Notice2026-17614
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Year 1 of the Bremerton Waterfront Infrastructure Improvements Project in Puget Sound, Washington
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
August 28, 2026
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has received a request from the United States Navy (Navy) for authorization to take marine mammals incidental to Year 1 of the Bremerton Waterfront Infrastructure Improvements Project in Puget Sound, Washington. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue an incidental harassment authorization (IHA) to take marine mammals incidental to 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.
Full Text
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<title>Federal Register, Volume 91 Issue 166 (Friday, August 28, 2026)</title>
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[Federal Register Volume 91, Number 166 (Friday, August 28, 2026)]
[Notices]
[Pages 55521-55545]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-17614]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XF907]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to Year 1 of the Bremerton Waterfront
Infrastructure Improvements Project in Puget Sound, Washington
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 United States Navy (Navy)
for authorization to take marine mammals incidental to Year 1 of the
Bremerton Waterfront Infrastructure Improvements Project in Puget
Sound, Washington. Pursuant to the Marine Mammal Protection Act (MMPA),
NMFS is requesting comments on its proposal to issue an incidental
harassment authorization (IHA) to take marine mammals incidental to 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.
DATES: Comments and information must be received no later than
September 28, 2026.
[[Page 55522]]
ADDRESSES: Comments should be addressed to Permits and Conservation
Division, Office of Protected Resources (OPR), National Marine
Fisheries Service and should be submitted via email to
<a href="/cdn-cgi/l/email-protection#367f626618505a535b5f5851765859575718515940"><span class="__cf_email__" data-cfemail="175e434739717b727a7e7970577978767639707861">[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: Kate Fleming, OPR, NMFS, (301) 427-
8401.
SUPPLEMENTARY INFORMATION:
Background
The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. Section 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et
seq.) directs 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). If such findings are made, NMFS must prescribe the
permissible methods of taking; other ``means of effecting the least
practicable adverse impact'' on the affected species or stocks and
their habitat, paying particular attention to rookeries, mating
grounds, and areas of similar significance, and on the availability of
the species or stocks for taking for certain subsistence uses (referred
to as ``mitigation''); and requirements pertaining to the monitoring
and reporting of the takings. The definitions of all applicable MMPA
statutory terms used above are included in the relevant sections below
(see also 16 U.S.C. 1362; 50 CFR 216.3, 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.
Summary of Request
On July 8, 2026, NMFS received a request from the Navy for an IHA
to take marine mammals incidental to Year 1 of the Bremerton Waterfront
Infrastructure Improvements Project in Puget Sound, Washington.
Following NMFS' review of the application and subsequent discussions
between NMFS and the Navy, the application was deemed adequate and
complete on July 16, 2026. The Navy's request is for take of seven
species of marine mammals, by Level B harassment and, for California
sea lions (Zalophus californianus) and harbor seals (Phoca vitulina),
Level A harassment. Neither the Navy nor NMFS expect serious injury or
mortality to result from this activity and, therefore, an IHA is
appropriate.
NMFS notes that the Navy provided information relevant to
activities planned for the 2027 to 2028 work window (Year 1) in an
application initially submitted with the intention of requesting
promulgation of incidental take regulations and an associated Letter of
Authorization for the first 5 years of a larger 15-year project. While
the information and analysis associated with the Year 1 activities have
been deemed adequate and complete for the purposes of this IHA, the
Navy is in the process of substantially revising the planned activities
and analysis for 2028 through 2032 (years 2 through 5). NMFS and the
Navy anticipate that construction activities in years 2 through 5 would
be analyzed under a future rule.
NMFS previously issued several incidental take authorizations
(ITAs) to the Navy for similar work (90 FR 17419, April 25, 2025; 89 FR
47539, June 3, 2024; 84 FR 15963, April 17, 2019). The Navy complied
with all the requirements (e.g., mitigation, monitoring, and reporting)
of the previous ITAs, and information regarding their monitoring
results may be found in the Potential Effects of the Specified Activity
on Marine Mammals and their Habitat section.
This proposed IHA would cover 1 year of a larger 15-year project.
The Navy is in the process of revising its application to request
incidental take authorization to cover the next 4 years of the project.
The larger 15-year project involves construction of a new multi-mission
dry dock (M2D2), and years 6 through 15 will be analyzed under future
ITAs.
Description of Proposed Activity
Overview
The Navy has plans to construct a multi-mission dry dock at Puget
Sound Naval Shipyard and Intermediate Maintenance Facility located at
Naval Base (NAVBASE) Kitsap Bremerton over 15 construction seasons.
During Year 1 of this project, the Navy proposes to install barge
mooring anchors to support upcoming construction. Additionally, to
ensure adequate pier capacity to accomplish mission requirements, the
Navy proposes to begin construction of a new pier 2 to replace existing
pier 4.
Dates and Duration
The proposed IHA would be valid for the statutory maximum of 1 year
from the date of effectiveness. It 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. In-water work would occur between July 16, 2027 and
February 15, 2028, which reflects the implementation of a work window
designed to protect fish species listed under the U.S. Endangered
Species Act (ESA).
Construction is planned for approximately 11 days, up to 7 days per
[[Page 55523]]
week, during daylight hours only. However, project delays may occur due
to a number of factors, including project funding, permitting
requirements, availability of equipment and/or materials, weather-
related delays, equipment maintenance and/or repair, and other
contingencies.
Specific Geographic Region
The project is planned in Sinclair Inlet, located on the east side
of the Kitsap Peninsula in Puget Sound, Washington (figure 1).
BILLING CODE 3510-22-P
[GRAPHIC] [TIFF OMITTED] TN28AU26.002
[[Page 55524]]
BILLING CODE 3510-22-C
The inlet is connected to the main Puget Sound basin through Port
Orchard Narrows and Rich Passage. Another relatively narrow waterway,
Port Washington Narrows, connects Sinclair Inlet to Dyes Inlet. Pier 2
construction would be located at NAVBASE Kitsap-Bremerton, which
occupies approximately 3 miles (5 kilometers (km)) along the
northwestern shoreline of Sinclair Inlet. The temporary mooring anchors
would be located in Sinclair Inlet, to the southeast of NAVBASE Kitsap-
Bremerton and south of the mouth of Port Washington Narrows.
NAVBASE Kitsap-Bremerton contains multiple dry docks, piers, and
wharves. In-water structures, shoreline fill, and erosion protection at
NAVBASE Kitsap-Bremerton have resulted in a shoreline geometry and
character that is quite different from undisturbed shorelines in Puget
Sound. Bathymetry near existing piers and in turning basins immediately
offshore has been altered by significant dredging to accommodate
aircraft carriers and other Navy vessels. Water depths range from 40 to
45 feet (ft) (12 to 14 meters (m)), increasing from 45 to 50 ft (14 to
16 m) in dredged berthing areas. West of the project sites, further
into the inlet, depths gradually decrease to less than 30 ft (9 m). For
more details about the geographic setting of this project area, see
section 2.2 (Geographic Region and Physical Settings of Activities) of
the application.
Detailed Description of the Specified Activity
The Navy plans to construct portions of pier 2 and install
temporary barge anchor mooring piles to support future construction. At
pier 2, construction includes vibratory installing 36 36-inch (in) (91-
centimeters (cm)) temporary steel pipe piles, 44 pairs of 24-in (61-cm)
permanent steel sheet piles, and impact installing 14 24-in permanent
concrete piles. Simultaneous pile driving of the same pile types is
planned at this site (table 1). Construction of the temporary barge
anchor mooring piles involves vibratory installation of eight 24-in
temporary steel pipe piles. Only one pile would be installed at a time
at this site. Although some project activities involve the installation
of temporary piles, no pile removal is planned during the Year 1
Bremerton Waterfront Infrastructure Improvements Project.
Construction activities associated with the Year 1 Bremerton
Waterfront Infrastructure Improvements Project that are not expected to
produce noise that would exceed baseline levels at NAVBASE Kitsap-
Bremerton include dredging for adequate draft pier-side berthing
basins, backfilling behind the new sheet pile wall, installation of a
cathodic protection system, and installation of new storm drain
features. Additionally, a Hammerhead Crane would be demolished on a
pier deck (above water level), and construction of a Radio Hill Complex
Expansion and Forge Shop would occur inland at NBK Bangor. These
activities are not expected to have the potential to result in
incidental take of marine mammals. Therefore, only impact and vibratory
pile driving are carried forward for further analysis.
Table 1 provides a summary of pile types, sizes, and numbers of
piles to be installed over the 1-year period from July 16, 2027,
through July 15, 2028.
Table 1--Pile Driving Summary for Year 1 Bremerton Waterfront Infrastructure Improvement Project, Including Pile Types and Driving Durations
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Number of Duration per pile Piles Rigs per Construction
Component Method Size/type piles (minutes or strikes) per rig day days
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M2D2 Temporary Barge Anchor Mooring Vibratory.......... 24-in steel pipe....... 8 50 4 1 2
Piles.
Pier 2 Construction Bulkhead Vibratory.......... 36-in steel pipe....... 36 50 5 2 4
Temporary Piles.
Pier 2 Construction Bulkhead....... Vibratory.......... 24-in steel sheet...... \1\ 88 21 12 2 4
Pier 2 Construction Indicator Piles Impact............. 24-in concrete......... 14 825 8 2 1
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\1\ Note that these 88 sheet piles are driven as pairs. Thus there will be 88 individual sheet piles installed as 44 interlocked pairs.
Proposed mitigation, monitoring, and reporting measures are
described in detail later in this document (Proposed Mitigation and
Proposed Monitoring and Reporting section).
Description of Marine Mammals in the Area of Specified Activities
Sections 3 and 4 of the 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>).
Table 2 lists all species or stocks for which take is likely and
proposed to be authorized for this activity and summarizes information
related to the population or stock, including regulatory status under
the MMPA and 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 mortality and serious injury (M/SI) from anthropogenic
sources are included here as gross indicators of the status of the
species or stocks and other threats.
Marine mammal abundance estimates presented in this document
represent the total number of individuals that make up a given stock or
the total number estimated within a particular study or survey area.
NMFS' stock abundance estimates for most species represent the total
estimate of individuals within the geographic area, if known, that
comprises that stock. For some species, this geographic area may extend
beyond U.S. waters. All managed stocks in this region are assessed in
NMFS' U.S. Alaska and Pacific SARs. All values presented in table 2 are
the most recent available at the time of publication (including from
the 2024 SARs) and are available 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>.
[[Page 55525]]
Table 2--Species, Stocks, and the Status of Marine Mammals \1\ With Estimated Take From the Specified Activities
----------------------------------------------------------------------------------------------------------------
Stock abundance
ESA/ MMPA (CV, Nmin, most Annual
Common name Scientific name Stock status; recent PBR M/SI
strategic abundance \4\
(Y/N) \2\ survey) \3\
----------------------------------------------------------------------------------------------------------------
Order Artiodactyla--Cetacea--Mysticeti (baleen whales)
----------------------------------------------------------------------------------------------------------------
Family Eschrichtiidae:
Gray Whale............... Eschrichtius Eastern North -, -, N 26,960 (0.05, 801 131
robustus. Pacific. 25,849, 2016).
----------------------------------------------------------------------------------------------------------------
Odontoceti (toothed whales, dolphins, and porpoises)
----------------------------------------------------------------------------------------------------------------
Family Phocoenidae
(porpoises):
Dall's Porpoise.......... Phocoenoides CA-OR-WA........ -, -, N 16,498 (0.61, 99 >=0.66
dalli. 10,286, 2018).
Harbor Porpoise.......... Phocoena Washington -, -, N 11,233 (0.37, 66 >=7.2
phocoena. Inland Waters. 8,308, 2015).
----------------------------------------------------------------------------------------------------------------
Order Carnivora--Pinnipedia
----------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals
and sea lions):
California Sea Lion...... Zalophus United States... -, -, N 257,606 (N/A, 14,011 >321
californianus. 233,515, 2014).
Steller Sea Lion......... Eumetopias Eastern......... -, -, N 36,308 (N/A,\5\ 2,178 93.2
jubatus. 36,308, 2022).
Family Phocidae (earless
seals):
Harbor Seal.............. Phoca vitulina.. Washington -, -, N UNK (UNK,\6\ UND 3.4
Inland Southern UNK, 1999).
Puget Sound.
Northern Elephant Seal... Mirounga California -, -, N 194,907 (N/A, 5,328 11.2
angustirostris. Breeding. 88,794, 2023).
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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 stock assessment reports 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>. CV is coefficient of variation; Nmin is the minimum
estimate of stock abundance.
\4\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury
from all sources combined (e.g., commercial fisheries, ship strike). 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\ Nest is best estimate of counts, which have not been corrected for animals at sea during abundance surveys.
Estimates provided are for the United States only.
\6\ Abundance estimates are greater than 8 years old, so stock abundance is considered unknown. Pearson et al.,
(2024) estimates the population abundance of the Washington Inland Southern Puget Sound stock of harbor seal
to be 2,529.
As indicated above, all seven species (with seven managed stocks)
in table 2 temporally and spatially co-occur with the specified
activity to the degree that take is 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 humpback whales (Central
America/Southern Mexico--CA/OR/WA; Mainland Mexico--CA/OR/WA; Hawai'i
stocks), minke whales, and killer whales (southern resident and
transient stocks) have been documented in the area, no take of these
species is proposed for authorization.
Occurrence of these species within the project area is expected to
be rare. In February 2026, the Navy provided the NMFS OPR with marine
mammal observation data collected by The Whale Museum from locations in
the project area (Sinclair Inlet) and nearby (Port Orchard, and Blake
Island) between August 2022 and July 2024. In Sinclair Inlet, a minke
whale was reported on 1 day in May 2024 (outside the project period)
and one to two humpback whales were reported on 2 days in December 2022
and April 2024 (the latter date is also outside the project period).
Southern Resident killer whales have only been observed in Sinclair
inlet twice in the last 30 years (1997 and 2015). The data provided by
the Navy show that transient killer whales more frequently visit
Sinclair Inlet; however, the majority of reports occur outside the in-
water work months (i.e., July through February), with sightings
reported on just 3 days during months when the project activities are
planned (all in October). These species were not documented by PSOs
monitoring for marine mammals during construction projects occurring
within or near Sinclair Inlet (table 3). Given the rarity of these
species in Sinclar Inlet and the short duration of activities proposed
for Year 1, the Navy would avoid take of humpback, minke, and killer
whales by implementing the measures described in the Proposed
Mitigation and Proposed Monitoring and Reporting sections.
Marine mammal monitoring data collected by Protected Species
Observers (PSOs) employed to monitor during construction projects
(table 3), and local research groups contribute to our understanding of
local occurrence of marine mammals near NAVBASE Kitsap-Bremerton and
Sinclair Inlet (tables 4 and 5).
Table 3--Marine Mammal Monitoring During Construction Projects Near NAVBASE Kitstap-Bremerton and Sinclair Inlet, Washington
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Monitoring
Project name Location Monitoring period days Reference
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Navy P454 Multi-Mission Drydock NAVBASE Kitsap- August 22, 2023-November 1, 2023............. 22 Department of Navy (DoN) 2024.
Test Pile Program. Bremerton.
Kitsap Transit Annapolis Southern shoreline December 12, 2019-January 22, 2020........... 8 Hamer Environmental, 2020.
Passenger Ferry Dock Project. of Sinclair Inlet
across from
NAVBASE Kitsap-
Bremerton.
[[Page 55526]]
Washington State Department of Port Washington July 2012-November 2012...................... 52 Rand, 2012.
Transportation Manette Bridge Narrows.
Replacement Project (2012).
Washington State Department of Port Washington August 2010-February 2011.................... 52 Rand, 2011.
Transportation Manette Bridge Narrows.
Replacement Project (2011).
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The Navy has conducted weekly shore-based pinniped surveys at NBK-
Kitsap Bremerton since 2010 (Navy, 2025). Surveys were initially
conducted once per month by boat, which allowed for counts along NBK
Bremerton's Port Security Barrier (PSB) floats. Starting in 2014, the
survey effort was expanded to include shore-based surveys and the
number of surveys each month increased. During the last 6 survey
periods (beginning in 2019-2020), the annual number of surveys
conducted have been less variable than previous survey periods, ranging
from 32 to 48 surveys annually rather than 10 to 52 surveys annually.
As such, summary data from the last 6 survey periods are provided and
used in consideration of take estimates. For each survey period, the
Navy provides the average and maximum count by month. Tables 4 and 5
provide a summary of these metrics.
Table 4--Mean of the Monthly Mean Count for Pinniped Survey Periods Between January 2019 to February 2025
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2019-2020 2021-2022 2022-2023 2023-2024 2024-2025 All years (Jul 2019-Feb
Species (Jul-Feb) (Jul-Feb) (Jul-Feb) (Jul-Feb) (Jul-Feb) 2025, annually)
--------------------------------------------------------------------------------------------------------------------------------------------------------
California Sea Lion...................................... 101 118 101 111 \1\ 100 105
Steller sea lion \2\..................................... ........... ........... ........... ........... 2 2
Harbor seal.............................................. 0.13 0 0.25 0.63 0 0.3
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\1\ The mean count for surveys conducted in February 2025 was not provided for California sea lions.
\2\ Navy first began recording observations of Steller sea lions at Bremerton during their weekly pinniped monitoring surveys in 2024.
Table 5--Mean of the Monthly Maximum Count for Pinniped Survey Periods Between January 2019 to February 2025
--------------------------------------------------------------------------------------------------------------------------------------------------------
2019-2020 2021-2022 2022-2023 2023-2024 2024-2025 All years (Jul 2019-Feb
Species (Jul-Feb) (Jul-Feb) (Jul-Feb) (Jul-Feb) (Jul-Feb) 2025, annually)
--------------------------------------------------------------------------------------------------------------------------------------------------------
California Sea Lion...................................... 120 155 128 145 111 132
Steller sea lion \1\..................................... ........... ........... ........... ........... 4 4
Harbor seal.............................................. 0.25 0 0.63 0.75 0.25 1.6
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\1\ Navy first began recording observations of Steller sea lions at Bremerton during their weekly pinniped monitoring surveys in 2024.
Gray Whale
During migration from Mexico to the Arctic, a subpopulation of the
Eastern North Pacific stock of gray whales, commonly referred to as the
Pacific Coast Feeding Group (PCFG), stops and feeds along the coasts of
Oregon and Washington including the Northern Puget Sound (Calambokidis
et al., 2024). A subgroup of the PCFG that feed in the Puget Sound,
recently termed as ``Sounders'' gray whales occurs in highest
concentrations on the southern ends of Whidbey and Camano Islands in
the North Puget Sound, and is an area that corresponds to a
Biologically Important Area (BIA) for feeding gray whales (Calambokidis
et al., 2024). This is well outside the project area, but gray whales
occasionally occur within the central and south Puget Sound.
No gray whales were observed during any PSO monitoring conducted
during construction projects located near NAVBASE Kitstap-Bremerton and
Sinclair Inlet, Washington (table 3). However, according to marine
mammal observation data collected by The Whale Museum and provided by
the Navy, single gray whales were reported on 5 days between October
2022 and April 2024 in Sinclair Inlet.
Between 2019 and 2023, there was an Unusual Mortality Event (UME)
for gray whales along the West Coast from Mexico through Alaska. While
most of the strandings associated with this UME were documented along
Washington's Pacific coast, 14 gray whale strandings were reported in
inland waters between the months of February and July, 1 of which was
near Bainbridge Island (May 2020), 1 in Sinclair Inlet (March 2021),
and 1 near Seattle (April 2019).
Although no gray whale UMEs are currently active, Cascadia Research
Collective is actively monitoring high numbers of stranded gray whales
along the Washington Coast and in Puget Sound this year (2026). As of
July 24, 2026, 30 stranded gray whales have been reported in these
waters, with malnutrition commonly documented. At least 10 whales also
had blunt force trauma consistent with vessel collision and 1 had
recent evidence of entanglement (Cascadia Research Collective, <a href="https://cascadiaresearch.org/working-list-of-gray-whale-strandings-in-2026/">https://cascadiaresearch.org/working-list-of-gray-whale-strandings-in-2026/</a>,
retrieved July 24, 2026).
Dall's Porpoise
Within the inland waters of Washington and British Columbia, this
species is most abundant in the Strait of Juan de Fuca east to the San
Juan Islands (Nyswander et al., 2005). Dall's porpoises may be most
abundant in Puget Sound during the winter (Nysewander et al., 2005;
Washington Department of Fish and Wildlife
[[Page 55527]]
(WDFW) 2007). While sightings have decreased in more recent decades
(Evenson et al., 2016), Dall's porpoises may occur in all areas of
inland Washington at all times of year, but with different
distributions throughout Puget Sound from winter to summer.
Dall's porpoises were not observed during monitoring efforts
associated with projects occurring in or near Sinclair Inlet (DoN,
2024; Hamer Environmental, 2020; Rand, 2011, 2012).
Harbor Porpoise
Harbor porpoises are known to occur year-round in the inland trans-
boundary waters of Washington and British Columbia, Canada and along
the Oregon/Washington coast (Barlow et al., 1988). There was a
significant decline in harbor porpoise sightings within southern Puget
Sound between the 1940s and 1990s but sightings have increased
seasonally more recently (Carretta et al., 2019). Annual winter aerial
surveys conducted by the WDFW from 1995 to 2015 revealed an increasing
trend in harbor porpoise in Washington inland waters, including the
return of harbor porpoises to Puget Sound. The data suggest that harbor
porpoises were already present in Juan de Fuca, Georgia Straits, and
the San Juan Islands from the mid-1990s to mid-2000s, and then expanded
into Puget Sound and Hood Canal from the mid-2000s to 2015, areas they
had used historically but abandoned (Evenson et al., 2016).
PSOs associated with the Navy's P454 Multi-Mission Drydock Test
Pile Program at NAVBASE Kitsap-Bremerton observed one group of two
harbor porpoises (DoN, 2024). Harbor porpoises were not reported by
PSOs monitoring for marine mammals during other construction projects
conducted in Sinclair Inlet (Hamer Environmental, 2021) and the mouth
of Port Washington Narrows (Rand, 2011, 2012).
California Sea Lion
Only male California sea lions migrate into Pacific Northwest
waters, with females remaining in waters near their breeding rookeries
off the coast of California and Mexico. They use haulout sites along
the outer coast, Strait of Juan de Fuca, and in Puget Sound. Haulout
sites are located on jetties, offshore rocks and islands, log booms,
marina docks and floats, and navigation buoys. This species also may be
frequently seen resting in the water, rafted together in groups in
Puget Sound.
In Washington inland waters, California sea lions are typically
present most of the year though occurrence is low in mid-June through
August, as most California sea lions would be returning to rookeries in
California waters (Navy, 2025). As described below, surveys at the
naval installations indicate that a few individuals remain year-round
(Navy, 2025).
California sea lions have been documented in shore-based and boat-
based surveys at NAVBASE Kitsap-Bremerton since 2010 (Navy, 2025). The
maximum number of California sea lions documented on PSB floats at one
time was 412 individuals (October 2019) (Navy, 2025). Using data from
the most recent 6 survey periods completed during project months (July-
February), the average of the monthly maximum count of California sea
lions hauled out on the PSBs is 132 animals, and the average of the
monthly mean count is 105 animals.
Additionally, California sea lions were consistently observed by
PSOs during construction projects in Sinclair Inlet and the mouth of
Port Washington Narrows: 332 groups of California sea lions with an
average group size of 13 reported during the Navy's P454 Multi-mission
Drydock Test Pile Program (DoN, 2024); 4 groups of 1 individual (for a
total of 4 California sea lions) reported during Kitsap Transit's
Annapolis Passenger Ferry Dock Project (Hamer Environmental, 2020); 256
individuals reported during WSDOT's Manette Bridge Replacement project
in 2012 (Rand, 2012); and 72 individuals reported during WSDOT's
Manette Bridge Replacement Project in 2011 (Rand, 2011).
Steller Sea Lion
Steller sea lions use haulout locations in Puget Sound and may
occur at the same haulouts as California sea lions. The Navy indicates
that between 2010 and 2023, only one Steller sea lion was detected
(September 2022; see section 4.8.3 of the application), though NMFS
notes the Navy first began recording observations of Steller sea lions
at Bremerton during their weekly pinniped monitoring surveys in 2024
(Navy, 2025). Between July 2024 and February 2025, the mean of the
monthly maximum count of Steller sea lions was four and the average of
the monthly mean count was two.
Steller sea lions were rarely observed by PSOs during monitoring
for construction projects conducted within or near the project area: 8
individuals were reported during 52 days of monitoring at the mouth of
Port Washington Narrows between July and November 2012 (Rand, 2012).
Steller sea lions were not observed by PSOs during any other monitoring
conducted during construction projects in Sinclair Inlet (DoN, 2024;
Hamer Environmental, 2020) and the mouth of Port Washington Narrows
(Rand, 2011).
Harbor Seal
Harbor seals are the most common pinniped in the inland marine
waters of Washington year-round (Calambokidis and Baird, 1994a). Harbor
seals haul out on rocks, reefs and beaches, and feed in marine,
estuarine and occasionally fresh waters. Harbor seals in the Puget
Sound region are known to exhibit site fidelity and generally remain
close to their primary haulout location; those that move further from
their primary haulout tend to stay at a new location for several weeks
(Peterson et al., 2012).
No haulout sites have been identified at NAVBASE Kitsap-Bremerton,
but there is a haulout across Sinclair Inlet, approximately 0.7 mile
(1.1 km) away. According to the Navy's pinniped haulout monitoring
program, harbor seals are observed inconsistently and in small numbers
at Bremerton between July and February (Navy, 2025). In its
application, the Navy indicates that harbor seals were primarily
observed swimming in the water near piers and other structures but were
occasionally documented hauled out on floats and rarely seen hauled out
on docked submarines. Most observations of harbor seals were of
individuals, but on some occasions, multiple seals were seen in the
same vicinity during surveys. Between the 2019-2020 survey period and
the 2024-2025 survey period (for a total of 6 survey periods, July
through February only), the mean of the monthly maximum count of harbor
seals was one, while the mean of the monthly mean count during this
time was 0.3 (Navy, 2025). Harbor seal pupping has not been documented
at NAVBASE Kitsap-Bremerton.
In its application (see section 4.11.3), the Navy describes that
dead harbor seals are occasionally located during these surveys or
reported by shipyard personnel, with causes of death, if evident,
including net entanglement, prematurely born pups, gunshot wounds, and
predation wounds. The Navy indicates that in 2022, nine harbor seal
carcasses were recorded at NAVBASE Kitsap-Bremerton. Many of the
carcasses were too decomposed to determine cause of death.
Harbor seals are more consistently observed by PSOs during
construction projects in Sinclair Inlet and the mouth of Port
Washington Narrows: 207 sightings of single harbor seals were reported
during the Navy's P454 Multi-Mission Drydock Test Pile Program, for
[[Page 55528]]
an average of 9 harbor seals per day; 40 individuals (an average of 5
per day) were observed across Sinclair Inlet during Kitsap Transit's
Annapolis Passenger Ferry Dock Project (Hamer Environmental, 2020); 586
harbor seals were observed during WSDOT's Manette Bridge Replacement
project in 2012 (Rand, 2012), and 194 harbor seals were observed in
2011 (Rand, 2011), which resulted an average group sizes of 11 and 4
harbor seals, respectively. However, the Rand (2012) report does not
appear to have accounted for re-sightings and likely overestimates the
number of harbor seals present during monitoring.
Northern Elephant Seal
The occurrence of elephant seals in Puget Sound is unpredictable.
No regular haulouts exist in Puget Sound; individual elephant seals
occasionally haul out for 2 to 4 weeks to molt, usually during the
spring and summer and typically on sandy beaches (Calambokidis and
Baird, 1994). These animals are usually yearlings or subadults and
their haulout locations are unpredictable. A female elephant seal has
been reported hauled out in Mutiny Bay on Whidbey Island, more than 30
km to the north of NAVBASE Kitsap-Bremerton, periodically since 2010.
She was observed alone for her first three visits to the area, but in
March 2015, she was seen with a pup. Since then, she has produced three
more pups between 2018 and 2021 (Orca Network, 2025). Northern elephant
seals generally give birth in January, but this individual has
repeatedly given birth in March. She typically returns to Mutiny Bay in
April and May to molt. Her pups have also repeatedly returned to haul
out on nearby beaches, and one has also had a pup (Orca Network, 2025).
Northern elephant seals are rarely reported near Bainbridge Island,
which is much closer to the project site, at just under 5 km from
NAVBASE Kitsap-Bremerton (Wakayama, 2025).
Northern elephant seals have not been detected at NAVBASE Kitsap-
Bremerton, Sinclair Inlet (DoN, 2024; Hamer Environmental, 2020) or
Port Washington Narrows (Rand, 2011, 2012) during PSO monitoring for
construction projects occurring in these areas nor have they been
reported during the Navy's pinniped monitoring program (Navy, 2025).
Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals
underwater, and exposure to anthropogenic sound can have deleterious
effects. To appropriately assess the potential effects of exposure to
sound, it is necessary to understand the frequency ranges marine
mammals are able to hear. Not all marine mammal species have equal
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al.
(2007, 2019) recommended that marine mammals be divided into hearing
groups based on directly measured (behavioral or auditory evoked
potential techniques) or estimated hearing ranges (behavioral response
data, anatomical modeling, etc.). Generalized hearing ranges were
chosen based on the approximately 65 decibel (dB) threshold from
composite audiograms, previous analyses in NMFS (2018), and/or data
from Southall et al. (2007, 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 6.
Table 6--Marine Mammal Hearing Groups
[NMFS, 2024]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 36 kHz.
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 may not be as broad. Generalized hearing range
chosen based on approximately 65 dB threshold from composite
audiogram, previous analysis in NMFS (2018), and/or data from Southall
et al. (2007, 2019). Additionally, animals are able to detect very
loud sounds above and below that ``generalized'' hearing range.
For more details 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 discusses how components of the specified activity may
impact marine mammals and their habitat. The Estimated Take of Marine
Mammals section 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.
Acoustic effects on marine mammals during the specified activities
could occur from vibratory and impact pile installation. The effects of
underwater noise from the Navy's proposed activities have the potential
to result in Level B harassment of marine mammals in the project area
and, for some species as a result of impact pile driving, Level A
harassment.
The Navy's proposed activities include the installation of
approximately 146 steel or concrete piles with diameters of 24-in
(including sheet piles) and 36-in. There are a variety of types and
degrees of effects on marine mammals and their habitat (including prey)
that could occur as a result of the specified activities. Below we
provide a brief description of the types of sound generated by
specified activities, the general impacts on marine mammals and their
habitat from these types of activities, and a related project-specific
analysis with consideration of the proposed mitigation measures.
[[Page 55529]]
Description of Sound Sources for Specified Activities
Activities associated with the project that have the potential to
incidentally take marine mammals through exposure to sound would
include vibratory and impact pile driving.
Impact hammers typically operate by repeatedly dropping and/or
pushing a heavy piston onto a pile to drive the pile into the
substrate. Sound generated by impact hammers is impulsive,
characterized by rapid rise times and high peak sound pressure 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 substrate, and extract piles
by using vibration to break the sediment friction and allow a crane to
pull the piles out. Vibratory hammers typically produce less sound
(i.e., lower sound pressure levels) 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; California Department of
Transportation (CALTRANS), 2015, 2020). Sounds produced by vibratory
hammers are non-impulsive; compared to sounds produced by impact
hammers, they have a slower rise time, reducing the probability and
severity of injury, and the sound energy is distributed over a greater
amount of time (Nedwell and Edwards, 2002; Carlson et al., 2005).
The likely or possible impacts of the Navy's proposed activities on
marine mammals could involve both non-acoustic and acoustic stressors.
Potential non-acoustic stressors could result from the physical
presence of the equipment and personnel; should any animals occur near
the project site(s) close enough to be harassed due to the presence of
equipment or personnel, we expect they would have already traveled
through the Level B and/or Level A harassment zones for the specified
in-water activities and, thus, would already be considered taken by
acoustic impacts. Therefore, any impacts to marine mammals are expected
to be primarily acoustic in nature.
Potential Effects of Underwater Sound on Marine Mammals
The introduction of anthropogenic noise into the aquatic
environment from pile driving is the primary means by which marine
mammals may be harassed from the Navy's specified activity.
Anthropogenic sounds span a broad range of frequencies and sound levels
and can have a range of highly variable impacts on marine life from
none or minor to potentially severe responses depending on received
levels, duration of exposure, behavioral context, and various other
factors. Broadly, underwater sound from active acoustic sources, such
as those in the Project, can potentially result in one or more of the
following: temporary or permanent hearing impairment, non-auditory
physical or physiological effects, behavioral disturbance, stress, and
masking (Richardson et al., 1995; Gordon et al., 2003; Nowacek et al.,
2007; Southall et al., 2007; G[ouml]tz et al., 2009).
We describe the more severe effects of certain non-auditory
physical or physiological effects only briefly as we do not expect that
use of impact and vibratory pile driving are reasonably likely to
result in such effects (see below for further discussion). Potential
effects from impulsive sound sources can range in severity from effects
such as behavioral disturbance or tactile perception to physical
discomfort, slight injury of the internal organs and the auditory
system, or mortality (Yelverton et al., 1973). Non-auditory
physiological effects or injuries that theoretically might occur in
marine mammals exposed to high level underwater sound or as a secondary
effect of extreme behavioral reactions (e.g., change in dive profile as
a result of an avoidance reaction) caused by exposure to sound include
neurological effects, bubble formation, resonance effects, and other
types of organ or tissue damage (Cox et al., 2006; Southall et al.,
2007; Zimmer and Tyack, 2007; Tal et al., 2015). The project activities
considered here do not involve the use of devices such as explosives or
mid-frequency tactical sonar that are associated with these types of
effects.
The degree of effect of an acoustic exposure on marine mammals is
dependent on several factors, including, but not limited to, sound type
(e.g., impulsive vs. non-impulsive), signal characteristics, the
species, age, and sex class (e.g., adult male vs. mom with calf),
duration of exposure, the distance between the noise source and the
animal, received levels, behavioral state at time of exposure, and
previous history with exposure (Wartzok et al., 2004; Southall et al.,
2007). In general, sudden, high-intensity sounds can cause hearing loss
as can longer exposures to lower-intensity sounds. Moreover, any
temporary or permanent loss of hearing, if it occurs at all, will occur
almost exclusively for noise within an animal's hearing range. We
describe below the specific manifestations of acoustic effects that may
occur based on the activities proposed by the Navy.
Richardson et al. (1995) described zones of increasing intensity of
effect that might be expected to occur in relation to distance from a
source and assuming that the signal is within an animal's hearing
range. First (at the greatest distance) is the area within which the
acoustic signal would be audible (potentially perceived) to the animal
but not strong enough to elicit any overt behavioral or physiological
response. The next zone (closer to the receiving animal) corresponds
with the area where the signal is audible to the animal and of
sufficient intensity to elicit behavioral or physiological
responsiveness. The third is a zone within which, for signals of high
intensity, the received level is sufficient to potentially cause
discomfort or tissue damage to auditory or other systems. Overlaying
these zones to a certain extent is the area within which masking (i.e.,
when a sound interferes with or masks the ability of an animal to
detect a signal of interest that is above the absolute hearing
threshold) may occur; the masking zone may be highly variable in size.
Below, we provide additional details regarding potential impacts on
marine mammals and their habitat from noise in general, starting with
hearing impairment, as well as from the specific activities the Navy
plans to conduct, to the degree it is available.
Hearing Threshold Shifts. NMFS defines a noise-induced threshold
shift (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 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).
[[Page 55530]]
Auditory Injury (AUD INJ). NMFS (2024) defines AUD INJ as damage to
the inner ear that can result in destruction of tissue, such as the
loss of cochlear neuron synapses or auditory neuropathy (Houser, 2021).
AUD INJ may or may not result in a permanent TS (PTS). PTS is
subsequently defined 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 some level of
hearing loss at the relevant frequencies; typically, animals with PTS
or other AUD INJ are not functionally deaf (Au and Hastings, 2008;
Finneran, 2016). Available data from humans and other terrestrial
mammals indicate that a 40-dB TS approximates AUD INJ onset (Ward et
al., 1958, 1959; Ward, 1960; Kryter et al., 1966; Miller, 1974; Ahroon
et al., 1996; Henderson et al., 2008). AUD INJ levels for marine
mammals are estimates, as with the exception of a single study
unintentionally inducing PTS in a harbor seal (Phoca vitulina) (Kastak
et al., 2008), there are no empirical data measuring AUD INJ in marine
mammals largely due to the fact that, for various ethical reasons,
experiments involving anthropogenic noise exposure at levels inducing
AUD INJ are not typically pursued or authorized (NMFS, 2024).
Temporary TS (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), and is not considered an AUD INJ. Based on data
from marine mammal TTS measurements (Southall et al., 2007, 2019), 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 (Finneran et al., 2000, 2002; Schlundt et al., 2000). As
described in Finneran (2015), marine mammal studies have shown the
amount of TTS increases with the 24-hour cumulative sound exposure
level (SEL<INF>24</INF>) in an accelerating fashion: at low exposures
with lower SEL<INF>24</INF>, the amount of TTS is typically small and
the growth curves have shallow slopes. At exposures with higher
SEL<INF>24</INF>, the growth curves become steeper and approach linear
relationships with the sound exposure level (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 more impactful (similar to those discussed in
auditory masking, 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 severe 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) (Finneran, 2015). 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
(Delphinapterus leucas), harbor porpoise, and Yangtze finless porpoise
(Neophocoena asiaeorientalis) (Southall et al., 2019). For pinnipeds in
water, measurements of TTS are limited to harbor seals, northern
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 TS at various post-exposure times.
The amount and onset of TTS depends on the exposure frequency.
Sounds below the region of best sensitivity for a species or hearing
group are less hazardous than those 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
SEL<INF>24</INF> 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, 2024). Additionally, the existing marine mammal TTS data come
from a limited number of individuals within these species.
Relationships between TTS and AUD INJ thresholds have not been
studied in marine mammals, and there are no measured PTS data for
cetaceans, but such relationships are assumed to be similar to those in
humans and other terrestrial mammals. AUD INJ typically occurs at
exposure levels at least several dB above that inducing mild TTS (e.g.,
a 40-dB TS approximates AUD INJ onset
[[Page 55531]]
(Kryter et al., 1966; Miller, 1974), while a 6-dB TS approximates TTS
onset (Southall et al., 2007, 2019). Based on data from terrestrial
mammals, a precautionary assumption is that the AUD INJ 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 AUD INJ 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 AUD INJ as
compared with TTS, it is considerably less likely that AUD INJ could
occur.
Behavioral Effects. Exposure to noise also has the potential to
behaviorally disturb marine mammals to a level that rises to the
definition of harassment under the MMPA. 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); and avoidance of areas where sound sources are located.
In addition, pinnipeds may increase their haulout 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 a ``progressive reduction in
response to stimuli that are perceived as neither aversive nor
beneficial,'' rather than a general moderation in response to human
disturbance (Bejder et al., 2009). The opposite process is
sensitization, when an unpleasant experience leads an animal to
subsequently respond, at a lower level of exposure, often in the form
of avoidance.
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 shown
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 (e.g., Erbe et al., 2019). 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. 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.
Avoidance and displacement. 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;
Blair et al., 2016). 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. Acoustic and movement bio-logging tools also have been used
in some cases to infer responses to anthropogenic noise. For example,
Blair et al. (2015) 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. 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
[[Page 55532]]
determination of whether foraging disruptions incur fitness
consequences would require information on or estimates of the energetic
requirements of the affected individuals and the relationship between
prey availability, foraging effort and success, and the life history
stage of the animal.
Respiration rates vary naturally 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 rates 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
(SEL<INF>ss</INF>): 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). Harbor porpoises, Atlantic white-sided dolphins (Lagenorhynchus
actusus), and minke whales have demonstrated avoidance in response to
vessels during line transect surveys (Palka and Hammond, 2001). In
addition, beluga whales in the St. Lawrence Estuary in Canada have been
reported to increase levels of avoidance with increased boat presence
by way of increased dive durations and swim speeds, decreased surfacing
intervals, and by bunching together into groups (Blane and Jaakson,
1994). 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 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.
During PSO monitoring for the Navy's test pile project at NAVBASE
Kitsap-Bremerton, harbor seals were most commonly observed milling and
slow traveling when the sound source was not in operation. During pile
driving, PSOs noticed slightly more looking around behavior as well as
fast travel, resting (hauled out) and feeding. California sea lions
were most commonly observed slow traveling when no pile driving was
occurring. Observed changes in behavior during pile driving included
porpoising, flushing, leaping, and swimming away from the pile, hauling
out, barking, and fast travel. Two harbor porpoises were observed slow
traveling when no pile driving was occurring.
Physiological 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., Selye,
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).
[[Page 55533]]
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; Ayres et al., 2012; Yang
et al., 2022). 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. In addition, Lemos et al. (2022)
observed a correlation between higher levels of fecal glucocorticoid
metabolite concentrations (indicative of a stress response) and vessel
traffic in gray whales. Yang et al. (2022) studied behavioral and
physiological responses in captive bottlenose dolphins exposed to
playbacks of ``pile-driving-like'' impulsive sounds, finding
significant changes in cortisol and other physiological indicators but
only minor behavioral changes. These and other studies lead to a
reasonable expectation that some marine mammals will experience
physiological stress responses upon exposure to acoustic stressors and
that it is possible that some of these would be classified as
``distress.'' In addition, any animal experiencing TTS would likely
also experience stress responses (NRC, 2005), however distress is an
unlikely result of this project based on observations of marine mammals
during previous, similar construction projects.
Vocalizations and 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 (Balaenoptera physalus) have
also been documented lowering the bandwidth, peak frequency, and center
frequency of their vocalizations under increased levels of background
noise 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, in some cases, animals
may cease sound production during production of aversive signals
(Bowles et al., 1994; Wisniewska et al., 2018).
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, including modifications of the acoustic
properties of the signal or the signaling behavior (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
[[Page 55534]]
studies addressing real-world masking sounds likely to be experienced
by marine mammals in the wild (e.g., Branstetter et al., 2013).
Masking occurs in the frequency band that the 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 vibratory pile driving sound spans a broad frequency
spectrum and is anticipated to be within the audible range of marine
mammals present in the proposed action area. Since noises generated
from the proposed construction activities are mostly concentrated at
low frequencies (< 2 kHz), these activities likely have less effect on
mid-frequency echolocation sounds produced by odontocetes (toothed
whales). However, lower frequency noises are more likely to affect
detection of communication calls and other potentially important
natural sounds such as surf and prey noise. Low-frequency noise may
also affect communication signals when they occur near the frequency
band for noise and thus reduce the communication space of animals
(e.g., Clark et al., 2009) and cause increased stress levels (e.g.,
Holt et al., 2009). Unlike TS, masking, which can occur over large
temporal and spatial scales, can potentially affect the species at
population, community, or even ecosystem levels, in addition to
individual levels. Masking affects both senders and receivers of the
signals, and at higher levels for longer durations, could have long-
term chronic effects on marine mammal species and populations. However,
the noise generated by the Navy's proposed activities will only occur
intermittently, across an estimated 11 days during the authorization
period in a relatively small area focused around the proposed
construction site. Thus, while the Navy's proposed 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 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. Cetaceans are not expected to be exposed to airborne sounds
that would result in harassment as defined under the MMPA. 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 the acoustic criteria. We recognize that pinnipeds in
the water could be exposed to airborne sound that may result in
behavioral harassment when looking with their heads above water. Most
likely, airborne sound would cause behavioral responses similar to
those discussed above in relation to underwater sound. For instance,
anthropogenic sound could cause hauled out pinnipeds to exhibit changes
in their normal behavior, such as reduction in vocalizations, or cause
them to temporarily abandon the area and move further from the source.
However, these animals would likely previously have been `taken'
because of exposure to underwater sound above the behavioral harassment
thresholds, which are generally larger than those associated with
airborne sound. Thus, the behavioral harassment of these animals is
already accounted for in these estimates of potential take. Therefore,
we do not believe that authorization of additional incidental take
resulting from airborne sound for pinnipeds is warranted, and airborne
sound is not discussed further.
Potential Effects on Marine Mammal Habitat
The Navy's proposed activities could have localized, temporary
impacts on marine mammal habitat, including prey, by increasing in-
water SPLs. Increased noise levels may affect acoustic habitat and
adversely affect marine mammal prey in the vicinity of the project
areas (see discussion below). Elevated levels of underwater noise would
ensonify the project areas where both fishes and mammals occur and
could affect foraging success. Additionally, marine mammals may avoid
the area during the proposed construction activities; however, any
displacement due to noise is expected to be temporary and is not
expected to result in long-term effects to the individuals or
populations.
The total area likely impacted by the Navy's activities is
relatively small compared to the available habitat in Puget Sound.
Avoidance by potential prey (i.e., fish) of the immediate area due to
increased noise is 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.
The nearshore and intertidal habitat where the proposed project
would occur is highly industrialized. Most marine mammals do not
generally use the area within the footprint of the project area.
Temporary, intermittent, and short-term habitat alteration may result
from increased noise levels during the proposed construction
activities. Effects on marine mammal habitat would be limited to
temporary pile installation noise, and effects on prey species would be
similarly limited in time and space.
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 of piles when bottom
sediments are disturbed. The installation of piles would disturb bottom
sediments and may cause a temporary increase in suspended sediment in
the project area. 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. Since the currents are so strong in the
area, following the completion of sediment-disturbing activities,
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 Puget Sound.
Potential Effects on Prey. Sound may affect marine mammals through
impacts on the abundance, behavior, or distribution of prey species
(e.g., crustaceans, cephalopods, fishes,
[[Page 55535]]
zooplankton). Marine mammal prey varies by species, season, and
location and, for some, is not well documented. Studies regarding the
effects of noise on known marine mammal prey are described here.
Fishes 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 that 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 fishes (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.,
Pe[ntilde]a et al., 2013; Wardle et al., 2001; Jorgenson and Gyselman,
2009; Cott et al., 2012). More commonly, though, the impacts of noise
on fishes are temporary.
SPLs of sufficient strength have been known to cause injury to
fishes and fish mortality (summarized in Popper et al., 2014). 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. (2012b) showed that a TTS of
4 to 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.,
2012a; Casper et al., 2013, 2017).
Fish populations in the proposed project area that serve as marine
mammal prey could be temporarily affected by noise from pile
installation. 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).
Zooplankton is a food source for several marine mammal species, as
well as a food source for fish that are then preyed upon by marine
mammals. Population effects on zooplankton could have indirect effects
on marine mammals. Data are limited on the effects of underwater sound
on zooplankton species, particularly sound from construction (Erbe et
al., 2019). Popper and Hastings (2009) reviewed information on the
effects of human-generated sound and concluded that no substantive data
are available on whether the sound levels from pile driving, seismic
activity, or any human-made sound would have physiological effects on
invertebrates. Any such effects would be limited to the area very near
(1 to 5 m) the sound source and would result in no population effects
because of the relatively small area affected at any one time and the
reproductive strategy of most zooplankton species (short generation,
high fecundity, and very high natural mortality). No adverse impact on
zooplankton populations is expected to occur from the specified
activity due, in part, to large reproductive capacities and naturally
high levels of predation and mortality of these populations. Any
mortality or impacts that might occur would be negligible.
The greatest potential impact to marine mammal prey during
construction would occur during impact pile driving. However, impact
pile installation of 24-in steel piles is planned on just 1
construction day for a maximum of 11,550 strikes estimated to complete
this activity. The remaining vibratory pile driving is planned to occur
on just 10 construction days. This in-water construction activities
would only occur during daylight hours, allowing fish to forage and
transit the project area in the evening. Impact pile driving and
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. Additionally, the proposed construction activity would
avoid the spawning season of ESA-listed salmon species. 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 lower-quality habitat
since it is already highly developed and experiences a high level of
anthropogenic noise from normal operations and other vessel traffic.
Potential Effects on Foraging Habitat
The Navy's Year 1 Bremerton Waterfront Infrastructure Improvement
Project is not expected to result in any habitat-related effects that
could cause significant or long-term negative consequences for
individual marine mammals or their populations, since installation of
in-water piles would be temporary and intermittent. The total seafloor
area affected by pile installation is a very small area compared to the
vast foraging area available to marine mammals outside this project
area. At best, the areas impacted provide marginal foraging habitat for
marine mammals and fishes. Furthermore, pile driving at the project
locations would not obstruct movements or migration of marine mammals.
The area impacted by the project is relatively small compared to
the available habitat just outside the project area, and there are no
areas of particular importance that would be impacted by this project.
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. As described in the preceding, the
potential for the Navy's construction to affect the availability of
prey to marine mammals or to meaningfully impact the quality of
physical or acoustic habitat is considered to be insignificant.
Therefore, impacts of the project are not likely to have adverse
effects on marine mammal foraging habitat in the proposed project area.
[[Page 55536]]
In summary, given the relatively small areas being affected, as
well as the temporary and mostly transitory nature of the proposed
construction activities, any adverse effects from the Navy's activities
on prey habitat or prey populations are expected to be minor and
temporary. The most likely impact to fishes at the project site would
be temporary avoidance of the area. Any behavioral avoidance by fish of
the disturbed area would still leave significantly large areas of fish
and marine mammal foraging habitat in the nearby vicinity. Thus, we
preliminarily conclude that impacts of the specified activities 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 provides an estimate of the number of incidental takes
proposed for authorization through the IHA, which will inform NMFS'
consideration of ``small numbers,'' the negligible impact
determinations, and impacts on subsistence uses.
Harassment is the only type of take expected to result from these
activities. Except with respect to certain activities not pertinent
here, section 3(18) of the MMPA defines ``harassment'' as any act of
pursuit, torment, or annoyance, which: (i) has the potential to injure
a marine mammal or marine mammal stock in the wild (Level A
harassment); or (ii) has the potential to disturb a marine mammal or
marine mammal stock in the wild by causing disruption of behavioral
patterns, including, but not limited to, migration, breathing, nursing,
breeding, feeding, or sheltering (Level B harassment).
Authorized takes would primarily be by Level B harassment, as use
of the acoustic source/s (i.e., vibratory and impact pile driving) has
the potential to result in disruption of behavioral patterns for
individual marine mammals. There is also some potential for AUD INJ
(Level A harassment) to result, primarily for very high frequency
species, phocids, and otariids, because predicted AUD INJ zones are
larger in comparison to the observability for some species. AUD INJ is
unlikely to occur for mysticetes and high-frequency species. 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 there is
some reasonable potential for marine mammals to be behaviorally
harassed or incur some degree of AUD INJ; (2) the area or volume of
water that will be ensonified above these levels in a day; (3) the
density or occurrence of marine mammals within these ensonified areas;
and, (4) the number of days of activities. We note that while these
factors can contribute to a basic calculation to provide an initial
prediction of potential takes, additional information that can
qualitatively inform take estimates is also sometimes available (e.g.,
previous monitoring results or average group size). Below, we describe
the factors considered here in more detail and present the proposed
take estimates.
Acoustic Criteria
NMFS recommends the use of acoustic criteria that identify the
received level of underwater sound above which exposed marine mammals
would be reasonably expected to be behaviorally harassed (equated to
Level B harassment) or to incur AUD INJ of some degree (equated to
Level A harassment).
Level B Harassment. Though significantly driven by received level,
the onset of behavioral disturbance from anthropogenic noise exposure
is also informed to varying degrees by other factors related to the
source or exposure context (e.g., frequency, predictability, duty
cycle, duration of the exposure, signal-to-noise ratio, distance to the
source), the environment (e.g., bathymetry, other noises in the area,
predators in the area), and the receiving animals (hearing, motivation,
experience, demography, life stage, depth) and can be difficult to
predict (e.g., Southall et al., 2007, 2021; Ellison et al., 2012).
Based on what the available science indicates and the practical need to
use a threshold based on a metric that is both predictable and
measurable for most activities, NMFS typically uses a generalized
acoustic threshold based on received level to estimate the onset of
behavioral harassment. NMFS generally predicts that marine mammals are
likely to be behaviorally harassed in a manner considered to be Level B
harassment when exposed to underwater anthropogenic noise above root-
mean-squared sound pressure levels (RMS SPL) of 120 dB (referenced to 1
micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive impulsive (e.g., impact pile driving) 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 as, in most cases, the likelihood of
TTS occurs at distances from the source less than those at which
behavioral harassment is likely. TTS of a sufficient degree can
manifest as behavioral harassment, as reduced hearing sensitivity and
the potential reduced opportunities to detect important signals
(conspecific communication, predators, prey) may result in changes in
behavior patterns that would not otherwise occur.
The Navy's proposed Year 1 Bremerton Infrastructure Improvements
Project includes the use of continuous (vibratory) and impulsive
(impact pile driving) sources, and therefore the RMS SPL thresholds of
120 and 160 dB re 1 [mu]Pa are applicable.
Level A harassment. NMFS' Updated Technical Guidance for Assessing
the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version
3.0; Updated Technical Guidance, 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 Navy's proposed Year 1 Bremerton Infrastructure Improvements
Project includes the use of impulsive (impact pile driving) and non-
impulsive (vibratory pile driving) sources.
The 2024 Updated Technical Guidance criteria include both updated
thresholds and updated weighting functions for each hearing group. The
thresholds are provided in the table below. The references, analysis,
and methodology used in the development of 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>.
[[Page 55537]]
Table 7--Thresholds Identifying the Onset of AUD INJ
----------------------------------------------------------------------------------------------------------------
AUD INJ onset acoustic thresholds * (received level)
Hearing group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: Lpk,flat: 222 dB; Cell 2: LE,LF,24h: 197 dB.
LE,LF,24h: 183 dB.
High-Frequency (HF) Cetaceans.......... Cell 3: Lpk,flat: 230 dB; Cell 4: LE,HF,24h: 201 dB.
LE,HF,24h: 193 dB.
Very High-Frequency (VHF) Cetaceans.... Cell 5: Lpk,flat: 202 dB; Cell 6: LE,VHF,24h: 181 dB.
LE,VHF,24h: 159 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lpk,flat: 223 dB; Cell 8: LE,PW,24h: 195 dB.
LE,PW,24h: 183 dB.
Otariid Pinnipeds (OW) (Underwater).... Cell 9: Lpk,flat: 230 dB; Cell 10: LE,OW,24h: 199 dB.
LE,OW,24h: 185 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric criteria for impulsive sounds: Use whichever criteria results in the larger isopleth for
calculating AUD INJ onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure
level criteria associated with impulsive sounds, the PK SPL criteria are recommended for consideration for non-
impulsive sources.
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, criteria 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 underwater (i.e., 7 Hz to 165 kHz). The subscript associated with
cumulative sound exposure level criteria 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 criteria 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 criteria will be exceeded.
Ensonified Area
Here, we describe operational and environmental parameters of the
activity that are used in estimating the area ensonified above the
acoustic thresholds, including source levels and transmission loss
coefficient.
The sound field in the project area is the existing background
noise plus additional construction noise from the proposed project.
Marine mammals are expected to be affected via sound generated by the
primary components of the project (i.e., vibratory and impact pile
driving).
Source levels for these activities are based on reviews of
measurements of the same or similar pile types and dimensions of piles
available in literature. Source levels agreed upon by NMFS and the Navy
for each pile size and activity each year are presented in table 8.
The Navy indicated that two hammers may operate simultaneously
during pier 2 construction activities. The Navy assumes that all
concurrent pile driving on a given day would be of the same pile size
and type. Source levels for the combination of piles that the Navy
proposes are also presented in table 8.
The methods for how the source levels for the concurrent vibratory
activities are derived are described here: When two noise sources have
overlapping sound fields, the sources are considered additive and
combined using the rules of dB addition. For addition of two
simultaneous sources, the difference between the two sound source
levels is calculated, and if that difference is between 0 and 1 dB, 3
dB are added to the higher sound source levels; if the difference is
between 2 and 3 dB, 2 dB are added to the highest sound source levels;
if the difference is between 4 and 9 dB, 1 dB is added to the highest
sound source levels; and with differences of 10 or more dB, there is no
addition.
The Navy calculated the maximum estimated likelihood of two impact
hammer strikes completely overlapping in time at approximately 0.25
percent (see section 6.6.3 of the application) and based on this low
likelihood did not adjust RMS levels for calculation of Level B
harassment isopleths during concurrent driving. NMFS concurs with the
Navy's approach.
Table 8--Estimates of Mean Underwater Sound Levels Generated During Vibratory and Impact Pile Installation
[Unattenuated]
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Adjusted sound
levels for
concurrent driving
Method Type Size (in) RMS Peak SELss of two of the same Reference
hammers and piles
types/sizes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory....................... Steel Pipe......... 24 161 N/A N/A N/A................ Navy, 2015.
36 167 N/A N/A 170 RMS............ Navy, 2015.
Steel Sheet........ 24 160 N/A N/A 163 RMS............ Caltrans, 2015.
Impact.......................... Concrete........... 24 174 188 164 No Change.......... Navy, 2015.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: dB peak = peak sound Level; rms = root mean square; SEL = sound exposure level.
\1\ Source levels for concurrent vibratory driving adjusted as described in the text. SELss for impact driving was not adjusted because the total number
of strikes for all all concurrent hammers is input separately. SPL RMS and SPL Peak for impact driving were not adjusted based on the low calculated
likelihood of overlapping strikes.
TL is the decrease in acoustic intensity as an acoustic pressure
wave propagates out from a source. TL parameters vary with frequency,
temperature, sea conditions, current, source and receiver depth, water
depth, water chemistry, and bottom composition and topography. The
general formula for underwater TL is:
TL = B x Log10 (R<INF>1</INF>/R<INF>2</INF>),
Where:
TL = transmission loss in dB
B = transmission loss coefficient
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
Absent site-specific acoustical monitoring with differing measured
TL, a practical spreading value of 15 is used as the TL coefficient in
the above formula. Site-specific TL data for Sinclair Inlet are not
available; therefore, the default coefficient of 15 is used to
determine the distances to the Level A harassment and Level B
harassment thresholds.
The ensonified area associated with Level A harassment is more
technically challenging to predict due to the need
[[Page 55538]]
to account for a duration component. Therefore, NMFS developed an
optional User Spreadsheet tool to accompany the 2024 Updated Technical
Guidance that can be used to relatively simply predict an isopleth
distance for use in conjunction with marine mammal density or
occurrence to help predict potential takes. We note that because of
some of the assumptions included in the methods underlying this
optional tool, we anticipate that the resulting isopleth estimates are
typically going to be overestimates of some degree, which may result in
an overestimate of potential take by Level A harassment. However, this
optional tool offers a practical, alternative way to estimate isopleth
distances when more sophisticated modeling methods are not available or
practical. For stationary sources such as pile driving, the optional
User Spreadsheet tool predicts the distance at which, if a marine
mammal remained at that distance for the duration of the activity, it
would be expected to incur AUD INJ. Inputs used in the optional User
Spreadsheet tool (table 9), and the resulting estimated isopleths
(table 10), are reported below.
To calculate Level A harassment isopleths for two simultaneous
vibratory hammers, the NMFS User Spreadsheet was used with modified
inputs to account for accumulation, weighting, and source overlap in
space and time (table 9).
To calculate Level A harassment isopleths for two impact hammers
operating simultaneously, the NMFS User Spreadsheet calculator was used
with modified inputs to account for the total estimated number of
strikes for all piles in a day. For simultaneous impact pile driving of
two 24-in concrete piles, the total estimated number of strikes per day
was summed to estimate total sound exposure during simultaneous
installation, and the number of piles per day was reduced to one. The
SEL<INF>ss</INF> for two simultaneous impact hammers was not adjusted
because the cumulative SEL depends on the total amount of energy, which
is accounted for using total strikes per day for two identical piles.
Table 9--User Spreadsheet Inputs
--------------------------------------------------------------------------------------------------------------------------------------------------------
Weighting Duration to
factor Piles per drive a Strikes per
Method Pile size and type Spreadsheet tab used adjustment day single pile day
(kHz) (minutes)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1 Vibratory Hammer....................... 24-in Steel pipe........... A.1 Vibratory pile driving. 2.5 4 50 N/A
2 Vibratory Hammers...................... 36-in steel pipe........... A.1 Vibratory pile driving. 2.5 10 50 N/A
2 Vibratory Hammers...................... 24-in steel sheet.......... A.1 Vibratory pile driving. 2.5 24 21 N/A
2 Impact Hammers......................... 24-in Concrete............. E.1 Impact pile driving.... 2 1 N/A 11,550
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table 10--Projected Distances to Level A and Level B Harassment Isopleths (m) by Marine Mammal Hearing Group
----------------------------------------------------------------------------------------------------------------
Level A harassment (m) Level B
Component Hammer Pile size and ----------------------------------- harassment
type LF HF VHF PW OW zone (m)
----------------------------------------------------------------------------------------------------------------
M2D2 Temporary Barge Anchor 1 vibratory 24-in steel 21 8 17 27 9 5,412
Mooring Piles. hammer. pipe.
Pier 2 Construction Bulkhead 2 vibratory 36-in steel 95 37 78 122 41 7,356
Temporary Piles. hammers. pipe.
Pier 2 Construction Bulkhead. 2 vibratory 24-in steel 33 13 27 42 14 21,522
hammers. sheet.
Pier 2 Construction Indicator 2 impact 24-in concrete. 301 38 465 267 100 86
Piles. hammers.
----------------------------------------------------------------------------------------------------------------
Marine Mammal Occurrence
In this section we provide information about the occurrence of
marine mammals, including density or other relevant information which
will inform the take calculations.
Available information regarding marine mammal occurrence in the
vicinity of the project area includes site-specific and nearby survey
information from the Navy, Kitsap Transit, and WSDOT (table 3).
Specifically, data sources consulted included the Navy's ``Summary of
Weekly Marine Mammal Surveys at Navy Northwest Region Installations:
2008-2025'' (Navy, 2025) and PSO monitoring completed across four
projects within or near the project area: the Navy's P454 Multi-Mission
Drydock Test Pile Program; Kitsap Transit's Annapolis Passenger Ferry
Dock Project; WDSOT's Mannette Bridge Replacement Project (years 2011
and 2012). Species-specific data summaries of the above are included in
the Description of Marine Mammals in the Area of Specified Activities
section.
No gray whales, Dall's porpoises or northern elephant seals were
documented during any of the projects listed above. For these species,
NMFS considered: (1) The Orca Network archived sightings (Orca Network,
2026); (2) the whale museum sightings data provided to OPR by the Navy
in February 2026; (3) Cascadia Research Collective gray whale
strandings in 2026 (Cascadia Research Collective, <a href="https://cascadiaresearch.org/working-list-of-gray-whale-strandings-in-2026/">https://cascadiaresearch.org/working-list-of-gray-whale-strandings-in-2026/</a>,
retrieved May 28, 2026); and (4) an observation of Dall's porpoise
documented by PSO's during the WSDOT's Mukilteo Multimodal Project from
the Mukilteo--Clinton Ferry monitoring location (90 FR 31965, July 16,
2025).
Take Estimation
Here we describe how the information provided above is synthesized
to produce a quantitative estimate of the take that is reasonably
likely to occur and proposed for authorization.
Exposure Estimates
For species with rare or infrequent occurrence during the in-water
work window, the likelihood of occurrence was reviewed on the basis of
past records of occurrence (using the data sources listed above and
described in Description of Marine Mammals in the Area of Specified
Activities) and the total number of work days. In most cases, the
occurrence of the species in
[[Page 55539]]
this category (i.e., gray whales, Dall's porpoise, and elephant seals),
would not be anticipated to extend for multiple days. The equation used
to estimate take for species with rare or infrequent occurrence is:
Exposure estimate = Probable abundance during construction x Probable
duration
Where:
Probable abundance = expected group size based on data sources
referenced above
Probable duration = probable duration of the animal(s) presence at
construction sites across the entire in-water pile driving period.
The Navy proposed this approach for large whales, killer whales,
and northern elephant seals. NMFS agrees that this approach is
appropriate for these species and also adds Dall's porpoise due to the
infrequent sightings of this species at the project location.
For less frequently observed small species (i.e., harbor porpoise,
Dall's porpoise, and Steller sea lions), Navy initially proposed to use
density estimates from the Navy's Marine Mammal Species Density
Database (Navy, 2019) to estimate the likelihood of occurrence. The
Navy proposed to use local occurrence information to estimate the
likelihood of occurrence for California sea lions and harbor seals.
However, NMFS finds it more appropriate to use local monitoring data to
estimate the likelihood of occurrence for all of these species (except
Dall's porpoise, see above). As such, for harbor porpoises, Steller sea
lions, California sea lions, and harbor seals, NMFS and the Navy agreed
to predict a daily occurrence based on local monitoring data referenced
above, and estimate take by multiplying the estimated daily occurrence
for each species by the number of in-water construction days, generally
using the following equation;
Take by Level B harassment = marine mammal occurrence x days of pile
driving activities.
The Navy proposes to implement a shutdown of pile driving activity
if any large whale or killer whale is observed within or approaching
any defined harassment zone (Proposed Mitigation section).
Additionally, the Navy plans daily coordination with the Orca Network
to maintain situational awareness of large whales in the vicinity of
the project sites and shut down should they be reported or observed by
PSOs near the project site. Given the plan to shut down and because
large whales and killer whales are generally conspicuous, no takes by
Level B or Level A harassment are anticipated for these species (except
gray whales) and none are proposed for authorization.
In most cases where proposed shutdown zones are greater than or
equal to the calculated Level A harassment zones, take by Level A
harassment is not proposed for authorization. However, there are
scenarios for some pinniped species and installations (i.e., California
sea lions and harbor seals during impact pile driving) where take by
Level A harassment is proposed to be authorized to account for the
possibility that individuals could enter the shutdown zone and stay
long enough to incur AUD INJ before PSOs are able to detect them and
enact a shutdown.
Low Frequency and High Frequency Cetaceans
For humpback whales, gray whales, minke whales, and killer whales,
the Navy plans to shut down operations upon observation of these
species approaching the estimated Level B harassment zone. Although the
Navy requested take by Level B harassment for these species, given the
plan to shut down and because large whales and killer whales are
generally conspicuous, NMFS has preliminarily determined that no takes
by Level B or Level A harassment are expected to occur for humpback
whales, minke whales, and killer whales, and none are proposed for
authorization. However, given the recent reports of stranded gray
whales in Puget Sound, NMFS proposes and the Navy agrees that up to two
gray whales may be taken by Level B harassment during the project
period.
No takes by Level A harassment of any large whale or killer whales
are anticipated and none are proposed for authorization.
Very High Frequency Cetaceans
NMFS and the Navy predict that one group of two Dall's porpoise
could occur within the project area during active pile driving over the
course of the 11-day period for a total of two takes by Level B
harassment.
NMFS and the Navy predict that two harbor porpoises could occur
within the Level B harassment zone each construction week. This results
in four takes by Level B harassment.
Although the estimated Level A harassment zone would be larger than
the proposed shutdown zone for very high frequency cetaceans on 1
construction day (impact pile driving of 24-in concrete piles, see
Proposed Mitigation section), no take by Level A harassment is
estimated for Dall's porpoises or harbor porpoises and none are
proposed for authorization due to the rarity of occurrence of these
species in the project area.
Otariids and Phocids
Steller Sea Lion. NMFS predicts that two Steller sea lions could
occur within the Level B harassment zone each construction day. This
results in 22 takes by Level B harassment. No takes by Level A
harassment of Steller sea lions are anticipated and none are proposed
for authorization.
California Sea Lion. NMFS predicts that 132 California sea lions
could occur within the Level B harassment zone each construction day.
This results in 1,452 takes by Level B harassment.
For all pinnipeds, the Navy plans to shut down at distances
slightly larger than the Level A harassment zones (table 12). However,
given the regular occurrence of California sea lions and the nature of
docks and piers in the project site, the Navy and NMFS agree that it is
possible that several California sea lions could go unobserved and
remain within the calculated Level A harassment zone for a sufficient
period to accumulate enough energy to result in AUD INJ. Based on the
resident nature of this species at this site, the Navy requested that
NMFS authorize 55 takes by Level A harassment. However, given the short
duration of the proposed work for year 1 and the planned mitigation
measures, we find it more appropriate to proposes to authorize 10 takes
by Level A harassment of California sea lions.
Takes by Level B harassment were modified to deduct the proposed
amount of take by Level A harassment estimated (i.e., 1,452 takes by
Level B harassment-10 takes by Level A harassment = 1,442 takes by
Level B harassment). Therefore, for California sea lions, NMFS proposes
to authorize 1,442 takes by Level B harassment and 10 takes by Level A
harassment for a total of 1,452 takes across the 11 days of
construction.
Harbor seal. NMFS predicts that nine harbor seals could occur
within the Level B harassment zone, which encompasses a harbor seal
haulout along the southern shoreline of Sinclair Inlet during all
vibratory activities, each construction day. This results in 99 takes
by Level B harassment.
Given the regular occurrence of harbor seals and the nature of
docks and piers in the project site, the Navy and NMFS agree that it is
possible that several animals could go unobserved and remain within the
calculated Level A harassment zone for a sufficient period to
accumulate enough energy to result in AUD INJ. Based on the resident
nature of this species at this site, the
[[Page 55540]]
Navy requested that NMFS authorize 11 takes by Level A harassment of
harbor seals. However, given the short duration of the proposed work
for year 1 and the planned mitigation measures, we find it more
appropriate to propose to authorize 10 takes by Level A harassment of
harbor seals.
Takes by Level B harassment were modified to deduct the proposed
amount of take by Level A harassment estimated (i.e., 99 takes by Level
B harassment-10 takes by Level A harassment = 89 takes by Level B
harassment). Therefore, for harbor seals, NMFS proposes to authorize 89
takes by Level B harassment and 10 takes by Level A harassment for a
total of 99 takes across the 11 days of construction.
Northern Elephant Seals. Because the occurrence of northern
elephant seals in Puget Sound is unpredictable and generally uncommon,
NMFS estimates that one northern elephant seal could occur within the
project area on 1 day during the 11 days that in-water work is planned.
This results in one take by Level B harassment.
No takes by Level A harassment of northern elephant seals are
anticipated and none are proposed for authorization.
Table 11--Take by Stock and Harassment Type and as a Percentage of Stock Abundance
----------------------------------------------------------------------------------------------------------------
Total Proposed take as
Species Stock Level A Level B harassment a percentage of
harassment harassment proposed stock abundance
----------------------------------------------------------------------------------------------------------------
Gray whale..................... Eastern North 0 2 2 <1
Pacific.
Dall's Porpoise................ CA-WA-OR.......... 0 2 2 <1
Harbor Porpoise................ Washington Inland. 0 4 4 <1
California Sea Lion............ United States..... 10 1,442 1,452 0.6
Steller Sea Lion............... Eastern United 0 22 22 <1
States.
Harbor Seal.................... Washington Inland 10 89 99 4
Southern Puget
Sound.
Northern Elephant Seal......... California 0 1 1 <1
Breeding.
----------------------------------------------------------------------------------------------------------------
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 (latter not applicable for this action). NMFS
regulations require applicants for incidental take authorizations to
include information about the availability and feasibility (economic
and technological) of equipment, methods, and manner of conducting the
activity or other means of effecting the least practicable adverse
impact upon the affected species or stocks, and their habitat (50 CFR
216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to
ensure the least practicable adverse impact on species or stocks and
their habitat, as well as subsistence uses where applicable, NMFS
considers two primary factors:
(1) The manner in which, and the degree to which, the successful
implementation of the measure(s) is expected to reduce impacts to
marine mammals, marine mammal species or stocks, and their habitat.
This considers the nature of the potential adverse impact being
mitigated (likelihood, scope, range). It further considers the
likelihood that the measure will be effective if implemented
(probability of accomplishing the mitigating result if implemented as
planned), the likelihood of effective implementation (probability
implemented as planned); and
(2) The practicability of the measures for applicant
implementation, which may consider such things as cost, and impact on
operations.
The mitigation requirements described in the following were
proposed by the Navy in its adequate and complete application or are
the result of subsequent coordination between NMFS and the Navy. The
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.
Shutdown Zones
For all pile driving activities, the Navy proposes to implement
shutdowns within designated zones. The purpose of a shutdown zone is
generally to define an area within which shutdown of the activity would
occur upon sighting of a marine mammal (or in anticipation of an animal
entering the defined area). Shutdown zones vary based on the activity
type and marine mammal hearing group (table 12).
For large whales and killer whales (LF and HF cetacean hearing
groups, respectively), the Navy proposes to shut down at distances
based on the largest harassment zone for each activity and hearing
group. For both hearing groups, this corresponds to 5.4 km during
vibratory pile driving of 24-in steel, 7.4 km during vibratory pile
driving of 24-in steel sheet piles, 21.5 km during vibratory pile
driving of 36-in steel. (NMFS notes that the Level B harassment zone is
truncated 8.2 km to the east of pier 2 by Bainbridge Island, and 5.2 km
to the west of pier 2, also by land). For large whales and killer
whales, during impact pile driving the largest harassment zone
corresponds to 310 m for low frequency cetaceans and 90 m for high
frequency cetaceans. If a large whale or killer whale is observed
approaching these shutdown zones, the Navy would implement shutdown
measures.
The Navy also plans to take measures to ensure that they are aware
of large whale and killer whale locations so that work is not conducted
when these species are within the vicinity of the project area. Such
measures include contacting and/or reviewing the latest sightings data
from the Orca Network on at least a daily basis (Proposed Monitoring
and Reporting section).
With the Navy's proposed shutdown zones, and efforts to determine
the locations of the nearest marine mammal sightings, all incidental
harassment would be prevented for most large whales and all killer
whales.
For phocids and otariids, the proposed shutdown zones are based on
the estimated Level A harassment isopleths for all activities. The
[[Page 55541]]
shutdown zones are also based on the estimated Level A harassment
isopleths for very high-frequency cetaceans during vibratory pile
driving.
In cases where it would be challenging to detect marine mammals at
the Level A harassment isopleth, (e.g., very high-frequency cetaceans
during impact pile driving), smaller shutdown zones have been proposed
(table 12).
Table 12--Proposed Shutdown Zones
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed shutdown zones (m) Level B
Component Hammer/s Size/type ----------------------------------------- harassment
LF HF VHF PW OW zone
--------------------------------------------------------------------------------------------------------------------------------------------------------
M2D2 Temporary Barge Anchor Buoys....... 1 vibratory hammer......... 24-in steel pipe.......... 5,412 5,412 20 30 10 5,412
Pier 2 Construction Bulkhead Temporary 2 vibratory hammers........ 36-in steel pipe.......... \1\ \1\ 80 130 50 \1\ 21,522
Piles. 21,522 21,522
Pier 2 Construction Bulkhead............ 2 vibratory hammers........ 24-in steel sheet......... \1\ \1\ 30 50 20 \1\ 7,365
7,365 7,365
Pier 2 Construction Indicator Piles..... 2 impact hammers........... 24-in Concrete............ 310 90 350 270 100 86
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Underwater noise would be truncated by Bainbridge Island to the east, approximately 8.2 km from pier 2, and truncated by land to the west at about
5.2 km from pier 2.
PSOs
The number and placement of PSOs during all construction activities
(described in the Proposed Monitoring and Reporting section) would
ensure that the shutdown zones are generally visible, such that PSOs
are reasonably confident of their ability observe species at relevant
distances. The Navy would employ at least four PSOs during all
vibratory pile driving and removal activities and at least three PSOs
during impact pile driving activities.
Pre-Clearance Monitoring Through Post-Activity Monitoring
PSOs would monitor the shutdown zones and beyond to the extent that
PSOs can see. Monitoring beyond the shutdown zones enables observers to
be aware of and communicate the presence of marine mammals in the
project areas outside the shutdown zones and thus prepare for a
potential cessation of activity should the animal enter the shutdown
zone.
Prior to the start of daily in-water construction activity, or
whenever a break in pile driving of 30 minutes or longer occurs, PSOs
would observe the shutdown zones and as much of the harassment zones as
possible for a period of 30 minutes. Pre-start clearance monitoring
must be conducted during periods of visibility sufficient for the lead
PSO to determine that the shutdown zones are clear of marine mammals
for which take is authorized.
Pile driving may commence following 30 minutes of observation when
the determination is made that the shutdown zones are clear of marine
mammals. Monitoring of the shutdown zones and beyond to the extent that
PSOs can see would continue for the duration of pile driving through 30
minutes post completion of pile driving activity. Monitoring beyond the
shutdown zones enables observers to be aware of and communicate the
presence of marine mammals in the project areas outside the shutdown
zones and thus prepare for a potential delay or cessation of activity
should the animal enter the zone.
If a marine mammal is observed entering or within shutdown zones,
pile driving activity must be delayed or halted. If pile driving is
delayed or halted due to the presence of a marine mammal, the activity
may not commence or resume until either the animal has voluntarily
exited and been visually confirmed beyond the shutdown zone, or 15
minutes have passed without re-detection of the animal. If work ceases
for more than 30 minutes, the pre-activity monitoring of the shutdown
zones would commence.
Construction supervisors and crews, PSOs, and relevant Navy staff
must avoid direct physical interaction with marine mammals during all
construction activities. 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.
Finally, construction activities must be halted upon observation of
a species for which incidental take is not authorized or a species for
which incidental take has been authorized but the authorized number of
takes has been met entering or within any harassment zone. If a marine
mammal species for which take is not authorized enters a harassment
zone, all in-water activities will cease until the animal leaves the
zone or has not been observed for at least 15 minutes. Pile driving
will proceed if the unauthorized species is observed leaving the
harassment zone or if 15 minutes have passed since the last
observation.
Soft Start
The use of soft-start procedures is believed to provide additional
protection to marine mammals by providing warning and/or giving marine
mammals a chance to leave the area prior to the hammer operating at
full capacity. For impact pile driving, contractors would be required
to provide an initial set of three strikes from the hammer at reduced
energy, with each strike followed by a 30-s waiting period. This
procedure would be conducted a total of 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 a period of 30 minutes or longer. Soft start is not
required during vibratory pile driving activities.
NMFS conducted an independent evaluation of the proposed measures
and 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
In order to issue an IHA for an activity, section 101(a)(5)(D) of
the MMPA states that NMFS must set forth requirements pertaining to the
monitoring and reporting of such taking. The MMPA implementing
regulations at 50 CFR 216.104(a)(13) indicate that requests for
authorizations must include the suggested means of accomplishing the
necessary monitoring and reporting that will result in increased
knowledge of the species and of the level of taking or impacts on
populations of marine mammals that are expected to be present while
conducting the activities. Effective reporting is critical both to
[[Page 55542]]
compliance as well as ensuring that the most value is obtained from the
required monitoring.
Monitoring and reporting requirements prescribed by NMFS should
contribute to improved understanding of one or more of the following:
<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: (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 the Navy. The Navy has agreed to the requirements. NMFS
describes these below as requirements and has included them in the
proposed IHA.
Visual Monitoring
Visual monitoring would be conducted by trained PSOs positioned at
suitable vantage points to be able to observe the entirety of the
shutdown zones and the surrounding area to the maximum extent possible
based on the required number of PSOs, required monitoring locations,
and environmental conditions.
The Navy intends to employ four PSOs to monitor the shutdown zones
and the surrounding area during vibratory pile driving and three PSOs
to monitor the shutdown zones and the surrounding area during impact
pile driving. At least one PSO would be placed near the pile driving
site during all impact and vibratory pile driving activities. During
vibratory pile driving two of the PSOs would be placed at suitable
vantage points to generally be able to observe the entirety of the
shutdown zones, which includes the full extent of the Level B
harassment zones for large whales and killer whales. Such locations may
include Waterman Point, Illahee State Park, and/or Annapolis Ferry
Dock.
Monitoring would be conducted 30 minutes before, during, and 30
minutes after all in-water construction activities. In addition, PSOs
would record all incidents of marine mammal occurrence, regardless of
distance from activity, and would document any behavioral reactions in
concert with distance from piles being driven or removed. Pile driving
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.
Coordination With Local Marine Mammal Research Network
The Orca Network receives sighting information from citizen
scientists, vessel captains, and researchers throughout the Puget Sound
area. Navy biologists and the lead PSO will have access to the Orca
Network notification texts, and they can call into the notification
system. Prior to pile driving each day, the lead PSO would contact the
Orca Network and monitor social media to review updated sighting
locations of large whales, including ESA-listed southern resident
killer whales and humpback whales. If any large whale or killer whale
species are reported approaching, or within the shutdown zone, pile
driving would be delayed until the whale or whales have moved away.
Reporting
The Navy would submit a draft marine mammal monitoring report
within 90 calendar days after the completion of pile driving
activities, or 60 days prior to a requested date of issuance of any
future IHAs for projects at the same location, whichever comes first.
The report would include an overall description of the construction
work completed, a narrative regarding marine mammal sightings, and
associated PSO data sheets (in a queryable electronic format).
Specifically, the report would include:
<bullet> Dates and times (begin and end) of all marine mammal
monitoring;
<bullet> Construction activities occurring during each daily
observation period, including: (1) number of and type of piles that
were driven and the method (e.g., impact or vibratory); and (2) total
duration of driving time for each pile (vibratory driving) and number
of strikes for each pile (impact driving);
<bullet> PSO locations during marine mammal monitoring;
<bullet> Environmental conditions during monitoring periods (at
beginning and end of PSO shift and whenever conditions change
significantly), including Beaufort sea state and other relevant weather
conditions including cloud cover, fog, sun glare, and overall
visibility to the horizon, and estimated observable distance;
<bullet> Upon observation of a marine mammal, the following
information: (1) name of PSO who sighted the animal(s) and PSO location
and activity at time of sighting; (2) time of sighting; (3)
identification of the animal(s) (e.g., genus/species, lowest possible
taxonomic level, or unidentified), PSO confidence in identification,
and the composition of the group if there is a mix of species; (4)
distance from activities to marine mammals and distance from the marine
mammals to the observation point; (5) estimated number of animals (min/
max/best estimate); (6) estimated number of animals by cohort (adults,
juveniles, neonates, group composition, etc.); (7) animal's closest
point of approach and estimated time spent within the estimated
harassment zone; (8) description of any marine mammal behavioral
observations (e.g., observed behaviors such as feeding or traveling),
including an assessment of behavioral responses thought to have
resulted from the activity (e.g., no response or changes in behavioral
state such as ceasing feeding, changing direction, flushing, or
breaching);
<bullet> Number of marine mammals detected within the estimated
harassment zones, by species; and,
<bullet> Detailed information about implementation of any
mitigation (e.g., shutdowns and delays), a description of specific
actions that ensued, and resulting changes in behavior of the
animal(s), if any.
A final report must be prepared and submitted within 30 calendar
days following receipt of any NMFS comments on the draft report. If no
comments are received from NMFS within 30 calendar days of receipt of
the draft report, the report will be considered final. All PSO data
would be submitted electronically in a format that can be queried such
as a spreadsheet or
[[Page 55543]]
database and would be submitted with the draft marine mammal report.
In the event that personnel involved in the construction activities
discover an injured or dead marine mammal, the USACE must report the
incident to the NMFS OPR (<a href="/cdn-cgi/l/email-protection#3363611d7a67631d7e5c5d5a475c415a5d546156435c414740735d5c52521d545c45"><span class="__cf_email__" data-cfemail="6030324e2934304e2d0f0e09140f12090e073205100f121413200e0f01014e070f16">[email protected]</span></a> and
<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="86eff2f6a8e0eae3ebefe8e1c6e8e9e7e7a8e1e9f0">[email protected]</a>) and the West Coast Regional Stranding Coordinator
as soon as possible. If the death or injury was clearly caused by the
specified activity, the Navy must immediately cease the activities
until NMFS OPR is able to review the circumstances of the incident and
determine what, if any, additional measures are appropriate to ensure
compliance with the terms of the LOA. USACE must not resume their
activities until notified by NMFS. 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 animals(s), if alive;
<bullet> Photographs or video footage of the animal(s), if
available; and
<bullet> The general circumstances under which the animal was
discovered.
Negligible Impact Analysis and Determination
NMFS has defined negligible impact as an impact resulting from the
specified activity that cannot be reasonably expected to, and is not
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough
information on which to base an impact determination. In addition to
considering estimates of the number of marine mammals that might be
``taken'' through harassment, NMFS considers other factors, such as the
likely nature of any impacts or responses (e.g., intensity, duration),
the context of any impacts or responses (e.g., critical reproductive
time or location, foraging impacts affecting energetics), as well as
effects on habitat, and the likely effectiveness of the mitigation. We
also assess the number, intensity, and context of estimated takes by
evaluating this information relative to population status. Consistent
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338,
September 29, 1989), the impacts from other past and ongoing
anthropogenic activities are incorporated into this analysis via their
impacts on the baseline (e.g., as reflected in the regulatory status of
the species, population size and growth rate where known, ongoing
sources of human-caused mortality, or ambient noise levels).
To avoid repetition, the majority of our analysis applies to all
the species listed in table 2, given that many of the anticipated
effects of this project on different marine mammal stocks are expected
to be relatively similar in nature. Where there are meaningful
differences between species or stocks, or groups of species, in
anticipated individual responses to activities, impact of expected take
on the population due to differences in population status, or impacts
on habitat, they are described independently in the analysis below.
Pile driving activities associated with this 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 and, for California sea lions and harbor seals,
Level A harassment, from underwater sounds generated by pile
installation. Potential takes could occur if individuals are present in
the ensonified zone when these activities are underway.
No serious injury or mortality is expected, even in the absence of
required mitigation measures, given the nature of the activities.
Further, for five species of marine mammals (all low-frequency and
very-high-frequency cetaceans, Steller sea lions, and northern elephant
seals), no take by Level A harassment is anticipated, due to the rarity
of the species near the project area, or due to the relatively small
Level A harassment zones. The likelihood of take by Level A harassment
occurring is further reduced by Navy's plans to implement mitigation
measures such as shutdown zones that encompass all of the Level A
harassment zones (low-frequency and high-frequency cetaceans, and
pinnipeds) (Proposed Mitigation section).
Take by Level A harassment is proposed for California sea lions and
harbor seals. Any take by Level A harassment is expected to arise from,
at most, a small degree of AUD INJ (i.e., minor degradation of hearing
capabilities within regions of hearing that align most completely with
the energy produced by impact pile driving such as the low-frequency
region below 2 kHz), not severe hearing impairment or impairment within
the ranges of greatest hearing sensitivity. Animals would need to be
exposed to higher levels and/or longer duration than are expected to
occur here in order to incur any more than a small degree of AUD INJ.
Additionally, the amount of take by Level A harassment of these two
species proposed for authorization is very low; NMFS expects no more
than 10 takes by Level A harassment for California sea lions and 10
takes by Level A harassment for harbor seals. For all hearing groups,
if hearing impairment occurs, it is most likely that the affected
animal would lose only a few dB in its hearing sensitivity. Due to the
small degree anticipated, any AUD INJ potentially incurred would not be
expected to affect the reproductive success or survival of any
individual, much less result in adverse impacts on the species or
stock.
Additionally, some subset of the individuals that are behaviorally
harassed could also simultaneously incur some small degree of TTS for a
short duration of time. However, since the hearing sensitivity of
individuals that incur TTS is expected to recover completely within
minutes to hours, it is unlikely that the brief hearing impairment
would affect the individual's long-term ability to forage and
communicate with conspecifics and would therefore not likely impact
reproduction or survival of any individual marine mammal, let alone
adversely affect rates of recruitment or survival of the species or
stock.
Effects on individuals that are taken by Level B harassment in the
form of behavioral disruption, on the basis of reports in the
literature as well as monitoring from other similar activities, would
likely be limited to reactions such as avoidance, increased swimming
speeds, increased surfacing time, or decreased foraging (if such
activity were occurring) (e.g., Thorson and Reyff, 2006). The Navy has
previously conducted and monitored activities potentially affecting
marine mammals at NAVBASE Kitsap-Bremerton. Reporting from these
activities has described no apparently consequential behavioral
reactions or long-term effects on marine mammal populations (DoN,
2024). Most likely, individuals would simply move away from the sound
source and temporarily avoid the area where pile driving is occurring.
If sound produced by project activities is sufficiently disturbing,
animals are likely to simply avoid the area while the activities are
occurring.
[[Page 55544]]
We expect that any avoidance of the project areas by marine mammals
would be temporary in nature and that any marine mammals that avoid the
project areas during construction would not be permanently displaced.
Short-term avoidance of the project areas and energetic impacts of
interrupted foraging or other important behaviors is unlikely to affect
the reproduction or survival of individual marine mammals, and the
effects of behavioral disturbance on individuals is not likely to
accrue in a manner that would affect the rates of recruitment or
survival of any affected stock.
Some individual marine mammals in the project areas, such as
California sea lions, harbor seals or harbor porpoises, may be present
and be subject to repeated exposure to sound from pile driving
activities on multiple days. Repeated exposures of individuals to
relatively low levels of sound outside of preferred habitat areas are
unlikely to significantly disrupt critical behaviors. Thus, even
repeated Level B harassment of some small subset of a stock is unlikely
to result in any effects on rates of reproduction and survival of the
stock as a whole.
Additionally, pile driving and extraction is expected on only 11
days during the year and thus would not occur on every day, and these
individuals would likely return to normal behavior during gaps in pile
driving activity within each day of construction and in between
workdays. As discussed above, individuals could temporarily relocate
during construction activities to reduce exposure to elevated sound
levels from the project. While vibratory driving associated with some
project components may produce sound at distances of many kms from the
pile driving site, thus intruding on higher-quality habitat, the
project sites themselves and the majority of sound fields produced by
the specified activities are within industrialized areas. Therefore, we
expect that animals displaced by project sound would simply avoid the
area.
The project is also not expected to have significant adverse
effects on affected marine mammals' habitats. The project activities
would not modify existing marine mammal habitat for a significant
amount of time. The activities may cause a low level of turbidity in
the water column and some fish may leave the area of disturbance, thus
temporarily impacting marine mammals' foraging opportunities in a
limited portion of the foraging range; but, because of the short
duration of the activities and the relatively small area of the habitat
that may be affected (there are no habitats of known particular
importance to marine mammals), the impacts to marine mammal habitat are
not expected to cause significant or long-term negative consequences.
As described above, increased sightings and strandings of gray
whales have been reported in Puget Sound. We do not expect authorized
takes to exacerbate or compound upon these increased strandings. As
discussed above, no injury, serious injury or mortality is expected or
proposed, and the impact of Level B harassment takes of these species
will be minimized through the incorporation of mitigation measures. The
strandings do not provide cause for concern regarding population-level
impacts. Despite the strandings, the Eastern North Pacific population
of gray whales remains healthy.
Finally, it is unlikely that minor noise effects in a small,
localized area of habitat would have any effect on the reproduction or
survival of any individuals, much less these stocks' annual rates of
recruitment or survival. In combination, we believe that these factors,
as well as the available body of evidence from other similar
activities, demonstrate that the potential effects of the specified
activities would have only minor, short-term effects on individuals.
The specified activities are not expected to impact rates of
recruitment or survival and would therefore not result in population-
level impacts.
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 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> Any Level A harassment is anticipated to cause only slight
AUD INJ, including PTS of a few decibels within the lower frequencies
associated with impact pile driving of 24-in concrete on 1 construction
day, and not encompassing a species' full hearing range;
<bullet> At worst, the anticipated incidents of Level B harassment
would result in temporary behavior modifications or a small degree of
TTS that would resume to baseline at the cessation of activities or as
animals move away from the source;
<bullet> The project area is industrialized; therefore, individuals
taken are likely habituated to anthropogenic activities and behavioral
reactions are expected to be minor and temporary;
<bullet> The project areas are small relative to the overall
habitat range of each species, and overlap with known habitats of
particular importance is minimal;
<bullet> Effects on marine mammal prey species from the activities
are primarily expected to be short-term, and any associated impacts on
marine mammal feeding are not expected to result in significant or
long-term consequences for individuals, or to accrue to adverse impacts
on their populations;
<bullet> The proposed mitigation measures are expected to minimize
the severity of the effects of the specified activity.
Based on the analysis contained herein of the likely effects of the
specified activity on marine mammals and their habitat, and taking into
consideration the implementation of the proposed monitoring and
mitigation measures, NMFS preliminarily finds that the total marine
mammal take from the proposed activity will have a negligible impact on
all affected marine mammal species or stocks.
Small Numbers
As noted previously, only take of small numbers of marine mammals
may be authorized under section 101(a)(5)(A) and (D) of the MMPA for
specified activities other than military readiness activities. The MMPA
does not define small numbers and so, in practice, where estimated
numbers are available, NMFS compares the number of individuals taken to
the most appropriate estimation of abundance of the relevant species or
stock in our determination of whether an authorization is limited to
small numbers of marine mammals. When the predicted number of
individuals to be taken is fewer than one-third of the species or stock
abundance, the take is considered to be of small numbers (86 FR 5322,
January 19, 2021). Additionally, other qualitative factors may be
considered in the analysis, such as the temporal or spatial scale of
the activities.
We propose to authorize incidental take of seven marine mammal
stocks (table 2). The total amount of taking proposed for authorization
is less than 4 percent of each of these stocks. Though the most recent
SAR includes an unreliable population estimate for the Washington
Inland Southern Puget Sound stock of harbor seal because it is more
than 8 years old, Pearson et al., 2024, reports that the peak
population estimate for this stock is 2,832. As such, the 89 proposed
takes by Level B harassment, and 10 proposed takes by Level A
harassment, compared to the abundance estimate, suggests that about
[[Page 55545]]
4 percent of the stock would be expected to be impacted.
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 ensures that any action it
authorizes, funds, or carries out is not likely to jeopardize the
continued existence of any endangered or threatened species or result
in the destruction or adverse modification of designated critical
habitat. To ensure ESA compliance for the issuance of incidental take
authorizations, NMFS consults internally whenever we propose to
authorize take for ESA-listed species.
No incidental take of ESA-listed species is proposed for
authorization or expected to result from this activity. Therefore, NMFS
has determined that formal consultation under section 7 of the ESA is
not required for this action.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
issue an IHA to the Navy for conducting Year 1 of the Bremerton
Waterfront Infrastructure Improvement project in Puget Sound,
Washington, 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 comment on our analyses, the proposed authorization, and
any other aspect of this notice of proposed IHA for the proposed
construction project. We also request comment on the potential renewal
of this proposed IHA as described in the paragraph below. Please
include with your comments any supporting data or literature citations
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 a 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
prior to the needed renewal IHA effective date (recognizing that the
renewal IHA expiration date cannot extend beyond 1 year from 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 minor changes in the activities,
the mitigation and monitoring measures will remain the same and
appropriate, and the findings in the initial IHA remain valid.
Dated: August 25, 2026.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2026-17614 Filed 8-27-26; 8:45 am]
BILLING CODE 3510-22-P
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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.