Notice2026-03861
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Demolition of Pier 10 and Construction of a Crane Weight Test Area Project at U.S. Naval Submarine Base New London
Primary source
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Published
February 26, 2026
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has received a request from the U.S. Navy (Navy) for authorization to take marine mammals incidental to the demolition of Pier 10 and the construction of a Crane Weight Test Area (CWTA) at Naval Submarine Base (SUBASE) New London in Groton, Connecticut. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue an incidental harassment authorization (IHA) to incidentally take marine mammals during the specified activities. NMFS is also requesting comments on a possible one-time, 1-year renewal that could be issued under certain circumstances and if all requirements are met, as described in Request for Public Comments at the end of this notice. NMFS will consider public comments prior to making any final decision on the issuance of the requested MMPA authorization and agency responses will be summarized in the final notice of our decision.
Full Text
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<title>Federal Register, Volume 91 Issue 38 (Thursday, February 26, 2026)</title>
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[Federal Register Volume 91, Number 38 (Thursday, February 26, 2026)]
[Notices]
[Pages 9574-9600]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-03861]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XE883]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to the Demolition of Pier 10 and
Construction of a Crane Weight Test Area Project at U.S. Naval
Submarine Base New London
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorization; request
for comments on proposed authorization and possible renewal.
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SUMMARY: NMFS has received a request from the U.S. Navy (Navy) for
authorization to take marine mammals incidental to the demolition of
Pier 10 and the construction of a Crane Weight Test Area (CWTA) at
Naval Submarine Base (SUBASE) New London in Groton, Connecticut.
Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting
comments on its proposal to issue an incidental harassment
authorization (IHA) to incidentally take marine mammals during the
specified activities. NMFS is also requesting comments on a possible
one-time, 1-year renewal that could be issued under certain
circumstances and if all requirements are met, as described in Request
for Public Comments at the end of this notice. NMFS will consider
public comments prior to making any final decision on the issuance of
the requested MMPA authorization and agency responses will be
summarized in the final notice of our decision.
DATES: Comments and information must be received no later than March
30, 2026.
ADDRESSES: Comments should be addressed to the Permits and Conservation
Division, Office of Protected Resources, National Marine Fisheries
Service and should be submitted via email to <a href="/cdn-cgi/l/email-protection#8fc6dbdfa1e7e0fbece7e4e6e1cfe1e0eeeea1e8e0f9"><span class="__cf_email__" data-cfemail="307964601e585f4453585b595e705e5f51511e575f46">[email protected]</span></a>.
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: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>. In
case of problems accessing these documents, please call the contact
listed below.
Instructions: NMFS is not responsible for comments sent by any
other method, to any other address or individual, or received after the
end of the comment period. Comments, including all attachments, must
not exceed a 25-megabyte file size. All comments received are a part of
the public record and will generally be posted online at <a href="https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act</a> without change. All personal identifying
information (e.g., name, address) voluntarily submitted by the
commenter may be publicly accessible. Do not submit confidential
business information or otherwise sensitive or protected information.
FOR FURTHER INFORMATION CONTACT: Cara Hotchkin, 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 monitoring and
reporting of the takings. The definitions of all applicable MMPA
statutory terms cited above are included in the relevant sections below
and can be found in section 3 of the MMPA (16 U.S.C. 1361 et seq.) and
NMFS regulations at 50 CFR 216.103.
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 review our proposed action (i.e., the issuance of an IHA)
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 preliminarily determined
that the issuance of the proposed IHA qualifies to be categorically
excluded from further NEPA review.
We will review all comments submitted in response to this notice
prior to concluding our NEPA process or making a final decision on the
request for an IHA.
Summary of Request
Demolition of Pier 10 and upgrading of the quay wall to accommodate
the construction of a new CWTA were part of a previously issued Letter
of Authorization (83 FR 36773, July 31, 2018), which was effective
until February 28, 2025. Because the project was not completed by
February 28, 2025, and some pile driving elements have changed, the
Navy is requesting a new one-year IHA for the demolition of Pier 10 and
construction of a new CWTA. On February 24, 2025, NMFS received a
request from the Navy for an IHA to take marine mammals incidental to
construction associated with the New London Pier 10 and construction of
a CWTA at SUBASE New London in Groton, Connecticut. Following NMFS'
review of the application and associated discussions, the Navy
submitted several
[[Page 9575]]
revised versions of the application. The application was deemed
adequate and complete on May 30, 2025. On July 22, 2025, the Navy
notified NMFS that the project schedule had changed, with a new
anticipated start date of August 1, 2026. The Navy's request is for
take of five species of marine mammals, by Level B harassment only.
Neither the Navy nor NMFS expect serious injury or mortality to result
from this activity and, therefore, an IHA is appropriate.
Description of Proposed Activity
Overview
The Navy is proposing the demolition of Pier 10 and the upgrade of
the quay wall to accommodate the construction of a new CWTA at SUBASE
New London in Groton, Connecticut (figure 1). Pier 10 has exceeded its
service life and is considered operationally inadequate. After
demolition of the pier, fender piles will be installed on the quay
wall. Construction of a new CWTA will involve demolition of the
existing quay wall and reconstruction of a 46-foot-long portion of
pile-supported quay wall structure north of Pier 33 to accommodate the
construction of an area for storage of crane test weights. The proposed
project includes impact and vibratory pile installation and vibratory
pile removal. For a portion of the piles, rock socket drilling (rotary
drill) would be used inside the pipe casing to lift sediment.
Sounds resulting from pile driving, removal, and drilling may
result in the incidental take of marine mammals by Level B harassment
in the form of behavioral harassment. Underwater sound would be
constrained to the Thames River and a small portion of the Long Island
Sound and would be truncated by land masses in the river. Construction
activities would start in August 2026 and last 12 months; in-water pile
driving is expected to take approximately 80 (potentially non-
consecutive) days.
Dates and Duration
The proposed IHA would be valid for the statutory maximum of 1 year
from the date of effectiveness and will become effective upon written
notification from the applicant to NMFS, but not beginning later than 1
year from the date of issuance or extending beyond 2 years from the
date of issuance. All pile driving and removal would be completed
during daylight hours.
Specific Geographic Region
The project is located at SUBASE New London in Groton, Connecticut
(figure 1), which is located approximately 6 miles (mi), or 9.5
kilometers (km), up the Thames River from Long Island Sound. Project
activities would occur at the existing Pier 10 and north of Pier 33.
[[Page 9576]]
[GRAPHIC] [TIFF OMITTED] TN26FE26.001
Detailed Description of the Specified Activity
The project proposes to demolish Pier 10, including the removal of
the existing concrete deck, utilities, support piles, and the fender
system. The existing steel fender H-piles and wood piles would be
extracted by crane and sling. In the unlikely event some of the steel
fender piles cannot be pulled by crane and sling, they would be
extracted by vibratory hammer. Therefore, vibratory extraction of a
portion of the piles is assumed for the analysis. Wood piles that
cannot be pulled will be cut below the mudline. The 24-inch concrete-
encased steel H-piles and cast-in-place reinforced concrete piles would
be extracted by vibratory hammer. After demolition of Pier 10, four 16-
inch polymeric fender piles with H-pile extension would be installed by
impact hammer on the pier's quay wall.
Construction of a new CWTA will occur concurrently with Pier 10
demolition. The existing quay wall includes steel fender H-piles, which
would be removed by vibratory hammer, and 18-inch diameter concrete
piles in rock sockets, which would be cut off below the mudline. A 46-
foot-long pile-supported quay wall would be constructed north of Pier
33 to accommodate the construction of an area for storage of crane test
weights. The concrete deck, deck equipment (light posts, cleats, etc.),
fender system with steel fender H-piles, concrete support piles, and
concrete pile caps associated with the existing quay wall will be
demolished prior to the CWTA construction. CWTA construction includes
the installation of 30-inch by 100-foot concrete-filled steel pipe
piles and 16-inch fiberglass-reinforced plastic fender piles drilled
into rock sockets. Table 1 provides a summary of the pile driving
activities.
Concurrent Activities--In order to maintain project schedules,
multiple pieces of equipment would operate at the same time within the
project area between Pier 10 and the CWTA area. Piles may be extracted
and installed on the same day, with a maximum of four vibratory hammers
operating simultaneously. It is estimated that approximately 2.5 days
in December and 2 days in January will have concurrent activities.
Table 2 provides a summary of the expected concurrent activities.
[[Page 9577]]
Table 1--Number and Type of Piles To Be Installed and/or Removed
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Piles
Method of installed/ Total pile Average hammer/ drill Average hammer/ drill
Activity (dates) Pile Pile type installation/ removed driving/ operation (seconds per operation (seconds per
count \1\ removal per work extraction pile) \3\ day)
day \2\ days
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Pier 10 Demolition/Pile 84 HP14x89 steel Pulled by crane & 12.5 0 0...................... 0.
Removal (August 2026-December 24 fender H-piles. sling. 9.5 2.5 3,600 seconds.......... 34,200 seconds.
2027) Concurrent with CWTA HP14x89 steel Vibratory
Demolition and CWTA fender piles. extraction of
Construction. estimated number
of piles that
cannot be pulled.
41 Wood piles....... Pulled by crane & 12.5 0 0...................... 0.
sling or cut
below mudline.
24 24-inch concrete- Vibratory hammer. 9.5 2.5 1,200 seconds.......... 11,400 seconds.
encase steel H-
piles.
166 24-inch cast-in- Vibratory hammer. 9.5 17.5 1,200 seconds.......... 11,400 seconds.
place reinforced
concrete piles.
Pier 10 Quay wall Construction/ 4 16-inch polymeric Impact hammer.... 2 2 1,000 strikes.......... 2,000 strikes.
Repair (January-February fender piles w/H-
2027) Concurrent with CWTA pile extension.
Construction.
CWTA Quay wall Demolition 5 HP14 steel fender Vibratory hammer. 3 1.67 7,200 seconds.......... 21,600 seconds.
(November-December 2026) 8 H-piles. Cut off below n/a n/a n/a.................... n/a.
Concurrent with Pier 10 18-inch diameter mudline.
Demolition and CWTA concrete piles
Construction. in rock sockets.
CWTA Construction/Pile 18 30-inch x 100-ft Rock socket 0.5 36 15,000 seconds......... 7,500 seconds.
Installation (December 2026) concrete-filled (rotary)
Concurrent with Pier 10 Quay steel pipe piles. drilling.
wall Construction/Repair.
CWTA Construction/Pile 9 16-inch Rock socket 0.5 18 7,500 seconds.......... 3,750 seconds.
Installation (January 2027) fiberglass (rotary)
Concurrent with Pier 10 reinforced, drilling.
Demolition and CWTA plastic fender
Demolition. piles.
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Legend: n/a = not applicable.
Notes:
1. Pile count based on Waterfront Facilities Inspections and Assessments.
2. Estimate provided by NAVFAC Mid-Atlantic Public Works Department; based on data from previous similar projects; assumes 5 workdays per week.
3. Vibratory hammer measured in seconds per pile.
Table 2--Number and Type of Concurrent Piles To Be Installed and Removed
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Total Total
Month and year Structure Activities Type, pile sizes, and Equipment equipment concurrent
types per scenario (quantity) quantity days
--------------------------------------------------------------------------------------------------------------------------------------------------------
December 2026................... Pier 10...................... Demolition/Removal. Vibratory extraction Vibratory hammer 5 2.5
HP14x89 steel fender H- (4), rotary drill
piles (2.5 days); (1).
Vibratory extraction
24-inch concrete-
encased steel H-piles
(2.5 days); Vibratory
Extraction 24-inch
cast-in-place
reinforced concrete
piles (17.5 days).
CWTA......................... Demolition......... Vibratory extraction ......... ..........
HP14 Steel fender H-
piles (1.67 days).
Construction/Pile Rock socket (rotary) ......... ..........
Installation. drilling 30-inch x 100-
ft concrete-filled,
steel pipe piles (36
days).
January 2027.................... Pier 10 Quay Wall............ Construction/Repair Impact installation of Impact hammer (1), 2 2
16-inch polymeric and rotary drill
fender piles with H- (1).
pile extension (2
days).
CWTA......................... Construction/Pile Rock socket (rotary) ......... ..........
Installation. drilling of 16-inch
fiberglass reinforced,
plastic fender piles
(18 days).
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Proposed mitigation, monitoring, and reporting measures are
described in detail later in this document (please see Proposed
Mitigation and Proposed Monitoring and Reporting).
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; <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>) and more general information about these species
(e.g., physical and behavioral descriptions) may be found on NMFS'
website (<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>).
[[Page 9578]]
Table 3 lists all species or stocks for which take is expected and
proposed to be 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 proposed
to be 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' Atlantic SARs. All values presented in table 3 are the most
recent available at the time of publication, including from the draft
2024 SARs, and are available online at <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports</a>.
Table 3--Marine Mammal Species \1\ Likely Impacted by the Specified Activities
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Stock abundance (CV,
Common name Scientific name Stock ESA/MMPA status; Nmin, most recent PBR Annual M/
strategic (Y/N) \2\ abundance survey) \3\ SI \4\
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Order Odontoceti (toothed whales, dolphins, and porpoises)
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Family Delphinidae:
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).
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Order Carnivora--Pinnipedia
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Family Phocidae (earless seals):
Harbor Seal.................... Phoca vitulina........ Western N Atlantic.... -, -, N 61,336 (0.08, 57,637, 1,729 339
2018).
Gray Seal...................... Halichoerus grypus.... Western N Atlantic \5\ -, -, N 27,911 (0.20, 23,624, 756 4,491
2021).
Harp Seal...................... Pagophilus Western N Atlantic.... -, -, N 7.6M (UNK, 7.1M, 2019) 426,000 178,573
groenlandicus.
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\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
(<a href="https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies">https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies</a>).
\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: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>. 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 based on the minimum population
estimate in U.S. waters is 23,624 and 359,332 in Canada, for a total Nmin of 376,621. The annual M/SI value given is for the total stock.
As indicated above, all five species in table 3 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 proposed 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 the area, 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 normally occur in the
Thames River. Sound from the project is only expected to propagate into
the Long Island Sound during the concurrent pile driving in December
(2.5 days). Only a small portion of the Long Island Sound would be
ensonified, and therefore incidental take of these species is not
anticipated.
Common Dolphin
The common dolphin is found world-wide in temperate to subtropical
seas. In the North Atlantic, common dolphins are found over the
continental shelf between the 100-m and 2,000-m isobaths and over
prominent underwater topography and east to the mid-Atlantic Ridge
(Hayes et al., 2024), but may be found in shallower shelf waters as
well. They can be found from Cape Hatteras northeast to Georges Bank
from mid-January to May and in Gulf of Maine from mid-summer to autumn
(Hayes et al., 2024). In the North Atlantic, common dolphins travel in
pods with an average group size of 30 individuals (from AMAPPS (Palka
et al., 2017 and 2021)).
Common dolphins are expected to occur in the vicinity of the
project area in Long Island Sound in moderate numbers but were not
found in the Navy's Thames River study (Tetra Tech, 2020); however,
common dolphins are likely to occur in Long Island Sound during mid-
summer through fall with peak abundance in September (Northeast Ocean
Data, 2023).
Harbor Porpoise
Harbor porpoise occur along the US and Canadian east coast (Hayes
et al., 2019). They rarely occur in waters warmer than 62.6 [deg]F
(17[deg] Celsius; Read, 1990). The Gulf of Maine/Bay of Fundy stock is
found is concentrated in the northern Gulf of Maine and southern Bay of
Fundy region, generally in waters
[[Page 9579]]
less than 150 m deep (Waring et al., 2017). During fall (October to
December) and spring (April to June) harbor porpoises are widely
dispersed from New Jersey to Maine. During winter (January to March),
intermediate densities of harbor porpoises can be found in waters off
New Jersey to North Carolina, and lower densities are found in waters
off New York to New Brunswick, Canada. In the summer they are sighted
primarily in the northern Gulf of Maine and southern Bay of Fundy. They
are seen from the coastline to deep waters (>1800 m; Westgate et al.,
1998), although the majority of the population is found over the
continental shelf (Waring et al., 2017). In most areas, harbor porpoise
occur in small groups of just a few individuals. Harbor porpoise must
forage nearly continuously to meet their high metabolic needs
(Wisniewska et al., 2016). They consume up to 550 small fish (1.2-3.9
in [3-10 cm]) per hour at a nearly 90 percent capture success rate
(Wisniewska et al., 2016).
Harbor porpoise have not been documented in the Thames River (Tetra
Tech, 2020) but are likely to occur near the mouth of the river and out
into Long Island Sound during the fall, with peak abundance in December
(Northeast Ocean Data, 2023).
Gray Seal
Gray seals in the project area belong to the western North Atlantic
stock. The range for this stock is from New Jersey to Labrador. Current
population trends show that gray seal abundance is likely increasing in
the U.S. Atlantic EEZ (Hayes et al., 2019). In U.S. waters, year-round
breeding of approximately 400 animals has been documented on areas of
outer Cape Cod and Muskeget Island in Massachusetts. They are a coastal
species that generally remains within the continental shelf region but
do venture into deeper water to feed. Gray seals primarily feed on
fish, squid, various crustacean species, and octopus.
Monthly observations over the 3-year marine mammal survey yielded a
total of three sightings of individual gray seals (Tetra Tech, 2020).
During marine mammal monitoring for Pier 32 construction activities
that occurred from May 2022 through December 2022, no gray seals were
observed (Navy, 2023).
Gray seals are common in Long Island Sound from September through
June (Medic, 2005). Aerial surveys of haulout sites around Long Island
in November 2018 recorded more than 900 harbor and gray seals (Atlantic
Marine Conservation Society, 2018). The closest haulout site is
approximately 10 miles (16 km) south of Pier 10 at Fishers Island in
Long Island Sound. With the increase in populations, gray seals are
likely to co-occur in the Thames River with, and would not always be
distinguishable from, harbor seals. No seals were observed hauled out
onshore (Tetra Tech, 2019) and there are no known haulout areas within
the Thames River (Navy, 2018).
Harbor Seal
Harbor seals are found in all nearshore waters of the North
Atlantic Ocean and adjoining seas above about lat. 30[deg] N (Burns,
2009). In the western North Atlantic, harbor seals are distributed from
the eastern Canadian Arctic and Greenland down the east coast of the
United States (Hayes et al., 2019). They occur seasonally along the
coasts from southern New England to New Jersey from September through
late May. Haulout and pupping sites are located off Manomet, MA, and
the Isles of Shoals, ME (Waring et al., 2016).
Harbor seals are central-place foragers (Orians and Pearson, 1979)
and tend to exhibit strong site fidelity within season and across
years, generally forage close to haulout sites, and repeatedly visit
specific foraging areas (Grigg et al., 2012; Suryan and Harvey, 1998;
Thompson et al., 1998). Harbor seals tend to forage at night and haul
out during the day (Grigg et al., 2012; London et al., 2001; Stewart
and Yochem, 1994; Yochem et al., 1987). Tide levels affect the maximum
number of seals hauled out, with the largest number of seals hauled out
at low tide, but time of day and season have the greatest influence on
haul out behavior (Manugian et al., 2017; Patterson and Acevedo-
Guti[eacute]rrez, 2008; Stewart and Yochem, 1994). Harbor seals molt
from May through June. Peak numbers of harbor seals haul out in late
May to early June, which coincides with the peak molt. During both
pupping and molting seasons, the number of seals and the length of time
hauled out per day increase, from an average of 7 to 10-12 hours per
day (Harvey and Goley, 2011; Huber et al., 2001; Stewart and Yochem,
1994).
Harbor seals are the most commonly observed marine mammals in the
Thames River. Monthly observations over the 3-year marine mammal survey
yielded a total of 12 sightings of individual harbor seals (Tetra Tech,
2020). Most of the sightings were in the inner portion of the river,
north of the I-95 Bridge. No seals were observed hauled out onshore
(Tetra Tech, 2020), and there are no known haulout areas within the
Thames River (Navy, 2018). During marine mammal monitoring for Pier 32
construction activities that occurred from May 2022 through December
2022, only one harbor seal was recorded (Navy, 2023). Harbor seal
populations have increased in Connecticut since the 1980s and they are
common in Long Island Sound from September through June (Medic, 2005).
Harp Seal
Harp seals are highly migratory and occur throughout much of the
North Atlantic and Arctic Oceans (Hayes et al., 2019). Breeding occurs
between late-February and April and adults then assemble on suitable
pack ice to undergo the annual molt. The migration then continues north
to Arctic summer feeding grounds. Harp seal occurrence in the project
area is considered rare. However, since the early 1990s, numbers of
sightings and strandings have been increasing off the east coast of the
United States from Maine to New Jersey (Hayes et al., 2019). These
appearances usually occur in January through May (Harris et al., 2002),
when the western North Atlantic stock is at its most southern point of
migration.
Harp seals are not known to regularly occur in the Thames River as
previous surveys have not recorded their presence (Tetra Tech, 2020).
However, two harp seals were identified in March and one harp seal in
April 2019 by Mystic Aquarium staff. On both occasions they were
observed hauled out on the finger piers of the marina at SUBASE (Navy,
2019a). Harp seals are also expected to occur within Long Island Sound
from January through May (Hayes et al., 2022).
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), Southall et al. (2019) recommended that marine mammals be
divided into hearing groups based on directly measured (behavioral or
auditory evoked potential techniques) or estimated hearing ranges
(e.g., behavioral response data, anatomical modeling). NMFS (2024)
generalized hearing ranges were chosen based on the approximately 65-dB
threshold from the composite audiograms, previous analysis in NMFS
(2018), and/or data from Southall et al. (2007) and Southall
[[Page 9580]]
et al. (2019). We note that the names of two hearing groups and the
generalized hearing ranges of all marine mammal hearing groups have
been recently updated (NMFS, 2024) as reflected below in table 4.
Table 4--Marine Mammal Hearing Groups
[NMFS, 2024]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans 7 Hz to 36 ** kHz.
(baleen whales).
High-frequency (HF) cetaceans 150 Hz to 160 kHz.
(dolphins, toothed whales, beaked
whales, bottlenose whales).
Very High-frequency (VHF) cetaceans 200 Hz to 165 kHz.
(true porpoises, Kogia, river
dolphins, Cephalorhynchid,
Lagenorhynchus cruciger & L.
australis).
Phocid pinnipeds (PW) (underwater) 40 Hz to 90 kHz.
(true seals).
Otariid pinnipeds (OW) (underwater) 60 Hz to 68 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 the ~65-dB threshold from composite
audiogram, previous analysis in NMFS (2018), and/or data from Southall
et al. (2007) and Southall et al. (2019). Additionally, animals are
able to detect very loud sounds above and below that ``generalized''
hearing range.
** NMFS is aware Houser et al., (2024) data and data collected during a
final field season by Houser et al. (in prep) have implications for
the generalized hearing range for low-frequency cetaceans and their
weighting function, however, as described in the 2024 Updated
Technical Guidance, it is premature for us to propose any changes to
our current Updated Technical Guidance. Mysticete hearing data is
identified as a special circumstance that could merit reevaluating the
acoustic criteria for low-frequency cetaceans in the 2024 Updated
Technical Guidance once the data from the final field season is
published. Therefore, we anticipate that once the data are published,
it will likely necessitate updating this document (i.e., likely after
the data gathered in the summer 2024 field season and associated
analysis are published).
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2024) for a review of available information.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section provides a discussion of the ways in which components
of the specified activity may impact marine mammals and their habitat.
The Estimated Take of Marine Mammals section later in this document
includes a quantitative analysis of the number of individuals that are
expected to be taken by this activity. The Negligible Impact Analysis
and Determination section considers the content of this section, the
Estimated Take of Marine Mammals section, and the Proposed Mitigation
section, to draw conclusions regarding the likely impacts of these
activities on the reproductive success or survivorship of individuals
and whether those impacts are reasonably expected to, or reasonably
likely to, adversely affect the species or stock through effects on
annual rates of recruitment or survival.
Description of Sound Sources
The marine soundscape is comprised of both ambient and
anthropogenic sounds. Ambient sound is defined as the all-encompassing
sound in a given place and is usually a composite of sound from many
sources both near and far. The sound level of an area is defined by the
total acoustical energy being generated by known and unknown sources.
These sources may include physical (e.g., waves, wind, precipitation,
earthquakes, ice, atmospheric sound), biological (e.g., sounds produced
by marine mammals, fish, and invertebrates), and anthropogenic sound
(e.g., vessels, dredging, aircraft, construction).
The sum of the various natural and anthropogenic sound sources at
any given location and time--which comprise ``ambient'' or
``background'' sound--depends not only on the source levels (as
determined by current weather conditions and levels of biological and
shipping activity) but also on the ability of sound to propagate
through the environment. In turn, sound propagation is dependent on the
spatially and temporally varying properties of the water column and sea
floor, and is frequency-dependent. As a result of the dependence on a
large number of varying factors, ambient sound levels can be expected
to vary widely over both coarse and fine spatial and temporal scales.
Sound levels at a given frequency and location can vary by 10 to 20 dB
from day to day (Richardson et al., 1995). The result is that,
depending on the source type and its intensity, sound from the
specified activity may be a negligible addition to the local
environment or could form a distinctive signal that may affect marine
mammals.
In-water construction activities associated with the project would
include vibratory pile removal, drilling, and impact and vibratory pile
driving. The sounds produced by these activities fall into one of two
general sound types: impulsive and non-impulsive. Impulsive sounds
(e.g., explosions, gunshots, sonic booms, impact pile driving) are
typically transient, brief (less than 1 second), broadband, and consist
of high peak sound pressure with rapid rise time and rapid decay (ANSI,
1986; NIOSH, 1998; ANSI, 2005; NMFS, 2018a). Non-impulsive sounds
(e.g., aircraft, machinery operations such as drilling or dredging,
vibratory pile driving, and active sonar systems) can be broadband,
narrowband or tonal, brief or prolonged (continuous or intermittent),
and typically do not have the high peak sound pressure with raid rise/
decay time that impulsive sounds do (ANSI, 1995; NIOSH, 1998; NMFS,
2018a). The distinction between these two sound types is important
because they have differing potential to cause physical effects,
particularly with regard to hearing (e.g., Ward 1997 in Southall et
al., 2007).
The proposed specified activities to use drilling, and vibratory
and impact pile driving. Impact hammers operate by repeatedly dropping
a heavy piston onto a pile to drive the pile into the substrate. Sound
generated by impact hammers is characterized by rapid rise times and
high peak levels, a potentially injurious combination (Hastings and
Popper, 2005). Vibratory hammers install piles by vibrating them and
allowing the weight of the hammer to push them into the sediment.
Vibratory hammers produce significantly less sound than impact hammers.
Peak sound pressure levels (SPLs) may be 180 dB or greater, but are
generally 10 to 20 dB lower than SPLs generated during impact pile
driving of the same-sized pile (Oestman et al., 2009). Rise time is
slower, reducing the probability and severity of injury, and sound
energy is distributed over a greater amount of time (Nedwell and
Edwards, 2002; Carlson et al., 2005). Rotary drilling of rock sockets
(i.e., rotary drilling with spiral shaft through loose rock or soft
sediment)
[[Page 9581]]
would be used to remove sediment from the inside of the pipe pile
casing after the casing has been driven to its required depth via
vibratory and/or impact driving. The rock socket (rotary) is progressed
through the casing and the sediment is lifted out of the casing. Rotary
drills typically have lower sound levels than vibratory pile drivers
(154 decibels referenced to 1 micro Pascal (dB re 1 [micro]Pa)).
The likely or possible impacts of the proposed activity on marine
mammals could involve both non-acoustic and acoustic stressors.
Potential non-acoustic stressors could result from the physical
presence of equipment and personnel; however, any impacts to marine
mammals are expected to be primarily acoustic in nature. Acoustic
stressors include effects of heavy equipment operation during pile
installation and removal.
Acoustic Effects
The introduction of anthropogenic noise into the aquatic
environment from pile driving and removal is the means by which marine
mammals may be harassed by the specified activity. In general, animals
exposed to natural or anthropogenic sound may experience behavioral,
physiological, and/or physical effects, ranging in magnitude from none
to severe (Southall et al. 2007, 2019). In general, exposure to pile
driving and removal noise has the potential to result in behavioral
reactions (e.g., avoidance, temporary cessation of foraging and
vocalizing, changes in dive behavior) and, in limited cases, an
auditory threshold shift (TS). Exposure to anthropogenic noise can also
lead to non-observable physiological responses such an increase in
stress hormones. Additional noise in a marine mammal's habitat can mask
acoustic cues used by marine mammals to carry out daily functions such
as communication and predator and prey detection. The effects of pile
driving noise on marine mammals are dependent on several factors,
including, but not limited to, sound type (e.g., impulsive vs. non-
impulsive), the species, age and sex class (e.g., adult male vs. mom
with calf), duration of exposure, the distance between the pile and the
animal, received levels, behavior at time of exposure, and previous
history with exposure (Wartzok et al., 2004; Southall et al. 2007).
Here, we discuss physical auditory effects (TSs) followed by behavioral
effects and potential impacts on habitat.
NMFS defines a noise-induced TS as a change, usually an increase,
in the threshold of audibility at a specified frequency or portion of
an individual's hearing range above a previously established reference
level (NMFS, 2018, 2024). The amount of TS is customarily expressed in
dB. A TS can be permanent or temporary. As described in NMFS (2018,
2024), there are numerous factors to consider when examining the
consequence of TS, including, but not limited to, the signal temporal
pattern (e.g., impulsive or non-impulsive), likelihood an individual
would be exposed for a long enough duration or to a high enough level
to induce a TS, the magnitude of the TS, time to recovery (seconds to
minutes or hours to days), the frequency range of the exposure (i.e.,
spectral content), the hearing and vocalization frequency range of the
exposed species relative to the signal's frequency spectrum (i.e., how
animal uses sound within the frequency band of the signal; e.g.,
Kastelein et al. 2014), and the overlap between the animal and the
source (e.g., spatial, temporal, and spectral).
Auditory Injury (AUD INJ) and Permanent Threshold Shift (PTS)--NMFS
defines AUD INJ as ``damage to the inner ear that can result in
destruction of tissue . . . which may or may not result in PTS'' (NMFS,
2024). NMFS defines PTS as a permanent, irreversible increase in the
threshold of audibility at a specified frequency or portion of an
individual's hearing range above a previously established reference
level (NMFS, 2024). PTS does not generally affect more than a limited
frequency range, and an animal that has incurred PTS has incurred some
level of hearing loss at the relevant frequencies; typically, animals
with PTS are not functionally deaf (Au and Hastings, 2008; Finneran,
2016). Available data from humans and other terrestrial mammals
indicate that a 40 dB threshold shift approximates PTS onset (see Ward
et al. 1958, 1959, 1960; Kryter et al., 1966; Miller, 1974; Ahroon et
al., 1996; Henderson et al., 2008). PTS levels for marine mammals are
estimates, as with the exception of a single study unintentionally
inducing PTS in a harbor seal (Kastak et al., 2008), there are no
empirical data measuring PTS in marine mammals largely due to the fact
that, for various ethical reasons, experiments involving anthropogenic
noise exposure at levels inducing PTS are not typically pursued or
authorized (NMFS 2024, 2018).
Temporary Threshold Shift (TTS)--TTS is a temporary, reversible
increase in the threshold of audibility at a specified frequency or
portion of an individual's hearing range above a previously established
reference level (NMFS 2024, 2018). Based on data from cetacean TTS
measurements (Southall et al., 2007), a TTS of 6 dB is considered the
minimum TS clearly larger than any day-to-day or session-to-session
variation in a subject's normal hearing ability (Schlundt et al., 2000;
Finneran et al., 2000, 2002). As described in Finneran (2015), marine
mammal studies have shown the amount of TTS increases with cumulative
sound exposure level (SEL<INF>cum</INF>) in an accelerating fashion: At
low exposures with lower SEL<INF>cum,</INF> the amount of TTS is
typically small and the growth curves have shallow slopes. At exposures
with higher SEL<INF>cum,</INF> the growth curves become steeper and
approach linear relationships with the noise SEL.
Depending on the degree (elevation of threshold in dB), duration
(i.e., recovery time), and frequency range of TTS, and the context in
which it is experienced, TTS can have effects on marine mammals ranging
from discountable to serious (similar to those discussed in the
Auditory Masking section, below). For example, a marine mammal may be
able to readily compensate for a brief, relatively small amount of TTS
in a non-critical frequency range that takes place during a time when
the animal is traveling through the open ocean, where ambient noise is
lower and there are not as many competing sounds present.
Alternatively, a larger amount and longer duration of TTS sustained
during time when communication is critical for successful mother/calf
interactions could have more serious impacts. We note that reduced
hearing sensitivity as a simple function of aging has been observed in
marine mammals, as well as humans and other taxa (Southall et al.,
2007), so we can infer that strategies exist for coping with this
condition to some degree, though likely not without cost.
Many studies have examined noise-induced hearing loss in marine
mammals (see Finneran (2015) and Southall et al. (2019) for summaries).
TTS is the mildest form of hearing impairment that can occur during
exposure to sound (Kryter, 2013). While experiencing TTS, the hearing
threshold rises, and a sound must be at a higher level in order to be
heard. In terrestrial and marine mammals, TTS can last from minutes or
hours to days (in cases of strong TTS). In many cases, hearing
sensitivity recovers rapidly after exposure to the sound ends. For
cetaceans, published data on the onset of TTS are limited to captive
bottlenose dolphin (Tursiops truncatus), beluga whale, harbor porpoise,
and Yangtze finless porpoise (Neophocoena asiaeorientalis) (Southall et
al., 2019). For pinnipeds in water, measurements
[[Page 9582]]
of TTS are limited to harbor seals, elephant seals, bearded seals
(Erignathus barbatus) and California sea lions (Kastak et al., 1999,
2007; Kastelein et al., 2019b, 2019c, 2021, 2022a, 2022b; Reichmuth et
al., 2019; Sills et al., 2020). TTS was not observed in spotted (Phoca
largha) and ringed (Pusa hispida) seals exposed to single airgun
impulse sounds at levels matching previous predictions of TTS onset
(Reichmuth et al., 2016). These studies examine hearing thresholds
measured in marine mammals before and after exposure to intense or
long-duration sound exposures. The difference between the pre-exposure
and post-exposure thresholds can be used to determine the amount of
threshold shift at various post-exposure times.
The amount and onset of TTS depends on the exposure frequency.
Sounds at low frequencies, well below the region of best sensitivity
for a species or hearing group, are less hazardous than those at higher
frequencies, near the region of best sensitivity (Finneran and
Schlundt, 2013). At low frequencies, onset-TTS exposure levels are
higher compared to those in the region of best sensitivity (i.e., a low
frequency noise would need to be louder to cause TTS onset when TTS
exposure level is higher), as shown for harbor porpoises and harbor
seals (Kastelein et al., 2019a, 2019c). Note that in general, harbor
seals and harbor porpoises have a lower TTS onset than other measured
pinniped or cetacean species (Finneran, 2015). In addition, TTS can
accumulate across multiple exposures, but the resulting TTS will be
less than the TTS from a single, continuous exposure with the same SEL
(Mooney et al., 2009; Finneran et al., 2010; Kastelein et al., 2014,
2015). This means that TTS predictions based on the total, cumulative
SEL will overestimate the amount of TTS from intermittent exposures,
such as sonars and impulsive sources. Nachtigall et al. (2018) describe
measurements of hearing sensitivity of multiple odontocete species
(bottlenose dolphin, harbor porpoise, beluga, and false killer whale
(Pseudorca crassidens)) when a relatively loud sound was preceded by a
warning sound. These captive animals were shown to reduce hearing
sensitivity when warned of an impending intense sound. Based on these
experimental observations of captive animals, the authors suggest that
wild animals may dampen their hearing during prolonged exposures or if
conditioned to anticipate intense sounds. Another study showed that
echolocating animals (including odontocetes) might have anatomical
specializations that might allow for conditioned hearing reduction and
filtering of low-frequency ambient noise, including increased stiffness
and control of middle ear structures and placement of inner ear
structures (Ketten et al., 2021). Data available on noise-induced
hearing loss for mysticetes are currently lacking (NMFS, 2018).
Additionally, the existing marine mammal TTS data come from a limited
number of individuals within these species.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals, and there is no PTS data for cetaceans, but such
relationships are assumed to be similar to those in humans and other
terrestrial mammals. PTS typically occurs at exposure levels at least
several decibels above that inducing mild TTS (e.g., a 40-dB threshold
shift approximates PTS onset (Kryter et al., 1966; Miller, 1974), while
a 6-dB threshold shift approximates TTS onset (Southall et al., 2007,
2019). Based on data from terrestrial mammals, a precautionary
assumption is that the PTS thresholds for impulsive sounds (such as
impact pile driving pulses as received close to the source) are at
least 6 dB higher than the TTS threshold on a peak-pressure basis and
PTS cumulative sound exposure level thresholds are 15 to 20 dB higher
than TTS cumulative sound exposure level thresholds (Southall et al.,
2007, 2019). Given the higher level of sound or longer exposure
duration necessary to cause PTS as compared with TTS, it is
considerably less likely that PTS could occur.
Activities for this project include impact and vibratory pile
driving and vibratory removal. There would likely be pauses in
activities producing the sound during each day. Given these pauses and
the fact that many marine mammals are likely moving through the project
areas and not remaining for extended periods of time, the potential for
TS declines.
Behavioral Harassment--Exposure to noise from drilling and pile
driving and removal can also has the potential to behaviorally disturb
marine mammals. Generally speaking, NMFS considers a behavioral
disturbance that rises to the level of harassment under the MMPA a non-
minor response--in other words, not every response qualifies as
behavioral disturbance, and for responses that do, those of a higher
level, or accrued across a longer duration, have the potential to
affect foraging, reproduction, or survival. Behavioral disturbance may
include a variety of effects, including subtle changes in behavior
(e.g., minor or brief avoidance of an area or changes in
vocalizations), more conspicuous changes in similar behavioral
activities, and more sustained and/or potentially severe reactions,
such as displacement from or abandonment of high-quality habitat.
Behavioral responses may include changing durations of surfacing and
dives, changing direction and/or speed; reducing/increasing vocal
activities; changing/cessation of certain behavioral activities (such
as socializing or feeding); eliciting a visible startle response or
aggressive behavior (such as tail/fin slapping or jaw clapping);
avoidance of areas where sound sources are located. Pinnipeds may
increase their haul out time, possibly to avoid in-water disturbance
(Thorson and Reyff, 2006).
Behavioral responses to sound are highly variable and context-
specific and any reactions depend on numerous intrinsic and extrinsic
factors (e.g., species, state of maturity, experience, current
activity, reproductive state, auditory sensitivity, time of day), as
well as the interplay between factors (e.g., Richardson et al., 1995;
Wartzok et al., 2004; Southall et al., 2007, 2019; Weilgart, 2007;
Archer et al., 2010). Behavioral reactions can vary not only among
individuals but also within an individual, depending on previous
experience with a sound source, context, and numerous other factors
(Ellison et al., 2012), and can vary depending on characteristics
associated with the sound source (e.g., whether it is moving or
stationary, number of sources, distance from the source). In general,
pinnipeds seem more tolerant of, or at least habituate more quickly to,
potentially disturbing underwater sound than do cetaceans, and
generally seem to be less responsive to exposure to industrial sound
than most cetaceans. Please see Appendices B and C of Southall et al.
(2007) and Gomez et al. (2016) for reviews of studies involving marine
mammal behavioral responses to sound.
Habituation can occur when an animal's response to a stimulus wanes
with repeated exposure, usually in the absence of unpleasant associated
events (Wartzok et al., 2004). Animals are most likely to habituate to
sounds that are predictable and unvarying. It is important to note that
habituation is appropriately considered as a ``progressive reduction in
response to stimuli that are perceived as neither aversive nor
beneficial,'' rather than as, more generally, moderation in response to
human disturbance (Bejder et al., 2009). The opposite process is
[[Page 9583]]
sensitization, when an unpleasant experience leads to subsequent
responses, often in the form of avoidance, at a lower level of
exposure.
As noted above, behavioral state may affect the type of response.
For example, animals that are resting may show greater behavioral
change in response to disturbing sound levels than animals that are
highly motivated to remain in an area for feeding (Richardson et al.,
1995; Wartzok et al., 2004; National Research Council (NRC), 2005).
Controlled experiments with captive marine mammals have showed
pronounced behavioral reactions, including avoidance of loud sound
sources (Ridgway et al., 1997; Finneran et al., 2003). Observed
responses of wild marine mammals to loud pulsed sound sources (e.g.,
seismic airguns) have been varied but often consist of avoidance
behavior or other behavioral changes (Richardson et al., 1995; Morton
and Symonds, 2002; Nowacek et al., 2007).
Available studies show wide variation in response to underwater
sound; therefore, it is difficult to predict specifically how any given
sound in a particular instance might affect marine mammals perceiving
the signal. If a marine mammal does react briefly to an underwater
sound by changing its behavior or moving a small distance, the impacts
of the change are unlikely to be significant to the individual, let
alone the stock or population. However, if a sound source displaces
marine mammals from an important feeding or breeding area for a
prolonged period, impacts on individuals and populations could be
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC,
2005). However, there are broad categories of potential response, which
we describe in greater detail here, that include alteration of dive
behavior, alteration of foraging behavior, effects to breathing,
interference with or alteration of vocalization, avoidance, and flight.
Changes in dive behavior can vary widely and may consist of
increased or decreased dive times and surface intervals as well as
changes in the rates of ascent and descent during a dive (e.g., Frankel
and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et
al., 2004; Goldbogen et al., 2013a, 2013b). Variations in dive behavior
may reflect interruptions in biologically significant activities (e.g.,
foraging) or they may be of little biological significance. The impact
of an alteration to dive behavior resulting from an acoustic exposure
depends on what the animal is doing at the time of the exposure and the
type and magnitude of the response.
Disruption of feeding behavior can be difficult to correlate with
anthropogenic sound exposure, so it is usually inferred by observed
displacement from known foraging areas, the appearance of secondary
indicators (e.g., bubble nets or sediment plumes), or changes in dive
behavior. However, acoustic and movement bio-logging tools have been
used in some cases, to infer responses of feeding to anthropogenic
noise. For example, Blair et al. (2016) reported significant effects on
humpback whale foraging behavior in Stellwagen Bank in response to ship
noise including slower descent rates, and fewer side-rolling events per
dive with increasing ship nose. In addition, Wisniewska et al. (2018)
reported that tagged harbor porpoises demonstrated fewer prey capture
attempts when encountering occasional high-noise levels resulting from
vessel noise as well as more vigorous fluking, interrupted foraging,
and cessation of echolocation signals observed in response to some
high-noise vessel passes.
In response to playbacks of vibratory pile driving sounds, captive
bottlenose dolphins showed changes in target detection and number of
clicks used for a trained echolocation task (Branstetter et al., 2018).
Similarly, harbor porpoises trained to collect fish during playback of
impact pile driving sounds also showed potential changes in behavior
and task success, though individual differences were prevalent
(Kastelein et al., 2019d). As for other types of behavioral response,
the frequency, duration, and temporal pattern of signal presentation,
as well as differences in species sensitivity, are likely contributing
factors to differences in response in any given circumstance (e.g.,
Croll et al., 2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko
et al., 2007). A determination of whether foraging disruptions incur
fitness consequences would require information on or estimates of the
energetic requirements of the affected individuals and the
relationships among prey availability, foraging effort and success, and
the life history stage(s) of the animal.
Variations in respiration naturally vary with different behaviors
and alterations to breathing rate as a function of acoustic exposure
can be expected to co-occur with other behavioral reactions, such as a
flight response or an alteration in diving. However, respiration rates
in and of themselves may be representative of annoyance or an acute
stress response. Various studies have shown that respiration rates may
either be unaffected or could increase, depending on the species and
signal characteristics, again highlighting the importance in
understanding species differences in the tolerance of underwater noise
when determining the potential for impacts resulting from anthropogenic
sound exposure (e.g., Kastelein et al., 2001, 2005, 2006; Gailey et
al., 2007). For example, harbor porpoise' respiration rate increased in
response to pile driving sounds at and above a received broadband SPL
of 136 dB (zero-peak SPL: 151 dB (re 1 [mu]Pa); SEL of a single strike:
127 dB re 1 [mu]Pa\2\-s) (Kastelein et al., 2013).
Avoidance is the displacement of an individual from an area or
migration path as a result of the presence of a sound or other
stressors, and is one of the most obvious manifestations of disturbance
in marine mammals (Richardson et al., 1995). For example, gray whales
are known to change direction--deflecting from customary migratory
paths--in order to avoid noise from seismic surveys (Malme et al.,
1984). Avoidance may be short-term, with animals returning to the area
once the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996;
Stone et al., 2000; Morton and Symonds, 2002; Gailey et al., 2007).
Longer-term displacement is possible, however, which may lead to
changes in abundance or distribution patterns of the affected species
in the affected region if habituation to the presence of the sound does
not occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann
et al., 2006).
A flight response is a dramatic change in normal movement to a
directed and rapid movement away from the perceived location of a sound
source. The flight response differs from other avoidance responses in
the intensity of the response (e.g., directed movement, rate of
travel). Relatively little information on flight responses of marine
mammals to anthropogenic signals exist, although observations of flight
responses to the presence of predators have occurred (Connor and
Heithaus, 1996; Bowers et al., 2018). The result of a flight response
could range from brief, temporary exertion and displacement from the
area where the signal provokes flight to, in extreme cases, marine
mammal strandings (England et al., 2001). However, it should be noted
that response to a perceived predator does not necessarily invoke
flight (Ford and Reeves, 2008), and whether individuals are solitary or
in groups may influence the response.
Behavioral disturbance can also impact marine mammals in more
subtle ways. Increased vigilance may result in costs related to
diversion of focus and attention (i.e., when a response consists of
increased vigilance, it may come at
[[Page 9584]]
the cost of decreased attention to other critical behaviors such as
foraging or resting). These effects have generally not been
demonstrated for marine mammals, but studies involving fishes and
terrestrial animals have shown that increased vigilance may
substantially reduce feeding rates (e.g., Beauchamp and Livoreil, 1997;
Fritz et al., 2002; Purser and Radford, 2011). In addition, chronic
disturbance can cause population declines through reduction of fitness
(e.g., decline in body condition) and subsequent reduction in
reproductive success, survival, or both (e.g., Harrington and Veitch,
1992; Daan et al., 1996; Bradshaw et al., 1998). However, Ridgway et
al. (2006) reported that increased vigilance in bottlenose dolphins
exposed to sound over a 5-day period did not cause any sleep
deprivation or stress effects.
Many animals perform vital functions, such as feeding, resting,
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption
of such functions resulting from reactions to stressors such as sound
exposure are more likely to be significant if they last more than one
diel cycle or recur on subsequent days (Southall et al., 2007).
Consequently, a behavioral response lasting less than 1 day and not
recurring on subsequent days is not considered particularly severe
unless it could directly affect reproduction or survival (Southall et
al., 2007). Note that there is a difference between multi-day
substantive (i.e., meaningful) behavioral reactions and multi-day
anthropogenic activities. For example, just because an activity lasts
for multiple days does not necessarily mean that individual animals are
either exposed to activity-related stressors for multiple days or,
further, exposed in a manner resulting in sustained multi-day
substantive behavioral responses.
Stress Responses--An animal's perception of a threat may be
sufficient to trigger stress responses consisting of some combination
of behavioral responses, autonomic nervous system responses,
neuroendocrine responses, or immune responses (e.g., Seyle, 1950;
Moberg, 2000). In many cases, an animal's first and sometimes most
economical (in terms of energetic costs) response is behavioral
avoidance of the potential stressor. Autonomic nervous system responses
to stress typically involve changes in heart rate, blood pressure, and
gastrointestinal activity. These responses have a relatively short
duration and may or may not have a significant long-term effect on an
animal's fitness.
Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that
are affected by stress--including immune competence, reproduction,
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been
implicated in failed reproduction, altered metabolism, reduced immune
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha,
2000). Increases in the circulation of glucocorticoids are also equated
with stress (Romano et al., 2004).
The primary distinction between stress (which is adaptive and does
not normally place an animal at risk) and ``distress'' is the cost of
the response. During a stress response, an animal uses glycogen stores
that can be quickly replenished once the stress is alleviated. In such
circumstances, the cost of the stress response would not pose serious
fitness consequences. However, when an animal does not have sufficient
energy reserves to satisfy the energetic costs of a stress response,
energy resources must be diverted from other functions. This state of
distress will last until the animal replenishes its energetic reserves
sufficient to restore normal function.
Relationships between these physiological mechanisms, animal
behavior, and the costs of stress responses are well-studied through
controlled experiments and for both laboratory and free-ranging animals
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003;
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to
exposure to anthropogenic sounds or other stressors and their effects
on marine mammals have also been reviewed (Fair and Becker, 2000;
Romano et al., 2002b) and, more rarely, studied in wild populations
(e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found
that noise reduction from reduced ship traffic in the Bay of Fundy was
associated with decreased stress in North Atlantic right whales. These
and other studies lead to a reasonable expectation that some marine
mammals would experience physiological stress responses upon exposure
to acoustic stressors and that it is possible that some of these would
be classified as ``distress''. In addition, any animal experiencing TTS
would likely also experience stress responses (NRC, 2003), however
distress is an unlikely result of this project based on observations of
marine mammals during previous, similar projects in the area.
Auditory Masking--Since many marine mammals rely on sound to find
prey, moderate social interactions, and facilitate mating (Tyack,
2008), noise from anthropogenic sound sources can interfere with these
functions, but only if the noise spectrum overlaps with the hearing
sensitivity of the receiving marine mammal (Southall et al., 2007;
Clark et al., 2009; Hatch et al., 2012). Chronic exposure to excessive,
though not high-intensity, noise could cause masking at particular
frequencies for marine mammals that utilize sound for vital biological
functions (Clark et al., 2009). Acoustic masking is when other noises
such as from human sources interfere with an animal's ability to
detect, recognize, or discriminate between acoustic signals of interest
(e.g., those used for intraspecific communication and social
interactions, prey detection, predator avoidance, navigation)
(Richardson et al., 1995; Erbe et al., 2016). Therefore, under certain
circumstances, marine mammals whose acoustical sensors or environment
are being severely masked could also be impaired from maximizing their
performance fitness in survival and reproduction. The ability of a
noise source to mask biologically important sounds depends on the
characteristics of both the noise source and the signal of interest
(e.g., signal-to-noise ratio, temporal variability, direction), in
relation to each other and to an animal's hearing abilities (e.g.,
sensitivity, frequency range, critical ratios, frequency
discrimination, directional discrimination, age or TTS hearing loss),
and existing ambient noise and propagation conditions (Hotchkin and
Parks, 2013).
Marine mammals vocalize for different purposes and across multiple
modes, such as whistling, echolocation click production, calling, and
singing. Changes in vocalization behavior in response to anthropogenic
noise can occur for any of these modes and may result from a need to
compete with an increase in background noise or may reflect increased
vigilance or a startle response. For example, in the presence of
potentially masking signals, humpback whales and killer whales have
been observed to increase the length of their songs (Miller et al.,
2000; Fristrup et al., 2003) or vocalizations (Foote et al., 2004),
respectively, while North Atlantic right whales (Eubalaena glacialis)
have been observed to shift the frequency content of their calls upward
while reducing the rate of calling in areas of increased anthropogenic
noise (Parks et al., 2007). Fin whales have also been documented
lowering the bandwidth, peak frequency, and center frequency of their
vocalizations under increased levels of background noise
[[Page 9585]]
from large vessels (Castellote et al., 2012). Other alterations to
communication signals have also been observed. For example, gray
whales, in response to playback experiments exposing them to vessel
noise, have been observed increasing their vocalization rate and
producing louder signals at times of increased outboard engine noise
(Dahlheim and Castellote, 2016). Alternatively, animals may cease sound
production during production of aversive signals (Bowles et al., 1994).
Under certain circumstances, marine mammals experiencing
significant masking could also be impaired from maximizing their
performance fitness in survival and reproduction. Therefore, when the
coincident (masking) sound is human-made, it may be considered
harassment when disrupting or altering critical behaviors. It is
important to distinguish TTS and PTS, which persist after the sound
exposure, from masking, which occurs during the sound exposure. Because
masking (without resulting in TS) is not associated with abnormal
physiological function, it is not considered a physiological effect,
but rather a potential behavioral effect (though not necessarily one
that would be associated with harassment).
The frequency range of the potentially masking sound is important
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation
sounds produced by odontocetes but are more likely to affect detection
of mysticete communication calls and other potentially important
natural sounds such as those produced by surf and some prey species.
The masking of communication signals by anthropogenic noise may be
considered as a reduction in the communication space of animals (e.g.,
Clark et al., 2009) and may result in energetic or other costs as
animals change their vocalization behavior (e.g., Miller et al., 2000;
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2010; Holt
et al., 2009). Masking can be reduced in situations where the signal
and noise come from different directions (Richardson et al., 1995),
through amplitude modulation of the signal, or through other
compensatory behaviors (Hotchkin and Parks, 2013). Masking can be
tested directly in captive species (e.g., Erbe, 2008), but in wild
populations it must be either modeled or inferred from evidence of
masking compensation. There are few studies addressing real-world
masking sounds likely to be experienced by marine mammals in the wild
(e.g., Branstetter et al., 2013).
Marine mammals at or near the proposed project site may be exposed
to anthropogenic noise which may be a source of masking. Vocalization
changes may result from a need to compete with an increase in
background noise and include increasing the source level, modifying the
frequency, increasing the call repetition rate of vocalizations, or
ceasing to vocalize in the presence of increased noise (Hotchkin and
Parks, 2013). For example, in response to loud noise, beluga whales may
shift the frequency of their echolocation clicks to prevent masking by
anthropogenic noise (Eickmeier and Vallarta, 2022).
Masking occurs in the frequency band or bands that animals utilize
and is more likely to occur in the presence of broadband, relatively
continuous noise sources such as vibratory pile driving. Energy
distribution of pile driving covers a broad frequency spectrum, and
sound from pile driving would be within the audible range of pinnipeds
and cetaceans present in the proposed action area. While some
construction during the specified activities may mask some acoustic
signals that are relevant to the daily behavior of marine mammals, the
short-term duration and limited areas affected make it very unlikely
that the fitness of individual marine mammals would be impacted.
Airborne Acoustic Effects--Pinnipeds that may occur near the
project site could be exposed to airborne sounds associated with
construction activities that have the potential to cause behavioral
harassment, depending on their distance from these activities. Airborne
noise would primarily be an issue for pinnipeds that are swimming or
hauled out near the project site within the range of noise levels
elevated above airborne acoustic harassment criteria. There is also a
possibility that an animal could surface in-water, but with head out,
within the area in which airborne sound exceeds relevant thresholds and
thereby be exposed to levels of airborne sound that we associate with
harassment. However, as a result of the mitigation and monitoring
measures and due to the infrequent occurrence of marine mammals in the
area, takes by behavioral harassment resulting from airborne sounds
that would result in harassment as defined under the MMPA are not
expected.
Marine Mammal Habitat Effects
The proposed specified activities could have localized, temporary
impacts on marine mammal habitat and their prey by increasing in-water
SPLs and slightly decreasing water quality. Increased noise levels may
affect acoustic habitat (see Auditory Masking discussion above) and
adversely affect marine mammal prey in the vicinity of the project area
(see discussion below). During drilling, in-water vibratory and impact
pile driving, elevated levels of underwater noise would ensonify the
project area where both fish and some mammals occur and could affect
foraging success.
Water Quality--Temporary and localized reduction in water quality
would occur as a result of in-water construction activities. Most of
this effect would occur during the installation and removal of piles
when bottom sediments are disturbed. The installation and removal of
piles would disturb bottom sediments and may cause a temporary increase
in suspended sediment in the project area. During pile removal,
sediment attached to the pile moves vertically through the water column
until gravitational forces cause it to slough off under its own weight.
The small resulting sediment plume is expected to settle out of the
water column within a few hours. Studies of the effects of turbid water
on fish (marine mammal prey) suggest that concentrations of suspended
sediment can reach thousands of milligrams per liter before an acute
toxic reaction is expected (Burton, 1993).
Effects to turbidity and sedimentation are expected to be short-
term, minor, and localized. Suspended sediments in the water column
should dissipate and quickly return to background levels in all
construction scenarios. Turbidity within the water column has the
potential to reduce the level of oxygen in the water and irritate the
gills of prey fish species in the proposed project area. However,
turbidity plumes associated with the project would be temporary and
localized, and fish in the proposed project area would be able to move
away from and avoid the areas where plumes may occur. Therefore, it is
expected that the impacts on prey fish species from turbidity, and
therefore on marine mammals, would be minimal and temporary. In
general, the area likely impacted by the proposed construction
activities is relatively small compared to the available marine mammal
habitat in the area, and does not include any areas of particular
importance.
In-Water Construction Effects on Potential Prey--Sound may affect
marine mammals through impacts on the abundance, behavior, or
distribution of prey species (e.g., crustaceans, cephalopods, fish,
zooplankton). Marine mammal prey varies by species, season, and
location and, for some, is not well documented. Here, we describe
studies
[[Page 9586]]
regarding the effects of noise on known marine mammal prey.
Fish utilize the soundscape and components of sound in their
environment to perform important functions such as foraging, predator
avoidance, mating, and spawning (e.g., Zelick et al., 1999; Fay, 2009).
Depending on their hearing anatomy and peripheral sensory structures,
which vary among species, fishes hear sounds using pressure and
particle motion sensitivity capabilities and detect the motion of
surrounding water (Fay et al., 2008). The potential effects of noise on
fishes depends on the overlapping frequency range, distance from the
sound source, water depth of exposure, and species-specific hearing
sensitivity, anatomy, and physiology. Key impacts to fishes may include
behavioral responses, hearing damage, barotrauma (pressure-related
injuries), and mortality.
Fish react to sounds which are especially strong and/or
intermittent low-frequency sounds, and behavioral responses such as
flight or avoidance are the most likely effects. Short duration, sharp
sounds can cause overt or subtle changes in fish behavior and local
distribution. The reaction of fish to noise depends on the
physiological state of the fish, past exposures, motivation (e.g.,
feeding, spawning, migration), and other environmental factors.
Hastings and Popper (2005) identified several studies that suggest fish
may relocate to avoid certain areas of sound energy. Additional studies
have documented effects of pile driving on fish, although several are
based on studies in support of large, multiyear bridge construction
projects (e.g., Scholik and Yan, 2001, 2002; Popper and Hastings,
2009). Several studies have demonstrated that impulse sounds might
affect the distribution and behavior of some fishes, potentially
impacting foraging opportunities or increasing energetic costs (e.g.,
Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski et al.,
1992; Santulli et al., 1999; Paxton et al., 2017). However, some
studies have shown no or slight reaction to impulse sounds (e.g., Pena
et al., 2013; Wardle et al., 2001; Jorgenson and Gyselman, 2009; Cott
et al., 2012). More commonly, though, the impacts of noise on fish are
temporary.
SPLs of sufficient strength have been known to cause injury to fish
and fish mortality. However, in most fish species, hair cells in the
ear continuously regenerate and loss of auditory function likely is
restored when damaged cells are replaced with new cells. Halvorsen et
al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours
for one species. Impacts would be most severe when the individual fish
is close to the source and when the duration of exposure is long.
Injury caused by barotrauma can range from slight to severe and can
cause death, and is most likely for fish with swim bladders. Barotrauma
injuries have been documented during controlled exposure to impact pile
driving (Halvorsen et al., 2012b; Casper et al., 2013).
The greatest potential impact to fishes during construction would
occur during impact pile installation. In-water construction activities
would only occur during daylight hours, allowing fish to forage and
transit the project area in the evening. Vibratory pile driving would
possibly elicit behavioral reactions from fishes such as temporary
avoidance of the area but is unlikely to cause injuries to fishes or
have persistent effects on local fish populations. Construction also
would have minimal permanent and temporary impacts on benthic
invertebrate species, a marine mammal prey source. In addition, it
should be noted that the area in question is low-quality habitat since
it is already highly developed and experiences a high level of
anthropogenic noise from normal operations and other vessel traffic. In
general, any negative impacts on marine mammal prey species are
expected to be minor and temporary.
Fish populations in the proposed project area that serve as marine
mammal prey could be temporarily affected by noise from pile
installation and removal. The frequency range in which fishes generally
perceive underwater sounds is 50 to 2,000 Hz, with peak sensitivities
below 800 Hz (Popper and Hastings, 2009). Fish behavior or distribution
may change, especially with strong and/or intermittent sounds that
could harm fishes. High underwater SPLs have been documented to alter
behavior, cause hearing loss, and injure or kill individual fish by
causing serious internal injury (Hastings and Popper, 2005).
The most likely impact to fish from drilling and pile driving and
removal activities in the project area would be temporary behavioral
avoidance of the area. The duration of fish avoidance of an area after
pile driving and drilling stops is unknown, but a rapid return to
normal recruitment, distribution and behavior is anticipated. In
general, impacts to marine mammal prey species are expected to be minor
and temporary due to the expected short daily duration of individual
pile driving and drilling events.
In-Water Construction Effects on Potential Foraging Habitat--The
area likely impacted by the project is relatively small compared to the
available habitat in the New England area and does not include any
biologically important areas (BIAs) or ESA-designated critical habitat.
The total area affected by the project is small compared to the vast
foraging area available to marine mammals in the area. Pile driving and
removal at the project site would not obstruct long-term movements or
migration of marine mammals.
Avoidance by potential prey (i.e., fish) of the immediate area due
to the temporary loss of this foraging habitat is also possible. The
duration of fish and marine mammal avoidance of this area after pile
driving stops is unknown, but a rapid return to normal recruitment,
distribution, and behavior is anticipated. Any behavioral avoidance by
fish or marine mammals of the disturbed area would still leave
significantly large areas of fish and marine mammal foraging habitat in
the nearby vicinity.
In summary, given the short daily duration of sound associated with
individual pile driving events and the relatively small areas being
affected, pile driving activities associated with the proposed action
are not likely to have a permanent adverse effect on any fish habitat,
or populations of fish species. Any behavioral avoidance by fish of the
disturbed area would still leave significantly large areas of fish and
marine mammal foraging habitat in the nearby vicinity. Thus, we
conclude that impacts of the specified activity are not likely to have
more than short-term adverse effects on any prey habitat or populations
of prey species. Further, any impacts to marine mammal habitat are not
expected to result in significant or long-term consequences for
individual marine mammals, or to contribute to adverse impacts on their
populations.
Estimated Take of Marine Mammals
This section estimates the number of incidental takes proposed for
authorization through the IHA. This information will inform NMFS'
consideration of ``small numbers'' and the negligible impact
determinations.
Harassment is the only type of take expected to result from these
activities. Except for 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);
[[Page 9587]]
or (ii) has the potential to disturb a marine mammal or marine mammal
stock in the wild by disrupting behavioral patterns, including, but not
limited to, migration, breathing, nursing, breeding, feeding, or
sheltering (Level B harassment).
Authorized takes would be by Level B harassment, as using acoustic
sources (i.e., vibratory or impact pile driving and rotary drilling)
can potentially disrupt behavioral patterns for individual marine
mammals. However, the proposed 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 proposed to be authorized for this activity. Below, we
describe how the proposed take numbers are estimated.
For acoustic impacts, generally speaking, we estimate take by
considering (1) acoustic criteria above which NMFS believes the best
available science indicates that marine mammals would likely be
behaviorally harassed or incur some degree of AUD INJ; (2) the area or
volume of water that would be ensonified above these levels in a day;
(3) the density or occurrence of marine mammals within these ensonified
areas; and (4) the number of days of activities. 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 in more detail and present the proposed take
estimates.
Acoustic Criteria
NMFS recommends using acoustic criteria to identify the received
level of underwater sound above which exposed marine mammals would
reasonably expect to be behaviorally harassed (equated to Level B
harassment) or incur AUD INJ of some degree (equated to Level A
harassment). We note that the criteria for AUD INJ and the names of two
hearing groups have been recently updated (NMFS 2024), as reflected
below in the Level A Harassment section.
Level B Harassment--Though significantly driven by the 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
complex 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 predictable and measurable metric
for most activities, NMFS typically uses a generalized acoustic
threshold based on the 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 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 TTS.
In most cases, the likelihood of TTS occurring at distances from the
source is less than at which behavioral harassment is probable. TTS of
a sufficient degree can manifest as behavioral harassment, as reduced
hearing sensitivity and the potential reduced opportunities to detect
essential signals (conspecific communication, predators, and prey) may
result in changes in behavior patterns that would not otherwise occur.
The proposed activity includes continuous (vibratory pile driving,
rotary drilling) and impulsive (impact pile driving) sources;
therefore, the RMS SPL thresholds of 120 and 160 dB re 1 [mu]Pa are
applicable.
Level A Harassment--NMFS' Updated Technical Guidance for Assessing
the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version
3.0) (NMFS 2024) identifies dual criteria to assess AUD INJ (Level A
harassment) to five different underwater 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 proposed
activity includes using impulsive (impact pile driving) and non-
impulsive (vibratory pile driving/removal, drilling) sources.
The 2024 Updated Technical Guidance criteria include updated
thresholds and weighting functions for each hearing group, provided in
table 5 below. The references, analysis, and methodology used to
develop the criteria are described in NMFS' 2024 Updated Technical
Guidance, which may be accessed at <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools</a>.
Table 5--Thresholds Identifying the Onset of Permanent Threshold Shift
[AUD INJ]
----------------------------------------------------------------------------------------------------------------
AUD INJ onset thresholds * (received level)
Hearing group -------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans.......... Cell 1: L0-pk,flat: 222 Cell 2: LE,LF,24h: 197 dB.
dB; LE,LF,24h: 183 dB.
High-Frequency (HF) Cetaceans......... Cell 3: L0-pk,flat: 230 Cell 4: LE,HF,24h: 201 dB.
dB; LE,HF,24h: 193 dB.
Very High-Frequency (VHF) Cetaceans... Cell 5: L0-pk,flat: 202 Cell 6: LE,VHF,24h: 181 dB.
dB; LE,VHF,24h: 159 dB.
Phocid Pinnipeds (PW) (Underwater).... Cell 7: L0-pk.flat: 223 Cell 8: LE,PW,24h: 195 dB.
dB; LE,PW,24h: 183 dB.
Otariid Pinnipeds (OW) (Underwater)... Cell 9: L0-pk,flat: 230 Cell 10: LE,OW,24h: 199 dB.
dB; LE,OW,24h: 185 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating AUD
INJ 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.
[[Page 9588]]
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 Hz to 165 kHz). The subscript associated with cumulative sound
exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, HF, and VHF
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 the operational and environmental parameters of
the activity 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 proposed project.
Marine mammals are expected to be affected via sound generated by the
primary components of the project (i.e., vibratory pile driving,
vibratory pile removal, impact pile driving, and rotary drilling).
Level B Harassment Zones
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, bottom composition, and
topography. The general formula for underwater TL is:
TL = B * Log<INF>10</INF> (R<INF>1</INF>/R<INF>2</INF>),
Where:
TL = transmission loss in dB
B = transmission loss coefficient; for practical spreading equals 15
R<INF>1</INF> = the distance of the modeled SPL from the driven
pile, and
R<INF>2</INF> = 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 depends on various factors, most
notably the water bathymetry and the 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*log<INF>10</INF>[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*log<INF>10</INF>[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 occurs. 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. The project includes
vibratory and impact pile installation, vibratory removal of piles, and
drilling. Source levels for each pile size and driving method are
presented in table 6.
Table 6--Proxy Sound Source Levels for Pile Sizes, Driving Methods, and Drilling
--------------------------------------------------------------------------------------------------------------------------------------------------------
Installation/ Peak (dB re 1 RMS (dB re 1 SEL (dB re 1
Pile type extraction method Pile diameter [micro]Pa) [micro]Pa) [micro]Pa \2\ sec) Source
--------------------------------------------------------------------------------------------------------------------------------------------------------
Steel H-pile..................... Vibratory........... 14-inch............ NA 158 158 Navy, 2019b, Table
6-4.
Concrete-encased Steel H-piles, Vibratory........... 24-inch............ NA 162 NA Greenbusch 2018.
and Cast-in-place.
Fiberglass, reinforced plastic... Vibratory........... 16-inch............ NA 158 NA Illingworth and
Rodkin, 2017.
Impact.............. 16-inch............ 177 165 157 California
Department of
Transportation,
2015.
Concrete-filled steel pipe piles Rock Socket Rotary All sizes.......... NA 154 NA Dazey et al., 2012.
and fiberglass reinforced Drilling.
plastic fender piles.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: All sound pressure levels (SPLs) are unattenuated; dB = decibels; SEL = sound exposure level; single strike SEL are the proxy source levels
presented for impact pile driving and were used to calculate distances to AUD INJ; dB re 1 [micro]Pa = dB referenced to a pressure of 1 microPascal,
measures underwater SPL dB re 1 [micro]Pa\2\-sec = dB referenced to a pressure of 1 microPascal squared per second.
The farthest extent to the Level B harassment threshold for marine
mammals would be a distance of 6,310 meters during vibratory extraction
of 24-inch concrete-encased steel H-piles and 24-inch cast-in-place
reinforced concrete piles from Pier 10 (table 8). However, this
distance would be truncated due to the presence of intersecting land
masses and would encompass a maximum area of 3.85 sq km.
Vibratory extraction of the HP14x89 steel fender piles would create
the largest predicted Level A harassment isopleth, with a radius of
33.6 meters. Vibratory extraction of 24-inch cast-in-place reinforced
concrete piles would create the largest Level B harassment zone for
approximately 18 days. Level A and Level B harassment radii would be
larger at 84.4 meters and 8,577 meters, respectively during concurrent
activities that would occur for approximately 3 days (table 8).
[[Page 9589]]
Table 7--Calculated Distances to Harassment Thresholds for Individual Activities: Impulsive
[Impact pile driving]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Level A (AUD INJ onset) harassment Level B (behavioral)
------------------------------------------------------------------ harassment--all
HF cetacean VHF cetacean Phocid marine mammals
---------------------------------------------------------------------------------------
Structure Pile size and type Activity Total production Maximum distance to Maximum distance to Maximum distance to Maximum distance 160
days 193 dB SELcum 159 dB SELcum 183 dB SELcum dB RMS SPL threshold
threshold (m)/ area threshold(m)/ area threshold(m)/ area (m)/ area of
of harassment zone of harassment zone of harassment zone harassment zone (sq
(sq km) (sq km) (sq km) km)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Pier 10 Quay Wall Construction/ 16-inch polymeric fender Impact Install....... 2 3.7/<0.001 45.2/0.004 25.9/0.001 22/<0.001
Repair (January-February 2026). piles with H-pile
extension.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Legend: AUD INJ = Auditory Injury; HF = high frequency; VHF = very high frequency; dB SELcum = cumulative sound exposure level; m = meter; sq km = square kilometer; dB RMS SPL = decibel root
mean square sound pressure level.
Table 8--Calculated Distances to Harassment Thresholds for Individual Activities: Non-Impulsive Continuous
[Vibratory installation/extraction and rock socket [rotary] drilling]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Level A (AUD INJ onset) harassment Level B (behavioral)
------------------------------------------------------------------ harassment--all
HF cetacean VHF cetacean Phocid marine mammals
---------------------------------------------------------------------------------------
Structure Pile size and type Activity Total production Maximum distance to Maximum distance to Maximum distance to Maximum distance 120
days 201 dB SELcum 181 dB SELcum 195 dB SELcum dB RMS SPL threshold
threshold (m)/ area threshold(m)/ area threshold(m)/ area (m)/ area of
of harassment zone of harassment zone of harassment zone harassment zone (sq
(sq km) (sq km) (sq km) km)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Pier 10 Demolition/Pile Removal HP14x89 steel Fender H- Vibratory Extraction. 2.5 10/<0.001 21.3/0.001 33.6/0.004 3,415/2.92
(August-December 2026). piles.
24-inch concrete-encased Vibratory Extraction. 2.5 8.9/<0.001 18.9/0.001 29.8/0.003 6,310/3.86
steel H-piles.
24-inch cast-in-place Vibratory Extraction. 17.5 8.9/<0.001 18.9/0.001 29.8/0.003 6,310/3.86
reinforced concrete piles.
CWTA Quay Wall Demolition HP14 Steel Fender H-piles. Vibratory Extraction. 1.67 7.4/<0.001 15.7/<0.001 24.7/0.001 3,415/1.04
(November-December 2026).
CWTA Construction/Pile 30-inch x 100-ft concrete- Rock socket (rotary) 36 0.2/0 0.2/0 0.6/<0.001 1,848/0.772
Installation (December 2026). filled, steel pipe piles. drilling.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Legend: AUD INJ = Auditory Injury; HF = high frequency; VHF = very high frequency; dB SELcum = cumulative sound exposure level; m = meter; sq km = square kilometer; dB RMS SPL = decibel root
mean square sound pressure level.
[[Page 9590]]
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 or 3 dB, 2 dB are added to the highest sound source
levels; if the difference is between 4 to 9 dB, 1 dB is added to the
highest sound source levels; and with differences of 10 or more
decibels, 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. For example, with overlapping isopleths from 24-, 36-, and 42-
inch diameter steel pipe piles with sound source levels of 161, 167,
and 168 dB RMS respectively, the 24- and 36-inch would be added
together; given that 167-161 = 6 dB, then 1 dB is added to the highest
of the two sound source levels (167 dB), for a combined noise level of
168 dB. Next, the newly calculated 168 dB is added to the 42-inch steel
pile with sound source levels of 168 dB. Since 168-168 = 0 dB, 3 dB is
added to the highest value, or 171 dB in total for the combination of
24-, 36-, and 42-inch steel pipe piles.
By using the rules of decibel addition method, a revised proxy
source for Level A and Level B analysis was determined for the use of
the concurrent non-impulsive activity scenarios. The revised proxy
values are presented in table 9 and the resulting harassment zones for
concurrent activities are shown in table 10.
There is one anticipated scenario when an impact hammer and
vibratory hammer and extractor are occurring simultaneously. In the
situation where an impact and vibratory hammer are used concurrently,
the largest zone generated by either the vibratory hammer or impact
hammer would be used (table 2).
[[Page 9591]]
Table 9--Calculated Proxy Sound Source Levels for Potential Concurrent Pile Driving Scenarios
--------------------------------------------------------------------------------------------------------------------------------------------------------
New proxy for non-
Structure Activity and proxy impulsive
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pier 10 Demolition/Removal; CWTA Demolition; CWTA Construction/ Vibratory Extraction HP14x89 steel H-piles--158 dB RMS........... 164 dB RMS
Pile Installation. Vibratory Extraction 24-inch concrete-encased steel H-piles--162
dB RMS..
Vibratory Extraction 24-inch cast-in-place reinforced concrete
piles--162 dB RMS..
Vibratory Extraction HP14 steel H-piles--158 dB RMS..............
Rock socket (rotary) drilling 30-inch concrete-filled steel pipe--
154 dB RMS..
Pier 10 Quay Wall Construction/Repair; CWTA Construction/Pile Impact Installation 16-inch polymeric pile with H-pile extension-- 154 dB RMS
Installation. 157 dB SEL\1\.
Rock socket (rotary) drilling 16-inch fiberglass reinforced
plastic piles--154 dB RMS.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Legend: dB RMS = decibel root mean square; dB SEL = decibel sound exposure level.
Notes: Per the rules of combining sound levels generated during impact pile installation, each impact proxy per pile type is modeled. When impact and
vibratory are occurring concurrently, the larger zone is modeled.
\1\ Although impact pile driving would occur concurrently with rock socket (rotary) drilling, mapping harassment zones and calculating takes will still
occur separately for impact pile driving (impulsive) from rock socket (rotary) drilling (non-impulsive).
Table 10--Calculated Distances to Harassment Thresholds for Concurrent Activities: Non-Impulsive Continuous
[Vibratory extraction/rock socket drilling)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Level A (AUD INJ onset) harassment Level B (behavioral)
------------------------------------------------------------------ harassment--all
HF cetacean VHF cetacean Phocid marine mammals
---------------------------------------------------------------------------------------
Structure Pile size and type Activity Total production Maximum distance to Maximum distance to Maximum distance to Maximum distance 120
days 201 dB SELcum 181 dB SELcum 195 dB SELcum dB RMS SPL threshold
threshold (m)/ area threshold(m)/ area threshold(m)/ area (m)/ area of
of harassment zone of harassment zone of harassment zone harassment zone (sq
(sq km) (sq km) (sq km) km)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Concurrent Pile Driving (3 days) HP14x89 steel H-pile, 24- Vibratory Extract and 2.5 \1\ 25.2/0.002 \1\ 53.6/0.009 \1\ 84.4/0.022 \1\ 8,577/4.57
of vibratory extraction of inch concrete-encased Rock socket (rotary) \2\ 0.8/<0.001 \2\ 1.1/<0.001 \2\ 2.8/<0.001 \2\ 8,577/1.04
HP14x89 steel H-piles from Pier steel H-Piles, 24-inch Drill.
10, Vibratory extraction of HP14 cast-in-place reinforced
Steel fender H-piles from CWTA, concrete piles, 30-inch x
Rock socket (rotary) drilling of 100-ft concrete-filled
30-inch x 100-ft concrete-filled steel pipe.
steel pipe for CWTA construction..
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Legend: AUD INJ = Auditory Injury; HF = high frequency; VHF = very high frequency; dB SELcum = cumulative sound exposure level; m = meter; sq km = square kilometer; dB RMS SPL = decibel root
mean square sound pressure level.
Notes:
\1\ Harassment zones mapped from Pier 10.
\2\ Harassment zones mapped from CWTA.
[[Page 9592]]
Marine Mammal Occurrence and Take Estimation
In this section, we provide information about the occurrence of
marine mammals, including density or other relevant information that
will inform the take calculations, and describe how the information
provided is synthesized to produce a quantitative estimate of the take
that is reasonably likely to occur and proposed for authorization.
Density estimates come from Northeast Ocean Data (2023) for cetaceans
and from the U.S. Navy Marine Species Density Database (NMSDD; Navy,
2023) for pinnipeds. For the purpose of assessing impacts from
underwater sound, the Navy assumed that all cetacean and pinniped
species spend 100 percent of their time in the water. This approach is
conservative because seals spend a portion of their time hauled-out
and, therefore, are expected to be exposed to less sound than is
estimated by this approach. Cetacean densities were derived from
Northeast Ocean Data to determine Level B harassment takes as cetaceans
do not occur in the Thames River, and Level A harassment exposure for
those species would not occur as Level A harassment noise would be
localized to the river. To determine the number of animals potentially
exposed within the harassment zone, the following equation was used:
Exposure estimate = (N x Harassment Zone) x maximum days of pile
driving
Where:
N = density estimate used for each species
Harassment Zone = the area where noise exceeds the noise threshold
value
The following assumptions were used to calculate potential
exposures to impact and vibratory pile driving noise for each
threshold:
<bullet> Each animal can be ``taken'' via Level B harassment once
every 24 hours.
<bullet> All piles would have an underwater noise disturbance
distance equal to the pile that causes the greatest noise disturbance
(i.e., the pile farthest from shore) installed with the method that has
the largest harassment zone. If vibratory pile driving/extracting would
occur, the largest harassment zone for Level B harassment would be
produced by vibratory driving/extracting. In this case, the harassment
zone for an impact hammer would be encompassed by the larger harassment
zone from the vibratory driver/extractor.
<bullet> Days of construction and demolition were conservatively
based on a relatively slow daily production rate, but actual daily
production rates may be higher, resulting in fewer actual pile driving/
extracting and drilling days. The production days are used solely to
assess the number of days during which pile driving/extracting and
drilling could occur if production were delayed due to equipment
maintenance, safety, etc. In a real construction situation, production
rates would be maximized when possible.
A subset of the species (common dolphin and harbor porpoise) do not
occur within the Thames River and have only been observed in the Long
Island Sound. For these species, the area from the mouth of the Thames
River to the furthest extent of the harassment zone in the Long Island
Sound was used to determine the incidental take estimate within that
zone.
The harassment zone used to calculate takes for cetaceans was from
the notional pile points at Pier 10 or CWTA out to the mouth of the
Thames River which only occurs during concurrent pile driving.
Densities for seals were derived from the NMSDD (Navy, 2017). The NMSDD
uses a combined density for harbor seal and gray seal for which the
densities for each species were 0.049 per sq km in the Thames River and
0.070 per sq km in Long Island Sound, just south of the mouth of the
Thames River. Harp seals are typically very rare in the Thames River
but regularly occur in Long Island Sound. A density of 0.287 per sq km
for harp seals was used for Long Island Sound (Navy, 2017). In order to
guard against unauthorized take of harp seals in the Thames River, it
was assumed that one harp seal may be present during pile installation
activities that occur from January through May (Navy, 2019a).
Common Dolphin
Monthly surveys conducted in the Thames River from 2017 through
2019 did not record presence of common dolphin (Tetra Tech, 2020). As
mentioned for Atlantic white-sided dolphin, an assumed juvenile dolphin
(species was not determined) was observed swimming in the Thames River
(specifically near Norwich Marina) in July 2022. Other surveys,
observations, and reports have been specific to areas adjacent to, but
not including the Thames River (Hayes et al., 2024; Kenney and Vigness-
Raposa, 2010; Jefferson et al., 2009). Dolphins occur occasionally in
Long Island Sound. Historic sightings of pods of dolphins in Long
Island Sound date back to pre-World War II but have become increasingly
rare (Durham, 2009). Common dolphins are more likely to occur from the
mouth of the Thames River south into Long Island Sound. They are most
common in the Gulf of Maine from July to October (Hayes et al., 2024),
and this is the timeframe they are likely to occur in Long Island
Sound.
The average density for common dolphin in Long Island Sound (0.15
per sq km) was used for the sake of being conservative. This density
was used to determine abundance of animals that could be present in the
area for exposure, using the equation abundance = n * harassment zone.
The average group size for common dolphin is 30 (NUWDC, 2024). Only
concurrent pile driving activities would generate a harassment zone
that extends to the mouth of the Thames River into Long Island Sound.
To calculate takes of common dolphin during concurrent pile driving,
the full harassment zone portion from the notional piles out to the
mouth of the Thames River was used.
No take by Level A or Level B harassment of common dolphin was
estimated per calculations for individual pile driving/extracting or
drilling activities. As previously stated, common dolphins are not
expected to be present in the river, particularly within potential
Level A harassment zones which would be a maximum of 10 meters. In
addition, the furthest extent of the Level B harassment zone from pile/
drilling activity ends in the Thames River, approximately 2 miles (3.2
km) north of Long Island Sound and thus, this species is not expected
to be exposed to take by Level B harassment.
During concurrent activities, NMFS concurs with the Navy's
determination that there would be no take by Level A harassment.
However, there is the potential of Level B harassment exposure during
approximately 3 days in December when concurrent activities may occur
and when the Level B harassment zone would extend into the mouth of the
Thames River. Calculated take estimates resulted in up to two takes by
Level B harassment of common dolphin during concurrent activities. It
is anticipated that should a pod of common dolphins be present, there
could be up to 30 takes by Level B harassment. Because this species'
regular occurrence is in much deeper waters of Long Island Sound than
the extent of the harassment zone to the mouth of the Thames River
(Hayes et al., 2024), takes of this species are extremely low. However,
to guard against unauthorized take, take by Level B harassment of
common dolphins is
[[Page 9593]]
requested at the group size of up to 30 individuals (NUWCD, 2024).
Harbor Porpoise
Monthly surveys conducted in the Thames River from 2017 through
2019 did not record presence of harbor porpoise (Tetra Tech, 2020). As
discussed above for dolphins, other surveys, reports, and studies have
been specific to areas adjacent to but not including the Thames River
(Hayes et al., 2024; Kenney and Vigness-Raposa, 2010; Jefferson et al.,
2009), and thus data for potential occurrence of harbor porpoise in the
Thames River is limited. Porpoises occur occasionally in Long Island
Sound. Historic sightings of pods of porpoises in Long Island Sound
date back to pre-World War II but have become increasingly rare
(Durham, 2009). Harbor porpoises are more likely to occur from the
mouth of the Thames River into Long Island Sound. Peak abundance of
harbor porpoise in Long Island Sound is expected to be in December
(Northeast Ocean Data, 2023).
The average density for harbor porpoise in Long Island Sound (0.32
per sq km) was used for the sake of being conservative. This density
was used to determine abundance of animals that could be present in the
area for exposure, using the equation abundance = n * harassment zone.
Only concurrent pile driving activities would generate a harassment
zone that extends to the mouth of the Thames River into Long Island
Sound. To calculate takes of harbor porpoise during concurrent pile
driving, the full harassment zone from the notional piles to the mouth
of the Thames River was used.
No take by Level A or Level B harassment of harbor porpoise was
estimated per calculations for individual pile driving/extracting or
rotary drilling activities. Harbor porpoise are not expected to be
present in the river, particularly within the potential Level A
harassment zone which would be a maximum of 45.2 meters. In addition,
the furthest extent of the Level B harassment zone from pile/drilling
activity ends in the Thames River, approximately 2 miles (3.2 km) north
of Long Island Sound and thus this species is not expected to be
exposed to take by Level B harassment. During concurrent activities,
NMFS concurs with the Navy's determination that there would be no Level
A harassment takes. However, calculated take estimates resulted in up
to five takes by Level B harassment.
Harbor Seal
Harbor seals may be present September to late May in the project
vicinity and in the Thames River in general. A total of 12 individual
sightings of harbor seals were recorded during monthly surveys over a
3-year period (Tetra Tech, 2020). No seals were observed on shore
(Tetra Tech, 2020), and there are no haul-out areas within the Thames
River (Navy, 2018). During marine mammal monitoring for Pier 32
construction activities that occurred from May 2022 through December
2022, only one harbor seal was recorded (Navy, 2023). Harbor seals also
occur within Long Island Sound (Hayes et al., 2022).
Two different densities were used to calculate takes of harbor
seals. A density of 0.049 per sq km was used in the Thames River and a
density of 0.070 per sq km was used in Long Island Sound (Navy, 2017).
These densities were used to determine abundance of animals that could
be present in the area of exposure, using the equation abundance = n *
harassment zone. Based on the Navy's calculations, NMFS concurs with
the determination that there would be no Level A harassment takes of
harbor seal but up to five Level B harassment takes during individual
pile driving/extracting and drilling activities. During concurrent
activities, of which the Long Island Sound density was used, NMFS
concurs with the Navy that there would be no Level A harassment takes
and there would be one Level B harassment take. Takes during concurrent
activities would potentially occur over approximately 3 days in
December.
Gray Seal
Gray seals may be present March through June in the project
vicinity and the Thames River in general, although at lower abundance
than harbor seals (Tetra Tech, 2020). Gray seals also occur within Long
Island Sound (Hayes et al., 2024).
Densities used to calculate takes for gray seal are the same as
described above for harbor seal per the NMSDD (Navy, 2017). These
densities were used to determine abundance of animals that could be
present in the area of exposure, using the equation abundance = n *
harassment zone. It was preliminarily determined that there would be no
Level A harassment takes of gray seal but up to five Level B harassment
takes of gray seal during individual pile driving/extracting and
drilling activities. During concurrent activities, of which the Long
Island Sound density was used, NMFS concurs with the preliminarily
determination that there would be no Level A harassment takes, and
there would be one Level B take. Takes during concurrent activities
would potentially occur over 3 days in December.
Harp Seal
Harp seals may be present in the project vicinity January through
May. In general, harp seals are much rarer than the harbor seal and
gray seal in the Thames River and were not observed during previous
years surveys (Tetra Tech, 2020). However, two harp seals were
identified in March 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 density used for calculating takes of harp seal in the
harassment zone that extends from the mouth of the Thames River south
into Long Island Sound is 0.287 per sq km (Navy, 2017). This density
was used to determine abundance of animals that could be present in the
area for exposure during concurrent activities, using the equation
abundance = n * harassment zone. A density for harp seals in the Thames
River was not available due to their rare occurrence. To guard against
unauthorized take, take estimates include up to one Level B harassment
take per month when this species may be present (January through May)
(Navy, 2019a). This take estimate results in two Level B harassment
takes during individual pile driving/extraction and drilling
activities. For concurrent activities, using the Long Island Sound
density of 0.287 per sq km, up to four Level B harassment takes of harp
seal may occur during 3 days in the month of December.
Table 11--Estimated Takes by Level A and Level B Harassment
----------------------------------------------------------------------------------------------------------------
Proposed
Stock Level A Level B Total take as a
Common name Stock abundance harassment harassment proposed percentage
take of stock
----------------------------------------------------------------------------------------------------------------
Common dolphin................ Western North 93100 0 \2\ 30 30 0.03
Atlantic.
[[Page 9594]]
Harbor porpoise............... Gulf of Maine/Bay 85,765 0 5 5 0.01
of Fundy.
Harbor seal................... Western North 61,336 0 6 6 0.01
Atlantic.
Gray seal..................... Western North 27,911 0 6 6 0.02
Atlantic.
Harp seal \1\................. Western North 7,600,000 0 6 6 0.00
Atlantic.
----------------------------------------------------------------------------------------------------------------
\1\ Harp seal incidental takes are calculated for concurrent activities that would extend to the mouth of the
Thames River at Long Island Sound. For individual activities in the Thames River, harp seals are not usually
present, but the Navy is requesting one Level B harassment take per month of pile activity when this species
may occur (January through May).
\2\ Take increased to average group size for common dolphins for concurrent activities where the sound will
reach the mouth of the Thames River (NMFS, 2023; NUWCD, 2024).
Proposed 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. 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 (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, as
well as subsistence uses. 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.
The mitigation requirements described in the following were
proposed by Navy in its adequate and complete application or are the
result of subsequent coordination between NMFS and Navy. Navy has
agreed that all of the mitigation measures are practicable. NMFS has
fully reviewed the specified activities and the mitigation measures to
determine if the mitigation measures would result in the least
practicable adverse impact on marine mammals and their habitat, as
required by the MMPA, and has determined the proposed measures are
appropriate. NMFS describes these below as proposed mitigation
requirements and has included them in the proposed IHA.
The Navy, as the responsible named party and the Navy of the
proposed IHA, must ensure that construction supervisors and crews, the
monitoring team, and relevant staff are trained prior to the start of
all pile driving and drilling activity, 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.
In addition to the measures described later in the Proposed
Monitoring and Reporting section and all mitigation measures described
in the Navy's Marine Mammal Monitoring Plan, the following mitigation
measures would also apply to the in-water construction activities.
<bullet> Implementation/Coordination--Qualified, trained Protected
Species Observers (PSOs) would implement mitigation measures. PSOs
would be located on-site before, during, and after permitted activities
to monitor marine mammals within (and approaching) mitigation zones.
PSOs would be in constant contact with the construction personnel to
implement appropriate mitigation measures.
Briefings must be conducted between construction supervisors and
crews and the marine mammal monitoring team before the start of all
pile driving/extraction/drilling activities and when new personnel join
the work to explain responsibilities, communication procedures, marine
mammal monitoring protocol, and operational procedures.
<bullet> Establishment of Shutdown Zones--Shutdown zones for all
pile driving and removal activities can be found in table 12. A
shutdown zone generally defines an area where the activity would shut
down upon sighting a marine mammal (or anticipating an animal to enter
the defined area). Shutdown zones would vary based on the activity type
and marine mammal hearing group (table 3). The largest applicable
shutdown zone size would be set for the project area during the
activities if more than one construction method is occurring at that
time. This will determine the appropriate Level A harassment isopleths
and associated shutdown zones.
<bullet> If a marine mammal enters or is observed within an
established shutdown zone, pile driving must be halted or delayed. Pile
driving may not commence or resume until either the animal has
voluntarily left and been visually confirmed beyond the shutdown zone,
or 15 minutes have passed without subsequent detections.
<bullet> Table 12--Proposed Shutdown and Level B Harassment
Monitoring and Shutdown Zones by Activity
[[Page 9595]]
----------------------------------------------------------------------------------------------------------------
Level A (AUD INJ onset)
Pile type, size, and driving method, Level A (AUD INJ onset) monitoring/shutdown Level B (behavioral)
location monitoring/shutdown distance (cetaceans) monitoring distance for
distance (seals) \1\ \1\ \2\ marine mammals
----------------------------------------------------------------------------------------------------------------
Pier 10 Demolition and Quay Wall Repair
----------------------------------------------------------------------------------------------------------------
Vibratory Extract HP14x89 steel 35 meters.............. 25 meters.............. 3,415 meters.
fender H-piles.
Vibratory Extract 24-inch concrete- 30 meters.............. 20 meters.............. 6,310 meters.
encased steel H-piles.
Vibratory Extract 24-inch cast-in- 30 meters.............. 20 meters.............. 6,310 meters.
place reinforced concrete piles.
Impact Install 16-inch polymetric 30 meters.............. 45 meters.............. 22 meters.
fender piles with H-pile extension.
----------------------------------------------------------------------------------------------------------------
CWTA Demolition and Construction
----------------------------------------------------------------------------------------------------------------
Vibratory Extract HP14 steel fender H- 30 meters.............. 20 meters.............. 3,415 meters.
piles.
Rock socket (rotary) drill 30-inch x 10 meters.............. 10 meters.............. 1,848 meters.
100-ft concrete-filled steel pipe
piles.
Rock socket (rotary) drill 16-inch 10 meters.............. 10 meters.............. 1,848 meters.
fiberglass reinforced plastic fender
piles.
----------------------------------------------------------------------------------------------------------------
Concurrent Activities
----------------------------------------------------------------------------------------------------------------
Concurrent Pile Driving (2.5 days) of From Pier 10: 90 meters From Pier 10: 60 meters Maximum harassment
vibratory extraction of HP14x89 From CWTA: 10 meters... From CWTA: 10 meters... zone.\3\
steel H-piles from Pier 10,
Vibratory extraction of HP14 steel
fender H-piles from CWTA, Rock
socket (rotary) drilling of 30-inch
x 100-ft concrete-filled steel pipe
for CWTA construction.
----------------------------------------------------------------------------------------------------------------
\1\ Level A shutdown distance encompasses the maximum Level A harassment distance to avoid injury.
\2\ Although cetaceans are not anticipated to be in the river, because of a rare but recent observation of a
dolphin in 2022, monitoring of the Level A harassment shutdown zones for cetaceans is included to guard
against unauthorized incidental take of dolphins.
\3\ Harassment zone would be a maximum distance of 8,577 meters but would be truncated at intersecting land
masses and would encompass a maximum area of 4.57 sq km.
<bullet> PSOs--the Navy must employ PSOs who would monitor the
project area to the maximum extent possible based on the required
number of PSOs, required monitoring locations, and environmental
conditions. The number, placement, and qualifications of PSOs during
all drilling and pile driving and removal activities (described in
detail in the Proposed Monitoring and Reporting section) would ensure
that the entire shutdown zone is visible during pile installation.
Visual monitoring would be conducted by up to five PSOs depending on
the pile activity.
<bullet> Pre-activity Monitoring--Before starting daily in-water
construction activity, or whenever a break in pile driving/removal of
30 minutes or longer occurs, PSOs would observe the shutdown and
monitoring zones for 30 minutes. The shutdown zone would be considered
cleared when a marine mammal has not been observed within the zone for
those 30 minutes. If a marine mammal is observed within the shutdown
zone, a soft-start cannot proceed until the animal has left the zone or
has not been observed for 15 minutes. When a marine mammal for which
take is authorized is present in the harassment zone, activities may
begin. If work ceases for more than 30 minutes, the pre-activity
monitoring of the shutdown zones would commence.
<bullet> Soft Start--Soft-start procedures are believed to provide
additional protection to marine mammals by warning and/or giving marine
mammals a chance to leave the area before the hammer operates at full
capacity. For impact pile driving, The Navy must provide an initial set
of strikes from the hammer at reduced energy, followed by a 30-second
waiting period. This procedure would be conducted three times before
impact pile driving begins. Soft start would be implemented at the
start of each day's impact pile driving and at any time following
cessation of impact pile driving for 30 minutes or longer.
<bullet> All personnel, including construction supervisors and
crews, PSOs, and relevant staff, must avoid direct physical interaction
with marine mammals during construction activity. If a marine mammal
comes within 10 m of such activity, operations must cease, and vessels
must reduce speed to the minimum level required to maintain steerage
and safe working conditions, as necessary to avoid direct physical
interaction.
<bullet> For those marine mammals for which take has not been
authorized, in-water drilling and pile installation and removal would
shut down immediately if such species are observed within or entering
the Level A or Level B harassment zone.
Protected Species Observers
The placement of PSOs during all pile driving and removal
activities (described in detail in the Proposed Monitoring and
Reporting section; see figure 11-1 in the application) will ensure that
the Thames River and portion of the Long Island Sound is visible during
the relevant specified activities to the maximum extent practicable.
Based on our evaluation of the applicant's proposed measures, NMFS
has preliminarily determined that the proposed 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.
Proposed Monitoring and Reporting
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 would result in increased
knowledge of the species and of the level of taking or impacts on
populations of marine
[[Page 9596]]
mammals that are expected to be present while conducting the
activities. Effective reporting is critical to compliance and ensuring
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:
<bullet> Occurrence of marine mammal species or stocks in the area
in which take is anticipated (e.g., presence, abundance, distribution,
density);
<bullet> Nature, scope, or context of likely marine mammal exposure
to potential stressors/impacts (individual or cumulative, acute or
chronic) through better understanding of the: (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);
<bullet> Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or cumulative impacts from multiple stressors;
<bullet> How anticipated responses to stressors impact either (1)
long-term fitness and survival of individual marine mammals or (2)
populations, species, or stocks;
<bullet> Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or other important physical components of
marine mammal habitat); and,
<bullet> Mitigation and monitoring effectiveness.
The monitoring and reporting requirements described in the
following were proposed by the Navy in its adequate and complete
application and/or are the result of subsequent coordination between
NMFS and Navy. The Navy has agreed to the requirements. NMFS describes
these below as requirements and has included them in the proposed IHA.
Visual Monitoring
Qualified, NMFS-approved PSOs must conduct monitoring in accordance
with project's Marine Mammal Monitoring Plan. PSOs would 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 would have prior experience performing the duties of a PSO
during an activity pursuant to a NMFS-issued ITA. Other PSOs may
substitute other relevant experience, education (degree in biological
science or related field), or training for prior experience performing
the duties of a PSO during construction activity pursuant to a NMFS-
issued ITA. PSOs would be present during all pile installation and
removal activities, including vibratory, impact, and drilling methods,
in accordance with the following:
<bullet> Observer training must be provided before the project
starts and must include instruction on species identification
(sufficient to distinguish the species in the project area),
description and categorization of observed behaviors, and
interpretation of behaviors that may be construed as being reactions to
the specified activity, proper completion of data forms, and other
basic components of biological monitoring, including tracking of
observed animals or groups of animals such that repeat sound exposures
may be attributed to individuals (to the extent possible).
<bullet> All PSOs must have no other project-related tasks while
conducting monitoring.
<bullet> PSOs shall be placed at the best vantage point(s)
practicable to monitor for marine mammals and implement shutdown or
delay procedures when applicable through communication with the
equipment operator.
<bullet> Monitoring would be conducted 30 minutes before, during,
and 30 minutes after drilling and pile driving/removal activities. In
addition, observers shall record all incidents of marine mammal
occurrence, regardless of distance from activity, and must document any
behavioral reactions in concert with the distance from piles being
driven or removed. Drilling and 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.
<bullet> At least five PSOs would be on duty during all vibratory
installation/removal, impact installation/removal, and drilling. PSOs
would be stationed at locations that provide optimal visual coverage
for shutdown and monitoring zones. One PSO would be stationed on land-
based features (such as Pier 10 or CWTA) or a construction barge, and
four PSOs would monitor from two boats for the larger monitoring zones.
PSOs would monitor for marine mammals entering the Level B harassment
zones; the position(s) may vary based on the construction activity and
the location of piles or equipment. To maximize the visual coverage of
shutdown and monitoring zones, observers would use elevated platforms
at observation points to the extent practicable. Observers would
contact each other via two-way radio and a cellular phone used as
backup communication.
<bullet> PSOs would scan the waters using binoculars and/or
spotting scopes and/or the naked eye and a handheld range-finder device
to verify the distance to each sighting from the project site.
Additionally, PSOs should meet the following qualifications:
<bullet> Have the ability to conduct field observations and collect
data according to assigned protocols;
<bullet> Experience or training in the field identification of
marine mammals, including the identification of behaviors;
<bullet> Sufficient training, orientation, or experience with the
construction operation to provide for personal safety during
observations;
<bullet> 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 and times when in-water construction
activities were suspended to avoid potential incidental injury from
construction sound of marine mammals observed within a defined shutdown
zone; and marine mammal behavior; and
<bullet> 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.
Hydroacoustic Monitoring
The Navy proposes to implement in situ acoustic monitoring efforts
to measure SPLs from in-water activities. The Navy would collect and
evaluate sound levels during construction and demolition activities.
Hydroacoustic monitoring would be successfully conducted for at least
10 percent or up to 10 of each different type of pile and each method
of installation. For the pile driving/extraction and rock socket
drilling events acoustically measured, 100 percent of the data would be
analyzed. The Navy would submit a detailed acoustic monitoring plan to
NMFS no later than 60 days in advance of the start of in-water work for
approval of proposed methodologies.
At a minimum, the methodology would include a stationary hydrophone
system with the ability to measure SPLs placed in accordance with NMFS'
most recent recommendations for the collection of source levels.
Monitoring would occur at 33 feet (10 meters) from
[[Page 9597]]
the noise; at a location within the Level A (AUD INJ onset) zones; and
occasionally near the predicted harassment zones for Level B
(Behavioral) harassment. The resulting data set would be analyzed to
examine and confirm SPLs and rates of transmission loss for each
separate in-water construction activity. With NMFS' concurrence, these
metrics would be used to recalculate the limits of the shutdown, Level
A (AUD INJ onset), and Level B (Behavioral) disturbance zones, and to
make corresponding adjustments in marine mammal monitoring of these
zones.
Environmental data would 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 would supply the acoustics specialist with the
substrate composition, hammer or drill model and size, hammer or drill
energy settings and any changes to those settings during the piles
being monitored, depth of the pile being driven or shaft excavated, and
blows per foot for the piles monitored.
For acoustically monitored piles, data from the monitoring
locations would be post-processed to obtain the following sound
measures:
<bullet> Mean, median, minimum, and maximum RMS pressure level in
[dB re 1 [mu]Pa];
<bullet> Mean, median, minimum, and maximum single strike SEL in
[dB re [mu]Pa\2\s];
<bullet> Cumulative SEL as defined by the mean single strike SEL +
10*log10 (number of hammer strikes) in [dB re [mu]Pa\2\s]; and
<bullet> A frequency spectrum (pressure spectral density) in dB re
[mu]Pa\2\ per Hz based on the average of up to eight successive strikes
with similar sound. Spectral resolution would be 1 Hz, and the spectrum
would cover nominal range from 7 Hz to 20 kHz.
Reporting
A draft marine mammal monitoring report would be submitted to NMFS
within 90 days after the completion of drilling and pile driving and
removal activities or 60 days before the requested date of issuance of
any future IHAs for projects at the exact location, whichever comes
first. The report would include an overall description of work
completed, a narrative regarding marine mammal sightings, and
associated PSO data sheets. Specifically, the report must include:
<bullet> Dates and times (beginning and end) of all marine mammal
monitoring;
<bullet> Construction activities occurring during each daily
observation period, including the number and type of holes/piles driven
or removed and by what method (i.e., impact, vibratory, or drilling);
<bullet> PSO locations during marine mammal monitoring; and
<bullet> Environmental conditions during monitoring periods (at the
beginning and end of a 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 is required:
<bullet> The name of the PSO who sighted the animal(s), the PSO's
location, and activity at the time of the sighting;
<bullet> The time of the sighting;
<bullet> Identification of the animal(s) (e.g., genus/species,
lowest possible taxonomic level, or unidentified), the PSO's confidence
in identification, and the composition of the group if there is a mix
of species;
<bullet> The distance and bearing of each marine mammal observed
relative to the specified activity for each sighting (e.g., if pile
driving was occurring at the time of sighting);
<bullet> The estimated number of animals (min/max/best estimate);
<bullet> The estimated number of animals by cohort (adults,
juveniles, neonates, group composition, sex class, etc.);
<bullet> The animal's closest point of approach and estimated time
spent within the harassment zone;
<bullet> A 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);
<bullet> The number of marine mammals detected within the
harassment zones by species (differentiated by month as appropriate);
and
<bullet> Detailed information about any implementation of any
mitigation triggered (e.g., shutdowns and delays), a description of
specific actions that ensued, and the resulting changes in the behavior
of the animal(s), if any.
Finally, The Navy must also submit all PSO datasheets and/or raw
sighting data in an electronic tabular format with the draft report. If
no comments are received from NMFS within 30 days, the draft report
would 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 Injured or Dead Marine Mammals
In the unanticipated event that the specified activity causes the
take of a marine mammal in a manner prohibited by the IHA (if issued),
such as an injury, serious injury, or mortality, The Navy must
immediately cease the specified activities and report the incident to
the NMFS Office of Protected Resources
(<a href="/cdn-cgi/l/email-protection#0555572b4c51552b486a6b6c716a776c6b625760756a777176456b6a64642b626a73"><span class="__cf_email__" data-cfemail="c49496ea8d9094ea89abaaadb0abb6adaaa396a1b4abb6b0b784aaaba5a5eaa3abb2">[email protected]</span></a> and <a href="/cdn-cgi/l/email-protection#9ad3cecab4f2f5eef9f2f1f3f4daf4f5fbfbb4fdf5ec"><span class="__cf_email__" data-cfemail="cb829f9be5a3a4bfa8a3a0a2a58ba5a4aaaae5aca4bd">[email protected]</span></a>) and to
the regional stranding coordinator as soon as feasible. The report must
include the following information:
<bullet> Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
<bullet> Species identification (if known) or description of the
animal(s) involved;
<bullet> Condition of the animal(s) (including carcass condition if
the animal is dead);
<bullet> Observed behaviors of the animal(s), if alive;
<bullet> If available, photographs or video footage of the
animal(s); and
<bullet> General circumstances under which the animal was
discovered.
Activities would not resume until NMFS can review the circumstances
surrounding the prohibited take. NMFS would work with the Navy to
determine what is necessary to minimize the likelihood of further
prohibited take and ensure MMPA compliance. The Navy must not resume
in-water construction activities until NMFS has notified them via
letter, email, or telephone.
If the Navy discovers an injured or dead marine mammal, and the
lead PSO determines that the cause of the injury or death is unknown
and the death is relatively recent (e.g., in less than a moderate state
of decomposition as described in the next paragraph), then the Navy
would immediately report the incident to the NMFS Office of Protected
Resources (<a href="/cdn-cgi/l/email-protection#4f1f1d61061b1f61022021263b203d2621281d2a3f203d3b3c0f21202e2e61282039"><span class="__cf_email__" data-cfemail="18484a36514c4836557776716c776a71767f4a7d68776a6c6b5876777979367f776e">[email protected]</span></a>) and to the regional
stranding coordinator as soon as feasible. The report would include the
same information identified in the paragraph above. Activities would be
able to continue while NMFS reviews the circumstances of the incident.
NMFS would work with Navy to determine whether modifications in the
activities are appropriate.
[[Page 9598]]
Finally, in the event that the Navy discovers an injured or dead
marine mammal and the lead PSO determines that the injury or death is
not associated with or related to the activities authorized in the IHA
(e.g., previously wounded animal, carcass with moderate to advanced
decomposition, or scavenger damage), the Navy would report the incident
to the Chief of the Permits and Conservation Division, Office of
Protected Resources, NMFS, and the NMFS Stranding Hotline and/or by
email to the Regional Stranding Coordinator, within 24 hours of the
discovery. The Navy would provide photographs, video footage (if
available), or other documentation of the stranded animal sighting to
NMFS and the Marine Mammal Stranding Network.
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 11, 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 the
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, removal, and drilling activities associated with the
project, as outlined previously, have the potential to disturb or
displace marine mammals. Specifically, the specified activities may
result in take in the form of Level B harassment from underwater sounds
generated from drilling and pile driving and removal. Potential takes
could occur if individuals of these species are present in zones
ensonified above the thresholds for Level A or Level B harassment
identified above when these activities are underway.
Given the nature of the activity, NMFS does not anticipate serious
injury or mortality due to the proposed project, even in the absence of
required mitigation. The Level A harassment zones identified in table
10 are based upon an animal exposed to vibratory pile driving, impact
pile driving, and drilling for periods ranging from up to a few minutes
to several hours (not exceeding daylight hours). Exposures of this
length are, however, unlikely for pile installation and removal
scenarios, given marine mammal movement throughout the area.
As stated in the Proposed Mitigation section, the Navy would
implement shutdown zones that equal or exceed many of the Level A
harassment isopleths shown in table 10. As noted previously, some
subset of the individuals that are behaviorally harassed could also
simultaneously incur some small degree of TTS for a short duration of
time. Because of the small degree anticipated, any TTS potentially
incurred here is not expected to adversely impact individual fitness,
let alone annual rates of recruitment or survival.
For all species and stocks, take is expected to occur within a
limited, confined area (adjacent to the project site) of the stock's
range. The intensity and duration of take by Level B harassment would
be minimized through the mitigation measures described herein. Further,
the amount of take authorized is small compared to the stock abundance.
Behavioral responses of marine mammals to pile driving, pile
removal, and drilling at the project site, if any, are expected to be
mild, short-term, and temporary. Given that the specified activities
that could result in take would occur over 10 months, any harassment
would be temporary and intermittent. Effects on individuals that are
taken by Level B harassment, based on reports in the literature as well
as monitoring from other similar activities, would likely be limited to
reactions such as increased swimming speeds, increased surfacing time,
or decreased foraging (if such activity were occurring) (e.g., Thorson
and Reyff 2006; Henningson, Durham, and Richardson, Inc. (HDR) 2012;
ABR 2016). Most likely, for pile driving, individuals would move away
from the sound source and be temporarily displaced from the areas of
pile driving. However, this reaction has been observed primarily
associated with impact pile driving. While vibratory driving associated
with the proposed project may produce sound at distances of many
kilometers from the project site, thus overlapping with some likely
less-disturbed habitat, the project site itself is located in a busy
harbor, and the majority of sound fields produced by the specified
activities are close to the harbor. Animals disturbed by project sounds
would be expected to avoid the area and use nearby higher-quality
habitats.
The potential for harassment is minimized by implementing the
proposed mitigation measures. During all impact driving, implementation
of soft start procedures and monitoring of established shutdown zones
shall be required, significantly reducing any possibility of injury.
Given sufficient notice through soft start (for impact driving), marine
mammals are expected to move away from an irritating sound source
before it becomes potentially injurious.
Any effects on marine mammal prey during in-water construction
would have a short-term impact on individual marine mammals' foraging
and likely no effect on the populations of marine mammals. 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 impact on
annual rates of recruitment or survival.
The area likely impacted by the project is relatively small
compared to the available habitat in the surrounding waters, noise
impacts do not overlap any known Biologically Important Areas (BIAs)
for any of the species likely to occur (Van Parijs et al. 2015), and
there is no marine mammal ESA-designated critical habitat in the
project area. In summary and as described above, the following factors
primarily support our preliminary determination that the impacts
resulting from this activity are not expected to adversely affect any
of
[[Page 9599]]
the species or stocks through effects on annual rates of recruitment or
survival:
<bullet> No serious injury or mortality is anticipated or proposed
for authorization;
<bullet> No takes by Level A harassment are anticipated or proposed
for authorization;
<bullet> The anticipated incidents of Level B harassment would
consist of, at worst, temporary modifications in behavior that would
not result in fitness impacts to individuals;
<bullet> The area affected by the specified activity is very small
relative to the overall habitat ranges of all species, does not include
any rookeries, does not include ESA-designated critical habitat, and
does not include any known BIAs for any of the species for which take
is proposed to be authorized;
<bullet> The project area is located in an industrialized and
commercial portion of the river; and
<bullet> The proposed mitigation measures are expected to reduce
the effects of the specified activity to the least practicable adverse
impact level.
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 would have only
minor, short-term effects on individuals. The specified activities are
not expected to affect the reproduction or survival of any individual
marine mammal and, therefore, would not affect the recruitment or
survival rates for any species or stock.
Based on the analysis of the likely effects of the specified
activity on marine mammals and their habitat and considering the
implementation of the proposed monitoring and mitigation measures, NMFS
preliminarily finds that the total number of marine mammals taken from
the proposed activity would have a negligible impact on all affected
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 less than one-third of the species or stock
abundance, the take is considered to be of small numbers. Additionally,
other qualitative factors may be considered in the analysis, such as
the temporal or spatial scale of the activities.
Table 11 demonstrates the number of animals that could be exposed
to the received noise levels that could cause takes by harassment for
the proposed work. Our analysis shows that less than one-third of each
affected stock could be taken by harassment. The number of animals
proposed to be taken for these stocks would be 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 proposed activity
(including the proposed mitigation and monitoring measures) and the
anticipated take of marine mammals, NMFS preliminarily finds that small
numbers of marine mammals would be taken relative to the population
size of the affected species or stocks.
Unmitigable Adverse Impact Analysis and Determination
There are no relevant subsistence uses of the affected marine
mammal stocks or species implicated by this action. Therefore, NMFS has
determined that the total taking of affected species or stocks would
not have an unmitigable adverse impact on the availability of such
species or stocks for taking for subsistence purposes.
Endangered Species Act
Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq.)
requires that each Federal agency ensure that any action it authorizes,
funds, or carries out is not likely to jeopardize the continued
existence of any endangered or threatened species or result in the
destruction or adverse modification of designated critical habitat. To
ensure ESA compliance for issuing IHAs, NMFS consults internally
whenever we propose to authorize take for endangered or threatened
species. No incidental take of ESA-listed species is proposed to be
authorized or expected to result from this activity. Therefore, NMFS
has determined that consultation under section 7 of the ESA is not
required for this action.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
issue an IHA to the applicant for conducting the proposed project
between August 1, 2026, and July 31, 2027, provided the previously
mentioned mitigation, monitoring, and reporting requirements are
incorporated. A draft of the proposed IHA can be found at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>.
Request for Public Comments
We request comments on our analyses, the proposed authorization,
and any other aspect of this notice of proposed IHA for the proposed
project. We also request comments on the potential renewal of this
proposed IHA, as described in the paragraph below. Please include any
supporting data or literature citations with your comments to help
inform decisions on the request for this IHA or a subsequent renewal
IHA. On a case-by-case basis, NMFS may issue a one-time, 1-year renewal
IHA following notice to the public providing an additional 15 days for
public comments when (1) up to another year of identical or nearly
identical activities as described in the Description of Proposed
Activity section of this notice is planned, or (2) the activities as
described in the Description of Proposed Activity section of this
notice would not be completed by the time the IHA expires and renewal
would allow for completion of the activities beyond that described in
the Dates and Duration section of this notice, provided all of the
following conditions are met:
<bullet> A request for renewal is received no later than 60 days
before the needed renewal IHA effective date (recognizing that the
renewal IHA expiration date cannot extend beyond 1 year from the
expiration of the initial IHA).
<bullet> The request for renewal must include the following:
(1) An explanation that the activities to be conducted under the
requested renewal IHA are identical to the activities analyzed under
the initial IHA, are a subset of the activities, or include changes so
minor (e.g., reduction in pile size) that the changes do not affect the
previous analyses, mitigation and monitoring requirements, or take
estimates (with the exception of reducing the type or amount of take).
(2) A preliminary monitoring report showing the results of the
required monitoring to date and an explanation showing that the
monitoring results do not indicate impacts of a scale or nature not
previously analyzed or authorized.
<bullet> Upon review of the request for renewal, the status of the
affected species or stocks, and any other pertinent information, NMFS
determines that there are no more than
[[Page 9600]]
minor changes in the activities, the mitigation and monitoring measures
would remain the same and appropriate, and the findings in the initial
IHA remain valid.
Dated: February 23, 2026.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2026-03861 Filed 2-25-26; 8:45 am]
BILLING CODE 3510-22-P
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</html>Indexed from Federal Register on February 26, 2026.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.