[Federal Register Volume 89, Number 116 (Friday, June 14, 2024)]
[Notices]
[Pages 50565-50579]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-13169]


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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.

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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

[[Page 50566]]

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-take-authorizations-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 
``mitigation''); 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

[[Page 50567]]

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/marine-mammal-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-mammal-stock-assessments.

                                     Table 1--Marine Mammal Species \1\ Likely Impacted by the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         ESA/ MMPA status;   Stock abundance (CV,
             Common name                  Scientific name               Stock             strategic (Y/N)      Nmin, most recent       PBR     Annual M/
                                                                                                \2\          abundance survey) \3\               SI \4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                               Order Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Atlantic White-Sided Dolphin....  Lagenorhynchus acutus..  Western N Atlantic.....  -, -, N             93,233 (0.71, 54,443,         544         28
                                                                                                             2021).
    Common Dolphin..................  Delphinus delphis......  Western N Atlantic.....  -, -, N             93,100 (0.56, 59,897,       1,452        414
                                                                                                             2021).
Family Phocoenidae (porpoises):
    Harbor Porpoise.................  Phocoena phocoena......  Gulf of Maine/Bay of     -, -, N             85,765 (0.53, 56,420,         649        145
                                                                Fundy.                                       2021).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                               Order Carnivora--Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocidae (earless seals):
    Gray Seal.......................  Halichoerus grypus.....  Western N Atlantic \5\.  -, -, N             27,911 (0.20, 23,624,       1,512      4,570
                                                                                                             2021).
    Harbor Seal.....................  Phoca vitulina.........  Western N Atlantic.....  -, -, N             61,336 (0.08, 57,637,       1,729        339
                                                                                                             2018).
    Harp Seal.......................  Pagophilus               Western N Atlantic.....  -, -, N             7.6M (UNK, 7.1M, 2019)    426,000    178,573
                                       groenlandicus.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies; 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 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.
\3\ NMFS marine mammal SARs online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region.
  CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable.
\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). 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.
\5\ NMFS' 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.

    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

[[Page 50568]]

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                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen   7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans           150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
High-frequency (HF) cetaceans (true    275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 Cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).
Phocid pinnipeds (PW) (underwater)     50 Hz to 86 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)    60 Hz to 39 kHz.
 (sea lions and fur seals).
------------------------------------------------------------------------
* 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 
(Hemil[auml] 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

[[Page 50569]]

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 [mu]Pa)) for continuous (e.g., vibratory pile 
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive 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 
[mu]Pa 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-mammal-acoustic-technical-guidance.

                     Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                         PTS onset thresholds * (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lp,0-pk,flat: 219   Cell 2: LE,p,LF,24h: 199 dB.
                                          dB; LE,p,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lp,0-pk,flat: 230   Cell 4: LE,p,MF,24h: 198 dB.
                                          dB; LE,p,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lp,0-pk,flat: 202   Cell 6: LE,p,HF,24h: 173 dB.
                                          dB; LE,p,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lp,0-pk,flat: 218   Cell 8: LE,p,PW,24h: 201 dB.
                                          dB; LE,p,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lp,0-pk,flat: 232   Cell 10: LE,p,OW,24h: 219 dB.
                                          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 [micro]Pa, and weighted cumulative sound
  exposure level (LE,p) has a reference value of 1[micro]Pa\2\s. 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.

[[Page 50570]]

    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 x 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 x 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 x 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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              Peak SPL (re 1     RMS SPL (re 1     SEL (re 1 [mu]Pa
            Pile type                  Pile size              Method          [mu]Pa (rms))      [mu]Pa (rms))          (rms))              Source
--------------------------------------------------------------------------------------------------------------------------------------------------------
Steel...........................  14-in H-pile.......  Vibratory..........                 NA                158                158  Navy, 2019b.
                                                       Impact.............                194                177                162  Navy, 2019b.
                                  36-in pipe pile....  Vibratory..........                 NA                168                168  Navy, 2018.
                                                       Impact.............                209                198                183  Navy, 2019b.
                                                       Auger drilling.....                 NA                154                 NA  Dazey et al., 2012.
Concrete encased steel..........  14-in H-pile.......  Vibratory..........                185                162                157  Caltrans, 2020.
Fiberglass reinforced plastic...  16-in fender.......  Vibratory..........                 NA                158                 NA  Illingworth and
                                                                                                                                      Rodkin, 2017.
                                                       Impact.............                177                165                157  California
                                                                                                                                      Department 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
----------------------------------------------------------------------------------------------------------------
Temporary work trestle installation and    Vibratory installation of 14- 163 dB RMS.
 pier 17 demolition.                        in steel H-pile: 158 dB RMS.
                                           Vibratory demolition of 14-
                                            in concrete encased steel H-
                                            pile: 162 dB RMS..
Temporary work trestle installation, pier  Vibratory installation of 14- 165 dB RMS.
 17 demolition, and pier 31 demolition.     in steel H-pile: 158 dB RMS.
                                           Vibratory demolition of 14-
                                            in concrete encased steel H-
                                            pile: 162 dB RMS..
                                           Vibratory demolition of 16-
                                            in fiberglass reinforced
                                            plastic fender: 158 dB RMS..
Temporary work trestle installation and    Vibratory installation of 14- 161 dB RMS.
 pier 31 demolition.                        in steel H-pile: 158 dB RMS.
                                           Vibratory demolition of 16-
                                            in fiberglass reinforced
                                            plastic fender: 158 dB RMS..
----------------------------------------------------------------------------------------------------------------


[[Page 50571]]

    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
----------------------------------------------------------------------------------------------------------------
                                                                                         Duration of
                                                                  Weighting                 sound
                                Pile size and   Spreadsheet tab     factor    Number of   production   Number of
            Method                   type             used        adjustment  piles per  within 24-h    strikes
                                                                    (kHz)        day        period     per pile
                                                                                            (sec)
----------------------------------------------------------------------------------------------------------------
Vibratory....................  16-in            A.1. Vibratory           2.5          2        2,400          NA
                                fiberglass       pile driving.
                                reinforced
                                plastic fender
                                piles install
                                and removal.
                               14-in steel H-   A.1. Vibratory           2.5          5        6,000          NA
                                pile             pile driving.
                                (temporary)
                                install and
                                removal.
                               14-in concrete   A.1. Vibratory           2.5          5        6,000          NA
                                encased steel    pile driving.
                                H-pile removal.
                               36-in steel      A.1 Vibratory            2.5       0.17        428.4          NA
                                pipe pile        pile driving.
                                install.
Impact.......................  16-in            E.1. Impact                2        2.5           NA       1,000
                                fiberglass       pile driving.
                                reinforced
                                plastic fender
                                piles.
                               14-in steel H-   E.1. Impact                2          4           NA       1,000
                                pile             pile driving.
                                (temporary)
                                install.
                               36-in steel      E.1. Impact                2        2.5           NA       1,000
                                pipe pile        pile driving.
                                install.
Auger drilling...............  36-in steel      A. Stationary              2          1       28,800          NA
                                pipe pile        source: non-
                                install.         impulsive,
                                                 continuous.
Concurrent pile driving......  14-in steel H-   A.1. Vibratory           2.5          5        6,000          NA
                                pile AND 14-in   pile driving.
                                concrete
                                encased steel
                                H-pile.
                               14-in steel H-   A.1. Vibratory           2.5          5        6,000          NA
                                pile AND 14-in   pile driving.
                                concrete
                                encased steel
                                H-pile AND 16-
                                in fiberglass
                                reinforced
                                plastic fender.
                               14-in steel H-   A.1. Vibratory           2.5          7        8,400          NA
                                pile AND 16-in   pile driving.
                                fiberglass
                                reinforced
                                plastic fender.
----------------------------------------------------------------------------------------------------------------


                                              Table 7--Calculated Level A and Level B Harassment Isopleths
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                  Level A harassment zone (m/km\2\)
                Method                     Pile size and type    ------------------------------------------------------------------  Level B harassment
                                                                      MF-cetaceans          HF-cetaceans             Phocid            zone (m/km\2\)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory.............................  16-in fiberglass                         0.3/0          4.9/0.000075           2.0/0.00013         3,415/2.47916
                                         reinforced plastic
                                         fender piles install
                                         and removal.
                                        14-in steel H-pile                0.5/0.000001          9.0/0.000253          3.7/0.000043
                                         (temporary) install and
                                         removal.
                                        14-in concrete encased            1.0/0.000003         16.5/0.000851          6.8/0.000145        6,310/2.620145
                                         steel H-pile removal.
                                        36-in steel pipe pile             0.4/0.000001          7.2/0.000162           2.9/0.00026       15,849/3.435273
                                         install.
Impact................................  16-in fiberglass                   1.2/0.00005         40.5/0.005136         18.2/0.001035           22/0.001513
                                         reinforced plastic
                                         fender piles.
                                        14-in steel H-pile                3.6/0.000041        119.3/0.044565         53.6/0.009004          136/0.056637
                                         (temporary) install.
                                        36-in steel pipe pile             65.4/0.01341        2,191/1.588304         984.4/0.86872        3,415/2.620145
                                         install.
Auger drilling........................  36-in steel pipe pile                    0.1/0          0.8/0.000002          0.5/0.000001        1,848/1.359058
                                         install.
Concurrent pile driving...............  14-in steel H-pile AND    \a\ \b\ 1.2/0.000005     \a\ 19.3/0.001164  \a\ \b\ 7.9/0.000195    \a\ 7,356/3.121835
                                         14-in concrete encased                            \b\ 19.3/0.001134                          \b\ 7,356/0.205166
                                         steel H-pile.
                                        14-in steel H-pile AND        \a\ \b\ \c\ 1.6/         \a\ \c\ 26.2/     \a\ \b\ \c\ 10.8/   \a\ 10,000/3.197942
                                         14-in concrete encased               0.000008              0.002146              0.000365   \b\ 10,000/0.205166
                                         steel H-pile AND 16-in                            \b\ 26.2/0.001807                         \c\ 10,000/2.822399
                                         fiberglass reinforced
                                         plastic fender.
                                        14-in steel H-pile AND    \a\ \b\ 1.1/0.000004  \a\ \b\ 17.8/0.00099  \a\ \b\ 7.3/0.000167    \a\ 5,412/3.078261
                                         16-in fiberglass                                                                             \b\ 5,412/2.822399
                                         reinforced plastic
                                         fender.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Harassment zones mapped from pier 31.
\b\ Harassment zones mapped from pier 17.
\c\ Harassment zones mapped from existing pier 31 for fender pile extraction.

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 [km\2\] x estimated density 
[individuals/km\2\]) x 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

[[Page 50572]]

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 (km\2\). 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 km\2\) 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 km\2\. 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 km\2\) 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 km\2\. 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 km\2\) 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               Total
                                                   Total     Ensonfied area                               Density      estimated              authorized
        Method            Pile size and type     ensonified    within the            Species           (individuals/    take by      Group     take by
                                                    area       Long Island                                km\2\)        Level B      size      Level B
                                                  (km\2\)     Sound (km\2\)                                            harassment             harassment
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact...............  36-in steel pipe pile       3.435273            0.24  Atlantic white-sided              0.022            1        12           12
                        install.                                              dolphin.
                                                                             Common dolphin.........            0.15            4        30           30
                                                                             Harbor porpoise........            0.32            9         3            9
--------------------------------------------------------------------------------------------------------------------------------------------------------

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 km\2\ was used in the 
Thames River and a density of 0.07 individuals per km\2\ 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 km\2\ was used in the Thames River 
and a density of 0.07 individuals per km\2\ 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

[[Page 50573]]

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 
km\2\. 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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                              Authorized
                                                                                           Stock        Level A      Level B       Total      take as a
                   Common name                                   Stock                 abundance \1\   harassment   harassment   authorized   percentage
                                                                                                                                    take       of stock
--------------------------------------------------------------------------------------------------------------------------------------------------------
Atlantic white-sided dolphin....................  Western North Atlantic............          93,233            0       \2\ 12           12         0.01
Common dolphin..................................  Western North Atlantic............          93,100            0       \2\ 30           30         0.03
Harbor porpoise.................................  Gulf of Maine/Bay of Fundy........          87,765            0            9            9         0.01
Harbor seal.....................................  Western North Atlantic............          61,336            8           44           52         0.08
Gray seal.......................................  Western North Atlantic............          27,911            8           44           52         0.19
Harp seal.......................................  Western North Atlantic............       7,600,000            5           12           17      0.00002
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Stock size is Nbest according to NMFS 2023a draft SARs.
\2\ Authorized take increased to mean group size from AMAPPS (Palka et al., 2017 and 2021).

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

[[Page 50574]]

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
----------------------------------------------------------------------------------------------------------------
                                                                                Level B monitoring zone (m)
                                                              Minimum    ---------------------------------------
              Method                 Pile size and type    shutdown zone      MF-         HF-
                                                                (m)        cetaceans   cetaceans      Phocid
----------------------------------------------------------------------------------------------------------------
Vibratory.........................  16-in fiberglass                  10          10          10           3,415
                                     reinforced plastic
                                     fender piles
                                     install and removal.
                                    14-in steel H-pile                10          10          10  ..............
                                     (temporary) install
                                     and removal.
                                    14-in concrete                    10          30          15           6,310
                                     encased steel H-
                                     pile removal.
                                    36-in steel pipe                  10          10          10          15,849
                                     pile install.
Impact............................  16-in fiberglass                  10          45          20              22
                                     reinforced plastic
                                     fender piles.
                                    14-in steel H-pile                10         120          55             136
                                     (temporary) install.
                                    36-in steel pipe                  70         200         200           3,415
                                     pile install.
Auger drilling....................  36-in steel pipe                  10          10          10           1,848
                                     pile install.
Concurrent pile driving...........  14-in steel H-pile                10          35          15           7,356
                                     AND 14-in concrete
                                     encased steel H-
                                     pile.
                                    14-in steel H-pile                10          30          15          10,000
                                     AND 14-in concrete
                                     encased steel H-
                                     pile AND 16-in
                                     fiberglass
                                     reinforced plastic
                                     fender.
                                    14-in steel H-pile                10          20          10           5,412
                                     AND 16-in
                                     fiberglass
                                     reinforced plastic
                                     fender.
----------------------------------------------------------------------------------------------------------------

Protected Species Observers

    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 30-second 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:
     Occurrence of marine mammal species or stocks in the area 
in which

[[Page 50575]]

take is anticipated (e.g., presence, abundance, distribution, density);
     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);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (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
     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.

[[Page 50576]]

     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:
    [cir] Maximum peak pressure level recorded for all activities, 
expressed in dB re 1 [mu]Pa.
    [ssquf] Mean, median, minimum, and maximum RMS pressure level in 
[dB re 1 [mu]Pa].
    [ssquf] Mean duration of a pile strike (based on 90 percent energy 
criterion).
    [ssquf] Number of hammer strikes.
    [ssquf] Mean, median, minimum, and maximum single strike sound 
exposure level (SEL) in [dB re [mu]Pa\2\ sec].
    [cir] Cumulative SEL as defined by the mean single strike SEL + 
10*log10 (number of hammer strikes) (dB re [mu]Pa\2\ sec).
    [cir] Median integration time used to calculate RMS SPL.
    [cir] A frequency spectrum (pressure spectral density) (dB re 
[mu]Pa\2\ 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.
    [cir] 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 [mu]Pa\2\ sec).
     For vibratory driving/extraction/drilling: duration and 
frequency spectrum of vibratory driving per pile; mean, median, and 
maximum sound levels (dB re: 1 [micro]Pa): root mean square sound 
pressure level (SPLrms), SELcum (and timeframe 
over which the sound is averaged).

               Table 11--Hydroacoustic Monitoring Summary
------------------------------------------------------------------------
                                                                Numbe
          Pile type              Count        Method of       monitored
                                           install/extract       \1\
------------------------------------------------------------------------
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)            2-10
                                           drill.
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 steel          20  Vibratory.......          2-10
 H-pile.
------------------------------------------------------------------------
\1\ Hydroacoustic 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:
     Dates and times (begin and end) of all marine mammal 
monitoring.
     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.
     PSO locations during marine mammal monitoring.
     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.
     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).
     Number of marine mammals detected within the harassment 
zones, by species.
     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.
     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

[[Page 50577]]

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 [email protected] and 
[email protected]. 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 [mu]Pa); 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 [mu]Pa): SPLrms, 
SELcum (and timeframe over which the sound is averaged).
     One-third octave band spectrum and power spectral density 
plot.
     General Daily Site Conditions
    [cir] Date and time of activities.
    [cir] Water conditions (e.g., sea state, tidal state).
    [cir] 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

[[Page 50578]]

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:
     No serious injury or mortality is anticipated or 
authorized;
     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;
     No important habitat areas have been identified within the 
project area;
     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
     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.


[[Page 50579]]


    Dated: June 11, 2024.
Angela Somma,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2024-13169 Filed 6-13-24; 8:45 am]
BILLING CODE 3510-22-P