Billing Code 3510-22-P DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration [RTID 0648-XD974] Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the New London Pier Extension Project at the Naval Submarine Base AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice; issuance of an incidental harassment authorization. SUMMARY: In accordance with the regulations implementing the Marine Mammal Protection Act (MMPA) as amended, notification is hereby given that NMFS has issued an incidental harassment authorization (IHA) to the U.S. Navy (Navy) to incidentally harass marine mammals during construction activities associated with the New London Pier Extension Project at Naval Submarine Base (SUBASE) New London in Groton, Connecticut. There are no changes from the proposed authorization in this final authorization. DATES: This authorization is effective from December 1, 2024, through November 30, 2025. ADDRESSES: Electronic copies of the 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-mammal-protection/incidental-takeauthorizations-construction-activities. In case of problems accessing these documents, please call the contact listed below. FOR FURTHER INFORMATION CONTACT: Rachel Wachtendonk, Office of Protected Resources, NMFS, (301) 427-8401. SUPPLEMENTARY INFORMATION: Background 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 and either regulations are proposed or, if the taking is limited to harassment, a notice of a proposed IHA is provided to the public for review. 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). Further, NMFS must prescribe the permissible methods of taking and 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 in shorthand as “mitigationâ€); and requirements pertaining to the mitigation, monitoring and reporting of the takings are set forth. The definitions of all applicable MMPA statutory terms cited above are included in the relevant sections below. Summary of Request On August 21, 2023, NMFS received a request from the Navy for an IHA to take marine mammals incidental to pile driving and removal activities associated with the New London Pier Extension Project at SUBASE New London in Groton, Connecticut. Following NMFS’ review of the application, the Navy submitted a revised version on January 31, 2024. The application was deemed adequate and complete on February 2, 2024. The Navy’s request is for take of six species of marine mammals by Level B harassment and for take of harbor seals, gray seals, and harp seals by Level A harassment. Neither the Navy nor NMFS expects serious injury or mortality to result from this activity; therefore, an IHA is appropriate. There are no changes from the proposed IHA to the final IHA. Description of Specified Activity Overview The Navy is planning the partial demolition and extension of pier 31 at SUBASE New London in Groton, Connecticut (figure 1). The existing pier 31 will be partially demolished and then an 81-foot (ft), or 24.7-meter (m), extension will be constructed. This project will also include the demolition of an existing small access ramp for pier 17. The project includes impact and vibratory pile installation and vibratory pile removal. For a portion of the piles, an auger drill will be used inside the pipe casing to lift sediment. The pier 31 extension will include the removal of 28 16-inch (in), or 0.41-m, fiberglass reinforced plastic fender piles. The pier 17 demolition will include the removal of 20 14-in (0.36-m) concrete encased steel H-piles and 10 timber piles. Existing piles will be removed by the deadpull method, with timber piles being cut at the mudline and all other piles being removed with the vibratory hammer if deadpull is unsuccessful. Once the existing piles are removed, 20 36-in (0.91-m) steel pipe piles and 60 16-in (0.41-m) fiberglass reinforced plastic fender piles will be installed to support the pier 31 extension and pier 17 quaywall. The installation and removal of a temporary work trestle supported by 60 14-in (0.36-m) steel H-piles will be completed to support permanent pile installation. Temporary and permanent piles will be initially installed with a vibratory hammer followed by an impact hammer to embed them to their final depth. For a portion of the piles, an auger drill will be used inside the pipe casing to lift sediment. In order to maintain project schedules, it is possible that multiple pieces of equipment will operate at the same time within the project area. Piles may be extracted and installed on the same day, with a maximum of three vibratory hammers operating simultaneously. The method of installation, and whether concurrent pile driving scenarios will be implemented, will be determined by the construction crew once the project has begun. Therefore, the total take estimate reflects the worst-case scenario for the project. A further detailed description of the planned construction project is provided in the Federal Register notice for the proposed IHA (89 FR 27717, April 18, 2024). Since that time, no changes have been made to the planned activities. Therefore, a detailed description is not provided here. Please refer to that Federal Register notice for the description of the specified activity. Mitigation, monitoring, and reporting measures are described in detail later in this document (please see Mitigation and Monitoring and Reporting sections). Comments and Responses A notice of NMFS' proposal to issue an IHA to the Navy was published in the Federal Register on April 18, 2024 (89 FR 27717). That notice described, in detail, the Navy's activity, the marine mammal species that may be affected by the activity, and the anticipated effects on marine mammals. In that notice, we requested public input on the request for authorization described therein, our analyses, the proposed authorization, and any other aspect of the notice of proposed IHA, and requested that interested persons submit relevant information, suggestions, and comments. During the 30-day public comment period, NMFS did not receive any substantive comments on the proposed IHA. Changes from the Proposed IHA to Final IHA Changes were made between publication of the notice of the proposed IHA and this notice of the final IHA. The Hydroacoustic Monitoring section was updated for clarification. We clarified that the monitoring should occur at 10 m (33 ft) from the monitored pile; at a location intermediate of the pinniped and cetacean Level A (permanent threshold shift (PTS) onset) zones; and occasionally near the predicted harassment zones for Level B (behavioral) harassment. Additionally, table 11 was updated to reflect that the measurements and acoustic monitoring would be conducted for at least 10 percent and up to a maximum of 10 of each different type of pile and each method of installation. We also added a requirement that all PSO data will be submitted electronically with the draft marine mammal report in a format that can be queried, such as a spreadsheet or database. Description of Marine Mammals in the Area of Specified Activities Sections 3 and 4 of the IHA application summarize available information regarding status and trends, distribution and habitat preferences, and behavior and life history of the potentially affected species. NMFS fully considered all of this information, and we refer the reader to these descriptions, instead of reprinting the information. Additional information regarding population trends and threats may be found in NMFS’ Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marinemammal-protection/marine-mammal-stock-assessments) 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). Table 1 lists all species or stocks for which take is expected and authorized for this activity and summarizes information related to the population or stock, including regulatory status under the MMPA and Endangered Species Act (ESA) and potential biological removal (PBR), where known. PBR is defined by the MMPA 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 (as described in NMFS’ SARs). While no serious injury or mortality is anticipated or authorized here, 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. 2022 SARs. All values presented in table 1 are the most recent available at the time of publication (including from the draft 2023 SARs) and are available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammalstock-assessments. Table 1 -- Marine Mammal Species1 Likely Impacted by the Specified Activities Common name ESA/MMPA status; Stock abundance (CV, Nmin, Scientific name Stock Strategic most recent abundance survey)3 (Y/N)2 Order Odontoceti (toothed whales, dolphins, and porpoises) Family Delphinidae Atlantic WhiteLagenorhynchus acutus Sided Dolphin Common Dolphin Delphinus delphis Family Phocoenidae (porpoises) Harbor Porpoise Phocoena phocoena Western N Atlantic Western N Atlantic PBR Annual M/SI4 -, -, N 93,233 (0.71, 54,443, 2021) 28 -, -, N 93,100 (0.56, 59,897, 2021) 1,452 85,765 (0.53, 56,420, 2021) 145 Gulf of Maine/ Bay -, -, N of Fundy Order Carnivora – Pinnipedia Family Phocidae (earless seals) Gray Seal Halichoerus grypus Western N Atlantic5 -, -, N 27,911 (0.20, 23,624, 2021) 1,512 Harbor Seal Phoca vitulina Western N Atlantic -, -, N 61,336 (0.08, 57,637, 2018) 1,729 Harp Seal Pagophilus groenlandicus Western N Atlantic -, -, N 7.6M (UNK, 7.1M, 2019) 426,000 1Information 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://marinemammalscience.org/science-and-publications/list-marinemammal-species-subspecies; Committee on Taxonomy, 2022). 2ESA 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 or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock. 3NMFS marine mammal SARs online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marinemammal-stock-assessment-reports-region. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable. 4These 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). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV associated with estimated mortality due to commercial fisheries is presented in some cases. 5NMFS' stock abundance estimate (and associated PBR value) applies to the U.S. population only. Total stock abundance (including animals in Canada) is approximately 394,311. The annual M/SI value given is for the total stock. 4,570 339 178,573 As indicated above, all six species (with six managed stocks) in table 1 temporally and spatially co-occur with the activity to the degree that take is reasonably likely to occur. All species that could potentially occur in the project area are included in table 3-1 of the IHA application. While North Atlantic right whale (Eubalaena glacialis), common minke whale (Balaenoptera acutorostrata), fin whale (Balaenoptera physalus), and humpback whale (Megaptera novaeangliae) have been documented in Long Island Sound, the spatial and temporal occurrence of these species is such that take is not expected to occur, and they are not discussed further beyond the explanation provided here. These species occur at low densities at the mouth of the Thames River, extending into Long Island Sound, and do not occur in the Thames River. Sound from the project is only expected to propagate into the Long Island Sound during the vibratory driving of the 36-in steel pipe piles. Only a small portion of the Long Island Sound will be ensonified, and therefore incidental take of these species is not anticipated. A detailed description of the species likely to be affected by the Navy's construction project, including brief introductions to the species and relevant stocks as well as available information regarding population trends and threats, and information regarding local occurrence, were provided in the Federal Register notice for the proposed IHA (89 FR 27717, April 18, 2024); since that time, we are not aware of any changes in the status of these species and stocks; therefore, detailed descriptions are not provided here. Please refer to that Federal Register notice for these descriptions. Please also refer to the NMFS website (https://www.fisheries.noaa.gov/find-species) for generalized species accounts. 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. 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, 2019) recommended that marine mammals be divided into hearing groups based on directly measured (behavioral or auditory evoked potential techniques) or estimated hearing ranges (behavioral response data, anatomical modeling, etc.). 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 2. Table 2 -- Marine Mammal Hearing Groups (NMFS, 2018) Hearing Group Low-frequency (LF) cetaceans (baleen whales) Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales) High-frequency (HF) cetaceans (true porpoises, Kogia, river dolphins, Cephalorhynchid, Lagenorhynchus cruciger & L. australis) Phocid pinnipeds (PW) (underwater) (true seals) Otariid pinnipeds (OW) (underwater) (sea lions and fur seals) Generalized Hearing Range* 7 Hz to 35 kHz 150 Hz to 160 kHz 275 Hz to 160 kHz 50 Hz to 86 kHz 60 Hz to 39 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 et al., 2013). This division between phocid and otariid pinnipeds is now reflected in the updated hearing groups proposed in Southall et al. (2019). For more detail concerning these groups and associated frequency ranges, please see NMFS (2018) for a review of available information. Potential Effects of Specified Activities on Marine Mammals and Their Habitat The effects of underwater noise from the Navy's pile driving activities have the potential to result in behavioral harassment of marine mammals in the vicinity of the project area. The notice of the proposed IHA (89 FR 27717, April 18, 2024) included a discussion of the effects of anthropogenic noise on marine mammals and the potential effects of underwater noise from the Navy's pile driving activities on marine mammals and their habitat. That information and analysis is incorporated by reference into this final IHA determination and is not repeated here; please refer to the notice of the proposed IHA (89 FR 27717, April 18, 2024). Estimated Take of Marine Mammals This section provides an estimate of the number of incidental takes authorized through the IHA, which will inform NMFS’ consideration of “small numbers,†the negligible impact determinations, and impacts on subsistence uses. Harassment is the only type of take expected to result from these activities. Except with respect to certain activities not pertinent here, section 3(18) of the MMPA defines “harassment†as any act of pursuit, torment, or annoyance, which: (i) has the potential to injure a marine mammal or marine mammal stock in the wild (Level A harassment); or (ii) 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 (Level B harassment). Authorized takes will primarily be by Level B harassment, as use of the acoustic (i.e., pile driving) has the potential to result in disruption of behavioral patterns for individual marine mammals. There is also some potential for auditory injury (Level A harassment) to result, primarily for phocids because no other species have been observed within the Thames River adjacent to the project site, and the Level A harassment isopleths do not extend to the Long Island Sound. The mitigation and monitoring measures are expected to minimize the severity of the taking to the extent practicable. As described previously, no serious injury or mortality is anticipated or authorized for this activity. Here we describe how the information provided above is synthesized to produce a quantitative estimate of the take that is reasonably likely to occur and is authorized. For acoustic impacts, generally speaking, we estimate take by considering: (1) acoustic thresholds above which NMFS believes the best available science indicates marine mammals will be behaviorally harassed or incur some degree of permanent hearing impairment; (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 the factors considered here in more detail and present the authorized take numbers. Acoustic Thresholds NMFS recommends the use of acoustic thresholds that identify the received level of underwater sound above which exposed marine mammals would be reasonably expected to be behaviorally harassed (equated to Level B harassment) or to incur a PTS of some degree (equated to Level A harassment). 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), the environment (e.g., bathymetry, other noises in the area, predators in the area), and the receiving animals (hearing, motivation, experience, demography, life stage, depth) and can be difficult to predict (e.g., Southall et al., 2007, 2021; Ellison et al., 2012). Based on what the available science indicates 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 root-mean-squared pressure received levels (RMS SPL) of 120 dB (referenced to 1 micropascal (re 1 μPa)) for continuous (e.g., vibratory pile driving, drilling) and above RMS SPL 160 dB re 1 μPa for nonexplosive impulsive (e.g., seismic airguns) or intermittent (e.g., scientific sonar) sources. Generally speaking, Level B harassment take estimates based on these behavioral harassment thresholds are expected to include any likely takes by temporary threshold shift (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. The Navy’s activity includes the use of continuous (vibratory pile driving and auger drilling) and impulsive (impact pile driving) sources, and therefore the RMS SPL thresholds of 120 and 160 dB re 1 μPa are applicable. Level A harassment – NMFS’ Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0; Technical Guidance, 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). The Navy’s activity includes the use of impulsive (impact pile driving) and non-impulsive (vibratory pile driving and auger drilling) sources. These thresholds are provided in the table below. The references, analysis, and methodology used in the development of the thresholds are described in NMFS’ 2018 Technical Guidance, which may be accessed at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammalacoustic-technical-guidance. Table 3 -- Thresholds Identifying the Onset of Permanent Threshold Shift Hearing Group Low-Frequency (LF) Cetaceans Mid-Frequency (MF) Cetaceans High-Frequency (HF) Cetaceans Phocid Pinnipeds (PW) (Underwater) Otariid Pinnipeds (OW) (Underwater) PTS Onset Thresholds* (Received Level) Impulsive Non-impulsive Cell 1 Cell 2 Lp,0-pk,flat: 219 dB LE,p,LF,24h: 199 dB LE,p,LF,24h: 183 dB Cell 3 Cell 4 Lp,0-pk,flat: 230 dB LE,p,MF,24h: 198 dB LE,p,MF,24h: 185 dB Cell 5 Cell 6 Lp,0-pk,flat: 202 dB LE,p,HF,24h: 173 dB LE,p,HF,24h: 155 dB Cell 7 Cell 8 Lp,0-pk,flat: 218 dB LE,p,PW,24h: 201 dB LE,p,PW,24h: 185 dB Cell 9 Cell 10 Lp,0-pk,flat: 232 dB LE,p,OW,24h: 219 dB LE,p,OW,24h: 203 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 table, 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 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 and OW 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. Ensonified Area Here, we describe operational and environmental parameters of the activity that are used in estimating the area ensonified above the acoustic thresholds, including source levels and transmission loss coefficient. The sound field in the project area is the existing background noise plus additional construction noise from the project. Pile driving generates underwater noise that can potentially result in disturbance to marine mammals in the project area. The maximum (underwater) area ensonified is determined by the topography of the Thames River, including intersecting land masses that will reduce the overall area of potential impact. Additionally, vessel traffic, including large vessels and ferries, in the project area may contribute to elevated background noise levels, which may mask sounds produced by the project. Transmission loss (TL) is the decrease in acoustic intensity as an acoustic pressure wave propagates out from a source. TL parameters vary with frequency, temperature, sea conditions, current, source and receiver depth, water depth, water chemistry, and bottom composition and topography. The general formula for underwater TL is: TL = B × Log10 (R1 /R2), where TL = transmission loss in dB; B = transmission loss coefficient; for practical spreading equals 15; R1 = the distance of the modeled SPL from the driven pile; and, R2 = the distance from the driven pile of the initial measurement. This formula neglects loss due to scattering and absorption, which is assumed to be zero here. The degree to which underwater sound propagates away from a sound source is dependent on a variety of factors, most notably the water bathymetry and presence or absence of reflective or absorptive conditions including in-water structures and sediments. Spherical spreading occurs in a perfectly unobstructed (free-field) environment not limited by depth or water surface, resulting in a 6-dB reduction in sound level for each doubling of distance from the source (20×log10[range]). Cylindrical spreading occurs in an environment in which sound propagation is bounded by the water surface and sea bottom, resulting in a reduction of 3 dB in sound level for each doubling of distance from the source (10×log10[range]). A practical spreading value of 15 is often used under conditions, such as the project site, where water increases with depth as the receiver moves away from the shoreline, resulting in an expected propagation environment that would lie between spherical and cylindrical spreading loss conditions. Practical spreading loss is assumed here. The intensity of pile driving sounds is greatly influenced by factors such as the type of piles, hammers, and the physical environment in which the activity takes place. In order to calculate the distances to the Level A harassment and the Level B harassment sound thresholds for the methods and piles being used in this project, NMFS used acoustic monitoring data from other locations to develop proxy source levels for the various pile types, sizes and methods (table 4). Generally, we choose source levels from similar pile types from locations (e.g., geology, bathymetry) similar to the project. Table 4 -- Proxy Sound Source Levels for Pile Sizes, Driving Methods, and Auger Drilling Pile type Pile size Peak SPL (re 1 RMS SPL (re 1 SEL (re 1 μPa μPa (rms)) μPa (rms)) (rms)) Vibratory NA 158 Navy, 2019b Impact 177 Navy, 2019b Vibratory NA 168 Navy, 2018 Impact 198 Navy, 2019b NA NA Dazey et al., 2012 Vibratory 162 Caltrans, 2020 Vibratory NA NA Method Source 14-in H-pile Steel 36-in pipe pile Auger drilling Concrete encased 14-in H-pile steel Illingworth and Rodkin, Fiberglass 16-in fender reinforced plastic California Department Impact 165 157 of Transportation, 2015 For this project, up to three vibratory hammers may operate simultaneously. When two noise sources have overlapping sound fields, there is potential for higher sound levels than for non-overlapping sources because the isopleth of one sound source encompasses the sound source of another isopleth. In such instances, the sources are considered additive and combined using the rules of decibel addition. For addition of two simultaneous sources, the difference between the two sound source levels is calculated, and if that difference is between 0 and 1 dB, 3 dB are added to the higher sound source levels; if the difference is between 2 and 3 dB, 2 dB are added to the highest sound source levels; if the difference is between 4 and 9 dB, 1 dB is added to the highest sound source levels; and with differences of 10 or more dB, there is no addition. For simultaneous usage of three or more continuous sound sources, the three overlapping sources with the highest sound source levels are identified. Of the three highest sound source levels, the lower two are combined using the above rules; then, the combination of the lower two is combined with the highest of the three. The calculated proxy source levels for the different potential concurrent pile driving scenarios are shown in table 5. Table 5 -- Calculated Proxy Sound Source Levels for Potential Concurrent Pile Driving Scenarios Structure Pile type and proxy Calculated proxy sound source level Vibratory installation of 14-in steel H-pile: 158 dB RMS Temporary work trestle installation and pier 17 demolition Temporary work trestle installation, pier 17 demolition, and pier 31 demolition Vibratory demolition of 14-in concrete encased steel H-pile: 162 dB RMS Vibratory installation of 14-in steel H-pile: 158 dB RMS Vibratory demolition of 14-in concrete encased steel H-pile: 162 dB RMS 163 dB RMS 165 dB RMS Vibratory demolition of 16-in fiberglass reinforced plastic fender: 158 dB RMS Vibratory installation of 14-in steel H-pile: 158 dB RMS Temporary work trestle installation and pier 31 demolition Vibratory demolition of 16-in fiberglass reinforced plastic fender: 158 dB RMS 161 dB RMS The ensonified area associated with Level A harassment is more technically challenging to predict due to the need to account for a duration component. Therefore, NMFS developed an optional User Spreadsheet tool to accompany the Technical Guidance that can be used to relatively simply predict an isopleth distance for use in conjunction with marine mammal density or occurrence to help predict potential takes. We note that because of some of the assumptions included in the methods underlying this optional tool, we anticipate that the resulting isopleth estimates are typically going to be overestimates of some degree, which may result in an overestimate of potential take by Level A harassment. However, this optional tool offers the best way to estimate isopleth distances when more sophisticated modeling methods are not available or practical. For stationary sources, like pile driving, the optional User Spreadsheet tool predicts the distance at which, if a marine mammal remained at that distance for the duration of the activity, it would be expected to incur PTS. Inputs used in the optional User Spreadsheet tool, and the resulting estimated isopleths, are reported below. Table 6 -- NMFS User Spreadsheet Inputs Method Vibratory Pile size and type 16-in fiberglass reinforced plastic fender piles install and removal 14-in steel H-pile (temporary) install and removal 14-in concrete encased steel H-pile removal 36-in steel pipe pile install 16-in fiberglass reinforced plastic fender piles Impact 14-in steel H-pile (temporary) install 36-in steel pipe pile install Auger drilling 36-in steel pipe pile install Spreadsheet tab used A.1. Vibratory pile driving A.1. Vibratory pile driving A.1. Vibratory pile driving A.1 Vibratory pile driving E.1. Impact pile driving E.1. Impact pile driving E.1. Impact pile driving A. Stationary source: nonimpulsive, continuous Weighting factor adjustment (kHz) Number of piles per day Duration of sound production within 24-h period (sec) Number of strikes per pile 2.5 2400 NA 2.5 6000 NA 2.5 6000 NA 2.5 0.17 428.4 NA 2.5 NA 2 NA 2 2.5 NA 2 28800 NA Concurrent pile driving 14-in steel H-pile AND 14-in concrete encased steel H-pile 14-in steel H-pile AND 14-in concrete encased steel H-pile AND 16-in fiberglass reinforced plastic fender 14-in steel H-pile AND 16-in fiberglass reinforced plastic fender A.1. Vibratory pile driving 2.5 6000 NA A.1. Vibratory pile driving 2.5 6000 NA A.1. Vibratory pile driving 2.5 8400 NA Table 7 -- Calculated Level A and Level B Harassment Isopleths Method Vibratory Impact Auger drilling Concurrent pile driving Pile size and type 16-in fiberglass reinforced plastic fender piles install and removal 14-in steel H-pile (temporary) install and removal 14-in concrete encased steel H-pile removal 36-in steel pipe pile install 16-in fiberglass reinforced plastic fender piles 14-in steel H-pile (temporary) install 36-in steel pipe pile install 36-in steel pipe pile install 14-in steel H-pile AND 14-in concrete encased steel H-pile 14-in steel H-pile AND 14-in concrete encased steel H-pile AND 16-in fiberglass Level A harassment zone (m/km2) MF- cetaceans HF- cetaceans Phocid 0.3/0 4.9/0.000075 2.0/0.00013 Level B harassment zone (m/km2) 3,415/2.47916 0.5/0.000001 9.0/0.000253 3.7/0.000043 1.0/0.000003 16.5/0.000851 6.8/0.000145 6,310/2.620145 0.4/0.000001 7.2/0.000162 2.9/0.00026 15,849/3.435273 1.2/0.00005 40.5/0.005136 18.2/0.001035 22/0.001513 3.6/0.000041 119.3/0.044565 53.6/0.009004 136/0.056637 65.4/0.01341 2,191/1.588304 984.4/0.86872 3,415/2.620145 0.1/0 0.8/0.000002 0.5/0.000001 1,848/1.359058 1.2/0.000005a,b 19.3/0.001164a 19.3/0.001134b 7.9/0.000195a,b 7,356/3.121835a 7,356/0.205166b 1.6/0.000008a,b,c 26.2/0.002146a,c 26.2/0.001807b 10.8/0.000365a,b,c 10,000/3.197942a 10,000/0.205166b 10,000/2.822399c reinforced plastic fender 14-in steel H-pile AND 16-in fiberglass 1.1/0.000004a,b 17.8/0.00099a,b 7.3/0.000167a,b reinforced plastic fender aHarassment zones mapped from pier 31 bHarassment zones mapped from pier 17 cHarassment zones mapped from existing pier 31 for fender pile extraction 5,412/3.078261a 5,412/2.822399b Marine Mammal Occurrence and Take Estimation In this section we provide information about the occurrence of marine mammals, including density or other relevant information which will inform the take calculations. Density estimates come from Northeast Ocean Data (2023) for cetaceans and from the U.S. Navy Marine Species Density Database (Navy, 2017) for pinnipeds. To determine the incidental take estimate within each harassment zone, the following equation was used: Incidental take estimate = (harassment zone [km2] × estimated density [individuals/km2]) × days of pile driving activity A subset of the species (Atlantic white-sided dolphin, common dolphin, and harbor porpoise) do not occur within the Thames River and have only been observed in the Long Island Sound. For these species, the area from the mouth of the Thames River to the furthest extent of the harassment zone in the Long Island Sound was used to determine the incidental take estimate within that zone. Atlantic White-Sided Dolphin Atlantic white-sided dolphins do not occur within the Thames River but they occur occasionally in the Long Island Sound. Monthly surveys conducted in the Thames River from 2017 through 2019 did not record the presence of Atlantic white-sided dolphins (Tetra Tech, 2019). The average density of Atlantic white-sided dolphins in the Long Island Sound is 0.022 individuals per square kilometer (km2). Only vibratory pile driving activities will generate a harassment zone that extends into the Long Island Sound so for those activities the area from the mouth of the Thames River to the furthest extent in the Long Island Sound (0.24 km2) was used to calculate take (table 8). Therefore, using the equation given above, the calculated estimated take by Level B harassment for Atlantic white-sided dolphins would be one. However, Atlantic white-sided dolphins typically travel in pods, so the estimated take by Level B harassment was increased to the average group size of 12 (NMFS, 2023b). The largest Level A harassment zone for Atlantic white-sided dolphins extends 65 m from the sound source (table 9) and is entirely contained within the Thames River. Therefore, no take by Level A harassment is anticipated or authorized. Common Dolphin Common dolphins do not occur within the Thames River but they occur occasionally in the Long Island Sound. Monthly surveys conducted in the Thames River from 2017 through 2019 did not record the presence of common dolphins (Tetra Tech, 2019). The average density of common dolphins in the Long Island Sound is 0.15 individuals per km2. Only vibratory pile driving activities will generate a harassment zone that extends into the Long Island Sound so for those activities the area from the mouth of the Thames River to the furthest extent in the Long Island Sound (0.24 km2) was used to calculate take (table 8). Therefore, using the equation given above, the calculated estimate of take by Level B harassment for common dolphins would be four. However, common dolphins generally travel in pods, so the estimated take by Level B harassment was increased to an assumed average group size of 30 (NMFS, 2023b). The largest Level A harassment zone for common dolphins extends 65 m from the sound source (table 7) and is entirely contained within the Thames River. Therefore, no take by Level A harassment is anticipated or authorized. Harbor Porpoise Harbor porpoises do not occur within the Thames River but they occur occasionally in the Long Island Sound. Monthly surveys conducted in the Thames River from 2017 through 2019 did not record the presence of harbor porpoises (Tetra Tech, 2019). The average density of harbor porpoises in the Long Island Sound is 0.32 individuals per km2. Only vibratory pile driving activities will generate a harassment zone that extends into the Long Island Sound so for those activities the area from the mouth of the Thames River to the furthest extent in the Long Island Sound (0.24 km2) was used to calculate take (table 8). Therefore, using the equation given above, the estimated take by Level B harassment for harbor porpoises would be nine. The largest Level A harassment zone for harbor porpoises extends 2,191 m from the sound source (table 7) and is entirely contained within the Thames River. Therefore, no take by Level A harassment is anticipated or authorized. Table 8 -- Estimated Take by Level B Harassment for species observed only in the Long Island Sound portion of the project area Calculated Ensonfied area Total Pile size and Method Density estimated (individuals/ take by km2) Level B Total authorized within the Long ensonified type Species Group size take by Level B Island Sound area (km2) harassment (km2) harassment Atlantic white-sided 0.022 12 0.15 30 0.32 3 dolphin 36-in steel pipe Impact 3.435273 0.24 Common pile install dolphin Harbor porpoise Harbor Seal Harbor seals are present in the project vicinity including the Thames River from September through May. Monthly surveys conducted in the Thames River from 2017 through 2019 recorded 12 sightings of individual harbor seals (Tetra Tech, 2019). Seals were not observed on the shore and there are no harbor seal haulouts within the project vicinity. Two different density estimates were used to calculate harbor seal take. A density of 0.049 individuals per km2 was used in the Thames River and a density of 0.07 individuals per km2 was used in the Long Island Sound (Navy, 2017). Therefore, using the equation given above, the estimated number of takes by Level B harassment for harbor seals would be 44. The largest Level A harassment zone for harbor seals extends 984 m from the sound source (table 7). Using the equation given above, the calculated estimated take by Level A harassment for harbor seals would be 1. However, due to the consistent presence of phocid pinnipeds at the SUBASE over the last several years, NMFS conservatively authorizes increasing the estimated take by Level A harassment to one per 30 days of pile driving resulting in an estimated 8 harbor seals by Level A harassment over the course of the project. Gray Seal Gray seals are present in the project vicinity including the Thames River from March through June. Monthly surveys conducted in the Thames River from 2017 through 2019 recorded three sightings of individual gray seals (Tetra Tech, 2019). Seals were not observed on the shore and there are no gray seal haulouts within the project vicinity. Two different density estimates were used to calculate take of gray seals. A density of 0.049 individuals per km2 was used in the Thames River and a density of 0.07 individuals per km2 was used in the Long Island Sound (Navy, 2017). Therefore, using the equation given above, the calculated estimated take by Level B harassment for gray seals would be 44. The largest Level A harassment zone for gray seals extends 984 m from the sound source (table 7). Using the equation given above, the calculated estimated take by Level A harassment for gray seals would be one. However, due to the consistent presence of phocid pinnipeds at the SUBASE over the last several years, NMFS conservatively authorized increasing the estimated take by Level A harassment to one per 30 days of pile driving resulting in an estimate of 8 takes of harbor seals by Level A harassment over the course of the project. Harp Seal Harp seals are present in the project vicinity from January through May and are much rarer in the Thames River then the other two seal species. Harp seals were not observed during monthly surveys conducted in the Thames River from 2017 through 2019 (Tetra Tech, 2019). However, two harp seals were identified in March 2019 and one harp seal in April 2019 by Mystic Aquarium staff. On both occasions they were hauled out on the finger piers of the marina at SUBASE (Navy, 2019a). The average density of harp seals in the Long Island Sound is 0.278 individuals per km2. Only vibratory pile driving activities will generate a harassment zone that extends into the Long Island Sound so for those activities the area from the mouth of the Thames River to the furthest extent in the Long Island Sound was used to calculate take. Therefore, using the equation given above, the estimated take by Level B harassment for harp seals would be seven. However, it was determined that up to one take by Level B harassment of harp seals could occur within the Thames River during each month they are present (January to May) resulting in an estimate of 12 takes of harp seals by Level B harassment. The largest Level A harassment zone for harp seals extends 984 m from the sound source (table 7) and is entirely contained within the Thames River. Harp seals do not have a density estimate for within the Thames River; therefore, given the sightings of this species hauled out at SUBASE, NMFS authorized increasing the estimated take by Level A harassment to one per 30 days of pile driving during the period in which harp seals could occur in the river. This results in an estimate of 5 takes of harp seals by Level A harassment over the course of the project. Table 9 -- Estimated Take by Level A and Level B Harassment Common name Stock Stock abundance1 Level A harassment Level B harassment Atlantic white-sided dolphin Total authorized take Western 2 12 North 93,233 0 12 Atlantic Western Common 2 30 North 93,100 0 30 dolphin Atlantic Gulf of Harbor Maine/Bay of 87,765 0 9 9 porpoise Fundy Western Harbor seal North 61,336 8 44 52 Atlantic Western Gray seal North 27,911 8 44 52 Atlantic Western Harp seal North 7,600,000 5 12 17 Atlantic 1Stock size is N best according to NMFS 2023a draft SARs. 2Authorized take increased to mean group size from AMAPPS (Palka et al., 2017 and 2021). Authorized take as a percentage of stock 0.01 0.03 0.01 0.08 0.19 0.00002 Mitigation In order to issue an IHA under section 101(a)(5)(D) of the MMPA, NMFS must set forth the permissible methods of taking pursuant to the activity, and other means of effecting the least practicable 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 applicants for incidental take authorizations to include information about the availability and feasibility (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 (see 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, NMFS considers 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 (likelihood, scope, range). It further considers the likelihood that the measure will be effective if implemented (probability of accomplishing the mitigating result if implemented as planned), the likelihood of effective implementation (probability implemented as planned); and (2) The practicability of the measures for applicant implementation, which may consider such things as cost, and impact on operations. In addition to the measures described later in this section, the Navy will employ the following mitigation measures: • The Navy will ensure that construction supervisors and crews, the monitoring team, and relevant Navy staff are trained prior to the start of activities subject to the IHA, so that responsibilities, communication procedures, monitoring protocols, and operational procedures are clearly understood. New personnel joining during the project must be trained prior to commencing work. • For those marine mammals for which incidental take has not been authorized, in-water pile installation/removal will shut down immediately if such species are observed within or entering the Level B harassment zone. • If take reaches the authorized limit for any species, pile installation/removal will shut down immediately if these species approach the Level B harassment zone to avoid additional take. The following mitigation measures will apply to the Navy's in-water construction activities: Shutdown and Monitoring Zones The Navy must establish shutdown zones and Level B harassment monitoring zones for all pile driving activities. The purpose of a shutdown zone is generally to define an area within which shutdown of the activity will occur upon sighting of a marine animal (or in anticipation of an animal entering the defined area). Shutdown zones are based on the largest Level A harassment zone for each pile size/type and driving method, and behavioral monitoring zones are meant to encompass Level B harassment zones for each pile size/type and driving method, as shown in table 10. A minimum shutdown zone of 10 m will be required for all in-water construction activities to avoid physical interaction with marine mammals. Shutdown zones for each activity type are shown in table 10. Prior to pile driving, shutdown zones and monitoring zones will be established based on zones represented in table 7. Protected Species Observers (PSOs) will survey the shutdown zones and surrounding areas for at least 30 minutes before pile driving activities start. If marine mammals are found within the shutdown zone, pile driving will be delayed until the animal has moved out of the shutdown zone, either verified by an observer or by waiting until 15 minutes has elapsed without a sighting. If a marine mammal approaches or enters the shutdown zone during pile driving, the activity will be halted. Pile driving may resume after the animal has moved out of and is moving away from the shutdown zone or after at least 15 minutes has passed since the last observation of the animal. All marine mammals will be monitored in the Level B harassment to the extent of visibility for the on-duty PSOs. If a marine mammal for which take is authorized enters the Level B harassment zone, in-water activities would continue and PSOs will document the animal's presence within the estimated harassment zone. If a species for which authorization has not been granted, or for which the authorized takes are met, is observed approaching or within the Level B harassment zone, pile driving activities will be shut down immediately. Activities will not resume until the animal has been confirmed to have left the area or 15 minutes has elapsed with no sighting of the animal. Table 10 –Shutdown and Level B Monitoring Zones by Activity Method Vibratory Impact Auger drilling Concurrent pile driving Pile size and type 16-in fiberglass reinforced plastic fender piles install and removal 14-in steel H-pile (temporary) install and removal 14-in concrete encased steel H-pile removal 36-in steel pipe pile install 16-in fiberglass reinforced plastic fender piles 14-in steel H-pile (temporary) install 36-in steel pipe pile install 36-in steel pipe pile install 14-in steel H-pile AND 14-in concrete encased steel H-pile 14-in steel H-pile AND 14-in concrete encased steel H-pile AND 16-in fiberglass reinforced plastic fender 14-in steel H-pile AND 16-in fiberglass reinforced plastic fender Protected Species Observers Minimum shutdown zone (m) MFHFPhocid cetaceans cetaceans 10 Level B monitoring zone (m) 10 3,415 10 10 15 6,310 10 15,849 45 22 120 136 200 3,415 10 1,848 35 7,356 30 10,000 20 5,412 The placement of PSOs during all pile driving and removal activities (described in detail in the Monitoring and Reporting section) will ensure that the Thames River and portion of the Long Island Sound is visible during pile installation. Pre- and Post-Activity Monitoring Monitoring must take place from 30 minutes prior to initiation of pile driving activities (i.e., pre-clearance monitoring) through 30 minutes post-completion of pile driving. Prior to the start of daily in-water construction activity, or whenever a break in pile driving of 30 minutes or longer occurs, PSOs will observe the shutdown and monitoring zones for a period of 30 minutes. The shutdown zone will be considered cleared when a marine mammal has not been observed within the zone for a 30-minute period. If a marine mammal is observed within the shutdown zones, pile driving activity will be delayed or halted. If work ceases for more than 30 minutes, the pre-activity monitoring of the shutdown zones will commence. A determination that the shutdown zone is clear must be made during a period of good visibility (i.e., the entire shutdown zone and surrounding waters must be visible to the naked eye). Soft Start Soft-start procedures are believed to provide additional protection to marine mammals by providing warning and/or giving marine mammals a chance to leave the area prior to the impact hammer operating at full capacity. For impact driving, an initial set of three strikes will be made by the hammer at reduced energy, followed by a 30second waiting period, then two subsequent three-strike sets before initiating continuous driving. Soft start will be implemented at the start of each day's impact pile driving and at any time following cessation of impact pile driving for a period of 30 minutes or longer. Based on our evaluation of the applicant’s planned measures, NMFS has determined that the mitigation measures provide the means of effecting the least practicable impact on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance. Monitoring and Reporting In order to issue an IHA for an activity, section 101(a)(5)(D) 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 while conducting the activities. 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: â— Occurrence of marine mammal species or stocks in the area in which take is anticipated (e.g., presence, abundance, distribution, density); â— Nature, scope, or context of likely marine mammal exposure to potential stressors/impacts (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 activity; or (4) biological or behavioral context of exposure (e.g., age, calving or feeding areas); â— Individual marine mammal responses (behavioral or physiological) to acoustic stressors (acute, chronic, or cumulative), other stressors, or cumulative impacts from multiple stressors; â— How anticipated responses to stressors impact either: (1) long-term fitness and survival of individual marine mammals; or (2) populations, species, or stocks; â— Effects on marine mammal habitat (e.g., marine mammal prey species, acoustic habitat, or other important physical components of marine mammal habitat); and â— Mitigation and monitoring effectiveness. Visual Monitoring Marine mammal monitoring must be conducted in accordance with the Monitoring Plan and section 5 of the IHA. Marine mammal monitoring during pile driving and removal must be conducted by NMFS-approved PSOs in a manner consistent with the following: • PSOs must be independent of the activity contractor (for example, employed by a subcontractor) and have no other assigned tasks during monitoring periods; • At least one PSO must have prior experience performing the duties of a PSO during construction activity pursuant to a NMFS-issued incidental take authorization; • Other PSOs may substitute education (degree in biological science or related field) or training for experience; and • The Navy must submit PSO Curriculum Vitae for approval by NMFS prior to the onset of pile driving. PSOs must have the following additional qualifications: • Ability to conduct field observations and collect data according to assigned protocols; • Experience or training in the field identification of marine mammals, including the identification of behaviors; • Sufficient training, orientation, or experience with the construction operation to provide for personal safety during observations; • Writing skills sufficient to prepare a report of observations including but not limited to the number and species of marine mammals observed; dates and times when in-water construction activities were conducted; dates, times, and reason for implementation of mitigation (or why mitigation was not implemented when required); and marine mammal behavior; and • Ability to communicate orally, by radio or in person, with project personnel to provide real-time information on marine mammals observed in the area as necessary. The Navy will employ up to five PSOs. PSO locations will provide an unobstructed view of all water within the shutdown zone(s), and as much of the Level A harassment and Level B harassment zones as possible. PSO locations may include the pile installation/extraction barge, shore-based locations (such as pier 17 or pier 32), small boats, and the mouth of the Thames River. Monitoring will be conducted 30 minutes before, during, and 30 minutes after pile driving/removal activities. In addition, observers shall record all incidents of marine mammal occurrence, regardless of distance from activity, and shall document any behavioral reactions in concert with distance from piles being driven or removed. Pile driving/removal activities include the time to install or remove a single pile or series of piles, as long as the time elapsed between uses of the pile driving equipment is no more than 30 minutes. Data Collection PSOs will use approved data forms to record the following information: • Dates and times (beginning and end) of all marine mammal monitoring. • PSO locations during marine mammal monitoring. Construction activities occurring during each daily observation period, including how many and what type of piles were driven or removed and by what method (i.e., vibratory, impact, or auger drilling). • Weather parameters and water conditions. • The number of marine mammals observed, by species, relative to the pile location and if pile driving or removal was occurring at time of sighting. • Distance and bearings of each marine mammal observed to the pile being driven or removed. • Description of marine mammal behavior patterns, including direction of travel. • Age and sex class, if possible, of all marine mammals observed. • Detailed information about implementation of any mitigation triggered (such as shutdowns and delays), a description of specific actions that ensued, and resulting behavior of the animal if any. Hydroacoustic Monitoring The Navy plans to conduct hydroacoustic monitoring, or sound source verification (SSV), of all pile installation and removal methods. Hydroacoustic monitoring results may be used to adjust the size of the Level A and Level B harassment and monitoring zones after a request is made and approved by NMFS. At minimum, the methodology includes: • For underwater recordings, a stationary hydrophone system with the ability to measure SPLs will be placed in accordance with NMFS most recent guidance for the collection of source levels. • Hydroacoustic monitoring will be successfully conducted for at least 10 percent and up to a maximum of 10 of each different type of pile and each method of installation (table 11). Monitoring will occur at 33 ft (10 m) from the noise; at a location intermediate of the pinniped and cetacean Level A (PTS onset) zones; and occasionally near the predicted harassment zones for Level B (Behavioral) harassment. The resulting data set will be analyzed to examine and confirm SPLs and rates of TL for each separate in-water construction activity. With NMFS concurrence, these metrics may be used to recalculate the limits of the shutdown, Level A (PTS onset), and Level B (Behavioral) disturbance zones, and to make corresponding adjustments in marine mammal monitoring of these zones. Hydrophones will be placed using a static line deployed from a stationary (temporarily moored) vessel. Locations of hydroacoustic recordings will be collected via global positioning system. A depth sounder and/or weighted tape measure will be used to determine the depth of the water. The hydrophone will be attached to a weighted nylon cord or chain to maintain a constant depth and distance from the pile area. The nylon cord or chain will be attached to a float or tied to a static line. • Each hydrophone will be calibrated at the start of each action and will be checked frequently to the applicable standards of the hydrophone manufacturer. • Environmental data will be collected, including but not limited to, the following: wind speed and direction, air temperature, humidity, surface water temperature, water depth, wave height, weather conditions, and other factors that could contribute to influencing the airborne and underwater sound levels (e.g., aircraft, boats, etc.). • The chief inspector will supply the acoustics specialist with the substrate composition, hammer/drill model and size, hammer/drill energy settings, depth of drilling, and boring rates and any changes to those settings during the monitoring. • For acoustically monitored construction activities, data from the continuous monitoring locations will be post-processed to obtain the following sound measures: o Maximum peak pressure level recorded for all activities, expressed in dB re 1 μPa. â–ª Mean, median, minimum, and maximum RMS pressure level in [dB re 1 μPa]. â–ª Mean duration of a pile strike (based on 90 percent energy criterion). â–ª Number of hammer strikes. â–ª Mean, median, minimum, and maximum single strike sound exposure level (SEL) in [dB re μPa2 sec]. o Cumulative SEL as defined by the mean single strike SEL + 10*log10 (number of hammer strikes) (dB re μPa2 sec). o Median integration time used to calculate RMS SPL. o A frequency spectrum (pressure spectral density) (dB re μPa2 per Hz) based on the average of up to eight successive strikes with similar sound. Spectral resolution will be 1 Hz, and the spectrum will cover nominal range from 7 Hz to 20 kHz. o Finally, the cumulative SEL will be computed from all the strikes associated with each pile occurring during all phases, i.e., soft start. This measure is defined as the sum of all single strike SEL values. The sum is taken of the antilog, with log10 taken of result to express (dB re μPa2 sec). • For vibratory driving/extraction/drilling: duration and frequency spectrum of vibratory driving per pile; mean, median, and maximum sound levels (dB re: 1 µPa): root mean square sound pressure level (SPLrms), SELcum (and timeframe over which the sound is averaged). Table 11 – Hydroacoustic Monitoring Summary Pile type Count Method of install/extract Number monitored1 14-in steel H-pile 60 Impact 6-10 14-in steel H-pile 60 Vibratory 6-10 36-in steel pipe pile 20 Impact 2-10 36-in steel pipe pile 20 Vibratory 2-10 36-in steel pipe pile 20 Auger (rotary) drill 2-10 16-in fiberglass reinforced 60 Impact 6-10 plastic fender pile 16-in fiberglass reinforced 60 Vibratory 6-10 plastic fender pile 14-in concrete encased 20 Vibratory 2-10 steel H-pile 1Hydroacoustic monitoring would be successfully conducted for at least 10 percent and up to 10 of each different type of pile and each method of installation. Reporting A draft marine mammal monitoring report will be submitted to NMFS within 90 days after the completion of pile driving and removal activities. It will include an overall description of work completed, a narrative regarding marine mammal sightings, and associated PSO data sheets. Specifically, the report must include: â— Dates and times (begin and end) of all marine mammal monitoring. â— Construction activities occurring during each daily observation period, including the number and type of piles driven or removed and by what method (i.e., vibratory driving) and the total equipment duration for cutting for each pile. â— PSO locations during marine mammal monitoring. â— Environmental conditions during monitoring periods (at beginning and end of PSO shift and whenever conditions change significantly), including Beaufort sea state and any other relevant weather conditions including cloud cover, fog, sun glare, and overall visibility to the horizon, and estimated observable distance. â— Upon observation of a marine mammal, the following information: (1) name of PSO who sighted the animal(s) and PSO location and activity at time of sighting; (2) time of sighting; (3) identification of the animal(s) (e.g., genus/species, lowest possible taxonomic level, or unidentified), PSO confidence in identification, and the composition of the group if there is a mix of species; (4) distance and bearing of each marine mammal observed relative to the pile being driven for each sighting (if pile driving was occurring at time of sighting); (5) estimated number of animals (min/max/best estimate); (6) estimated number of animals by cohort (adults, juveniles, neonates, group composition, etc.); (7) animal’s closest point of approach and estimated time spent within the harassment zone; and (8) description of any marine mammal behavioral observations (e.g., observed behaviors such as feeding or traveling), including an assessment of behavioral responses thought to have resulted from the activity (e.g., no response or changes in behavioral state such as ceasing feeding, changing direction, flushing, or breaching). â— Number of marine mammals detected within the harassment zones, by species. â— Detailed information about any implementation of any mitigation triggered (e.g., shutdowns and delays), a description of specific actions that ensued, and resulting changes in behavior of the animal(s), if any. â— All PSO data will be submitted electronically in a format that can be queried such as a spreadsheet or database and would be submitted with the draft marine mammal report. If no comments are received from NMFS within 30 days, the draft final report will constitute the final report. If comments are received, a final report addressing NMFS comments must be submitted within 30 days after receipt of comments. Reporting of Hydroacoustic Monitoring The Navy shall also submit a draft hydroacoustic monitoring report to NMFS within 90 days of the completion of required monitoring at the end of the project, including data in a tabular spreadsheet format (Microsoft Excel or similar). The report will detail the hydroacoustic monitoring protocol and summarize the data recorded during monitoring. The final report must be prepared and submitted within 30 days following resolution of any NMFS comments on the draft report. If no comments are received from NMFS within 30 days of receipt of the draft report, the report shall be considered final. If comments are received, a final report addressing NMFS comments must be submitted within 30 days after receipt of comments. All draft and final hydroacoustic monitoring reports must be submitted to PR.ITP.MonitoringReports@noaa.gov and ITP.Wachtendonk@noaa.gov. The hydroacoustic monitoring report will contain the informational elements described in the Hydroacoustic Monitoring Plan and, at minimum, will include: • Hydrophone equipment and methods: recording device, sampling rate, distance (m) from the pile where recordings were made; depth of recording device(s). • Type and size of pile being driven, substrate type, method of driving during recordings (e.g., hammer model and energy), and total pile driving duration. • Whether a sound attenuation device is used and, if so, a detailed description of the device used and the duration of its use per pile. • For impact pile driving: number of strikes and strike rate; depth of substrate to penetrate; pulse duration and mean, median, and maximum sound levels (dB re: 1 μPa); SPLrms; SELcum; peak sound pressure level (SPLpeak); and single-strike sound exposure level (SELss). • For vibratory driving/extraction/drilling: duration and frequency spectrum of vibratory driving per pile; mean, median, and maximum sound levels (dB re: 1 μPa): SPLrms, SELcum (and timeframe over which the sound is averaged). • One-third octave band spectrum and power spectral density plot. • General Daily Site Conditions o Date and time of activities. o Water conditions (e.g., sea state, tidal state). o Weather conditions (e.g., percent cover, visibility). Reporting Injured or Dead Marine Mammals In the event that personnel involved in the construction activities discover an injured or dead marine mammal, the Navy shall report the incident to the Office of Protected Resources (OPR), NMFS and to the regional stranding coordinator as soon as feasible. If the death or injury was clearly caused by the specified activity, the Navy must immediately cease the specified activities until NMFS 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 IHA. The IHA-holder must not resume their activities until notified by NMFS. The report must include the following information: • Time, date, and location (latitude/longitude) of the first discovery (and updated location information if known and applicable); • Species identification (if known) or description of the animal(s) involved; • Condition of the animal(s) (including carcass condition if the animal is dead); • Observed behaviors of the animal(s), if alive; • If available, photographs or video footage of the animal(s); and • General circumstances under which the animal was discovered. 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†through harassment, NMFS considers other factors, such as the likely nature of any impacts or responses (e.g., intensity, duration), the context of any impacts or responses (e.g., critical reproductive time or location, foraging impacts affecting energetics), as well as effects on habitat, and the likely effectiveness of the 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 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). To avoid repetition, the discussion of our analysis applies to all the species listed in table 1, given that the anticipated effects of this activity on these different marine mammal stocks are expected to be similar. There is little information about the nature or severity of the impacts, or the size, status, or structure of any of these species or stocks that would lead to a different analysis for this activity. Pile driving activities have the potential to disturb or displace marine mammals. Specifically, the project activities may result in take, in the form of Level A harassment and Level B harassment from underwater sounds generated from pile driving and removal. Potential takes could occur if individuals are present in the ensonified zone when these activities are underway. Estimated takes by Level B harassment would be due to potential behavioral disturbance, and TTS. Take by Level A harassment would be due to PTS. No mortality or serious injury is anticipated given the nature of the activity, even in the absence of the required mitigation, and therefore none is authorized. The potential for harassment is minimized through the construction method and the implementation of the mitigation measures (see Mitigation section). Take would occur within a limited, confined area (the Thames River and a small section of the Long Island Sound) of the stocks’ ranges. Take by Level A and Level B harassment would be reduced to the level of least practicable adverse impact through use of mitigation measures described herein. Further, the amount of take authorized is extremely small when compared to stock abundance, and the project is not anticipated to impact any known important habitat areas for any marine mammal species. Take by Level A harassment is authorized to account for the potential that an animal could enter and remain within the area between a Level A harassment zone and the shutdown zone for a duration long enough to be taken by Level A harassment. Any take by Level A harassment is expected to arise from, at most, a small degree of PTS because animals would need to be exposed to higher levels and/or longer duration than are expected to occur here in order to incur any more than a small degree of PTS. Additionally, and as noted previously, some subset of the individuals that are behaviorally harassed could simultaneously incur some small degree of TTS for a short duration of time. Because of the small degree anticipated, though, any PTS or TTS potentially incurred here would not be expected to adversely impact individual fitness, let alone annual rates of recruitment or survival. Behavioral responses of marine mammals to pile driving at the project site, if any, are expected to be mild and temporary. Marine mammals within the Level B harassment zone may not show any visual cues they are disturbed by activities or could become alert, avoid the area, leave the area, or display other mild responses that are not observable such as changes in vocalization patterns. Given the limited number of piles to be installed or extracted per day and that pile driving and removal will occur across a maximum of 242 days within the 12-month authorization period, any harassment will be temporary. Any impacts on marine mammal prey that would occur during the Navy's activity would have, at most, short-term effects on foraging of individual marine mammals, and likely no effect on the populations of marine mammals as a whole. Indirect effects on marine mammal prey during the construction are expected to be minor, and these effects are unlikely to cause substantial effects on marine mammals at the individual level, with no expected effect on annual rates of recruitment or survival. In addition, it is unlikely that minor noise effects in a small, localized area of habitat would have any effect on the stocks' annual rates of recruitment or survival. In combination, we believe that these factors, as well as the available body of evidence from other similar activities, demonstrate that the potential effects of the specified activities will have only minor, short-term effects on individuals. The specified activities are not expected to impact rates of recruitment or survival and will therefore not result in population-level impacts. In summary and as described above, the following factors primarily support our determination that the impacts resulting from this activity are not expected to adversely affect any of the species or stocks through effects on annual rates of recruitment or survival: â— No serious injury or mortality is anticipated or authorized; â— The intensity of anticipated takes by Level B harassment is relatively low for all stocks and would not be of a duration or intensity expected to result in impacts on reproduction or survival; â— No important habitat areas have been identified within the project area; â— For all species, the Thames River and Long Island Sound are a very small and peripheral part of their range and anticipated habitat impacts are minor; and â— The Navy will implement mitigation measures, such as soft-starts for impact pile driving and shut downs to minimize the numbers of marine mammals exposed to injurious levels of sound, and to ensure that take by Level A harassment, is at most, a small degree of PTS. 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 monitoring and mitigation measures, NMFS finds that the total marine mammal take from the activity will have a negligible impact on all affected marine mammal species or stocks. Small Numbers As noted previously, only take of small numbers of marine mammals 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 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 fewer 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. Table 9 demonstrates the number of animals that could be exposed to received noise levels that could cause take by Level A and Level B harassment for the work at SUBASE. Our analysis shows that less than 1 percent of each affected stock could be taken by harassment. The numbers of animals authorized to be taken for these stocks is considered small relative to the relevant stock's abundances, even if each estimated taking occurred to a new individual—an extremely unlikely scenario. Based on the analysis contained herein of the activity (including the mitigation and monitoring measures) and the anticipated take of marine mammals, NMFS 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 will not have an unmitigable adverse impact on the availability of such species or stocks for taking for subsistence purposes. Endangered Species Act Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq.) requires that each Federal agency insure 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 issuance of IHAs, NMFS consults internally whenever we authorize take for endangered or threatened species. No incidental take of ESA-listed species is authorized or expected to result from this activity. Therefore, NMFS has determined that formal consultation under section 7 of the ESA is not required for this action. National Environmental Policy Act 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 our action (i.e., the issuance of an IHA) and alternatives with respect to potential impacts on the human environment. This action is consistent with categories of activities identified in Categorical Exclusion B4 (IHAs with no anticipated serious injury or mortality) of the Companion Manual for NAO 216–6A, which do not individually or cumulatively have the potential for significant impacts on the quality of the human environment and for which we have not identified any extraordinary circumstances that would preclude this categorical exclusion. Accordingly, NMFS has determined that the issuance of this IHA qualifies to be categorically excluded from further NEPA review. Authorization NMFS has issued an IHA to the Navy for the potential harassment of small numbers of six marine mammal species incidental to the New London Pier Extension Project at SUBASE in Groton, Connecticut, that includes the previously explained mitigation, monitoring and reporting requirements. Dated: June 11, 2024. Angela Somma, Acting Director, Office of Protected Resources, National Marine Fisheries Service. [FR Doc. 2024-13169 Filed: 6/13/2024 8:45 am; Publication Date: 6/14/2024]