Proposed Rule2025-14342
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Alaska LNG Project in Cook Inlet
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
July 29, 2025
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has received a request from 8 Star Alaska, LLC (8 Star Alaska), a subsidiary of Alaska Gasline Development Corporation (AGDC), for authorization to take marine mammals incidental to the Alaska Liquefied Natural Gas (LNG) Project in Cook Inlet, Alaska, over the course of 5 years (2026-2030). Pursuant to the Marine Mammal Protection Act (MMPA), NMFS proposes regulations setting forth permissible methods of taking, other means of effecting the least practicable adverse impact on such marine mammal stocks (i.e., mitigation measures), and requirements pertaining to monitoring and reporting such takes, and requests comments on the proposed regulations. NMFS will consider public comments prior to making any final decision on the promulgation of the requested MMPA regulations, and NMFS' responses to public comments will be summarized in the final notification of our decision.
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[Federal Register Volume 90, Number 143 (Tuesday, July 29, 2025)]
[Proposed Rules]
[Pages 35762-35814]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-14342]
[[Page 35761]]
Vol. 90
Tuesday,
No. 143
July 29, 2025
Part II
Department of Commerce
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National Oceanic and Atmospheric Administration
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50 CFR Part 217
Takes of Marine Mammals Incidental to Specified Activities; Taking
Marine Mammals Incidental to Alaska LNG Project in Cook Inlet; Proposed
Rule
Federal Register / Vol. 90 , No. 143 / Tuesday, July 29, 2025 /
Proposed Rules
[[Page 35762]]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
50 CFR Part 217
[Docket No. 250722-0128]
RIN 0648-BN50
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to Alaska LNG Project in Cook Inlet
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Proposed rule; request for comments.
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SUMMARY: NMFS has received a request from 8 Star Alaska, LLC (8 Star
Alaska), a subsidiary of Alaska Gasline Development Corporation (AGDC),
for authorization to take marine mammals incidental to the Alaska
Liquefied Natural Gas (LNG) Project in Cook Inlet, Alaska, over the
course of 5 years (2026-2030). Pursuant to the Marine Mammal Protection
Act (MMPA), NMFS proposes regulations setting forth permissible methods
of taking, other means of effecting the least practicable adverse
impact on such marine mammal stocks (i.e., mitigation measures), and
requirements pertaining to monitoring and reporting such takes, and
requests comments on the proposed regulations. NMFS will consider
public comments prior to making any final decision on the promulgation
of the requested MMPA regulations, and NMFS' responses to public
comments will be summarized in the final notification of our decision.
DATES: Comments and information must be received no later than August
28, 2025.
ADDRESSES: A plain language summary of this proposed rule is available
at <a href="https://www.regulations.gov/docket/NOAA-NMFS-2025-0141">https://www.regulations.gov/docket/NOAA-NMFS-2025-0141</a>. You may
submit comments on this document, identified by NOAA-NMFS-2025-0141, by
any of the following methods:
<bullet> Electronic Submission: Submit all electronic public
comments via the Federal e-Rulemaking Portal. Visit <a href="https://www.regulations.gov">https://www.regulations.gov</a> and type NOAA-NMFS-2025-0141 in the Search box.
Click on the ``Comment'' icon, complete the required fields, and enter
or attach your comments.
<bullet> Mail: Submit written comments to the Permits and
Conservation Division, Office of Protected Resources, National Marine
Fisheries Service, 1315 East-West Highway, Silver Spring, MD 20910-
3225.
<bullet> Fax: (301) 713-0376.
Instructions: Comments sent by any other method, to any other
address or individual, or received after the end of the comment period,
may not be considered by NMFS. All comments received are a part of the
public record and will generally be posted for public viewing on
<a href="https://www.regulations.gov">https://www.regulations.gov</a> without change. All personal identifying
information (e.g., name, address, etc.), confidential business
information, or otherwise sensitive information submitted voluntarily
by the sender will be publicly accessible. NMFS will accept anonymous
comments (enter ``N/A'' in the required fields if you wish to remain
anonymous).
A copy of 8 Star Alaska's Incidental Take Authorization (ITA)
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-oil-and-gas">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-oil-and-gas</a>. In case of problems accessing these
documents, please call the contact listed below.
FOR FURTHER INFORMATION CONTACT: Kristy Jacobus, Office of Protected
Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Purpose and Need for Regulatory Action
NMFS received a request from 8 Star Alaska requesting 5-year
regulations and a Letter of Authorization (LOA) that would authorize
take of marine mammals by Level A and Level B harassment incidental to
8 Star Alaska's activities. No serious injury or mortality is
anticipated or proposed to be authorized. Please see below for
definitions of relevant terms and the Estimated Take of Marine Mammals
section for definitions of harassment.
The proposed rule, promulgated under the authority of the MMPA (16
U.S.C. 1361 et seq.), would provide a framework for authorizing the
take of marine mammals incidental to construction activities associated
with 8 Star Alaska's LNG project, including impact and vibratory pile
driving and anchor handling.
Legal Authority for the Proposed Action
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, regulations are
promulgated (when applicable), and public notice and an opportunity for
public comment are provided.
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, the availability of the species or stocks for taking for
certain subsistence uses (referred to as ``mitigation''), and
requirements pertaining to the mitigation, monitoring and reporting of
the takings are set forth.
As noted above, no serious injury or mortality is proposed to be
authorized in this proposed rule. Relevant definitions of MMPA
statutory and regulatory terms are included below:
<bullet> Citizen--individual U.S. citizens or any corporation or
similar entity if it is organized under the laws of the United States
or any governmental unit defined in 16 U.S.C. 1362(13) (50 CFR
216.103);
<bullet> Take--to harass, hunt, capture, or kill, or attempt to
harass, hunt, capture, or kill any marine mammal (16 U.S.C. 1362; 50
CFR 216.3);
<bullet> Incidental taking--an accidental taking. This does not
mean that the taking is unexpected, but rather it includes those
takings that are infrequent, unavoidable, or accidental (50 CFR
216.103);
<bullet> Serious injury--any injury that will likely result in
mortality (50 CFR 216.3);
<bullet> Level A harassment--any act of pursuit, torment, or
annoyance which has the potential to injure a marine mammal or marine
mammal stock in the wild (16 U.S.C. 1362); and
<bullet> Level B harassment--any act of pursuit, torment, or
annoyance which 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 (16 U.S.C. 1362).
Section 101(a)(5)(A) of the MMPA and the implementing regulations
at 50 CFR part 216, subpart I, provide the legal basis for proposing
and, if appropriate, issuing 5-year regulations and
[[Page 35763]]
associated LOA(s). This proposed rule also proposes required
mitigation, monitoring, and reporting requirements for 8 Star Alaska's
activities.
Summary of Major Provisions Within the Proposed Rule
The major provisions of this proposed rule include:
<bullet> Allowing NMFS to authorize, through an LOA, the take of
small numbers of marine mammals by Level A harassment and/or Level B
harassment;
<bullet> No mortality or serious injury of any marine mammal is
proposed to be authorized;
<bullet> Requiring NMFS-approved protected species observers (PSOs)
and delaying commencement of or shutting down select activities should
a marine mammal be detected within identified clearance or shutdown
zones to minimize the amount and severity of take;
<bullet> Requiring time/area closure for beluga whale during summer
months in the western portion of Cook Inlet; and
<bullet> Requiring soft start for impact pile driving to allow
marine mammals the opportunity to leave the area prior to beginning
impact pile driving at full power.
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 216-6A, NMFS must
review our proposed action (i.e., promulgation of regulations and
subsequent issuance of a 5-year LOA) with respect to potential impacts
on the human environment.
NMFS participated as a cooperating agency on the 2020 Alaska LNG
Project Environmental Impact Statement (EIS), which was finalized on
March 6, 2020, and is available at <a href="https://www.ferc.gov/industries-data/natural-gas/environment/final-environmental-impact-statement-feis">https://www.ferc.gov/industries-data/natural-gas/environment/final-environmental-impact-statement-feis</a>.
When acting as a cooperating agency, as is the case with this project,
NMFS may satisfy its independent NEPA obligations by either preparing a
separate NEPA analysis for its issuance of an incidental take
authorization or, if appropriate, by adopting the NEPA analysis
prepared by the lead agency. NMFS independently reviewed and evaluated
the 2020 Alaska LNG Project EIS and determined it was adequate and
sufficient to meet our responsibilities under NEPA for the issuance of
the 2020 Alaska LNG Cook Inlet LOA (85 FR 59291, September 21, 2020).
NMFS therefore adopted the 2020 Alaska LNG Project EIS and signed a
Record of Decision on February 16, 2021.
Consistent with NEPA, applicable NOAA NEPA procedures, and the
information and analysis contained in this proposed rule, NMFS has made
a preliminary determination that this proposed rule and any subsequent
LOAs would not result in significant impacts that were not fully
considered in the 2020 Alaska LNG Project EIS. As indicated in this
proposed rule, 8 Star Alaska has made no substantial changes to the
activities evaluated in the EIS, and NMFS is unaware of any significant
new circumstances or information relevant to environmental concerns or
their impacts. NMFS will make a final NEPA determination prior to a
decision whether to issue a final rule and LOA.
Fixing America's Surface Transportation Act
This project is covered under Title 41 of the Fixing America's
Surface Transportation Act, or ``FAST-41.'' FAST-41 includes a suite of
provisions designed to expedite the environmental review for covered
infrastructure projects, including enhanced interagency coordination as
well as milestone tracking on the public-facing Permitting Dashboard.
FAST-41 also places a 2-year limitations period on any judicial claim
that challenges the validity of a Federal agency decision to issue or
deny an authorization for a FAST-41 covered project. 42 U.S.C. 4370m-
6(a)(1)(A).
8 Star Alaska's proposed project is listed on the permitting
dashboard. Milestones and schedules related to the environmental review
and permitting for the Alaska LNG Project can be found at <a href="https://www.permits.performance.gov/permitting-project/fast-41-covered-projects/alaska-lng-project">https://www.permits.performance.gov/permitting-project/fast-41-covered-projects/alaska-lng-project</a>.
Summary of Request
On December 5, 2024, NMFS received a request from 8 Star Alaska for
regulations and a LOA to take marine mammals incidental to construction
of LNG facilities in Cook Inlet, Alaska. Following NMFS' review of the
application, 8 Star Alaska submitted a revised version on April 3,
2025, which was deemed adequate and complete. On April 8, 2025, NMFS
published a notice of receipt (NOR) of application in the Federal
Register (90 FR 15137), requesting comments and information during a
30-day public comment period related to 8 Star Alaska's request. NMFS
received one letter from the Center for Biological Diversity and Cook
Inletkeeper providing substantive comments and approximately 14,000
comments from members of the public expressing general opposition to 8
Star Alaska's proposed project but providing no information relevant to
the information contained within 8 Star Alaska's application or to
NMFS' determination that the application is adequate and complete. The
comment letters from members of the public followed a generic template
format in which respondents provided comments that were identical or
substantively the same. NMFS has reviewed all submitted material and
taken the information into consideration during the drafting of this
proposed rule.
NMFS is proposing to authorize take of 12 species of marine mammals
by Level B harassment, and by Level A harassment for a subset of 3 of
these species. Neither 8 Star Alaska nor NMFS expect serious injury or
mortality to result from the specified activities and neither are
proposed to be authorized.
NMFS previously promulgated regulations and issued an LOA to AGDC
for the same work on September 15, 2020 (85 FR 59291, September 21,
2020), effective from January 1, 2021, through December 31, 2025.
However, no work has been conducted during the effective period of that
LOA and none is planned prior to its expiration.
Description of Proposed Activity
Overview
8 Star Alaska proposes to construct facilities to transport and
offload LNG in Cook Inlet, Alaska, for export. Project activities would
include the construction of a Marine Terminal comprised of a temporary
Marine Terminal Material Offloading Facility (MOF) and a permanent
Product Loading Facility (PLF) on the east side of Cook Inlet, near
Nikiski; construction of a pipeline (referred to as the Mainline)
across Cook Inlet; and construction of a Mainline MOF on the west side
of Cook Inlet, north of Tyonek. The components of the proposed
construction activities that have the potential to expose marine
mammals to sound levels that could result in take are vibratory and
impact pile driving of steel sheet piles and 24-, 48-, 60-, and 66-inch
(61-, 122-, 152.4-, and 167.6-centimer [cm]) steel pipe piles, as well
as the use of anchor handling tugs (AHTs).
Dates and Duration
Planned in-water work would occur over 5 years between January 1,
2026, and December 31, 2030. The construction window is based on the
ice-free working window, which is from approximately April 1 through
October 31. Pile driving would occur during
[[Page 35764]]
daylight hours and is estimated to occur 6 days per week. Work for
pipelaying would occur 24 hours per day, 7 days per week, and could
occur during periods of low visibility. In-water pile-driving is
expected to occur over an estimated 323 nonconsecutive days over the 5-
year period, and use of AHTs used for pipelaying in construction of the
Mainline is expected to occur over an estimated 55 nonconsecutive days
during Years 3 and 4 of the project, for a total of 378 construction
days over the 5 year period (See table 1).
Table 1--Estimated Construction Schedule
------------------------------------------------------------------------
Estimated
Construction element number of days
------------------------------------------------------------------------
Year 1
------------------------------------------------------------------------
Marine Terminal MOF..................................... 78
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Year 2
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Marine Terminal MOF..................................... 69
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Mainline MOF............................................ 14
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Year 3
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PLF..................................................... 74
Mainline................................................ 2
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Year 4
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Mainline................................................ 53
PLF..................................................... 52
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Year 5
------------------------------------------------------------------------
PLF..................................................... 36
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Total............................................... 378
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Specified Geographical Region
The proposed construction activities would occur in Cook Inlet,
Alaska. The Marine Terminal, consisting of the temporary marine
terminal MOF and PLF, would be constructed adjacent to the proposed
onshore liquefaction facility near Nikiski, Alaska. The Mainline would
cross the Cook Inlet shoreline on the west side of Cook Inlet south of
Beluga Landing, traverse Cook Inlet in a generally southward direction
for approximately 26.7 miles (43 kilometers [km]), and cross the east
Cook Inlet shoreline near Suneva Lake. An MOF (Mainline MOF) may be
constructed on the west side of Cook Inlet near the existing Beluga
Landing to support installation of the Cook Inlet shoreline crossing.
See figure 1 for a map of 8 Star Alaska's action area (see 8 Star
Alaska's application for color legends).
BILLING CODE 3510-22-P
[[Page 35765]]
[GRAPHIC] [TIFF OMITTED] TP29JY25.004
BILLING CODE 3510-22-C
Detailed Description of the Specified Activity
Construction of the Alaska LNG facilities would include
construction of a Marine Terminal, comprised of a temporary marine
terminal MOF and PLF; a Mainline MOF; and a pipeline (referred to as
Mainline) crossing Cook Inlet. Noise generated by impact and vibratory
pile driving would be likely to result in take of marine mammals.
Additionally, we assume here that noise generated by AHTs conducting
anchor handling may result in take of marine mammals.
[[Page 35766]]
Temporary Marine Terminal Material Offloading Facility
The temporary Marine Terminal MOF would consist of a quay and two
berths, which would be used during construction of the Liquefaction
Facility to enable direct deliveries of equipment modules, bulk
materials, construction equipment, and other cargo to minimize the
transport of large and heavy loads over road infrastructure. See Figure
6 in 8 Star Alaska's application for visual depiction of the Marine
Terminal MOF. Construction of the Temporary MOF is expected to occur in
Years 1 and 2.
Quay--The quay would be constructed of an outer wall consisting of
combi-wall (combination of sheet pile and 66-inch steel pipe piles),
tied back to a sheet pile anchor wall, and 11 sheet pile coffer cells,
comprised of sheet piles and 24-inch pipe piles, backfilled with
granular materials. The 24-inch pipe piles would be removed once coffer
cell installation is complete. All pile installation and removal would
be conducted with vibratory methods. 8 Star Alaska expects to use two
crews during the installation of piles for the combi-wall and coffer
cells, and therefore concurrent pile driving is expected to occur
during installation of these features. This could result in concurrent
vibratory pile driving of two 66-inch sheet piles, 2 sheet piles, 2 24-
inch pile piles, a 66-inch pipe pile with a sheet pile, and a 24-inch
pipe pile with a sheet pile. Installation of the sheet pile anchor wall
is not considered in this analysis because the anchor wall would be
installed into fill and would not generate substantial underwater
sound.
Berths--Berths at the Marine Terminal MOF would include one Lift-
on/Lift-off (Lo-Lo) berth and one Roll-on/Roll-off (Ro-Ro) berth
maintained at depths alongside of 32 feet Mean Lower Low Water (MLLW).
The berths would be constructed of 24-inch and 48-inch pipe piles using
an impact hammer.
The Marine Terminal MOF would be constructed using both land-based
(from shore and subsequently from constructed portions of the Marine
Terminal MOF) and marine construction methods.
Dredging would be conducted at the Marine Terminal MOF with
hydraulic or mechanical dredgers. While marine mammals may behaviorally
respond in some small degree to the noise generated by dredging
operations, given the slow, predictable movements of these vessels, and
absent any other contextual features that would cause enhanced concern,
NMFS does not consider it likely that 8 Star Alaska's proposed dredging
would result in the take of marine mammals.
Product Loading Facility (PLF)
The proposed PLF would be a permanent facility used to load LNG
carriers for export. The PLF would consist of two loading platforms,
two berths, a marine operations platform, and an access trestle that
supports the piping that delivers LNG from shore. See figure 4 in 8
Star Alaska's application for a visual description. In-water
construction for the PLF would occur in Years 3-5. Construction methods
would include both overhead construction (conducted with equipment
located on a cantilever bridge extending from shore) and marine
construction (conducted with equipment located on barges/vessels). All
pile driving for the PLF would be conducted with an impact hammer. See
figures 3 through 5 in 8 Star Alaska's application for visual depiction
of the PLF.
PLF Berth Loading Platforms--The two loading platforms, located at
either end of the north-south portion of the trestle would be supported
above the seafloor on steel-jacketed structures called quadropods, made
of 48-inch steel pipe piles.
PLF Berth Breasting and Mooring Dolphins--Each berth would have
four concrete pre-cast breasting dolphins and six concrete pre-cast
mooring dolphins that would be supported over the seabed on quadropods,
comprised of 48-inch and 60-inch steel pipe piles. A catwalk, supported
on two-pile bents comprised of 60-inch steel pipe piles, would connect
the mooring dolphins to the loading platforms.
Marine Operations Platform--The platform would be located along the
east-west portion of the access trestle and would be supported above
the seafloor on four-pile bents, comprised of 60-inch steel pipe piles.
Access Trestle--The access trestle would be T-shaped with a long
east-west oriented section and a shorter north-south oriented section.
The east-west portion would be supported on three-pile and four-pile
bents, comprised of 60-inch steel pipe piles, and the north-south
oriented portion would be supported on five-pile quadropods, comprised
of 48-inch steel pipe piles.
Mainline MOF
A Mainline MOF may be required on the west side of Cook Inlet to
support installation of the Cook Inlet shoreline crossing. The Mainline
MOF would consist of a quay, space for tugs, and berths including a Lo-
Lo berth for unloading pipe and construction material and Ro-Ro berth
and ramp dedicated to Ro-Ro operations. Approximately 1,270 feet (387.1
meters [m]) of sheet pile would be installed with a combination of
vibratory and impact methods for construction of the quay and Ro-Ro
ramp, and a corresponding length of sheet pile would be installed as
anchor wall. However, only 670 feet (204.2 m) of sheet pile would be
installed in the water, as the remainder would be installed as anchor
wall in fill material or in the intertidal area when the tide is out.
Therefore, only the installation of these 670 feet (204.2 m) of sheet
pile is likely to result in the take of marine mammals. Construction of
the Mainline MOF is expected to occur in Year 2.
Mainline Crossing Cook Inlet
8 Star Alaska proposes to install a 42-inch-diameter natural gas
pipeline that would cross Cook inlet from the west side of the inlet
south of Beluga Landing in a generally southward direction to the east
side of Cook Inlet near Suneva Lake. The pipe would be trenched into
the seafloor and buried from the shoreline out to a water depth of
approximately 35-45 feet (10.7-13.7 m) MLLW on both sides of the inlet,
approximately 8,800 feet from the north landfall and 6,600 feet from
the south landfall. Burial depth in these areas would be 3-6 feet (0.9-
1.8 m). Seaward of these sections, the pipeline would be placed on the
seafloor. The installation methods would vary depending on the distance
from shore, as described below. Installation of the Mainline crossing
of Cook Inlet would include AHTs engaged in anchor handling (described
further below). Construction of the Mainline is expected to occur
during Years 3 and 4.
Pre-installation surveys--High-resolution geophysical surveys would
be conducted prior to pipeline construction in order to develop a
detailed bathymetric profile. The acoustic survey equipment proposed
for use includes:
<bullet> Single-beam echosounder operating at 200 kilohertz (kHz);
<bullet> Multi-beam echosounder operating at 200-400 kHz;
<bullet> Side-scan sonar system at 400-900 kHz; and
<bullet> Magnetometer, which does not emit underwater sound.
The echosounders and side-scan sonar operate at or above 200 kHz,
which are above the range of marine mammals' hearing thresholds, and
the magnetometer does not emit sound. Therefore, use of this equipment
is not expected to result in take of marine
[[Page 35767]]
mammals, and it is not further evaluated in this proposed rule.
Nearshore Trenching, Pipelay, and Burial--In the nearshore portions
of the route across Cook Inlet, the pipeline would be trenched and
buried. The nearshore portion of the trench (extending from the
shoreline to a transition water depth where a dredge vessel can be
employed) would be constructed using amphibious or barge-based
excavators. From the transition water depth to water depth of the -25
feet or -45 feet MLLW, 8 Star Alaska would use a dredge to excavate a
trench for the pipeline. As described above, NMFS does not consider it
likely that 8 Star Alaska's proposed dredging would result in the take
of marine mammals.
Pipeline joints would be welded together onshore in 1,000 foot-long
strings (pipe strings) and laid on the ground surface in an orientation
that approximates the offshore alignment. 8 Star Alaska would anchor a
pipe pull barge near the seaward end of the trench using AHTs. The
barge would be used to pull the pipe strings from their onshore
position into the trench. Given the transient and slow, predictable
movement of barges, NMFS does not expect any potential for startle
responses from individual marine mammals that may be in the vicinity.
Similarly, with regard to the characteristics of noise output resulting
from use of barges and other, similar industrial activities, NMFS
generally assumes that the relative lack of variation in the signal and
associated absence of high peak pressure or rapid rise time events
(characteristics associated with impulsive and/or intermittent sound
sources) significantly limits the likelihood of behavioral responses
that might appropriately be considered take.
In addition to these general conclusions related to the physical
and acoustic characteristics of the activity, NMFS considers contextual
issues that may result in different, case-specific conclusions. For
example, when considering relatively loud continuous noise sources,
such as use of AHTs or tugging under load, NMFS evaluates the potential
for exposure to result in take for sensitive species such as Cook Inlet
beluga whales in important habitat is sufficient to justify a
determination that some amount of take is likely. Following pipeline
installation, the trench is expected to backfill naturally through the
movement of seafloor sediments. If manual backfilling is required, the
backfill would be placed by reversing the flow of the dredger used
offshore or mechanically with the use of excavators.
Trenching, pipelay, and burial would be conducted 24 hours per day,
seven days per week. 8 Star Alaska anticipates a pipelay rate of 2,000
(609.6 m) to 2,500 feet (762 m) per 24 hours. Anchor handling is only
expected to occur during the initial anchoring of the pull barge, and
therefore the AHTs are only expected to be used for a total of two days
during nearshore pipelay, one day on the west coast near Beluga and one
day on the east coast near Suneva Lake. We note here that AHT
activities are not generally dissimilar from dredging, pipe-pulling,
etc., in terms of the characteristics of noise output, although AHTs
are assumed to be louder than these other similar activities. Given the
slow, predictable, and generally straight path (or stationary nature)
of tugs engaged in anchor handling activities, the likelihood of
disrupting marine mammal behavioral patterns from tug use that would
qualify as harassment under the MMPA is considered relatively low.
Nevertheless, we have quantified the potential exposures from this
activity, assumed that these exposures would equate to take, and
analyzed the impacts of the assumed takes, which we propose for
authorization. Anchor handling is the only activity assumed to result
in take of marine mammals during the nearshore trenching, pipelay, and
burial.
Offshore Pipeline Installation--Seaward of the trenched sections,
the pipeline would be laid on the seafloor across Cook Inlet using
conventional pipelay vessel methods. The pipelay vessel would likely
employ 12 anchors to keep it positioned during pipelay and provide
resistance as it is winched ahead 80 feet each time an additional 80-
foot section of pipe is added/welded on the pipe string. 8 Star Alaska
anticipates a pipelay rate of 2,000 to 2,500 feet (609.6-762 m) per 24
hours. 8 Star Alaska would use AHTs to reposition the anchors. Use of
the AHTs could potentially result in take of marine mammals and is
described in more detail below. Offshore pipelaying would be conducted
for 24 hours per day, 7 days per week. 8 Star Alaska anticipates using
AHTs about 25 percent of the time (i.e., approximately 6 hours per
day).
AHTs--8 Star Alaska would use AHTs and anchor systems to maintain
the optimal stability and alignment of a specialized vessel, referred
to as a pipelay barge, while laying pipeline on the seafloor. Pipeline
activities utilizing pipelay barge methods include support from up to
three AHTs that would repeatedly reposition the anchors, thereby
maintaining proper position and permitting forward movement.
8 Star Alaska is unable to specify tugging characteristics at this
time. However, based on specifications for other similar activities
such as Hilcorp Alaska's LLC's Production Drilling Support Activities
in Cook Inlet (89 FR 79529; September 30, 2024) and Furie Operating
Alaska, LLC Natural Gas Activities in Cook Inlet (89 FR 77836;
September 24, 2024), NMFS anticipates that the AHTs would be rated
between 4,000 horsepower (hp) and 8,000 hp. Potential tug power output
during anchor handling is discussed in further detail in the Estimated
Take of Marine Mammals section.
A summary of pile driving activities for the Alaska LNG facilities
construction is provided in table 2, and a summary of the use of AHTs
for pipelaying is provided in table 3.
Table 2--Anticipated In-Water Pile Driving Schedule
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of steel pipe piles or length of sheet piles
-----------------------------------------------------------------
Section Element 24-inch 48-inch 60-inch 66-inch Hammer type # days
steel pipe steel pipe steel pipe steel pipe Sheet piles
--------------------------------------------------------------------------------------------------------------------------------------------------------
Year 1
--------------------------------------------------------------------------------------------------------------------------------------------------------
Marine Terminal MOF............. Combi-wall......... ........... ........... ........... 70 144 Vibratory.......... 22
Marine Terminal MOF............. Coffer cell........ 48 ........... ........... ........... 1,496 Vibratory.......... 56
--------------------------------------------------------------------------------------------------------------------------------------------------------
Year 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Marine Terminal MOF............. Coffer cell........ 40 ........... ........... ........... 1,491 Vibratory.......... 54
Marine Terminal MOF............. Ro-Ro/Lo-Lo berths. 7 28 ........... ........... ........... Impact............. 14
Mainline MOF.................... Quay............... ........... ........... ........... ........... 205 Vibratory/Impact... 10
[[Page 35768]]
Mainline MOF.................... Ro-Ro ramp......... ........... ........... ........... ........... 87 Vibratory/Impact... 4
--------------------------------------------------------------------------------------------------------------------------------------------------------
Year 3
--------------------------------------------------------------------------------------------------------------------------------------------------------
PLF............................. E-W Trestle........ ........... ........... 73 ........... ........... Impact............. 42
PLF............................. Berth Loading ........... 40 ........... ........... ........... Impact............. 16
Platforms.
PLF............................. N-S Trestle........ ........... 40 ........... ........... ........... Impact............. 16
--------------------------------------------------------------------------------------------------------------------------------------------------------
Year 4
--------------------------------------------------------------------------------------------------------------------------------------------------------
PLF............................. E-W Trestle........ ........... ........... 28 ........... ........... Impact............. 14
PLF............................. Operations Platform ........... ........... 12 ........... ........... Impact............. 6
PLF............................. Breasting Dolphin.. ........... 8 32 ........... ........... Impact............. 16
PLF............................. Mooring Dolphin.... ........... 2 8 ........... ........... Impact............. 4
PLF............................. N-S Trestle........ ........... 30 ........... ........... ........... Impact............. 12
--------------------------------------------------------------------------------------------------------------------------------------------------------
Year 5
--------------------------------------------------------------------------------------------------------------------------------------------------------
PLF............................. Mooring Dolphin.... ........... 10 40 ........... ........... Impact............. 20
PLF............................. Catwalk............ ........... ........... 8 ........... ........... Impact............. 16
--------------------------------------------------------------------------------------------------
Total....................... ................... 73 158 236 70 3,423 ................... 323
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table 3--Schedule of Anchor Handling for Construction of Mainline Across
Cook Inlet
------------------------------------------------------------------------
Activity Hours/day Days
------------------------------------------------------------------------
Year 3
------------------------------------------------------------------------
Nearshore pipelay................................. 6 2
------------------------------------------------------------------------
Year 4
------------------------------------------------------------------------
Offshore pipelay.................................. 6 53
------------------------------------------------------------------------
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 4 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' U.S. Alaska and Pacific SARs. All values presented in table 4 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 4--Species \1\ 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/
\2\ abundance survey) \3\ SI \4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Artiodactyla--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):
Fin Whale....................... Balaenoptera physalus.. Northeast Pacific...... E, D, Y 11,065 (0.405 7,970, UND 0.6
2013) \5\.
Humpback Whale.................. Megaptera novaeangliae. Hawai[revaps]i......... -, -, N 11,278 (0.56, 7,265, 127 27.09
2020).
Humpback Whale.................. Megaptera novaeangliae. Mexico-North Pacific... T, D, Y N/A \6\ (N/A, N/A, UND 0.57
2006).
[[Page 35769]]
Humpback Whale.................. Megaptera novaeangliae. Western North Pacific.. E, D, Y 1,084 (0.088, 1,007, 3.4 5.82
2006).
Minke Whale..................... Balaenoptera Alaska................. -, -, N N/A \7\ (N/A, N/A, N/ UND 0
acutorostrata. A).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
Killer Whale.................... Orcinus orca........... Eastern North Pacific -, -, N 1,920 (N/A, 1,920, 19 1.3
Alaska Resident. 2019).
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.
Pacific White-Sided Dolphin..... Lagenorhynchus North Pacific.......... -, -, N 26,880 (N/A, N/A, UND 0
obliquidens. 1990).
Family Monodontidae (white whales):
Beluga Whale.................... Delphinapterus leucas.. Cook Inlet............. E, D, Y 331 (0.076, 311, 2022) ......... 0
Family Phocoenidae (porpoises):
Dall's Porpoise................. Phocoenoides dalli..... Alaska................. -, -, N UND \8\ (UND, UND, UND 37
2015).
Harbor Porpoise................. Phocoena............... Gulf of Alaska......... -, -, Y 31,046 (0.21, N/A, UND 72
1998).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Carnivora--Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
sea lions):
California Sea Lion............. Zalophus californianus. U.S.................... -, -, N 257,606 (N/A, 233,515, 14,011 >321
2014).
Steller Sea Lion................ Eumetopias jubatus..... Western................ E, D, Y 49,837 \9\ (N/A, 299 267
49,837, 2022).
Family Phocidae (earless seals):
Harbor Seal..................... Phoca vitulina......... Cook Inlet/Shelikof -, -, N 28,411 (N/A, 26,907, 807 107
Strait. 2018).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on Taxonomy
(<a href="https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/">https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/</a>).
\2\ 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 which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\3\ NMFS marine mammal stock assessment reports online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region</a>. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\4\ These values, found in NMFS' SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial
fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range.
\5\ The best available abundance estimate for this stock is not considered representative of the entire stock as surveys were limited to a small portion
of the stock's range.
\6\ NMFS's abundance estimate for this stock is greater than eight years old and not considered current. PBR is therefore considered undetermined for
this stock, as there is no current minimum abundance estimate for use in calculation. We nevertheless present the most recent abundance estimate as
the best available information.
\7\ Reliable population estimates are not available for this stock.
\8\ The best available abundance estimate is likely an underestimate for the entire stock because it is based upon a survey that covered only a small
portion of the stock's range.
\9\ Nest is best estimate of counts, which have not been corrected for animals at sea during abundance surveys. Estimates provided are for the U.S.
only. The overall Nmin is 73,211 and overall PBR is 439.
As indicated above, all 12 species (with 15 managed stocks) in
table 4 temporally and spatially co-occur with the activity to the
degree that take is reasonably likely to occur.
In addition, the northern sea otter may be found in Cook Inlet,
Alaska. However, northern sea otters are managed by the U.S. Fish and
Wildlife Service and are not considered further in this document.
Gray Whale
The stock structure for gray whales in the Pacific has been studied
for a number of years and remains uncertain as of the most recent draft
2024 Pacific SARs (Carretta et al., 2025). Gray whale population
structure is not determined by simple geography and may be in flux due
to evolving migratory dynamics (Carretta et al., 2024). Currently, the
SARs delineate a western North Pacific (WNP) gray whale stock and an
eastern North Pacific (ENP) stock based on genetic differentiation
(Carretta et al., 2025). WNP gray whales are not known to feed in or
travel to upper Cook Inlet (Conant and Lohe, 2023, Weller et al.,
2023). Therefore, we assume that gray whales near the project area are
members of the ENP stock.
An Unusual Mortality Event (UME) for gray whales along the West
Coast and in Alaska occurred from December 17, 2018, through November
9, 2023. During that time 690 gray whales stranded in the United
States, Mexico, and Canada, 146 of which stranded off the coast of
Alaska. The investigative team concluded that the preliminary cause of
the UME was localized ecosystem changes in the whale's Subarctic and
Arctic feeding areas that led to changes in food, malnutrition,
decreased birth rates, and increased mortality (see <a href="https://www.fisheries.noaa.gov/national/marine-life-distress/2019-2023-gray-whale-unusual-mortality-event-along-west-coast-and">https://www.fisheries.noaa.gov/national/marine-life-distress/2019-2023-gray-whale-unusual-mortality-event-along-west-coast-and</a> for more
information).
Gray whales occur infrequently in Cook Inlet, but may be seasonally
present during spring and fall in the lower inlet (Bureau of Ocean
Energy Management (BOEM), 2022). Migrating gray whales pass through the
lower inlet during their spring and fall migrations to and from their
primary summer feeding areas in the Bering, Chukchi, and Beaufort seas
(Swartz, 2018, Silber et al., 2021, Bureau of Ocean Energy Management
(BOEM), 2022). Several surveys and monitoring programs have sighted
gray whales in lower Cook Inlet (Shelden et al., 2013, Owl Ridge, 2014,
Lomac-MacNair et al., 2013, 2014,
[[Page 35770]]
Kendall et al., 2015). Gray whales are occasionally seen in mid- and
upper Cook Inlet, Alaska, but they are not common. During NMFS aerial
surveys conducted in June 1994, 2000, 2001, 2005, and 2009, gray whales
were observed in Cook Inlet near Port Graham and Elizabeth Island as
well as near Kamishak Bay, with one gray whale observed as far north as
the Beluga River (Shelden et al., 2013). Gray whales were also observed
offshore of Cape Starichkof in 2013 by marine mammal observers
monitoring Buccaneer's Cosmopolitan drilling project (Owl Ridge, 2014)
and in middle Cook Inlet in 2014 during the 2014 Apache 2D seismic
survey (Lomac-MacNair et al., 2015). Several projects performed in Cook
Inlet in recent years reported no observations of gray whales. These
project activities included the SAExploration seismic survey in 2015
(Kendall and Cornick, 2015), the 2018 Cook Inlet Pipeline (CIPL)
Extension Project (Sitkiewicz et al., 2018), and the 2019 Hilcorp
seismic survey in lower Cook Inlet (Fairweather Science, 2020).
In 2020, during the aforementioned UME, a young male gray whale was
stranded in the Twentymile River near Girdwood for over a week before
swimming back into Turnagain Arm. The whale did not survive and was
found dead in west Cook Inlet later that month (NMFS, 2020). One gray
whale was sighted in Knik Arm near the Port of Alaska (POA) in
Anchorage in upper Cook Inlet in May of 2020 during observations
conducted during construction of the Petroleum and Cement Terminal
project (61 North Environmental, 2021). The sighting occurred less than
a week before the reports of the gray whale stranding in the Twentymile
River and was likely the same animal. In 2021, one small gray whale was
sighted in Knik Arm near Ship Creek, south of the POA (61 North
Environmental, 2022a). Although some sightings have been documented in
the middle and upper Inlet, the gray whale range typically only extends
into the lower Cook Inlet region.
Humpback Whale
The most comprehensive photo-identification data available suggest
that approximately 89 percent of all humpback whales in the Gulf of
Alaska are from the Hawaii stock, 11 percent are from the Mexico stock,
and less than 1 percent are from the Western North Pacific stock (Wade,
2021). Individuals from different stocks are known to intermix in
feeding grounds. There is no designated critical habitat for humpback
whales in or near the area where the specified activity is planned to
occur (86 FR 21082, April 21, 2021), nor does the project overlap with
any known biologically important areas (Wild et al., 2023).
Humpback whales are encountered regularly in lower Cook Inlet and
occasionally in mid-Cook Inlet; sightings are rare in upper Cook Inlet.
Eighty-three groups containing an estimated 187 humpbacks were sighted
during Cook Inlet beluga whale aerial surveys conducted by NMFS from
1994 to 2012 (Shelden et al., 2013). Surveys conducted north of the
forelands have documented small numbers in middle Cook Inlet. During
the 2014 Apache seismic surveys in Cook Inlet, five groups (six
individuals) were reported, with three groups north of the forelands on
the east side of the inlet (Lomac-MacNair et al., 2014). In 2015,
during the construction of the Furie Operating Alaska, LLC (Furie)
platform and pipeline, four groups of humpback whales were documented.
Another group of 6 to 10 unidentified whales, thought to be either
humpback or gray whales, was sighted approximately 15 km northeast of
the Julius R. Platform Large cetaceans were visible near the project
(i.e., whales or blows were visible) for 2 hours out of the 1,275 hours
of observation conducted (Jacobs Engineering Group Inc., 2015).
Minke Whale
No estimates have been made for the number of minke whales in the
entire North Pacific (Young et al., 2024). However, some information is
available on the number of minke whales in some areas of Alaska. Visual
surveys for cetaceans were conducted on the eastern Bering Sea shelf in
2002, 2008, and 2010 in cooperation with research on commercial
fisheries (Friday et al., 2013). Results of the surveys in 2002, 2008,
and 2010 provided provisional abundance estimates of 389 (CV-0.52), 517
(CV = 0.69), and 2,020 (CV = 0.73) minke whales on the eastern Bering
Sea shelf, respectively (Friday et al., 2013). These estimates are
considered provisional because they have not been corrected for animals
missed on the trackline, animals submerged when the ship passed, or
responsive movement. Additionally, line transect surveys were conducted
in shelf and nearshore waters (within 30-45 nautical miles of land) in
2001-2003 from the Kenai Fjords in the Gulf of Alaska to the central
Aleutian Islands. Minke whale abundance was estimated to be 1,233 (CV =
0.34) for this area (Zerbini et al., 2006). This estimate has also not
been corrected for animals missed on the trackline. The majority of the
sightings were in the Aleutian Islands, rather than in the Gulf of
Alaska, and in water shallower than 200 m. So few minke whales were
seen during three offshore Gulf of Alaska surveys for cetaceans in
2009, 2013, and 2015 that a population estimate for the species in this
area could not be determined (Rone et al., 2017). These estimates
cannot be used as an estimate of the entire Alaska stock of minke
whales because only a portion of the stock's range was surveyed (Young
et al., 2024).
Minke whales are most abundant in the Gulf of Alaska during summer
and occupy localized feeding areas (Zerbini et al., 2006). During the
NMFS annual and semiannual surveys of Cook Inlet, minke whales were
observed near Anchor Point in 1998, 1999, 2006, and 2021 (Shelden et
al., 2013, 2015b, 2017, 2022, Shelden and Wade, 2019) and near
Ninilchik and the middle of lower Cook Inlet in 2021 (Shelden et al.,
2022). Minke whales were sighted southeast of Kalgin Island and near
Homer during Apache's 2014 survey (Lomac-MacNair et al., 2014), and one
was observed near Tuxedni Bay in 2015 (Kendall et al., 2015 as cited in
Weston and SLR 2022). During Hilcorp's seismic survey in lower Cook
Inlet in the fall of 2019, eight minke whales were observed
(Fairweather Science, 2020). In 2018, no minke whales were observed
during observations conducted for the CIPL project near Tyonek
(Sitkiewicz et al., 2018). Minke whales were also not recorded during
Hilcorp's aerial or rig-based monitoring efforts in 2023 (Horsley and
Larson, 2023).
Fin Whale
Fin whales' range extends into lower Cook Inlet; however, sightings
are infrequent, and they are mostly spotted near the Inlet's entrance.
Fin whales are usually observed as individuals traveling alone,
although they are sometimes observed in small groups. From 2000 to
2022, 10 sightings of 26 estimated individual fin whales were observed
in lower Cook Inlet during NMFS aerial surveys (Shelden et al., 2013,
2015b, 2017, 2022, Shelden and Wade, 2019). In the fall of 2019 during
Hilcorp's seismic survey in lower Cook Inlet, 8 sightings of 23 fin
whales were documented, suggesting greater numbers may use the area in
the fall than previously estimated (Fairweather Science, 2020). Hilcorp
did not record any sightings of fin whales from their aerial or rig-
based monitoring efforts in 2023 (Horsley and Larson, 2023).
Beluga Whale
Five stocks of beluga whales are recognized in Alaska: the Beaufort
Sea stock, eastern Chukchi Sea stock,
[[Page 35771]]
eastern Bering Sea stock, Bristol Bay stock, and Cook Inlet stock
(Young et al., 2023). The Cook Inlet stock of beluga whale is the only
stock that inhabits the project area. It is geographically and
genetically isolated from the other stocks (O'Corry-Crowe et al., 1997,
Laidre et al., 2000) and resides year-round in Cook Inlet (Laidre et
al., 2000, Castellote et al., 2020). Cook Inlet beluga whales (CIBWs)
were designated as depleted under the MMPA in 2000 (65 FR 34950, May
31, 2000), and as a distinct population segment (DPS) and listed as
endangered under the ESA in October 2008 (73 FR 62919, October 10,
2008) when the species failed to recover following a moratorium on
subsistence harvest. Between 2008 and 2018, CIBWs experienced a decline
of about 2.3 percent per year (Wade et al., 2019). The decline
overlapped with the northeast Pacific marine heatwave that occurred
from 2014 to 2016 in the Gulf of Alaska, significantly impacting the
marine ecosystem (Suryan et al., 2021 as cited in Goetz et al., 2023).
In June 2023, NMFS released an updated abundance estimate for CIBWs
in Alaska that incorporates aerial survey data from June 2021 and 2022
and accounted for visibility bias (Goetz et al., 2023). This report
estimated that CIBW abundance is between 290 and 386, with a median
best estimate of 331. Goetz et al. (2023) also present an analysis of
population trends for the most recent 10-year period (2012-2022). The
addition of data from the 2021 and 2022 survey years in the analysis
resulted in a 65.1 percent probability that the CIBW population is now
increasing at 0.9 percent per year (95 percent prediction interval of -
3 to 5.7 percent). This increase drops slightly to 0.2 percent per year
(95 percent prediction interval of -1.8 to 2.6 percent) with a 60
percent probability that the CIBW population is increasing more than 1
percent per year when data from 2021, which had limited survey coverage
due to poor weather, are excluded from the analysis.
Threats that have the potential to impact this stock and its
habitat include the following: changes in prey availability due to
natural environmental variability, ocean acidification, and commercial
fisheries; climatic changes affecting habitat; predation by killer
whales; contaminants; noise; ship strikes; waste management; urban
runoff; construction projects; and physical habitat modifications that
may occur as Cook Inlet becomes increasingly urbanized (Moore et al.,
2000, Hobbs et al., 2015, NMFS, 2016). Another source of CIBW mortality
in Cook Inlet is predation by transient-type (mammal-eating) killer
whales (NMFS, 2016, Shelden et al., 2003). No human-caused mortality or
serious injury of CIBWs through interactions with commercial,
recreational, and subsistence fisheries, takes by subsistence hunters,
and or human-caused events (e.g., entanglement in marine debris, ship
strikes) has been recently documented (Muto et al., 2022) and
harvesting of CIBWs has not occurred since 2008 (NMFS, 2008a).
Recovery Plan
In 2010, a recovery team, consisting of a science panel and
stakeholder panel, began meeting to develop a recovery plan for the
CIBW. The final recovery plan was published in the Federal Register on
January 5, 2017 (82 FR 1325). In September 2022, NMFS completed the ESA
5-year review for the CIBW DPS and determined that the CIBW DPS should
remain listed as endangered (NMFS, 2022a).
In its recovery plan (82 FR 1325, January 5, 2017), NMFS identified
several potential threats to CIBWs, including: (1) high concern:
catastrophic events (e.g., natural disasters, spills, mass strandings),
cumulative effects of multiple stressors, and noise; (2) medium
concern: disease agents (e.g., pathogens, parasites, and harmful algal
blooms), habitat loss or degradation, reduction in prey, and
unauthorized take; and (3) low concern: pollution, predation, and
subsistence harvest. The recovery plan did not treat climate change as
a distinct threat but rather as a consideration in the threats of high
and medium concern. Other potential threats most likely to result in
direct human-caused mortality or serious injury of this stock include
vessel strikes.
Critical Habitat
On April 11, 2011, NMFS designated two areas of critical habitat
for CIBW (76 FR 20179). The designation includes 7,800 square
kilometers (km\2\) of marine and estuarine habitat within Cook Inlet,
encompassing approximately 1,909 km\2\ in Area 1 and 5,891 km\2\ in
Area 2 (see figure 1 in 76 FR 20179). Area 1 of the CIBW critical
habitat encompasses all marine waters of Cook Inlet north of a line
connecting Point Possession (lat. 61.04[deg] N, long. 150.37[deg] W)
and the mouth of Three Mile Creek (lat. 61.08.55[deg] N, long.
151.04.40[deg] W), including waters of the Susitna, Little Susitna, and
Chickaloon Rivers below Mean Higher High Water (MHHW). From spring
through fall, Area 1 critical habitat has the highest concentration of
CIBWs due to its important foraging and calving habitat. Critical
Habitat Area 2, where 8 Star Alaska's proposed construction activities
would occur, encompasses some of the fall and winter feeding grounds in
middle Cook Inlet. This area has a lower concentration of CIBWs in
spring and summer but is used by CIBWs in fall and winter. More
information on CIBW critical habitat can be found at <a href="https://www.fisheries.noaa.gov/action/critical-habitat-cook-inlet-beluga-whale">https://www.fisheries.noaa.gov/action/critical-habitat-cook-inlet-beluga-whale</a>.
The designation identified the following Primary Constituent
Elements, essential features important to the conservation of the CIBW:
(1) Intertidal and subtidal waters of Cook Inlet with depths of
less than 9 m Mean Lower Low Water (MLLW) and within 8 km of high- and
medium-flow anadromous fish streams;
(2) Primary prey species, including four of the five species of
Pacific salmon (chum (Oncorhynchus keta), sockeye (Oncorhynchus nerka),
Chinook (Oncorhynchus tshawytscha), and coho (Oncorhynchus kisutch)),
Pacific eulachon (Thaleichthys pacificus), Pacific cod (Gadus
macrocephalus), walleye Pollock (Gadus chalcogrammus), saffron cod
(Eleginus gracilis), and yellowfin sole (Limanda aspera);
(3) The absence of toxins or other agents of a type or amount
harmful to CIBWs;
(4) Unrestricted passage within or between the critical habitat
areas; and
(5) The absence of in-water noise at levels resulting in the
abandonment of habitat by CIBWs.
Biologically Important Areas
Wild et al. (2023) delineated a small and resident population
Biologically Important Area (BIA) in Cook Inlet that is active year-
round and overlaps 8 Star Alaska's proposed project area. The authors
assigned the BIA an importance score of 2, an intensity score of 2, a
data support score of 3, and a boundary certainty score of 2 (scores
range from 1 to 3, with a higher score representing an area of more
concentrated or focused use and higher confidence in the data
supporting the BIA (Harrison et al., 2023)). These scores indicate that
the BIA is of moderate importance and intensity, the authors have high
confidence that the population is small and resident and in the
abundance and range estimates of the population, and the boundary
certainty is medium (see Harrison et al. (2023) for additional
information about the scoring process used to identify BIAs). The
boundary of the CIBW BIA is consistent with NMFS' critical habitat
designation (Wild et al., 2023).
[[Page 35772]]
Ecology
Generally, female beluga whales reach sexual maturity at 9 to 12
years old, while males reach maturity later (O'Corry[hyphen]Crowe,
2009); however, this can vary between populations. For example, in
Greenland, males in a population of beluga whales were found to reach
sexual maturity at 6 to 7 years of age and females at 4 to 7 years
(Heide-J[oslash]rgensen and Teilmann, 1994). Suydam (2009) estimated
that 50 percent of females were sexually mature at age 8.25 and the
average age at first birth was 8.27 years for belugas sampled near
Point Lay. Mating behavior in beluga whales typically occurs between
February and June, peaking in March (Burns and Seaman, 1986, Suydam,
2009). In the Chukchi Sea, the gestation period of beluga whales was
determined to be 14.9 months, with a calving interval of 2 to 3 years
and a pregnancy rate of 0.41, declining after 25 years of age (Suydam,
2009). Calves are born between mid-June and mid-July and typically
remain with the mother for up to 2 years of age (Suydam, 2009).
CIBWs feed on a wide variety of prey species, particularly those
that are seasonally abundant. From late spring through summer, most
CIBW stomachs sampled contained salmon, which corresponded to the
timing of fish runs in the area. Anadromous smolt and adult fish
aggregate at river mouths and adjacent intertidal mudflats (Calkins,
1989). All five Pacific salmon species (i.e., Chinook, pink
(Oncorhynchus gorbuscha), coho, sockeye, and chum) spawn in rivers
throughout Cook Inlet (Moulton, 1997, Moore et al., 2000). Overall,
Pacific salmon represent the highest percent frequency of occurrence of
prey species in CIBW stomachs. This suggests that their spring feeding
in upper Cook Inlet, principally on fat-rich fish such as salmon and
eulachon, is important to the energetics of these animals (NMFS, 2016).
The nutritional quality of Chinook salmon in particular is
unparalleled, with an energy content four times greater than that of a
Coho salmon. It is suggested the decline of the Chinook salmon
population has left a nutritional void in the diet of the CIBWs that no
other prey species can fill in terms of quality or quantity (Norman et
al., 2022, Norman et al., 2020).
In fall, as anadromous fish runs begin to decline, CIBWs return to
consume fish species (cod and bottom fish) found in nearshore bays and
estuaries. Stomach samples from CIBWs are not available for winter
(December through March), although dive data from CIBWs tagged with
satellite transmitters suggest that they feed in deeper waters during
winter (Hobbs et al., 2005), possibly on such prey species as flatfish,
cod, sculpin, and pollock.
Distribution in Cook Inlet
The CIBW stock remains within Cook Inlet throughout the year,
showing only small seasonal shifts in distribution (Goetz et al.,
2012a, Lammers et al., 2013, Castellote et al., 2015, Shelden et al.,
2015a, Shelden et al., 2018, Lowry et al., 2019). The ecological range
of CIBWs has contracted significantly since the 1970s. From late spring
to fall, nearly the entire population is now found in the upper inlet
north of the forelands, with a range reduced to approximately 39
percent of the size documented in the late 1970s (Goetz et al., 2023).
The recent annual and semiannual aerial surveys (since 2008) found that
approximately 83 percent of the population inhabits the area between
the Beluga River and Little Susitna River during the survey period,
typically conducted in early June. Some aerial survey counts were
performed in August, September, and October, finding minor differences
in the numbers of belugas in the upper inlet compared to June,
reinforcing the importance of the upper inlet habitat area (Young et
al., 2023). 8 Star Alaska's proposed construction would not occur in
this upper inlet habitat area.
During spring and summer, CIBWs generally aggregate near the warmer
waters of river mouths along the northern shores of middle and upper
Cook Inlet where prey availability is high and predator occurrence is
low (Moore et al., 2000, Shelden and Wade, 2019, McGuire et al., 2020).
In particular, CIBW groups are seen in the Susitna River Delta, the
Beluga River and along the shore to the Little Susitna River, Knik Arm,
and along the shores of Chickaloon Bay. Small groups were recorded
farther south in Kachemak Bay, Redoubt Bay (Big River), and Trading Bay
(McArthur River) prior to 1996, but rarely thereafter. Since the mid-
1990s, most CIBWs (96 to 100 percent) aggregate in shallow areas near
river mouths in upper Cook Inlet, and they are only occasionally
sighted in the central or southern portions of Cook Inlet during summer
(Hobbs et al., 2008). Almost the entire population can be found in
northern Cook Inlet from late spring through the summer and into the
fall (Muto et al., 2020), shifting into deeper waters in middle Cook
Inlet in winter (Hobbs et al., 2008).
Data from tagged whales (14 tags deployed July 2000 through March
2003) show that CIBWs use upper Cook Inlet intensively between summer
and late autumn (Hobbs et al., 2005). CIBWs tagged with satellite
transmitters continue to use Knik Arm, Turnagain Arm, and Chickaloon
Bay as late as October, but some range into lower Cook Inlet to
Chinitna Bay, Tuxedni Bay, and Trading Bay (McArthur River) in fall
(Hobbs et al., 2005, Hobbs et al., 2012). From September through
November, CIBWs move between Knik Arm, Turnagain Arm, and Chickaloon
Bay (Hobbs et al., 2005, Goetz et al., 2012b). By December, CIBWs are
distributed throughout the upper to mid-inlet. From January into March,
they move as far south as Kalgin Island and slightly beyond in central
offshore waters. CIBWs make occasional excursions into Knik Arm and
Turnagain Arm in February and March in spite of ice cover (Hobbs et
al., 2005). Although tagged CIBWs move widely around Cook Inlet
throughout the year, there is no indication of seasonal migration in
and out of Cook Inlet (Hobbs et al., 2005). Data from NMFS aerial
surveys, opportunistic sighting reports, and corrected satellite-tagged
CIBWs confirm that they are more widely dispersed throughout Cook Inlet
during winter (November-April), with animals found between Kalgin
Island and Point Possession. Generally fewer observations of CIBWs are
reported from the Anchorage and Knik Arm area from November through
April (76 FR 20179, April 11, 2011; Rugh et al., 2000, 2004). Later in
winter (January into March), belugas were sighted near Kalgin Island
and in deeper waters offshore. However, even when ice cover exceeds 90
percent in February and March, belugas travel into Knik Arm and
Turnagain Arm (Hobbs et al., 2005).
The NMFS Alaska Fisheries Science Center (AFSC) has conducted long-
term passive acoustic monitoring demonstrating seasonal shifts in CIBW
concentrations throughout Cook Inlet. Castellote et al. (2015)
conducted long-term acoustic monitoring at 13 locations throughout Cook
Inlet between 2008 and 2015: North Eagle Bay, Eagle River Mouth, South
Eagle Bay, Six Mile, Point MacKenzie, Cairn Point, Fire Island, Little
Susitna, Beluga River, Trading Bay, Kenai River, Tuxedni Bay, and Homer
Spit; the former 6 stations being located within Knik Arm. In general,
the observed seasonal distribution is in accordance with descriptions
based on aerial surveys and satellite telemetry: CIBW detections are
higher in the upper inlet during summer, peaking at Little Susitna,
Beluga River, and Eagle Bay, followed by fewer detections at those
locations during winter. Higher detections in winter at Trading Bay,
[[Page 35773]]
Kenai River, and Tuxedni Bay suggest a broader CIBW distribution in the
lower inlet during winter.
Goetz et al. (2012b) modeled habitat preferences using NMFS' 1994-
2008 June abundance survey data. In large areas, such as the Susitna
Delta (Beluga to Little Susitna Rivers) and Knik Arm, there was a high
probability that CIBWs were in larger groups. CIBW presence and
acoustic foraging behavior also increased closer to rivers with Chinook
salmon runs, such as the Susitna River (e.g., Castellote et al., 2021).
Movement has been correlated with the peak discharge of seven major
rivers emptying into Cook Inlet. Boat-based surveys from 2005 to the
present (McGuire and Stephens, 2017) and results from passive acoustic
monitoring across the entire inlet (Castellote et al., 2015) also
support seasonal patterns observed with other methods. Based on long-
term passive acoustic monitoring, foraging behavior was more prevalent
during summer, particularly at upper inlet rivers, than during winter.
The foraging index was highest at Little Susitna, with a peak in July-
August and a secondary peak in May, followed by Beluga River and then
Eagle Bay; monthly variation in the foraging index indicates CIBWs
shift their foraging behavior among these three locations from April
through September. The location of the towing routes are areas of
predicted low density in the summer months.
CIBWs are believed to mostly calve in the summer, and breed between
late spring and early summer (NMFS, 2016), primarily in upper Cook
Inlet. The first neonates encountered during each field season from
2005 through 2015 were always seen in the Susitna River Delta in July.
The photographic identification team's documentation of the dates of
the first neonate of each year indicate that calving begins in mid-late
July/early August, generally coinciding with the observed timing of
annual maximum group size. Probable mating behavior of CIBWs was
observed in April and May of 2014 in Trading Bay. Young CIBWs are
nursed for 2 years and may continue to associate with their mothers for
a considerable time thereafter (Colbeck et al., 2013). Important
calving grounds are thought to be located near the river mouths of
upper Cook Inlet.
During Apache's seismic test program in 2011 along the west coast
of Redoubt Bay, lower Cook Inlet, a total of 33 CIBWs were sighted
during the survey (Lomac-MacNair et al., 2013). During Apache's 2012
seismic program in mid-inlet, a total of 151 groups consisting of an
estimated 1,463 CIBWs were observed (note individuals were likely
observed more than once) (Lomac-MacNair et al., 2014). During
SAExploration's 2015 seismic program, a total of 8 groups of 33
estimated individual CIBWs were visually observed during this time
period and there were two acoustic detections of CIBWs (Kendall et al.,
2015). During Harvest Alaska's recent CIPL project on the west side of
Cook Inlet in between Ladd Landing and Tyonek Platform, a total of 143
CIBW groups (814 individuals) were observed almost daily from May 31 to
July 11, even though observations spanned from May 9 through September
15 (Sitkiewicz et al., 2018). There were two CIBW carcasses observed by
the project vessels in the 2019 Hilcorp lower Cook Inlet seismic survey
in the fall which were reported to the NMFS Marine Mammal Stranding
Network (Fairweather Science, 2020). Both carcasses were moderately
decomposed when they were sighted by the PSOs. Daily aerial surveys
specifically for CIBWs were flown over the lower Cook Inlet region, but
no beluga whales were observed. In 2023, Hilcorp recorded 21 groups of
more than 125 beluga whales during aerial surveys in middle Cook Inlet,
and an additional 21 opportunistic groups which included approximately
81 CIBWs (Horsley and Larson, 2023). Hilcorp did not record any
sightings of CIBWs from their rig-based monitoring efforts (Horsley and
Larson, 2023).
Killer Whale
Along the west coast of North America, seasonal and year-round
occurrence of killer whales has been noted along the entire Alaska
coast (Braham and Dahlheim, 1982), in British Columbia and Washington
inland waterways (Bigg et al., 1990), and along the outer coasts of
Washington, Oregon, and California (Green et al., 1992, Barlow, 1995,
Barlow, 1997, Forney et al., 1995). Killer whales from these areas have
been labeled as ``resident,'' ``transient,'' and ``offshore'' type
killer whales (Bigg et al., 1990, Ford et al., 2000, Dahlheim et al.,
2008) based on aspects of morphology, ecology, genetics, and behavior
(Ford and Fisher, 1982, Baird and Stacey, 1988, Baird et al., 1992,
Hoelzel et al., 1998, Hoelzel et al., 2002, Barrett-Lennard, 2000,
Dahlheim et al., 2008). Based on data regarding association patterns,
acoustics, movements, and genetic differences, eight killer whale
stocks are now recognized within the U.S. Pacific, two of which have
the potential to be found in the proposed project area: the Eastern
North Pacific Alaska Resident stock and the Gulf of Alaska, Aleutian
Islands, and the Bering Sea Transient stock. Both stocks occur in lower
Cook Inlet, but rarely in middle and upper Cook Inlet (Shelden et al.,
2013). While these stocks overlap the same geographic area, they
maintain social and reproductive isolation and feed on different prey
species. Resident killer whales are primarily fish-eaters, while
transients primarily hunt and consume marine mammals, such as harbor
seals, Dall's porpoises, harbor porpoises, beluga whales and sea lions.
Killer whales are not harvested for subsistence in Alaska. Potential
threats most likely to result in direct human-caused M/SI of killer
whales in this region include oil spills, vessel strikes, and
interactions with fisheries.
Killer whales have been sighted near Homer and Port Graham in lower
Cook Inlet (Shelden et al., 2022, Shelden et al., 2003, Rugh et al.,
2005). Resident killer whales from pods often sighted near Kenai Fjords
and Prince William Sound have been occasionally photographed in lower
Cook Inlet (Shelden et al., 2003). The availability of salmon
influences when resident killer whales are more likely to be sighted in
Cook Inlet. Killer whales were observed in the Kachemak and English Bay
three times during aerial surveys conducted between 1993 and 2004 (Rugh
et al., 2005). Passive acoustic monitoring efforts throughout Cook
Inlet documented killer whales at the Beluga River, Kenai River, and
Homer Spit, although they were not encountered within Knik Arm
(Castellote et al., 2016). These detections were likely resident killer
whales. Transient killer whales likely have not been acoustically
detected due to their propensity to move quietly through waters to
track prey (Small, 2010, Lammers et al., 2013). Transient killer whales
were increasingly reported to feed on belugas in the middle and upper
Cook Inlet in the 1990s.
During the 2015 SAExploration seismic program near the North
Foreland, two killer whales were observed (Kendall et al., 2015, as
cited in Weston and SLR, 2022). Killer whales were observed in lower
Cook Inlet in 1994, 1997, 2001, 2005, 2010, 2012, and 2022 during the
NMFS aerial surveys (Shelden et al., 2013, 2022). Eleven killer whale
strandings have been reported in Turnagain Arm: 6 in May 1991 and 5 in
August 1993. During the Hilcorp lower Cook Inlet seismic survey in the
fall of 2019, 21 killer whales were documented (Fairweather Science,
2020). Throughout 4 months of observation in 2018 during the CIPL
project in middle Cook Inlet, no killer whales were observed
(Sitkiewicz et al., 2018). In September 2021, two killer
[[Page 35774]]
whales were documented in Knik Arm in upper Cook Inlet, near the POA
(61 North Environmental, 2022a). Hilcorp did not record any sightings
of killer whales from their aerial or rig-based monitoring efforts in
2023 (Horsley and Larson, 2023).
Pacific White-Sided Dolphin
The North Pacific stock of Pacific white-sided dolphin is common in
the Gulf of Alaska's pelagic waters and Alaska's nearshore areas,
British Columbia, and Washington Ferrero and Walker, 1996, as cited in
Muto et al., 2022). They do not typically occur in Cook Inlet, but in
2019, Castellote et al. (2020) documented short durations of Pacific
white-sided dolphin presence using passive acoustic recorders near
Iniskin Bay (6 minutes) and at an offshore mooring located
approximately midway between Port Graham and Iniskin Bay (51 minutes).
Detections of vocalizations typically lasted on the order of minutes,
suggesting the animals did not remain in the area and/or continue
vocalizing for extended durations. Visual monitoring conducted during
the same period by marine mammal observers on seismic vessels near the
offshore recorder did not detect any Pacific white-sided dolphins
(Fairweather Science, 2020). These observational data, combined with
anecdotal information, indicate that there is a small potential for
Pacific white-sided dolphins to occur in the project area. On May 7,
2014, Apache Alaska observed three Pacific white-sided dolphins during
an aerial survey near Kenai. This is one of the only recorded visual
observations of Pacific white-sided dolphins in Cook Inlet; they have
not been reported in groups as large as those estimated in other parts
of Alaska (Muto et al., 2022).
Harbor Porpoise
Harbor porpoises in Cook Inlet are assumed to be members of the
Gulf of Alaska stock (Young et al., 2023). Harbor porpoises occur most
frequently in waters less than 100 m deep (Hobbs and Waite, 2010) and
are common in nearshore areas of the Gulf of Alaska, Shelikof Strait,
and lower Cook Inlet (Dahlheim et al., 2000). Harbor porpoises are
often observed in lower Cook Inlet in Kachemak Bay and from Cape
Douglas to the West Foreland (Rugh et al., 2005). They can be
opportunistic foragers but consume primarily schooling forage fish
(Bowen and Siniff, 1999). Subsistence users have not reported any
harvest from the Gulf of Alaska harbor porpoise stock since the early
1900s (Shelden et al., 2014). Calving occurs from May to August;
however, this can vary by region. Harbor porpoises often travel alone
or in small groups of less than 10 individuals (Schmale, 2008).
Harbor porpoises occur throughout Cook Inlet, with passive acoustic
detections being more prevalent in lower Cook Inlet. Although harbor
porpoises have been frequently observed during aerial surveys in Cook
Inlet (Shelden et al., 2014), most sightings are of single animals and
are concentrated at Chinitna and Tuxedni bays on the west side of lower
Cook Inlet (Rugh et al., 2005), with smaller numbers observed in upper
Cook Inlet between April and October. The occurrence of larger numbers
of porpoise in the lower Cook Inlet may be driven by greater
availability of preferred prey and possibly less competition with
CIBWs, as CIBWs move into upper inlet waters to forage on Pacific
salmon during the summer months (Shelden et al., 2014).
An increase in harbor porpoise sightings in upper Cook Inlet was
observed over recent decades (e.g., 61 North Environmental, 2021,
2022a, Shelden et al., 2014). Small numbers of harbor porpoises have
been consistently reported in upper Cook Inlet between April and
October (Prevel-Ramos et al., 2008). The reason for the increase in
sightings in upper Cook Inlet is unknown, although it may be an
artifact of increased monitoring effort in upper Cook Inlet. It is also
possible that the contraction in the CIBW's range has opened up
previously occupied CIBW range to harbor porpoises (Shelden et al.,
2014).
During Apache's 2012 seismic program in middle Cook Inlet, 137
groups of harbor porpoises comprising 190 individuals were documented
between May and August (Lomac-MacNair et al., 2013). In June 2012,
Shelden et al. (2015b) documented 65 groups of 129 individual harbor
porpoises during an aerial survey, none of which were in upper Cook
Inlet. Kendall et al. (2015, as cited in Weston and SLR, 2022)
documented 52 groups comprising 65 individuals north of the Forelands
during SAExploration's 2015 seismic survey. Shelden et al. (2017, 2019,
2022) also conducted aerial surveys in June and July over Cook Inlet in
2016, 2018, 2021, and 2022 and recorded 65 individuals. Observations
occurred in middle and lower Cook Inlet with a majority in Kachemak
Bay. There were two sightings of three harbor porpoises observed during
the 2019 Hilcorp lower Cook Inlet seismic survey in the fall
(Fairweather Science, 2020). A total of 29 groups (44 individuals) were
observed north of the Forelands from May to September during the CIPL
Extension Project (Sitkiewicz et al., 2018). During jack-up rig moves
in 2021, a PSO observed two individual harbor porpoises in middle Cook
Inlet: one in July and one in October. Four monitoring events were
conducted at the POA in Anchorage between April 2020 and August 2022,
during which 42 groups of harbor porpoises comprising 50 individual
porpoises were documented over 285 days of observation (61 North
Environmental, 2021, 2022a, 2022b, 2022c 2022c). One harbor porpoise
was observed during Hilcorp's boat-based monitoring efforts in June
2023 (Horsley and Larson, 2023).
Dall's Porpoise
Dall's porpoises in Alaska are of the Alaska stock. This species
can be found in offshore, inshore, and nearshore habitat. The most
recently updated SAR for the Alaska stock of Dall's porpoise (Muto et
al., 2021) assess the abundance of Alaska Dall's porpoise only in the
northwestern Gulf of Alaska, which is a small portion of the stock's
geographic range. Sighting surveys for cetaceans were conducted
opportunistically during NMFS' pollock stock assessment surveys in
1999, 2000, 2002, 2004, 2008, and 2010 on the eastern Bering Sea shelf
(Moore et al., 2002, Friday et al., 2012, 2013). The entire study area
of the survey, which corresponded to only a fraction of the range of
the Alaska stock, was fully covered in three of those years (2002,
2008, and 2010). Dall's porpoise abundance estimates were 35,303 (CV =
0.53) in 2002, 14,543 (CV = 0.32) in 2008, and 11,143 (CV = 0.32) in
2010 (Friday et al. 2013). Abundance estimates for Dall's porpoise in
inland waters of Southeast Alaska were calculated from 19 line-transect
vessel surveys from 1991 to 2012 (Jefferson et al. 2019). Abundance
across the whole period was estimated at 5,381 (CV = 0.25), 2,680 (CV =
0.20), and 1,637 (CV = 0.23) in the spring, summer, and fall,
respectively (Jefferson et al. 2019). Vessel surveys were carried out
in and around a Navy Maritime Activity/Training Area in the
northwestern Gulf of Alaska to document abundance and density of
cetaceans in 2013 and 2015 (Rone et al. 2017). The surveys covered
different, but partially overlapping, areas in the two years and
estimated Dall's porpoise abundance as 15,432 (CV = 0.28) in 2013 and
13,110 (CV = 0.22) in 2015. The minimum population estimate
(N<INF>MIN</INF>) for this stock is assumed to correspond to the point
estimate of the 2015 vessel-based abundance computed by Rone et al.
(2017) in the Gulf of Alaska (N = 13,110; CV = 0.22).
[[Page 35775]]
The Dall's porpoise range in Alaska includes lower Cook Inlet, but
very few sightings have been reported in upper Cook Inlet. Observations
have been documented near Kachemak Bay and Anchor Point (Owl Ridge,
2014; BOEM, 2015). Shelden et al. (2013). Rugh et al. (2005) collated
data from aerial surveys conducted between 1994 and 2012 and documented
9 sightings of 25 individuals in the lower Cook Inlet during June and/
or July 1997, 1999, and 2000. No Dall's porpoise were observed on
subsequent surveys in June and/or July 2014, 2016, 2018, 2021, and 2022
(Shelden et al., 2015b, 2017, and 2022; Shelden and Wade, 2019). During
Apache's 2014 seismic survey, two groups of three Dall's porpoises were
observed in upper and middle Cook Inlet (Lomac-MacNair et al., 2014).
In August 2015, one Dall's porpoise was reported in north of Nikiski in
middle Cook Inlet during SAExploration's seismic program (Kendall et
al., 2015). During aerial surveys in Cook Inlet, they were observed in
Iniskin Bay, Barren Island, Elizabeth Island, and Kamishak Bay (Shelden
et al., 2013). No Dall's porpoises were observed during the 2018 CIPL
Extension Project Acoustic Monitoring Program in middle Cook Inlet
(Sitkiewicz et al., 2018); however, 30 individuals in 10 groups were
sighted during a lower Cook Inlet seismic project in the fall 2019
(Fairweather Science, 2020). Hilcorp recorded three sightings of Dall's
porpoises in 2021 and one sighting of a Dall's porpoise in 2023 from
their rig-based monitoring efforts in the project area (Korsmo et al.,
2022, Horsley and Larson, 2023). One Dall's porpoise was observed near
the POA during the NES1 project, but it is possible this was
misidentified (61 North Environmental, 2025). This higher number of
sightings suggests Dall's porpoise may use portions of middle Cook
Inlet in greater numbers than previously expected but would still be
considered infrequent in middle and upper Cook Inlet.
Steller Sea Lion
Two DPSs of Steller sea lion occur in Alaska: the western DPS and
the eastern DPS. The western DPS includes animals that occur west of
Cape Suckling, Alaska, and therefore includes individuals within the
project area. The western DPS was listed under the ESA as threatened in
1990 (55 FR 49204, November 26, 1990), and its continued population
decline resulted in a change in listing status to endangered in 1997
(62 FR 24345, May 5, 1997). Since 2000, studies indicate that the
population east of Samalga Pass (i.e., east of the Aleutian Islands)
has increased and is potentially stable (Young et al., 2023).
There is uncertainty regarding threats currently impeding the
recovery of Steller sea lions, particularly in the Aleutian Islands.
Many factors have been suggested as causes of the steep decline in
abundance of western Steller sea lions observed in the 1980s, including
competitive effects of fishing, environmental change, disease,
contaminants, killer whale predation, incidental take, and illegal and
legal shooting (Atkinson et al., 2008, NMFS, 2008b). A number of
management actions have been implemented since 1990 to promote the
recovery of the Western U.S. stock of Steller sea lions, including 5.6-
km (3-nautical mile) no-entry zones around rookeries, prohibition of
shooting at or near sea lions, and regulation of fisheries for sea lion
prey species (e.g., walleye pollock, Pacific cod, and Atka mackerel
(Pleurogrammus monopterygius)) (Tollit et al., 2017, Sinclair et al.,
2013). Additionally, potentially deleterious events, such as harmful
algal blooms (Lefebvre et al., 2016) and disease transmission across
the Arctic (VanWormer et al., 2019) that have been associated with
warming waters, could lead to potentially negative population-level
impacts on Steller sea lions.
NMFS designated critical habitat for Steller sea lions on August
27, 1993 (58 FR 45269), including portions of the southern reaches of
lower Cook Inlet. The critical habitat designation for the Western DPS
was determined to include a 37-km (20-nautical mile) buffer around all
major haul-outs and rookeries, and associated terrestrial, atmospheric,
and aquatic zones, plus three large offshore foraging areas, none of
which occurs in the project area. There is no designated critical
habitat for Steller sea lions in the mid- or upper inlet, nor is there
habitat of particular importance for Steller sea lions in the project
area. Rookeries and haul out sites in lower Cook Inlet include those
near the mouth of the inlet, which are approximately 56 km or more
south of the closest action area.
Most Steller sea lions in Cook Inlet occur south of Anchor Point on
the east side of lower Cook Inlet, with concentrations near haulout
sites at Shaw Island and Elizabeth Island and by Chinitna Bay and
Iniskin Bay on the west side (Rugh et al., 2005). Steller sea lions are
rarely seen in upper Cook Inlet (Nemeth et al., 2007). About 3,600 sea
lions use haulout sites in the lower Cook Inlet area (Sweeney et al.,
2017), with additional individuals venturing into the area to forage.
Several surveys and monitoring programs have documented Steller sea
lions throughout Cook Inlet, including in upper Cook Inlet in 2012
(Lomac-MacNair et al., 2013), near Cape Starichkof in 2013 (Owl Ridge,
2014), in middle and lower Cook Inlet in 2015 (Kendall et al., 2015, as
cited in Weston and SLR, 2022), in middle Cook Inlet in 2018
(Sitkiewicz et al., 2018), in lower Cook Inlet in 2019 (Fairweather
Science, 2020), and near the POA in Anchorage in 2020, 2021, and 2022
(61 North Environmental, 2021, 2022a, 2022b, and 2022c). During NMFS
CIBW aerial surveys from 2000 to 2016, 39 sightings of 769 estimated
individual Steller sea lions in lower Cook Inlet were recorded (Shelden
et al., 2017). Sightings of large congregations of Steller sea lions
during NMFS aerial surveys occurred outside the specific geographic
region, on land in the mouth of Cook Inlet (e.g., Elizabeth and Shaw
Islands). In 2012, during Apache's 3D Seismic surveys, three sightings
of approximately four individuals in upper Cook Inlet were recorded
(Lomac-MacNair et al., 2013). PSOs associated with Buccaneer's drilling
project off Cape Starichkof observed seven Steller sea lions in summer
2013 (Owl Ridge, 2014), and another four Steller sea lions were
observed in 2015 in Cook Inlet during SAExploration's 3D Seismic
Program. Of the three 2015 sightings, one sighting occurred between the
West and East Forelands, one occurred near Nikiski, and one occurred
northeast of the North Foreland in the center of Cook Inlet (Kendall
and Cornick, 2015). Five sightings of five Steller sea lions were
recorded during Hilcorp's lower Cook Inlet seismic survey in the fall
of 2019 (Fairweather Science, 2020). Additionally, one sighting of two
individuals occurred during the CIPL Extension Project in 2018 in
middle Cook Inlet (Sitkiewicz et al., 2018). At the end of July 2022,
while conducting a waterfowl survey an estimated 25 Steller sea lions
were observed hauled-out at low tide in the Lewis River, on the west
side of Cook Inlet. (K. Lindberg, personal communication, August 15,
2022). Steller sea lions have also been reported near the POA in
Anchorage in 2020, 2021, and 2022 (61 North Environmental 2021, 2022a,
2022b, and 2022c). Hilcorp did not record any sightings of Steller sea
lions from their aerial or rig-based monitoring efforts in 2023
(Horsley and Larson, 2023).
Harbor Seal
Harbor seals in the proposed project area are of the Cook Inlet/
Shelikof stock, which ranges from the southwest tip of
[[Page 35776]]
Unimak Island east along the southern coast of the Alaska Peninsula to
Elizabeth Island off the southwest tip of the Kenai Peninsula,
including Cook Inlet, Knik Arm, and Turnagain Arm. Distribution of the
Cook Inlet/Shelikof stock extends from Unimak Island, in the Aleutian
Islands archipelago, north through all of upper and lower Cook Inlet
(Young et al., 2023).
Harbor seals inhabit the coastal and estuarine waters of Cook Inlet
and occur in both upper and lower Cook Inlet throughout most of the
year (Boveng et al., 2012, Shelden et al., 2013). High-density areas
include Kachemak Bay, Iniskin Bay, Iliamna Bay, Kamishak Bay, Cape
Douglas, and Shelikof Strait. Up to a few hundred seals seasonally
occur in middle and upper Cook Inlet (Rugh et al. 2005), with the
highest concentrations found near the Susitna River and other
tributaries within upper Cook Inlet during eulachon and salmon runs
(Nemeth et al., 2007; Boveng et al., 2012), but most remain south of
the forelands (Boveng et al., 2012).
The results of past and recent satellite tagging studies in
Southeast Alaska, Prince William Sound, Kodiak Island, and Cook Inlet
are also consistent with the conclusion that harbor seals are non-
migratory (Lowry et al., 2001; Small et al., 2003; Boveng et al.,
2012). However, some long-distance movements of tagged animals in
Alaska have been recorded (Pitcher and McAllister, 1981, Lowry et al.,
2001, Small et al., 2003, Womble, 2012, Womble and Gende, 2013). Strong
fidelity of individuals for haulout sites during the breeding season
has been documented in several populations (H[auml]rk[ouml]nen and
Harding, 2001), including in Cook Inlet (Small et al., 2005, Pitcher
and McAllister, 1981, Boveng et al., 2012, Womble, 2012, Womble and
Gende, 2013). Harbor seals usually give birth to a single pup between
May and mid-July; birthing locations are dispersed over several haulout
sites and not confined to major rookeries (Klinkhart et al., 2008).
More than 200 haulout sites are documented in lower Cook Inlet
(Montgomery et al., 2007) and 18 in middle and upper Cook Inlet (London
et al., 2015). Of the 18 in middle and upper Cook Inlet, nine are
considered ``key haulout'' locations where aggregations of 50 or more
harbor seals have been documented. Seven key haulouts are in the
Susitna River delta, and two are near the Chickaloon River.
Recent research on satellite-tagged harbor seals observed several
movement patterns within Cook Inlet (Boveng et al., 2012), including a
strong seasonal pattern of more coastal and restricted spatial use
during the spring and summer (breeding, pupping, molting) and more
wide-ranging movements within and outside of Cook Inlet during the
winter months, with some seals ranging as far as Shumagin Islands.
During summer months, movements and distribution were mostly confined
to the west side of Cook Inlet and Kachemak Bay, and seals captured in
lower Cook Inlet generally exhibited site fidelity by remaining south
of the Forelands in lower Cook Inlet after release (Boveng et al.,
2012). In the fall, a portion of the harbor seals appeared to move out
of Cook Inlet and into Shelikof Strait, northern Kodiak Island, and
coastal habitats of the Alaska Peninsula. The western coast of Cook
Inlet had higher usage by harbor seals than eastern coast habitats, and
seals captured in lower Cook Inlet generally exhibited site fidelity by
remaining south of the Forelands in lower Cook Inlet after release
(south of Nikiski; Boveng et al., 2012).
Harbor seals have been sighted in Cook Inlet during every year of
the aerial surveys conducted by NMFS and during recent mitigation and
monitoring programs in lower, middle, and upper Cook Inlet (61N
Environmental, 2021, 2022a, 2022b, and 2022c; Fairweather Science,
2020; Kendall et al., 2015 as cited in Weston and SLR, 2022; Lomac-
MacNair et al., 2013, 2014; Sitkiewicz et al., 2018).
California Sea Lion
Few observations of California sea lions have been reported in
Alaska, and most observations have been limited to solitary
individuals, typically males that are known to migrate long distances.
Occasionally, California sea lions occur in small groups of two or
more, usually associated with Steller sea lions at their haul outs and
rookeries (Maniscalco et al., 2004). Sightings in Cook Inlet are rare,
with two documented during the Apache 2012 seismic survey (Lomac-
MacNair et al., 2013) and anecdotal sightings in Kachemak Bay.
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 (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 5.
Table 5--Marine Mammal Hearing Groups
[NMFS, 2024]
----------------------------------------------------------------------------------------------------------------
Hearing group Generalized hearing range *
----------------------------------------------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen whales)............... 7 Hz (Hertz) to 36 kHz.
High-frequency (HF) cetaceans (dolphins, toothed whales, 150 Hz to 160 kHz.
beaked whales, bottlenose whales).
Very High-frequency (VHF) cetaceans (true porpoises, Kogia, 200 Hz to 165 kHz.
river dolphins, Cephalorhynchid, Lagenorhynchus cruciger &
L. australis).
Phocid pinnipeds (PW) (underwater) (true seals)............ 40 Hz to 90 kHz.
Otariid pinnipeds (OW) (underwater) (sea lions and fur 60 Hz to 68 kHz.
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; Southall et al. 2019. Additionally, animals are able to detect very loud sounds above and below that
``generalized'' hearing range.
[[Page 35777]]
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2024) for a review of available information.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section provides a discussion of the ways in which components
of the specified activity may impact marine mammals and their habitat.
The Estimated Take of Marine Mammals section later in this document
includes a quantitative analysis of the number of individuals that are
expected to be taken by this activity. The Negligible Impact Analysis
and Determination section considers the content of this section, the
Estimated Take of Marine Mammals section, and the Proposed Mitigation
section, to draw conclusions regarding the likely impacts of these
activities on the reproductive success or survivorship of individuals
and whether those impacts are reasonably expected to, or reasonably
likely to, adversely affect the species or stock through effects on
annual rates of recruitment or survival.
Description of Sound Sources
The marine soundscape is comprised of both ambient and
anthropogenic sounds. Ambient sound is defined as the all-encompassing
sound in a given place and is usually a composite of sound from many
sources both near and far. The sound level of an area is defined by the
total acoustical energy being generated by known and unknown sources.
These sources may include physical (e.g., waves, wind, precipitation,
earthquakes, ice, atmospheric sound), biological (e.g., sounds produced
by marine mammals, fish, and invertebrates), and anthropogenic sound
(e.g., vessels, dredging, aircraft, construction).
The sum of the various natural and anthropogenic sound sources at
any given location and time--which comprise ``ambient'' or
``background'' sound--depends not only on the source levels (as
determined by current weather conditions and levels of biological and
shipping activity) but also on the ability of sound to propagate
through the environment. In turn, sound propagation is dependent on the
spatially and temporally varying properties of the water column and sea
floor and is frequency-dependent. As a result of the dependence on a
large number of varying factors, ambient sound levels can be expected
to vary widely over both coarse and fine spatial and temporal scales.
Sound levels at a given frequency and location can vary by 10-20 dB
from day to day (Richardson et al., 1995). The result is that,
depending on the source type and its intensity, sound from the
specified activity may be a negligible addition to the local
environment or could form a distinctive signal that may affect marine
mammals.
The proposed project includes impact and vibratory pile driving and
use of AHTs to handle anchors during pipelaying. 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 sediment. Vibratory pile
driving produces non-impulsive sound. Non-impulsive sounds typically do
not have the high peak sound pressure with rapid rise/decay time that
impulsive sounds do (ANSI, 1995, National Institute for Occupational
Safety and Health (NIOSH), 1998, NMFS, 2024, ANSI, 2005). Vibratory
hammers produce significantly less sound than impact hammers. Peak
sound pressure levels (SPLs) may be 180 dB or greater, but are
generally 10 to 20 dB lower than SPLs generated during impact pile
driving of the same-sized piles (Oestman et al., 2009). Rise time is
slower, reducing the probability and severity of injury, and sound
energy is distributed over a greater amount of time (Nedwell and
Edwards, 2002, Carlson et al., 2005).
Unlike discrete noise sources with known potential to harass marine
mammals (e.g., pile driving), both the noise sources and impacts from
the AHTs handling anchors are less well documented. Our assessments of
the potential for harassment of marine mammals incidental to 8 Star
Alaska's AHTs engaged in anchor handling activities specified here are
presented to account for what NMFS concludes is a likely potential for
take in context of the generally conservative Level B harassment
exposure threshold for continuous noise, and the impact that non-
quantitative contextual factors have on the likelihood of Level B
harassment occurring (e.g., NMFS considers conservatively the potential
for effects of relatively loud continuous noise sources on sensitive
species in important habitat, as is the case here for CIBWs), and the
nature and duration of the particular tug activities analyzed here.
The likely or possible impacts of 8 Star Alaska's proposed activity
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, any impacts
to marine mammals are expected to primarily be acoustic in nature.
Acoustic stressors would include effects of heavy equipment operation
during pile installation and AHTs engaged in anchor handling during
pipelaying.
Acoustic Impacts
The introduction of anthropogenic noise into the aquatic
environment from pile driving and AHTs is the primary means by which
marine mammals may be harassed from 8 Star Alaska's specified activity.
Animals exposed to natural or anthropogenic sound may experience
physical and psychological effects, ranging in magnitude from none to
severe (Southall et al., 2007, Southall et al., 2019). Exposure to pile
driving and noise from AHTs has the potential to result in auditory
threshold shifts (TS) and behavioral disturbance (e.g., avoidance,
temporary cessation of foraging and vocalizing, changes in dive
behavior). Exposure to anthropogenic noise can also lead to non-
observable physiological responses such as an increase in stress
hormones. Additional noise in a marine mammal's habitat can mask
acoustic cues used by marine mammals to carry out daily functions such
as communication and predator and prey detection. The effects of pile
driving and AHT noise on marine mammals are influenced by several
factors, including, but not limited to, sound type (e.g., impulsive vs.
non-impulsive), the species, age and sex class (e.g., adult male vs.
mom with calf), duration of exposure, the distance between the pile and
the animal, received levels, behavior at time of exposure, and previous
history with exposure (Wartzok et al., 2004, Southall et al., 2007).
Here we discuss physical auditory effects (TS) followed by behavioral
effects and potential impacts on habitat.
NMFS defines a noise-induced TS as a change, usually an increase,
in the threshold of audibility at a specified frequency or portion of
an individual's hearing range above a previously established reference
level (NMFS, 2018). The amount of TS is customarily expressed in dB. TS
can be permanent or temporary. As described by NMFS (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
[[Page 35778]]
to a high enough level to induce a TS, the magnitude of the TS, time to
recovery (seconds to minutes or hours to days), the frequency range of
the exposure (i.e., spectral content), the hearing and vocalization
frequency range of the exposed species relative to the signal's
frequency spectrum (i.e., how an animal uses sound within the frequency
band of the signal (e.g., Kastelein et al., 2014), and the overlap
between the animal and the source (e.g., spatial, temporal, and
spectral).
Auditory Injury (AUD INJ) and Permanent Threshold Shift (PTS)
NMFS defines auditory injury as ``damage to the inner ear that can
result in destruction of tissue . . . which may or may not result in
PTS'' (NMFS, 2024). NMFS defines PTS as a permanent irreversible
increase in the threshold of audibility at a specified frequency or
portion of an individual's hearing range above a previously established
reference level (NMFS, 2024). PTS does not generally affect more than a
limited frequency range, and an animal that has incurred PTS has
incurred some level of hearing loss at the relevant frequencies;
typically, animals with PTS are not functionally deaf (Au and Hastings,
2008, Finneran, 2016). Available data from humans and other terrestrial
mammals indicate that a 40 dB threshold shift approximates PTS onset
(see Ahroon et al., 1996, Kryter et al., 1966, Miller, 1974, Ward et
al., 1958, 1959, Ward, 1960, Henderson et al., 2008). PTS levels for
marine mammals are estimates because there are limited empirical data
measuring PTS in marine mammals (e.g., Kastak et al., 2008), largely
due to the fact that, for various ethical reasons, experiments
involving anthropogenic noise exposure at levels inducing PTS are not
typically pursued or authorized.
Temporary Threshold Shift (TTS)
NMFS defines TTS as 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, 2018). Based on data from cetacean TTS measurements (see
Southall et al., 2007, 2019), a TTS of 6 dB is considered the minimum
TS clearly larger than any day-to-day or session-to-session variation
in a subject's normal hearing ability (Finneran et al., 2000, 2022,
Schlundt et al., 2000). As described in Finneran (2015), marine mammal
studies have shown the amount of TTS increases with cumulative sound
exposure level (SELcum) in an accelerating fashion: At low exposures
with lower SELcum, the amount of TTS is typically small and the growth
curves have shallow slopes. At exposures with higher SELcum, the growth
curves become steeper and approach linear relationships with the noise
SEL.
Depending on the degree (elevation of threshold in dB), duration
(i.e., recovery time), and frequency range of TTS, and the context in
which it is experienced, TTS can have effects on marine mammals ranging
from discountable to serious (similar to those discussed in 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 serious impacts. We note that reduced hearing sensitivity as
a simple function of aging has been observed in marine mammals, as well
as humans and other taxa (Southall et al., 2007), so we can infer that
strategies exist for coping with this condition to some degree, though
likely not without cost.
Many studies have examined noise-induced hearing loss in marine
mammals (see Finneran (2015) and Southall et al., (2019) for
summaries). TTS is the mildest form of hearing impairment that can
occur during exposure to sound (Kryter, 2013). While experiencing TTS,
the hearing threshold rises, and a sound must be at a higher level in
order to be heard. In terrestrial and marine mammals, TTS can last from
minutes or hours to days (in cases of strong TTS). In many cases,
hearing sensitivity recovers rapidly after exposure to the sound ends.
For cetaceans, published data on the onset of TTS are limited to
captive bottlenose dolphin (Tursiops truncatus), beluga whale, harbor
porpoise, and Yangtze finless porpoise (Neophocoena asiaeorientalis)
(Southall et al., 2019). For pinnipeds in water, measurements of TTS
are limited to harbor seals, elephant seals (Mirounga angustirostris),
bearded seals (Erignathus barbatus) and California sea lions (Kastak et
al., 1999, Southall et al., 2007, Kastelein et al., 2019b, 2019c, 2021,
2022a, 2022b, Reichmuth et al., 2019, Sills et al., 2020). TTS was not
observed in spotted (Phoca largha) and ringed (Pusa hispida) seals
exposed to single airgun impulse sounds at levels matching previous
predictions of TTS onset (Reichmuth et al., 2016). These studies
examine hearing thresholds measured in marine mammals before and after
exposure to intense or long-duration sound exposures. The difference
between the pre-exposure and post-exposure thresholds can be used to
determine the amount of threshold shift at various post-exposure times.
The amount and onset of TTS depends on the exposure frequency.
Sounds at low frequencies, well below the region of best sensitivity
for a species or hearing group, are less hazardous than those at higher
frequencies, near the region of best sensitivity (Finneran and
Schlundt, 2013). At low frequencies, onset-TTS exposure levels are
higher compared to those in the region of best sensitivity (i.e., a low
frequency noise would need to be louder to cause TTS onset when TTS
exposure level is higher), as shown for harbor porpoises and harbor
seals (Kastelein et al., 2020a, Kastelein et al., 2020b, Kastelein et
al., 2019a, Kastelein et al., 2019c). Note that in general, harbor
seals and harbor porpoises have a lower TTS onset than other measured
pinniped or cetacean species (Finneran, 2015). In addition, TTS can
accumulate across multiple exposures, but the resulting TTS will be
less than the TTS from a single, continuous exposure with the same SEL
(Finneran et al., 2010, Kastelein et al., 2015, Kastelein et al., 2014,
Mooney et al., 2009). This means that TTS predictions based on the
total, SELcum will overestimate the amount of TTS from intermittent
exposures such as sonars and impulsive sources.
Nachtigall et al. (2018) describe measurements of hearing
sensitivity of multiple odontocete species (bottlenose dolphin, harbor
porpoise, beluga, and false killer whale (Pseudorca crassidens)) when a
relatively loud sound was preceded by a warning sound. These captive
animals were shown to reduce hearing sensitivity when warned of an
impending intense sound. Based on these experimental observations of
captive animals, the authors suggest that wild animals may dampen their
hearing during prolonged exposures or if conditioned to anticipate
intense sounds. Another study showed that echolocating animals
(including odontocetes) might have anatomical specializations that
might allow for conditioned hearing reduction and filtering of low-
frequency ambient noise, including increased stiffness and control of
middle ear structures and placement of inner ear structures (Ketten et
al., 2021). Data available on noise-induced hearing loss for mysticetes
are currently lacking (NMFS, 2018). Additionally, the existing marine
[[Page 35779]]
mammal TTS data come from a limited number of individuals within these
species.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals, and there is no PTS data for cetaceans. However,
such relationships are assumed to be similar to those in humans and
other terrestrial mammals. PTS typically occurs at exposure levels at
least several dB above that inducing mild TTS (e.g., a 40-dB threshold
shift approximates PTS onset (Kryter et al., 1966, Miller, 1974), while
a 6-dB threshold shift approximates TTS onset (Southall et al., 2007,
Southall et al., 2019)). Based on data from terrestrial mammals, a
precautionary assumption is that the PTS thresholds for impulsive
sounds (such as impact pile driving pulses as received close to the
source) are at least 6 dB higher than the TTS threshold on a peak-
pressure basis, and PTS cumulative sound exposure level thresholds are
15 to 20 dB higher than TTS cumulative sound exposure level thresholds
(Southall et al., 2007, 2019). Given the higher level of sound or
longer exposure duration necessary to cause PTS as compared with TTS,
it is considerably less likely that PTS could occur.
8 Star Alaska proposes to conduct vibratory and impact pile driving
activities and use AHTs to manage anchors during pipelaying. There
would likely be pauses in activities during the day. Given these pauses
and the fact that many marine mammals are likely to be moving through
the ensonified area and not remaining for extended periods of time, the
potential for TS declines.
Behavioral Harassment
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., Moberg, 2000, Selye, 1950). In
many cases, an animal's first and sometimes most economical (in terms
of energetic costs) response is behavioral avoidance of the potential
stressor. Autonomic nervous system responses to stress typically
involve changes in heart rate, blood pressure, and gastrointestinal
activity. These responses have a relatively short duration and may or
may not have a significant long-term effect on an animal's fitness.
Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that
are affected by stress--including immune competence, reproduction,
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been
implicated in failed reproduction, altered metabolism, reduced immune
competence, and behavioral disturbance (e.g., Moberg, 1987, Blecha,
2000). Increases in the circulation of glucocorticoids are also equated
with stress (Romano et al., 2004).
The primary distinction between stress (which is adaptive and does
not normally place an animal at risk) and distress is the cost of the
response. During a stress response, an animal uses glycogen stores that
can be quickly replenished once the stress is alleviated. In such
circumstances, the cost of the stress response would not pose serious
fitness consequences. However, when an animal does not have sufficient
energy reserves to satisfy the energetic costs of a stress response,
energy resources must be diverted from other functions. This state of
distress will last until the animal replenishes its energetic reserves
sufficient to restore normal function.
Relationships between these physiological mechanisms, animal
behavior, and the costs of stress responses are well-studied through
controlled experiments for both laboratory and free-ranging animals
(Holberton et al., 1996, Hood et al., 1998, Jessop et al., 2003,
Krausman et al., 2004, Lankford et al., 2005). Stress responses due to
exposure to anthropogenic sounds or other stressors and their effects
on marine mammals have also been reviewed (Romano et al., 2002b, Fair
and Becker, 2000) 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 vessel 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. These and other
studies lead to a reasonable expectation that some marine mammals will
experience physiological stress responses upon exposure to acoustic
stressors and that it is possible that some of these would be
classified as distress. In addition, any animal experiencing TTS would
likely also experience stress responses (National Research Council,
2005); however, distress would be an unlikely result of these proposed
project activities based on observations of marine mammals during
previous, similar projects in the area.
In consideration of the range of potential effects (AUD INJ to
behavioral disturbance), we consider the potential exposure scenarios
and context in which species would be exposed to pile driving and AHT
noise. CIBWs may be present in low numbers during the work; therefore,
some individuals may be reasonably expected to be exposed to elevated
sound levels, including briefly those that exceed the Level B
harassment threshold for continuous or impulsive noise. However, CIBWs
would be expected to be transiting through the area, given this work is
proposed primarily in middle Cook Inlet (as described in the
Description of Marine Mammals in the Area of Specified Activities
section), thereby limiting exposure duration, as belugas in the area
would be expected to be headed to or from the concentrated foraging
areas farther north near the Susitna Delta and Knik and Turnigan Arms.
Similarly, humpback whales, fin whales, minke whales, gray whales,
killer whales, California sea lion, and Steller sea lions would not be
expected to remain in the area of the AHTs. Dall's porpoise, harbor
porpoise, and harbor seal have been sighted with more regularity than
many other species during oil and gas activities in Cook Inlet, but due
to the transitory nature of these species, they would be unlikely to
remain at any particular site for the full duration of the noise-
producing activity. In fact, during Hilcorp's jack-up rig-based
monitoring efforts in 2023, only one Dall's porpoise, two harbor seals,
and one harbor porpoise were observed across four different sightings,
and observations only lasted 1 to 5 minutes (Horsley and Larson, 2023).
Because of this and the relatively low-intensity source levels, the
likelihood of AUD INJ over the course of the AHT activities is
considered discountable. Harbor seals may linger or haul-out in the
area, but they are not known to do so in any large number or for
extended periods of time. Here we find there would be a small potential
for TTS during the use of AHTs for anchor handling but again, AUD INJ
would not be likely due to the nature of the activity. Potential for
AUD INJ and TTS due to pile driving is discussed further in the
Estimated Take of Marine Mammals section.
Given most marine mammals would likely be transiting through the
area, exposure would be expected to be brief but, in combination with
the actual presence of the AHTs and pile driving, could result in
animals shifting pathways around the work site (e.g., avoidance),
increasing speed or dive times, or cessation of vocalizations. The
[[Page 35780]]
likelihood of no more than a short-term, localized disturbance response
is supported by data indicating belugas regularly pass by
industrialized areas such as the Port of Anchorage; therefore, we would
not expect abandonment of their transiting route or other disruptions
of their behavioral patterns. We also anticipate some animals may
respond with such mild reactions to the project that the response would
not be detectable.
While in some cases marine mammals have exhibited little to no
obviously detectable response to certain common or routine
industrialized activity (Cornick and Pinney, 2011), we conservatively
assume here that exposure to received levels of sound above the Level B
harassment threshold during AHT anchor-handling operations, in
conjunction with the nature of AHT operations (e.g., difficult to
maneuver, potential need to operate at night) means it is possible that
take could occur over the total estimated period of activities.
Masking
Sound can disrupt behavior through masking, or interfering 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). Masking occurs when the receipt
of a sound is interfered with by another coincident sound at similar
frequencies and at similar or higher intensity and may occur whether
the sound is natural (e.g., snapping shrimp, wind, waves,
precipitation) or anthropogenic (e.g., pile driving, shipping, sonar,
seismic exploration) in origin. 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. Masking of natural sounds can result when human activities
produce high levels of background sound at frequencies important to
marine mammals. Conversely, if the background level of underwater sound
is high (e.g., on a day with strong wind and high waves), an
anthropogenic sound source would not be detectable as far away as would
be possible under quieter conditions and would itself be masked.
Airborne Acoustic Effects
Pinnipeds that occur near the project site could be exposed to
airborne sounds associated with pile driving, depending on their
distance from pile driving activities. Cetaceans are not expected to be
exposed to airborne sounds that would result in harassment as defined
under the MMPA.
There are no known pinniped haulouts near the noise producing
project components. Therefore, it is unlikely that pinnipeds would be
taken by exposure to in-air noise during construction. We recognize
that pinnipeds in the water could be exposed to airborne sound that may
result in behavioral harassment when looking with their heads above
water. Most likely, airborne sound would cause behavioral responses
similar to those discussed above in relation to underwater sound. For
instance, anthropogenic sound could cause hauled-out pinnipeds to
exhibit changes in their normal behavior, such as reduction in
vocalizations, or cause them to temporarily abandon the area and move
further from the source. However, these animals would likely previously
have been ``taken'' because of exposure to underwater sound above the
behavioral harassment thresholds, which are generally larger than those
associated with airborne sound. Thus, the behavioral harassment of
these animals is already accounted for in these estimates of potential
take. Therefore, we are not proposing to authorize incidental take
solely from exposure to airborne sound for pinnipeds, and airborne
sound is not discussed further.
Marine Mammal Habitat Effects
8 Star Alaska's proposed activities could have localized, temporary
impacts on marine mammal habitat, including prey, by increasing in-
water sound pressure levels and, for pile driving, slightly decreasing
water quality. Increased noise levels may affect acoustic habitat and
adversely affect marine mammal prey in the vicinity of the project
area. Elevated levels of underwater noise would ensonify the project
areas where both fishes and mammals occur and could affect foraging
success.
The total seafloor area likely impacted by the pile driving
associated with the project would be relatively small compared to the
available habitat in Cook Inlet. Avoidance by potential prey (i.e.,
fish) of the immediate area due to the temporary loss of this foraging
habitat would be possible. The duration of fish and marine mammal
avoidance of this area after pile driving stops is unknown, but a rapid
return to normal recruitment, distribution, and behavior is
anticipated. Any behavioral avoidance by fish or marine mammals of the
disturbed area would still leave significantly large areas of fish and
marine mammal foraging habitat in the nearby vicinity.
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. Key impacts to fishes may include behavioral responses,
hearing damage, barotrauma (pressure-related injuries), and mortality.
Fishes utilize the soundscape and components of sound in their
environment to perform important functions such as foraging, predator
avoidance, mating, and spawning (Fay, 2009, Zelick et al., 1999).
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. Reactions also depend on the
physiological state of the fish, past exposures, motivation (e.g.,
feeding, spawning, migration), and other environmental factors.
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 fish; several are based on studies in support of large,
multiyear bridge construction projects (e.g., Scholik and Yan, 2002,
Scholik and Yan, 2001, Popper and Hastings,
[[Page 35781]]
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). 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).
SPLs of sufficient strength have been known to cause injury to
fishes and fish mortality (Popper et al., 2014). However, in most fish
species, hair cells in the ear continuously regenerate and loss of
auditory function likely is restored when damaged cells are replaced
with new cells. Halvorsen et al. (2012) 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 (Casper et al., 2013,
Halvorsen et al., 2012).
For pile driving, the most likely impact to fishes at the project
site would be temporary avoidance of the area, although alarmed
responses, including an increase in swimming speed and changes in
ventilation and heart rate, could occur. The duration of fish avoidance
of this area or an alarm response after pile driving stops is unknown,
but a rapid return to normal recruitment, distribution, and behavior is
anticipated. In relation to AHT activities, fish have been observed to
react when engine and propeller sounds exceed a certain level (Ona and
God[oslash], 1990, Ona, 1988, Olsen, 1983). Avoidance reactions have
been observed in fish, including cod and herring, when vessel sound
levels were 110 to 130 dB re 1 [mu]Pa root-mean-squared (RMS) (Ona and
God[oslash], 1990, Nakken, 1992, Olsen, 1979, Ona and Toresen, 1988).
Vessel sound source levels in the audible range for fish are typically
150 to 170 dB re 1 [mu]Pa per Hz (Richardson et al., 1995). The AHTs
used during the specified activity could be expected to produce levels
in this range when in transit. However, much of the tugging would be
mobile during anchor handling, and the tugging noise that occurs during
anchor handling would be temporary, similar to pile driving. Therefore,
based upon the reports in the literature and the predicted sound levels
from these vessels, some temporary avoidance by fish in the immediate
area may occur.
In addition to fish, prey sources such as marine invertebrates
could potentially be impacted by noise stressors as a result of the
proposed activities. However, most marine invertebrates' ability to
sense sounds is limited. Invertebrates appear to be able to detect
sounds (Pumphrey, 1950, Frings and Frings, 1967) and are most sensitive
to low-frequency sounds (Packard et al., 1990, Budelmann and
Williamson, 1994, Lovell et al., 2005, Mooney et al., 2010). Data on
response of invertebrates such as squid, another marine mammal prey
species, to anthropogenic sound is more limited (de Soto, 2016,
Sol[eacute] et al., 2017). Data suggest that cephalopods are capable of
sensing the particle motion of sounds and detect low frequencies up to
1-1.5 kHz, depending on the species (Kaifu et al., 2008, Hu et al.,
2009, Mooney et al., 2010, Samson et al., 2014). Sole et al. (2017)
reported physiological injuries to cuttlefish in cages placed at-sea
when exposed during a controlled exposure experiment to low-frequency
sources (315 Hz, 139 to 142 dB re 1m Pascal (Pa)\2\ and 400 Hz, 139 to
141 dB re 1m Pa\2\). Fewtrell and McCauley (2012) reported squids
maintained in cages displayed startle responses and behavioral changes
when exposed to seismic airgun sonar (136-162 re 1m Pa\2\[middot]s).
Jones et al. (2020) found that when squid (Doryteuthis pealeii) were
exposed to impulse pile driving noise, body pattern changes, inking,
jetting, and startle responses were observed, and nearly all squid
exhibited at least one response. However, these responses occurred
primarily during the first eight impulses and diminished quickly,
indicating potential rapid, short-term habituation.
Cephalopods have a specialized sensory organ inside the head called
a statocyst that may help an animal determine its position in space
(orientation) and maintain balance (Budelmann, 1992). Packard et al.
(1990) showed that cephalopods were sensitive to particle motion, not
sound pressure, and Mooney et al. (2010) demonstrated that squid
statocysts act as an accelerometer through which particle motion of the
sound field can be detected (Budelmann, 1992). Auditory injuries
(lesions occurring on the statocyst sensory hair cells) have been
reported upon controlled exposure to low-frequency sounds, suggesting
that cephalopods are particularly sensitive to low-frequency sound
(Andr[eacute] et al., 2011, Sol[eacute] et al., 2013). Behavioral
responses, such as inking and jetting, have also been reported upon
exposure to low-frequency sound (McCauley et al., 2000, Samson et al.,
2014). Squids, like most fish species, are likely more sensitive to low
frequency sounds and may not perceive mid- and high-frequency sonars.
With regard to potential impacts on zooplankton, McCauley et al.
(2017) found that exposure to airgun noise resulted in significant
depletion for more than half the taxa present and that there were two
to three times more dead zooplankton after airgun exposure compared
with controls for all taxa, within 1 km (0.6 mi) of the airguns.
However, the results of this study are inconsistent with a large body
of research that generally finds limited spatial and temporal impacts
to zooplankton as a result of exposure to airgun noise (e.g., Dalen and
Knutsen, 1987, Payne, 2004, Stanley et al., 2011). Most prior research
on this topic, which has focused on relatively small spatial scales,
has showed minimal effects (e.g., Bolle et al., 2012, Booman et al.,
1996, Kostyuchenko, 1973, Pearson et al., 1994, Saetre and Ona, 1996).
Notably, a more recent study produced results inconsistent with
those of McCauley et al. (2017). Researchers conducted a field and
laboratory study to assess if exposure to airgun noise affects
mortality, predator escape response, or gene expression of the copepod
Calanus finmarchicus (Fields et al., 2019). There were no sublethal
effects on the escape performance or the sensory threshold needed to
initiate an escape response at any of the distances from the airgun
that were tested. Whereas McCauley et al. (2017) reported an SEL of 156
dB at a range of 509-658 m (1,670-2,159 feet (ft)), with zooplankton
mortality observed at that range, Fields et al. (2019) reported an SEL
of 186 dB at a range of 25 m (82 ft), with no reported mortality at
that distance.
In summary, given the relatively small areas potentially affected,
the short duration of sound associated with individual pile driving
events, and the temporary nature of the use of AHTs for anchor handling
activities, any adverse effects from 8 Star Alaska's activities on any
prey habitat or prey populations would be 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
conclude that the specified activities would not be likely to have more
than short-term adverse effects on any prey habitat or
[[Page 35782]]
populations of prey species. Further, any impacts to marine mammal
habitat would not be 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 under the rule, 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).
Proposed takes would primarily be by Level B harassment, as
exposure to sound resulting from use of the acoustic sources (i.e.,
pile driving and AHT activities) has the potential to result in
disruption of behavioral patterns for individual marine mammals. We
note here that given the slow, predictable, and generally straight path
of tugs towing and positioning, the likelihood of a resulting
disruption of marine mammal behavioral patterns that would qualify as
harassment is considered relatively low. However, in consideration of
the relatively louder sound produced by these tugs and the sensitive
context present in Cook Inlet, NMFS cannot consider the likelihood of
take to be discountable and here consider it to be sufficiently likely
that quantified exposures above the generalized harassment threshold
equate to take. Therefore, we have quantified the potential exposures
from this activity, assumed that these exposures would equate to take,
and analyzed the impacts of the assumed takes, which we propose for
authorization. There is also some potential for AUD INJ (Level A
harassment) to result due to impact pile driving, primarily for
mysticetes, very high frequency species, and phocids because predicted
AUD INJ zones are larger than for high-frequency species and otariids.
AUD INJ is unlikely to occur for high-frequency species. The proposed
mitigation and monitoring measures would be expected to minimize the
severity of the taking to the extent practicable.
As described previously, no serious injury or mortality is
anticipated or proposed to be authorized for this activity. Below we
describe how the proposed take numbers are estimated.
For acoustic impacts, generally speaking, we estimate take by
considering: (1) acoustic criteria above which NMFS believes the best
available science indicates marine mammals will likely be behaviorally
harassed or incur some degree of AUD INJ; (2) the area or volume of
water that will be ensonified above these levels in a day; (3) the
density or occurrence of marine mammals within these ensonified areas;
and, (4) the number of days of activities. We note that while these
factors can contribute to a basic calculation to provide an initial
prediction of potential takes, additional information that can
qualitatively inform take estimates is also sometimes available (e.g.,
previous monitoring results or average group size). Below, we describe
the factors considered here in more detail and present the proposed
take estimates.
Acoustic Criteria
NMFS recommends the use of acoustic criteria that identify the
received level of underwater sound above which exposed marine mammals
would be reasonably expected to be behaviorally harassed (equated to
Level B harassment) or to incur AUD INJ of some degree (equated to
Level A harassment). 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, Southall et al., 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.
8 Star Alaska's proposed activity includes the use of continuous
(vibratory pile driving and AHTs engaged in anchor handling) and
impulsive (impact pile driving) sources, and therefore the RMS SPL
thresholds of 120 and 160 dB re 1 [mu]Pa are applicable.
Level A harassment--NMFS' Updated Technical Guidance for Assessing
the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version
3.0) (Updated Technical Guidance, 2024) identifies dual criteria to
assess AUD INJ (Level A harassment) to five different underwater marine
mammal groups (based on hearing sensitivity) as a result of exposure to
noise from two different types of sources (impulsive or non-impulsive).
8 Star Alaska's proposed activity includes the use of impulsive (impact
pile driving) and non-impulsive (vibratory pile driving and use of
AHTs) sources.
The 2024 Updated Technical Guidance criteria include both updated
thresholds and updated weighting functions for each hearing group. The
thresholds are provided in table 6 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 35783]]
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 [mu]Pa, and weighted cumulative sound
exposure level (LE,p) has a reference value of 1 [mu]Pa\2\s. In this Table, criteria are abbreviated to be
more reflective of International Organization for Standardization standards (ISO, 2017, ISO, 2020). 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 noise from pile driving and AHTs engaging in
anchor handling from the proposed project.
Pile Driving
8 Star Alaska proposes to conduct vibratory pile installation and
removal and impact pile installation. Source levels for these
activities are based on reviews of measurements of the same or similar
types and dimension of piles available in the literature. Source levels
for each pile size and activity are presented in table 7. Source levels
for vibratory installation and removal of piles of the same diameter
are assumed to be the same.
8 Star Alaska proposes to conduct concurrent pile driving during
construction of the combi-wall and coffer cells in the Marine Terminal
MOF. When two noise sources have overlapping sound fields, the sources
are considered additive and combined using the rules of dB addition.
For addition of two concurrent sources, the difference between the two
sound source levels is calculated, and if that difference is between 0
and 1 dB, 3 dB are added to the higher sound source levels; if the
difference is between 2 and 3 dB, 2 dB are added to the highest sound
source levels; if the difference is between 4 and 9 dB, 1 db is added
to the highest sound source levels; and with differences of 10 or more
dB, there is no addition. For two concurrent sources of different type
(i.e., impact and vibratory driving), there is no sound source
addition. Combinations of concurrent pile driving and the predicted
source values are shown in table 8. All concurrent pile driving would
consist of two vibratory hammers.
Table 7--Sound Source Levels for Single Hammer Pile Driving
----------------------------------------------------------------------------------------------------------------
Source level (at 10 m)
------------------------------------------------
Pile type Peak (dB re 1 SEL (dB re 1 RMS (dB re 1 Proxy Source
[mu]Pa) [mu]Pa2 sec) [mu]Pa)
----------------------------------------------------------------------------------------------------------------
Impact
----------------------------------------------------------------------------------------------------------------
Sheet Pile................... 205 180 190 24-inch (61-cm) Caltrans
AZ Sheet Pile. (2015).
24-inch Steel Pipe Pile...... 203 177 190 24-inch (61-cm) Caltrans
Steel Pipe Pile. (2015).
48-inch Steel Pipe Pile...... 213 179 192 48-inch (121.9- Caltrans
cm) Steel Pipe (2020).
Pile.
60-inch Steel Pipe Pile...... 210 185 195 60-inch (152.4 Caltrans
cm) Steel Pipe (2020).
Pile.
----------------------------------------------------------------------------------------------------------------
Vibratory
----------------------------------------------------------------------------------------------------------------
Sheet Pile................... N/A N/A 160 24-inch (61-cm) Caltrans
AZ Sheet Pile. (2015).
24-inch Steel Pipe Pile)..... N/A N/A 163 20- to 24-inch U.S. Navy
(50.8- to 61- (2012, 2013),
cm) Steel Pipe (Miner, 2020).
Pile.
66-inch Steel Pipe Pile...... N/A N/A 170 49- to 72-inch Caltrans
(124.5-182.9- (2020),
cm) to Steel Illingworth &
Pipe Piles Rodkin (2021).
(average).
----------------------------------------------------------------------------------------------------------------
Table 8--Concurrent Pile Driving Scenarios and Predicted Source Levels
[All vibratory hammers]
------------------------------------------------------------------------
Predicted RMS (dB re 1
Concurrent pile driving scenarios [mu]Pa) at 10 m
------------------------------------------------------------------------
66-inch Steel Pipe Pile x 2.................... 173
66-inch Steel Pipe Pile with Sheet Pile........ 170
Sheet Pile x 2................................. 163
[[Page 35784]]
24-inch Steel Pipe Pile with Sheet Pile........ 165
24-inch Steel Pipe Pile x 2.................... 166
------------------------------------------------------------------------
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
topography. The general formula for underwater TL is:
TL = B * Log10 (R<INF>1</INF>/R<INF>2</INF>),
Where:
TL = transmission loss in dB;
B = transmission loss coefficient;
R<INF>1</INF> = the distance of the modeled SPL from the driven
pile; and
R<INF>2</INF> = the distance from the driven pile of the initial
measurement.
Absent site-specific acoustical monitoring with differing measured
transmission loss, a practical spreading value of 15 is used as the
transmission loss coefficient in the above formula. Project and site-
specific transmission loss data for 8 Star Alaska's project area in
Cook Inlet are not available; therefore, the default coefficient of 15
is used to determine the distances to the Level A and Level B
harassment thresholds for all pile driving. All Level B harassment
isopleths are reported in table 10. However, as discussed in the
Proposed Monitoring and Reporting section, 8 Star Alaska would conduct
SSV for pile driving. Following the analysis of SSV results, 8 Star
Alaska may propose revised estimated Level A and Level B harassment
zones (for the purpose of monitoring and reporting) and adjusted
shutdown zones accordingly for NMFS review and approval.
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. 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 impact and vibratory pile driving and AHTs
engaged in anchor handling, 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 are provided in table
9, and the resulting estimated isopleths are reported in table 10.
Table 9--User Spreadsheet Input Parameters Used for Calculating Level A Harassment Isopleths
[Source levels provided in Table 7]
----------------------------------------------------------------------------------------------------------------
Duration to Weighting
Pile Piles per day Strikes per drive pile factor
pile (min) adjustment
----------------------------------------------------------------------------------------------------------------
Impact
----------------------------------------------------------------------------------------------------------------
Sheet Pile...................................... 30 1,000 N/A 2
24-inch Steel Pipe Pile......................... 4 1,000 N/A 2
48-inch Steel Pipe Pile......................... 3 1,000 N/A 2
60-inch Steel Pipe Pile......................... 4 1,000 N/A 2
----------------------------------------------------------------------------------------------------------------
Vibratory
----------------------------------------------------------------------------------------------------------------
Sheet Pile...................................... 30 N/A 15 2.5
24-inch Steel Pipe Pile......................... 8 N/A 15 2.5
66-inch Steel Pipe Pile......................... 7 N/A 15 2.5
----------------------------------------------------------------------------------------------------------------
Concurrent Pile Driving With Two Vibratory Hammers
----------------------------------------------------------------------------------------------------------------
66-inch Steel Pipe Pile x 2..................... 1 N/A * 105 2.5
66-inch Steel Pipe Pile with Sheet Pile......... 1 N/A * 450 2.5
Sheet pile x 2.................................. 1 N/A * 450 2.5
24-inch Steel Pipe Pile with Sheet Pile......... 1 N/A * 450 2.5
24-inch Steel Pipe Pile x 2..................... 1 N/A * 120 2.5
----------------------------------------------------------------------------------------------------------------
* This value represents the maximum duration of concurrent activity.
[[Page 35785]]
Table 10--Calculated Distances to Level A and Level B Harassment Isopleths for Pile Driving
----------------------------------------------------------------------------------------------------------------
Level A harassment zone (m)
----------------------------------------------------------------- Level B
Pile VHF harassment
LF cetacean HF cetacean cetacean Phocids Otariids zone (m)
----------------------------------------------------------------------------------------------------------------
Impact
----------------------------------------------------------------------------------------------------------------
Sheet Pile........................ 6,061 773 9,380 5,385 2,007 1,000
24-inch Steel Pipe Pile........... 998 127 1,545 887 331 1,000
48-inch Steel Pipe Pile........... 1,120 143 1,733 995 371 1,359
60-inch Steel Pipe Pile........... 3,408 435 5,274 3,028 1,120 2,154
----------------------------------------------------------------------------------------------------------------
Vibratory
----------------------------------------------------------------------------------------------------------------
Sheet Pile........................ 30 12 25 39 13 4,642
24-inch Steel Pipe Pile........... 20 8 16 26 9 7,356
66-inch Steel Pipe Pile........... 53 21 44 69 23 21,544
----------------------------------------------------------------------------------------------------------------
Concurrent Pile Driving With Two Vibratory Hammers
----------------------------------------------------------------------------------------------------------------
66-inch Steel Pipe Pile x 2....... 85 33 69 109 37 34,146
66-inch Steel Pipe Pile With Sheet 141 54 115 181 61 21,544
Pile.............................
Sheet Pile x 2.................... 48 19 39 62 21 7,356
24-inch Steel Pipe Pile With Sheet 32 12 26 41 14 11,659
Pile.............................
24-inch Steel Pipe Pile x 2....... 65 25 53 84 28 10,000
----------------------------------------------------------------------------------------------------------------
Except for Level B harassment areas of ensonification for the
single hammer vibratory installation of 66-inch steel pipe pile, the
concurrent vibratory installation of two 66-inch piles, and the
concurrent vibratory installation of a 66-inch steel pipe pile with a
sheet pile, estimated areas of ensonification were calculated for pile
driving using the formula of \1/2\[pi]r\2\, where r is the respective
isopleth. For the single hammer vibratory installation of 66-inch steel
pipe pile, the concurrent vibratory installation of two 66-inch piles,
and the concurrent vibratory installation of a 66-inch steel pipe pile
with a sheet pile, the Level B harassment isopleths were truncated by
land, and therefore \1/2\[pi]r\2\ was not representative of the area of
ensonification. Therefore, mapping software was used to draw the
estimated area of ensonification. Estimated Level A and Level B
harassment areas of ensonification are in table 11.
NMFS used the following formula to estimate the area of
ensonification for AHTs engaged in anchor handling, where distance
traveled per day is the linear distance that the AHTs would be expected
to travel over the course of a day, and r is the radial distance of the
Level B harassment isopleth (3.85 km). 8 Star Alaska estimates the
pipelay rate to be 2,500 feet/day (0.762 km/day), so 0.762 km was used
as the distance traveled per day.
Area of ensonification = (Distance traveled per day x 2r) + [pi]r\2\
Table 11--Calculated Level A and B Harassment Areas of Ensonification
----------------------------------------------------------------------------------------------------------------
Level A harassment areas of ensonification (km\2\) Level B
----------------------------------------------------------------- harassment
Pile area of
LF cetacean HF cetacean VHF Phocids Otariids ensonification
cetacean (km\2\)
----------------------------------------------------------------------------------------------------------------
Impact
----------------------------------------------------------------------------------------------------------------
Sheet Pile..................... 57.7 0.94 138.21 45.47 6.33 1.57
24-inch Steel Pipe Pile........ 1.56 0.03 3.75 1.24 0.17 1.57
48-inch Steel Pipe Pile........ 1.97 0.03 4.72 1.56 0.22 2.9
60-inch Steel Pipe Pile........ 18.24 0.3 43.69 14.4 2.0 7.29
----------------------------------------------------------------------------------------------------------------
Vibratory
----------------------------------------------------------------------------------------------------------------
Sheet Pile..................... 0.00 0.00 0.00 0.00 0.00 33.85
24-inch Steel Pipe Pile........ 0.00 0.00 0.00 0.00 0.00 24.89
66-inch Steel Pipe Pile........ 0.00 0.00 0.00 0.00 0.00 62.54
66-inch Steel Pipe Pile x 2.... 0.01 0.00 0.01 0.02 0.00 1,426.4
66-inch Steel Pipe Pile with 0.03 0.00 0.02 0.05 0.01 722.5
Sheet Pile....................
Sheet Pile x 2................. 0.00 0.00 0.00 0.01 0.00 85
24-inch Steel Pipe Pile With 0.01 0.00 0.00 0.01 0.00 157.08
Sheet Pile....................
24-inch Steel Pipe Pile x 2.... 0.00 0.00 0.00 0.00 0.00 213.5
----------------------------------------------------------------------------------------------------------------
AHTs
----------------------------------------------------------------------------------------------------------------
Anchor Handling................ 0.00 0.00 0.00 0.01 0.00 52.4
----------------------------------------------------------------------------------------------------------------
Level A harassment zones are typically smaller than Level B
harassment zones. However, in some cases, the calculated Level A
harassment isopleth is greater than the calculated Level B harassment
isopleth. Calculation of Level A harassment isopleths include a
duration component, which in the case of impact pile driving, is
estimated through the total number of daily strikes and the associated
pulse duration. For a stationary sound source, we assume here that an
animal is exposed to all of the strikes expected within a 24-hour
period. Calculation of
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a Level B harassment zone does not include a duration component.
Depending on the duration included in the calculation, the calculated
Level A harassment isopleths can be larger than the calculated Level B
harassment isopleth for the same activity.
Mainline Installation
8 Star Alaska intends to use AHTs to position a pipelaying barge in
order to install the pipe on the seafloor for the Mainline across Cook
Inlet. For the nearshore pipelay, planned for Year 3, an AHT would
engage in anchor handling to moor a pull barge, and is expected to be
used for two days of work, one day on the west coast near Beluga and
one day on the east coast near Suneva Lake. For offshore pipelay, AHTs
would be engaged in anchor handling to repeatedly position the barge
during the duration of pipelay. Consistent with other tug activities,
including those for tugs towing a jack-up rig (Furie Operating Alaska,
LLC Natural Gas Activities, 89 FR 77836, September 24, 2024; Hilcorp
Alaska, LLC, 89 FR 79529, September 30, 2024), NMFS anticipates that
the AHTs would operate at approximately 50 percent power during anchor
handling activities.
Because of the similarities to tugging activities planned by
Hilcorp in Cook Inlet (89 FR 79529, September 30, 2024), NMFS
determined it appropriate to adopt analysis provided for those
activities for 8 Star Alaska's planned tugging activities. In addition,
we refer here to an existing literature review of available source
level data for tugs under load in varying power output scenarios (87 FR
27597, May 9, 2022). Please see that notice for the detailed analysis.
While that analysis is for tugs under load towing a jack-up rig, NMFS
expects the AHT power output for the proposed anchor handling is to be
consistent with that assumed for tugs towing a jack-up rig (Furie
Operating Alaska, LLC Natural Gas Activities, 89 FR 77836, September
24, 2024; Hilcorp Alaska, LLC, 89 FR 79529, September 30, 2024), and
therefore, NMFS determined that this analysis represents the best
scientific evidence available for considering the appropriate source
level proxy for 8 Star Alaska's proposed AHT use during anchor
handling.
In addition to the literature review referenced above, which
indicates that a source level of 180 dB for a single AHT would be
appropriate, we also consider other relevant information to adequately
consider 8 Star Alaska's planned use of three AHTs to handle anchors.
If all three tugs were operating simultaneously at 180 dB RMS, the
overall source emission levels would be expected to increase by
approximately 5 dB when logarithmically adding the sources (i.e., to
185 dB RMS). To further support this level as an appropriate proxy, a
sound source verification (SSV) study performed by JASCO Applied
Sciences (JASCO) in Cook Inlet in October 2021 (Lawrence et al., 2022)
measured the sound source level from three tugs pulling a jack-up rig
in Cook Inlet at various power outputs. Lawrence et al. (2022) reported
a source level of 167.3 dB RMS for the 20 percent-power scenario and a
source level of 205.9 dB RMS for the 85 percent-power scenario.
Assuming a linear scaling of tug power, a source level of 185 dB RMS
was calculated as a single point source level for three tugs operating
at 50 percent power output. Therefore, the analyses presented below use
a mean tug sound source level scenario of 185 dB RMS to estimate
distances to the 120 dB RMS isopleth for three tugs operating at 50
percent power output. In practice, the load condition of the three tugs
is unlikely to be identical at all times, so sound emissions would be
dominated by the single tug in the group that is working hardest at any
point in time. NMFS, therefore, has determined it appropriate to use
the source level of 185 dB RMS at 1 m to represent the use of three
AHTs. Modeling using this source level resulted in an estimated
distance to the 120-dB isopleth of 3,850 m. Please see 89 FR 79529
(September 30, 2024) for full detail.
As noted previously, NMFS determined that Level A harassment would
not be a reasonably likely outcome of the use of AHTs. In order to
characterize the extent of the Level A harassment isopleths to provide
additional quantitative support for this determination, NMFS used the
NMFS user spreadsheet to calculate Level A harassment zones for each
hearing group for AHTs conducting anchor handling. NMFS used Tab A
(Non-Impulse-Stat-Cont) in the spreadsheet and used a WFA of 2, a 6
hour duration of sound production within a 24 hour period, and a
propagation loss coefficient of 18.129. Weston and SLR (2022)
determined the average 120 dB isopleth was 3,850 meters for a
continuous noise source of 185 dB rms SPL across 25 locations in middle
Cook Inlet. The coefficient is calculated as (185 dB-120 dB)/
Log10(3850/1) = 18.129 dB per decade.)). Estimated Level A and Level B
harassment isopleths for AHTs engaged in anchor handling are reported
in table 12.
Table 12--Level A and Level B Harassment Isopleths From AHTs Engaged in Anchor Handling
----------------------------------------------------------------------------------------------------------------
Level A harassment isopleths (m) \1\ Level B
----------------------------------------------------------------- harassment
Sound source isopleth
LF HF VHF Phocids Otariids (m) \2\
----------------------------------------------------------------------------------------------------------------
3 AHTs............................ 53 21 28 62 21 3,850
----------------------------------------------------------------------------------------------------------------
\1\ Level A harassment isopleths calculated using NMFS User spreadsheet.
\2\ Level B harassment isopleth determined using results from Hilcorp's modeling.
Marine Mammal Occurrence
In this section we provide information about the occurrence of
marine mammals, including density or other relevant information which
will inform the take calculations.
8 Star Alaska requested take of humpback whale, killer whale,
beluga whale, harbor porpoise, and harbor seal. In addition to those
species, NMFS determined that minke whale, gray whale, fin whale,
Dall's porpoise, Pacific white-sided dolphin, Steller sea lion, and
California sea lion are likely to occur in the project area during 8
Star Alaska's activities and, accordingly, proposes to authorize take
for these species.
Densities for marine mammals in Cook Inlet were derived from NMFS
AFSC's Marine Mammal Laboratory (MML) aerial surveys, typically flown
in June, from 2000 to 2022 (Rugh et al., 2005, Shelden et al., 2013,
2015b, 2017, 2022, Shelden and Wade, Goetz et al., 2023) except for
beluga whales, for which other density data exist, or for Steller sea
lions, fin whale, Pacific white-sided dolphins, and California sea
lions, which occur too rarely to support development of density
estimates. Total survey area was not reported for the
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2021 or 2022 survey years (Shelden et al., 2022, Goetz et al., 2023) so
total survey area for 2021 and 2022 was estimated as 8,377.2 km\2\ for
each year based on previous reports. While the surveys are concentrated
for a few days in summer annually, which may skew densities for
seasonally present species, they represent the best available long-term
dataset of marine mammal sightings available in Cook Inlet. To estimate
the average density, the maximum number of individuals per species was
divided by the area surveyed, and NMFS used the average across all
survey years for each species.
CIBW densities estimated from the AFSC surveys across regions are
low; however, there is a known effect of seasonality on their
distribution. Thus, densities derived directly from these summer
surveys might underestimate the density of CIBWs in lower Cook Inlet at
other ice-free times of the year. Therefore, NMFS used the Goetz et al.
(2012a) habitat-based model to determine CIBW density. This model is
derived from sightings and incorporates depth soundings, coastal
substrate type, environmental sensitivity index, anthropogenic
disturbance, and anadromous fish streams to predict densities
throughout Cook Inlet. The output of this model is a density map of
Cook Inlet, which predicts spatially explicit density estimates for
CIBW. Using the resulting grid densities, average densities were
calculated for three regions applicable to 8 Star Alaska's operations
(table 13). The densities applicable to the area of activity (i.e., the
Marine Terminal near Nikiski, the Mainline in middle Cook Inlet, and
the Mainline MOF near Tyonek) are provided in table 13 and were carried
forward to the exposure estimates as they were deemed to be the most
representative estimates available.
Although data exists for Steller sea lions and fin whales in Cook
Inlet from AFSC aerial surveys, this data is based on sightings of
Steller sea lions and fin whales that were mostly observed in lower
Cook Inlet and is not representative of middle Cook Inlet, where 8 Star
Alaska proposes to conduct construction. Therefore, in order to
calculate take of these species, NMFS proposes to use marine mammal
occurrence.
For Steller sea lions, NMFS proposes to use monitoring data from
the Port of Alaska (POA) in Anchorage, as these animals would be
expected to pass through middle Cook Inlet and therefore be observed in
8 Star Alaska's Project Area. In 2020-2022 and 2024 (61 North
Environmental, 2021, 2022a, 2022b, 2025, Easley-Appleyard and Leonard,
2022), the maximum number of Steller sea lions observed at POA was nine
animals, eight during Petroleum and Cement Terminal (PCT) observations
(61 North Environmental, 2022a) and one during NMFS 2021 monitoring
effort (Easley-Appleyard and Leonard, 2022). Therefore, NMFS
anticipates that up to nine Steller sea lions may occur in the project
area per year during the course of 8 Star Alaska's proposed project.
During seismic surveys conducted in 2019 by Hilcorp in the lower
Cook Inlet, fin whales were recorded in groups ranging in size from one
to 15 individuals (Fairweather, 2020). During the NMFS aerial surveys
in Cook Inlet from 2000 to 2018, 10 sightings of 26 estimated
individual fin whales in lower Cook Inlet were observed (Shelden et al.
2013, 2015, 2016, 2019). Therefore, NMFS anticipates that one group of
two fin whales (the lower end of the range of common group sizes) may
occur in the project area per year during the course of 8 Star Alaska's
proposed project.
No density estimates are available for Pacific white-sided dolphins
and California sea lions, as they are so infrequently sighted.
Therefore, NMFS proposes to authorize take of these species based on
group number (see table 14).
Due to the paucity of data of Pacific white-sided dolphins in this
region, there is no available density for Pacific white-sided dolphins.
They are considered rare in most of Cook Inlet, including in the lower
entrance, but their presence was documented in Iniskin Bay and mid-
inlet through passive acoustic recorders in 2019 (Castellote et al.,
2020). In 2014, during Apache's seismic survey program, three Pacific
white-sided dolphins were reported (Lomac-MacNair et al. 2014).
While California sea lions are uncommon in Cook Inlet, two were
seen during the 2012 Apache seismic survey in Cook Inlet (Lomac-MacNair
et al., 2013). California sea lions in Alaska are typically alone but
may be seen in small groups usually associated with Steller sea lions
at their haul outs and rookeries (Maniscalco et al., 2004).
Table 13--Calculated Densities
------------------------------------------------------------------------
Density
Species (animals/
km\2\)
------------------------------------------------------------------------
Gray whale.............................................. 0.00070
Humpback whale.......................................... 0.00185
Minke whale............................................. 0.00003
Killer whale............................................ 0.00610
Beluga whale (Marine Terminal).......................... 0.00016
Beluga whale (Mainline Crossing)........................ 0.01070
Beluga whale (Mainline MOF)............................. 0.03680
Dall's porpoise......................................... 0.00014
Harbor porpoise......................................... 0.00380
Harbor seal............................................. 0.26819
------------------------------------------------------------------------
Table 14--Marine Mammal Occurrence *
------------------------------------------------------------------------
Expected
Species occurrence
(animals/year)
------------------------------------------------------------------------
Fin whale............................................... 2
Pacific white-sided dolphin............................. 3
California sea lion..................................... 2
Steller sea lion........................................ 9
------------------------------------------------------------------------
* Marine mammal occurrence is used when density data is unavailable or
not representative of the proposed project area.
Take Estimation
Here we describe how the information provided above is synthesized
to produce a quantitative estimate of the take that is reasonably
likely to occur and proposed for authorization.
To estimate take by Level B harassment for all species except for
fin whale, Pacific white-sided dolphin, California sea lion, and
Steller sea lion, 8 Star Alaska multiplied the area (km\2\) estimated
to be ensonified above the Level B harassment thresholds (table 11) for
each activity by the duration (days) of that activity by the calculated
density for each species (number of animals/km\2\). As described above,
take of fin whale, Pacific white-sided dolphin, California sea lion,
and Steller sea lion were calculated using group numbers and estimated
frequency of occurrence (see table 14).
For species where calculated take by Level B harassment was less
than the average group size for that species, NMFS rounded up the take
estimate to the anticipated group size as displayed in table 15 and
described below.
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During Apache's 2012 seismic program, nine sightings of a total of
nine gray whales were observed in June and July (Lomac-MacNair et al.,
2013). In 2014, one gray whale was observed during Apache's seismic
program (Lomac-MacNair et al., 2014) and in 2015, no gray whales were
observed during SAExploration's seismic survey (Kendall and Cornick,
2015). No gray whales were observed during the 2018 Cook Inlet Pipeline
(CIPL) Extension Project (Sitkiewicz et al., 2018) or during the 2019
Hilcorp seismic survey in lower Cook Inlet (Fairweather Science, 2020).
The greatest densities of gray whales in Cook Inlet occur from November
through January and March through May; the former are southbound, the
latter are northbound (Ferguson et al., 2015). Based on this
information, NMFS is proposing to authorize three takes by Level B
harassment annually for gray whales. This is higher than the exposure
estimate for each to allow for the potential occurrence of a group, or
several individuals, per year.
During annual aerial surveys conducted in Cook Inlet from 2000 to
2016, humpback group sizes ranged from one to 12 individuals, with most
groups comprised of 1 to 3 individuals (Shelden et al., 2013). Three
humpback whales were observed in Cook Inlet during SAExploration's
seismic study in 2015: two near the Forelands and one in Kachemak Bay
(Kendall and Cornick, 2015). In total, 14 sightings of 38 humpback
whales (ranging in group size from 1 to 14) were recorded in the 2019
Hilcorp lower Cook Inlet seismic survey in the fall (Fairweather
Science, 2020). Two sightings totaling three individual humpback whales
were recorded near Ladd Landing north of the Forelands on the recent
Harvest Alaska CIPL Extension Project (Sitkiewicz et al., 2018). Based
on documented observations from the CIPL Extension Project, which is
the data closest to 8 Star Alaska's project area, NMFS is proposing to
authorize three takes by Level B harassment for humpback whales for
years 3 and 5. For years 1, 2, and 4, the calculated take exceeds the
estimated group size.
Groups of up to three minke whales have been recorded in recent
years, including one group of three southeast of Kalgin Island (Lomac-
MacNair et al. 2014). Other recent surveys in Cook Inlet typically have
documented minke whales traveling alone (Shelden et al. 2013, 2015,
2017; Fairweather Science 2020). As the occurrence of minke whales is
expected to be lower in middle Cook Inlet than lower Cook Inlet and
considering the observed group sizes, NMFS is proposing to authorize
three takes of minke whale by Level B harassment for each year of 8
Star Alaska's project.
Killer whale pods typically consist of a few to 20 or more animals
(NMFS, 2025b). During seismic surveys conducted in 2019 by Hilcorp in
lower Cook Inlet, 21 killer whales were observed. Although also
observed as single individuals, killer whales were recorded during this
survey in groups ranging in size from two to five individuals
(Fairweather Science, 2020). One killer whale group of two individuals
was observed during the 2015 SAExploration seismic program near the
North Foreland (Kendall and Cornick, 2015). Based on recent documented
sightings, observed group sizes, and the established presence of killer
whales in Cook Inlet, NMFS is proposing to authorize 10 takes (2 groups
of 5 animals, the upper end of recently recorded group size) by Level B
harassment for killer whales for years 2-5.
The 2018 MML aerial survey (Shelden and Wade 2019) estimated a
median group size of approximately 11 beluga whales, although group
sizes were highly variable (2 to 147 whales) as was the case in
previous survey years (Boyd et al., 2019). Over 3 seasons of monitoring
at the Port of Alaska, 61 North reported groups of up to 53 belugas,
with a median group size of 3 and a mean group size of 4.4 (61 North
Environmental, 2021, 2022a, 2022b, 2022c). Additionally, vessel-based
surveys in 2019 observed beluga whale groups in the Susitna River Delta
that ranged from 5 to 200 animals (McGuire et al., 2022). The very
large groups seen in the Susitna River Delta are not expected in the
areas of 8 Star Alaska's construction. However, smaller groups (i.e.,
around the median group size) could be traveling through to access the
Susitna River Delta and other nearby coastal locations, particularly in
the shoulder seasons when belugas are more likely to occur in middle
Cook Inlet. Therefore, NMFS is proposing to authorize 11 takes by Level
B harassment of beluga whale in Years 1-3, and 5, in which calculated
exposures were below the median group size. Calculated takes of beluga
whales was greater than the median group size in year 4 and therefore
were not adjusted for group size.
Dall's porpoises are usually found in groups averaging between 2
and 12 individuals (NMFS, 2025a). During seismic surveys conducted in
2019 by Hilcorp in lower Cook Inlet, Dall's porpoises were recorded in
groups ranging from two to seven individuals (Fairweather Science,
2020). The 2012 Apache survey recorded two groups of three individual
Dall's porpoises (Lomac-MacNair et al., 2014). NMFS
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proposes to authorize six takes by Level B harassment per year for
Dall's porpoises. This is greater than the estimated exposure estimate
for each year, but would allow for at least one group at the higher end
of documented group size or a combination of small groups.
8 Star Alaska proposes to shut down at the Level A harassment
isopleth for all vibratory pile driving activities. The largest Level A
harassment isopleth during vibratory pile driving is 181 m, and NMFS
anticipates that 8 Star Alaska would be able to adequately monitor
these zones and shutdown appropriately. NMFS, therefore, does not
expect and does not propose to authorize Level A harassment due to
vibratory pile driving for any species. As discussed in the Acoustic
Impacts section, due to the characteristics of noise produced by AHTs,
e.g., low-intensity source levels relative to impact pile driving, and
transitory nature of occurrence of marine mammal species in this area,
auditory injury is not a likely outcome of this activity. Therefore,
NMFS does not expect, and does not propose to authorize, take by Level
A harassment due to AHTs engaging in anchor handling.
To estimate take by Level A harassment from impact pile driving, 8
Star Alaska multiplied the area (km\2\) estimated to be ensonified
above the Level A harassment thresholds (table 11) for each impact pile
driving activity by the duration (days) of that activity by the
calculated density for each species (number of animals/km\2\). Due to
the infrequency of occurrence of fin whales, Pacific white-sided
dolphins, California sea lions, and Steller sea lions in middle Cook
Inlet, NMFS does not expect these species to enter Level A harassment
zones for sufficient duration to incur injury, and is not proposing to
authorize take by Level A harassment of these species.
When attributing take to respective humpback whale stocks for each
year, NMFS assumed that 89 percent of calculated take would be from the
Hawai[revaps]i stock, 10.7 percent would be from the Mexico-North
Pacific stock, and 0.3 percent would be from the Western North Pacific
stock, as described in Wade (2021) (see table 17). Although the number
calculated for the Western North Pacific stock is less than 0.5
animals, NMFS is conservatively attributing one take by Level B
harassment to the Western North Pacific stock of the humpback whale.
For species for which take by Level A harassment is anticipated,
those estimated takes by Level A harassment were subtracted from the
estimated takes by Level B harassment to avoid double-counting the same
exposures as both Level A and Level B harassment. Adjustments are
reflected in table 17.
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[…truncated; see source link]Indexed from Federal Register on July 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.