Notice2025-23894
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Alaska Department of Transportation and Public Facilities' Cold Bay Ferry Terminal Reconstruction Project in Cold Bay, Alaska
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
December 29, 2025
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has received a request from the Alaska Department of Transportation and Public Facilities (ADOT&PF) for authorization to take marine mammals incidental to the Cold Bay Ferry Terminal Reconstruction Project in Cold Bay, Alaska. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue an incidental harassment authorization (IHA) to incidentally take marine mammals during the specified activities. NMFS is also requesting comments on a possible one-time, 1-year renewal that could be issued under certain circumstances and if all requirements are met, as described in Request for Public Comments at the end of this notice. NMFS will consider public comments prior to making any final decision on the issuance of the requested MMPA authorization and agency responses will be summarized in the final notice of our decision.
Full Text
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<title>Federal Register, Volume 90 Issue 245 (Monday, December 29, 2025)</title>
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[Federal Register Volume 90, Number 245 (Monday, December 29, 2025)]
[Notices]
[Pages 60653-60682]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-23894]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XF215]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to the Alaska Department of
Transportation and Public Facilities' Cold Bay Ferry Terminal
Reconstruction Project in Cold Bay, Alaska
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 Alaska Department of
Transportation and Public Facilities (ADOT&PF) for authorization to
take marine mammals incidental to the Cold Bay Ferry Terminal
Reconstruction Project in Cold Bay, Alaska. Pursuant to the Marine
Mammal Protection Act (MMPA), NMFS is requesting comments on its
proposal to issue an incidental harassment authorization (IHA) to
incidentally take marine mammals during the specified activities. NMFS
is also requesting comments on a possible one-time, 1-year renewal that
could be issued under certain circumstances and if all requirements are
met, as described in Request for Public Comments at the end of this
notice. NMFS will consider public comments prior to making any final
decision on the issuance of the requested MMPA authorization and agency
responses will be summarized in the final notice of our decision.
DATES: Comments and information must be received no later than January
28, 2026.
ADDRESSES: Comments should be addressed to 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#753c21255b251a01191a161e351b1a14145b121a03"><span class="__cf_email__" data-cfemail="f3baa7a3dda39c879f9c9098b39d9c9292dd949c85">[email protected]</span></a>.
Electronic copies of the application and supporting documents, as well
as a list of the references cited in this document, may be obtained
online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>. In
case of problems accessing these documents, please call the contact
listed below.
Instructions: NMFS is not responsible for comments sent by any
other method, to any other address or individual, or received after the
end of the comment period. Comments, including all attachments, must
not exceed a 25-megabyte file size. All comments received are a part of
the public record and will generally be posted online at <a href="https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act</a> without change. All personal identifying
information (e.g., name, address) voluntarily submitted by the
commenter may be publicly accessible. Do not submit confidential
business information or otherwise sensitive or protected information.
FOR FURTHER INFORMATION CONTACT: Kelsey Potlock, 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 and other ``means of effecting the least practicable adverse
impact'' on the affected species or stocks and their habitat, paying
particular attention to rookeries, mating grounds, and areas of similar
significance, and on the availability of the species or stocks for
taking for certain subsistence uses (collectively 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
and can be found in section 3 of the MMPA (16 U.S.C. 1362) and NMFS
regulations at 50 CFR 216.103.
National Environmental Policy Act
To comply with the National Environmental Policy Act of 1969 (NEPA;
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A,
NMFS must review our proposed action (i.e., the issuance of an IHA)
with respect to potential impacts on the human environment.
This action is consistent with categories of activities identified
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or
mortality) of the Companion Manual for NAO 216-6A, which do not
individually or cumulatively have the potential for significant impacts
on the quality of the human environment and for which we have not
identified any extraordinary circumstances that would preclude this
categorical exclusion. Accordingly, NMFS has preliminarily determined
that the issuance of the proposed IHA qualifies to be categorically
excluded from further NEPA review.
Summary of Request
On July 30, 2025, NMFS received a request from ADOT&PF for an IHA
to take marine mammals incidental to pile-driving activities for the
Cold Bay Ferry Terminal Reconstruction Project in Cold Bay, Alaska.
Following NMFS' review of the application, ADOT&PF submitted revised
versions on November 14, 2025, November 21, 2025, December 11, 2025,
and December 19, 2025. The application was deemed adequate and complete
on
[[Page 60654]]
December 12, 2025. ADOT&PF's request is for take of six species (eight
stocks) of marine mammals by Level B harassment and, for a subset of
these species, Level A harassment. Neither ADOT&PF nor NMFS expect
serious injury or mortality to result from this activity and,
therefore, an IHA is appropriate.
NMFS previously issued several IHAs to ADOT&PF for similar coastal
construction work between 2018 and 2025 (e.g., 83 FR 5063, February 5,
2018; 83 FR 29749, June 26, 2018; July 19, 2023, 88 FR 46145; 90 FR
24385, June 10, 2025; 90 FR 38134, August 7, 2025). To date, ADOT&PF
has complied with all the requirements (e.g., mitigation, monitoring,
and reporting) of the previous IHAs.
Description of Proposed Activity
Overview
ADOT&PF has requested an IHA to take marine mammals incidental to
in-water construction activities. The original Cold Bay Dock was
constructed by the State of Alaska in 1978, expanded in 1993, and then
refurbished in 2015. Currently, the structure is nearing the end of
serviceable life and is at risk of failing, which would be detrimental
for the communities that so heavily rely on this infrastructure. At
present, use restrictions are currently in place that limit axel loads
and gross vehicle weights until the dock can be fully replaced. Given
the receipt of additional funding, ADOT&PF plans to replace the aging
public dock to improve accessibility; support commercial, subsistence,
and recreation users; continue uninterrupted ferry service; secure
cargo delivery and bulk materials offloading; ensure public safety; and
safeguard vessel moorage. Additionally, this project would maintain
access to essential services for surrounding communities that rely on
Cold Bay as a hub for fuel, goods, cargo, and potable drinking water.
The new dock would be designed and built to accommodate commercial use,
freight and fuel transportation, private vessel use, and public uses
like emergency medical services and public transportation through the
Alaska Marine Highway System (AMHS).
Given the proposed use of vibratory and impact pile driving to
remove and install piles, there is potential of the take of marine
mammals by Level B harassment and, for a subset of the species, Level A
harassment. No serious injury and/or mortality is expected or proposed
for this project.
Dates and Duration
ADOT&PF has been awarded funds by the U.S. Department of
Transportation's (DOT) Maritime Administration (MARAD) under the Port
Infrastructure Development Program (via the Infrastructure Investment
and Jobs Act (Pub. L. 117-58, November 15, 2021)), a discretionary
grant program awarded on a competitive basis to projects that improve
the safety, efficiency, or reliability of the movement of goods into,
out of, around, or within a port (<a href="https://www.maritime.dot.gov/PIDPgrants">https://www.maritime.dot.gov/PIDPgrants</a>). These grants are awarded to improve port and related
freight infrastructure to meet the nation's freight transport needs and
ensure that port infrastructure can keep up with the growth of freight
volume as it continues to increase.
ADOT&PF intends to begin their project on May 1, 2028, and continue
for one year through April 30, 2029. The entire project is anticipated
to consist of 18 months of activities (in-water and on-shore), whereas
the in-water activities (i.e., pile driving) are expected to occur for
12 months, consisting of 231 (not necessarily consecutive) days
requiring 10 to 12 hours of activities per day, following the general
schedule of events described in table 1. In-water pile driving is
expected to occur near-continuously for the first 7 months (May through
November with an estimated driving duration of 165 days), which would
allow for the installation of the trestle and dock piles. For the next
3 months (December through February), limited in-water pile driving is
expected to occur as the dock superstructure is completed. Likely
activities during these months include fender and dolphin installation
(estimated 21 days of in-water pile driving). After this is completed,
demolition activities on the existing dock would be performed,
estimated to require non-continuous in-water pile driving over
approximately 45 days within a 2-month period (March to April).
Table 1--Anticipated Schedule of Activities
------------------------------------------------------------------------
Phase Tasks
------------------------------------------------------------------------
Mobilize to site.................. The contractor would mobilize the
necessary equipment and personnel.
Install Trestle \a\............... <bullet> Install temporary work
trestle and pile driving templates.
<bullet> Drive and proof foundation
pile.
<bullet> Remove templates and
template support piles.
<bullet> Install precast concrete
caps.
<bullet> Set trestle superstructure.
<bullet> Grout deck joints and place
and cast-in-place concrete in
closure pours.
Install Dock...................... <bullet> Install temporary work
trestle and pile driving templates.
<bullet> Drive and proof foundation
pile.
<bullet> Remove templates and
template support piles.
<bullet> Install precast concrete
caps.
<bullet> Set precast concrete deck
panels.
<bullet> Grout deck joints and place
and cast-in-place concrete in
closure pours.
<bullet> Install on-dock
appurtenances (bullrails, ladders,
cleats, bollards, etc.).
Install Dolphins.................. <bullet> Install pile driving
template.
<bullet> Drive and proof foundation
piles.
<bullet> Remove template and extract
template support piles.
<bullet> Install pile caps.
<bullet> Set catwalks.
Install Fendering................. <bullet> Install pile driving
template.
<bullet> Drive and proof fender
piles.
<bullet> Install fender panels.
Utility Installation.............. <bullet> Install onshore utility
service as required.
<bullet> Install trestle supported
service lines.
<bullet> Install dock-mounted
headers and service connections.
[[Page 60655]]
Existing Dock Demolition.......... <bullet> Remove appurtenances and
utilities located on the dock and
trestle.
<bullet> Demolish and remove
existing superstructure.
<bullet> Extract existing piles.
Demobilization.................... <bullet> All demolished existing
materials staged on the uplands
would be removed from the site.
------------------------------------------------------------------------
\a\ Installation of the trestle would likely progress from shore,
seaward to the dock location.
However, project delays may occur due to a number of factors,
including other permitting requirements, availability of equipment and/
or materials, weather-related delays, equipment maintenance and/or
repair, transit to and from ports to survey locations, and other
contingencies. Therefore, the analysis herein represents a best
estimate of activities and timeframe and does not imply limits to
activities in a given month.
Specific Geographic Region
The proposed project is located within southwestern tip of the
Alaska Peninsula (Township 57 South, Range 89 West of the Seward
Meridian; U.S. Geological Survey Quadrangle COLD BAY A-3) (see figure
1). Situated at approximately Latitude 55[deg]12' N, Longitude
162[deg]42' W, the city encompasses 53.41 square miles (mi\2\; 138
square kilometers (km\2\)) of land and 14.64 mi\2\ (38 km\2\) of water.
Per the United States 2020 census, approximately 50 people live within
Cold Bay (U.S. Census Bureau, 2025). The City of Cold Bay sits
approximately 138 feet (ft; 42 meters (m)) above mean sea level.
Geologically, the region is part of the Aleutian arc, a highly
active segment of the Pacific Ring of Fire. The landscape is dominated
by prominent volcanic features, including Frosty Peak and Mount Simeon
nearby, with the more distant and active Pavlof and Shishaldin
Volcanoes. The region contains complex geology, which is shaped by a
long history of volcanic, glacial, and tectonic processes. The
immediate topography of Cold Bay is characterized by a rolling,
treeless tundra dotted with numerous lakes and swamps. This landscape
is part of a broad coastal lowland on the northern side of the
peninsula, which generally lies less than 100 ft (30.5 m) above sea
level. Cold Bay's most defining physical characteristic is its location
on a narrow isthmus separating two great marine ecosystems: the cold,
shallow, and enclosed Bering Sea to the north, and the deep, warmer,
and open North Pacific Ocean to the south. This unique geographical
position creates a convergence zone of powerful ocean currents,
temperature gradients, and salinities, resulting in one of the most
biologically productive marine environments on the planet. The City of
Cold Bay lies on the shore of Cold Bay, a large Pacific Ocean
embayment, and is adjacent to the Izembek Lagoon (a shallow, 30-mi (48-
km) coastal ecosystem that contains one of the world's largest beds of
eelgrass (Zostera marina) (Rice and Hogan, 1995)) on the Bering Sea
side.
Cold Bay serves as a primary commercial and transportation hub for
the Alaska Peninsula and a gateway to the Aleutian Islands. It is the
headquarters for the Izembek National Wildlife Refuge (see U.S. Fish
and Wildlife Service (2025a)) and a key logistics and support center
for the commercial fishing industry in the region. The city's primary
infrastructure includes the Port of Cold Bay, which serves the state
ferry system, and the Cold Bay Airport, a critical regional hub and
emergency diversion airport for trans-Pacific flights with one of the
longest runways in Alaska.
BILLING CODE 3510-22-P
[[Page 60656]]
[GRAPHIC] [TIFF OMITTED] TN29DE25.001
BILLING CODE 3510-22-C
Detailed Description of the Specified Activity
ADOT&PF has proposed to remove components of the existing and aging
structure and install new components to better serve the Cold Bay
community. The existing Cold Bay Dock is a critical facility for the
community and surrounding areas, serving as the sole location for the
sea-based delivery of fuel, goods, cargo, and potable drinking water.
Per the 2022-2027 Alaska Statewide Comprehensive Economic Development
Strategy, officials have highlighted that coastal communities, such as
Cold Bay, depend on efficient and well-functioning waterfront
infrastructure to receive goods. Currently, the dock is nearing the end
of its serviceable life and is at risk of failing. Use restrictions are
in place that limit axle loads and gross vehicle weights until the dock
can be replaced. The new dock would be designed and built to
accommodate a variety of uses, including commercial use, freight and
fuel transportation, private vessel uses, and public uses like
emergency medical services and public transportation through the AMHS.
The project would be completed in stages, depending on the
structure being constructed, including development of a trestle and
abutment, a dock, dolphin piles, and then demolition/removal of old
structures (i.e., trestle, dock, dolphins, and fenders). For all in-
water work, the project would require the mobilization of barges and
support vessels, all of which are likely to come from different
communities within Alaska. The number of vessels is not currently known
as the construction contractor has not been chosen but all support
vessels, support barges, material barges, and construction barges would
follow known routes when transiting to the construction site.
To develop the new infrastructure, a 360 ft (109.7 m) by 54 ft
(16.5 m) pile-supported dock with adjacent mooring dolphins would be
developed. The applicant would also develop fendering (both heavy-duty
on the primary face and light-duty fenders on opposite faces) around
the new dock. All access to the dock would be made available by a 22 ft
(6.7 m) by 1,800 ft (548.6 m) pile-supported trestle. The trestle and
dock would be constructed using pre-cast concrete elements, supported
by pile-driven steel foundation piles. For the trestle and dock
construction, vibratory pile driving would be used whenever feasible,
but impact pile driving likely would be needed to proof piles. The
trestle would be constructed using prefabricated sections supported by
pile bents. A pile-supported abutment would support the nearshore end
of the trestle. All pier-support piles would be installed first,
followed by the pre-cast concrete caps, and then the superstructure
would be set. The trestle piles would require both vibratory and impact
pile driving methods, to install and (in some cases remove) a total of
208 temporary piles, 261 new permanent piles, and 322 existing piles.
No simultaneous pile driving is planned. Pile specifics for the dock
trestle are described here:
<bullet> Vibratory and impact installation of 113 permanent trestle
support piles (36-inch (in); 91.44-centimeter (cm) pipe piles);
<bullet> Vibratory and impact installation and vibratory removal of
150 temporary trestle piles (24-in (60.96-cm) to 36-in (91.44-cm) pipe
or H-piles);
<bullet> Vibratory and impact installation of 80 permanent dock
support piles (36-in (91.44-cm) pipe piles);
[[Page 60657]]
<bullet> Vibratory and impact installation and vibratory removal of
50 temporary dock piles (24-in (60.96-cm) to 36-in (91.44-cm) pipe
piles);
<bullet> Vibratory installation of 20 fender piles (30-in (76.2-cm)
pipe piles); and
<bullet> Vibratory installation of 40 fender piles (24-in (60.96-
cm) pipe piles).
The construction of the dock would proceed similarly to trestle
construction, where the dock piles would be installed using both
vibratory and impact methods. All permanent piles would be driven at
their pre-planned locations, which would be followed by a setting of
pre-cast concrete caps and structural panel systems that make up the
superstructure of the dock. Piles would be set and driven using a crane
either located on a barge or working on a temporary structure. Fenders
(using two fender piles) would be installed along the offshore dock
face to protect the dock from moored vessels. Single pile fenders would
be installed on the shoreward dock face. Installation would only be by
vibratory pile driving. Lastly, various dock appurtenances and
utilities would be installed, although these would not necessitate any
pile driving. These would serve the current and future needs of the
dock and consist of water, electrical, and fuel piping, such as the
installation of utility lines and diesel/gasoline fuel lines, a
portable water supply line, and new lighting along the new trestle and
dock.
Upon completion of the dock and trestle structures, the applicant
would install two dolphins at opposite ends, using four temporary pile
templates initially driven for the installation of each dolphin and
removed following completion. Temporary piles would be installed using
vibratory pile driving, and impact pile driving would be used to proof
the vertical load supporting piles or in the case of obstructions. All
temporary piles would be extracted using vibratory pile driving. Pile
specifics for the dolphins are described here:
<bullet> Vibratory and impact installation of eight permanent
dolphin piles (36-in (76.2-cm) pipe piles); and
<bullet> Vibratory installation and removal of eight temporary
dolphin piles (24-in (60.96-cm) to 36-in (76.2-cm) pipe piles).
During all the construction, demolition and removal of the existing
older dock structure would be coordinated with the installation of the
new structure to minimize any potential disturbance to users of the
facility. Trestle demolition would not be performed until the new
trestle is completed. Demolition for the dock and trestle would include
removal of the concrete superstructure, support piles, fenders and all
dock utilities and appurtenances. Removal of the superstructure would
be accomplished by first saw-cutting and pulling the concrete deck
panels. The existing pile caps would then be cut, while the supporting
piles would be cut at the pile/cap interface and then the caps would be
lifted and removed. Pile extraction would proceed following the removal
of the superstructure. All piles would be removed using vibratory pile
driving equipment or cut off at the mudline. Piles removed during
demolition would include:
<bullet> 180 trestle piles (16-in (40.64-cm) pipe piles);
<bullet> 24 dock piles (16-in (40.64-cm) pipe piles);
<bullet> 65 dock piles (26-in (66-cm) pipe piles);
<bullet> 9 dolphin piles (16-in (40.64-cm) pipe piles);
<bullet> 13 fender piles (20-in (50.8-cm) pipe piles); and
<bullet> 31 fender piles (16-in (40.64-cm) timber piles).
Upon completion, refuse and excess materials from the project would
be either reclaimed, recycled, or disposed of and all project equipment
would be demobilized to the port of origin.
A summary of all piles planned to be installed or removed and their
specific attributes are included in table 2 below.
Table 2--Pile Parameters for the Proposed Cold Bay Ferry Terminal Reconstruction Project
----------------------------------------------------------------------------------------------------------------
Installation and/or Number of
Specific activity Pile information Pile material removal approach piles
----------------------------------------------------------------------------------------------------------------
Permanent Removal Activities
----------------------------------------------------------------------------------------------------------------
Trestle removal.................. 16-inch pipe pile... Steel.................. Vibratory.......... 180
Dock removal..................... 16-inch pipe pile... Steel.................. Vibratory.......... 24
Dock removal..................... 26-inch pipe pile... Steel.................. Vibratory.......... 65
Dolphin removal.................. 16-inch pipe pile... Steel.................. Vibratory.......... 9
Fender removal................... 20-inch pipe pile... Steel.................. Vibratory.......... 13
Fender removal................... 16-inch pipe pile... Timber................. Vibratory.......... 31
----------
Removal total................ .................... ....................... ................... 322
----------------------------------------------------------------------------------------------------------------
Temporary installation and subsequent removal
----------------------------------------------------------------------------------------------------------------
Temporary trestle pile........... 24-inch to 36-inch Steel.................. Vibratory 240
pipe pile or H-pile. installation,
impact
installation,
vibratory removal.
Temporary dock pile.............. 24-inch to 36-inch Steel.................. Vibratory 50
pipe pile. installation,
impact
installation,
vibratory removal.
Temporary dolphin pile........... 24-inch to 36-inch Steel.................. Vibratory 8
pipe pile. installation,
impact
installation,
vibratory removal.
----------
Temporary installation and .................... ....................... ................... 298
removal total.
----------------------------------------------------------------------------------------------------------------
Permanent Installation Activities
----------------------------------------------------------------------------------------------------------------
Trestle support piles............ 36-inch pipe piles.. Steel.................. Vibratory and 113
impact
installation.
Dock support pile................ 36-inch pipe pile... Steel.................. Vibratory and 80
impact
installation.
Fender pile...................... 30-inch pipe pile... Steel.................. Vibratory 20
installation.
Fender pile...................... 24-inch pipe pile... Steel.................. Vibratory 40
installation.
Dolphin pile..................... 36-inch pipe pile... Steel.................. Vibratory and 8
impact
installation.
----------
[[Page 60658]]
Installation total........... .................... ....................... ................... 269
----------
In-water total........... .................... ....................... ................... 889
----------------------------------------------------------------------------------------------------------------
Proposed mitigation, monitoring, and reporting measures are
described in detail later in this document (please see Proposed
Mitigation and Proposed Monitoring and Reporting).
Description of Marine Mammals in the Area of Specified Activities
Sections 3 and 4 of the application summarize available information
regarding status and trends, distribution and habitat preferences, and
behavior and life history of the potentially affected species. NMFS
fully considered all of this information, and we refer the reader to
these descriptions, instead of reprinting the information. Additional
information regarding population trends and threats may be found in
NMFS' Stock Assessment Reports (SARs; <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>) and
more general information about these species (e.g., physical and
behavioral descriptions) may be found on NMFS' website (<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>).
Table 3 lists all species or stocks for which take is expected and
proposed to be authorized for this activity and summarizes information
related to the population or stock, including regulatory status under
the MMPA and Endangered Species Act (ESA) and potential biological
removal (PBR), where known. PBR is defined by the MMPA as the maximum
number of animals, not including natural mortalities, that may be
removed from a marine mammal stock while allowing that stock to reach
or maintain its optimum sustainable population (as described in NMFS'
SARs). While no serious injury or mortality is anticipated or proposed
to be authorized here, PBR and annual serious injury and mortality (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' Alaska SARs. All values presented in table 3 are the most recent
available at the time of publication (including from the draft 2024
SARs) and are available online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>.
Table 3--Species \a\ With Estimated Take From the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
ESA/MMPA status; Stock abundance (CV;
Common name Scientific name Stock strategic (Y/N) Nmin; most recent PBR Annual M/
\b\ abundance survey) \c\ SI \d\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Artiodactyla--Infraorder Cetacea--Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Eschrichtiidae:
Gray whale...................... Eschrichtius robustus.. Eastern North Pacific.. -, -, N 26,960 (0.05; 25,849; 801 131
2016).
Family Balaenopteridae (rorquals):
Humpback whale.................. Megaptera novaeangliae. Hawai[revaps]i......... -, -, N 11,278 (0.56; 7,265; 127 27.09
2020).
Mexico-North Pacific... T, D, Y N/A (N/A; N/A; 2006) UND 0.6
\e\.
Western North Pacific.. E, D, Y 1,084 (0.88; 1,007; 3.4 5.82
2022).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
Killer whale.................... Orcinus orca........... Eastern North Pacific -, -, N 587 (N/A; 587; 2012).. 5.9 0.8
Gulf of Alaska,
Aleutian Islands, and
Bering Sea Transient.
Family Phocoenidae (porpoises):
Harbor porpoise................. Phocoena phocoena...... Gulf of Alaska......... -, -, Y 31,046 (0.21; N/A; UND 72
1998).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order--Carnivora--Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
sea lions):
Steller sea lion................ Eumetopias jubatus..... Western................ E, D, Y 49,837 (N/A; 49,837; 299 267
2023) \f\.
Family Phocidae (earless seals):
Harbor seal..................... Phoca vitulina......... Cook Inlet/Shelikof -, -, N 28,411 (N/A; 26,907; 807 107
Strait. 2018).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ 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>).
\b\ Endangered Species Act (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 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.
[[Page 60659]]
\c\ NMFS marine mammal stock assessment reports 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> assessments. CV is the coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, a CV is not applicable. N/A indicates
data are unknown. UND (undetermined) PBR indicates data are available to calculate a PBR level, but a determination has been made that calculating a
PBR level using those data is inappropriate (see the SAR for details).
\d\ 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 strikes). Annual M/SI often cannot be determined precisely and is sometimes presented as a minimum value or range. A CV
associated with estimated mortality due to commercial fisheries is presented in some cases.
\e\ Abundance estimates are currently considered unknown.
\f\ Nest is best estimate of counts, which have not been corrected for animals at sea during abundance surveys.
As indicated above, all six species (with eight managed stocks) in
table 3 temporally and spatially co-occur with the activity to the
degree that take is reasonably likely to occur.
For all marine mammal species, there are no known biologically
important areas (BIA) within the coastal site that ADOT&PF's proposed
activities would be expected to impact. For fin whales (Balaenoptera
physalus), gray whales, humpback whales, North Pacific right whales
(Eubalaena japonica), and sperm whales (Physeter macrocephalus), while
these have been sighted near Cold Bay historically or could be
encountered along anticipated vessel transit routes, these are not
expected within the Bay itself, where the construction would be
occurring and acoustic disturbance could occur, given its relatively
shallow depths. Furthermore, any feeding or migratory BIAs exist
outside of the project area in more offshore areas (Brower et al.,
2022). Given the inshore and sheltered nature of the project, NMFS does
not expect that any acoustic influence would transmit outside of Cold
Bay. Furthermore, the area where the proposed project would occur
represents a small portion of the available habitat for these species.
In addition, northern sea otters may (Enhydra lutris kenyonii) be
found in Cold Bay (Alaska Department of Fish and Game, 2025). However,
this species and its stocks are managed by the U.S. Fish and Wildlife
Service and are not considered further in this notice.
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 or hear over the same frequency range (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
~65 decibel (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 4.
Table 4--Marine Mammal Hearing Groups
[NMFS, 2024]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 36 kHz.
whales).
High-frequency (HF) cetaceans 150 Hz to 160 kHz.
(dolphins, toothed whales, beaked
whales, bottlenose whales).
Very High-frequency (VHF) cetaceans 200 Hz to 165 kHz.
(true porpoises, Kogia, river
dolphins, Cephalorhynchid,
Lagenorhynchus cruciger & L.
australis).
Phocid pinnipeds (PW) (underwater) 40 Hz to 90 kHz.
(true seals).
Otariid pinnipeds (OW) (underwater) 60 Hz to 68 kHz.
(sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
composite (i.e., all species within the group), where individual
species' hearing ranges may not be as broad. Generalized hearing range
chosen based on ~65 dB threshold from composite audiogram, previous
analysis in NMFS (2018), and/or data from Southall et al. (2007) and
Southall et al. (2019). Additionally, animals are able to detect very
loud sounds above and below that ``generalized'' hearing range.
Of the species potentially present in the action area, two are
considered low-frequency (LF) cetaceans (i.e., gray whales and humpback
whales), one is considered a high-frequency (HF) cetacean (i.e., killer
whale), one is considered a very high-frequency (VHF) cetacean (i.e.,
harbor porpoise), one is an otariid pinniped (i.e., Steller sea lion),
and one is a phocid pinniped (i.e., harbor seal).
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2024) for a review of available information.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section 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 that are expected to be taken by this activity. The
Negligible Impact Analysis and Determination section considers the
content of this section, the Estimated Take of Marine Mammals section,
and the Proposed Mitigation section, to draw conclusions regarding the
likely impacts of these activities on the reproductive success or
survivorship of individuals and whether those impacts are reasonably
expected to, or reasonably likely to, adversely affect the species or
stock through effects on annual rates of recruitment or survival.
Acoustic effects on marine mammals during the specified activity
are expected to potentially occur from impact and vibratory pile
installation and removal. The effects of underwater noise from
ADOT&PF's proposed activities have the potential to result in Level B
harassment of marine mammals in the action area and, for some species
as a result of certain activities, Level A harassment.
[[Page 60660]]
Overall, the proposed activities include the removal and
installation of old, temporary, and permanent piles in Cold Bay,
Alaska. There are a variety of types and degrees of effects to marine
mammals, prey species, and habitat that could occur as a result of the
project. Below we provide a brief description of the types of sound
sources that would be generated by the project, the general impacts
from these types of activities, and an analysis of the anticipated
impacts on marine mammals from the project, with consideration of the
proposed mitigation measures.
Description of Sound Sources for the Specified Activities
Activities associated with the project that have the potential to
incidentally take marine mammals though exposure to sound would include
impact pile driving for installation, and vibratory pile driving for
installation and removal. Impact hammers typically operate by
repeatedly dropping and/or pushing a heavy piston onto a pile to drive
the pile into the substrate. Sound generated by impact hammers is
impulsive, characterized by rapid rise times and high peak levels, a
potentially injurious combination (Hastings and Popper, 2005).
Vibratory hammers install piles by vibrating them and allowing the
weight of the hammer to push them into the substrate. Vibratory hammers
typically produce less sound (i.e., lower levels) than impact hammers.
Peak sound pressure levels (SPLs) may be 180 dB or greater but are
generally 10 to 20 dB lower than SPLs generated during impact pile
driving of the same-sized pile (Oestman et al., 2009; California
Department of Transportation (CALTRANS), 2015, 2020). Sounds produced
by vibratory hammers are non-impulsive; compared to sounds produced by
impact hammers, the rise time is slower, reducing the probability and
severity of injury, and the sound energy is distributed over more time
(Nedwell and Edwards, 2002; Carlson et al., 2005).
The likely or possible impacts of ADOT&PF's proposed activities on
marine mammals could involve both non-acoustic and acoustic stressors.
Potential non-acoustic stressors could result from the physical
presence of the equipment and personnel. However, given there are no
known pinniped haul-out sites in the vicinity of the project site,
visual and other non-acoustic stressors would be limited, and any
impacts to marine mammals are expected to primarily be acoustic in
nature. While there are known rookeries for Steller sea lions at
Clubbing Rocks North (57 km (35.4 mi) to the south), Clubbing Rocks
South (58 km (36 mi) to the south), and Pinnacle Rock (76 km (47.2 mi)
to the southeast), no Steller sea lion haulouts have been reported in
Cold Bay (Fritz et al., 2015). Additionally, while harbor seals are
known to haul out at the mouth of Kinzarof Lagoon, the mouth of the
Lagoon is approximately 8.35 km (5.2 mi) away the existing Cold Bay
dock and the largest isopleth for any in-air noises from construction
is 0.152 km (0.09 mi), meaning that any harbor seals near the Lagoon
would not be affected by in-air noises (table 5). Therefore, NMFS
considers take from in-air exposures to be unlikely, and it is not
considered further in this notice.
Table 5--Calculated Isopleths in Kilometers for Potential In-Air Sources \a\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Installation details Harbor seal Other pinnipeds
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source level
Structure Installation approach (dB) \a\ Isopleths (m) Isopleths (km) Isopleths (m) Isopleths (km)
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-in round steel........................ Vibratory.................. 95 27.0 0.0 8.5 0.0
Impact..................... 112 191.4 0.2 60.6 0.1
24-in round steel........................ Vibratory.................. 92 19.1 0.0 6.1 0.0
Impact..................... 110 152.0 0.2 48.1 0.0
16-in round steel........................ Vibratory.................. 87.5 11.4 0.0 3.6 0.0
Impact..................... 110 152.0 0.2 48.1 0.0
---------------------------------------------------------------------------------
Gravity fill............................. Vibratory.................. n/a
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Impulsive RMS Lmax (Unweighted), Non-Impulsive RMS Leq (Unweighted). All values are relative to 20 [mu]Pa and at 15 m (50 ft) from the pile.
Potential Effects of Underwater Sound on Marine Mammals
The introduction of anthropogenic noise into the aquatic
environment from impact and vibratory pile driving is the primary means
by which marine mammals may be harassed from ADOT&PF's specified
activity. Anthropogenic sounds cover a broad range of frequencies and
sound levels and can have a range of highly variable impacts on marine
life from none or minor to potentially severe responses depending on
received levels, duration of exposure, behavioral context, and various
other factors. Broadly, underwater sound from active acoustic sources,
such as those in the project, can potentially result in one or more of
the following: temporary or permanent hearing impairment, non-auditory
physical or physiological effects, behavioral disturbance, stress, and
masking (Richardson et al., 1995; Gordon et al., 2003; Nowacek et al.,
2007; Southall et al., 2007; G[ouml]tz et al., 2009).
We describe the more severe effects of certain non-auditory
physical or physiological effects only briefly as we do not expect that
use of impact and vibratory hammers are reasonably likely to result in
such effects (see below for further discussion). Potential effects from
impulsive sound sources can range in severity from effects such as
behavioral disturbance or tactile perception to physical discomfort,
slight injury of the internal organs and the auditory system, or
mortality (Yelverton et al., 1973). Non-auditory physiological effects
or injuries that theoretically might occur in marine mammals exposed to
high level underwater sound or as a secondary effect of extreme
behavioral reactions (e.g., change in dive profile as a result of an
avoidance reaction) caused by exposure to sound include neurological
effects, bubble formation, resonance effects, and other types of organ
or tissue damage (Cox et al., 2006; Southall et al., 2007; Zimmer and
Tyack, 2007; Tal et al., 2015). The proposed project activities
considered here do not involve the use of devices such as explosives or
mid-frequency tactical sonar that are associated with these types of
effects.
In general, animals exposed to natural or anthropogenic sound may
experience physical and psychological effects, ranging in magnitude
from none to severe (Southall et al., 2007, 2019). Exposure to
anthropogenic noise has the potential to result in auditory threshold
shifts and behavioral reactions (e.g., avoidance, temporary cessation
of foraging and vocalizing, changes in dive
[[Page 60661]]
behavior). It 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 degree of effect of an acoustic exposure on marine mammals is
dependent on several factors, including, but not limited to, sound type
(e.g., impulsive vs. non-impulsive), signal characteristics, the
species, age and sex class (e.g., adult male vs. mom with calf),
duration of exposure, the distance between the noise source and the
animal, received levels, behavioral state at time of exposure, and
previous history with exposure (Wartzok et al., 2004; Southall et al.,
2007). In general, sudden, high-intensity sounds can cause hearing
loss, as can longer exposures to lower-intensity sounds. Moreover, any
temporary or permanent loss of hearing, if it occurs at all, would
occur almost exclusively for noise within an animal's hearing range. We
describe below the specific manifestations of acoustic effects that may
occur based on the activities proposed by ADOT&PF.
Richardson et al. (1995) described zones of increasing intensity of
effect that might be expected to occur in relation to distance from a
source and assuming that the signal is within an animal's hearing
range. First (at the greatest distance) is the area within which the
acoustic signal would be audible (potentially perceived) to the animal
but not strong enough to elicit any overt behavioral or physiological
response. The next zone (closer to the receiving animal) corresponds
with the area where the signal is audible to the animal and of
sufficient intensity to elicit behavioral or physiological
responsiveness. The third is a zone within which, for signals of high
intensity, the received level is sufficient to potentially cause
discomfort or tissue damage to auditory or other systems. Overlaying
these zones to a certain extent is the area within which masking (i.e.,
when a sound interferes with or masks the ability of an animal to
detect a signal of interest that is above the absolute hearing
threshold) may occur; the masking zone may be highly variable in size.
Below, we provide additional detail regarding potential impacts on
marine mammals and their habitat from noise in general, starting with
hearing impairment, as well as from the specific activities ADOT&PF
plans to conduct, to the degree it is available.
Hearing Threshold Shifts-- NMFS defines a noise-induced threshold
shift (TS) as a change, usually an increase, in the threshold of
audibility at a specified frequency or portion of an individual's
hearing range above a previously established reference level (NMFS,
2018, 2024). The amount of threshold shift is customarily expressed in
dB. TS can be permanent or temporary. As described in NMFS (2018, 2024)
there are numerous factors to consider when examining the consequence
of TS, including, but not limited to, the signal temporal pattern
(e.g., impulsive or non-impulsive), likelihood an individual would be
exposed for a long enough duration or to a high enough level to induce
a TS, the magnitude of the TS, time to recovery (seconds to minutes or
hours to days), the frequency range of the exposure (i.e., spectral
content), the hearing frequency range of the exposed species relative
to the signal's frequency spectrum (i.e., how animal uses sound within
the frequency band of the signal; e.g., Kastelein et al., 2014), and
the overlap between the animal and the source (e.g., spatial, temporal,
and spectral).
Auditory Injury (AUD INJ)-- NMFS (2024) defines AUD INJ as damage
to the inner ear that can result in destruction of tissue, such as the
loss of cochlear neuron synapses or auditory neuropathy (Houser, 2021;
Finneran, 2024). AUD INJ may or may not result in a permanent threshold
shift (PTS). PTS is subsequently defined as a permanent, irreversible
increase in the threshold of audibility at a specified frequency or
portion of an individual's hearing range above a previously established
reference level (NMFS, 2024). PTS does not generally affect more than a
limited frequency range, and an animal that has incurred PTS has some
level of hearing loss at the relevant frequencies; typically, animals
with PTS or other AUD INJ are not functionally deaf (Au and Hastings,
2008; Finneran, 2016). Available data from humans and other terrestrial
mammals indicate that a 40-dB threshold shift approximates AUD INJ
onset (see Ward et al., 1958, 1959; Ward, 1960; Kryter et al., 1966;
Miller, 1974; Ahroon et al., 1996; Henderson et al., 2008). AUD INJ
levels for marine mammals are estimates, as with the exception of a
single study unintentionally inducing PTS in a harbor seal (Kastak et
al., 2008), there are no empirical data measuring AUD INJ in marine
mammals largely due to the fact that, for various ethical reasons,
experiments involving anthropogenic noise exposure at levels inducing
AUD INJ are not typically pursued or authorized (NMFS, 2024).
Temporary 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), and is not considered an AUD INJ. Based
on data from marine mammal TTS measurements (see Southall et al., 2007,
2019), a TTS of 6 dB is considered the minimum threshold shift clearly
larger than any day-to-day or session-to-session variation in a
subject's normal hearing ability (Finneran et al., 2000, 2002; Schlundt
et al., 2000). As described in Finneran (2015), marine mammal studies
have shown the amount of TTS increases with the 24-hour cumulative
sound exposure level (SEL<INF>24</INF>) in an accelerating fashion: at
low exposures with lower SEL<INF>24</INF>, the amount of TTS is
typically small and the growth curves have shallow slopes. At exposures
with higher SEL<INF>24</INF>, the growth curves become steeper and
approach linear relationships with the sound exposure level (SEL).
Depending on the degree (elevation of threshold in dB), duration
(i.e., recovery time), and frequency range of TTS, and the context in
which it is experienced, TTS can have effects on marine mammals ranging
from discountable to more impactful (similar to those discussed in
auditory masking, below). For example, a marine mammal may be able to
readily compensate for a brief, relatively small amount of TTS in a
non-critical frequency range that takes place during a time when the
animal is traveling through the open ocean, where ambient noise is
lower and there are not as many competing sounds present.
Alternatively, a larger amount and longer duration of TTS sustained
during time when communication is critical for successful mother/calf
interactions could have more severe impacts. We note that reduced
hearing sensitivity as a simple function of aging has been observed in
marine mammals, as well as humans and other taxa (Southall et al.,
2007), so we can infer that strategies exist for coping with this
condition to some degree, though likely not without cost.
Many studies have examined noise-induced hearing loss in marine
mammals (see Finneran (2015) and Southall et al. (2019) for summaries).
TTS is the mildest form of hearing impairment that can occur during
exposure to sound (Kryter, 2013). While experiencing TTS, the hearing
threshold rises, and a sound must be at a higher level in order to be
heard. In terrestrial and marine mammals, TTS can last from minutes or
hours to days (in cases of strong TTS). In many cases, hearing
sensitivity recovers rapidly after
[[Page 60662]]
exposure to the sound ends. For cetaceans, published data on the onset
of TTS are limited to captive bottlenose dolphin (Tursiops truncatus),
beluga whale (Delphinapterus leucas), harbor porpoise, and Yangtze
finless porpoise (Neophocoena asiaeorientalis) (Southall et al., 2019).
For pinnipeds in water, measurements of TTS are limited to harbor
seals, elephant seals (Mirounga angustirostris), bearded seals
(Erignathus barbatus) and California sea lions (Zalophus californianus)
(Kastak et al., 1999, 2007; Kastelein et al., 2019b, 2019c, 2021,
2022a, 2022b; Reichmuth et al., 2019; Sills et al., 2020). TTS was not
observed in spotted (Phoca largha) and ringed (Pusa hispida) seals
exposed to single airgun impulse sounds at levels matching previous
predictions of TTS onset (Reichmuth et al., 2016). These studies
examine hearing thresholds measured in marine mammals before and after
exposure to intense or long-duration sound exposures. The difference
between the pre-exposure and post-exposure thresholds can be used to
determine the amount of threshold shift at various post-exposure times.
The amount and onset of TTS depends on the exposure frequency.
Sounds 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
would 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> would overestimate the amount of TTS from intermittent
exposures, such as sonars and impulsive sources. Nachtigall et al.
(2018) describe measurements of hearing sensitivity of multiple
odontocete species (bottlenose dolphin, harbor porpoise, beluga, and
false killer whale (Pseudorca crassidens)) when a relatively loud sound
was preceded by a warning sound. These captive animals were shown to
reduce hearing sensitivity when warned of an impending intense sound.
Based on these experimental observations of captive animals, the
authors suggest that wild animals may dampen their hearing during
prolonged exposures or if conditioned to anticipate intense sounds.
Another study showed that echolocating animals (including odontocetes)
might have anatomical specializations that might allow for conditioned
hearing reduction and filtering of low-frequency ambient noise,
including increased stiffness and control of middle ear structures and
placement of inner ear structures (Ketten et al., 2021). Data available
on noise-induced hearing loss for mysticetes are currently lacking
(NMFS, 2024). Additionally, the existing marine mammal TTS data come
from a limited number of individuals within these species.
Relationships between TTS and AUD INJ thresholds have not been
studied in marine mammals, and there are no measured PTS data for
cetaceans, but such relationships are assumed to be similar to those in
humans and other terrestrial mammals. AUD INJ typically occurs at
exposure levels at least several dB above that inducing mild TTS (e.g.,
a 40-dB threshold shift approximates AUD INJ onset (Kryter et al.,
1966; Miller, 1974), while a 6-dB threshold shift approximates TTS
onset (Southall et al., 2007, 2019). Based on data from terrestrial
mammals, a precautionary assumption is that the AUD INJ thresholds for
impulsive sounds (such as impact pile driving pulses as received close
to the source) are at least 6 dB higher than the TTS threshold on a
peak-pressure basis and AUD INJ cumulative sound exposure level
thresholds are 15 to 20 dB higher than TTS cumulative sound exposure
level thresholds (Southall et al., 2007, 2019). Given the higher level
of sound or longer exposure duration necessary to cause AUD INJ as
compared with TTS, it is considerably less likely that AUD INJ could
occur. Given the stationary nature of the construction activities, the
fact that Cold Bay is relatively sheltered (i.e., not located in the
open ocean), and the fact that many marine mammals are likely moving
through the project areas and not remaining for extended periods of
time, the potential for threshold shift is low for most species.
Behavioral Effects--Exposure to noise also has the potential to
behaviorally disturb marine mammal response--in other words, not every
response qualifies as behavioral disturbance, and for responses that
do, those of a higher level, or accrued across a longer duration, have
the potential to affect foraging, reproduction, or survival. Behavioral
disturbance may include a variety of effects, including subtle changes
in behavior (e.g., minor or brief avoidance of an area or changes in
vocalizations), more conspicuous changes in similar behavioral
activities, and more sustained and/or potentially severe reactions,
such as displacement from or abandonment of high-quality habitat.
Behavioral responses may include changing durations of surfacing and
dives, changing direction and/or speed; reducing/increasing vocal
activities; changing/cessation of certain behavioral activities (such
as socializing or feeding); eliciting a visible startle response or
aggressive behavior (such as tail/fin slapping or jaw clapping); and
avoidance of areas where sound sources are located. In addition,
pinnipeds may increase their haul out time, possibly to avoid in-water
disturbance (Thorson and Reyff, 2006).
Behavioral responses to sound are highly variable and context-
specific and any reactions depend on numerous intrinsic and extrinsic
factors (e.g., species, state of maturity, experience, current
activity, reproductive state, auditory sensitivity, time of day), as
well as the interplay between factors (e.g., Richardson et al., 1995;
Wartzok et al., 2004; Southall et al., 2007, 2019; Weilgart, 2007;
Archer et al., 2010). Behavioral reactions can vary not only among
individuals but also within an individual, depending on previous
experience with a sound source, context, and numerous other factors
(Ellison et al., 2012), and can vary depending on characteristics
associated with the sound source (e.g., whether it is moving or
stationary, number of sources, distance from the source). In general,
pinnipeds seem more tolerant of, or at least habituate more quickly to,
potentially disturbing underwater sound than do cetaceans, and
generally seem to be less responsive to exposure to industrial sound
than most cetaceans. Please see Appendices B and C of Southall et al.
(2007) and Gomez et al. (2016) for reviews of studies involving marine
mammal behavioral responses to sound.
Habituation can occur when an animal's response to a stimulus wanes
with repeated exposure, usually in the absence of unpleasant associated
events (Wartzok et al., 2004). Animals are most likely to habituate to
sounds that are predictable and unvarying. It is important to note that
habituation is appropriately considered as a ``progressive reduction in
response to stimuli that are perceived as neither aversive nor
beneficial,'' rather than as, more generally, moderation in response to
human disturbance (Bejder et al.,
[[Page 60663]]
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 (e.g., Erbe et al., 2019). If a marine mammal does react
briefly to an underwater sound by changing its behavior or moving a
small distance, the impacts of the change are unlikely to be
significant to the individual, let alone the stock or population. If a
sound source displaces marine mammals from an important feeding or
breeding area for a prolonged period, impacts on individuals and
populations could be significant (e.g., Lusseau and Bejder, 2007;
Weilgart, 2007; NRC, 2005). However, there are broad categories of
potential response, which we describe in greater detail here, that
include alteration of dive behavior, alteration of foraging behavior,
effects to breathing, interference with or alteration of vocalization,
avoidance, and flight.
Avoidance and displacement-- Changes in dive behavior can vary
widely and may consist of increased or decreased dive times and surface
intervals as well as changes in the rates of ascent and descent during
a dive (e.g., Frankel and Clark, 2000; Costa et al., 2003; Ng and
Leung, 2003; Nowacek et al., 2004; Goldbogen et al., 2013a, 2013b,
Blair et al., 2016). Variations in dive behavior may reflect
interruptions in biologically significant activities (e.g., foraging)
or they may be of little biological significance. The impact of an
alteration to dive behavior resulting from an acoustic exposure depends
on what the animal is doing at the time of the exposure and the type
and magnitude of the response.
Disruption of feeding behavior can be difficult to correlate with
anthropogenic sound exposure, so it is usually inferred by observed
displacement from known foraging areas, the appearance of secondary
indicators (e.g., bubble nets or sediment plumes), or changes in dive
behavior. Acoustic and movement bio-logging tools also have been used
in some cases to infer responses to anthropogenic noise. For example,
Blair et al. (2015) reported significant effects on humpback whale
foraging behavior in Stellwagen Bank in response to ship noise
including slower descent rates, and fewer side-rolling events per dive
with increasing ship nose. In addition, Wisniewska et al. (2018)
reported that tagged harbor porpoises demonstrated fewer prey capture
attempts when encountering occasional high-noise levels resulting from
vessel noise as well as more vigorous fluking, interrupted foraging,
and cessation of echolocation signals observed in response to some
high-noise vessel passes. As for other types of behavioral response,
the frequency, duration, and temporal pattern of signal presentation,
as well as differences in species sensitivity, are likely contributing
factors to differences in response in any given circumstance (e.g.,
Croll et al., 2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko
et al., 2007). A determination of whether foraging disruptions incur
fitness consequences would require information on or estimates of the
energetic requirements of the affected individuals and the relationship
between prey availability, foraging effort and success, and the life
history stage of the animal.
Respiration rates vary naturally with different behaviors and
alterations to breathing rate as a function of acoustic exposure can be
expected to co-occur with other behavioral reactions, such as a flight
response or an alteration in diving. However, respiration rates in and
of themselves may be representative of annoyance or an acute stress
response. Various studies have shown that respiration rates may either
be unaffected or could increase, depending on the species and signal
characteristics, again highlighting the importance in understanding
species differences in the tolerance of underwater noise when
determining the potential for impacts resulting from anthropogenic
sound exposure (e.g., Kastelein et al., 2001; 2005; 2006; Gailey et
al., 2007). For example, harbor porpoise respiration rates increased in
response to pile driving sounds at and above a received broadband SPL
of 136 dB (zero-peak SPL: 151 dB re 1 [mu]Pa; SEL of a single strike
(SEL<INF>ss</INF>): 127 dB re 1 [mu]Pa\2\-s) (Kastelein et al., 2013).
Avoidance is the displacement of an individual from an area or
migration path as a result of the presence of a sound or other
stressors, and is one of the most obvious manifestations of disturbance
in marine mammals (Richardson et al., 1995). For example, gray whales
are known to change direction--deflecting from customary migratory
paths--in order to avoid noise from seismic surveys (Malme et al.,
1984). Harbor porpoises, Atlantic white-sided dolphins (Lagenorhynchus
actusus), and minke whales (Balaenoptera acutorostrata) have
demonstrated avoidance in response to vessels during line transect
surveys (Palka and Hammond, 2001). In addition, beluga whales in the
St. Lawrence Estuary in Canada have been reported to increase levels of
avoidance with increased boat presence by way of increased dive
durations and swim speeds, decreased surfacing intervals, and by
bunching together into groups (Blane and Jaakson, 1994). Avoidance may
be short-term, with animals returning to the area once the noise has
ceased (e.g., Bowles et al., 1994; Goold, 1996; Stone et al., 2000;
Morton and Symonds, 2002; Gailey et al., 2007). Longer-term
displacement is possible, however, which may lead to changes in
abundance or distribution patterns of the affected species in the
affected region if habituation to the presence of the sound does not
occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann et
al., 2006).
A flight response is a dramatic change in normal movement to a
directed and rapid movement away from the perceived location of a sound
source. The flight response differs from other avoidance responses in
the intensity of the response (e.g., directed movement, rate of
travel). Relatively little information on flight responses of marine
mammals to anthropogenic signals exist, although observations of flight
responses to the presence of predators have occurred (Connor and
Heithaus, 1996; Bowers et al., 2018). The result of a flight response
could range from brief, temporary exertion and displacement from the
area where the signal provokes flight to, in extreme cases, marine
mammal strandings (England et al., 2001). However, it should be noted
that response to a perceived predator does not necessarily invoke
flight (Ford and Reeves, 2008), and whether individuals are solitary or
in groups may influence the response.
Behavioral disturbance can also impact marine mammals in more
subtle
[[Page 60664]]
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.
Physiological stress responses--An animal's perception of a threat
may be sufficient to trigger stress responses consisting of some
combination of behavioral responses, autonomic nervous system
responses, neuroendocrine responses, or immune responses (e.g., Selye,
1950; Moberg, 2000). In many cases, an animal's first and sometimes
most economical (in terms of energetic costs) response is behavioral
avoidance of the potential stressor. Autonomic nervous system responses
to stress typically involve changes in heart rate, blood pressure, and
gastrointestinal activity. These responses have a relatively short
duration and may or may not have a significant long-term effect on an
animal's fitness.
Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that
are affected by stress--including immune competence, reproduction,
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been
implicated in failed reproduction, altered metabolism, reduced immune
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha,
2000). Increases in the circulation of glucocorticoids are also equated
with stress (Romano et al., 2004).
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 would last until the animal replenishes its energetic reserves
sufficient to restore normal function.
Relationships between these physiological mechanisms, animal
behavior, and the costs of stress responses are well studied through
controlled experiments and for both laboratory and free-ranging animals
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003;
Krausman et al., 2004; Lankford et al., 2005; Ayres et al., 2012; Yang
et al., 2022). Stress responses due to exposure to anthropogenic sounds
or other stressors and their effects on marine mammals have also been
reviewed (Fair and Becker, 2000; Romano et al., 2002b) and, more
rarely, studied in wild populations (e.g., Romano et al., 2002a). For
example, Rolland et al. (2012) found that noise reduction from reduced
ship traffic in the Bay of Fundy was associated with decreased stress
in North Atlantic right whales. In addition, Lemos et al. (2022)
observed a correlation between higher levels of fecal glucocorticoid
metabolite concentrations (indicative of a stress response) and vessel
traffic in gray whales. Yang et al. (2022) studied behavioral and
physiological responses in captive bottlenose dolphins exposed to
playbacks of ``pile-driving-like'' impulsive sounds, finding
significant changes in cortisol and other physiological indicators but
only minor behavioral changes. These and other studies lead to a
reasonable expectation that some marine mammals 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, 2005), however distress is an
unlikely result of this project based on observations of marine mammals
during previous, similar construction projects.
Vocalizations and Auditory Masking--Since many marine mammals rely
on sound to find prey, moderate social interactions, and facilitate
mating (Tyack, 2008), noise from anthropogenic sound sources can
interfere with these functions, but only if the noise spectrum overlaps
with the hearing sensitivity of the receiving marine mammal (Southall
et al., 2007; Clark et al., 2009; Hatch et al., 2012). Chronic exposure
to excessive, though not high-intensity, noise could cause masking at
particular frequencies for marine mammals that utilize sound for vital
biological functions (Clark et al., 2009). Acoustic masking is when
other noises such as from human sources interfere with an animal's
ability to detect, recognize, or discriminate between acoustic signals
of interest (e.g., those used for intraspecific communication and
social interactions, prey detection, predator avoidance, navigation)
(Richardson et al., 1995; Erbe et al., 2016). Therefore, under certain
circumstances, for marine mammals whose acoustic 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
[[Page 60665]]
reflect increased vigilance or a startle response. For example, in the
presence of potentially masking signals, humpback whales and killer
whales have been observed to increase the length of their songs (Miller
et al., 2000; Fristrup et al., 2003) or vocalizations (Foote et al.,
2004), respectively, while North Atlantic right whales (Eubalaena
glacialis) have been observed to shift the frequency content of their
calls upward while reducing the rate of calling in areas of increased
anthropogenic noise (Parks et al., 2007). Fin whales (Balaenoptera
physalus) have also been documented lowering the bandwidth, peak
frequency, and center frequency of their vocalizations under increased
levels of background noise from large vessels (Castellote et al. 2012).
Other alterations to communication signals have also been observed. For
example, gray whales, in response to playback experiments exposing them
to vessel noise, have been observed increasing their vocalization rate
and producing louder signals at times of increased outboard engine
noise (Dahlheim and Castellote, 2016). Alternatively, in some cases,
animals may cease sound production during production of aversive
signals (Bowles et al., 1994, Wisniewska et al., 2018).
Under certain circumstances, marine mammals experiencing
significant masking could also be impaired from maximizing their
performance fitness in survival and reproduction. Therefore, when the
coincident (masking) sound is human-made, it may be considered
harassment when disrupting or altering critical behaviors. It is
important to distinguish TTS and PTS, which persist after the sound
exposure, from masking, which occurs during the sound exposure. Because
masking (without resulting in TS) is not associated with abnormal
physiological function, it is not considered a physiological effect,
but rather a potential behavioral effect (though not necessarily one
that would be associated with harassment).
The frequency range of the potentially masking sound is important
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation
sounds produced by odontocetes but are more likely to affect detection
of mysticete communication calls and other potentially important
natural sounds such as those produced by surf and some prey species.
The masking of communication signals by anthropogenic noise may be
considered as a reduction in the communication space of animals (e.g.,
Clark et al., 2009) and may result in energetic or other costs as
animals change their vocalization behavior (e.g., Miller et al., 2000;
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2010; Holt
et al., 2009). Masking can be reduced in situations where the signal
and noise come from different directions (Richardson et al., 1995),
through amplitude modulation of the signal, or through other
compensatory behaviors, including modifications of the acoustic
properties of the signal or the signaling behavior (Hotchkin and Parks,
2013). Masking can be tested directly in captive species (e.g., Erbe,
2008), but in wild populations it must be either modeled or inferred
from evidence of masking compensation. There are few studies addressing
real-world masking sounds likely to be experienced by marine mammals in
the wild (e.g., Branstetter et al., 2013).
Masking occurs in the frequency band that the animals utilize and
is more likely to occur in the presence of broadband, relatively
continuous noise sources such as vibratory pile driving. Energy
distribution of vibratory pile driving sound covers a broad frequency
spectrum and is anticipated to be within the audible range of marine
mammals present in the proposed action area. Since noises generated
from the proposed construction activities are mostly concentrated at
low frequencies (<2 kHz), these activities likely have less effect on
mid-frequency echolocation sounds produced by odontocetes (toothed
whales). However, lower frequency noises are more likely to affect
detection of communication calls and other potentially important
natural sounds such as surf and prey noise. Low-frequency noise may
also affect communication signals when they occur near the frequency
band for noise and thus reduce the communication space of animals
(e.g., Clark et al., 2009) and cause increased stress levels (e.g.,
Holt et al., 2009). Unlike TS, masking, which can occur over large
temporal and spatial scales, can potentially affect the species at
population, community, or even ecosystem levels, in addition to
individual levels. Masking affects both senders and receivers of the
signals, and at higher levels for longer durations, could have long-
term chronic effects on marine mammal species and populations. However,
the noise generated by ADOT&PF's proposed activities would only occur
intermittently, across an estimated 231 (not necessarily consecutive)
days during the proposed authorization period in a relatively small
area focused around the proposed construction site. Thus, while the
ADOT&PF's proposed activities may mask some acoustic signals that are
relevant to the daily behavior of marine mammals, the short-term
duration and limited areas affected make it very unlikely that the
fitness of individual marine mammals would be impacted.
While in some cases marine mammals have exhibited little to no
obviously detectable response to certain common or routine
industrialized activities (Cornick et al., 2011; Horley and Larson,
2023), it is possible some animals may at times be exposed to received
levels of sound above the AUD INJ and Level B harassment thresholds
during the proposed project. This potential exposure in combination
with the nature of planned activity (e.g., vibratory pile driving,
impact pile driving) means it is possible that take by Level A and
Level B harassment could occur over the total estimated period of
activities; therefore, NMFS, in response to ADOT&PF's IHA application,
proposes to authorize take by Level A and Level B harassment from
ADOT&PF's proposed construction activities.
Airborne Acoustic Effects--Pinnipeds that occur near the project
site could be exposed to airborne sounds associated with construction
activities that have the potential to cause behavioral harassment,
depending on their distance from these activities. Airborne noise would
primarily be an issue for pinnipeds that are swimming or hauled out
near the project site within the range of noise levels elevated above
airborne acoustic harassment criteria. As described above in
Description of Sound Sources for the Specified Activities, although
pinnipeds are known to haul-out regularly on man-made objects, we
believe that incidents of take resulting solely from airborne sound are
unlikely due to the proximity between the proposed project area and the
known haulout sites (refer back to table 5). Cetaceans are not expected
to be exposed to airborne sounds that would result in harassment as
defined under the MMPA.
We recognize that pinnipeds in the water could be exposed to
airborne sound that may result in behavioral harassment when looking
with their heads above water. Most likely, airborne sound would cause
behavioral responses similar to those discussed above in relation to
underwater sound. For instance, anthropogenic sound could cause hauled
out pinnipeds to exhibit changes in their normal behavior, such as
reduction in vocalizations, or cause them to flush from haulouts,
temporarily abandon the area, and or move further from the
[[Page 60666]]
source. However, these animals would previously have been ``taken''
because of exposure to underwater sound above the behavioral harassment
thresholds, which are in all cases larger than those associated with
airborne sound. Thus, the behavioral harassment of these animals is
already accounted for in these estimates of potential take. Therefore,
we do not believe that authorization of incidental take resulting from
airborne sound for pinnipeds is warranted, and airborne sound is not
discussed further here.
Potential Effects on Marine Mammal Habitat
ADOT&PF's proposed activities could have localized, temporary
impacts on marine mammal habitat, including prey, by increasing in-
water SPLs. Increased noise levels may affect acoustic habitat and
adversely affect marine mammal prey in the vicinity of the project
areas (see discussion below). Elevated levels of underwater noise would
ensonify the project areas where both fishes and mammals occur and
could affect foraging success. Additionally, marine mammals may avoid
the area during the proposed construction activities; however,
displacement due to noise is expected to be temporary and is not
expected to result in long-term effects to the individuals or
populations.
The total area likely impacted by ADOT&PF's activities is
relatively small compared to the available habitat in and around Cold
Bay. Avoidance by potential prey (i.e., fish) of the immediate area due
to increased noise is possible. The duration of fish and marine mammal
avoidance of this area after tugging stops is unknown, but a rapid
return to normal recruitment, distribution, and behavior is
anticipated. Any behavioral avoidance by fish or marine mammals of the
disturbed area would still leave significantly large areas of fish and
marine mammal foraging habitat in the nearby vicinity.
The proposed project would occur within the same general footprint
as the existing marine infrastructure. The nearshore and intertidal
habitat where the proposed project would occur is an area of relatively
high marine vessel traffic. Most marine mammals do not generally use
the area within the footprint of the project area. Temporary,
intermittent, and short-term habitat alteration may result from
increased noise levels during the proposed construction activities.
Effects on marine mammals would be limited to temporary displacement
from pile installation and removal noise, and effects on prey species
would be similarly limited in time and space.
Water quality--Temporary and localized reduction in water quality
would occur as a result of in-water construction activities. Most of
this effect would occur during the installation and removal of piles
when bottom sediments are disturbed. The installation and removal of
piles would disturb bottom sediments and may cause a temporary increase
in suspended sediment in the project area. During pile 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. Turbidity within the water column has the
potential to reduce the level of oxygen in the water and irritate the
gills of prey fish species in the proposed project area. However,
turbidity plumes associated with the project would be temporary and
localized, and fish in the proposed project area would be able to move
away from and avoid the areas where plumes may occur. Therefore, it is
expected that the impacts on prey fish species from turbidity, and
therefore on marine mammals, would be minimal and temporary. In
general, the area likely impacted by the proposed construction
activities is relatively small compared to the available marine mammal
habitat in Cold Bay.
Potential Effects on Prey--Sound may affect marine mammals through
impacts on the abundance, behavior, or distribution of prey species
(e.g., crustaceans, cephalopods, fishes, zooplankton). Marine mammal
prey varies by species, season, and location and, for some, is not well
documented. Studies regarding the effects of noise on known marine
mammal prey are described here.
Fishes utilize the soundscape and components of sound in their
environment to perform important functions such as foraging, predator
avoidance, mating, and spawning (e.g., Zelick et al., 1999; Fay, 2009).
Depending on their hearing anatomy and peripheral sensory structures,
which vary among species, fishes hear sounds using pressure and
particle motion sensitivity capabilities and detect the motion of
surrounding water (Fay et al., 2008). The potential effects of noise on
fishes depends on the overlapping frequency range, distance from the
sound source, water depth of exposure, and species-specific hearing
sensitivity, anatomy, and physiology. Key impacts to fishes may include
behavioral responses, hearing damage, barotrauma (pressure-related
injuries), and mortality.
Fish react to sounds that are especially strong and/or intermittent
low-frequency sounds, and behavioral responses such as flight or
avoidance are the most likely effects. Short duration, sharp sounds can
cause overt or subtle changes in fish behavior and local distribution.
The reaction of fish to noise depends on the physiological state of the
fish, past exposures, motivation (e.g., feeding, spawning, migration),
and other environmental factors. (Hastings and Popper, 2005) identified
several studies that suggest fish may relocate to avoid certain areas
of sound energy. Additional studies have documented effects of pile
driving on fishes (e.g., Scholik and Yan, 2001, 2002; Popper and
Hastings, 2009). Several studies have demonstrated that impulse sounds
might affect the distribution and behavior of some fishes, potentially
impacting foraging opportunities or increasing energetic costs (e.g.,
Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski et al.,
1992; Santulli et al., 1999; Paxton et al., 2017). However, some
studies have shown no or slight reaction to impulse sounds (e.g.,
Pe[ntilde]a et al., 2013; Wardle et al., 2001; Jorgenson and Gyselman,
2009; Cott et al., 2012). More commonly, though, the impacts of noise
on fishes are temporary. For example, during the Port of Alaska's
Marine Terminal Redevelopment Project, the effects of impact and
vibratory installation of 30-in (76-cm) steel sheet piles at the POA on
133 caged juvenile coho salmon (Oncorhynchus kisutc) in Knik Arm were
studied (Hart Crowser Incorporated et al., 2009; Houghton et al.,
2010). Acute or delayed mortalities, or behavioral abnormalities were
not observed in any of the coho salmon. Furthermore, results indicated
that the pile driving had no adverse effect on feeding ability or the
ability of the fish to respond normally to threatening stimuli (Hart
Crowser Incorporated et al., 2009; Houghton et al., 2010).
SPLs of sufficient strength have been known to cause injury to
fishes and fish mortality (summarized in Popper et al., 2014). However,
in most fish species, hair cells in the ear continuously regenerate and
loss of auditory function
[[Page 60667]]
is likely restored when damaged cells are replaced with new cells.
Halvorsen et al. (2012b) showed that a TTS of 4 to 6 dB was recoverable
within 24 hours for one species. Impacts would be most severe when the
individual fish is close to the source and when the duration of
exposure is long. Injury caused by barotrauma can range from slight to
severe and can cause death, and is most likely for fish with swim
bladders. Barotrauma injuries have been documented during controlled
exposure to impact pile driving (Halvorsen et al., 2012a; Casper et
al., 2013, 2017).
Fish populations in the proposed project area that serve as marine
mammal prey could be temporarily affected by noise from pile
installation and removal. The frequency range in which fishes generally
perceive underwater sounds is 50 to 2,000 Hz, with peak sensitivities
below 800 Hz (Popper and Hastings, 2009). Fish behavior or distribution
may change, especially with strong and/or intermittent sounds that
could harm fishes. High underwater SPLs have been documented to alter
behavior, cause hearing loss, and injure or kill individual fish by
causing serious internal injury (Hastings and Popper, 2005).
Zooplankton is a food source for several marine mammal species, as
well as a food source for fish that are then preyed upon by marine
mammals. Population effects on zooplankton could have indirect effects
on marine mammals. Data are limited on the effects of underwater sound
on zooplankton species, particularly sound from construction (Erbe et
al., 2019). Popper and Hastings (2009) reviewed information on the
effects of human-generated sound and concluded that no substantive data
are available on whether the sound levels from pile driving, seismic
activity, or any human-made sound would have physiological effects on
invertebrates. Any such effects would be limited to the area very near
(1 to 5 m (3.28 to 16.4 ft)) to the sound source and would result in no
population effects because of the relatively small area affected at any
one time and the reproductive strategy of most zooplankton species
(short generation, high fecundity, and very high natural mortality). No
adverse impact on zooplankton populations is expected to occur from the
specified activity due in part to large reproductive capacities and
naturally high levels of predation and mortality of these populations.
Any mortalities or impacts that might occur would be negligible.
The Essential Fish Habitat (EFH) designation for the Cold Bay,
Alaska region is fundamentally driven by the Izembek Lagoon complex,
which harbors one of the world's most extensive and productive eelgrass
(Zostera marina) beds (Ward et al., 1997; Ward and Amundson, 2019;
Douglas et al., 2024). This submerged aquatic vegetation serves as the
ecological foundation, acting as a critical nursery EFH by providing
abundant food resources, crucial shelter from predators, and favorable
hydrological conditions necessary for the feeding and growth to
maturity life stages of marine species. The adjacent coastal waters
also serve as habitat for various marine mammals, including harbor
seals, Steller sea lions, and cetaceans such as gray, minke, killer,
and humpback whales.
The habitat is vital for sustaining major regional fisheries,
serving as an important area for all five species of Pacific salmon
(genus Oncorhynchus) which utilize the lagoon and associated streams
for migration and spawning. Crucially, the Izembek Lagoon nursery
supports federally managed crustaceans, including juvenile red king
crab (Paralithodes camtschaticus) and tanner crab (Chionoecetes
bairdi), whose survival is dependent on the shallow, protected
environment before they move to deeper Cold Bay areas as adults (U.S.
Fish and Wildlife Service, 2024). Additionally, the system sustains
large populations of forage fish (such as capelin (Mallotus villosus),
sand lance (family Ammodytidae), and herring (Clupea pallasii)),
Pacific halibut (Hippoglossus stenolepis), and Walleye Pollack (Gadus
chalcogrammus), which in turn support high concentrations of apex
predators (U.S. Fish and Wildlife Service, 2024). However, based on the
potential effects of the proposed project, adverse effects on EFH in
this area are not expected.
The greatest potential impact to marine mammal prey during
construction would occur during impact pile driving. However, in most
cases, the duration of impact pile driving would be limited to the
final stage of installation (proofing) after the pile has been driven
as close as practicable to the design depth with a vibratory driver.
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 could 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.
Potential Effects on Foraging Habitat
The proposed project is not expected to result in any habitat
related effects that could cause significant or long-term negative
consequences for individual marine mammals or their populations, since
installation and removal of in-water piles would be temporary and
intermittent. The total seafloor area affected by pile installation and
removal is a very small area compared to the vast foraging area
available to marine mammals outside this project area. For marine
mammals, while the area is commonly used or traversed by some species,
the proposed project area does not contain any particularly high-value
habitat and is not usually important to any of the other species
potentially affected by ADOT&PF's proposed activities. While
opportunistic foraging could occur, more foraging habitat is available
outside the Bay, in more open ocean waters. Overall, the area impacted
by the project is relatively small compared to the available habitat
just outside the project area, and there are no areas of particular
importance that would be impacted by this project during the period
planned for activities to occur. Any behavioral avoidance by fish of
the disturbed area would still leave significantly large areas of fish
and marine mammal foraging habitat in the nearby vicinity. As described
in the preceding, the potential for the ADOT&PF's construction to
affect the availability of prey to marine mammals or to meaningfully
impact the quality of physical or acoustic habitat is considered
insignificant. Therefore, impacts of the project are not likely to have
adverse effects on marine mammal foraging habitat in the proposed
project area.
In summary, given the relatively small areas being affected, as
well as the temporary and mostly transitory nature of the proposed
construction activities, any adverse effects from ADOT&PF's activities
on prey habitat or prey populations are expected to be minor and
temporary. The most likely impact to fishes at the project site would
be temporary avoidance of the area. Any behavioral avoidance by fish of
the disturbed area would still leave significantly large areas of fish
and marine mammal foraging habitat in the nearby vicinity. Thus, we
preliminarily conclude that impacts of the specified
[[Page 60668]]
activities are not likely to have more than short-term adverse effects
on any prey habitat or populations of prey species. Further, any
impacts to marine mammal habitat are not expected to result in
significant or long-term consequences for individual marine mammals, or
to contribute to adverse impacts on their populations.
Estimated Take of Marine Mammals
This section provides an estimate of the number of incidental takes
proposed for authorization through the IHA, which will inform NMFS'
consideration of ``small numbers,'' the negligible impact
determinations, and impacts on subsistence uses.
Harassment is the only type of take expected to result from these
activities. Except with respect to certain activities not pertinent
here, section 3(18) of the MMPA defines ``harassment'' as any act of
pursuit, torment, or annoyance, which (i) has the potential to injure a
marine mammal or marine mammal stock in the wild (Level A harassment);
or (ii) has the potential to disturb a marine mammal or marine mammal
stock in the wild by causing disruption of behavioral patterns,
including, but not limited to, migration, breathing, nursing, breeding,
feeding, or sheltering (Level B harassment).
Authorized takes would primarily be by Level B harassment, as use
of the acoustic sources (i.e., impact pile driving, vibratory pile
driving) has the potential to result in disruption of behavioral
patterns for individual marine mammals. There is also some potential
for auditory injury (AUD INJ) (Level A harassment) to result, primarily
for mysticetes, very high-frequency cetaceans, phocids, and otariids
because predicted AUD INJ zones are larger than for high-frequency
species. AUD INJ is unlikely to occur for high-frequency cetaceans. The
proposed mitigation and monitoring measures are expected to minimize
the severity of the taking to the extent practicable.
As described previously, no serious injury or mortality is
anticipated or proposed to be authorized for this activity. Below we
describe how the proposed take numbers are estimated.
For acoustic impacts, generally speaking, we estimate take by
considering: (1) acoustic criteria above which NMFS believes there is
some reasonable potential for marine mammals to be behaviorally
harassed or incur some degree of AUD INJ; (2) the area or volume of
water that would be ensonified above these levels in a day; (3) the
density or occurrence of marine mammals within these ensonified areas;
and, (4) the number of days of activities. 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). We note that the criteria for AUD INJ, as well as
the names of two hearing groups, have been recently updated (NMFS,
2024) as reflected below in the Level A harassment section.
Level B Harassment--Though significantly driven by received level,
the onset of behavioral disturbance from anthropogenic noise exposure
is also informed to varying degrees by other factors related to the
source or exposure context (e.g., frequency, predictability, duty
cycle, duration of the exposure, signal-to-noise ratio, distance to the
source), the environment (e.g., bathymetry, other noises in the area,
predators in the area), and the receiving animals (hearing, motivation,
experience, demography, life stage, depth) and can be difficult to
predict (e.g., Southall et al., 2007, 2021, Ellison et al., 2012).
Based on what the available science indicates and the practical need to
use a threshold based on a metric that is both predictable and
measurable for most activities, NMFS typically uses a generalized
acoustic threshold based on received level to estimate the onset of
behavioral harassment. NMFS generally predicts that marine mammals are
likely to be behaviorally harassed in a manner considered to be Level B
harassment when exposed to underwater anthropogenic noise above root-
mean-squared pressure received levels (RMS SPL) of 120 dB (referenced
to 1 micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive impulsive (e.g., seismic airguns) or intermittent (e.g.,
scientific sonar) sources. Generally speaking, Level B harassment take
estimates based on these behavioral harassment thresholds are expected
to include any likely takes by 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.
ADOT&PF's proposed pile driving includes the use of continuous
(vibratory hammer) and impulsive (impact hammer) sources, and therefore
the RMS SPL thresholds of 120 and 160 dB re 1 [mu]Pa are applicable.
Level A harassment--NMFS' Updated Technical Guidance for Assessing
the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version
3.0) (Updated Technical Guidance, 2024) identifies dual criteria to
assess AUD INJ (Level A harassment) to five different underwater marine
mammal groups (based on hearing sensitivity) as a result of exposure to
noise from two different types of sources (impulsive or non-impulsive).
ADOT&PF's proposed pile driving includes the use of impulsive (impact
hammer) and non-impulsive (vibratory hammer) sources.
The 2024 Updated Technical Guidance criteria include both updated
thresholds and updated weighting functions for each hearing group
(table 6). The thresholds are provided in the table below. The
references, analysis, and methodology used in the development of the
criteria are described in NMFS' 2024 Updated Technical Guidance, which
may be accessed at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools</a>.
[[Page 60669]]
Table 6--Thresholds Identifying the Onset of Auditory Injury
----------------------------------------------------------------------------------------------------------------
AUD INJ onset acoustic thresholds * (received level)
Hearing group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: Lpk,flat: 222 dB; Cell 2: LE,LF,24h: 197 dB.
LE,LF,24h: 183 dB.
High-Frequency (HF) Cetaceans.......... Cell 3: Lpk,flat: 230 dB; Cell 4: LE,HF,24h: 201 dB.
LE,HF,24h: 193 dB.
Very High-Frequency (VHF) Cetaceans.... Cell 5: Lpk,flat: 202 dB; Cell 6: LE,VHF,24h: 181 dB.
LE,VHF,24h: 159 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lpk,flat: 223 dB; Cell 8: LE,PW,24h: 195 dB.
LE,PW,24h: 183 dB.
Otariid Pinnipeds (OW) (Underwater).... Cell 9: Lpk,flat: 230 dB; Cell 10: LE,OW,24h: 199 dB.
LE,OW,24h: 185 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric criteria for impulsive sounds: Use whichever criteria results in the larger isopleth for
calculating AUD INJ onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure
level criteria associated with impulsive sounds, the PK SPL criteria are recommended for consideration for non-
impulsive sources.
Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1 [micro]Pa, and weighted cumulative sound
exposure level (LE,p) has a reference value of 1 [micro]Pa\2\s. In this table, criteria are abbreviated to be
more reflective of International Organization for Standardization standards (ISO, 2017). The subscript
``flat'' is being included to indicate peak sound pressure are flat weighted or unweighted within the
generalized hearing range of marine mammals underwater (i.e., 7 Hz to 165 kHz). The subscript associated with
cumulative sound exposure level criteria indicates the designated marine mammal auditory weighting function
(LF, HF, and VHF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours.
The weighted cumulative sound exposure level criteria could be exceeded in a multitude of ways (i.e., varying
exposure levels and durations, duty cycle). When possible, it is valuable for action proponents to indicate
the conditions under which these criteria will be exceeded.
Ensonified Area
Here, we describe operational and environmental parameters of the
activity that are used in estimating the area ensonified above the
acoustic thresholds, including source levels and transmission loss
coefficient.
The sound field in the project area is the existing background
noise plus additional construction noise from the proposed project.
Marine mammals are expected to be affected via sound generated by the
primary components of the project (i.e., impact pile driving and
vibratory pile driving). The source levels assumed for both removal and
installation activities are based on reviews of measurements of the
same or similar types and dimensions of piles available in the
scientific literature and from similar coastal construction projects.
Derived by the applicant using Geographic Information System software,
the source levels for the piles and activities (i.e., installation and/
or removal), and the information and literature used to determine
appropriate proxy sources, where applicable, are presented in table 7.
The source levels for vibratory removal and installation of piles of
the same material and diameter are assumed to be the same.
Table 7--Sound Source Levels Incorporated Into the Analysis at 10 Meters (M)
----------------------------------------------------------------------------------------------------------------
Sound Sound Peak
Installation pressure exposure source
Activity Pile type method level (SPL level level
RMS) \a\ (SEL) (SPL PK)
----------------------------------------------------------------------------------------------------------------
Trestle and Abutment
----------------------------------------------------------------------------------------------------------------
Trestle support pile............. 36-in steel pipe Vibratory 166.0 ......... .........
piles. Installation \b\.
Impact Installation 193.0 183.0 210.0
\c\.
Temporary trestle pile........... 24-in to 36-in steel Vibratory 166.0 ......... .........
pipe or H-pile. Installation and
Removal \b\ \e\.
Impact Installation 193.0 183.0 210.0
\c\.
----------------------------------------------------------------------------------------------------------------
Dock
----------------------------------------------------------------------------------------------------------------
Dock support pile................ 36-in steel pipe Vibratory 166.0 ......... .........
pile. Installation \b\.
Impact Installation 193.0 183.0 210.0
\c\.
Temporary dock pile.............. 24-in to 36-in steel Vibratory 166.0 ......... .........
pipe pile. Installation and
Removal \b\ \e\.
Impact Installation 193.0 183.0 210.0
\c\.
Fender pile...................... 30-in steel pipe Vibratory 166.0 ......... .........
pile. Installation \d\.
Fender pile...................... 24-in steel pipe Vibratory 161.0 ......... .........
pile. Installation.
----------------------------------------------------------------------------------------------------------------
Dolphin
----------------------------------------------------------------------------------------------------------------
Dolphin pile..................... 36-in steel pipe Vibratory 166.0 ......... .........
pile. Installation \b\.
Impact Installation 193.0 183.0 210.0
\c\.
Temporary dolphin pile........... 24-in to 36-in steel Vibratory 166.0 ......... .........
pipe pile. installation and
removal \b\ \e\.
----------------------------------------------------------------------------------------------------------------
Demolition (Removal)
----------------------------------------------------------------------------------------------------------------
Trestle removal.................. 16-in steel pipe Vibratory removal 161.0 ......... .........
pile. \e\.
Dock removal..................... 16-in steel pipe Vibratory removal 161.0 ......... .........
pile. \e\.
Dock removal..................... 26-in steel pipe Vibratory removal 166.0 ......... .........
pile. \d\.
Dolphin removal.................. 16-in steel pipe Vibratory removal 161.0 ......... .........
pile. \e\.
Fender removal................... 20-in steel pipe Vibratory removal 161.0 ......... .........
pile. \e\.
Fender removal................... 16-in timber pile... Vibratory removal 162.0 ......... .........
\f\.
----------------------------------------------------------------------------------------------------------------
\a\ All values relative to 1 [micro]Pa.
[[Page 60670]]
\b\ Navy (2012, 2013), Sexton (2007), Laughlin (2011, 2017), Miner (2020), CALTRANS (2020).
\c\ CALTRANS (2015, 2020).
\d\ Denes et al. (2016), Laughlin (2011, 2012, 2017), PND Engineering (2015), CALTRANS (2020).
\e\ NAVFAC (2015), CALTRANS (2020); fillingworth and Rodkin (2017).
Level B Harassment
Transmission Loss (TL) is the decrease in acoustic intensity as an
acoustic pressure wave propagates out from a source. TL parameters vary
with frequency, temperature, sea conditions, current, source and
receiver depth, water depth, water chemistry, and bottom composition
and topography. The general formula for underwater TL is:
TL = B x Log10(R1/R2),
Where:
TL = transmission loss in dB,
B = transmission loss coefficient,
R1 = the distance of the modeled SPL from the driven pile, and
R2 = the distance from the driven pile of the initial measurement.
This formula neglects loss due to scattering and absorption, which
is assumed to be zero in this case. The degree to which underwater
sound propagates away from a sound source depends on various factors,
most notably the water bathymetry and the presence or absence of
reflective or absorptive conditions, including in-water structures and
sediments. Spherical spreading occurs in a perfectly unobstructed
(free-field) environment not limited by depth or water surface,
resulting in a 6 dB reduction in sound level for each doubling of
distance from the source (20*log<INF>10</INF>[range]). Cylindrical
spreading occurs in an environment in which sound propagation is
bounded by the water surface and sea bottom, resulting in a reduction
of 3 dB in sound level for each doubling of distance from the source
(10*log<INF>10</INF>[range]). A practical spreading value of 15 is
often used under conditions where water increases with depth as the
receiver moves away from the shoreline, resulting in an expected
propagation environment that would lie between spherical and
cylindrical spreading loss conditions. Absent site-specific acoustic
monitoring with differing measured TL, practical spreading is used.
Site-specific TL data for Cold Bay is not available; therefore, the
default coefficient of 15 is used to determine the distances to the
Level A harassment and Level B harassment thresholds.
Level A Harassment
The ensonified area associated with Level A harassment is more
technically challenging to predict due to the need to account for a
duration component. Therefore, NMFS developed an optional User
Spreadsheet tool to accompany the 2024 Updated Technical Guidance that
can be used to relatively simply predict an isopleth distance for use
in conjunction with marine mammal density or occurrence to help predict
potential takes (found on our website here: <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>).
We note that because of some of the assumptions included in the
methods underlying this optional tool, we anticipate that the resulting
isopleth estimates are typically going to be overestimates of some
degree, which may result in an overestimate of potential take by Level
A harassment. However, this optional tool offers the best way to
estimate isopleth distances when more sophisticated modeling methods
are not available or practical. For stationary sources, such as
vibratory pile driving and impact pile driving, the optional User
Spreadsheet tool predicts the distance at which, if a marine mammal
remained at that distance for the duration of the activity, it would be
expected to incur AUD INJ. Inputs used in the optional User Spreadsheet
tool, and the resulting estimated isopleths, are reported below in
tables 8 and 9. Using the practical spreading model, NMFS determined
that the underwater noise would yield the calculated distances to the
Level A harassment and Level B harassment thresholds for marine mammals
shown in table 10.
[[Page 60671]]
Table 8--User Spreadsheet Inputs for Vibratory Pile Driving
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
User spreadsheet variables
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Structure Trestle and Dock Dolphin Demolition (removal)
---------------------------------------------- abutment -----------------------------------------------------------------------------------------------------------------------------
--------------------- Dock Temporary Fender Fender Dolphin Temporary Trestle Dock Dock Dolphin Fender Fender
Trestle Temporary support dock pile pile pile pile dolphin removal removal removal removal removal removal
trestle pile ------------------------------------------- pile -----------------------------------------------------------
support ---------------------- -------------
Pile information pile 30-inch 24-inch 36-inch 16-inch 16-inch 16-inch 16-inch 20-inch
--------- 24-inch to 36-inch 36-inch steel steel steel 24-inch to steel steel steel steel steel 16-inch
36-inch 36-inch steel steel pipe pipe pipe pipe 36-inch pipe pipe pipe pipe pipe timber
steel steel pipe pipe pile pile pile pile steel pipe pile pile pile pile pile pile
pile or H-pile pile pile
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Tab of User Spreadsheet...................... A.1: Vibratory Pile Driving (Stationary source: non-impulsive, continuous)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sound Pressure Level (dB).................... 166 166 166 166 166 161 166 166 161 161 166 161 161 162
Distance associated with sound pressure level 10 10 10 10 10 10 10 10 10 10 10 10 10 10
(meters)....................................
Transmission loss constant................... 15 15 15 15 15 15 15 15 15 15 15 15 15 15
Number of piles per day...................... 8 8 8 8 10 10 8 8 15 15 15 8 15 15
Duration to drive a single pile (minutes).... 30 60 30 30 20 20 60 30 30 30 30 30 30 30
Duration of sound production in a day 14,400 28,800 14,400 28,800 12,000 12,000 28,800 14,400 27,000 27,000 27,000 14,400 27,000 27,000
(seconds)...................................
Marine Mammal default WFA (kHz).............. 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 60672]]
Table 9--User Spreadsheet Inputs for Impact Pile Driving
----------------------------------------------------------------------------------------------------------------
User spreadsheet variables
-----------------------------------------------------------------------------------------------------------------
Structure Trestle and abutment Dock Dolphin
----------------------------------------------------------------------------------------------------------------
Trestle Temporary Dock Temporary Dolphin
support trestle support dock pile pile
pile ------------- pile ----------------------
---------- ----------
Pile information 24-inch to 36-inch 24-inch to 36-inch
36-inch 36-inch steel 36-inch steel
steel steel pipe pipe steel pipe pipe
pile or H-pile pile pile pile
----------------------------------------------------------------------------------------------------------------
Tab of User Spreadsheet................................. E.1: Impact pile driving (Stationary Source:
Impulsive, Intermittent)
----------------------------------------------------------------------------------------------------------------
Unweighted SELcum....................................... 209.8 219.8 219.8 219.8 222.0
----------------------------------------------------------------------------------------------------------------
SEL
----------------------------------------------------------------------------------------------------------------
Single Strike SELss at ``X'' distance (meters).......... 183 183 183 183 183
Number of strikes per pile.............................. 60 600 600 600 1,000
Number of piles per day................................. 8 8 8 8 8
Transmission loss coefficient........................... 15 15 15 15 15
Distance of single strike SELss (meters)................ 10 10 10 10 10
----------------------------------------------------------------------------------------------------------------
Weighting Factor Adjustment (kHz)....................... 2 2 2 2 2
----------------------------------------------------------------------------------------------------------------
PK (single strike)
----------------------------------------------------------------------------------------------------------------
Lp,0-pk at ``X'' distance (meters)...................... 210 210 210 210 210
Distance of Lp,0-pk measurements (meters)............... 10 10 10 10 10
Lp,0-pk source level.................................... 225.0 225.0 225.0 225.0 225.0
----------------------------------------------------------------------------------------------------------------
Table 10--Calculated Isopleths (in Meters (M)) and Areas (in Kilometers (Km\2\)) to NMFS' Thresholds
[NMFS, 2024]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Installation details Level A harassment (PTS) Level B
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ harassment
LFC HFC VHFC PW OW ------------------
------------------------------------------------------------------------------------- All species
Structure Pile parameters Installation approach ------------------
Isopleth Area Isopleth Area Isopleth Area Isopleth Area Isopleth Area Isopleth Area
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Trestle and Abutment
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Trestle Support Pile................. 36-in steel pipe pile... Vibratory installation. 50.1 0.1 19.2 0.0 40.9 0.1 64.4 0.1 21.7 0.0 11,659.2 116.9
Impact installation.... 610.0 1.4 77.8 0.1 944.0 2.8 541.9 1.2 202.0 0.4 1,584.9 6.4
Temporary Trestle Pile............... 24-in to 36-in steel Vibratory installation. 79.5 0.1 30.5 0.1 64.9 0.1 102.3 0.2 34.4 0.1 11,659.2 116.9
pipe or H-pile. Impact installation.... 2,831.3 14.9 361.2 0.7 4,381.4 28.0 2,515.2 12.5 937.6 2.8 1,584.9 6.4
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Dock
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Dock Support Pile.................... 36-in steel pipe piles.. Vibratory installation. 50.1 0.1 19.2 0.0 40.9 0.1 64.4 0.1 21.7 0.0 11,659.2 116.9
Impact installation.... 2,831.3 14.9 361.2 0.7 4,381.4 28.0 2,515.2 12.5 937.6 2.8 1,584.9 6.4
Temporary Dock Pile.................. 24-in to 36-in steel Vibratory installation 79.5 0.1 30.5 0.1 64.9 0.1 102.3 0.2 34.4 0.1 11,659.2 116.9
pipe piles. and removal.
Impact installation.... 2,831.3 14.9 361.2 0.7 4,381.4 28.0 2,515.2 12.5 937.6 2.8 1,584.9 6.4
Fender Pile.......................... 30-in steel pipe piles.. Vibratory installation. 44.3 0.1 17.0 0.0 36.2 0.1 57.1 0.1 19.2 0.0 11,659.2 116.9
Fender Pile.......................... 24-in steel pipe piles.. Vibratory installation. 20.6 0.0 7.9 0.0 16.8 0.0 26.5 0.0 8.9 0.0 5,411.7 39.0
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Dolphin
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Dolphin Pile......................... 36-in steel pipe piles.. Vibratory installation. 79.5 0.1 30.5 0.1 64.9 0.1 102.3 0.2 34.4 0.1 11,659.2 116.9
Impact installation.... 3,980.0 24.2 507.8 1.1 6,159.1 47.8 3,535.7 20.3 1,318.0 4.8 1,584.9 6.4
[[Page 60673]]
Temporary Dolphin Pile............... 24-in to 36-in steel Vibratory installation 50.1 0.1 19.2 0.0 40.9 0.1 64.4 0.1 21.7 0.0 11,659.2 116.9
pipe piles. and removal.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Demolition (Removal)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Trestle Removal...................... 16-in steel pipe piles.. Vibratory removal...... 35.3 0.1 13.6 0.0 28.9 0.0 45.5 0.1 15.3 0.0 5,411.7 39.0
Dock Removal......................... 16-in steel pipe piles.. Vibratory removal...... 35.3 0.1 13.6 0.0 28.9 0.0 45.5 0.1 15.3 0.0 5,411.7 39.0
Dock Removal......................... 26-in steel pipe piles.. Vibratory removal...... 76.1 0.1 29.2 0.0 62.2 0.1 98.0 0.0 33.0 0.1 11,659.2 116.9
Dolphin Removal...................... 16-in steel pipe piles.. Vibratory removal...... 23.2 0.0 8.9 0.0 19.0 0.0 29.9 0.0 10.1 0.0 5,411.7 39.0
Fender Removal....................... 20-in steel pipe piles.. Vibratory removal...... 35.3 0.1 13.6 0.0 28.9 0.0 45.5 0.1 15.3 0.0 5,411.7 39.0
Fender Removal....................... 16-in timber piles...... Vibratory removal...... 41.2 0.1 15.8 0.0 33.7 0.1 53.0 0.1 17.8 0.0 6,309.6 49.7
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: LFC = low-frequency cetaceans; HFC = high-frequency cetaceans; VHFC = very high-frequency cetaceans; PW = phocid pinnipeds (in-water); OW = otariids pinnipeds (in-water).
It should be noted that, based on the geography of Cold Bay and the
surrounding islands outside of the mouth of the Bay, the sound would
not reach the entire distance of the Level B harassment isopleths. The
size and shape of the Bay are expected to truncate the largest Level B
harassment isopleths.
Marine Mammal Occurrence and Take Estimation
In this section, we provide information about the occurrence of
marine mammals, including density or other relevant information, which
will inform the take calculations. Then, we describe how all of the
information detailed above is synthesized to produce a quantitative
estimate of the take that is reasonably likely to occur and proposed
for authorization.
In their ITA application, ADOT&PF calculated their requested take
based on the synthetization of different resources, including websites
from state and Federal agencies (i.e., Alaska Department of Fish &
Game, NMFS, U.S. Fish and Wildlife Service), data from aerial survey
performed by the National Marine Mammal Laboratory, information gleaned
from scientific literature (i.e., Zerbini et al., 2007, Rone et al.,
2017, and McInnes et al., 2024b), and information from non-profits
(i.e., iNaturalist) with both relevant species-specific and site-
specific information. Given the secluded and sheltered nature of Cold
Bay's geographic location, these resources provide the most appropriate
information for which to determine estimated species densities/
occurrences and group sizes.
Estimated take was calculated different for each species, depending
on the likely occurrence of the species in the proposed project area
(see table 11). This means that some occurrences were calculated on a
daily basis, some on a weekly, or some on a monthly (or multi-monthly)
basis. This is all assumed to occur within 231 days of project
activities requiring the use of in-water pile driving, consisting of
both vibratory and impact approaches, which can vary in total number of
days based on the specific construction activity.
Table 11--Estimated Species Occurrence
------------------------------------------------------------------------
Abundance estimate Estimated
Species assumed occurrence
------------------------------------------------------------------------
Humpback whale................ Group size of 2 0.067 \a\ per
individuals per month. workday.
Gray whale.................... Group size of 5.7 0.03 per
individuals per 3 workday.
months.
Killer whale.................. Group size of 3 0.43 per
individuals per workday.
group, assuming 1
group per week.
Harbor porpoise............... Group size of 3 0.43 per
individuals per week. workday.
Steller sea lion.............. Group size of 15 15.
individuals per day.
Harbor seal................... Group size of 10 10.
individuals per day.
------------------------------------------------------------------------
\a\ This was assumed for the entire species and then, based on NMFS
(2021), was split further for each stock/Distinct Population Segment
(DPS).
After reviewing the available resources to determine an appropriate
occurrence level (i.e., daily, weekly, monthly, multi-monthly) and
group size, these were multiplied together to yield the overall
estimated take (combined Level A harassment and Level B harassment).
These were then split using two different methods. Potential takes by
Level A harassment were calculated if 1) some of the Level A harassment
zones were estimated to exceed the practicable shutdown zone for a
given hearing group, or 2) if the species could be difficult to see due
to its small size or cryptic behavior. To calculate the proposed takes
by Level A harassment, ``areal calculations'' were performed for three
species (Steller sea lion, harbor seal, and harbor porpoise) where the
calculated area of each hearing group's Level A harassment zone was
divided by the area of the largest predicted Level B harassment
[[Page 60674]]
zone to result in an ``areal percentage''. This was then multiplied by
both the number of days determined necessary to complete the
construction task and then by unique species occurrence. To calculate
the number of estimated takes proposed for authorization by Level B
harassment, the calculated takes by Level A harassment were subtracted
from the total number of calculated takes, with the remaining assumed
to be taken by Level B harassment only.
Humpback whales are common in the general region during the summer
months; however, their presence within the project area is uncommon due
to the shallow and sheltered nature of Cold Bay. Given that all work
and noise are expected to be confined to the Bay, but in some cases,
exceed the practicable shutdown zone, NMFS proposes to conservatively
authorize two groups of two humpback whales for take by Level A
harassment.
More specific information on species/stock occurrence, which was
incorporated into the analysis, can be found in section 6 of ADOT&PF's
application and is not repeated here; instead, we reference the reader
to the application for this additional information. Below, we provide
the areal calculations (table 12), and we summarize the relevant group
sizes and information presented on the occurrence of each species/stock
and provide the numerical values proposed for authorization in the
table below (table 13).
Table 12--Areal Calculations for Three Marine Mammal Species To Estimate Proposed Takes by Level A Harassment
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level A
Maximum Level A area to Calculated
Level B harassment maximum Takes Days of proposed
Source Source type Species harassment area Level B assumed effort takes by
area (km\2\) area ratio per day planned Level A
(km\2\) \a\ (%) harassment
--------------------------------------------------------------------------------------------------------------------------------------------------------
Trestle and Abutment
--------------------------------------------------------------------------------------------------------------------------------------------------------
Trestle support pile (36-inch Impact pile driving Harbor porpoise..... 116.9 2.82 2.41 0.43 8 0
steel pipe pile). (installation). Steller sea lion.... 116.9 0.35 0.30 15 8 0
Harbor seal......... 116.9 12.55 10.74 10 8 9
Temporary trestle pile (24-inch to Impact pile driving Harbor porpoise..... 116.9 28.02 23.97 0.43 8 1
36-inch steel pipe or H-pile). (installation). Steller sea lion.... 116.9 2.78 2.38 15 8 3
Harbor seal......... 116.9 12.55 10.74 10 8 9
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dock
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dock support pile (36-inch steel Impact pile driving Harbor porpoise..... 116.9 28.02 23.97 0.43 8 1
pipe pile). (installation). Steller sea lion.... 116.9 2.78 2.38 15 8 3
Harbor seal......... 116.9 12.55 10.74 10 8 9
Temporary dock pile (24-inch to 36- Impact pile driving Harbor porpoise..... 116.9 28.02 23.97 0.43 8 1
inch steel pile). (installation). Steller sea lion.... 116.9 2.78 2.38 15 8 3
Harbor seal......... 116.9 12.55 10.74 10 8 9
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dolphin
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dolphin pile (36-inch steel pipe Impact pile driving Harbor porpoise..... 116.9 47.85 40.93 0.43 8 1
pile). (installation). Steller sea lion.... 116.9 4.79 4.10 15 8 5
Harbor seal......... 116.9 20.33 17.39 10 8 14
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ The largest behavioral isopleth (i.e., 116.9 km\2\) was calculated based on vibratory driving of 36-in pipe piles.
Table 13--Proposed Take, by Level A Harassment and/or Level B Harassment, by Stock, Harassment Type, Takes Estimated Per Day, Total Proposed Takes, and
as a Percentage of Stock Abundance
--------------------------------------------------------------------------------------------------------------------------------------------------------
Takes proposed for authorization Proposed
Takes Estimated ------------------------------------ percentage to be
NEST \a\ Takes per day number of taken \b\
Species Stock per day (by pile Level A Level B -------------------
(total) stock) driving harassment harassment Total By
days species By stock
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gray whale...................... Eastern North 26,960 0.03 231 2 13 15 0.06
Pacific.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale \c\.............. Hawai[revaps]i..... 11,278 0.067 0.061 231 4 11 15 0.16 0.13
Mexico-North n/a ........ 0.005 231 0 2 2 n/a n/a
Pacific. 1,084 ........ 0.001 231 0 1 1 1.66 0.09
Western North
Pacific.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Killer whale.................... Eastern North 587 0.43 231 0 99 99 16.87
Pacific Gulf of
Alaska, Aleutian
Islands, and
Bering Sea
Transient.
Harbor porpoise................. Gulf of Alaska..... 31,046 0.43 231 4 26 30 0.10
Steller sea lion................ Western............ 49,837 15 231 14 3,211 3,225 6.47
Harbor seal..................... Cook Inlet/Shelikof 28,411 10 231 50 1,566 1,616 5.69
Strait.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Stock estimates from the most recent NMFS stock assessment reports, unless otherwise noted.
\b\ Proposed percentage to be taken refers to combined take by both Level B harassment and Level A harassment (where requested) for each individual
species/stock. If there is more than one stock of a species, the percent of stock is also calculated as if all takes occurred to a single stock.
\c\ Although different stocks of humpback whales could be present, PSOs would likely be unable to identify to the stock-level. Given this, NMFS will
count any takes for humpback whales as a single group, not by stocks.
[[Page 60675]]
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. NMFS regulations require applicants for incidental take
authorizations (ITA) to include information about the availability and
feasibility (economic and technological) of equipment, methods, and
manner of conducting the activity or other means of effecting the least
practicable adverse impact upon the affected species or stocks, and
their habitat (50 CFR 216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to
ensure the least practicable adverse impact on species or stocks and
their habitat, as well as subsistence uses where applicable, NMFS
considers two primary factors:
(1) The manner in which, and the degree to which, the successful
implementation of the measure(s) is expected to reduce impacts to
marine mammals, marine mammal species or stocks, and their habitat, as
well as subsistence uses. This considers the nature of the potential
adverse impact being mitigated (likelihood, scope, range). It further
considers the likelihood that the measure will be effective if
implemented (probability of accomplishing the mitigating result if
implemented as planned), the likelihood of effective implementation
(probability implemented as planned), and;
(2) The practicability of the measures for applicant
implementation, which may consider such things as cost, and impact on
operations.
The mitigation requirements described in the following were
proposed by ADOT&PF in its adequate and complete application or are the
result of subsequent coordination between NMFS and ADOT&PF. ADOT&PF has
agreed that all of the mitigation measures are practicable. NMFS has
fully reviewed the specified activities and the mitigation measures to
determine if the mitigation measures would result in the least
practicable adverse impact on marine mammals and their habitat, as
required by the MMPA, and has determined the proposed measures are
appropriate. NMFS describes these below as proposed mitigation
requirements and has included them in the proposed IHA.
In addition to the measures described later in this section,
ADOT&PF would be required to follow these general mitigation measures:
<bullet> Takes proposed for authorization, by Level A harassment
and Level B harassment only, would be limited to the species and
numbers listed in table 14. Construction activities would be required
to be halted upon observation of either a species for which incidental
take was not authorized or for a species for which incidental take has
been authorized but the number of takes has been met, entering or is
within the harassment zone, if the IHA is issued.
<bullet> The taking by serious injury or death of any of the
species listed in table 14 or any taking of any other species of marine
mammal would be prohibited and would result in the modification,
suspension, or revocation of the IHA, if issued. Any taking exceeding
the amounts proposed for authorization listed in table 14 would be
prohibited and would result in the modification, suspension, or
revocation of the IHA, if issued;
<bullet> Ensure that construction supervisors and crews, the marine
mammal monitoring team, and relevant ADOT&PF staff are trained prior to
the start of all construction activities, so that responsibilities,
communication procedures, marine mammal monitoring protocol, and
operational procedures are clearly understood. New personnel joining
during the project must be trained prior to commencing work;
<bullet> ADOT&PF, construction supervisors and crews, PSOs, and
relevant ADOT&PF staff must avoid direct physical interaction with
marine mammals during construction activities. If a marine mammal comes
within 10 m (32.8 ft) of such activity, operations must cease and
vessels must reduce speed to the minimum level required to maintain
steerage and safe working conditions, as necessary to avoid direct
physical interaction;
<bullet> Employ PSOs and establish monitoring locations as
described in the Protected Species Monitoring and Mitigation Plan
(PSMMP) (see NMFS' website). ADOT&PF must monitor the project area to
the maximum extent possible based on the required number of PSOs,
required monitoring locations, and environmental conditions;
<bullet> ADOT&PF also would abide by the reasonable and prudent
measures and terms and conditions of a Biological Opinion and
Incidental Take Statement, if issued by NMFS, pursuant to Section 7 of
the ESA; and
<bullet> ADOT&PF, in alignment with the PSMMP, would abide by
vessel measures related to North Pacific right whales (50 CFR
224.103(c)), Steller sea lions (50 CFR 224.103(d)), and humpback whales
(50 CFR 224.103(b), 50 CFR 223.214).
Additionally, the following mitigation measures apply to ADOT&PF's
in-water construction activities.
Pre- and Post-Activity Monitoring
ADOT&PF would be required to establish pre- and post-monitoring
zones with radial distances (based on the distances to the Level B
harassment threshold and feasibility for PSOs in the field) for all
construction activities (see table 14). Monitoring would take place
from 30 minutes prior to initiation of any pile driving activity (i.e.,
pre-start clearance monitoring) through 30 minutes post-completion of
pile driving activity. In addition, monitoring for 30 minutes would
take place whenever a break in the specified activity (i.e., impact
pile driving, vibratory pile driving) of 30 minutes or longer occurs.
Pre-start clearance monitoring would be conducted during periods of
visibility sufficient for the Lead PSO to determine that the shutdown
zones (indicated further below) are clear of marine mammals. Pile
driving may commence following 30 minutes of observation when the
determination is made that the shutdown zones are clear of marine
mammals.
Table 14--Proposed Monitoring Zones (in Meters) for all Marine Mammal Species
----------------------------------------------------------------------------------------------------------------
Largest Level B
Activity Pile type Installation method harassment monitoring
zone \a\
----------------------------------------------------------------------------------------------------------------
Trestle and Abutment
----------------------------------------------------------------------------------------------------------------
Trestle support pile................. 36-in steel pipe piles. Vibratory Installation. 11,659.2 m.
Impact Installation.... 1,584.9 m.
[[Page 60676]]
Temporary trestle pile............... 24-in to 36-in steel Vibratory Installation 11,659.2 m.
pipe or H-pile. and Removal.
Impact Installation.... 1,584.9 m.
----------------------------------------------------------------------------------------------------------------
Dock
----------------------------------------------------------------------------------------------------------------
Dock support pile.................... 36-in steel pipe pile.. Vibratory Installation. 11,659.2 m.
Impact Installation.... 1,584.9 m.
Temporary dock pile.................. 24-in to 36-in steel Vibratory Installation 11,659.2 m.
pipe pile. and Removal.
Impact Installation.... 1,584.9 m.
Fender pile.......................... 30-in steel pipe pile.. Vibratory Installation. 11,659.2 m.
Fender pile.......................... 24-in steel pipe pile.. Vibratory Installation. 5,411.7 m.
----------------------------------------------------------------------------------------------------------------
Dolphin
----------------------------------------------------------------------------------------------------------------
Dolphin pile......................... 36-in steel pipe pile.. Vibratory Installation. 11,659.2 m.
Impact Installation.... 1,584.9 m.
Temporary dolphin pile............... 24-in to 36-in steel Vibratory installation 11,659.2 m.
pipe pile. and removal.
----------------------------------------------------------------------------------------------------------------
Demolition (Removal)
----------------------------------------------------------------------------------------------------------------
Trestle removal...................... 16-in steel pipe pile.. Vibratory removal...... 5,411.7 m.
Dock removal......................... 16-in steel pipe pile.. Vibratory removal...... 5,411.7 m.
Dock removal......................... 26-in steel pipe pile.. Vibratory removal...... 11,659.2 m.
Dolphin removal...................... 16-in steel pipe pile.. Vibratory removal...... 5,411.7 m.
Fender removal....................... 20-in steel pipe pile.. Vibratory removal...... 5,411.7 m.
Fender removal....................... 16-in timber pile...... Vibratory removal...... 6,309.6 m.
----------------------------------------------------------------------------------------------------------------
\a\ Monitoring zones are measured from shore (where PSOs would be located) outward from each monitoring station.
Soft-Start
ADOT&PF would use soft start techniques when impact pile driving.
Soft-start requires contractors to provide an initial set of three
strikes at reduced energy, followed by a 30-second waiting period, then
two subsequent reduced-energy strike sets. A soft-start would be
implemented at the start of each day's impact pile driving and at any
time following cessation of impact pile driving for a period of 30
minutes or longer. Soft-start procedures are used to provide additional
protection to marine mammals by providing warning and/or giving marine
mammals a chance to leave the area prior to the hammer operating at
full capacity.
Establishment of Shutdown Zones
ADOT&PF would be required to establish shutdown zones with radial
distances, as identified in table 15 for all construction activities.
The purpose of a shutdown zone is generally to define an area within
which shutdown of the activity would occur upon sighting of a marine
mammal (or in anticipation of an animal entering the defined area).
Additionally, ADOT&PF would be required to shutdown in the event an
unauthorized species is present, to avoid take of that unauthorized
species. Shutdown zones would vary based on the activity type and
marine mammal hearing group.
If a marine mammal is observed entering or within the shutdown
zones indicated in table 15, pile driving activities must be delayed or
halted. If pile driving is delayed or halted due to the presence of a
marine mammal, the activity may not commence or resume until either the
animal has voluntarily exited and been visually confirmed beyond the
shutdown zones or a specific time period has passed without re-
detection of the animal (i.e., 30 minutes for cetaceans, 15 minutes for
pinnipeds). If a marine mammal comes within or approaches the shutdown
zone indicated in table 15, such operations must cease.
Table 15--Proposed Shutdown Zones (in Meters) for all Marine Mammal Species
--------------------------------------------------------------------------------------------------------------------------------------------------------
Shutdown zones \a\
-----------------------------------------------------
Activity Pile type Installation method Humpback Steller
whales, gray Killer Harbor Harbor sea
whales whales porpoise seals lions
--------------------------------------------------------------------------------------------------------------------------------------------------------
Trestle and Abutment
--------------------------------------------------------------------------------------------------------------------------------------------------------
Trestle support pile.................... 36-in steel pipe piles..... Vibratory Installation..... 60 20 50 70 30
Impact Installation........ 610 80 300 500 210
Temporary trestle pile.................. 24-in to 36-in steel pipe Vibratory Installation and 80 40 70 110 40
or H-pile. Removal.
Impact Installation........ \b\ 2,000 370 300 500 \b\ 300
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dock
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dock support pile....................... 36-in steel pipe pile...... Vibratory Installation..... 60 20 50 70 30
Impact Installation........ \b\ 2,000 370 300 500 \c\ 300
[[Page 60677]]
Temporary dock pile..................... 24-in to 36-in steel pipe Vibratory Installation and 80 40 70 110 40
pile. Removal.
Impact Installation........ \b\ 2,000 370 300 500 \c\ 300
Fender pile............................. 30-in steel pipe pile...... Vibratory Installation..... 50 20 40 60 20
Fender pile............................. 24-in steel pipe pile...... Vibratory Installation..... 30 10 20 30 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dolphin
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dolphin pile............................ 36-in steel pipe pile...... Vibratory Installation..... 80 40 70 110 40
Impact Installation........ \b\ 2,000 510 300 500 \d\ 300
Temporary dolphin pile.................. 24-in to 36-in steel pipe Vibratory installation and 60 20 50 70 30
pile. removal.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Demolition (Removal)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Trestle removal......................... 16-in steel pipe pile...... Vibratory removal.......... 40 20 30 50 20
Dock removal............................ 16-in steel pipe pile...... Vibratory removal.......... 440 20 30 50 20
Dock removal............................ 26-in steel pipe pile...... Vibratory removal.......... 80 30 70 100 40
Dolphin removal......................... 16-in steel pipe pile...... Vibratory removal.......... 30 10 20 30 20
Fender removal.......................... 20-in steel pipe pile...... Vibratory removal.......... 40 20 30 50 20
Fender removal.......................... 16-in timber pile.......... Vibratory removal.......... 50 20 40 60 20
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ A minimum shutdown zone of 10 m (32.8 ft) would be enforced to ensure animals are not endangered by any physical interaction with the construction
equipment (i.e., barge positioning operations, the positioning of piles via a crane (``stabbing'' the pile), the removal of piles via a crane
(deadpull), or the overwater slinging of construction materials).
\b\ While NMFS acknowledges that the Level A harassment zones are larger than the 2,000-meter monitoring zone, NMFS considers 2,000 meters a practicable
shutdown zone distance for LF cetaceans.
\c\ NMFS notes that this value was original 940 m (3,084 ft); however, given the size of Steller sea lions, NMFS suggested and the applicant accepted, a
more realistic shutdown zone for 300 m (984.3 ft) for these activities.
\d\ NMFS notes that this value was original 1,320 m (4,330.7 ft); however, given the size of Steller sea lions, NMFS suggested and the applicant
accepted, a more realistic shutdown zone for 300 m (984.3 ft) for these activities.
Bubble Curtain
ADOT&PF has not proposed, to utilize a bubble curtain during any of
the proposed pile driving activities presented herein due to
feasibility concerns related to the costs and time necessary to install
and operate the curtains. Time delays are impractical for the proposed
project due to the short field season available in the extreme
environment of the Aleutian Islands.
NMFS conducted an independent evaluation of the proposed measures,
and has preliminarily determined that the proposed mitigation measures
provide the means of effecting the least practicable impact on the
affected species or stocks and their habitat, paying particular
attention to rookeries, mating grounds, areas of similar significance,
and on the availability of such species or stock for subsistence uses.
Proposed Monitoring and Reporting
In order to issue an IHA for an activity, section 101(a)(5)(D) of
the MMPA states that NMFS must set forth requirements pertaining to the
monitoring and reporting of such taking. The MMPA implementing
regulations at 50 CFR 216.104(a)(13) indicate that requests for
authorizations must include the suggested means of accomplishing the
necessary monitoring and reporting that will result in increased
knowledge of the species and of the level of taking or impacts on
populations of marine mammals that are expected to be present while
conducting the activities. Effective reporting is critical both to
compliance as well as ensuring that the most value is obtained from the
required monitoring.
Monitoring and reporting requirements prescribed by NMFS should
contribute to improved understanding of one or more of the following:
<bullet> Occurrence of marine mammal species or stocks in the area
in which take is anticipated (e.g., presence, abundance, distribution,
density);
<bullet> Nature, scope, or context of likely marine mammal exposure
to potential stressors/impacts (individual or cumulative, acute or
chronic), through better understanding of: (1) action or environment
(e.g., source characterization, propagation, ambient noise); (2)
affected species (e.g., life history, dive patterns); (3) co-occurrence
of marine mammal species with the activity; or (4) biological or
behavioral context of exposure (e.g., age, calving or feeding areas);
<bullet> Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or cumulative impacts from multiple stressors;
<bullet> How anticipated responses to stressors impact either: (1)
long-term fitness and survival of individual marine mammals; or (2)
populations, species, or stocks;
<bullet> Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or other important physical components of
marine mammal habitat); and
<bullet> Mitigation and monitoring effectiveness.
ADOT&PF would abide by all monitoring and reporting measures
contained within the IHA, if issued, and their PSMMP (see NMFS'
website). The monitoring and reporting requirements described in the
following were proposed by ADOT&PF in its adequate and complete
application and/or are the result of subsequent coordination between
NMFS and ADOT&PF. ADOT&PF has agreed to the requirements. NMFS
describes these below as requirements and has included them in the
proposed IHA.
[[Page 60678]]
Visual Monitoring
All PSOs must be NMFS-approved. 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 (including relevant Alaska Native traditional
knowledge), 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.
Additionally, PSOs would be required to meet the following
qualifications:
<bullet> The ability to conduct field observations and collect data
according to assigned protocols;
<bullet> Experience or training in the field identification of
marine mammals, including the identification of behaviors;
<bullet> Sufficient training, orientation, or experience with the
construction operation to provide for personal safety during
observations;
<bullet> Writing skills sufficient to prepare a report of
observations including but not limited to:
(1) Number and species of marine mammals observed;
(2) Dates and times when in-water construction activities were
conducted;
(3) Dates, times, and reason for implementation of mitigation (or
why mitigation was not implemented when required); and
(4) Marine mammal behavior.
<bullet> The ability to communicate orally, by radio or in person,
with project personnel to provide real-time information on marine
mammals observed in the area as necessary.
ADOT&PF must establish monitoring locations, as described in PSMMP
(see NMFS' website). ADOT&PF must use a minimum of two PSOs. Where a
team of three or more PSOs is required, a lead observer (``Lead PSO'')
or monitoring coordinator would be designated. The lead observer must
have prior experience performing the duties of a PSO during
construction activity pursuant to a NMFS-issued ITA or Letter of
Concurrence.
For all pile driving activities, a minimum of one PSO must be
assigned to each active pile driving location to monitor the applicable
shutdown zones for the entirety of active construction operations (see
PSMMP). Given the maximum effective observation distance, PSOs would be
required to continuously monitor the entirety of the shutdown zones and
as much as possible of the Level B harassment zones given visibility
constraints, using binoculars and other resources to aid in
observation. At all locations, all PSOs, to the extent practicable,
must use an elevator platform at observation points to enhance
observation ability. PSOs would be required to 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
IHA, if issued.
Proposed Reporting
ADOT&PF would be required to submit an annual draft summary report
on all construction activities and marine mammal monitoring results to
NMFS within 90 days following the end of construction or 60 calendar
days prior to the requested issuance of any subsequent IHA for similar
activity at the same location, whichever comes first. The draft summary
report would include an overall description of construction work
completed, a narrative regarding marine mammal sightings, and
associated raw PSO data sheets (in electronic spreadsheet format).
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) how many and what type of piles were
driven or removed and the method (i.e., impact and vibratory); and (b)
the total duration of time for each pile (vibratory driving) or number
of strikes for each pile (impact driving);
<bullet> PSO locations during marine mammal monitoring; and
<bullet> Environmental conditions during monitoring periods (at
beginning and end of PSO shift and whenever conditions change
significantly), including Beaufort sea state and any other relevant
weather conditions including cloud cover, fog, sun glare, and overall
visibility to the horizon, and estimated observable distance.
Upon observation of a marine mammal, the following information 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 estimated 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);
<bullet> Number of marine mammals detected within the estimated
harassment zones, by species; and
<bullet> Detailed information about implementation of any
mitigation (e.g., shutdowns and delays), a description of specified
actions that occurred, and resulting changes in behavior of the
animal(s), if any.
If no comments are received from NMFS within 30 days after the
submission of the draft summary report, the draft report would
constitute the final report. If ADOT&PF received comments from NMFS, a
final summary report addressing NMFS' comments would be submitted
within 30 days after receipt of comments.
Reporting Injured or Dead Marine Mammals
In the event that personnel involved in ADOT&PF's activities
discover an injured or dead marine mammal, ADOT&PF would report the
incident to the NMFS Office of Protected Resources (OPR)
(<a href="/cdn-cgi/l/email-protection#3d6d6f1374696d137052535449524f54535a6f584d524f494e7d53525c5c135a524b"><span class="__cf_email__" data-cfemail="92c2c0bcdbc6c2bcdffdfcfbe6fde0fbfcf5c0f7e2fde0e6e1d2fcfdf3f3bcf5fde4">[email protected]</span></a>, <a href="/cdn-cgi/l/email-protection#85ccd1d5abd5eaf1e9eae6eec5ebeae4e4abe2eaf3"><span class="__cf_email__" data-cfemail="d59c8185fb85baa1b9bab6be95bbbab4b4fbb2baa3">[email protected]</span></a>) and to the
Alaska Regional Stranding Coordinator (877-925-7773) as soon as
feasible. If the death or injury was clearly caused by the specified
activity, ADOT&PF 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 IHA. ADOT&PF would not resume their activities
until notified by NMFS. The report would include the following
information:
<bullet> Description of the incident;
<bullet> Environmental conditions (e.g., Beaufort sea state,
visibility);
<bullet> Description of all marine mammal observations in the 24
hours preceding the incident;
[[Page 60679]]
<bullet> Photographs or video footage of the animal(s) (if
equipment is available).
<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; 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
of 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 these activities.
Impact pile driving for installation and vibratory pile driving for
installation and/or removal activities associated with the proposed
project, as outlined previously, have the potential to disturb or
displace marine mammals. Specifically, the specified activities may
result in take in the form of Level A harassment and/or Level B
harassment from underwater sounds generated from pile driving
installation and removal. Potential takes could occur if individuals of
these species are present in zones ensonified above the thresholds for
Level A harassment or Level B harassment identified above when these
activities are underway.
Given the nature of the proposed activities, NMFS does not
anticipate serious injury or mortality due to ADOT&PF's proposed
project, even in the absence of required mitigation. The Level A
harassment zones identified in table 10 are based upon an animal
exposed to vibratory pile driving and/or impact pile driving for
periods ranging from 20 to 60 minutes for in-water pile driving per
day. Overall, construction activities are not expected to exceed 12
hours per day (likely ranging between 10-12 hours but not all of that
would be spent actively pile driving). Exposures of this length are,
however, unlikely for vibratory driving for installation and/or
removal, given marine mammal movement throughout the area. Even during
impact driving scenarios, an animal exposed to the accumulated sound
energy would likely only experience limited AUD INJ at the lower
frequencies where pile driving energy is concentrated.
As stated in the Proposed Mitigation section, ADOT&PF would
implement shutdown zones that equal or exceed many of the Level A
harassment isopleths shown in table 15. Take by Level A harassment is
proposed for five marine mammal species/stocks. This is precautionary
to account for the potential that an animal could enter and remain
within the area between a Level A harassment zone and the shutdown zone
for long enough to be taken by Level A harassment. Additionally, in
some cases, this precaution would account for the possibility that an
animal could enter a shutdown zone without detection and remain in the
Level A harassment zone for a duration long enough to be taken by Level
A harassment before being observed and a shutdown occurring. That said,
any take by Level A harassment is expected to arise from, at most, a
small degree of AUD INJ because animals would need to be exposed to
higher levels and/or longer duration than are expected to occur here to
incur any more than a small degree of AUD INJ. Given the proximity to
shore and the secluded nature of the Bay, exposure over extended
periods of time are not considered likely to occur before the animal is
observed by PSOs and the proposed mitigation measures are implemented.
Additionally, and as noted previously, some subset of the individuals
that are behaviorally harassed could also simultaneously incur some
small degree of TTS for a short duration of time. Because of the small
degree anticipated, any AUD INJ or TTS potentially incurred here is not
expected to adversely affect an animal's individual fitness, let alone
annual rates of recruitment or survival.
For all species and stocks, take is expected to occur within a
limited, confined area (adjacent to the project site) of the stock's
range. The intensity and duration of take by Level A harassment and
Level B harassment would be expected to be minimized through the
proposed mitigation measures described herein. Furthermore, the amount
of take proposed for authorization is small compared to the relative
stock's abundance, even assuming that every take for any particular
species could wholly occur to individuals of an individual stock (where
estimates of the stocks population are available).
Behavioral responses of marine mammals to pile driving for pile
installation and/or pile removal at the project site, if any, are
expected to be mild, short-term, and temporary. Given that old piles
would be removed, temporary piles would be installed and then
subsequently removed, and new piles would be permanently installed over
231 days in total (not necessarily be consecutive) over 10 to 12 hours
per day, any harassment is expected to be temporary and intermittent.
Marine mammals within the Level B harassment zones may not show any
visual cues they are disturbed by activities or they could become
alert, avoid the area, leave the area, or display other mild responses
that are not observable, such as changes in vocalization patterns.
Additionally, many of the species present in this region would only be
present temporarily based on seasonal patterns or during active transit
between other habitats. Most likely, during pile driving, individuals
would be expected to move away from the sound source and be temporarily
displaced from the areas of pile driving throughout the duration of
pile driving activities. However, this reaction has been
[[Page 60680]]
observed primarily associated with impact pile driving. While vibratory
driving associated with the proposed project may produce sound at
distances of many kilometers from the project site, thus overlapping
with some likely less-disturbed habitat, the project site itself is
located in a busy harbor, and
[…truncated; see source link]Indexed from Federal Register on December 29, 2025.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.