BILLING CODE 3510-22-P
DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-BM11
50 CFR Part 217
[Docket No. 240605-0153]
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine
Mammals Incidental to the SouthCoast Wind Project Offshore Massachusetts
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Proposed rule; proposed letter of authorization; request for comments.
SUMMARY: NMFS received a request from SouthCoast Wind Energy LLC
(SouthCoast) (formerly Mayflower Wind Energy LLC), for Incidental Take Regulations
(ITR) and an associated Letter of Authorization (LOA) pursuant to the Marine Mammal
Protection Act (MMPA). The requested regulations would govern the authorization of
take, by Level A harassment and Level B harassment, of small numbers of marine
mammals over the course of five years (2027-2032) incidental to construction of the
SouthCoast Wind Project (SouthCoast Project) offshore of Massachusetts within the
Bureau of Ocean Energy Management (BOEM) Commercial Lease of Submerged Lands
for Renewable Energy Development on the Outer Continental Shelf (OCS) Lease Area
OCS–A 0521 (Lease Area) and associated Export Cable Corridors (ECCs). Specified
activities expected to result in incidental take are pile driving (impact and vibratory),
unexploded ordnance or munitions and explosives of concern (UXO/MEC) detonation,
and site assessment surveys using high-resolution geophysical (HRG) equipment. NMFS
requests comments on this proposed rule. NMFS will consider public comments prior to
making any final decision on the promulgation of the requested ITR and issuance of the

LOA; agency responses to public comments will be summarized in the final rule. The
regulations, if promulgated, would be effective April 1, 2027 through March 31, 2032.
DATES: Comments and information must be received no later than [INSERT DATE 30
DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER].
ADDRESSES: A plain language summary of this proposed rule is available at
https://www.regulations.gov/docket/ NOAA-NMFS-2024-0074. Submit all electronic
public comments via the Federal e- Portal. Visit https://www.regulations.gov and type
NOAA-NMFS-2024-0074 in the Rulemaking Search box. Click on the “Comment” icon,
complete the required fields, and enter or attach your comments.
Instructions: Comments sent by any other method, to any other address or
individual, or received after the end of the comment period, may not be considered by
NMFS. All comments received are a part of the public record and will generally be
posted for public viewing on https://www.regulations.gov without change. All personal
identifying information (e.g., name, address), confidential business information, or
otherwise sensitive information submitted voluntarily by the sender will be publicly
accessible. NMFS will accept anonymous comments (enter “N/A” in the required fields if
you wish to remain anonymous).
A copy of SouthCoast’s Incidental Take Authorization (ITA) application and
supporting documents, as well as a list of the references cited in this document, may be
obtained online at: https://www.fisheries.noaa.gov/national/marine-mammalprotection/incidental-take-authorizations-other-energy-activities-renewable. In case of
problems accessing these documents, please call the contact listed below (see FOR
FURTHER INFORMATION CONTACT)
FOR FURTHER INFORMATION CONTACT: Carter Esch, Office of Protected
Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:

Purpose and Need for Regulatory Action
This proposed rule, if promulgated, would provide a framework under the
authority of the MMPA (16 U.S.C. 1361 et seq.) to allow for the authorization of take of
marine mammals incidental to construction of the SouthCoast Project within the Lease
Area and along ECCs to landfall locations in Massachusetts. NMFS received a request
from SouthCoast for 5-year regulations and a LOA that would authorize take of
individuals of 16 species of marine mammals by harassment only (4 species by Level A
harassment and Level B harassment and 12 species by Level B harassment only)
incidental to SouthCoast’s construction activities. No mortality or serious injury is
anticipated or proposed for authorization. Please see the Legal Authority for the Proposed
Action section below for relevant definitions.
Legal Authority for the Proposed Action
The MMPA prohibits the “take” of marine mammals, with certain exceptions.
Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) direct the Secretary
of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not
intentional, taking of small numbers of marine mammals by U.S. citizens who engage in
a specified activity (other than commercial fishing) within a specified geographical
region if certain findings are made, regulations are promulgated, and public notice and an
opportunity for public comment are provided.
Authorization for incidental takings shall be granted if NMFS finds that the taking
will have a negligible impact on the species or stock(s) and will not have an unmitigable
adverse impact on the availability of the species or stock(s) for taking for subsistence
uses (where relevant). If such findings are made, NMFS must prescribe the permissible
methods of taking; other “means of effecting the least practicable adverse impact” on the
affected species or stocks and their habitat, paying particular attention to rookeries,
mating grounds, and areas of similar significance, and on the availability of the species or

stocks for taking for certain subsistence uses (referred to as “mitigation”); and
requirements pertaining to the monitoring and reporting of such takings.
As noted above, no serious injury or mortality is anticipated or proposed for
authorization in this proposed rule. Relevant definitions of MMPA statutory and
regulatory terms are included below:
●

U.S. Citizen - individual U.S. citizens or any corporation or similar entity

if it is organized under the laws of the United States or any governmental unit defined in
16 U.S.C. 1362(13); 50 CFR 216.103);
●

Take - to harass, hunt, capture, or kill, or attempt to harass, hunt, capture,

or kill any marine mammal (16 U.S.C. 1362(13); 50 CFR 216.3);
●

Incidental harassment, Incidental taking, and incidental, but not

intentional, taking - an accidental taking. This does not mean that the taking is
unexpected, but rather it includes those takings that are infrequent, unavoidable or
accidental (50 CFR 216.103);
●

Serious Injury - any injury that will likely result in mortality (50 CFR

●

Level A harassment - any act of pursuit, torment, or annoyance which has

216.3);

the potential to injure a marine mammal or marine mammal stock in the wild (16 U.S.C.
1362(18); 50 CFR 216.3); and
●

Level B harassment - any act of pursuit, torment, or annoyance which has

the potential to disturb a marine mammal or marine mammal stock in the wild by causing
disruption of behavioral patterns, including, but not limited to, migration, breathing,
nursing, breeding, feeding, or sheltering (16 U.S.C. 1362(18); 50 CFR 216.3).
Summary of Major Provisions within the Proposed Rule
The major provisions of this proposed rule are:

●

Allowing NMFS to authorize, under a LOA, the take of small numbers of

marine mammals by Level A harassment and/or Level B harassment incidental to the
SouthCoast Project and prohibiting take of such species or stocks in any manner not
permitted (e.g., mortality or serious injury);
●

Establishing a seasonal moratorium on foundation installation within 20

kilometers (km) (12.4 miles (mi)) of the 30-m isobath on the western side of Nantucket
Shoals which, for purposes of this proposed rule, is hereafter referred to as the North
Atlantic Right Whale Enhanced Mitigation Area (NARW EMA), from October 16 – May
31, annually;
●

Establishing a seasonal moratorium on foundation installation throughout

the rest of the Lease Area January 1 – May 15 and a restriction on foundation pile driving
in December unless Southcoast requests and NMFS approves piling driving in December,
which would require SouthCoast to implement enhanced mitigation and monitoring to
minimize impacts to North Atlantic right whales (Eubalaena glacialis);
●

Establishing enhanced North Atlantic right whale monitoring, clearance,

and shutdown procedures SouthCoast must implement in the NARW EMA August 1 –
October 15, and throughout the rest of the Lease Area May 16 – 31 and December 1 – 31;
●

Establishing a seasonal moratorium on the detonation of unexploded

ordnance or munitions and explosives of concern (UXO/MEC) December 1 – April 30 to
minimize impacts to North Atlantic right whales;
●

Requirements for UXO/MEC detonations to only occur if all other means

of removal are exhausted (i.e., As Low As Reasonably Practicable (ALARP) risk
mitigation procedure) and conducting UXO/MEC detonations during daylight hours only
and limiting detonations to 1 per 24 hour period;

●

Conducting both visual and passive acoustic monitoring (PAM) by

trained, NMFS-approved Protected Species Observers (PSOs) and PAM operators before,
during, and after select in-water construction activities;
●

Requiring training for all SouthCoast Project personnel to ensure marine

mammal protocols and procedures are understood;
●

Establishing clearance and shutdown zones for all in-water construction

activities to prevent or reduce the risk of Level A harassment and to minimize the risk of
Level B harassment, including a delay or shutdown of foundation impact pile driving and
delay to UXO/MEC detonation if a North Atlantic right whale is observed at any distance
by PSOs or acoustically detected within certain distances;
●

Establishing minimum visibility and PAM monitoring zones during

foundation impact pile driving and detonations of UXO/MECs;
●

Requiring use of a double bubble curtain during all foundation pile driving

installation activities and UXO/MEC detonations to reduce noise levels to those modeled
assuming a broadband 10 decibel (dB) attenuation;
●

Requiring sound field verification (SFV) monitoring during pile driving of

foundation piles and during UXO/MEC detonations to measure in situ noise levels for
comparison against the modeled results and ensure noise levels assuming 10 dB
attenuation are not exceeded;
●

Requiring SFV during the operational phase of the SouthCoast Project;

●

Implementing soft-starts during pile driving and ramp-up during the use of

high-resolution geophysical (HRG) marine site characterization survey equipment;
●

Requiring various vessel strike avoidance measures;

●

Requiring various measures during fisheries monitoring surveys, such as

immediately removing gear from the water if marine mammals are considered at-risk of
interacting with gear;

●

Requiring regular and situational reporting, including, but not limited to,

information regarding activities occurring, marine mammal observations and acoustic
detections, and sound field verification monitoring results; and
●

Requiring monitoring of the North Atlantic right whale sighting networks,

Channel 16, and PAM data as well as reporting any sightings to NMFS.
Through adaptive management, NMFS Office of Protected Resources may
modify (e.g., remove, revise, or add to) the existing mitigation, monitoring, or reporting
measures summarized above and required by the LOA.
NMFS must withdraw or suspend an LOA issued under these regulations, after
notice and opportunity for public comment, if it finds the methods of taking or the
mitigation, monitoring, or reporting measures are not being substantially complied with
(16 U.S.C. 1371(a)(5)(B); 50 CFR 216.106(e)). Additionally, failure to comply with the
requirements of the LOA may result in civil monetary penalties and knowing violations
may result in criminal penalties (16 U.S.C. 1375; 50 CFR 216.106(g)).
National Environmental Policy Act (NEPA)
On February 15, 2021, SouthCoast submitted a Construction and Operations Plan
(COP) to BOEM for approval to construct and operate the SouthCoast Project, which has
been updated several times since, as recently as September 2023. On November 1, 2021,
BOEM published in the Federal Register a Notice of Intent (NOI) to prepare an
Environmental Impact Statement (EIS) for the COP (86 FR 60270). On February 17,
2023, BOEM published and made its SouthCoast Draft Environmental Impact Statement
(DEIS) for Commercial Wind Lease OCS-A 0521 available for public comment for 45
days, February 17, 2023 to April 3, 2023 (88 FR 10377). On April 4, 2023, BOEM
extended the public comment period by 15 days through April 18, 2023 (88 FR 19986).
Additionally, BOEM held three virtual public hearings on March 20, March 22, and
March 27, 2023.

To comply with the National Environmental Policy Act of 1969 (NEPA; 42
U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, NMFS must
evaluate the potential impacts on the human environment of the proposed action (i.e.,
promulgating the regulations and subsequently issuing a 5-year LOA to SouthCoast) and
alternatives to that action. Accordingly, NMFS is a cooperating agency on BOEM’s
Environmental Impact Statement (EIS) and proposes to adopt the EIS, provided our
independent evaluation of the document finds that it includes adequate information
analyzing the effects on the human environment of promulgating the proposed
regulations and issuing the LOA.
Information in the SouthCoast ITA application, this proposed rule, and the BOEM
EIS mentioned above collectively provide the environmental information related to
proposed promulgation of these regulations and associated LOA for public review and
comment. NMFS will review all comments submitted in response to this proposed
rulemaking prior to concluding the NEPA process or making a final decision on the
request for an ITA.
Fixing America’s Surface Transportation Act (FAST-41)
The SouthCoast Project is covered under Title 41 of the Fixing America’s Surface
Transportation Act, or “FAST-41.” FAST-41 includes a suite of provisions designed to
expedite the environmental review for covered infrastructure projects, including
enhanced interagency coordination as well as milestone tracking on the public-facing
Permitting Dashboard. FAST-41 also places a 2-year limitations period on any judicial
claim that challenges the validity of a Federal agency decision to issue or deny an
authorization for a FAST-41 covered project. 42 U.S.C. § 4370m-6(a)(1)(A).
SouthCoast’s proposed project is listed on the Permitting Dashboard, where
milestones and schedules related to the environmental review and permitting for the

project can be found: https://www.permits.performance.gov/permittingproject/southcoast-wind-energy-llc-southcoast-wind.
Summary of Request
On March 18, 2022, Mayflower Wind Energy LLC (Mayflower Wind) submitted
a request for the promulgation of regulations and issuance of an associated 5-year LOA to
take marine mammals incidental to construction activities associated with the Mayflower
Wind Project offshore of Massachusetts in the Lease Area OCS-A-0521. On February 1,
2023, Mayflower Wind notified NMFS that it changed its company name and project
name to SouthCoast Wind Energy LLC and SouthCoast Wind Project, respectively.
SouthCoast’s request is for the incidental, but not intentional, taking of a small number of
16 marine mammal species (comprising 16 stocks) by Level B harassment (for all 16
species or stocks) and by Level A harassment (for four species or stocks). No serious
injury or mortality is expected to result from the specified activities, nor is any proposed
for authorization.
In response to our questions and comments and following extensive information
exchange between SouthCoast and NMFS, SouthCoast submitted revised applications on
April 23, June 24, and August 16, 2022, and a final revised application on September 14,
2022, which NMFS deemed adequate and complete on September 19, 2022. On October
17, 2022, NMFS published a notice of receipt (NOR) of SouthCoast’s adequate and
complete application in the Federal Register (87 FR 62793), requesting comments and
soliciting information related to SouthCoast’s request during a 30-day public comment
period. During the NOR public comment period, NMFS received comment letters from
one member of the public, Seafreeze, Ltd, and two environmental non-governmental
organizations: Conservation Law Foundation and Oceana. NMFS has reviewed all
submitted material and has taken the material into consideration during the drafting of
this proposed rule.

Following publication of the NOR (87 FR 62793, October 17, 2022), NMFS
further assessed potential impacts of SouthCoast’s proposed activities on North Atlantic
right whales that utilize foraging habitat within and near the Lease Area and consulted
with SouthCoast to develop enhanced mitigation and monitoring measures that would
reduce the likelihood of these potential impacts. On March 15, 2024, following extensive
information exchange, SouthCoast submitted a North Atlantic Right Whale Enhanced
Mitigation Plan and Monitoring Plan and revised application on March 15, 2024, which
NMFS accepted on March 19, 2024.
NMFS previously issued two Incidental Harassment Authorizations (IHAs) to
Mayflower Wind and one IHA to SouthCoast Wind authorizing the taking of marine
mammals incidental to marine site characterization surveys (using HRG equipment) of
SouthCoast’s Lease Area (OCS-A 0521) (see 85 FR 45578, July 29, 2020; 86 FR 38033,
July 19, 2021; 88 FR 31678, May 18, 2023). To date, SouthCoast has complied with all
IHA requirements (e.g., mitigation, monitoring, and reporting). Information regarding
SouthCoast’s monitoring results, which were utilized in take estimation, may be found in
the Estimated Take section, and the full monitoring reports can be found on NMFS’
website: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidentaltake-authorizations-other-energy-activities-renewable.
On August 1, 2022, NMFS announced proposed changes to the existing North
Atlantic right whale vessel speed regulations to further reduce the likelihood of
mortalities and serious injuries to endangered right whales from vessel collisions, which
are a leading cause of the species' decline and a primary factor in an ongoing Unusual
Mortality Event (87 FR 46921). Should a final vessel speed rule be promulgated and
become effective during the effective period of these proposed regulations (or any other
MMPA incidental take authorization), the authorization holder would be required to
comply with any and all applicable requirements contained within such final vessel speed

rule. Specifically, where measures in any final vessel speed rule are more protective or
restrictive than those in this or any other MMPA authorization, authorization holders
would be required to comply with the requirements of such rule. Alternatively, where
measures in this or any other MMPA authorization are more restrictive or protective than
those in any final vessel speed rule, the measures in the MMPA authorization would
remain in place. The responsibility to comply with the applicable requirements of any
vessel speed rule would become effective immediately upon the effective date of any
final vessel speed rule and, when notice is published of the effective date, NMFS would
also notify SouthCoast if the measures in such speed rule were to supercede any of the
measures in the MMPA authorization.
Description of the Specified Activities
Overview
SouthCoast has proposed to construct and operate an up to 2,400 megawatt (MW)
offshore wind energy facility (SouthCoast Project) in state and Federal waters in the
Atlantic Ocean in Lease Area OCS-A-0521. This lease area is located within the
Massachusetts Wind Energy Area (MA WEA), 26 nautical miles (nm, 48 km) south of
Martha’s Vineyard and 20 nm (37 km) south of Nantucket, Massachusetts. Development
of the offshore wind energy facility would be divided into two projects, each of which
would be developed in separate years. Project 1 and Project 2 would occupy the
northeastern and southwestern halves (approximately) of the Lease Area, respectively.
Each Project would have the potential to generate approximately 1,200 MW of renewable
energy. Once operational, SouthCoast would allow the State of Massachusetts to advance
Federal and State offshore wind targets as well as reduce greenhouse gas emissions,
increase grid reliability, and support economic development and growth in the region.
The SouthCoast Project would consist of several different types of permanent
offshore infrastructure: wind turbine generators (WTGs), offshore substation platforms

(OSPs), associated WTG and OSP foundations, inter-array and ECCs, and offshore
cabling. Onshore substation and converter stations, onshore interconnection routes, and
operations and maintenance (O&M) facilities are also planned. There are 149 positions in
OSP foundations (totaling no more than 149) would be installed. The number of WTG
foundations installed would vary by project. SouthCoast has not yet determined the exact
number of OSPs necessary to support each project, but the total across projects would not
exceed five. Project 1 would include up to 85 WTG foundations, and Project 2 would
include up to 73 WTG foundations for a maximum of 147 WTG foundations for both
Project 1 and Project 2. Project 1 foundations would be installed in two distinct areas.
Subject to extensive mitigation, including extended seasonal restrictions and monitoring,
SouthCoast would install up to 54 foundations within the NARW EMA, defined as the
northeastern portion of the lease area within 20 km (9.3 mi) of the 30-m (98.4 ft) isobath
along the western side of Nantucket Shoals (see Figure 2 in the Specified Geographical
Area section for more detail). The remaining foundations for Project 1 (out of a
maximum of 85) would be installed in positions immediately southwest of the NARW
EMA.
SouthCoast is considering three foundation types for WTGs and OSPs:
monopile, piled jacket, and suction-bucket jacket. SouthCoast would install up to two
different foundation types for WTGs (i.e., piled jacket and monopiles), and potentially
a third concept for OSPs (e.g., suction bucket jacket). However, due to economic and
technical infeasibility, suction-bucket jackets are no longer under consideration for
Project 1. Geotechnical investigations at Project 2 foundation locations are ongoing,
and SouthCoast will need to assess the data to determine whether it would be feasible
to install suction-bucket jacket foundations, rather than monopile or jacket foundations.
However, due to predicted installation complexities, this is not the preferred foundation

type. If suction bucket foundations are selected for Project 2, pile driving would not be
necessary.
SouthCoast is considering multiple installation scenarios for each project,
which differ by foundation type and number, and installation method. For Project 1,
SouthCoast plans to install either all monopile WTG (Project 1, Scenario 1; P1S1: 71
WTGs) or pin-piled jacket (Project 1, Scenario 2; P1S2: 85 WTGs) foundations by
impact pile driving only. For Project 2, unless suction bucket jackets are selected as the
preferred type, foundation installation would also include either all monopile or all
piled jacket WTG foundations, which would be installed using impact pile driving only
(Project 2, Scenario 1; P2S1: 68 WTGs) or a combination of vibratory and impact
(Project 2, Scenario 2; P2S2, 73 WTGs; Project 2 Scenario 3; P2S3 62 WTGs) pile
driving. Each WTG and OSP would be supported by a single foundation. OSP
monopile or piled jacket foundations would be installed using only impact pile driving.
SouthCoast is considering three OSP designs: modular, integrated, and DC-converter.
Should they elect to install piled jacket foundations to support OSPs, the number of
jacket legs and pin piles would vary depending on the OSP design. SouthCoast
currently identifies installation of one DC-converter OSP per project, each supported
by a piled jacket foundation, as the most realistic scenario.
Inter-array cables will transmit electricity from the WTGs to the OSP. Export
cables would transmit electricity from each OSP to a landfall site. All offshore cables
will connect to onshore export cables, substations, and grid connections, which would
be located at landfall locations. SouthCoast is proposing to develop one preferred ECC
for both Project 1 and Project 2, making landfall and interconnecting to the ISO New
England Inc. (ISO-NE) grid at Brayton Point, in Somerset, Massachusetts (i.e., the
Brayton Point Export Cable Corridor (Brayton Point ECC)). For Project 2, SouthCoast
is proposing an alternative export cable corridor which, if utilized, would make landfall

and interconnect to the ISO-NE grid in the town of Falmouth, MA (the Falmouth ECC)
in the event that technical, logistical, grid interconnection, or other unforeseen
challenges arise during the design and engineering phase that prevent Project 2 from
making interconnection at Brayton Point.
Specified activities would also include temporary installation of up to four
nearshore gravity-based structures (e.g., gravity cell or gravity-based cofferdam) and/or
dredged exit pits to connect the offshore export cables to onshore facilities; vessel-based
site characterization and assessment surveys using high-resolution geophysical active
acoustic sources with frequencies of less than 180 kilohertz (kHz) (HRG surveys);
detonation of up to 10 unexploded ordnances or Munitions and Explosives of Concern
(UXO/MEC) of different charge weights; several types of fishery and ecological
monitoring surveys; site preparation work (e.g., boulder removal); the placement of scour
protected; trenching, laying, and burial activities associated with the installation of the
export cable from OSPs to shore-based switching and substations and inter-array cables
between turbines; transit within the Lease Area and between ports and the Lease Area to
transport crew, supplies, and materials to support pile installation via vessels; and WTG
operation.
Based on the current project schedule, SouthCoast anticipates WTGs would
become operational for Project 1 beginning in approximately Q2 2029 and Project 2 by
Q4 2031, after installation is completed and all necessary components, such as array
cables, OSPs, ECCs, and onshore substations are installed. Turbines would be
commissioned individually by personnel on location, so the number of commissioning
teams would dictate how quickly turbines would become operational. SouthCoast expects
that all turbines will be commissioned by Q4 2031.
Marine mammals exposed to elevated noise levels during impact and vibratory
pile driving during foundation installation, detonations of UXO/MECs, or HRG surveys

may be taken by Level A harassment and/or Level B harassment depending on the
specified activity. No serious injury or mortality is anticipated or proposed for
authorization.
Dates and Duration
The specified activities would occur over approximately 6 years, starting in the
fourth quarter of 2026 and continuing through the end of 2031. SouthCoast anticipates
that the specified activities with the potential to result in take by harassment of marine
mammals would begin in the second quarter of 2027 and occur throughout all 5 years
of the proposed regulations which, if issued, would be effective from April 1, 2027March 31, 2032.
The general schedule provided in table 1 includes all of the major project
components, including those that may result in harassment of marine mammals (i.e.,
foundation installation, HRG surveys, and UXO/MEC detonation) and those that are
not expected to do so (shown in italics). Projects 1 and 2 will be developed in separate
years, which may not be consecutive. To allow flexibility in the final design and during
the construction period, SouthCoast has not identified specific years in which each
Project would be installed.
Table 1 – Estimated Activity Schedule to Construct and Operate the SouthCoast
Project
Specified Activity

Estimated Schedule

Activity Timing

HRG Surveys

Q2 2027- Q3 2031

Any time of the year, up to 112.5
days per year during construction
of Project 1 and Project 2, and up
to 75 days per year during nonconstruction years

Scour Protection Pre- or PostInstallation

Q1 2027-Q3 2029

Any time of the year

WTG and OSP Foundation
Installation, Project 1

Q2-Q4 2028 or Q2-Q4 20291,2

Approximately 6 months

WTG and OSP Foundation
Installation, Project 2

Q2-Q4 20301, 2, 3

Approximately 6 months

Horizontal Directional Drilling
at Cable Landfall Sites

Project 1 Q4 2026-Q1 2027
Project 2 Q4 2029-Q1 2030

Approximately 6 months per
project

UXO/MEC Detonations

Q2-Q4 2028, 2029, and 20304

Up to 5 days for Project 1 and up
to 5 days for Project 2. No more
than 10 days total

Inter-array Cable Installation

Project 1: 2028-2029
Project 2: 2029-2030

Project 1: up to 16 months
Project 2: up to 12 months

Export Cable Installation and
Termination

Project 1: 2027-2029
Project 2: 2029–2030

Project 1: up to 30 months
Project 2: up to 12 months

Fishery Monitoring Surveys

Before, during, and after
construction of Projects 1 and 2

Any time of year

Turbine Installation and
Operation

Initial turbines operational 2030, all turbines operational by 2032

1 – SouthCoast does not currently know in which of these years Project 1 and Project 2 construction would
occur but estimates that each Project would be completed in a single year (2 years total).
2 – NMFS is proposing seasonal restriction mitigation measures that would limit pile driving to June 1
through October 15 in the NARW EMA and May 16 through December 31 in the rest of the Lease Area
(although proposing requiring NMFS’ prior approval to install foundations in December).
3 – Should SouthCoast decide to install suction bucket foundations for Project 2, installation would occur
Q2 2030-Q2 2031. This activity would not be seasonally restricted because installation of this foundation
type does not require pile driving.
4 – NMFS is proposing seasonal restriction mitigation measures UXO/MEC detonations from December 1
through April 30.
5 – Activities in italics are not expected to result in incidental take of marine mammals.

Specific Geographical Region
Most of SouthCoast’s specified activities would occur in the Northeast U.S.
Continental Shelf Large Marine Ecosystem (NES LME), an area of approximately
260,000 km2 (64,247,399.2 acres), spanning from Cape Hatteras in the south to the Gulf
of Maine in the north. More specifically, the Lease Area and ECC would be located
within the Mid-Atlantic Bight subarea of the NES LME, which extends between Cape
Hatteras, North Carolina, and Martha’s Vineyard, Massachusetts, and eastward into the
Atlantic to the 100-m (328.1 ft) isobath.
The Lease Area and ECCs are located within the Southern New England (SNE)
sub-region of the Northeast U.S. Shelf Ecosystem, at the northernmost end of the MidAtlantic Bight (MAB), which is distinct from other regions based on differences in
productivity, species assemblages and structure, and habitat features (Cook and Auster,
2007). Weather-driven surface currents, tidal mixing, and estuarine outflow all contribute

to driving water movement through the area (Kaplan, 2011), which is subjected to highly
seasonal variation in temperature, stratification, and productivity. The Lease Area, OCSA 0521, is part of the Massachusetts Wind Energy Area (MA WEA) (3,007 square
kilometers (km2) (742,974 acres)) (Figure 1). Within the MA WEA, the Lease Area
covers approximately 516 km2 (127, 388 acres) and is located approximately 30 statute
miles (mi) (26 nm; 48 km) south of Martha’s Vineyard, Massachusetts, and
approximately 23 mi (20 nm, 37 km) south of Nantucket, Massachusetts. At its closest
point to land, the Lease Area is approximately 45 mi (39 nm, 72 km) south from the
mainland at Nobska Point in Falmouth, Massachusetts.
During construction, the Project will require support from temporary construction
laydown yard(s) and construction port(s). The operational phase of the Project will
require support from onshore O&M facilities. While a final decision has not yet been
made, SouthCoast will likely use more than one marshalling port for the SouthCoast
Project. The following ports are under consideration: New Bedford, MA; Fall River, MA;
South Quay, RI; Salem Harbor, MA; Port of New London, CT; Port of Charleston, SC;
Port of Davisville, RI; Sparrows Point Port, Maryland; and Sheet Harbor, Canada.

Figure 1 – SouthCoast Project Location

The Brayton Point ECC and the Falmouth ECC would traverse Federal and state
territorial waters of Massachusetts and Rhode Island, making landfall at Brayton Point in
Somerset, Massachusetts or at Falmouth, Massachusetts, respectively. Within the Brayton
Point ECC, up to six submarine offshore export cables, including up to four power cables
and up to two dedicated communications cables, would be installed from one or more
OSPs within the lease area in Federal waters and run through the Sakonnet River, make
intermediate landfall on Aquidneck Island in Portsmouth, Rhode Island, which includes
an underground onshore export cable route, and then into Mount Hope Bay to make
landfall at Brayton Point in Somerset, Massachusetts. Within the Falmouth export cable
corridor, up to five submarine offshore export cables, including up to four power cables
and up to one dedicated communications cable, would be installed from one or more
OSPs within the Lease Area and run through Muskeget Channel into Nantucket Sound in
Massachusetts state waters to make landfall in Falmouth, Massachusetts.
As described in further detail below, SouthCoast proposed mitigation and
monitoring measures that would apply throughout the Lease Area, as well as enhanced
measures applicable to a portion of the Lease Area that overlaps with the NARW EMA.
The 30-m (98.4 ft)) isobath represents bathymetry defining the edge of Nantucket Shoals
and corresponds with the predicted location of tidal mixing fronts in this region (Simpson
and Hunter, 1974; Wilkin, 2006) and observations of high productivity and North
Atlantic right whale foraging (Leiter et al., 2017; White et al., 2020).

Figure 2 – Map of Foundation Locations in the SouthCoast Lease Area, Including Those in Project 1 (Black and White
Circles), Project 2 (Gray Circles), and Inside the NARW EMA (Black Circles).

Water depths in the project area (which includes the lease area, cable corridors,
vessel transit lanes and ensonified area above NMFS thresholds) span from less than 1
meter ((m); 3.28 feet (ft)), near the landfall sites, to approximately 64 m at the deepest
location in the lease area. Water depths in the lease area, in relation to Mean Lower Low
Water (MLLW), range from approximately 37.1 to 63.5 m (121.7 – 208.3 ft). Of the 149
foundation locations, 101 are located in waters depths less than 54 m (177 ft) and the
remaining 48 are located in water depths from 54 – 64 m (177 – 210 ft). Water depths
along the Brayton Point and Falmouth ECCs range from 0 – 41.5 m (0 – 136.2 ft)
MLLW. The cable landfall construction areas would be approximately 2.0 – 10.0 m (6.6
– 32.8 ft) deep in Somerset and 5.0 to 8.0 m (16.4 – 26.3 ft) deep in Falmouth.
Geological conditions in the project area, including sediment composition, are the
result of glacial processes. The pattern of sediment distribution in the Mid-Atlantic Bight
is relatively simple. The continental shelf south of New England is broad and flat,
dominated by fine-grained sediments. Sediment composition is primarily dominated by
sand, but varies by location, comprising various sand grain sizes sand to silt. Seafloor
conditions in the Lease Area align with the findings at nearby locations in the RI/MA and
MA WEAs showing little relief and low complexity (i.e., mostly homogeneous) (section
6.6.1.6.1, SouthCoast Wind COP, 2024; Epsilon, 2018). Data collected as part of
SouthCoast’s benthic surveys indicate varying levels of surficial sediment mobility
throughout the Lease Area and ECCs, evidenced by the ubiquitous presence of bedforms
(ripples), both large and small. The deeper shelf waters of the Lease Area and ECCs are
characterized by predominantly rippled sand and soft bottoms. Where the Falmouth ECC
would enter Muskeget Channel and Nantucket Sound, the surface sediments become
coarser sand with gravel and hard bottoms. The coarser sediments represent reworked
glacial materials. No large-scale seabed topographic features or bedforms were found
within the Lease Area (SouthCoast Wind COP, 2024). Moraine deposits related to the

formation of Martha’s Vineyard and Nantucket Island have resulted in boulder fields
along portions of both ECCs (Baldwin et al., 2016; Oldale, 1980). The Brayton Point
ECC also crosses moraine features represented by the Southwest Shoal off Martha’s
Vineyard and Browns Ledge off the Elizabeth Island in Rhode Island Sound (section 3.1,
SouthCoast Wind COP, 2024).
The species that inhabit the benthic habitats of the Lease Area and OCS are
typically described as infaunal species, those living in the sediments (e.g., polychaetes,
amphipods, mollusks), and epifaunal species, those living on the seafloor surface
(mobile, e.g., sea starts, sand dollars, sand shrimp) or attached to substrates (sessile
organisms; e.g., barnacles, anemones, tunicates). These organisms are important food
sources for several commercially important northern groundfish species.
The SouthCoast Lease Area is located adjacent to Nantucket Shoals, a broad
shallow and sandy shelf that extends southeast of Nantucket Island. Waters from the Gulf
of Maine, the Great South Channel, and Nantucket Sound converge in this area, creating
a well-mixed water column throughout the year (Limeburner and Beardsley, 1982).
The shoals area has an underwater dunelike topography and strong tidal currents
(PCCS, 2005). Surface currents become stronger during the spring and summer as
heating and stratification increase (Brookes, 1992; PCCS, 2005). Due to wind and tidal
mixing, a persistent tidal front occurs along the western edge of Nantucket Shoals, (Chen
et al., 1994a; b). This frontal region typically spans approximately 10-20 km (6.2-12.4
mi) (Potter and Lough, 1987; Lough and Manning, 2001; Ullman and Cornillon, 2001;
White and Veit, 2020), with its strength and cross-isobath flow potentially influenced by
regional winds (Ullman and Cornillon, 2001). The estimated location of this front varies
from the 50-m (164-ft) isobath to inshore of the 30-m (98.4-ft) isobath (Ullman and
Cornillon, 2001; Wilkin, 2006).

The ecology of the Nantucket Shoals region is unique in that it supports recurring
enhanced aggregations of zooplankton that provide prey for North Atlantic right whales
and other species migrating to the region to forage (Quintana-Rizzo et al., 2021). The
region is characterized by complex hydrodynamics and ecology. The hydrodynamics of
this region result from processes at variable spatial scales that extend from oceanic (Gulf
Stream warm core rings) to local (tidal mixing) and timescales of seasonal (stratification)
to decadal (National Academy of Sciences (NAS), 2023). The physical oceanographic
and bathymetric features (i.e., shallow, well-lit, well-mixed) provide for year-round high
phytoplankton biomass. Strong tidal currents create thorough mixing of the water
column, distributing nutrients, which enhances and concentrates productivity of
phytoplankton and zooplankton (PCCS, 2005; White et al., 2020). High productivity in
the area is also stimulated by a local tidal pump generated by the tidal dissipation
between Nantucket Sound and the shoals so significantly that this tidal pump creates one
of the largest tidal dispensation areas in New England (Chen et al., 2018; Quintana-Rizzo
et al., 2021). Hydrographic features, such as circulation patterns and tides, result in the
flow of zooplankton into area from source regions outside, rather than increased primary
productivity due to upwelling (Kenney and Wishner, 1995; PCCS, 2005). The persistent
frontal zone on the western side of Nantucket Shoals, with an estimated location that
varies from the 50-m isobath to inshore of the 30-m (98.4-ft) isobath (Ullman and
Cornillon, 2001; Wilkin, 2006), aggregates zooplankton prey whose distributions are
dependent on hydrodynamics and frontal features (White et al., 2020). These
aggregations not only draw North Atlantic right whales but also other marine vertebrates
that forage on the resulting dense prey patches, such as schooling fish and sea ducks and
white-winged scooters (Scales et al., 2014; White et al., 2020). The frontal zone is also
associated with a wide diversity of mollusk, crustacean, and echinoderm species, as well

as surf clams, quahogs, and “intense winter aggregations” of Gammarid amphipods
(White et al., 2020).
Detailed Description of Specified Activities
Below, we provide detailed descriptions of SouthCoast’s specified activities,
explicitly noting those that are anticipated to result in the take of marine mammals and
for which incidental take authorization is requested. Additionally, a brief explanation is
provided for those activities that are not expected to result in the take of marine
mammals. For more information beyond that provided here, see SouthCoast’s ITA
application.
WTG and OSP Foundation Installation
SouthCoast proposes to install a maximum of 149 foundations composed of a
combination of up to 147 WTG and up to 5 OSP foundations, conforming to spacing on a
1 nm x 1 nm (1.9 km x 1.9 km) grid layout, oriented east-west and north-south).
SouthCoast would be restricted from pile driving in the NARW EMA from October 16
through May 31 and January 1 through May 15 in the remainder of the Lease Area.
SouthCoast should avoid pile driving in December (i.e., it should not be planned), and it
may only occur with prior approval by NMFS and implementation of enhanced
mitigation and monitoring measures. SouthCoast must notify NMFS in writing by
September 1 of that year, indicating that circumstances are expected to necessitate pile
driving in December.
Project 1 would include installation of up to 86 foundations (85 WTG, 1 OSP),
including 54 foundations located within the NARW EMA and up to 32 foundations
immediately to the southwest of the NARW EMA. Foundation installation would begin
in the northeast portion of the Project 1 area (Figure 2) no earlier than June 1, 2028, given
NMFS’ proposed pile driving seasonal restriction. By installing foundations in this
portion of the Project 1 area first (beginning June 1), SouthCoast would begin conducting

work closest to Nantucket Shoals and then progressing towards the southwest and
moving away from Nantucket Shoals. SouthCoast would complete foundation
installations in the NARW EMA by October 15, prior to when North Atlantic right whale
occurrence is expected to begin increasing in eastern southern New England (e.g., Davis
et al., 2024). The number of WTG foundations available for Project 2 depends on the
final footprint for Project 1, but the combined number for both projects would not exceed
147. SouthCoast would install Project 2 foundations in the portion of the Lease Area
southwest of Project 1.
SouthCoast would install foundations using impact pile driving only for Project 1
and a combination of impact and vibratory pile driving for Project 2. Vibratory setting, a
technique wherein the pile is initially installed with a vibratory hammer until an impact
hammer is needed, is particularly useful when soft seabed sediments, such as those
previously described for SouthCoast’s project area in the Specified Geographic Region
section, are not sufficiently stiff to support the weight of the pile during the initial
installation, increasing the risk of ‘pile run’ (i.e., where a pile sinks rapidly through
seabed sediments). Piles subject to pile run can be difficult to recover and pose
significant safety risks to the personnel and equipment on the construction vessel. The
vibratory hammer mitigates this risk by forming a hard connection to the pile using
hydraulic clamps, thereby acting as a lifting/handling tool as well as a vibratory hammer.
The tool is inserted into the pile on the construction vessel deck, and the connection
made. The pile is then lifted, upended, and lowered into position on the seabed using the
vessel crane. After the pile is lowered into position, vibratory pile installation will
commence, whereby piles are driven into soil using a longitudinal vibration motion. The
vibratory hammer installation method can continue until the pile is inserted to a depth
that is sufficient to fully support the structure, and then the impact hammer can be
positioned and operated to complete the pile installation. This can be accomplished using

a single installation vessel equipped with both hammer types or two separate vessels,
each equipped with either the vibratory or impact hammer.
For each Project, SouthCoast expects to install foundations within a 6-month
period each year for two years. However, it is possible that foundation installation could
continue into a second year for either Project, depending on construction logistics and
local and environmental conditions that may influence SouthCoast’s ability to maintain
the planned construction schedule. Regardless of shifts in the construction schedule, the
seasonal restrictions on pile driving would apply.
SouthCoast has proposed to initiate pile driving any time of day or night. Once
construction begins, SouthCoast would proceed as rapidly as possible while
implementing all required mitigation and monitoring measures, to reduce the total
duration of construction. NMFS acknowledges the benefits of completing construction
quickly during times when North Atlantic right whales are unlikely to be in the area but
also recognizes challenges associated with monitoring during reduced visibility
conditions, such as at night. SouthCoast is currently conducting a review of available,
systematically collected data on the efficacy of technology to monitor (visually and
acoustically) marine mammals during nighttime and in reduced visibility conditions
during daytime. Should SouthCoast submit, and NMFS approve, an Alternative
Monitoring Plan (which includes nighttime pile driving monitoring), pile driving may be
initiated at night.
While the majority of foundation installations would be sequential (i.e., one at a
time), SouthCoast proposed concurrent pile driving (i.e., two installation vessels
installing foundations at the same time) for a small number of foundations, limited to the
few days on which both OSP and WTG foundations are installed simultaneously. Using a
single installation vessel, SouthCoast anticipates that a maximum of two monopile
foundations could be sequentially driven into the seabed per day, assuming 24-hour pile

driving operations; however, installation of one monopile per day is expected to be more
common and the installation schedule assumed for the take estimation analyses reflects
this (table 2). For jacket foundation installation, SouthCoast estimates that no more than
four pin piles (supporting one jacket foundation) could be installed per 24 hours on days
limited to sequential installation. SouthCoast anticipates that, on days with concurrent
pile driving using two installation vessels, up to 1) two WTG monopiles or four WTG pin
piles (by one installation vessel) and 2) four OSP pin piles (by a second vessel, working
simultaneously) could be installed in 24 hours.
As described previously, SouthCoast is considering several foundation options.
For Project 1, SouthCoast is considering installation of two types of WTG foundations,
monopile or pin-piled jacket, which would be installed by impact pile driving only.
SouthCoast is also considering these foundation types for Project 2 but may use a
combination of vibratory and/or impact pile driving for their installation. Finally, suctionbucket jacket foundations may provide an alternative to monopile and pin-piled jacket
foundations to support WTGs for Project 2. However, installing this third foundation type
does not require impact or vibratory pile driving, and it is not anticipated to result in
noise levels that would cause harassment to marine mammals. Therefore, suction-bucket
jacket foundations are not discussed further beyond the brief explanation below.
Although considering three foundation types for Projects 1 and 2, for the
purposes of estimating the maximum impacts to marine mammals that could occur
incidental to WTG and OSP foundation installation, SouthCoast assumed WTGs would
be supported by monopile or pin-piled jacket foundations and that OSPs would be
supported by pin-piled jacket foundations. For both Project 1 and Project 2 acoustic and
exposure modeling of the potential acoustic impacts resulting from installation of
monopiles and pin piles (see Estimated Take section), SouthCoast proposed multiple
WTG and OSP foundation installation scenarios for Projects 1 and 2, distinguished by

foundation type and number, installation method (i.e., impact only; vibratory and impact
pile driving), order (i.e., sequential or concurrent) and construction schedule (table 2).
Table 2 – Potential Installation Scenarios for Project 1 and Project 21
Project 1 (IMPACT ONLY)
Number of Piles
Installation
Order and
Method

9/16-m
monopile
1/day

9/16-m
monopile
2/day

4.5-m pin
4.5-m pin
piles WTG
piled OSP
jacket piles
jacket 4/day
4/day

Total foundations

Total days

Project 1 Scenario 1 (P1S1)
Sequential
(IMPACT)

24

--

--

Concurrent
(IMPACT)

--

--

71 WTG

1 OSP

85 WTG

1 OSP

Project 1 Scenario 2 (P1S2)
Sequential
(IMPACT)
Concurrent
(IMPACT)





324
-85

Project 2 (VIBE AND/OR IMPACT)
Project 2 Scenario 1 (P2S1)
Sequential
(IMPACT)

30

--

--

Concurrent
(IMPACT)

--

--

68 WTG

1 OSP

73 WTG

1 OSP

62 WTG

1 OSP

Project 2 Scenario 2 (P2S2)
Sequential
(IMPACT)

--

--

--

Sequential
(VIBE+IM
PACT)

48

--

--

Concurrent
(IMPACT)

--

--

Project 2 Scenario 3 (P2S3)
Sequential
(IMPACT)

--

--

--

Sequential
(VIBE+IM
PACT)

--

--

--

Concurrent
(IMPACT)

--

--

16

1 - Installation schedules vary based on foundation type (WTG monopile or pin-piled jacket, OSP pin-piled
jacket) and number, installation method (impact, or combination of vibratory and impact), and installation

order (sequential or concurrent).

As described previously, SouthCoast considered two WTG foundation installation
scenarios for Project 1 and one scenario for Project 2 that would employ impact pile
driving only (I), and two scenarios for Project 2 that would require a combination of
vibratory and impact pile driving (V/I):
● Project 1
â—‹ Scenario 1 (I): 71 monopile WTG, 1 pin-piled jacket OSP
â—‹ Scenario 2 (I): 85 pin-piled jacket WTG, 1 pin-piled jacket OSP
● Project 2
â—‹ Scenario 1 (I): 68 monopile WTG, 1 pin-piled jacket OSP
â—‹ Scenario 2 (V/I): 73 monopile WTG, 1 pin-piled jacket OSP
â—‹ Scenario 3 (V/I): 62 pin-piled jacket WTG, 1 pin-piled jacket OSP
For each Project, only one scenario would be implemented. For example,
SouthCoast could choose to install Scenario 1 for Project 1 (P1S1; 71 monopile WTG
foundations, 1 pin-piled jacket OSP foundation) and Scenario 1 for Project 2 (P2S1; 68
monopile WTG foundations, 1 pin-piled jacket OSP foundation) for a total of 139 WTG
monopile and 2 OSP pin-piled jacket foundations, or 141 foundations overall (table 2).
Alternatively, SouthCoast could install Scenario 2 for Project 1 (P1S2; 85 WTG pin-piled
jacket foundations, and 1 OSP pin-piled jacket) and Scenario 3 for Project 2 (P2S3; 62
pin-piled jacket foundation, 1 pin-piled jacket OSP foundation), for a total of 147 WTG
and 2 OSP foundations (or 149 foundations overall). Both of these combinations fall
within SouthCoast’s PDE, which specifies that SouthCoast would install no more than up
to 147 WTG foundations and up to 5 OSP foundations. Given this limitation, there are
Project 2 scenarios that can not be combined with scenarios for Project 1 because the
total WTG foundation number would exceed 147 (i.e., the total number of WTG
foundations would be 153 should SouthCoast combine the Project 1 Scenario 2 (85 pin-

piled jacket WTG foundations) with Project 2 Scenario 1 (68 monopile WTG
foundations) or 158 if combined with Project 2 Scenario 2). Thus, SouthCoast’s selection
of a scenario for Project 2 will depend on their scenario choice for Project 1.
WTG foundations
Monopile
SouthCoast proposed three scenarios that include monopile installations to
support WTGs. A monopile foundation normally consists of a single steel tubular section
with several sections of rolled steel plate welded together. Secondary structures on each
WTG monopile foundation would include a boat landing or alternative means of safe
access, ladders, a crane, and other ancillary components. Figure 3 in SouthCoast’s
application provides a conceptual example of a monopile. SouthCoast would install up to
147 WTG monopile foundations with a maximum diameter tapering from 9 m (2.7 ft)
above the waterline to 16 m (52.5 ft) below the waterline (9/16-m monopile). A typical
impact pile driven monopile installation sequence begins with transport of the monopiles
either directly to the Lease Area or to the construction staging port by an installation
vessel or a feeding barge. At the foundation location, the main installation vessel upends
the monopile in a vertical position in the pile gripper mounted on the side of the vessel.
The impact hammer is then lifted on top of the pile and pile driving commences with a
20-minute minimum soft-start, where lower hammer energy is used at the beginning of
each pile installation to allow marine mammal and prey to move away from the sound
source before noise levels increase to the maximum extent. Piles are driven until the
target embedment depth is met, then the pile hammer is removed and the monopile is
released from the pile gripper. SouthCoast would install WTG monopiles using an impact
pile driver with a maximum hammer energy of 6,600 kJ (model NNN 6600) for a total of
7,000 strikes (including soft-start hammer strikes) at a rate of 30 strikes per minute to a
total maximum penetration depth of 50 m (164 ft). As described previously, for pile

installations utilizing vibratory pile driving as well, this impact installation sequence
would be preceded by use of a vibratory hammer to drive the pile to a depth that is
sufficient to fully support the structure before beginning the soft-start and subsequent
impact hammering. For these piles, SouthCoast would use a vibratory hammer (model
HX-CV640) followed by a maximum of 5,000 impact hammer strikes (including softstart) using the same hammer and parameters specified above.
SouthCoast is proposing to install the majority of monopile foundations
consecutively using a single vessel and on a small number of days, concurrently with
OSP piled jacket pin piles using two vessels (see Dates and Duration section). Under
typical conditions, impact installation of a single monopile foundation is estimated to
require up to 4 hours of active impact pile driving (7,000 strikes/30 strikes per minute
equals approximately 233 minutes, or 3.9 hours), which can occur either in a continuous
4-hour interval or intermittently over a longer time period. For installations requiring
vibratory and impact pile driving, the installation duration is also expected to last
approximately 4 hours, beginning with 20 minutes of active vibratory driving, followed
by short period during which the hammer set-up would be changed from vibratory to
impact, after which impact installation would begin with a 20-minute soft-start (5,000
strikes/30 strikes per minute equals approximately 167 minutes, or 2.8 hours). Following
monopile installation completion, SouthCoast anticipates it would then take
approximately 4 hours to move to the next piling location. Once at the new location, a 1hour marine mammal monitoring period would occur such that there would be a
minimum of 5 hours between pile installations. Based on this schedule, SouthCoast
estimates a maximum of two monopiles could be sequentially driven per day using a
single installation vessel, assuming a 24-hour pile driving schedule.
For Project 1 Scenario 1, it is assumed that all 71 WTG monopiles would be
installed using only an impact hammer (i.e., no vibratory pile driving), requiring a

maximum of 284 hours (71 WTGs x 4 hours each) of active impact pile driving.
Similarly, for Project 2 Scenario 1, it is assumed that all 68 monopiles would be installed
using the same approach, for a total of 272 hours of impact hammering. However, for
Project 2 Scenario 2, it is assumed that 67 (out of a total of 73) monopiles would be
installed using a combination of vibratory and impact pile driving, and 6 monopiles
would be installed using only impact pile driving. Installation of all WTG foundations for
Project 2 Scenario 2 would require a total of approximately 212 hours (6 WTGs x 4 hours
plus 67 WTGs x 2.8 hours each) of impact and 23 hours (67 WTGs x 20 minutes each) of
vibratory pile driving.
Pin-piled jacket
As an alternative to monopiles, SouthCoast proposed one scenario for each
Project (P1S2 and P2S3) that, when combined, would include installation of 147 pinpiled jacket foundations to support WTGs. Jackets are large lattice structures made of
steel tubes welded together and supported by securing piles (i.e., pin piles). Figure 4 of
SouthCoast’s application provides a conceptual example of this type of foundation. For
the SouthCoast Project, each WTG piled jacket foundation would have up to four legs
supported by one pin pile per leg, for a total of up to 588 pin piles to support 147 WTGs.
Each pin pile would have a maximum diameter of 4.5 m (14.7 ft). Pin-piled jacket
foundation installation is a multi-stage process, beginning with preparation of the seabed
by clearing any debris. The WTG jacket foundations are expected to be pre-piled,
meaning that pin piles would be installed first, and the jacket structure would be set on
those pre-installed piles. Once the piled-jacket foundation materials are delivered to the
Lease Area, a reusable template would be placed on the prepared seabed to ensure
accurate positioning of the pin piles that will be installed to support the jacket. Pin piles
would be individually lowered into the template and driven to the target penetration depth
using the same approach described for monopile installation. For installations requiring

only impact pile driving (e.g., P1S2), SouthCoast would install pin piles using an impact
pile driver with a maximum hammer energy of 3,500 kJ (MHU 3500S) for a total of
4,000 strikes (including soft-start hammer strikes) at a rate of 30 strikes per minute to a
maximum penetration depth of 70 m (229.6 ft). When installations require both types of
pile driving, this impact pile driving sequence would only begin after SouthCoast utilized
a vibratory hammer (S-CV640) to set the pile to a depth providing adequate stability.
Subsequent impact hammering (using the same hammer specified) above would require
fewer strikes (n=2,667) to drive the pile to the final 70-m maximum penetration depth.
Under typical conditions, impact-only installation (applicable to P1S2, and all
OSP pin-piled jacket foundations) of each pin pile is estimated to require approximately 2
hours of active impact pile driving (4,000 strikes/30 strikes per minute equals
approximately 133 minutes, or 2.2 hours), for a maximum of 8.8 hours total for a single
WTG or OSP pin- piled jacket foundation supported by 4 pin piles. For each pin pile
requiring vibratory and impact pile driving (applicable to P2S3 WTG pin- piled jacket
foundations only), the installation would begin with 90 minutes of vibratory hammering
per pin pile, and would require fewer hammer strikes per pile over a shorter duration
compared to impact-only installations (2,667 strikes/30 strikes per minute equals
approximately 89 minutes, or 1.5 hours), for a total of 6 hours for each installation
method (12 hours total). Pile driving would occur continuously or intermittently, with
installations requiring both methods of pile driving punctuated by the time required to
change from the vibratory to impact hammer. SouthCoast estimates that they could install
a maximum of four pin piles per day, assuming use of a single installation vessel and 24hour pile driving operations. Following pin pile installations, a vessel would install the
jacket to the piles, either directly after the piling vessel completes operations or up to one
year later.

For Project 1 Scenario 2, it is assumed that all 85 WTG pin-piled jacket
foundations (for a total of 340 pin piles) would be installed using only an impact hammer
(i.e., no vibratory pile driving), requiring a maximum of 680 hours (85 WTGs x 8 hours
each) of active impact pile driving. For Project 2 Scenario 3, it is assumed that 48 (out of
a total of 62) pin-piled jacket foundations (or 192 out of 248 pin piles) would be installed
using a combination of vibratory and impact pile driving, and 14 pin-piled jacket
foundations (or 56 pin piles) would be installed using only impact pile driving.
Installation of all WTG foundations for Project 2 Scenario 3 would require a total of
approximately 184 hours (14 WTGs x 8 hours plus 48 WTGs x 1.5 hours each) of impact
and 72 hours (48 WTGs x 90 minutes (or 1.5 hours) each) of vibratory pile driving.
Installation of WTG monopile and pin-piled jacket foundations is anticipated to
result in take of marine mammals due to noise generated during pile driving. Therefore,
SouthCoast has requested, and NMFS proposes to authorize, take by Level A harassment
and Level B harassment of marine mammals incidental to this activity.
Suction bucket
Suction bucket jackets have a similar steel lattice design to the piled jacket
described previously, but the connection to the seafloor is different (see Figure 5 in
SouthCoast’s application for a conceptual example of the WTG suction bucket jacket
foundation). These substructures use suction-bucket foundations instead of piles to secure
the structure to the seabed; thus, no impact driving would be used for installation of WTG
suction bucket jackets. Should SouthCoast select this foundation type for Project 2, each
of the suction-bucket jacket substructures, including four buckets per foundation (one per
leg), would be installed as described below. Similar to monopiles and pin-piled jackets,
the number of suction-bucket jacket foundations will depend on the final design for
Project 1. For suction-bucket jackets, the jacket is lowered to the seabed, the open bottom
of the bucket and weight of the jacket embeds the bottom of the bucket in the seabed. To

complete the installation and secure the foundation, water and air are pumped out of the
bucket creating a negative pressure within the bucket, which embeds the foundation
buckets into the seabed. The jacket can also be leveled at this stage by varying the
applied pressure. The pumps will be released from the suction buckets once the jacket
reaches its designed penetration. The connection of the required suction hoses is typically
completed using a remotely operated vehicle (ROV).
As previously indicated, installation of suction bucket foundations is not expected
to result in take of marine mammals; thus, this activity is not further discussed.
Offshore Substation Platform (OSP)
Each construction scenario SouthCoast defined includes installation of a pin-piled
jacket foundation to support a single OSP per Projects 1 and 2, However, in the ITA
application, SouthCoast indicates that their project design envelope includes the potential
installation of up to a total of 5 OSPs, situated on the same 1 nm x 1 nm (1.9 km x 1.9
km) grid layout as the WTG foundation, and describes three OSP designs (i.e., modular,
integrated, or Direct Current (DC) Converter) that are under consideration (see Figures 6,
7, and 8 in SouthCoast’s ITA application). The number of OSPs installed would vary
based upon design. Based on the COP PDE, SouthCoast could install a minimum of a
single modular OSP on a monopile foundation, and a maximum of five DC Converter
OSPs, each with nine pin-piled jacket foundations secured by three pin piles each, for a
total of 135 pin piles. All OSP monopile and pin-piled jacket foundations would be
installed using only impact pile driving.
Installation of an OSP monopile foundation would follow the same parameters
(e.g., pile diameter, hammer energy, penetration depth) and procedure as previously
described for WTG monopiles. OSP piled jacket foundations would be similar to that
described for WTG piled jacket foundations but would be installed using a post-piling,
rather than pre-piling, installation sequence. In this sequence, the seabed is prepared, the

jacket is set on the seafloor, and the piles are driven through the jacket legs to the
designed penetration depth (dependent upon which OSP design is selected). The piles are
connected to the jacket via grouted and/or swaged connections. A second vessel may
perform grouting tasks, freeing the installation vessel to continue jacket installation at a
subsequent OSP location, if needed. Pin piles for each jacket design would be installed
using an impact hammer with a maximum energy of 3,500 kJ. A maximum of four OSP
pin piles could be installed per day using a single vessel, assuming 24-hour pile driving
operations. All impact pile driving activity of pin piles would include a 20-minute softstart at the beginning of each pile installation. Installation of a single OSP piled jacket
foundation by impact pile driving (the only proposed method) would vary by design and
the associated number of supporting pin piles, each of which would require 2 hours of
impact hammering.
The “Modular OSP” design would sit on any one of the three types of
substructure designs (i.e., monopile, piled jacket, or suction bucket) similar in
size and weight to those described for the WTGs (see Section 1.1.1 in
SouthCoast’s ITA application), with the topside connected to a transition piece
(TP). This Modular OSP design is an AC solution and will likely hold a single
transformer with a single export cable. This option is a relatively small design
relative to other options and, thus, has benefits related to manufacture,
transportation, and installation. An example of the Modular OSP on a jacket
substructure is shown in Figure 6 of SouthCoast’s ITR application. The
Modular OSP design assumes an OSP topside height ranging from 50 m (164
ft) to 73.9 m (242.5 ft). A Modular OSP piled jacket foundation would be the
smallest and include three to four legs with one to two pin piles per leg (three
to eight total pin piles per piled jacket). Pin piles would have a diameter of up

to 4.5 m (14.7 ft) and would be installed using up to a 3,500-kJ hammer to a
target penetration depth of 70 m (229.6 ft) below the seabed.
The “Integrated OSP'' design would have a jacket substructure and a
larger topside than the Modular OSP. This OSP option is also an AC solution
and is designed to support a high number of inter-array cable connections as
well as the connection of multiple export cables. This design differs from the
Modular OSP in that it is expected to contain multiple transformers and export
cables integrated into a single topside. The Integrated OSP design assumes the
same topside height indicated for the Modular design. Depending on the final
weight of the topside and soil conditions, the jacket substructure may be fouror six-legged and require support from one to three piles per leg (up to 16 pin
piles). The larger size of the Integrated OSP would provide housing for a
greater number of electrical components as compared to smaller designs (such
as the Modular OSP), reducing the number of OSPs required to support the
proposed Project. An example of the integrated OSP design is shown in Figure
7 of SouthCoast’s ITR application.
SouthCoast may install one or more “DC Converter OSPs.” This OSP
option would serve as a gathering platform for inter-array cables and then
convert power from high-voltage AC to high-voltage DC or it could be
connected to one or more AC gathering units (Modular or Integrated OSPs)
and serve to convert power from AC to DC prior to transmission on an export
cable. The DC Converter OSP would be installed on a piled jacket foundation
with four legs, each supported by three to four 3.9-m (12.8-ft) pin piles per leg
(up to 16 total pin piles per jacket), installed using a 3,500-kJ hammer to a
target penetration depth of 90 m (295.3 ft) below the seabed. Please see Figure
8 in SouthCoast’s ITR application for example of a DC jacket OSP design.

Although SouthCoast has not yet selected an OSP design or finalized their foundation
installation plan, they anticipate that they would only install only two of the five OSPs
included in the PDE, one per Project. Each OSP would be supported by a piled jacket
foundation with four legs anchored by three to four pin piles (for a total of up to 16 pin
piles per OSP piled jacket). SouthCoast plans to install a maximum of four OSP jacket
pin piles per day, so an OSP jacket foundation requiring 16 pin piles would be installed
over four days (intermittently). For all three OSP piled jacket options (modular,
integrated and DC-converter), installation of a single pin pile is anticipated to take up to 2
hours of pile driving. It is anticipated that a maximum of eight pin piles could be driven
into the seabed per day assuming 24-hour pile driving operation. Pile driving activity will
include a soft-start at the beginning of each pin pile installation. Impacts of pile-driving
noise incidental to OSP piled jacket foundation installation have been evaluated based on
the use of a 3,500 kJ hammer, as this is representative of the maximum hammer energy
included in the PDE.
Installation of OSP foundations is anticipated to result in take of marine mammals
due to noise generated during pile driving. Therefore, SouthCoast has requested, and
NMFS proposes to authorize, take by Level A harassment and Level B harassment of
marine mammals incidental to OSP foundation installation.
HRG Surveys
SouthCoast would conduct HRG surveys to identify any seabed debris and to
support micrositing of the WTG and OSP foundations and ECCs. These surveys may
utilize active acoustic equipment such as multibeam echosounders, side scan sonars,
shallow penetration sub-bottom profilers (SBPs) (e.g., parametric Compressed HighIntensity Radiated Pulses (CHIRP) SBPs and non-parametric SBP), medium penetration
sub-bottom profilers (e.g., sparkers and boomers), and ultra-short baseline positioning
equipment, some of which are expected to result in the take of marine mammals. Surveys

would occur annually, with durations dependent on the activities occurring in that year
(i.e., construction years versus non-construction years).
HRG surveys will be conducted using up to four vessels. On average, 80-line km
(49.7-mi) will be surveyed per vessel each survey day at approximately 5.6 km/hour (3
knots) on a 24-hour basis although some vessels may only operate during daylight hours
(~12-hour survey vessels).
During the 2-year construction phase, an estimated 4,000 km (2,485 mi) may be
surveyed within the Lease Area and 5,000 km (3,106 mi) along the ECCs in water depth
ranging from 2 m (6.5 ft) to 62 m (204 ft). A maximum of four vessels will be used
concurrently for surveying. While the final survey plans will not be completed until
construction contracting commences, HRG surveys are anticipated to operate at any time
of year for a maximum of 112.5 survey days per year.
During non-construction periods (3 of the 5 years within the effective period of
the regulations), SouthCoast would survey an estimated 2,800 km (1,7398 mi) in the
Lease Area and 3,200 km (1,988.4 mi) along the ECCs each year for three years
(n=18,000 km total). Using the same estimate of 80 km (49.7 mi) of surveys completed
each day per vessel, approximately 75 days of surveys would occur each year, for a total
of up to 225 active sound source days over the 3-year operations period.
Of the HRG equipment types proposed for use, the following sources have the
potential to result in take of marine mammals:
●

Shallow penetration sub-bottom profilers (SBPs) to map the near-surface

stratigraphy (top 0 to 5 m (0 to 16 ft) of sediment below seabed). A CHIRP system emits
sonar pulses that increase in frequency over time. The pulse length frequency range can
be adjusted to meet Projectvariables. These are typically mounted on the hull of the
vessel or from a side pole.

●

Medium penetration SBPs (boomers) to map deeper subsurface

stratigraphy as needed. A boomer is a broad-band sound source operating in the 3.5 Hz to
10 kHz frequency range. This system is typically mounted on a sled and towed behind the
vessel.
●

Medium penetration SBPs (sparkers) to map deeper subsurface

stratigraphy as needed. A sparker creates acoustic pulses from 50 Hz to 4 kHz omnidirectionally from the source that can penetrate several hundred meters into the seafloor.
These are typically towed behind the vessel with adjacent hydrophone arrays to receive
the return signals.
Table 3 identifies all the representative survey equipment that operate below 180
kilohertz (kHz) (i.e., at frequencies that are audible and have the potential to disturb
marine mammals) that may be used in support of planned geophysical survey activities
and is likely to be detected by marine mammals given the source level, frequency, and
beamwidth of the equipment. Equipment with operating frequencies above 180 kHz (e.g.,
SSS, MBES) and equipment that does not have an acoustic output (e.g., magnetometers)
will also be used but are not discussed further because they are outside the general
hearing range of marine mammals likely to occur in the Lease Area and ECCs. No take is
expected from the operation of these sources; therefore, they are not discussed further.
Table 3 – Summary of Representative HRG Survey Equipment and Operating
Parameters
Source
Level
SPLrms
(dB)

Source
Level0-pk
(dB)

2 – 16

184

9.1

CF

1–6

183

14.4

66

CF

180

4

71

CF

2–7

204

14.4

CF

Operating
Equipment Representat
Frequency
Type
ive Model
(kHz)
EdgeTech
3100 with
SB 2-161
towfish
EdgeTech
DW-1061
Knudson
Sub-bottom Pinger2
Profiler
Teledyn
Benthos
CHIRP III
- TTV 1703

Pulse
Repetition Beamwidth Informatio
Duration
Rate (Hz) (degrees) n Source
(ms)

Sparker4

Applied
Acoustics
Dura-Spark 0.01 – 1.9
UHD (400
tips, 800 J)
Geomarine
Geo-Spark
0.01 – 1.9
(400 tips,
800 J)

213

3.4

Omni

CF

213

3.4

Omni

CF

Applied
Acoustics
triple plate 0.1 – 5
205
211
0.9
3
61
CF
Boomer
S-Boom
(700–1,000
J)
Note: J = joule; kHz = kilohertz; dB = decibels; SL = source level; UHD = ultra-high definition; rms =
root-mean square; µPa = microPascals; re = referenced to; SPL = sound pressure level; PK = zero-to-peak
pressure level; Omni = omnidirectional source; CF = Crocker and Fratantonio (2016)
1 – The EdgeTech Chirp 512i measurements and specifications provided by Crocker and Fratantonio
(2016) were used as a proxy for the Edgetech 3100 with SB-216 towfish and EdgeTech DW-106.
2 – The EdgeTech Chirp 424 as a proxy for source levels as the Chirp 424 has similar operation settings as
the Knudsen Pinger SBP.
3 – The Knudsen 3202 Echosounder measurements and specifications provided by Crocker and Fratantonio
(2016) were used as a proxy for the Teledyne Benthos Chirp III TTV 170.
4 – The SIG ELC 820 Sparker, 5 m source depth, 750 J setting was used a proxy for both the Applied
Acoustics Dura-Spark UHD (400 tips, 800 J) and Geomarine Geo-Spark (400 tips, 800 J).

Based on the operating frequencies of HRG survey equipment in table 3 and the
hearing ranges of the marine mammals that have the potential to occur in the Lease Area
and ECCs, HRG survey activities have the potential to result in take by Level B
harassment of marine mammals. No take by Level A harassment is anticipated as a result
of HRG survey activities.
UXO/MEC Detonations
SouthCoast anticipates encountering UXO/MECs during Project construction in
the Lease Area and along the ECCs. UXO/MECs include explosive munitions such as
bombs, shells, mines, torpedoes, etc., that did not explode when they were originally
deployed or were intentionally discarded in offshore munitions dump sites to avoid landbased detonations. SouthCoast plans to remove any UXO/MEC encountered, else, the
risk of incidental detonation associated with conducting seabed-altering activities, such as
cable laying and foundation installation in proximity to UXO/MECs, would potentially
jeopardize the health and safety of Projectparticipants.

SouthCoast would follow an industry standard As Low as Reasonably Practicable
(ALARP) process that minimizes the number of detonations, to the extent possible. For
UXO/MECs that are positively identified in proximity to specified activities on the
seabed, several alternative strategies would be considered prior to in-situ UXO/MEC
disposal. These may include: 1) relocating the activity away from the UXO/MEC
(avoidance); 2) physical UXO/MEC removal (lift and shift); 3) alternative combustive
removal technique (low order disposal); 4) cutting the UXO/MEC open to apportion large
ammunition or deactivate fused munitions (cut and capture); or 5) using shaped charges
to ignite the explosive materials and allow them to burn at a slow rate rather than
detonate instantaneously (deflagration). Only after these alternatives are considered and
found infeasible would in-situ high-order UXO/MEC detonation be pursued. If
detonation is necessary, detonation noise could result in the take of marine mammals by
Level A harassment and Level B harassment.
SouthCoast is currently conducting a study to more accurately determine the
number of UXO/MECs that may be encountered during the specified activities (see
section 1.1.5 in SouthCoast’s ITA application). Based on estimates for other offshore
wind projects in southern New England, SouthCoast assumes that up to ten UXO/MEC
454-kg (1000 pounds; lbs) charges, which is the largest charge that is reasonably
expected to be encountered, may require in situ detonation. Although it is highly unlikely
that all ten charges would weigh 454 kg, this approach was determined to be the most
conservative for the purposes of impact analysis. All charged detonations would occur on
different days (i.e., only one detonation would occur per day). In the event that high-order
detonation is determined to be the preferred and safest method of disposal, all detonations
would occur during daylight hours. SouthCoast proposed a seasonal restriction on
UXO/MEC detonations from December 1 – April 30, annually.

UXO/MEC activities have the potential to result in take by Level A harassment
and Level B harassment of marine mammals. No non-auditory take by Level A
harassment is anticipated due to proposed mitigation and monitoring measures.
Cable Landfall Construction
Installation of the SouthCoast export cables at the designated landfall sites will be
accomplished using horizontal directional drilling (HDD) methodology. HDD is a
“trenchless” process for installing cables or pipes which enables the cables to remain
buried below the beach and intertidal zone while limiting environmental impact during
installation. Drilling activities would occur on land with the borehole extending under the
seabed to an exit point offshore, outside of the intertidal zone. There will be up to two
ECCs, both exiting the Lease Area in the northwestern corner. These then split, with one
making landfall at Brayton Point in Somerset, MA (Brayton Point ECC) and the other in
Falmouth, MA (Falmouth ECC). The Brayton Point ECC is anticipated to contain up to
six export cables, bundled where practicable, while the Falmouth ECC is anticipated to
contain up to five export cables. HDD seaward exit points will be sited within the defined
ECCs at the Brayton Point and intermediate Aquidneck Island landfall sites and at the
Falmouth landfall site(s). The exit points will be within approximately 3,500 ft (1,069 m)
of the shoreline for the Falmouth ECC landfall(s), and within approximately 1,000 ft (305
m) of the shoreline for the Brayton Point landfalls.
At the seaward exit point, construction activities may include installation of either
a temporary gravity-based structure (i.e., gravity cell or gravity-based cofferdam) or a
dredged exit pit, neither of which would require pile driving or hammering. Additionally,
a conductor pipe may be installed at the exit point to support the drilling activity.
Conductor pipe installation would include pushing or jetting rather than pipe ramming.
For the Falmouth landfall locations, the proposed HDD trajectory is anticipated to
be approximately 0.9 mi (1.5 km) in length with a cable burial depth of up to

approximately 90 ft (27.4 m) below the seabed. HDD boreholes will be separated by a
distance of approximately 33 ft (10 m). Each offshore export cable is planned to require a
separate HDD, with an individual bore and conduit for each export cable. The number of
boreholes per site will be equal to the number of power cables installed. The Falmouth
ECC would include up to four power cables with up to four boreholes at each landfall
site. There may be up to one additional communications cable; however, the
communications cable would be installed within the same bore as one of the power
cables, likely within a separate conduit.
For the Brayton Point and Aquidneck Island intermediate landfall locations, the
proposed HDD trajectory is anticipated to be approximately 0.3 mi (0.5 km) in length
with a cable burial depth of up to approximately 90 ft (27.4 m) below the seabed. HDD
bores will be separated by a distance of approximately 33 ft (10 m). It is anticipated the
high-voltage DC cables will be unbundled at landfall. Each high-voltage DC power cable
is planned to require a separate HDD, with an individual bore and conduit for each power
cable. The Brayton Point and Aquidneck Island ECCs will include up to four power
cables for a total of up to four boreholes at each landfall site. Each dedicated
communications cable may be installed within the same bore as a power cable, likely
within a separate conduit.
In collaboration with the HDD contractor, SouthCoast will further assess the
potential use of a dredged exit pit and/or gravity cell at each landfall location. The
specifics of each site will be evaluated in detail, in terms of soil and metocean conditions
(i.e., current), suitability for maintaining a dredged exit pit for the duration of the HDD
construction, and other construction planning factors that may affect the HDD operation.
The relatively low noise levels generated by installation and removal of gravity-cell
cofferdams, dredged exit pits, and conductor pipe are not expected to result in Level A
harassment or Level B harassment of marine mammals. SouthCoast is not requesting, and

NMFS is not proposing to authorize, take associated with landfall construction activities.
Therefore, these activities are not analyzed further in this document.
Cable Laying and Installation
Cable burial operations would occur both in the Lease Area for the inter-array
cables connecting WTGs to OSPs and in the ECCs for cables carrying power from the
OSPs to shore. The offshore export cables would be buried in the seabed at a target depth
of up to 1.0 to 4.0 m (3.2 to 13.1 ft) while the inter-array cables would be buried at a
target depth up to 1.0 to 2.5 m (3.2 to 8.2 ft). Both cable types would be buried onshore
up to the transition joint bays. All cable burial operations would follow installation of the
monopile foundations as the foundations must be in place to provide connection points
for the export cable and inter-array cables. Cable laying, cable installation, and cable
burial activities planned to occur during the construction of the SouthCoast Project May
include the following: jetting; vertical injection; leveling; mechanical cutting; plowing
(with or without jet-assistance); pre-trenching; boulder removal; and controlled flow
excavation. Installation of any required protection at the cable ends is typically completed
prior to cable installation from the vessel.
Some dredging may be required prior to cable laying due to the presence of
sandwaves. Sandwave clearance may be undertaken to provide a level bottom to install
the export cable. The work could be undertaken by traditional dredging methods such as
a trailing suction hopper. Alternatively, controlled flow excavation or a water-injection
dredger could be used. In some cases, multiple passes may be required. The method of
sand wave clearance SouthCoast chooses would be based on the results from the site
investigation surveys and cable design.
As the noise levels generated from cable laying and installation work are low, the
potential for take of marine mammals to result is discountable. SouthCoast is not

requesting, and NMFS is not proposing to authorize, take associated with cable laying
activities. Therefore, cable laying activities are not analyzed further in this document.
Vessel Operation
SouthCoast will utilize various types of vessels over the course of the 5-year
proposed regulations for surveying, foundation installation, cable installation, WTG and
OSP installation, UXO/MEC detonation, and support activities. SouthCoast anticipates
operating an average of 15 to 35 vessels daily depending on construction phase, with an
expected maximum of 50 vessels in the Lease Area at one time during the foundation
installation period. Table 4 provides a list of the vessel types, number of each vessel type,
number of expected trips, and anticipated years each vessel type will be in use. All
vessels will follow the vessel strike avoidance measures as described in the Proposed
Mitigation section.
To support offshore construction, assembly and fabrication, crew transfer and
logistics, as well as other operational activities, SouthCoast has identified several existing
domestic port facilities located in Massachusetts (Ports of Salem, New Bedford, Fall
River), Rhode Island (Ports of Providence and Davisville), Connecticut (Port of New
London), and to a lesser extent Maryland (Sparrows Point Port), South Carolina (Port of
Charleston), and Texas (Port of Corpus Cristi).
The largest vessels are expected to be used during the foundation installation
phase with heavy transport vessels, heavy lift crane vessels, cable laying vessels, supply
and crew vessels, and associated tugs and barges transporting construction equipment and
materials. A large service operation vessel would have the ability to stay in the lease area
and house crews overnight. These larger vessels will generally move slowly over a short
distance between work locations, within the Lease Area and along ECCs. Smaller vessels
would be used to transfer crew and smaller dimension Project materials to and from, as
well as within, the Lease Area. Transport vessels will travel between several ports and the

Lease Area over the course of the construction period following mandatory vessel speed
restrictions (see Proposed Mitigation section). These vessels will range in size from
smaller crew transport to tug and barge vessels. Construction crews responsible for
assembling the WTGs would hotel onboard installation vessels at sea, thus limiting the
number of crew vessel transits expected during the construction period. WTG and OSP
foundation installation vessels may include jack-up, DP, or semi-submersible vessels.
Jack-up vessels lower their legs into the seabed for stability and then lift out of the water,
whereas DP vessels utilize computer-controlled positioning systems and thrusters to
maintain their station. SouthCoast is also considering the use of heavy lift vessels, barges,
feeder vessels, and roll-on lift-off vessels to transport WTG components to the Lease
Area for installation by the WTG installation vessel. Fabrication and installation vessels
may include transport vessels, feeder vessels, jack-up vessels, and installation vessels.
Sounds from vessels associated with the proposed Project are anticipated to be
similar in frequency to existing levels of commercial traffic present in the region. Vessel
sound would be associated with cable installation vessels and operations, piling
installation vessels, and general transit to and from WTG or OSP locations during
construction. During construction, it is estimated that multiple vessels may operate
concurrently at different locations throughout the Lease Area or ECCs. Some of these
vessels may maintain their position (using DP thrusters) during pile driving or other
construction activities. The dominant underwater sound source on DP vessels arises from
cavitation on the propeller blades of the thrusters (Leggat et al., 1981). The noise power
from the propellers is proportional to the number of blades, propeller diameter, and
propeller tip speed. Sound levels generated by vessels using DP are dependent on the
operational state and weather conditions.
All vessels emit sound from propulsion systems while in transit. The SouthCoast
Project would be constructed in an area that consistently experiences extensive marine

traffic. As such, marine mammals in the general region are regularly subjected to vessel
activity and would potentially be habituated to the associated underwater noise as a result
of this exposure (BOEM, 2014b). Because noise from vessel traffic associated with
construction activities is likely to be similar to background vessel traffic noise, the
potential risk of impacts from vessel noise to marine life is expected to be low relative to
the risk of impact from pile-driving sound.
Sound produced through use of DP thrusters is considered a continuous sound
source and similar to that produced by transiting vessels. DP thrusters are typically
operated either in a similarly predictable manner or used intermittently for short durations
around stationary activities. Sound produced by DP thrusters would be preceded by and
associated with sound from ongoing vessel noise and would be similar in nature. Any
marine mammals in the vicinity of the activity would be aware of the vessel's presence,
thus making it unlikely that the noise source would elicit a startle response.
Construction-related vessel activity, including the use of dynamic positioning thrusters, is
not expected to result in take of marine mammals. SouthCoast did not request, and NMFS
does not propose to authorize, take associated with vessel activity.
During operations, SouthCoast will use crew transfer vessels (CTVs) and service
operations vessels (SOVs). The number of each vessel type, number of trips, and
potential ports to be used during operations and maintenance are provided in table 4. The
operations vessels will follow the vessel strike avoidance measures as described in the
Proposed Mitigation section.
Table 4 – Type and Number of Vessels Anticipated During Construction and
Operations
Vessel Types

Estimated Number of
Vessel Type

Supply Trips to Port
from Lease Area (or
Point of Entry in U.S.,
where applicable1)

Anticipated Years In
Use

Vessel Use During Construction
Heavy Lift Crane Vessel

1-5

2028-2031 (P1 and 2)

Heavy Transport Vessel

1-20

2027-2031 (P1 and 2)

Tugboat

1-12

2028-2031 (P1 and 2)

Crew Transfer Vessel

2-5

1,608

2028-2031 (P1 and 2)

Anchor Handling Tug

1-10

2028-2031 (Projects 1
and 2)

Scour Protection
Installation Vessel

1-2

2028-2030 (P1 and P2)

Cable Laying Barge

1-3

2027-2028 (Project 1)
2029-2030 (Project 2)

Cable Transport and Lay
Vessel

1-5

2028-2029 Project 1 and
Project 2

Maintenance
Crew/CTVs

2-5

1,608

2028-2031 (P1 and 2)

Dredging Vessel

1-5

2026-2027 (P1) 20292030 (P2)

Survey Vessel

1-5

2027-2031 (P1 and P2)

Barge

1-6

2028-2031 (P1 and P2)

Jack-up Accommodation
Vessel

1-2

2029-2030 (P1 and P2)

DP Accommodation
Vessel

1-2

2029-2030 (P1 and P2)

Service Operation
Vessel

1-4

Multi-purpose Support
Vessel/Service
Operation Vessel

1-8

2029-2031 (P1 and P2)

2027-2031 P1 and P2)

Vessel Use During Operations
Maintenance Crew/Crew
Transfer Vessels (CTVs)

Service Operation
Vessel

1-2

15,015
2028-2031

1-2

1,638

While vessel strikes cause injury or mortality of marine mammals, NMFS does
not anticipate such taking to occur from the specified activity due to general low
probability and proposed extensive vessel strike avoidance measures (see Proposed
Mitigation section). SouthCoast has not requested, and NMFS is not proposing to
authorize, take from vessel strikes.
Seabed Preparation
Seabed preparations will be the first offshore activity to occur during the
construction phase of the SouthCoast Project, and may include scour (i.e., erosion)

protection, sand leveling, sand wave removal, and boulder removal. Scour protection is
the placement of materials on the seafloor around the substructures to prevent the
development of scour, or erosion, created by the presence of structures. Each substructure
used for WTGs and OSPs may require individual scour protection, thus the type and
amount utilized will vary depending on the final substructure type selected for
installation. For a substructure that utilizes seabed penetration in the form of piles or
suction caissons, the use of scour protectant to prevent scour development results in
minimized substructure penetration. Scour protection considered for Projects 1 and 2 may
include rock (rock bags), concrete mattresses, sandbags, artificial seaweeds/reefs/frond
mats, or self-deploying umbrella systems (typically used for suction-bucket jackets).
Installation activities and order of events of scour protection will depend on the type and
material used. For rock scour protection, a rock placement vessel may be deployed. A
thin layer of filter stones would be placed prior to pile driving activity while the armor
rock layer would be installed following completion of foundation installation. Frond mats
or umbrella-based structures may be pre-attached to the substructure, in which case the
pile and scour protection would be installed simultaneously. For all types of scour
protection materials considered, the results of detailed geological campaigns and
assessments will support the final decision of the extent of scour protection required.
Placement of scour protection may result in suspended sediments and a minor conversion
of marine mammal prey benthic habitat conversion of the existing sandy bottom habitat
to a hard bottom habitat as well as potential beneficial reef effects (see Section 1.3 of the
ITA application).
Seabed preparation may also include leveling, sand wave removal, and boulder
removal. SouthCoast may utilize equipment to level the seabed locally in order to use
seabed operated cable burial tools to ensure consistent burial is achieved. If sand waves
are present, the tops may be removed to provide a level bottom to install the export cable.

Sand wave removal may be conducted using a trailing suction hopper dredger (or
similar), a water injection dredge in shallow areas, or a constant flow excavator. Any
boulder discovered in the cable route during pre-installation surveys that cannot be easily
avoided by micro-routing may be removed using non-explosive methods such as a grab
lift or plow. If deemed necessary, a pre-lay grapnel run will be conducted to clear the
cable route of buried hazards along the installation route to remove obstacles that could
impact cable installation such as abandoned mooring lines, wires, or fishing equipment.
Site-specific conditions will be assessed prior to any boulder removal to ensure that
boulder removal can safely proceed. Boulder clearance is a discreet action occurring over
a short duration resulting in short term direct effects.
Sound produced by Dynamic Positioning (DP) vessels is considered nonimpulsive and is typically more dominant than mechanical or hydraulic noises produced
from the cable trenching or boulder removal vessels and equipment. Therefore, noise
produced by a pull vessel with a towed plow or a support vessel carrying a boulder grab
would be comparable to or less than the noise produced by DP vessels, so impacts are
also expected to be similar. Boulder clearance is a discreet action occurring over a short
duration resulting in short term direct effects. Additionally, sound produced by boulder
clearance vessels and equipment would be preceded by, and associated with, sound from
ongoing vessel noise and would be similar in nature. presence, further reducing the
potential for startle or flight responses on the part of marine mammals. Monitoring of
past projects that entailed use of DP thrusters has shown a lack of observed marine
mammal responses as a result of exposure to sound from DP thrusters (NMFS 2018). As
DP thrusters are not expected to result in take of marine mammals, these activities are not
analyzed further in this document.
NMFS expects that marine mammals would not be exposed to sounds levels or
durations from seafloor preparation work that would disrupt behavioral patterns.

Therefore, the potential for take of marine mammals to result from these activities is
discountable and SouthCoast did not request, and NMFS does not propose to authorize,
any takes associated with seafloor preparation work. These activities are not analyzed
further in this document.
NMFS does not expect site preparation work, including boulder removal and sand
leveling, to generate noise levels that would cause take of marine mammals. Underwater
noise associated with these activities is expected to be similar in nature to the nonimpulsive sound produced by the DP cable lay vessels used to install inter-array cables in
the Lease Area and export cables along the ECCs. Boulder clearance is a discreet action
occurring over a short duration resulting in short term direct effects.
Southcoast did not request take of marine mammals incidental to this activity, and
based on the activity, NMFS neither expects nor proposes to authorize take of marine
mammals incidental to this activity. Thus, this activity will not be discussed further.
Fisheries and Benthic Monitoring
SouthCoast has developed a fisheries monitoring plan (FMP) focusing on the
Lease Area, an inshore FMP that focuses on nearshore portions of the Brayton Point ECC
(i.e., the Sakonnet River), and a benthic monitoring plan that covers both offshore and
inshore portions of the Lease Area and ECCs. The fisheries and benthic monitoring plans
for the SouthCoast Project were developed following guidance outlined in “Guidelines
for Providing Information on Fisheries for Renewable Energy Development on the
Atlantic Outer Continental Shelf” (BOEM, 2019) and the Responsible Offshore Science
Alliance (ROSA) “Offshore Wind Project Monitoring Framework and Guidelines”
(2021).
SouthCoast is working with the University of Massachusetts Dartmouth’s School
for Marine Science and Technology (SMAST) (in partnership with the Massachusetts
Lobstermen's Association) and Inspire Environmental to develop and conduct surveys as

a cooperative research program using local fishing vessels and knowledge. SouthCoast
intends to conduct their research on contracted commercial and recreational fishing
vessels whenever practicable.
Offshore fisheries monitoring will likely include the following types of surveys:
trawls, ventless trap, drop camera, neuston net, and acoustic telemetry with tagging of
highly migratory species (e.g., blue sharks). Inshore fisheries monitoring surveys will
also include acoustic telemetry targeting commercially and recreationally important fish
species (e.g., striped bass) and trap survey targeting whelk. Benthic monitoring plans are
under development and may include grab samples and collection of imagery. Because the
gear types and equipment used for the acoustic telemetry study, benthic habitat
monitoring, and drop camera monitoring surveys do not have components with which
marine mammals are likely to interact (i.e., become entangled in or hooked by), these
activities are unlikely to have any impacts on marine mammals. Therefore, only trap and
trawl surveys, in general, have the potential to result in harassment to marine mammals.
However, based on proposed mitigation and monitoring measures, taking marine
mammals from this specified activity is not anticipated. A full description of mitigation
and monitoring measures can be found in the Proposed Mitigation and Proposed
Monitoring sections.
Given the planned implementation of the mitigation and monitoring measures,
SouthCoast did not request, and NMFS is not proposing to authorize, take of marine
mammals incidental to research trap and trawl surveys. Any lost gear associated with the
fishery surveys will be reported to the NOAA Greater Atlantic Regional Fisheries Office
Protected Resources Division (GARFO PRD) as soon as possible. Therefore, take from
fishery surveys will not be discussed further.

Description of Marine Mammals in the Specified Geographical Region
Thirty-eight marine mammal species and/or stocks under NMFS’ jurisdiction
have geographic ranges within the western North Atlantic OCS (Hayes et al., 2023). In
the ITA application, SouthCoast identified 31 of those species that could potentially
occur in the Lease Area and surrounding waters. However, for reasons described below,
SouthCoast has requested, and NMFS proposes to authorize, take of only 16 species
(comprising 16 stocks) of marine mammals. Section 4 of SouthCoast’s ITA application
summarizes available information regarding status and trends, distribution and habitat
preferences, and behavior and life history of the species included in SouthCoast’s take
estimation analyses, except for the Atlantic spotted dolphin as it was unintentionally
excluded from this section but included in Section 6 Take Estimates for Marine
Mammals. Given previous observations of the species in the RI/MA and MA WEAs,
SouthCoast included Atlantic spotted dolphins take analyses (and Table 5), and is
requesting Level B harassment take of the species incidental to foundation installation,
UXO/MEC detonation, and HRG surveys, which NMFS is proposing for authorization.
NMFS fully considered all available information for the potentially affected species, and
we refer the reader to Section 4 of the ITA application for more details about each species
(except the Atlantic spotted dolphin) instead of reprinting the information. A description
of Atlantic spotted dolphin distribution, population trends, and life history can be found
in the NMFS SAR (Hayes et al., 2019) (https://media.fisheries.noaa.gov/dammigration/2019_sars_atlantic_atlanticspotteddolphin.pdf).
Additional information regarding population trends and threats may be found in
NMFS’ Stock Assessment Reports (SARs;
https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marinemammal-stock-assessment-reports) and more general information about these species

(e.g., physical and behavioral descriptions) may be found on NMFS’ website
(https://www.fisheries.noaa.gov/find-species).
Of the 31 marine mammal species (comprising 31 stocks) SouthCoast determined
have geographic ranges that include the project area, 14 are considered rare or
unexpected based on the best scientific information available (i.e., sighting and
distribution data, low predicted densities, and lack of preferred habitat) for a given
species. SouthCoast did not request, and NMFS is not proposing to authorize, take of
these species and they are not discussed further in this proposed rulemaking: Dwarf and
pygmy sperm whales (Kogia sima and K. breviceps), Cuvier’s beaked whale (Ziphius
cavirostris), four species of Mesoplodont beaked whales (Mesoplodon densitostris, M.
europaeus, M. mirus, and M. bidens), killer whale (Orcinus orca), short-finned pilot
whale (Globicephalus macrohynchus), white-beaked dolphin (Lagenorhynchus
albirotris), pantropical spotted dolphin (Stenella attenuate), and the, striped dolphin
(Stenella coeruleoalba). Two species of phocid pinnipeds are also uncommon in the
project area, including: harp seals (Pagophilus groenlandica) and hooded seals
(Cystophora cristata).
In addition, the Florida manatee (Trichechus manatus; a sub-species of the West
Indian manatee) has been previously documented as a rare visitor to the Northeast region
during summer months (U.S. Fish and Wildlife Service (USFWS), 2022). However,
manatees are managed by the USFWS and are not considered further in this document.
More information on this species can be found at the following website:
https://www.fws.gov/species/manatee-trichechus-manatus.
Table 5 lists all species or stocks for which take is likely and proposed for
authorization for this action and summarizes information related to the species or stock,
including regulatory status under the MMPA and Endangered Species Act (ESA) and
potential biological removal (PBR), where known. PBR is defined as “the maximum

number of animals, not including natural mortalities, that may be removed from a marine
mammal stock while allowing that stock to reach or maintain its optimum sustainable
population” (16 U.S.C. 1362(20)). While no mortality is anticipated or proposed for
authorization, PBR and annual serious injury and mortality from anthropogenic sources
are included here as gross indicators of the status of the species or stocks and other
threats.
Marine mammal abundance estimates presented in this document represent the
total number of individuals that make up a given stock or the total number estimated
within a particular study or survey area. NMFS’ stock abundance estimates for most
species represent the total estimate of individuals within the geographic area, if known,
that comprises that stock. For some species, this geographic area may extend beyond U.S.
waters. All managed stocks in this region are assessed in NMFS’ U.S. Atlantic and Gulf
of Mexico SARs. All values presented in table 5 are the most recent available at the time
of publication and, unless noted otherwise, use NMFS’ draft 2023 SARs (Hayes et al.,
2024) available online at https://www.fisheries.noaa.gov/national/marine-mammalprotection/draft-marine-mammal-stock-assessment-reports.
Table 5 – Marine Mammal Species1 That May Occur in the Specified Geographical
Region and be Taken by Harassment

Common
name1

Scientific
name

Stock

Stock
abundance
(CV, Nmin,
most recent
abundance
survey)3

ESA/MMP
A status;
Strategic
(Y/N)2

PBR

Annual
M/SI4

Order Artiodactyla – Cetacea – Superfamily Mysticeti (baleen whales)
Family Balaenidae
North
Atlantic
right whale

Eubalaena
glacialis

Western
Atlantic

E, D, Y

340 (0; 337;
2021); 356
(346-363,
2022)5

Family Balaenopteridae (rorquals)

0.7

27.26

Blue whale

Balaenopter
a musculus

Western
North
Atlantic

E, D, Y

UNK
(UNK; 402;
1980-2008)

0.8

Fin whale

Balaenopter
a physalus

Western
North
Atlantic

E, D, Y

6,802 (0.24;
5,573; 2021)

2.05

Sei whale

Balaenopter
a borealis

Nova Scotia

E, D, Y

6,292 (1.02;
3,098; 2021)

6.2

0.6

Minke
whale

Balaenopter
a
acutorostrata

Canadian
Eastern
Coastal

-, -, N

21,968
(0.31;
17,002;
2021)

9.4

Humpback
whale

Megaptera
novaeanglia
e

Gulf of
Maine

-, -, Y

1,396 (0;
1,380; 2016)

12.15

Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
Family Physeteridae
Sperm
whale

Physeter
macrocephal
us

North
Atlantic

E, D, Y

5,895 (0.29;
4,639; 2021)

9.28

0.2

-, -, N

93,233
(0.71;
54,433;
2021)

28

-, -, N

31,506
(0.28;
25,042;
2021)

0

28

Family Delphinidae
Atlantic
white-sided
dolphin

Lagenorhyn
chus acutus

Western
North
Atlantic

Atlantic
spotted
dolphin

Stenella
frontalis

Western
North
Atlantic

Bottlenose
dolphin7

Tursiops
truncatus

Western
North
Atlantic
Offshore

-, -, N

64,587
(0.24;
52,801;
2021)7

Long-finned
pilot whale8

Globicephal
a melas

Western
North
Atlantic

-, -, N

39,215 (0.3;
30,627;
2021)

5.7

Common
dolphin
(shortbeaked)

Delphinus
delphis

Western
North
Atlantic

-, -, N

93,100
(0.21;
59,817;
2021)

1,452

Risso’s
dolphin

Grampus
griseus

Western
North
Atlantic

-, -, N

44,067
(0.19;
30,662;
2021)

18

Family Phocoenidae (porpoises)

Harbor
porpoise

Phocoena
phocoena

Gulf of
Maine/Bay
of Fundy

-, -, N

85,765
(0.53;
56,420;
2021)

45

-, -, N

27,911
(0.20;
23,624;
2021)

1,512

4,570

-, -, N

61,336
(0.08;
57,637;
2018)

1,729

Order Carnivora – Superfamily Pinnipedia
Family Phocidae (earless seals)

Gray seal9

Halichoerus
grypus

Western
North
Atlantic

Harbor seal

Phoca
vitulina

Western
North
Atlantic

1 – Information on the classification of marine mammal species can be found on the web page for The
Society for Marine Mammalogy's Committee on Taxonomy
(https://www.marinemammalscience.org/science-and-publications/list-marine-mammal-speciessubspecies/; Committee on Taxonomy (2022)).
2 – ESA status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the
species is not listed under the ESA or designated as depleted under the MMPA. Under the MMPA, a
strategic stock is one for which the level of direct human-caused mortality exceeds PBR, is declining and
likely to be listed under the ESA within the foreseeable future, or listed under the ESA. A marine mammal
species or population is considered depleted under the MMPA if it is below its optimum sustainable
population (OSP) level, or is listed as endangered or threatened under the ESA.
3 –CV is the coefficient of variation; Nmin is the minimum estimate of stock abundance.
4 – These values, found in NMFS’s SARs, represent annual levels of human-caused mortality plus serious
injury from all sources combined (e.g., commercial fisheries, ship strike).
5 – The current SAR includes an estimated population (Nbest 340) based on sighting history through
November 2021 (Hayes et al., 2024). In October 2023, NMFS released a technical report identifying that
the North Atlantic right whale population size based on sighting history through 2022 was 356 whales, with
a 95 percent credible interval ranging from 346 to 363 (Linden, 2023).
6 – Total annual average observed North Atlantic right whale mortality during the period 2017–2021 was
7.1 animals and annual average observed fishery mortality was 4.6 animals. Numbers presented in this
table (27.2 total mortality and 176 fishery mortality) are 2016–2020 estimated annual means, accounting
for undetected mortality and serious injury.
7 – There are two morphologically and genetically distinct common bottlenose morphotypes, the Western
North Atlantic Northern Migratory Coastal stock and the Western North Atlantic Offshore stock. The
western North Atlantic offshore stock is primarily distributed along the outer shelf and slope from Georges
Bank to Florida during spring and summer and has been observed in the Gulf of Maine during late summer
and fall (Hayes et al. 2020), whereas the northern migratory coastal stock is distributed along the coast
between southern Long Island, New York, and Florida (Hayes et al., 2018). Given their distribution, only
the offshore stock of bottlenose dolphins is likely to occur in the project area.
8 – There are two pilot whale species, long-finned (Globicephala melas) and short-finned (Globicephala
macrorhynchus), with distributions that overlap in the latitudinal range of the SouthCoast Project (Hayes et
al., 2020; Roberts et al., 2016). Because it is difficult to differentiate between the two species at sea,
sightings, and thus the densities calculated from them, are generally reported together as Globicephala spp.
(Roberts et al., 2016; Hayes et al., 2020). However, based on the best available information, short-finned
pilot whales occur in habitat that is both further offshore on the shelf break and further south than the
project area (Hayes et al., 2020). Therefore, NMFS assumes that any take of pilot whales would be of longfinned pilot whales.
9 – NMFS’ stock abundance estimate (and associated PBR value) applies to the U.S. population only. Total
stock abundance (including animals in Canada) is approximately 451,431. The annual M/SI value given is
for the total stock.

As indicated above, all 16 species and stocks in table 5 temporally and spatially
co-occur with the activity to the degree that take is likely to occur. Five of the marine

mammal species for which take is requested are listed as endangered under the ESA:
North Atlantic right, blue, fin, sei, and sperm whales. In addition to what is included in
sections 3 and 4 of SouthCoast’s ITA application
(https://www.fisheries.noaa.gov/action/incidental-take-authorization-southcoast-windllc-construction-southcoast-wind-offshore-wind), the SARs
(https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammalstock-assessments), and NMFS’ website (https://www.fisheries.noaa.gov/speciesdirectory/marine-mammals), we provide further detail below informing the baseline for
select species (e.g., information regarding current UMEs and known important habitat
areas, such as Biologically Important Areas (BIAs;
https://oceannoise.noaa.gov/biologically-important-areas) (Van Parijs et al., 2015)).
There are no ESA-designated critical habitats for any species within the project area.
Under the MMPA, a UME is defined as “a stranding that is unexpected; involves
a significant die-off of any marine mammal population; and demands immediate
response” (16 U.S.C. 1421h(6)). As of May 20, 2024, four UMEs are active. Below we
include information for species that are listed under the ESA, have an active or recently
closed UME occurring along the Atlantic coast, or for which there is information
available related to areas of biological significance within the project area.
North Atlantic Right Whale
The North Atlantic right whale has been listed as Endangered since the ESA’s
enactment in 1973. The species was recently uplisted from Endangered to Critically
Endangered on the International Union for Conservation of Nature (IUCN) Red List of
Threatened Species (Cooke, 2020). The uplisting was due to a decrease in population size
(Pace et al., 2017), an increase in vessel strikes and entanglements in fixed fishing gear
(Daoust et al., 2017; Davis & Brillant, 2019; Knowlton et al., 2012; Knowlton et al.,
2022; Moore et al., 2021; Sharp et al., 2019), and a decrease in birth rate (Pettis et al.,

2021; Reed et al., 2022). There is a recovery plan (NOAA Fisheries, 2005) for the North
Atlantic right whale and, in November 2022, NMFS completed the 5-year review and
concluded that no change to this listing status is
warranted.(https://www.fisheries.noaa.gov/resource/document/north-atlantic-rightwhale-5-year-review). Designated by NMFS as a Species in the Spotlight, the North
Atlantic right whale is considered among the species with the greatest risk of extinction
in the near future (https://www.fisheries.noaa.gov/topic/endangered-speciesconservation/species-in-the-spotlight).
The North Atlantic right whale population had only a 2.8-percent recovery rate
between 1990 and 2011 and an overall abundance decline of 23.5 percent from 20112019 (Hayes et al., 2023). Since 2010, the North Atlantic right whale population has been
in decline; however, the sharp decrease observed from 2015 to 2020 appears to have
slowed, though the North Atlantic right whale population continues to experience annual
mortalities above recovery thresholds (Pace et al., 2017; Pace et al., 2021; Linden, 2023).
North Atlantic right whale calving rates dropped from 2017 to 2020 with zero births
recorded during the 2017-2018 season. The 2020-2021 calving season had the first
substantial calving increase in 5 years with 20 calves born, followed by 15 calves during
the 2021-2022 calving season and 12 births in the 2022-2023 calving season. As of May
20, 2024, the 2023-2024 calving season includes 19 births. However, mortalities continue
to outpace births, including three calf mortalities/presumed mortalities during the 2024
calving season, and the best estimates indicate fewer than 70 reproductively active
females remain in the population (Hayes et al., 2024). North Atlantic right whale total
annual mortality and serious injury (M/SI) estimates have fluctuated in recent years, as
presented in annual stock assessment reports. The estimate for 2022 (31.2) was a marked
increase over the previous year. In the 2022 SARs, Hayes et al., (2023) report the total
annual North Atlantic right whale mortality increased from 8.1 (which represents 2016-

2020) to 31.2 (which represents 2015-2019), however, this updated estimate also
accounted for undetected mortality and serious injury (Hayes et al., 2024). Presently, the
best available peer-reviewed population estimate for North Atlantic right whales is 340
per the draft 2023 SARs (Hayes et al., 2024). Approximately, 42 percent of the
population is known to be in reduced health (Hamilton et al., 2021) likely contributing to
smaller body sizes at maturation, making them more susceptible to threats and reducing
fecundity (Moore et al., 2021; Reed et al., 2022; Stewart et al., 2022; Pirotta et al., 2024).
Body size is generally positively correlated to reproductive potential. Pirrota et al. (2024)
found North Atlantic right whale body size was strongly associated with the probability
of giving birth to a calf, such that smaller body size was associated with lower
reproductive output. In turn, shorter females that do calve tend to produce offspring with
a limited maximum size, likely through a combination of genetics and the influence of
body condition during gestation and weaning (Pirotta et al., 2024). When combined with
other factors (e.g., health deterioration due to sublethal effects of entanglement), this
feedback loop has led to a decrease in overall body length and fecundity over the past 50
years (Pirotta et al., 2023; Pirotta et al., 2024).
Since 2017, dead, seriously injured, sublethally injured, or ill North Atlantic right
whales along the United States and Canadian coasts have been documented, necessitating
a UME declaration and investigation. The leading category for the cause of death for this
ongoing UME is “human interaction,” specifically from entanglements or vessel strikes.
As of May 20, 2024, there have been 39 confirmed mortalities (dead, stranded, or
floaters), 1 pending mortality, and 34 seriously injured free-swimming whales for a total
of 74 whales. The UME also considers animals with sublethal injury or illness (i.e.,
“morbidity”; n=51) bringing the total number of whales in the UME from 71 to 122.
More information about the North Atlantic right whale UME is available online at

https://www.fisheries.noaa.gov/national/marine-life-distress/2017-2023-north-atlanticright-whale-unusual-mortality-event.
The project area both spatially and temporally overlaps the migratory corridor
BIA, within which a portion of the North Atlantic right whale population migrates south
to calving grounds, generally in November and December, followed by a northward
migration into feeding areas east and north of the project area in March and April
(LaBrecque et al., 2015; Van Parijs et al., 2015). While the Project does not overlap
previously identified critical feeding habitat or a feeding BIA, it is located within a
recently described important feeding area south of Martha’s Vineyard and Nantucket,
primarily along the western side of Nantucket Shoals (Kraus et al., 2016; O’Brien et al.,
2022, Quintano-Rizzo et al., 2021). Finally, the Project overlaps the currently established
November 1 through April 30th Block Island Seasonal Management Area (SMA) (73 FR
60173, October 10, 2008) and the proposed November 1 through May 30 Atlantic
Seasonal Speed Zone (87 FR 46921, August 1, 2022), which may be used by North
Atlantic right whales for various activities, including feeding and migration. Due to the
current status of North Atlantic right whales and the overlap of the proposed Project with
areas of biological significance (i.e., a migratory corridor, feeding habitat, SMA), the
potential impacts of the proposed SouthCoast project on North Atlantic right whales
warrant particular attention.
Recent research indicates that the overall understanding of North Atlantic right
whale movement patterns remains incomplete, and not all of the population undergoes a
consistent annual migration (Davis et al., 2017; Gowan et al., 2019; Krzystan et al.,
2018; O’Brien et al., 2022; Estabrook et al., 2022; Davis et al., 2023; van Parijs et al.,
2023). The seasonal migration between northern feeding grounds, mating grounds, and
southern calving grounds off Florida and Georgia involves a part of the population while
the remaining whales overwinter in other widely distributed areas (Morano et al., 2012,

Cole et al., 2013, Bort et al., 2015, Davis et al., 2017). The results of multistate
temporary emigration capture-recapture modeling, based on sighting data collected over
the past 22 years, indicate that non-calving females may remain in the feeding habitat
during winter in the years preceding and following the birth of a calf to increase their
energy stores (Gowen et al., 2019). O’ Brien et al. (2022) hypothesized that North
Atlantic right whales might gain an energetic advantage by summertime foraging in
southern New England on sub-optimal prey patches rather than engaging in the extensive
migration required to access more high-quality prey patches in northern feeding habitats
(e.g., Gulf of St. Lawrence). These observations of transitions in North Atlantic right
whale habitat use, variability in seasonal presence in identified core habitats, and
utilization of habitat outside of previously focused survey effort prompted the formation
of a NMFS’ Expert Working Group, which identified current data collection efforts, data
gaps, and provided recommendations for future survey and research efforts (Oleson et al.,
2020).
North Atlantic right whale distribution and demography has been shown to
depend on the distribution and density of zooplankton, which varies spatially and
temporily. North Atlantic right whales feed on high-density patches of different
zooplankton species (e.g., calanoid copepods, Centrophages spp., Pseudocalanus spp.),
but primarily on aggregations of late-stage Calanus finmarchicus, a species whose
seasonal availability and distribution has changed both spatially and temporally over the
last decade due to an oceanographic regime shift that has ultimately been linked to
climate change (Meyer-Gutbrod et al., 2021; Meyer-Gutbrod et al., 2023; Record et al.,
2019; Sorochan et al., 2019). This distribution change in prey availability has led to shifts
in North Atlantic right whale habitat-use patterns over the same time period (Davis et al.,
2020; Meyer-Gutbrod et al., 2022; Quintano-Rizzo et al., 2021; O'Brien et al., 2022) with
reduced use of foraging habitats in the Great South Channel and Bay of Fundy and

increased use of habitat within Cape Cod Bay (Stone et al., 2017; Mayo et al., 2018;
Ganley et al., 2019; Record et al., 2019; Meyer-Gutbrod et al., 2021; O’Brien et al.,
2022; Davis et al., 2017). North Atlantic right whales have recolonized areas that have
not had large numbers of right whales since the whaling era, likely in response to changes
in zooplankton distribution (e.g., Gulf of St. Lawrence, Simard et al., 2019; Nantucket
Shoals, e.g., Kraus et al., 2016; Quintana-Rizzo et al., 2021; O’Brien et al., 2022; Davis
et al., 2023; Ganley et al., 2022; Van Parijs et al., 2023).
Pendleton et al. (2022) found that peak use of North Atlantic right whale foraging
habitat in Cape Cod Bay, north of the Lease Area, has shifted over the past 20 years to
later in the spring, likely due to variations in seasonal conditions. However, initial yearly
sightings of individual North Atlantic right whales in Cape Cod Bay have started earlier
in the year concurrent with climate changes, indicating that their migratory movements
between habitats may be cued by changes in regional water temperature (Pendleton et al.,
2022). These changes have the potential to lead to temporal misalignment between North
Atlantic right whale seasonal arrival to this foraging habitat and the availability of the
zooplankton prey (Ganley et al., 2022).
North Atlantic right whale use of habitats such as in the Gulf of St. Lawrence and
East Coast mid-Atlantic waters of the U.S. have also increased over time (Davis et al.,
2017; Davis and Brillant, 2019; Simard et al., 2019; Crowe et al., 2021; Quintana-Rizzo
et al., 2021). Using passive acoustic data collected from 2010-2018 throughout the Gulf
of St. Lawrence, a foraging habitat more recently exploited by a significant portion of the
population, Simard et al. (2019) documented the presence of North Atlantic right whales
for an unexpectedly extended period at four out of the eight recording stations, from the
end of April through January, and found that occurrence peaked in the area from August
through November each year. In 2015, the mean daily occurrence of North Atlantic right
whales in the feeding grounds off Gaspé, located on the west side of the upper Gulf of St.

Lawrence, quadrupled compared to 2011-2014 (Simard et al., 2019). However, there is
concern that prey biomass in the Gulf of St. Lawrence may be insufficient in most years
to support successful reproduction of North Atlantic right whales (Gavrilchuk et al.,
2021), which could impel whales to seek out alternative foraging habitats. Based on highresolution climate models, Ross et al., (2021) projected that the redistribution of North
Atlantic right whales throughout the western North Atlantic Ocean will continue at least
through the year 2050 (Ross et al., 2021).
Within the past decade in southern New England, increasing year-round
observations of North Atlantic right whales have occurred and include documentation of
social behaviors and foraging in all seasons, making it the only known winter foraging
habitat (Kraus et al., 2016; Leiter et al., 2017; Stone et al., 2017; Quintana-Rizzo et al.,
2021; O’Brien et al., 2022; Van Parijs et al., 2023; Davis et al., 2023). Both visual and
acoustic lines of evidence demonstrate the year-round presence of North Atlantic right
whales in southern New England (Kraus et al., 2016; Quintana-Rizzo et al. 2021;
Estabrook et al., 2022; O’Brian et al., 2022; Davis et al., 2023; van Parijs et al., 2023).
Right whales were sighted in winter and spring during aerial surveys conducted in the
RI/MA and MA WEAs from 2011-2015 and 2017-2019 (Kraus et al., 2016; QuintanaRizzo et al., 2021; O’Brien et al., 2022). There was not significant variability in sighting
rates among years, indicating consistent annual seasonal use of the area by North Atlantic
right whales. Despite the lack of visual detection in most summer and fall months, right
whales were acoustically detected in 30 out of the 36 recorded months (Kraus et al.,
2016). Since 2017, whales have been sighted in southern New England nearly every
month with peak sighting rates between late winter and spring. Model outputs in
Quintana-Rizzo et al. (2021) suggested that 23 percent of the right whale population is
present from December through May, and the mean residence time tripled between 20112015 and 2017-2019 to an average of 13 days during these same months.

Based on analyses of PAM data collected at recording sites in the RI/MA and MA
WEAs from 2011-2015, Estabrook et al. (2022) report that North Atlantic right whale
upcall detections occurred throughout both WEAs in all seasons (during 34 of the 37
surveyed months) but predominantly in the late winter and spring, which aligns with
visual observations (Kraus et al., 2016; Quintana-Rizzo et al., 2021). Among the
recording locations in southern New England, detections were most frequent on acoustic
recorders along the eastern side of the MA WEA (Estabrook et al., 2022). December
through April had higher presence while June through September had lower presence.
Winter (December-April) had the highest presence (75 percent array-days, n=193), and
summer (June-Sep had the lowest presence (10 percent array-days, n = 27). Spring and
autumn were similar, where approximately half of the array-days had upcall detections.
The mean daily call rate for days upcalls were detected was highest in January, February,
and March, accounting for 72 percent of all detected upcalls, and calling rates were
significantly different among seasons (Estabrook et al., 2022). Upcalls were detected on
41 percent of the 1,023 recording days in the MA WEA and on only 24 percent of the
recording days in the RI-MA WEA. Similarly, both van Parijs et al. (2023) and. Davis et
al. (2023) evaluated a 2020-2022 PAM dataset collected using seven acoustic recorders
deployed in the RI/MA and MA WEAs, two deployed on Cox Ledge (i.e., the northwest
side of the RI/MA WEA), four along the eastern side of the MA WEA (along a transect
approximately parallel to the 30-m isobath on the west side of Nantucket Shoals, the
same bathymetric feature used to define the NARW EMA), and one positioned towards
the center of Nantucket Shoals, and noted that North Atlantic right whales were
acoustically detected at all seven sites from September through May, with sporadic
presence in June through August. Upcalls were detected at each location nearly every
week, annually, with detections steadily increasing through October, reaching
consistently high levels from November through April, steadily declining in May, and

remaining low throughout summer. Upcalls were detected nearly 7 days a week
December through March at the two locations nearest the Lease Area along the eastern
edge of the MA WEA (NS01 and NS02, see Figures 1 and 2 in Davis et al., 2023).
Comprehensively, acoustic and visual observations of North Atlantic right whales in
southern New England indicate that whales occur year-round but more frequently in
winter and spring and in eastern (versus western) southern New England.
While Nantucket Shoals is not designated as critical North Atlantic right whale
habitat, its importance as a foraging habitat is well established (Leiter et al., 2017;
Quintana-Rizzo et al., 2021; Estabrook et al., 2022; O’Brien et al., 2022). However,
studies focusing on the link between right whale habitat use and zooplankton in the
Nantucket Shoals region are limited (National Academy of Sciences, 2003). The supply
of zooplankton to the Nantucket Shoals region is dependent on advection from sources
outside the Shoals via regional circulation, but zooplankton aggregation is presumably
dependent on local physical processes and zooplankton behavior (National Academy of
Sciences, 2023). Nantucket Shoals’ unique oceanographic and bathymetric features,
including the persistent tidal front described in the Specified Geographical Area section,
help sustain year-round elevated phytoplankton biomass and aggregate zooplankton prey
for North Atlantic right whales (White et al., 2020; Quintana-Rizzo et al., 2021). O’Brien
et al. (2022) hypothesize that North Atlantic right whale southern New England habitat
use has increased in recent years (i.e., over the last decade) as a result of either, or a
combination of, a northward shift in prey distribution (thus increasing local prey
availability) or a decline in prey in other abandoned feeding areas (e.g., Gulf of Maine),
both induced by climate change. Pendleton et al. (2022) characterize southern New
England as a “waiting room” for North Atlantic right whales in the spring, providing
sufficient, although sub-optimal, prey choices while North Atlantic right whales wait for
Calanus finmarchicus supplies in Cape Cod Bay (and other primary foraging grounds

like the Great South Channel) to optimize as seasonal primary and secondary production
progresses. Throughout the year, southern New England provides opportunities for North
Atlantic right whales to capitalize on C.finmarchicus blooms or alternative prey (e.g.,
Pseudocalanus elongatus and Centropages spp., found in greater concentrations than
C.finmarchicus in winter), although likely not to the extent provided seasonally in more
well-understood feeding habitats like Cape Cod Bay in late spring or the Great South
Channel (O’Brien et al., 2022). Although extensive data gaps, highlighted in a recent
report by the National Academy of Sciences (NAS, 2023), have prevented development
of a thorough understanding of North Atlantic right whale foraging ecology in the
Nantucket Shoals region, it is clear that the habitat was historically valuable to the
species, given that the whaling industry capitalized on consistent right whale occurrence
there and has again become increasingly so over the last decade.
Humpback Whale
Humpback whales were listed as endangered under the Endangered Species
Conservation Act (ESCA) in June 1970. In 1973, the ESA replaced the ESCA, and
humpbacks continued to be listed as endangered. On September 8, 2016, NMFS divided
the once single species into 14 distinct population segments (DPS), removed the specieslevel listing, and, in its place, listed four DPSs as endangered and one DPS as threatened
(81 FR 62259; September 8, 2016). The remaining nine DPSs were not listed. The West
Indies DPS, which is not listed under the ESA, is the only DPS of humpback whales that
is expected to occur in the project area. Bettridge et al. (2015) estimated the size of the
West Indies DPS population at 12,312 (95 percent confidence interval (CI) 8,688-15,954)
whales in 2004-2005, which is consistent with previous population estimates of
approximately 10,000-11,000 whales (Stevick et al., 2003; Smith et al., 1999) and the
increasing trend for the West Indies DPS (Bettridge et al., 2015).

The project area does not overlap any ESA-designated critical habitat, BIAs, or
other important areas for the humpback whales. A humpback whale feeding BIA extends
throughout the Gulf of Maine, Stellwagen Bank, and Great South Channel from May
through December, annually (LeBrecque et al., 2015). However, this BIA is located
further east and north of, and thus, does not overlap the project area.
Kraus et al. (2016) visually observed humpback whales in the RI/MA and MA
WEAs and surrounding areas during all seasons, but most frequently during spring and
summer months, particularly from April to June. Concurrently collected acoustic data
(from 2011 through 2015) indicated that this species may be present within the RI/MA
WEA year-round, with the highest rates of acoustic detections in the winter and spring
(Kraus et al., 2016). Analyzing PAM data collected at six acoustic recording locations
from January 2020 through November 2022, van Parijs et al. (2023) assessed daily,
weekly, and monthly patterns in humpback whale acoustic occurrence within the RI/MA
and MA WEAs, and found patterns similar to those described in Kraus et al. (2016).
Humpback whale vocalizations were detected in all months, although most commonly
from November through June, annually, at recording sites in eastern southern New
England (near Nantucket Shoals) (van Parijs et al. 2023). Detections at recorder locations
in western southern New England, near Cox Ledge, were even more frequent than at the
eastern southern New England recorder locations, indicating humpback whales were
present on a nearly daily basis in all months except September and October.
In New England waters, feeding is the principal activity of humpback whales, and
their distribution in this region has been largely correlated to abundance of prey species,
although behavior and bathymetry are factors influencing foraging strategy (Payne et al.,
1986; 1990). Humpback whales are frequently piscivorous when in New England waters,
feeding on herring (Clupea harengus), sand lance (Ammodytes spp.), and other small
fishes, as well as euphausiids in the northern Gulf of Maine (Paquet et al., 1997). During

winter, the majority of humpback whales from North Atlantic feeding areas (including
the Gulf of Maine) mate and calve in the West Indies, where spatial and genetic mixing
among feeding groups occurs, though significant numbers of animals are found in midand high-latitude regions at this time and some individuals have been sighted repeatedly
within the same winter season, indicating that not all humpback whales migrate south
every winter (Hayes et al., 2018).
Since January 2016, elevated humpback whale mortalities have occurred along
the Atlantic coast from Maine to Florida. This event was declared a UME in April 2017.
Partial or full necropsy examinations have been conducted on approximately half of the
212 known cases (as of January 5, 2024). Of the whales examined (approximately 90),
about 40 percent had evidence of human interaction either from vessel strike or
entanglement. While a portion of the whales have shown evidence of pre-mortem vessel
strike, this finding is not consistent across all whales examined and more research is
needed. NOAA is consulting with researchers that are conducting studies on the
humpback whale populations, and these efforts may provide information on changes in
whale distribution and habitat use that could provide additional insight into how these
vessel interactions occurred. More information is available at:
https://www.fisheries.noaa.gov/national/marine-life-distress/active-and-closed-unusualmortality-events.
Since December 1, 2022, the number of humpback strandings along the midAtlantic coast has been elevated. In some cases, the cause of death is not yet known. In
others, vessel strike has been deemed the cause of death. As the humpback whale
population has grown, they are seen more often in the Mid-Atlantic. These whales may
be following their prey (small fish) which were reportedly close to shore in the 20222033 winter. Changing distributions of prey impact larger marine species that depend on
them and result in changing distribution of whales and other marine life. These prey also

attract fish that are targeted by recreational and commercial fishermen, which increases
the number of boats and amount of fishing gear in these areas. This nearshore movement
increases the potential for anthropogenic interactions, particularly as the increased
presence of whales in areas traveled by boats of all sizes increases the risk of vessel
strikes.
Minke Whale
Minke whales are common and widely distributed throughout the U.S. Atlantic
Exclusive Economic Zone (EEZ) (Cetacean and Turtle Assessment Program (CETAP),
1982; Hayes et al., 2022), although their distribution has a strong seasonal component.
Individuals have often been detected acoustically in shelf waters from spring to fall and
more often detected in deeper offshore waters from winter to spring (Risch et al., 2013).
Minke whales are abundant in New England waters from May through September
(Pittman et al., 2006; Waring et al., 2014), yet largely absent from these areas during the
winter, suggesting the possible existence of a migratory corridor (LaBrecque et al.,
2015). A migratory route for minke whales transiting between northern feeding grounds
and southern breeding areas may exist to the east of the Lease Area, as minke whales
may track warmer waters along the continental shelf while migrating (Risch et al., 2014).
Risch et al. (2014) suggests the presence of a minke whale breeding ground offshore of
the southeastern U.S. during the winter.
There are two minke whale feeding BIAs from March through November,
annually, identified in the southern and southwestern sections of the Gulf of Maine,
including multiple habitats: Georges Bank, the Great South Channel, Cape Cod Bay and
Massachusetts Bay, Stellwagen Bank, Cape Anne, and Jeffreys Ledge (LeBrecque et al.,
2015). However, these BIAs do not overlap the Lease Area or ECCs, as they are located
further east and north.

Although minke whales are sighted in every season in southern New England
(O’Brien et al., 2022), minke whale use of the area is highest during the months of March
through September (Kraus et al., 2016; O’Brien et al., 2023), and the species is largely
absent in the winter (Risch et al., 2013; Hayes et al., 2023). Large feeding aggregations
of humpback, fin, and minke whales have been observed during the summer (O’Brien et
al., 2023), suggesting southern New England may serve as a supplemental feeding
grounds for these species. Aerial survey data indicate that minke whales are the most
common baleen whale in the RI/MA & MA WEAs (Kraus et al.,2016; Quintana and
Kraus, 2019; O’Brien et al., 2021a, b). Surveys also reported a shift in the greatest
seasonal abundance of minke whales from spring (2017-2018) (Quintana and Kraus,
2019) to summer (2018-2019 and 2020-2021) (O’Brien et al., 2021a, b). Through
analysis of PAM data collected in southern New England from January 2020 through
November 2022, Van Parijs et al. (2023) detected minke whales at all seven passive
acoustic recorder deployment sites, primarily from March through June and August
through early December. Additional detections occurred in January on Cox Ledge and
near the northeast portion of the Lease Area.
Elevated minke whale mortalities detected along the Atlantic coast from Maine
through South Carolina resulted in the declaration of an on-going UME in 2017. As of
May 20, 2024, a total of 169 minke whales have stranded during this UME. Full or partial
necropsy examinations were conducted on more than 60 percent of the whales.
Preliminary findings show evidence of human interactions or infectious disease, but these
findings are not consistent across all of the minke whales examined, so more research is
needed. More information is available at:
https://www.fisheries.noaa.gov/national/marine-life-distress/2017-2022-minke-whaleunusual-mortality-event-along-atlantic-coast.

Sei Whale
The Nova Scotia stock of sei whales can be found in deeper waters of the
continental shelf edge of the eastern United States and northeastward to south of
Newfoundland (Mitchell, 1975; Hain et al., 1985; Hayes et al., 2022). Sei whales have
been detected acoustically along the Atlantic Continental Shelf and Slope from south of
Cape Hatteras, North Carolina to the Davis Strait, and acoustic occurrence has been
increasing in the mid-Atlantic region since 2010 (Davis et al., 2020).
Sei whales are largely planktivorous, feeding primarily on euphausiids and
copepods (Hayes et al., 2023). Although their migratory movements are not well
understood, sei whales are believed to migrate between feeding grounds in temperate and
subpolar regions to wintering grounds in lower latitudes (Kenney and Vigness-Raposa,
2010; Hayes et al., 2020). Through an analysis of PAM data collected from X to X, Davis
et al. (2020) determined that peak call detections occurred in northern latitudes during
summer, ranging from Southern New England through the Scotian Shelf. During spring
and summer, the stock is mainly concentrated in these northern feeding areas, including
the Scotian Shelf (Mitchell and Chapman, 1977), the Gulf of Maine, Georges Bank, the
Northeast Channel, and south of Nantucket (CETAP, 1982; Kraus et al., 2016; Roberts et
al., 2016; Palka et al., 2017; Cholewiak et al., 2018; Hayes et al., 2022). While sei
whales generally occur offshore, individuals may also move into shallower, more inshore
waters to pursue prey (Payne et al., 1990; Halpin et al., 2009; Hayes et al., 2023).
A sei whale feeding BIA occurs in New England waters from May through
November (LaBrecque et al., 2015). This BIA is located over 100 km to the east and
north of the project area and is not expected to be impacted by the Project activities.
Persistent year-round detections in southern New England and the New York
Bight indicate that sei whales may utilize these habitats to a greater extent than
previously thought (Hayes et al., 2023). The results of an analysis of acoustic data

collected from January 2020 through November 2022 indicate that sei whale acoustic
presence in southern New England peaks in late winter and early spring (February to
May), and is otherwise sporadic throughout the rest of the year (van Parijs et al., 2023).
Fewer detections occurred at the two sites on Cox Ledge to the west compared to the sites
located near the eastern edge of the MA WEA, potentially indicating sei whales prefer
specific habitat within southern New England (Figure 1 in van Parijs et al., 2023).
Fin Whale
Fin whales frequently occur in the waters of the U.S. Atlantic Exclusive EEZ,
principally from Cape Hatteras, North Carolina northward and are distributed in both
continental shelf and deep-water habitats (Hayes et al., 2023). Although fin whales are
present north of the 35-degree latitude region in every season and are broadly distributed
throughout the western North Atlantic for most of the year, densities vary seasonally
(Edwards et al., 2015; Hayes et al., 2023). Observations of fin whales indicate that they
typically feed in the Gulf of Maine and the waters surrounding New England, but their
mating and calving (and general wintering) areas are largely unknown (Hain et al., 1992;
Hayes et al., 2021). Acoustic detections of fin whale singers augment and confirm these
conclusions for males drawn from visual sightings. Recordings from Massachusetts Bay,
New York Bight, and deep-ocean areas have detected some level of fin whale singing
from September through June (Watkins et al., 1987; Clark and Gagnon, 2002; Morano et
al., 2012). These acoustic observations from both coastal and deep-ocean regions support
the conclusion that male fin whales are broadly distributed throughout the western North
Atlantic for most of the year (Hayes et al., 2019).
New England waters represent a major feeding ground for fin whales. A relatively
small fin whale feeding BIA (2,933 km2), active from March through October, is located
approximately 34 km to the west of the Lease Area, offshore of Montauk Point, New
York (Hain et al., 1992; LaBrecque et al. 2015). A portion of the planned Brayton Point

ECC route traces the northeast edge of the BIA. Although the Lease Area does not
overlap this BIA, should SouthCoast decide to use vibratory pile driving to install
foundations for Project 2, it’s possible that the resulting Level B harassment zone may
extend into the southeastern edge of the BIA during installation of the foundations on the
northwest edge of the Lease Area. A separate larger year-round feeding BIA (18,015
km2) located far to the northeast in the southern Gulf of Maine does not overlap with the
project area and would, thus, not be impacted by project activities.
Kraus et al. (2016) suggest that, compared to other baleen whale species, fin
whales have a high multi-seasonal relative abundance in the RI/MA & MA WEAs and
surrounding areas. This species was observed primarily in the offshore (southern) regions
of the RI/MA & MA WEAs during spring and was found closer to shore (northern areas)
during the summer months (Kraus et al., 2016). Although fin whales were largely absent
from visual surveys in the RI/MA & MA WEAs in the fall and winter months (Kraus et
al., 2016), acoustic data indicate that this species is present in the RI/MA & MA WEAs
during all months of the year, although to a much lesser extent in summer (Morano et al.,
2012; Muirhead et al., 2018; Davis et al., 2020). More recent surveys have documented
fin whales throughout winter, spring, and summer (O’Brien et al., 2020; 2021; 2022;
2023) with the greatest abundance occurring during the summer and clustered in the
western portion of the WEAs (O’Brien et al., 2023). Most recently, from January 2020
through November 2022, van Parijs et al. (2023) fin whales were acoustically detected at
all seven recording sites in southern New England, which included two locations on Cox
Ledge (western southern New England) and five locations along the east side of the MA
WEA (along the western side of Nantucket Shoals). Similar to observations of humpback
whale acoustic occurrence, fin whales were detected more frequently near Cox Ledge
than at locations closer to Nantucket Shoals (van Paris et al. (2023). Daily acoustic
presence occurred for the majority of the year, most intensively in the fall, yet fin whales

were essentially acoustically absent at all recorder locations from April through August
(van Parijs et al., 2023). Although fin whale distribution is not fully understood, we
expect that this period lacking acoustic detections corresponds to fin whale northward
movement in late spring towards higher-latitude foraging grounds.
Blue Whale
Much is unknown about the blue whale populations. The last minimum
population abundance was estimated at 402, but insufficient data prevent determining
population trends (Hayes et al., 2023). The total level of human caused mortality and
serious injury is unknown, but it is believed to be insignificant and approaching a zero
mortality and serious injury rate (Hayes et al., 2019). There are no blue whale BIAs or
ESA-protected critical habitats identified in the project area or along the U.S. Eastern
Seaboard. There is no UME for blue whales.
In the North Atlantic Ocean, blue whales range from the subtropics to the
Greenland Sea. The North Atlantic Stock includes animals utilizing mid-latitude (North
Carolina coastal and open ocean) to Arctic (Newfoundland and Labrador) waters. Blue
whales do not regularly occur within the U.S. EEZ, preferring offshore habitat with water
depths of 328 ft (100 m) or more (Waring et al., 2011). The most frequent sightings occur
at higher latitudes off eastern Canada in the Gulf of St. Lawrence, with the greatest
concentration of this species in the St. Lawrence Estuary (Comtois et al., 2010; Lesage et
al., 2007; Hayes et al., 2019). They often are found near the continental shelf edge where
upwelling produces concentrations of krill, their main prey species (Yochem and
Leatherwood, 1985; Fiedler et al., 1998; Gill et al., 2011).
Blue whales are uncommon in New England coastal waters. Visual surveys
conducted in 2018-2020, did not result in any sightings of blue whales in MA and RI/MA
WEAs (O’Brien et al., 2021a; O’Brien et al., 2021b). However, Kraus et al. (2016)
conducted aerial and acoustic surveys between 2011-2015 in the MA and RI/MA WEAs

and surrounding areas and, although blue whales were not visually observed, they were
infrequently acoustically detected during winter. A 2008 study detected blue whale calls
in offshore areas of the New York Bight, south of southern New England, on 28 out of
258 days of recordings (11 percent of recording days), mostly during winter (Muirhead et
al., 2018). Van Paris et al. (2023) detected a small number of blue whale calls in southern
New England in January and February, although the species was otherwise acoustically
absent. Given the long-distance propagation characteristics of low-frequency blue whale
vocalizations, it’s possible blue whale calls detected in southern New England originated
from distant whales. Together, these data suggest that blue whales are rarely present in
the MA and RI/MA WEAs.
Sperm Whale
Sperm whales can be found throughout the world’s oceans. They can be found
near the edge of the ice pack in both hemispheres and are also common along the equator.
The North Atlantic stock is distributed mainly along the continental shelf-edge, over the
continental slope, and mid-ocean regions, where they prefer water depths of 600 m (1,969
ft) or more and are less common in waters <300 m (984 ft) deep (Waring et al., 2015;
Hayes et al., 2020). In the winter, sperm whales are observed east and northeast of Cape
Hatteras. In the spring, sperm whales are more widely distributed throughout the MidAtlantic Bight and southern portions of George’s Bank (Hayes et al., 2020). In the
summer, sperm whale distribution is similar to the spring, but they are more widespread
in Georges Bank and the Northeast Channel region and are also observed inshore of the
100-m (328-ft) isobath south of New England (Hayes et al., 2020). Sperm whale
occurrence on the continental shelf in areas south of New England is at its highest in the
fall (Hayes et al., 2020). Between April 2020 and December 2021, there was 1 sighting
of 2 individual sperm whales recorded during HRG surveys conducted within the area
surrounding the Lease Area and Falmouth ECC.

Kraus et al. (2016) observed sperm whales four times in the RI/MA and MA
WEAs and surrounding areas in the summer and fall during the 2011–2015 NLPSC aerial
survey. Sperm whales, traveling singly or in groups of three or four, were observed three
times in August and September of 2012, and once in June of 2015. Effort-weighted
average sighting rates could not be calculated. The frequency of sperm whale clicks
exceeded the maximum frequency of PAM equipment used in the Kraus et al. (2016)
study, so no acoustic data are available for this species from that study. Sperm whales
were observed only once in the MA WEA and nearby waters during the 2010–2017
AMAPPS surveys (NEFSC and SEFSC 2011, 2012, 2013, 2014, 2015, 2016, 2017,
2018). This occurred during a summer shipboard survey in 2016.
Phocid Seals
Harbor and gray seals have experienced two UMEs since 2018, although one was
recently closed (2022 Pinniped UME in Maine) and closure of the second, described
here, is pending. Beginning in July 2018, elevated numbers of harbor seal and gray seal
mortalities occurred across Maine, New Hampshire, and Massachusetts. Additionally,
stranded seals have shown clinical signs as far south as Virginia, although not in elevated
numbers, therefore the UME investigation encompassed all seal strandings from Maine to
Virginia. A total of 3,152 reported strandings (of all species) occurred from July 1, 2018,
through March 13, 2020. Full or partial necropsy examinations were conducted on some
of the seals and samples were collected for testing. Based on tests conducted thus far, the
main pathogen found in the seals is phocine distemper virus. NMFS is performing
additional testing to identify any other factors that may be involved in this UME, which is
pending closure. Information on this UME is available online at:
https://www.fisheries.noaa.gov/new-england-mid-atlantic/marine-life-distress/20182020-pinniped-unusual-mortality-event-along.

Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals underwater,
and exposure to anthropogenic sound can have deleterious effects. To appropriately
assess the potential effects of exposure to sound, it is necessary to understand the
frequency ranges marine mammals are able to hear. Current data indicate that not all
marine mammal species have equal hearing capabilities (e.g., Richardson et al., 1995;
Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. (2007)
recommended that marine mammals be divided into functional hearing groups based on
directly measured or estimated hearing ranges on the basis of available behavioral
response data, audiograms derived using auditory evoked potential techniques,
anatomical modeling, and other data. Note that no direct measurements of hearing ability
have been successfully completed for mysticetes (i.e., low-frequency cetaceans).
Subsequently, NMFS (2018) described generalized hearing ranges for these marine
mammal hearing groups. Generalized hearing ranges were chosen based on the
approximately 65 decibel (dB) threshold from the normalized composite audiograms,
with the exception for lower limits for low-frequency cetaceans where the lower bound
was deemed to be biologically implausible and the lower bound from Southall et al.
(2007) retained. Marine mammal hearing groups and their associated hearing ranges are
provided in table 6.

Table 6 – Marine Mammal Hearing Groups (NMFS, 2018)
Hearing Group

Generalized Hearing Range*

Low-frequency (LF) cetaceans
(baleen whales)

7 Hz to 35 kHz

Mid-frequency (MF) cetaceans
(dolphins, toothed whales, beaked whales,
bottlenose whales)

150 Hz to 160 kHz

High-frequency (HF) cetaceans
(true porpoises, Kogia, river dolphins,
cephalorhynchid, Lagenorhynchus cruciger & L.
australis)

275 Hz to 160 kHz

Phocid pinnipeds (PW) (underwater)
(true seals)

50 Hz to 86 kHz

* Represents the generalized hearing range for the entire group as a composite (i.e., all species within the
group), where individual species’ hearing ranges are typically not as broad. Generalized hearing range
chosen based on ~65 dB threshold from normalized composite audiogram, with the exception for lower
limits for LF cetaceans (Southall et al. 2007) and PW pinniped (approximation).

The pinniped functional hearing group was modified from Southall et al. (2007)
on the basis of data indicating that phocid species have consistently demonstrated an
extended frequency range of hearing compared to otariids, especially in the higher
frequency range (Hemilä et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 2013).
For more detail concerning these groups and associated frequency ranges, please see
NMFS (2018) for a review of available information.
NMFS notes that in 2019, Southall et al. recommended new names for hearing
groups that are widely recognized. However, this new hearing group classification does
not change the weighting functions or acoustic thresholds (i.e., the weighting functions
and thresholds in Southall et al. (2019) are identical to NMFS 2018 Revised Technical
Guidance). When NMFS updates our Technical Guidance, we will be adopting the
updated Southall et al. (2019) hearing group classification.

Acoustic Habitat
Acoustic habitat is defined as distinguishable soundscapes inhabited by individual
animals or assemblages of species, inclusive of both the sounds they create and those
they hear (NOAA, 2016). All of the sound present in a particular location and time,
considered as a whole, comprises a “soundscape” (Pijanowski et al., 2011). When
examined from the perspective of the animals experiencing it, a soundscape may also be
referred to as “acoustic habitat” (Clark et al., 2009, Moore et al., 2012, Merchant et al.,
2015). High value acoustic habitats, which vary spectrally, spatially, and temporally,
support critical life functions (feeding, breeding, and survival) of their inhabitants. Thus,
it is important to consider acute (e.g., stress or missed feeding/breeding opportunities)
and chronic effects (e.g., masking) of noise on important acoustic habitats. Effects that
accumulate over long periods can ultimately result in detrimental impacts on the
individual, stability of a population, or ecosystems that they inhabit.
Potential Effects of the Specified Activities on Marine Mammals and Their Habitat
This section includes a summary and discussion of the ways that components of
the specified activity may impact marine mammals and their habitat. The Estimated
Take section later in this document includes a quantitative analysis of the number of
individuals that are expected to be taken by this activity. The Negligible Impact
Analysis and Determination section considers the content of this section, the Estimated
Take section, and the Proposed Mitigation section, to draw conclusions regarding the
likely impacts of these activities on the reproductive success or survivorship of
individuals and how those impacts on individuals are likely to impact marine mammal
species or stocks. General background information on marine mammal hearing was
provided previously (see the Description of Marine Mammals in the Specified
Geographical Area section). Here, the potential effects of sound on marine mammals are
discussed.

SouthCoast has requested, and NMFS proposes to authorize, the take of marine
mammals incidental to the construction activities associated with the SouthCoast project.
In their application, SouthCoast presented their analyses of potential impacts to marine
mammals from the specified activities. NMFS carefully reviewed the information
provided by SouthCoast and also independently reviewed applicable scientific research
and literature and other information to evaluate the potential effects of SouthCoast's
specified activities on marine mammals.
The proposed activities would result in the construction and placement of up to
149 permanent foundations (up to 147 WTGs; up to 5 OSPs) in the marine environment.
Up to 10 UXO/MEC detonations may occur during construction if any found UXO/MEC
cannot be removed by other means. There are a variety of types and degrees of effects to
marine mammals, prey species, and habitat that could occur as a result of SouthCoast’s
specified activities. Below, we provide a brief description of the types of sound sources
that would be generated by the project, the general impacts from these types of activities,
and an analysis of the anticipated impacts on marine mammals from SouthCoast’s
specified activities, with consideration of select proposed mitigation measures.
Description of Sound Sources
This section contains a brief technical background on sound, on the characteristics
of certain sound types, and on metrics used in this proposal inasmuch as the information
is relevant to the specified activity and to a discussion of the potential effects of the
specified activity on marine mammals found later in this document. For general
information on sound and its interaction with the marine environment, please see Au and
Hastings (2008), Richardson et al. (1995), Urick (1983), as well as the Discovery of
Sound in the Sea (DOSITS) website at https://dosits.org/.
Sound is a vibration that travels as an acoustic wave through a medium such as a
gas, liquid or solid. Sound waves alternately compress and decompress the medium as the

wave travels. These compressions and decompressions are detected as changes in
pressure by aquatic life and man-made sound receptors such as hydrophones (underwater
microphones). In water, sound waves radiate in a manner similar to ripples on the surface
of a pond and may be either directed in a beam (narrow beam or directional sources) or
sound beams may radiate in all directions (omnidirectional sources).
Sound travels in water more efficiently than almost any other form of energy,
making the use of acoustics ideal for the aquatic environment and its inhabitants. In
seawater, sound travels at roughly 1,500 meters per second (m/s). In-air, sound waves
travel much more slowly, at about 340 m/s. However, the speed of sound can vary by a
small amount based on characteristics of the transmission medium, such as water
temperature and salinity.
The basic components of a sound wave are frequency, wavelength, velocity, and
amplitude. Frequency is the number of pressure waves that pass by a reference point per
unit of time and is measured in Hz or cycles per second. Wavelength is the distance
between two peaks or corresponding points of a sound wave (length of one cycle). Higher
frequency sounds have shorter wavelengths than lower frequency sounds and typically
attenuate (decrease) more rapidly except in certain cases in shallower water. The intensity
(or amplitude) of sounds are measured in decibels (dB), which are a relative unit of
measurement that is used to express the ratio of one value of a power or field to another.
Decibels are measured on a logarithmic scale, so a small change in dB corresponds to
large changes in sound pressure. For example, a 10-dB increase is a ten-fold increase in
acoustic power. A 20-dB increase is then a 100-fold increase in power and a 30-dB
increase is a 1,000-fold increase in power. However, a ten-fold increase in acoustic power
does not mean that the sound is perceived as being ten times louder. Decibels are a
relative unit comparing two pressures; therefore, a reference pressure must always be
indicated. For underwater sound, this is 1 microPascal (μPa). For in-air sound, the

reference pressure is 20 μPa. The amplitude of a sound can be presented in various ways;
however, NMFS typically considers three metrics. In this proposed rule, all decibel levels
referenced to 1μPa.
Sound exposure level (SEL) represents the total energy in a stated frequency band
over a stated time interval or event and considers both amplitude and duration of
exposure (represented as dB re 1 μPa2-s). SEL is a cumulative metric; it can be
accumulated over a single pulse (for pile driving this is often referred to as single-strike
SEL; SELss) or calculated over periods containing multiple pulses (SELcum). Cumulative
SEL represents the total energy accumulated by a receiver over a defined time window or
during an event. The SEL metric is useful because it allows sound exposures of different
durations to be related to one another in terms of total acoustic energy. The duration of a
sound event and the number of pulses, however, should be specified as there is no
accepted standard duration over which the summation of energy is measured.
Sound is generally defined using common metrics. Root mean square (rms) is the
quadratic mean sound pressure over the duration of an impulse. Root mean square is
calculated by squaring all of the sound amplitudes, averaging the squares, and then taking
the square root of the average (Urick, 1983). Root mean square accounts for both positive
and negative values; squaring the pressures makes all values positive so that they may be
accounted for in the summation of pressure levels (Hastings and Popper, 2005). This
measurement is often used in the context of discussing behavioral effects, in part because
behavioral effects, which often result from auditory cues, may be better expressed
through averaged units than by peak pressures. Peak sound pressure (also referred to as
zero-to-peak sound pressure or 0-pk) is the maximum instantaneous sound pressure
measurable in the water at a specified distance from the source, and is represented in the
same units as the rms sound pressure. Along with SEL, this metric is used in evaluating
the potential for PTS (permanent threshold shift) and TTS (temporary threshold shift).

Peak pressure is also used to evaluate the potential for gastro-intestinal tract injury (Level
A harassment) from explosives. For explosives, an impulse metric (Pa-s), which is the
integral of a transient sound pressure over the duration of the pulse, is used to evaluate
the potential for mortality (i.e., severe lung injury) and slight lung injury. Thes impulse
metric thresholds account for animal mass and depth.
Sounds can be either impulsive or non-impulsive. The distinction between these
two sound types is important because they have differing potential to cause physical
effects, particularly with regard to hearing (e.g., Ward, 1997 in Southall et al., 2007).
Please see NMFS et al. (2018) and Southall et al. (2007, 2019a) for an in-depth
discussion of these concepts. Impulsive sound sources (e.g., airguns, explosions,
gunshots, sonic booms, impact pile driving) produce signals that are brief (typically
considered to be less than one second), broadband, atonal transients (American National
Standards Institute (ANSI), 1986, 2005; Harris, 1998; National Institute for Occupational
Safety and Health (NIOSH), 1998; International Organization for Standardization (ISO,
2003)) and occur either as isolated events or repeated in some succession. Impulsive
sounds are all characterized by a relatively rapid rise from ambient pressure to a maximal
pressure value followed by a rapid decay period that may include a period of diminishing,
oscillating maximal and minimal pressures, and generally have an increased capacity to
induce physical injury as compared with sounds that lack these features. Impulsive
sounds are typically intermittent in nature.
Non-impulsive sounds can be tonal, narrowband, or broadband, brief or
prolonged, and may be either continuous or intermittent (ANSI, 1995; NIOSH, 1998).
Some of these non-impulsive sounds can be transient signals of short duration but
without the essential properties of pulses (e.g., rapid rise time). Examples of nonimpulsive sounds include those produced by vessels, aircraft, machinery operations such
as drilling or dredging, vibratory pile driving, and active sonar systems.

Sounds are also characterized by their temporal component. Continuous sounds
are those whose sound pressure level remains above that of the ambient sound with
negligibly small fluctuations in level (NIOSH, 1998; ANSI, 2005) while intermittent
sounds are defined as sounds with interrupted levels of low or no sound (NIOSH, 1998).
NMFS identifies Level B harassment thresholds based on if a sound is continuous or
intermittent.
Even in the absence of sound from the specified activity, the underwater
environment is typically loud due to ambient sound, which is defined as environmental
background sound levels lacking a single source or point (Richardson et al., 1995). The
sound level of a region is defined by the total acoustical energy being generated by
known and unknown sources. These sources may include physical (e.g., wind and waves,
earthquakes, ice, atmospheric sound), biological (e.g., sounds produced by marine
mammals, fish, and invertebrates), and anthropogenic (e.g., vessels, dredging,
construction) sound. A number of sources contribute to ambient sound, including wind
and waves, which are a main source of naturally occurring ambient sound for frequencies
between 200 Hz and 50 kHz (International Council for the Exploration of the Sea (ICES),
1995). In general, ambient sound levels tend to increase with increasing wind speed and
wave height. Precipitation can become an important component of total sound at
frequencies above 500 Hz and possibly down to 100 Hz during quiet times. Marine
mammals can contribute significantly to ambient sound levels as can some fish and
snapping shrimp. The frequency band for biological contributions is from approximately
12 Hz to over 100 kHz. Sources of ambient sound related to human activity include
transportation (surface vessels), dredging and construction, oil and gas drilling and
production, geophysical surveys, sonar, and explosions. Vessel noise typically dominates
the total ambient sound for frequencies between 20 and 300 Hz. In general, the

frequencies of anthropogenic sounds are below 1 kHz, and if higher frequency sound
levels are created, they attenuate rapidly.
The sum of the various natural and anthropogenic sound sources that comprise
ambient sound at any given location and time depends not only on the source levels (as
determined by current weather conditions and levels of biological and human activity)
but also on the ability of sound to propagate through the environment. In turn, sound
propagation is dependent on the spatially and temporally varying properties of the water
column and sea floor and is frequency-dependent. As a result of the dependence on a
large number of varying factors, ambient sound levels can be expected to vary widely
over both coarse and fine spatial and temporal scales. Sound levels at a given frequency
and location can vary by 10-20 dB from day to day (Richardson et al., 1995). The result
is that, depending on the source type and its intensity, sound from the specified activity
may be a negligible addition to the local environment or could form a distinctive signal
that may affect marine mammals. Human-generated sound is a significant contributor to
the acoustic environment in the Project location.
Potential Effects of Underwater Sound on Marine Mammals
Anthropogenic sounds cover a broad range of frequencies and sound levels and
can have a range of highly variable impacts on marine life from none or minor to
potentially severe responses depending on received levels, duration of exposure,
behavioral context, and various other factors. Broadly, underwater sound from active
acoustic sources, such as those that would be produced by SouthCoast’s activities, can
potentially result in one or more of the following: temporary or permanent hearing
impairment, non-auditory physical or physiological effects, behavioral disturbance,
stress, and masking (Richardson et al., 1995; Gordon et al., 2003; Nowacek et al., 2007;
Southall et al., 2007; Götz et al., 2009; Erbe et al., 2016, 2019). Non-auditory
physiological effects or injuries that theoretically might occur in marine mammals

exposed to high level underwater sound or as a secondary effect of extreme behavioral
reactions (e.g., change in dive profile as a result of an avoidance reaction) caused by
exposure to sound include neurological effects, bubble formation, resonance effects, and
other types of organ or tissue damage (Cox et al., 2006; Southall et al., 2007; Zimmer
and Tyack, 2007; Tal et al., 2015). Potential effects from explosive sound sources can
range in severity from behavioral disturbance or tactile perception to physical discomfort,
slight injury of the internal organs and the auditory system, or mortality (Yelverton et al.,
1973; Siebert et al., 2022).
In general, the degree of effect of an acoustic exposure is intrinsically related to
the signal characteristics, received level, distance from the source, and duration of the
sound exposure, in addition to the contextual factors of the receiver (e.g., behavioral state
at time of exposure, age class, etc.). In general, sudden, high level sounds can cause
hearing loss as can longer exposures to lower level sounds. Moreover, any temporary or
permanent loss of hearing will occur almost exclusively for noise within an animal’s
hearing range. We describe below the specific manifestations of acoustic effects that may
occur based on the activities proposed by SouthCoast.
Richardson et al. (1995) described zones of increasing intensity of effect that
might be expected to occur in relation to distance from a source and assuming that the
signal is within an animal’s hearing range. First (at the greatest distance) is the area
within which the acoustic signal would be audible (potentially perceived) to the animal
but not strong enough to elicit any overt behavioral or physiological response. The next
zone (closer to the receiving animal) corresponds with the area where the signal is
audible to the animal and of sufficient intensity to elicit behavioral or physiological
responsiveness. The third is a zone within which, for signals of high intensity, the
received level is sufficient to potentially cause discomfort or tissue damage to auditory or
other systems. Overlaying these zones to a certain extent is the area within which

masking (i.e., when a sound interferes with or masks the ability of an animal to detect a
signal of interest that is above the absolute hearing threshold) may occur; the masking
zone may be highly variable in size.
Below, we provide additional detail regarding potential impacts on marine
mammals and their habitat from noise in general, starting with hearing impairment, as
well as from the specific activities SouthCoast plans to conduct, to the degree it is
available (noting that there is limited information regarding the impacts of offshore wind
construction on marine mammals).
Hearing Threshold Shift
Marine mammals exposed to high-intensity sound or to lower-intensity sound for
prolonged periods can experience hearing threshold shift (TS), which NMFS defines as a
change, usually an increase, in the threshold of audibility at a specified frequency or
portion of an individual's hearing range above a previously established reference level
expressed in decibels (NMFS, 2018). Threshold shifts can be permanent, in which case
there is an irreversible increase in the threshold of audibility at a specified frequency or
portion of an individual’s hearing range or temporary, in which there is reversible
increase in the threshold of audibility at a specified frequency or portion of an
individual’s hearing range and the animal's hearing threshold would fully recover over
time (Southall et al., 2019a). Repeated sound exposure that leads to TTS could cause
PTS.
When PTS occurs, there can be physical damage to the sound receptors in the ear
(i.e., tissue damage) whereas TTS represents primarily tissue fatigue and is reversible
(Henderson et al., 2008). In addition, other investigators have suggested that TTS is
within the normal bounds of physiological variability and tolerance and does not
represent physical injury (e.g., Ward, 1997; Southall et al., 2019a). Therefore, NMFS
does not consider TTS to constitute auditory injury.

Relationships between TTS and PTS thresholds have not been studied in marine
mammals, and there is no PTS data for cetaceans. However, such relationships are
assumed to be similar to those in humans and other terrestrial mammals. Noise exposure
can result in either a permanent shift in hearing thresholds from baseline (PTS; a 40-dB
threshold shift approximates a PTS onset; e.g., Kryter et al., 1966; Miller, 1974;
Henderson et al., 2008) or a temporary, recoverable shift in hearing that returns to
baseline (a 6-dB threshold shift approximates a TTS onset; e.g., Southall et al., 2019a).
Based on data from terrestrial mammals, a precautionary assumption is that the PTS
thresholds, expressed in the unweighted peak sound pressure level metric (PK), for
impulsive sounds (such as impact pile driving pulses) are at least 6 dB higher than the
TTS thresholds and the weighted PTS cumulative sound exposure level thresholds are 15
(impulsive sound) to 20 (non-impulsive sounds) dB higher than TTS cumulative sound
exposure level thresholds (Southall et al., 2019a). Given the higher level of sound or
longer exposure duration necessary to cause PTS as compared with TTS, PTS is less
likely to occur as a result of these activities, but it is possible and a small amount has
been proposed for authorization for several species.
TTS is the mildest form of hearing impairment that can occur during exposure to
sound, with a TTS of 6 dB considered the minimum threshold shift clearly larger than
any day-to-day or session-to-session variation in a subject’s normal hearing ability
(Schlundt et al., 2000; Finneran et al., 2000; Finneran et al., 2002). While experiencing
TTS, the hearing threshold rises, and a sound must be at a higher level in order to be
heard. In terrestrial and marine mammals, TTS can last from minutes or hours to days (in
cases of strong TTS). In many cases, hearing sensitivity recovers rapidly after exposure
to the sound ends. There is data on sound levels and durations necessary to elicit mild
TTS for marine mammals, but recovery is complicated to predict and dependent on
multiple factors.

Marine mammal hearing plays a critical role in communication with conspecifics,
and interpretation of environmental cues for purposes such as predator avoidance and
prey capture. Depending on the degree (elevation of threshold in dB), duration (i.e.,
recovery time), and frequency range of TTS, and the context in which it is experienced,
TTS can have effects on marine mammals ranging from discountable to serious
depending on the degree of interference with marine mammals hearing. For example, a
marine mammal may be able to readily compensate for a brief, relatively small amount of
TTS in a non-critical frequency range that occurs during a time where ambient noise is
lower and there are not as many competing sounds present. Alternatively, a larger amount
and longer duration of TTS sustained during time when communication is critical (e.g.,
for successful mother/calf interactions, consistent detection of prey) could have more
serious impacts.
Currently, TTS data only exist for four species of cetaceans (bottlenose dolphin,
beluga whale (Delphinapterus leucas), harbor porpoise, and Yangtze finless porpoise
(Neophocoena asiaeorientalis)) and six species of pinnipeds (northern elephant seal
(Mirounga angustirostris), harbor seal, ring seal, spotted seal, bearded seal, and
California sea lion (Zalophus californianus)) that were exposed to a limited number of
sound sources (i.e., mostly tones and octave-band noise with limited number of exposure
to impulsive sources such as seismic airguns or impact pile driving) in laboratory settings
(Southall et al., 2019). There is currently no data available on noise-induced hearing loss
for mysticetes. For summaries of data on TTS or PTS in marine mammals or for further
discussion of TTS or PTS onset thresholds, please see Southall et al. (2019), and NMFS
(2018).
Recent studies with captive odontocete species (bottlenose dolphin, harbor
porpoise, beluga, and false killer whale) have observed increases in hearing threshold
levels when individuals received a warning sound prior to exposure to a relatively loud

sound (Nachtigall and Supin, 2013, 2015; Nachtigall et al., 2016a, 2016b, 2016c;
Finneran, 2018;, Nachtigall et al., 2018). These studies suggest that captive animals have
a mechanism to reduce hearing sensitivity prior to impending loud sounds. Hearing
change was observed to be frequency dependent and Finneran (2018) suggests hearing
attenuation occurs within the cochlea or auditory nerve. Based on these observations on
captive odontocetes, the authors suggest that wild animals may have a mechanism to selfmitigate the impacts of noise exposure by dampening their hearing during prolonged
exposures of loud sound, or if conditioned to anticipate intense sounds (Finneran, 2018;
Nachtigall et al., 2018).
Behavioral Effects
Exposure of marine mammals to sound sources can result in, but is not limited to,
no response or any of the following observable responses: increased alertness; orientation
or attraction to a sound source; vocal modifications; cessation of feeding; cessation of
social interaction; alteration of movement or diving behavior; habitat abandonment
(temporary or permanent); and, in severe cases, panic, flight, stampede, or stranding,
potentially resulting in death (Southall et al., 2007). A review of marine mammal
responses to anthropogenic sound was first conducted by Richardson (1995). More recent
reviews address studies conducted since 1995 and focused on observations where the
received sound level of the exposed marine mammal(s) was known or could be estimated
Nowacek et al., 2007; DeRuiter et al., 2013; Ellison et al., 2012; Gomez et al., 2016;
Southall et al., 2021; Gomez et al. 2016). Gomez et al. (2016) conducted a review of the
literature considering the contextual information of exposure in addition to received level
and found that higher received levels were not always associated with more severe
behavioral responses and vice versa. Southall et al. (2021) states that results demonstrate
that some individuals of different species display clear yet varied responses, some of
which have negative implications while others appear to tolerate high levels and that

responses may not be fully predictable with simple acoustic exposure metrics (e.g.,
received sound level). Rather, the authors state that differences among species and
individuals along with contextual aspects of exposure (e.g., behavioral state) appear to
affect response probability.
Behavioral responses to sound are highly variable and context-specific. Many
different variables can influence an animal's perception of and response to (nature and
magnitude) an acoustic event. An animal's prior experience with a sound or sound source
affects whether it is less likely (habituation) or more likely (sensitization) to respond to
certain sounds in the future (animals can also be innately predisposed to respond to
certain sounds in certain ways) (Southall et al., 2019a). Related to the sound itself, the
perceived nearness of the sound, bearing of the sound (approaching versus retreating), the
similarity of a sound to biologically relevant sounds in the animal's environment (i.e.,
calls of predators, prey, or conspecifics), and familiarity of the sound may affect the way
an animal responds to the sound (Southall et al., 2007, DeRuiter et al., 2013). Individuals
(of different age, gender, reproductive status, etc.) among most populations will have
variable hearing capabilities, and differing behavioral sensitivities to sounds that will be
affected by prior conditioning, experience, and current activities of those individuals.
Often, specific acoustic features of the sound and contextual variables (i.e., proximity,
duration, or recurrence of the sound or the current behavior that the marine mammal is
engaged in or its prior experience), as well as entirely separate factors such as the
physical presence of a nearby vessel, may be more relevant to the animal's response than
the received level alone.
Overall, the variability of responses to acoustic stimuli depends on the species
receiving the sound, the sound source, and the social, behavioral, or environmental
contexts of exposure (e.g., DeRuiter and Doukara, 2012). For example, Goldbogen et al.
(2013b) demonstrated that individual behavioral state was critically important in

determining response of blue whales to sonar, noting that some individuals engaged in
deep (greater than 50 m) feeding behavior had greater dive responses than those in
shallow feeding or non-feeding conditions. Some blue whales in the Goldbogen et al.
(2013a) study that were engaged in shallow feeding behavior demonstrated no clear
changes in diving or movement even when received levels were high (~160 dB re 1µPa)
for exposures to 3-4 kHz sonar signals, while deep feeding and non-feeding whales
showed a clear response at exposures at lower received levels of sonar and pseudorandom
noise. Southall et al. (2011) found that blue whales had a different response to sonar
exposure depending on behavioral state, more pronounced when deep feeding/travel
modes than when engaged in surface feeding.
With respect to distance influencing disturbance, DeRuiter et al. (2013) examined
behavioral responses of Cuvier's beaked whales to mid-frequency sonar and found that
whales responded strongly at low received levels (89-127 dB re 1µPa) by ceasing normal
fluking and echolocation, swimming rapidly away, and extending both dive duration and
subsequent non-foraging intervals when the sound source was 3.4-9.5 km (2.1-5.9 mi)
away. Importantly, this study also showed that whales exposed to a similar range of
received levels (78-106 dB re 1µPa) from distant sonar exercises (118 km (73 mi) away)
did not elicit such responses, suggesting that context may moderate reactions. Thus,
distance from the source is an important variable in influencing the type and degree of
behavioral response and this variable is independent of the effect of received levels (e.g.,
DeRuiter et al., 2013; Dunlop et al., 2017a, 2017b; Falcone et al., 2017; Dunlop et al.,
2018; Southall et al., 2019b).
Ellison et al. (2012) outlined an approach to assessing the effects of sound on
marine mammals that incorporates contextual-based factors. The authors recommend
considering not just the received level of sound but also the activity the animal is engaged
in at the time the sound is received, the nature and novelty of the sound (i.e., is this a new

sound from the animal's perspective), and the distance between the sound source and the
animal. They submit that this “exposure context,” as described, greatly influences the
type of behavioral response exhibited by the animal. Forney et al. (2017) also point out
that an apparent lack of response (e.g., no displacement or avoidance of a sound source)
may not necessarily mean there is no cost to the individual or population, as some
resources or habitats may be of such high value that animals may choose to stay, even
when experiencing stress or hearing loss. Forney et al. (2017) recommend considering
both the costs of remaining in an area of noise exposure such as TTS, PTS, or masking,
which could lead to an increased risk of predation or other threats or a decreased
capability to forage, and the costs of displacement, including potential increased risk of
vessel strike, increased risks of predation or competition for resources, or decreased
habitat suitable for foraging, resting, or socializing. This sort of contextual information is
challenging to predict with accuracy for ongoing activities that occur over large spatial
and temporal expanses. However, distance is one contextual factor for which data exist to
quantitatively inform a take estimate, and the method for predicting Level B harassment
in this rule does consider distance to the source. Other factors are often considered
qualitatively in the analysis of the likely consequences of sound exposure, where
supporting information is available.
Behavioral change, such as disturbance manifesting in lost foraging time, in
response to anthropogenic activities is often assumed to indicate a biologically significant
effect on a population of concern. However, individuals may be able to compensate for
some types and degrees of shifts in behavior, preserving their health and thus their vital
rates and population dynamics. For example, New et al. (2013) developed a model
simulating the complex social, spatial, behavioral and motivational interactions of coastal
bottlenose dolphins in the Moray Firth, Scotland, to assess the biological significance of
increased rate of behavioral disruptions caused by vessel traffic. Despite a modeled

scenario in which vessel traffic increased from 70 to 470 vessels a year (a six-fold
increase in vessel traffic) in response to the construction of a proposed offshore
renewables' facility, the dolphins' behavioral time budget, spatial distribution,
motivations and social structure remained unchanged. Similarly, two bottlenose dolphin
populations in Australia were also modeled over 5 years against a number of disturbances
(Reed et al., 2020) and results indicate that habitat/noise disturbance had little overall
impact on population abundances in either location, even in the most extreme impact
scenarios modeled.
Friedlaender et al. (2016) provided the first integration of direct measures of prey
distribution and density variables incorporated into across-individual analyses of
behavior responses of blue whales to sonar, and demonstrated a five-fold increase in the
ability to quantify variability in blue whale diving behavior. When the prey field was
mapped and used as a covariate in examining how behavioral state of blue whales is
influenced by mid-frequency sound, the response in blue whale deep-feeding behavior
was even more apparent, reinforcing the need for contextual variables to be included
when assessing behavioral responses (Friedlaender et al., 2016). These results illustrate
that responses evaluated without such measurements for foraging animals may be
misleading, which again illustrates the context-dependent nature of the probability of
response.
The following subsections provide examples of behavioral responses that give an
idea of the variability in behavioral responses that would be expected given the
differential sensitivities of marine mammal species to sound, contextual factors, and the
wide range of potential acoustic sources to which a marine mammal may be exposed.
Behavioral responses that could occur for a given sound exposure should be determined
from the literature that is available for each species, or extrapolated from closely related
species when no information exists, along with contextual factors.

Avoidance and Displacement
Avoidance is the displacement of an individual from an area or migration path as
a result of the presence of a sound or other stressors and is one of the most obvious
manifestations of disturbance in marine mammals (Richardson et al., 1995). For example,
gray whales (Eschrichtius robustus) and humpback whales are known to change
direction, deflecting from customary migratory paths, in order to avoid noise from airgun
surveys (Malme et al., 1984; Dunlop et al., 2018). Avoidance is qualitatively different
from the flight response but also differs in the magnitude of the response (i.e., directed
movement, rate of travel, etc.). Avoidance may be short-term with animals returning to
the area once the noise has ceased (e.g., Malme et al., 1984; Bowles et al., 1994; Goold,
1996; Stone et al., 2000; Morton and Symonds, 2002; Gailey et al., 2007; Dähne et al.,
2013; Russel et al., 2016). Longer-term displacement is possible, however, which may
lead to changes in abundance or distribution patterns of the affected species in the
affected region if habituation to the presence of the sound does not occur (e.g., Blackwell
et al., 2004; Bejder et al., 2006; Teilmann et al., 2006; Forney et al., 2017). Avoidance of
marine mammals during the construction of offshore wind facilities (specifically, impact
pile driving) has been documented in the literature with some significant variation in the
temporal and spatial degree of avoidance and with most studies focused on harbor
porpoises as one of the most common marine mammals in European waters (e.g.,
Tougaard et al., 2009; Dähne et al., 2013; Thompson et al., 2013; Russell et al., 2016;
Brandt et al., 2018).
Available information on impacts to marine mammals from pile driving
associated with offshore wind is limited to information on harbor porpoises and seals, as
the vast majority of this research has occurred at European offshore wind projects where
large whales and other odontocete species are uncommon. Harbor porpoises and harbor
seals are considered to be behaviorally sensitive species (e.g., Southall et al., 2007) and

the effects of wind farm construction in Europe on these species has been well
documented. These species have received particular attention in European waters due to
their abundance in the North Sea (Hammond et al., 2002; Nachtsheim et al., 2021). A
summary of the literature on documented effects of wind farm construction on harbor
porpoise and harbor seals is described below.
Brandt et al. (2016) summarized the effects of the construction of eight offshore
wind projects within the German North Sea (i.e., Alpha Ventus, BARD Offshore I,
Borkum West II, DanTysk, Global Tech I, Meerwind Süd/Ost, Nordsee Ost, and Riffgat)
between 2009 and 2013 on harbor porpoises, combining PAM data from 2010-2013 and
aerial surveys from 2009-2013 with data on noise levels associated with pile driving.
Results of the analysis revealed significant declines in porpoise detections during pile
driving when compared to 25-48 hours before pile driving began, with the magnitude of
decline during pile driving clearly decreasing with increasing distances to the
construction site. During the majority of projects, significant declines in detections (by at
least 20 percent) were found within at least 5-10 km (3.1-6.2 mi) of the pile driving site,
with declines at up to 20-30 km (12.4-18.6 mi) of the pile driving site documented in
some cases. Similar results demonstrating the long-distance displacement of harbor
porpoises (18-25 km (11.2-15.5 mi)) and harbor seals (up to 40 km (25 mi)) during
impact pile driving have also been observed during the construction at multiple other
European wind farms (Tougaard et al., 2009; Bailey et al., 2010.; Dähne et al., 2013;
Lucke et al., 2012; Haelters et al., 2015).
While harbor porpoises and seals tend to move several kilometers away from
wind farm construction activities, the duration of displacement has been documented to
be relatively temporary. In two studies at Horns Rev II using impact pile driving, harbor
porpoise returned within 1-2 days following cessation of pile driving (Tougaard et al.,
2009, Brandt et al., 2011). Similar recovery periods have been noted for harbor seals off

England during the construction of four wind farms (Brasseur et al., 2012; Carroll et al.,
2010; Hamre et al., 2011; Hastie et al., 2015; Russell et al., 2016). In some cases, an
increase in harbor porpoise activity has been documented inside wind farm areas
following construction (e.g., Lindeboom et al., 2011). Other studies have noted longer
term impacts after impact pile driving. Near Dogger Bank in Germany, harbor porpoises
continued to avoid the area for over 2 years after construction began (Gilles et al. 2009).
Approximately 10 years after construction of the Nysted wind farm, harbor porpoise
abundance had not recovered to the original levels previously seen, although the
echolocation activity was noted to have been increasing when compared to the previous
monitoring period (Teilmann and Carstensen, 2012). However, overall, there are no
indications for a population decline of harbor porpoises in European waters (e.g., Brandt
et al., 2016). Notably, where significant differences in displacement and return rates have
been identified for these species, the occurrence of secondary project-specific influences
such as use of mitigation measures (e.g., bubble curtains, acoustic deterrent devices
(ADDs)) or the manner in which species use the habitat in the project area are likely the
driving factors of this variation.
NMFS notes the aforementioned studies from Europe involve installing much
smaller piles than SouthCoast proposes to install and therefore, we anticipate noise levels
from impact pile driving to be louder. For this reason, we anticipate that the greater
distances of displacement observed in harbor porpoise and harbor seals documented in
Europe are likely to occur off of Massachusetts. However, we do not anticipate any
greater severity of response due to harbor porpoise and harbor seal habitat use off of
Massachusetts or population level consequences similar to European findings. In many
cases, harbor porpoises and harbor seals are resident to the areas where European wind
farms have been constructed. However, off of Massachusetts, harbor porpoises are
transient (with higher abundances in winter when foundation installation would not

occur) and a small percentage of the large harbor seal population are only seasonally
present with no rookeries established. In summary, we anticipate that harbor porpoise and
harbor seals will likely respond to pile driving by moving several kilometers away from
the source but return to typical habitat use patterns when pile driving ceases.
Some avoidance behavior of other marine mammal species has been documented
to be dependent on distance from the source. As described above, DeRuiter et al. (2013)
noted that distance from a sound source may moderate marine mammal reactions in their
study of Cuvier's beaked whales (an acoustically sensitive species), which showed the
whales swimming rapidly and silently away when a sonar signal was 3.4-9.5 km (2.1-5.9
mi) away while showing no such reaction to the same signal when the signal was 118 km
(73 mi) away even though the received levels were similar. Tyack et al. (1983) conducted
playback studies of Surveillance Towed Array Sensor System (SURTASS) lowfrequency active (LFA) sonar in a gray whale migratory corridor off California. Similar
to North Atlantic right whales, gray whales migrate close to shore (approximately 2 km
(1.2 mi) from shore) and are low-frequency hearing specialists. The LFA sonar source
was placed within the gray whale migratory corridor (approximately 2 km (1.2 mi)
offshore) and offshore of most, but not all, migrating whales (approximately 4 km (2.5
mi) offshore). These locations influenced received levels and distance to the source. For
the inshore playbacks, not unexpectedly, the louder the source level of the playback (i.e.,
the louder the received level), whale avoided the source at greater distances. Specifically,
when the source level was 170 dB SPLrms and 178 dBrms, whales avoided the inshore
source at ranges of several hundred meters, similar to avoidance responses reported by
Malme et al. (1983; 1984). Whales exposed to source levels of 185 dBrms demonstrated
avoidance levels at ranges of +1 km (+0.6 mi). While there was observed deflection from
course, in no case did a whale abandon its migratory behavior.

The signal context of the noise exposure has been shown to play an important
role in avoidance responses. In a 2007-2008 study in the Bahamas, playback sounds of a
potential predator—a killer whale—resulted in a similar but more pronounced reaction in
beaked whales (an acoustically sensitive species), which included longer inter-dive
intervals and a sustained straight-line departure of more than 20 km (12.4 mi) from the
area (Boyd et al., 2008; Southall et al., 2009; Tyack et al., 2011). SouthCoast does not
anticipate and NMFS is not proposing to authorize take of beaked whales and, moreover,
the sounds produced by SouthCoast do not have signal characteristics similar to
predators. Therefore, we would not expect such extreme reactions to occur for similar
species.
One potential consequence of behavioral avoidance is the altered energetic
expenditure of marine mammals because energy is required to move and avoid surface
vessels or the sound field associated with active sonar (Frid and Dill, 2002). Most
animals can avoid that energetic cost by swimming away at slow speeds or speeds that
minimize the cost of transport (Miksis-Olds, 2006), as has been demonstrated in Florida
manatees (Miksis-Olds, 2006). Those energetic costs increase, however, when animals
shift from a resting state, which is designed to conserve an animal's energy, to an active
state that consumes energy the animal would have conserved had it not been disturbed.
Marine mammals that have been disturbed by anthropogenic noise and vessel approaches
are commonly reported to shift from resting to active behavioral states, which would
imply that they incur an energy cost.
Forney et al. (2017) detailed the potential effects of noise on marine mammal
populations with high site fidelity, including displacement and auditory masking, noting
that a lack of observed response does not imply absence of fitness costs and that apparent
tolerance of disturbance may have population-level impacts that are less obvious and
difficult to document. Avoidance of overlap between disturbing noise and areas and/or

times of particular importance for sensitive species may be critical to avoiding
population-level impacts because (particularly for animals with high site fidelity) there
may be a strong motivation to remain in the area despite negative impacts. Forney et al.
(2017) stated that, for these animals, remaining in a disturbed area may reflect a lack of
alternatives rather than a lack of effects.
A flight response is a dramatic change in normal movement to a directed and
rapid movement away from the perceived location of a sound source. The flight response
differs from other avoidance responses in the intensity of the response (e.g., directed
movement, rate of travel). Relatively little information on flight responses of marine
mammals to anthropogenic signals exist, although observations of flight responses to the
presence of predators have occurred (Connor and Heithaus, 1996; Frid and Dill, 2002).
The result of a flight response could range from brief, temporary exertion and
displacement from the area where the signal provokes flight to, in extreme cases, beaked
whale strandings (Cox et al., 2006; D’Amico et al., 2009). However, it should be noted
that response to a perceived predator does not necessarily invoke flight (Ford and Reeves,
2008), and whether individuals are solitary or in groups may influence the response.
Flight responses of marine mammals have been documented in response to mobile high
intensity active sonar (e.g., Tyack et al., 2011; DeRuiter et al., 2013; Wensveen et al.,
2019), and more severe responses have been documented when sources are moving
towards an animal or when they are surprised by unpredictable exposures (Watkins 1986;
Falcone et al. 2017). Generally speaking, however, marine mammals would be expected
to be less likely to respond with a flight response to either stationary pile driving (which
they can sense is stationary and predictable) or significantly lower-level HRG surveys
unless they are within the area ensonified above behavioral harassment thresholds at the
moment the source is turned on (Watkins, 1986; Falcone et al., 2017). A flight response
may also be possible in response to UXO/MEC detonation. However, detonations would

be restricted to one per day and a maximum of 10 over 5 years, thus, there would be
limited opportunities for flight response to be elicited as a result of detonation noise. The
proposed mitigation and monitoring would result in any animals being far from the
detonation location (i.e., the clearance zones vary by hearing group and charge weight,
but all zones are sized to ensure that marine mammals are beyond the area where PTS
could occur prior to detonation) and any flight response would be spatially and
temporally limited.
Diving and Foraging
Changes in dive behavior in response to noise exposure can vary widely. They
may consist of increased or decreased dive times and surface intervals as well as changes
in the rates of ascent and descent during a dive (e.g., Frankel and Clark, 2000; Costa et
al., 2003; Ng and Leung, 2003; Nowacek et al.; 2004; Goldbogen et al., 2013a,
Goldbogen et al. 2013b). Variations in dive behavior may reflect interruptions in
biologically significant activities (e.g., foraging) or they may be of little biological
significance. Variations in dive behavior may also expose an animal to potentially
harmful conditions (e.g., increasing the chance of ship-strike) or may serve as an
avoidance response that enhances survivorship. The impact of a variation in diving
resulting from an acoustic exposure depends on what the animal is doing at the time of
the exposure, the type and magnitude of the response, and the context within which the
response occurs (e.g., the surrounding environmental and anthropogenic circumstances).
Nowacek et al. (2004) reported disruptions of dive behaviors in foraging North
Atlantic right whales when exposed to an alerting stimulus, an action, they noted, that
could lead to an increased likelihood of vessel strike. The alerting stimulus was in the
form of an 18 minute exposure that included three 2-minute signals played three times
sequentially. This stimulus was designed with the purpose of providing signals distinct to
background noise that serve as localization cues. However, the whales did not respond to

playbacks of either right whale social sounds or vessel noise, highlighting the importance
of the sound characteristics in producing a behavioral reaction. Although source levels
for the proposed pile driving activities may exceed the received level of the alerting
stimulus described by Nowacek et al. (2004), proposed mitigation strategies (further
described in the Proposed Mitigation section) will reduce the severity of any response to
proposed pile driving activities. Converse to the behavior of North Atlantic right whales,
Indo-Pacific humpback dolphins have been observed to dive for longer periods of time in
areas where vessels were present and/or approaching (Ng and Leung, 2003). In both of
these studies, the influence of the sound exposure cannot be decoupled from the physical
presence of a surface vessel, thus complicating interpretations of the relative contribution
of each stimulus to the response. Indeed, the presence of surface vessels, their approach,
and speed of approach seemed to be significant factors in the response of the Indo-Pacific
humpback dolphins (Ng and Leung, 2003). Low frequency signals of the Acoustic
Thermometry of Ocean Climate (ATOC) sound source were not found to affect dive
times of humpback whales in Hawaiian waters (Frankel and Clark, 2000) or to overtly
affect elephant seal dives (Costa et al., 2003). They did, however, produce subtle effects
that varied in direction and degree among the individual seals, illustrating the equivocal
nature of behavioral effects and consequent difficulty in defining and predicting them.
Disruption of feeding behavior can be difficult to correlate with anthropogenic
sound exposure, so it is usually inferred by observed displacement from known foraging
areas, the cessation of secondary indicators of feeding (e.g., bubble nets or sediment
plumes), or changes in dive behavior. As for other types of behavioral response, the
frequency, duration, and temporal pattern of signal presentation as well as differences in
species sensitivity are likely contributing factors to differences in response in any given
circumstance (e.g., Croll et al., 2001; Nowacek et al.; 2004; Madsen et al., 2006;
Yazvenko et al., 2007; Southall et al., 2019b). An understanding of the energetic

requirements of the affected individuals and the relationship between prey availability,
foraging effort and success, and the life history stage of the animal can facilitate the
assessment of whether foraging disruptions are likely to incur fitness consequences
(Goldbogen et al., 2013b; Farmer et al., 2018; Pirotta et al., 2018a; Southall et al., 2019a;
Pirotta et al., 2021).
Impacts on marine mammal foraging rates from noise exposure have been
documented, though there is little data regarding the impacts of offshore turbine
construction specifically. Several broader examples follow, and it is reasonable to expect
that exposure to noise produced during the 5-years the proposed rule would be effective
could have similar impacts.
Visual tracking, passive acoustic monitoring, and movement recording tags were
used to quantify sperm whale behavior prior to, during, and following exposure to airgun
arrays at received levels in the range 140-160 dB at distances of 7-13 km (4.3-8.1 mi),
following a phase-in of sound intensity and full array exposures at 1-13 km (0.6-8.1 mi)
(Madsen et al., 2006; Miller et al., 2009). Sperm whales did not exhibit horizontal
avoidance behavior at the surface. However, foraging behavior may have been affected.
The sperm whales exhibited 19 percent less vocal (buzz) rate during full exposure
relative to post exposure, and the whale that was approached most closely had an
extended resting period and did not resume foraging until the airguns had ceased firing.
The remaining whales continued to execute foraging dives throughout exposure;
however, swimming movements during foraging dives were six percent lower during
exposure than control periods (Miller et al., 2009). Miller et al. (2009) noted that more
data are required to understand whether the differences were due to exposure or natural
variation in sperm whale behavior.
Balaenopterid whales exposed to moderate low-frequency signals similar to the
ATOC sound source demonstrated no variation in foraging activity (Croll et al., 2001)

whereas five out of six North Atlantic right whales exposed to an acoustic alarm
interrupted their foraging dives (Nowacek et al., 2004). Although the received SPLs were
similar in the latter two studies, the frequency, duration, and temporal pattern of signal
presentation were different. These factors, as well as differences in species sensitivity, are
likely contributing factors to the differential response. The source levels of both the
proposed construction and HRG activities exceed the source levels of the signals
described by Nowacek et al. (2004) and Croll et al. (2001), and noise generated by
SouthCoast’s activities at least partially overlaps in frequency with the described signals.
Blue whales exposed to mid-frequency sonar in the Southern California Bight were less
likely to produce low frequency calls usually associated with feeding behavior (Melcón et
al., 2012). However, Melcón et al. (2012) were unable to determine if suppression of
low-frequency calls reflected a change in their feeding performance or abandonment of
foraging behavior and indicated that implications of the documented responses are
unknown. Further, it is not known whether the lower rates of calling actually indicated a
reduction in feeding behavior or social contact since the study used data from remotely
deployed, passive acoustic monitoring buoys. Results from the 2010-2011 field season of
a behavioral response study in Southern California waters indicated that, in some cases
and at low received levels, tagged blue whales responded to mid-frequency sonar but that
those responses were mild and there was a quick return to their baseline activity (Southall
et al., 2011; Southall et al., 2012b, Southall et al., 2019b).
Southall et al. (2011) found that blue whales had a different response to sonar
exposure depending on behavioral state, which was more pronounced when whales were
in deep feeding/travel modes than when engaged in surface feeding. Southall et al. (2023)
conducted a controlled exposure experiment (CEE) study similar to Southall et al. (2011),
but focused on fin whale behavioral responses to different sound sources including midfrequency active sonar (MFAS), and pseudorandom noise (PRN) signals lacking tonal

patterns but having frequency, duration, and source levels similar to sonar. In general,
fewer fin whales (33 percent) displayed observable behavioral responses to similar noise
stimuli compared to blue whales (66 percent), and fin whale responses were less
dependent on the behavioral state of the whale at the time of exposure and more closely
associated with the received level (i.e., loudness) of the signal. Similar to blue whales,
some fin whales responded to the sound exposure by lunge feeding and deep diving,
particularly at higher received levels, and returned to baseline behaviors (i.e., as observed
prior to sound exposure) relatively quickly following noise exposure. Southall et al.
(2023) found no evidence that noise exposure compromised fin whale foraging success,
in contrast with observations of noise-exposed foraging blue whales by Friedlander et al.
(2016). The baseline acoustic environment appeared to influence the degree of fin whale
behavioral responses. The five fin whales that did present observable behavioral
responses did so to a greater extent when exposed to PRN than MFAS. Southall et al.
(2023) conducted the CEE in fin whale habitat that overlaps with an area in southern
California frequently used for military sonar training exercises, thus, whales may be more
familiar with sonar signals than PRN, a novel stimulus. The observations by Southall et
al. (2023) underscore the importance of considering an animal’s exposure history when
evaluating behavioral responses to particular noise stimuli.
Foraging strategies may impact foraging efficiency, such as by reducing foraging
effort and increasing success in prey detection and capture, in turn promoting fitness and
allowing individuals to better compensate for foraging disruptions. Surface feeding blue
whales did not show a change in behavior in response to mid-frequency simulated and
real sonar sources with received levels between 90 and 179 dB re 1 µPa, but deep feeding
and non-feeding whales showed temporary reactions including cessation of feeding,
reduced initiation of deep foraging dives, generalized avoidance responses, and changes
to dive behavior (DeRuiter et al., 2017; Goldbogen et al.; 2013b; Sivle et al., 2015).

Goldbogen et al. (2013b) indicate that disruption of feeding and displacement could
impact individual fitness and health. However, for this to be true, we would have to
assume that an individual whale could not compensate for this lost feeding opportunity
by either immediately feeding at another location, by feeding shortly after cessation of
acoustic exposure, or by feeding at a later time. Here, there is no indication that
individual fitness and health would be impacted, particularly since unconsumed prey
would likely still be available in the environment in most cases following the cessation of
acoustic exposure. Seasonal restrictions on pile driving and UXO/MEC detonations
would limit temporal and spatial co-occurrence of these activities and foraging North
Atlantic right whales (and other marine mammal species) in southern New England,
thereby minimizing disturbance during times of year when prey are most abundant.
Similarly, while the rates of foraging lunges decrease in humpback whales due to
sonar exposure, there was variability in the response across individuals with one animal
ceasing to forage completely and another animal starting to forage during the exposure
(Sivle et al., 2016). In addition, almost half of the animals that demonstrated avoidance
were foraging before the exposure but the others were not; the animals that avoided while
not feeding responded at a slightly lower received level and greater distance than those
that were feeding (Wensveen et al., 2017). These findings indicate the behavioral state of
the animal and foraging strategies play a role in the type and severity of a behavioral
response.
Vocalizations and Auditory Masking
Marine mammals vocalize for different purposes and across multiple modes, such
as whistling, production of echolocation clicks, calling, and singing. Changes in
vocalization behavior in response to anthropogenic noise can occur for any of these
modes and may result directly from increased vigilance or a startle response, or from a

need to compete with an increase in background noise (see Erbe et al. (2016)’s review on
communication masking), the latter of which is described more below.
For example, in the presence of potentially masking signals, humpback whales
and killer whales have been observed to increase the length of their songs (Miller et al.,
2000; Fristrup et al., 2003; Foote et al., 2004) and blue whales increased song production
(Di Iorio and Clark, 2009) while North Atlantic right whales have been observed to shift
the frequency content of their calls upward while reducing the rate of calling in areas of
increased anthropogenic noise (Parks et al., 2007). In some cases, animals may cease or
reduce sound production during production of aversive signals (Bowles et al., 1994;
Thode et al., 2020; Cerchio et al., (2014); McDonald et al., 1995. Blackwell et al. (2015)
showed that whales increased calling rates as soon as airgun signals were detectable
before ultimately decreasing calling rates at higher received levels.
Sound can disrupt behavior through masking or interfering with an animal's
ability to detect, recognize, or discriminate between acoustic signals of interest (e.g.,
those used for intraspecific communication and social interactions, prey detection,
predator avoidance, or navigation) (Richardson et al., 1995; Erbe and Farmer, 2000;
Tyack, 2000; Erbe et al., 2016). Masking occurs when the receipt of a sound is interfered
with by another coincident sound at similar frequencies and at similar or higher intensity
and may occur whether the sound is natural (e.g., snapping shrimp, wind, waves,
precipitation) or anthropogenic (e.g., shipping, sonar, seismic exploration) in origin. The
ability of a noise source to mask biologically important sounds depends on the
characteristics of both the noise source and the signal of interest (e.g., signal-to-noise
ratio, temporal variability, direction) in relation to each other and to an animal's hearing
abilities (e.g., sensitivity, frequency range, critical ratios, frequency discrimination,
directional discrimination, age, or TTS hearing loss), and existing ambient noise and
propagation conditions.

Masking these acoustic signals can disturb the behavior of individual animals,
groups of animals, or entire populations. Masking can lead to behavioral changes,
including vocal changes (e.g., Lombard effect, increasing amplitude, or changing
frequency), cessation of foraging or lost foraging opportunities, and leaving an area, to
both signalers and receivers in an attempt to compensate for noise levels (Erbe et al.,
2016) or because sounds that would typically have triggered a behavior were not
detected. In humans, significant masking of tonal signals occurs as a result of exposure to
noise in a narrow band of similar frequencies. As the sound level increases, though, the
detection of frequencies above those of the masking stimulus decreases also. This
principle is expected to apply to marine mammals as well because of common
biomechanical cochlear properties across taxa. Therefore, when the coincident (masking)
sound is man-made, it may be considered harassment when disrupting behavioral
patterns. It is important to distinguish TTS and PTS, which persist after the sound
exposure, from masking, which only occurs during the sound exposure. Because masking
(without resulting in threshold shift) is not associated with abnormal physiological
function, it is not considered a physiological effect, but rather a potential behavioral
effect.
The frequency range of the potentially masking sound is important in determining
any potential behavioral impacts. For example, low-frequency signals may have less
effect on high-frequency echolocation sounds produced by odontocetes but are more
likely to affect detection of mysticete communication calls and other potentially
important natural sounds such as those produced by surf and some prey species. The
masking of communication signals by anthropogenic noise may be considered as a
reduction in the communication space of animals (e.g., Clark et al., 2009; Matthews et
al., 2017) and may result in energetic or other costs as animals change their vocalization
behavior (e.g., Miller et al., 2000; Foote et al., 2004; Parks et al., 2007; Di Iorio and

Clark, 2009; Holt et al., 2009). Masking can be reduced in situations where the signal and
noise come from different directions (Richardson et al., 1995), through amplitude
modulation of the signal, or through other compensatory behaviors (Houser and Moore,
2014). Masking can be tested directly in captive species (e.g., Erbe, 2008), but in wild
populations it must be either modeled or inferred from evidence of masking
compensation. There are few studies addressing real-world masking sounds likely to be
experienced by marine mammals in the wild (e.g., Branstetter et al., 2013; Cholewiak et
al., 2018).
The echolocation calls of toothed whales are subject to masking by highfrequency sound. Human data indicate low-frequency sound can mask high-frequency
sounds (i.e., upward masking). Studies on captive odontocetes by Au et al. (1974, 1985,
1993) indicate that some species may use various processes to reduce masking effects
(e.g., adjustments in echolocation call intensity or frequency as a function of background
noise conditions). There is also evidence that the directional hearing abilities of
odontocetes are useful in reducing masking at the high-frequencies these cetaceans use to
echolocate but not at the low-to-moderate frequencies they use to communicate (Zaitseva
et al., 1980). A study by Nachtigall and Supin (2008) showed that false killer whales
adjust their hearing to compensate for ambient sounds and the intensity of returning
echolocation signals.
Impacts on signal detection, measured by masked detection thresholds, are not the
only important factors to address when considering the potential effects of masking. As
marine mammals use sound to recognize conspecifics, prey, predators, or other
biologically significant sources (Branstetter et al., 2016), it is also important to
understand the impacts of masked recognition thresholds (often called “informational
masking”). Branstetter et al. (2016) measured masked recognition thresholds for whistlelike sounds of bottlenose dolphins and observed that they are approximately 4 dB above

detection thresholds (energetic masking) for the same signals. Reduced ability to
recognize a conspecific call or the acoustic signature of a predator could have severe
negative impacts. Branstetter et al. (2016) observed that if “quality communication” is set
at 90 percent recognition the output of communication space models (which are based on
50 percent detection) would likely result in a significant decrease in communication
range.
As marine mammals use sound to recognize predators (Allen et al., 2014;
Cummings and Thompson, 1971; Curé et al., 2015; Fish and Vania, 1971), the presence
of masking noise may also prevent marine mammals from responding to acoustic cues
produced by their predators, particularly if it occurs in the same frequency band. For
example, harbor seals that reside in the coastal waters off British Columbia are frequently
targeted by mammal-eating killer whales. The seals acoustically discriminate between the
calls of mammal-eating and fish-eating killer whales (Deecke et al., 2002), a capability
that should increase survivorship while reducing the energy required to attend to all killer
whale calls. Similarly, sperm whales (Curé et al., 2016; Isojunno et al., 2016), longfinned pilot whales (Visser et al., 2016), and humpback whales (Curé et al., 2015)
changed their behavior in response to killer whale vocalization playbacks; these findings
indicate that some recognition of predator cues could be missed if the killer whale
vocalizations were masked. The potential effects of masked predator acoustic cues
depends on the duration of the masking noise and the likelihood of a marine mammal
encountering a predator during the time that detection and recognition of predator cues
are impeded.
Redundancy and context can also facilitate detection of weak signals. These
phenomena may help marine mammals detect weak sounds in the presence of natural or
manmade noise. Most masking studies in marine mammals present the test signal and the
masking noise from the same direction. The dominant background noise may be highly

directional if it comes from a particular anthropogenic source such as a ship or industrial
site. Directional hearing may significantly reduce the masking effects of these sounds by
improving the effective signal-to-noise ratio.
Masking affects both senders and receivers of acoustic signals and, at higher
levels and longer duration, can potentially have long-term chronic effects on marine
mammals at the population level as well as at the individual level. Low-frequency
ambient sound levels have increased by as much as 20 dB (more than three times in terms
of SPL) in the world's ocean from pre-industrial periods, with most of the increase from
distant commercial shipping (Hildebrand, 2009; Cholewiak et al., 2018). All
anthropogenic sound sources, but especially chronic and lower-frequency signals (e.g.,
from commercial vessel traffic), contribute to elevated ambient sound levels, thus
intensifying masking.
In addition to making it more difficult for animals to perceive and recognize
acoustic cues in their environment, anthropogenic sound presents separate challenges for
animals that are vocalizing. When they vocalize, animals are aware of environmental
conditions that affect the “active space” (or communication space) of their vocalizations,
which is the maximum area within which their vocalizations can be detected before it
drops to the level of ambient noise (Brenowitz, 2004; Brumm et al., 2004; Lohr et al.,
2003). Animals are also aware of environmental conditions that affect whether listeners
can discriminate and recognize their vocalizations from other sounds, which is more
important than simply detecting that a vocalization is occurring (Brenowitz, 1982;
Brumm et al., 2004; Dooling, 2004; Marten and Marler, 1977; Patricelli and Blickley,
2006). Most species that vocalize have evolved with an ability to make adjustments to
their vocalizations to increase the signal-to-noise ratio, active space, and
recognizability/distinguishability of their vocalizations in the face of temporary changes
in background noise (Brumm et al., 2004; Patricelli and Blickley, 2006). Vocalizing

animals can make adjustments to vocalization characteristics such as the frequency
structure, amplitude, temporal structure, and temporal delivery (repetition rate), or
ceasing to vocalize.
Many animals will combine several of these strategies to compensate for high
levels of background noise. Anthropogenic sounds that reduce the signal-to-noise ratio of
animal vocalizations, increase the masked auditory thresholds of animals listening for
such vocalizations, or reduce the active space of an animal's vocalizations impair
communication between animals. Most animals that vocalize have evolved strategies to
compensate for the effects of short-term or temporary increases in background or ambient
noise on their songs or calls. Although the fitness consequences of these vocal
adjustments are not directly known in all instances, like most other trade-offs animals
must make, some of these strategies likely come at a cost (Patricelli and Blickley, 2006;
Noren et al., 2017; Noren et al., 2020). Shifting songs and calls to higher frequencies
may also impose energetic costs (Lambrechts, 1996).
Marine mammals are also known to make vocal changes in response to
anthropogenic noise. In cetaceans, vocalization changes have been reported from
exposure to anthropogenic noise sources such as sonar, vessel noise, and seismic
surveying (see the following for examples: Gordon et al., 2003; Di Iorio and Clark, 2009;
Hatch et al., 2012; Holt et al., 2009; Holt et al., 2011; Lesage et al., 1999; McDonald et
al., 2009; Parks et al., 2007; Risch et al., 2012; Rolland et al., 2012), as well as changes
in the natural acoustic environment (Dunlop et al., 2014). Vocal changes can be
temporary or persistent. For example, model simulation suggests that the increase in
starting frequency for the North Atlantic right whale upcall over the last 50 years resulted
in increased detection ranges between right whales. The frequency shift, coupled with an
increase in call intensity by 20 dB, led to a call detectability range of less than 3 km (1.9
mi) to over 9 km (5.6 mi) (Tennessen and Parks, 2016). Holt et al. (2009) measured killer

whale call source levels and background noise levels in the 1 to 40 kHz band and
reported that the whales increased their call source levels by 1 dB SPL for every one dB
SPL increase in background noise level. Similarly, another study on St. Lawrence River
belugas reported a similar rate of increase in vocalization activity in response to passing
vessels (Scheifele et al., 2005). Di Iorio and Clark (2009) showed that blue whale calling
rates vary in association with seismic sparker survey activity, with whales calling more
on days with surveys than on days without surveys. They suggested that the whales called
more during seismic survey periods as a way to compensate for the elevated noise
conditions.
In some cases, these vocal changes may have fitness consequences, such as an
increase in metabolic rates and oxygen consumption, as observed in bottlenose dolphins
when increasing their call amplitude (Holt et al., 2015). A switch from vocal
communication to physical, surface-generated sounds, such as pectoral fin slapping or
breaching, was observed for humpback whales in the presence of increasing natural
background noise levels indicating that adaptations to masking may also move beyond
vocal modifications (Dunlop et al., 2010).
While these changes all represent possible tactics by the sound-producing animal
to reduce the impact of masking, the receiving animal can also reduce masking by using
active listening strategies such as orienting to the sound source, moving to a quieter
location, or reducing self-noise from hydrodynamic flow by remaining still. The temporal
structure of noise (e.g., amplitude modulation) may also provide a considerable release
from masking through comodulation masking release (a reduction of masking that occurs
when broadband noise, with a frequency spectrum wider than an animal's auditory filter
bandwidth at the frequency of interest, is amplitude modulated) (Branstetter and
Finneran, 2008; Branstetter et al., 2013). Signal type (e.g., whistles, burst-pulse, sonar
clicks) and spectral characteristics (e.g., frequency modulated with harmonics) may

further influence masked detection thresholds (Branstetter et al., 2016; Cunningham et
al., 2014).
Masking is more likely to occur in the presence of broadband, relatively
continuous noise sources such as vessels. Several studies have shown decreases in marine
mammal communication space and changes in behavior as a result of the presence of
vessel noise. For example, right whales were observed to shift the frequency content of
their calls upward while reducing the rate of calling in areas of increased anthropogenic
noise (Parks et al., 2007) as well as increasing the amplitude (intensity) of their calls
(Parks, 2009; Parks et al., 2011). Clark et al. (2009) observed that right whales'
communication space decreased by up to 84 percent in the presence of vessels.
Cholewiak et al. (2018) also observed loss in communication space in Stellwagen
National Marine Sanctuary for North Atlantic right whales, fin whales, and humpback
whales with increased ambient noise and shipping noise. Although humpback whales off
Australia did not change the frequency or duration of their vocalizations in the presence
of vessel noise, source levels were lower than expected compared to observed source
level changes with increased wind noise, potentially indicating some signal masking
(Dunlop, 2016). Multiple delphinid species have also been shown to increase the
minimum or maximum frequencies of their whistles in the presence of anthropogenic
noise and reduced communication space (for examples see: Holt et al., 2009; Holt et al.,
2011; Gervaise et al., 2012; Williams et al., 2013; Hermannsen et al., 2014; Papale et al.,
2015; Liu et al., 2017). While masking impacts are not a concern from lower intensity,
higher frequency HRG surveys, some degree of masking would be expected in the
vicinity of turbine pile driving (e.g., during vibratory pile driving, a continuous acoustic
source) and concentrated support vessel operation. However, pile driving is an
intermittent sound and would not be continuous throughout the day.

Habituation and Sensitization
Habituation can occur when an animal's response to a stimulus wanes with
repeated exposure, usually in the absence of unpleasant associated events (Wartzok et al.,
2003). Animals are most likely to habituate to sounds that are predictable and unvarying.
It is important to note that habituation is appropriately considered as a “progressive
reduction in response to stimuli that are perceived as neither aversive nor beneficial,”
rather than as, more generally, moderation in response to human disturbance having a
neutral or positive outcome (Bejder et al., 2009). The opposite process is sensitization,
when an unpleasant experience leads to subsequent responses, often in the form of
avoidance, at a lower level of exposure. Both habituation and sensitization require an
ongoing learning process. As noted, behavioral state may affect the type of response. For
example, animals that are resting may show greater behavioral change in response to
disturbing sound levels than animals that are highly motivated to remain in an area for
feeding (Richardson et al., 1995; U.S. National Research Council (NRC), 2003; Wartzok
et al., 2003; Southall et al., 2019b). Controlled experiments with captive marine
mammals have shown pronounced behavioral reactions, including avoidance of loud
sound sources (e.g., Ridgway et al., 1997; Finneran et al., 2003; Houser et al. (2013a);
Houser et al., 2013b; Kastelein et al., 2018). Observed responses of wild marine
mammals to loud impulsive sound sources (typically airguns or acoustic harassment
devices) have been varied but often consist of avoidance behavior or other behavioral
changes suggesting discomfort (Morton and Symonds, 2002; see also Richardson et al.,
1995; Nowacek et al., 2007; Tougaard et al., 2009; Brandt et al., 2011, Brandt et al.,
2012, Dähne et al., 2013; Brandt et al., 2014; Russell et al., 2016; Brandt et al., 2018 ).
Stone (2015) reported data from at-sea observations during 1,196 airgun surveys
from 1994 to 2010. When large arrays of airguns (considered to be 500 in 3 or more)
were firing, lateral displacement, more localized avoidance, or other changes in behavior

were evident for most odontocetes. However, significant responses to large arrays were
found only for the minke whale and fin whale. Behavioral responses observed included
changes in swimming or surfacing behavior with indications that cetaceans remained near
the water surface at these times. Behavioral observations of gray whales during an airgun
survey monitored whale movements and respirations pre-, during-, and post-seismic
survey (Gailey et al., 2016). Behavioral state and water depth were the best 'natural'
predictors of whale movements and respiration and after considering natural variation,
none of the response variables were significantly associated with survey or vessel sounds.
Many delphinids approach low-frequency airgun source vessels with no apparent
discomfort or obvious behavioral change (e.g., Barkaszi et al., 2012), indicating the
importance of frequency output in relation to the species' hearing sensitivity.
Physiological Responses
An animal's perception of a threat may be sufficient to trigger stress responses
consisting of some combination of behavioral responses, autonomic nervous system
responses, neuroendocrine responses, or immune responses (e.g., Seyle, 1950; Moberg
and Mench, 2000). In many cases, an animal's first and sometimes most economical (in
terms of energetic costs) response is behavioral avoidance of the potential stressor.
Autonomic nervous system responses to stress typically involve changes in heart rate,
blood pressure, and gastrointestinal activity. These responses have a relatively short
duration and may or may not have a significant long-term effect on an animal's fitness.
Neuroendocrine stress responses often involve the hypothalamus-pituitary-adrenal
system. Virtually all neuroendocrine functions that are affected by stress—including
immune competence, reproduction, metabolism, and behavior—are regulated by pituitary
hormones. Stress-induced changes in the secretion of pituitary hormones have been
implicated in failed reproduction, altered metabolism, reduced immune competence, and

behavioral disturbance (e.g., Moberg, 1987; Blecha, 2000). Increases in the circulation of
glucocorticoids are also equated with stress (Romano et al., 2004).
The primary distinction between stress (which is adaptive and does not normally
place an animal at risk) and “distress” is the cost of the response. During a stress
response, an animal uses glycogen stores that can be quickly replenished once the stress
is alleviated. In such circumstances, the cost of the stress response would not pose serious
fitness consequences. However, when an animal does not have sufficient energy reserves
to satisfy the energetic costs of a stress response, energy resources must be diverted from
other functions. This state of distress will last until the animal replenishes its energetic
reserves sufficiently to restore normal function.
Relationships between these physiological mechanisms, animal behavior, and the
costs of stress responses are well studied through controlled experiments and for both
laboratory and free-ranging animals (e.g., Holberton et al., 1996; Hood et al., 1998;
Jessop et al., 2003; Krausman et al., 2004; Lankford et al., 2005). Stress responses due to
exposure to anthropogenic sounds or other stressors and their effects on marine mammals
have also been reviewed (Fair and Becker, 2000; Romano et al., 2002b) and, more rarely,
studied in wild populations (e.g., Lusseau and Bejder, 2007; Romano et al., 2002a;
Rolland et al., 2012). For example, Rolland et al. (2012) found that noise reduction from
reduced ship traffic in the Bay of Fundy was associated with decreased stress in North
Atlantic right whales.
These and other studies lead to a reasonable expectation that some marine
mammals will experience physiological stress responses upon exposure to acoustic
stressors and that it is possible that some of these would be classified as “distress.” In
addition, any animal experiencing TTS would likely also experience stress responses
(NRC, 2003, 2017). Respiration naturally varies with different behaviors and variations
in respiration rate as a function of acoustic exposure can be expected to co-occur with

other behavioral reactions, such as a flight response or an alteration in diving. However,
respiration rates in and of themselves may be representative of annoyance or an acute
stress response. Mean exhalation rates of gray whales at rest and while diving were found
to be unaffected by seismic surveys conducted adjacent to the whale feeding grounds
(Gailey et al., 2007). Studies with captive harbor porpoises show increased respiration
rates upon introduction of acoustic alarms (Kastelein et al., 2001; Kastelein et al., 2006a)
and emissions for underwater data transmission (Kastelein et al., 2005). However,
exposure of the same acoustic alarm to a striped dolphin under the same conditions did
not elicit a response (Kastelein et al., 2006a), again highlighting the importance in
understanding species differences in the tolerance of underwater noise when determining
the potential for impacts resulting from anthropogenic sound exposure.
Stranding
The definition for a stranding under title IV of the MMPA is that (A) a marine
mammal is dead and is (i) on a beach or shore of the United States; or (ii) in waters under
the jurisdiction of the United States (including any navigable waters); or (B) a marine
mammal is alive and is (i) on a beach or shore of the United States and is unable to return
to the water; (ii) on a beach or shore of the United States and, although able to return to
the water, is in need of apparent medical attention; or (iii) in the waters under the
jurisdiction of the United States (including any navigable waters), but is unable to return
to its natural habitat under its own power or without assistance (16 U.S.C. 1421h).
Marine mammal strandings have been linked to a variety of causes, such as illness
from exposure to infectious agents, biotoxins, or parasites; starvation; unusual
oceanographic or weather events; or anthropogenic causes including fishery interaction,
vessel strike, entrainment, entrapment, sound exposure, or combinations of these stressors
sustained concurrently or in series. There have been multiple events worldwide in which
marine mammals (primarily beaked whales, or other deep divers) have stranded

coincident with relatively nearby activities utilizing loud sound sources (primarily
military training events), and five in which mid-frequency active sonar has been more
definitively determined to have been a contributing factor.
There are multiple theories regarding the specific mechanisms responsible for
marine mammal strandings caused by exposure to loud sounds. One primary theme is the
behaviorally mediated responses of deep-diving species (odontocetes), in which their
startled response to an acoustic disturbance 1) affects ascent or descent rates, the time
they stay at depth or the surface, or other regular dive patterns that are used to
physiologically manage gas formation and absorption within their bodies, such that the
formation or growth of gas bubbles damages tissues or causes other injury, or 2) results in
their flight to shallow areas, enclosed bays, or other areas considered “out of habitat,” in
which they become disoriented and physiologically compromised. For more information
on marine mammal stranding events and potential causes, please see the Mortality and
Stranding section of NMFS Proposed Incidental Take Regulations for the Navy’s
Training and Testing Activities in the Hawaii-Southern California Training and Testing
Study Area (50 CFR Part 218, Volume 83, No. 123, June 26, 2018).
The construction activities proposed by SouthCoast (e.g., pile driving) do not
inherently have the potential to result in marine mammal strandings. While vessel strikes
could kill or injure a marine mammal (which may eventually strand), the required
mitigation measures would reduce the potential for take from these activities to de
minimus levels (see Proposed Mitigation section for more details). As described above,
no mortality or serious injury is anticipated or proposed for authorization from any
specified activities.
Of the strandings documented to date worldwide, NMFS is not aware of any
being attributed to pile driving or the types of HRG equipment proposed for use during
SouthCoast’s surveys. Recently, there has been heightened interest in HRG surveys

relative to recent marine mammals strandings along the U.S. East Coast. HRG surveys
involve the use of certain sources to image the ocean bottom, which are very different
from seismic airguns used in oil and gas surveys or tactical military sonar, in that they
produce much smaller impact zones. Marine mammals may respond to exposure to these
sources by, for example, avoiding the immediate area, which is why offshore wind
developers have authorization to allow for Level B (behavioral) harassment, including
SouthCoast. However, because of the combination of lower source levels, higher
frequency, narrower beam-width (for some sources), and other factors, the area within
which a marine mammal might be expected to be behaviorally disturbed by HRG sources
is much smaller (by orders of magnitude) than the impact areas for seismic airguns or the
military sonar with which a small number of marine mammal have been causally
associated. Specifically, estimated harassment zones for HRG surveys are typically less
than 200 m (656.2 ft) (such as those associated with the project), while zones for military
mid-frequency active sonar or seismic airgun surveys typically extend for several
kilometers ranging up to 10s of kilometers. Further, because of this much smaller
ensonified area, any marine mammal exposure to HRG sources is reasonably expected to
be at significantly lower levels and shorter duration (associated with less severe
responses), and there is no evidence suggesting, or reason to speculate, that marine
mammals exposed to HRG survey noise are likely to be injured, much less strand, as a
result. Last, all but one of the small number of marine mammal stranding events that have
been causally associated with exposure to loud sound sources have been deep-diving
toothed whale species (not mysticetes), which are known to respond differently to loud
sounds. NMFS has performed a thorough review of a report submitted by Rand (2023)
that includes measurements of the Geo-Marine Geo-Source 400 sparker and suggests that
NMFS is assuming lower source and received levels than is appropriate in its assessments
of HRG impacts. NMFS has determined that the values in this proposed rule are

appropriate, based on the model methodology (i.e., the assumed source level propagated
using spherical spreading) here predicting a peak level 3 dB louder than the maximum
measured peak level at the closest measurement range in Rand (2023).
Also of note, in an assessment of monitoring reports for HRG surveys received
from 2021 through 2023, as compared to the takes of marine mammals authorized, an
average of fewer than 15 percent have been detected within harassment zones, with no
more than 27 percent for any species (common dolphins) and 20 percent or less for all
other species. The most common behavioral change observed while the HRG sound
source was active was "change direction" (i.e. a potential behavioral reaction) though
detections of "no behavioral change" occurred at least twice as many times as "change
direction.”
Potential Effects of Disturbance on Marine Mammal Fitness
The different ways that marine mammals respond to sound are sometimes
indicators of the ultimate effect that exposure to a given stimulus will have on the wellbeing (survival, reproduction, etc.) of an animal. There is numerous data relating the
exposure of terrestrial mammals from sound to effects on reproduction or survival, and
data for marine mammals continues to accumulate. Several authors have reported that
disturbance stimuli may cause animals to abandon nesting and foraging sites (Sutherland
and Crockford, 1993); may cause animals to increase their activity levels and suffer
premature deaths or reduced reproductive success when their energy expenditures exceed
their energy budgets (Daan et al., 1996; Feare, 1976; Mullner et al., 2004); or may cause
animals to experience higher predation rates when they adopt risk-prone foraging or
migratory strategies (Frid and Dill, 2002). Each of these studies addressed the
consequences of animals shifting from one behavioral state (e.g., resting or foraging) to
another behavioral state (e.g., avoidance or escape behavior) because of human
disturbance or disturbance stimuli.

Attention is the cognitive process of selectively concentrating on one aspect of an
animal's environment while ignoring other things (Posner, 1994). Because animals
(including humans) have limited cognitive resources, there is a limit to how much
sensory information they can process at any time. The phenomenon called “attentional
capture” occurs when a stimulus (usually a stimulus that an animal is not concentrating
on or attending to) “captures” an animal's attention. This shift in attention can occur
consciously or subconsciously (for example, when an animal hears sounds that it
associates with the approach of a predator) and the shift in attention can be sudden
(Dukas, 2002; van Rij, 2007). Once a stimulus has captured an animal's attention, the
animal can respond by ignoring the stimulus, assuming a “watch and wait” posture, or
treat the stimulus as a disturbance and respond accordingly, which includes scanning for
the source of the stimulus or “vigilance” (Cowlishaw et al., 2004).
Vigilance is an adaptive behavior that helps animals determine the presence or
absence of predators, assess their distance from conspecifics, or to attend cues from prey
(Bednekoff and Lima, 1998; Treves, 2000). Despite those benefits, however, vigilance
has a cost of time; when animals focus their attention on specific environmental cues,
they are not attending to other activities such as foraging or resting. These effects have
generally not been demonstrated for marine mammals, but studies involving fish and
terrestrial animals have shown that increased vigilance may substantially reduce feeding
rates (Saino, 1994; Beauchamp and Livoreil, 1997; Fritz et al., 2002; Purser and Radford,
2011). Animals will spend more time being vigilant, which may translate to less time
foraging or resting, when disturbance stimuli approach them more directly, remain at
closer distances, have a greater group size (e.g., multiple surface vessels), or when they
co-occur with times that an animal perceives increased risk (e.g., when they are giving
birth or accompanied by a calf).

The primary mechanism by which increased vigilance and disturbance appear to
affect the fitness of individual animals is by disrupting an animal's time budget and, as a
result, reducing the time they might spend foraging and resting (which increases an
animal's activity rate and energy demand while decreasing their caloric intake/energy). In
a study of northern resident killer whales off Vancouver Island, exposure to boat traffic
was shown to reduce foraging opportunities and increase traveling time (Holt et al.,
2021). A simple bioenergetics model was applied to show that the reduced foraging
opportunities equated to a decreased energy intake of 18 percent while the increased
traveling incurred an increased energy output of 3-4 percent, which suggests that a
management action based on avoiding interference with foraging might be particularly
effective.
On a related note, many animals perform vital functions, such as feeding, resting,
traveling, and socializing, on a diel cycle (24-hr cycle). Behavioral reactions to noise
exposure (such as disruption of critical life functions, displacement, or avoidance of
important habitat) are more likely to be significant for fitness if they last more than one
diel cycle or recur on subsequent days (Southall et al., 2007). Consequently, a behavioral
response lasting less than one day and not recurring on subsequent days is not considered
particularly severe unless it could directly affect reproduction or survival (Southall et al.,
2007). It is important to note the difference between behavioral reactions lasting or
recurring over multiple days and anthropogenic activities lasting or recurring over
multiple days. For example, just because certain activities last for multiple days does not
necessarily mean that individual animals will be either exposed to those activity-related
stressors (i.e., pile driving) for multiple days or further exposed in a manner that would
result in sustained multi-day substantive behavioral responses. However, special attention
is warranted where longer-duration activities overlay areas in which animals are known
to congregate for longer durations for biologically important behaviors.

There are few studies that directly illustrate the impacts of disturbance on marine
mammal populations. Lusseau and Bejder (2007) present data from three long-term
studies illustrating the connections between disturbance from whale-watching boats and
population-level effects in cetaceans. In Shark Bay, Australia, the abundance of
bottlenose dolphins was compared within adjacent control and tourism sites over three
consecutive 4.5-year periods of increasing tourism levels. Between the second and third
time periods, in which tourism doubled, dolphin abundance decreased by 15 percent in
the tourism area and did not change significantly in the control area. In Fiordland, New
Zealand, two populations (Milford and Doubtful Sounds) of bottlenose dolphins with
tourism levels that differed by a factor of seven were observed and significant increases
in traveling time and decreases in resting time were documented for both. Consistent
short-term avoidance strategies were observed in response to tour boats until a threshold
of disturbance was reached (average 68 minutes between interactions), after which the
response switched to a longer-term habitat displacement strategy. For one population,
tourism only occurred in a part of the home range. However, tourism occurred throughout
the home range of the Doubtful Sound population and once boat traffic increased beyond
the 68-minute threshold (resulting in abandonment of their home range/preferred habitat),
reproductive success drastically decreased (increased stillbirths) and abundance
decreased significantly (from 67 to 56 individuals in a short period).
In order to understand how the effects of activities may or may not impact species
and stocks of marine mammals, it is necessary to understand not only what the likely
disturbances are going to be but how those disturbances may affect the reproductive
success and survivorship of individuals and then how those impacts to individuals
translate to population-level effects. Following on the earlier work of a committee of the
U.S. National Research Council (NRC, 2005); New et al. (2014), in an effort termed the
Potential Consequences of Disturbance (PCoD), outline an updated conceptual model of

the relationships linking disturbance to changes in behavior and physiology, health, vital
rates, and population dynamics. This framework is a four-step process progressing from
changes in individual behavior and/or physiology, to changes in individual health, then
vital rates, and finally to population-level effects. In this framework, behavioral and
physiological changes can have direct (acute) effects on vital rates, such as when changes
in habitat use or increased stress levels raise the probability of mother-calf separation or
predation; indirect and long-term (chronic) effects on vital rates, such as when changes in
time/energy budgets or increased disease susceptibility affect health, which then affects
vital rates; or no effect to vital rates (New et al., 2014).
Since the PCoD general framework was outlined and the relevant supporting
literature compiled, multiple studies developing state-space energetic models for species
with extensive long-term monitoring (e.g., southern elephant seals, North Atlantic right
whales, Ziphiidae beaked whales, and bottlenose dolphins) have been conducted and can
be used to effectively forecast longer-term population-level impacts from behavioral
changes. While these are very specific models with very specific data requirements that
cannot yet be applied broadly to project-specific risk assessments for the majority of
species, they are a critical first step towards being able to quantify the likelihood of a
population level effect. Since New et al. (2014), several publications have described
models developed to examine the long-term effects of environmental or anthropogenic
disturbance of foraging on various life stages of selected species (e.g., sperm whale,
Farmer et al. (2018); California sea lion, McHuron et al. (2018); blue whale, Pirotta et al.
(2018a); humpback whale, Dunlop et al. (2021)). These models continue to add to
refinement of the approaches to the PCoD framework. Such models also help identify
what data inputs require further investigation. Pirotta et al. (2018b) provides a review of
the PCoD framework with details on each step of the process and approaches to applying
real data or simulations to achieve each step.

Despite its simplicity, there are few complete PCoD models available for any
marine mammal species due to a lack of data available to parameterize many of the steps.
To date, no PCoD model has been fully parameterized with empirical data (Pirotta et al.,
2018a) due to the fact they are data intensive and logistically challenging to complete.
Therefore, most complete PCoD models include simulations, theoretical modeling, and
expert opinion to move through the steps. For example, PCoD models have been
developed to evaluate the effect of wind farm construction on the North Sea harbor
porpoise populations (e.g., King et al., 2015; Nabe-Nielsen et al., 2018). These models
include a mix of empirical data, expert elicitation (King et al., 2015) and simulations of
animals’ movements, energetics, and/or survival (New et al., 2014; Nabe-Nielsen et al.,
2018).
PCoD models may also be approached in different manners. Dunlop et al. (2021)
modeled migrating humpback whale mother-calf pairs in response to seismic surveys
using both a forwards and backwards approach. While a typical forwards approach can
determine if a stressor would have population-level consequences, Dunlop et al.
demonstrated that working backwards through a PCoD model can be used to assess the
“worst case” scenario for an interaction of a target species and stressor. This method may
be useful for future management goals when appropriate data becomes available to fully
support the model. In another example, harbor porpoise PCoD model investigating the
impact of seismic surveys on harbor porpoise included an investigation on underlying
drivers of vulnerability. Harbor porpoise movement and foraging were modeled for
baseline periods and then for periods with seismic surveys as well; the models
demonstrated that temporal (i.e., seasonal) variation in individual energetics and their link
to costs associated with disturbances was key in predicting population impacts (Gallagher
et al., 2021).

Behavioral change, such as disturbance manifesting in lost foraging time, in
response to anthropogenic activities is often assumed to indicate a biologically significant
effect on a population of concern. However, as described above, individuals may be able
to compensate for some types and degrees of shifts in behavior, preserving their health
and thus their vital rates and population dynamics. For example, New et al. (2013)
developed a model simulating the complex social, spatial, behavioral and motivational
interactions of coastal bottlenose dolphins in the Moray Firth, Scotland, to assess the
biological significance of increased rate of behavioral disruptions caused by vessel
traffic. Despite a modeled scenario in which vessel traffic increased from 70 to 470
vessels a year (a six-fold increase in vessel traffic) in response to the construction of a
proposed offshore renewables' facility, the dolphins' behavioral time budget, spatial
distribution, motivations, and social structure remain unchanged. Similarly, two
bottlenose dolphin populations in Australia were also modeled over 5 years against a
number of disturbances (Reed et al., 2020), and results indicated that habitat/noise
disturbance had little overall impact on population abundances in either location, even in
the most extreme impact scenarios modeled.
By integrating different sources of data (e.g., controlled exposure data, activity
monitoring, telemetry tracking, and prey sampling) into a theoretical model to predict
effects from sonar on a blue whale’s daily energy intake, Pirotta et al. (2021) found that
tagged blue whales’ activity budgets, lunging rates, and ranging patterns caused
variability in their predicted cost of disturbance. This method may be useful for future
management goals when appropriate data becomes available to fully support the model.
Harbor porpoise movement and foraging were modeled for baseline periods and then for
periods with seismic surveys as well; the models demonstrated that the seasonality of the
seismic activity was an important predictor of impact (Gallagher et al., 2021).

Keen et al. (2021) summarize the emerging themes in PCoD models that should
be considered when assessing the likelihood and duration of exposure and the sensitivity
of a population to disturbance (see Table 1 from Keen et al., 2021). The themes are
categorized by life history traits (movement ecology, life history strategy, body size, and
pace of life), disturbance source characteristics (overlap with biologically important
areas, duration and frequency, and nature and context), and environmental conditions
(natural variability in prey availability and climate change). Keen et al. (2021) then
summarize how each of these features influence an assessment, noting, for example, that
individual animals with small home ranges have a higher likelihood of prolonged or yearround exposure, that the effect of disturbance is strongly influenced by whether it
overlaps with biologically important habitats when individuals are present, and that
continuous disruption will have a greater impact than intermittent disruption.
Nearly all PCoD studies and experts agree that infrequent exposures of a single
day or less are unlikely to impact individual fitness, let alone lead to population level
effects (Booth et al., 2016; Booth et al., 2017; Christiansen and Lusseau 2015; Farmer et
al., 2018; Wilson et al., 2020; Harwood and Booth 2016; King et al., 2015; McHuron et
al., 2018; National Academies of Sciences, Engineering, and Medicine (NAS) 2017; New
et al., 2014; Pirotta et al., 2018a; Southall et al., 2007; Villegas-Amtmann et al., 2015).
As described through this proposed rule, NMFS expects that any behavioral disturbance
that would occur due to animals being exposed to construction activity would be of a
relatively short duration, with behavior returning to a baseline state shortly after the
acoustic stimuli ceases or the animal moves far enough away from the source. Given this,
and NMFS' evaluation of the available PCoD studies, and the required mitigation
discussed later, any such behavioral disturbance resulting from SouthCoast’s activities is
not expected to impact individual animals' health or have effects on individual animals'
survival or reproduction, thus no detrimental impacts at the population level are

anticipated. Marine mammals may temporarily avoid the immediate area but are not
expected to permanently abandon the area or their migratory or foraging behavior.
Impacts to breeding, feeding, sheltering, resting, or migration are not expected nor are
shifts in habitat use, distribution, or foraging success.
Potential Effects from Explosive Sources
With respect to the noise from underwater explosives, the same acoustic-related
impacts described above apply and are not repeated here. Noise from explosives can
cause hearing impairment if an animal is close enough to the sources; however, because
noise from an explosion is discrete, lasting less than approximately one second, no
behavioral impacts below the TTS threshold are anticipated considering that SouthCoast
would not detonate more than one UXO/MEC per day and only ten during the life of the
proposed rule. This section focuses on the pressure-related impacts of underwater
explosives, including physiological injury and mortality.
Underwater explosive detonations send a shock wave and sound energy through
the water and can release gaseous by-products, create an oscillating bubble, or cause a
plume of water to shoot up from the water surface. The shock wave and accompanying
noise are of most concern to marine animals. Depending on the intensity of the shock
wave and size, location, and depth of the animal, an animal can be injured, killed, suffer
non-lethal physical effects, experience hearing related effects with or without behavioral
responses, or exhibit temporary behavioral responses or tolerance from hearing the blast
sound. Generally, exposures to higher levels of impulse and pressure levels would result
in greater impacts to an individual animal.
Injuries resulting from a shock wave take place at boundaries between tissues of
different densities. Different velocities are imparted to tissues of different densities, and
this can lead to their physical disruption. Blast effects are greatest at the gas-liquid
interface (Landsberg, 2000). Gas-containing organs, particularly the lungs and

gastrointestinal tract, are especially susceptible (Goertner, 1982; Hill, 1978; Yelverton et
al., 1973). Intestinal walls can bruise or rupture, with subsequent hemorrhage and escape
of gut contents into the body cavity. Less severe gastrointestinal tract injuries include
contusions, petechiae (small red or purple spots caused by bleeding in the skin), and
slight hemorrhaging (Yelverton et al., 1973).
Because the ears are the most sensitive to pressure, they are the organs most
sensitive to injury (Ketten, 2000). Sound-related damage associated with sound energy
from detonations can be theoretically distinct from injury from the shock wave,
particularly farther from the explosion. If a noise is audible to an animal, it has the
potential to damage the animal's hearing by causing decreased sensitivity (Ketten, 1995).
Lethal impacts are those that result in immediate death or serious debilitation in or near
an intense source and are not, technically, pure acoustic trauma (Ketten, 1995). Sublethal
impacts include hearing loss, which is caused by exposures to perceptible sounds. Severe
damage (from the shock wave) to the ears includes tympanic membrane rupture, fracture
of the ossicles, and damage to the cochlea, hemorrhage, and cerebrospinal fluid leakage
into the middle ear. Moderate injury implies partial hearing loss due to tympanic
membrane rupture and blood in the middle ear. Permanent hearing loss also can occur
when the hair cells are damaged by one very loud event as well as by prolonged exposure
to a loud noise or chronic exposure to noise. The level of impact from blasts depends on
both an animal's location and at outer zones, its sensitivity to the residual noise (Ketten,
1995).
Given the mitigation measures proposed, it is unlikely that any of the more
serious injuries or mortality discussed above will result from any UXO/MEC detonation
that SouthCoast might need to undertake. PTS, TTS, and brief startle reactions are the
most likely impacts to result from this activity, if it occurs (noting detonation is the last
method to be chosen for removal).

Potential Effects from Vessel Strike
Vessel collisions with marine mammals, also referred to as vessel strikes or ship
strikes, can result in death or serious injury of the animal. The most vulnerable marine
mammals are those that spend extended periods of time at the surface in order to restore
oxygen levels within their tissues after deep dives (e.g., the sperm whale). Some baleen
whales seem generally unresponsive to vessel sound, making them more susceptible to
vessel collisions (Nowacek et al., 2004). Marine mammal responses to vessels may
include avoidance and changes in dive pattern (NRC, 2003). Wounds resulting from
vessel strike may include massive trauma, hemorrhaging, broken bones, or propeller
lacerations (Knowlton and Kraus, 2001). An animal at the surface could be struck
directly by a vessel, a surfacing animal could hit the bottom of a vessel, or an animal just
below the surface could be cut by a vessel's propeller. Superficial strikes may not kill or
result in the death of the animal. Lethal interactions are typically associated with large
whales, which are occasionally found draped across the bulbous bow of large commercial
ships upon arrival in port. Although smaller cetaceans are more maneuverable in relation
to large vessels than are large whales, they may also be susceptible to strike. The severity
of injuries typically depends on the size and speed of the vessel (Knowlton and Kraus,
2001; Laist et al., 2001; Vanderlaan and Taggart, 2007; Conn and Silber, 2013). Impact
forces increase with speed as does the probability of a strike at a given distance (Silber et
al., 2010; Gende et al., 2011).
An examination of all known vessel strikes from all shipping sources (civilian and
military) indicates vessel speed is a principal factor in whether a vessel strike occurs and,
if so, whether it results in injury, serious injury, or mortality (Knowlton and Kraus, 2001;
Laist et al., 2001; Jensen and Silber, 2003; Pace and Silber, 2005; Vanderlaan and
Taggart, 2007; Conn and Silber, 2013). In assessing records in which vessel speed was
known, Laist et al. (2001) found a direct relationship between the occurrence of a whale

strike and the speed of the vessel involved in the collision. The authors concluded that
most deaths occurred when a vessel was traveling in excess of 13 knots (15 mph).
Jensen and Silber (2003) detailed 292 records of known or probable vessel strikes
of all large whale species from 1975 to 2002. Of these, vessel speed at the time of
collision was reported for 58 cases. Of these 58 cases, 39 (or 67 percent) resulted in
serious injury or death (19 of those resulted in serious injury as determined by blood in
the water, propeller gashes or severed tailstock, and fractured skull, jaw, vertebrae,
hemorrhaging, massive bruising or other injuries noted during necropsy and 20 resulted
in death). Operating speeds of vessels that struck various species of large whales ranged
from 2 to 51 knots (2.3 to 59 mph). The majority (79 percent) of these strikes occurred at
speeds of 13 knots (15 mph) or greater. The average speed that resulted in serious injury
or death was 18.6 knots (21.4 mph). Pace and Silber (2005) found that the probability of
death or serious injury increased rapidly with increasing vessel speed. Specifically, the
predicted probability of serious injury or death increased from 45 to 75 percent as vessel
speed increased from 10 to 14 knots (11.5 to 16 mph), and exceeded 90 percent at 17
knots (20 mph). Higher speeds during collisions result in greater force of impact and also
appear to increase the chance of severe injuries or death. While modeling studies have
suggested that hydrodynamic forces pulling whales toward the vessel hull increase with
increasing speed (Clyne, 1999; Knowlton et al., 1995), this is inconsistent with Silber et
al. (2010), which demonstrated that there is no such relationship (i.e., hydrodynamic
forces are independent of speed).
In a separate study, Vanderlaan and Taggart (2007) analyzed the probability of
lethal mortality of large whales at a given speed, showing that the greatest rate of change
in the probability of a lethal injury to a large whale as a function of vessel speed occurs
between 8.6 and 15 knots (9.9 and 17 mph). The chances of a lethal injury decline from
approximately 80 percent at 15 knots (17 mph) to approximately 20 percent at 8.6 knots

(10 mph). At speeds below 11.8 knots (13.5 mph), the chances of lethal injury drop
below 50 percent, while the probability asymptotically increases toward 100 percent
above 15 knots (17 mph).
The Jensen and Silber (2003) report notes that the Large Whale Ship Strike
Database represents a minimum number of collisions, because the vast majority go
undetected or unreported. In contrast, SouthCoast’s personnel are likely to detect any
strike that does occur because of the required personnel training and lookouts, along with
the inclusion of PSOs as described in the Proposed Mitigation section), and they are
required to report all ship strikes involving marine mammals.
There are no known vessel strikes of marine mammals by any offshore wind
energy vessel in the U.S. Given the extensive mitigation and monitoring measures (see
the Proposed Mitigation and Proposed Monitoring and Reporting section) that would
be required of SouthCoast, NMFS believes that a vessel strike is not likely to occur.
Potential Effects to Marine Mammal Habitat
SouthCoast’s proposed activities could potentially affect marine mammal habitat
through the introduction of impacts to the prey species of marine mammals (through
noise, oceanographic processes, or reef effects), acoustic habitat (sound in the water
column), water quality, and biologically important habitat for marine mammals.
Effects on Prey
Sound may affect marine mammals through impacts on the abundance, behavior,
or distribution of prey species (e.g., crustaceans, cephalopods, fish, and zooplankton).
Marine mammal prey varies by species, season, and location and, for some, is not well
documented. Here, we describe studies regarding the effects of noise on known marine
mammal prey.
Fish utilize the soundscape and components of sound in their environment to
perform important functions such as foraging, predator avoidance, mating, and spawning

(e.g., Zelick and Mann., 1999; Fay, 2009). The most likely effects on fishes exposed to
loud, intermittent, low-frequency sounds are behavioral responses (i.e., flight or
avoidance). Short duration, sharp sounds (such as pile driving or airguns) can cause overt
or subtle changes in fish behavior and local distribution. The reaction of fish to acoustic
sources depends on the physiological state of the fish, past exposures, motivation (e.g.,
feeding, spawning, migration), and other environmental factors. Key impacts to fishes
may include behavioral responses, hearing damage, barotrauma (pressure-related
injuries), and mortality. While it is clear that the behavioral responses of individual prey,
such as displacement or other changes in distribution, can have direct impacts on the
foraging success of marine mammals, the effects on marine mammals of individual prey
that experience hearing damage, barotrauma, or mortality is less clear, though obviously
population scale impacts that meaningfully reduce the amount of prey available could
have more serious impacts.
Fishes, like other vertebrates, have a variety of different sensory systems to glean
information from ocean around them (Astrup and Mohl, 1993; Astrup, 1999; Braun and
Grande, 2008; Carroll et al., 2017; Hawkins and Johnstone, 1978; Ladich and Popper,
2004; Ladich and Schulz-Mirbach, 2016; Mann, 2016; Nedwell et al., 2004; Popper et
al., 2003; Popper et al., 2005). Depending on their hearing anatomy and peripheral
sensory structures, which vary among species, fishes hear sounds using pressure and
particle motion sensitivity capabilities and detect the motion of surrounding water (Fay et
al., 2008) (terrestrial vertebrates generally only detect pressure). Most marine fishes
primarily detect particle motion using the inner ear and lateral line system while some
fishes possess additional morphological adaptations or specializations that can enhance
their sensitivity to sound pressure, such as a gas-filled swim bladder (Braun and Grande,
2008; Popper and Fay, 2011).

Hearing capabilities vary considerably between different fish species with data
only available for just over 100 species out of the 34,000 marine and freshwater fish
species (Eschmeyer and Fong, 2016). In order to better understand acoustic impacts on
fishes, fish hearing groups are defined by species that possess a similar continuum of
anatomical features, which result in varying degrees of hearing sensitivity (Popper and
Hastings, 2009a). There are four hearing groups defined for all fish species (modified
from Popper et al., 2014) within this analysis, and they include: fishes without a swim
bladder (e.g., flatfish, sharks, rays, etc.); fishes with a swim bladder not involved in
hearing (e.g., salmon, cod, pollock, etc.); fishes with a swim bladder involved in hearing
(e.g., sardines, anchovy, herring, etc.); and fishes with a swim bladder involved in
hearing and high-frequency hearing (e.g., shad and menhaden). Most marine mammal
fish prey species would not be likely to perceive or hear mid- or high-frequency
sonars.While hearing studies have not been done on sardines and northern anchovies, it
would not be unexpected for them to have hearing similarities to Pacific herring (up to 25 kHz) (Mann et al., 2005). Currently, less data are available to estimate the range of best
sensitivity for fishes without a swim bladder.
In terms of physiology, multiple scientific studies have documented a lack of
mortality or physiological effects to fish from exposure to low- and mid-frequency sonar
and other sounds (Halvorsen et al., 2012a; Jørgensen et al., 2005; Juanes et al., 2017;
Kane et al., 2010; Kvadsheim and Sevaldsen, 2005; Popper et al., 2007; Popper et al.,
2016; Watwood et al., 2016). Techer et al. (2017) exposed carp in floating cages for up to
30 days to low-power 23 and 46 kHz source without any significant physiological
response. Other studies have documented either a lack of TTS in species whose hearing
range cannot perceive sonar (such as Navy sonar), or for those species that could perceive
sonar-like signals, any TTS experienced would be recoverable (Halvorsen et al., 2012a;
Ladich and Fay, 2013; Popper and Hastings, 2009a, 2009b; Popper et al., 2014; Smith,

2016). Only fishes that have specializations that enable them to hear sounds above about
2,500 Hz (2.5 kHz), such as herring (Halvorsen et al., 2012a; Mann et al., 2005; Mann,
2016; Popper et al., 2014), would have the potential to receive TTS or exhibit behavioral
responses from exposure to mid-frequency sonar. In addition, any sonar induced TTS to
fish with a hearing range could perceive sonar would only occur in the narrow spectrum
of the source (e.g., 3.5 kHz) compared to the fish's total hearing range (e.g., 0.01 kHz to 5
kHz).
In terms of behavioral responses, Juanes et al. (2017) discuss the potential for
negative impacts from anthropogenic noise on fish, but the author's focus was on broader
based sounds, such as ship and boat noise sources. Watwood et al. (2016) also
documented no behavioral responses by reef fish after exposure to mid-frequency active
sonar. Doksaeter et al. (2009; 2012) reported no behavioral responses to mid-frequency
sonar (such as naval sonar) by Atlantic herring; specifically, no escape reactions
(vertically or horizontally) were observed in free swimming herring exposed to midfrequency sonar transmissions. Based on these results (Doksaeter et al., 2009; Doksaeter
et al., 2012; Sivle et al., 2012), Sivle et al. (2014) created a model in order to report on
the possible population-level effects on Atlantic herring from active sonar. The authors
concluded that the use of sonar poses little risk to populations of herring regardless of
season, even when the herring populations are aggregated and directly exposed to sonar.
Finally, Bruintjes et al. (2016) commented that fish exposed to any short-term noise
within their hearing range might initially startle, but would quickly return to normal
behavior.
Pile-driving noise during construction is of particular concern as the very high
sound pressure levels could potentially prevent fish from reaching breeding or spawning
sites, finding food, and acoustically locating mates. A playback study in West Scotland
revealed that there was a significant movement response to the pile-driving stimulus in

both species at relatively low received sound pressure levels (sole: 144 – 156 dB re 1μPa
Peak; cod: 140 – 161 dB re 1 μPa Peak, particle motion between 51 x 10 and 62 x 1044
m/s2 peak) (Mueller-Blenkle et al., 2010). The swimming speed of the sole increased
significantly during the playback period compared to before and after playback of
construction noise when compared to the playbacks of before and after construction.
While not statistically significant, cod also displayed a similar reaction, yet results were
not significant. Cod showed a behavioral response during before, during, and after
construction playbacks. However, cod demonstrated a specific and significant freezing
response at the onset and cessation of the playback recording. Both species displayed
indications of directional movements away from the playback source. During wind farm
construction in the Eastern Taiwan Strait, Type 1 soniferous fish chorusing showed a
relatively lower intensity and longer duration, while Type 2 chorusing exhibited higher
intensity and no changes in its duration. Deviation from regular fish vocalization patterns
may affect fish reproductive success, cause migration, augmented predation, or
physiological alterations.
Occasional behavioral reactions to activities that produce underwater noise
sources are unlikely to cause long-term consequences for individual fish or populations.
The most likely impact to fish from impact and vibratory pile driving activities at the
project areas would be temporary behavioral avoidance of the area. Any behavioral
avoidance by fish of the disturbed area would still leave significantly large areas of fish
and marine mammal foraging habitat in the nearby vicinity. The duration of fish
avoidance of an area after pile driving stops is unknown, but a rapid return to normal
recruitment, distribution and behavior is anticipated. In general, impacts to marine
mammal prey species are expected to be minor and temporary due to the expected short
daily duration of individual pile driving events and the relatively small areas being
affected.

SPLs of sufficient strength have been known to cause fish auditory impairment,
injury, and mortality. Popper et al. (2014) found that fish with or without air bladders
could experience TTS at 186 dB SELcum. Mortality could occur for fish without swim
bladders at >216 dB SELcum. Those with swim bladders or at the egg or larvae life stage,
mortality was possible at >203 dB SELcum. Other studies found that 203 dB SELcum or
above caused a physiological response in other fish species (Casper et al., 2012;
Halvorsen et al., 2012a; Halvorsen et al., 2012b; Casper et al., 2013a; Casper et al.,
2013b). However, in most fish species, hair cells in the ear continuously regenerate and
loss of auditory function likely is restored when damaged cells are replaced with new
cells. Halvorsen et al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24
hours for one species. Impacts would be most severe when the individual fish is close to
the source and when the duration of exposure is long. Injury caused by barotrauma can
range from slight to severe and can cause death and is most likely for fish with swim
bladders. Barotrauma injuries have been documented during controlled exposure to
impact pile driving (Halvorsen et al., 2012b; Casper et al., 2013a).
As described in the Proposed Mitigation section below, SouthCoast would
utilize a sound attenuation device which would reduce potential for injury to marine
mammal prey. Other fish that experience hearing loss as a result of exposure to
explosions and impulsive sound sources may have a reduced ability to detect relevant
sounds such as predators, prey, or social vocalizations. However, PTS has not been
known to occur in fishes and any hearing loss in fish may be as temporary as the
timeframe required to repair or replace the sensory cells that were damaged or destroyed
(Popper et al., 2005; Popper et al., 2014; Smith et al., 2006). It is not known if damage to
auditory nerve fibers could occur, and if so, whether fibers would recover during this
process.

It is also possible for fish to be injured or killed by an explosion from UXO/MEC
detonation. Physical effects from pressure waves generated by underwater sounds (e.g.,
underwater explosions) could potentially affect fish within proximity of the UXO/MEC
detonation. The shock wave from an underwater explosion is lethal to fish at close range,
causing massive organ and tissue damage and internal bleeding (Keevin and Hempen,
1997). At greater distance from the detonation point, the extent of mortality or injury
depends on a number of factors including fish size, body shape, orientation, and species
(Keevin and Hempen, 1997; Wright, 1982). At the same distance from the source, larger
fish are generally less susceptible to death or injury, elongated forms that are round in
cross-section are less at risk than deep-bodied forms, and fish oriented sideways to the
blast suffer the greatest impact (Edds-Walton and Finneran, 2006; O'Keeffe, 1984;
O'Keeffe and Young, 1984; Wiley et al., 1981; Yelverton et al., 1975). Species with gasfilled organs are more susceptible to injury and mortality than those without them
(Gaspin, 1975; Gaspin et al., 1976; Goertner et al., 1994). Barotrauma injuries have been
documented during controlled exposure to impact pile driving (an impulsive noise source,
as are explosives and air guns) (Halvorsen et al., 2012b; Casper et al., 2013).
Fish not killed or driven from a location by an explosion might change their
behavior, feeding pattern, or distribution. Changes in behavior of fish have been observed
as a result of sound produced by explosives, with effect intensified in areas of hard
substrate (Wright, 1982). Stunning from pressure waves could also temporarily
immobilize fish, making them more susceptible to predation. The abundances of various
fish (and invertebrates) near the detonation point for explosives could be altered for a few
hours before animals from surrounding areas repopulate the area. However, these
populations would likely be replenished as waters near the detonation point are mixed
with adjacent waters.

UXO/MEC detonations would be dispersed in space and time; therefore, repeated
exposure of individual fishes are unlikely. Mortality and injury effects to fishes from
explosives would be localized around the area of a given in-water explosion but only if
individual fish and the explosive (and immediate pressure field) were co-located at the
same time. Repeated exposure of individual fish to sound and energy from underwater
explosions is not likely given fish movement patterns, especially schooling prey species.
In addition, most acoustic effects, if any, are expected to be short-term and localized.
Long-term consequences for fish populations, including key prey species within the
project area, would not be expected.
Required soft-starts would allow prey and marine mammals to move away from
the impact pile driving source prior to any noise levels that may physically injure prey,
and the use of the noise attenuation devices would reduce noise levels to the degree any
mortality or injury of prey is also minimized. Use of bubble curtains, in addition to
reducing impacts to marine mammals, for example, is a key mitigation measure in
reducing injury and mortality of ESA-listed salmon on the U.S. West Coast. However,
we recognize some mortality, physical injury and hearing impairment in marine mammal
prey may occur, but we anticipate the amount of prey impacted in this manner is minimal
compared to overall availability. Any behavioral responses to pile driving by marine
mammal prey are expected to be brief. We expect that other impacts, such as stress or
masking, would occur in fish that serve as marine mammal prey (Popper et al., 2019);
however, those impacts would be limited to the duration of impact pile driving and
during any UXO/MEC detonations and, if prey were to move out the area in response to
noise, these impacts would be minimized.
In addition to fish, prey sources such as marine invertebrates could potentially be
impacted by noise stressors as a result of the proposed activities. However, most marine
invertebrates' ability to sense sounds is limited. Invertebrates appear to be able to detect

sounds (Pumphrey, 1950; Frings and Frings, 1967) and are most sensitive to lowfrequency sounds (Packard et al., 1990; Budelmann and Williamson, 1994; Lovell et al.,
2005; Mooney et al., 2010). Data on response of invertebrates such as squid, another
marine mammal prey species, to anthropogenic sound is more limited (de Soto, 2016;
Sole et al., 2017). Data suggest that cephalopods are capable of sensing the particle
motion of sounds and detect low frequencies up to 1-1.5 kHz, depending on the species,
and so are likely to detect airgun noise (Kaifu et al., 2008; Hu et al., 2009; Mooney et al.,
2010; Samson et al., 2014). Sole et al. (2017) reported physiological injuries to cuttlefish
in cages placed at-sea when exposed during a controlled exposure experiment to lowfrequency sources (315 Hz, 139 to 142 dB re 1 μPa2 and 400 Hz, 139 to 141 dB re 1
μPa2). Fewtrell and McCauley (2012) reported squids maintained in cages displayed
startle responses and behavioral changes when exposed to seismic airgun sonar (136-162
re 1 μPa2·s). Jones et al. (2020) found that when squid (Doryteuthis pealeii) were
exposed to impulse pile driving noise, body pattern changes, inking, jetting, and startle
responses were observed and nearly all squid exhibited at least one response. However,
these responses occurred primarily during the first eight impulses and diminished
quickly, indicating potential rapid, short-term habituation.
Cephalopods have a specialized sensory organ inside the head called a statocyst
that may help an animal determine its position in space (orientation) and maintain
balance (Budelmann, 1992). Packard et al. (1990) showed that cephalopods were
sensitive to particle motion, not sound pressure, and Mooney et al. (2010) demonstrated
that squid statocysts act as an accelerometer through which particle motion of the sound
field can be detected (Budelmann, 1992). Auditory injuries (lesions occurring on the
statocyst sensory hair cells) have been reported upon controlled exposure to lowfrequency sounds, suggesting that cephalopods are particularly sensitive to low-frequency
sound (Andre et al., 2011; Sole et al., 2013). Behavioral responses, such as inking and

jetting, have also been reported upon exposure to low-frequency sound (McCauley et al.,
2000; Samson et al., 2014). Squids, like most fish species, are likely more sensitive to
low frequency sounds and may not perceive mid- and high-frequency sonars.
With regard to potential impacts on zooplankton, McCauley et al. (2017) found
that exposure to airgun noise resulted in significant depletion for more than half the taxa
present and that there were two to three times more dead zooplankton after airgun
exposure compared with controls for all taxa, within 1 km (0.6 mi) of the airguns.
However, the authors also stated that in order to have significant impacts on r-selected
species (i.e., those with high growth rates and that produce many offspring) such as
plankton, the spatial or temporal scale of impact must be large in comparison with the
ecosystem concerned, and it is possible that the findings reflect avoidance by
zooplankton rather than mortality (McCauley et al., 2017). In addition, the results of this
study are inconsistent with a large body of research that generally finds limited spatial
and temporal impacts to zooplankton as a result of exposure to airgun noise (e.g., Dalen
and Knutsen, 1987; Payne, 2004; Stanley et al., 2011). Most prior research on this topic,
which has focused on relatively small spatial scales, has showed minimal effects (e.g.,
Kostyuchenko, 1973; Booman et al., 1996; Sætre and Ona, 1996; Pearson et al., 1994;
Bolle et al., 2012).
A modeling exercise was conducted as a follow-up to the McCauley et al. (2017)
study (as recommended by McCauley et al.), in order to assess the potential for impacts
on ocean ecosystem dynamics and zooplankton population dynamics (Richardson et al.,
2017). Richardson et al. (2017) found that a full-scale airgun survey would impact
copepod abundance within the survey area, but that effects at a regional scale were
minimal (2 percent decline in abundance within 150 km of the survey area and effects not
discernible over the full region). The authors also found that recovery within the survey
area would be relatively quick (3 days following survey completion), and suggest that the

quick recovery was due to the fast growth rates of zooplankton, and the dispersal and
mixing of zooplankton from both inside and outside of the impacted region. The authors
also suggest that surveys in areas with more dynamic ocean circulation in comparison
with the study region and/or with deeper waters (i.e., typical offshore wind locations)
would have less net impact on zooplankton.
Notably, a more recent study produced results inconsistent with those of
McCauley et al. (2017). Researchers conducted a field and laboratory study to assess if
exposure to airgun noise affects mortality, predator escape response, or gene expression
of the copepod Calanus finmarchicus (Fields et al., 2019). Immediate mortality of
copepods was significantly higher, relative to controls, at distances of 5 m (16.4 ft) or less
from the airguns. Mortality one week after the airgun blast was significantly higher in the
copepods placed 10 m (32.8 ft) from the airgun but was not significantly different from
the controls at a distance of 20 m (65.6 ft) from the airgun. The increase in mortality,
relative to controls, did not exceed 30 percent at any distance from the airgun. Moreover,
the authors caution that even this higher mortality in the immediate vicinity of the airguns
may be more pronounced than what would be observed in free-swimming animals due to
increased flow speed of fluid inside bags containing the experimental animals. There
were no sublethal effects on the escape performance or the sensory threshold needed to
initiate an escape response at any of the distances from the airgun that were tested.
Whereas McCauley et al. (2017) reported an SEL of 156 dB at a range of 509-658 m
(1,670-2,159 ft), with zooplankton mortality observed at that range, Fields et al. (2019)
reported an SEL of 186 dB at a range of 25 m (82 ft), with no reported mortality at that
distance.
The presence and operation of wind turbines (both the foundation and WTG) has
been shown to impact meso- and sub-meso-scale water column circulation, which can
affect the density, distribution, and energy content of zooplankton and thereby, their

availability as marine mammal prey. Topside, atmospheric wakes result in wind speed
reductions influencing upwelling and downwelling in the ocean, while underwater
structures such as WTG and OSP foundations cause turbulent current wakes, which
impact circulation, stratification, mixing, turbidity, and sediment resuspension (Daewel et
al., 2022). Impacts from the presence of structures and/or operation of wind turbine
generators are generally likely to result in certain oceanographic effects, such as
perturbation of zooplankton aggregation mechanisms through changes to the strength of
tidal currents and associated fronts, stratification, the degree of mixing, and primary
production in the water column, and these effects may alter the production, distribution,
and/or availability of marine mammal zooplankton prey (Chen et al., 2021; Chen et al.,
2024,, Johnson et al., 2021, Christiansen et al., 2022, Dorrell et al., 2022).
Assessing the ecosystem impacts of offshore wind development has a unique set
of challenges, including minimizing uncertainties in the fundamental understanding of
how existing physical and biological oceanography might be altered by the presence of a
single offshore wind turbine, by an offshore wind farm, or by a region of adjacent
offshore wind farms. Physical models can demonstrate, among many things, the extent to
which and how a single or large number of operating offshore wind turbine(s) can alter
atmospheric and hydrodynamic flow through interruptions of local winds that drive
circulation processes and by creating turbulence in the water column surrounding the
pile(s). For example, Chen et al., 2024 found that regardless of variations in wind
intensity and direction, the downwind wake caused by WTGs, as modeled from a wind
farm simulation in a lease area located to the west of the SouthCoast lease area, could
consistently produce and enhance offshore water transport of zooplankton (in this case
scallop larvae), particularly around the 40 to 50-m isobaths.
However, many physical and biological processes are influenced by cross-scale
phenomena (e.g., aggregation of dense zooplankton patches), necessitating construction

of more complex models that tolerate varying degrees of uncertainty. Thus, determining
the impacts of offshore wind operations on not only physical processes but trophic
connections from phytoplankton to marine mammals and ultimately the ecosystem will
require significant data collection, monitoring, modeling, and research effort. Given the
limited state of understanding of the entire system in southern New England and the
changing oceanography and ecology, identification of substantial impacts on
zooplankton, and specifically on right whale prey, that may result from wind energy
development in the Nantucket Shoals region is difficult to assess ((National Academy of
Sciences (NAS), 2023.
SouthCoast intends to install up to 147 WTGs, up to 85 of which would be
operational following completion of Project 1 and the remainder operational following
installation of Project 2. SouthCoast may commission turbines in batches (i.e., not all
foundations and WTGs need to be installed per Project before becoming operational).
Based on SouthCoast’s current schedule (Table 1), commissioning could begin in early
2029, assuming foundations were installed the previous year, thus, it is possible that any
influence of operating turbines on local physical and/or biological processes may be
observable at that time, depending on latency of effects. Given the proposed sequencing,
NMFS anticipates the turbines closest to Nantucket Shoals would be commissioned first.
As described above, there is scientific uncertainty around the scale of oceanographic
impacts (meters to kilometers) associated with the presence of foundation structures (e.g.,
monopile, piled jacket) in the water, as well as operation of the WTGs. Generally
speaking and depending on the extent, impacts on prey could influence the distribution of
marine mammals in within and among foraging habitats, potentially necessitating
additional energy expenditure to find and capture prey, which could lead to fitness
consequences. Although studies assessing the impacts of offshore wind development on
marine mammals are limited and the results vary, the repopulation of some wind energy

areas by harbor porpoises (Brandt et al., 2016; Lindeboom et al., 2011) and harbor seals
(Lindeboom et al., 2011; Russell et al., 2016) following the installation of wind turbines
indicates that, in some cases, there is evidence that suitable habitat, including prey
resources, exists within developed waters.
Reef Effects
The presence of WTG and OSP foundations, scour protection, and cable
protection will result in a conversion of the existing sandy bottom habitat to a hard
bottom habitat with areas of vertical structural relief. This could potentially alter the
existing habitat by creating an “artificial reef effect” that results in colonization by
assemblages of both sessile and mobile animals within the new hard-bottom habitat
(Wilhelmsson et al., 2006; Reubens et al., 2013; Bergström et al., 2014; Coates et al.,
2014). This colonization by marine species, especially hard-substrate preferring species,
can result in changes to the diversity, composition, and/or biomass of the area thereby
impacting the trophic composition of the site (Wilhelmsson et al., 2010, Krone et al.,
2013; Bergström et al., 2014; Hooper et al., 2017; Raoux et al., 2017; Harrison and
Rousseau, 2020; Taormina et al., 2020; Buyse et al., 2022a; ter Hofstede et al., 2022).
Artificial structures can create increased habitat heterogeneity important for
species diversity and density (Langhamer, 2012). The WTG and OSP foundations will
extend through the water column, which may serve to increase settlement of
meroplankton or planktonic larvae on the structures in both the pelagic and benthic zones
(Boehlert and Gill, 2010). Fish and invertebrate species are also likely to aggregate
around the foundations and scour protection which could provide increased prey
availability and structural habitat (Boehlert and Gill, 2010; Bonar et al., 2015). Further,
instances of species previously unknown, rare, or nonindigenous to an area have been
documented at artificial structures, changing the composition of the food web and
possibly the attractability of the area to new or existing predators (Adams et al., 2014; de

Mesel, 2015; Bishop et al., 2017; Hooper et al., 2017; Raoux et al., 2017; van Hal et al.,
2017; Degraer et al., 2020; Fernandez-Betelu et al., 2022). Notably, there are examples
of these sites becoming dominated by marine mammal prey species, such as filter-feeding
species and suspension-feeding crustaceans (Andersson and Öhman, 2010; Slavik et al.,
2019; Hutchison et al., 2020; Pezy et al., 2020; Mavraki et al., 2022).
Numerous studies have documented significantly higher fish concentrations
including species like cod and pouting (Trisopterus luscus), flounder (Platichthys flesus),
eelpout (Zoarces viviparus), and eel (Anguilla anguilla) near in-water structures than in
surrounding soft bottom habitat (Langhamer and Wilhelmsson, 2009; Bergström et al.,
2013; Reubens et al., 2013). In the German Bight portion of the North Sea, fish were
most densely congregated near the anchorages of jacket foundations, and the structures
extending through the water column were thought to make it more likely that juvenile or
larval fish encounter and settle on them (Rhode Island Coastal Resources Management
Council (RI-CRMC), 2010; Krone et al., 2013). In addition, fish can take advantage of
the shelter provided by these structures while also being exposed to stronger currents
created by the structures, which generate increased feeding opportunities and decreased
potential for predation (Wilhelmsson et al., 2006). The presence of the foundations and
resulting fish aggregations around the foundations is expected to be a long-term habitat
impact, but the increase in prey availability could potentially be beneficial for some
marine mammals.
The most likely impact to marine mammal habitat from the Project is expected to
be from pile driving, which may affect marine mammal food sources such as forage fish
and zooplankton.
Water Quality
Temporary and localized reduction in water quality will occur as a result of inwater construction activities. Most of this effect will occur during pile driving and

installation of the cables, including auxiliary work such as dredging and scour placement.
These activities will disturb bottom sediments and may cause a temporary increase in
suspended sediment in the Lease Area and ECCs. Indirect effects of explosives and
unexploded ordnance to marine mammals via sediment disturbance is possible in the
immediate vicinity of the ordnance but through the implementation of the mitigation, is it
not anticipated marine mammals would be in the direct area of the explosive source.
Currents should quickly dissipate any raised total suspended sediment (TSS) levels, and
levels should return to background levels once the Project activities in that area cease.
No direct impacts on marine mammals are anticipated due to increased TSS and
turbidity; however, turbidity within the water column has the potential to reduce the level
of oxygen in the water and irritate the gills of prey fish species in the Lease Area and
ECCs.
Further, contamination of water is not anticipated. Degradation products of Royal
Demolition Explosive are not toxic to marine organisms at realistic exposure levels
(Rosen and Lotufo, 2010). Relatively low solubility of most explosives and their
degradation products means that concentrations of these contaminants in the marine
environment are relatively low and readily diluted. Furthermore, while explosives and
their degradation products were detectable in marine sediment approximately 6-12 in
(0.15-0.3 m) away from degrading ordnance, the concentrations of these compounds were
not statistically distinguishable from background beyond 3-6 ft (1-2 m) from the
degrading ordnance.
Turbidity plumes associated with the Project would be temporary and localized,
and fish in the proposed project area would be able to move away from and avoid the
areas where plumes may occur. Therefore, it is expected that the impacts on prey fish
species from turbidity, and therefore on marine mammals, would be minimal and
temporary.

Equipment used by SouthCoast for the project, including ships and other marine
vessels, aircrafts, and other implements, are also potential sources of by-products (e.g.,
hydrocarbons, particulate matter, heavy metals). SouthCoast would be required to
properly maintain all equipment in accordance with applicable legal requirements such
that operating equipment meets Federal water quality standards, where applicable. Given
these requirements, impacts to water quality are expected to be minimal.
Acoustic Habitat
Acoustic habitat is the holistic soundscape, encompassing all of the biotic and
abiotic sound in a particular location and time, as perceived by an individual. Animals
produce sound for and listen for sounds produced by conspecifics (communication during
feeding, mating, and other social activities), other animals (finding prey or avoiding
predators), and the physical environment (finding suitable habitats, navigating). Together,
sounds made by animals and the geophysical environment (e.g., produced by
earthquakes, lightning, wind, rain, waves) comprise the natural contributions to the total
soundscape. These acoustic conditions, termed acoustic habitat, are one attribute of an
animal's total habitat.
Anthropogenic sound is another facet of the soundscape that influences the
overall acoustic habitat. This may include incidental contributions from sources such as
vessels or sounds intentionally introduced to the marine environment for data acquisition
purposes (e.g., use of high-resolution geophysical surveys), detonations for munitions
disposal or coastal constructions, sonar for Navy training and testing purposes, or pile
driving/hammering for construction.projects. Anthropogenic noise varies widely in its
frequency, content, duration, and loudness, and these characteristics greatly influence the
potential habitat-mediated effects to marine mammals (please also see the previous
discussion on Masking), which may range from local effects for brief periods of time to
chronic effects over large areas and for long durations. Depending on the extent of effects

to their acoustic habitat, animals may alter their communications signals (thereby
potentially expending additional energy) or miss acoustic cues (either conspecific or
adventitious). Problems arising from a failure to detect cues are more likely to occur
when noise stimuli are chronic and overlap with biologically relevant cues used for
communication, orientation, and predator/prey detection (Francis and Barber, 2013). For
more detail on these concepts see, e.g., Barber et al., 2009; Pijanowski et al., 2011;
Francis and Barber, 2013; Lillis et al., 2014.
Communication space describes the area over which an animal’s acoustic signal
travels and is audible to the intended receiver (Brenowitz, 1982; Janik, 2000; Clark et al.,
2009; Havlick et al., 2022). The extent of this area depends on the temporal and spectral
structure of the signal, the characteristics of the environment, and the receiver's ability to
detect (the detection threshold) and discriminate the signal from background noise (Wiley
and Richards, 1978; Clark et al., 2009; Havlick et al., 2022). Large communication
spaces are created by acoustic signals that propagate over long distances relative to the
distribution of conspecifics, as exemplified by low-frequency baleen whale vocalizations
(McGregor and Krebs, 1984; Morton, 1986; Janik, 2000). Conversely, both natural and
anthropogenic noise may reduce communication space by increasing background noise,
leading to a generalized contraction of the range over which animals would be able to
detect signals of biological importance, including eavesdropping on predators and prey
(Barber et al., 2009). Any reduction in the communication space, due to increased
background noise resulting in masking, may therefore have detrimental effects on the
ability of animals to obtain important social and environmental information. Such metrics
do not, in and of themselves, document fitness consequences for the marine animals that
live in chronically noisy environments. Long-term population-level consequences of
acoustic signal interference mediated through changes in the ultimate survival and
reproductive success of individuals are difficult to study, and particularly in the marine

environment. However, it is increasingly well documented that aquatic species rely on
qualities of natural acoustic habitats. For example, researchers have quantified reduced
detection of important ecological cues (e.g., Francis and Barber, 2013; Slabbekoorn et al.,
2010) as well as survivorship consequences in several species (e.g., damselfish; Simpson
et al., 2016; larval Atlantic cod, Nedelec et al., 2015a; embryonic sea hare, Nedelec et
al., 2015a) following noise exposure.
Although this proposed rulemaking primarily covers the noise produced from
construction activities relevant to the SouthCoast offshore wind facility, operational noise
was a consideration in NMFS’ analysis of the project, as some, and potentially all,
turbines would become operational within the effective period of the rule (if issued).
Once operational, offshore wind turbines are known to produce continuous, nonimpulsive underwater noise, primarily below 1 kHz (Tougaard et al., 2020; Stöber and
Thomsen, 2021).
In both newer, quieter, direct-drive systems and older generation, geared turbine
designs, recent scientific studies indicate that operational noise from turbines is on the
order of 110 to 125 dB re 1 μPa root-mean-square sound pressure level (SPLrms) at an
approximate distance of 50 m (164 ft) (Tougaard et al., 2020). Recent measurements of
operational sound generated from wind turbines (direct drive, 6 MW, jacket foundations)
at Block Island wind farm (BIWF) indicate average broadband levels of 119 dB at 50 m
(164 ft) from the turbine, with levels varying with wind speed (HDR, Inc., 2019).
Interestingly, measurements from BIWF turbines showed operational sound had less
tonal components compared to European measurements of turbines with gear boxes.
Tougaard et al. (2020) further stated that the operational noise produced by
WTGs is static in nature and lower than noise produced by passing ships. This is a noise
source in this region to which marine mammals are likely already habituated.
Furthermore, operational noise levels are likely lower than those ambient levels already

present in active shipping lanes, such that operational noise would likely only be detected
in very close proximity to the WTG (Thomsen et al., 2006; Tougaard et al., 2020).
Similarly, recent measurements from a wind farm (3 MW turbines) in China found at
above 300 Hz, turbines produced sound that was similar to background levels (Zhang et
al., 2021). Other studies by Jansen and de Jong (2016) and Tougaard et al. (2009)
determined that, while marine mammals would be able to detect operational noise from
offshore wind farms (again, based on older 2 MW models) for several kilometers, they
expected no significant impacts on individual survival, population viability, marine
mammal distribution, or the behavior of the animals considered in their study (harbor
porpoises and harbor seals). In addition, Madsen et al. (2006) found the intensity of noise
generated by operational wind turbines to be much less than the noises present during
construction, although this observation was based on a single turbine with a maximum
power of 2 MW.
More recently, Stöber and Thomsen (2021) used monitoring data and modeling to
estimate noise generated by more recently developed, larger (10 MW) direct-drive
WTGs. Their findings, similar to Tougaard et al. (2020), demonstrate that there is a trend
that operational noise increases with turbine size. Their study predicts broadband source
levels could exceed 170 dB SPLrms for a 10 MW WTG; however, those noise levels were
generated based on geared turbines; newer turbines operate with direct drive technology.
The shift from using gear boxes to direct drive technology is expected to reduce the
levels by 10 dB. The findings in the Stöber and Thomsen (2021) study have not been
experimentally validated, though the modeling (using largely geared turbines parameters)
performed by Tougaard et al. (2020) yields similar results for a hypothetical 10 MW
WTG.
Recently, Holme et al. (2023) cautioned that Tougaard et al. (2020) and Stöber
and Thomsen (2021) extrapolated levels for larger turbines should be interpreted with

caution since both studies relied on data from smaller turbines (0.45 to 6.15 MW)
collected over a variety of environmental conditions. They demonstrated that the model
presented in Tougaard et al. (2020) tends to potentially overestimate levels (up to
approximately 8 dB) measured to those in the field, especially with measurements closer
to the turbine for larger turbines. Holme et al. (2023) measured operational noise from
larger turbines (6.3 and 8.3 MW) associated with three wind farms in Europe and found
no relationship between turbine activity (power production, which is proportional to the
blade’s revolutions per minute) and noise level, though it was noted that this missing
relationship may have been masked by the area’s relatively high ambient noise sound
levels. Sound levels (RMS) of a 6.3 MW direct-drive turbine were measured to be 117.3
dB at a distance of 70 m (229.7 ft). However, measurements from 8.3 MW turbines were
inconclusive as turbine noise was deemed to have been largely masked by ambient noise.
Finally, operational turbine measurements are available from the Coastal Virginia
Offshore Wind (CVOW) pilot pile project, where two 7.8 m-monopile WTGs were
installed (HDR, 2023). Compared to BIWF, levels at CVOW were higher (10-30 dB)
below 120 Hz, believed to be caused by the vibrations associated with the monopile
structure, while above 120 Hz levels were consistent among the two wind farms.
Overall, noise from operating turbines would raise ambient noise levels in the
immediate vicinity of the turbines; however, the spatial extent of increased noise levels
would be limited. NMFS proposes to require SouthCoast to measure operational noise
levels.
Estimated Take
This section provides an estimate of the number of incidental takes that may be
authorized through the proposed regulations, which will inform both NMFS’
consideration of “small numbers” and the negligible impact determination. Harassment is
the only type of take expected to result from these activities.

Authorized takes would be primarily by Level B harassment, as use of the
acoustic sources (i.e., impact and vibratory pile driving, site characterization surveys, and
UXO/MEC detonations) has the potential to result in disruption of marine mammal
behavioral patterns due to exposure to elevated noise levels. Impacts such as masking and
TTS can contribute to behavioral disturbances. There is also some potential for auditory
injury (Level A harassment) to occur in select marine mammal species incidental to the
specified activities (i.e., impact pile driving and UXO/MEC detonations). The required
mitigation and monitoring measures, the majority of which are not considered in the
estimated take analysis, are expected to reduce the extent of the taking to the lowest level
practicable.
While, in general, mortality and serious injury of marine mammals could occur
from vessel strikes or UXO/MEC detonation if an animal is close enough to the source,
the mitigation and monitoring measures in this proposed rule, when implemented, are
expected to minimize the potential for take by mortality or serious injury such that the
probability for take is discountable. No other activities have the potential to result in
mortality or serious injury, and no serious injury is anticipated or proposed for
authorization through this rulemaking.
Generally speaking, we estimate take by considering: (1) thresholds above which
the best scientific information available indicates marine mammals will be behaviorally
harassed or incur some degree of permanent hearing impairment or non-auditory injury;
(2) the area or volume of water that will be ensonified above these levels in a day; (3) the
density or occurrence of marine mammals within these ensonified areas; and, (4) the
number of days of activities. We note that while these factors can contribute to a basic
calculation to provide an initial prediction of potential takes; additional information that
can qualitatively inform take estimates is also sometimes available (e.g., previous
monitoring results or average group size).

Below, we describe NMFS’ acoustic and non-auditory injury thresholds, acoustic
and exposure modeling methodologies, marine mammal density calculation
methodology, occurrence information, and the modeling and methodologies applied to
estimate incidental take for each specified activity likely to result in take by harassment.
Marine Mammal Acoustic Thresholds
NMFS recommends the use of acoustic thresholds that identify the received level
of underwater sound above which exposed marine mammals are likely to be behaviorally
harassed (equated to Level B harassment) or to incur PTS of some degree (equated to
Level A harassment). Thresholds have also been developed to identify the levels above
which animals may incur different types of tissue damage (non-acoustic Level A
harassment or mortality) from exposure to pressure waves from explosive detonation. A
summary of all NMFS’ thresholds can be found at
(https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammalacoustic-technical-guidance).
Level B harassment
Though significantly driven by received level, the onset of behavioral disturbance
from anthropogenic noise exposure is also informed to varying degrees by other factors
related to the source or exposure context (e.g., frequency, predictability, duty cycle,
duration of the exposure, signal-to-noise ratio, distance to the source, ambient noise, and
the receiving animals (animal’s hearing, motivation, experience, demography, behavior at
time of exposure, life stage, depth)) and can be difficult to predict (e.g., Southall et al.,
2007, 2021; Ellison et al., 2012). Based on the best scientific information available and
the practical need to use a threshold based on a metric that is both predictable and
measurable for most activities, NMFS typically uses a generalized acoustic threshold
based on received level to estimate the onset of behavioral harassment. NMFS generally
predicts that marine mammals are likely to be behaviorally harassed in a manner

considered to be Level B harassment when exposed to underwater anthropogenic noise
above the received sound pressure levels (SPLrms) of 120 dB for continuous sources (e.g.,
vibratory pile-driving, drilling) and above the received SPLrms160 dB for non-explosive
impulsive or intermittent sources (e.g., impact pile driving, scientific sonar). Generally
speaking, Level B harassment take estimates based on these behavioral harassment
thresholds are expected to include any likely takes by TTS as, in most cases, the
likelihood of TTS occurs at distances from the source less than those at which behavioral
harassment is likely. TTS of a sufficient degree can manifest as behavioral harassment, as
reduced hearing sensitivity and the potential reduced opportunities to detect important
signals (conspecific communication, predators, prey) may result in changes in behavior
patterns that would not otherwise occur.
Level A harassment
NMFS’ Technical Guidance for Assessing the Effects of Anthropogenic Sound on
Marine Mammal Hearing (Version 2.0) (NMFS, 2018) identifies dual criteria to assess
auditory injury (Level A harassment) to five different marine mammal groups (based on
hearing sensitivity) as a result of exposure to noise from two different types of sources
(impulsive or non-impulsive). As dual metrics, NMFS considers onset of PTS (Level A
harassment) to have occurred when either one of the two metrics is exceeded (i.e., metric
resulting in the largest isopleth). As described above, SouthCoast’s proposed activities
include the use of both impulsive and non-impulsive sources.
NMFS’ thresholds identifying the onset of PTS are provided in table 7. The
references, analysis, and methodology used in the development of the thresholds are
described in NMFS’ 2018 Technical Guidance, which may be accessed at:
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustictechnical-guidance.

Table 7 – Onset of Permanent Threshold Shift (PTS) (NMFS, 2018)
PTS Onset Thresholds*
(Received Level)

Hearing Group
Impulsive

Non-impulsive

Low-Frequency (LF) Cetaceans

Cell 1
Lp,0-pk,flat: 219 dB
LE,p, LF,24h: 183 dB

Cell 2
LE,p, LF,24h: 199 dB

Mid-Frequency (MF) Cetaceans

Cell 3
Lp,0-pk,flat: 230 dB
LE,p, MF,24h: 185 dB

Cell 4
LE,p, MF,24h: 198 dB

High-Frequency (HF) Cetaceans

Cell 5
Lp,0-pk,flat: 202 dB
LE,p,HF,24h: 155 dB

Cell 6
LE,p, HF,24h: 173 dB

Phocid Pinnipeds (PW)
(Underwater)

Cell 7
Lp,0-pk.flat: 218 dB
LE,p,PW,24h: 185 dB

Cell 8
LE,p,PW,24h: 201 dB

* Dual metric thresholds for impulsive sounds: Use whichever results in the largest isopleth for
calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure
level thresholds associated with impulsive sounds, these thresholds are recommended for consideration.
Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1 µPa, and weighted cumulative sound
exposure level (LE,p) has a reference value of 1µPa2s. In this 6able, thresholds are abbreviated to be
more reflective of International Organization for Standardization standards (ISO, 2017). The subscript
“flat” is being included to indicate peak sound pressure are flat weighted or unweighted within the
generalized hearing range of marine mammals (i.e., 7 Hz to 160 kHz). The subscript associated with
cumulative sound exposure level thresholds indicates the designated marine mammal auditory weighting
function (LF, MF, and HF cetaceans, and PW pinnipeds) and that the recommended accumulation period
is 24 hours. The weighted cumulative sound exposure level thresholds could be exceeded in a multitude
of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it is valuable for action
proponents to indicate the conditions under which these thresholds will be exceeded.

Explosive source
Based on the best scientific information available, NMFS uses the acoustic and
pressure thresholds indicated in tables 8 and 9 to predict the onset of behavioral
harassment, TTS, PTS, non-auditory injury, and mortality incidental to explosive
detonations. Given SouthCoast would be limited to detonating one UXO/MEC per day,
the TTS threshold is used to estimate the potential for Level B (behavioral) harassment
(i.e., individuals exposed above the TTS threshold may also be harassed by behavioral
disruption, but we do not anticipate any impacts from exposure to UXO/MEC detonation
below the TTS threshold would constitute behavioral harassment).

Table 8 – PTS Onset, TTS Onset, for Underwater Explosives (NMFS, 2018)
Hearing Group

PTS Impulsive Thresholds

Impulsive Thresholds for TTS and
behavioral disturbance from a
single detonation

Low-Frequency (LF) Cetaceans

Cell 1
Lpk,flat: 219 dB
LE,LF,24h: 183 dB

Cell 2
Lpk,flat: 213 dB
LE,LF,24h: 168 dB

Mid-Frequency (MF) Cetaceans

Cell 4
Lpk,flat: 230 dB
LE,MF,24h: 185 dB

Cell 5
Lpk,flat: 224 dB
LE,MF,24h: 170 dB

High-Frequency (HF) Cetaceans

Cell 7
Lpk,flat: 202 dB
LE,HF,24h: 155 dB

Cell 8
Lpk,flat: 196 dB
LE,HF,24h: 140 dB

Phocid Pinnipeds (PW)
(Underwater)

Cell 10
Lpk,flat: 218 dB
LE,PW,24h: 185 dB

Cell 11
Lpk,flat: 212 dB
LE,PW,24h: 170 dB

* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
calculating PTS/TTS onset.
Note: Peak sound pressure (Lpk) has a reference value of 1 µPa, and cumulative sound exposure level (LE) has
a reference value of 1µPa2s. In this table, thresholds are abbreviated to reflect American National Standards
Institute standards (ANSI, 2013). However, ANSI defines peak sound pressure as incorporating frequency
weighting, which is not the intent for this Technical Guidance. Hence, the subscript “flat” is being included to
indicate peak sound pressure should be flat weighted or unweighted within the overall marine mammal
generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates
the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW pinnipeds)
and that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds
could be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When
possible, it is valuable for action proponents to indicate the conditions under which these acoustic thresholds
will be exceeded.

Additional thresholds for non-auditory injury to lung and gastrointestinal (GI)
tracts from the blast shock wave and/or onset of high peak pressures are also relevant (at
relatively close ranges) (table 9). These criteria have been developed by the U.S. Navy
(DoN (U.S. Department of the Navy) 2017a) and are based on the mass of the animal and
the depth at which it is present in the water column. Equations predicting the onset of the
associated potential effects are included below (table 9).
Table 9 – Lung and G.I. Tract Injury Thresholds (DoN, 2017)
Mortality
Slight Lung Injury*
G.I. Tract Injury
(Severe lung injury)*
Cell 1
Cell 2
Cell 3
All Marine Mammals
Modified Goertner
Modified Goertner
Lpk,flat: 237 dB
model; Equation 1
model; Equation 2
* Lung injury (severe and slight) thresholds are dependent on animal mass (Recommendation: Table C.9
from DoN (2017) based on adult and/or calf/pup mass by species).
Hearing Group

Note: Peak sound pressure (Lpk) has a reference value of 1 µPa. In this table, thresholds are abbreviated
to reflect American National Standards Institute standards (ANSI, 2013). However, ANSI defines peak

sound pressure as incorporating frequency weighting, which is not the intent for this Technical
Guidance. Hence, the subscript “flat” is being included to indicate peak sound pressure should be flat
weighted or unweighted within the overall marine mammal generalized hearing range.
Modified Goertner Equations for severe and slight lung injury (pascal-second)
Equation 1: 103M1/3(1 + D/10.1)1/6 Pa-s
Equation 2: 47.5M1/3(1 + D/10.1)1/6 Pa-s
M animal (adult and/or calf/pup) mass (kg) (Table C.9 in DoN, 2017)
D animal depth (meters)

Modeling and Take Estimation
SouthCoast estimated density-based exposures in two separate ways, depending
on the activity. To assess the potential for Level A harassment and Level B harassment
resulting from exposure to the underwater sound fields produced during impact and
vibratory pile driving, sophisticated sound and animal movement modeling was
conducted to account for movement and behavior of marine mammals. For HRG surveys
and UXO/MEC detonations, SouthCoast estimated the number of takes by Level B
harassment using a simplified “static” method wherein the take estimates are the product
of density, area of water ensonified above the NMFS defined threshold (e.g., unweighted
160 dB SPLrms) levels, and number of activity days (assuming a maximum of one
UXO/MEC detonation per day). For some species, observational data from PSOs aboard
HRG survey vessels or group size indicated that the density-based take estimates may be
insufficient to account for the number of individuals of a species that may be encountered
during the planned activities; thus, adjustments were made to the density-based estimates.
The assumptions and methodologies used to estimate take, in consideration of
acoustic thresholds and appropriate marine mammal density and occurrence information,
are described in activity-specific subsections below (i.e.,WTG and OSP foundation
installation, HRG surveys, and UXO/MEC detonation). Resulting distances to threshold
isopleths, densities used, activity-specific exposure estimates (as relevant to the analysis),
and take estimates can be found in each activity subsection below. At the end of this

section, we present the total annual and 5-year take estimates that NMFS proposes to
authorize.
Marine Mammal Density and Occurrence
In this section, we provide information about marine mammal presence, density,
or group dynamics that will inform the take calculations for all activities. Depending on
the stock and as described in the take estimation section for each activity, take estimates
may be based on the Roberts et al. (2023) density estimates, marine mammal monitoring
results from HRG surveys, or average group sizes. The density and occurrence
information resulting in the highest take estimate was considered in subsequent analyses,
and the explanation and results for each activity are described in the specific activity subsections.
Habitat-based density models produced by the Duke University Marine
Geospatial Ecology Laboratory and the Marine-life Data and Analysis Team, based on
the best available marine mammal data obtained in a collaboration between Duke
University, the Northeast Regional Planning Body, the University of North Carolina
Wilmington, the Virginia Aquarium and Marine Science Center, and NOAA (Roberts et
al., 2016a, 2016b, 2017, 2018, 2020, 2021a, 2021b, 2023), represent the best available
scientific information regarding marine mammal densities in and surrounding the Lease
Area and along ECCs. Density data are subdivided into five separate raster data layers for
each species, including: Abundance (density), 95 percent Confidence Interval of
Abundance, 5 percent Confidence Interval of Abundance, Standard Error of Abundance,
and Coefficient of Variation of Abundance.
Modifications to the densities used were necessary for some species. The
estimated monthly density of seals provided in Roberts et al. (2016; 2023) includes all
seal species present in the region as a single guild. To split the resulting “seal” density
estimate by species, SouthCoast multiplied the estimate by the proportion of each species

observed by PSOs during SouthCoast’s 2020–2021 site characterization surveys (Milne,
2021; 2022). The proportions used were 231/246 (0.939) for gray seals and 15/246
(0.061) for harbor seals. The “seal” density provided by Roberts et al. (2016; 2023) was
then multiplied by these proportions to get the species specific densities. While the
Roberts et al. (2016; 2023) seals guild includes all phocid seals, as described in the
Descriptions of Marine Mammals in the Specified Geographical Region section, harp
seal occurrence is considered rare and unexpected in SNE. Given this, harp seals were not
included when splitting the seal guild density and SouthCoast did not request take for this
species. Monthly densities were unavailable for pilot whales, so SouthCoast applied the
annual mean density to estimate take. As described in the Marine Mammal section,
species’ distributions indicate that the only species of pilot whale expected to occur in
SNE is the long-finned pilot whale; therefore, the densities provided in Roberts et al.
(2016, 2023) are attributed to this species (and not short-finned pilot whales). Similarly,
distribution data for bottlenose dolphins stocks indicate that the only stock likely to occur
in SNE is the Western North Atlantic offshore stock, thus all Robert et al. (2016, 2023)
densities are attributed to this stock. Below, we describe observational data from
monitoring reports and average group size information, both of which are appropriate to
inform take estimates for certain activities or species in lieu of density estimates.
For some species and activities, observational data from Protected Species
Observers (PSOs) aboard HRG and geotechnical (GT) survey vessels indicate that the
density-based exposure estimates may be insufficient to account for the number of
individuals of a species that may be encountered during the planned activities. PSO data
from geophysical and geotechnical surveys conducted in the area surrounding the Lease
Area and ECCs from April 2020 through December 2021 (RPS, 2021) were analyzed to
determine the average number of individuals of each species observed per vessel day. For
each species, the total number of individuals observed (including the“proportion of

unidentified individuals'') was divided by the number of vessel days during which
observations were conducted in 2020–2021 HRG surveys (555 survey days) to calculate
the number of individuals observed per vessel day, as shown in the final columns of
Table 7 in the SouthCoast ITA application.
For other less-common species, the predicted densities from Roberts et al. (2016;
2023) are very low and the resulting density-based exposure estimate is less than a single
animal or a typical group size for the species. In such cases, the mean group size was
considered as an alternative to the density-based or PSO data-based take estimates to
account for potential impacts on a group during an activity. Mean group sizes for each
species were calculated from recent aerial and/or vessel-based surveys, as shown in table
10. Additional detail regarding the density and occurrence as well as the methodology
used to estimate take for specific activities is included in the activity-specific subsections
below.
Table 10 – Mean Group Sizes of Species That May Occur in the Project Area
Species

Individuals

Sightings

Mean Group Size

Information
Source

North Atlantic
right whale*

60

2.4

Kraus et al. (2016)

Blue whale*

3

1.0

Palka et al. (2017)

Fin whale*

86

1.8

Kraus et al. (2016)

Humpback whale

82

2.0

Kraus et al. (2016)

Minke whale

83

1.2

Kraus et al. (2016)

Sei whale*

25

1.6

Kraus et al. (2016)

Sperm whale*

138

1.5

Palka et al. (2017)

Atlantic spotted
dolphin

1,335

29.0

Palka et al. (2017)

Atlantic whitesided dolphin

8

27.9

Kraus et al. (2016)

Bottlenose dolphin

33

7.8

Kraus et al. (2016)

Common dolphin

2,896

34.9

Kraus et al. (2016)

Pilot whales

14

8.4

Kraus et al. (2016)

Risso’s dolphin

1,215

5.4

Palka et al. (2017)

Harbor porpoise

45

2.7

Kraus et al. (2016)

Seals
(harbor and gray)

144

1.4

Palka et al. (2017)

* Denotes species listed under the Endangered Species Act.

The estimated exposure and take tables for each activity present the density-based
exposure estimates, PSO-date derived take estimate, and mean group size for each
species. The number of species-specific takes by Level B harassment that is proposed for
authorization is based on the largest of these three values. Although animal exposure
modeling resulted in Level A harassment exposure estimates for other species, NMFS is
not proposing to authorize Level A harassment take for any species other than fin whales,
harbor porpoises, and harbor and gray seals. The numbers of takes by Level A
harassment proposed for authorization for these species are based strictly on densitybased exposure modeling results (i.e., not on PSO-data derived estimates or group size).
WTG and OSP Foundation Installation
Here, for WTG and OSP monopile and pin-piled jacket foundation installation,
we provide summary descriptions of the modeling methodology used to predict sound
levels generated from the Project with respect to harassment thresholds and potential
exposures using animal movement, the density and/or occurrence information used to
support the take estimates for this activity, and the resulting acoustic and exposure
ranges, exposures, and authorized takes.
The predominant underwater noise associated with the construction of offshore
components of the SouthCoast Project would result from impact and vibratory pile

driving of the monopile and jacket foundations. SouthCoast employed JASCO Applied
Sciences (USA) Inc. (JASCO) to conduct acoustic modeling to better understand sound
fields produced during these activities (Limpert et al., 2024). The basic modeling
approach is to characterize the sounds produced by the source, and determine how the
sounds propagate within the surrounding water column. For both impact and vibratory
pile driving, JASCO conducted sophisticated source and propagation modeling (as
described below). JASCO also conducted animal movement modeling to estimate the
potential for marine mammal harassment incidental to pile driving. JASCO estimated
species-specific exposure probabilities by considering the range- and depth-dependent
sound fields in relation to animal movement in simulated representative construction
scenarios. More details on these acoustic source modeling, propagation modeling and
exposure modeling methods are described below and can be found in Limpert et al.
(2024).
Pile Driving Acoustic Source Modeling
To model the sound emissions from the piles, the force of the pile driving
hammers had to be modeled first. JASCO used the GRL, Inc. Wave Equation Analysis of
Pile Driving wave equation model (GRLWEAP) (Pile Dynamics, 2010) in conjunction
with JASCO’s Pile Driving Source Model (PDSM), a physical model of pile vibration
and near-field sound radiation (MacGillivray, 2014), to predict source levels associated
with impact and vibratory pile driving activities. Forcing functions, representing the force
of the impact or vibratory hammer at the top of each 9/16-m monopile and 4.5-m jacket
foundation pile, were computed using the GRLWEAP 2010 wave equation model
(GRLWEAP) (Pile Dynamics, 2010), which includes a large database of simulated
impact and vibratory hammers. The GRLWEAP model assumed direct contact between
the representative impact and vibratory hammers, helmets, and piles (i.e., no cushioning
material, which provides a more conservative estimate). For monopile and jacket

foundations, the piles were assumed to be vertical and driven to a penetration depth of 35
m (115 ft) and 60 m (197 ft), respectively. Modeling assumed jacket foundation piles
were either pre- and post-piled. As indicated in the Description of Specified Activities
section, pre-piling means that the jacket structure will be set on pre-installed piles, as
would be the case for SouthCoast’s WTG foundations (if jacket foundations are used for
WTGs). OSP foundations would be post-piled (using only impact pile driving), meaning
that the jacket structure is placed on the seafloor and piles would be subsequently driven
through guides at the base of each leg. These jacket foundations (which are separate from
the pin piles on which they sit) will also radiate sound as the piles are driven. To account
for the additional sound (beyond impact hammering of the OSP pin piles) radiating from
the jacket structure, a 2-dB increase in received levels was included in the propagation
calculations for OSP post-piling installations, based on a recommendation from Bellman
et al. (2020).
Modeling the forcing function for vibratory pile driving required slightly different
considerations than for impact pile driving given differences in the way each hammer
type interacts with a pile, although the models used are the same for installation methods.
Piles deform when driven with impact hammers, creating a bulge that travels down the
pile and radiates sound into the surrounding air, water, and seabed. During the vibratory
pile driving stage, piles are driven into the substrate due to longitudinal vibration motion
at the hammer’s operational frequency and corresponding amplitude, which causes the
soil to liquefy, allowing the pile to penetrate into the seabed. Using GRLWEAP, onesecond long vibratory forcing functions were computed for the 9/16-m monopile and 4.5m jacket foundations, assuming the use of 32 clamps with total weight of 2102.4 kN for
the monopile and 4 clamps with total weight of 213.56 kN for the jacket piles, connecting
the hammer to the piles. Non-linearities were introduced to the vibratory forcing
functions based on the decay rate observed in data measured during vibratory pile driving

of smaller diameter piles (Quijano et al., 2017). Key modeling assumptions can be found
in Table B-1 in Appendix B of Limpert et al. (2024). Please see Figures 12 and 13 in
Section 4.1.1 of Limpert et al. (2024), for impact pile driving forcing functions, and
Figures 18 and 19 in section 4.1.2 for vibratory pile driving forcing functions.
Both the impact and vibratory pile driving forcing functions computed using the
GRLWEAP model were used then as inputs to the PDSM model to compute the resulting
pile vibrations. These models account for several parameters that describe the
operation—pile type, material, size, and length—the pile driving equipment, and
approximate pile penetration depth. The PDSM physical model computes the underwater
vibration and sound radiation of a pile by solving the theoretical equations of motion for
axial and radial vibrations of a cylindrical shell. Piles were modeled assuming vertical
installation using a finite-difference structural model of pile vibration based on thin-shell
theory. The sound radiating from the pile itself was simulated using a vertical array of
discrete point sources. This model is used to estimate the energy distribution per
frequency (source spectrum) at a close distance from the source (10 m (32.8 ft)). Please
see Appendix E in Limpert et al. (2024), for a more detailed description.
The amount of sound generated during pile driving varies with the energy
required to drive piles to a desired depth, and depends on the sediment resistance
encountered. Sediment types with greater resistance require hammers that deliver higher
energy strikes and/or an increased number of strikes relative to installations in softer
sediment. Maximum sound levels usually occur during the last stage of impact pile
driving (i.e., when the pile is approaching full installation depth) where the greatest
resistance is encountered (Betke, 2008). Rather than modeling increasing hammer energy
with increasing penetration depth, SouthCoast assumed that maximum hammer energy
would be used throughout the entire installation of monopiles and pin piles (tables 11 and
12). This is a conservative assumption, given the project area includes a predominantly

sandy bottom habitat, which is a softer sediment (see Specified Geographical Area
section) that would require less than the maximum hammer energy to penetrate.
Representative hammering schedules for impact installation are shown in table 11
and for installations requiring vibratory followed by impact installation in table 12. For
impact installation of 9/16-m WTG monopiles, 7,000 total hammer strikes were assumed,
using the maximum hammer energy (6,600 kJ). The smaller 4.5-m pin piles for the WTG
and OSP jacket foundations were assumed to require 4,000 total strikes using the
maximum hammer energy (3,500 kJ). Modeling vibratory and subsequent impact
installation of 9/16-m monopiles assumed 20 minutes of vibratory piling followed by
5,000 strikes of impact hammering. Installation of 4.5-m WTG piles using both vibratory
and impact hammering methods assumed 90 minutes of vibratory pile driving followed
by 2,667 impact hammer strikes.
Table 11 – Hammer Energy Schedules For Monopile and Jacket Foundations
Installed With Impact Hammer Only
WTG Monopile Foundations (9/16-m diameter)

WTG and OSP Jacket Foundations (4.5-m
diameter)

Hammer: NNN 6600

Hammer: MHU 3500S

Energy Level
(kilojoule,
kJ)1

Strike Count

Pile
Penetration
Depth (m)

Energy Level
(kilojoule, kJ)

Strike Count

Pile
Penetration
Depth

6,600a

2,000

0-10

3,500a

1,333

0-20

6,600b

2,000

11-21

3,500b

1,333

21-41

6,600c

3,000

22-35

3,500c

1,334

41-60

Total:

7,000

Total:

4,000

a, b, c – Modeling assumed application of the maximum hammer energy throughout the entire monopile
installation. For ease of reference, JASCO used this notation to differentiate progressive stages of
installation at the same hammer energy but at different penetration depths and number of hammer strikes.

Table 12 – Hammer Energy Schedules For Monopile and Jacket Foundations
Installed With Both Vibratory and Impact Hammers
WTG Monopile foundations (9/16-m diameter)

WTG Jacket Foundations (4.5-m diameter)
Hammers

Hammers

Vibratory SCV640
Vibratory HXCV640

Hamme
r type

Energy
Level
(kilojou
le, kJ)

Vibrato
ry

3,500

Impact

6,600

Total:

–

Impact MHU 3500S

Impact NNN6600

Strike
Count

Duratio
n
(minute
s)

Pile
Penetrat
ion
Depth
(m)

–

0-10

2,000

–

11-21

3,000

–

22-35

5,000

35

Hamme
r type

Energy
Level
(kilojou
le, kJ)

Vibrato
ry

3,500

Impact

6,000

–

Strike
Count

Duratio
n
(minute
s)

Pile
Penetrat
ion
Depth
(m)

–

0-20

1,333

–

21-41

1,334

–

42-60

2,667

60

–

a, b, c – Modeling assumed application of the maximum hammer energy throughout the entire monopile
installation. For ease of reference, JASCO used this notation to differentiate progressive stages of
installation at the same hammer energy but at different penetration depths and number of hammer strikes.

Table 13 – Broadband SEL (dB re 1 μPa2·s) per Modeled Energy Level at 10 m
From a 9/16-m Monopile and 4.5-m Pin Pile Installed Using a Impact Hammer at
Two Representative Locations in the Lease Areaa
Pile Type

9/16-m Monopile

4.5-m Pin Pile

Impact
Hammer

NNN6600

MHU 3500S

SEL

Energy Level
(kilojoule, kJ)a

L011

L021

6,600a

207.5

208.1

6,600b

206.2

206.9

6,600c

206.9

207.1

3,500

197.4

198.1

3,500

198.5

198.7

3,500

195.7

190.5

1 – L01 and L02 are located in the southwest and northeast sections of the Lease Area, respectively. See
Figure 2 in Limpert et al. (2023) for a map of these locations.
a, b, c – Modeling assumed application of the maximum hammer energy throughout the entire monopile
installation. For ease of reference, JASCO used this notation to differentiate progressive stages of
installation at the same hammer energy but at different penetration depths and number of hammer strikes.

Table 14 – Broadband SEL (dB re 1 μPa2·s) Per Duration of Vibratory Piling at 10
m From a 9/16-m Monopile and 4.5-m Pin Pile Installed Using Impact Hammering
at Two Representative Locations in the Lease Areaa
Pile Type

Vibraotry
Hammer

Vibratory Pile
Driving
Duration (min)

SEL (dB re 1 μPa2·s
L01

L02

9/16-m Monopile

TA-CV320

214.8

213.5

4.5-m Pin Pile

HX-CV640

193.3

190.3

a – L01 and L02 are located in the southwest and northeast sections of the Lease Area, respectively. See
Figure 2 in Limpert et al. (2023) for a map of these locations.

a, b, c – Modeling assumed application of the maximum hammer energy throughout the entire monopile
installation. For ease of reference, JASCO used this notation to differentiate progressive stages of
installation at the same hammer energy but at different penetration depths and number of hammer strikes.

Beyond understanding pile driving source levels (estimated using forcing
functions), there are additional factors to consider when determining the degree to which
noise would be transmitted through the water column. Noise abatement systems (NAS)
are often used to decrease the sound levels in the water near a source by inserting a local
impedance change that acts as a barrier to sound transmission. Attenuation by impedance
change can be achieved through a variety of technologies, including bubble curtains,
evacuated sleeve systems (e.g., IHC-Noise Mitigation System (NMS)), encapsulated
bubble systems (e.g., HydroSound Dampers (HSD)), or Helmholtz resonators (AdBm
NMS). The effectiveness of each system is frequency dependent and may be influenced
by local environmental conditions such as current and depth. SouthCoast would employ
systems to attenuate noise during all pile driving of monopile and jacket foundations,
including, at minimum, a double big bubble curtain (DBBC). Several recent studies
summarizing the effectiveness of NAS have shown that broadband sound levels are likely
to be reduced by anywhere from 7 to 17 dB, depending on the environment, pile size, and
the size, configuration and number of systems used (Buehler et al., 2015; Bellmann et al.,
2020). Hence, hypothetical broadband attenuation levels of 0 dB, 6 dB, 10 dB, 15 dB,
and 20 dB were incorporated into acoustic modeling to gauge effects on the ranges to
thresholds given these levels of attenuation. Although five attenuation levels were
evaluated, SouthCoast and NMFS anticipate that the noise attenuation system ultimately
chosen will be capable of reliably reducing source levels by 10 dB; therefore, modeling
results assuming 10-dB attenuation are carried forward in this analysis for pile driving.
See the Proposed Mitigation section for more information regarding the justification for
the 10-dB attenuation assumption.

Acoustic Propagation Modeling
To estimate sound propagation during foundation installation, JASCO’s used the
Full Waveform Range-dependent Acoustic Model (FWRAM) to combine the outputs of
the source model with spatial and temporal environmental factors (e.g., location,
oceanographic conditions, and seabed type) to get time-domain representations of the
sound signals in the environment and estimate sound field levels ((Limpert et al. (2024),
Section F.1 in Appendix F of SouthCoast’s ITA application)). Because the foundation
pile is represented as a linear array and FWRAM employs the array starter method to
accurately model sound propagation from a spatially distributed source (MacGillivray
and Chapman, 2012), using FWRAM ensures accurate characterization of vertical
directivity effects in the near-field zone. Due to seasonal changes in the temperature and
salinity of the water column, sound propagation is likely to vary among different times of
the year. To capture this variability, acoustic modeling was conducted using an average
sound speed profile for a “summer” period including the months of May through
November, and a “winter” period including December through April. FWRAM computes
pressure waveforms via Fourier synthesis of the modeled acoustic transfer function in
closely spaced frequency bands. This model is used to estimate the energy distribution
per frequency (source spectrum) at a close distance from the source (10 m (32.8 ft)).
Examples of decidecade spectral levels for each foundation pile type, hammer energy,
and modeled location, using average summer sound speed profile are provided in Limpert
et al. (2024).
Sounds produced by sequential installation of the 9/16-m WTG monopiles and
4.5-m pin piles were modeled at two locations. Water depths within the Lease Area range
from 37 m to 64 m (121 ft to 210 ft). Sound fields produced during both impact and
vibratory installation of 9/16-m WTG monopiles and 4.5-m WTG and OSP pin piles were
modeled at two locations: L01 in the southwest section of the lease area in 38 m water

depth and L02 in the northeast section of the lease area in 53 m (173.9 ft) depth (Figure 2
in Appendix A in Limpert et al., 2024). Propagation modeling did not include water
depths between 54 m and 64 m (deepest location) given the majority of foundation
locations (i.e., 101 out of 149) occur in depths less than 54 m (177 ft). The locations were
selected to represent the acoustic propagation environment within the Lease Area and
may not be actual foundation locations. JASCO selected alternative locations to model
the ensonified zones produced during concurrent pile driving because the foundation
installation locations would be closer together (i.e., separated by approximately 2 nm)
than those selected for sequential foundation installations.
For impulsive sounds from impact pile driving as well as non-impulsive sounds
from vibratory piling, time-domain representations of the pressure waves generated in the
water are required for calculating SPLrms and SPLpeak at various distances from the pile,
metrics that are important for characterizing potential impacts of pile driving noise on
marine mammals. Furthermore, the pile must be represented as a distributed source to
accurately characterize vertical directivity effects in the near-field zone. JASCO used
FWRAM to compute synthetic pressure waveforms as a function of range and depth via
Fourier synthesis of transfer functions in closely spaced frequency bands, in rangevarying marine acoustic environments. Additional modeling details are described in
Limpert et al. (2024). Impact and vibratory pile driving source and propagation modeling
provides estimates of the distances from the pile location to NMFS’ Level A harassment
and Level B harassment threshold isopleths.
JASCO calculated acoustic ranges, which represent the distance to a harassment
threshold based on sound propagation through the environment, independent of
movement of a receiver. The use of acoustic ranges (R95%) to the Level A harassment
SELcum metric thresholds to assess the potential for PTS is considered an overly
conservative method, as it does not account for animal movement and behavior and,

therefore, assumes that animals are essentially stationary at that distance for the entire
duration of the pile installation, a scenario that does not reflect realistic animal behavior.
However, because NMFS’ Level A harassment (SPLpeak) and Level B harassment
(SPLrms) thresholds refer to instantaneous exposures, acoustic ranges are a better
representation of distances to these NMFS’ instantaneous harassment thresholds. These
distances were not applied to exposure estimation but were used to define the Level B
harassment zones for all species (see Proposed Mitigation and Monitoring) for WTG
and OSP foundation installation in summer and winter, and the minimum visibility zone
for installation of foundations in the NARW EMA (see Proposed Mitigation and
Monitoring). The following tables present the largest acoustic ranges (R95%) among
modeling sites (Figure 2 in Limpert et al., 2024) resulting from JASCO’s source and
propagation models, for both “summer” and “winter.” Table 15 presents the R95%
distances to the Level A harassment (SPLpeak) isopleths. Table 16 provides R95% distances
to the Level A harassment (SELcum) thresholds for impact-only and combined method
(i.e., vibratory and impact pile driving) installations, respectively. Finally, table 17
presents R95% distances for Level B harassment thresholds, for impact (160 dB) and
vibratory (120 dB) pile driving.
Table 15 – Acoustic Ranges (R95%), in Kilometers (km), to Marine Mammal Level A
Harassment Thresholds (SPLpeak) During Impact Pile Driving of 9/16-m Monopiles,
4.5-m Pre-Piled WTG Jackets, and 4.5-m Post-Piled OSP Jackets, Assuming 10 dB
Attenuation in Both Summer and Winter
Distances to Level A (SPLpeak) Harassment Thresholds (km)
Hearing Group

WTG 9/16-m monopile

WTG 4.5-m pre-piled pin

OSP 4.5-m post-piled pin

Summer

Winter

Summer

Winter

Summer

Winter

LFC

-

-

-

-

-

-

MFC

-

-

-

-

-

-

HFC

0.27

0.26

0.12

0.13

0.14

0.13

PW

-

-

-

-

-

-

Table 16 – Acoustic Ranges (R95%), in Kilometers (km), to Marine Mammal Level A
Harassment Thresholds (SELcum) During Pile Driving of 9/16-m Monopiles, 4.5-m
Pre-Piled WTG Jackets, and 4.5-m Post-Piled OSP Jackets, Assuming 10 dB
Attenuation in Both Summer and Winter
Hearing
Group

LFC
MFC

HFC

PW

Impact (I)
or
Vibratory1
and Impact
(V/I)
Installation

Distances to Level A (SPLcum) Harassment Thresholds (km)
WTG 9/16-m monopile

WTG 4.5-m pre-piled
pin

OSP 4.5-m post-piled pin

Summer

Winter

Summer

Winter

Summer

Winter

I

6.09

6.68

4.94

5.16

5.83

6.21

V/I

6.19

6.8

2.11

2.15

-

-

I

-

-

-

-

-

-

V/I

-

-

-

-

-

-

I

0.26

0.3

0.09

0.09

0.11

0.12

V/I

0.2

0.2

0.02

0.02

-

-

I

0.79

0.79

0.48

0.49

0.68

0.71

V/I

0.81

0.85

0.11

0.11

-

-

1 – Vibratory pile driving applies to Project 2 only.

Table 17 – Acoustic Ranges (R95%), in Kilometers (km), to the Marine Mammal
Level B Harassment Thresholds During Impact (160 dB) and Vibratory1 (120 dB)
Pile Driving of 9/16-m Monopiles, 4.5-m Pre-Piled WTG Jackets, and 4.5-m PostPiled OSP Jackets, Assuming 10 dB Attenuation, in Summer and Winter
Distances to Level B (SPLrms) Harassment Thresholds (km)
Installation
Approach

WTG 9/16-m monopile

WTG 4.5-m pre-piled pin

OSP 4.5-m post-piled pin

Summer

Winter

Summe

Winter

Summer

Winter

Impact

7.44

8.63

4.18

4.41

4.88

5.24

Vibratory

42.02

84.63

15.83

21.92

-

-

1 – Vibratory pile driving applies to Project 2 only.

To assess the extent to which marine mammal harassment might occur as a result
of movement within this acoustic environment, JASCO next conducted animal movement
and exposure modeling.
Animal Movement Modeling
To estimate the probability of exposure of animals to sound above NMFS’
harassment thresholds to during foundation installation, JASCO’s Animal Simulation
Model Including Noise Exposure (JASMINE) was used to integrate the sound fields
generated from the source and propagation models described above with species-typical

behavioral parameters (e.g., swim speeds dive patterns). The parameters used for
forecasting realistic behaviors (e.g., diving, foraging, and surface times) were determined
and interpreted from marine species studies (e.g., tagging studies) where available, or
reasonably extrapolated from related species (Limpert et al., 2024).
Applying animal movement and behavior within the modeled noise fields allows
for a more realistic indication of the distances at which PTS acoustic thresholds are
reached that considers the accumulation of sound over different durations. Sound
exposure models such as JASMINE use simulated animals (animats) to sample the
predicted 3-D sound fields with movement derived from animal observations (see
Limpert et al., 2024). Animats that exceed NMFS’ acoustic thresholds are identified and
the range (distance from the noise source) for the exceedances determined. The output of
the simulation is the exposure history for each animat accumulated within the simulation.
An individual animat’s sound exposure levels are summed over a specific duration, (24
hours), to determine its total received acoustic energy (SEL) and maximum received
SPLPK and SPLrms. These received levels are then compared to the harassment threshold
criteria. The combined history of all animats gives a probability density function of
exposure above threshold levels. The number of animals expected to exceed the
regulatory thresholds is determined by scaling the number of predicted animat exposures
by the species-specific density of animals in the area. By programming animats to behave
like the 16 marine mammal species that may be exposed to pile driving noise, the sound
fields are sampled in a manner similar to that expected for real animals.
Vibratory setting of piles followed by impact pile driving is being considered for
Project 2 (Scenarios 2 and 3). Given the qualities of vibratory pile driving noise (e.g.,
continuous, lower hammer energy), Level A harassment (PTS) is not an anticipated
impact on marine mammals incidental to SouthCoast’s use of this method. Although the
potential to induce hearing loss is low during vibratory driving, it does introduce some

SEL exposure that must be considered in the 24- hour SELcum estimates. For this reason,
JASCO computed acoustic ranges from the combined sound energy from vibratory and
impact pile driving. These results are presented in Appendix G in Limpert et al. (2024).
The PTS-onset SEL thresholds are lower for impact piling than for vibratory piling (table
7) so, to be conservative, when estimating acoustic ranges and the number of animats
exposed to potentially injurious sound levels from both impact and vibratory pile driving
(for those piles that may require both methods), the lower (impulsive) SEL criteria were
applied to determine if thresholds were exceeded.
Estimating the number of animats that may be exposed to sound above a
behavioral SPL response threshold is simpler because it does not require integrating
sound pressure over long time periods. This calculation was done separately for vibratory
and impact pile driving because these two sound sources use different thresholds, and
they are temporally separated activities (i.e., impact follows vibratory pile driving). The
numbers of animats exposed above the 120 dB (vibratory) and 160 dB (impact) Level B
harassment thresholds are calculated individually and then the resulting numbers are
combined to get total behavioral exposures from a single pile installed at each
representative location when both hammer types are expected to be used on a pile.
Individual animats that are exposed above behavioral thresholds for both vibratory and
impact pile driving are only counted once to avoid over-estimation.
For modeled animats that have received enough acoustic energy to exceed a given
harassment threshold, the exposure range for each animal is defined as the closest point
of approach (CPA) to the source made by that animal while it moved throughout the
modeled sound field, accumulating received acoustic energy. The CPA for each of the
species-specific animats during a simulation is recorded and then the CPA distance that
accounts for 95 percent of the animats that exceed an acoustic threshold is determined.
The ER95% (95 percent exposure radial distance) is the horizontal distance that includes

95 percent of the CPAs of animats exceeding a given impact threshold. The ER95% ranges
are species-specific rather than categorized only by any functional hearing group, which
allows for the incorporation of more species-specific biological parameters (e.g., dive
durations, swim speeds) for assessing the potential for PTS from pile driving.
Furthermore, because these ER95% ranges are species-specific, they can be used to
develop mitigation monitoring or shutdown zones.
As described in the Detailed Description of Specific Activity section,
SouthCoast proposed construction schedules that include both sequential and concurrent
foundation installations. For sequential installations (both vibratory and/or impact) of two
monopiles foundations or four jacket pin piles per day, two sites were used for modeling
(see Figures 7 and 8, Section 2.51 of Appendix A in Limpert et al., 2024), both
considered representative locations of the Lease Area (one location for each foundation).
Animats were exposed to only one sound field at a time. Received levels were
accumulated over each animat's track over a 24-hour time window to derive sound
exposure levels (SEL). Instantaneous single-exposure metrics (e.g., SPLrms and SPLpeak)
were recorded at each simulation time step, and the maximum received level was
reported.
Concurrent operations were handled slightly differently to capture the effects of
installing piles spatially close to each other (i.e., 2 nm (2.3 mi; 3.7 km)). The sites chosen
for exposure modeling for concurrent operations are shown in Figure 9, Section 2.51 in
Limpert et al. (2024). When simulating concurrent operations in JASMINE, sound fields
from separate piles may be overlapping in time and space. For cumulative metrics
(SELcum), received energy from each sound field the animat encounters is summed over a
24-hour time window. For SPL, received levels were summed within each simulation
time step and the resultant maximum SPL over all time steps was carried forward. For

both sequential and concurrent operations, the resulting cumulative or maximum received
levels were then compared to the NMFS’ thresholds criteria within each analysis period.
Additional assumptions used in modeling for each year of construction are
summarized in table 18. As discussed previously, modeling assumed SouthCoast would
install Project 1 WTG foundations using only impact pile driving and Project 2 WTG
foundations using vibratory and/or impact pile driving. All pin piles supporting OSP
jacket foundations would be impact driven. In addition, modeling assumed a seasonal
restriction on pile driving from January 1 through April 30. However, as previously
described, to provide additional North Atlantic right whale protection, SouthCoast would
not install foundation in the NARW EMA from October 16 through May 31 or
throughout the rest of the Lease Area from January 1 to May 15.
Table 18 – Assumptions Used in WTG and OSP Foundation Installation Exposure
Modeling
Project 1

Project 2

WTG
Monopiles
Scenario 1

WTG
Jackets
Scenario 2

OSP
jackets

WTG
Monopiles
Scenario 1

WTG
Monopiles
Scenario 2

WTG
Jackets
(Scenario
OSP
jackets

# of
foundation
s

85

68

62

Pile
diameter
(m)

9/16

4.5

4.5

9/16

9/16

4.5

4.5

Piles per
foundation

4

12-16

1

12-16

Penetratio
n depth
(m)

60

35

60

Max
hammer
energy
(kJ)

3500

6600

3500

Impact or
Vibratory

Impact

Impact

Impact

Impact

Both

Both

Impact

Parameter

Number of
impact
strikes1

4000

7000

7000/5000

4000/2667

Piles/day

1-2

4

1-2

1-2

4

Piling
Days

85

0.75

49

0.75

1 – The second value is the number of strikes required when vibratory preceded impact pile driving

All proposed construction scenarios, including foundation type, installation
method, number of monopiles or pin piles installed per day, and the rate of installation
were presented in table 2 in the Detailed Description of Specific Activities section.
Tables 19-23 summarize the monthly construction schedules for each scenario
assumed for modeling, including installation sequence and method, and the number of
pile driving days per month. However, construction schedules cannot be fully predicted
due to uncontrollable environmental factors (e.g., weather) and installation schedules
include variability (e.g., due to drivability). The total number of construction days per
month would be dependent on a number of factors, including environmental conditions,
planning, construction, and installation logistics. As described previously, SouthCoast
assumed that for sequential WTG foundation installations (using a single vessel), a
maximum of 2 WTG monopiles or 4 OSP piled jacket pin piles may be driven in 24
hours. For concurrent installation (using two vessels), a maximum of 2 WTG monopiles
and 4 OSP piled jacket pin piles or 4 WTG and 4 OSP pin piles may be driven in 24
hours. It is unlikely that these maximum installation rates would be consistently
attainable throughout the construction phase, but this schedule was considered to have the
greatest potential for Level A harassment (PTS) and was, therefore, carried forward into
take estimation.
Table 19 – SouthCoast’s Potential Foundation Installation Schedule for Project 1
Scenario 1 (P1S1)
Month

Vibratory & Impact

Concurrent
Impact

Impact

Totals

WTG Monopile

WTG
Monopile
& OSP
Jacket Pin
Piles

WTG Monopile

2/day

1/day

1/day &
4/day

2/day

1/day

Total piles

Total days

May

0

0

2

June

0

1

10

July

0

3

16

Aug

0

4

18

Sept

0

3

15

Oct

0

1

20

Nov

0

0

1

Dec

0

0

1

Total

0

12

83

Table 20 – SouthCoast’s Potential Foundation Installation Schedule for Project 1
Scenario 2 (P1S2)
Vibratory &
Impact

Concurrent
Impact

WTG Jacket

WTG
Monopile &
OSP Jacket Pin
Piles

WTG Jacket

4/day

1/day & 4/day

4/day

Total piles

Total days

May

0

32

June

0

40

July

0

48

Aug

0

56

Sept

0

48

Oct

4

80

Nov

0

40

Dec

0

12

Total

0

356

Month

Impact
Totals

Table 21 – SouthCoast’s Potential Foundation Installation Schedule for Project 2
Scenario 1 (P2S1)

Month

Vibratory & Impact

Concurrent
Impact

WTG Monopile

WTG
Monopile
& OSP
Jacket Pin
Piles

Impact
Totals
WTG Monopile

2/day

1/day

1/day &
4/day

2/day

1/day

Total piles

Total days

May

0

0

2

June

0

3

12

July

0

3

12

Aug

0

3

12

Sept

0

3

12

Oct

0

3

27

Nov

0

0

2

Dec

0

0

1

Total

0

15

80

Table 22 – SouthCoast’s Potential Foundation Installation Schedule for Project 2
Scenario 2 (P2S2)

Month

Vibratory & Impact

Concurrent
Impact

WTG Monopile

WTG
Monopile
& OSP
Jacket Pin
Piles

Impact
Totals
WTG Monopile

2/day

1/day

1/day &
4/day

2/day

1/day

Total piles

Total days

May

0

0

2

June

4

0

8

July

4

0

16

Aug

4

0

18

Sept

4

0

16

Oct

2

0

23

Nov

1

0

1

Dec

0

0

1

Total

19

0

85

Table 23 – SouthCoast’s Potential Foundation Installation Schedule for Project 2
Scenario 3 (P2S3)
Vibratory &
Impact

Concurrent
Impact

WTG Jacket

WTG
Monopile &
OSP Jacket Pin
Piles

WTG Jacket

4/day

1/day & 4/day

4/day

Total piles

Total days

May

0

20

June

0

36

July

0

36

Aug

0

36

Sept

0

36

Oct

4

56

Nov

0

24

Dec

0

20

Total

4

264

Month

Impact
Totals

By incorporating animal movement into the calculation of ranges to timedependent thresholds (SEL metrics), ER95% values provide a more realistic assessment of
the distances within which acoustic thresholds may be exceeded. This also means that
different species within the same hearing group can have different exposure ranges as a
result of species-specific movement patterns. Substantial differences (greater than 500 m
(1,640 ft)) between species within the same hearing group occurred for low frequencycetaceans, so Level A harassment (PTS) ER95% values are shown separately for those
species (tables 24-29). For mid-frequency cetaceans and pinnipeds, the largest value from
any single species was selected.
Projects 1 and 2 would include sequential WTG foundation installations using
impact pile driving only and both vibratory and impact pile driving (Project 2 only), and
concurrent WTG and OSP installations using only impact pile driving, each of which

generates different ER95% distances. The Level A harassment (PTS) ER95% distances for
sequential installation of WTG foundations using only impact pile driving are shown in
table 24 for both summer and winter. SouthCoast does not anticipate conducting
vibratory or concurrent pile driving in December, thus the Level A harassment (PTS)
ER95% distances for sequential installation of WTG foundations (both monopile and pinpiled jacket) using both vibratory and impact pile driving are shown in table 25 for
summer only. Lastly, Level A harassment (PTS) ER95% distances for potential concurrent
installation of WTG and OSP foundations using impact pile driving (also limited to
“summer” for modeling) are shown in table 26.
Comparison of the results in table 24 and table 26 show that the case assuming
sequential installation of two WTG monopiles per day and concurrent installation of two
WTG monopiles and 4 OSP piles per day yield very similar results. This may seem
counterintuitive, given the assumed number of piles installed per day for concurrent
installations is larger than that assumed for sequential installations, thus it might be
expected that Level A harassment (PTS) ER95% distances would be larger for concurrent
installations. However, for that result to occur, animal movement modeling would have
to show that animals would routinely occur close enough to one pile driving location
(e.g., WTG monopile) to accumulate enough sound energy without exceeding the Level
A harassment SELcum threshold, and then also occur at the second pile driving location
(e.g., OSP jacket) at a distance close enough to accumulate the remaining sound energy
needed to cross the SELcum threshold. The animal movement modeling showed this
sequence of events did not happen often enough during concurrent installations of WTG
monopile and OSP jacket foundations to cause a consistent increase in the Level A
harassment (PTS) ER95% distances across all species. This sequence of events did occur
more often during concurrent installation of WTG jacket and OSP jacket foundation
installations, thus the Level A harassment (PTS) ER95% distances for concurrent

installations were consistently larger than for installation of a single WTG jacket
foundation on a given day (table 26). This was likely a result of the overall longer
duration of pile driving per day required for installing 4 pin piles for each jacket
foundation.
Table 24 – Exposure Ranges (ER95%)1 to the Marine Mammal PTS (Level A)
Cumulative Sound Exposure Level (SELcum) Thresholds for Sequential Impact Pile
Driving Installation of One or Two 9/16-m WTG Monopiles, Four 4.5-m WTG
Jacket Pin Piles, or Four 4.5-m OSP Jacket Pin Piles in One Day, Assuming 10 dB of
Broadband Noise Attenuation in Summer (S) and Winter (W)2
Range (km)
SELcum
Thresho
ld (dB
re 1
μPa2
·s)

9/16-m WTG
Monopiles
(1 piles/day)

9/16-m WTG
Monopiles
(2 piles/day)

S

W

S

W3

S

W

S

W

Blue
whale*

-

-

-

-

-

-

-

-

Fin
whale*

3.99

4.49

4.15

-

2.37

2.55

3.18

3.50

Humpb
ack
whale

3.13

3.66

3.46

-

1.88

1.96

2.36

2.54

Minke
whale

2.41

2.42

-

1.24

1.28

1.58

1.79

N.Atl.
right
whale*

2.83

3.23

2.95

-

1.73

1.85

2.01

2.13

Sei
whale*

3.06

3.38

3.19

-

1.96

2.22

2.59

2.72

Hearing
Group

4.5-m WTG Jacket
Pin Piles
(4 piles/day)

4.5-m OSP Jacket
Pin Piles
(4 piles/day)

Midfrequen
cy

0

0

-

0

0

Highfrequen
cy

0

0

-

0

0

Phocids

0.4

0.34

0.12

-

0.32

0.41

0.41

* Denotes species listed under the Endangered Species Act
1 – These are the maximum ER95% values among modeling locations (L01 and L02 in Limpert et al., 2024).
2 – For acoustic propagation modeling, two average sound speed profiles were used, one for the “summer”
season (May-November) and a second for the “winter” season (December)
3 – Given the small number of foundation installations planned for December (see tables 19-23), modeling
assumed installation of only a single monopile per day for “winter.”

Table 25 – Exposure Ranges (ER95%)1 to the Marine Mammal Level A Cumulative
Sound Exposure Level (SELcum) Thresholds During Sequential Vibratory2 and
Impact Pile Driving Installation of One or Two 9/16-m WTG Monopiles or Four 4.5m WTG Jacket Pin Piles Assuming 10 dB of Attenuation in Summer3

Hearing
Group

SELcum
Threshold
(dB re 1
μPa2 ·s)

Range (km)
WTG Monopile
(1 pile/day)

WTG Monopile
(2 piles/day)

WTG Jacket Pin Piles
(4 piles/day)

Impact

Vibratory

Impact

Vibratory

Impact

Vibratory

Blue
whale*

-

-

-

-

-

-

Fin
whale*

3.98

4.11

0.08

2.25

Humpback
whale

3.10

3.49

0.18

1.84

2.41

2.37

1.13

N.Atl.
right
whale*

2.81

3.07

0.13

1.57

Sei
whale*

3.11

3.13

1.84

Minke
whale

Midfrequency

0

0

0

Highfrequency

0

0

0

Phocids

0.01

0.11

0

* Denotes species listed under the Endangered Species Act
1 – These are the maximum ER95% values among modeling locations (L01 and L02 in Limpert et al.,
2024).
2 – SouthCoast proposed vibratory pile driving for Project 2 (Scenarios 2 and 3) but not for Project 1.
3 – For acoustic propagation modeling, two average sound speed profiles were used, one for the “summer”
season (May-November) and a second for the “winter” season (December). Modeling assumed vibratory
pile driving would only occur in “summer,” thus, table 25 does not present “winter” values.

Table 26 – Exposure Ranges (ER95%)1 to the Marine Mammal Level A Cumulative
Sound Exposure Level (SELcum) Thresholds During Concurrent2 Impact Pile
Driving Installation of Two 9/16-m WTG Monopiles And Four 4.5-m Osp Jacket
Pin Piles, or Four 4.5-m WTG Jacket Pin Piles2 and Four 4.5-m Osp Jacket Pin Pile
in One Day Assuming 10 dB of Broadband Noise Attenuation in Summer3
Range (km)
Hearing Group

SELcum Threshold (dB
re 1 μPa2 ·s)

16-m WTG Monopiles
(2 piles/day)
and

4.5-m WTG Jacket Pin
Piles (4 piles/day)
and

4.5-m OSP Jacket Pin
Piles (4 piles/day)

4.5-m OSP Jacket Pin
Piles (4 piles/day)

Low-frequency

Blue whale

-

-

-

Fin whale*

-

4.53

3.58

Humpback whale

-

3.71

2.57

Minke whale

-

2.31

1.56

N.Atl. right whale*

-

3.07

1.92

Sei whale*

-

3.44

2.31

Mid-frequency

0

High-frequency

0

Phocids

0.3

0.17

* Denotes species listed under the Endangered Act
1 – These are the maximum ER95% values among modeling locations (L01 and L02 in Limpert et al., 2024).
2 – SouthCoast proposed concurrent impact pile driving of WTG and OSP foundations for Projects 1 and 2.
3 – For acoustic propagation modeling, two average sound speed profiles were used, one for the “summer”
season (May-November) and a second for the “winter” season (December).

In addition to ER95% distances to Level A harassment (PTS) thresholds, exposure
modeling produced ER95% distances to the Level B harassment 160 dB SPLrms (impact
pile driving) and 120 dB SPLrms (vibratory pile driving) thresholds. The following tables
provide the Level B harassment ER95% distances for 1) sequential installation of WTG
foundations using only impact pile driving for summer and winter (table 27); 2) summeronly sequential installation of WTG foundations (both monopile and pin-piled jacket)
using both vibratory and impact pile driving (table 28); and 3) concurrent installation of
WTG monopile and OSP pin-piled jacket foundations (table 29, also limited to
“summer”). These ranges were used to define the outer perimeter around the Lease Area
from which Roberts et al. (2016, 2023) model data density grid cells were selected for
exposure estimation.

Table 27 – Exposure Ranges (ER95%)1 to the Marine Mammal 160 dB Level B
Harassment (Splrms) Threshold for Sequential Impact Pile Driving Installation of
One or Two 9/16-m WTG Monopiles, Four 4.5-m WTG Jacket Pin Piles, or Four
4.5-m OSP Jacket Pin Piles in One Day, Assuming 10 dB of Broadband Noise
Attenuation in Summer (S) And Winter (W)2
Range (km)
9/16-m WTG
Monopiles
(1 piles/day)

9/16-m WTG
Monopiles
(2 piles/day)

S

W

S

W3

S

W

S

W

North
Atlantic
Right
whale*

6.82

7.66

6.71

–

3.73

3.85

4.28

4.54

Blue
Whale*

–

–

–

–

–

–

–

–

Fin
Whale*

7.08

8.33

7.03

–

3.92

4.27

4.55

4.94

Sei
Whale*

7.04

8.17

6.86

–

3.85

3.90

4.42

4.88

Minke
Whale

6.61

7.64

6.68

–

3.47

3.67

4.34

4.60

Humpbac
k Whale

6.97

8.03

6.79

–

3.77

4.01

4.45

4.82

Sperm
Whale*

6.93

7.93

6.75

–

3.73

3.92

4.34

4.72

Atlantic
Spotted
Dolphin

6.94

8.17

6.64

–

3.80

3.87

4.40

4.73

Atlantic
WhiteSided
Dolphin

6.57

7.53

6.54

–

3.55

3.61

4.14

4.38

Bottlenos
e
Dolphin,
Offshore

5.51

6.55

5.46

–

3.08

3.22

3.72

3.86

Common
Dolphin

6.67

7.61

6.44

–

3.63

3.80

4.38

4.60

Pilot
Whale

6.80

7.65

6.60

–

3.66

3.76

4.31

4.64

Risso’s
Dolphin

7.02

7.89

6.87

–

3.68

4.08

4.42

4.71

Harbor
Porpoise

6.67

7.54

6.67

–

3.47

3.75

4.31

4.58

Species

4.5-m WTG Jacket
Pin Piles
(4 piles/day)

4.5-m OSP Jacket Pin
Piles
(4 piles/day)

Gray Seal

7.48

8.58

7.29

–

4.04

4.29

4.68

5.18

Harbor
Seal

6.91

7.87

6.84

–

3.61

4.00

4.40

4.75

* Denotes species listed under the Endangered Species Act
1 – These are the maximum ER95% values among modeling locations (L01 and L02 in Limpert et al.,
2024).
2 – For acoustic propagation modeling, two average sound speed profiles were used, one for the “summer”
season (May-November) and a second for the “winter” season (December).
3 – Given the small number of foundation installations planned for December (see tables 19-23), modeling
assumed installation of only a single monopile per day for “winter.”

Table 28 – Exposure Ranges (ER95%)1 to the Marine Mammal 160 dB and 120 dB
Level B Harassment (SPLrms) Thresholds During Sequential Vibratory2 and Impact
Pile Driving Installation of One or Two 9/16-m WTG Monopiles3 or Four 4.5-m
WTG Jacket Pin Piles4 Assuming 10 dB of Broadband Noise Attenuation in
Summer5
Range (km)
Species

WTG Monopile (1 pile/day)

WTG Monopile
(2 piles/day)

WTG Jacket Pin Piles
(4 piles/day)

Impact

Vibratory

Impact

Vibratory

Impact

Vibratory

North
Atlantic right
whale

6.77

39.14

6.72

38.20

5.12

15.21

Blue Whale*

-

-

-

-

-

-

Fin Whale

7.06

41.83

7.00

41.69

5.48

15.75

Sei Whale

7.01

41.15

6.87

40.46

5.35

15.43

Minke
Whale

6.65

38.77

6.69

38.49

5.06

14.99

Humpback
Whale

6.96

39.71

6.84

39.06

5.23

15.47

Sperm
Whale

6.83

40.64

6.81

40.27

5.32

15.27

Atlantic
Spotted
Dolphin

6.90

40.92

6.65

39.53

5.35

15.72

Atlantic
White-Sided
Dolphin

6.64

38.50

6.58

37.57

5.03

14.67

Bottlenose
Dolphin,
Offshore

5.46

34.63

5.42

33.05

4.32

13.22

Common
Dolphin

6.74

40.99

6.43

39.94

5.17

15.11

Pilot Whale

6.70

40.42

6.56

39.17

5.12

15.22

Risso’s
Dolphin

6.97

41.86

6.86

41.27

5.26

15.45

Harbor
Porpoise

6.68

37.31

6.59

36.86

5.16

14.85

Gray Seal

7.49

40.66

7.30

40.38

5.54

15.68

Harbor Seal

6.81

39.66

6.84

39.28

5.11

14.91

* Denotes species listed under the Endangered Species Act
1 – These are the maximum ER95% values among modeling locations (L01 and L02 in Limpert et al., 2024).
2 – SouthCoast proposed vibratory pile driving for Project 2, Scenarios 2 and 3, but not for Project 1.
3 – Monopiles installed by 20 minutes of vibratory pile driving using HX-CV640 hammer followed by
5,000 strikes using NNN 6600 impact hammer
4 – Pin piles installed by 90 minutes of vibratory pile driving using S-CV640 hammer followed by 2,667
strikes using MHU 3500S impact hammer
5 – For acoustic propagation modeling, two average sound speed profiles were used, one for the “summer”
season (May-November) and a second for the “winter” season (December). Modeling assumed vibratory
pile driving would only occur in “summer,” thus, table 28 does not present “winter” values.

Table 29 – Exposure Ranges (ER95%) to the Marine Mammal 160 dB Level B
Harassment (SPLrms) Threshold During Concurrent Impact Pile Driving
Installation of Two 9/16-m WTG Monopiles and Four 4.5-m OSP Jacket Pin Piles,
or Four 4.5-m Wtg Jacket Pin Piles and Four 4.5-m OSP Jacket Pin Pile in One Day
Assuming 10 dB of Broadband Noise Attenuation in the Summer 1
Range (km)

Species

16-m WTG Monopiles (2
piles/day)
and
4.5-m OSP Jacket Pin Piles (4
piles/day)

4.5-m WTG Jacket Pin Piles (4
piles/day)
and
4.5-m OSP Jacket Pin Piles (4
piles/day)

Fin whale*

4.53

3.58

Humpback whale

3.71

2.57

Minke whale

2.31

1.56

N.Atl. right whale*

3.07

1.92

Sei whale*

3.44

2.31

Mid-frequency

0

High-frequency

0

Phocids

0.3

0.17

* Denotes species listed under the Endangered Act
1 – For acoustic propagation modeling, two average sound speed profiles were used, one for the “summer”
season (May-November) and a second for the “winter” season (December). Modeling assumed concurrent
installations would only occur in October, thus table 29 present values for summer only.

SouthCoast modeled potential Level A harassment and Level B harassment
density-based exposure estimates for all five foundation installation schedules (P1S1P2S3), all of which include sequential pile driving and concurrent pile driving. In
creating the installation schedules used for exposure modeling, the total number of
installations was spread across all potential months in which they might occur (May-

December) in order to incorporate the month-to-month variability in species densities.
SouthCoast assumed that the OSP jacket foundations would be installed in October for
each Project.
For both WTG and OSP foundation installations, mean monthly densities were
calculated by first selecting density data from 5 x 5 km (3.1 x 3.1 mi) grid cells (Roberts
et al., 2016; 2023) both within the Lease Area and beyond its boundaries to
predetermined perimeter distances. The widths of the perimeter (referred to as a “buffer”
in SouthCoast’s application) around the activity area used to select density data were
determined using the ER95%, distances to the isopleths corresponding to Level A
harassment (tables 24-26) and Level B harassment (table 27-29) thresholds, assuming 10dB attenuation, which vary according to sound source (impact/vibratory piling) and
season. For each species, foundation type and number, installation method, and season,
the most appropriate density perimeter was selected from the predetermined distances
(i.e., 1 km (0.6 mi), 5 km (3.1 mi), 10 km (6.2 mi), 15 km (9.3 mi), 20 km (12.4 mi), 30
km (18.6 mi), 40 km (25 mi), and 50 km (31.1 mi)) by rounding the ER95% up to the
nearest predetermined perimeter size. For example, if the Level A harassment (PTS)
ER95% was 7.1 km (4.4 mi) for a given species and activity, a 10-km (6.2-mi) perimeter
was created around the Lease Area and used to calculate mean monthly densities that
were used in foundation installation Level A harassment (PTS) exposure estimates (e.g.,
table 30). Similarly, if the 160 dB Level B harassment ER95% was 20.1 km (12.5 mi) for a
given species or activity, a 30-km (18.6-mi) perimeter around the Lease Area was created
and used to calculate mean monthly densities for exposure estimation. In cases where the
ER95% was larger than 50 km (31.1 mi), the 50-km (31.1-mi) perimeter was used. The 50km (31.1-mi) limit is derived from studies of mysticetes that demonstrate received levels,
distance from the source, and behavioral context are known to influence the probability
of behavioral response (Dunlop et al., 2017). Please see Figure 10 in SouthCoast’s ITA

Application for an example of a density map showing the Roberts et al. (2016; 2023)
density grid cells overlaid on a map of the Lease Area. Given the extensive number of
density tables used for exposure modeling, we do not present them here beyond the
example provided in table 30. Please see tables in Section H.2.1.1 of Appendix H in
Limpert et al. (2024) for densities within the areas defined by additional perimeter sizes
(i.e., 1 km (0.6 mi), 5 km (3.1 mi), 10 km (6.2 mi), 15 km (9.3 mi), 20 km (12.4 mi), 30
km (18.6 mi), 40 km (25 mi), and 50 km (31.1 mi)).

Table 30 – Mean Monthly Marine Mammal Density Estimates (Animals/km2) Within 10-km (6.2 mi) of the Lease Area
Perimeter
Species

Jan

Feb

Mar

Apr

May

Jun

July

Aug

Sep

Oct

Nov

Dec

North
Atlantic
right whale*

0.0054

0.0060

0.0054

0.0050

0.0037

0.0008

0.0004

0.0003

0.0004

0.0006

0.0011

0.0033

Blue
Whale*

0.0000

0.000

0.000

0.000

0.000

0.000

0.0000

0.000

0.000

0.000

0.000

0.000

Fin Whale*

0.0022

0.0018

0.0015

0.0015

0.0030

0.0029

0.0047

0.0036

0.0027

0.0009

0.0005

0.0004

Sei Whale*

0.0004

0.0003

0.0005

0.0012

0.0019

0.0007

0.0002

0.0001

0.0002

0.0004

0.0009

0.0007

Minke
Whale

0.0011

0.0013

0.0014

0.0075

0.0151

0.0175

0.0080

0.048

0.0054

0.0050

0.0005

0.0007

Humpback
Whale

0.0003

0.0003

0.0005

0.0018

0.0031

0.0035

0.0021

0.0012

0.0017

0.0025

0.0020

0.0003

Sperm
Whale*

0.0005

0.0002

0.0002

0.0000

0.0002

0.0003

0.0005

0.0017

0.0009

0.0006

0.0004

0.0003

Atlantic
Spotted
Dolphin

0.0000

0.0000

0.0000

0.0001

0.0004

0.0006

0.0005

0.0008

0.0043

0.0068

0.0017

0.0002

Atlantic
WhiteSided
Dolphin

0.0263

0.0158

0.0111

0.0169

0.0369

0.0380

0.0204

0.0087

0.0193

0.0298

0.0225

0.0321

Bottlenose
Dolphin,
Offshore

0.0051

0.0012

0.0008

0.0022

0.0097

0.0163

0.0177

0.0200

0.0198

0.0181

0.0160

0.0129

Common
Dolphin

0.0933

0.0362

0.0320

0.0474

0.0799

0.1721

0.0154
0.2008

0.3334

0.3331

0.1732

0.1467

Pilot
Whales

0.0029

0.0029

0.0029

0.0029

0.0029

0.0029

0.0029

0.0029

0.0029

0.0029

0.0029

0.0029

Risso’s
Dolphin

0.0005

0.0001

0.0000

0.0003

0.0014

0.0010

0.0013

0.0028

0.0035

0.0017

0.0015

0.0020

Harbor
Porpoise

0.1050

0.1135

0.1081

0.0936

0.0720

0.0174

0.0174

0.0156

0.0165

0.0203

0.0219

0.0675

Gray Seal

0.0594

0.0585

0.0419

0.0379

0.0499

0.0075

0.0019

0.0016

0.0028

0.0064

0.0246

0.0499

Harbor Seal

0.1335

0.1314

0.0941

0.0850

0.1120

0.0167

0.0043

0.0037

0.0063

0.0145

0.0552

0.1120

*Listed as Endangered under the ESA.
1 – Densities were calculated using the 2022 Duke Habitat-Based Marine Mammal Density Models (Roberts et al., 2016; 2023).

As previously discussed, SouthCoast’s ITA application includes installation of up
to 147 WTG foundations and up to 5 OSP foundations in 149 positions within the Lease
Area. However, for the purposes of exposure modeling, SouthCoast assumed installation
of two OSPs (one per Project), each supported by a piled jacket foundation secured by 12
to 16 pin piles.
Table 31 – Foundation Installation Scenarios
Scenario

Method:
Impact or
Vibratory

WTG
Foundation
Type

WTG
foundation
Number

OSP Pin Pile
Number

Piling Days

Project 1
Scenario 1

Impact

Monopile

12

Scenario 2

Impact

Jacket

16

Project 2
Scenario 1

Impact

Monopile

12

Scenario 2

Both

Monopile

12

Scenario 3

Both

Jacket

16

SouthCoast calculated take estimates for all five foundation installation scenarios
presented in their application, based on modeled exposures and other relevant data (e.g.,
PSO date, mean group sizes). Tables 32-36 provide the results of marine mammal
exposure modeling, which assumes 10-dB attenuation and seasonal restrictions, for each
scenario. The Level A harassment exposure estimates represent animats that exceeded the
PTS SELcum thresholds as this metric was exceeded prior to exceeding PTS SPLpeak
thresholds The Level B harassment exposure estimates shown for Project 1 Scenarios 1
and 2, and Project 2 Scenario 1 represent animats exceeding the unweighted 160 dB
SPLrms criterion because impact pile driving would be the only installation method in
these scenarios. The Level B harassment exposure estimates shown for Project 2
Scenarios 2 and 3 (tables 32-36) represent animats exceeding the unweighted 120 dB
SPLrms and/or 160 dB SPLrms criteria because these scenarios require both vibratory and

impact pile driving. Columns 4 and 5 in tables 32-36 show what the take estimates would
be if the PSO data or average group size, respectively, were used to inform the number of
proposed takes by Level B harassment in lieu of the density and exposure modeling. The
last column represents the total Level B harassment take estimate for each species, based
on the highest of the three estimates (density-based exposures, PSO data, or average
group size).
Below we present the exposure estimates and the take estimates for these
scenarios (Tables 32-36). For Project 1, no single scenario results in a greater amount of
take for all species; therefore, the maximum annual and 5-year total amount of take
proposed for authorization is a combination of both scenarios depending on species (i.e.,
the scenario which resulted in the greatest amount of take was carried forward for each
species). For Project 2, Scenario 2 results in the greatest amount of take for all species
and is carried forward in the maximum annual and 5-year total amount of take proposed
for authorization.
Table 32 – Project 1 Scenario 1 (P1S1): Estimated Level A Harassment1 and Level B
Harassment2 Take From Installation of 71 WTG Monopile Foundations and 12 OSP
Jacket Pin Piles, Assuming 10 dB of Noise Attenuation

Species

Level A
Harassment
Exposure
Modeling
Take
Estimate
P1S1

Level B
Harassment
Exposure
Modeling
Take
Estimate
P1S1

PSO Data
Take
Estimate

Mean Group
Size

Blue whale*

N/A

N/A

-

Fin whale*

13.2

38.8

Humpback
whale

9.3

Minke
whale
North
Atlantic
right whale*

Estimated
Level A
Harassment
Take
P1S1

Estimated
Level B
Harassment
Take
P1S1

1.0

1

3.4

1.8

39

28.4

32.4

2.0

33

45.7

168.6

6.4

1.4

169

2.1

8.8

-

2.4

9

Sei whale*

1.3

4.7

0.9

1.6

5

Atlantic
spotted
dolphin

0.0

22.71

-

29.0

29

Atlantic
white-sided
dolphin

0.0

520.8

-

27.9

521

Bottlenose
dolphin

0.0

267.4

84.2

12.3

268

Common
dolphin

0.0

6,975.3

735.6

34.9

6.976

Harbor
porpoise

0.0

312.2

0.1

2.7

313

Pilot whales

0.0

60.7

3.7

10.3

61

Risso’s
dolphin

0.0

36.5

-

5.4

37

Sperm
whale*

0.0

12.4

0.3

2.0

13

Gray seal

0.1

209.6

2.0

1.4

210

Harbor seal

0.0

15.1

30.5

1.4

31

* Denotes species listed under the Endangered Species Act.
1 – Level A harassment take estimates assumes no implementation of monitoring and mitigation measures
beyond 10-dB attenuation using a Noise Mitigation System, and seasonal restrictions.
2 – Level B harassment take estimates are based on distances to the unweighted 120 dB threshold for
vibratory pile driving and 160 dB threshold for impact pile driving

Table 33 – Project 1 Scenario 2 (P1S2): Estimated Level A Harassment1 and Level B
Harassment2 Take From Installation of 85 Piled Jacket WTG Foundations and 16
OSP Jacket Pin Piles Assuming 10 dB of Noise Attenuation

Species

Level A
Harassment
Exposure
Modeling
Take
Estimate
P1S2

Blue whale*

N/A

Fin whale*

Level B
Harassment
Exposure
Modeling
Take
Estimate
P1S2

Estimated
Level A
Harassment
Take
P1S2

Estimated
Level B
Harassment
Take
P1S2

PSO Data
Take
Estimate

Mean Group
Size

N/A

-

1.0

1

10.3

22.4

3.8

1.8

23

Humpback
whale

11.7

28.4

37.0

2.0

37

Minke
whale

45.6

196.1

7.3

1.4

197

North
Atlantic
right whale*

3.9

12.0

-

2.4

12

Sei whale*

2.3

6.1

1.0

1.6

7

Atlantic
spotted
dolphin

0.0

24,4

-

29.0

29

Atlantic
white-sided
dolphin

0.0

727.1

-

27.9

728

Bottlenose
dolphin

0.0

303.5

96.0

12.3

304

Common
dolphin

0.0

8.552.1

839.2

34.9

8,553

Harbor
porpoise

0.0

377.3

0.2

2.7

378

Pilot whales

0.0

39.8

4.2

10.3

40

Risso’s
dolphin

0.0

29.1

-

5.4

30

Sperm
whale*

0.0

10.0

0.3

2.0

10

Gray seal

0.2

224.9

2.3

1.4

225

Harbor seal

0.0

25.8

34.8

1.4

35

* Denotes species listed under the Endangered Species Act.
1 – Level A harassment take estimates assumes no implementation of monitoring and mitigation measures
beyond 10-dB attenuation using a Noise Mitigation System, and seasonal restrictions.
2 – Level B harassment take estimates are based on distances to the unweighted 120 dB threshold for
vibratory pile driving and 160 dB threshold for impact pile driving

Table 34 – Project 2 Scenario 1 (P2S1): Estimated Level A Harassment1 and Level B
Harassment2 Take From Installation of 68 Monopile WTG Foundations and 12 OSP
Jacket Pin Piles Assuming 10 dB of Noise Attenuation

Species

Level A
Harassment
Exposure
Modeling
Take
Estimate
P2S1

Blue whale*

N/A

Fin whale*
Humpback
whale

Level B
Harassment
Exposure
Modeling
Take
Estimate
P2S1

Estimated
Level A
Harassment
Take
P2S1

Estimated
Level B
Harassment
Take
P2S1

PSO Data
Take
Estimate

Mean Group
Size

N/A

-

1.0

1

11.0

31.9

3.2

1.8

32

9.7

28.8

31.1

2.0

32

Minke
whale

45.0

163.9

6.2

1.4

164

North
Atlantic
right whale*

2.2

9.1

-

2.4

10

Sei whale*

1.5

5.2

0.8

1.6

6

Atlantic
spotted
dolphin

0.0

26.05

-

29.0

29

Atlantic
white-sided
dolphin

0.0

550.1

-

27.9

551

Bottlenose
dolphin

0.0

249.7

80.6

12.3

250

Common
dolphin

0.0

6,912.3

704.5

34.9

6,913

Harbor
porpoise

0.0

304.3

0.1

2.7

305

Pilot whales

0.0

57.5

3.5

10.3

58

Risso’s
dolphin

0.0

31.9

-

5.4

32

Sperm
whale*

0.0

10.4

0.3

2.0

11

Gray seal

0.1

234.1

1.9

1.4

235

Harbor seal

0.0

16.9

29.2

1.4

30

* Denotes species listed under the Endangered Species Act.
1 – Level A harassment take estimates assumes no implementation of monitoring and mitigation measures
beyond 10-dB attenuation using a Noise Mitigation System, and seasonal restrictions.
2 – Level B harassment take estimates are based on distances to the unweighted 120 dB threshold for
vibratory pile driving and 160 dB threshold for impact pile driving

Table 35 – Project 2 Scenario 2 (P2S2): Estimated Level A Harassment1 and Level B
Harassment2 Take From Installation of 73 Monopile WTG Foundations and 12 OSP
Jacket Pin Piles Assuming 10 dB of Noise Attenuation

Species

Level A
Harassment
Exposure
Modeling
Take
Estimate
P2S2

Blue whale*

N/A

Fin whale*

14.3

Level B
Harassment
Exposure
Modeling
Take
Estimate
P2S2

Estimated
Level A
Harassment
Take
P2S2

Estimated
Level B
Harassment
Take
P2S2

PSO Data
Take
Estimate

Mean Group
Size

N/A

-

1.0

1

482.0

7.2

1.8

481

Humpback
whale

10.7

282.0

69.9

2.0

282

Minke
whale

49.6

868.2

13.9

1.4

869

North
Atlantic
right whale*

2.3

100.0

-

2.4

100

Sei whale*

1.4

41.9

1.9

1.6

42

Atlantic
spotted
dolphin

0.0

319.59

-

29.0

320

Atlantic
white-sided
dolphin

0.0

3,045.0

-

27.9

3,045

Bottlenose
dolphin

0.0

2,341.1

181.4

12.3

2,342

Common
dolphin

0.0

41,092.2

1,585.1

34.9

41,093

Harbor
porpoise

0.0

2,381.3

0.3

2.7

2,382

Pilot whales

0.0

634.0

8.0

10.3

635

Risso’s
dolphin

0.0

1,759.8

-

5.4

1,760

Sperm
whale*

0.0

121.4

0.6

2.0

122

Gray seal

0.2

8,330.8

4.3

1.4

8,331

Harbor seal

0.0

432.0

65.8

1.4

432

* Denotes species listed under the Endangered Species Act.
1 – Level A harassment take estimates assumes no implementation of monitoring and mitigation measures
beyond 10-dB attenuation using a Noise Mitigation System, and seasonal restrictions.
2 – Level B harassment take estimates are based on distances to the unweighted 120 dB threshold for
vibratory pile driving and 160 dB threshold for impact pile driving.

Table 36 – Project 2 Scenario 3 (P2S3): Estimated Level A Harassment1 and Level B
Harassment2 Take From Installation of 62 Piled Jacket WTG Foundations and 16
OSP Jacket Pin Piles Assuming 10 dB of Noise Attenuation

Species

Level A
Harassment
Exposure
Modeling
Take
Estimate
P2S3

Blue whale*

N/A

Level B
Harassment
Exposure
Modeling
Take
Estimate
P2S3
N/A

PSO Data
Take
Estimate

Mean Group
Size

-

1.0

Estimated
Level A
Harassment
Take
P2S3

Estimated
Level B
Harassment
Take
P2S3

1

Fin whale*

8.1

113.0

3.4

1.8

113

Humpback
whale

8.7

97.7

32.4

2.0

98

Minke
whale

34.9

491.1

6.4

1.4

492

North
Atlantic
right whale*

3.1

40.0

-

2.4

40

Sei whale*

1.7

18.0

0.9

1.6

19

Atlantic
spotted
dolphin

0.0

74.62

-

29.0

75

Atlantic
white-sided
dolphin

0.0

1,647.5

-

27.9

1,648

Bottlenose
dolphin

0.0

829.5

84.2

12.3

830

Common
dolphin

0.0

20,176.9

735.6

34.9

20,177

Harbor
porpoise

0.0

1,001.1

0.1

2.7

1,002

Long-finned
pilot whale

0.0

195.0

3.7

10.3

195

Risso’s
dolphin

0.0

135.7

-

5.4

136

Sperm
whale*

0.0

35.1

0.3

2.0

36

Gray seal

0.3

992.8

2.0

1.4

993

Harbor seal

0.0

70.2

30.5

1.4

71

* Denotes species listed under the Endangered Species Act.
1 – Level A harassment take estimates assumes no implementation of monitoring and mitigation measures
beyond 10-dB attenuation using a Noise Mitigation System, and seasonal restrictions.
2 – Level B harassment take estimates are based on distances to the unweighted 120 dB threshold for
vibratory pile driving and 160 dB threshold for impact pile driving.

The model-based Level A harassment (PTS) exposure estimates are conservative
in that they assume no mitigation measures other than 10 dB of sound attenuation and
seasonal restrictions. Although the enhanced mitigation and monitoring measures
SouthCoast proposed (see Proposed Mitigation and Proposed Monitoring and
Reporting sections below) are specifically focused on reducing pile-driving impacts on

North Atlantic right whales, other marine mammal species would experience
conservation benefits as well (e.g., extended seasonal restrictions, increased monitoring
effort and larger minimum visibility zone improving detectability and mitigation efficacy,
extended pile-driving delays (24-48 hrs) if a North Atlantic right whale is detected).
When implemented, the additional mitigation measures described in the Proposed
Mitigation section, including soft-start and clearance/shutdown processes, would reduce
the already very low probability of Level A harassment. Additionally, modeling does not
include any avoidance behavior by the animals, yet we know many marine mammals
avoid areas of loud sounds. Thus, it is unlikely that an animal would remain within the
Level A harassment SELcum zone long enough to incur PTS and could potentially redirect
their movements away from the pile installation location in response to the soft-start
procedure. For these reasons, SouthCoast is not requesting Level A harassment (PTS)
take incidental to foundation installation for most marine mammal species, even though
animal movement modeling estimated that a small number of PTS exposures could occur
for multiple species (as shown in tables 32-36). In the case of North Atlantic right
whales, the potential for Level A harassment (PTS) has been determined to be reduced to
a de minimis likelihood due to the enhanced mitigation and monitoring measures, which
include even larger clearance and shutdown zones (see Proposed Mitigation and
Proposed Monitoring and Reporting sections). SouthCoast did not request, and NMFS
is not proposing to authorize, take by Level A harassment of North Atlantic right whales.
However, as a precautionary measure, because the WTG and OSP foundation
installation Level A harassment ER95% distances for fin whales are, in some cases,
substantially larger than for other mysticete whales, Level A harassment take is being
requested for this species. The second largest mysticete Level A harassment ER95%
distance was selected as the clearance/shutdown zone size for baleen whales to avoid
Level A harassment take of other mysticete species. SouthCoast assumed that the large

clearance/shutdown zone size along with the soft-start procedure and potential for animal
aversion to loud sounds would prevent Level A harassment take of other species. In most
installation scenarios, 15-20 percent of the fin whale Level A harassment ER95% zone
extends beyond the planned clearance/shutdown distance for non-NARW baleen whales,
therefore, the requested Level A take for fin whales incidental to foundation installation
is 20 percent of the fin whale Level A exposure estimates produced by the exposure
modeling (Project 1 = 14; Project 2 = 15). This results in a request for 3 Level A
harassment takes for fin whales for both Project 1 and Project 2 (total of 6 across
Projects). Table 37 shows the requested take incidental to foundation installation that is
included in the total take NMFS proposes to authorize.
For Project 1, no single scenario resulted in a greater amount of take for all
species; therefore, the annual Level B harassment take numbers carried forward in table
37 reflect the maximum take estimate for each species between the two possible
foundation installation scenarios (P1S1 and P1S2). Similarly for Project 2, the number of
species-specific Level B harassment takes in table 37 reflects the maximum take estimate
among the three analyzed scenarios (P2S1, P2S2, P2S3) which, in all cases, resulted from
installations of P2S2. However, the 5-year total take incidental to foundation installation
proposed for authorization for a given species (shown in the last two columns in table 37)
is less than the direct sum across Projects 1 and 2 values in the columns to the left. This is
because the total number of takes must be based on a realistic construction scenario
sequence that does not include take estimates resulting from modeling of installation of
more than 149 foundations. For example, the number of estimated sei whale Level B
harassment takes in column 3 of table 37 resulted from modeling installation of Project 1
Scenario 2 (85 WTG foundations) and the number in column 5 resulted from modeling
installation of Project 2 Scenario 2 (73 WTG foundations), representing take incidental to
installation of a number of WTG foundations (158) larger than the maximum in

SouthCoast’s PDE (147). As described previously, some combinations of Project 1 and 2
scenarios are not possible because they would exceed the number of foundation positions
available. However, SouthCoast indicates that the scenario chosen for Project 2 is
dependent on the scenario installed for Project 1, which is uncertain at this time. Given
this uncertainty, SouthCoast considers each of the five installation scenarios (Project 1,
Scenarios 1 or 2; Project 2, Scenarios 1-3) described in table 2 possible. To ensure the
total take proposed for authorization is based on a realistic number of foundations, the 5year total is based on installation of Project 1 Scenario 1 and Project 2 Scenario 2 (146
total foundations). This ensures that the take proposed for authorization for Project 2
represents the maximum possible yearly take among the three scenarios considered for
Project 2 as it is estimated using the largest potential ensonified zone (resulting from
vibratory pile driving) and that sufficient take is requested for the full buildout.
SouthCoast also considers the combination of Project 1 Scenario 2 and Project 2 Scenario
3 (147 total foundations) a realistic construction plan. However, the 5-year take request is
based on Project 1 Scenario 1 combined with Project 2 Scenario 2 because it reflects a
realistic construction plan that results in the greatest number of estimated takes.
Table 37 – Level A Harassment (PTS) and Level B Harassment Take Incidental to
WTG and OSP Foundation Installation Proposed to be Authorized
SouthCoast Requested and NMFS Proposed Take

Species

Project 1 - Maximum
Between Scenarios 1-2
(P1S1 and P1S2)

Project 2 - Maximum
Among Scenarios 1-3
(P2S1, P2S2, and P1S2)

Total Based on Realistic
Combination of Project 1
Scenario 1 and Project 2
Scenario 2

Level A
Harassment

Level B
Harassment

Level A
Harassment

Level B
Harassment

Level A
Harassment

Level B
Harassment

Blue whale*

-

-

-

Fin whale*

39

481

520

Humpback
whale

-

-

-

Minke
whale

-

-

-

1,038

North
Atlantic
right whale*

-

-

-

Sei whale*

-

-

-

Atlantic
spotted
dolphin

-

-

-

Atlantic
white-sided
dolphin

-

-

3,045

-

3,566

Bottlenose
dolphin

-

-

2,342

-

2,610

Common
dolphin

-

8,553

-

41,093

-

48,069

Harbor
porpoise

-

-

2,382

-

2,695

Pilot whales

-

-

-

Risso’s
dolphin

-

-

1,760

-

1,797

Sperm
whale*

-

-

-

Gray seal

-

-

8,331

-

8,451

Harbor seal

-

-

-

* Denotes species listed under the Endangered Species Act.

UXO/MEC Detonation
SouthCoast may detonate up to 5 UXO/MECs within the Lease Area and 5 within
the ECCs (10 UXOs/MECs total) over the 5-year effective period of the proposed rule.
Charge weights of 2.3 kgs (2.2 lbs), 9.1 kgs (20.1 lbs), 45.5 kgs (100 lbs), 227 kgs (500
lbs), and 454 kgs (1,001 lbs), were modeled to determine acoustic ranges to mortality,
gastrointestinal injury, lung injury, PTS, and TTS thresholds. To do this, the source
pressure function used for estimating peak pressure level and impulse metrics was
calculated with an empirical model that approximates the rapid conversion of solid
explosive to gaseous form in a small bubble under high pressure, followed by exponential
pressure decay as that bubble expands (Hannay and Zykov, 2022). This initial empirical

model is only valid close to the source (within tens of meters), so alternative formulas
were used beyond those distances to a point where the sound pressure decay with range
transitions to the spherical spreading model. The SEL thresholds occur at distances of
many water depths in the relatively shallow waters of the Project (Hannay and Zykov,
2022). As a result, the sound field becomes increasingly influenced by the contributions
of sound energy reflected from the sea surface and sea bottom multiples times. To
account for this, propagation modeling was carried out in decidecade frequency bands
using JASCO’s MONM. This model applies a parabolic equation approach for
frequencies below 4 kHz and a Gaussian beam ray trace model at higher frequencies
(Hannay and Zykov, 2022). In SouthCoast project’s location, sound speed profiles
generally change little with depth, so these environments do not have strong seasonal
dependence (see Figure 2 in the SouthCoast Underwater Acoustic Modeling of
UXO/MEC report). The propagation modeling for UXO/MEC detonations was
performed using an average sound speed profile for “September”, which is slightly
downward refracting. Please see the supplementary report for SouthCoast’s ITA
application titled “Underwater Acoustic Modeling of Detonations of Unexploded
Ordnance (UXO/MEC removal) for Mayflower Wind Farm Construction,” found on
NMFS’ website (https://www.fisheries.noaa.gov/action/incidental-take-authorizationSouthCoast-wind-llc-construction-and-operation-SouthCoast-wind) for more technical
details about the modeling methods, assumptions and environmental parameters used as
inputs (Hannay and Zykov, 2022).
The exact type and net explosive weight of UXO/MECs that may be detonated are
not known at this time; however, they are likely to fall into one of the bins identified in
table 38. To capture a range of UXO/MECs, five categories or “bins” of net explosive
weight, established by the U.S. Navy (2017a), were selected for acoustic modeling (table
38).

Table 38 – Navy “Bins” and Corresponding Maximum Charge Weights (Equivalent
TNT) Modeled
Navy Bin Designation

Maximum Equivalent (kg)

Weight (TNT) lbs

E4

2.3

E6

9.1

E8

45.5

E10

500

E12

1,000

These charge weights were modeled at five different locations and associated
depths located within the Lease Area and ECCs. Two sites are located in the Lease Area,
S1 (60 m (196.9 ft)) and S2 (45 m (147.6 ft)). Three sites are located within the ECCs,
one along the western ECC (S3, 30 m) and two along the eastern ECC (S4, 20m (65.6 ft);
S5, 10 m (32.8 ft))). Sites 1 and 2 were deemed to be representative of the Lease Area
and Sites 3-5 were deemed representative of the ECCs where detonations could occur
(see Figure 1 in Hannay and Zykov, 2022). Exact locations for the modeling sites are
shown in Figure 1 of Hannay and Zykov (2022).
All distances to isopleths modeled can be found in Hannay and Zykov (2022). It
is not currently known how easily SouthCoast would be able to identify the size and
charge weights of UXOs/MECs in the field. Therefore, NMFS has proposed to require
SouthCoast to implement mitigation measures assuming the largest E12 charge weight as
a conservative approach. As such, distances to PTS (tables 39 and 40) and TTS
thresholds (tables 41 and 42) for only the 454 kg (1,001 lbs) UXO/MEC are presented, as
this size UXO/MEC has the greatest potential for these impacts and is what is used to
estimate take. NMFS notes that it is extremely unlikely that all 10 of the UXO/MECs
found and requiring detonation for the SouthCoast Project would consist of this 454 kg
(1,001 lbs) charge weight. If SouthCoast is able to reliably demonstrate that they can
easily and accurately identify charge weights in the field, NMFS will consider mitigation

and monitoring zones based on UXO/MEC charge weight for the final rulemaking rather
than assuming the largest charge weight in every situation.
To further reduce impacts to marine mammals, SouthCoast would deploy a NAS
(a DBBC, at minimum) during every detonation event, similar to that described for
foundation installation, with the expectation that their selected system would be able to
achieve 10-dB attenuation. This expectation is based on an assessment of UXO/MEC
clearance activities in European waters as summarized by Bellman and Betke
(2021). NMFS would require SouthCoast to deploy NAS(s) (a dBBC, at minimum)
during all denotations, thus it was deemed appropriate to apply attenuation R95%
distances to determine the size of the ensonified zone for take estimation.
Given the impact zone sizes and the required mitigation and monitoring measures,
neither mortality nor non-auditory injury are considered likely to result from the activity.
NMFS does not expect or propose to authorize any non-auditory injury, serious injury, or
mortality of marine mammals from UXO/MEC detonation. The modeled distances,
assuming 10 dB of sound attenuation, to the mortality threshold for all UXO/MECs sizes
for all animal masses for the ECCs and Lease Area are small (i.e., 28-368 m (91.9 ft1,207.4 ft); see Tables 40-44 in SouthCoast’s supplemental UXO/MEC modeling report;
Hannay and Zykov, 2022), as compared to the distance/area that can be effectively
monitored. The modeled distances to non-auditory injury thresholds range from 67-694 m
(219.8-2,276.9 ft), assuming 10 dB of sound attenuation (see Tables 35-39 in
SouthCoast’s supplemental UXO/MEC modeling report; Hannay and Zykov, 2022).
SouthCoast would be required to conduct extensive monitoring using both PSOs and
PAM operators and clear an area of marine mammals prior to any detonation of
UXOs/MECs. Given that SouthCoast would be employing multiple platforms to visually
monitor marine mammals as well as passive acoustic monitoring, it is reasonable to
assume that marine mammals would be reliably detected within approximately 700 m

(2,296.59 ft) of the UXO/MEC being detonated, the potential for mortality or nonauditory injury is de minimis. SouthCoast did not request, and NMFS is not proposing to
authorize, take by mortality or non-auditory injury. For this reason, we are not presenting
all modeling results here; however, they can be found in SouthCoast’s UXO/MEC
acoustic modeling report (Hannay and Zykov, 2022).
To estimate the maximum ensonified zones that could result from UXO/MEC
detonations, the largest acoustic ranges (R95%; assuming 10-dB attenuation) to PTS and
TTS thresholds for the E12 UXO/MEC charge weight were used as radii to calculate the
area of a circle (pi × r2; where r is the range to the threshold level) for each marine
mammal hearing group. The largest range for the Lease Area from Sites 1 and 2 (S1 and
S2) is shown in tables 39 and 41 and for the ECCs the largest range from Sites 3-5 (S3,
S4, and S5) is shown in tables 40 and 42. These results represent the largest area
potentially ensonified above the PTS and TTS threshold levels from a single detonation
within the SouthCoast ECCs (tables 40 and 42) and Lease Area (tables 39 and 41).
Table 39 – Largest SEL-based R95% PTS-Onset Ranges (in Meters) Sites S1-S2
(Lease Area) Modeled During UXO/MEC Detonation, Assuming 10-dB Sound
Reduction
Marine Mammal
Hearing Group

Representative
Site Used For
Modeling

Distance (m) to PTS Threshold During
E12
(454 kg) detonation
Rmax

R95%

Maximum
Ensonified Zone
(km2)

Low-Frequency
Cetaceans

Site S1

4,490

4,300

58.1

Mid-Frequency
Cetaceans

Site S2

322

0.3

High-frequency
cetaceans

Site S1

9,280

8,610

Phocid pinnipeds
(in water)

Site S1

1,680

1,560

7.6

1 – For each hearing group, a given range (R95% or Rmax) reflects the modeling result for S1 or S2,
whichever value was largest

Table 40 – Largest SEL-based R95% PTS-Onset Ranges (in Meters) Sites S3-S5
(ECCs) Modeled During UXO/MEC Detonation, Assuming 10-dB Sound Reduction
Marine Mammal
Hearing Group

Representative
Site Used For
Modeling

Distance (m) to PTS Threshold During
E12
(454 kg) detonation
Rmax

R95%

Maximum
Ensonified Zone
(km2)

Low-frequency
cetaceans

Site S5

5,830

4,840

73.6

Mid-frequency
cetaceans

Site S5

597

1.1

High-frequency
cetaceans

Site S3

8,190

7,390

Phocid pinnipeds
(in water)

Site S5

2,990

2,600

21.2

1 – For each hearing group, a given range (R95% or Rmax) reflects the modeling result for S3, S4, or S5,
whichever value was largest

Table 41 – Largest SEL-based R95% TTS-Onset Ranges (in Meters) From Sites S1S2 (Lease Area) Modeled During UXO/MEC Detonation, Assuming 10-dB Sound
Reduction
Marine Mammal
Hearing Group

Representative
Site Used For
Modeling

Distance (m) to TTS Threshold During
E12
(454 kg) detonation
Rmax

R95%

Maximum
Ensonified Zone
(km2)

Low-frequency
cetaceans

Site S2

13,200

11,900

Mid-frequency
cetaceans

Site S1

2,820

2,550

20.4

High-frequency
cetaceans

Site S1

15,400

14,100

Phocid pinnipeds
(in water)

Site S2

7,610

6,990

1 – For each hearing group, a given range (R95% or Rmax) reflects the modeling result for S1 or S2,
whichever value was largest

Table 42 – Largest SEL-based R95% TTS-Onset Ranges (In Meters) From Sites S3S5 (ECCs) Modeled During UXO/MEC Detonation, Assuming 10-dB Sound
Reduction
Marine Mammal
Hearing Group

Low-frequency
cetaceans

Representative
Site Used For
Modeling

Sites S4 and S5

Distance (m) to TTS Threshold During
E12
(454 kg) detonation
Rmax

R95%

13,500

11,800

Maximum
Ensonified Zone
(km2)

Mid-frequency
cetaceans

Site S3

2,820

2,480

19.3

High-frequency
cetaceans

Site S4 and S5

15,600

13,700

Phocid pinnipeds
(in water)

Sites S4 and S5

7,820

7,020

1 – For each hearing group, a given range (R95% or Rmax) reflects the modeling result for S3, S4, or S5,
whichever value was largest

To avoid any in situ detonations of UXO/MECs during periods when North
Atlantic right whale densities are highest in and near the ECCs and Lease Area, this
activity would be restricted from December 1 through April 30, annually. Accordingly,
for each species, they selected the highest average monthly density between May and
November and assumed all 10 UXO/MECs would be detonated in that month to
conservatively estimate exposures from UXO/MEC detonation for a given species in any
given year. Given UXO/MECs detonations have the potential to occur anywhere within
the Lease Area and ECCs, a 15-km (9.3-mi) perimeter was applied around the Lease and,
separately, the ECCs to define the area over which densities would be evaluated. As
described above, in the case of blue whales and pilot whales, monthly densities were
unavailable; therefore, annual densities were used instead.
Table 43 provides those densities and the associated months in which the speciesspecific densities are highest for the Lease Area and ECCs.
Table 43 – Maximum Average Monthly Marine Mammal Densities
(Individuals/km2) Within 15 km of the SouthCoast Project ECCs and Lease Area
From May Through November, and the Month in Which the Maximum Density
Occurs
ECCs

Lease Area

Maximum
Average Monthly
Density
(Individual/km2)

Maximum Density
Month

Maximum
Density

Maximum
Average Monthly
Density
(Individual/km2)

Blue whale*

0.0000

Annual

0.0000

Annual

Fin whale*

0.0013

May

0.0047

July

Humpback whale

0.0012

May

0.0035

June

Species

Minke whale

0.0107

May

0.0175

June

North Atlantic
right whale*

0.0022

May

0.0037

May

Sei whale*

0.0007

May

0.0019

May

Atlantic spotted
dolphin

0.0002

September

0.0068

October

Atlantic whitesided dolphin

0.0102

May

0.0380

June

Bottlenose dolphin

0.0042

August

0.0200

August

Common dolphin

0.0335

November

0.3334

September

Harbor porpoise

0.0284

May

0.0720

May

Pilot whales

0.0002

Annual

0.0029

Annual

Risso’s dolphin

0.0004

November

0.0035

September

Sperm whale*

0.0003

August

0.0017

August

Grey seal

0.1051

May

0.0499

May

Harbor seal

0.2362

May

0.1120

May

* Denotes species listed under the Endangered Species Act

Based on the available information, up to five UXO/MEC detonations may be
necessary in the ECCs and up to five in the Lease Area (10 UXO/MEC detonations total).
To estimate take incidental to UXO/MEC detonations in the SouthCoast ECCs, the
maximum ensonified areas based on the largest R95% to Level A harassment (PTS) and
Level B harassment (TTS) thresholds (assuming 10-dB attenuation) from a single
detonation (assuming the largest UXO/MEC charge weight) in the ECC, as shown in
tables 40 and 42, were multiplied by three (the maximum number of UXOs/MECs that
are expected to be detonated in the SouthCoast ECC in Year 1 of construction) and two
(the maximum number of UXOs/MECs that are expected to be detonated in the
SouthCoast ECC in Year 2 of construction). The results were then multiplied by the
marine mammal densities shown in table 43, resulting in the exposures estimates in table
44. The division of five total detonations within the ECCs across the two years was based
on the relative number of foundations to be installed in each year. The same method was

applied using the maximum single detonation areas shown in table 39 and table 41 to
calculate the potential take from UXO/MEC detonations in the Lease area. The resulting
density-based take estimates for all 10 UXO/MEC detonations are summarized in table
44. Table 52 in SouthCoast’s application provides annual take estimates separately for
each of the two years during which UXO/MEC detonations may occur.
As shown below in table 44, the likelihood of marine mammal exposures above
the PTS threshold is low, especially considering the instantaneous nature of the acoustic
signal and the fact that there will be no more than 10 UXO/MECs detonated throughout
the effective period of the authorization. Further, NMFS is proposing mitigation and
monitoring measures intended to minimize the potential for PTS for most marine
mammal species, and the extent and severity of behavioral harassment (TTS), including:
(1) time of year/seasonal restrictions; (2) time of day restrictions; (3) use of PSOs to
visually observe for North Atlantic right whales; (4) use of PAM to acoustically detect
North Atlantic right whales; (5) implementation of clearance zones; (6) use of noise
mitigation technology; and, (7) post-detonation monitoring visual and acoustic
monitoring by PSOs and PAM operators (see Proposed Mitigation and Proposed
Monitoring and Reporting sections below). However, given the relatively large
distances to the high-frequency cetacean Level A harassment (PTS, SELcum) isopleth
applicable to harbor porpoises and the difficulty detecting this species at sea, NMFS is
proposing to authorize 109 Level A harassment takes of harbor porpoise from UXO/MEC
detonations. Similarly, seals are difficult to detect at longer ranges, and although the
distances to the phocid hearing group SEL PTS threshold are not as large as those for
high-frequency cetaceans, it may not be possible to detect all seals within the PTS
threshold distances even with the proposed monitoring measures. Therefore, NMFS is
proposing to authorize 40 Level A harassment takes of gray seals and 4 Level A
harassment takes of harbor seals incidental to UXO/MEC detonation. Although exposure

modeling resulted in small numbers of estimated Level A harassment (PTS) exposures
for large whales (i.e., fin, humpback, minke, North Atlantic, and sei whales), NMFS
anticipates that implementation of the mitigation and monitoring measures described
above will reduce the potential for Level A harassment to discountable amounts.

Table 44 – Level A Harassment (PTS) and Level B Harassment (TTS, Behavior) Estimated Take Incidental to
UXO/MEC Detonations1 Assuming 10-dB Noise Attenuation
Marine
Mammal
Species

Total
Level A
Density
based
Exposure
Estimate
Project 1

Total
Level B
Density
based
Exposure
Estimate
Project 1

Total
Level A
Density
based
Exposure
Estimate
Project 2

Total
Level B
Density
based
Exposure
Estimate
Project 2

PSO Data
Take
Estimate

Mean
Group Size

Requested
Level A
Take
Project 12

Requested
Level B
Take
Project 1

Requested
Level A
Take
Project 22

Requested
Level B
Take
Project 2

Blue
whale*

0.0

0.0

0.0

0.0

-

1.0

1

1

Fin whale*

1.1

12.5

0.7

8.3

0.5

1.8

13

9

Humpback
whale

0.9

9.2

0.6

6.1

4.6

2.0

10

7

Minke
whale

5.5

46.4

3.6

30.9

0.9

1.2

47

31

North
Atlantic
right
whale*

1.1

9.9

0.7

6.6

-

2.4

10

7

Sei whale*

0.5

5.1

0.3

3.4

-

1.6

6

4

Atlantic
spotted
dolphin

0.0

0.8

0.0

0.6

-

29.0

29

29

Atlantic
whitesided
dolphin

0.0

4.5

0.0

3.1

-

27.9

28

28

Bottlenose
dolphin

0.0

2.4

0.0

1.6

11.9

7.8

13

13

Common
dolphin

0.4

39.7

0.3

26.5

103.6

34.9

104

104

Harbor
porpoise

64.9

262.3

43.2

174.8

0.0

2.7

263

175

Pilot
whales

0.0

0.4

0.0

0.2

0.5

8.4

11

11

Risso’s
dolphin

0.0

0.4

0.0

0.2

-

5.4

6

6

Sperm
whale*

0.0

0.2

0.0

0.2

0.0

1.5

2

2

Gray seal

23.9

140.6

15.9

93.8

0.1

1.4

141

94

Harbor
seal

1.5

9.1

1.1

6.1

0.2

1.4

10

7

* Denotes species listed under the Endangered Species Act.
1 – SouthCoast expects up to 10 UXO/MECs will necessitate high-order removal (detonation), and anticipates that 5 of these would be found in the
Lease Area, and 5 would be found in the export cable corridors.
2 – Although UXO/MEC exposure modeling estimated potential Level A harassment (PTS) exposures for mysticete whales, SouthCoast did not request
Level A harassment for these species given the assumption that their proposed monitoring and mitigation measures would prevent this form of take
incidental to UXO/MEC detonations.

HRG Surveys
SouthCoast’s proposed HRG survey activity includes the use of impulsive (i.e.,
boomers and sparkers) and non-impulsive (e.g., CHIRP SBPs) sources (table 45).
Table 45 – Representative HRG Survey Equipment and Operating Frequencies
Equipment Type

Representative Equipment
Model

Operating Frequency (kHz)

Sub-bottom Profiler

Teledyne Benthos Chirp III –
TTV 170

2-7

Sparker

Applied Acoustics Dura-Spark
UHD (400 tips, 800 J)

0.01 - 1.9

Boomer

Applied Acoustics triple plate SBoom (700 J)

0.1 - 5

Authorized takes would be by Level B harassment only in the form of disruption
of behavioral patterns for individual marine mammals resulting from exposure to noise
from certain HRG acoustic sources. Based primarily on the characteristics of the signals
produced by the acoustic sources planned for use, Level A harassment is neither
anticipated, even absent mitigation, nor proposed for authorization. Therefore, the
potential for Level A harassment is not evaluated further. Please see SouthCoast’s
application for details of a quantitative exposure analysis (i.e., calculated distances to
Level A harassment isopleths and Level A harassment exposures). No serious injury or
mortality is anticipated to result from HRG survey activities.
In order to better account for the narrower and directional beams of the sources,
NMFS has developed a tool, specific to HRG surveys, for determining the sound pressure
level (SPLrms) at the 160-dB isopleth for the purposes of estimating the extent of Level B
harassment isopleths associated with HRG survey equipment (NMFS, 2020). This
methodology incorporates frequency-dependent absorption and some directionality to
refine estimated ensonified zones. SouthCoast used NMFS' methodology with additional
modifications to incorporate a seawater absorption formula and account for energy
emitted outside of the primary beam of the source. For sources that operate with different

beamwidths, the maximum beam width was used, and the lowest frequency of the source
was used when calculating the frequency-dependent absorption coefficient.
NMFS considers the data provided by Crocker and Fratantonio (2016) to
represent the best scientific information available on source levels associated with HRG
equipment and therefore, recommends that source levels provided by Crocker and
Fratantonio (2016) be incorporated in the method described above to estimate ranges to
the Level A harassment and Level B harassment isopleths. In cases when the source level
for a specific type of HRG equipment is not provided in Crocker and Fratantonio (2016),
NMFS recommends that either the source levels provided by the manufacturer be used or
in instances where source levels provided by the manufacturer are unavailable or
unreliable, a proxy from Crocker and Fratantonio (2016) be used instead. SouthCoast
utilized the NMFS User Spreadsheet Tool (NMFS, 2018), following these criteria for
selecting the appropriate inputs:
(1) For equipment that was measured in Crocker and Fratantonio (2016), the
reported SL for the most likely operational parameters was selected.
(2) For equipment not measured in Crocker and Fratantonio (2016), the best
available manufacturer specifications were selected. Use of manufacturer specifications
represent the absolute maximum output of any source and do not adequately represent the
operational source. Therefore, they should be considered an overestimate of the sound
propagation range for that equipment.
(3) For equipment that was not measured in Crocker and Fratantonio (2016) and
did not have sufficient manufacturer information, the closest proxy source measured in
Crocker and Fratantonio (2016) was used.
The Teledyne Benthos Chirp III has the highest source level, so it was also
selected as a representative sub-bottom profiling system in table 45. Crocker and
Fratantonio (2016) measured source levels of a device similar to the Teledyne Benthos

Chirp III TTV 170 towfish, the Knudsen 3202 Chirp sub-bottom profiler, at several
different power settings. The highest power settings measured for the Knudsen 3202 were
determined to be applicable to a hull-mounted Teledyne Benthos Chirp III system, while
the lowest power settings were determined to be applicable to the towfish version of the
Teledyne Benthos Chirp III that may be used by SouthCoast. The EdgeTech Chirp 512i
measurements and specifications provided by Crocker and Fratantonio (2016) were used
as a proxy for both the Edgetech 3100 with SB-216 towfish and EdgeTech DW-106,
given its similar operations settings. The EdgeTech Chirp 424 source levels were used as
a proxy for the Knudsen Pinger sub-bottom profiler. The sparker systems that may be
used during the HRG surveys, the Applied Acoustics Dura-Spark and the Geomarine
Geo-Spark, were measured by Crocker and Fratantonio (2016) but not with an energy
setting near 800 Joules (J). A similar alternative system, the SIG ELC 820
sparker,measured with an input voltage of 750 J, was used as a proxy for both the
Applied Acoustics Dura-Spark UHD (400 tips, 800 J) and Geomarine Geo-Spark (400
tips, 800 J), and was conservatively assumed to be an omnidirectional source.
Table 46 identifies all the representative survey equipment that operates below
180 kHz (i.e., at frequencies that are audible and have the potential to disturb marine
mammals) that may be used in support of planned survey activities and are likely to be
detected by marine mammals given the source level, frequency, and beamwidth of the
equipment. This table also provides all operating parameters used to calculate the
distances to threshold for marine mammals.

Table 46 – Summary Of Representative HRG Survey Equipment and Operating Parameters
Equipment
Type

Sub-bottom
Profiler

Sparker4

Boomer

Representative
Model

Operating
Frequency
(kHz)

Source Level
SPLrms (dB)

EdgeTech 3100
with SB-2161
towfish

2 – 16

184

EdgeTech DW1061

1–6

Knudson Pinger2

Teledyne Benthos
CHIRP III - TTV
Source Level0Pulse
Duration (ms)
pk (dB)

Repetition
Rate (Hz)

Beamwidth
(degrees)

Information
Source

9.1

CF

14.4

66

CF

187

2

CF

2–7

204

14.4

CF

Applied Acoustics
Dura-Spark UHD
(400 tips, 800 J)

0.01 – 1.9

213

3.4

Omni

CF

Geomarine GeoSpark (400 tips,
800 J)

0.01 – 1.9

213

3.4

Omni

CF

Applied Acoustics
triple plate SBoom (700 J)

0.1 – 5

211

0.9

61

CF

Note: J = joule; kHz = kilohertz; dB = decibels; SL = source level; UHD = ultra-high definition; rms = root-mean square; µPa = microPascals; re =
referenced to; SPL = sound pressure level; PK = zero-to-peak pressure level; Omni = omnidirectional source; CF = Crocker and Fratantonio (2016)
1 – The EdgeTech Chirp 512i measurements and specifications provided by Crocker and Fratantonio (2016) were used as a proxy for the Edgetech
3100 with SB-216 towfish and EdgeTech DW-106.
2 – The EdgeTech Chirp 424 measurements and specifications provided by Crocker and Fratantonio (2016) were used as a proxy for the Knudsen
Pinger SBP.
3 – The Knudsen 3202 Echosounder measurements and specifications provided by Crocker and Fratantonio (2016) were used as a proxy for the
Teledyne Benthos Chirp III TTV 170.
4 – The SIG ELC 820 Sparker, 5 m source depth, 750 J setting was used as a proxy for both the Applied Acoustics Dura-Spark UHD (400 tips, 800 J)
and Geomarine Geo-Spark (400 tips, 800 J).

Results of modeling using the methodology described above indicated that, of the
HRG equipment planned for use by SouthCoast that has the potential to result in Level B
harassment of marine mammals, sound produced by the Geomarine Geo-Spark and
Applied Acoustics Dura-Spark would propagate furthest to the Level B harassment
isopleth (141 m (462.6 ft); table 47). For the purposes of take estimation, it was
conservatively assumed that sparkers would be the dominant acoustic source for all
survey days (although, again, this may not always be the case). Thus, the range to the
isopleth corresponding to the threshold for Level B harassment for and the boomer and
sparkers (141 m (462.6 ft)) was used as the basis of take calculations for all marine
mammals. This is a conservative approach as the actual sources used on individual survey
days or during a portion of a survey day may produce smaller distances to the Level B
harassment isopleth.
Table 47 – Distances to the Level B Harassment Thresholds for Representative
HRG Sound Source or Comparable Sound Source Category For Each Marine
Mammal Hearing Group
Equipment Type

Representative Model

Level B Harassment Threshold
(m)
All (SPLrms)

Edgetech 3100 with SB-216
towfish

EdgeTech DW-1061

Knudson Pinger2

Teledyn Benthos CHIRP III - TTV
66

Applied Acoustics DuraSpark UHD
400 tips (800 J)

Geomarine Geo-Spark (400 tips,
800 J)

Applied Acoustics triple plate SBoom (700–1,000 J)

Sub-bottom Profiler

Sparker

Boomer

To estimate species densities for the HRG surveys occurring both within the
Lease Area and within the ECCs based on Roberts et al. (2016; 2023), a 5-km (3.11 mi)

perimeter was applied around each area (see Figures 14 and 15 of SouthCoast’s
application) using GIS (ESRI, 2017). Given that HRG surveys could occur at any point
year-round and is likely to be spread out throughout the year, the annual average density
for each species was calculated using average monthly densities from January through
December (table 48).
Table 48 – Annual Average Marine Mammal Densities Along the Export Cable
Corridors and SouthCoast Lease Area1
Marine Mammal Species

ECCs Annual Average Density
(Individual per km2)

Lease Area Annual Average
Density (Individual per km2)

Blue whale*

0.0000

0.0000

Fin whale*

0.0008

0.0022

Humpback whale

0.0007

0.0016

Minke whale

0.0029

0.0057

North Atlantic right whale*

0.0023

0.0027

Sei whale*

0.0003

0.0006

Atlantic spotted dolphin

0.0000

0.0013

Atlantic white-sided dolphin

0.0050

0.0231

Bottlenose dolphin

0.0023

0.0116

Common dolphin

0.0218

0.1503

Harbor porpoise

0.0267

0.0557

Pilot whales

0.0002

0.0029

Risso’s dolphin

0.0002

0.0013

Sperm whale*

0.0001

0.0005

Harbor seal

0.1345

0.0641

Gray seal

0.0599

0.0285

* Denotes species listed under the Endangered Species Act.

The maximum range (141 m (462.6 ft)) to the Level B harassment threshold and
the estimated trackline distance traveled per day by a given survey vessel (i.e., 80 km (50
mi)) were then used to calculate the daily ensonified area or zone of influence (ZOI)
around the survey vessel.

The ZOI is a representation of the maximum extent of the ensonified area around
a HRG sound source over a 24-hr period. The ZOI for each piece of equipment operating
at or below 180 kHz was calculated per the following formula:
ZOI = (Distance/day × 2r) + pi x r2
Where r is the linear distance from the source to the harassment isopleth.
The largest daily ZOI (22.6 km2 (8.7 mi2)), associated with the proposed use of
sparkers, was applied to all planned survey days.
During construction, SouthCoast estimated approximately a length of 4,000 km
(2,485.5 mi) of surveys would occur within the Lease Area and 5,000 km (3,106.8 mi)
would occur within the ECCs. Potential Level B density-based harassment exposures
were estimated by multiplying the average annual density of each species within the
survey area by the daily ZOI. That product was then multiplied by the number of planned
survey days in each sector during the approximately 2-year construction timeframe (62.5
days in the ECCs and 50 days in the Lease Area), and the product was rounded to the
nearest whole number. This assumed a total ensonified area of 1,130 km2 (702.1 mi2) in
the Lease Area and 1,412.5 km2 (877.7 mi2) along the ECCs. The density-based modeled
Level B harassment take for HRG surveys during the construction period assumes
approximately 60 percent (5,400 km) and 40 percent (3,600 km) of track lines would be
surveyed during Year 1 (associated with Project 1) and Year 2 (associated with Project
2), respectively. SouthCoast estimated a conservative number of annual takes by Level B
harassment based on the highest predicted value among the density-based, PSO dataderived, or average group size estimates. These results can be found in table 49.

Table 49 – Estimated Level B Harassment Take Incidental to HRG Surveys During the 2-Year Construction Period
Project 1 Estimated Take

Project 2 Estimated Take

Marine
Mammal
Species

Total
DensityBased Take
Estimate

PSO Data
Take
Estimate

Mean Group
Size

Highest
Annual
Level B
Harassment
Take
Project 1

Highest
Annual
Level B
Harassment
Take
Project 2

Lease Area

ECCs

Lease Area

ECCs

Blue whale*

0.0

0.0

0.0

0.0

0.0

-

1.0

1

Fin whale*

1.2

0.6

1.3

0.6

3.6

5.3

1.8

6

Humpback
whale

0.9

0.5

0.9

0.5

2.8

51.4

2.0

52

Minke
whale

3.2

2.0

3.3

1.7

10.5

10.2

1.4

11

North
Atlantic
right whale*

1.5

1.6

1.5

1.7

6.3

-

2.4

4

Sei whale*

0.3

0.2

0.4

0.2

1.1

1.4

1.6

2

Atlantic
spotted
dolphin

0.7

0.0

0.7

0.0

1.5

-

29.0

29

Atlantic
white-sided
dolphin

12.9

3.5

13.3

3.6

33.2

-

27.9

28

Bottlenose
dolphin

6.5

1.6

6.7

1.7

16.4

133.4

12.3

134

Common
dolphin

83.8

15.2

86.1

15.6

200.8

1165.5

34.9

1,166

1,166

Harbor
porpoise

31.1

18.6

31.9

19.1

100.8

0.2

2.7

52

Pilot whales

1.6

0.1

1.7

0.1

3.6

5.9

8.4

11

Risso’s
dolphin

0.7

0.1

0.8

0.1

1.

-

5.4

6

Sperm
whale*

0.3

0.1

0.3

0.1

0.7

0.4

1.5

2

Gray seal

48.5

127.2

49.8

130.8

355.6

3.1

1.4

181

Harbor seal

3.1

8.3

3.2

8.5

23.1

48.3

1.4

49

* Denotes species listed under the Endangered Species Act.
Note - not applicable

As mentioned previously, HRG surveys would also routinely be carried out
during the period following completion of foundation installations which, for the
purposes of exposure modeling, SouthCoast assumed to be three years. Generally,
SouthCoast followed the same approach as described above for HRG surveys occurring
during the two years of construction activities, modified to account for reduced survey
effort following foundation installation. During the three years when construction is not
occurring, SouthCoast estimates that HRG surveys would cover 2,800 km (1,739.8 mi)
within the Lease Area and 3,200 km (1,988.4 mi) along the ECCs annually. Maintaining
that 80 km (50 mi) are surveyed per day, this amounts to 35 days of survey activity in the
Lease Area and 40 days of survey activity along the ECCs each year or 225 days total for
the three-year timeframe following the two years of construction activities. Similar to the
approach outlined above, density-based take was estimated by multiplying the daily ZOI
by the annual average densities and the number of survey days planned for the ECCs and
SouthCoast Lease Area. Using the same approach described above, SouthCoast estimated
a conservative number of annual takes by Level B harassment based on the highest
exposures predicted by the density-based, PSO based, or average group size-based
estimates. The highest predicted take estimate was multiplied by three to yield the
number of takes that is proposed for authorization, as shown in table 50 below.
Table 50 – Estimate Take, by Level B Harassment, Incidental to HRG Surveys
During the 3 Years When Construction Would Not Occur

Marine
Mammal
Species

Annual Operations
Phase Take by Survey
Area

Annual
Total
DensityBased
Take
Estimate

Annual
PSO Data
Take
Estimate

Mean
Group
Size

Highest
Annual
Level B
Take

Total
Level B
Harassme
nt Take
Over 3
Years of
HRG
Surveys

Lease
Area

ECCs

Blue
whale*

0.0

0.0

0.0

-

1.0

3

Fin
whale*

1.8

0.7

2.5

3.6

1.8

12

Humpback
whale

1.3

0.6

1.9

34.3

2.0

105

Minke
whale

4.5

2.6

7.1

6.8

1.4

24

North
Atlantic
right
whale*

2.1

2.1

4.2

-

2.4

15

Sei
whale*

0.5

0.3

0.7

0.9

1.6

6

Atlantic
spotted
dolphin

1.0

0.0

1.1

-

29.0

87

Atlantic
whitesided
dolphin

18.3

4.5

22.8

-

27.9

84

Bottlenose
dolphin

9.2

2.1

11.3

88.9

12.3

267

Common
dolphin

119.0

19.7

138.7

777.0

34.9

2,334

Harbor
porpoise

44.1

24.2

68.3

0.1

2.7

207

Pilot
whales

2.3

0.1

2.5

3.9

10.3

33

Risso’s
dolphin

1.1

0.1

1.2

-

5.4

18

Sperm
whale*

0.4

0.1

0.5

0.3

2.0

6

Gray seal

68.8

165.1

234.0

2.1

1.4

702

Harbor
seal

4.5

10.7

15.2

32.2

1.4

99

** Denotes species listed under the Endangered Species Act.
Note: - not applicable

Total Proposed Take Across All Activities
The species-specific numbers of annual take by Level A harassment and Level B
harassment NMFS proposes to authorize incidental to all specified activities combined
are provided in table 51. Take estimation assumed pile-driving noise will be attenuated
by 10 dB and, where applicable, implementation of seasonal restrictions and clearance

and shutdown processes to discount the potential for Level A harassment of most species
for which it was estimated. NMFS also presents the 5-year total number of takes
proposed for authorization for each species in table 52.
Table 51 presents the annual take proposed for authorization, based on the
assumption that specific activities would occur in particular years. SouthCoast currently
plans to install all permanent structures (i.e., WTG and OSP foundations) within two of
the five years of the proposed effective period, which includes a single year for Project 1
and a single year for Project 2. However, foundation installations may not begin in the
first year of the effective period of the rule or occur in sequential years, and NMFS
acknowledges that construction schedules may shift. The proposed rule allows for this
flexibility; however, the number of takes for each species in any given year must not
exceed the maximum annual numbers provided in table 53.
In table 51, years 1 and 2 represent the assumed years (for take estimation) in
which SouthCoast would install WTG and OSP foundations. For each species, the Year 1
proposed take includes the highest take estimate between P1S1 and P1S2 for foundation
installation, one year of HRG surveys, and five high-order detonations of the heaviest
charge weight (E12) UXO/MECs (at a rate of one per day for up to five days). The
proposed Level B harassment take for Year 2 is based on P2S2 for foundation
installation, given it resulted in the highest Level B harassment take estimates among
P2S1, P2S2, and P2S3 for all species because it includes vibratory (in addition to impact)
pile driving of monopiles, one year of HRG surveys, and up to five high-order
detonations of the heaviest charge weight (E12) UXO/MECs (also at a rate of one per day
for up to five days). In table 51, take for years 3-5 is incidental to HRG surveys. All
activities with the potential to result in incidental take of marine mammals are expected
to be completed by early 2031.

In making the negligible impact determination, NMFS assesses both the
maximum annual total number of takes (Level A harassment and Level B harassment) of
each marine mammal species or stocks allowable in any one year, which in the case of
this proposed rule is in Year 2, and the total taking of each marine mammal species or
stock allowable during the 5-year effective period of the rule.
NMFS has carefully considered all information and analysis presented by
SouthCoast as well as all other applicable information and, based on the best scientific
information available, concurs that the SouthCoast’s estimates of the types and number of
take for each species and stock are reasonable and, thus, NMFS is proposing to authorize
the number requested.

Table 51 – Level A Harassment and Level B Harassment Takes of Marine Mammals Proposed to be Authorized
Incidental to All Activities During Construction and Development of the SouthCoast Offshore Wind Energy Project.
Year 1
Marine
Mammal
Species

NMFS
Stock
Abundan
ce

Blue
whale*

Year 21

Year 3

Year 4

Year 5

Level A
harassme
nt (Max
annual)

Level B
harassme
nt

Level A
harassme
nt

Level B
harassme
nt (Max
annual)

Level A
harassme
nt

Level B
harassme
nt

Level A
harassme
nt

Level B
harassme
nt

Level A
harassme
nt

Level B
harassme
nt

0

0

0

0

0

Fin
whale*

6,802

58

496

4

4

4

Humpbac
k whale

1,396

99

341

35

35

35

Minke
whale

21,968

255

911

8

8

8

North
Atlantic
right
whale*

0

0

0

0

0

Sei
whale*

6,292

15

48

2

2

2

Atlantic
spotted
dolphin

39,921

87

378

29

29

29

Atlantic
whitesided
dolphin

93,221

784

3,101

28

28

28

Bottlenos
e dolphin3

62,851

451

2,489

89

89

89

Common
dolphin

172,974

9,823

42,363

778

778

778

Harbor
porpoise

95,543

65*

44

2,609

69

69

69

Longfinned
pilot
whales3

39,215

83

657

11

11

11

Risso’s
dolphin

35,215

49

1,772

6

6

6

Sperm
whale*

4,349

17

126

2

2

2

Gray seal

27,300

24*

16

8,606

234

234

234

Harbor
seal

61,336

94

488

33

33

33

* Denotes species listed under the Endangered Species Act.

Table 52 – 5-Year Total Level A Harassment and Level B Harassment Takes of Marine Mammals Proposed to be
Authorized Incidental to all Activities During Construction and Development of the SouthCoast Offshore Wind Energy
Project
5-Year Totals
Marine Mammal Species

NMFS Stock Abundance
Proposed Level A harassment Take

Proposed Level B harassment

Blue whale*

0

Fin whale*

6,802

566

Humpback whale

1,396

541

Minke whale

21,968

1,162

North Atlantic right whale*

0

Sei whale*

6,292

67

Atlantic spotted dolphin

39,921

552

Atlantic white-sided dolphin

93,233

3,762

Bottlenose dolphin

62,851

3,171

Common dolphin

172,974

52,943

Harbor porpoise

95,543

3,442

Long-finned pilot whales

39,215

773

Risso’s dolphin

35,215

1,839

Sperm whale*

4,349

149

Gray seal

27,300

9,835

Harbor seal

61,336

677

* Denotes species listed under the Endangered Species Act.

To inform both the negligible impact analysis and the small numbers
determination, NMFS assesses the maximum number of takes of marine mammals that
could occur within any given year. In this calculation, the maximum number of Level A
harassment takes in any one year is summed with the maximum number of Level B
harassment takes in any one year for each species to yield the highest number of
estimated take that could occur in any year (table 53). Table 53 also depicts the number
of takes relative to the abundance of each stock. The takes enumerated here represent
daily instances of take, not necessarily individual marine mammals taken. One take
represents a day (24-hour period) in which an animal was exposed to noise above the
associated harassment threshold at least once. Some takes represent a brief exposure
above a threshold, while in some cases takes could represent a longer, or repeated,
exposure of one individual animal above a threshold within a 24-hour period. Whether or
not every take assigned to a species represents a different individual depends on the daily
and seasonal movement patterns of the species in the area. For example, activity areas
with continuous activities (all or nearly every day) overlapping known feeding areas
(where animals are known to remain for days or weeks on end) or areas where species
with small home ranges live (e.g., some pinnipeds) are more likely to result in repeated
takes to some individuals. Alternatively, activities far out in the deep ocean or takes to
nomadic species where individuals move over the population’s range without spatial or
temporal consistency represent circumstances where repeat takes of the same individuals
are less likely. In other words, for example, 100 takes could represent 100 individuals
each taken on 1 day within the year, or it could represent 5 individuals each taken on 20
days within the year, or some other combination depending on the activity, whether there
are biologically important areas in the project area, and the daily and seasonal movement
patterns of the species of marine mammals exposed. Wherever there is information to
better contextualize the enumerated takes for a given species is available, it is discussed

in the Preliminary Negligible Impact Analysis and Determination and/or Small
Numbers sections, as appropriate. We recognize that certain activities could shift within
the 5-year effective period of the rule; however, the rule allows for that flexibility and the
takes are not expected to exceed those shown in table 53 in any one year.
Of note, there is significant uncertainty regarding the impacts of turbine
foundation presence and operation on the oceanographic conditions that serve to
aggregate prey species for North Atlantic right whales and - given SouthCoast’s
proximity to Nantucket Shoals - it is possible that the expanded analysis of turbine
presence and/or operation over the life of the project developed for the ESA biological
opinion for the proposed SouthCoast project or additional information received during
the public comment period will necessitate modifications to this analysis. For example, it
is possible that additional information or analysis could result in a determination that
changes in the oceanographic conditions that serve to aggregate North Atlantic right
whale prey may result in impacts that would qualify as a take under the MMPA for North
Atlantic right whales.

Table 53 – Maximum Number of Proposed Takes (Level A Harassment and Level B
Harassment) That Could Occur in Any One Year of the Project Relative to Stock
Population Size (Assuming Each Take is of a Different Individual), and Total Take
for 5-Year Period
Maximum Annual1 Take Proposed to be Authorized
Maximum
Level A
Harassment

Maximum
Level B
Harassment

Maximum
Annual Tak4

Total Percent
Stock Taken
Based on
Maximum
Annual Take

0

3

0.75

Fin whale*

6,802

496

7.34

Humpback
whale

1,396

341

24.4

Minke whale

21,968

911

4.15

North Atlantic
right whale*

0

111

32.8

Sei whale*

6,292

48

0.76

Atlantic
spotted dolphin

39,921

378

0.95

Atlantic whitesided dolphin

93,221

3,101

3,101

3.33

Bottlenose
dolphin,

62,851

2,489

2,489

3.96

Common
dolphin

172,974

42,363

42,363

24.5

Harbor
porpoise

95,543

2,609

2,674

2.80

Long-finned
pilot whales

68,139

657

0.96

Risso’s
dolphin

35,215

1,772

1,772

5.03

Sperm whale*

4,349

126

2.90

Gray seal

27,300

8,606

8,630

31.6

Harbor seal

61,336

488

0.80

Marine
Mammal
Species

NMFS Stock
Abundance

Blue whale*2

*Denotes species listed under the Endangered Species Act.
1 – The percent of stock impacted is the sum of the maximum number of Level A harassment takes in any
year plus the maximum and Level B harassment divided by the stock abundance estimate then multiplied
by 100. The best available stock abundance estimates are derived from the NMFS Stock Assessment
Reports (Hayes et al., 2024). Year 2 has the maximum expected annual take authorized.
2 – The minimum blue whale population is estimated at 402 (Hayes et al., 2024), although the exact value
is not known. NMFS is utilizing this value for our small numbers determination.
3 – NMFS notes that the 2022 North Atlantic Right Whale Annual Report Card (Pettis et al., 2023; n=340)
is the same as the draft 2023 SAR (Hayes et al., 2024). While NMFS acknowledges the estimate found on
the North Atlantic Right Whale Consortium’s website (https://www.narwc.org/report-cards.html) matches,

we have used the value presented in the draft 2023 SARs as the best available science for this final action
(88 FR 5495, January 29, 2024, https://www.fisheries.noaa.gov/national/marine-mammalprotection/marine-mammal-stock-assessment-reports; nmin=340).

Proposed Mitigation
In order to promulgate a rulemaking under section 101(a)(5)(A) of the MMPA,
NMFS must set forth the permissible methods of taking pursuant to the activity and other
means of effecting the least practicable adverse impact on the species or stock and its
habitat, paying particular attention to rookeries, mating grounds, and areas of similar
significance and on the availability of the species or stock for taking for certain
subsistence uses (latter not applicable for this action). NMFS’ regulations require
incidental take authorization applicants to include in their application information about
the availability and feasibility (e.g., economic and technological) of equipment, methods,
and manner of conducting the activity or other means of effecting the least practicable
adverse impact upon the affected species or stocks and their habitat (50 CFR
216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to ensure the least
practicable adverse impact on species or stocks and their habitat, as well as subsistence
uses where applicable, we carefully consider two primary factors:
(1) The manner in which, and the degree to which, the successful implementation
of the measure(s) is expected to reduce impacts to marine mammals, marine mammal
species or stocks, and their habitat. This considers the nature of the potential adverse
impact being mitigated (e.g., likelihood, scope, range). It further considers the likelihood
that the measure will be effective if implemented (i.e., probability of accomplishing the
mitigating result if implemented as planned), the likelihood of effective implementation
(i.e., probability if implemented as planned); and
(2) The practicability of the measures for applicant implementation, which may
consider factors, such as: cost, impact on operations, and, in the case of military readiness

activities, personnel safety, practicality of implementation, and impact on the
effectiveness of the military readiness activity.
The mitigation strategies described below are consistent with those required and
successfully implemented under previous incidental take authorizations issued in
association with in-water construction activities (e.g., soft-start, establishing shutdown
zones). Additional measures have also been incorporated to account for the fact that the
construction activities would occur offshore in an area that includes important marine
mammal habitat. Modeling was performed to estimate Level A harassment and Level B
harassment zone sizes, which were used to inform mitigation measures for the project’s
activities to minimize Level A harassment and Level B harassment to the extent
practicable. Generally speaking, the proposed mitigation measures considered and
required here fall into three categories: temporal (i.e., seasonal and daily) work
restrictions, real-time measures (e.g., clearance, shutdown, and vessel strike avoidance),
and noise attenuation/reduction measures. Temporal work restrictions are designed to
avoid operations when marine mammals are concentrated or engaged in behaviors that
make them more susceptible or make impacts more likely to occur. When temporal
restrictions are in place, both the number and severity of potential takes, as well as both
chronic (longer-term) and acute effects are expected to be reduced. Real-time measures,
such as clearing an area of marine mammals prior to beginning activities or shutting
down an activity if it is occuring, as well as vessel strike avoidance measures, are
intended to reduce the probability and severity of harassment by taking steps in real time
once a higher-risk scenario is identified (e.g., once animals are detected within a
harassment zone). Noise attenuation measures, such as bubble curtains, are intended to
reduce the noise at the source, which reduces both acute impacts as well as the
contribution to aggregate and cumulative noise that may result in long-term chronic
impacts. Soft-starts are another type of noise reduction measure in that animals are

warned of the introduction of sound into their environment at lower levels before higher
noise levels are produced. As a conservative measure applicable to all project activities
and vessels, if a whale is observed or acoustically detected but cannot be confirmed as a
species other than a North Atlantic right whale, SouthCoast must assume that it is a North
Atlantic right whale and take the appropriate mitigation measures.
Below, NMFS briefly describes the required training, coordination, and vessel
strike avoidance measures that apply to all specified activities, and in the following
subsections, we describe the measures that apply specifically to foundation installation,
UXO/MEC detonations, and HRG surveys. Throughout, we also present enhanced
mitigation measures specifically focused on reducing potential impacts of project
activities on North Atlantic right whales given their population status and baseline
conditions, as described in the Description of Marine Mammals in the Specified
Geographic Area section. Details on specific mitigation requirements can be found in
section 217.334 of the proposed regulatory text below in Part 217 – Regulations
Governing The Taking And Importing Of Marine Mammals.
Training and Coordination
NMFS requires all project employees and contractors conducting activities on the
water, including but not limited to, all vessel captains and crew, to be trained in various
marine mammal and regulatory requirements. All relevant personnel, including the
marine mammal monitoring team(s), are required to participate in joint, onboarding
training prior to the beginning of project activities. New relevant personnel (e.g., new
PSOs, construction contractors, relevant crew) who join the project after work
commences must also complete training before they begin work. The training must
include review of, at minimum, marine mammal detection and identification methods,
communication requirements and protocols, all required mitigation measures for each
activity, including vessel strike avoidance measures, to minimize impacts on marine

mammals and the authority of the marine mammal monitoring team(s). The training must
support SouthCoast’s compliance with these regulations and associated LOA if
promulgated and issued. In addition, training would include information and resources
available regarding applicable Federal laws and regulations for protected species.
SouthCoast would provide documentation of training to NMFS prior to the start of inwater activities, and any time new personnel receive training.
Vessel Strike Avoidance Measures
Implementation of the numerous vessel strike avoidance measures included in this
rule is expected to reduce the risk of vessel strike to the degree that vessel strike would be
avoided. While the likelihood of a vessel strike is generally low without these measures,
vessel interaction is one of the most common ways that marine mammals are seriously
injured or killed by human activities. Therefore, enhanced mitigation and monitoring
measures are required to avoid vessel strikes to the extent practicable. While many of
these measures are proactive, intending to avoid the heavy use of vessels during times
when marine mammals of particular concern may be in the area, several are reactive and
occur when Project personnel sight a marine mammal. The vessel strike avoidance
mitigation requirements are described generally here and in detail in the proposed
regulatory text in proposed section 217.334(b)). SouthCoast Wind must comply with all
vessel strike avoidance measures while in the specific geographic region unless a
deviation is necessary to maintain safe maneuvering speed and justified because the
vessel is in an area where oceanographic, hydrographic, and/or meteorological conditions
severely restrict the maneuverability of the vessel; an emergency situation (as defined in
the proposed regulatory text) presents a threat to the health, safety, life of a person; or
when a vessel is actively engaged in emergency rescue or response duties, including
vessel-in distress or environmental crisis response.

While underway, SouthCoast Wind would be required to monitor for marine
mammals and operate vessels in a manner that reduces the potential for vessel strike.
SouthCoast must employ at least one dedicated visual observer (i.e., PSO or trained crew
member) on each transiting vessel, regardless of speed or size. The dedicated visual
observer(s) must maintain a vigilant watch for all marine mammals during transit and be
equipped with suitable monitoring technology (e.g., binoculars, night vision devices)
located at an appropriate vantage point. Any marine mammal detection by the observer
(or anyone else on the vessel) must immediately be communicated to the vessel captain
and any required mitigative action (e.g., reduce speed) must be taken.
All of the project-related vessels would be required to comply with existing
NMFS vessel speed restrictions for North Atlantic right whales and additional speed
restriction measures within this rule. Reducing vessel speed is one of the most effective,
feasible options available to reduce the likelihood of and effects from a vessel strike.
Numerous studies have indicated that slowing the speed of vessels reduces the risk of
lethal vessel collisions, particularly in areas where right whales are abundant and vessel
traffic is common and otherwise traveling at high speeds (Vanderlaan and Taggart, 2007;
Conn and Silber, 2013; Van der Hoop et al., 2014; Martin et al., 2015; Crum et al.,
2019). In summary, all vessels must operate at 10 knots (18.5 km/hr) or less when
traveling from November 1 through April 30; in a SMA, DMA, Slow Zone; or when a
North Atlantic right whale is observed or acoustically detected. Additionally, in the event
that any project-related vessel, regardless of size, observes any large whale (other than a
North Atlantic right whale) within 500 m of an underway vessel or acoustically detected
via the PAM system in the transit corridor, the vessel is required to immediately reduce
speeds to 10 knots (18.5 km/hr) or less and turn away from the animal until the whale can
be confirmed visually beyond 500 m (1,640 ft) of the vessel.

When vessel speed restrictions are not in effect and a vessel is traveling at greater
than 10 knots 10 knots (18.5 km/hr) in addition to the required dedicated visual observer,
SouthCoast would be required to monitor the vessel transit corridor(s) (the path(s) crew
transfer vessels take from port to any work area) in real-time with PAM prior to and
during transits. Should SouthCoast determine it may travel over 10 knots (18.5 km/hr), it
must submit a North Atlantic Right Whale Vessel Strike Avoidance Plan at least 180
days prior to transiting over 10 knots (18.5 km/hr) which fully identifies the
communication protocols and PAM system proposed for use. NMFS must approve the
plan before SouthCoast Wind can operate vessels over 10 knots (18.5 km/hr).
To monitor SouthCoast Wind’s requirements with vessel speed restrictions, all
vessels must be equipped with an AIS and SouthCoast Wind must report all Maritime
Mobile Service Identify (MMSI) numbers to NMFS Office of Protected Resources prior
to initiating in-water activities.
In addition to speed restrictions, all project vessels, regardless of size, must
maintain the following minimum separation distances between vessels and marine
mammals: 500 m (1,640 ft) from North Atlantic right whale; 100 m (328 ft) from sperm
whales and non-North Atlantic right whale baleen whales; and 50 m (164 ft) from all
delphinid cetaceans and pinnipeds (an exception is made for those species that approach
the vessel such as bow-riding dolphins) (table 56). All reasonable steps must be taken to
not violate minimum separation distances. If any of these species are sighted within their
respective minimum separation zone, the underway vessel must turn away from the
animal and shift its engine to neutral (if safe to do so) and the engines must not be
engaged until the animal(s) have been observed to be outside of the vessel’s path and
beyond the respective minimum separation zone.
Seasonal and Daily Restrictions and Foundation Installation Sequencing

Temporal restrictions in places where marine mammals are concentrated, engaged
in biologically important behaviors, and/or present in sensitive life stages are effective
measures for reducing the magnitude and severity of human impacts. NMFS is requiring
temporal work restrictions to minimize the risk of noise exposure to North Atlantic right
whales incidental to certain specified activities to the extent practicable. These temporal
work restrictions are expected to greatly reduce the number of takes of North Atlantic
right whales that would have otherwise occurred should all activities be conducted during
these months. The measures proposed by SouthCoast Wind and those included in this
rule are built around North Atlantic right whale protection; however, they also afford
protection to other marine mammals that are known to use the project area with greater
frequency during months when the restrictions would be in place, including other baleen
whales.
As described in the Description of Marine Mammals in the Specified
Geographic Area section above, North Atlantic right whales may be present in the
specified geographical region throughout the year. As it is not practicable to restrict
activities year-round, NMFS evaluated the best scientific information available to
identify temporal restrictions on foundation pile driving and UXO/MEC detonation that
would ensure that the mitigation measures effect the least practicable adverse impact on
marine mammals. First, NMFS evaluated density data (Roberts et al., 2023) which
demonstrate that from June through October, the densities of North Atlantic right whales
are expected to be an order of magnitude lower than those in November through May
(see table 30 as an example). In addition, the number of DMAs, which are triggered by a
sighting of three or more whales (and suggest foraging behavior may be taking place
(Pace and Clapham, 2001)) also increase November through May. Additionally, the best
available, recently published science indicates North Atlantic right whale presence is
persistent beginning in late October through May (e.g., Davis et al., 2023; van Parijs et

al., 2023) (see Description of Marine Mammals in the Specified Geographic Area).
NMFS and SouthCoast worked together to evaluate these multiple data sources in
consideration of the modeling analysis and proximity to known high density areas of
critical foraging importance in and around Nantucket Shoals to identify practicable
temporal restrictions that affect the least practicable adverse impact on marine mammals.
As described previously, no foundation pile driving would occur October 16 – May 31
inside the NARW EMA or January 1 – May 15 throughout the rest of the Lease Area.
Further, pile driving in December outside of the NARW EMA must not be planned (i.e.,
may only occur due to unforeseen circumstances, following approval by NMFS). Should
NMFS approve December pile driving outside the NARW EMA, SouthCoast would be
required to implement enhanced mitigation and monitoring measures to further reduce
potential impacts to North Atlantic right whales as well as other marine mammal species.
As described previously, the area in and around Nantucket Shoals is important
foraging habitat for many marine mammal species. Therefore, SouthCoast Wind, in
coordination with NMFS, has also proposed (and NMFS is proposing to require) that
SouthCoast Wind sequence the installation of piles strategically. In the NARW EMA,
SouthCoast would install foundations beginning June 1 in the northernmost positions, and
sequence subsequent installations to the south/southwest such that foundation installation
in positions closest to Nantucket Shoals would be completed during the period of lowest
North Atlantic right whale occurrence in that area. NMFS would require SouthCoast to
install the foundations as quickly as possible.
With respect to diel restrictions, SouthCoast Wind has requested to initiate pile
driving during night time. For nighttime pile driving to be approved, SouthCoast would
be required to submit a Nighttime Monitoring Plan for NMFS’ approval that reliably
demonstrates the efficacy of their nighttime monitoring methods and systems and
provides evidence that their systems are capable of detecting marine mammals,

particularly large whales, at distances necessary to ensure that the required mitigation
measures are effective. Should a plan not be approved, SouthCoast Wind would be
restricted to initiating foundation pile driving during daylight hours, no earlier than 1
hour after civil sunrise and no later than 1.5 hours before civil sunset. Pile driving would
be allowed to continue after dark when the installation of the same pile began during
daylight (1.5 hours before civil sunset), when clearance zones were fully visible for at
least 30 minutes or must proceed for human safety or installation feasibility reasons.
There is no schedule for UXO/MEC detonations, as they would be considered on
a case-by-case basis and only after all other means of removal have been exhausted.
However, SouthCoast proposed a seasonal restriction on UXO/MEC detonations from
December 1 through April 30 in both the Lease Area and ECCs to reduce impacts to
North Atlantic right whales during peak occurrence periods. SouthCoast proposes to
detonate no more than one UXO/MEC per 24-hr period. Moreover, detonations may only
occur during daylight hours.
Given the very small harassment zones resulting from HRG surveys and that the
best available science indicates that any harassment from HRG surveys, should a marine
mammal be exposed to sounds produced by the survey equipment (e.g., boomer), would
most likely manifest as minor behavioral harassment only (e.g., potentially some
avoidance of the HRG source), SouthCoast did not propose and NMFS is not proposing
to require any seasonal and daily restrictions for HRG surveys.
More information on activity-specific seasonal and daily restrictions can be found
in the proposed regulatory text in proposed sections 217.334(c)(1) and 217.334(c)(2).
Noise Abatement Systems
SouthCoast Wind would be required to employ noise abatement systems (NAS),
also known as noise attenuation systems, during all foundation installations (i.e., during
both vibratory and impact pile driving) and UXO/MEC detonations to reduce the sound

pressure levels that are transmitted through the water in an effort to reduce ranges to
acoustic thresholds and minimize any acoustic impacts, to the extent practicable,
resulting from these activities.
Two categories of NASs exist: primary and secondary. A primary NAS would be
used to reduce the level of noise produced by foundation installation activities at the
source, typically through adjustments on to the equipment (e.g., hammer strike
parameters). Primary NASs are still evolving and would be considered for use during
mitigation efforts when the NAS has been demonstrated as effective in commercial
projects. However, as primary NASs are not fully effective at eliminating noise, a
secondary NAS would be employed. The secondary NAS is a device or group of devices
that would reduce noise as it was transmitted through the water away from the pile,
typically through a physical barrier that would reflect or absorb sound waves and
therefore, reduce the distance the higher energy sound propagates through the water
column.
Noise abatement systems, such as bubble curtains, are used to decrease the sound
levels radiated from a source. Bubbles create a local impedance change that acts as a
barrier to sound transmission. The size of the bubbles determines their effective
frequency band, with larger bubbles needed for lower frequencies. There are a variety of
bubble curtain systems, confined or unconfined bubbles, and some with encapsulated
bubbles or panels. Attenuation levels also vary by type of system, frequency band, and
location. Small bubble curtains have been measured to reduce sound levels but effective
attenuation is highly dependent on depth of water, current, and configuration and
operation of the curtain (Austin et al., 2016; Koschinski and Lüdemann, 2013). Bubble
curtains vary in terms of the sizes of the bubbles and those with larger bubbles tend to
perform a bit better and more reliably, particularly when deployed with two separate
rings (Bellmann, 2014; Koschinski and Lüdemann, 2013; Nehls et al., 2016).

Encapsulated bubble systems (e.g., Hydro Sound Dampers (HSDs)), can be effective
within their targeted frequency ranges (e.g., 100–800 Hz), and when used in conjunction
with a bubble curtain appear to create the greatest attenuation.
The literature presents a wide array of observed attenuation results for bubble
curtains. The variability in attenuation levels is the result of variation in design as well as
differences in site conditions and difficulty in properly installing and operating in-water
attenuation devices. Dähne et al. (2017) found that single bubble curtains that reduce
sound levels by 7 to 10 dB reduced the overall sound level by approximately 12 dB when
combined as a double bubble curtain for 6-m steel monopiles in the North Sea. During
installation of monopiles (consisting of approximately 8-m in diameter) for more than
150 WTGs in comparable water depths (>25 m) and conditions in Europe indicate that
attenuation of 10 dB is readily achieved (Bellmann, 2019; Bellmann et al., 2020) using
single BBCs for noise attenuation. While there are many assumptions that influence
results of acoustic modeling (e.g., hammer energy, propagation), sound field verification
measurements taken during construction of the South Fork Wind Farm and Vineyard
Wind 1 wind farm indicate that it is reasonable to expect dual attenuation systems to
achieve at least 10 dB sound attenuation.
SouthCoast Wind would be required to use multiple NASs (e.g., double big
bubble curtain (DBBC)) to ensure that measured sound levels do not exceed the levels
modeled assuming a 10-dB sound level reduction for foundation installation and highorder UXO/MEC detonations, as well as implement adjustments to operational protocols
(e.g., reduce hammer energy) to minimize noise levels. A single bubble curtain, alone or
in combination with another NAS device, may not be used for either pile driving or
UXO/MEC detonation as previously received sound field verification (SFV) data has
revealed that this approach is unlikely to attenuate sounds to the degree that measured
distances to harassment thresholds are equal to or smaller than those modeled assuming

10 dB of attenuation. Pursuant to the adaptive management provisions included in the
proposed rule, should the research and development phase of newer attenuation systems
demonstrate effectiveness, SouthCoast Wind may submit data on the efficacy of these
systems and request approval from NMFS to use them during foundation installation and
UXO/MEC detonation activities.
Together, these systems must reduce noise levels to those not exceeding modeled
ranges to Level A harassment and Level B harassment isopleths corresponding to those
modeled assuming 10-dB sound attenuation, pending results of SFV; see the Sound Field
Verification section below and Part 217 – Regulations Governing The Taking And
Importing Of Marine Mammals).
When a double big bubble curtain is used (noting a single bubble curtain is not
allowed), SouthCoast Wind would be required to maintain numerous operational
performance standards. These standards are defined in the proposed regulatory text in
proposed sections 217.334(c)(7) and 217.334(d)(5) and include, but are not limited to, the
requirements that construction contractors must train personnel in the proper balancing of
airflow to the bubble ring and SouthCoast Wind must submit a performance test and
maintenance report to NMFS within 72 hours following the performance test. Corrections
to the attenuation device to meet regulatory requirements must occur prior to use during
foundation installation activities and UXO/MEC detonation. In addition, a full
maintenance check (e.g., manually clearing holes) must occur prior to each pile
installation and UXO/MEC detonation. Should SouthCoast Wind identify that the NAS
systems are not optimized, they would be required to make corrections to the NASs. The
SFV monitoring and reporting requirements (see Proposed Monitoring and Reporting
section) would be the means by which NMFS would determine if modifications to the
NASs would be required. Noise abatement systems are not required during HRG surveys.
A NAS cannot practicably be employed around a moving survey ship, but SouthCoast

Wind would be required to make efforts to minimize source levels by using the lowest
energy settings on equipment that has the potential to result in harassment of marine
mammals (e.g., sparkers, CHIRPs, boomers) and turning off equipment when not actively
surveying. Overall, minimizing the amount and duration of noise in the ocean from any
of the project’s activities through use of all means necessary and practicable will affect
the least practicable adverse impact on marine mammals.
Clearance and Shutdown Zones
NMFS requires the establishment of both clearance and, where technically
feasible, shutdown zones during project activities that have the potential to result in
harassment of marine mammals. The purpose of “clearance” of a particular zone is to
minimize potential instances of auditory injury and more severe behavioral disturbances
by delaying the commencement of an activity if marine mammals are near the activity.
The purpose of a shutdown is to prevent a specific acute impact, such as auditory injury
or severe behavioral disturbance of sensitive species, by halting the activity.
In addition to the zones described above, SouthCoast Wind would be required to
establish a minimum visibility zone during pile driving to ensure that sighting conditions
are sufficient for PSOs to visually detect marine mammals in the areas of highest
potential impact. No minimum visibility zone would be required for UXO/MEC
detonation as the entire visual clearance zone must be clearly visible, given the potential
for lung and GI injury. Within the NARW EMA from August 1 – October 15 and outside
the NARW EMA from May 16 – 31 and December 1 – 31, the minimum visibility zone
sizes would be set equal to the largest Level B harassment zone (unweighted acoustic
ranges to 160 dB re 1 μPa sound pressure level) modeled for each pile type, assuming 10
dB of noise attenuation, rounded up to the nearest 0.1 km (0.06 mi) (7.5 km (4.7 mi)
monopiles; 4.9 km (3.0 mi) pin piles). For installations outside the NARW EMA from
June 1 – November 30, the minimum visibility zone would extend 3.7 km (2.3 mi) from

the pile driving location (table 54). This distance equals the second largest modeled ER

95%

distance to the Level A harassment isopleth (assuming 10 dB attenuation) among all
marine mammals, rounded up to the closest 0.1 km (0.06 mi). The entire minimum
visibility zone must be visible (i.e., not obscured by dark, rain, fog, etc.) for a full 60
minutes immediately prior to commencing foundation pile driving. At no time would
foundation pile driving be initiated when the minimum visibility zones cannot be fully
visually monitored (using appropriate technology), as determined by the Lead PSO on
duty.
All relevant clearance and shutdown zones during project activities would be
monitored by NMFS-approved PSOs and PAM operators (where required). Marine
mammals may be detected visually or, in the case of pile driving and UXO/MEC
detonation, acoustically. SouthCoast must design PAM systems to acoustically detect
North Atlantic right whales to the identified PAM Clearance and Shutdown Zones (table
54). The PAM system must also be able to detect marine mammal vocalizations,
maximize baleen whale detections, and be capable of detecting North Atlantic right
whales to 10 km (6.2 km) and 15 km (9.3 mi), around pin piles and monopiles,
respectively. NMFS recognizes that detectability of each species’ vocalizations will vary
based on vocalization characteristics (e.g., frequency content, source level), acoustic
propagation conditions, and competing noise sources), such that other marine mammal
species (e.g., harbor porpoise) may not be detected at 10 km (6.2 mi) or 15 km (9.3 mi).
and that, during pile driving, detecting marine mammals very close to the pile may be
difficult due to masking from pile driving noise. Acoustic detections of any species
would trigger mitigative action (delays or shutdown), when appropriate.
Before the start of the specified activities (i.e., foundation installation, UXO/MEC
detonation, and HRG surveys), SouthCoast Wind would be required to ensure designated
areas (i.e., clearance zones as provided in tables 54–56) are clear of marine mammals to

minimize the potential for and degree of harassment once the noise-producing activity
begins. Immediately prior to foundation installation and UXO/MEC detonations, PSOs
and PAM operators would be required to begin visually and acoustically monitor
clearance zones for marine mammals for a minimum of 60 minutes. For HRG surveys,
PSOs would be required to monitor these zones for the 30 minutes directly before
commencing use of boomers, sparkers, or CHIRPS. Clearance zones for all activities
(i.e., foundation installation, UXO/MEC detonation, HRG surveys) must be confirmed to
be free of marine mammals for 30-minutes immediately prior to commencing these
activities, else, commencement of the activity must be delayed until the animal(s) has
been observed exiting its respective zone or until an additional time period has elapsed
with no further sightings. A North Atlantic right whale sighting at any distance by PSOs
monitoring pile driving or UXO/MEC activities or acoustically detected within the PAM
clearance zone (for pile driving or UXO/MEC detonations) would trigger a pile driving
or detonation delay.
In some cases, NMFS would require SouthCoast to implement extended pile
driving delays to further reduce potential impacts to North Atlantic right whales utilizing
habitat in the project area. As described previously, North Atlantic right whale
occurrence in the project area remains low in June and July and begins to steadily
increase from August through the fall, reaching maximum occurrence in winter,
particularly in the portion of the lease area closest to Nantucket Shoals. For foundation
installations in the NARW EMA from August 1 – October 15 and throughout the
remainder of the lease area May 16 – 31 and December 1 – 31, annually, if a delay or
shutdown is triggered by a sighting of less than three (i.e., one or two) North Atlantic
right whales or an acoustic detection within the PAM clearance zone (10 km (6.2 mi), pin
piles; 15 km (9.3 mi), monopiles), SouthCoast would be required to delay
commencement or resumption of pile driving 24 hours rather than after 60 minutes pass

without additional sightings of the whale(s). While NMFS is requiring seasonal
restrictions, there is potential for North Atlantic right whales to congregate in the project
area when foundation pile driving activities are occuring. Data demonstrates these
foraging aggregations are sporadic and dependent upon availability of prey, which is
highly variable. For example, in August and October 2022, a total of 9 and 10 North
Atlantic right whales, respectively, were sighted south of Nantucket (southeast of
SouthCoast’s Lease Area) over multiple days. In May 2023, 58 North Atlantic right
whales were sighted southeast of Nantucket, although further to the east of the Lease
Area than the 2022 sightings. The best available science demonstrates that when three or
more North Atlantic right whales are observed, more often than not, they are both
foraging and persisting in an area (Pace and Clapham, 2001). Therefore, for all
foundation installations in the NARW EMA and those outside the NARW EMA from
May 16 – 31 and December 1 – 31, annually, should PSOs sight three or more North
Atlantic right whales in the same areas/times, SouthCoast would be required to delay pile
driving for 48 hours. In both cases (i.e., 24- or 48- hour delay), NMFS would require that
SouthCoast complete a vessel-based survey of the area around the pile driving location
(10-km (6.2-mi) radius, pin piles; 15-km (9.3-mi) radius, monopiles) to ensure North
Atlantic right whales are no longer in the project area before they could commence pile
driving activities for the day.
Once an activity begins, an observation of any marine mammal entering or within
its respective shutdown zone (tables 54-56) would trigger cessation of the activity. In the
case of pile driving, the shutdown requirement may be waived if is not practicable due to
imminent risk of injury or loss of life to an individual, risk of damage to a vessel that
creates risk of injury or loss of life for individuals, or where the lead engineer determines
there is pile refusal or pile instability. Because UXO/MEC detonations are instantaneous,
no shutdown is possible; therefore, there are clearance, but no shutdown, zones for

UXO/MEC detonations (table 55). In situations when shutdown is called for during
foundation pile driving but SouthCoast Wind determines shutdown is not practicable due
to any of the aforementioned emergency reasons, reduced hammer energy must be
implemented when the lead engineer determines it is practicable. Specifically, pile refusal
or pile instability could result in not being able to shut down pile driving immediately.
Pile refusal occurs when a foundation pile encounters significant resistance or difficulty
during the installation process. Pile instability occurs when the pile is unstable and unable
to stay standing if the piling vessel were to “let go.” During these periods of instability,
the lead engineer may determine a shut-down is not feasible because the shutdown
combined with impending weather conditions may require the piling vessel to “let go”
SouthCoast Wind would be required to document and report to NMFS all cases where the
emergency exemption is taken.
After shutdown, foundation installation may be reinitiated once all clearance
zones are clear of marine mammals for the minimum species-specific periods, or, if
required to maintain pile stability, at which time the lowest hammer energy must be used
to maintain stability. As described previously, for shutdowns triggered by observations of
North Atlantic right whales, SouthCoast would not be able to resume pile driving until a
survey of the 10-km (6.2-mi; for 4.5-m pin piles) or 15-km (9.3-mi; for 9/16-m
monopiles) zone surrounding the installation location is completed wherein no additional
sightings occur. Upon re-starting pile driving, soft-start protocols must be followed if pile
driving has ceased for 30 minutes or longer.
SouthCoast proposed equally-sized clearance and shutdown zones for pile
driving, which are generally based on Level A harassment (PTS) ER distances, rounded
95%

up to the nearest 0.1 km (0.06 mi) for PSO clarity. For impact pile driving, the visual
clearance and shutdown zones for large whales, other than North Atlantic right whales,

correspond to the second largest modeled Level A harassment (PTS) exposure range
(ER ) distance, assuming 10 dB attenuation.
95%

Clearance and shutdown zone sizes vary by activity and species groups. All
distances to the perimeter of these zones are the radii from the center of the pile (table
54), UXO/MEC detonation location (table 55), or HRG acoustic source (table 56).
Pursuant to the proposed adaptive management provisions, SouthCoast may request
modification to these zone sizes (except for those that apply to North Atlantic right
whales) as well as the minimum visibility zone, pending results of sound field
verification (see Proposed Monitoring and Reporting section). Any changes to zone
size would require NMFS’ approval.

Table 54 – Clearance, Shutdown, and Minimum Visibility Zones, in meters (m), during Sequential and Concurrent
Installation of 9/16-m Monopiles and 4.5-m Pin Piles in Summer (and Winter)
Installation
Order
Pile type
Method

Sequential
9/16-m
Monopile

4.5-m Pin pile

Impact only

Concurrent

9/16-m Monopile
Impact

Vibe

4.5-m Pin Pile
Impact

1 WTG
Monopile + 4
OSP pin piles

Vibe

North
Atlantic right
whale Visual
Clearance/Sh
utdown Zone

Sighting at any distance from PSOs on pile-driving or dedicated PSO vessels

North
Atlantic right
whale PAM1
Clearance/Sh
utdown Zone1

10,000 m (pin), 15,000 m (monopile)

4 WTG pin
+4 OSP pin
piles

Impact

Other baleen
whales
Clearance/Sh
utdown Zone1

3,500 (3,700)

2,000 (2,300)

3,500

1,900

NAS2

3,500

2,600

Sperm whales
& delphinids
Clearance/Sh
utdown Zone1

NAS

NAS

NAS

NAS

NAS

NAS

NAS

NAS

Harbor
porpoise
Clearance/Sh
utdown Zone1

NAS

NAS

NAS

NAS

NAS

NAS

NAS

NAS

Seals
Clearance/Sh
utdown Zone1

200 (400)

NAS

NAS

NAS

NAS

200

Minimum
Visibility
Zone3

Within NARW EMA Enhanced: 4,800 m (pin) 7,400 m (mono)
Outside NARW EMA: equal to ‘other baleen whales’ impact pile driving clearance zones

1 – The PAM system used during clearance and shutdown must be designed to detect marine mammal vocalizations, maximize baleen whale detections,
and must be capable of detecting North Atlantic right whales at 10 km (6.2 mi) and 15 km (9.3 mi) for pin piles and monopile installations, respectively.
NMFS recognizes that detectability of each species’ vocalizations will vary based on vocalization characteristics (e.g., frequency content, source level),
acoustic propagation conditions, and competing noise sources), such that other marine mammal species (e.g., harbor porpoise) may not be detected at 10
km (6.2 mi) or 15 km (9.3 mi).
2 - NAS = noise attenuation system (e.g., double bubble curtain (DBBC)). This zone size designation indicates that the clearance and shutdown zones,
based on modeled distances to the Level A harassment thresholds, would not extend beyond the DBBC deployment radius around the pile.
3 – PSOs must be able to visually monitor minimum visibility zones. To provide enhanced protection of North Atlantic right whales during foundation
installations in the NARW EMA, SouthCoast proposed monitoring of minimum visibility zones equal to the Level B harassment zones when installing
pin piles (4.8 km (3.0 mi)) and monopiles (7.4 km (4.6 mi)). Outside the NARW EMA, the minimum visibility zone would be equal to SouthCoast’s
clearance/shutdown zones for ‘other baleen whales.’

SouthCoast proposed the following clearance zone sizes for UXO/MEC
detonation, which are dependent on the size (i.e., charge weight) of a UXO/MEC.
SouthCoast has indicated that they will be able to determine the UXO/MEC charge
weight prior to detonation. If the charge weight is determined to be unknown or
uncertain, SouthCoast would implement the largest clearance zone (E12, 454 kg (1,001
lbs)) prior to detonation.
Table 55 – Level B Harassment and Clearance Zones (in Meters (m)) During
UXO/MEC Detonations in the Export Cable Corridor (ECC) and Lease Area (LA),
by Charge Weight and Assuming 10 dB of Sound Attenuation
UXO/MEC Charge
Weights

Low-frequency
cetaceans

Mid-frequency
cetaceans

High-frequency
cetaceans

ECC

ECC

ECC

LA

LA

PAM Clearance
Zone1

E4
(2.3 kg)

E6
(9.1 kg)

E8
(45.5
kg)

E10
(227 kg)

Phocid Pinnipeds

LA

ECC

LA

15 km

Level B
harassm
ent (m)

2,800

2,900

500

6,200

6,200

1,300

1,500

Clearan
ce Zone
(m)

400

50

2,500

2,200

100

Level B
harassm
ent (m)

4,500

4,700

800

7,900

8,000

2,200

2,400

Clearan
ce Zone
(m)

1,500

200

3,500

3,200

200

Level B
harassm
ent (m)

7,300

7,500

1,300

1,300

10,100

10,300

3,900

3,900

Clearan
ce Zone
(m)

2,900

1,800

100

4,900

4,900

1,000

Level B
harassm
ent (m)

10,300

10,500

2,100

2,200

12,600

12,900

6,000

6,000

Clearan
ce Zone
(m)

4,200

3,400

300

6,600

7,200

1,900

1,200

E12
(454 kg)

Level B
harassm
ent (m)

11,800

11,900

2,500

2,600

13,700

14,100

7,100

7,000

Clearan
ce Zone
(m)

4,900

4,300

400

7,400

8,700

2,600

1,600

1 – The PAM system used during clearance must be designed to detect marine mammal vocalizations,
maximize baleen whale detections, and must be capable of detecting North Atlantic right whales at 15 km
(9.3 mi). NMFS recognizes that detectability of each species’ vocalizations will vary based on vocalization
characteristics (e.g., frequency content, source level), acoustic propagation conditions, and competing noise
sources), such that other marine mammal species (e.g., harbor porpoise) may not be detected at 10 km (6.2
mi) or 15 km (9.3 mi).

For an HRG survey clearance process that had begun in conditions with good
visibility, including via the use of night vision equipment (i.e., IR/thermal camera), and
during which the Lead PSO has determined that the clearance zones (table 56) are clear
of marine mammals, survey operations would be allowed to commence (i.e., no delay is
required) despite periods of inclement weather and/or loss of daylight.
Table 56 – Level B Harassment Threshold Ranges and Mitigation Zones During HRG
Surveys
Species

Level B
Harassment Zone
Boomer/Sparker
(m)

Level B
Harassment Zone
CHIRPs (m)

North Atlantic
right whale
Clearance Zone
(m)

Shutdown Zone
(m)

500

100

Other baleen
whales1
Mid-frequency
cetaceans2

48

1001

High-frequency
cetaceans

48

100

Phocid Pinnipeds

48

100

1 – Baleen whales other the the North Atlantic right whale
2 – An exception is noted for bow-riding delphinids of the following genera: Delphinus, Stenella,
Lagenorhynchus, and Tursiops.

For any other in-water construction heavy machinery activities (e.g., trenching,
cable laying, etc.), if a marine mammal is on a path towards or comes within 10 m (32.8

ft) of equipment, SouthCoast Wind would be required to delay or cease operations until
the marine mammal has moved more than 10 m (32.8 ft) on a path away from the
activity to avoid direct interaction with equipment.
Soft-Start and Ramp-Up
The use of a soft-start for impact pile driving or ramp-up for HRG surveys
procedures are employed to provide additional protection to marine mammals by warning
them or providing them with a chance to leave the area prior to the impact hammer or
HRG equipment operating at full capacity. Soft-start typically involves initiating hammer
operation at a reduced energy level, relative to the full operating capacity, followed by a
waiting period. It is difficult to specify a reduction in energy for any given hammer
because of variation across drivers and installation conditions. Typically, NMFS requires
a soft-start procedure of the applicant performing four to six strikes per minute at 10 to 20
percent of the maximum hammer energy, for a minimum of 20 minutes. To allow
maximum flexibility given Project-specific conditions and any number of safety issues,
particularly if pile driving stops before target pile penetration depth is reached, which
may result in pile refusal, general soft-start requirements are incorporated into the
proposed regulatory text at proposed section 217.334(c)(6) but specific soft-start
protocols considering final construction design details, including site-specific soil
properties and other considerations, would be identified in their Pile Driving Monitoring
Plan, which SouthCoast would submit to NMFS for approval prior to begin foundation
installation.
HRG survey operators are required to ramp-up sources when the acoustic sources
are used unless the equipment operates on a binary on/off switch. The ramp-up would
involve starting from the smallest setting to the operating level over a period of
approximately 30 minutes.

Soft-start and ramp-up would be required at the beginning of each day’s activity
and at any time following a cessation of activity of 30 minutes or longer. Prior to softstart or ramp-up beginning, the operator must receive confirmation from the PSO that the
clearance zone is clear of any marine mammals.
Fishery Monitoring Surveys
While the likelihood of SouthCoast Wind’s fishery monitoring surveys impacting
marine mammals is minimal, NMFS is proposing to require SouthCoast Wind to adhere
to gear and vessel mitigation measures to reduce the risk of gear interaction to de minimis
levels. In addition, all crew undertaking the fishery monitoring survey activities would be
required to receive protected species identification training prior to activities occurring
and attend the aforementioned onboarding training. The specific requirements that NMFS
is proposing for the fishery monitoring surveys can be found in the proposed regulatory
text in proposed section 217.334(f).
Based on our evaluation of the mitigation measures, as well as other measures
considered by NMFS, NMFS has preliminarily determined that these measures will
provide the means of affecting the least practicable adverse impact on the affected
species or stocks and their habitat, paying particular attention to rookeries, mating
grounds, and areas of similar significance.
Proposed Monitoring and Reporting
In order to promulgate a rulemaking for an activity, section 101(a)(5)(A) of the
MMPA states that NMFS must set forth requirements pertaining to the monitoring and
reporting of such taking. The MMPA implementing regulations at 50 CFR 216.104
(a)(13) indicate that requests for authorizations must include the suggested means of
accomplishing the necessary monitoring and reporting that will result in increased
knowledge of the species and of the level of taking or impacts on populations of marine
mammals that are expected to be present in the project area. Effective reporting is critical

both to compliance as well as ensuring that the most value is obtained from the required
monitoring.
Monitoring and reporting requirements prescribed by NMFS should contribute to
improved understanding of one or more of the following:
●

Occurrence of marine mammal species or stocks in the area in

which take is anticipated (e.g., presence, abundance, distribution, density);
●

Nature, scope, or context of likely marine mammal exposure to

potential stressors/impacts (i.e., individual or cumulative, acute or chronic),
through better understanding of: (1) action or environment (e.g., source
characterization, propagation, ambient noise); (2) affected species (e.g., life
history, dive patterns); (3) co-occurrence of marine mammal species with the
action; or (4) biological or behavioral context of exposure (e.g., age, calving or
feeding areas);
●

Individual marine mammal responses (i.e., behavioral or

physiological) to acoustic stressors (i.e., acute, chronic, or cumulative), other
stressors, or cumulative impacts from multiple stressors;
●

How anticipated responses to stressors impact either: (1) long-term

fitness and survival of individual marine mammals; or (2) populations, species, or
stocks;
●

Effects on marine mammal habitat (e.g., marine mammal prey

species, acoustic habitat, or other important physical components of marine
mammal habitat); and/or
●

Mitigation and monitoring effectiveness.

Separately, monitoring is also regularly used to support mitigation
implementation (i.e., mitigation monitoring) and monitoring plans typically include

measures that both support mitigation implementation and increase our understanding of
the impacts of the activity on marine mammals.
North Atlantic Right Whale Awareness Monitoring
SouthCoast Wind must use available sources of information on North Atlantic
right whale presence, including, but not limited to, daily monitoring of the Right Whale
Sightings Advisory System, Whale Alert, and monitoring of U.S. Coast Guard very high
frequency (VHF) Channel 16 throughout each day to receive notifications of any
sightings and information associated with any regulatory management actions (e.g.,
establishment of a zone identifying the need to reduce vessel speeds). Maintaining
frequent daily awareness of North Atlantic right whale presence in the area through
SouthCoast’s ongoing visual and passive acoustic monitoring efforts and opportunistic
data sources (outside of SouthCoast Wind’s efforts) and subsequent coordination for
disseminating that information across Project personnel affords increased protection of
North Atlantic right whales by alerting project personnel and the marine mammal
monitoring team to a higher likelihood of encountering a North Atlantic right whale,
potentially increasing the efficacy of mitigation and vessel strike avoidance efforts.
Finally, at least one PAM operator must review available passive acoustic data collected
in the project area within at least the 24 hours, the duration recommended by Davis et al.
(2023), prior to foundation installation or any UXO/MEC detonations to identify
detections of North Atlantic right whales and convey that information to project
personnel (e.g., vessel operators and crew, PSOs).
In addition to utilizing available sources of information on marine mammal
presence as described above, SouthCoast would be required to employ and utilize a
marine mammal visual monitoring team to monitor throughout (i.e., before, during, and
after) all specified activities (i.e., foundation installation, UXO/MEC detonation, and
HRG surveys) consisting of NMFS-approved vessel-based PSOs and trained lookouts on

all vessels, and PAM operator(s) to monitor throughout foundation installation and
UXO/MEC detonation. Visual observations and acoustic detections would be used to
support the activity-specific mitigation measures (e.g., clearance zones). To increase
understanding of the impacts of the activity on marine mammals, PSOs must record all
incidents of marine mammal occurrence at any distance from the piling locations, near
the HRG acoustic sources, and during UXO/MEC detonations. PSOs would document all
behaviors and behavioral changes, in concert with distance from an acoustic source.
Further, SFV during foundation installation and UXO/MEC detonation is required to
ensure compliance and that the potential impacts are within the bounds of that analyzed.
The required monitoring, including PSO and PAM Operator qualifications, is described
below, beginning with PSO measures that are applicable to all the aforementioned
activities and PAM (for specific activities).
Protected Species Observer and PAM Operator Requirements
SouthCoast Wind would be required to employ NMFS-approved PSOs and PAM
operators for certain activities. PSOs are trained professionals who are tasked with
visually monitoring for marine mammals during pile driving, UXO/MEC detonations,
and HRG surveys. The primary purpose of a PSO is to carry out the monitoring, collect
data, and, when appropriate, call for the implementation of mitigation measures. In
addition to visual observations, NMFS would require SouthCoast Wind to conduct realtime acoustic monitoring by PAM operators during foundation pile driving, UXO/MEC
detonation, and vessel transit over 10 knots (18.5 km/hr).
The inclusion of PAM, which would be conducted by NMFS-approved PAM
operators utilizing standardized measurement, processing, reporting, and metadata
methods and metrics for offshore wind, combined with visual data collection, is a
valuable way to provide the most accurate record of species presence as possible and,
together, these two monitoring methods are well understood to provide best results when

combined together (e.g., Barlow and Taylor, 2005; Clark et al., 2010; Gerrodette et al.,
2011; Van Parijs et al., 2021). Acoustic monitoring (in addition to visual monitoring)
increases the likelihood of detecting marine mammals, if they are vocalizing, within the
shutdown and clearance zones of project activities, which when applied in combination
of required shutdowns helps to further reduce the risk of marine mammals being exposed
to sound levels that could otherwise result in acoustic injury or more intense behavioral
harassment. The exact configuration and number of PAM systems depends on the size of
the zone(s) being monitored, the amount of noise expected in the area, and the
characteristics of the signals being monitored.
The exact configuration and number of PAM systems depends on the size of the
zone(s) being monitored, the amount of noise expected in the area, and the characteristics
of the signals being monitored. More closely-spaced hydrophones would allow for more
directionality and range to the vocalizing marine mammals. Larger baleen cetacean
species (i.e., mysticetes), which produce loud and lower-frequency vocalizations, may be
able to be heard with fewer hydrophones spaced at greater distances. However, detection
of smaller cetaceans (e.g., mid-frequency delphinids; odontocetes) may necessitate more
hydrophones and to be spaced closer together given the shorter range of the shorter, midfrequency acoustic signals (e.g., whistles and echolocation clicks). As there are no
“perfect fit” single-optimal-array configurations, these set-ups would need to be
considered on a case-by-case basis.
NMFS does not formally administer any PSO or PAM operator training programs
or endorse specific providers but would approve PSOs and PAM operators that have
successfully completed courses that meet the curriculum and training requirements
referenced below and/or demonstrate experience. PSOs would be allowed to act as PAM
operators or PSOs (but not simultaneously) as long as they demonstrate that their training
and experience are sufficient to perform each task.

NMFS would provide PSO and PAM operator approval, if the candidate is
qualified, to ensure that PSOs and PAM operators have the necessary training and/or
experience to carry out their duties competently. NMFS may approve PSOs and PAM
operators as conditional or unconditional. A conditionally-approved PSO may be one
who has completed training in the last 5 years but has not yet attained the requisite field
experience. An unconditionally approved PSO is one who has completed training within
the last 5 years (or completed training earlier but has demonstrated recent experience
acting as a PSO) and attained the necessary experience (i.e., demonstrate experience with
monitoring for marine mammals at clearance and shutdown zone sizes similar to those
produced during the respective activity). The specific requirements for conditional and
unconditional approval can be found in the proposed regulatory text in proposed section
217.335(a)(7). PSOs and PAM operators for pile driving and UXO/MEC detonation must
be unconditionally approved. PSOs for HRG surveys may be conditionally or
unconditionally approved; however, conditionally-approved PSOs must be paired with an
unconditional-approved PSO to ensure that the quality of marine mammal observations
and data recording is kept consistent.
At least one PSO and PAM operator per platform must be designated as a Lead.
To qualify as a Lead PSO or PAM operator, the person must be unconditionally approved
and demonstrate that they have a minimum of 90 days of at-sea experience monitoring
marine mammals in the specific role, with the conclusion of the most recent relevant
experience not more than 18 months previous to deployment. The person must also have
experience specifically monitoring baleen whale species;
SouthCoast Wind must submit a list of previously approved PSOs and PAM
operators to NMFS Office of Protected Resources for review and confirmation of their
approval for specific roles at least 30 days prior to commencement of the activities
requiring PSOs and PAM operators or 15 days prior to when new, previously approved

PSOs and PAM operators are required after activities have commenced. For prospective
PSOs and PAM operators not previously approved or for PSOs and PAM operators
whose approval is not current, SouthCoast Wind must submit resumes for approval to
NMFS at least 60 days prior to PSO and PAM operator use. Resumes must include
information related to roles for which approval is being sought, relevant education,
experience, and training, including dates, duration, location, and description of prior PSO
or PAM operator experience. Resumes must be accompanied by relevant documentation
of successful completion of necessary training.
The number of PSOs and PAM operators that would be required to actively
observe for the presence of marine mammals are specific to each activity, as are the types
of equipment required (e.g., big eyes on the pile driving vessel; acoustic buoys) to
increase marine mammal detection capabilities. A minimum of three on-duty PSOs per
platform (e.g., pile driving vessel, dedicated PSO vessel) would conduct monitoring
before, during, and after foundation installations and UXO/MEC detonations. A
minimum number of PAM operators would be required to actively monitor for marine
mammal acoustic detections for these activities; this number would be based on the PAM
systems and specified in the PAM Plan SouthCoast would submit for NMFS approval
prior to the start of in-water activities. At least one PSO must be on-duty during HRG
surveys conducted during daylight hours; and at least two PSOs must be on-duty during
HRG surveys conducted during nighttime. NMFS would not require PAM or PAM
operators during HRG surveys.
The number of platforms from which the required number of PSOs would conduct
monitoring depends on the activity and timeframe. Within the NARW EMA from June 1
– August 15 and outside the NARW EMA June 1 - November 30, SouthCoast would
conduct monitoring before, during, and after foundation installation from three dedicated
PSO monitoring vessels, in addition to the pile driving platform. Within the NARW

EMA from August 16 – October 15 and outside the NARW EMA May 16 – May 31 and
December 1 – 31 (if NMFS approved SouthCoast’s request for allowance to install
foundations in December), PSOs would monitor from four dedicated PSO vessels and the
pile driving vessel (i.e., five platforms total). The number of monitoring platforms
required for UXO/MEC detonations depends on the charge weight. For detonation of
lower charge weight (E4-E8) UXO/MECs, SouthCoast would conduct monitoring from
the main activity platform and a dedicated PSO monitoring platform. If, after attempting
all methods of UXO/MEC disposal, SouthCoast must detonate a heavier charge weight
UXO/MEC (i.e., E10 or E12) that is predicted to result in a larger ensonified zone (i.e.,
>5 km), additional monitoring platforms (i.e., vessel, plane) would be required. During
HRG surveys, PSOs would conduct monitoring from the survey vessels. In addition to
monitoring duties, PSOs and PAM operators are responsible for data collection. The data
collected by PSO and PAM operators and subsequent analysis provide the necessary
information to inform an estimate of the number of take that occurred during the project,
better understand the impacts of the project on marine mammals, address the
effectiveness of monitoring and mitigation measures, and to adaptively manage activities
and mitigation in the future. Data reported includes information on marine mammal
sightings, activity occurring at time of sighting, monitoring conditions, and if mitigative
actions were taken. Specific data collection requirements are contained within the
regulations at the end of this rulemaking.
SouthCoast Wind would be required to submit Pile Driving and UXO/MEC
Detonation Marine Mammal Monitoring Plans and a PAM Plan to NMFS 180 days in
advance of foundation installation and UXO/MEC detonation. The Plans must include
details regarding PSO and PAM monitoring protocols and equipment proposed for use, as
described in the draft LOA available at https://www.fisheries.noaa.gov/action/incidentaltake-authorization-southcoast-wind-llc-construction-southcoast-wind-offshore-wind.

More specifically, the PAM Plan must, among other things, include a description of all
proposed PAM equipment, address how the proposed passive acoustic monitoring must
follow standardized measurement, processing methods, reporting metrics, and metadata
standards for offshore wind as described in NOAA and BOEM Minimum
Recommendations for Use of Passive Acoustic Listening Systems in Offshore Wind
Energy Development Monitoring and Mitigation Programs (Van Parijs et al., 2021).
NMFS must approve the Plans prior to foundation installation activities or UXO/MEC
detonation commencing.
Sound Field Verification (SFV)
SouthCoast would be required to conduct SFV measurements during all
foundation installations and all UXO/MEC detonations. At minimum, the first three
monopile foundations and four pin piles must be monitored with Thorough SFV (TSFV), which requires, at minimum, measurements at four locations along one transect
from the pile with each recorder equipped with two hydrophones as well as an additional
recorder at a 90 degrees from the transect (total of 10 hydrophones). For example,
SouthCoast would deploy acoustic recorders at positions 750 m (2,460.6 ft), 1500 m
(4,921.3 ft)), 3000 m (9,842.5 ft), and 10,000 m (32,808.4 ft) in a single linear array due
south and another acoustic recorder due east of the foundation installation location. SFV
protocols for impact pile driving, can be found in ISO 18406 Underwater acoustics —
Measurement of radiated underwater sound from percussive pile driving (2017). T-SFV
measurements must continue until at least three consecutive piles demonstrate distances
to thresholds are at or below those modeled assuming 10 dB of attenuation. Subsequent
T-SFV measurements are also required should larger piles be installed or additional piles
be driven that are anticipated to produce longer distances to harassment isopleths than
those previously measured (e.g., higher hammer energy, greater number of strikes, etc.).
The required reporting metrics associated with T-SFV can be found in the draft LOA.

The requirements are extensive to ensure monitoring is conducted appropriately and the
reporting (i.e., communicating monitoring results to NMFS) is frequent to ensure
SouthCoast is making any necessary adjustments quickly (e.g., ensure bubble curtain
hose maintenance, check bubble curtain air pressure supply, add additional sound
attenuation) to ensure impacts to marine mammals are not above those considered in this
analysis. SouthCoast would be required to conduct abbreviated SFV (A-SFV) on all piles
for which T-SFV is not conducted; the reporting requirements and frequency of reporting
can be found in the proposed regulatory text at proposed section 217.334(c)(20).
SouthCoastWind must also conduct SFV during operations to better understand the sound
fields and potential impacts on marine mammals associated with turbine operations.
Reporting
Prior to any construction activities occurring, SouthCoast would be required to
provide a report to NMFS Office of Protected Resources that demonstrates that all
SouthCoast personnel, including the vessel crews, vessel captains, PSOs, and PAM
operators have completed all required trainings.
NMFS would require standardized and frequent reporting from SouthCoast Wind
during the life of the regulations and LOA. All data collected relating to the Project
would be recorded using industry-standard software (e.g., Mysticetus or a similar
software) installed on field laptops and/or tablets. SouthCoast Wind is required to submit
weekly, monthly, annual, and situational, and final reports. The specifics of what we
require to be reported can be found in the proposed regulatory text at proposed section
217.335(c).
Weekly Report - During foundation installation activities, SouthCoast would be
required to compile and submit weekly marine mammal monitoring reports for
foundation installation pile driving to NMFS Office of Protected Resources that
document the daily start and stop of all pile-driving activities, the start and stop of

associated observation periods by PSOs, details on the deployment of PSOs, a record of
all detections of marine mammals (acoustic and visual), any mitigation actions (or if
mitigation actions could not be taken, provide reasons why), and details on the noise
abatement system(s) (e.g., system type, distance deployed from the pile, bubble rate,
etc.), and A-SFV results. Weekly reports will be due on Wednesday for the previous
week (Sunday to Saturday). The weekly reports are also required to identify which
turbines become operational and when (a map must be provided). Once all foundation
pile installation is complete, weekly reports would no longer be required.
Monthly Report – SouthCoast would be required to compile and submit monthly
reports to NMFS Office of Protected Resources that include a summary of all information
in the weekly reports, including project activities carried out in the previous month,
vessel transits (number, type of vessel, and route), number of piles installed, all
detections of marine mammals, and any mitigative actions taken. Monthly reports would
be due on the 15th of the month for the previous month. The monthly report would also
identify which turbines become operational and when, and a map must be provided. Once
all foundation pile installation is complete, monthly reports would no longer be required.
Annual Reporting – SouthCoast is required to submit an annual marine mammal
monitoring (including visual and acoustic observations of marine mammals) report to
NMFS Office of Protected Resources by March 31st, annually, describing in detail all of
the information required in the monitoring section above for the previous calendar year.
A final annual report must be prepared and submitted within 30 calendar days following
receipt of any NMFS comments on the draft report.
Final Reporting – SouthCoast must submit its draft 5-year report(s) to NMFS
Office of Protected Resources. The report must contain, but is not limited to, a
description of activities conducted (including GIS files where relevant), and all visual and
acoustic monitoring, including all SFV and monitoring effectiveness, conducted under

the LOA within 90 calendar days of the completion of activities occurring under the
LOA. A final 5-year report must be prepared and submitted within 60 calendar days
following receipt of any NMFS comments on the draft report.
Situational Reporting - Specific situations encountered during the development of
the Project requires immediate reporting. For instance, if a North Atlantic right whale is
observed at any time by PSOs or project personnel, the sighting must be immediately (if
not feasible, as soon as possible and no longer than 24 hours after the sighting) reported
to NMFS. If a North Atlantic right whale is acoustically detected at any time via a
project-related PAM system, the detection must be reported as soon as possible and no
longer than 24 hours after the detection to NMFS via the 24-hour North Atlantic right
whale Detection Template (https://www.fisheries.noaa.gov/resource/document/passiveacoustic-reporting-system-templates). Calling the hotline is not necessary when reporting
PAM detections via the template.
If a sighting of a stranded, entangled, injured, or dead marine mammal occurs, the
sighting would be reported to NMFS Office of Protected Resources, the NMFS Greater
Atlantic Stranding Coordinator for the New England/Mid-Atlantic area (866-755-6622),
and the U.S. Coast Guard within 24 hours. If the injury or death was caused by a project
activity, SouthCoast Wind must immediately cease all activities until NMFS Office of
Protected Resources is able to review the circumstances of the incident and determine
what, if any, additional measures are appropriate to ensure compliance with the terms of
the LOA. NMFS Office of Protected Resources may impose additional measures to
minimize the likelihood of further prohibited take and ensure MMPA compliance.
SouthCoast may not resume their activities until notified by NMFS Office of Protected
Resources.
In the event of a vessel strike of a marine mammal by any vessel associated with
the Project, SouthCoast Wind must immediately report the strike incident. If the strike

occurs in the Greater Atlantic Region (Maine to Virginia), SouthCoast must call the
NMFS Greater Atlantic Stranding Hotline. Separately, SouthCoast must also and
immediately report the incident to NMFS Office of Protected Resources and GARFO.
SouthCoast must immediately cease all on-water activities until NMFS Office of
Protected Resources is able to review the circumstances of the incident and determine
what, if any, additional measures are appropriate to ensure compliance with the terms of
the LOA. NMFS Office of Protected Resources may impose additional measures to
minimize the likelihood of further prohibited take and ensure MMPA compliance.
SouthCoast Wind may not resume their activities until notified by NMFS.
In the event of any lost gear associated with the fishery surveys, SouthCoast must
report to the GARFO as soon as possible or within 24 hours of the documented time of
missing or lost gear. This report must include information on any markings on the gear
and any efforts undertaken or planned to recover the gear.
The specifics of what NMFS Office of Protected Resources proposes to require to
be reported are included in the draft LOA..
Sound Field Verification - SouthCoast is required to submit interim T-SFV
reports after each foundation installation and UXO/MEC detonation as soon as possible
but no later than 48 hours after monitoring of each activity is complete. Reports for ASFV must be included in the weekly monitoring reports. The final SFV report (including
both A-SFV and T-SFV results) for all foundation installations and UXO/MEC
detonations would be required within 90 days following completion of sound field
verification monitoring.
Adaptive Management
The regulations governing the take of marine mammals incidental to SouthCoast’s
construction activities contain an adaptive management component. Our understanding of
the effects of offshore wind construction activities (e.g., acoustic and explosive stressors)

on marine mammals continues to evolve, which makes the inclusion of an adaptive
management component both valuable and necessary within the context of 5-year
regulations.
The monitoring and reporting requirements in this proposed rule will provide
NMFS with information that helps us to better understand the impacts of the project’s
activities on marine mammals and informs our consideration of whether any changes to
mitigation and monitoring are appropriate. The use of adaptive management allows
NMFS to consider new information and modify mitigation, monitoring, or reporting
requirements, as appropriate, with input from SouthCoast regarding practicability, if such
modifications will have a reasonable likelihood of more effectively accomplishing the
goals of the measures.
The following are some of the possible sources of new information to be
considered through the adaptive management process: (1) results from monitoring
reports, including the weekly, monthly, situational, and annual reports required; (2)
results from research on marine mammals, noise impacts, or other related topics; and (3)
any information that reveals that marine mammals may have been taken in a manner,
extent, or number not authorized by these regulations or subsequent LOA. Adaptive
management decisions may be made at any time, as new information warrants it. NMFS
may consult with SouthCoast Wind regarding the practicability of the modifications.
Preliminary Negligible Impact Analysis and Determination
NMFS has defined negligible impact as an impact resulting from the specified
activity that cannot be reasonably expected to, and is not reasonably likely to, adversely
affect the species or stock through effects on annual rates of recruitment or survival (50
CFR 216.103). A negligible impact finding is based on the lack of likely adverse effects
on annual rates of recruitment or survival (i.e., population-level effects). An estimate of
the number of takes alone is not enough information on which to base an impact

determination. In addition to considering estimates of the number of marine mammals
that might be “taken” by mortality, serious injury, Level A harassment and Level B
harassment, we consider other factors, such as the likely nature of any behavioral
responses (e.g., intensity, duration), the context of any such responses (e.g., critical
reproductive time or location, migration) as well as effects on habitat and the likely
effectiveness of mitigation. We also assess the number, intensity, and context of
estimated takes by evaluating this information relative to population status. Consistent
with the 1989 preamble for NMFS’ implementing regulations (54 FR 40338, September
29, 1989), the impacts from other past and ongoing anthropogenic activities are
incorporated into this analysis via their impacts on the environmental baseline (e.g., as
reflected in the regulatory status of the species, population size and growth rate where
known, ongoing sources of human-caused mortality, or ambient noise levels).
In the Estimated Take section, we estimated the maximum number of takes, by
Level A harassment and Level B harassment, of marine mammal species and stocks that
could occur incidental to SouthCoast’s specified activities. The impact on the affected
species and stock that any given take may have is dependent on many case-specific
factors that need to be considered in the negligible impact analysis (e.g., the context of
behavioral exposures such as duration or intensity of a disturbance, the health of
impacted animals, the status of a species that incurs fitness-level impacts to individuals,
etc.). In this proposed rule, we evaluate the likely impacts of the enumerated harassment
takes that are proposed for authorization, in consideration of the context in which the
predicted takes would occur. We also collectively evaluate this information as well as
other more taxa-specific information and mitigation measure effectiveness in groupspecific discussions that support our preliminary negligible impact determinations for
each stock. No serious injury or mortality is expected or proposed for authorization for
any species or stock.

The Description of the Specified Activities section describes SouthCoast’s
specified activities that may result in the take of marine mammals and an estimated
schedule for conducting those activities. SouthCoast has provided a realistic construction
schedule, although we recognize schedules may shift for a variety of reasons (e.g.,
weather or supply delays). For each species, the maximum number of annual takes
proposed for authorization is based on the pile driving scenario for each year (table X)
that resulted in the highest number of Level B harassment takes for a given species. The
5-year total number of takes proposed for authorization is based on installation of Project
1 Scenario 1 in a single year and Project 2 Scenario 2 in a single year. The total number
of authorized takes would not exceed the maximum annual totals in any given year or the
5-year total take specified in tables 53 and 52, respectively.
We base our analysis and preliminary negligible impact determination on the
maximum number of takes that are proposed for authorization in any given year and the
total takes proposed for authorization across the 5-year effective period of these
regulations, if issued, as well as extensive qualitative consideration of other contextual
factors that influence the severity and nature of impacts on affected individuals and the
number and context of the individuals affected. As stated before, the number of takes,
both maximum annual and 5-year totals, alone are only a part of the analysis.
To avoid repetition, we provide some general analysis in this Negligible Impact
Analysis and Determination section that applies to all the species listed in table 5, given
that some of the anticipated effects of SouthCoast Wind’s specified activities on marine
mammals are expected to be relatively similar in nature. Then, we subdivide into more
detailed discussions for mysticetes, odontocetes, and pinnipeds, which have broad life
history traits that support an overarching discussion of some factors considered within the
analysis for those groups (e.g., habitat-use patterns, high-level differences in feeding
strategies).

Last, we provide a preliminary negligible impact determination for each species
or stock, providing information relevant to our analysis, where appropriate. Organizing
our analysis by grouping species or stocks that share common traits or that would respond
similarly to effects of SouthCoast’s activities and then providing species- or stockspecific information allows us to avoid duplication while ensuring that we have analyzed
the effects of the specified activities on each affected species or stock. It is important to
note that for all species or stocks, the majority of the impacts are associated with WTG
and OSP foundation installation, which would occur over 2 years per SouthCoast’s
schedule (tables 19-23). The maximum annual take for each species or stock would occur
during construction of Project 2. The number of takes proposed for authorization by
NMFS in other years would be notably less.
As described previously, no serious injury or mortality is anticipated or proposed
for authorization. Non-auditory injury (e.g., lung injury or gastrointestinal injury from
UXO/MEC detonation) is also not anticipated due to the proposed mitigation measures
and would not be authorized in any LOA issued under this rule. Any Level A harassment
authorized would be in the form of auditory injury (i.e., PTS).
Behavioral Disturbance
In general, NMFS anticipates that impacts on an individual that has been harassed
are likely to be more intense when exposed to higher received levels and for a longer
duration (though this is not a strictly linear relationship for behavioral effects across
species, individuals, or circumstances) and less severe impacts result when exposed to
lower received levels and for a brief duration. However, there is also growing evidence of
the importance of contextual factors, such as distance from a source in predicting marine
mammal behavioral response to sound—i.e., sounds of a similar level emanating from a
more distant source have been shown to be less likely to evoke a response of equal
magnitude (e.g., DeRuiter and Doukara, 2012; Falcone et al., 2017). As described in the

Potential Effects to Marine Mammals and their Habitat section, the intensity and
duration of any impact resulting from exposure to SouthCoast’s activities is dependent
upon a number of contextual factors including, but not limited to, sound source
frequencies, whether the sound source is stationary or moving towards the animal,
hearing ranges of marine mammals, behavioral state at time of exposure, status of
individual exposed (e.g., reproductive status, age class, health) and an individual’s
experience with similar sound sources. Southall et al. (2021), Ellison et al. (2012), and
Moore and Barlow (2013), among others, emphasize the importance of context (e.g.,
behavioral state of the animals, distance from the sound source) in evaluating behavioral
responses of marine mammals to acoustic sources. Harassment of marine mammals may
result in behavioral modifications (e.g., avoidance, temporary cessation of foraging or
communicating, changes in respiration or group dynamics, masking) or may result in
auditory impacts such as hearing loss. In addition, some of the lower level physiological
stress responses (e.g., change in respiration, change in heart rate) discussed previously
would likely co-occur with the behavioral modifications, although these physiological
responses are more difficult to detect and fewer data exist relating these responses to
specific received levels of sound. Level B harassment takes, then, may have a stressrelated physiological component as well; however, we would not expect SouthCoast’s
activities to produce conditions of long-term and continuous exposure to noise leading to
long-term physiological stress responses in marine mammals that could affect
reproduction or survival.
In the range of exposure intensities that might result in Level B harassment
(which by nature of the way it is modeled/counted, occurs within one day), the less
severe end might include exposure to comparatively lower levels of a sound, at a greater
distance from the animal, for a few or several minutes. A less severe exposure of this
nature could result in a behavioral response such as avoiding a small area that an animal

would otherwise have chosen to move through or feed in for some number of time, or
breaking off one or a few feeding bouts. More severe effects could occur if an animal
receives comparatively higher levels at very close distances, is exposed continuously to
one source for a longer time, or is exposed intermittently throughout a day. Such
exposure might result in an animal having a more severe avoidance response and leaving
a larger area for an extended duration, potentially, for example, losing feeding
opportunities for a day or more. Given the extensive mitigation and monitoring measures
included in this rule, we anticipate severe behavioral effects to be minimized to the extent
practicable.
Many species perform vital functions, such as feeding, resting, traveling, and
socializing on a diel cycle (24-hour cycle). Behavioral reactions to noise exposure, when
taking place in a biologically important context, such as disruption of critical life
functions, displacement, or avoidance of important habitat, are more likely to be
significant if they last more than one day or recur on subsequent days (Southall et al.,
2007) due to diel and lunar patterns in diving and foraging behaviors observed in many
cetaceans (Baird et al., 2008; Barlow et al., 2020; Henderson et al., 2016, Schorr et al.,
2014). It is important to note the water depth in the Lease Area and ECCs is shallow
ranging from 0-41.5 in the ECCs and 37.1-63.4 in the Lease Area) and deep-diving
species, such as sperm whales, are not expected to be engaging in deep foraging dives
when exposed to noise above NMFS harassment thresholds during the specified
activities. Therefore, we do not anticipate foraging behavior in deep water to be impacted
by the specified activities.
It is important to identify that the estimated number of takes for each stock does
not necessarily equate to the number of individual marine mammals expected to be
harassed (which may be lower, depending on the circumstances), but rather to the
instances of take that may occur. These instances may represent either brief exposures of

seconds for UXO/MEC detonations, seconds to minutes for HRG surveys, or, in some
cases, longer durations of exposure within (but not exceeding) a day (e.g., pile driving).
Some members of a species or stock may experience one exposure (i.e., be taken on one
day) as they move through an area, while other individuals may experience recurring
instances of take over multiple days throughout the year, in which case the number of
individuals taken is smaller than the number of takes proposed for authorization for that
species or stock. For species that are more likely to be migrating through the area and/or
for which only a comparatively smaller number of takes are predicted (e.g., some of the
mysticetes), it is more likely that each take represents a different individual. However, for
non-migrating species or stocks with larger numbers of predicted take, we expect that the
total anticipated takes represent exposures of a smaller number of individuals of which
some would be taken across multiple days.
For the SouthCoast Project, impact pile driving of foundation piles is most likely
to result in a higher magnitude and severity of behavioral disturbance than other activities
(i.e., vibratory pile driving, UXO/MEC detonations, and HRG surveys). Impact pile
driving has higher source levels than vibratory pile driving and HRG surveys, and
produces much lower frequencies than most HRG survey equipment, resulting in
significantly greater sound propagation because lower frequencies typically propagate
further than higher frequencies. While UXO/MEC detonations may have higher source
levels than other activities, the number of UXO/MEC detonations is limited (10 over 5
years) and each produces blast noise and pressure for an extremely short period (on the
order of a fraction of a second near the source and seconds further from the source) as
compared to multiple hours of pile driving or HRG surveys in a given day.
While foundation installation impact pile driving is anticipated to result in the
most takes due to high source levels, pile driving would not occur all day, every day.
Table 2 describes the number of piles, by pile type and scenario, that may be driven each

day. As described in the Description of Specified Activities section, impact driving
could occur for up to 4 hours per monopile and 2 hours per pin pile. For those piles also
including vibratory driving in Project 2, the duration of impact driving would be reduced.
If vibratory pile driving is used to set the pile (Project 2 only), this would be limited to 20
minutes per monopile and 90 minutes per pin pile. No more than 2 monopiles or 4 pin
piles would be installed each day for the majority of installations. As described in the
construction schedule scenarios (Table 2), on 3 or 4 days for each Project, two
installation vessels would work concurrently to install WTG foundations and OSP
foundations, further reducing the overall amount of time during which impact pile driving
noise is transmitted into marine mammal habitat. Impacts would be minimized through
implementation of mitigation measures, including use of a sound attenuation system,
soft-starts, and the implementation of clearance and shutdown zones that either delay or
suspend, respectively, pile driving when marine mammals are detected at specified
distances. Further, given sufficient notice through the use of soft-start, marine mammals
are expected to move away from a pile driving sound source prior to becoming exposed
to very loud noise levels. The requirement to couple visual monitoring (using multiple
PSOs) and PAM before and during all foundation installation and UXO/MEC detonations
will increase the overall capability to detect marine mammals and effectively implement
realtime mitigation measures, as compared to one method alone. Measures such as the
requirement to apply noise attenuation systems and implementation of clearance zones
also apply to UXO/MEC detonation(s), which also have the potential to elicit TTS and
more severe behavioral reactions; hence, severity of TTS and behavioral responses, are
expected to be lower than would be the case without noise mitigation.
Occasional, milder behavioral reactions are unlikely to cause long-term
consequences for individual animals or populations. Even if some smaller subset of the
takes are in the form of a longer (several hours or a day) and more severe response, if

they are not expected to be repeated over numerous or sequential days, impacts to
individual fitness are not anticipated. Nearly all studies and experts agree that infrequent
exposures of a single day or less are unlikely to impact an individual’s overall energy
budget (Farmer et al., 2018; Harris et al., 2017; King et al., 2015; National Academy of
Science, 2017; New et al., 2014; Southall et al., 2007; Villegas-Amtmann et al., 2015).
Further, the effect of disturbance is strongly influenced by whether it overlaps with
biologically important habitats when individuals are present—avoiding biologically
important habitats (which occur in both space and time) will provide opportunities to
compensate for reduced or lost foraging (Keen et al., 2021). Importantly, the seasonal
restrictions on pile driving and UXO/MEC detonation limit take to those times when
species of particular concern are less likely to be present in biologically important
habitats and, if present, less likely to be engaged in critical behaviors such as foraging.
Temporary Threshold Shift (TTS)
Temporary Threshold Shift (TTS)
TTS is one form of Level B harassment that marine mammals may incur through
exposure to SouthCoast’s activities and, as described earlier, the proposed takes by Level
B harassment may represent takes in the form of behavioral disturbance, TTS, or both. As
discussed in the Potential Effects to Marine Mammals and their Habitat section, in
general, TTS can last from a few minutes to days, be of varying degree, and occur across
different frequency bandwidths, all of which determine the severity of the impacts on the
affected individual, which can range from minor to more severe. Impact and vibratory
pile driving and UXO/MEC detonations are broadband noise sources (i.e., produce sound
over a wide range of frequencies) but most of the energy is concentrated below 1-2 kHz,
with a small amount of energy ranging up to 20 kHz. Low-frequency cetaceans are most
susceptible to noise-induced hearing loss at lower frequencies, given this is a frequency
band in which they produce vocalizations to communicate with conspecifics, we would

anticipate the potential for TTS incidental to pile driving and detonations to be greater in
this hearing group (i.e., mysticetes) compared to others (e.g., mid-frequency). However,
we would not expect the TTS to span the entire communication or hearing range of any
species given that the frequencies produced by these activities do not span entire hearing
ranges for any particular species. Additionally, though the frequency range of TTS that
marine mammals might sustain would overlap with some of the frequency ranges of their
vocalizations and other auditory cues for the time periods when they are in the vicinity of
the sources, the frequency range of TTS from SouthCoast’s pile driving and UXO/MEC
detonation activities would not be expected to span the entire frequency range of one
vocalization type, much less span all types of vocalizations or of all other critical auditory
cues for any given species, much less for long continuous durations. The proposed
mitigation measures further reduce the potential for TTS in mysticetes.
Generally, both the degree of TTS and the duration of TTS would be greater if the
marine mammal is exposed to a higher level of energy (which would occur when the
peak dB level is higher or the duration is longer). The threshold for the onset of TTS was
discussed previously (see Estimated Take). An animal would have to approach closer to
the source or remain in the vicinity of the sound source appreciably longer to increase the
received SEL, which would be unlikely considering the proposed mitigation and the
nominal speed of the receiving animal relative to the stationary sources such as impact
pile driving. The recovery time of TTS is also of importance when considering the
potential impacts from TTS. In TTS laboratory studies (as discussed in Potential Effects
of the Specified Activities on Marine Mammals and Their Habitat), some using
exposures of almost an hour in duration or up to 217 SEL, almost all individuals
recovered within 1 day (or less, often in minutes) and we note that while the pile driving
activities last for hours a day, it is unlikely that most marine mammals would stay in
close proximity to the source long enough to incur more severe TTS. UXO/MEC

detonation also has the potential to result in TTS. However, given the duration of
exposure is extremely short (milliseconds), the degree of TTS (i.e., the amount of dB
shift) is expected to be small and TTS duration is expected to be short (minutes to hours).
Overall, given the few instances in which any individual might incur TTS, the low degree
of TTS and the short anticipated duration, and very low likelihood that any TTS would
overlap the entirety of an individual’s critical hearing range, it is unlikely that TTS (of the
nature expected to result from SouthCoast’s activities) would result in behavioral changes
or other impacts that would impact any individual's (of any hearing sensitivity)
reproduction or survival.
Permanent Threshold Shift (PTS)
NMFS proposes to authorize a very small number of take by PTS to some marine
mammals. The numbers of proposed annual takes by Level A harassment are relatively
low for all marine mammal stocks and species (table 51). The only activities incidental to
which we anticipate PTS may occur is from exposure to impact pile driving and
UXO/MEC detonations, which produce sounds that are both impulsive and primarily
concentrated in the lower frequency ranges (below 1 kHz) (David, 2006; Krumpel et al.,
2021). PTS would consist of minor degradation of hearing capabilities occurring
predominantly at frequencies one-half to one octave above the frequency of the energy
produced by pile driving or instantaneous UXO/MEC detonation (i.e., the low-frequency
region below 2 kHz) (Cody and Johnstone, 1981; McFadden, 1986; Finneran, 2015), not
severe hearing impairment. If hearing impairment occurs from either impact pile driving
or UXO/MEC detonation, it is most likely that the affected animal would lose a few
decibels in its hearing sensitivity, which in most cases is not likely to meaningfully affect
its ability to forage and communicate with conspecifics.
SouthCoast estimates 10 UXO/MECs may be detonated and the exposure analysis
conservatively assumes that all of the UXO/MECs found would consist of the largest

charge weight of UXO/MEC (E12; 454 kg (1,001 lbs)). However, it is highly unlikely
that all charges would be the maximum size; thus, the number of takes by Level A
harassment that may occur incidental to the detonation of the UXO/MECs is likely less
than what is estimated.
There are no PTS data on cetaceans and only one instance of PTS being induced
in older harbor seals (Reichmuth et al., 2019). However, available TTS data (of midfrequency hearing specialists exposed to mid- or high-frequency sounds (Southall et al.,
2007; NMFS, 2018; Southall et al., 2019)) suggest that most threshold shifts occur in the
frequency range of the source up to one octave higher than the source. We would
anticipate a similar result for PTS. Further, no more than a small degree of PTS is
expected to be associated with any of the incurred Level A harassment given it is unlikely
that animals would stay in the close vicinity of impact pile driving for a duration long
enough to produce more than a small degree of PTS and given sufficient notice through
use of soft-start prior to implementation of full hammer energy during impact pile
driving, marine mammals are expected to move away from a sound source that is
disturbing prior to it resulting in severe PTS. Given UXO/MEC detonations are
instantaneous, the potential for PTS is not a function of duration. NMFS recognizes the
distances to PTS thresholds may be large for certain species (e.g., over 8.6 km (28,215 ft)
based on the largest charge weights; see tables 39-42); however, SouthCoast would
utilize multiple vessels equipped with at minimum 3 PSOs each as well as PAM to
observe and acoustically detect marine mammals. A marine mammal within the PTS
zone would trigger a delay to detonation until the clearance zones are declared clear of
marine mammals, thereby minimizing potential for PTS for all marine mammal species
and ensuring that any PTS that does occur is of a relatively low degree.
Auditory Masking or Communication Impairment

The ultimate potential impacts of masking on an individual are similar to those
discussed for TTS (e.g., decreased ability to communicate, forage effectively, or detect
predators), but an important difference is that masking only occurs during the time of the
signal versus TTS, which continues beyond the duration of the signal. Also, though,
masking can result from the sum of exposure to multiple signals, none of which might
individually cause TTS. Fundamentally, masking is referred to as a chronic effect
because one of the key potential harmful components of masking is its duration—the fact
that an animal would have reduced ability to hear or interpret critical cues becomes much
more likely to cause a problem the longer it is occurring. Inherent in the concept of
masking is the fact that the potential for the effect is only present during the times that the
animal and the source are in close enough proximity for the effect to occur (and further,
this time period would need to coincide with a time that the animal was utilizing sounds
at the masked frequency).
As our analysis has indicated, for this project we expect that impact pile driving
foundations have the greatest potential to mask marine mammal signals, and this pile
driving may occur for several, albeit intermittent, hours per day for multiple days per
year. Masking is fundamentally more of a concern at lower frequencies (which are pile
driving dominant frequencies) because low-frequency signals propagate significantly
further than higher frequencies and because they are more likely to overlap both the
narrower low frequency calls of mysticetes, as well as many non-communication cues
related to fish and invertebrate prey, and geologic sounds that inform navigation.
However, the area in which masking would occur for all marine mammal species and
stocks (e.g., predominantly in the vicinity of the foundation pile being driven) is small
relative to the extent of habitat used by each species and stock. In summary, the nature of
SouthCoast’s activities, paired with habitat use patterns by marine mammals, does not

support the likelihood that the level of masking that could occur would have the potential
to affect reproductive success or survival.
Impacts on Habitat and Prey
Pile driving associated with foundation installation or UXO/MEC detonation may
result in impacts to prey, the extent to which based, in part, on the specific prey type.
While fish and invertebrate mortality or injury may occur, it is anticipated that these
types of impacts would be limited to a very small subset of available prey very close to
the source, and that the implementation of mitigation measures (e.g., use of a noise
attenuation system during pile driving and UXO/MEC detonation, soft-starts for pile
driving) would limit the severity and extent of impacts (again, noting UXO/MEC
detonation would be limited to 10 events). Pile driving noise, both impact and vibratory,
UXO.MEC detonations, and HRG surveys may cause mobile prey species, primarily fish,
to temporarily leave the area of disturbance, resulting in temporary displacement from
habitat near the pile driving or detonation site. For those HRG acoustic sources used by
SouthCoast that operate at frequencies that are likely outside the hearing range of marine
mammal prey species, no effects are anticipated.
Any behavioral avoidance of the disturbed area by the subset of affected fish is
expected to be localized (i.e., fish would not travel far from the site of disturbance) and
temporary, thus piscivorous species (including marine mammals and some larger fish
species), would still have access to significantly large areas of prey in foraging habitat in
the nearby vicinity. Repeated exposure of individual fish to sound and energy from pile
driving or underwater explosions is not likely, given fish movement patterns, especially
schooling prey species. The duration of fish avoidance of an area after pile driving stops
or a UXO/MEC is detonated is unknown, but it is anticipated that there would be a rapid
return to normal recruitment, distribution and behavior following cessation of the

disturbance. Long-term consequences for fish populations, including key prey species
within the project area, would not be expected.
Impacts to prey species with limited self-mobility (e.g., zooplankton) would also
depend on proximity to the specified activities, without the potential for avoidance of the
activity site on the same spatial scale as fishes and other mobile species. However,
impacts to zooplankton, in the context of availability as marine mammal prey, from these
activities are expected to be minimal, based on both experimental data and theoretical
modeling of zooplankton population responses to airgun noise exposure (see Effects on
Prey section). In general, the rapid reproductive rate of zooplankton, coupled with
advection of zooplankton from sources outside of the Lease Area and ECCs would help
support maintenance of the population in these areas, should pile driving or detonation
activities result in changes in physiology impacting limiting reproduction (e.g., growth
suppression) or mortality of zooplankton. Long-term impacts to zooplankton populations
and their habitat from pile driving and detonation activities in the project area are not
anticipated, thereby limiting potential impacts to zooplanktivorous species, including
North Atlantic right whales.
In general, impacts to marine mammal prey species from construction activities
are expected to be minor and temporary due to the expected limited daily duration of
individual pile driving events and few instances (10) of UXO/MEC detonations.
Behavioral changes in prey in response to construction activities could temporarily
impact marine mammals' foraging opportunities in a limited portion of the foraging range
but, because of the relatively small area of the habitat that may be affected at any given
time (e.g., around a pile being driven) and the temporary nature of the disturbance on
prey species, the impacts to marine mammal habitat from construction activities (i.e.,
foundation installation, UXO/MEC detonation, and HRG surveys) are not expected to
cause significant or long-term negative consequences.

Cable presence is not anticipated to impact marine mammal habitat as these
would be buried, and any electromagnetic fields emanating from the cables are not
anticipated to result in consequences that would impact marine mammals’ prey to the
extent they would be unavailable for consumption.
The physical presence of WTG foundations and associated scour protection
within the Lease Area would remain within marine mammal habitat for approximately 30
years. The submerged parts of these structures act as artificial reefs, providing new
habitats and restructuring local ecology, likely affecting some prey resources that could
benefit many species, including some marine mammals. Wind turbine presence and/or
operations is, in general, likely to result in oceanographic effects in the marine
environment, and may alter aggregations and distribution of marine mammal zooplankton
prey and other species through changing the strength of tidal currents and associated
fronts, changes in stratification, primary production, the degree of mixing, and
stratification in the water column (Schultze et al., 2020; Chen et al., 2021; Johnson et al.,
2021; Christiansen et al., 2022; Dorrell et al., 2022). However, there is significant
uncertainty regarding the extent to and rate at which changes may occur, how potential
changes might impact various marine mammal prey species (e.g., fish, copepods), and
how or if impacts to prey species might result in impacts to marine mammal foraging that
may result in fitness consequences.
The project would consist of no more than 149 foundations supporting 147 WTGs
and 2 OSPs in the Lease Area, which will gradually become operational (i.e.,
commissioned) throughout construction of Project 1 and Project 2. SouthCoast’s
construction schedule indicates that it is possible that WTGs would not become
operational until the latter part of the 5-year effective period of the rule, if issued.

Mitigation to Reduce Impacts on All Species
This proposed rulemaking includes a variety of mitigation measures designed to
minimize impacts on all marine mammals, with enhanced measures focused on North
Atlantic right whales (the latter is described in more detail below). For impact pile
driving of foundation piles and UXO/MEC detonations, ten overarching mitigation and
monitoring measures are proposed, which are intended to reduce both the number and
intensity of marine mammal takes: (1) seasonal and time of day work restrictions; (2) use
of multiple PSOs to visually observe for marine mammals (with any detection within
specifically designated zones that would trigger a delay or shutdown); (3) use of PAM to
acoustically detect marine mammals, with a focus on detecting baleen whales (with any
detection within designated zones triggering delay or shutdown); (4) implementation of
clearance zones; (5) implementation of shutdown zones; (6) use of soft-start; (7) use of
noise attenuation technology; (8) maintaining situational awareness of marine mammal
presence through the requirement that any marine mammal sighting(s) by SouthCoast’s
personnel must be reported to PSOs; (9) sound field verification monitoring; and (10)
vessel strike avoidance measures to reduce the risk of a collision with a marine mammal
and vessel. For HRG surveys, we are requiring six measures: (1) measures specifically
for vessel strike avoidance; (2) specific requirements during daytime and nighttime HRG
surveys; (3) implementation of clearance zones; (4) implementation of shutdown zones;
(5) use of ramp-up of acoustic sources; and (6) maintaining situational awareness of
marine mammal presence through the requirement that any marine mammal sighting(s)
by SouthCoast’s personnel must be reported to PSOs.
NMFS has proposed mitigation to reduce the impacts of the specified activities on
the species and stocks to the extent practicable. The Proposed Mitigation section
discusses the manner in which the required mitigation measures reduce the magnitude
and/or severity of the take of marine mammals. For pile driving and UXO/MEC

detonations, SouthCoast would be required to reduce noise levels to the lowest levels
practicable and implement additional NAS should SFV identify that measured distances
have exceeded modeled distances to harassment threshold isopleths, assuming a 10-dB
attenuation. Use of a soft-start during impact pile driving will allow animals to move
away from the sound source prior to applying higher hammer energy levels needed to
install the pile (this anticipated behavior is accounted for in the take estimates given they
represent installation of the entire pile at various hammer energy levels, including very
low energy levels). SouthCoast would not use a hammer energy greater than necessary to
install piles, thereby minimizing exposures to higher sound levels. Similarly, ramp-up
during HRG surveys would allow animals to move away and avoid the acoustic sources
before they reach their maximum energy level. For pile driving and HRG surveys,
clearance zone and shutdown zone implementation, which are required when marine
mammals are within given distances associated with certain impact thresholds for all
activities, would reduce the magnitude and severity of marine mammal take by delaying
or shutting down the activity if marine mammals are detected within these relevant zones,
thus reducing the potential for exposure to more disturbing levels of noise. Additionally,
the use of multiple PSOs (WTG and OSP foundation installation, HRG surveys, and
UXO/MEC detonations), PAM operators (for impact foundation installation and
UXO/MEC detonation), and maintaining awareness of marine mammal sightings
reported in the region (for WTG and OSP foundation installation, HRG surveys, and
UXO/MEC detonations) would aid in detecting marine mammals that would trigger the
implementation of the mitigation measures. The reporting requirements, including SFV
reporting (for foundation installation, foundation operation, and UXO/MEC detonations),
will assist NMFS in identifying if impacts beyond those analyzed in this proposed rule
are occurring, potentially leading to the need to enact adaptive management measures in
addition to or in place of the proposed mitigation measures. Overall, the proposed

mitigation measures affect the least practicable adverse impact on marine mammals from
the specified activities.
Mysticetes
Six mysticete species (comprising six stocks) of cetaceans (North Atlantic right
whale, humpback whale, blue whale, fin whale, sei whale, and minke whale) may be
taken by harassment. These species, to varying extents, utilize the specified
geographicalregion, including the Lease Area and ECCs, for the purposes of migration,
foraging, and socializing. The extent to which any given individual animal engages in
these behaviors in the area is species-specific, varies seasonally, and, in part, is dependent
upon the availability of prey (with animals generally foraging if the amount of prey
necessary to forage is available). For example, mysticetes may be migrating through the
project area towards or from primary feeding habitats (e.g., Cape Cod Bay, Stellwagen
Bank, Great South Channel, and Gulf of St. Lawrence) and calving grounds in the
southeast, and thereby spending a very limited amount of time in the presence of the
specified activities. Alternatively, as discussed in the Effects section and in the speciesspecific sections below, mysticetes may be engaged in foraging behavior over several
days. Overall, the mitigation measures, including the enhanced seasonal restrictions on
pile driving and UXO/MEC detonation, are specifically designed to limit, to the
maximum extent practical, take to those times when species of concern, namely the North
Atlantic right whale, are most likely to not be engaged in critical behaviors such as
concentrated foraging.
As described previously, Nantucket Shoals provides important foraging habitat
for multiple species. For Projects 1 and 2, the ensonified zone extending to the NMFS
harassment threshold isopleths produced during impact installation of foundations would
extend out to a distance of 7.4 km (4.6 mi) from each pile as it is installed, including from
foundations located closest to Nantucket Shoals. While vibratory pile driving for Project

2 would result in a larger ensonified zone (42 km (26.1 mi)), foundations for that project
would be located in the southwestern part of the Lease Area, a minimum of 20 km (12.4
mi) from the 30-m (98.4-ft) isobath on the western edge of Nantucket Shoals and
vibratory driving would be limited in duration for each foundation using this method (up
to 90 minutes for each pin pile and up to 20 minutes for each monopile). As described in
the Effects section, distance from a source can be influential on the intensity of impact
(i.e., the farther a marine mammal receiver is from a source, the less intense the expected
behavioral reaction). In addition, any displacement of whales or interruption of foraging
bouts would be expected to be relatively temporary in nature. Seasonal restrictions on
pile driving and UXO/MEC detonations would ensure that these activities do not occur
during prime foraging periods for particular mysticete species, including the North
Atlantic right whale. Thus, for both projects, the area of potential marine mammal
disturbance during pile driving does not fully spatially and temporally encompass the
entirety of any specific mysticete foraging habitat.
Behavioral data on mysticete reactions to pile driving noise are scant. Kraus et al.
(2019) predicted that the three main impacts of offshore wind farms on marine mammals
would consist of displacement, behavioral disruptions, and stress. Broadly, we can look
to studies that have focused on other noise sources such as seismic surveys and military
training exercises, which suggest that exposure to loud signals can result in avoidance of
the sound source (or displacement if the activity continues for a longer duration in a place
where individuals would otherwise have been staying, which is less likely for mysticetes
in this area), disruption of foraging activities (if they are occurring in the area), local
masking around the source, associated stress responses, and impacts to prey (as well as
TTS or PTS in some cases) that may affect marine mammal behavior.
The potential for repeated exposures is dependent upon the residency time of
whales, with migratory animals unlikely to be exposed on repeated occasions and animals

remaining in the area to be more likely exposed repeatedly. For mysticetes, where
relatively low numbers of species-specific take by Level B harassment are predicted
(compared to the abundance of the mysticete species or stock, such as is indicated in table
53) and movement patterns for most species suggest that individuals would not
necessarily linger around the project area for multiple days, each predicted take likely
represents an exposure of a different individual, with perhaps, for a few species, a subset
of takes potentially representing a small number of repeated takes of a limited number of
individuals across multiple days. In other words, the behavioral disturbance to any
individual mysticete would, therefore, likely occur within a single day within a year, or
potentially across a few days.
In general, the duration of exposures would not be continuous throughout any
given day (with an estimated maximum of 8 hours of intermittent impact pile driving per
day in Project 1, regardless of foundation type; up to 8 hours of intermittent impact
driving if 2 monopiles are installed per day using only an impact hammer in Project 2;up
to 5.6 hours of intermittent impact and 40 minutes of of vibratory pile driving in Project 2
if installing 2 monopiles requiring both installation methods; or up to 6 hours of
intermittent impact and 6 hours of vibratory pile driving if installing 4 pin piles requiring
both methods). In addition, pile driving would not occur on all consecutive days within a
given year, due to weather delays or any number of logistical constraints SouthCoast has
identified. Species-specific analysis regarding potential for repeated exposures and
impacts is provided below.
The fin whale is the only mysticete species for which PTS is anticipated and
proposed for authorization. As described previously, PTS for mysticetes from some
project activities may overlap frequencies used for communication, navigation, or
detecting prey. However, given the nature and duration of the activity, the mitigation
measures, and likely avoidance behavior for pile driving, any PTS is expected to be of a

small degree, would be limited to frequencies where pile driving noise is concentrated
(i.e., only a small subset of their expected hearing range) and would not be expected to
impact reproductive success or survival.
North Atlantic Right Whale
North Atlantic right whales are listed as endangered under the ESA and as both
depleted and strategic stocks under the MMPA. As described in the Potential Effects to
Marine Mammals and Their Habitat section, North Atlantic right whales are
threatened by a low population abundance, high mortality rates, and low reproductive
rates. Recent studies have reported individuals showing high stress levels (e.g., Corkeron
et al., 2017) and poor health, which has further implications on reproductive success and
calf survival (Christiansen et al., 2020; Stewart et al., 2021; Stewart et al., 2022; Pirotta
et al., 2024). As described below, a UME has been designated for North Atlantic right
whales. Given this, the status of the North Atlantic right whale population is of
heightened concern and, therefore, merits additional analysis and consideration. No Level
A harassment, serious injury, or mortality is anticipated or proposed for authorization for
this species.
For North Atlantic right whales, this proposed rule would allow for the
authorization of up to 149 takes, by Level B harassment, over the 5-year period, with no
more than 111 takes by Level B harassment allowed in any single year. The majority of
these takes (n=111) would likely occur in the year in which SouthCoast proposes to
construct Project 2 Scenario 2 (73 monopiles), with two-thirds (n=100) occurring
incidental to impact and vibratory pile driving in the southern portion of the Lease Area
(farthest from important feeding habitat near Nantucket Shoals). Installation using a
combination of pile driving methods would begin with vibratory pile driving, which is
expected to occur for 20 minutes per 9/16-m monopile and 90 minutes per 4.5-m pin pile,
and require fewer impact hammer strikes during the impact hammering phase because the

pile would already be partially installed using vibratory pile driving, thus minimizing use
of the installation method (i.e., impact pile driving) expected to elicit stronger behavioral
responses. Although the Level B harassment zone resulting from vibratory pile driving is
larger (42 km (26.1 mi)) than that produced by impact hammering (7.4 km (4.6 mi)), it
would extend from Project 2 foundation only, thus reducing overlap of the ensonified
zone with North Atlantic right whale feeding habitat nearer Nantucket Shoals. As
described in the Potential Effects of the Specified Activities on Marine Mammals and
Their Habitat section, the best available science indicates that distance from a source is
an important variable when considering both the potential for and the anticipated severity
of behavioral disturbance from an exposure in that it can have an effect on behavioral
response that is independent of the effect of received level (e.g., DeRuiter et al., 2013;
Dunlop et al., 2017a; Dunlop et al., 2017b; Falcone et al., 2017; Dunlop et al., 2018;
Southall et al., 2019a). The maximum number of North Atlantic right whale takes that
may occur in a given year are primarily driven by Project 2, Scenario 2 in which impact
and vibratory driving are anticipated to result in 100 takes (table 35). The majority of
these takes are due to extension of the ensonified zone, given the 120-dB behavioral
threshold for vibratory driving, towards areas with higher densities of North Atlantic
right whales on Nantucket Shoals. Animals exposed to vibratory driving sounds on the
Shoals would be tens of kilometers from the source; therefore, while NMFS anticipates
takes may occur, the intensity of take is expected to be minimal and not result in
behavioral changes that would meaningfully result in impacts that could affect the
population through annual rates of recruitment or survival.
The maximum number of annual takes (111 total, incidental to all activities)
equates to approximately 32.8 percent of the stock abundance, if each take were
considered to be of a different individual. However, this is a highly unlikely scenario
given the reasons described below. Further, far lower numbers of take are expected in the

years when SouthCoast is not installing foundations (e.g., years when only HRG surveys
would be occurring). For Project 1, only 12 takes (approximately 8 percent of all 149
takes) would be incidental to installation of foundations using impact pile driving as the
only installation method, the activity NMFS anticipates would result in the most intense
behavioral responses. A small number of Level B harassment takes (23) would occur
incidental to HRG surveys over 5 years, an activity for which the maximum size
ensonified zone is very small (141 m (462.6 ft)) and the severity of any behavioral
harassment is expected to be very low. The remaining takes (17) would occur incidentally
to 10 instantaneous UXO/MEC detonations, should they occur. SouthCoast would
detonate UXO/MECs as a last resort, only after attempting every other option available,
including avoidance (i.e., working around the UXO/MEC location in the project area).
SouthCoast’s proposed seasonal restriction on this activity (December 1 – April 30)
would significantly reduce the potential that detonation events occur when North Atlantic
right whales are expected to be most frequent in Southern New England region, and the
required extensive clearance process prior to detonation would help ensure no right
whales were within the portion of the Lease Area or ECC where the planned detonation
would occur, minimizing the potential for more severe TTS (e.g., longer lasting and of
higher shift) or behavioral reaction. Detonations, if required, would be instantaneous,
further limiting the probability of exposure to sound levels likely to result in TTS or more
severe behavioral reactions. In consideration of the enhanced mitigation measures,
including the extensive monitoring proposed to detect North Atlantic right whales to
enact such mitigation, the Level B harassment takes proposed for authorization are
expected to elicit only minor behavioral responses (e.g., avoidance, temporary cessation
of foraging) and not result in impacts to reproduction and survival.
As previously described, it is long-established that coastal waters in SNE are part
of a known migratory corridor for North Atlantic right whales, but over the past decade

or more, it has become increasingly clear that suitable foraging habitat exists in the area
as well. In addition to increased occurrence (understood through visual and PAM
detection data) in the area, the number of DMAs declared in the area has also increased in
recent years. Foraging North Atlantic right whales, particularly those in groups of 3 or
more, often remain in a feeding area for up to 2 weeks (this is the basis for defining
DMAs), meaning individual whales may be using SNE habitat for extended periods. The
region has been also been characterized as an important transition region (i.e., a stopover
site for migrating North Atlantic right whales moving to or from southeastern calving
grounds and more northern feeding grounds, as well as a feeding location utilized at other
times of the year by individuals (Quintana-Rizzo et al., 2021; O’Brien et al., 2022).
Additional qualitative observations in southern New England include animals socializing
(Quintana-Rizzo et al., 2021). As described in the Potential Effects of the Specified
Activities on Marine Mammals and Their Habitat section, North Atlantic right whales
range outside of the project area for their main feeding, breeding, and calving activities;
however, the importance of Southern New England, particularly the Nantucket Shoals
area, for critical behaviors such as foraging, warranted the enhanced mitigation measures
described in this proposed rule to minimize the potential impacts on North Atlantic right
whales.
Quintana-Rizzo et al. (2021) noted different degrees of residency (i.e., the
minimum number of days an individual remained in southern New England) for right
whales, with individual sighting frequency ranging from 1 to 10 days, annually.
Resightings (i.e., observation of the same individual on separate occasions) occurred
most frequently from December through May. Model outputs suggested that, during these
months, 23 percent of the species’ population was present in this region, and that the
mean residence time tripled between their study periods (i.e., December through May,
2011-2015 compared to 2017-2019) to an average of 13 days during these months. The

seasonal restriction on pile driving for both Projects 1 and 2 includes this period, thus
reducing the potential for repeated exposures of individual right whales during either
project because whales are not expected to persist in the project area to the same extent
during the months pile driving would occur. The more extensive seasonal restriction
within the NARW EMA (October 16 - May 31 would further reduce this possibility,
although the increased likelihood of foraging activity closer to Nantucket Shoals might
create the potential for repeated exposures, should whales linger there to forage despite
the occurrence of construction activities in the vicinity. Across all years, if an individual
were exposed during a subsequent year, the impact of that exposure is likely independent
of the previous exposure given the expectation that impacts to marine mammals from
project activities would generally be temporary (i.e., minutes to hours) and of low
severity, coupled with the extensive duration between exposures. However, the extensive
mitigation and monitoring measures SouthCoast would be required to implement,
including delaying or ceasing pile driving for 24 to 48 hours (depending on the number of
animals sighted and time of year) if SouthCoast observes a North Atlantic right whale at
any distance or acoustically detects a right whale within the 10-km (6.2-mi) (pin pile) or
15-km (9.3-mi) (monopile) PAM clearance/shutdown zone, are expected to reduce
impacts should take occur.
Quintana-Rizzo et al. (2021) noted that North Atlantic right whale sightings
during the 2017-2019 study period were primarily concentrated in the southeastern
sections of the MA WEA, throughout the northeast section of the Lease Area and areas
south of Nantucket, during winter (December-February), shifted northwest towards
Martha’s Vineyard and the RI/MA WEA in spring (March-May), and to the east higher
up on Nantucket Shoals in the summer (June-August) (Quintano-Rizzo et al., 2021).
Summer and fall sightings did not occur in 2011-2015, and only a small number of right
whales were sighted south of Nantucket (Quintana-Rizzo et al., 2021). In PAM data

collected in southern New England from 2020 through 2022, acoustic detections of North
Atlantic right whales occurred most frequently from November through April, and less
frequently from May through mid-October, particularly in recordings collected on the
eastern edge of the WEAs, within the NARW EMA, compared to recordings collected in
western southern New England (van Parijs et al., 2023; Davis et al., 2023). Placing a
moratorium on pile driving in the NARW EMA from Oct 16 – May 31 would minimize
exposures of right whales to pile driving noise, and any potential associated foraging
disruptions, by avoiding foundation installation when right whales are most prevalent and
most likely to be engaged in foraging in that part of the project area, as well as
minimizing the potential for multiple exposures per individual given pile driving would
not occur when residency times are expected to be extended based on resighting
frequency and acoustic persistence data (Quintano-Rizzo et al., 2021; Davis et al., 2023).
Similarly, seasonally restricting pile driving from January 1 – May 15, annually, outside
of the NARW EMA (applicable to a portion of Project 1 foundations and all of Project 2
foundations), would extend the area over which pile driving is limited during the period
of peak right whale abundance in southern New England, thus limiting exposures and
temporary foraging disturbances more broadly. Similarly, restricting UXO/MEC
detonations from December 1 – April 30 ensures that this activity would not occur when
North Atlantic right whales utilize habitat in the project area most often. Although HRG
surveys would not be subject to seasonal restrictions, impacts from Level B harassment
would be minimal given the low numbers of take proposed for authorization and very
small harassment zone.
In summary, North Atlantic right whales in the project area are expected to be
predominately engaging in migratory behavior during the spring and fall, foraging
behavior primarily in late winter and spring (and, to some degree, throughout the year),
and social behavior during winter and spring (Quintana-Rizzo et al., 2021). Within the

project area, North Atlantic right whale occurrence and foraging are both expected to be
most extensive near Nantucket Shoals, along the eastern edge of the MA WEA within the
NARW EMA. Given the species’ migratory behavior and occurrence patterns, we
anticipate individual whales would typically utilize specific habitat in the project area
(inside and outside the NARW EMA), primarily during months when foundation
installation and UXO/MEC detonation would not occur (given the specific time/area
restrictions on these activities specific to inside, and outside, the NARW EMA). It is
important to note the activities that could occur from December through May (i.e., are not
seasonally restricted) that may impact North Atlantic right whales using the habitat for
foraging would be primarily HRG surveys, with very small Level B harassment zones
(less than 150 m) due to rapid transmission loss of the sounds produced neither of which
would result in very high received levels. While UXO/MEC detonation may occur in
November or May, the number of UXO/MECs are expected to be very minimal (if any)
and would be instantaneous in nature; thereby, resulting in short term, minimal impacts
with any TTS that may occur recovering quickly.
As described in the Description of Marine Mammals in the Specified
Geographic Area section of this preamble, North Atlantic right whales are presently
experiencing an ongoing UME (beginning in June 2017). Preliminary findings support
human interactions, specifically vessel strikes and entanglements, as the cause of death
for the majority of North Atlantic right whales. Given the current status of the North
Atlantic right whale, the loss of even one individual could significantly impact the
population. Any disturbance to North Atlantic right whales due to SouthCoast’s activities
is expected to result in temporary avoidance of the immediate area of construction. As no
injury, serious injury, or mortality is expected or proposed for authorization and Level B
harassment of North Atlantic right whales will be reduced to the lowest level practicable
(both in magnitude and severity) through use of mitigation measures, the proposed

number of takes of North Atlantic right whales would not exacerbate or compound the
effects of the ongoing UME.
As described in the general Mysticetes section above, foundation installation is
likely to result in the greatest number of annual takes and is of greatest concern given
loud source levels. This activity would be most extensively limited to locations outside of
the NARW EMA and during times when, based on the best available science, North
Atlantic right whales are less frequently encountered in the NARW EMA and less likely
to be engaged in critical foraging behavior (although NMFS recognizes North Atlantic
right whales may forage year-round in the project area). Temporal limits on foundation
installation outside of the NARW EMA are similarly defined by expectations, based on
the best available science, that North Atlantic right whale occurrence would be lowest
when pile driving would occur.
The potential types, severity, and magnitude of impacts are also anticipated to
mirror that described in the general Mysticetes section above, including avoidance (the
most likely outcome), changes in foraging or vocalization behavior, masking, and
temporary physiological impacts (e.g., change in respiration, change in heart rate).
Although a small amount of TTS is possible, it is not likely. Importantly, given the
enhanced mitigation measures specific to North Atlantic right whales, the effects of the
activities are expected to be sufficiently low-level and localized to specific areas as to not
meaningfully impact important migratory or foraging behaviors for North Atlantic right
whales. These takes are expected to result in temporary behavioral disturbance, such as
slight displacement (but not abandonment) of migratory habitat or temporary cessation of
feeding.
In addition to the general mitigation measures discussed earlier in the Preliminary
Negligible Impact Analysis section, to provide enhanced protection for right whales and
minimize the number and/or severity of exposures, SouthCoast would be required to

implement conditionally-triggered protocols in response to sightings or acoustic
detections of North Atlantic right whales. If one or two North Atlantic right whales is/are
sighted or if PAM operators detect a right whale vocalization, pile driving would be
suspended until the next day, commencing only after SouthCoast conducts a vessel-based
survey of the zone around the pile driving location (10-km (6.2-mi) zone for pin pile; 15km (9.3-mi) zone for monopile) to ensure the zone is clear of North Atlantic right whales.
Pile driving would be delayed for 482 days following a sighting of 3 or more whales
(more likely indicative of a potential feeding aggregation), followed by the same survey
requirement prior to commencing foundation installation. Further, given many of these
exposures are generally expected to occur to different individual right whales migrating
through (i.e., many individuals would not be impacted on more than one day in a year),
with some subset potentially being exposed on no more than a few days within the year,
they are unlikely to result in energetic consequences that could affect reproduction or
survival of any individuals.
Overall, NMFS expects that any behavioral harassment of North Atlantic right
whales incidental to the specified activities would not result in changes to their migration
patterns or foraging success, as only temporary avoidance of an area during construction
is expected to occur. As described previously, North Atlantic right whales migrate,
forage, and socialize in the Lease Area, but are not expected to remain in this habitat (i.e.,
not expected to be engaged in extensive foraging behavior) for prolonged durations
during the months SouthCoast would install foundations, considering the seasonal
restrictions SouthCoast proposed and NMFS would require, relative to habitats to the
north, such as Cape Cod Bay, the Great South Channel, and the Gulf of St. Lawrence
(Mayo, 2018; Quintana-Rizzo et al., 2021; Meyer-Gutbrod et al., 2022; Plourde et al.,
2024). Any temporarily displaced animals would be able to return to or continue to travel
through the project area and subsequently utilize this habitat once activities have ceased.

Although acoustic masking may occur in the vicinity of the foundation
installation activities, based on the acoustic characteristics of noise associated with
impact pile driving (e.g., frequency spectra, short duration of exposure) and construction
surveys (e.g., intermittent signals), NMFS expects masking effects to be minimal. Given
that the majority of Project 1 foundations would be located within the NARW EMA,
where North Atlantic right whales are most likely to occur throughout the year,
SouthCoast decided to use the installation method that resulted in a smaller ensonified
zone (i.e., impact pile driving). Foundations would be installed farther from the NARW
EMA in the southwestern half of the Lease Area for Project 2, thus, if vibratory pile
driving occurs, the Level B harassment zone would not overlap this high-use area to the
same extent. In addition, the most severe masking impacts would likely occur when a
North Atlantic right whale is in relatively close proximity to the pile driving location,
which would be minimized given the requirement that pile driving must be delayed or
shutdown if a North Atlantic right whale is sighted at any distance or acoustically
detected within the PAM clearance or shutdown zones (10-km (6.2-mi) or 15-km (9.3mi)) during installation of 4.5-m pin piles or 9/16-m monopiles, respectively). In
addition, both pile driving methods are expected to occur intermittently within a day and
be confined to the months in which North Atlantic right whales occur at lower densities.
Any masking effects would be minimized by anticipated mitigation effectiveness and
likely avoidance behaviors.
As described in the Potential Effects to Marine Mammals and Their Habitat
section of this preamble, the distance of the receiver to the source influences the severity
of response with greater distances typically eliciting less severe responses. NMFS
recognizes North Atlantic right whales migrating could be pregnant females (in the fall)
and cows with older calves (in spring) and that these animals may slightly alter their
migration course in response to any foundation pile driving; however, we anticipate that

course diversion would be of small magnitude. Hence, while some avoidance of the pile
driving activities may occur, we anticipate any avoidance behavior of migratory North
Atlantic right whales would be similar to that of gray whales (Tyack et al., 1983), on the
order of hundreds of meters up to 1 to 2 km. This diversion from a migratory path
otherwise uninterrupted by project activities is not expected to result in meaningful
energetic costs that would impact annual rates of recruitment or survival. NMFS expects
that North Atlantic right whales would be able to avoid areas during periods of active
noise production while not being forced out of this portion of their habitat.
North Atlantic right whale presence in the project area is year-round. However,
abundance during summer months is lower compared to the winter months, with spring
and fall serving as “shoulder seasons” wherein abundance waxes (fall) or wanes (spring).
Given this year-round habitat usage, in recognition that where and when whales may
actually occur during project activities is unknown, as it depends on the annual migratory
behaviors, SouthCoast has proposed and NMFS is proposing to require a suite of
mitigation measures designed to reduce impacts to North Atlantic right whales to the
maximum extent practicable. These mitigation measures (e.g., seasonal/daily work
restrictions, vessel separation distances, reduced vessel speed, increased monitoring
effort) would not only avoid the likelihood of vessel strikes but also would minimize the
severity of behavioral disruptions by minimizing impacts (e.g., through sound reduction
using noise attenuation systems and reduced temporal and spatial overlap of project
activities and North Atlantic right whales). This would further ensure that the number of
takes by Level B harassment that are estimated to occur are not expected to affect
reproductive success or survivorship by impacts to energy intake or cow/calf interactions
during migratory transit. However, even in consideration of recent habitat-use and
distribution shifts, SouthCoast would still be installing foundations when the occurrence
of North Atlantic right whales is expected to be lower.

As described in the Description of Marine Mammals in the Specified
Geographic Area section of this preamble, SouthCoast Project would be constructed
within the North Atlantic right whale migratory corridor BIA, which represents areas and
months within which a substantial portion of a species is known to migrate. The Lease
Area is relatively narrow compared to the width of the North Atlantic right whale
migratory corridor BIA (approximately 47.5 km (29.5 mi) versus approximately 300 km
(186 mi), respectively, at the furthest points near the Lease Area). Because of this, overall
North Atlantic right whale migration is not expected to be impacted by the proposed
activities. There are no known North Atlantic right whale mating or calving areas within
the project area. Although the project area includes foraging habitat, extensive mitigation
measures would minimize impacts by temporally and spatially reducing co-occurrence of
project activities and feeding North Atlantic right whales. Prey species (e.g., calanoid
copepods) are more broadly distributed throughout southern New England during periods
when pile driving and UXO/MEC detonation would occur (noting again that North
Atlantic right whale prey is not particularly concentrated in the project area relative to
nearby habitats). Therefore, any impacts to prey that may occur during the effective
period of these regulations are also unlikely to impact marine mammals in a manner that
would affect reproduction or survival of any individuals.
The most significant measure to minimize impacts to individual North Atlantic
right whales is the seasonal moratorium on all foundation installation activities in the
NARW EMA from October 16 through May 31, annually, and throughout the rest of the
Lease Area from January 1 through May 15, as well as the limitation on these activities in
December (e.g., only work with approval from NMFS), when North Atlantic right whale
abundance in the Lease Area is expected to be highest. NMFS also expects this measure
to greatly reduce the potential for mother-calf pairs to be exposed to impact pile driving
noise above the Level B harassment threshold during their annual spring migration

through the project area from calving grounds to primary foraging grounds (e.g., Cape
Cod Bay). UXO/MEC detonations would also be restricted from December 1 through
April 30, annually. NMFS also expects that the severity of any take of North Atlantic
right whales would be reduced due to the additional proposed mitigation measures that
would ensure that any exposures above the Level B harassment threshold would result in
only short-term effects to individuals exposed.
Pile driving and UXO/MEC detonations may only begin in the absence of North
Atlantic right whales (based on visual and passive acoustic monitoring). If pile driving
has commenced, NMFS anticipates North Atlantic right whales would avoid the area,
utilizing nearby waters to carry on pre-exposure behaviors. However, foundation
installation activities must be shut down if a North Atlantic right whale is sighted at any
distance or acoustically detected at any distance within the PAM shutdown zone, unless a
shutdown is not feasible due to risk of injury or loss of life. If a sighting of a North
Atlantic right whale within the Level B harassment zone triggers shutdown, both the
duration and intensity of exposure would be reduced. NMFS anticipates that if North
Atlantic right whales are exposed to foundation installation or UXO/MEC detonation
noise, it is unlikely a North Atlantic right whale would approach the sound source
locations to the degree that they would purposely expose themselves to very high noise
levels. This is because observations of typical whale behavior demonstrate likely
avoidance of harassing levels of sound where possible (Richardson et al., 1985). These
measures are designed to avoid PTS and also reduce the severity of Level B harassment,
including the potential for TTS. While some TTS could occur, given the mitigation
measures (e.g., delay pile driving upon a sighting or acoustic detection and shutting down
upon a sighting or acoustic detection), the potential for TTS to occur is low and, as
described above for all mysticetes, any TTS would be expected to be of a relatively short
duration and small degree.

The proposed clearance and shutdown measures are most effective when
detection efficiency is maximized, as the measures are triggered by a sighting or acoustic
detection. To maximize detection efficiency, SouthCoast proposed and NMFS is
proposing to require the combination of PAM and visual observers. In addition, NMFS is
proposing to require communication protocols with other project vessels and other
heightened awareness efforts (e.g., daily monitoring of North Atlantic right whale
sighting databases) such that as a North Atlantic right whale approaches the source (and
thereby could be exposed to higher noise energy levels), PSO detection efficacy would
increase, the whale would be detected, and a delay to commencing pile driving or
shutdown (if feasible) would occur. NMFS is proposing to require that, during three
timeframes (NARW EMA: August 1-Oct 15; outside NARW EMA: May 16-May 31 and
December 1-31), SouthCoast deploy four dedicated PSO vessels, each with three on-duty
PSOs, to monitor before, during, and after pile driving for right whale sightings “at any
distance.” For all other foundation installation timeframes (NARW EMA: June 1-July
31; outside NARW EMA: June 1-November 30) NMFS would require that this
monitoring be conducted by a minimum 3 PSOs on each of three dedicated PSO vessels.
By increasing the extent of monitoring platforms and observers, and thereby the detection
efficacy, exposures would be minimized because North Atlantic right whales would be
detected at greater distances, prompting delay or shutdown before the whale enters the
Level B harassment zone.
Given that specific locations for the 10 possible UXOs/MECs are not presently
known, SouthCoast has agreed to undertake specific mitigation measures to reduce
impacts on any North Atlantic right whales, including delaying a UXO/MEC detonation
if a North Atlantic right whale is visually observed or acoustically detected at any
distance. The UXO/MEC detonations mitigation measures described above would further
reduce the potential to be exposed to high received levels.

For HRG surveys, the maximum distance to the Level B harassment isopleth is
141 m (462.6 ft). Because of the short maximum distance to the Level B harassment
isopleth, the requirement that vessels maintain a distance of 500 m (1,640.4 ft) from any
North Atlantic right whale, the fact whales are unlikely to remain in close proximity to an
HRG survey vessel for any length of time, and that the acoustic source would be
shutdown if a North Atlantic right whale is observed within 500 m (1,640.4 ft) of the
source, any exposure to noise levels above the Level B harassment threshold (if any)
would be very brief. To further minimize exposures, ramp-up of boomers, sparkers, and
CHIRPs must be delayed during the clearance period if PSOs detect a North Atlantic
right whale within 500 m (1,640.4 ft) of the acoustic source. Due to the nature of the
activity, and with implementation of the proposed mitigation requirements, take by Level
A harassment is unlikely and, therefore, not proposed for authorization. Potential impacts
associated with Level B harassment would include low-level, temporary behavioral
modifications, most likely in the form of avoidance behavior. Given the high level of
precautions taken to minimize both the amount and intensity of Level B harassment on
North Atlantic right whales, it is unlikely that the anticipated low-level exposures would
lead to reduced reproductive success or survival for any individual North Atlantic right
whales.
Given the documented habitat use within the area within the timeframe
foundation installations and UXO/MEC detonations may occur, a subset of these takes
may represent multiple exposures of some number of individuals than is the case for
other mysticetes, though some takes may also represent one-time exposures to an
individual the majority of the individuals taken would be impacted on only one day in a
year, with a small subset potentially impacted on no more than a few days a year and,
further, low level impacts are generally expected from any North Atlantic right whale
exposure. The magnitude and severity of harassment are not expected to result in impacts

on the reproduction or survival of any individuals, let alone have impacts on annual rates
of recruitment or survival of this stock.
Given the low magnitude and severity of the impacts from the take proposed for
authorization discussed above and in consideration of the proposed mitigation and other
information presented, SouthCoast’s specified activities during the proposed effective
period of the rule are not expected to result in impacts on the reproduction or survival of
any individuals, or affect annual rates of recruitment or survival. For these reasons, we
have preliminarily determined that the take by Level B harassment only anticipated and
proposed for authorization would have a negligible impact on the North Atlantic right
whale.
Of note, there is significant uncertainty regarding the impacts of turbine
foundation presence and operation on the oceanographic conditions that serve to
aggregate prey species for North Atlantic right whales and - given SouthCoast’s
proximity to Nantucket Shoals - it is possible that the expanded analysis of turbine
presence and/or operation over the life of the project developed for the ESA biological
opinion for the proposed SouthCoast project or additional information received during
the public comment period will necessitate modifications to the proposed analysis,
mitigation and monitoring measures, and/or this finding. For example, it is possible that
additional information or analysis could result in a determination that changes in the
oceanographic conditions that serve to aggregate North Atlantic right whale prey may
result in impacts that would qualify as a take under the MMPA for North Atlantic right
whales.
Blue whale
The blue whale is listed as endangered under the ESA, and the Western North
Atlantic stock is considered depleted and strategic under the MMPA. There are no known
areas of specific biological importance in or around the project area, and there is no

ongoing UME. The actual abundance of the stock is likely significantly greater than what
is reflected in the SAR because the most recent population estimates are primarily based
on surveys conducted in U.S. waters and the stock's range extends well beyond the U.S.
EEZ. No serious injury or mortality is anticipated or authorized for this species.
The rule allows up to nine takes of blue whales, by Level B harassment, over the
5-year period. The maximum annual allowable number of takes by Level B harassment is
three, which equates to approximately 0.75 percent of the stock abundance if each take
were considered to be of a different individual. Based on the migratory nature of blue
whales and the fact that there are neither feeding nor reproductive areas documented in or
near the project area, and in consideration of the very low number of predicted annual
takes, it is unlikely that the predicted instances of takes would represent repeat takes of
any individual—in other words, each take likely represents one whale exposed on 1 day
within a year.
With respect to the severity of those individual takes by Level B harassment, we
would anticipate impacts to be limited to low-level, temporary behavioral responses with
avoidance and potential masking impacts in the vicinity of the foundation installation to
be the most likely type of response. Any potential TTS would be concentrated at half or
one octave above the frequency band of pile driving noise (most sound is below 2 kHz)
which does not include the full predicted hearing range of blue whales. Any hearing
ability temporarily impaired from TTS is anticipated to return to pre-exposure conditions
within a relatively short time period after the exposures cease. Any avoidance of the
project area due to the activities would be expected to be temporary.
Given the magnitude and severity of the impacts discussed above, and in
consideration of the required mitigation and other information presented, SouthCoast's
activities are not expected to result in impacts on the reproduction or survival of any
individuals, much less affect annual rates of recruitment or survival. For these reasons,

we have preliminarily determined that the take by Level B harassment anticipated and
proposed to be authorized will have a negligible impact on the western North Atlantic
stock of blue whales.
Fin whale
The fin whale is listed as endangered under the ESA, and the western North
Atlantic stock is considered both depleted and strategic under the MMPA. No UME has
been designated for this species or stock.
The rule proposes to authorize up to 572 takes, by harassment only, over the 5year effective period. The maximum annual allowable take by Level A harassment and
Level B harassment, is 3 and 496, respectively (combined, this annual take (n=499)
equates to approximately 7.34 percent of the stock abundance, if each take were
considered to be of a different individual), with far lower numbers than that expected in
the years without foundation installation (e.g., years when only HRG surveys would be
occurring). Given the months the project will occur and that southern New England is
generally considered a feeding habitat, it is likely that some subset of the individual
whales exposed could be taken several times annually.
Level B harassment is expected to be in the form of behavioral disturbance,
primarily resulting in avoidance of the Lease Area where foundation installation is
occurring, potential disruption of feeding, and some low-level TTS and masking that may
limit the detection of acoustic cues for relatively brief periods of time. Any potential PTS
would be minor (limited to a few dB) and any TTS would be of short duration and
concentrated at half or one octave above the frequency band of pile driving noise (most
sound is below 2 kHz) which does not include the full predicted hearing range of fin
whales.
Fin whales are present in the waters off of New England year-round and are one
of the most frequently observed large whales and cetaceans in continental shelf waters,

principally from Cape Hatteras, North Carolina in the Mid-Atlantic northward to Nova
Scotia, Canada (Sergeant, 1977; Sutcliffe and Brodie, 1977; CETAP, 1982; Hain et al.,
1992; Geo-Marine, 2010; BOEM, 2012; Edwards et al., 2015; Hayes et al., 2022). In the
project area, fin whales densities are highest in the winter and summer months (Roberts
et al., 2023) though detections do occur in spring and fall (Watkins et al., 1987; Clark
and Gagnon, 2002; Geo-Marine, 2010; Morano et al., 2012). However, fin whales feed
more extensively in waters in the Great South Channel north to the Gulf Maine into the
Gulf of St. Lawrence, areas north and east of the project area (Hayes et al., 2024).
As discussed previously, the majority of project area is located to the east of small
fin whale feeding BIA (2,933 km2 (724,760.1 acres)) east of Montauk Point, New York
(Figure 2.3 in LaBrecque et al., 2015) that is active from March to October. Except for a
small section of the Brayton Point route, the Lease Area and the ECCs do not overlap the
fin whale feeding BIA. However, if vibratory pile driving is used for Project 2, the
ensonified zone resulting from installation of the closest foundations could extend into
the southeastern side of the BIA. Foundation installations and UXO/MEC detonations
have seasonal work restrictions (i.e., spatial and temporal) such that the temporal overlap
between these specified activities and the active BIA timeframe would exclude the
months of March and April. A separate larger year-round feeding BIA (18,015 km2
(4,451,603.4 acres)) located to the east in the southern Gulf of Maine does not overlap
with the project area and would thus not be impacted by project activities. We anticipate
that if foraging is occurring in the project area and foraging whales are exposed to noise
levels of sufficient strength, they would avoid the project area and move into the
remaining area of the feeding BIA that would be unaffected to continue foraging without
substantial energy expenditure or, depending on the time of year, travel south towards
New York Bight foraging habitat or northeast to the larger year-round feeding BIA.

Given the documented habitat use within the area, some of the individuals taken
would likely be exposed on multiple days. However, low level impacts are generally
expected from any fin whale exposure. Given the magnitude and severity of the impacts
discussed above (including no more than 566 takes of the course of the 5-year rule, and a
maximum annual allowable take by Level A harassment and Level B harassment, of 3
and 496, respectively), and in consideration of the required mitigation and other
information presented, SouthCoast’s activities are not expected to result in impacts on the
reproduction or survival of any individuals, much less affect annual rates of recruitment
or survival. For these reasons, we have determined that the take by harassment
anticipated and proposed for authorization will have a negligible impact on the western
North Atlantic stock of fin whales.
Sei whale
Sei whales are listed as endangered under the ESA, and the Nova Scotia stock is
considered both depleted and strategic under the MMPA. There are no known areas of
specific biological importance in or adjacent to the project area, and no UME has been
designated for this species or stock. No serious injury or mortality is anticipated or
authorized for this species.
The rule authorizes up to 67 takes by harassment over the 5-year period. No Level
A harassment is anticipated for proposed for authorization. The maximum annual
allowable take by Level B harassment is 48, which equates to approximately 0.8 percent
of the stock abundance, if each take were considered to be of a different individual), with
far lower numbers than that expected in the years without foundation installation (e.g.,
years when only HRG surveys would be occurring). As described in the Description of
Marine Mammals in the Specified Geographic Area section of this preamble, most of
the sei whale distribution is concentrated in Canadian waters and seasonally in northerly
U.S. waters, although they are uncommonly observed as far south as the waters off of

New York. Because sei whales are migratory and their known feeding areas are east and
north of the project area (e.g., there is a feeding BIA in the Gulf of Maine), they would be
more likely to be moving through and, considering this and the very low number of total
takes, it is unlikely that any individual would be exposed more than once within a given
year.
With respect to the severity of those individual takes by Level B harassment, we
anticipate impacts to be limited to low-level, temporary behavioral responses with
avoidance and potential masking impacts in the vicinity of the WTG installation to be the
most likely type of response. Any potential PTS and TTS would likely be concentrated at
half or one octave above the frequency band of pile driving noise (most sound is below 2
kHz) which does not include the full predicted hearing range of sei whales. Moreover,
any TTS would be of a small degree. Any avoidance of the project area due to the
Project’s activities would be expected to be temporary.
Given the magnitude and severity of the impacts discussed above (including no
more than 67 takes of the course of the 5-year rule, and a maximum annual allowable
take of 0 by Level A harassment and 48 by Level B harassment), and in consideration of
the required mitigation and other information presented, SouthCoast’s activities are not
expected to result in impacts on the reproduction or survival of any individuals, much
less affect annual rates of recruitment or survival. For these reasons, we have
preliminarily determined that the take by harassment anticipated and proposed to be
authorized will have a negligible impact on the Nova Scotia stock of sei whales.
Minke whale
Minke whales are not listed under the ESA, and the Canadian East Coast stock is
neither considered depleted nor strategic under the MMPA. There are no known areas of
specific biological importance in or adjacent to the project area. As described in the
Description of Marine Mammals in the Specific Geographic Area section of this

preamble, a UME has been designated for this species but is pending closure. No serious
injury or mortality is anticipated or authorized for this species.
The rule authorizes up to 1,162 takes by Level B harassment over the 5-year
period. No Level A harassment is anticipated or proposed for authorization. The
maximum annual allowable take by Level B harassment is 911, which equates to
approximately 4 percent of the stock abundance, if each take were considered to be of a
different individual), with far lower numbers than that expected in the years without
foundation installation (e.g., years when only HRG surveys would be occurring). As
described in the Description of Marine Mammals in the Specified Geographic Area
section, minke whales inhabit coastal waters during much of the year and are common
offshore the U.S. Eastern Seaboard with a strong seasonal component in the continental
shelf and in deeper, off-shelf waters (CETAP, 1982; Hayes et al., 2022; Hayes et al.,
2024). Spring through fall are times of relatively widespread and common acoustic
occurrence on the continental shelf. From September through April, minke whales are
frequently detected in deep-ocean waters throughout most of the western North Atlantic
(Clark and Gagnon, 2002; Risch et al., 2014; Hayes et al., 2024). Minke whales were
detected in southern New England primarily in the spring and fall, with few detections in
the summer and winter. In eastern southern New England, near the project area, acoustic
detections were most frequent from April through mid-June (van Parijs et al., 2023).
Because minke whales are migratory and their known feeding areas are north and east of
the project area, including a feeding BIA in the southwestern Gulf of Maine and George’s
Bank, they would be more likely to be transiting through (with each take representing a
separate individual), though it is possible that some subset of the individual whales
exposed could be taken up to a few times annually.
As previously detailed in the Description of Marine Mammals in the Specified
Geographic Area section, there is a UME for minke whales along the Atlantic coast,

from Maine through South Carolina, with the highest number of deaths in Massachusetts,
Maine, and New York. Preliminary findings in several of the whales have shown
evidence of human interactions or infectious diseases. However, we note that the
population abundance is approximately 22,000, and the take by Level B harassment
authorized through this action is not expected to exacerbate the UME.
We anticipate the impacts of this harassment to follow those described in the
general Mysticetes section above. Any TTS would be of short duration and concentrated
at half or one octave above the frequency band of pile driving noise (most sound is below
2 kHz) which does not include the full predicted hearing range of minke whales. Level B
harassment would be temporary, with primary impacts being temporary displacement of
the project area but not abandonment of any migratory or foraging behavior.
Given the magnitude and severity of the impacts discussed above (including no
more than 1,162 takes of the course of the 5-year rule, and a maximum annual allowable
take by Level A harassment and Level B harassment, of 0 and 911, respectively), and in
consideration of the required mitigation and other information presented, SouthCoast’s
activities are not expected to result in impacts on the reproduction or survival of any
individuals, much less affect annual rates of recruitment or survival. For these reasons,
we have preliminarily determined that the take by harassment anticipated and proposed
for authorized will have a negligible impact on the Canadian Eastern Coastal stock of
minke whales.
Humpback whale
The West Indies Distinct Population Segments (DPS) of humpback whales is not
listed as threatened or endangered under the ESA but the Gulf of Maine stock, which
includes individuals from the West Indies DPS, is considered strategic under the MMPA.
However, as described in the Description of Marine Mammals in the Specified
Geographic Area section of this preamble to the rule, humpback whales along the

Atlantic Coast have been experiencing an active UME as elevated humpback whale
mortalities have occurred along the Atlantic coast from Maine through Florida since
January 2016. Of the cases examined, approximately 40 percent had evidence of human
interaction (vessel strike or entanglement). Take from vessel strike and entanglement is
not authorized. Despite the UME, the relevant population of humpback whales (the West
Indies breeding population, or DPS of which the Gulf of Maine stock is a part) remains
stable at approximately 12,000 individuals.
NMFS is proposing to authorize up to 541 takes, by Level B harassment, over the
5-year period. No Level A harassment take is proposed for authorization. The maximum
annual allowable take by Level B harassment is 341, which equates to approximately 24
percent of the stock abundance, if each take were considered to be of a different
individual), with far lower numbers than that expected in the years without foundation
installation (e.g., years when only HRG surveys would be occurring). Given that feeding
is considered the principal activity of humpback whales in southern New England waters,
it is likely that some subset of the individual whales exposed could be taken several times
annually.
Among the activities analyzed, the combination of impact and vibratory pile
driving has the potential to result in the highest amount of annual take of humpback
whales (0 takes by Level A harassment and 341 takes by Level B harassment) and is of
greatest concern, given the associated loud source levels associated with impact pile
driving and large Level B harassment zone resulting from vibratory pile driving.
In the western North Atlantic, humpback whales feed during spring, summer, and
fall over a geographic range encompassing the eastern coast of the U.S. Feeding is
generally considered to be focused in areas north of the project area, including in a
feeding BIA in the Gulf of Maine/Stellwagen Bank/Great South Channel, but has been
documented off the coast of southern New England and as far south as Virginia (Swingle

et al., 1993). Foraging animals tend to remain in the area for extended durations to
capitalize on the food sources.
Assuming humpback whales who are feeding in waters within or surrounding the
project area behave similarly, we expect that the predicted instances of disturbance could
consist of some individuals that may be exposed on multiple days if they are utilizing the
area as foraging habitat. Also similar to other baleen whales, if migrating, such
individuals would likely be exposed to noise levels from the project above the harassment
thresholds only once during migration through the project area.
For all the reasons described in the Mysticetes section above, we anticipate any
potential PTS and TTS would be concentrated at half or one octave above the frequency
band of pile driving noise (most sound is below 2 kHz), which does not include the full
predicted hearing range of baleen whales. If TTS is incurred, hearing sensitivity would
likely return to pre-exposure levels relatively shortly after exposure ends. Any masking
or physiological responses would also be of low magnitude and severity for reasons
described above.
Given the magnitude and severity of the impacts discussed above (including no
more than 541 takes over the course of the 5-year rule, and a maximum annual allowable
take by Level A harassment and Level B harassment, of 0 and 341 respectively), and in
consideration of the required mitigation measures and other information presented,
SouthCoast ’s activities are not expected to result in impacts on the reproduction or
survival of any individuals, much less affect annual rates of recruitment or survival. For
these reasons, we have preliminarily determined that the take by harassment anticipated
and proposed for authorization will have a negligible impact on the Gulf of Maine stock
of humpback whales.
Odontocetes

In this section, we include information here that applies to all of the odontocete
species and stocks addressed below, which are further divided into the following
subsections: sperm whales, dolphins and small whales; and harbor porpoises. These subsections include more specific information, as well as conclusions for each stock
represented.
The takes of odontocetes proposed for authorization are incidental to pile driving,
UXO/MEC detonations, and HRG surveys. No serious injury or mortality is anticipated
or proposed for authorization. We anticipate that, given ranges of individuals (i.e., that
some individuals remain within a small area for some period of time) and non-migratory
nature of some odontocetes in general (especially as compared to mysticetes), a larger
subset of these takes are more likely to represent multiple exposures of some number of
individuals than is the case for mysticetes, though some takes may also represent onetime exposures to an individual. Foundation installation is likely to disturb odontocetes to
the greatest extent compared to UXO/MEC detonations and HRG surveys. While we
expect animals to avoid the area during foundation installation and UXO/MEC
detonations, their habitat range is extensive compared to the area ensonified during these
activities. In addition, as described above, UXO/MEC detonations are instantaneous;
therefore, any disturbance would be very limited in time.
Any masking or TTS effects are anticipated to be of low severity. First, while the
frequency range of pile driving, the most impactful planned activity in terms of response
severity, falls within a portion of the frequency range of most odontocete vocalizations,
odontocete vocalizations span a much wider range than the low frequency construction
activities planned for the project. Also, as described above, recent studies suggest
odontocetes have a mechanism to self-mitigate the impacts of noise exposure (i.e., reduce
hearing sensitivity), which could potentially reduce TTS impacts. Any masking or TTS is
anticipated to be limited and would typically only interfere with communication within a

portion of an odontocete’s range and as discussed earlier, the effects would only be
expected to be of a short duration and for TTS, a relatively small degree.
Furthermore, odontocete echolocation occurs predominantly at frequencies
significantly higher than low frequency construction activities. Therefore, there is little
likelihood that threshold shift would interfere with feeding behaviors. The sources
operate at higher frequencies than foundation installation activities HRG surveys and
UXO/MEC detonations. However, sounds from these sources attenuate very quickly in
the water column, as described above. Therefore, any potential for PTS and TTS and
masking is very limited. Further, odontocetes (e.g., common dolphins, spotted dolphins,
bottlenose dolphins) have demonstrated an affinity to bow-ride actively surveying HRG
surveys. Therefore, the severity of any harassment, if it does occur, is anticipated to be
minimal based on the lack of avoidance previously demonstrated by these species.
The waters off the coast of Massachusetts are used by several odontocete species;
however, none (except the sperm whale) are listed under the ESA and there are no known
habitats of particular importance. In general, odontocete habitat ranges are far-reaching
along the Atlantic coast of the U.S., and the waters off of New England, including the
project area, do not contain any particularly unique odontocete habitat features.
Sperm Whale
The Western North Atlantic stock of sperm whales spans the East Coast out into
oceanic waters well beyond the U.S. EEZ. Although listed as endangered, the primary
threat faced by the sperm whale (i.e., commercial whaling) has been eliminated and,
further, sperm whales in the western North Atlantic were little affected by modern
whaling (Taylor et al., 2008). Current potential threats to the species globally include
vessel strikes, entanglement in fishing gear, anthropogenic noise, exposure to
contaminants, climate change, and marine debris. There is no currently reported trend for
the stock and, although the species is listed as endangered under the ESA, there are no

specific issues with the status of the stock that cause particular concern (e.g., no UMEs).
There are no known areas of biological importance (e.g., critical habitat or BIAs) in or
near the project area.
No mortality, serious injury or Level A harassment is anticipated or proposed for
authorization for this species. Impacts would be limited to Level B harassment and would
occur to only a small number of individuals (maximum of 126 in any given year (likely
year 2) and 149 across all 5 years) incidental to pile driving, UXO/MEC detonation(s),
and HRG surveys. Sperm whales are not common within the project area due to the
shallow waters, and it is not expected that any noise levels would reach habitat in which
sperm whales are common, including deep-water foraging habitat. If sperm whales do
happen to be present in the project area during any activities related to the SouthCoast
project, they would likely be only transient visitors and not engaging in any significant
behaviors. This very low magnitude and severity of effects is not expected to result in
impacts on the reproduction or survival of individuals, much less impact annual rates of
recruitment or survival. For these reasons, we have preliminarily determined, in
consideration of all of the effects of the SouthCoast’s activities combined, that the take
proposed for authorization would have a negligible impact on the North Atlantic stock of
sperm whales.
Dolphins and Small Whales (including delphinids and pilot whales)
There are no specific issues with the status of odontocete stocks that cause
particular concern (e.g., no recent UMEs). No mortality or serious injury is expected or
proposed for authorization for these stocks. No Level A harassment is anticipated or
proposed for authorization for any dolphin or small whale.
The maximum number of take, by Level B harassment, proposed for authorization
within any one year for all odontocetes cetacean stocks ranges from 522 to 52,943
instances, which is less than approximately 5 percent for 5 stocks and less that 25 percent

for one stock, as compared to the population size for all stocks. The common dolphin,
one of the most frequently occurring marine mammals in southern New England, is the
species for which take estimation resulted in the maximum number of takes (n=52,943)
and associated population percentage (24.5 percent) among small odontocetes. As
described above for odontocetes broadly, we anticipate that a fair number of these
instances of take in a day represent multiple exposures of a smaller number of
individuals, meaning the actual number of individuals taken is lower. Although some
amount of repeated exposure to some individuals is likely given the duration of activity
proposed by SouthCoast, the intensity of any Level B harassment combined with the
availability of alternate nearby foraging habitat suggests that the likely impacts would not
impact the reproduction or survival of any individuals.
Overall, the populations of all dolphins and small whale species and stocks for
which we propose to authorize take are stable (no declining population trends), not facing
existing UMEs, and the small number, magnitude and severity of takes is not expected to
result in impacts on the reproduction or survival of any individuals, much less affect
annual rates of recruitment or survival. For these reasons, we have preliminarily
determined, in consideration of all of the effects of the SouthCoast’s activities combined,
that the take proposed for authorization would have a negligible impact on all dolphin
and small whale species and stocks considered in this analysis.
Harbor Porpoises
The Gulf of Maine/Bay of Fundy stock of harbor porpoises is found
predominantly in northern U.S. coastal waters (less than 150 m depth) and up into
Canada's Bay of Fundy. Although the population trend is not known, there are no UMEs
or other factors that cause particular concern for this stock. No mortality or non-auditory
injury is anticipated or proposed for authorization for this stock. NMFS proposes to

authorize 109 takes by Level A harassment (PTS; incidental to UXO/MEC detonations)
and 3,442 takes by Level B harassment (incidental to multiple activities).
Regarding the severity of takes by behavioral Level B harassment, because harbor
porpoises are particularly sensitive to noise, it is likely that a fair number of the responses
could be of a moderate nature, particularly to pile driving. In response to pile driving,
harbor porpoises are likely to avoid the area during construction, as previously
demonstrated in Tougaard et al. (2009) in Denmark, in Dahne et al. (2013) in Germany,
and in Vallejo et al. (2017) in the United Kingdom, although a study by Graham et al.
(2019) may indicate that the avoidance distance could decrease over time. However, pile
driving is scheduled to occur when harbor porpoise abundance is low off the coast of
Massachusetts and, given alternative foraging areas, any avoidance of the area by
individuals is not likely to impact the reproduction or survival of any individuals. Given
only one UXO/MEC would be detonated on any given day and up to only 10 UXO/MEC
would be detonated over the 5-year effective period of the LOA, any behavioral response
would be brief and of a low severity.
With respect to PTS and TTS, the effects on an individual are likely relatively low
given the frequency bands of pile driving (most energy below 2 kHz) compared to harbor
porpoise hearing (150 Hz to 160 kHz peaking around 40 kHz). Specifically, PTS or TTS
is unlikely to impact hearing ability in their more sensitive hearing ranges, or the
frequencies in which they communicate and echolocate. Regardless, we have authorized
a limited amount of PTS, but expect any PTS that may occur to be within the very low
end of their hearing range where harbor porpoises are not particularly sensitive, and any
PTS would be of small magnitude. As such, any PTS would not interfere with key
foraging or reproductive strategies necessary for reproduction or survival.
In summary, the number of takes proposed for authorization across all 5 years is
109 by Level A harassment and 3,442 by Level B harassment. While harbor porpoises are

likely to avoid the area during any construction activity discussed herein, as demonstrated
during European wind farm construction, the time of year in which work would occur is
when harbor porpoises are not in high abundance, and any work that does occur would
not result in the species’ abandonment of the waters off of Massachusetts. The low
magnitude and severity of harassment effects is not expected to result in impacts on the
reproduction or survival of any individuals, let alone have impacts on annual rates of
recruitment or survival of this stock. No mortality or serious injury is anticipated or
proposed for authorization. For these reasons, we have preliminarily determined, in
consideration of all of the effects of the SouthCoast’s activities combined, that the
proposed authorized take would have a negligible impact on the Gulf of Maine/Bay of
Fundy stock of harbor porpoises.
Phocids (harbor seals and gray seals)
Neither the harbor seal nor gray seal are listed under the ESA. SouthCoast
requested, and NMFS proposes to authorize, that no more than 4 and 677 harbor seals
and 40 and 9,835 gray seals may be taken by Level A harassment and Level B
harassment, respectively, within any one year. These species occur in Massachusetts
waters most often in winter, when impact pile driving and UXO/MEC detonations would
not occur. Seals are also more likely to be close to shore such that exposure to impact pile
driving would be expected to be at lower levels generally (but still above NMFS
behavioral harassment threshold). The majority of takes of these species is from
monopile installations, and HRG surveys. Research and observations show that pinnipeds
in the water may be tolerant of anthropogenic noise and activity (a review of behavioral
reactions by pinnipeds to impulsive and non-impulsive noise can be found in Richardson
et al. (1995) and Southall et al. (2007)). Available data, though limited, suggest that
exposures between approximately 90 and 140 dB SPL do not appear to induce strong
behavioral responses in pinnipeds exposed to non-pulse sounds in water (Costa et al.,

2003; Jacobs and Terhune, 2002; Kastelein et al., 2006c). Although there was no
significant displacement during construction as a whole, Russell et al. (2016) found that
displacement did occur during active pile driving at predicted received levels between
168 and 178 dB re 1µPa(p-p); however seal distribution returned to the pre-piling condition
within two hours of cessation of pile driving. Pinnipeds may not react at all until the
sound source is approaching (or they approach the sound source) within a few hundred
meters and then may alert, ignore the stimulus, change their behaviors, or avoid the
immediate area by swimming away or diving. Effects on pinnipeds that are taken by
Level B harassment in the project area would likely be limited to reactions such as
increased swimming speeds, increased surfacing time, or decreased foraging (if such
activity were occurring). Most likely, individuals would simply move away from the
sound source and be temporarily displaced from those areas (see Lucke et al., 2006;
Edren et al., 2010; Skeate et al., 2012; Russell et al., 2016). Given their documented
tolerance of anthropogenic sound (Richardson et al., 1995; Southall et al., 2007),
repeated exposures of individuals of either of these species to levels of sound that may
cause Level B harassment are unlikely to significantly disrupt foraging behavior. Given
the low anticipated magnitude of impacts from any given exposure, even repeated Level
B harassment across a few days of some small subset of individuals, which could occur,
is unlikely to result in impacts on the reproduction or survival of any individuals.
Moreover, pinnipeds would benefit from the mitigation measures described in the
Proposed Mitigation section.
SouthCoast requested, and NMFS is proposing to authorize, a limited number of
takes by Level A harassment in the form of PTS (4 harbor seals and 40 gray seals)
incidental to UXO/MEC detonations over the 5-year effective period of the rule. As
described above, noise from UXO/MEC detonation is low frequency and while any PTS
that does occur would fall within the lower end of pinniped hearing ranges (50 Hz to 86

kHz), PTS would not occur at frequencies where pinniped hearing is most sensitive. In
summary, any PTS, would be of limited degree and not occur across the entire or even
most sensitive hearing range. Hence, any impacts from PTS are likely to be of low
severity and not interfere with behaviors critical to reproduction or survival.
Elevated numbers of harbor seal and gray seal mortalities were first observed in
July 2018 and occurred across Maine, New Hampshire, and Massachusetts until 2020.
Based on tests conducted so far, the main pathogen found in the seals belonging to that
UME was phocine distemper virus, although additional testing to identify other factors
that may be involved in this UME are underway. In 2022, a UME was declared in Maine
with some harbor and gray seals testing positive for highly pathogenic avian influenza
(HPAI) H5N1. Although elevated strandings continue. For harbor seals, the population
abundance is over 75,000 and annual M/SI (350) is well below PBR (2,006) (Hayes et
al., 2020). The population abundance for gray seals in the United States is over 27,000,
with an estimated overall abundance, including seals in Canada, of approximately
450,000. In addition, the abundance of gray seals is likely increasing in the U.S. Atlantic,
as well as in Canada (Hayes et al., 2020).
Overall, impacts from the Level B harassment take proposed for authorization
incidental to SouthCoast’s specified activities would be of relatively low magnitude and a
low severity. Similarly, while some individuals may incur PTS overlapping some
frequencies that are used for foraging and communication, given the low degree, the
impacts would not be expected to impact reproduction or survival of any individuals. In
consideration of all of the effects of SouthCoast’s activities combined, we have
preliminarily determined that the authorized take will have a negligible impact on harbor
seals and gray seals.
Preliminary Negligible Impact Determination

Based on the analysis contained herein of the likely effects of the specified
activity on marine mammals and their habitat and taking into consideration the
implementation of the proposed monitoring and mitigation measures, NMFS
preliminarily finds that the proposed marine mammal take from all of SouthCoast ’s
specified activities combined will have a negligible impact on all affected marine
mammal species or stocks.
Small Numbers
As noted above, only small numbers of incidental take may be authorized under
sections 101(a)(5)(A) and (D) of the MMPA for specified activities other than military
readiness activities. The MMPA does not define small numbers and so, in practice, where
estimated numbers are available, NMFS compares the number of individuals estimated to
be taken to the most appropriate estimation of abundance of the relevant species or stock
in our determination of whether an authorization is limited to small numbers of marine
mammals. When the predicted number of individuals to be taken is less than one-third of
the species or stock abundance, the take is considered to be of small numbers.
Additionally, other qualitative factors may be considered in the analysis, such as the
temporal or spatial scale of the activities.
NMFS proposes to authorize incidental take (by Level A harassment and Level B
harassment) of 16 species of marine mammal (with 16 managed stocks). The maximum
number of takes possible within any one year and proposed for authorization relative to
the best available population abundance is less than one-third for all species and stocks
potentially impacted (i.e., less than 1 percent for 5 stocks, less than 8 percent for 7 stocks,
less than 25 percent for 2 stocks, and less than 33 percent for 2 stocks; see table 53).
Based on the analysis contained herein of the proposed activities (including the
proposed mitigation and monitoring measures) and the anticipated take of marine

mammals, NMFS preliminarily finds that small numbers of marine mammals would be
taken relative to the population size of the affected species or stocks.
Unmitigable Adverse Impact Analysis and Determination
There are no relevant subsistence uses of the affected marine mammal stocks or
species implicated by this action. Therefore, NMFS has determined that the total taking
of affected species or stocks would not have an unmitigable adverse impact on the
availability of such species or stocks for taking for subsistence purposes.
Classification
Endangered Species Act (ESA)
Section 7(a)(2) of the Endangered Species Act of 1973 (ESA: 16 U.S.C. 1531 et
seq.) requires that each Federal agency ensure that any action it authorizes, funds, or
carries out is not likely to jeopardize the continued existence of any endangered or
threatened species or result in the destruction or adverse modification of designated
critical habitat. To ensure ESA compliance for the promulgation of rulemakings, NMFS
consults internally whenever we propose to authorize take for endangered or threatened
species, in this case with the NMFS Greater Atlantic Regional Field Office (GARFO).
NMFS is proposing to authorize the take of five marine mammal species which
are listed under the ESA: the North Atlantic right, sei, fin, blue, and sperm whale. The
Permit and Conservation Division requested initiation of Section 7 consultation on
November 1, 2022 with GARFO for the promulgation of this proposed rulemaking.
NMFS will conclude the Endangered Species Act consultation prior to reaching a
determination regarding the proposed issuance of the authorization. The proposed
regulations and any subsequent LOA(s) would be conditioned such that, in addition to
measures included in those documents, SouthCoast would also be required to abide by
the reasonable and prudent measures and terms and conditions of a Biological Opinion

and Incidental Take Statement, issued by NMFS, pursuant to Section 7 of the Endangered
Species Act.
Executive Order 12866
The Office of Management and Budget has determined that this proposed rule is
not significant for purposes of Executive Order 12866.
Regulatory Flexibility Act (RFA)
Pursuant to the RFA (5 U.S.C. 601 et seq.), the Chief Counsel for Regulation of
the Department of Commerce has certified to the Chief Counsel for Advocacy of the
Small Business Administration that this proposed rule, if adopted, would not have a
significant economic impact on a substantial number of small entities. SouthCoast is the
sole entity that would be subject to the requirements in these proposed regulations, and
SouthCoast is not a small governmental jurisdiction, small organization, or small
business, as defined by the RFA. Because of this certification, a regulatory flexibility
analysis is not required and none has been prepared.
Paperwork Reduction Act (PRA)
Notwithstanding any other provision of law, no person is required to respond to
nor shall a person be subject to a penalty for failure to comply with a collection of
information subject to the requirements of the PRA unless that collection of information
displays a currently valid Office of Management and Budget (OMB) control number.
These requirements have been approved by OMB under control number 0648-0151 and
include applications for regulations, subsequent LOA, and reports. Submit comments
regarding any aspect of this data collection, including suggestions for reducing the
burden, to NMFS.
Coastal Zone Management Act (CZMA)
We have preliminarily determined that this action is not within or would not
affect a state's coastal zone, and thus do not require a consistency determination under

307(c)(3)(A) of the Coastal Zone Management Act (CZMA; 16 U.S.C. § 1456 (c)(3)(A)).
Since the proposed action is expected to authorize incidental take of marine mammals in
coastal waters and on the outer continental shelf, and is an unlisted activity under 15
C.F.R. § 930.54, the only way in which this action would be subject to state consistency
review is if the state timely submits an unlisted activity request to the Director of
NOAA’s Office for Coastal Management (along with copies concurrently submitted to
the applicant and NMFS) within 30 days from the date of publication of the notice of
proposed rulemaking in the Federal Register and the Director approves such request.
Proposed Promulgation
As a result of these preliminary determinations, NMFS proposes to promulgate
regulations that allow for the authorization of take, by Level A harassment and Level B
harassment, incidental to construction activities associated with the SouthCoast Wind
Project offshore of Massachusetts for a 5-year period from April 1, 2027, through March
31, 2032, provided the previously mentioned mitigation, monitoring, and reporting
requirements are incorporated.
Request for Additional Information and Public Comments
NMFS requests interested persons to submit comments, information, and
suggestions concerning SouthCoast’s request and the proposed regulations (see
ADDRESSES). All comments will be reviewed and evaluated as we prepare the final
rule and make final determinations on whether to issue the requested authorization. This
proposed rule and referenced documents provide all environmental information relating
to our proposed action for public review.
Recognizing, as a general matter, that this action is one of many current and
future wind energy actions, we invite comment on the relative merits of the IHA, singleaction rule/LOA, and programmatic multi-action rule/LOA approaches, including

potential marine mammal take impacts resulting from this and other related wind energy
actions and possible benefits resulting from regulatory certainty and efficiency.
List of Subjects in 50 CFR Part 217
Administrative practice and procedure, Endangered and threatened species, Fish,
Fisheries, Marine mammals, Penalties, Reporting and recordkeeping requirements,
Transportation, Wildlife.
Dated: June 17, 2024.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs,
National Marine Fisheries Service.

For reasons set forth in the preamble, NMFS proposes to amend 50 CFR part 217
as follows:
PART 217—REGULATIONS GOVERNING THE TAKING AND IMPORTING
OF MARINE MAMMALS
1. The authority citation for part 217 continues to read as follows:
Authority: 16 U.S.C. 1361 et seq., unless otherwise noted.
2. Add subpart HH, consisting of §§ 217.330 through 217.339, to read as follows:
Subpart HH—Taking Marine Mammals Incidental to the SouthCoast Wind
Offshore Wind Farm Project Offshore Massachusetts
Sec.
217.330 Specified activity and specified geographical region.
217.331 Effective dates.
217.332 Permissible methods of taking.
217.333 Prohibitions.
217.334 Mitigation requirements.
217.335 Requirements for monitoring and reporting.
217.336 Letter of Authorization.
217.337 Modifications of Letter of Authorization.
217.338-217.339 [Reserved]
Subpart HH—Taking Marine Mammals Incidental to the SouthCoast Wind Project
Offshore Massachusetts
§ 217.330 Specified activity and specified geographical region.
(a) Regulations in this subpart apply only to activities associated with the
SouthCoast Wind Project conducted by SouthCoast Wind Energy, LLC (SouthCoast
Wind) and those persons SouthCoast Wind authorizes or funds to conduct activities on its
behalf in the area outlined in paragraph (b) of this section. Requirements imposed on
SouthCoast Wind must be implemented by those persons it authorizes or funds to
conduct activities on its behalf.
(b) The specified geographical region is the Mid-Atlantic Bight and vessel transit
routes to marshaling ports in Charleston, South Carolina and Sheet Harbor, Canada. The

Mid-Atlantic Bight extends between Cape Hatteras, North Carolina and Martha's
Vineyard, Massachusetts, extending westward into the Atlantic to the 100-m isobath and
includes, but is not limited to, the Bureau of Ocean Energy Management (BOEM) Lease
Area Outer Continental Shelf (OCS)-A-0521 Commercial Lease of Submerged Lands for
Renewable Energy Development, two export cable routes, and two sea-to-shore transition
point at Brayton Point in Somerset, Massachusetts and Falmouth, Massachusetts.
(c) The specified activities are impact and vibratory pile driving to install wind
turbine generator (WTG) and offshore substation platform (OSP) foundations; highresolution geophysical (HRG) site characterization surveys; detonation of unexploded
ordnances or munitions and explosives of concern (UXOs/MECs); fisheries and benthic
monitoring surveys; placement of scour protection; sand leveling; dredging; trenching,
laying, and burial activities associated with the installation of the export cable from the
OSP to shore based converter stations and inter-array cables between WTG foundations;
vessel transit within the specified geographical region to transport crew, supplies, and
materials; and WTG operations.
§ 217.331 Effective dates.
The regulations in this subpart are effective from April 1, 2027 through March 31,
2032.
§ 217.332 Permissible methods of taking.
Under a LOA issued pursuant to §§ 216.106 and 217.336, SouthCoast Wind and
those persons it authorizes or funds to conduct activities on its behalf, may incidentally,
but not intentionally, take marine mammals within the specified geographicalregion in
the following ways, provided SouthCoast Wind is in compliance with all terms,
conditions, and requirements of the regulations in this subpart and the LOA.

(a) By Level B harassment associated with the acoustic disturbance of marine
mammals by impact and vibratory pile driving of WTG and OSP foundations;
UXO/MEC detonations, and HRG site characterization surveys.
(b) By Level A harassment associated with impact pile driving WTG and OSP
foundations and UXO/MEC detonations.
(c) The incidental take of marine mammals by the activities listed in paragraphs
(a) and (b) of this section is limited to the following species and stocks:
Table 1 to Paragraph (c)
Marine mammal species

Scientific name

Stock

Blue whale

Balaenoptera musculus

Western North Atlantic

Fin whale

Balaenoptera physalus

Western North Atlantic

Sei whale

Balaenoptera borealis

Nova Scotia

Minke whale

Balaenoptera
acutorostrata

Canadian East Stock

North Atlantic right whale

Eubalaena glacialis

Western North Atlantic

Humpback whale

Megaptera novaeangliae

Gulf of Maine

Sperm whale

Physeter macrocephalus

North Atlantic

Atlantic spotted dolphin

Stenella frontalis

Western North Atlantic

Atlantic white-sided
dolphin

Lagenorhynchus acutus

Western North Atlantic

Bottlenose dolphin

Tursiops truncatus

Western North Atlantic
Offshore

Common dolphin

Delphinus delphis

Western North Atlantic

Harbor porpoise

Phocoena phocoena

Gulf of Maine/Bay of
Fundy

Long-finned pilot whale

Globicephala melas

Western North Atlantic

Risso's dolphin

Grampus griseus

Western North Atlantic

Gray seal

Halichoerus grypus

Western North Atlantic

Harbor seal

Phoca vitulina

Western North Atlantic

§ 217.333 Prohibitions.
Except for the takings described in § 217.332 and authorized by a LOA issued
under §§ 217.336 or 217.337, it is unlawful for any person to do any of the following in
connection with the activities described in this subpart.
(a) Violate or fail to comply with the terms, conditions, and requirements of this
subpart or a LOA issued under §§ 217.336 or 217.337.
(b) Take any marine mammal not specified in § 217.332(c).
(c) Take any marine mammal specified in § 217.332(c) in any manner other than
specified in § 217.332(a) and (b).
§ 217.334 Mitigation requirements.
When conducting the specified activities identified in §§ 217.330(c), SouthCoast
Wind must implement the following mitigation measures contained in this section and
any LOA issued under §§ 217.336 or 217.337 of this subpart. These mitigation measures
include, but are not limited to:
(a) General Conditions. SouthCoast Wind must comply with the following
general measures:
(1) A copy of any issued LOA must be in the possession of SouthCoast Wind and
its designees, all vessel operators, visual protected species observers (PSOs), passive
acoustic monitoring (PAM) operators, pile driver operators, and any other relevant
designees operating under the authority of the issued LOA;
(2) SouthCoast Wind must conduct training for construction supervisors,
construction crews, and the PSO and PAM team prior to the start of all construction
activities and when new personnel join the work in order to explain responsibilities,

communication procedures, marine mammal monitoring and reporting protocols, and
operational procedures. A description of the training program must be provided to NMFS
at least 60 days prior to the initial training before in-water activities begin. Confirmation
of all required training must be documented on a training course log sheet and reported to
NMFS Office of Protected Resources prior to initiating project activities;
(3) SouthCoast Wind is required to use available sources of information on North
Atlantic right whale presence to aid in monitoring efforts. These include daily monitoring
of the Right Whale Sighting Advisory System, consulting of the WhaleAlert app, and
monitoring of the Coast Guard's VHF Channel 16 to receive notifications of marine
mammal sightings and information associated with any Dynamic Management Areas
(DMA) and Slow Zones;
(4) Any marine mammal observation by project personnel must be immediately
communicated to any on-duty PSOs and PAM operator(s). Any large whale observation
or acoustic detection by any project personnel must be conveyed to all vessel captains;
(5) If an individual from a species for which authorization has not been granted or
a species for which authorization has been granted but the authorized take number has
been met is observed entering or within the relevant clearance zone prior to beginning a
specified activity, the activity must be delayed. If an activity is ongoing and an individual
from a species for which authorization has not been granted or a species for which
authorization has been granted but the authorized take number has been met is observed
entering or within the relevant shutdown zone, the activity must be shut down (i.e., cease)
immediately unless shutdown would result in imminent risk of injury or loss of life to an
individual, pile refusal, or pile instability. The activity must not commence or resume
until the animal(s) has been confirmed to have left the clearance or shutdown zones and
is on a path away from the applicable zone or after 30 minutes for all baleen whale
species and sperm whales, and 15 minutes for all other species;

(6) In the event that a large whale is sighted or acoustically detected that cannot
be confirmed as a non-North Atlantic right whale, it must be treated as if it were a North
Atlantic right whale for purposes of mitigation;
(7) For in-water construction heavy machinery activities listed in section 1(a), if a
marine mammal is detected within or about to enter 10 meters (m) (32.8 feet (ft)) of
equipment, SouthCoast Wind must cease operations until the marine mammal has moved
more than 10 m on a path away from the activity to avoid direct interaction with
equipment;
(8) All vessels must be equipped with a properly installed, operational Automatic
Identification System (AIS) device prior to vessel use and SouthCoast Wind must report
all Maritime Mobile Service Identify (MMSI) numbers to NMFS Office of Protected
Resources;
(9) By accepting a LOA, SouthCoast Wind consents to on-site observation and
inspections by Federal agency personnel (including NOAA personnel) during activities
described in this subpart, for the purposes of evaluating the implementation and
effectiveness of measures contained within this subpart and the LOA; and
(10) It is prohibited to assault, harm, harass (including sexually harass), oppose,
impede, intimidate, impair, or in any way influence or interfere with a PSO, PAM
operator, or vessel crew member acting as an observer, or attempt the same. This
prohibition includes, but is not limited to, any action that interferes with an observer's
responsibilities or that creates an intimidating, hostile, or offensive environment.
Personnel may report any violations to the NMFS Office of Law Enforcement.
(b) Vessel strike avoidance measures: SouthCoast Wind must comply with the
following vessel strike avoidance measures while in the specific geographic region unless
a deviation is necessary to maintain safe maneuvering speed and justified because the
vessel is in an area where oceanographic, hydrographic, and/or meteorological conditions

severely restrict the maneuverability of the vessel; an emergency situation presents a
threat to the health, safety, life of a person; or when a vessel is actively engaged in
emergency rescue or response duties, including vessel-in distress or environmental crisis
response. An emergency is defined as a serious event that occurs without warning and
requires immediate action to avert, control, or remedy harm.
(1) Prior to the start of the Project’s activities involving vessels, all vessel
personnel must receive a protected species training that covers, at a minimum,
identification of marine mammals that have the potential to occur in the specified
geographical region; detection and observation methods in both good weather conditions
(i.e., clear visibility, low winds, low sea states) and bad weather conditions (i.e., fog, high
winds, high sea states, with glare); sighting communication protocols; all vessel strike
avoidance mitigation requirements; and information and resources available to the project
personnel regarding the applicability of Federal laws and regulations for protected
species. This training must be repeated for any new vessel personnel who join the project.
Confirmation of the vessel personnels’ training and understanding of the LOA
requirements must be documented on a training course log sheet and reported to NMFS
within 30 days of completion of training, prior to personnel joining vessel operations;
(2) All vessel operators and dedicated visual observers must maintain a vigilant
watch for all marine mammals and slow down, stop their vessel, or alter course to avoid
striking any marine mammal;
(3) All transiting vessels, operating at any speed must have a dedicated visual
observer on duty at all times to monitor for marine mammals within a 180 degrees (°)
direction of the forward path of the vessel (90° port to 90° starboard) located at an
appropriate vantage point for ensuring vessels are maintaining required separation
distances. Dedicated visual observers may be PSOs or crew members, but crew members
responsible for these duties must be provided sufficient training by SouthCoast Wind to

distinguish marine mammals from other phenomena and must be able to identify a
marine mammal as a North Atlantic right whale, other large whale (defined in this
context as sperm whales or baleen whales other than North Atlantic right whales), or
other marine mammals. Dedicated visual observers must be equipped with alternative
monitoring technology (e.g., night vision devices, infrared cameras) for periods of low
visibility (e.g., darkness, rain, fog, etc.). The dedicated visual observer must not have any
other duties while observing and must receive prior training on protected species
detection and identification, vessel strike avoidance procedures, how and when to
communicate with the vessel captain, and reporting requirements in this subpart;
(4) All vessel operators and dedicated visual observers must continuously monitor
US Coast Guard VHF Channel 16 at the onset of transiting through the duration of
transit. At the onset of transiting and at least once every 4 hours, vessel operators and/or
trained crew member(s) must also monitor the project’s Situational Awareness System,
(if applicable), WhaleAlert, and relevant NOAA information systems such as the Right
Whale Sighting Advisory System (RWSAS) for the presence of North Atlantic right
whales;
(5) Prior to transit, vessel operators must check for information regarding the
establishment of Seasonal and Dynamic Management Areas, Slow Zones, and any
information regarding North Atlantic right whale sighting locations;
(6) All vessel operators must abide by vessel speed regulations (50 CFR 224.105).
Nothing in this subpart exempts vessels from any other applicable marine mammal speed
or approach regulations;
(7) All vessels, regardless of size, must immediately reduce speed to 10 knots
(18.5 km/hr) or less for at least 24 hours when a North Atlantic right whale is sighted at
any distance by any project related personnel or acoustically detected by any projectrelated PAM system. Each subsequent observation or acoustic detection in the Project

area must trigger an additional 24-hour period. If a North Atlantic right whale is reported
via any of the monitoring systems (described in paragraph (b)(4) of this section) within
10 km of a transiting vessel(s), that vessel must operate at 10 knots (18.5 km/hr) or less
for 24 hours following the reported detection.
(8) In the event that a DMA or Slow Zone is established that overlaps with an area
where a project-associated vessel is operating, that vessel, regardless of size, must transit
that area at 10 knots (18.5 km/hr) or less;
(9) Between November 1st and April 30th, all vessels, regardless of size, must
operate at 10 knots (18.5 km/hr) or less in the specified geographical region, except for
vessels while transiting in Narragansett Bay or Long Island Sound;
(10) All vessels, regardless of size, must immediately reduce speed to 10 knots
(18.5 km/hr) or less when any large whale, (other than a North Atlantic right whale),
mother/calf pairs, or large assemblages of non-delphinid cetaceans are observed within
500 m (0.31 mi) of a transiting vessel;
(11) If a vessel is traveling at any speed greater than 10 knots (18.5 km/hr) (i.e.,
no speed restrictions are enacted) in the transit corridor (defined as from a port to the
Lease Area or return), in addition to the required dedicated visual observer, SouthCoast
Wind must monitor the transit corridor in real-time with PAM prior to and during
transits. If a North Atlantic right whale is detected via visual observation or PAM within
or approaching the transit corridor, all vessels in the transit corridor must travel at 10
knots (18.5 km/hr) or less for 24 hours following the detection. Each subsequent
detection shall trigger a 24-hour reset. A slowdown in the transit corridor expires when
there has been no further North Atlantic right whale visual or acoustic detection in the
transit corridor in the past 24 hours;
(12) All vessels must maintain a minimum separation distance of 500 m from
North Atlantic right whales. If underway, all vessels must steer a course away from any

sighted North Atlantic right whale at 10 knots (18.5 km/hr) or less such that the 500-m
minimum separation distance requirement is not violated. If a North Atlantic right whale
is sighted within 500 m of an underway vessel, that vessel must turn away from the
whale(s), reduce speed and shift the engine to neutral. Engines must not be engaged until
the whale has moved outside of the vessel’s path and beyond 500 m;
(13) All vessels must maintain a minimum separation distance of 100 m (328 ft)
from sperm whales and non-North Atlantic right whale baleen whales. If one of these
species is sighted within 100 m (328 ft) of an underway vessel, the vessel must turn away
from the whale(s), reduce speed, and shift the engine(s) to neutral. Engines must not be
engaged until the whale has moved outside of the vessel’s path and beyond 100 m (328
ft);
(14) All vessels must maintain a minimum separation distance of 50 m (164 ft)
from all delphinid cetaceans and pinnipeds with an exception made for those that
approach the vessel (e.g., bow-riding dolphins). If a delphinid cetacean or pinniped is
sighted within 50 m (164 ft) of a transiting vessel, that vessel must turn away from the
animal(s), reduce speed, and shift the engine to neutral, with an exception made for those
that approach the vessel (e.g., bow-riding dolphins). Engines must not be engaged until
the animal(s) has moved outside of the vessel’s path and beyond 50 m (164 ft);
(15) All vessels underway must not divert or alter course to approach any marine
mammal; and
(16) SouthCoast Wind must submit a Marine Mammal Vessel Strike Avoidance
Plan 180 days prior to the planned start of vessel activity that provides details on all
relevant mitigation and monitoring measures for marine mammals, vessel speeds and
transit protocols from all planned ports, vessel-based observer protocols for transiting
vessels, communication and reporting plans, and proposed alternative monitoring
equipment in varying weather conditions, darkness, sea states, and in consideration of the

use of artificial lighting. If SouthCoast Wind plans to implement PAM in any transit
corridor to allow vessel transit above 10 knots (18.5 km/hr) the plan must describe how
PAM, in combination with visual observations, will be conducted. If a plan is not
submitted and approved by NMFS prior to vessel operations, all project vessels must
travel at speeds of 10 knots (18.5 km/hr) or less. SouthCoast Wind must comply with any
approved Marine Mammal Vessel Strike Avoidance Plan.
(c) Wind turbine generator (WTG) and offshore substation platform (OSP)
foundation installation. The following requirements apply to vibratory and impact pile
driving activities associated with the installation of WTG and OSP foundations:
(1) Foundation pile driving activities must not occur January 1 through May 15
throughout the Lease Area. From October 16 through May 31, impact and vibratory pile
driving must not occur at locations in SouthCoast’s Lease Area within the North Atlantic
right whale Enhanced Mitigation Area (NARW EMA; defined as the area within 20 km
(12.4 mi) from the 30-m (98-ft) isobath on the west side of Nantucket Shoals);
(2) Outside of the NARW EMA, foundation pile driving must not be planned for
December; however, it may occur only if necessary to complete pile driving within a
given year and with prior approval by NMFS and implementation of enhanced mitigation
and monitoring (see 217.334(c)(7), 217.334(c)(13)). SouthCoast Wind must notify
NMFS in writing by September 1 of that year if circumstances are expected to necessitate
pile driving in December;
(3) In the NARW EMA, SouthCoast must install foundations as quickly as
possible and sequence them from the northeast corner of the Lease Area to the southwest
corner such that foundation installation in positions closest to Nantucket Shoals are
completed during the period of lowest North Atlantic right whale occurrence in that area;
(4) Monopiles must be no larger than a tapered 9/16-m diameter monopile design
and pin piles must be no larger than 4.5-m diameter design. The minimum amount of

hammer energy necessary to effectively and safely install and maintain the integrity of
the piles must be used. Impact hammer energies must not exceed 6,600 kilojoules (kJ) for
monopile installations and 3,500 kJ for pin pile installations;
(5) SouthCoast must not initiate pile driving earlier than 1 hour after civil sunrise
or later than 1.5 hours prior to civil sunset unless SouthCoast submits and NMFS
approves a Nighttime Pile Driving Monitoring Plan that demonstrates the efficacy of their
low-visibility visual monitoring technology (e.g., night vision devices, Infrared (IR)
cameras) to effectively monitor the mitigation zones in low visibility conditions.
SouthCoast must submit this plan or plans (if separate Daytime Reduced Visibility and
Nighttime Monitoring Plans are prepared) at least 180 calendar days before foundation
installation is planned to begin. SouthCoast must submit a separate Plan describing
daytime reduced visibility monitoring if the information in the Nighttime Monitoring
Plan does not sufficiently apply to all low-visibility monitoring;
(6) SouthCoast Wind must utilize a soft-start protocol at the beginning of
foundation installation for each impact pile driving event and at any time following a
cessation of impact pile driving for 30 minutes or longer;
(7) SouthCoast Wind must deploy, at minimum, a double bubble curtain during
all foundation pile driving;
(i) The double bubble curtain must distribute air bubbles using an air flow rate of
at least 0.5 m3/(min*m). The double bubble curtain must surround 100 percent of the
piling perimeter throughout the full depth of the water column. In the unforeseen event of
a single compressor malfunction, the offshore personnel operating the bubble curtain(s)
must make adjustments to the air supply and operating pressure such that the maximum
possible sound attenuation performance of the bubble curtain(s) is achieved;
(ii) The lowest bubble ring must be in contact with the seafloor for the full
circumference of the ring, and the weights attached to the bottom ring must ensure 100-

percent seafloor contact.
(iii) No parts of the ring or other objects may prevent full seafloor contact with a
bubble curtain ring.
(iv) SouthCoast Wind must inspect and carry out maintenance on the noise
attenuation systems prior to every pile driving event and prepare and submit a Noise
Attenuation System (NAS) inspection/performance report. For piles for which Thorough
SFV (T-SFV) (as required by 217.334(c)(19)) is carried out, this report must be
submitted as soon as it is available, but no later than when the interim T-SFV report is
submitted for the respective pile. Performance reports for all subsequent piles must be
submitted with the weekly pile driving reports. All reports must be submitted by email to
pr.itp.monitoringreports@noaa.gov.
(8) SouthCoast Wind must utilize PSOs. Each monitoring platform must have at
least three on-duty PSOs. PSOs must be located on the pile driving vessel as well as on a
minimum of three PSO-dedicated vessels inside the NARW EMA June 1 through July 31
and outside the NARW EMA June 1 through November 30, and a minimum of four PSOdedicated vessels within the NARW EMA from August 1 through October 15 and
throughout the Lease Area from May 16-31 and December 1-31 (if pile driving in
December is deemed necessary and approved by NMFS);
(9) Concurrent with visual monitoring, SouthCoast Wind must utilize PAM
operator(s), as described in a NMFS-approved PAM Plan, who must conduct acoustic
monitoring of marine mammals for 60 minutes before, during, and 30 minutes after
completion of impact and vibratory pile driving for each pile. PAM operators must
immediately communicate all detections of marine mammals to the Lead PSO, including
any determination regarding species identification, distance, and bearing and the degree
of confidence in the determination;

(10) To increase situational awareness prior to pile driving, the PAM operator
must review PAM data collected within the 24 hours prior to a pile installation;
(11) The PAM system must be able to detect marine mammal vocalizations,
maximize baleen whale detections, and detect North Atlantic right whale vocalizations up
to a distance of 10 km (6.2 mi) and 15 km (9.3mi) during pin pile and monopile
installation, respectively. NMFS recognizes that detectability of each species’
vocalizations will vary based on vocalization characteristics (e.g., frequency content,
source level), acoustic propagation conditions, and competing noise sources), such that
other marine mammal species (e.g., harbor porpoise) may not be detected at 10 km (6.2
mi) or 15 km (9.3 mi);
(12) SouthCoast Wind must submit a Passive Acoustic Monitoring Plan (PAM
Plan) to NMFS Office of Protected Resources for review and approval at least 180 days
prior to the planned start of foundation installation activities and abide by the Plan if
approved;
(13) SouthCoast Wind must establish clearance and shutdown zones, which must
be measured using the radial distance from the pile being driven. All clearance zones
must be confirmed to be free of marine mammals for 30 minutes immediately prior to the
beginning of soft-start procedures or vibratory pile driving. If a marine mammal (other
than a North Atlantic right whale) is detected within or about to enter the applicable
clearance zones during this 30-minute time period, vibratory and impact pile driving must
be delayed until the animal has been visually observed exiting the clearance zone or until
a specific time period has elapsed with no further sightings. The specific time periods are
30 minutes for all baleen whale species and sperm whales and 15 minutes for all other
species;
(14) For North Atlantic right whales, any visual observation by a PSO at any
distance, or acoustic detection within the 10-km (6.2-mi) (pin pile) and 15-km (9.32-mi)

(monopile) PAM clearance and shutdown zones must trigger a delay to the
commencement or shutdown (if already begun) of pile driving. For any acoustic detection
within the North Atlantic right whale PAM clearance and shutdown zones or sighting of
1 or 2 North Atlantic right whales, SouthCoast Wind must delay commencement of or
shutdown pile driving for 24 hours. For any sighting of 3 or more North Atlantic right
whales, SouthCoast Wind must delay commencement of or shutdown pile driving for 48
hours. Prior to beginning clearance at the pile driving location after these periods,
SouthCoast must conduct a vessel-based survey to visually clear the 10-km (6.2-mi)
zone, if installing pin piles that day, or 15-km (9.32-mi) zone, if installing monopiles.
(15) If visibility decreases such that the entire clearance zone is not visible, at
minimum, PSOs must be able to visually clear (i.e., confirm no marine mammals are
present) the minimum visibility zone. The entire minimum visibility zone must be visible
(i.e., not obscured by dark, rain, fog, etc.) for the full 60 minutes immediately prior to
commencing impact and vibratory pile driving;
(16) If a marine mammal is detected (visually or acoustically) entering or within
the respective shutdown zone after pile driving has begun, the PSO or PAM operator
must call for a shutdown of pile driving and SouthCoast Wind must stop pile driving
immediately, unless shutdown is not practicable due to imminent risk of injury or loss of
life to an individual or risk of damage to a vessel that creates risk of injury or loss of life
for individuals, or the lead engineer determines there is risk of pile refusal or pile
instability. If pile driving is not shut down due to one of these situations, SouthCoast
Wind must reduce hammer energy to the lowest level practicable to maintain stability;
(17) If pile driving has been shut down due to the presence of a marine mammal
other than a North Atlantic right whale, pile driving must not restart until either the
marine mammal(s) has voluntarily left the species-specific clearance zone and has been
visually or acoustically confirmed beyond that clearance zone, or, when specific time

periods have elapsed with no further sightings or acoustic detections. The specific time
periods are 30 minutes for all non-North Atlantic right whale baleen whale species and
sperm whales and 15 minutes for all other species. In cases where these criteria are not
met, pile driving may restart only if necessary to maintain pile stability at which time
SouthCoast Wind must use the lowest hammer energy practicable to maintain stability;
(18) SouthCoast Wind must submit a Pile Driving Marine Mammal Monitoring
Plan to NMFS Office of Protected Resources for review and approval at least 180 days
prior to planned start of foundation pile driving and abide by the Plan if approved.
SouthCoast Wind must obtain both NMFS Office of Protected Resources and NMFS
Greater Atlantic Regional Fisheries Office Protected Resources Division’s concurrence
with this Plan prior to the start of any pile driving;
(19) SouthCoast Wind must perform T-SFV measurements during installation of,
at minimum, the first three WTG monopile foundations, first four WTG pin piles, and all
OSP jacket foundation pin piles;
(i) T-SFV measurements must continue until at least three consecutive monopiles
or four consecutive pin piles demonstrate noise levels are at or below those modeled,
assuming 10 decibels (dB) of attenuation. Subsequent T-SFV measurements are also
required should larger piles be installed or if additional monopiles or pin piles are driven
that may produce louder sound fields than those previously measured (e.g., from higher
hammer energy, greater number of strikes);
(ii) T-SFV measurements must be made at a minimum of four distances from the
pile(s) being driven along a single transect in the direction of lowest transmission loss
(i.e., projected lowest transmission loss coefficient), including, but not limited to, 750 m
(2,460 ft) and three additional ranges selected such that measurement of modeled Level A
harassment and Level B harassment isopleths are accurate, feasible, and avoids
extrapolation (i.e., recorder spacing is approximately logarithmic and significant gaps

near expected isopleths are avoided). At least one additional measurement at an azimuth
90 degrees from the transect array at 750 m (2,460 ft) must be made. At each location,
there must be a near bottom and mid-water column hydrophone (acoustic recorder);
(iii) If any of the T-SFV results indicate that distances to harassment isopleths
were exceeded, then SouthCoast Wind must implement additional measures for all
subsequent foundation installations to ensure the measured distances to the Level A
harassment and Level B harassment threshold isopleths do not exceed those modeled
assuming 10 dB attenuation. SouthCoast Wind must also increase clearance, shutdown,
and/or Level B harassment zone sizes to those identified by NMFS until T-SFV
measurements on at least three additional monopiles or four pin piles demonstrate
distances to harassment threshold isopleths meet or are less than those modeled assuming
10-dB of attenuation. For every 1,500 m (4,900 ft) that a marine mammal clearance or
shutdown zone is expanded, additional PSOs must be deployed from additional
platforms/vessels to ensure adequate and complete monitoring of the expanded clearance
and/or shutdown zone(s), with each PSO responsible for scanning no more than 120
degrees (°) out to a radius no greater than 1,500 m (4,900 ft). SouthCoast Wind must
optimize the sound attenuation systems (e.g., ensure hose maintenance, pressure testing,
etc.) to, at least, meet noise levels modeled, assuming 10-dB attenuation, within three
monopiles or four pin piles, or else foundation installation activities must cease until
NMFS and SouthCoast Wind can evaluate potential reasons for louder than anticipated
noise levels. Alternatively, if SouthCoast determines T-SFV results demonstrate noise
levels are within those modeled assuming 10 dB attenuation, SouthCoast may proceed to
the next pile after submitting the interim report to NMFS;
(20) SouthCoast Wind also must conduct abbreviated SFV, using at least one
acoustic recorder (consisting of a bottom and mid-water column hydrophone) for every
foundation for which T-SFV monitoring is not conducted. All abbreviated SFV data must

be included in weekly reports. Any indications that distances to the identified Level A
harassment and Level B harassment thresholds for marine mammals may be exceeded
based on this abbreviated monitoring must be addressed by SouthCoast Wind in the
weekly report, including an explanation of factors that contributed to the exceedance and
corrective actions that were taken to avoid exceedance on subsequent piles. SouthCoast
Wind must meet with NMFS within two business days of SouthCoast Wind’s submission
of a report that includes an exceedance to discuss if any additional action is necessary;
(21) The SFV measurement systems must have a sensitivity for the expected
sound levels from pile driving received at the nominal ranges throughout the installation
of the pile. The frequency range of SFV measurement systems must cover the range of at
least 20 hertz (Hz) to 20 kilohertz (kHz). The SFV measurement systems must be
designed to have omnidirectional sensitivity so that the broadband received level of all
pile driving exceeds the system noise floor by at least 10 dB. The dynamic range of the
SFV measurement system must be sufficient such that at each location, and the signals
avoid poor signal-to-noise ratios for low amplitude signals and avoid clipping,
nonlinearity, and saturation for high amplitude signals;
(22) SouthCoast must ensure that all hydrophones used in pile installation SFV
measurements systems have undergone a full system, traceable laboratory calibration
conforming to International Electrotechnical Commission (IEC) 60565, or an equivalent
standard procedure from a factory or accredited source, at a date not to exceed 2 years
before deployment, to guarantee each hydrophone receives accurate sound levels.
Additional in situ calibration checks using a pistonphone must be performed before and
after each hydrophone deployment. If the measurement system employs filters via
hardware or software (e.g., high-pass, low-pass, etc.), which is not already accounted for
by the calibration, the filter performance (i.e., the filter’s frequency response) must be
known, reported, and the data corrected for the filter’s effect before analysis;

(23) SouthCoast Wind must be prepared with additional equipment (e.g.,
hydrophones, recording devices, hydrophone calibrators, cables, batteries), which
exceeds the amount of equipment necessary to perform the measurements, such that
technical issues can be mitigated before measurement;
(24) If any of the SFV measurements from any pile indicate that the distance to
any isopleth of concern is greater than those modeled assuming 10-dB attenuation, before
the next pile is installed, SouthCoast Wind must implement the following measures, as
applicable: identify and propose for review and concurrence; additional, modified, and/or
alternative noise attenuation measures or operational changes that present a reasonable
likelihood of reducing sound levels to the modeled distances; provide a written
explanation to NMFS Office of Protected Resources supporting that determination, and
request concurrence to proceed; and, following NMFS Office of Protected Resources’
concurrence, deploy those additional measures on any subsequent piles that are installed
(e.g., if threshold distances are exceeded on pile 1, then additional measures must be
deployed before installing pile 2);
(25) If SFV measurements indicate that ranges to isopleths corresponding to the
Level A harassment and Level B harassment thresholds are less than the ranges predicted
by modeling (assuming 10-dB attenuation) for 3 consecutive monopiles or 4 consecutive
pin piles, SouthCoast Wind may submit a request to NMFS Office of Protected
Resources for a modification of the mitigation zones for non-North Atlantic right whale
species. Mitigation zones for North Atlantic right whales cannot be decreased;
(26) SouthCoast must measure background noise (i.e., noise absent pile driving)
for 30 minutes before and after each pile installation;
(27) SouthCoast must conduct SFV measurements upon commencement of
turbine operations to estimate turbine operational source levels, in accordance with a
NMFS-approved Foundation Installation Pile Driving SFV Plan. SFV must be conducted

in the same manner as previously described in paragraph (13) of this section, with
adjustments to measurement distances, number of hydrophones, and hydrophone
sensitivities being made, as necessary; and
(28) SouthCoast Wind must submit a SFV Plan for thorough and abbreviated SFV
for foundation installation and WTG operations to NMFS Office of Protected Resources
for review and approval at least 180 days prior to planned start of foundation installation
activities and abide by the Plan if approved. Pile driving may not occur until NMFS
provides SouthCoast concurrence that implementation of the SFV Plan meets the
requirements in the LOA.
(d) UXO/MEC detonation.The following requirements apply to Unexploded
Ordnances and Munitions and Explosives of Concern (UXO/MEC) detonation:
(1) Upon encountering a UXO/MEC, SouthCoast Wind can only resort to highorder removal (i.e., detonation) if all other means of removal are impracticable (i.e., As
Low As Reasonably Practicable (ALARP) risk mitigation procedure)) and this
determination must be documented and submitted to NMFS;
(2) UXO/MEC detonations must not occur from December 1 through April 30;
(3) UXO/MEC detonations must only occur during daylight hours (1 hour after
civil sunrise through 1.5 hours prior to civil sunset);
(4) No more than one detonation can occur within a 24-hour period. No more than
10 detonations may occur throughout the effective period of these regulations;
(5) SouthCoast Wind must deploy, at minimum, a double bubble curtain during
all UXO/MEC detonations and comply with the following requirements related to noise
abatement:
(i) The bubble curtain(s) must distribute air bubbles using an air flow rate of at
least 0.5 m3/(min*m). The bubble curtain(s) must surround 100 percent of the UXO/MEC
detonation perimeter throughout the full depth of the water column. In the unforeseen

event of a single compressor malfunction, the offshore personnel operating the bubble
curtain(s) must make adjustments to the air supply and operating pressure such that the
maximum possible noise attenuation performance of the bubble curtain(s) is achieved;
(ii) The lowest bubble ring must be in contact with the seafloor for the full
circumference of the ring, and the weights attached to the bottom ring must ensure 100percent seafloor contact;
(iii) No parts of the ring or other objects may prevent full seafloor contact;
(iv) Construction contractors must train personnel in the proper balancing of
airflow to the ring. Construction contractors must submit an inspection/performance
report for approval by SouthCoast Wind within 72 hours following the performance test.
SouthCoast Wind must then submit that report to NMFS Office of Protected Resources;
(v) Corrections to the bubble ring(s) to meet the performance standards in this
paragraph (5) must occur prior to UXO/MEC detonations. If SouthCoast Wind uses a
noise mitigation device in addition to the bubble curtain, SouthCoast Wind must maintain
similar quality control measures as described in this paragraph (5); and
(vi) SouthCoast Wind must inspect and carry out maintenance on the noise
attenuation system prior to every UXO/MEC detonation and prepare and submit a Noise
Attenuation System (NAS) inspection/performance report as soon as it is available and
prior to the UXO/MEC detonation to NMFS Office of Protected Resources.
(6) SouthCoast Wind must conduct SFV during all UXO/MEC detonations at a
minimum of three locations (at two water depths at each location) from each detonation
in a direction toward deeper water in accordance with the following requirements:
(i) SouthCoast Wind must empirically determine source levels (peak and
cumulative sound exposure level), the ranges to the isopleths corresponding to the Level
A harassment and Level B harassment threshold isopleths in meters and the transmission
loss coefficient(s). SouthCoast Wind may estimate ranges to the Level A harassment and

Level B harassment isopleths by extrapolating from in situ measurements conducted at
several distances from the detonation location monitored;
(ii) The SFV measurement systems must have a sensitivity for the expected sound
levels from detonations received at the nominal ranges throughout the detonation. The
dynamic range of the SFV measurement systems must be sufficient such that at each
location, the signals avoid poor signal-to-noise ratios for low amplitude signals and the
signals avoid clipping, nonlinearity, and saturation for high amplitude signals;
(iii) All hydrophones used in UXO/MEC SFV measurements systems are required
to have undergone a full system, traceable laboratory calibration conforming to
International Electrotechnical Commission (IEC) 60565, or an equivalent standard
procedure, from a factory or accredited source to ensure the hydrophone receives
accurate sound levels, at a date not to exceed 2 years before deployment. Additional insitu calibration checks using a pistonphone are required to be performed before and after
each hydrophone deployment. If the measurement system employs filters via hardware or
software (e.g., high-pass, low-pass, etc.), which is not already accounted for by the
calibration, the filter performance (i.e., the filter’s frequency response) must be known,
reported, and the data corrected before analysis;
(iv) SouthCoast Wind must be prepared with additional equipment (hydrophones,
recording devices, hydrophone calibrators, cables, batteries, etc.), which exceeds the
amount of equipment necessary to perform the measurements, such that technical issues
can be mitigated before measurement;
(v) SouthCoast Wind must submit SFV reports within 72 hours after each
UXO/MEC detonation;
(vi) If acoustic field measurements collected during UXO/MEC detonation
indicate ranges to the isopleths, corresponding to Level A harassment and Level B
harassment thresholds, are greater than the ranges predicted by modeling (assuming 10

dB attenuation), SouthCoast Wind must implement additional noise mitigation measures
prior to the next UXO/MEC detonation. SouthCoast Wind must provide written
notification to NMFS Office of Protected Resources of the changes planned for the next
detonation within 24 hours of implementation. Subsequent UXO/MEC detonation
activities must not occur until NMFS and SouthCoast Wind can evaluate the situation and
ensure future detonations will not exceed noise levels modeled assuming 10-dB
attenuation; and
(vii) SouthCoast Wind must optimize the noise attenuation systems (e.g., ensure
hose maintenance, pressure testing) to, at least, meet noise levels modeled, assuming 10dB attenuation.
(7) SouthCoast Wind must establish and implement clearance zones for
UXO/MEC detonation using both visual and acoustic monitoring;
(8) At least three on-duty PSOs must be stationed on each monitoring platform
and be monitoring for 60 minutes prior to, during, and 30 minutes after each UXO/MEC
detonation. The number of platforms is contingent upon the size of the UXO/MEC
detonation to be identified in SouthCoast’s UXO/MEC Detonation Marine Mammal
Monitoring Plan and must be sufficient such that PSOs are able to visually clear the
entire clearance zone. Concurrently, at least one PAM operator must be actively
monitoring for marine mammals with PAM 60 minutes before, during, and 30 minutes
after detonation; and
(9) All clearance zones must be confirmed to be acoustically free of marine
mammals for 30 minutes prior to a detonation. If a marine mammal is observed entering
or within the relevant clearance zone prior to the initiation of a detonation, detonation
must be delayed and must not begin until either the marine mammal(s) has voluntarily
left the specific clearance zones and have been visually and acoustically confirmed
beyond that clearance zone, or, when specific time periods have elapsed with no further

sightings or acoustic detections. The specific time periods are 30 minutes for all baleen
whale species and sperm whales and 15 minutes for all other species.
(e) HRG surveys. The following requirements apply to HRG surveys operating
sub-bottom profilers (SBPs) (e.g., boomers, sparkers, and Compressed High Intensity
Radiated Pulse (CHIRPS)) (hereinafter referred to as “acoustic sources”):
(1) SouthCoast Wind must establish and implement clearance and shutdown
zones for HRG surveys using visual monitoring. These zones must be measured using the
radial distance(s) from the acoustic source(s) currently in use;
(2) SouthCoast must utilize PSO(s), as described in § 217.335(e). Visual
monitoring must begin no less than 30 minutes prior to initiation of specified acoustic
sources and must continue until 30 minutes after use of specified acoustic sources ceases.
Any PSO on duty has the authority to delay the start of survey operations or shutdown
operations if a marine mammal is detected within the applicable zones. When delay or
shutdown is instructed by a PSO, the mitigative action must be taken and any dispute
resolved only following deactivation;
(3) Prior to starting the survey and after receiving confirmation from the PSOs
that the clearance zone is clear of any marine mammals, SouthCoast Wind is required to
ramp-up acoustic sources to half power for 5 minutes prior to commencing full power,
unless the equipment operates on a binary on/off switch (in which case ramp-up is not
required). Any ramp-up of acoustic sources may only commence when visual clearance
zones are fully visible (e.g., not obscured by darkness, rain, fog, etc.) and clear of marine
mammals, as determined by the Lead PSO, for at least 30 minutes immediately prior to
the initiation of survey activities using a specified acoustic source. Ramp-ups must be
scheduled so as to minimize the time spent with the source activated;
(4) Prior to a ramp-up procedure starting, the acoustic source operator must notify
the Lead PSO of the planned start of ramp-up. The notification time must not be less than

60 minutes prior to the planned ramp-up or activation in order to allow the PSO(s) time to
monitor the clearance zone(s) for 30 minutes prior to the initiation of ramp-up or
activation (pre-start clearance). During this 30-minute clearance period, the entire
applicable clearance zones must be visible;
(5) A PSO conducting clearance observations must be notified again immediately
prior to reinitiating ramp-up procedures and the operator must receive confirmation from
the PSO to proceed;
(6) If a marine mammal is observed within a clearance zone during the 30 minute
clearance period, ramp-up or acoustic surveys may not begin until the animal(s) has been
observed voluntarily exiting its respective clearance zone or until a specific time period
has elapsed with no further sighting. The specific time periods are 30 minutes for all
baleen whale species and sperm whales and 15 minutes for all other species;
(7) In any case when the clearance process has begun in conditions with good
visibility, including via the use of night vision/reduced visibility monitoring equipment
(infrared (IR)/thermal camera), and the Lead PSO has determined that the clearance
zones are clear of marine mammals, survey operations may commence (i.e., no delay is
required) despite periods of inclement weather and/or loss of daylight. Ramp-up may
occur at times of poor visibility, including nighttime, if required visual monitoring has
occurred with no detections of marine mammals in the 30 minutes prior to beginning
ramp-up;
(8) Once the survey has commenced, SouthCoast Wind must shut down acoustic
sources if a marine mammal enters a respective shutdown zone. In cases when the
shutdown zones become obscured for brief periods (less than 30 minutes) due to
inclement weather, survey operations would be allowed to continue (i.e., no shutdown is
required) so long as no marine mammals have been detected. The shutdown requirement
does not apply to small delphinids of the following genera: Delphinus, Stenella,

Lagenorhynchus, and Tursiops. If there is uncertainty regarding the identification of a
marine mammal species (i.e., whether the observed marine mammal belongs to one of the
delphinid genera for which shutdown is waived), the PSOs must use their best
professional judgment in making the decision to call for a shutdown. Shutdown is
required if a delphinid that belongs to a genus other than those specified in this paragraph
of this section is detected in the shutdown zone;
(9) If an acoustic source has been shut down due to the presence of a marine
mammal, the use of an acoustic source may not commence or resume until the animal(s)
has been confirmed to have left the Level B harassment zone or until a full 30 minutes for
all baleen whale species and sperm whales and 15 minutes for all other species have
elapsed with no further sighting. If an acoustic source is shut down for reasons other than
mitigation (e.g., mechanical difficulty) for less than 30 minutes, it may be activated again
without ramp-up only if PSOs have maintained constant observation and no additional
detections of any marine mammal occurred within the respective shutdown zones. If an
acoustic source is shut down for a period longer than 30 minutes, then all clearance and
ramp-up procedures must be initiated;
(10) If multiple HRG vessels are operating concurrently, any observations of
marine mammals must be communicated to PSOs on all nearby survey vessels; and
(11) Should an autonomous survey vehicle (ASV) be used during HRG surveys,
the ASV must remain with 800 m (2,635 ft) of the primary vessel while conducting
survey operations; two PSOs must be stationed on the mother vessel at the best vantage
points to monitor the clearance and shutdown zones around the ASV; at least one PSO
must monitor the output of a thermal high-definition camera installed on the mother
vessel to monitor the field-of-view around the ASV using a hand-held tablet, and during
periods of reduced visibility (e.g., darkness, rain, or fog), PSOs must use night-vision

goggles with thermal clip-ons and a hand-held spotlight to monitor the clearance and
shutdown zones around the ASV.
(f) Fisheries Monitoring Surveys. The following measures apply during fisheries
monitoring surveys and must be implemented by SouthCoast Wind:
(1) Marine mammal monitoring must be conducted within 1 nmi (1.85 km) from
the planned survey location by the trained captain and/or a member of the scientific crew
for 15 minutes prior to deploying gear, throughout gear deployment and use, and for 15
minutes after haul back;
(2) All captains and crew conducting fishery surveys must be trained in marine
mammal detection and identification;
(3) Gear must not be deployed if there is a risk of interaction with marine
mammals. Gear must not be deployed until a minimum of 15 consecutive minutes have
elapsed during which no marine mammal sightings within 1 nmi (1,852 m) of the
sampling station have occurred;
(4) If marine mammals are sighted within 1 nm of the planned location (i.e.,
station) within the 15 minutes prior to gear deployment, then SouthCoast Wind must
move the vessel away from the marine mammal to a different section of the sampling
area. If, after moving on, marine mammals are still visible from the vessel, SouthCoast
Wind must move again to an area visibly clear of marine mammals or skip the station;
(5) If a marine mammal is at risk of interacting with deployed gear or set, all gear
must be immediately removed from the water. If marine mammals are sighted before the
gear is fully removed from the water, the vessel must slow its speed and maneuver the
vessel away from the animals to minimize potential interactions with the observed
animal;
(6) Survey gear must be deployed as soon as possible once the vessel arrives on
station and after fulfilling the requirements in (g)(1) and (g)(3);

(7) SouthCoast Wind must maintain visual marine mammal monitoring effort
during the entire period of time that gear is in the water (i.e., throughout gear
deployment, fishing, and retrieval). If marine mammals are sighted before the gear is
fully removed from the water, SouthCoast Wind will take the most appropriate action to
avoid marine mammal interaction;
(8) All fisheries monitoring gear must be fully cleaned and repaired (if damaged)
before each use/deployment;
(9) SouthCoast Wind’s fixed gear must comply with the Atlantic Large Whale
Take Reduction Plan regulations at 50 CFR 229.32 during fisheries monitoring surveys;
(10) Trawl tows must be limited to a maximum of 20 minute trawl-time and trawl
tows must not exceed at a speed of 3.0 knots (3.5 mph);
(11) All gear must be emptied as close to the deck/sorting area and as quickly as
possible after retrieval;
(12) During trawl surveys, vessel or scientific crew must open the cod end of the
trawl net close to the deck in order to avoid injury to animals that may be caught in the
gear;
(13) All fishery survey-related lines must include the breaking strength of all lines
being less than 1,700 pounds (lbs; 771 kilograms (kg)). This may be accomplished by
using whole buoy line that has a breaking strength of 1,700 lbs (771 kg); or buoy line
with weak inserts that result in line having an overall breaking strength of 1,700 lbs (771
kg);
(14) During any survey that uses vertical lines, buoy lines must be weighted and
must not float at the surface of the water. All groundlines must be composed entirely of
sinking lines. Buoy lines must utilize weak links. Weak links must break cleanly leaving
behind the bitter end of the line. The bitter end of the line must be free of any knots when
the weak link breaks. Splices are not considered to be knots. The attachment of buoys,

toggles, or other floatation devices to groundlines is prohibited;
(15) All in-water survey gear, including buoys, must be properly labeled with the
scientific permit number or identification as SouthCoast Wind’s research gear. All labels
and markings on the gear, buoys, and buoy lines must also be compliant with the
applicable regulations, and all buoy markings must comply with instructions received by
the NOAA Greater Atlantic Regional Fisheries Office Protected Resources Division;
(16) All survey gear must be removed from the water whenever not in active
survey use (i.e., no wet storage);
(17) All reasonable efforts that do not compromise human safety must be
undertaken to recover gear; and
(18) Any lost gear associated with the fishery surveys must be reported to the
NOAA Greater Atlantic Regional Fisheries Office Protected Resources Division
within 24 hours.
§ 217.335 Monitoring and Reporting Requirements
SouthCoast Wind must implement the following monitoring and reporting
requirements when conducting the specified activities (see § 217.330(c)):
(a) Protected species observer (PSO) and passive acoustic monitoring (PAM)
operator qualifications: SouthCoast Wind must implement the following measures
applicable to PSOs and PAM operators:
(1) SouthCoast Wind must use NMFS-approved PSOs and PAM operators that
are employed by a third-party observer provider. PSOs and PAM operators must have no
tasks other than to conduct observational effort, collect data, and communicate with and
instruct relevant personnel regarding the presence of marine mammals and mitigation
requirements;
(2) All PSOs and PAM operators must have successfully attained a bachelor’s
degree from an accredited college or university with a major in one of the natural

sciences. The educational requirements may be waived if the PSO or PAM operator has
acquired the relevant experience and skills (see § 217.335(a)(3)) for visually and/or
acoustically detecting marine mammals in a range of environmental conditions (e.g., sea
state, visibility) within zone sizes equivalent to the clearance and shutdown zones
required by these regulations. Requests for such a waiver must be submitted to NMFS
Office of Protected Resources prior to or when SouthCoast Wind requests PSO and PAM
operator approvals and must include written justification describing alternative
experience. Alternate experience that may be considered includes, but is not limited to,
conducting academic, commercial, or government-sponsored marine mammal visual
and/or acoustic surveys or previous work experience as a PSO/PAM operator. All PSO’s
and PAM operators should demonstrate good standing and consistently good
performance of all assigned duties;
(3) PSOs must have visual acuity in both eyes (with correction of vision being
permissible) sufficient enough to discern moving targets on the water's surface with the
ability to estimate the target size and distance (binocular use is allowable); ability to
conduct field observations and collect data according to the assigned protocols, writing
skills sufficient to document observations and the ability to communicate orally by radio
or in-person with project personnel to provide real-time information on marine mammals
observed in the area;
(4) All PSOs must be trained to identify northwestern Atlantic Ocean marine
mammal species and behaviors and be able to conduct field observations and collect data
according to assigned protocols. Additionally, PSOs must have the ability to work with
all required and relevant software and equipment necessary during observations described
in paragraphs (b)(2) and (b)(3) of this section;
(5) All PSOs and PAM operators must have successfully completed a PSO, PAM,
or refresher training course within the last 5 years and obtained a certificate of course

completion that must be submitted to NMFS. This requirement is waived for any PSOs
and PAM operators that completed a relevant training course more than five years prior
to seeking approval but have been working consistently as a PSO or PAM operator within
the past five years;
(6) At least one on-duty PSO and PAM operator, where applicable, per platform
must be designated as a Lead during each of the specified activities;
(7) PSOs and PAM operators are responsible for obtaining NMFS’ approval.
NMFS may approve PSOs as conditional or unconditional. An unconditionally approved
PSO is one who has completed training within the last 5 years and attained the necessary
experience (i.e., demonstrate experience with monitoring for marine mammals at
clearance and shutdown zone sizes similar to those produced during the respective
activity) or for PSOs and PAM operators who completed training more than five years
previously and have worked in the specified role consistently for at least the past 5 years.
A conditionally-approved PSO may be one who has completed training in the last 5 years
but has not yet attained the requisite field experience. To qualify as a Lead PSO or PAM
operator, the person must be unconditionally approved and demonstrate that they have a
minimum of 90 days of at-sea experience in the specific role, with the conclusion of the
most recent relevant experience not more than 18 months previous to deployment, and
must also have experience specifically monitoring baleen whale species;
(7) PSOs for HRG surveys may be unconditionally or conditionally approved. A
conditionally approved PSO for HRG surveys must be paired with an unconditionally
approved PSO;
(8) PSOs and PAM operators for foundation installation and UXO detonation
must be unconditionally approved;
(9) SouthCoast Wind must submit NMFS-approved PSO and PAM operator
resumes to NMFS Office of Protected Resources for review and confirmation of their

approval for specific roles at least 90 days prior to commencement of the activities
requiring PSOs/PAM operators or 30 days prior to when new PSOs/PAM operators are
required after activities have commenced. Resumes must include information related to
relevant education, experience, and training, including dates, duration (i.e., number of
days as a PSO or PAM operator per project), location, and description of each prior PSO
or PAM operator experience (i.e., zone sizes monitored, how monitoring supported
mitigation; PAM system/software utilized);
(10) For prospective PSOs and PAM operators not previously approved by NMFS
or for PSOs and PAM operators whose approval is not current (i.e., approval date is more
than 5 years prior to the start of monitoring duties), SouthCoast Wind must submit the list
of pre-approved PSOs and PAM operators for qualification verification at least 60 days
prior to PSO and PAM operator use. Resumes must include information detailed in
217.335(a)(9). Resumes must be accompanied by certificate of completion of a NMFSapproved PSO and/or PAM training/course;
(11) To be approved as a PAM operator, the person must meet the following
qualifications: the PAM operator must have completed a PAM Operator training course,
and demonstrate prior experience using PAM software, equipment, and real-time acoustic
detection systems. They must demonstrate that they have prior experience independently
analyzing archived and/or real-time PAM data to identify and classify baleen whale and
other marine mammal vocalizations by species, including North Atlantic right whale and
humpback whale vocalizations, and experience with deconfliction of multiple species’
vocalizations that are similar and/or received concurrently. PAM operators must be
independent observers (i.e., not construction personnel), trained to use relevant projectspecific PAM software and equipment, and must also be able to test software and
hardware functionality prior to beginning real-time monitoring. The PAM operator must
be able to identify and classify marine mammal acoustic detections by species in real-

time (prioritizing North Atlantic right whales and noting other marine mammals
vocalizations, when detected). At a minimum, for each acoustic detection, the PAM
operator must be able to categorically determine whether a North Atlantic right whale is
detected, possibly detected, or not detected, and notify the Lead PSO of any confirmed or
possible detections, including baleen whale detections that cannot be identified to
species. If the PAM software is capable of localization of sounds or deriving bearings and
distance, the PAM operators must demonstrate experience using this technique;
(12) PSOs may work as PAM operators and vice versa if NMFS approves each
individual for both roles; however, they may only perform one role at any one time and
must not exceed work time restrictions, which must be tallied cumulatively; and
(13) All PSOs and PAM operators must complete a Permits and Environmental
Compliance Plan training that must be held by the Project compliance representative(s)
prior to the start of in-water project activities and whenever new PSOs and PAM
operators join the marine mammal monitoring team. PSOs and PAM operators must also
complete training and orientation with the construction operation to provide for personal
safety;
(b) General PSO and PAM operator requirements. The following measures apply
to PSOs and PAM operators and must be implemented by SouthCoast Wind:
(1) All PSOs must be located at the best vantage point(s) on any platform, as
determined by the Lead PSO, in order to collectively obtain 360-degree visual coverage
of the entire clearance and shutdown zones around the activity area and as much of the
Level B harassment zone as possible. PAM operators may be located on a vessel or
remotely on-shore but must have a computer station equipped with a data collection
software system and acoustic data analysis software available wherever they are
stationed, and data or data products must be streamed in real-time or in near real-time to
allow PAM operators to provide assistance to on-duty PSOs in determining if mitigation

is required (i.e., delay or shutdown);
(2) PSOs must use high magnification (25x) binoculars, standard handheld (7x)
binoculars, and the naked eye to search continuously for marine mammals during visual
monitoring. During foundation installation, at least three PSOs on each dedicated PSO
vessel must be equipped with functional Big Eye binoculars (e.g., 25 x 150; 2.7 view
angle; individual ocular focus; height control). These must be pedestal mounted on the
deck at the best vantage point that provides for optimal sea surface observation and PSO
safety. PAM operators must use a NMFS-approved PAM system to conduct acoustic
monitoring;
(3) During periods of low visibility (e.g., darkness, rain, fog, poor weather
conditions, etc.), PSOs must use alternative technology (e.g., infrared or thermal
cameras) to monitor the mitigation zones;
(4) PSOs and PAM operators must not exceed 4 consecutive watch hours on duty
at any time, must have a 2-hour (minimum) break between watches, and must not exceed
a combined watch schedule of more than 12 hours in a 24-hour period; and
(5) SouthCoast Wind must ensure that PSOs conduct, as rotation schedules allow,
observations for comparison of sighting rates and behavior with and without use of the
specified acoustic sources. Off-effort PSO monitoring must be reflected in the PSO
monitoring reports.
(c) Reporting. SouthCoast Wind must comply with the following reporting
measures:
(1) Prior to initiation of project activities, SouthCoast Wind must demonstrate in a
report submitted to NMFS Office of Protected Resources
(pr.itp.monitoringreports@noaa.gov) that all required training for SouthCoast Wind
personnel, including the vessel crews, vessel captains, PSOs, and PAM operators has
been completed;

(2) SouthCoast Wind must use a standardized reporting system. All data collected
related to the Project must be recorded using industry-standard software that is installed
on field laptops and/or tablets. Unless stated otherwise, all reports must be submitted to
NMFS Office of Protected Resources (PR.ITP.MonitoringReports@noaa.gov), dates
must be in MM/DD/YYYY format, and location information must be provided in
Decimal Degrees and with the coordinate system information (e.g., NAD83, WGS84);
(3) Full detection data, metadata, and location of recorders (or GPS tracks, if
applicable) from all real-time hydrophones used for monitoring during foundation
installation and UXO/MEC detonations must be submitted within 90 calendar days
following completion of activities requiring PAM for mitigation via the International
Organization for Standardization (ISO) standard metadata forms available on the NMFS
Passive Acoustic Reporting System website
(https://www.fisheries.noaa.gov/resource/document/passive-acoustic-reportingsystemtemplates). Submit the completed data templates to nmfs.nec.pacmdata@noaa.gov. The
full acoustic recordings from real-time systems must also be sent to the National Centers
for Environmental Information (NCEI) for archiving within 90 days following
completion of activities requiring PAM for mitigation. Submission details can be found
at: https://www.ncei.noaa.gov/products/passive-acoustic-data;
(4) SouthCoast Wind must compile and submit weekly reports during foundation
installation containing, at minimum, the marine mammal monitoring and abbreviated
SFV data to NMFS Office of Protected Resources (pr.itp.monitoringreports@noaa.gov).
Weekly reports are due on Wednesday for the previous week (Sunday – Saturday);
(5) SouthCoast Wind must compile and submit monthly reports during foundation
installation containing, at minimum, data as described in the weekly reports to NMFS
Office of Protected Resources (pr.itp.monitoringreports@noaa.gov). Monthly reports are
due on the 15th of the month for the previous month;

(6) SouthCoast Wind must submit a draft annual marine mammal monitoring
report to NMFS (PR.ITP.monitoringreports@noaa.gov) no later than March 31, annually
that contains data for all specified activities. The final annual marine mammal monitoring
report must be prepared and submitted within 30 calendar days following the receipt of
any comments from NMFS on the draft report;
(7) SouthCoast Wind must submit the T-SFV interim report no later than 48 hours
after cessation of pile driving for a given foundation installation. In addition to the 48hour interim reports, SouthCoast Wind must submit a draft annual SFV report to NMFS
(PR.ITP.monitoringreports@noaa.gov) no later than 90 days after SFV is completed for
the year. The final annual SFV report must be prepared and submitted within 30 calendar
days (or longer upon approval by NMFS) following the receipt of any comments from
NMFS on the draft report;
(8) SouthCoast Wind must submit its draft final 5-year report to NMFS
(PR.ITP.monitoringreports@noaa.gov) on all visual and acoustic monitoring, including
SFV monitoring, within 90 calendar days of the completion of the specified activities. A
5-year report must be prepared and submitted within 60 calendar days (or longer upon
approval by NMFS) following receipt of any NMFS Office of Protected Resources
comments on the draft report;
(9) SouthCoast Wind must submit SFV results from UXO/MEC detonation
monitoring in a report prior to detonating a subsequent UXO/MEC or within the relevant
weekly report, whichever comes first;
(10) SouthCoast must submit bubble curtain performance reports within 48 hours
of each bubble curtain deployment;
(11) SouthCoast Wind must provide NMFS Office of Protected Resources with
notification of planned UXO/MEC detonation as soon as possible but at least 48 hours
prior to the planned detonation unless this 48-hour notification requirement would create

delays to the detonation that would result in imminent risk of human life or safety. This
notification must include the coordinates of the planned detonation, the estimated charge
size, and any other information available on the characteristics of the UXO/MEC;
(13) SouthCoast Wind must submit a report to the NMFS Office of Protected
Resources (insert ITP monitoring email) within 24 hours if an exemption to any of the
requirements in the regulations and LOA is taken;
(14) SouthCoast Wind must submit reports on all North Atlantic right whale
sightings and any dead or entangled marine mammal sightings to NMFS Office of
Protected Resources (PR.ITP.MonitoringReports@noaa.gov); and
(15) SouthCoast Wind must report any lost gear associated with the fishery
surveys to the NOAA Greater Atlantic Regional Fisheries Office Protected Resources
Division (nmfs.gar.incidentaltake@noaa.gov) as soon as possible or within 24 hours of
the documented time of missing or lost gear.
§ 217.336 Letter of Authorization.
(a) To incidentally take marine mammals pursuant to these regulations,
SouthCoast Wind must apply for and obtain an LOA;
(b) An LOA, unless suspended or revoked, may be effective for a period of time
not to exceed the effective period of this subpart;
(c) If an LOA expires prior to the expiration date of these regulations, SouthCoast
Wind may apply for and obtain a renewal of the LOA;
(d) In the event of projected changes to the activity or to mitigation and
monitoring measures required by an LOA, SouthCoast Wind must apply for and obtain a
modification of the LOA as described in § 217.337; and
(e) The LOA must set forth:
(1) Permissible methods of incidental taking;

(2) Means of effecting the least practicable adverse impact (i.e., mitigation) on the
species, its habitat, and on the availability of the species for subsistence uses; and
(3) Requirements for monitoring and reporting.
(f) Issuance of the LOA must be based on a determination that the level of taking
must be consistent with the findings made for the total taking allowable under this
subpart; and
(g) Notice of issuance or denial of an LOA must be published in the Federal
Register within 30 days of a determination.
§ 217.337 Modifications of Letter of Authorization.
(a) A LOA issued under §§ 216.106 and 217.336 of this section for the activities
identified in § 217.330(c) shall be modified upon request by SouthCoast Wind, provided
that:
(1) The specified activity and mitigation, monitoring, and reporting measures, as
well as the anticipated impacts, are the same as those described and analyzed for this
subpart (excluding changes made pursuant to the adaptive management provision in
paragraph (c)(1) of this section); and
(2) NMFS determines that the mitigation, monitoring, or reporting measures
required by the previous LOA under this subpart were implemented.
(b) For a LOA modification request by the applicant that includes changes to the
activity or the mitigation, monitoring, or reporting measures (excluding changes made
pursuant to the adaptive management provision in paragraph (c)(1) of this section), the
LOA shall be modified, provided that:
(1) NMFS determines that the changes to the activity or the mitigation,
monitoring, or reporting do not change the findings made for the regulations in this
subpart and do not result in more than a minor change in the total estimated number of
takes (or distribution by species or years); and

(2) NMFS may publish a notice of proposed modified LOA in the Federal
Register, including the associated analysis of the change, and solicit public comment
before issuing the LOA.
(c) A LOA issued under §§ 216.106 and 217.336 of this section for the activities
identified in § 217.330(c) may be modified by NMFS under the following circumstances:
(1) Through adaptive management, NMFS may modify (including remove, revise,
or add to) the existing mitigation, monitoring, or reporting measures after consulting with
SouthCoast Wind regarding the practicability of the modifications, if doing so creates a
reasonable likelihood of more effectively accomplishing the goals of the mitigation and
monitoring measures set forth in this subpart.
(i) Possible sources of data that could contribute to the decision to modify the
mitigation, monitoring, or reporting measures in an LOA include, but are not limited to:
(A) Results from SouthCoast Wind’s monitoring;
(B) Results from other marine mammals and/or sound research or studies; and
(C) Any information that reveals marine mammals may have been taken in a
manner, extent, or number not authorized by this subpart or subsequent LOA.
(ii) If, through adaptive management, the modifications to the mitigation,
monitoring, or reporting measures are substantial, NMFS shall publish a notice of
proposed LOA in the Federal Register and solicit public comment; and
(2) If NMFS determines that an emergency exists that poses a significant risk to
the well-being of the species or stocks of marine mammals specified in the LOA issued
pursuant to §§ 216.106 and 217.336 of this section, a LOA may be modified without
prior notice or opportunity for public comment. Notice would be published in the
Federal Register within 30 days of the action.
§§ 217.338 - 217.339 [Reserved]

[FR Doc. 2024-13770 Filed: 6/25/2024 8:45 am; Publication Date: 6/27/2024]