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Notice2026-06484

Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Port of San Francisco Mission Bay Ferry Landing Project in San Francisco Bay, California

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Published

April 3, 2026

Issuing agencies

Commerce DepartmentNational Oceanic and Atmospheric Administration

Abstract

NMFS has received a request from the Port of San Francisco (PSF) for authorization to take marine mammals incidental to the Mission Bay Ferry Landing (MBFL) Project in San Francisco Bay (SFB), California (CA). Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue an incidental harassment authorization (IHA) to incidentally take marine mammals during the specified activities. NMFS is also requesting comments on possible one-time, 1-year renewals for each IHA that could be issued under certain circumstances and if all requirements are met, as described in the Request for Public Comments section at the end of this notice. NMFS will consider public comments prior to making any final decision on the issuance of the requested MMPA authorization and agency responses will be summarized in the final notice of our decision.

Full Text

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[Federal Register Volume 91, Number 64 (Friday, April 3, 2026)]
[Notices]
[Pages 16900-16923]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-06484]

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XF443]

Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to the Port of San Francisco Mission
Bay Ferry Landing Project in San Francisco Bay, California

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 Port of San Francisco
(PSF) for authorization to take marine mammals incidental to the
Mission Bay Ferry Landing (MBFL) Project in San Francisco Bay (SFB),
California (CA). Pursuant to the Marine Mammal Protection Act (MMPA),
NMFS is requesting comments on its proposal to issue an incidental
harassment authorization (IHA) to incidentally take marine mammals
during the specified activities. NMFS is also requesting comments on
possible one-time, 1-year renewals for each IHA that could be issued
under certain circumstances and if all requirements are met, as
described in the Request for Public Comments section at the end of this
notice. NMFS will consider public comments prior to making any final
decision on the issuance of the requested MMPA authorization and agency
responses will be summarized in the final notice of our decision.

DATES: Comments and information must be received no later than May 4,
2026.

ADDRESSES: Comments should be addressed to the Permits and Conservation
Division, Office of Protected Resources, National Marine Fisheries
Service and should be submitted via email to <a href="/cdn-cgi/l/email-protection#eda4b9bdc3889e8e85ad83828c8cc38a829b"><span class="__cf_email__" data-cfemail="f2bba6a2dc9781919ab29c9d9393dc959d84">[email&#160;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: Carter Esch, Office of Protected
Resources, 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). Further, 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 C.F.R 216.3, and 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.
These actions are 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 October 10, 2025, NMFS received a request from PSF for an IHA to
take marine mammals incidental to vibratory pile driving and
extraction, and down-the-hole (DTH) driving, necessary for construction
of the MBFL Project within PSF's Southern Waterfront in the Mission
Bay/Central Waterfront area.
NMFS previously issued an IHA to PSF to harass small numbers of
marine mammals, by Level B harassment, incidental to similar
activities, effective June 1, 2019, to May 31, 2020 (83 FR 53217,
October 22, 2018). Following issuance of the original IHA, Project
construction was significantly delayed due to the City of San
Francisco's project resources and funding constraints. PSF then divided
the Project construction sequencing into two phases. MBFL Phase 1
project elements, completed from June to November 2020, included only
project activities incidental to which take of marine mammals was not
anticipated (i.e., demolition, dredging, and sand capping). Following a
five-year construction delay, PSF is preparing to initiate construction
of the remaining MBFL Phase 2 elements (i.e., pile installation and
extraction using vibratory methods and DTH driving). Since issuance of
the 2018 IHA, PSF has

[[Page 16901]]

streamlined the project description to include a ferry landing only,
rather than both ferry and water taxi landings. Therefore, the
specified activities described in the 2025 IHA request include only a
subset of those analyzed for the 2018 IHA, with minor changes to pile
sizes and installation parameters.
Following NMFS' review of the application drafts and associated
discussions, PSF iteratively submitted revised versions of the
application on January 8, February 6, and February 23, 2026. The
application was deemed adequate and complete on March 5, 2026.
PSF now proposes to construct a single-float, two-berth MBFL to
provide ferry access to the SFB area. PSF is requesting an IHA to cover
the period of June 1, 2026, to May 31, 2027. PSF's proposed activity
includes vibratory pile driving, vibratory pile extraction, and DTH
driving, which may result in the incidental take of marine mammals, by
harassment only. PSF's request is for incidental take, by Level B
harassment, of eight species of marine mammals. No Level A harassment
is anticipated to occur, and none is proposed for authorization.
Neither PSF nor NMFS expect serious injury or mortality to result from
this activity and, therefore, an IHA is appropriate.

Description of Proposed Activity

Overview

PSF proposes to construct the MBFL, a single[hyphen]float,
two[hyphen]berth ferry landing, in SFB, CA, within PSF's Southern
Waterfront in the Mission Bay/Central Waterfront area. The MBFL will
provide critical regional ferry service to and from the Mission Bay
neighborhood, one of the fastest growing neighborhoods in San
Francisco, as well as the Dogpatch, Potrero Hill, Pier 70, and the
Central Waterfront neighborhoods. The MBFL will provide capability to
berth two ferry boats simultaneously and it is estimated that the ferry
landing will have the capacity to handle up to 6,000 passengers per
day. The ferry landing is considered essential to alleviate current
regional transportation overcrowding and provide transportation
resiliency in the event of an earthquake, Bay Bridge failure, or other
unplanned events. The ferry landing in-water construction activities
that have the potential to take marine mammals include vibratory pile
driving and extraction, and DTH driving. In total, PSF anticipates
conducting 32 non-consecutive days of in-water construction with the
potential to result in take of eight species of marine mammals, over a
46-day period between June 1 and November 30, 2026.

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. Although the IHA would be active for a period of 1
year, in-water pile installation and extraction activities are planned
from June through November to protect sensitive life stages of
endangered fish in the area. PSF plans to conduct in-water construction
activities over the course of 46 days from June 1, 2026, through
November 30, 2026, although only 32 of those days would include
construction activities that may result in incidental harassment of
marine mammals. This schedule is subject to change, however, as project
delays may occur due to a number of factors (e.g., poor weather,
equipment availability constraints).
Pile installations would proceed sequentially (i.e., no concurrent
activities planned). PSF estimates an overall production rate of two to
six piles per day, although this number would vary depending on the
stage of construction. PSF anticipates that all vibratory pile driving
and extraction and DTH driving would be limited to daylight hours.

Specified Geographical Region

The project is located in SFB within PSF's Southern Waterfront in
the Mission Bay/Central Waterfront area. The specific geographic
location for the project is provided in figure 1. The project site is
approximately three kilometers (km) south of the San Francisco-Oakland
Bay Bridge, on the western side of SFB in the Central Basin. The nearby
waterfront is an active recreational and commercial port and shipyard.
The Long Wharf is located in northern region of the central Bay, south
of the eastern terminus of the Richmond-San Rafael Bridge (Figure 1).
Water depth in the project area ranges from approximately 6 to 15
meters (m). The substrate is primarily Bay mud, however, sand or gravel
may exist deeper into the substrate. The project area around Berth 1 is
approximately 470 square kilometers (km\2\) in size. Ambient underwater
noise in the vicinity of the project area is generated by shipping
activity, ferry traffic, and sound generated by the Richmond Bridge
piers. Underwater noise measurements in 2006 and from 2020 to 2022
found the ambient noise in the project area to exceed 120 decibels (dB)
root-mean-squared (RMS). Ambient underwater noise levels at Long Wharf
may vary with noise levels being higher at Berth 1, likely due to its
closer proximity to the main shipping channel.

[[Page 16902]]

[GRAPHIC] [TIFF OMITTED] TN03AP26.000

Figure 1--MBFL Project Location in SFB, CA

Detailed Description of Specific Activity

PSF proposes to construct the MBFL, a single[hyphen]float,
two[hyphen]berth ferry landing in Mission Bay, located in SFB, CA,
within PSF's Southern Waterfront in the Mission Bay/Central Waterfront
area. Table 1 provides a summary of in-water construction activities,
including installation of octagonal concrete piles which would not
require pile driving or DTH driving. PSF defines four components of the
overall ferry landing structure:
Pier Bents 1 and 2--includes vibratory pile driving installation of
four permanent 48-in steel caisson sleeves, drilling inside each
caisson sleeve to create space to accommodate the base of one 24-in
octagonal concrete pile per caisson sleeve, crane-mediated placement of
four concrete piles (one per sleeve), and grouting to secure the base
of each concrete pile;
Pier Bents 3 to 7--includes vibratory pile driving installation of
10 temporary 30-in steel caisson sleeves, drilling inside each caisson
sleeve to create space to accommodate the base of a 24-in octagonal
concrete pile per caisson sleeve, crane-mediated placement of ten
concrete piles, grouting to secure the base of each concrete pile, and
vibratory pile extraction of each 30-in steel caisson sleeve;
Float Guide Piles--includes vibratory pile driving installation of
six 36-in steel pipe piles to refusal, followed by DTH to the 20-ft
(6.1-m) embedment depth; and
Donut Fender Piles--includes vibratory pile driving installation of
two 36-in steel pipe piles to refusal, followed by DTH to the 20-ft
(6.1-m) embedment depth.
To ensure the piles are correctly positioned during construction of
the ferry landing, the contractor may elect to utilize a temporary
pile-driving template. PSF estimates that the template may be installed
and moved up to 10 times during construction. Four 14-in steel H-piles
would support the template. Each of the four H-piles would be driven to
refusal with a vibratory pile driver (600 seconds/pile) every time the
template is set up and extracted using the same vibratory piling
methodology to release the template for subsequent use, for a combined
total of 80 H-pile installations and extractions (installation and
extraction of 4 H-piles x 10 template applications).

Table 1--Summary of PSF's Pile Installation Activities for the MBFL Project
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pile Duration and
Project element Pile type diameter Method strikes/second Pile events per Days Total pile events
(inches) (sec) day
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pile driving template piles..... H-Pile Steel 14 Vibratory pile 600................ 8 (4 installed and 10 80 (40 installed
(temporary). driving and 4 removed). and 40 removed).
extraction.
Pier (Bents 1 & 2).............. Steel Caisson 48 Vibratory pile 900................ 1................. 4 4.
(permanent). driving.
Octagonal Concrete. 24 No pile driving or N/A................ 1................. 4 4.
DTH.
Pier (Bents 3 -7)............... Steel Caisson 30 Vibratory pile 900................ 2 (1 installed and 10 20 (10 installed
(temporary). driving and 1 removed). and 10 removed).
extraction.
Octagonal Concrete. 24 No pile driving or N/A................ 1................. 10 10.
DTH.
Float Guide Piles............... Steel Pipe 36 Vibratory pile 1,200.............. 1................. 6 6.
(permanent). installation.

[[Page 16903]]

Donut Fender Piles.............. DTH driving........ 20 minutes (10/sec) 1................. 2 2.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Activities in italics are not likely to incidentally harass marine mammals.

To aid in constructing Pier Bents, PSF would first install the
template (using the approach described above) to support vibratory pile
driving installation of each of four permanent 48-in (Bents 1 and 2)
and 10 temporary 30-in (Bents 3 to 7) steel caisson sleeves. Once a
given caisson sleeve is in place, sediment/soil/rock within the caisson
would be drilled out using a Bauer BG18 rotary drill (similar) to
create a rock socket (i.e., a void in the substrate in which to seat
the base of the pile). All drilled sediment/soil/rock will be collected
for disposal and transported to an appropriate permitted facility.
However, rotary drilling is not likely to result in incidental take of
marine mammals, and we do not discuss it further. Using a crane, PSF
would place/seat a 24[hyphen]in diameter concrete pile in each rock
socket. After securing each concrete pile with grouting, PSF would
remove the associated outer caisson sleeve and four temporary support
H-piles. The 48-in caisson sleeves (n=4) would be permanent; thus,
extraction only applies to the 30-in caisson sleeves (n=10). Figure 3
in the IHA application provides a depiction of this process.
Installation of the 36-in steel float and donut piles will require
vibratory pile driving until refusal is reached (1,200 sec/pile),
followed by DTH driving for approximately 20 minutes to achieve the
target full 20 ft (6.1 m) embedment depth. PSF would utilize a noise
attenuation system (i.e., bubble curtain) during all DTH driving.
Proposed mitigation, monitoring, and reporting measures are
described in detail later in this document (please see Proposed
Mitigation and Proposed Monitoring and Reporting section).

Description of Marine Mammals in the Area of Specified Activities

Sections 3 and 4 of the ITA 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 this information, and we refer the
reader to these descriptions, instead of reprinting the information.
Information regarding population trends and threats for the following
species may be found in NMFS' Stock Assessment Reports (SARs; <a href="https://www.fisherie.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisherie.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 expected and
proposed to be authorized for this activity and summarizes information
related to the population or stock, including regulatory status under
the MMPA and ESA and potential biological removal (PBR), where known.
PBR is defined by the MMPA as the maximum number of animals, not
including natural mortalities, which may be removed from a marine
mammal stock while allowing that stock to reach or maintain its optimum
sustainable population (as described in NMFS' SARs). While no serious
injury or mortality is anticipated or proposed to be authorized here,
PBR and annual serious injury and mortality (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. Pacific and Alaska SARs. All values presented in table 2 are
the most recent available at the time of publication (including from
the draft 2024 SARs) and are available online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>.

Table 2--Status of Marine Mammal Species \1\ Likely To Occur Near the Project Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
ESA/ MMPA status; Stock abundance (CV,
Common name Scientific name Stock strategic (Y/N) Nmin, most recent PBR Annual M/
\2\ abundance survey) \3\ SI \4\
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Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Eschrichtiidae:
Gray whale...................... Eschrichtius robustus.. Eastern North Pacific.. -/- ; N 25,960 (0.05, 25,849, 801 131
2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
Bottlenose dolphin.............. Tursiops truncatus..... California Coastal..... -/- ; N 453 (0.06, 346, 2011). 2.7 > = 2
Family Phocoenidae (porpoises):
Harbor porpoise................. Phocoena phocoena...... San Francisco-Russian -/- ; N 7,777 (0.62, 4,811, 73 > = 0.4
River. 2017.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
California sea lion................. Zalophus californianus. United States.......... -/- ; N 257,606 (N/A, 233,515, 14,011 >321
2014).

[[Page 16904]]

Steller sea lion.................... Eumetopias jubatus..... Eastern North Pacific.. -,-,N 36,308 (N/A, 36,308, 2,178 92.3
2022).
Northern fur seal................... Callorhinus ursinus.... California............. -/- ; N 14,050 (n/a, 7,524, 451 1.8
2013).
Eastern North Pacific.. -/- ; N 612,765 (0.2, 518,651, 11,151 296
2022).
Family Phocidae (earless seals):
Pacific harbor seal............. Phoca vitulina California............. -/- ; N 30,968 (n/a, 27,348, 1,641 43
richardii. 2012).
Northern elephant seal.......... Mirounga angustirostris California Breeding.... -/- ; N 194,907 (N/A, 88,794, 5,328 11.2
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 SARs can be found online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>.
CV is the coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable.
\4\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range.

Very few marine mammal species occur consistently within SFB, and
even fewer are likely to occur near the project area (i.e., in the
inner Bay) during the planned period of in-water construction (June-
November). When cetacean sightings do occur, most tend to occur north
of the project area, in the Central Bay (the area bound by the Golden
Gate Bridge to the west, the Richmond Bridge to the north, and the San
Francisco-Oakland Bay Bridge (SFOBB) to the south). The SFOBB, the
southern boundary of the Central Bay, is approximately 1.5 miles (2.4
km) north of the project area. Only harbor seals, California sea lions,
harbor porpoises, and bottlenose dolphins are sighted in SFB year-
round; other marine mammal species sighted, although more infrequently,
include the gray whale, humpback whale, northern elephant seal,
Guadalupe fur seal, and northern fur seal. However, both the temporal
and/or spatial occurrence of the humpback whale and Guadalupe fur seal
is such that take is not expected to occur, and they are not discussed
further beyond the explanation provided here.
Humpback whales are historically rare visitors to the interior of
SFB. However, beginning in 2016, a seasonal (i.e., April to November)
influx of humpback whales occurred inside SFB near the Golden Gate
Bridge (Keener 2017). Markiwitz et al. (2024) documented increased use
of the portions of SFB near the Golden Gate strait as foraging habitat
by humpback whales. Systematic land- and boat-based observations made
during their 2016-2018 study period indicated that individual humpback
whales moved into and out of SFB (i.e., east and west of the Golden
Gate Bridge) daily, on a timescale correlated with the tidal cycle,
although individuals rarely ventured east of Alcatraz Island and never
south of the SFOBB. PSF's project location is south of the documented
foraging habitat, to the extent that neither NMFS nor PSF anticipates
that planned construction activities would result in incidental taking
of humpback whales. To ensure no take occurs, PSF proposes to shutdown
construction activities should this species show up unexpectedly and
approach the Level B harassment zone.
Although extremely rare, Guadalupe fur seals may range into the
waters of northern California and the Pacific Northwest, potentially
using the Farallon Islands (off central California) and Channel Islands
(off southern California) as haul-out sites during these movements
(Simon, 2016). However, Guadalupe fur seal occurrence in the vicinity
of San Francisco is usually in the form of stranded juveniles (usually
younger than 2 years old) with evidence of malnutrition, especially
during El Ni[ntilde]o events (NMFS 2017a). Because Guadalupe fur seals
are so rare in the area, and sightings are associated with specific
abnormal weather conditions, NMFS has determined that no Guadalupe fur
seals are likely to occur in the project vicinity and, therefore, no
take is expected to occur.
As indicated above, all eight species (with nine managed stocks) in
table 2 temporally and spatially co-occur with the activity to the
degree that take is reasonably likely to occur.

Harbor Seal

Harbor seals are distributed from Baja California north to the
Aleutian Islands of Alaska. Harbor seals do not make extensive pelagic
migrations but may travel hundreds of km to find food or suitable
breeding areas (Herder, 1986; Harvey and Goley, 2011; Carretta et al.,
2023). Harbor seals are the most common marine mammal species observed
in SFB and occur year-round, primarily observed hauled out on exposed
rocky ledges and sloughs in the southern Bay. Harbor seals, central-
place foragers (Orians and Pearson 1979) that tend to exhibit strong
site fidelity within season and across years, forage close to haul-out
sites, thus repeatedly visiting specific foraging areas (Grigg et al.,
2012; Suryan and Harvey, 1998; Thompson et al., 1998). Harbor seals in
SFB forage mainly within 7 mi (11.3 km of their primary haul-out site
(Grigg et al., 2012), and often within just 1-3 mi (1-5 km; Torok
1994). The closest harbor seal haul-out site to the Project Area is
Yerba Buena Island (YBI), approximately 3.3 mi (5.3 km) to the east of
the Project Area. Although the YBI haul-out is not expected to be
within the area of ensonification, it is likely that foraging seals
from this location would be present in the water during construction.

Gray Whale

Gray whales are one of the most common whales along the California
coast. A small number of whales, known as the Pacific Coast Feeding
Group, are known to feed along the Pacific coast between Kodiak Island,
AK and northern California, as well as in nearshore waters just outside
of SFB (Carretta et al., 2022). The southward migration to winter
breeding grounds occurs from December through February

[[Page 16905]]

while the northward migration to the feeding grounds takes place from
February through May, peaking in March. Since 2019, it has become more
common for gray whales on their northward migration, during the months
of February and March, to enter SFB to feed (Bartlett, 2022). Although
PSF would not initiate MBFL pile installation activities until June 1,
well outside the northward migratory period, it is possible that a gray
whale may enter the project area during pile driving activities.
In 2024, during monitoring required by an IHA for construction
activities near the MBFL project site, Protected Species Observers
(PSOs) observed gray whales more often than expected (Integral
Consulting Inc., 2025a). The California Academy of Sciences and Marine
Mammal Center reported an unusually high number of sightings in the SFB
in 2025, with more than 30 individual gray whales confirmed via photo
identification. By comparison, only six gray whales were sighted in SFB
in 2024. Roughly one-third of the whales sighted in 2025 remained in
SFB for at least 20 days; among these individuals, body condition
ranged from normal to emaciated.

Bottlenose Dolphin

The common bottlenose dolphin is found in all oceans across the
globe and is one of the most commonly observed marine mammal species in
coastal waters and estuaries. Two genetically distinct stocks occur off
the coast of California, the California coastal stock and the
California/Oregon/Washington offshore stock. The range of the
California coastal stock has been expanding north since an El
Ni[ntilde]o event in 1982 through 1983 (Hansen and Defran, 1990; Wells
et al., 1990) and spans as far north as Sonoma County (Keener et al.,
2023). From 2010 to 2018, a photo-identification monitoring study
identified 84 distinctive individual bottlenose dolphins in SFB, likely
belonging to the California coastal stock (Keener et al., 2023). This
stock is highly transitory, shows little site fidelity, and individuals
are highly mobile (Weller et al., 2016). Since 2008, coastal bottlenose
dolphins have been observed regularly in SFB in proximity to the Golden
Gate near the mouth of SFB, north of PSF's MBFL project site (Bay
Nature, 2020). However, due to increased numbers of dolphins occurring
in SFB, it is possible that a limited number of individuals may
approach the project area during in-water construction activities.

Harbor Porpoise

Harbor porpoises typically occur in cool temperate to sub-polar
waters less than 62.6 degrees Fahrenheit (17 degrees Celsius) (Read
1999) where prey aggregations are concentrated (Watts and Gaskin,
1985). In the eastern Pacific, harbor porpoises occur in coastal and
inland waters from Point Conception, California to Alaska (Gaskin
1984). The non-migratory San Francisco-Russian River stock ranges from
Pescadero to Point Arena, California, utilizes relatively shallow
nearshore waters (<100 m), and feeds on small schooling fishes such as
northern anchovy and Pacific herring which enter SFB (Caretta et al.,
2022; Stern et al., 2017). Harbor porpoises tend to occur in small
groups and are considered relatively cryptic animals.
Recently, observations of harbor porpoises within SFB have become
more common (Duffy 2015; Stern et al., 2017; AECOM, 2021). Before 2008,
harbor porpoises occurred primarily outside of SFB, although SFB has
historically been considered habitat for harbor porpoises (Broughton,
1999). From 2011 to 2014, the Golden Gate Cetacean Research program
conducted a visual count and identified 2,698 porpoise groups from the
Golden Gate Bridge during 96 percent of their on-effort survey days
(Stern et al., 2017). Harbor porpoise movements into SFB are linked to
tidal cycles, with the greatest numbers of individuals sighted during
high tide to ebb tide periods. Movements into SFB, which may serve as a
foraging habitat, are likely influenced by prey availability (Duffy
2015; Stern et al., 2017). Although harbor porpoise sightings are
generally concentrated in the vicinity of the Golden Gate Bridge and
Angel Island, northwest of the project site (Keener, 2011), this
species is occurring more frequently in SFB east of Angel Island and
may approach the project area during pile driving activities.

California Sea Lion

California sea lions reside in the Eastern North Pacific Ocean in
shallow coastal and estuarine waters. A common, abundant marine mammal,
they are found throughout the U.S. west coast, generally within 10-
miles of shore and are known to breed on the offshore islands of
California from May through July (Heath and Perrin 2009). During the
non-breeding season, adult and sub-adult males and juveniles migrate
northward along the coast, to central and northern California, Oregon,
Washington, and Vancouver Island (Jefferson et al., 1993). They return
south the following spring (Lowry and Forney 2005; Heath and Perrin
2009). Females and some juveniles tend to remain closer to rookeries
(Antonelis et al., 1990; Melin et al., 2008).
California sea lions occur within SFB-Delta in their highest
numbers while migrating to and from their primary breeding areas on the
Farallon and California Channel Islands, and when Pacific herring and
salmon inhabit Bay-Delta waters spawn. or migrate to upriver spawning
areas. They haul out on offshore rocks, sandy beaches, and onto
floating docks, wharfs, vessels, and other man-made structures in SFB
and coastal waters of the state.
In SFB, California sea lions have been observed at Angel Island and
occupying the docks near Pier 39, which is the largest California sea
lion haul[hyphen]out in SFB. A maximum of 1,706 sea lions were counted
at Pier 39 in 2009. However, since then the population has averaged at
about 50-300 depending upon the season (The Marine Mammal Center
((TMMC) 2017). This group of sea lions has decreased in size in recent
years, coincident with a fluctuating decrease in the herring population
in SFB. There are no known breeding sites within SFB. Their primary
breeding site is in the Channel Islands (USACE 2011). The sea lions
appear at Pier 39 after returning from the Channel Islands at the
beginning of August (Bauer 1999). No other sea lion haul[hyphen]out
sites have been identified in SFB and no pupping has been observed at
the Pier 39 site or any other site in SFB under normal conditions
(USACE 2011). Although there has been documentation of pupping on docks
in SFB, this event was during a domoic acid event. The Port does not
anticipate that any domoic events will occur during the project
construction activities. The project site is approximately 4 miles away
from Pier 39.
Although there is little information regarding the foraging
behavior of the California sea lion in southern SFB, they have been
observed foraging on a regular basis in the shipping channel south of
YBI. Foraging grounds have also been identified for pinnipeds,
including sea lions, between YBI and Treasure Island, as well as off
the Tiburon Peninsula (California Department of Transportation
(CALTRANS), 2006), 2006). The California sea lions that use the Pier 39
haul[hyphen]out site may be feeding on Pacific herring (Clupea
harengus), northern anchovy, and other prey in the waters of SFB
(CALTRANS, 2013a). In addition to the Pier 39 haul[hyphen]out,
California sea lions haul out on buoys and similar structures
throughout SFB. Although

[[Page 16906]]

mainly observed swimming off the San Francisco and Marin shorelines
within SFB, California sea lions may occasionally enter the project
area to forage.

Stellar Sea Lion

Steller sea lions are found along the North Pacific Rim from Japan
to California. The eastern Pacific U.S. stock includes animals
originating from rookeries east of Cape Suckling, Alaska, and ranges
from approximately the Alaska-Canada border to California. Breeding and
pupping occur from mid-May to mid-July. Females usually mate within two
weeks of giving birth. Steller sea lions have a polygynous mating
system in which only a small proportion of the males (i.e., bulls)
father most of the pups. Bulls are highly territorial during the
breeding season, often aggressively guarding a rocky outcrop or area
onshore. Although species' occurrence is rare in the project area,
since 1993, a single adult male Steller sea lion has been observed
using the nearby Pier 39 haul-out sites more than 30 times over 10
years, typically intermittently July through September, but as recently
as March 2026.

Northern Elephant Seal

Northern elephant seals are found in the eastern and central North
Pacific Ocean and range as far north as Alaska and as far south as
Mexico, spending approximately 9 months per year at sea. The species
breeds and pups from December through March in the Channel Islands of
California or Baja California in Mexico, preferring sandy beaches or
similar habitat (Stewart and Huber, 1993; Stewart et al., 1994;
Carretta et al., 2022). The largest rookeries are on San Nicolas and
San Miguel islands in the northern Channel Islands. Near SFB, elephant
seals breed, molt, and haul out at A[ntilde]o Nuevo Island, the
Farallon Islands, and Point Reyes National Seashore.
Elephant seals do not have any established haul out sites in the
SFB, but occasional sightings have occurred. The most recent sighting
was in 2012 on the beach at Clipper Cove on Treasure Island, when a
healthy yearling elephant seal hauled out for a day. Approximately 100
juvenile northern elephant seals strand in SFB each year, including at
YBI and Treasure Island (fewer than 10 strandings per year) (CALTRANS,
2018). Although visits to SFB are rare, it is possible that a few
individuals could be present in the project area during construction
activities.

Northern Fur Seal

Northern fur seals range from southern California north to the
Bering Sea, and west to the Okhotsk Sea and Honshu Island, Japan in the
west (Carretta et al., 2022). Most of the population breeds on the
Pribilof Islands in the southern Bering Sea, although a small
percentage of the population breed at San Miguel Island and the
Farallon Islands off the coast of California. Northern fur seals show
high site fidelity to breeding and rookery locations and may swim long
distances for prey. Their diet is composed of small schooling fish such
as walleye pollock, herring, hake, anchovy, and squid. Diet and
population trends vary with environmental conditions, such as El
Ni[ntilde]o (Carretta et al., 2022). The California stock of northern
fur seals forage in waters outside of SFB. Juvenile northern fur seals
occasionally strand in SFB, especially during El Ni[ntilde]o events
(TMMC 2016). TMMC responds to approximately five northern fur seal
strandings per year in SFB (TMMC, 2016). TMMC occasionally responds to
stranded fur seals around YBI and Treasure Island. Although rarely
observed in SFB, it is possible individuals may be present during
construction activities but unlikely that the species will be exposed
to construction activities.

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-dB threshold from composite
audiograms, previous analyses in NMFS (2018), and/or data from Southall
et al. (2007) and Southall et al. (2019). We note that the names of two
hearing groups and the generalized hearing ranges of all marine mammal
hearing groups have been recently updated (NMFS, 2024) as reflected
below in table 3.

Table 3--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 (dolphins, 150 Hz to 160 kHz.
toothed whales, beaked whales, bottlenose
whales).
Very High-frequency (VHF) cetaceans (true 200 Hz to 165 kHz.
porpoises, Kogia, river dolphins,
Cephalorhynchid, Lagenorhynchus cruciger
& L. australis).
Phocid pinnipeds (PW) (underwater) (true 40 Hz to 90 kHz.
seals).
Otariid pinnipeds (OW) (underwater) (sea 60 Hz to 68 kHz.
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 ~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 generalized
hearing ranges, please see (NMFS, 2024) for a review of available
information.

Potential Effects of Specified Activities on Marine Mammals and Their
Habitat

This section includes a summary and provides a discussion of the
ways in which components of the specified activity may impact marine
mammals and their habitat. The Estimated Take of Marine Mammals section
later in this document includes a quantitative analysis of the number
of individuals

[[Page 16907]]

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 likely to adversely affect
the species or stock through effects on annual rates of recruitment or
survival.
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.

Description of Sound Sources for the Specified Activities

Activities associated with the project with the potential to
incidentally take marine mammals though exposure to sound would include
vibratory pile installation and extraction, and DTH driving. Vibratory
hammers install piles by vibrating them and allowing the weight of the
hammer to push them into the substrate. Vibratory hammers typically
produce less sound (i.e., lower sound pressure level (SPLs)) than
impact hammers. Peak 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; CALTRANS, 2015, 2020). Sounds
produced by vibratory hammers are non-impulsive and, compared to sounds
produced by impact hammers, have a slower rise time that reduces the
probability and severity of injury, given the sound energy is
distributed over a greater amount of time (Nedwell and Edwards, 2002;
Carlson et al., 2005).
DTH driving uses a combination of drilling and impact hammering
mechanisms to advance development of a hole in rock, with or without
simultaneously advancing a pile/casing into that hole. DTH excavation
is accomplished by the efficient progression of a drill bit, rotated
under pressure while simultaneously hammered by a specialized
percussive hammer located within the drill string (i.e., ``behind'' the
bit), the combined forces moving the bit forward to fracture rock.
Traditional impact and vibratory pile driving involve a hammer striking
the top of the pile, causing the entire length of the submerged pile to
radiate sound as a linear source. However, the DTH hammering mechanism
is integrated into the drill itself, so the primary sound generation
point is at the interface of the drill bit and the substrate (i.e.,
rock) deep within the ground/seabed, radiating sound pressure more like
a point rather than linear source. DTH systems often involve a single
hammer (mono-hammer), but multi- or ``cluster'' hammer drills are also
used widely. For construction of the MBFL, PSF anticipates that
installation of the 36-in steel pipe piles to the full 20-ft (6.1-m)
embedment depth will require DTH driving using a mono-hammer.
The sounds produced by the DTH driving methods simultaneously
contain both a continuous non-impulsive component from the drilling
action and an impulsive component from the hammering effect. Therefore,
for purposes of evaluating Level A harassment and Level B harassment
under the MMPA, NMFS treats DTH systems simultaneously as both
impulsive (Level A harassment thresholds) and continuous, non-impulsive
(Level B harassment thresholds) sound source types. While DTH impact
hammering can, in general, result in Level A harassment of marine
mammals, it is not expected for this project given the small zones
produced by the proposed DTH driving (quantified in the Estimated Take
of Marine Mammals section) coupled with proposed monitoring and
shutdown measures (described in the Proposed Mitigation and Proposed
Monitoring and Reporting sections) that would prevent animals from
entering these small zones.
The likely or possible impacts of the proposed activities on marine
mammals could result from both non-acoustic and acoustic stressors.
Potential non-acoustic stressors include the physical presence of the
equipment, vessels, and personnel; however, the closest known harbor
seal (i.e., YBI) and California sea lion (i.e., Pier 39) haul-out sites
are located approximately 3.3 mi (5.3 km) and 4.0 mi (6.4 km),
respectively, from the MBFL location; thus, we expect that visual and
other non-acoustic stressors would be limited. Should any animals
approach the project site(s) closely enough to be harassed due to the
presence of equipment or personnel, we expect they would have already
traveled through the acoustic 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.

Acoustic Effects

The introduction of anthropogenic noise into the aquatic
environment from pile driving and extraction is the means by which
marine mammals may be harassed by the specified activity. In general,
animals exposed to natural or anthropogenic sound may experience
behavioral, physiological, and/or physical effects, ranging in
magnitude from none to severe (Southall et al. 2007, 2019). In general,
exposure to pile driving and extraction noise has the potential to
result in behavioral reactions (e.g., avoidance, temporary cessation of
foraging and vocalizing, changes in dive behavior) and, in limited
cases, an auditory threshold shift (TS). Exposure to anthropogenic
noise can also lead to non-observable physiological responses such an
increase in stress hormones. Additional noise in a marine mammal's
habitat can mask acoustic cues used by marine mammals to carry out
daily functions such as communication, and predator and prey detection.
The effects of pile driving noise on marine mammals are dependent on
several factors, including, but not limited to, sound type (e.g.,
impulsive vs. non-impulsive), the species, age and sex class (e.g.,
adult male vs. mom with calf), duration of exposure, the distance
between the pile and the animal, received levels, behavior at time of
exposure, and previous history with exposure (Wartzok et al., 2004;
Southall et al. 2007). Here, we discuss physical auditory effects (TSs)
followed by behavioral effects and potential impacts on habitat.
NMFS defines a noise-induced TS as a change, usually an increase,
in the threshold of audibility at a specified frequency or portion of
an individual's hearing range above a previously established reference
level (NMFS, 2018, 2024). The amount of TS is customarily expressed in
dB. A TS can be permanent or temporary. As described in NMFS (2018,
2024), there are numerous factors to consider when examining the
consequence of TS, including, but not limited to, the signal temporal
pattern (e.g., impulsive or non- impulsive), likelihood an individual
would be exposed for a long enough duration or to a high enough level
to induce a TS, the magnitude of the TS, time to recovery (seconds to
minutes or hours to days), the frequency range of the exposure (i.e.,
spectral content), the hearing and vocalization frequency range of the
exposed species relative to the signal's frequency spectrum (i.e.,

[[Page 16908]]

how animal uses sound within the frequency band of the signal; e.g.,
Kastelein et al. 2014), and the overlap between the animal and the
source (e.g., spatial, temporal, and spectral).
Auditory Injury (AUD INJ) and Permanent Threshold Shift (PTS)--NMFS
defines AUD INJ as ``damage to the inner ear that can result in
destruction of tissue . . . which may or may not result in PTS'' (NMFS,
2024). NMFS defines PTS as a permanent, irreversible increase in the
threshold of audibility at a specified frequency or portion of an
individual's hearing range above a previously established reference
level (NMFS, 2024). PTS does not generally affect more than a limited
frequency range, and an animal that has incurred PTS has incurred some
level of hearing loss at the relevant frequencies; typically, animals
with PTS are not functionally deaf (Au and Hastings, 2008; Finneran,
2016). Available data from humans and other terrestrial mammals
indicate that a 40-dB TS approximates PTS onset (see Ward et al. 1958,
1959, 1960; Kryter et al., 1966; Miller, 1974; Ahroon et al., 1996;
Henderson et al., 2008). PTS levels for marine mammals are estimates;
with the exception of a single study unintentionally inducing PTS in a
harbor seal (Kastak et al., 2008), there are no empirical data
measuring PTS in marine mammals. For various ethical reasons,
experiments involving anthropogenic noise exposure at levels inducing
PTS are not typically pursued or authorized (NMFS 2024, 2018).
Temporary Threshold Shift (TTS)--TTS is a temporary, reversible
increase in the threshold of audibility at a specified frequency or
portion of an individual's hearing range above a previously established
reference level (NMFS, 2024, 2018). Based on data from mammals ranging
from discountable to serious (similar to those discussed in the
Auditory Masking section, below). For example, a marine mammal may be
able to readily compensate for a brief, relatively small amount of TTS
in a non- critical frequency range that takes place during a time when
the animal is traveling through the open ocean, where ambient noise is
lower and there are not as many competing sounds present.
Alternatively, a larger amount and longer duration of TTS sustained
during time when communication is critical for successful mother/calf
interactions could have more serious impacts. We note that reduced
hearing sensitivity as a simple function of aging has been observed in
marine mammals, as well as humans and other taxa (Southall et al.,
2007), so we can infer that strategies exist for coping with this
condition to some degree, though likely not without cost.
Many studies have examined noise- induced hearing loss in marine
mammals (see Finneran (2015) and Southall et al. (2019) for summaries).
TTS is the mildest form of hearing impairment that can occur during
exposure to sound (Kryter, 2013). While experiencing TTS, the hearing
threshold rises, and a sound must be at a higher level in order to be
heard. In terrestrial and marine mammals, TTS can last from minutes or
hours to days (in cases of strong TTS). In many cases, hearing
sensitivity recovers rapidly after exposure to the sound ends. For
cetaceans, published data on the onset of TTS are limited to captive
bottlenose dolphin, beluga whale, harbor porpoise, and Yangtze finless
porpoise (Neophocoena asiaeorientalis) (Southall et al., 2019). For
pinnipeds in water, measurements of TTS are limited to harbor seals,
elephant seals, bearded seals (Erignathus barbatus) and California sea
lions (Kastak et al., 1999, 2007; Kastelein et al., 2019b, 2019c, 2021,
2022a, 2022b; Reichmuth et al., 2019; Sills et al., 2020). TTS was not
observed in spotted (Phoca largha) and ringed (Pusa hispida) seals
exposed to single airgun impulse sounds at levels matching previous
predictions of TTS onset (Reichmuth et al., 2016). These studies
examine hearing thresholds measured in marine mammals before and after
exposure to intense or long- duration sound exposures. The difference
between the pre-exposure and post-exposure thresholds can be used to
determine the amount of TS at various post-exposure times. The amount
and onset of TTS depend on the exposure frequency. Sounds at low
frequencies, well below the region of best sensitivity for a species or
hearing group, are less hazardous than those at higher frequencies,
near the region of best sensitivity (Finneran and Schlundt, 2013). At
low frequencies, onset-TTS exposure levels are higher compared to those
in the region of best sensitivity (i.e., a low frequency noise would
need to be louder to cause TTS onset when TTS exposure level is
higher), as shown for harbor porpoises and harbor seals (Kastelein et
al., 2019a, 2019c). Note that in general, harbor seals and harbor
porpoises have a lower TTS onset than other measured pinniped or
cetacean species (Finneran, 2015). In addition, TTS can accumulate
across multiple exposures, but the resulting TTS will be less than the
TTS from a single, continuous exposure with the same sound exposure
level (SEL) (Mooney et al., 2009; Finneran et al., 2010; Kastelein et
al., 2014, 2015). This means that TTS predictions based on the total,
cumulative SEL will overestimate the amount of TTS from intermittent
exposures, such as sonars and impulsive sources. Nachtigall et al.
(2018) describe measurements of hearing sensitivity of multiple
odontocete species (bottlenose dolphin, harbor porpoise, beluga, and
false killer whale (Pseudorca crassidens)) when a relatively loud sound
was preceded by a warning sound. These captive animals were shown to
reduce hearing sensitivity when warned of an impending intense sound.
Based on these experimental observations of captive animals, the
authors suggest that wild animals may dampen their hearing during
prolonged exposures or if conditioned to anticipate intense sounds.
Another study showed that 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 SEL
(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 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

[[Page 16909]]

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, 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, 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 depend 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) 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. echolocating animals
(including odontocetes) might have anatomical specializations that
might allow for conditioned hearing reduction and filtering of low-
frequency ambient noise, including increased stiffness and control of
middle ear structures and placement of inner ear structures (Ketten et
al., 2021). Data available on noise-induced hearing loss for mysticetes
are currently lacking (NMFS, 2018). Additionally, the existing marine
mammal TTS data come from a limited number of individuals within these
species.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals, and there is no PTS data for cetaceans, but such
relationships are assumed to be similar to those in humans and other
terrestrial mammals. PTS typically occurs at exposure levels at least
several decibels above that inducing mild TTS (e.g., a 40-dB TS
approximates PTS onset (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
PTS thresholds for impulsive sounds (such as impact pile driving pulses
as received close to the source) are at least 6 dB higher than the TTS
threshold on a peak-pressure basis and PTS cumulative SEL thresholds
are 15 to 20 dB higher than TTS cumulative SEL thresholds (Southall et
al., 2007, 2019). Given the higher level of sound or longer exposure
duration necessary to cause PTS as compared with TTS, it is
considerably less likely that PTS could occur.
Activities for this project include vibratory pile driving and
vibratory extraction, and DTH driving. There would likely be pauses in
activities producing the sound during each day. Given these pauses and
the fact that many marine mammals are unlikely to remain in the project
area for extended periods of time, the potential for TS declines.
Behavioral Harassment--Exposure to noise from vibratory pile
driving and vibratory extraction, and DTH driving, can also have the
potential to behaviorally disturb marine mammals. Generally speaking,
NMFS considers a behavioral disturbance that rises to the level of
harassment under the MMPA a non-minor response--in other words, not
every response qualifies as behavioral disturbance, and for responses
that do, those of a higher level, or accrued across a longer duration,
have the potential to affect foraging, reproduction, or survival.
Behavioral disturbance may include a variety of effects, including
subtle changes in behavior (e.g., minor or brief avoidance of an area
or changes in vocalizations), more conspicuous changes in similar
behavioral activities, and more sustained and/or potentially severe
reactions, such as displacement from or abandonment of high-quality
habitat. Behavioral responses may include changing durations of
surfacing and dives, changing direction and/or speed; reducing/
increasing vocal activities; changing/cessation of certain behavioral
activities (such as socializing or feeding); eliciting a visible
startle response or aggressive behavior (such as tail/fin slapping or
jaw clapping); avoidance of areas where sound sources are located.
Pinnipeds may increase their haul out time, possibly to avoid in- water
disturbance (Thorson and Reyff, 2006).
Behavioral responses to sound are highly variable and context-
specific and any reactions depend on numerous intrinsic and extrinsic
factors (e.g., species, state of maturity, experience, current
activity, reproductive state, auditory sensitivity, time of day), as
well as the interplay between factors (e.g., Richardson et al., 1995;
Wartzok et al., 2004; Southall et al., 2007, 2019; Weilgart, 2007;
Archer et al., 2010). Behavioral reactions can vary not only among
individuals but also within an individual, depending on previous
experience with a sound source, context, and numerous other factors
(Ellison et al., 2012), and can vary depending on characteristics
associated with the sound source (e.g., whether it is moving or
stationary, number of sources, distance from the source). In general,
pinnipeds seem more tolerant of, or at least habituate more quickly to,
potentially disturbing underwater sound than do cetaceans, and
generally seem to be less responsive to exposure to industrial sound
than most cetaceans. Please see Appendices B and C of Southall et al.
(2007) and Gomez et al.

[[Page 16910]]

(2016) for reviews of studies involving marine mammal behavioral
responses to sound.
Habituation can occur when an animal's response to a stimulus wanes
with repeated exposure, usually in the absence of unpleasant associated
events (Wartzok et al., 2004). Animals are most likely to habituate to
sounds that are predictable and unvarying. It is important to note that
habituation is appropriately considered as a ``progressive reduction in
response to stimuli that are perceived as neither aversive nor
beneficial,'' rather than as, more generally, moderation in response to
human disturbance (Bejder et al., 2009). The opposite process is
sensitization, when an unpleasant experience leads to subsequent
responses, often in the form of avoidance, at a lower level of
exposure.
As noted above, behavioral state may affect the type of response.
For example, animals that are resting may show greater behavioral
change in response to disturbing sound levels than animals that are
highly motivated to remain in an area for feeding (Richardson et al.,
1995; Wartzok et al., 2004; National Research Council (NRC), 2005).
Controlled experiments with captive marine mammals have 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. If a marine mammal does react briefly to an underwater
sound by changing its behavior or moving a small distance, the impacts
of the change are unlikely to be significant to the individual, let
alone the stock or population. However, if a sound source displaces
marine mammals from an important feeding or breeding area for a
prolonged period, impacts on individuals and populations could be
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC,
2005). However, there are broad categories of potential response, which
we describe in greater detail here, that include alteration of dive
behavior, alteration of foraging behavior, effects to breathing,
interference with or alteration of vocalization, avoidance, and flight.
Changes in dive behavior can vary widely and may consist of
increased or decreased dive times and surface intervals as well as
changes in the rates of ascent and descent during a dive (e.g., Frankel
and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et
al., 2004; Goldbogen et al., 2013a, 2013b). Variations in dive behavior
may reflect interruptions in biologically significant activities (e.g.,
foraging) or they may be of little biological significance. The impact
of an alteration to dive behavior resulting from an acoustic exposure
depends on what the animal is doing at the time of the exposure and the
type and magnitude of the response.
Disruption of feeding behavior can be difficult to correlate with
anthropogenic sound exposure, so it is usually inferred by observed
displacement from known foraging areas, the appearance of secondary
indicators (e.g., bubble nets or sediment plumes), or changes in dive
behavior. However, acoustic and movement bio-logging tools have been
used in some cases, to infer responses of feeding to anthropogenic
noise. For example, Blair et al. (2016) reported significant effects on
humpback whale foraging behavior in Stellwagen Bank in response to ship
noise including slower descent rates, and fewer side-rolling events per
dive with increasing ship nose. In addition, Wisniewska et al. (2018)
reported that tagged harbor porpoises demonstrated fewer prey capture
attempts when encountering occasional high-noise levels resulting from
vessel noise as well as more vigorous fluking, interrupted foraging,
and cessation of echolocation signals observed in response to some
high-noise vessel passes.
In response to playbacks of vibratory pile driving sounds, captive
bottlenose dolphins showed changes in target detection and number of
clicks used for a trained echolocation task (Branstetter et al., 2018).
Similarly, harbor porpoises trained to collect fish during playback of
impact pile driving sounds also showed potential changes in behavior
and task success, though individual differences were prevalent
(Kastelein et al., 2019d). As for other types of behavioral response,
the frequency, duration, and temporal pattern of signal presentation,
as well as differences in species sensitivity, are likely contributing
factors to differences in response in any given circumstance (e.g.,
Croll et al., 2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko
et al., 2007). A determination of whether foraging disruptions incur
fitness consequences would require information on or estimates of the
energetic requirements of the affected individuals and the
relationships among prey availability, foraging effort and success, and
the life history stage(s) of the animal.
Variations in respiration naturally vary with different behaviors
and alterations to breathing rate as a function of acoustic exposure
can be expected to co-occur with other behavioral reactions, such as a
flight response or an alteration in diving. However, respiration rates
in and of themselves may be representative of annoyance or an acute
stress response. Various studies have shown that respiration rates may
either be unaffected or could increase, depending on the species and
signal characteristics, again highlighting the importance in
understanding species differences in the tolerance of underwater noise
when determining the potential for impacts resulting from anthropogenic
sound exposure (e.g., Kastelein et al., 2001, 2005, 2006; Gailey et
al., 2007). For example, harbor porpoises' respiration rate increased
in response to pile driving sounds at and above a received broadband
SPL of 136 dB (zero-peak SPL: 151 dB (re 1 mPa); SEL of a single
strike: 127 dB re 1 mPa2-s) (Kastelein et al., 2013).
Avoidance is the displacement of an individual from an area or
migration path as a result of the presence of a sound or other
stressors and is one of the most obvious manifestations of disturbance
in marine mammals (Richardson et al., 1995). For example, gray whales
are known to change direction--deflecting from customary migratory
paths--in order to avoid noise from seismic surveys (Malme et al.,
1984). Avoidance may be short-term, with animals returning to the area
once the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996;
Stone et al., 2000; Morton and Symonds, 2002; Gailey et al., 2007).
Longer-term displacement is possible, however, which may lead to
changes in abundance or distribution patterns of the affected species
in the affected region if habituation to the presence of the sound does
not occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann
et al., 2006).
A flight response is a dramatic change in normal movement to a
directed and rapid movement away from the perceived location of a sound
source. The flight response differs from other avoidance responses in
the intensity of the response (e.g., directed movement, rate of
travel). Relatively little information on flight responses of marine
mammals to anthropogenic signals exist, although observations of flight
responses to the presence of predators have occurred (Connor and

[[Page 16911]]

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.
Stress Responses--An animal's perception of a threat may be
sufficient to trigger stress responses consisting of some combination
of behavioral responses, autonomic nervous system responses,
neuroendocrine responses, or immune responses (e.g., Seyle, 1950;
Moberg, 2000). In many cases, an animal's first and sometimes most
economical (in terms of energetic costs) response is behavioral
avoidance of the potential stressor. Autonomic nervous system responses
to stress typically involve changes in heart rate, blood pressure, and
gastrointestinal activity. These responses have a relatively short
duration and may or may not have a significant long-term effect on an
animal's fitness.
Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that
are affected by stress--including immune competence, reproduction,
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been
implicated in failed reproduction, altered metabolism, reduced immune
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha,
2000). Increases in the circulation of glucocorticoids are also equated
with stress (Romano et al., 2004).
The primary distinction between stress (which is adaptive and does
not normally place an animal at risk) and ``distress'' is the cost of
the response. During a stress response, an animal uses glycogen stores
that can be quickly replenished once the stress is alleviated. In such
circumstances, the cost of the stress response would not pose serious
fitness consequences. However, when an animal does not have sufficient
energy reserves to satisfy the energetic costs of a stress response,
energy resources must be diverted from other functions. This state of
distress will last until the animal replenishes its energetic reserves
sufficient to restore normal function.
Relationships between these physiological mechanisms, animal
behavior, and the costs of stress responses are well-studied through
controlled experiments and for both laboratory and free-ranging animals
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003;
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to
exposure to anthropogenic sounds or other stressors and their effects
on marine mammals have also been reviewed (Fair and Becker, 2000;
Romano et al., 2002b) and, more rarely, studied in wild populations
(e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found
that noise reduction from reduced ship traffic in the Bay of Fundy was
associated with decreased stress in North Atlantic right whales. These
and other studies lead to a reasonable expectation that some marine
mammals would experience physiological stress responses upon exposure
to acoustic stressors and that it is possible that some of these would
be classified as ``distress''. In addition, any animal experiencing TTS
would likely also experience stress responses (NRC, 2003), however
distress is an unlikely result of this project based on observations of
marine mammals during previous, similar projects in the area.
Auditory Masking--Since many marine mammals rely on sound to find
prey, moderate social interactions, and facilitate mating (Tyack,
2008), noise from anthropogenic sound sources can interfere with these
functions, but only if the noise spectrum overlaps with the hearing
sensitivity of the receiving marine mammal (Southall et al., 2007;
Clark et al., 2009; Hatch et al., 2012). Chronic exposure to excessive,
though not high-intensity, noise could cause masking at particular
frequencies for marine mammals that utilize sound for vital biological
functions (Clark et al., 2009). Acoustic masking is when other noises
such as from human sources interfere with an animal's ability to
detect, recognize, or discriminate between acoustic signals of interest
(e.g., those used for intraspecific communication and social
interactions, prey detection, predator avoidance, navigation)
(Richardson et al., 1995; Erbe et al., 2016). Therefore, under certain
circumstances, marine mammals whose acoustical sensors or environment
are being severely masked could also be impaired from maximizing their
performance fitness in survival and reproduction. The ability of a
noise source to mask biologically important sounds depends on the
characteristics of both the noise source and the signal of interest
(e.g., signal-to-noise ratio, temporal variability, direction), in
relation to each other and to an animal's hearing abilities (e.g.,
sensitivity, frequency range, critical ratios, frequency
discrimination, directional discrimination, age or TTS hearing loss),
and existing ambient noise and propagation conditions (Hotchkin and
Parks, 2013).
Marine mammals vocalize for different purposes and across multiple
modes, such as whistling, echolocation click production, calling, and
singing. Changes in vocalization behavior in response to anthropogenic
noise can occur for any of these modes and may result from a need to
compete with an increase in background noise or may reflect increased
vigilance or a startle

[[Page 16912]]

response. For example, in the presence of potentially masking signals,
humpback whales and killer whales have been observed to increase the
length of their songs (Miller et al., 2000; Fristrup et al., 2003) or
vocalizations (Foote et al., 2004), respectively, while North Atlantic
right whales (Eubalaena glacialis) have been observed to shift the
frequency content of their calls upward while reducing the rate of
calling in areas of increased anthropogenic noise (Parks et al., 2007).
Fin whales have also been documented lowering the bandwidth, peak
frequency, and center frequency of their vocalizations under increased
levels of background noise from large vessels (Castellote et al.,
2012). Other alterations to communication signals have also been
observed. For example, gray whales, in response to playback experiments
exposing them to vessel noise, have been observed increasing their
vocalization rate and producing louder signals at times of increased
outboard engine noise (Dahlheim and Castellote, 2016). Alternatively,
animals may cease sound production during production of aversive
signals (Bowles et al., 1994).
Under certain circumstances, marine mammals experiencing
significant masking could also be impaired from maximizing their
performance fitness in survival and reproduction. Therefore, when the
coincident (masking) sound is human made, it may be considered
harassment when disrupting or altering critical behaviors. It is
important to distinguish TTS and PTS, which persist after the sound
exposure, from masking, which occurs during the sound exposure. Because
masking (without resulting in TS) is not associated with abnormal
physiological function, it is not considered a physiological effect,
but rather a potential behavioral effect (though not necessarily one
that would be associated with harassment).
The frequency range of the potentially masking sound is important
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high- frequency echolocation
sounds produced by odontocetes but are more likely to affect detection
of mysticete communication calls and other potentially important
natural sounds such as those produced by surf and some prey species.
The masking of communication signals by anthropogenic noise may be
considered as a reduction in the communication space of animals (e.g.,
Clark et al., 2009) and may result in energetic or other costs as
animals change their vocalization behavior (e.g., Miller et al., 2000;
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2010; Holt
et al., 2009). Masking can be reduced in situations where the signal
and noise come from different directions (Richardson et al., 1995),
through amplitude modulation of the signal, or through other
compensatory behaviors (Hotchkin and Parks, 2013). Masking can be
tested directly in captive species (e.g., Erbe, 2008), but in wild
populations it must be either modeled or inferred from evidence of
masking compensation. There are few studies addressing real-world
masking sounds likely to be experienced by marine mammals in the wild
(e.g., Branstetter et al., 2013).
Marine mammals at or near the proposed project site may be exposed
to anthropogenic noise which may be a source of masking. Vocalization
changes may result from a need to compete with an increase in
background noise and include increasing the source level, modifying the
frequency, increasing the call repetition rate of vocalizations, or
ceasing to vocalize in the presence of increased noise (Hotchkin and
Parks, 2013). For example, in response to loud noise, beluga whales may
shift the frequency of their echolocation clicks to prevent masking by
anthropogenic noise (Eickmeier and Vallarta, 2022).
Masking occurs in the frequency band or bands that animals utilize
and is more likely to occur in the presence of broadband, relatively
continuous noise sources such as vibratory pile driving. Energy
distribution of pile driving covers a broad frequency spectrum, and
sound from pile driving would be within the audible range of pinnipeds
and cetaceans present in the proposed action area. While some
construction during the specified activities may mask some acoustic
signals that are relevant to the daily behavior of marine mammals, the
short-term duration and limited areas affected make it very unlikely
that the fitness of individual marine mammals would be impacted.
Airborne Acoustic Effects--Pinnipeds that may occur near the
project site could be exposed to airborne sounds associated with
construction activities that have the potential to cause behavioral
harassment, depending on their distance from these activities. Airborne
noise would primarily be an issue for pinnipeds that are swimming or
hauled out near the project site within the range of noise levels
elevated above airborne acoustic harassment criteria. There is also a
possibility that an animal could surface in-water, but with head out,
within the area in which airborne sound exceeds relevant thresholds and
thereby be exposed to levels of airborne sound that we associate with
harassment. However, as a result of the mitigation and monitoring
measures and due to the infrequent occurrence of marine mammals in the
area, takes by behavioral harassment resulting from airborne sounds
that would result in harassment as defined under the MMPA are not
expected.

Marine Mammal Habitat Effects

The proposed specified activities could have localized, temporary
impacts on marine mammal habitat and their prey by increasing in-water
SPLs and slightly decreasing water quality. Increased noise levels may
affect acoustic habitat (see Auditory Masking discussion above) and
adversely affect marine mammal prey in the vicinity of the project area
(see discussion below). During in-water vibratory pile driving and
vibratory extraction, and DTH driving, elevated levels of underwater
noise would ensonify the project area where both fish and some mammals
occur and could affect foraging success.
Water Quality--Temporary and localized reduction in water quality
would occur as a result of in-water construction activities. Most of
this effect would occur during the installation and extraction of piles
when bottom sediments are disturbed. The installation and extraction of
piles would disturb bottom sediments and may cause a temporary increase
in suspended sediment in the project area. During pile extraction,
sediment attached to the pile moves vertically through the water column
until gravitational forces cause it to slough off under its own weight.
The small resulting sediment plume is expected to settle out of the
water column within a few hours. Studies of the effects of turbid water
on fish (marine mammal prey) suggest that concentrations of suspended
sediment can reach thousands of milligrams per liter before an acute
toxic reaction is expected (Burton, 1993).
Effects to turbidity and sedimentation are expected to be short-
term, minor, and localized. Suspended sediments in the water column
should dissipate and quickly return to background levels in all
construction scenarios. Turbidity within the water column has the
potential to reduce the level of oxygen in the water and irritate the
gills of prey fish species in the proposed project area. However,
turbidity plumes associated with the project would be temporary and
localized, and fish in the proposed project area would be able to move
away from and avoid the areas where plumes may occur. Therefore, it is
expected that the impacts on prey fish species from turbidity, and
therefore on

[[Page 16913]]

marine mammals, would be minimal and temporary. In general, the area
likely impacted by the proposed construction activities is relatively
small compared to the available marine mammal habitat in the area and
does not include any areas of particular importance.
In-Water Construction Effects on Potential Prey--Sound may affect
marine mammals through impacts on the abundance, behavior, or
distribution of prey species (e.g., crustaceans, cephalopods, fish,
zooplankton). Marine mammal prey varies by species, season, and
location and, for some, is not well documented. Here, we describe
studies regarding the effects of noise on known marine mammal prey.
Fish utilize the soundscape and components of sound in their
environment to perform important functions such as foraging, predator
avoidance, mating, and spawning (e.g., Zelick et al., 1999; Fay, 2009).
Depending on their hearing anatomy and peripheral sensory structures,
which vary among species, fishes hear sounds using pressure and
particle motion sensitivity capabilities and detect the motion of
surrounding water (Fay et al., 2008). The potential effects of noise on
fish depend on the overlapping frequency range, distance from the sound
source, water depth of exposure, and species-specific hearing
sensitivity, anatomy, and physiology. Key impacts to fishes may include
behavioral responses, hearing damage, barotrauma (pressure-related
injuries), and mortality.
Fish react to sounds which are especially strong and/or
intermittent low-frequency sounds, and behavioral responses such as
flight or avoidance are the most likely effects. Short duration, sharp
sounds can cause overt or subtle changes in fish behavior and local
distribution. The reaction of fish to noise depends on the
physiological state of the fish, past exposures, motivation (e.g.,
feeding, spawning, migration), and other environmental factors.
Hastings and Popper (2005) identified several studies that suggest fish
may relocate to avoid certain areas of sound energy. Additional studies
have documented effects of pile driving on fish, although several are
based on studies in support of large, multiyear bridge construction
projects (e.g., Scholik and Yan, 2001, 2002; Popper and Hastings,
2009). Several studies have demonstrated that impulse sounds might
affect the distribution and behavior of some fishes, potentially
impacting foraging opportunities or increasing energetic costs (e.g.,
Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski et al.,
1992; Santulli et al., 1999; Paxton et al., 2017). However, some
studies have shown no or slight reaction to impulse sounds (e.g., Pena
et al., 2013; Wardle et al., 2001; Jorgenson and Gyselman, 2009; Cott
et al., 2012). More commonly, though, the impacts of noise on fish are
temporary.
SPLs of sufficient strength have been known to cause injury to fish
and fish mortality. However, in most fish species, hair cells in the
ear continuously regenerate and loss of auditory function is likely
restored when damaged cells are replaced with new cells. Halvorsen et
al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours
for one species. Impacts would be most severe when the individual fish
is close to the source and when the duration of exposure is long.
Injury caused by barotrauma can range from slight to severe and can
cause death and is most likely for fish with swim bladders. Barotrauma
injuries have been documented during controlled exposure to impact pile
driving (Halvorsen et al., 2012b; Casper et al., 2013).
The greatest potential impact to fishes during construction would
occur during DTH driving, which has an impact hammer component. In-
water construction activities would only occur during daylight hours,
allowing fish to forage and transit the project area in the evening.
Vibratory pile driving would possibly elicit behavioral reactions from
fishes such as temporary avoidance of the area but is unlikely to cause
injuries to fishes or have persistent effects on local fish
populations. Construction also would have minimal permanent and
temporary impacts on benthic invertebrate species, a marine mammal prey
source. In addition, it should be noted that the area in question is
low-quality habitat since it is already highly developed and
experiences a high level of anthropogenic noise from normal operations
and other vessel traffic. In general, any negative impacts on marine
mammal prey species are expected to be minor and temporary.
Fish populations in the proposed project area that serve as marine
mammal prey could be temporarily affected by noise from pile
installation and extraction. The frequency range in which fishes
generally perceive underwater sounds is 50 to 2,000 Hz, with peak
sensitivities below 800 Hz (Popper and Hastings, 2009). Fish behavior
or distribution may change, especially with strong and/or intermittent
sounds that could harm fishes. High underwater SPLs have been
documented to alter behavior, cause hearing loss, and injure or kill
individual fish by causing serious internal injury (Hastings and
Popper, 2005).
The most likely impact to fish from pile driving and extraction
activities in the project area would be temporary behavioral avoidance
of the area. The duration of fish avoidance of an area after pile
driving stops is unknown, but a rapid return to normal recruitment,
distribution and behavior is anticipated. In general, impacts to marine
mammal prey species are expected to be minor and temporary due to the
expected short daily duration of individual pile driving events.
In-Water Construction Effects on Potential Foraging Habitat--The
area likely impacted by the project is relatively small compared to the
available habitat in the SFB area and does not include any biologically
important areas (BIAs) or ESA-designated critical habitat. The total
area affected by the project is small compared to the vast foraging
area available to marine mammals in the area. Pile driving and
extraction at the project site would not obstruct long-term movements
or migration of marine mammals.
Avoidance by potential prey (i.e., fish) of the immediate area due
to the temporary loss of this foraging habitat is also possible. The
duration of fish and marine mammal avoidance of this area after pile
driving stops is unknown, but a rapid return to normal recruitment,
distribution, and behavior is anticipated.
In summary, given the short daily duration of sound associated with
individual pile driving events and the relatively small areas being
affected, pile driving activities associated with the proposed action
are not likely to have a permanent adverse effect on any fish habitat,
or populations of fish species. Any behavioral avoidance by fish of the
disturbed area would still leave significantly large areas of fish and
marine mammal foraging habitat in the nearby vicinity. Thus, we
conclude that impacts of the specified activity are not likely to have
more than short-term adverse effects on any prey habitat or populations
of prey species. Further, any impacts to marine mammal habitat are not
expected to result in significant or long-term consequences for
individual marine mammals, or to contribute to adverse impacts on their
populations.

Estimated Take of Marine Mammals

This section provides an estimate of the number of incidental takes
proposed for authorization through the IHA, which will inform NMFS'
consideration

[[Page 16914]]

of ``small numbers'' and the negligible impact determinations.
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 be by Level B harassment, as use of the
acoustic sources (i.e., vibratory installation and extraction, DTH
driving) has the potential to result in disruption of behavioral
patterns for individual marine mammals. Based on the nature of the
activity and the anticipated effectiveness of the mitigation measures
(i.e., shutdown at the Level A harassment isopleth) discussed in detail
below in the Proposed Mitigation section, Level A harassment is neither
anticipated nor proposed to be authorized. 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 RMS
pressure received levels (RMS SPL) of 120 dB (referenced to 1 re 1
[mu]Pa) for continuous (e.g., vibratory pile driving, drilling) and
above RMS SPL 160 dB re 1 [mu]Pa for non-explosive impulsive (e.g.,
seismic airguns) or intermittent (e.g., scientific sonar) sources.
Generally speaking, estimates of take by Level B harassment 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.
PSF's proposed construction activity includes the use of vibratory
pile driving and extraction, and DTH driving, both of which are treated
as continuous noise sources when evaluating the potential for Level B
harassment; therefore, the RMS SPL thresholds of 120 dB re 1 [mu]Pa is
applicable.
Level A Harassment--NMFS' 2024 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) (table 4). PSF's proposed activity
includes the use of impulsive (DTH hammering component) and non-
impulsive (vibratory pile driving and DTH drilling component) sources.
The 2024 Updated Technical Guidance criteria include both updated
thresholds and updated weighting functions for each hearing group
(table 4). These thresholds criteria are provided in the table below.
The references, analysis, and methodology used in the development of
the criteria thresholds, as well as the detailed description of the
updated weighting functions, are described in NMFS' 2024 Updated
Technical Guidance, which may be accessed at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools</a>.

Table 4--Thresholds Identifying the Onset of AUD INJ
----------------------------------------------------------------------------------------------------------------
AUD INJ onset thresholds * (received level)
Hearing group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: L0-pk,flat: 222 Cell 2: LE, LF,24h: 197 dB.
dB; LE, LF,24h: 183 dB.
High-Frequency (HF) Cetaceans.......... Cell 3: L0-pk,flat: 230 Cell 4: LE, HF,24h: 201 dB.
dB; LE, HF,24h: 193 dB.
Very High-Frequency (VHF) Cetaceans.... Cell 5: L0-pk,flat: 202 Cell 6: LE, VHF,24h: 181 dB.
dB; LE,VHF,24h: 159 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: L0-pk.flat: 223 Cell 8: LE,PW,24h: 195 dB.
dB; LE,PW,24h: 183 dB.

[[Page 16915]]

Otariid Pinnipeds (OW) (Underwater).... Cell 9: L0-pk,flat: 230 Cell 10: LE,OW,24h: 199 dB.
dB; LE,OW,24h: 185 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating AUD
INJ onset. If a non-impulsive sound has the potential of exceeding the peak SPL thresholds associated with
impulsive sounds, these thresholds are recommended for consideration.
Note: Peak SPL (L0-pk) has a reference value of 1 [micro]Pa, and weighted cumulative SEL (LE,) has a reference
value of 1[micro]Pa\2\s. In this table, thresholds are abbreviated to be more reflective of International
Organization (ISO) for Standardization standards (ISO 2017). The subscript ``flat'' is being included to
indicate peak sound pressure are flat weighted or unweighted within the generalized hearing range of marine
mammals (i.e., 7 Hz to 165 kHz). The subscript associated with cumulative SEL thresholds indicates the
designated marine mammal auditory weighting function (LF, HF, and VHF cetaceans, and PW and OW pinnipeds) and
that the recommended accumulation period is 24 hours. The weighted cumulative SEL thresholds could be exceeded
in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it is
valuable for action proponents to indicate the conditions under which these thresholds will be exceeded.

As discussed in the Description of Sound Sources section above, DTH
systems have both continuous, non-impulsive, and impulsive components.
When evaluating Level B harassment, NMFS recommends treating DTH as a
continuous source and applying RMS SPL thresholds of 120 dB re 1
[mu]Pa. When evaluating Level A harassment, NMFS recommends treating
DTH as an impulsive source, applying the thresholds in the second
column of table 4.
NMFS (2022) guidance on DTH systems recommends source levels for
DTH systems (<a href="https://media.fisheries.noaa.gov/2022-11/PUBLIC%20DTH%20Basic%20Guidance_November%202022.pdf">https://media.fisheries.noaa.gov/2022-11/PUBLIC%20DTH%20Basic%20Guidance_November%202022.pdf</a>). NMFS has applied
those levels in our analysis (see table 5 for NMFS' proposed source
levels) of potential acoustic impacts from DTH driving during PSF's
installation of 36-in steel pipe piles.

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., pile driving and extraction).
The project includes vibratory pile installation and extraction and
DTH driving. Source levels for these activities are based on reviews of
measurements of the same or similar types and dimensions of pile
available in the literature. Source levels for each pile size are
presented in table 5. Source levels for vibratory installation and
extraction of piles of the same diameter are assumed to be the same.
PSF plans to use a bubble curtain for all DTH driving, and a 5-dB
reduction in source level is assumed from those presented in table 5
for DTH driving.

Table 5--Source Levels for Proposed Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Daily/total Source level (dB)
Pile piling events --------------------------------
Project element Pile type diameter Method Duration (seconds/ (including
(in) pile) installation and Peak SEL RMS
extraction)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pile driving template piles.... H-pile steel 14 Vibratory pile 600.............. 8/80 (40 165 NA 150
(temporary). installation and installed and 40
extraction. removed).
Pier (Bents 1 & 2)............. Steel Caisson 48 Vibratory pile 900.............. 1/4.............. NA NA 170
(permanent). installation.
Pier (Bents 3-7)............... Steel Caisson 30 Vibratory pile 900.............. 2/20 (10 196 NA 159
(temporary). installation and installed and 10
extraction. removed).
Float Guide and Donut Fender Steel (permanent) 36 Vibratory pile 1,200............ 2/8.............. 206 172 172
Piles. installation.
DTH driving...... 20 minutes (10 2/8.............. \1\ 194 164 \1\ 174
strikes per
second).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ PSF will deploy a bubble curtain during all DTH driving, which is expected to provide a 5-dB reduction from the source levels presented in table
(SPLpeak and SPLrms).

Transmission loss (TL) is the decrease in acoustic intensity as an
acoustic pressure wave propagates out from a source in the acoustic
field. 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 acoustic monitoring with differing measured
TL, a practical spreading loss value of 15 is used as the TL
coefficient in the above formula for nearshore environments. Site-
specific TL data for the MBFL project site 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 TL model described above was used to calculate the expected
noise propagation from vibratory pile driving and extraction, and DTH
driving, using

[[Page 16916]]

representative source levels to estimate the harassment zones exceeding
the noise criteria. The resulting distances to Level A harassment and
Level B harassment isopleths are shown in table 6. The largest
calculated distances to the Level B harassment isopleth would be
produced during vibratory pile installation of 36-in steel pipe piles
(29,286 m) and 48-in steel caisson sleeves (21,544 m), and DTH driving
of 36-in steel pipe piles (39,811 m). However, when accounting for
attenuation from landmass interference, the maximum radius of the Level
B harassment zone is approximately 6,000 m (table 6).
The ensonified area associated with Level A harassment (AUD INJ) is
more technically challenging to predict due to the need to account for
a duration component. Therefore, NMFS developed an optional User
Spreadsheet tool to accompany the 2024 Updated Technical Guidance that
can be used to 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 (AUD INJ). However, this optional tool offers the best way
to estimate isopleth distances when more sophisticated modeling methods
are not available or practical. For stationary sources such as pile
driving and DTH, 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, which
includes but is not limited to PTS.
PSF used NMFS' 2024 Updated Technical Guidance and optional User
Spreadsheet to calculate the maximum distances to Level A harassment
(AUD INJ onset) thresholds for all in-water construction activities
(i.e., vibratory installation and extraction, and DTH driving). Inputs
used in the optional User Spreadsheet tool include values in table 1
(e.g., number of piles per day, duration) and table 5 (i.e., source
levels). Sound source locations were chosen to model the greatest
possible affected area from the representative notional pile location.
The resulting estimated distances to Level A harassment threshold
isopleths are reported below in table 6.

Table 6--Maximum Distances \1\ to MMPA Harassment Threshold Isopleths
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Distance to Level A harassment (AUD INJ) isopleth Distance to
(meters) Level B
Pile ------------------------------------------------------- harassment
Project element Pile type diameter Duration (seconds/pile) Method Cetaceans Pinnipeds isopleth
(in) ------------------------------------------------------- \1\
LF HF VHF PW OW (meters)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Pile driving template piles......... H-pile steel 14 600.................... Vibratory pile 4.4 1.7 3.6 5.7 1.9 2,154
(temporary). installation and
extraction.
Pier (Bents 1 & 2).................. Steel Caisson 48 900.................... Vibratory pile 23.1 8.9 18.9 29.8 10 \2\ 21,554
(permanent). installation.
Pier (Bents 3-7).................... Steel Caisson 30 900.................... Vibratory pile 4.3 1.6 3.5 5.5 1.9 3,981
(temporary). installation and
extraction.
Float Guide and Donut Fender Piles.. Steel (permanent)...... 36 1,200.................. Vibratory pile 38.1 14.6 31.1 49 16.5 \2\ 29,286
installation.
20 minutes (10 strikes DTH driving \3\........ 282.2 36 436.8 250.7 93.5 \2\ 39,811
per second).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ The distances to Level B harassment isopleth were evaluated relative to the 120 dB SPLrms threshold for vibratory pile driving and DTH driving, based on its continuous component.
\2\ The harassment zones will be truncated due to the presence of intersecting landmasses, extending to a maximum of 6,000 m from the sound source during vibratory pile installation of 48-in
steel caisson sleeves and both methods of installation (i.e., vibratory pile driving and DTH driving) of 36-in steel pipe piles.
\3\ All distances calculated assuming 5 dB attenuation by a bubble curtain.

Marine Mammal Occurrence and Take Estimation

In this section, we provide information about the occurrence of
marine mammals, including density or other relevant information that
will inform the take calculations.
No systematic line transect surveys of marine mammals have been
performed in SFB. Therefore, estimates of occurrence for each species
were derived using the following datasets:
<bullet> 17 years of sighting data collected during the SFOBB
construction project (CALTRANS, 2018);
<bullet> 5 years of sighting and stranding data from TMMC (NMFS,
2021b as cited by Integral Consulting Inc., 2025a)
<bullet> 5 years of sighting and stranding data from The California
Academy of Sciences (CAS) (Integral Consulting Inc., 2025a); and
<bullet> Monitoring data collected in Spring 2025 over 11 days in
Remedial Response Areas A and B (required by NMFS-issued IHA for the
Piers 39 to 43\1/2\ Sediment Remediation Project) (Integral Consulting
Inc., 2025b).
Monitoring data collected by CALTRANS for the SFOBB project over 17
years can be used to approximate density of the observed species near
PSF's project site. Care was taken to eliminate multiple observations
of the same animal in the dataset, although this can be difficult and
it is likely that the same individual may have been counted by
observers multiple times on the same day. The amount of monitoring
performed per year varied, depending on the frequency and duration of
construction activities with the potential to affect marine mammals.
During the 257 days of monitoring from 2000 through 2017 (including 15
days of baseline monitoring in 2003), CALTRANS observed a total of
1,029 harbor seals, 83 California sea lions, and 24 harbor porpoises in
the vicinity of the SFOBB, with the number of harbor seals and harbor
porpoises increasing significantly beginning in 2015. These
observations included data from baseline, pre-, during, and post-pile
driving, mechanical dismantling, onshore blasting, and offshore
implosion activities.
The TMMC and CAS datasets report sightings of marine mammals found
within SFB between September 2016 and September 2021. The sightings
include those of stranded animals (that

[[Page 16917]]

were of confirmed species and associated with a confirmed location
within SFB) whether they were living, dead (all stages of
decomposition), floating, or stranded. The TMMC and CAS often have
duplicate sightings in their databases due to how information is
received from the public. As TMMC receives the most reports from the
public, their dataset was treated as the primary source. Duplicates
were removed from the CAS dataset and CAS sightings are reported
separately. The age, sex, and reproductive condition of individuals of
each species that may potentially be taken is difficult to estimate
given the lack of information on the class distribution of these
species within the project area and greater SFB. Below are estimates
for each species potentially affected.
Depending on the distribution of sightings and granularity of data,
different sources have been used to estimate the species-specific
number of individuals expected to occur within SFB and, thus,
potentially within the area ensonified by PSF's pile-installation
activities.
Gray Whale
Gray whales may enter SFB in late winter/early spring or in the
fall during their migrations and, in recent years, there have been an
increased number of gray whales in the western and Central Bay
(Integral Consulting Inc., 2025a). During construction in March-April
2025, multiple gray whales were observed in SFB (Integral Consulting
Inc., 2025b). According to TMMC, in June 2025, 9 individual gray whales
were observed over 14 days (TMMC, unpublished data). As such, PSF
anticipates the potential for gray whale occurrence in the MBFL
project's Level B harassment ensonified zones. Given these data, and
the trends they indicate, PSF estimates that one gray whale could occur
in the project area every other day (0.5 whales/day), and NMFS concurs
with this approach.
Bottlenose Dolphin
Historically, observations of bottlenose dolphins have occurred
west of Treasure Island and were concentrated along the nearshore area
of San Francisco south to Redwood City. Since 2016, one individual has
been regularly seen near the former Alameda Air Station, and five
animals were regularly seen in the summer and fall of 2018 in the same
location (Integral Consulting Inc., 2025a). In February 2019, an adult
and juvenile were seen on two separate occasions northwest of the
Oakland Inner Harbor, over 4 mi (6.4 km) from PSF's proposed project
area (Integral Consulting Inc., 2025a). No bottlenose dolphins were
observed during pre-construction monitoring in 2020 (Haase, 2021) or
during construction in the spring of 2025 (Integral Consulting Inc.,
2025b). Although bottlenose dolphins are relatively uncommon in SFB,
NMFS conservatively assumes that one group of bottlenose dolphins will
be present in the project area during the construction period. A group
size is estimated to be five animals based on sightings of bottlenose
dolphins in SFB (Integral Consulting Inc., 2025a).
Pacific Harbor Porpoise
Harbor porpoises are primarily seen near the Golden Gate Bridge,
Marin County, and the city of San Francisco on the northwest side of
SFB (Keener et al., 2012; Stern et al., 2017). CAS recorded 29 harbor
porpoises (only 2 of which were alive) over the past 5 years, and
<a href="https://www.iNaturalist.org">https://www.iNaturalist.org</a> recorded 11 harbor porpoises in SFB over
the past 2 years. During 2020 monitoring, an individual harbor porpoise
was seen near the project area on 2 of the 5 monitoring days (Haase,
2021), and a single harbor porpoise was observed within the Level B
harassment zone during 11 days of monitoring in the spring of 2025
(Integral Consulting Inc., 2025b). Based on these data, PSF estimates
that two harbor porpoises could occur within the MBFL project's Level B
harassment zone per day, and NMFS concurs.
California Sea Lion
The Pier 39 K-Dock California sea lion haul-out site supports up to
1,701 individuals, with the highest abundance occurring from August
through October. Pier 39 is the only regularly used sea lion haul-out
site in the project vicinity, located approximately 3 mi (5 km)
northwest of the MBFL project site. The Sea Lion Center at Pier 39
regularly counted sea lions at K-Dock from 1991 through 2018; from 2016
through 2018, the yearly average ranged from 89 to 229 animals per day;
the average per day over all 3 years was 191. The maximum numbers of
animals using the haul-out site in 2016, 2017, and 2018 were 707, 239,
and 466 respectively; the average maximum per day over this period was
324. TMMC recorded 1,586 sea lions in SFB between September 2016 and
September 2021. CAS recorded an additional 191 for a total of 1,777
over 5 years. Based on these data, PSF estimates that California sea
lions could occur within the MBFL project's Level B harassment zone at
a rate of 0.97 per day, and NMFS concurs with this approach.
Steller Sea Lion
Steller sea lions are rare in SFB. TMMC recorded four Steller sea
lions in SFB from 2016 to 2021 (NMFS, 2021b), and CAS recorded no
Steller sea lions over the same time frame (NMFS, 2021a). On rare
occasions, Steller sea lions are seen on the Pier 39 K-Dock haul-out
site (located approximately 3 miles (5 km) northwest of the MBFL site).
An adult male was spotted there in May 2023 (Segura, 2023), and, in
previous years, a single male Steller sea lion had been observed using
the Pier 39 K-Dock haul-out site intermittently during July and August,
and occasionally September (Integral Consulting Inc., 2025a). No
Steller sea lions were observed during the 2020 or 2025 monitoring
(Haase, 2021; Integral Consulting Inc., 2025b). Given the potential for
Stellar sea lion occurrence at Pier 39, if only rarely, NMFS feels it
is appropriate to assume one Steller sea lion may occur in PSF's
proposed project area during the period of construction.
Northern Fur Seal
TMMC recorded 44 northern fur seals in SFB from 2016 to 2021 (NMFS,
2021b). CAS recorded an additional 3 for a total of 47 over 5 years
(NMFS, 2021a), yielding a frequency of 0.03 northern fur seals per day,
or approximately 10 northern fur seals per year. In the fall and
winter, northern fur seals occasionally strand on YBI and Treasure
Island (Integral Consulting Inc., 2025a), approximately 3.3 mi (5.3 km)
from PSF's proposed project area. PSF assumes 10 northern fur seals
could occur in the proposed project area and within the Level B
harassment zone per year (i.e., within the effective period of the
proposed IHA), given the maximum potential sightings in San Franciso
Bay averaged over a 5-year period is 10 individuals. NMFS concurs with
this approach.
Northern Elephant Seal
TMMC recorded 903 northern elephant seals in SFB from 2016 to 2021
(NMFS, 2021b). The CAS reported an additional 6 northern elephant seals
over the same timeframe (NMFS, 2021a), for a total of 909 seals,
yielding an average of 0.5 northern elephant seals per day. No northern
elephant seals were observed during monitoring efforts conducted in
2020 and 2025 (Haase, 2021; Integral Consulting Inc., 2025b). Based on
these data, PSF assumed 0.5 elephant seals will occur in the proposed
project area per day (i.e., one elephant seal in the ensonified zone

[[Page 16918]]

every 2 days). NMFS concurs with this assumption.
Pacific Harbor Seal
Pacific harbor seals in SFB forage mainly within 7 mi (11.3 km) of
their primary haul-out site (Grigg et al., 2012) and often within just
1-3 mi (1.6-4.8 km) (Torok, 1994). The only harbor seal haul-out site
within 7 mi (11.3 km) of the project site is YBI, approximately 3.3 mi
(5.3 km) northeast of the MBFL site. Given the large Level B harassment
zone sizes predicted for vibratory installation of 48-in steel caisson
sleeves (21,554 m) and 36-in steel pipe piles (29,286 m), and DTH
driving of 36-in steel pipe piles (39,811 m), it is likely harbor seals
foraging in the vicinity of the YBI would enter the ensonified area
during pile installations.
The TMMC recorded 495 harbor seals in SFB between September 2016
and September 2021. CAS recorded an additional 34 for a total of 529
over the same period, yielding an average of 0.29 per day. CALTRANS has
reported between zero and 188 harbor seals using the YBI haul-out site,
depending on the year. PSF determined that an occurrence rate estimate
for harbor seals based on the CALTRANS dataset (3.957 harbor seals per
day) would be appropriate, given the large sample size, and NMFS
concurs.
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.
To estimate take by Level B harassment for the gray whale, harbor
porpoise, California sea lion, northern elephant seal, and harbor seal,
the species-specific expected daily occurrence was multiplied by the
estimated number of construction days for the entire project (n=46),
which includes only 32 days of in-water construction with the potential
for incidental take of marine mammals (see table 1) and an additional
14 days to support placement of the 24-in octagonal concrete piles, a
process that does not require pile driving or DTH. PSF estimated take
based on the maximum total of 46 days to account for any delays in
construction. PSF is assuming that five northern fur seals and one
Steller sea lion will occur in the proposed project area during the
course of pile installations (see table 7). For bottlenose dolphins,
PSF estimates that one group of five bottlenose dolphins will occur in
the proposed project area during the 46-day construction period (table
7).

Table 7--Estimated Take by Level B Harassment Proposed for Authorization
----------------------------------------------------------------------------------------------------------------
Estimated Percent of
abundance in Total take Stock stock (take/
Species Stock project area requested abundance abundance
per day \1\ *100)
----------------------------------------------------------------------------------------------------------------
Gray Whale.................... Eastern North 0.5 23 26,960 <0.1
Pacific.
Bottlenose Dolphin............ California 5 5 453 1.10
Coastal.
Harbor Porpoise............... San Francisco- 2 92 7,777 1.18
Russian River.
California Sea Lion........... United States... 0.97 45 257,606 <0.1
Northern Fur Seal............. Eastern North 0.027 2 14,050 <0.1
Pacific.
California...... 626,618 <0.1
Steller Sea Lion.............. Eastern North 0.0027 1 43,201 <0.1
Pacific.
Pacific Harbor Seal........... California...... 3.957 183 30,968 <0.1
Northern Elephant Seal........ California 0.5 23 187,386 <0.1
Breeding.
----------------------------------------------------------------------------------------------------------------
\1\ Local occurrence information calculated based on CALTRANS (2018), NOAA (2021a, b), and Integral Consulting
(2025 a, b).

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 ITAs 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 sections
were either proposed by PSF in its adequate and complete application or
are the result of subsequent coordination between NMFS and PSF. PSF has
agreed that all 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 measures below as proposed mitigation
requirements (see section 11 of PSF's application for more detail) and
has included them in the proposed IHA.
PSF, as the responsible named party of the proposed IHA, must
ensure that construction supervisors and crews, the monitoring team,
and relevant staff are trained prior to the start of all vibratory pile
driving and DTH driving activity, so that responsibilities,
communication procedures, monitoring protocols, and operational
procedures are clearly

[[Page 16919]]

understood. New personnel joining during the project must be trained
prior to commencing work. In addition to the measures described later
in the Proposed Monitoring and Reporting section and all mitigation
measures described in PSF's Marine Mammal Monitoring Plan, the
following mitigation measures would also apply to the in-water
construction activities.
Implementation/Coordination-- Qualified, trained PSOs would
implement mitigation measures. PSOs would be located on-site before,
during, and after permitted activities to monitor marine mammals within
(and approaching) mitigation zones. PSOs would be in constant contact
with the construction personnel to implement appropriate mitigation
measures. Briefings must be conducted between construction supervisors
and crews and the marine mammal monitoring team before the start of all
vibratory pile driving/extraction and DTH driving activities and when
new personnel join the work to explain responsibilities, communication
procedures, marine mammal monitoring protocol, and operational
procedures.
Establishment of Shutdown Zones -- Shutdown zones for all the
specified activities can be found in table 8. A shutdown zone generally
defines an area near or within which a marine mammal sighting would
trigger cessation of a specified activity. Shutdown zone sizes would
vary based on the activity type and marine mammal hearing group (table
3). PSF proposes shutdown zones with radial distances identified in
table 8 for all construction activities (i.e., pile driving or
extraction and DTH). If a marine mammal enters or is observed within an
established shutdown zone, pile driving must be halted or delayed. Pile
driving may not commence or resume until either the animal has
voluntarily left and been visually confirmed beyond the shutdown zone,
or 15 minutes have passed without subsequent detections. For those
marine mammals for which take has not been authorized, vibratory pile
driving/extraction and DTH driving would shut down immediately if such
species are observed within or entering any harassment zone defined for
that activity.
For those marine mammals for which take has not been authorized,
in-water vibratory pile installation and extraction, and DTH, would
shut down immediately if such species are observed within or entering
the Level A or Level B harassment zone.

Table 8--Proposed Shutdown Zones and Level B Harassment Zones for Project Activities
----------------------------------------------------------------------------------------------------------------
Level A (AUD INJ onset) Level B (Behavioral)
Pile description shutdown zone radius for harassment zone radius
all species (meters) (meters)
----------------------------------------------------------------------------------------------------------------
Vibratory pile driving and extraction
----------------------------------------------------------------------------------------------------------------
14-inch steel H-pile (temporary)...................... 10 2,200
48-inch steel caisson (permanent)..................... 30 \1\ 6,000
30-inch steel caisson (temporary)..................... 10 4,000
36-inch steel pipe (permanent)........................ 50 \1\ 6,000
----------------------------------------------------------------------------------------------------------------
DTH driving
----------------------------------------------------------------------------------------------------------------
36-inch steel pipe (permanent)........................ 450 \1\ 6,000
----------------------------------------------------------------------------------------------------------------
\1\ 6,000 meters is the maximum distance sound can propagate in the project area before interception by land.

PSOs--PSF must employ PSOs who would monitor the project area to
the maximum extent possible based on the required number of PSOs,
required monitoring locations, and environmental conditions. The
number, placement, and qualifications of PSOs during all pile driving
and extraction activities (described in detail in the Proposed
Monitoring and Reporting section) would ensure that the entire shutdown
zone is visible during pile installation. Visual monitoring would be
conducted by at least one PSO, depending on the pile activity.
Pre- and Post-activity Monitoring--Before starting daily in-water
construction activity, or whenever a break in activity (i.e., vibratory
pile driving/extraction or DTH driving) of 30 minutes or longer occurs,
the PSO(s) would observe the shutdown and monitoring zones for 30
minutes. The shutdown zone would be considered cleared when a marine
mammal has not been observed within the zone for those 30 minutes. If a
marine mammal is observed within the shutdown zone, pile-driving
activities (i.e., vibratory pile driving installation/extraction or DTH
driving) cannot proceed until the animal has left the zone or has not
been observed for 15 minutes. When a marine mammal for which take is
authorized is present in the harassment zone, activities may begin.
Bubble Curtain--PSF would employ a bubble curtain during all DTH
driving. The bubble curtain must distribute air bubbles around 100
percent of the piling circumference for the full depth of the water
column. The lowest bubble ring must be in contact with the mudline for
the full circumference of the ring. The weights attached to the bottom
ring must ensure 100 percent substrate contact. No parts of the ring or
other objects may prevent full substrate contact. Air flow to the
bubblers must be balanced around the circumference of the pile.
Based on our evaluation of the applicant's proposed measures, as
well as other measures we considered, NMFS has preliminarily determined
that the proposed mitigation measures provide the means of effecting
the least practicable impact on the affected species or stocks and
their habitat, paying particular attention to rookeries, mating
grounds, and areas of similar significance.

Proposed Monitoring and Reporting

To issue an IHA for an activity, section 101(a)(5)(D) of the MMPA
states that NMFS must set forth requirements pertaining to the
monitoring and reporting of such taking. The MMPA implementing
regulations at 50 CFR 216.104(a)(13) indicate that requests for
authorizations must include the suggested means of accomplishing the
necessary monitoring and reporting that 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 to
compliance as well as ensuring that the

[[Page 16920]]

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> Extent to which 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 here were
proposed by PSF in its adequate and complete application and/or are the
result of subsequent coordination between NMFS and PSF has agreed to
the requirements. NMFS describes these below as requirements and has
included them in the proposed IHA.
PSF would abide by all monitoring and reporting measures contained
within the IHA, if issued, and their Marine Mammal Monitoring and
Mitigation Plan (to be submitted for NMFS approval no later than 30
days prior to the start of construction). A summary of those measures
and additional requirements proposed by NMFS is provided below.
Visual Monitoring--Qualified, NMFS-approved PSOs must conduct
monitoring in accordance with project's Marine Mammal Monitoring Plan.
PSOs would be independent of the activity contractor (for example,
employed by a subcontractor) and have no other assigned tasks during
monitoring periods. At least one PSO would have prior experience
performing the duties of a PSO during an activity pursuant to a NMFS-
issued ITA. Other PSOs may substitute other relevant experience,
education (degree in biological science or related field), or training
for prior experience performing the duties of a PSO during construction
activity pursuant to a NMFS-issued ITA. PSOs would be present during
all pile installation and extraction activities, including vibratory
and DTH methods, in accordance with the following:
<bullet> Observer training must be provided before the project
starts and must include instruction on species identification
(sufficient to distinguish the species in the project area),
description and categorization of observed behaviors, and
interpretation of behaviors that may be construed as being reactions to
the specified activity, proper completion of data forms, and other
basic components of biological monitoring, including tracking of
observed animals or groups of animals such that repeat sound exposures
may be attributed to individuals (to the extent possible).
<bullet> All PSOs must have no other project-related tasks while
conducting monitoring.
<bullet> PSOs shall be placed at the best vantage point(s)
practicable to monitor for marine mammals and implement shutdown or
delay procedures when applicable through communication with the
equipment operator.
<bullet> Monitoring would be conducted 30 minutes before, during,
and 30 minutes after drilling and pile driving/extraction activities.
PSOs would record all observations of marine mammals, regardless of
distance from the pile being driven, as well as the additional data
indicated below and in section 6 of the IHAs, if issued.
Hydroacoustic Monitoring--PSF proposes implementing in situ
acoustic monitoring efforts to measure SPLs from in-water activities.
PSF would collect and evaluate sound level data for a subset of
representative piles (minimum of two) for each installation or
extraction method and pile type PSF would submit a detailed acoustic
monitoring plan to NMFS for approval no later than 60 days in advance
of the start of in-water work for approval of proposed methodologies.
At a minimum, the methodology would include a stationary hydrophone
system with the ability to measure SPLs placed in accordance with NMFS'
most recent recommendations for the collection of source levels.
Monitoring would occur at 33 ft (10 m) from the noise; at a location
within the Level A (AUD INJ onset) zones; and occasionally near the
predicted harassment zones for Level B (Behavioral) harassment. The
resulting data set would be analyzed to examine and confirm SPLs and
rates of transmission loss for each separate in- water construction
activity. With NMFS' concurrence, these metrics would be used to
recalculate the limits of the shutdown, Level A (AUD INJ onset), and
Level B (behavioral) disturbance zones, and to make corresponding
adjustments in marine mammal monitoring of these zones.
Environmental data would be collected, including but not limited
to, the following: wind speed and direction, air temperature, humidity,
surface water temperature, water depth, wave height, weather
conditions, and other factors that could contribute to influencing the
airborne and underwater sound levels (e.g., aircraft, boats, etc.). The
chief inspector would supply the acoustics specialist with the
substrate composition, hammer or drill model and size, hammer or drill
energy settings and any changes to those settings during acoustic
monitoring, depth of the pile being driven or steel caisson being
excavated and strikes per second during DTH driving.
For acoustically monitored piles, data from the monitoring
locations would be post-processed to obtain the following sound
measures:
<bullet> Mean, median, minimum, and maximum RMS pressure level in
[dB re 1 mPa];
<bullet> Mean, median, minimum, and maximum single strike SEL in
[dB re mPa\2\s];
<bullet> Cumulative SEL as defined by the mean single strike SEL +
10*log10 (number of hammer strikes) in [dB re mPa\2\s]; and
<bullet> A frequency spectrum (pressure spectral density) in dB re
millipascals squared per hertz ((mPa\2\/Hz) based on the average of up
to eight successive strikes with similar sound. Spectral resolution
would be 1 Hz, and the spectrum would cover nominal range from 7 Hz to
20 kHz.
Reporting--PSF must submit a draft marine mammal monitoring report
to NMFS within 90 days after the completion of pile driving activities,
or 60 days prior to the requested issuance of any future IHAs for the
project, or other projects at the same location, whichever comes first.
A final report must be prepared and submitted within 30 calendar days
of 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 shall be considered final. The marine

[[Page 16921]]

mammal report would include an overall description of work completed, a
narrative regarding marine mammal sightings, and associated PSO data
sheets and/or raw sighting data. Specifically, the report must include:
<bullet> Dates and times (begin and end) of all marine mammal
monitoring;
<bullet> Construction activities occurring during each daily
observation period, including: (a) the number and type of piles that
were driven and the method (e.g., vibratory, DTH driving); and (b)
total duration of driving time for each pile (vibratory driving, DTH
driving);
<bullet> PSO locations during marine mammal monitoring; and
<bullet> Environmental conditions during monitoring periods (at the
beginning and end of a PSO shift and whenever conditions change
significantly), including Beaufort sea state and any other relevant
weather conditions, including cloud cover, fog, sun glare, and overall
visibility to the horizon, and estimated observable distance.
Upon observation of a marine mammal, the following information must
be reported:
<bullet> Name of PSO who sighted the animal(s) and PSO location and
activity at the time of the sighting;
<bullet> Time of the sighting;
<bullet> 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;
<bullet> Distance and bearing of each observed marine mammal
relative to the pile being driven or removed for each sighting;
<bullet> Estimated number of animals (min/max/best estimate);
<bullet> Estimated number of animals by cohort (e.g., adults,
juveniles, neonates, group composition, etc.);
<bullet> Animal's closest point of approach and estimated time
spent within the harassment zone(s);
<bullet> 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);
description of any actions implemented in response to the sighting
(e.g., delays, shutdown), time and location of the action;
<bullet> Number of marine mammals detected within the harassment
zones, by species; and
<bullet> Summary 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.
Hydroacoustic Monitoring Report--The hydroacoustic monitoring
report must, at minimum, include the following:
<bullet> Hydrophone equipment and methods, recording device,
sampling rate, distance (m) from the pile where recordings were made;
depth of water and recordings device(s);
<bullet> Type and size of pile being driven, substrate type, method
of driving during recordings (e.g., hammer model and energy), and total
pile driving duration;
<bullet> Whether a sound attenuation device is used and, if so, a
detailed description of the device used and the duration of its use per
pile;
<bullet> For vibratory driving/extraction (per pile): Duration of
driving per pile; mean, median, and maximum sound levels (dB re: 1
mPa): SPLrms, SEL<INF>cum</INF> (and timeframe over which the sound is
averaged).
<bullet> One-third octave band spectrum and power spectral density
plot; and
<bullet> Transmission loss values for each pile size and type and
installation method, when appropriate.
Reporting Injured or Dead Marine Mammals--In the event that
personnel involved in the construction activities discover an injured
or dead marine mammal, PSF must report the incident to the Office of
Protected Resources, NMFS (<a href="/cdn-cgi/l/email-protection#b0e0e29ef9e4e09efddfded9c4dfc2d9ded7e2d5c0dfc2c4c3f0dedfd1d19ed7dfc6"><span class="__cf_email__" data-cfemail="b7e7e599fee3e799fad8d9dec3d8c5ded9d0e5d2c7d8c5c3c4f7d9d8d6d699d0d8c1">[email&#160;protected]</span></a>) and to
the West Coast regional stranding network (866-767-6114) as soon as
feasible. If the death or injury was clearly caused by the specified
activity, PSF would immediately cease the specified activities until
NMFS is able to review the circumstances of the incident and determine
what, if any, additional measures are appropriate to ensure compliance
with the terms of the IHA. PSF would not resume their activities until
notified by NMFS. The report would include the following information:
<bullet> Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
<bullet> Species identification (if known) or description of the
animal(s) involved;
<bullet> Condition of the animal(s) (including carcass condition if
the animal is dead);
<bullet> Observed behaviors of the animal(s), if alive;
<bullet> If available, photographs or video footage of the
animal(s); and
<bullet> General circumstances under which the animal was
discovered.

Negligible Impact Analysis and Determination

NMFS has defined negligible impact as an impact resulting from the
specified activity that cannot be reasonably expected to, and is not
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough
information on which to base an impact determination. In addition to
considering estimates of the number of marine mammals that might be
``taken'' through harassment, NMFS considers other factors, such as the
likely nature of any impacts or responses (e.g., intensity, duration),
the context of any impacts or responses (e.g., critical reproductive
time or location, foraging impacts affecting energetics), as well as
effects on habitat, and the likely effectiveness of the mitigation. We
also assess the number, intensity, and context of estimated takes by
evaluating this information relative to population status. Consistent
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338,
September 29, 1989), the impacts from other past and ongoing
anthropogenic activities are incorporated into this analysis via their
impacts on the baseline (e.g., as reflected in the regulatory status of
the species, population size and growth rate where known, ongoing
sources of human-caused mortality, or ambient noise levels).
To avoid repetition, the discussion of our analysis applies to all
the species listed in table 3, given that the anticipated effects of
this activity on these different marine mammal stocks are expected to
be similar. There is little information about the nature or severity of
the impacts, or the size, status, or structure of any of these species
or stocks that would lead to a different analysis for this activity.
Level A harassment is extremely unlikely given the small size of
the Level A harassment isopleths and the required mitigation measures
designed to minimize the possibility of injury to marine mammals. No
serious injury or mortality is anticipated given the nature of the
activity.
Pile driving activities have the potential to disturb or displace
marine mammals. Specifically, the project activities may result in
take, in the form of Level B harassment from underwater sounds
generated from vibratory pile

[[Page 16922]]

driving and DTH driving activities. Potential takes could occur if
individuals move into the ensonified zones when these activities are
underway.
The takes by Level B harassment would be due to potential
behavioral disturbances. The potential for harassment is minimized
through construction methods and the implementation of planned
mitigation strategies (see Proposed Mitigation section).
Behavioral responses of marine mammals to vibratory pile driving
and DTH driving at the project site, if any, are expected to be mild
and temporary. Marine mammals within the Level B harassment zone may
not show any visual cues they are disturbed by activities or could
become alert, avoid the area, leave the area, or display other mild
responses that are not observable such as changes in vocalization
patterns. Given the short duration of noise-generating activities per
day and that pile driving and extraction would occur over approximately
32 days during a 46-day period, any harassment would be temporary.
There are no other overlapping areas or times of known biological
importance for any of the affected species. Take would occur within a
limited, confined area of each stock's range. Further, the numbers of
take proposed to be authorized are extremely small when compared to
stock abundance.
No marine mammal stocks for which incidental take authorization is
proposed are listed as threatened or endangered under the ESA. Only one
stock, the Eastern North Pacific Stock of the northern fur seal, is
listed as depleted under the MMPA. However, we do not expect the
proposed authorized take included in this action to affect the stock.
No injury or mortality is proposed for authorization, take by Level B
harassment is limited (two takes over the duration of the project), and
the proposed action should have no effect on the reproduction of this
species. In addition, the two authorized takes for the northern fur
seal include both the depleted Eastern North Pacific Stock and the
California stock, which is not depleted.
The relatively low marine mammal occurrences in the area, shutdown
zones, and planned monitoring make injury of marine mammals unlikely.
The shutdown zones would be thoroughly monitored before the pile
driving activities begin, and activities would be postponed if a marine
mammal is sighted within the shutdown zone. There is a high likelihood
that marine mammals would be detected by trained observers under
environmental conditions described for the project. Limiting pile
driving activities to daylight hours would also increase detectability
of marine mammals in the area. Therefore, the mitigation and monitoring
measures are expected to eliminate the potential for injury and Level A
harassment as well as reduce the amount and intensity of Level B
behavioral harassment. Furthermore, the pile driving activities
analyzed here are similar to, or less impactful than, numerous
construction activities conducted in other similar locations which have
occurred with no reported injuries or mortality to marine mammals, and
no known long-term adverse consequences from behavioral harassment.
The project is not expected to have significant adverse effects on
marine mammal habitat. There are no known BIA or ESA-designated
critical habitat within the project area, and the activities would not
permanently modify existing marine mammal habitat. 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
authorized;
<bullet> The specified activities and associated ensonified areas
are very small relative to the overall habitat ranges of all species;
<bullet> The project area does not overlap known BIAs or ESA-
designated critical habitat;
<bullet> The lack of anticipated significant or long-term effects
or marine mammal habitat; and
<bullet> The presumed efficacy of the mitigation measures in
reducing 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 sections 101(a)(5)(A) and (D) of the MMPA for
specified activities other than military readiness activities. The MMPA
does not define small numbers and so, in practice, where estimated
numbers are available, NMFS compares the number of individuals taken to
the most appropriate estimation of abundance of the relevant species or
stock in our determination of whether an authorization is limited to
small numbers of marine mammals. When the predicted number of
individuals to be taken is fewer than one-third of the species or stock
abundance, the take is considered to be of small numbers (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.
The instances of take NMFS proposes to authorize are below one-
third of the estimated stock abundance for all impacted stocks (table
7). In fact, take of individuals is 2 percent or less of the abundance
for all affected stocks. Indeed, even if each take NMFS proposes to
authorize occurred to a new individual, the number of animals would be
considered small relative to the size of the relevant stocks or
populations. Furthermore, the takes proposed for authorization would be
limited to individuals occurring local to PSF's construction
activities, an area that represents a small portion of the range for
any of the eight species considered here. Thus, the likelihood that
each take would occur to a new individual is low and, while some
individuals may return multiple times in a day, PSOs would count them
as separate takes if the individuals are not identifiable.
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, with no species take exceeding
2 percent of the best available population abundance estimate.

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

[[Page 16923]]

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 IHAs, NMFS consults internally whenever
we propose to authorize take for endangered or threatened 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 PSF for conducting pile driving activities in SFB,
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. 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: March 31, 2026.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2026-06484 Filed 4-2-26; 8:45 am]
BILLING CODE 3510-22-P

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