Federal Register / Vol. 87, No. 89 / Monday, May 9, 2022 / Notices 27597 

taken is fewer than one third of the 

species or stock abundance, the take is 

considered to be of small numbers. 

Additionally, other qualitative factors 

may be considered in the analysis, such 

as the temporal or spatial scale of the 

activities. 

NMFS proposes to authorize 

incidental take of 15 marine mammal 

species (with 16 managed stocks). The 

total amount of takes proposed for 

authorization relative to the best 

available population abundance is less 

than 8.5 percent for all stocks which 

NMFS preliminarily finds are small 

numbers of marine mammals relative to 

the estimated overall population 

abundances for those stocks. Refer back 

to Table 3. 

Based on the analysis contained 

herein of the proposed activity 

(including the proposed mitigation and 

monitoring measures) and the 

anticipated take of marine mammals, 

NMFS preliminarily finds that small 

numbers of marine mammals will be 

taken relative to the population size of 

the affected species or stocks. 

Unmitigable Adverse Impact Analysis 

and Determination 

There are no relevant subsistence uses 

of the affected marine mammal stocks or 

species implicated by this action. 

Therefore, NMFS has determined that 

the total taking of affected species or 

stocks would not have an unmitigable 

adverse impact on the availability of 

such species or stocks for taking for 

subsistence purposes. 

Endangered Species Act 

Section 7(a)(2) of the Endangered 

Species Act of 1973 (ESA: 16 U.S.C. 

1531 et seq.) requires that each Federal 

agency insure that any action it 

authorizes, funds, or carries out is not 

likely to jeopardize the continued 

existence of any endangered or 

threatened species or result in the 

destruction or adverse modification of 

designated critical habitat. To ensure 

ESA compliance for the issuance of 

IHAs, NMFS Office of Protected 

Resources (OPR) consults internally 

whenever we propose to authorize take 

for endangered or threatened species. 

NMFS is authorizing the incidental take 

of four species of marine mammals 

which are listed under the ESA, 

including the North Atlantic right, fin, 

and sperm whale, and has determined 

that these activities fall within the scope 

of activities analyzed 107 in GARFO’s 

programmatic consultation regarding 

geophysical surveys along the U.S. 

Atlantic coast in the three Atlantic 

Renewable Energy Regions (completed 

June 29, 2021; revised September 2021). 

Proposed Authorization 

As a result of these preliminary 

determinations, NMFS proposes to issue 

an IHA to NEETMA for conducting 

high-resolution site characterization 

surveys off New Jersey for one year from 

the date of issuance, provided the 

previously mentioned mitigation, 

monitoring, and reporting requirements 

are incorporated. A draft of the 

proposed IHA can be found at https:// 

www.fisheries.noaa.gov/national/ 

marine-mammal-protection/incidentaltake-authorizations-other-energyactivities-renewable. 

Request for Public Comments 

We request comment on our analyses, 

the proposed authorization, and any 

other aspect of this notice of proposed 

IHA for the proposed marine site 

characterization surveys. We also 

request at this time comment on the 

potential Renewal of this proposed IHA 

as described in the paragraph below. 

Please include with your comments any 

supporting data or literature citations to 

help inform decisions on the request for 

this IHA or a subsequent Renewal IHA. 

On a case-by-case basis, NMFS may 

issue a one-time, one-year Renewal IHA 

following notice to the public providing 

an additional 15 days for public 

comments when (1) up to another year 

of identical or nearly identical activities 

as described in the Description of 

Proposed Activities section of this 

notice is planned or (2) the activities as 

described in the Description of 

Proposed Activities section of this 

notice would not be completed by the 

time the IHA expires and a Renewal 

would allow for completion of the 

activities beyond that described in the 

Dates and Duration section of this 

notice, provided all of the following 

conditions are met: 

• A request for Renewal is received 

no later than 60 days prior to the needed 

Renewal IHA effective date (recognizing 

that the Renewal IHA expiration date 

cannot extend beyond one year from 

expiration of the initial IHA). 

• The request for Renewal must 

include the following: 

(1) An explanation that the activities 

to be conducted under the requested 

Renewal IHA are identical to the 

activities analyzed under the initial 

IHA, are a subset of the activities, or 

include changes so minor (e.g., 

reduction in pile size) that the changes 

do not affect the previous analyses, 

mitigation and monitoring 

requirements, or take estimates (with 

the exception of reducing the type or 

amount of take). 

(2) A preliminary monitoring report 

showing the results of the required 

monitoring to date and an explanation 

showing that the monitoring results do 

not indicate impacts of a scale or nature 

not previously analyzed or authorized. 

Upon review of the request for 

Renewal, the status of the affected 

species or stocks, and any other 

pertinent information, NMFS 

determines that there are no more than 

minor changes in the activities, the 

mitigation and monitoring measures 

will remain the same and appropriate, 

and the findings in the initial IHA 

remain valid. 

Dated: May 4, 2022. 

Kimberly Damon-Randall, 

Director, Office of Protected Resources, 

National Marine Fisheries Service. 

[FR Doc. 2022–09917 Filed 5–6–22; 8:45 am] 

BILLING CODE 3510–22–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XB882] 

Takes of Marine Mammals Incidental to 

Specified Activities; Taking Marine 

Mammals Incidental to Tugs Towing 

Drill Rig in Cook Inlet, Alaska 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice; proposed incidental 

harassment authorizations; request for 

comments on proposed authorizations. 

SUMMARY: NMFS has received a request 

from Hilcorp Alaska LLC (Hilcorp) for 

authorization to take marine mammals 

incidental to tugboats towing a drill rig 

in Cook Inlet, Alaska. Pursuant to the 

Marine Mammal Protection Act 

(MMPA), NMFS is requesting comments 

on its proposal to issue two successive 

incidental harassment authorizations 

(IHAs) to incidentally take marine 

mammals during the specified activities. 

NMFS is also requesting comments on 

a possible one-time, one-year renewal 

that could be issued under certain 

circumstances and if all requirements 

are met, as described in Request for 

Public Comments at the end of this 

notice. NMFS will consider public 

comments prior to making any final 

decision on the issuance of the 

requested MMPA authorizations and 

agency responses will be summarized in 

the final notice of our decision. 

DATES: Comments and information must 

be received no later than June 8, 2022. 

ADDRESSES: Comments should be 

addressed to Jolie Harrison, Chief, 


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27598 Federal Register / Vol. 87, No. 89 / Monday, May 9, 2022 / Notices 

Permits and Conservation Division, 

Office of Protected Resources, National 

Marine Fisheries Service. Written 

comments should be submitted via 

email to ITP.Young@noaa.gov. 

Instructions: NMFS is not responsible 

for comments sent by any other method, 

to any other address or individual, or 

received after the end of the comment 

period. Comments, including all 

attachments, must not exceed a 25- 

megabyte file size. All comments 

received are a part of the public record 

and will generally be posted online at 

www.fisheries.noaa.gov/permit/ 

incidental-take-authorizations-undermarine-mammal-protection-act without 

change. All personal identifying 

information (e.g., name, address) 

voluntarily submitted by the commenter 

may be publicly accessible. Do not 

submit confidential business 

information or otherwise sensitive or 

protected information. 

FOR FURTHER INFORMATION CONTACT: Sara 

Young, Office of Protected Resources, 

NMFS, (301) 427–8401. Electronic 

copies of the application and supporting 

documents, as well as a list of the 

references cited in this document, may 

be obtained online at: https://

www.fisheries.noaa.gov/permit/ 

incidental-take-authorizations-undermarine-mammal-protection-act. In case 

of problems accessing these documents, 

please call the contact listed above. 

SUPPLEMENTARY INFORMATION: 

Background 

The MMPA prohibits the ‘‘take’’ of 

marine mammals, with certain 

exceptions. Sections 101(a)(5)(A) and 

(D) of the MMPA (16 U.S.C. 1361 et 

seq.) direct the Secretary of Commerce 

(as delegated to NMFS) to allow, upon 

request, the incidental, but not 

intentional, taking of small numbers of 

marine mammals by U.S. citizens who 

engage in a specified activity (other than 

commercial fishing) within a specified 

geographical region if certain findings 

are made and either regulations are 

proposed or, if the taking is limited to 

harassment, a notice of a proposed 

incidental harassment authorization is 

provided to the public for review. 

Authorization for incidental takings 

shall be granted if NMFS finds that the 

taking will have a negligible impact on 

the species or stock(s) and will not have 

an unmitigable adverse impact on the 

availability of the species or stock(s) for 

taking for subsistence uses (where 

relevant). Further, NMFS must prescribe 

the permissible methods of taking and 

other ‘‘means of effecting the least 

practicable adverse impact’’ on the 

affected species or stocks and their 

habitat, paying particular attention to 

rookeries, mating grounds, and areas of 

similar significance, and on the 

availability of the species or stocks for 

taking for certain subsistence uses 

(referred to in shorthand as 

‘‘mitigation’’); and requirements 

pertaining to the mitigation, monitoring 

and reporting of the takings are set forth. 

The definitions of all applicable MMPA 

statutory terms cited above are included 

in the relevant sections below. 

National Environmental Policy Act 

To comply with the National 

Environmental Policy Act of 1969 

(NEPA; 42 U.S.C. 4321 et seq.) and 

NOAA Administrative Order (NAO) 

216–6A, NMFS must review its 

proposed action (i.e., the issuance of an 

IHA) with respect to potential impacts 

on the human environment. 

Accordingly, NMFS is preparing an 

Environmental Assessment (EA) to 

consider the environmental impacts 

associated with the issuance of the 

proposed IHAs. NMFS’ EA will be made 

available at https://www.fisheries.

noaa.gov/permit/incidental-takeauthorizations-under-marine-mammalprotection-act at the time of publication. 

We will review all comments submitted 

in response to this notice prior to 

concluding our NEPA process or making 

a final decision on the IHA requests. 

Summary of Request 

On January 13, 2022, NMFS received 

a request from Hilcorp for two IHAs to 

take marine mammals incidental to tugs 

towing a drill rig in Cook Inlet, Alaska. 

The application was deemed adequate 

and complete on March 8, 2022. 

Hilcorp’s request is for take of small 

numbers of eleven species of marine 

mammals by Level B harassment only. 

Neither Hilcorp nor NMFS expects 

serious injury or mortality to result from 

this activity and, therefore, an IHA is 

appropriate. 

NMFS previously issued Incidental 

Take Regulations (ITRs) to Hilcorp for a 

suite of oil and gas activities in Cook 

Inlet, Alaska (84 FR 37442; July 31, 

2019) and issued three letters of 

authorization (LOAs) under those ITRs. 

The ITRs covered activities including: 

Two-dimensional (2D) and threedimensional (3D) seismic surveys, 

geohazard surveys, vibratory sheet pile 

driving, and drilling of exploratory 

wells. On September 17, 2019, Cook 

Inletkeeper and the Center for Biological 

Diversity filed suit in the District of 

Alaska challenging NMFS’s issuance of 

the ITRs and LOAs and supporting 

documents (the EA and Endangered 

Species Act (ESA) Biological Opinion). 

In a decision issued on March 30, 2021, 

the court ruled largely in NMFS’s favor, 

but found a lack of adequate support in 

NMFS’s record for the agency’s 

determination that tug towing of drill 

rigs in connection with production 

activity will not cause take of beluga 

whales and remanded back to NMFS for 

further analysis of tug use under the 

MMPA, ESA, and NEPA. Hilcorp 

notified NMFS that all activities 

described in their initial ITR application 

(2018) and for which incidental take 

was authorized have already been 

completed or will not be completed in 

the remaining effective period of the 

ITRs. As a result, the only remaining 

activity to be analyzed is the use of tugs 

towing a jack-up rig. NMFS proposes to 

authorize incidental take from the tugs 

towing a jack-up rig through two 

sequential IHAs as the appropriate 

mechanism, given that there are no 

more activities occurring under the 

ITRs, no serious injury or mortality is 

expected, and Hilcorp’s timing needs. 

Description of Proposed Activity 

Overview 

Hilcorp Alaska, LLC (Hilcorp) plans 

to carry out activities that will occur 

over two separate one-year periods— 

from April 1, 2022 to March 31, 2023 

(Year 1) and from April 1, 2023 to 

March 31, 2024 (Year 2). Hilcorp plans 

to use three ocean-going tugs to tow a 

jack-up rig in support of plugging and 

abandonment (P&A) of an existing well 

and to support production drilling at 

other locations in middle Cook Inlet and 

Trading Bay over the course of two 

years. 

Dates and Duration 

The schedule for Hilcorp’s P&A and 

production drilling activities is 

provided in Table 1 below. The noiseproducing rig-towing activities for 

which take is proposed would occur in 

between those activities, for 

approximately 16 days per year for Year 

1 and Year 2. 


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Federal Register / Vol. 87, No. 89 / Monday, May 9, 2022 / Notices 27599 

TABLE 1—DATES AND DURATIONS OF PLANNED ACTIVITIES IN COOK INLET

Project type Cook inlet region Timing 

Duration of 

activity * 

(days) 

Year 1: 

Plug and Abandonment of Well 17589 ............. Middle Cook Inlet ..................................................... April–November ..... 30 

Production Drilling ............................................. Middle Cook Inlet Trading Bay ................................ April–November ..... 180 

Year 2: 

Production Drilling ............................................. Middle Cook Inlet Trading Bay ................................ April–November ..... 180 

* Duration is in reference to the supported activity that requires the jack-up rig to be in a specific location. It is not reflective of the duration or 

the number of days the jack-up rig is towed. 

Specific Geographic Region 

Hilcorp’s proposed activities would 

take place in Cook Inlet, Alaska. For the 

purposes of this project, lower Cook 

Inlet refers to waters south of the East 

and West Forelands; middle Cook Inlet 

refers to waters north of the East and 

West Forelands and south of Threemile 

River on the west and Point Possession 

on the east; Trading Bay refers to waters 

from approximately the Granite Point 

Tank Farm on the north to the West 

Foreland on the south; and upper Cook 

Inlet refers to waters north and east of 

Beluga River on the west and Point 

Possession on the east. A map of the 

specific area in which Hilcorp plans to 

operate is provided in Figure 1 below. 

BILLING CODE 3510–22–P 


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BILLING CODE 3510–22–C 

Detailed Description of Specific Activity 

Hilcorp proposes to use three tugs to 

pull and position a jack-up rig in 

support of well plugging and 

abandonment (P&A) and support of 

production drilling by using the rig as 

a temporary drilling platform. Hilcorp 

proposes to use the jack-up rig Spartan 

151, or similar. A jack-up rig is a type 

of mobile offshore drill unit used in 

offshore oil and gas drilling activities. It 

is comprised of a buoyant mobile 

platform or hull with moveable legs that 

are adjusted to raise and lower the hull 

over the surface of the water. The 

Spartan 151 (or similar) will be towed 

via three ocean-going tugs. The 

horsepower (hp) of each of the three 

tugs used to tow the jack-up rig may 

range between 4,000 and 8,000. Three 

tugs are needed to safely and effectively 

pull the jack-up rig into the correct 

position where it can be temporarily 

secured to the seafloor. Specifications of 

the tugs anticipated for use are provided 

in Table 2 below. If these specific tugs 

are not available, the tugs contracted 

would be of similar size and power to 

those listed in Table 2. 


khammond on DSKJM1Z7X2PROD with NOTICESEN09MY22.030</GPH>

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Met-iorage. AK 00503 

Map Date: 2'2112022 

151°_30'<:l"W 

Cook Inlet, Alaska 

Existing Hilcorp Assets 

Action Area 

Alaska Albers NAO 1983 

0 2 4 

I I I 

6Miles 

I 

Figure 1. Map of Hilcorp's Proposed Activity Location 
Federal Register / Vol. 87, No. 89 / Monday, May 9, 2022 / Notices 27601 

TABLE 2—DESCRIPTION OF TUGS

TOWING THE JACK-UP RIG

Vessel name Specifications 

M/V Bering 

Wind.

22-m length × 10-m breadth, 

144 gross tonnage 

M/V Anna T ... 32-m length × 11-m breadth, 

160 gross tonnage 

M/V Bob Franco.37-m length × 11-m breadth, 

196 gross tonnage 

The amount of time the tugs are under 

load transiting, holding, and positioning 

the jack-up rig in Cook Inlet is tidedependent. The power output of the 

tugs depends on whether the tugs are 

towing with or against the tide and can 

vary across a tide cycle as the current 

increases or decreases in speed over 

time. Hilcorp proposes to make every 

effort to transit with the tide (which 

requires lower power output) and 

minimize transit against the tide (which 

requires higher power output). 

The jack-up rig will be mobilized and 

demobilized via towing by three oceangoing tugs from and to the Rig Tenders 

Dock in Nikiski, Alaska. A high slack 

tide is necessary for the tugs to 

approach close enough to shore to 

attach and mobilize the jack-up rig from 

the Rig Tenders Dock. Because Hilcorp’s 

production platforms/well sites are 

north of the initial mobilization site, the 

tugs will begin their transit from Nikiski 

against an outgoing tide. To minimize 

transit time against the outgoing tide 

and reduce power output, the tugs will 

first tow the jack-up rig to a location 

near the Offshore Systems Kenai dock 

for approximately three hours, which 

provides protection from the fast 

outgoing tidal current. Protection from 

the outgoing tidal current will allow the 

tugs to expend less power holding the 

jack-up rig in position than they would 

if they continued to transit against the 

tide. The tugs will begin transiting north 

again when the tide changes to an 

incoming tide, which is about six hours 

after the high slack tide. Towing the 

jack-up rig northward with an incoming 

tide requires less than half power, 

generally only 20 to 30 percent of total 

power output (Durham 2021, pers. 

comm.). 

A high slack tide is preferred to 

position the jack-up rig on an existing 

platform or well site. The relatively 

slow current and calm conditions at a 

slack tide enables the tugs to perform 

the fine movements necessary to safely 

position the jack-up rig within several 

feet of the platform. Positioning and 

securing the jack-up rig is generally 

performed at high slack tide rather than 

low slack tide to pin the legs down at 

an adequate height to ensure the hull of 

the jack-up rig remains above the water 

level of the subsequent incoming high 

tide. Because 12 hours elapse between 

each high slack tide, tugs are generally 

under load for those 12 hours, even if 

the towed distance is small, as high 

slack tides are preferred to both attach 

and detach the jack-up rig from the tugs. 

Once the tugs are on location with the 

jack-up rig at high slack tide (12 hours 

from the previous departure), there is a 

1 to 2-hour window when the tide is 

slow enough for the tugs to initiate 

positioning the jack-up rig and pin the 

legs to the seafloor on location. The tugs 

are estimated to be under load, generally 

at half-power conditions or less, for up 

to 14 hours from the time of departure 

through the initial positioning attempt 

of the jack-up rig. If the first positioning 

attempt takes longer than anticipated, 

the increasing current speed prevents 

the tugs from safely positioning the jackup rig on location. If the first 

positioning attempt is not successful, 

the jack-up rig will be pinned down at 

a nearby location and the tugs will be 

released from the jack-up rig and no 

longer under load. The tugs will remain 

nearby, generally floating with the 

current. Approximately an hour before 

the next high slack tide, the tugs will reattach to the jack-up rig and reattempt 

positioning over a period of 2 to 3 

hours. Positioning activities are 

generally at half power. If a third 

attempt is needed, the tugs would be 

under load holding or positioning the 

jack-up rig on a second day for up to 5 

hours. The vast majority of the time, the 

jack-up rig can be successfully 

positioned over the platform in one or 

two attempts. 

A location-to-location transport (e.g., 

platform-to-platform) of a jack-up rig is 

conducted similarly to the mobilization 

from the Rig Tenders Dock described 

above with one main difference. In a 

location-to-location transport in middle 

Cook Inlet or Trading Bay, there is no 

harbor available for temporary staging to 

avoid transiting against the tide. 

Maintaining position of the jack-up rig 

against the tidal current can require 

more than half power (up to 90 percent 

power at the peak tidal outflow). 

However, greater than half power effort 

is only needed for short periods of time 

during the maximum tidal current, 

expected to be no more than three hours 

maximum. During a location-to-location 

transport, the tugs will transport the 

jack-up rig traveling with the tide in 

nearly all circumstances except in 

situations that threaten the safety of 

humans and/or infrastructure integrity. 

There may be a situation wherein the 

tugs pulling the jack-up rig begin 

transiting with the tide to their next 

location, miss the tide window to safely 

set the jack-up rig on the platform or pin 

it nearby, and so have to transport the 

jack-up rig against the tide to a safe 

harbor. Tugs may also need to transport 

the jack-up rig against the tide if large 

pieces of ice or extreme wind events 

threaten the stability of the jack-up rig 

on the platform. 

Although the variability in power 

output from the tugs can range from an 

estimated 20 percent to 90 percent 

throughout the hours under load with 

the jack-up rig, as described above, the 

majority of the hours (spent transiting, 

holding, and positioning) occur at half 

power or less. See the Estimated Take 

section below for more detail on 

assumptions related to power output. 

Year 1—For the first year of activity, 

Hilcorp proposes use of three tugs to 

pull the jack-up rig for plugging and 

abandonment (P&A) of Well 17589, 

which began in 2021 but was not 

completed due to equipment sourcing 

issues. Prior to pinning the jack-up rig 

legs to the seafloor, a multi-beam sonar 

may be used to ensure the seafloor is 

clear of debris that may impact the 

ability to pin down the legs of the 

platform. The multibeam echosounder 

emits high frequency (240 kilohertz 

[kHz]) energy in a fan-shaped pattern of 

equidistant or equiangular beam 

spacing. The multi-beam sonar operates 

at a frequency outside of marine 

mammal hearing range and is not 

addressed further in our analysis. After 

the rig is secure, divers enter the water 

and use hand tools to complete the P&A 

process. In addition to the hand tools, 

the divers will also use water jets to 

wash away debris and marine growth on 

the structure (e.g., a CaviDyne 

CaviBlaster). Based on measurements 

conducted by Hilcorp during 2017 use 

of water jets, the source level for the 

CaviBlaster® was estimated as 176 

decibels (dB) re 1 micropascal (mPa) root 

mean square (rms) with a Level B 

harassment threshold of 860 m, with 

most energy concentrated above 500 Hz 

with a dominant tone near 2 kHz. 

Hilcorp plans to put a protected species 

observer (PSO) on watch to monitor the 

full extent of the harassment zone and 

shutdown when an animal approaches 

the zone during water jet use. Because 

of this, Hilcorp is not requesting take 

associated with water jet use and it is 

not considered further in our analysis. 

Hilcorp also plans to tug the jack-up 

rig to existing platforms in middle Cook 

Inlet and Trading Bay in support of 

production drilling activities from 

existing platforms and wellbores. 

Production drilling itself creates some 

small level of noise due to the use of 


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generators and other potentially noisegenerating equipment. Furie Operating 

Alaska, LLC, performed detailed 

underwater acoustic measurements in 

the vicinity of the Spartan 151 in 2011 

(Marine Acoustics Inc. 2011) northeast 

of Nikiski Bay in water depths of 24.4 

to 27.4 m (80 to 90 ft). Primary sources 

of rig-based acoustic energy were 

identified as coming from the D399/ 

D398 diesel engines, the PZ–10 mud 

pump, ventilation fans, and electrical 

generators. The source level of one of 

the loudest acoustic sources, the diesel 

engines, was estimated to be 137 dB re 

1 mPa rms at 1 m in the 141 to 178 Hz 

frequency range. Based on this 

measured level, the 120 dB rms acoustic 

received level isopleth would be 

approximately 50 m away from where 

the energy enters the water (jack-up leg 

or drill riser). This small radius would 

overlap substantially with the physical 

footprint of the platform and other 

equipment, so Hilcorp is not requesting 

take for this activity and it is not 

considered further in our analysis. In 

support of these activities, helicopters 

and support vessels transit from the 

mainland to the production sites to 

mobilize personnel and supplies. 

Helicopters will fly at 1,500 ft or higher 

unless human safety is at risk or it is 

operationally impossible (e.g., takeoff 

and landing points are so close together 

the aircraft cannot reach 1,500 ft). 

Vessel trips to and from the location of 

the jack-up rig are expected to increase 

by two trips per day above normal 

activity levels. 

Year 2—For the second year of 

activity, Hilcorp does not plan to 

conduct P&A activities with the jack-up 

rig and will only be tugging the jack-up 

rig in support of production drilling 

activities. 

The specific configuration of tugs 

towing the jack-up-rig as proposed by 

Hilcorp has not been analyzed 

previously. Hilcorp contracted JASCO 

Applied Sciences to conduct a sound 

source verification (SSV) of their tugs in 

operation in Cook Inlet during October 

2021. This SSC measured tugs pulling 

the jack-up-rig at various power outputs. 

This SSV returned a source level of a 

source level of 167.3 dB re 1 mPa for the 

20 percent power scenario and a source 

level of 205.9 dB re 1 mPa for the 85 

percent power scenario. Assuming a 

linear scaling of tug power, a source 

level of 185 dB re 1 mPa was then 

calculated as a single point source level 

for three tugs operating at 50% power 

output. This is approximately five dB 

higher than the literature summary 

described below. 

Hilcorp conducted a literature review 

of available source level data for tugs 

under load in varying power output 

scenarios. Table 3 below provides 

values of measured source levels for 

tugs varying from 2,000 to 8,2000 

horsepower. For the purposes of this 

table, berthing activities could include 

tugs either pushing or pulling a load. 

The sound source levels appear 

correlated to speed and power output, 

with full power output and higher 

speeds generating more propeller 

cavitation and greater sound source 

levels than lower power output and 

lower speeds. Additional tug source 

levels are available from the literature 

but they are not specific to tugs under 

load but rather measured values for tugs 

during activities such as transiting, 

docking, and anchor pulling. For a 

summary of these additional tug values, 

see Table 7 in Hilcorp’s application. 

TABLE 3—LITERATURE VALUES OF MEASURED TUG SOURCE LEVELS

Vessel Vessel length 

(m) 

Speed 

(knots) Activity 

Source level 

@1 m 

(re: 1 μPa) 

Horsepower Reference 

Eagle ............................. 32 9.6 Towing barge ................ 173 6,770 Bassett et al. 2012. 

Valor .............................. 30 8.4 Towing barge ................ 168 2,400 

Lela Joy ........................ 24 4.9 Towing barge ................ 172 2,000 

Pacific Eagle ................. 28 8.2 Towing barge ................ 165 2,000 

Shannon ........................ 30 9.3 Towing barge ................ 171 2,000 

James T Quigg ............. 30 7.9 Towing barge ................ 167 2,000 

Island Scout .................. 30 5.8 Towing barge ................ 174 4,800 

Chief .............................. 34 11.4 Towing barge ................ 174 8,200 

Lauren Foss .................. 45 N/A Berthing barge .............. 167 8,200 Austin et al. 2013. 

Seaspan Resolution ...... 30 N/A Berthing at half power .. 180 6,000 Roberts Bank Terminal 2 Technical 

Report 2014. 

Seaspan Resolution ...... 30 N/A Berthing at full power ... 200 6,000 

The Roberts Bank Terminal 2 

Technical Report (2014), although not in 

Cook Inlet, includes repeated 

measurements of the same tug operating 

under different speeds and loads. This 

allows for a comparison of source levels 

from the same vessel at half power 

versus full power, which is an 

important distinction for Hilcorp’s 

activities, as a small fraction of the total 

time spent by tugs under load will be at 

greater than 50 percent power. The 

Seaspan Resolution’s half-power 

berthing scenario has a sound source 

level of 180 dB re 1 mPa at 1 m. In 

addition, the Roberts Bank Report 

(2014) analyzed 650 tug transits under 

varying load and speed conditions and 

reported mean tug source levels of 179.3 

dB re 1 mPa at 1 m, the 25th percentile 

was 179.0 dB re 1 mPa at 1 m, and 5th 

percentile source levels were 184.9 dB 

re 1 mPa at 1 m. 

Based solely on the literature review, 

a source level of 180 dB for a tug under 

load would be appropriate. However, 

Hilcorp’s use of a three tug 

configuration would increase the 

literature source level to approximately 

185dB. As one or two tugs are primarily 

under load, the third tug sits off to the 

side. NMFS still considers these tugs to 

be simultaneous sources. When 

considered in conjunction with the 

additional tugs present in the 

configuration as well as the SSV 

conducted by JASCO for Hilcorp’s 

specific configuration, a source level of 

185 dB for tugs towing a jack-up rig was 

carried forward for analysis. 

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. Additional information 


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regarding population trends and threats 

may be found in NMFS’s Stock 

Assessment Reports (SARs; https://

www.fisheries.noaa.gov/national/ 

marine-mammal-protection/marinemammal-stock-assessments) and more 

general information about these species 

(e.g., physical and behavioral 

descriptions) may be found on NMFS’s 

website (https://www.fisheries.

noaa.gov/find-species). 

Table 4 lists all species or stocks for 

which take is expected and proposed to 

be authorized for this action, 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. For taxonomy, we follow 

the Committee on Taxonomy (2021). 

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’s 

SARs). While no mortality is anticipated 

or authorized here, PBR and annual 

serious injury and mortality from 

anthropogenic sources are included here 

as gross indicators of the status of the 

species 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’s 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’s U.S. 2020 SARs (e.g., Muto et 

al. 2021). All values presented in Table 

4 are the most recent available at the 

time of publication and are available in 

the 2020 SARs (Muto et al. 2021) and 

draft 2021 SARs (available online at: 

https://www.fisheries.noaa.gov/ 

national/marine-mammal-protection/ 

draft-marine-mammal-stockassessment-reports). 

TABLE 4—MARINE MAMMAL SPECIES OR STOCKS FOR WHICH TAKE IS EXPECTED AND PROPOSED TO BE AUTHORIZED

Common name Scientific name Stock 

ESA/ 

MMPA 

status; 

strategic 

(Y/N) 1

Stock abundance 

(CV, Nmin, most recent 

abundance survey) 2

PBR Annual 

M/SI 3

Order Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales) 

Family Eschrichtiidae: 

Gray whale ......................... Eschrichtius robustus ............... Eastern Pacific ......................... -, -, N 26,960 (0.05, 25,849, 

2016).

801 131 

Family Balaenidae: 

Humpback whale ................ Megaptera novaeangliae ......... Western North Pacific .............. E, D, Y 1,107 (0.3, 865, 2006) ... 3 2.8 

Minke whale ....................... Balaenoptera acutorostrata ..... Alaska ...................................... -, -, N N/A (see SAR, N/A, see 

SAR).

UND 0 

Family Balaenopteridae 

(rorquals): 

Fin whale ............................ Balaenoptera physalus ............ Northeastern Pacific ................ E, D, Y see SAR (see SAR, see 

SAR, 2013).

see SAR 0.6 

Superfamily Odontoceti (toothed whales, dolphins, and porpoises) 

Family Delphinidae: 

Beluga whale ...................... Delphinapterus leucas ............. Cook Inlet ................................. E, D, Y 279 (0.061, 267, 2018) .. see SAR 0 

Killer whale ......................... Orcinus orca ............................ Alaska Resident ....................... -, -, N 2,347 c (N/A, 2347, 

2012).

24 1 

Killer whale ......................... Orcinus orca ............................ Gulf of Alaska, Aleutian Islands, and Bering Sea Transient.-, -, N 587 c (N/A, 587, 2012) .. 5.87 0.8 

Family Phocoenidae (porpoises): 

Harbor porpoise .................. Phocoena phocoena ................ Gulf of Alaska .......................... -, -, Y 31,046 (0.21, N/A, 1998) UND 72 

Dall’s porpoise .................... Phocoenoides dalli ................... Alaska ...................................... -, -, N see SAR (0.097, see 

SAR, 2015).

see SAR 37 

Order Carnivora—Superfamily Pinnipedia 

Family Otariidae (eared seals 

and sea lions): 

Steller sea lion .................... Eumetopias jubatus ................. Western .................................... E, D, Y 52,932 a (see SAR, 

52,932, 2019).

318 254 

California sea lion ............... Zalophus californianus ............. U.S ........................................... -, -, N 257,606 (N/A,233,515, 

2014).

14011 >320 

Family Phocidae (earless seals): 

Harbor seal ......................... Phoca vitulina .......................... Cook Inlet/Shelikof ................... -, -, N 28,411 (see SAR, 

26,907, 2018).

807 107 

1Endangered 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. 2 NMFS marine mammal stock assessment reports online at: www.nmfs.noaa.gov/pr/sars/. CV is coefficient of variation; Nmin is the minimum estimate of stock 

abundance. In some cases, CV is not applicable depending on the methodology described in the stock assessment report (SAR) and the date of last available survey 

data. Where necessary, NMFS refers reader to the SAR for more detail. 3These values, found in NMFS’s SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial fisheries, ship strike). Annual mortality and serious injury often cannot be determined precisely and is in some cases presented as a minimum value or range. 


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As indicated above, all 11 species 

(with 12 managed stocks) in Table 4 

temporally and spatially co-occur with 

the activity to the degree that take could 

reasonably occur, and we have proposed 

authorizing it. In addition, the northern 

sea otter may be found in Cook Inlet, 

Alaska. However, sea otters are managed 

by the U.S. Fish and Wildlife Service 

and are not considered further in this 

document. 

Gray Whale 

The eastern North Pacific stock of 

gray whales occurring in Cook Inlet are 

likely migrating to summer feeding 

grounds in the Bering, Chukchi, and 

Beaufort seas, although some whales are 

known to feed near Kodiak Island 

(Carretta et al. 2014). Gray whales 

generally breed every two years during 

November and December while 

undertaking the southern migration 

(Jones and Swartz 2009). Gray whales 

have been reported feeding near Kodiak 

Island, in southeastern Alaska, and 

south along the Pacific Northwest (Allen 

and Angliss 2013). Most gray whales 

migrating through the Gulf of Alaska 

region are thought to take a coastal route 

and (Ferguson et al. 2015) delineated 

the migratory corridor biologically 

important area (BIA) boundaries based 

on the extent of the continental shelf. 

Most gray whales calve and breed 

from late December to early February in 

protected waters along the western coast 

of Baja California, Mexico. In spring, the 

Eastern North Pacific stock of gray 

whales migrates ∼8,000 km (5,000 mi) to 

feeding grounds in the Bering and 

Chukchi seas before returning to their 

wintering areas in the fall (Rice and 

Wolman 1971). Northward migration, 

primarily of individuals without calves, 

begins in February; some cow/calf pairs 

delay their departure from the calving 

area until well into April (Jones and 

Swartz 1984). Gray whales approach the 

lower Cook Inlet in late March, April, 

May, and June, and leave again in 

November and December (Consiglieri et 

al. 1982; Rice and Wolman 1971) but 

migrate past the mouth of Cook Inlet to 

and from northern feeding grounds. 

Some gray whales do not migrate 

completely from Baja to the Chukchi 

Sea but instead feed in select coastal 

areas in the Pacific Northwest, 

including lower Cook Inlet (Moore et al. 

2007). 

Most of the population follows the 

outer coast of the Kodiak Archipelago 

from the Kenai Peninsula in spring or 

the Alaska Peninsula in fall (Consiglieri 

et al. 1982; Rice and Wolman 1971). 

Though most gray whales migrate past 

Cook Inlet, small numbers have been 

noted by fishers near Kachemak Bay, 

and north of Anchor Point (BOEM 

2015). During the NMFS aerial surveys, 

gray whales were observed in the month 

of June in 1994, 2000, 2001, 2005 and 

2009 on the east side of Cook Inlet near 

Port Graham and Elizabeth Island but 

also on the west side near Kamishak Bay 

(Shelden et al. 2013). One gray whale 

was sighted as far north at the Beluga 

River. Additionally, summering gray 

whales were seen offshore of Cape 

Starichkof by marine mammal observers 

monitoring Buccaneer’s Cosmopolitan 

drilling program in 2013 (Owl Ridge 

2014). During Apache’s 2012 seismic 

program, nine gray whales were 

observed in June and July (LomacMacNair et al. 2013). During Apache’s 

seismic program in 2014, one gray 

whale was observed (Lomac-MacNair et 

al. 2014). During SAExploration’s 

seismic survey in 2015, no gray whales 

were observed (Kendall et al. 2015). No 

gray whales were observed during the 

2019 Hilcorp seismic survey in lower 

Cook Inlet (Fairweather Science 2020) 

or during the 2018 Cook Inlet Pipeline 

(CIPL) project (Sitkiewicz et al. 2018). 

Humpback Whale 

Humpback whales are found 

throughout southern Alaska in a variety 

of marine environments, including 

open-ocean, near-shore waters, and 

areas with strong tidal currents 

(Dahlheim et al. 2009). Most humpback 

whales are migratory and spend winters 

in the breeding grounds off either 

Hawaii or Mexico. Humpback whales 

are regularly present and feeding in 

Cook Inlet in the summer. Current 

threats to humpback whales include 

vessel strikes, spills, climate change, 

and commercial fishing operations 

(Muto et al. 2021). 

Humpback whales worldwide were 

designated as ‘‘endangered’’ under the 

Endangered Species Conservation Act in 

1970, and were listed under the ESA at 

its inception in 1973. However, on 

September 8, 2016, NMFS published a 

final decision that changed the status of 

humpback whales under the ESA (81 FR 

62259), effective October 11, 2016. The 

decision recognized the existence of 14 

distinct population segments (DPSs) 

based on distinct breeding areas in 

tropical and temperate waters. Five of 

the 14 DPSs were classified under the 

ESA (4 endangered and 1 threatened), 

while the other 9 DPSs were delisted. 

Humpback whales found in the project 

area are predominantly members of the 

Hawaii DPS, which is not listed under 

the ESA. However, based on analyses of 

photo-identification studies in Alaska, 

members of the Mexico DPS and the 

Western North Pacific DPS, which are 

listed as threatened and endangered 

respectively, are thought to occur in 

Cook Inlet. Approximately one percent 

of all humpback whales in Cook Inlet 

are thought to belong to the endangered 

Western North Pacific DPS and 11 

percent are thought to belong to the 

threatened Mexico DPS. All other 

humpback whales present are thought to 

belong to the non-listed Hawaii DPS 

(Wade et al. 2021). Members of different 

DPSs are known to intermix on feeding 

grounds; therefore, all waters off the 

coast of Alaska should be considered to 

have ESA-listed humpback whales. 

Critical habitat was recently designated 

near the entrance of lower Cook Inlet for 

Western North Pacific DPS and Mexico 

DPS humpback whales (86 FR 21082; 

April 21, 2021); however, Hilcorp’s 

action area does not spatially overlap 

with any critical habitat designated for 

humpback whale DPS. 

The DPSs of humpback whales that 

were identified through the ESA listing 

process do not necessarily equate to the 

existing MMPA stocks. The stock 

delineations of humpback whales under 

the MMPA are currently under review. 

Until this review is complete, NMFS 

considers humpback whales in Cook 

Inlet to be part of the Central North 

Pacific stock, with a status of 

endangered under the ESA and 

designations of strategic and depleted 

under the MMPA (Muto et al. 2021). 

In the summer, humpback whales are 

regularly present and feeding in the 

Cook Inlet region, including Shelikof 

Strait, Kodiak Island bays, and the 

Barren Islands, in addition to Gulf of 

Alaska regions adjacent to the southeast 

side of Kodiak Island (especially 

Albatross Banks), the Kenai and Alaska 

peninsulas, Elizabeth Island, as well as 

south of the Aleutian Islands. 

Humpbacks also may be present in some 

of these areas throughout autumn (Muto 

et al. 2017). 

Humpback whales have been 

observed during marine mammal 

surveys conducted in Cook Inlet; 

however, their presence is largely 

confined to lower Cook Inlet. During 

SAExploration’s 2015 seismic program, 

three humpback whales were observed 

in Cook Inlet; two near the Forelands 

and one in Kachemak Bay (Kendall et al. 

2015). During NMFS Cook Inlet beluga 

whale aerial surveys from 2000 to 2018, 

there were 88 sightings of 191 estimated 

individual humpback whales in lower 

Cook Inlet (Shelden et al. 2017). They 

have been regularly seen near Kachemak 

Bay during the summer months (Rugh et 

al. 2005). There are observations of 

humpback whales as far north as 

Anchor Point, with recent summer 

observations extending to Cape 

Starichkof (Owl Ridge 2014). Several 


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humpback whale sightings occurred 

lower Cook Inlet between Iniskin 

Peninsula and Kachemak Bay near 

Augustine, Barren, and Elizabeth 

Islands (Shelden et al. 2013, 2015, 

2017). There were two sightings of three 

humpback whales observed near Ladd 

Landing north of the Forelands on the 

recent Harvest Alaska Cook Inlet 

Pipeline Extension (CIPL) project 

(Sitkiewicz et al. 2018). There were 14 

sightings of 38 humpback whales 

observed in the 2019 Hilcorp lower 

Cook Inlet seismic survey in the fall 

(Fairweather Science 2020). This higher 

number of humpback whales was 

expected in the lower Cook Inlet region 

than Hilcorp’s proposed work in the late 

summer/fall period. 

Ferguson et al. (2015) identified a 

biologically important area (BIA), in 

which humpback whales are known to 

concentrate for feeding, in the Gulf of 

Alaska region. The BIA encompasses the 

waters east of Kodiak Island (the 

Albatross and Portlock Banks), a target 

for historical commercial whalers based 

out of Port Hobron, Alaska (Ferguson et 

al. 2015; Reeves et al. 1985; Witteveen 

et al. 2007). This BIA also includes 

waters along the southeastern side of 

Shelikof Strait and in the bays along the 

northwestern shore of Kodiak Island. 

The highest densities of humpback 

whales around the Kodiak Island BIA 

occur from July–August (Ferguson et al. 

2015). This BIA lies directly south but 

does not spatially overlap with 

Hilcorp’s proposed action area. 

Minke Whale 

Minke whales are a non-ESA listed 

cetacean not commonly found in the 

Cook Inlet region. Minke whales are not 

designated as depleted under the 

MMPA or listed as threatened or 

endangered under the ESA. Presumably, 

minke whales breed in warm, low 

latitude waters during winter, give birth 

every other year to one calf, and reach 

sexual maturity at 7 to 9 m (23 to 30 ft) 

in length (Perrin and Brownell 2009). 

Potential threats to and vulnerabilities 

of minke whales include anthropogenic 

sound emissions underwater, impacts 

on prey distribution, climate change, 

fishing operations, vessel strikes, and oil 

and gas operations (Muto et al. 2018). 

Minke whales are most abundant in 

the Gulf of Alaska during summer and 

occupy localized feeding areas (Zerbini 

et al. 2006). Concentrations of minke 

whales have occurred along the north 

coast of Kodiak Island and along the 

south coast of the Alaska Peninsula 

(Zerbini et al. 2006). The most recent 

estimate for minke whales specifically 

between Kenai Fjords and the Aleutian 

Islands is 1,233 individuals (Zerbini et 

al. 2006). No population estimate for 

minke whales in the entirety of the 

north Pacific exists (Muto et al, 2019). 

During shipboard surveys conducted in 

2003, three minke whale sightings were 

made, all near the eastern extent of the 

survey from nearshore Prince William 

Sound to the shelf break (MML, 2003). 

Minke whales become scarce in the Gulf 

of Alaska in fall; most whales are 

thought to leave the region by October 

(Consiglieri et al. 1982). Minke whales 

are migratory in Alaska, but recently 

have been observed off Cape Starichkof 

and Anchor Point year-round (Muto et 

al. 2017). 

During Cook Inlet-wide aerial surveys 

conducted from 1993 to 2004, minke 

whales were encountered three times 

(1998, 1999, and 2006), both times off 

Anchor Point 26 km (16 miles [mi]) 

northwest of Homer (Shelden et al. 

2013, 2015, 2017; Shelden and Wade 

2019). A minke whale was also reported 

off Cape Starichkof in 2011 and 2013, 

suggesting this location is regularly used 

by minke whales, including during the 

winter. Several minke whales were 

recorded off Cape Starichkof in early 

summer 2013 during exploratory 

drilling (Owl Ridge 2014), suggesting 

this location may be used by minke 

whales year-round. During Apache’s 

2014 survey, a total of two minke whale 

groups (totaling three individuals) were 

observed during this time period, one 

sighting to the southeast of Kalgin 

Island and another sighting near Homer 

(Lomac-MacNair et al. 2014). 

SAExploration noted one minke whale 

near Tuxedni Bay in 2015 (Kendall et al. 

2015). There were eight sightings of 

eight minke whales observed in the 

2019 Hilcorp lower Cook Inlet seismic 

survey in the fall (Fairweather Science 

2020). This higher number of minke 

whales suggests these offshore waters of 

lower Cook Inlet may be utilized by 

minke whales in greater numbers than 

previously estimated, particularly 

during the fall period. No minke whales 

were observed during the 2018 CIPL 

project (Sitkiewicz et al. 2018). 

Fin Whale 

Fin whales are listed as endangered 

under the ESA in 1990 and depleted 

under the MMPA. For management 

purposes, three stocks of fin whales are 

currently recognized in United States 

(U.S.) Pacific waters: Alaska (Northeast 

Pacific), California/Washington/Oregon, 

and Hawaii. Recent analyses provide 

evidence that the population structure 

should be reviewed and possibly 

updated, however substantially new 

data on the stock structure is lacking 

(Muto et al. 2019).The Northeast Pacific 

stock is categorized as a strategic stock. 

No critical habitat has been designated 

or proposed for fin whales in the North 

Pacific. 

Fin whales are usually observed as 

individuals traveling alone, although 

they are sometimes observed in small 

groups. Rarely, large groups of 50 to 300 

fin whales can travel together during 

migrations (NMFS 2010a). Fin whales in 

the Cook Inlet have only been observed 

as individuals or in small groups. Fin 

whales are vulnerable to natural and 

anthropogenic variables. Impacts on 

prey quality and distribution could 

affect distribution and energetics. The 

natural range of fin whales could be 

expanded due to sea ice melting and 

expanded available habitat. This could 

also result in increased exposure to 

shipping and other commercial 

activities. Toxicity and resulting deaths, 

as seen in recent years, from harmful 

algal blooms producing biotoxins could 

result from warming waters (Muto et al. 

2021). 

In the U.S. Pacific waters, fin whales 

are found seasonally in the Gulf of 

Alaska, Bering Sea, and as far north as 

the northern Chukchi Sea (Muto et al. 

2019). Surveys conducted in coastal 

waters of the Aleutians and the Alaska 

Peninsula found fin whales occurred 

primarily from the Kenai Peninsula to 

the Shumagin Islands and were 

abundant near the Semidi Islands and 

Kodiak Island (Zerbini et al. 2006). An 

opportunistic survey conducted on the 

shelf of the Gulf of Alaska found fin 

whales concentrated west of Kodiak 

Island in Shelikof Strait, and in the 

southern Cook Inlet region. In the 

northeastern Chukchi Sea, visual 

sightings and acoustic detections have 

been increasing, which suggests the 

stock may be re-occupying habitat used 

prior to large-scale commercial whaling 

(Muto et al. 2019). Most of these areas 

are feeding habitat for fin whales. 

Watkins et al. (2000), and Stafford et al. 

(2007) documented high rates of calling 

along the Alaska coast beginning in 

August/September and lasting through 

February. Fin whales are regularly 

observed in the Gulf of Alaska during 

the summer months, even though calls 

are seldom detected during this period 

(Stafford et al. 2007). Instruments 

moored in the southeast Bering Sea 

detected calls over the course of a year 

and found peaks from September to 

November as well as in February and 

March (Stafford et al. 2010). Delarue et 

al. (2013) detected calls in the 

northeastern Chukchi Sea from 

instruments moored from July through 

October from 2007 through 2010. 

Fin whales are rarely observed in 

Cook Inlet and most sightings occur 

near the entrance of the inlet. During the 


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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, 2017; 

Shelden and Wade 2019). There were 

eight sightings of 23 fin whales observed 

in the 2019 Hilcorp lower Cook Inlet 

seismic survey in the fall (Fairweather 

Science 2020). This higher number of 

fin whale sightings suggests these 

offshore waters of lower Cook Inlet may 

be utilized by fin whales in greater 

numbers than previously estimated, 

particularly during the fall period. 

Beluga Whale 

The Cook Inlet beluga whale stock is 

a small geographically isolated 

population that is separated from other 

beluga populations by the Alaska 

Peninsula. The population is genetically 

distinct from other Alaska populations 

suggesting the Peninsula is an effective 

barrier to genetic exchange (O’CorryCrowe et al. 1997). The Cook Inlet 

beluga whale population is estimated to 

have declined from 1,300 animals in the 

1970s (Calkins 1989) to about 340 

animals in 2014 (Shelden et al. 2015). 

The current population estimate is 279 

animals (Shelden and Wade 2019). In 

1999, beluga hunters agreed to a 

moratorium on hunting to protect the 

species, from 2000 through 2005 one 

strike per year was allowed and taken in 

all but 2004, and since 2006 no Cook 

Inlet belugas have been harvested by 

subsistence users (Muto et al. 2021). 

NMFS designated the population as 

depleted under the MMPA in 2000 and 

listed it as endangered under the ESA in 

2008 when the population failed to 

recover following a moratorium on 

subsistence harvest (65 FR 34590; May 

31, 2000). In April 2011, NMFS 

designated critical habitat for the beluga 

under the ESA (76 FR 20180; April 11, 

2011). NMFS finalized the Conservation 

Plan for the Cook Inlet beluga in 2008 

(NMFS 2008a) and the Recovery Plan 

for Cook Inlet beluga whales in 2016 

(NMFS 2016a). During the most recent 

10-year time period (2008 to 2018), the 

population of Cook Inlet belugas 

experienced a decline of about 2.3 

percent per year (Wade et al. 2019). 

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, Lowry et al., 2006, Hobbs et al., 

2015, NMFS, 2106). Planned projects 

that may alter the physical habitat of 

Cook Inlet include highway 

improvements; mine construction and 

operation; oil and gas exploration and 

development; and expansion and 

improvements to ports. 

Generally, female beluga whales reach 

sexual maturity at 9 to 12 years old, 

while males reach maturity later 

(O’Corry-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-Joregensen 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 two to three 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). 

Several studies (Johnson et al. 1989; 

Klishin et al. 2000; Finneran et al. 2002; 

Erbe 2008; white et al. 1978; Awbrey et 

al. 1988; Ridgway et al. 2001; Finneran 

et al. 2005; Castellote et al. 2019) 

describe beluga whale hearing 

capabilities. One study on beluga 

whales captured and released in Bristol 

Bay, Alaska measured hearing ranges at 

4 to 150 kHz with greatest variation 

between individuals at the high end of 

the auditory range in combination with 

frequencies near the maximum 

sensitivity (Castellote et al. 2014). All 

animals tested heard well up to 128 

kHz, with two individuals hearing up to 

150 kHz (Castellote et al. 2014). Beluga 

whales are included in the NMFSidentified mid-frequency functional 

hearing group. 

The Cook Inlet beluga stock remains 

within Cook Inlet throughout the year 

(Goetz et al. 2012a). Two areas, 

consisting of 7,809 square kilometers 

(km2) of marine and estuarine 

environments considered essential for 

the species’ survival and recovery, were 

designated critical habitat. However, in 

recent years the range of the beluga 

whale has contracted to the upper 

reaches of Cook Inlet (Rugh et al. 2010). 

Area 1 of the Cook Inlet beluga whale 

critical habitat encompasses all marine 

waters of Cook Inlet north of a line 

connecting Point Possession (61.04° N, 

150.37° W) and the mouth of Threemile 

Creek (61.08.55° N, 151.04.40° W), 

including waters of the Susitna, Little 

Susitna, and Chickaloon Rivers below 

the mean higher high water line 

(MHHW). This area provides important 

habitat during ice-free months and is 

used intensively by Cook Inlet beluga 

between April and November for 

feeding and other biological functions 

(NMFS 2016a). 

Since 1993, NMFS has conducted 

annual aerial surveys in June, July, or 

August to document the distribution 

and abundance of beluga whales in 

Cook Inlet. The collective survey results 

show that beluga whales have been 

consistently found near or in river 

mouths along the northern shores of 

middle and upper Cook Inlet. In 

particular, beluga whale groups are seen 

in the Susitna River Delta, Knik Arm, 

and along the shores of Chickaloon Bay. 

Small groups had also been recorded 

farther south in Kachemak Bay, Redoubt 

Bay (Big River), and Trading Bay 

(McArthur River) prior to 1996, but very 

rarely thereafter. Since the mid-1990s, 

most beluga whales have been 

concentrated in shallow areas near river 

mouths north and east of Beluga River 

and Point Possession (Hobbs et al. 

2008). Based on these aerial surveys, 

there is a consistent pattern of beluga 

whale presence in the northernmost 

portion of Cook Inlet from June to 

October (Rugh et al. 2000, 2004a, 2004b, 

2005, 2006, 2007). 

Though Cook Inlet beluga whales can 

be found throughout the inlet at any 

time of year, generally they spend the 

ice-free months in the upper Cook Inlet, 

shifting into deeper waters in middle 

Cook Inlet in winter (Hobbs et al. 2008). 

In 1999, one beluga whale was tagged 

with a satellite transmitter, and its 

movements were recorded from June 

through September of that year. Since 

1999, 18 beluga whales in upper Cook 

Inlet have been captured and fitted with 

satellite tags to provide information on 

their movements during late summer, 

fall, winter, and spring. Using location 

data from satellite-tagged Cook Inlet 

belugas, Ezer et al. (2013) found most 

tagged whales were in the lower to 

middle inlet during January through 

March, near the Susitna River Delta 

from April to July) and in the Knik and 

Turnagain Arms from August to 

December. 

During the spring and summer, beluga 

whales are generally concentrated near 

the warmer waters of river mouths 

where prey availability is high and 

predator occurrence is low (Moore et al. 

2000). Beluga whales in Cook Inlet are 


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believed to mostly calve between midMay and mid-July, and concurrently 

breed between late spring and early 

summer (NMFS 2016a), primarily in 

upper Cook Inlet. Beluga movement was 

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 initial results from passive 

acoustic monitoring across the entire 

inlet (Castellote et al. 2016) also support 

seasonal patterns observed with other 

methods, and other surveys confirm 

Cook Inlet belugas near the Kenai River 

during summer months (McGuire and 

Stephens 2017). 

During the summer and fall, beluga 

whales are concentrated near the 

Susitna River mouth, Knik Arm, 

Turnagain Arm, and Chickaloon Bay 

(Nemeth et al. 2007) where they feed on 

migrating eulachon (Thaleichthys 

pacificus) and salmon (Onchorhyncus 

spp.) (Moore et al. 2000). Data from 

tagged whales (14 tags between July and 

March 2000 through 2003) show beluga 

whales use upper Cook Inlet intensively 

between summer and late autumn 

(Hobbs et al. 2005). Critical Habitat Area 

1 encompasses this summer 

distribution. 

As late as October, beluga whales 

tagged with satellite transmitters 

continued to use Knik Arm and 

Turnagain Arm and Chickaloon Bay, but 

some ranged into lower Cook Inlet south 

to Chinitna Bay, Tuxedni Bay, and 

Trading Bay (McArthur River) in the fall 

(Hobbs et al. 2005). Data from NMFS 

aerial surveys, opportunistic sighting 

reports, and satellite-tagged beluga 

whales confirm they are more widely 

dispersed throughout Cook Inlet during 

the winter months (November to April), 

with animals found between Kalgin 

Island and Point Possession. In 

November, beluga whales moved 

between Knik Arm, Turnagain Arm, and 

Chickaloon Bay, similar to patterns 

observed in September (Hobbs et al. 

2005). By December, beluga whales 

were distributed throughout the upper 

to middle Cook Inlet. From January into 

March, they moved as far south as 

Kalgin Island and slightly beyond in 

central offshore waters. Beluga whales 

also made occasional excursions into 

Knik Arm and Turnagain Arm in 

February and March despite ice cover 

greater than 90 percent (Hobbs et al. 

2005). Critical Habitat Area 2 

encompasses some of the fall and winter 

feeding grounds in middle Cook Inlet. 

Ferguson et al. (2015) delineated one 

‘Small’ and ‘Resident’ BIA for Cook Inlet 

beluga whales. Small and Resident BIAs 

are defined as ‘‘areas and time within 

which small and resident populations 

occupy a limited geographic extent’’ 

(Ferguson et al. 2015). The Cook Inlet 

beluga whale BIA was delineated using 

the habitat model results of Goetz et al. 

2012 and the critical habitat boundaries 

and overlaps with both Critical Habitat 

Areas 1 and 2. 

During Apache’s seismic test program 

in 2011 along the west coast of Redoubt 

Bay, lower Cook Inlet, a total of 33 

beluga whales were sighted during the 

survey (Lomac-MacNair et al. 2013). 

During Apache’s 2012 seismic program 

in mid-inlet, a total of 151 sightings 

consisting of an estimated 1,463 beluga 

whales were observed (Lomac-MacNair 

et al. 2014). During SAExploration’s 

2015 seismic program, a total of eight 

sightings of 33 estimated individual 

beluga whales were visually observed 

during this time period and there were 

two acoustic detections of beluga 

whales (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 beluga whale sightings (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 beluga whale 

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 beluga whales were 

flown over the lower Cook Inlet region, 

but no beluga whales were observed. 

Killer Whale 

Based on data regarding association 

patterns, acoustics, movements, and 

genetic differences, eight killer whale 

stocks are now recognized within the 

Pacific U.S. Exclusive Economic Zone. 

Two different stocks of killer whales 

inhabit the Cook Inlet region of Alaska: 

The Alaska Resident Stock and the Gulf 

of Alaska, Aleutian Islands, Bering Sea 

Transient Stock (Muto et al. 2021). The 

Alaska Resident Stock and the Gulf of 

Alaska, Aleutian Islands, Bering Sea 

Transient Stock of killer whales are not 

designated as depleted under the 

MMPA or listed as threatened or 

endangered under the ESA. Reliable 

data on population trends for these 

killer whale stocks are unavailable 

(Muto et al. 2021). 

Resident and transient killer whales 

from the Alaska Resident Stock and the 

Gulf of Alaska, Aleutian Islands, and 

Bering Sea Transient Stock occur in 

Cook Inlet (Allen and Angliss 2015), 

though rarely in middle and upper Cook 

Inlet. Transient killer whales feed on 

beluga whales and other marine 

mammals, and resident populations 

feed on anadromous fish (Shelden et al. 

2003). The likelihood of killer whale 

occurrence depends on prey availability 

(NOAA 2019). Threats to and 

vulnerabilities of killer whales include 

natural causes, such as predation, and 

anthropogenic factors such as climate 

change, fishing operations and vessel 

strikes (Muto et al. 2016). 

Killer whales are occasionally 

observed in lower Cook Inlet, especially 

near Homer and Port Graham (Shelden 

et al. 2003; Rugh et al. 2005). The few 

whales that have been photographically 

identified in lower Cook Inlet belong to 

resident groups more commonly found 

in nearby Kenai Fjords and Prince 

William Sound (Shelden et al. 2003). 

The availability of prey species largely 

determines the likeliest times for killer 

whales to be in the area. During aerial 

surveys conducted between 1993 and 

2004, killer whales were observed on 

only three flights, all in the Kachemak 

and English Bay area (Rugh et al. 2005). 

However, anecdotal reports of killer 

whales feeding on belugas in middle 

and upper Cook Inlet began increasing 

in the 1990s, possibly in response to 

declines in sea lion and harbor seal prey 

elsewhere (Shelden et al. 2003). 

One killer whale group of two 

individuals was observed during the 

2015 SAExploration seismic program 

near the North Foreland (Kendall et al. 

2015). During NMFS aerial surveys, 

killer whales were observed in 1994 

(Kamishak Bay), 1997 (Kachemak Bay), 

2001 (Port Graham), 2005 (Iniskin Bay), 

2010 (Elizabeth and Augustine Islands), 

and 2012 (Kachemak Bay; Shelden et al. 

2013). Eleven killer whale strandings 

have been reported in Turnagain Arm, 

six in May 1991, and five in August 

1993. There were six sightings of 21 

killer whales observed in the 2019 

Hilcorp lower Cook Inlet seismic survey 

in the fall (Fairweather Science 2020). 

This species is expected to be rarely 

seen in upper Cook Inlet but may be 

encountered in the middle and lower 

Inlet. However, no killer whales were 

observed during the 4-month CIPL 

project in middle Cook Inlet in 2018 

(Sitkiewicz et al. 2018). 

Harbor Porpoise 

In Alaskan waters, three stocks of 

harbor porpoises are currently 

recognized for management purposes: 

Southeast Alaska, Gulf of Alaska, and 

Bering Sea Stocks (Muto et al. 2019). 

Porpoises found in Cook Inlet belong to 

the Gulf of Alaska Stock which is 

distributed from Cape Suckling to 


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Unimak Pass and most recently was 

estimated to number 31,046 individuals 

(Muto et al. 2019). Harbor porpoises are 

regularly seen throughout Cook Inlet 

(Nemeth et al. 2007), especially during 

spring eulachon and summer salmon 

runs. Harbor porpoises are not 

designated as depleted under the 

MMPA or listed as threatened or 

endangered under the ESA. 

Harbor porpoises primarily frequent 

the coastal waters of the Gulf of Alaska 

and Southeast Alaska (Dahlheim et al. 

2000, 2008), typically occurring in 

waters less than 100 m deep (Hobbs and 

Waite 2010). The range of the Gulf of 

Alaska stock includes the entire Cook 

Inlet, Shelikof Strait, and the Gulf of 

Alaska. Harbor porpoises have been 

reported in lower Cook Inlet from Cape 

Douglas to the West Foreland, 

Kachemak Bay, and offshore (Rugh et al. 

2005). Although they 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) and in the upper inlet. 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 beluga whales, as 

belugas move into upper inlet waters to 

forage on Pacific salmon (Oncorhynchus 

spp.) during the summer months 

(Shelden et al. 2014). Recent passive 

acoustic research in Cook Inlet by 

Alaska Department of Fish and Game 

(ADF&G) and MML have indicated that 

harbor porpoises occur more frequently 

than expected, particularly in the West 

Foreland area in the spring (Castellote et 

al. 2016). 

The harbor porpoise frequently has 

been observed during summer aerial 

surveys of Cook Inlet, with most 

sightings of individuals concentrated at 

Chinitna and Tuxedni Bays on the west 

side of lower Cook Inlet (Rugh et al. 

2005). Mating likely occurs from June or 

July to October, with peak calving in 

May and June (Consiglieri et al. 1982). 

Small numbers of harbor porpoises have 

been consistently reported in the upper 

Cook Inlet between April and October, 

except for a recent survey that recorded 

higher numbers than typical. NMFS 

aerial surveys have routinely identified 

many harbor porpoise sightings 

throughout Cook Inle. During Apache’s 

2012 seismic program, 137 sightings 

(190 individuals) were observed 

between May and August (LomacMacNair et al. 2013). Lomac-MacNair et 

al. 2014 identified 77 groups of harbor 

porpoise totaling 13 individuals during 

Apache’s 2014 seismic survey, both 

from vessels and aircraft, during the 

month of May. During SAExploration’s 

2015 seismic survey, 52 sightings (65 

individuals) were observed north of the 

Forelands (Kendall et al. 2015). There 

were 2 sightings of 3 harbor porpoises 

observed during the 2019 Hilcorp lower 

Cook Inlet seismic survey in the fall 

(Fairweather Science 2020). A total of 

29 sightings (44 individuals) were 

observed north of the Forelands from 

May to September during the Harvest 

Alaska CIPL project (Sitkiewicz et al. 

2018). During jack-up rig moves in 2021, 

a Protected Species Observer (PSO) 

observed two individual harbor 

porpoises in middle Cook Inlet, one in 

July and one in October. 

Dall’s Porpoise 

Dall’s porpoises are widely 

distributed across the North Pacific, but 

they are infrequently sighted in upper 

Cook Inlet (Muto et al. 2020). Dall’s 

porpoises have been observed in lower 

Cook Inlet, around Kachemak Bay, and 

rarely near Anchor Point (BOEM 2015). 

Dall’s porpoises are not designated as 

depleted under the MMPA or listed as 

threatened or endangered under the 

ESA (Muto et al. 2019). Threats to and 

vulnerabilities of Dall’s porpoises 

include natural and anthropogenic 

factors such as habitat modifications 

and climate change. The nearshore 

areas, bays, channels, and inlets where 

Dall’s porpoises frequent are of 

particular concern. These areas are 

subject to substantial changes with 

urbanization and industrialization, 

including waste management and 

nonpoint source runoff (Linnenschmidt 

et al. 2013). 

Throughout most of the eastern North 

Pacific they are present during all 

months of the year, although there may 

be seasonal onshore-offshore 

movements along the west coast of the 

continental U.S. and winter movements 

of populations out of areas with ice such 

as Prince William Sound (Muto et al. 

2019). No Dall’s porpoises were 

observed during the CIPL project 

monitoring program in middle Cook 

Inlet in 2018 (Sitkiewicz et al. 2018). 

Dall’s porpoises were observed (two 

groups of three individuals) during 

Apache’s 2014 seismic survey which 

occurred in the summer months 

(Lomac-MacNair et al. 2014). Dall’s 

porpoises were observed during the 

month of June in 1997 (Iniskin Bay), 199 

(Barren Island), and 2000 (Elizabeth 

Island, Kamishak Bay and Barren 

Island) (Shelden et al. 2013). Dall’s 

porpoises have been observed in lower 

Cook Inlet, including Kachemak Bay 

and near Anchor Point (Owl Ridge 

2014). One Dall’s porpoise was observed 

in August north of Nikiski in the middle 

of the Inlet during SAExploration’s 2015 

seismic program (Kendall et al. 2015). 

There were 10 sightings of 30 Dall’s 

porpoises observed during the 2019 

Hilcorp lower Cook Inlet seismic survey 

in the fall (Fairweather Science 2020). 

Steller Sea Lion 

The Western DPS of Steller sea lions 

is currently listed as endangered under 

the ESA (55 FR 49204; November 26, 

1990) and designated as depleted under 

the MMPA. Critical habitat was 

designated on August 27, 1993 (58 FR 

45269; August 27, 1993) south of the 

proposed action area in the Cook Inlet 

region. The critical habitat designation 

for the Western DPS of Steller sea lions 

includes a 37 km buffer around all 

major haul outs and rookeries, and 

associated terrestrial, atmospheric, and 

aquatic zones, plus three large offshore 

foraging areas, as well as designated no 

entry zones around rookeries (50 CFR 

223.202). Designated critical habitat is 

located outside Cook Inlet at Gore Point, 

Elizabeth Island, Perl Island, and 

Chugach Island (NMFS 2008b). The 

Western DPS of the Steller sea lion is 

defined as all populations west of 

longitude 144° W to the western end of 

the Aleutian Islands. 

Steller sea lions are not migratory 

animals but exhibit wide dispersion in 

the non-breeding season (Loughlin 

1997). They are polygynous in nature, 

with one male typically breeding with 

large numbers of females. Steller sea 

lions tend to haul out in large groups. 

Underwater vocalizations of Steller 

sea lions have been noted to include 

belches, barks, and clicks (Kastelein et 

al. 2005). Audiograms have revealed a 

maximum underwater hearing 

sensitivity at 77 dB RL at 1kHz for a 

male Steller sea lion, with a range of 

best hearing at 10 dB from the 

maximum sensitivity, of between 1 and 

16 kHz. His average pre-stimulus 

responses occurred at low frequency 

signals. Similar audiograms of a female 

Steller sea lion revealed a maximum 

hearing sensitivity of 73 dB received 

level, occurring at 25 kHz, indicating 

that low frequency sounds are audible 

to Steller sea lions (Kastelein et al. 

2005). 

Steller sea lions feed largely on 

walleye pollock (Theragra 

chalcogramma), salmon (Onchorhyncus 

spp.), and arrowtooth flounder 

(Atheresthes stomias) during the 

summer, and walleye pollock and 

Pacific cod (Gadus macrocephalus) 

during the winter (Sinclair and 

Zeppelin 2002). Except for salmon, 

these species are not found in 


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abundance in upper Cook Inlet (Nemeth 

et al. 2007). Threats to and 

vulnerabilities of Steller sea lions 

include natural and anthropogenic 

factors, including depletion of prey 

availability from fishing activities, 

climate change, disease, contaminants, 

predation by killer whales, incidental 

take, and illegal and legal shooting 

(Atkinson et al. 2008, NMFS 2008), 

harmful algal blooms (Lefebvre et al. 

2016), disease proliferation from 

warming waters (VanWormer et al. 

2019), and potentially metal and 

contaminant exposure (Rea et al. 2013; 

Beckmen et al. 2016, Keogh et al. 2020). 

Steller sea lions inhabit lower Cook 

Inlet, especially near Shaw Island and 

Elizabeth Island (Nagahut Rocks) haul 

out sites (Rugh et al. 2005) but are rarely 

seen in upper Cook Inlet (Nemeth et al. 

2007). Steller sea lions occur in Cook 

Inlet but south of Anchor Point around 

the offshore islands and along the west 

coast of the upper inlet in the bays 

(Chinitna Bay, Iniskin Bay, etc.) (Rugh 

et al. 2005). Portions of the southern 

reaches of the lower inlet are designated 

as critical habitat, including a 37 km (20 

nautical mile) buffer around all major 

haul out sites and rookeries. Rookeries 

and haul out sites in lower Cook Inlet 

include those near the mouth of the 

inlet, which are far south of the Action 

Area. 

Steller sea lions have been observed 

during marine mammal surveys 

conducted in Cook Inlet. In 2012, during 

Apache’s 3D Seismic surveys, there 

were three sightings of approximately 

four individuals in upper Cook Inlet 

(Lomac-MacNair et al. 2013). Marine 

mammal observers associated with 

Buccaneer’s drilling project off Cape 

Starichkof observed seven Steller sea 

lions during the summer of 2013 (Owl 

Ridge 2014). During SAExploration’s 3D 

Seismic Program in 2015, four Steller 

sea lions were observed in Cook Inlet. 

One sighting occurred between the West 

and East Forelands, one near Nikiski 

and one northeast of the North Foreland 

in the center of Cook Inlet (Kendall et 

al. 2015). There were five sightings of 

five Steller sea lions observed during 

the 2019 Hilcorp lower Cook Inlet 

seismic survey in the fall (Fairweather 

Science 2020). One sighting of two 

individuals occurred during the CIPL 

project in 2018 in middle Cook Inlet 

(Sitkiewicz et al. 2018). During NMFS 

Cook Inlet beluga whale aerial surveys 

from 2000 to 2016, there were 39 

sightings of 769 estimated individual 

Steller sea lions in lower Cook Inlet 

(Shelden et al. 2017). Sightings of large 

congregations of Steller sea lions during 

NMFS aerial surveys occurred outside 

the Action Area, on land in the mouth 

of Cook Inlet (e.g., Elizabeth and Shaw 

Islands). 

California Sea Lion 

California sea lions in the U.S. are not 

listed as endangered or threatened 

under the ESA or as depleted or 

strategic under the MMPA. The growth 

rate of the species is approximately 

seven percent annually (Carretta et al. 

2020). There is limited information on 

the presence of California sea lions in 

Alaska. California sea lion presence in 

Alaska was correlated with increasing 

population numbers within their 

southern breeding range (Maniscalco et 

al. 2004). California sea lions are not 

commonly observed in Alaska. When 

they are observed, they are often alone 

or, less commonly, in groups of two or 

more. They are most often associated 

with Steller sea lions at their haulouts 

and rookeries (Maniscalco et al. 2004). 

Threats to and vulnerabilities of 

California sea lions include natural and 

anthropogenic factors including climate 

change, exposure to harmful algal 

neurotoxins (Scholin et al. 2000, Brodie 

et al. 2006, Ramsdell and Zabka 2008), 

shootings, entrainment in industrial 

facilities, fishing gear interactions, 

vessel strikes, and human disturbance 

(Muto et al. 2019). 

California sea lions are not typically 

observed farther north than southeast 

Alaska, and sightings are very rare in 

Cook Inlet. California sea lions have not 

been observed during the annual NMFS 

aerial surveys in Cook Inlet. However, a 

sighting of two California sea lions was 

documented during the Apache 2012 

seismic survey (Lomac-MacNair et al. 

2013). Additionally, NMFS’ anecdotal 

sighting database has four sightings in 

Seward and Kachemak Bay. There were 

no California sea lions observed during 

the 2019 Hilcorp lower Cook Inlet 

seismic survey (Fairweather Science 

2020) or the CIPL project in 2018 

(Sitkiewicz et al. 2018). 

Harbor Seal 

In 2010, NMFS and their comanagement partners, the Alaska Native 

Harbor Seal Commission, defined 12 

separate stocks of harbor seals based 

largely on genetics. The harbor seal 

stocks present in the action area are 

from the Cook Inlet/Shelikof stock. No 

harbor seal stocks in Alaska are 

designated as depleted under the 

MMPA or listed as threatened or 

endangered under the ESA (Muto et al. 

2019). 

In Cook Inlet, large harbor seal 

haulout areas are located in lower Cook 

Inlet, with occurrence in upper inlet 

coinciding with prey availability. 

Harbor seals frequent the Susitna River 

and other rivers feeding into upper Cook 

Inlet when eulachon and salmon are 

migrating in those areas (NMFS, 2003). 

Harbor seals haul out on rocks, reefs, 

beaches, and drifting glacial ice. Prey 

species include capelin, eulachon, cod, 

pollock, flatfish, shrimp, octopus, and 

squid. Threats to and vulnerabilities of 

harbor seals include natural and 

anthropogenic factors including climate 

change, shipping, and tour vessel traffic 

(Muto et al. 2021). 

The major haul out sites for harbor 

seals are located in lower Cook Inlet and 

their presence in middle and upper 

Cook Inlet is seasonal. In Cook Inlet, 

seal use of western habitats is greater 

than use of the eastern coastline 

(Boveng et al. 2012). NMFS has 

documented a strong seasonal pattern of 

more coastal and restricted spatial use 

during the spring and summer for 

breeding, pupping, and molting, and 

more wide-ranging seal movements 

within and outside of Cook Inlet during 

the winter months (Boveng et al. 2012). 

Large-scale movement patterns indicate 

a portion of harbor seals captured in 

Cook Inlet move out of the area in the 

fall, and into habitats within Shelikof 

Strait, Northern Kodiak Island, and 

coastal habitats of the Alaska Peninsula, 

and are most concentrated in Kachemak 

Bay, across Cook Inlet toward Iniskin 

and Iliamna Bays, and south through the 

Kamishak Bay, Cape Douglas, and 

Shelikof Strait regions (Boveng et al. 

2012). 

The Cook Inlet/Shelikof Stock is 

distributed from Anchorage into lower 

Cook Inlet during summer and from 

lower Cook Inlet through Shelikof Strait 

to Unimak Pass during winter (Boveng 

et al. 2012). Large numbers concentrate 

at the river mouths and embayments of 

lower Cook Inlet, including the Fox 

River mouth in Kachemak Bay, and 

several haul outs have been identified 

on the southern end of Kalgin Island in 

lower Cook Inlet (Rugh et al. 2005; 

Boveng et al. 2012). Montgomery et al. 

(2007) recorded over 200 haul-out sites 

in lower Cook Inlet alone. 

NMFS aerial surveys have routinely 

identified many harbor seal sightings 

throughout Cook Inlet over the past 20 

years of survey effort. During Apache’s 

2012 seismic program, harbor seals were 

observed in the project area from early 

May until the end of the seismic 

operations in late September (LomacMacNair et al. 2013). Up to 100 harbor 

seals were observed hauled out at the 

mouths of the Theodore and Lewis 

rivers during monitoring activity. 

During Apache’s 2014 seismic program, 

492 groups of harbor seals (613 

individuals) were observed; this highest 

sighting rate of any marine mammal 


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observed during the summer of 2014 

(Lomac-MacNair et al. 2014). During 

SAExploration’s 2015 seismic survey, 

823 sightings (1,680 individuals) were 

observed north and between the 

Forelands (Kendall et al. 2015). 

Recently, a total of 313 sightings (316 

individuals) were observed near Ladd 

Landing for the Harvest Alaska CIPL 

project during the summer (Sitkiewicz 

et al. 2018). There were 10 sightings of 

10 harbor seals observed during the 

2019 Hilcorp lower Cook Inlet seismic 

survey in the fall (Fairweather Science 

2020). During a Hilcorp jack-up rig 

move in 2021, one pinniped of an 

unidentified species was observed in 

July in middle Cook Inlet. 

Marine Mammal Hearing 

Hearing is the most important sensory 

modality for marine mammals 

underwater, and exposure to 

anthropogenic sound can have 

deleterious effects. To appropriately 

assess the potential effects of exposure 

to sound, it is necessary to understand 

the frequency ranges marine mammals 

are able to hear. Not all marine mammal 

species have equal hearing capabilities 

(e.g., Richardson et al., 1995; Wartzok 

and Ketten, 1999; Au and Hastings, 

2008). To reflect this, Southall et al. 

(2007, 2019) recommended that marine 

mammals be divided into hearing 

groups based on directly measured 

(behavioral or auditory evoked potential 

techniques) or estimated hearing ranges 

(behavioral response data, anatomical 

modeling, etc.). Note that no direct 

measurements of hearing ability have 

been successfully completed for 

mysticetes (i.e., low-frequency 

cetaceans). Subsequently, NMFS (2018) 

described generalized hearing ranges for 

these marine mammal hearing groups. 

Generalized hearing ranges were chosen 

based on the approximately 65 decibel 

(dB) threshold from the normalized 

composite audiograms, with the 

exception for lower limits for lowfrequency cetaceans where the lower 

bound was deemed to be biologically 

implausible and the lower bound from 

Southall et al. (2007) retained. Marine 

mammal hearing groups and their 

associated hearing ranges are provided 

in Table 5. 

TABLE 5—MARINE MAMMAL HEARING GROUPS

[NMFS, 2018] 

Hearing group Generalized hearing 

range * 

Low-frequency (LF) cetaceans (baleen whales) ......................................................................................................................... 7 Hz to 35 kHz. 

Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales) .............................................. 150 Hz to 160 kHz. 

High-frequency (HF) cetaceans (true porpoises, Kogia, river dolphins, cephalorhynchid, Lagenorhynchus cruciger & L. 

australis).

275 Hz to 160 kHz. 

Phocid pinnipeds (PW) (underwater) (true seals) ....................................................................................................................... 50 Hz to 86 kHz. 

Otariid pinnipeds (OW) (underwater) (sea lions and fur seals) .................................................................................................. 60 Hz to 39 kHz. 

* Represents the generalized hearing range for the entire group as a composite (i.e., all species within the group), where individual species’ 

hearing ranges are typically not as broad. Generalized hearing range chosen based on ∼65 dB threshold from normalized composite audiogram, 

with the exception for lower limits for LF cetaceans (Southall et al. 2007) and PW pinniped (approximation). 

The pinniped functional hearing 

group was modified from Southall et al. 

(2007) on the basis of data indicating 

that phocid species have consistently 

demonstrated an extended frequency 

range of hearing compared to otariids, 

especially in the higher frequency range 

(Hemila ̈ et al., 2006; Kastelein et al., 

2009; Reichmuth and Holt, 2013). 

For more detail concerning these 

groups and associated frequency ranges, 

please see NMFS (2018) for a review of 

available information. 

Potential Effects of Specified Activities 

on Marine Mammals and Their Habitat 

This section includes a summary and 

discussion of the ways that components 

of the specified activity may impact 

marine mammals and their habitat. The 

Estimated Take 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 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 how 

those impacts on individuals are likely 

to impact marine mammal species or 

stocks. 

The proposed project includes the use 

of three tugs towing a jack-up rig, which 

would emit consistent, low levels of 

noise into a small portion of Cook Inlet 

for an extended period of time. 

Hilcorp’s tugging and positioning 

activities would occur for 

approximately 16 days in Year 1 and 16 

days in Year 2 to support overall 

production and well plug and 

abandonment operations that would 

occur across 210 days in Year 1 and 180 

days in Year 2. Unlike projects that 

involve discrete noise sources with 

known potential to harass marine 

mammals (e.g., pile driving, seismic 

surveys), both the noise sources and 

impacts from the tugs towing the jackup rig are less well documented. In light 

of the aforementioned court decision we 

have re-examined the available 

information. The various scenarios that 

may occur during this project extend 

from tugs in a stationary mode, 

positioning the drill rig to pulling the 

jack-up rig at nearly full power against 

strong tides. Our assessments of the 

potential for harassment of marine 

mammals incidental to Hilcorp’s tug 

activities specified here are conservative 

in light of the general Level B 

harassment exposure thresholds, the 

fact that NMFS is still in the process of 

developing analyses of the impact that 

non-quantitative contextual factors have 

on the likelihood of Level B harassment 

occurring, and the nature and duration 

of the particular tug activities analyzed 

here. 

The proposed project has the 

potential to harass marine mammals 

from exposure to noise and the physical 

presence of working vessels (e.g., three 

tug configuration) as well as associated 

noise with the positioning of the jackup rig. In this case, NMFS considers 

potential for harassment from the 

collective use of these technologies 

working in a concentrated area (relative 

to the entire Cook Inlet) for an extended 

period of time (when making multiple 

positioning attempts) and noise created 

when moving the jack-up rig using three 

tugs. Essentially, the project area will 

become a concentrated work area in an 

otherwise non-industrial setting for a 

period of several days. Accordingly the 

Estimated Take section proposes to 

authorize take, by Level B harassment, 


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from tug towing activities over the 

course of 16 days of activity each year. 

Auditory Effects 

NMFS defines a noise-induced 

threshold shift (TS) as ‘‘a change, 

usually an increase, in the threshold of 

audibility at a specified frequency or 

portion of an individual’s hearing range 

above a previously established reference 

level’’ (NMFS, 2018). The amount of 

threshold shift is customarily expressed 

in dB (ANSI 1995, Yost 2007). A TS can 

be permanent (PTS) or temporary (TTS). 

As described in NMFS (2016), 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 nonimpulsive), likelihood an individual 

would be exposed for a long enough 

duration or to a high enough level to 

induce a TS, the magnitude of the TS, 

time to recovery (seconds to minutes or 

hours to days), the frequency range of 

the exposure (i.e., spectral content), the 

hearing and vocalization frequency 

range of the exposed species relative to 

the signal’s frequency spectrum (i.e., 

how animal uses sound within the 

frequency band of the signal; e.g., 

Kastelein et al., 2014), and the overlap 

between the animal and the source (e.g., 

spatial, temporal, and spectral). When 

analyzing the auditory effects of noise 

exposure, it is often helpful to broadly 

categorize sound as either impulsive— 

noise with high peak sound pressure, 

short duration, fast rise-time, and broad 

frequency content—or non-impulsive. 

For example, when considering auditory 

effects, vibratory pile driving is 

considered a non-impulsive source 

while impact pile driving is treated as 

an impulsive source. The sounds 

produced by tugs towing and 

positioning the jack-up rig are 

characterized as non-impulsive sounds. 

Permanent Threshold Shift—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 2018). Available data from 

humans and other terrestrial mammals 

indicate that a 40 dB threshold shift 

approximates PTS onset (see NMFS 

2018 for review). 

Temporary Threshold Shift—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 

Finneran 2015 for a review), a TTS of 

6 dB is considered the minimum 

threshold shift clearly larger than any 

day-to-day or session-to-session 

variation in a subject’s normal hearing 

ability (Schlundt et al., 2000; Finneran 

et al., 2002; Finneran, 2015). 

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 

times when hearing is critical, such as 

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. 

Masking 

Since many marine mammals rely on 

sound to find prey, moderate social 

interactions, and facilitate mating 

(Tyack, 2008), noise from anthropogenic 

sound sources can interfere with these 

functions, but only if the noise spectrum 

overlaps with the hearing sensitivity of 

the marine mammal (Southall et al., 

2007; Clark et al., 2009; Hatch et al., 

2012). Chronic exposure to excessive, 

though not high-intensity, noise could 

cause masking at particular frequencies 

for marine mammals that utilize sound 

for vital biological functions (Clark et 

al., 2009). Acoustic masking is when 

other noises such as from human 

sources interfere with animal detection 

and/or interpretation of acoustic signals 

such as communication calls, 

echolocation sounds, and 

environmental sounds important to 

marine mammals. Therefore, under 

certain circumstances, marine mammals 

whose acoustical sensors or 

environment are being severely masked 

could also be impaired from maximizing 

their performance fitness in survival 

and reproduction. 

Masking occurs in the frequency band 

that the animals utilize. Since noises 

generated from tugs towing and 

positioning are mostly concentrated at 

low frequency ranges, with a small 

concentration in high frequencies as 

well, these activities likely have less 

effect on mid-frequency echolocation 

sounds by odontocetes (toothed whales) 

such as Cook Inlet beluga whales. 

However, lower frequency noises are 

more likely to affect detection of 

communication calls and other 

potentially important natural sounds 

such as surf and prey noise. Lowfrequency noise may also affect 

communication signals when they occur 

near the noise band and thus reduce the 

communication space of animals (e.g., 

Clark et al., 2009) and cause increased 

stress levels (e.g., Holt et al., 2009). 

Unlike TS, masking, which can occur 

over large temporal and spatial scales, 

can potentially affect the species at 

population, community, or even 

ecosystem levels, in addition to 

individual levels. Masking affects both 

senders and receivers of the signals and 

at higher levels for longer durations 

could have long-term chronic effects on 

marine mammal species and 

populations. However, the noise 

generated by the tugs will not be 

concentrated in one location or for more 

than five hours per day and in the same 

geographic location for only two days 

per well site. 

Behavioral Disturbance 

Finally, exposure of marine mammals 

to certain sounds could result in 

behavioral disturbance (Richardson et 

al., 1995), not all of which constitutes 

harassment under the MMPA. The onset 

of behavioral disturbance from 

anthropogenic noise depends on both 

external factors (e.g., characteristics of 

noise sources and their paths) and the 

receiving animals (e.g., hearing, 

behavioral state, experience, 

demography) and is difficult to predict 

(Southall et al., 2007, 2021). Currently 

NMFS uses a received level of 160 dB 

re 1 micro Pascal (mPa) root mean square 

(rms) to predict the onset of behavioral 

harassment from impulse noises (such 

as impact pile driving), and 120 dB re 

1 mPa (rms) for continuous noises (such 

as operating dynamic positioning (DP) 

thrusters), although in certain 

circumstances there may be contextual 

factors that alter our assessment of the 

onset of behavioral harassment. No 

impulsive noise within the hearing 

range of marine mammals is expected 

from Hilcorp’s proposed activities. For 

the tug towing and positioning 

activities, only the 120 dB re 1 mPa (rms) 

threshold is considered because only 

continuous noise sources would be 

generated. 

Disturbance may result in changing 

durations of surfacing and dives, 

number of blows per surfacing, moving 


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direction and/or speed, reduced/ 

increased vocal activities; changing/ 

cessation of certain behavioral activities 

(such as socializing or feeding), visible 

startle response or aggressive behavior 

(such as tail/fluke slapping or jaw 

clapping), avoidance of areas where 

sound sources are located, and/or flight 

responses. Pinnipeds may increase their 

haul-out time, possibly to avoid inwater disturbance (Thorson and Reyff 

2006). These potential behavioral 

responses to sound are highly variable 

and context-specific and reactions, if 

any, depend on species, state of 

maturity, experience, current activity, 

reproductive state, auditory sensitivity, 

time of day, and many other factors 

regarding the source eliciting the 

response (Richardson et al., 1995; 

Wartzok et al., 2004; Southall et al., 

2007). For example, animals that are 

resting may show greater behavioral 

change in response to disturbing sound 

levels than animals that are highly 

motivated to remain in an area for 

feeding (Richardson et al., 1995; NRC 

2003; Wartzok et al., 2004). The 

biological significance of many of these 

behavioral disturbances is difficult to 

predict, especially if the detected 

disturbances appear minor. However, 

the consequences of behavioral 

modification could be biologically 

significant if the change affects growth, 

survival, and/or reproduction, which 

depends on the severity, duration, and 

context of the effects. 

In consideration of the range of 

potential effects (PTS to behavioral 

disturbance), we consider the potential 

exposure scenarios and context in 

which species would be exposed to tugrelated activity. Cook Inlet beluga 

whales 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 noise. However, beluga 

whales are 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 are expected to be headed to 

or from the concentrated foraging areas 

farther north near the Beluga River, 

Susitna Delta, and Knik and Turnigan 

Arms. Similarly, humpback whales, fin 

whales, minke whales, killer whales, 

California sea lion, and Steller sea lions 

are not expected to remain in the area 

of the tugs. 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 porpoises, they are 

unlikely to remain at any particular well 

site for the full duration of the noiseproducing activity. Because of this and 

the relatively low-level sources, the 

likelihood of PTS and TTS over the 

course of the tug activities is 

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 (there are 

no known major haul-outs or rookeries 

coinciding with the well sites). Here we 

find there is small potential for TTS 

over the course of tug activities but 

again, PTS is not likely due to the types 

of sources involved in the project. 

Given most marine mammals are 

likely transiting through the area, 

exposure is expected to be brief but, in 

combination with the actual presence of 

the tug and jack-up rig configuration, 

may result in animals shifting pathways 

around the work site (e.g., avoidance), 

increasing speed or dive times, or 

cessation of vocalizations. The 

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 do 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. For example, during low 

levels of power output (e.g., while tugs 

may be operating at low power because 

of favorable conditions), the animals 

may be able to hear the work but any 

resulting reactions, if any, are not 

expected to rise to the level of take. 

While in some cases marine mammals 

have exhibited little to no obviously 

detectable response to certain common 

or routine industrialized activity 

(Cornick et al, 2011), it is possible some 

animals may at times be exposed to 

received levels of sound above the Level 

B harassment threshold. This potential 

exposure in combination with the 

nature of the tug and jack-up rig 

configuration (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 

tug activities; therefore, NMFS in 

response to Hilcorp’s IHA application 

proposes to authorize take by Level B 

harassment from Hilcorp’s use of tugs 

towing a jack-up rig for both positioning 

and straight-line tug activities. 

Estimated Take 

This section provides an estimate of 

the number of incidental takes proposed 

for authorization through this IHA, 

which will inform both NMFS’ 

consideration of ‘‘small numbers’’ and 

the negligible impact determinations. 

Harassment is the only type of take 

reasonably expected to result from these 

activities. Except with respect to certain 

activities not pertinent here, section 

3(18) of the MMPA defines 

‘‘harassment’’ as any act of pursuit, 

torment, or annoyance, which (i) has the 

potential to injure a marine mammal or 

marine mammal stock in the wild (Level 

A harassment); or (ii) has the potential 

to disturb a marine mammal or marine 

mammal stock in the wild by causing 

disruption of behavioral patterns, 

including, but not limited to, migration, 

breathing, nursing, breeding, feeding, or 

sheltering (Level B harassment). 

Authorized takes would be by Level B 

harassment only, in the form of 

disruption of behavioral patterns for 

individual marine mammals resulting 

from exposure to the tugs towing and 

positioning the jack-up rig. Based on the 

nature of the activity, Level A 

harassment is neither anticipated nor 

proposed to be authorized. 

As described previously, no serious 

injury or mortality is anticipated or 

proposed to be authorized for this 

activity. Below we describe how the 

proposed take numbers are estimated. 

For acoustic impacts, generally 

speaking, we estimate take by 

considering: (1) Acoustic thresholds 

above which NMFS believes the best 

available science indicates marine 

mammals will be behaviorally harassed 

or incur some degree of permanent 

hearing impairment; (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 Thresholds 

NMFS recommends the use of 

acoustic thresholds that identify the 

received level of underwater sound 

above which exposed marine mammals 

would be reasonably expected to be 

behaviorally harassed (equated to Level 


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B harassment) or to incur PTS of some 

degree (equated to Level A harassment). 

Level B Harassment—Though 

significantly driven by received level, 

the onset of behavioral disturbance or 

harassment from anthropogenic noise 

exposure is also informed to varying 

degrees by other factors related to the 

source or exposure context (e.g., 

frequency, predictability, duty cycle, 

duration of the exposure, signal-to-noise 

ratio, distance to the source), the 

environment (e.g., bathymetry, other 

noises in the area, predators in the area), 

and the receiving animals (hearing, 

motivation, experience, demography, 

life stage, depth) and can be difficult to 

predict (e.g., Southall et al., 2007, 2021, 

Ellison et al., 2012). Accordingly, 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 reasonably 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 mPa)) for 

continuous (e.g., vibratory pile-driving, 

drilling) and above RMS SPL, 160 dB re 

1 mPa (rms) for non-explosive impulsive 

(e.g., seismic airguns) or intermittent 

(e.g., scientific sonar) sources. 

Hilcorp’s activity includes the use of 

continuous (tug towing and positioning 

the rig) sources, and therefore the RMS 

SPL 120 dB re 1 mPa is applicable. 

Level A harassment for non-explosive 

sources—NMFS’ Technical Guidance 

for Assessing the Effects of 

Anthropogenic Sound on Marine 

Mammal Hearing (Version 2.0) 

(Technical Guidance, 2018) identifies 

dual criteria to assess auditory injury 

(Level A harassment) to five different 

marine mammal groups (based on 

hearing sensitivity) as a result of 

exposure to noise from two different 

types of sources (impulsive or nonimpulsive). Hilcorp’s proposed activity 

includes the use of non-impulsive (tugs 

towing rig) sources. 

These thresholds are provided in the 

table below. The references, analysis, 

and methodology used in the 

development of the thresholds are 

described in NMFS 2018 Technical 

Guidance, which may be accessed at 

https://www.fisheries.noaa.gov/ 

national/marine-mammal-protection/ 

marine-mammal-acoustic-technicalguidance. 

TABLE 6—THRESHOLDS IDENTIFYING THE ONSET OF PERMANENT THRESHOLD SHIFT

Hearing group 

PTS onset acoustic thresholds * 

(received level) 

Impulsive Non-Impulsive 

Low-Frequency (LF) Cetaceans ...................................... Cell 1: Lpk,flat: 219 dB; LE,LF,24h: 183 dB ......................... Cell 2: LE,LF,24h: 199 dB. 

Mid-Frequency (MF) Cetaceans ...................................... Cell 3: Lpk,flat: 230 dB; LE,MF,24h: 185 dB ........................ Cell 4: LE,MF,24h: 198 dB. 

High-Frequency (HF) Cetaceans ..................................... Cell 5: Lpk,flat: 202 dB; LE,HF,24h: 155 dB ........................ Cell 6: LE,HF,24h: 173 dB. 

Phocid Pinnipeds (PW) (Underwater) ............................. Cell 7: Lpk,flat: 218 dB; LE,PW,24h: 185 dB ....................... Cell 8: LE,PW,24h: 201 dB. 

Otariid Pinnipeds (OW) (Underwater) ............................. Cell 9: Lpk,flat: 232 dB; LE,OW,24h: 203 dB ....................... Cell 10: LE,OW,24h: 219 dB. 

* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level thresholds associated with impulsive sounds, these thresholds should 

also be considered. 

Note: Peak sound pressure (Lpk) has a reference value of 1 μPa, and cumulative sound exposure level (LE) has a reference value of 1μPa2s. 

In this Table, thresholds are abbreviated to reflect American National Standards Institute standards (ANSI 2013). However, peak sound pressure 

is defined by ANSI as incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ‘‘flat’’ is being 

included to indicate peak sound pressure should be flat weighted or unweighted within the generalized hearing range. The subscript associated 

with cumulative sound exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, MF, and HF 

cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours. The cumulative sound exposure level 

thresholds could be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it is valuable for 

action proponents to indicate the conditions under which these acoustic thresholds will be exceeded. 

Ensonified Area 

Here, we describe operational and 

environmental parameters of the activity 

that will feed into identifying the area 

ensonified above the acoustic 

thresholds, which include source levels 

and transmission loss coefficient. 

As described above in the Detailed 

Description of the Specific Activity, 

based on in situ measurements of 

Hilcorp’s tug and a review of the 

available literature of tugs under load, a 

source level of 185 dB re 1 mPa was used 

for Hilcorp’s three tug configuration for 

towing the jack-up-rig. Hilcorp 

contracted SLR Consulting to model the 

extent of the Level B harassment 

isopleth as well as the extent of the PTS 

isopleth for their proposed activity. 

Rather than applying practical 

spreading loss, SLR created a more 

detailed propagation loss model in an 

effort to improve the accuracy of the 

results by considering the influence of 

environmental variables (e.g. 

bathymetry) at the specific well sites, as 

Hilcorp’s operational locations are 

known in advance. Modeling was 

conducted using dBSea software. The 

fluid parabolic equation modeling 

algorithm was used with 5 Pade ́ terms 

(see pg. 57 in Hilcorp’s application for 

more detail) to calculate the 

transmission loss between the source 

and the receiver at low frequencies (1/ 

3-octave bands, 31.5 Hz up to 1 kHz). 

For higher frequencies (1 kHz up to 8 

kHz) the ray tracing model was used 

with 1,000 reflections for each ray. 

Sound sources were assumed to be 

omnidirectional and modeled as points. 

The received sound levels for the 

project were calculated as follows: (1) 

One-third octave source spectral levels 

were obtained via reference spectral 

curves with subsequent corrections 

based on their corresponding overall 

source levels; (2) Transmission loss was 

modeled at one-third octave band 

central frequencies along 100 radial 

paths at regular increments around each 

source location, out to the maximum 

range of the bathymetry data set or until 

constrained by land; (3) The bathymetry 

variation of the vertical plane along 

each modeling path was obtained via 

interpolation of the bathymetry dataset 

which has 83 m grid resolution; (4) The 

one-third octave source levels and 

transmission loss were combined to 

obtain the received levels as a function 

of range, depth, and frequency; and (5) 

The overall received levels were 

calculated at a 1-m depth resolution 

along each propagation path by 


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summing all frequency band spectral 

levels. 

Model Inputs—Bathymetry data used 

in the model was collected from the 

NOAA National Centers for 

Environmental Information (AFSC 

2019). Using NOAA’s temperature and 

salinity data, sound speed profiles were 

computed for depths from 0 to 100 

meters for May, July, and October to 

capture the range of possible sound 

speed depending on the time of year 

Hilcorp’s work could be conducted. 

These sound speed profiles were 

compiled using the Mackenzie Equation 

(1981) and are presented in Table 8 of 

Hilcorp’s application. Geoacoustic 

parameters were also incorporated into 

the model. The parameters were based 

on substrate type and their relation to 

depth. These parameters are presented 

in Table 9 of Hilcorp’s application. 

Detailed broadband sound 

transmission loss modeling in dBSea 

used the source level of 185 dB re 1 mPa 

at 1 m calculated in one-third octave 

band levels (31.5 Hz to 64,000 Hz) for 

frequency dependent solutions. The 

frequencies associated with tug sound 

sources occur within the hearing range 

of marine mammals in Cook Inlet. 

Received levels for each hearing marine 

mammal group based on one-third 

octave auditory weighting functions 

were also calculated and integrated into 

the modeling scenarios of dBSea. For 

modeling the distances to relevant PTS 

thresholds, a weighting factor 

adjustment was not used; instead, the 

data on the spectrum associated with 

their source was used and incorporated 

the full auditory weighting function for 

each marine mammal hearing group. 

Because Hilcorp plans to use the tugs 

towing the jack-up-rig for essentially 

two functions (positioning and towing), 

the activity was divided into two parts 

(stationary and mobile) and two 

approaches were taken for modeling the 

relevant isopleths. 

Stationary—For stationary activity, 

two locations representative of where 

tugs will be stationary positioning the 

jack-up rig were selected for the model. 

These locations are in middle Cook Inlet 

near the Tyonek platform, and in lower 

Trading Bay where the production 

platforms are located, with water depths 

of 40 m and 20 m respectively. The 

modeling at these locations assumed a 

stationary five-hour exposure to a 

broadband spectrum of 185 dB as 

described above. A five-hour exposure 

duration was chosen to account for the 

up to five-hour positioning attempts on 

individual days as well as events where 

the tugs need to hold the jack-up rig 

while waiting for a following tide. 

Stationary model results are presented 

in Table 7. 

Mobile—For the mobile portion of the 

activity, a representative route was used 

from the Rig Tender’s dock in Nikiski to 

the Tyonek platform, the northernmost 

platform in Cook Inlet (representing 

Middle Cook Inlet), as well as from the 

Tyonek Platform to the Dolly Varden 

platform in lower Trading Bay and then 

from the Dolly Varden platform back to 

the Rig Tender’s Dock in Nikiski. This 

route is representative of a typical route 

the tugs may take; the specific route is 

not yet known because the order in 

which platforms will be drilled with the 

jack-up rig is not yet known. The lowest 

threshold for the onset of PTS is for high 

frequency cetaceans at 173 dB. Based on 

a source level of 185 dB, and assuming 

practical spreading, the high frequency 

cetacean PTS threshold of 173 dB would 

be reached at 6.3 meters away from the 

source. The mobile source modeling 

assumed a transit speed of 2.06 m/s for 

the tug configuration. With an assumed 

vessel speed of 2.06 m/s, it would take 

the vessel 6.11 seconds to traverse a 

distance of two times the radius, with 

two times the radius used because the 

source is omnidirectional and the ship 

is moving in a straight line. Although a 

source level of 185 dB incorporates the 

use of three tugs simultaneously, 

because the three tugs will likely not be 

perfectly aligned in space (e.g. one 

could lag slightly behind the forward 

two), three separate six second 

exposures were summed (one for each 

tug passing in space) to arrive at a total 

duration of exposure of 18 seconds. 

While it is possible the duration of 

exposure could be as short as six 

seconds if all tugs were perfectly 

aligned, separate exposures for each tug 

were considered as the exact formation 

of the tugging vessels at any given time 

is unknown. Mobile source model 

results are presented in Table 8. 

Because there is no temporal 

component associated with NMFS’ 

current Level B threshold, making it a 

potentially conservative assumption 

given the transitory nature of the rig 

towing activity, the results of the 

modeled distance to the 120 dB 

threshold for both stationary and mobile 

tug use are presented in Table 9 below. 

The average of these distances was used 

for calculation of estimated exposure to 

Level B harassment (3,850 m). 

The locations used in the stationary 

and mobile source models are depicted 

in Figure 2 below. 


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Federal Register / Vol. 87, No. 89 / Monday, May 9, 2022 / Notices 27615 

The outputs of the mobile and 

stationary models as distances to the 

relevant threshold (in meters) are 

presented below in Tables 7–9. 


khammond on DSKJM1Z7X2PROD with NOTICESEN09MY22.031</GPH>

Onshore HI\K fociities 

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Cook Inlet, Alaska 

Modeled Sound Source Locations 

in the Hilcorp Action Area 

1.lWO'll'W 

NAO_ 1963_UTM_Zone_5N 

0 1 2 3 4 5 Miles 

I I I I II 

Figure 2. Locations Used for Stationary and Mobile Isopleth Models 
27616 Federal Register / Vol. 87, No. 89 / Monday, May 9, 2022 / Notices 

TABLE 7—AVERAGE DISTANCES TO PTS THRESHOLDS FOR STATIONARY ACTIVITY

Location Season 

Average distances (m) to PTS threshold by functional hearing group 

LF MF HF PW OW 

Trading Bay ......................... May ..................................... 100 72 716 59 ........................

Trading Bay ......................... July ..................................... 122 73 697 63 ........................

Trading Bay ......................... October ............................... 98 72 694 59 ........................

Middle Cook Inlet ................ May ..................................... 83 83 643 77 ........................

Middle Cook Inlet ................ July ..................................... 89 85 664 78 ........................

Middle Cook Inlet ................ October ............................... 80 84 661 78 ........................

Average ........................ ............................................. 95 78 679 69 0 

TABLE 8—AVERAGE DISTANCES TO PTS THRESHOLDS FOR MOBILE ACTIVITY

Location Season 

Average distances (m) to PTS threshold by functional hearing group 

LF MF HF PW OW 

M2 ....................................... May ..................................... ........................ ........................ 10 ........................ ........................

M2 ....................................... July ..................................... ........................ ........................ 5 ........................ ........................

M2 ....................................... October ............................... ........................ ........................ 10 ........................ ........................

M11 ..................................... May ..................................... ........................ ........................ 10 ........................ ........................

M11 ..................................... July ..................................... ........................ ........................ 5 ........................ ........................

M11 ..................................... October ............................... ........................ ........................ 10 ........................ ........................

M22 ..................................... May ..................................... ........................ ........................ 10 ........................ ........................

M22 ..................................... July ..................................... ........................ ........................ 5 ........................ ........................

M22 ..................................... October ............................... ........................ ........................ 10 ........................ ........................

Average ........................ ............................................. 0 0 8 0 0 

TABLE 9—AVERAGE DISTANCES TO LEVEL B THRESHOLD (STATIONARY AND MOBILE) 

[120 dB] 

Waypoint 

Average distance to 120 dB threshold 

(m) 

Season average 

distance to 

threshold 

May July October (m) 

M1 .......................................................................................................................... 4,215 3,911 4,352 4,159 

M2 .......................................................................................................................... 3,946 3,841 4,350 4,046 

M3 .......................................................................................................................... 4,156 3,971 4,458 4,195 

M4 .......................................................................................................................... 4,040 3,844 4,364 4,083 

M5 .......................................................................................................................... 4,053 3,676 4,304 4,011 

M6 .......................................................................................................................... 3,716 3,445 3,554 3,572 

M7 .......................................................................................................................... 2,947 2,753 2,898 2,866 

M8 .......................................................................................................................... 3,270 3,008 3,247 3,175 

M9 .......................................................................................................................... 3,567 3,359 3,727 3,551 

M10 ........................................................................................................................ 3,600 3,487 3,691 3,593 

M11 ........................................................................................................................ 3,746 3,579 4,214 3,846 

M12 ........................................................................................................................ 3,815 3,600 3,995 3,803 

M13 ........................................................................................................................ 4,010 3,831 4,338 4,060 

M14 ........................................................................................................................ 3,837 3,647 4,217 3,900 

M15 ........................................................................................................................ 3,966 3,798 4,455 4,073 

M16 ........................................................................................................................ 3,873 3,676 4,504 4,018 

M18 ........................................................................................................................ 5,562 3,893 4,626 4,694 

M20 ........................................................................................................................ 5,044 3,692 4,320 4,352 

M22 ........................................................................................................................ 4,717 3,553 4,067 4,112 

M24 ........................................................................................................................ 4,456 3,384 4,182 4,007 

M25 ........................................................................................................................ 3,842 3,686 4,218 3,915 

M26 ........................................................................................................................ 3,690 3,400 3,801 3,630 

M27 ........................................................................................................................ 3,707 3,497 3,711 3,638 

M28 ........................................................................................................................ 3,546 3,271 3,480 3,432 

M29 ........................................................................................................................ 3,618 3,279 3,646 3,514 

Average .......................................................................................................... 3,958 3,563 4,029 3,850 

Marine Mammal Occurrence 

In this section we provide the 

information about the presence, density, 

or group dynamics of marine mammals 

that will inform the take calculations. 

Densities for marine mammals in 

Cook Inlet were derived from MML 

aerial surveys, typically flown in June, 


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Federal Register / Vol. 87, No. 89 / Monday, May 9, 2022 / Notices 27617 

from 2000 to 2018 (Rugh et al. 2005; 

Shelden et al. 2013, 2015, 2017, 2019). 

A survey was also conducted in 2021 

but density information is not yet 

available. While the surveys are 

concentrated for a few days in June 

annually, which may skew densities for 

seasonally present species, they are still 

the best available long-term dataset of 

marine mammal sightings available in 

Cook Inlet. Density was calculated by 

summing the total number of animals 

observed and dividing the number 

sighted by the area surveyed. The total 

number of animals observed accounts 

for both lower and upper Cook Inlet. 

There are no density estimates available 

for California sea lions in Cook Inlet, as 

they are so infrequently sighted. 

Densities are presented in Table 10 

below. 

TABLE 10—DENSITIES OF MARINE

MAMMALS IN COOK INLET

Species Density 

(indiv/km2) 

Humpback whale ...................... 0.001770 

Minke whale .............................. 0.000009 

Gray whale ............................... 0.000075 

Fin whale .................................. 0.000311 

Killer whale ............................... 0.000601 

Beluga whale (MML lower CI) .. 0.000023 

Beluga whale (MML middle CI) 0.001110 

Goetz beluga—LCI ................... 0.011106 

Goetz beluga—NCI .................. 0.001664 

Goetz beluga—TB .................... 0.015053 

Dall’s porpoise .......................... 0.000154 

Harbor porpoise ........................ 0.004386 

Harbor seal ............................... 0.241401 

Steller sea lion .......................... 0.007609 

California sea lion ..................... 0.000000 

For beluga whales, two densities were 

considered as a comparison of available 

data. The first source considered was 

directly from the MML aerial surveys, as 

described above. Sighting data collected 

during aerial surveys is collected and 

then several correction factors are 

applied to address perception, 

availability, and proximity bias. These 

corrected sightings totals are then 

divided by the total area covered during 

the survey to arrive at a density value. 

Densities were derived for the entirety 

of Cook Inlet as well as for middle and 

lower Cook Inlet. Densities across all 

three regions are low and there is a 

known effect of seasonality on the 

distribution of the whales. Thus, 

densities derived directly from surveys 

flown in June might underestimate the 

density of beluga whales in lower Cook 

Inlet at other ice-free times of the year. 

The other mechanism for arriving at 

beluga whale density considered here is 

the Goetz et al. (2012) habitat-based 

model. 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 beluga density 

map of Cook Inlet, which predicts 

spatially explicit density estimates for 

Cook Inlet belugas. Using the resulting 

grid densities, average densities were 

calculated for two regions applicable to 

Hilcorp’s operations. The densities 

applicable to the area of activity (i.e., the 

North Cook Inlet Unit density for 

middle Cook Inlet activities and the 

Trading Bay density for activities in 

Trading Bay) are provided in Table 11 

below and were carried forward to the 

exposure estimates. Likewise, when a 

range is given, the higher end of the 

range was used out of caution to 

calculate exposure estimates (i.e., 

Trading Bay in the Goetz model has a 

range of 0.004453 to 0.015053; 0.015053 

was used for the exposure estimates). 

TABLE 11—COOK INLET BELUGA

WHALE DENSITIES BASED ON GOETZ

et al. (2012) HABITAT MODEL

Project location 

Beluga whale 

density 

(ind/km2) 

North Cook Inlet Unit (middle 

Cook Inlet) ......................... 0.001664 

Trading Bay Area ................. 0.004453– 

0.015053 

Take Calculation and Estimation 

Here we describe how the information 

provided above is brought together to 

produce a quantitative take estimate for 

each of the two IHAs. 

Year 1 IHA—As described above, 

Hilcorp’s tug towing rig activity was 

divided into two portions for the 

purpose of take estimation: Stationary 

and mobile activity. For stationary 

activity, five hours of sound production 

per day was assumed for up to 16 days 

(eight moves or segments consisting of 

two days each). For the mobile portion 

of the activity, two days of nine hours 

of mobile activity (assuming a source 

velocity of 2.06 m/s) and six days of six 

hours of mobile activity were assumed, 

for a total of eight rig moves. 

Year 2 IHA—For stationary activity, 5 

hours of sound production per day was 

assumed for up to 16 days. For mobile 

activity, 9 hours of sound production 

was assumed for 2 days, as well as 6 

hours of sound production for 6 days, 

for a total of eight rig moves. 

The ensonified areas calculated per 

activity type (stationary and mobile) for 

a single day were multiplied by marine 

mammal densities to get an estimate of 

exposures per day. This was then 

multiplied by the number of days of that 

type of activity (stationary or mobile) to 

arrive at the number of estimated 

exposures per year per activity type. 

These exposures by activity type were 

then summed to result in a number of 

exposures per year for all tug towing rig 

activity. The estimated exposures are 

provided below in Tables 12 and 13 for 

Year 1 and Year 2 of activity, 

respectively. The calculated exposures 

for Years 1 and 2 are identical, as the 

number of days and hours of expected 

tug noise is ultimately the same despite 

the different divisions of the activity 

(e.g. Year 1 has tug noise from P&A, 

Year 2 does not have P&A but has more 

overall tugging trips). There are two 

estimates for beluga whales provided in 

the tables below to demonstrate the 

difference in the calculations based on 

the chosen density value. As exposure 

estimates were calculated based on 

specific potential rig moves or well 

locations, the density value for beluga 

whales that was carried through the 

estimate was the higher density value 

for that particular location. There are no 

estimated exposures based on this 

method of calculation for California sea 

lions because the assumed density is 

0.00 animals/km2. 

TABLE 12—TOTAL CALCULATED EXPOSURES FOR YEAR 1 

Group Species Level A Level B 

LF Cetaceans ............................................................... Humpback whale .......................................................... 0.000 4.058 

Minke whale .................................................................. 0.000 0.021 

Gray whale ................................................................... 0.000 0.171 

Fin whale ...................................................................... 0.000 0.712 

MF Cetaceans .............................................................. Killer whale ................................................................... 0.000 1.379 

Beluga whale NMFS ..................................................... 0.000 2.545 

Beluga whale Goetz ..................................................... 0.000 10.345 


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TABLE 12—TOTAL CALCULATED EXPOSURES FOR YEAR 1—Continued 

Group Species Level A Level B 

HF Cetaceans ............................................................... Dall’s porpoise .............................................................. 0.001 0.353 

Harbor porpoise ............................................................ 0.038 10.057 

Phocids ......................................................................... Harbor seal ................................................................... 0.012 553.565 

Otariids ......................................................................... Steller sea lion .............................................................. 0.000 17.448 

California sea lion ......................................................... 0.000 0.000 

TABLE 13—TOTAL CALCULATED EXPOSURES FOR YEAR 2 

Group Species Level A Level B 

LF Cetaceans ............................................................... Humpback whale .......................................................... 0.000 4.058 

Minke whale .................................................................. 0.000 0.021 

Gray whale ................................................................... 0.000 0.171 

Fin whale ...................................................................... 0.000 0.712 

MF Cetaceans .............................................................. Killer whale ................................................................... 0.000 1.379 

Beluga whale NMFS ..................................................... 0.000 2.545 

Beluga whale Goetz ..................................................... 0.000 11.651 

HF Cetaceans ............................................................... Dall’s porpoise .............................................................. 0.001 0.353 

Harbor porpoise ............................................................ 0.038 10.057 

Phocids ......................................................................... Harbor seal ................................................................... 0.012 553.565 

Otariids ......................................................................... Steller sea lion .............................................................. 0.000 17.448 

California sea lion ......................................................... 0.000 0.000 

Based on the analysis described 

above, NMFS does not propose to 

authorize take via Level A harassment 

related to Hilcorp’s tug towing drill rig 

activity. For mobile tugging, the 

distances to the PTS thresholds for high 

frequency cetaceans (the only functional 

hearing group of concern based on the 

model results) are smaller than the 

overall size of the tug and rig 

configuration, making it unlikely a 

cetacean would remain close enough to 

the tug engines to incur PTS. For 

stationary positioning of the jack up rig, 

the PTS isopleths are up to 679 m for 

high frequency cetaceans, but calculated 

on the assumption that an animal would 

remain within several hundred meters 

of the jack-up rig for the full five hours 

of noise-producing activity. Given the 

location of the activity is not in an area 

known to be essential habitat for any 

marine mammal species with extreme 

site fidelity over the course of two days, 

the occurrence of PTS is unlikely. A 

table indicating the number of takes, by 

Level B harassment, proposed to be 

authorized is provided below. 

TABLE 14—TAKES (BY LEVEL B HARASSMENT) CALCULATED AND PROPOSED TO BE AUTHORIZED FOR YEAR 1 IHA AND

YEAR 2 IHA 

Year 1 

calculated 

Year 1 

authorized 

Year 2 

calculated 

Year 2 

authorized 

Humpback whale ............................................................................................. 4.058 6 4.058 6 

Minke whale ..................................................................................................... 0.021 6 0.021 6

Gray whale ....................................................................................................... 0.171 2 0.171 2 

Fin whale ......................................................................................................... 0.712 4 0.712 4 

Killer whale ...................................................................................................... 1.379 10 1.379 10 

Beluga whale ................................................................................................... 2.545 (MML) 

10.345 (Goetz) 

22 2.545 (MML) 

11.651 (Goetz) 

22 

Dall’s porpoise ................................................................................................. 0.353 6 0.353 6

Harbor porpoise ............................................................................................... 10.057 44 10.057 44 

Harbor seal ...................................................................................................... 553.565 554 553.565 554 

Steller sea lion ................................................................................................. 17.448 17 17.448 17 

California sea lion ............................................................................................ 0 2 0 2 

As illustrated by the table above, the 

estimated exposures for several species 

are less than one. While uncommon, 

these species have been previously 

sighted in Cook Inlet and some are 

unlikely to appear as solitary 

individuals when sighted. For 

humpback whales, the number of takes 

proposed to be authorized is increased 

from the calculated estimate of four to 

six individuals. There were two 

sightings of three humpback whales 

observed near Ladd Landing north of 

the Forelands during the Harvest Alaska 

CIPL project (Sitkiewicz et al. 2018). 

Based on documented observations 

during the CIPL survey (the survey 

nearest the Action Area), Hilcorp is 

requesting six takes of humpback 

whales to allow for up to two sightings 

of three individuals, consistent with 

what was observed during the CIPL 

project. Minke whale takes proposed to 

be authorized are increased from the 

calculated less than one individual to 

five. Minke whales are commonly 

sighted in groups of two or three, as 

well as sightings of individuals. There 

were eight sightings of eight minke 

whales observed during the 2019 

Hilcorp lower Cook Inlet seismic survey 

(Fairweather Science 2020). As the 

occurrence of minke whales is expected 

to be less in middle Cook Inlet than 

lower Cook Inlet and considering the 

observed group sizes, Hilcorp is 


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requesting six takes of minke whale to 

allow for the possibility of two sightings 

of a group of three individuals. During 

Apache’s 2012 seismic program, nine 

gray whales were observed in June and 

July (Lomac-MacNair et al. 2013). 

During Apache’s seismic program in 

2014, one gray whale was observed 

(Lomac-MacNair et al. 2014). During 

SAExploration’s seismic survey in 2015, 

the 2018 CIPL project, and Hilcorp’s 

2019 seismic survey, no gray whales 

were observed (Kendall et al. 2015; 

Sitkiewicz et al. 2018; Fairweather 

Science 2020). Considering the Action 

Area is in middle Cook Inlet where 

sightings of gray whales are less 

common, Hilcorp is requesting two 

takes of gray whales to allow for the 

potential occurrence of two individual 

gray whales. The number of fin whale 

takes proposed to be authorized is 

increased from one to four individuals, 

as they may be seen in groups of two to 

seven individuals. 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). A total authorized take of 

four fin whales would account for two 

sightings of two animals, which is the 

lower end of the range of common group 

size. 

The number of proposed killer whale 

takes is increased to ten from the 

calculated exposure of one. Killer 

whales are typically sighted in pods of 

a few animals to 20 or more (NOAA 

2022b). During seismic surveys 

conducted in 2019 by Hilcorp in the 

lower Cook Inlet, 21 killer whales were 

observed, either as single individuals or 

in groups ranging in size from two to 

five individuals (Fairweather 2020). 

Based on documented sightings, Hilcorp 

requests ten takes of killer whales to 

allow for two sightings with a group size 

of five individuals. Depending on the 

density data used for each activity, the 

estimated annual exposures for beluga 

whales is three to 10 animals. The 

proposed number of takes to be 

authorized for beluga whales is 22 

animals to allow for the possibility that 

more than one observation of typical 

Cook Inlet beluga groups occurs. 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 (two to 147 whales) as was the 

case in previous survey years (Boyd et 

al. 2019). Additionally, vessel-based 

surveys in 2019 observed beluga whale 

groups in the Susitna River Delta 

(roughly 24 km [15 miles] north of the 

Tyonek Platform) that ranged from 5 to 

200 animals (McGuire et al. 2021). The 

very large groups seen in the Susitna 

River Delta are not expected near 

Hilcorp’s platforms, 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. The number of Dall’s porpoise 

takes proposed to be authorized is 

increased from less than one estimated 

individual to six. Dall’s porpoises are 

usually found in groups averaging 

between two and 12 individuals (NOAA 

2022c). During seismic surveys 

conducted in 2019 by Hilcorp in the 

lower Cook Inlet, Dall’s porpoises were 

recorded in groups ranging in size from 

two to seven individuals (Fairweather 

2020). The 2012 Apache survey 

recorded two groups of three individual 

Dall’s porpoises (Lomac-MacNair 2014). 

Because occurrence of Dall’s porpoise is 

anticipated to be less in middle Cook 

Inlet than lower Cook Inlet, the smaller 

end of documented group sizes (three 

individuals) is used, and Hilcorp 

requests six takes of Dall’s porpoise to 

allow for two sightings of three 

individuals similar to the numbers 

observed during the 2012 Apache 

survey. Harbor porpoise takes are 

proposed to be increased from an 

estimated 10 takes to 44 takes. Shelden 

et al. (2014) compiled historical 

sightings of harbor porpoises from lower 

to upper Cook Inlet that spanned from 

a few animals to 92 individuals. The 

2018 CIPL project that occurred just 

north of the Action Area in Cook Inlet 

reported 29 sightings of 44 individuals 

(Sitkiewicz et al. 2018). While the 

duration of days that the tugs are towing 

a jack-up rig will be less than the CIPL 

project, given the increase in sightings 

of harbor porpoise in recent years and 

the inability to shut down the tugs, 

Hilcorp request 44 takes of harbor 

porpoise, commensurate with the 

number observed in the nearby CIPL 

project. 

Calculated take of California sea lions 

was zero because the assumed density 

in Cook Inlet is zero. Any potential 

sightings would likely be of lone out of 

habitat individuals. Two solitary 

individuals were seen during the 2012 

Apache seismic survey in Cook Inlet 

(Lomac-MacNair et al. 2013). Two takes 

are requested based on the potential that 

two lone animals could be sighted over 

a year of work, as was seen during 

Apache’s year of work. 

Proposed Mitigation 

In order to issue an IHA under section 

101(a)(5)(D) of the MMPA, NMFS must 

set forth the permissible methods of 

taking pursuant to the activity, and 

other means of effecting the least 

practicable impact on the species or 

stock and its habitat, paying particular 

attention to rookeries, mating grounds, 

and areas of similar significance, and on 

the availability of the species or stock 

for taking for certain subsistence uses. 

NMFS regulations require applicants for 

incidental take authorizations to include 

information about the availability and 

feasibility (economic and technological) 

of equipment, methods, and manner of 

conducting the activity or other means 

of effecting the least practicable adverse 

impact upon the affected species or 

stocks and their habitat (50 CFR 

216.104(a)(11)). 

In evaluating how mitigation may or 

may not be appropriate to ensure the 

least practicable adverse impact on 

species or stocks and their habitat, as 

well as subsistence uses where 

applicable, we carefully consider two 

primary factors: 

(1) The manner in which, and the 

degree to which, the successful 

implementation of the measure(s) is 

expected to reduce impacts to marine 

mammals, marine mammal species or 

stocks, and their habitat, as well as 

subsistence uses. This considers the 

nature of the potential adverse impact 

being mitigated (likelihood, scope, 

range). It further considers the 

likelihood that the measure will be 

effective if implemented (probability of 

accomplishing the mitigating result if 

implemented as planned), the 

likelihood of effective implementation 

(probability implemented as planned), 

and; 

(2) The practicability of the measures 

for applicant implementation, which 

may consider such things as cost, 

impact on operations, and, in the case 

of a military readiness activity, 

personnel safety, practicality of 

implementation, and impact on the 

effectiveness of the military readiness 

activity. 

Mitigation for Marine Mammals and 

Their Habitat 

NMFS anticipates the project, in both 

of the two IHAs, will create an acoustic 

footprint above ambient sound levels of 

approximately 45 km2 around the tugs 

positioning the jack-up rig or for 

approximately 7 km in all directions 

along a towing trajectory of 

approximately 37km. There is a 


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27620 Federal Register / Vol. 87, No. 89 / Monday, May 9, 2022 / Notices 

discountable potential for marine 

mammals to incur PTS from the project, 

as source levels are relatively low, nonimpulsive, and animals would have to 

remain at very close distances for 

multiple hours to accumulate acoustic 

energy at levels that could damage 

hearing. Therefore, we do not believe 

there is potential for Level A harassment 

and there is no designated shut-down/ 

exclusion zone proposed for this 

project. However, Hilcorp will 

implement a number of mitigation 

measures designed to reduce the 

potential for and severity of Level B 

harassment and minimize the acoustic 

footprint of the project. 

The tugs towing a jack-up rig are not 

able to shutdown while transiting or 

positioning the rig. Hilcorp will 

maneuver the tugs towing the jack-up 

rig such that they maintain a consistent 

speed (approximately 4 knots) and 

avoid multiple changes of speed and 

direction to make the course of the 

vessels as predictable as possible to 

marine mammals in the surrounding 

environment, characteristics that are 

expected to be associated with a lower 

likelihood of disturbance. Hilcorp 

proposes to implement a clearance zone 

of 1,500 meters around the centerpoint 

of the three tug configuration and will 

employ two NMFS-approved protected 

species observers (PSOs) to conduct 

marine mammal monitoring for all 

mobile and stationary activity involving 

tugs towing attached to the jack-up rig. 

Prior to commencing activities during 

daylight hours or if there is a 30-minute 

lapse in operational activities, the PSOs 

will monitor the clearance zone for 

marine mammals for 30 minutes. If no 

marine mammals are observed, 

operations may commence. If a marine 

mammal(s) is observed within the 

clearance zone during the clearing, the 

PSOs will continue to watch until 

either: (1) The animal(s) is outside of 

and on a path away from the clearance 

zone; or (2) 15 minutes have elapsed if 

the species was a pinniped or small 

cetacean, or 30 minutes for large 

cetaceans whales. Once the PSOs have 

determined one of those conditions are 

met, operations may commence. 

Should a marine mammal be observed 

during towing or positioning, the PSOs 

will monitor and carefully record any 

reactions observed until the jack-up rig 

has reached its intended position. No 

new operational activities would be 

started until the animal leaves the area. 

PSOs will also collect behavioral 

information on marine mammals 

sighted during monitoring efforts. 

Hilcorp will make every effort to 

operate with the tide, resulting in a low 

power output from the tugs towing the 

jack-up rig. If human safety or 

equipment integrity is at risk, Hilcorp 

may necessarily operate in an 

unfavorable tidal state. Due to the 

nature of tidal cycles in Cook Inlet, it is 

possible the most favorable tide for the 

towing operation will occur during 

nighttime hours. Hilcorp will operate 

the tugs towing the jack-up rigs at night 

if the nighttime operations result in a 

lower power output from the tugs by 

operating with a favorable tide. 

In low-light conditions, night-vision 

devices shown to be effective at 

detecting marine mammals in low-light 

conditions (e.g., Armasight by FLIR 

Command Pro®, or similar) will be 

provided to PSOs to aid in low-light 

visibility. Every effort will be made to 

observe that the clearance zone is free 

of marine mammals by using nightvision devices, however it may not 

always be possible to see and clear the 

entire clearance zone prior to nighttime 

transport. PSOs will monitor the 

greatest extent feasible for 30 minutes 

immediately prior to the start of load 

bearing activities. If no marine 

mammals are observed, operations may 

commence. If a marine mammal is 

observed within the during the clearing, 

the PSOs will continue to watch until 

either: (1) The animal(s) is outside of 

and on a path away from the clearance 

zone; or (2) 15 minutes have elapsed if 

the species was a pinniped or small 

cetacean, or 30 minutes for large 

cetaceans whales. Once the PSOs have 

determined one of those conditions are 

met, operations may commence. 

Out of concern for potential 

disturbance to Cook Inlet beluga whales 

in sensitive and essential habitat, 

Hilcorp will not conduct noiseproducing activity within 16 km (10 

miles) of the mean high-high water line 

of the Susitna River Delta (Beluga River 

to the Little Susitna River) between 

April 15 and October 15. 

Based on our evaluation of the 

applicant’s proposed measures, for both 

IHAs, NMFS has preliminarily 

determined that the proposed mitigation 

measures provide the means of effecting 

the least practicable impact on the 

affected species or stocks and their 

habitat, paying particular attention to 

rookeries, mating grounds, and areas of 

similar significance and on the 

availability of such species or stock for 

subsistence uses. 

Proposed Monitoring and Reporting 

In order to issue an IHA for an 

activity, section 101(a)(5)(D) of the 

MMPA states that NMFS must set forth 

requirements pertaining to the 

monitoring and reporting of such taking. 

The MMPA implementing regulations at 

50 CFR 216.104(a)(13) indicate that 

requests for authorizations must include 

the suggested means of accomplishing 

the necessary monitoring and reporting 

that will result in increased knowledge 

of the species and of the level of taking 

or impacts on populations of marine 

mammals that are expected to be 

present in the proposed action area. 

Effective reporting is critical both to 

compliance as well as ensuring that the 

most value is obtained from the required 

monitoring. 

Monitoring and reporting 

requirements prescribed by NMFS 

should contribute to improved 

understanding of one or more of the 

following: 

• Occurrence of marine mammal 

species or stocks in the area in which 

take is anticipated (e.g., presence, 

abundance, distribution, density). 

• Nature, scope, or context of likely 

marine mammal exposure to potential 

stressors/impacts (individual or 

cumulative, acute or chronic), through 

better understanding of: (1) Action or 

environment (e.g., source 

characterization, propagation, ambient 

noise); (2) affected species (e.g., life 

history, dive patterns); (3) co-occurrence 

of marine mammal species with the 

action; or (4) biological or behavioral 

context of exposure (e.g., age, calving or 

feeding areas). 

• Individual marine mammal 

responses (behavioral or physiological) 

to acoustic stressors (acute, chronic, or 

cumulative), other stressors, or 

cumulative impacts from multiple 

stressors. 

• How anticipated responses to 

stressors impact either: (1) Long-term 

fitness and survival of individual 

marine mammals; or (2) populations, 

species, or stocks. 

• Effects on marine mammal habitat 

(e.g., marine mammal prey species, 

acoustic habitat, or other important 

physical components of marine 

mammal habitat). 

• Mitigation and monitoring 

effectiveness. 

Hilcorp will abide by all monitoring 

and reporting measures contained 

within their Marine Mammal 

Monitoring and Mitigation Plan, dated 

February 25, 2022. A summary of those 

measures and additional requirements 

proposed by NMFS is provided below. 

A minimum of two NMFS-approved 

PSOs will be on-watch during all 

activities wherein the jack-up rig is 

attached to the tugs for the duration of 

the project. Minimum requirements for 

a PSO include: 

(a) Visual acuity in both eyes 

(correction is permissible) sufficient for 

discernment of moving targets at the 


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water’s surface with ability to estimate 

target size and distance; use of 

binoculars may be necessary to correctly 

identify the target; 

(b) Advanced education in biological 

science or related field (undergraduate 

degree or higher required); 

(c) Experience and ability to conduct 

field observations and collect data 

according to assigned protocols (this 

may include academic experience); 

(d) Experience or training in the field 

identification of marine mammals, 

including the identification of 

behaviors; 

(e) Sufficient training, orientation, or 

experience with the construction 

operation to provide for personal safety 

during observations; 

(f) Writing skills sufficient to prepare 

a report of observations including but 

not limited to the number and species 

of marine mammals observed; dates and 

times when in-water construction 

activities were conducted; dates and 

times when in-water construction 

activities were suspended to avoid 

potential incidental injury from 

construction sound of marine mammals 

observed within a defined shutdown 

zone; and marine mammal behavior; 

and 

(g) Ability to communicate orally, by 

radio or in person, with project 

personnel to provide real-time 

information on marine mammals 

observed in the area as necessary. 

PSOs will be stationed aboard a tug or 

the jack-up rig, work in shifts lasting no 

more than four hours without a 

minimum of a one hour break, and will 

not be on-watch for more than 12 hours 

within a 24-hour period. 

Hilcorp will submit monthly reports 

for all months in which tugs towing or 

positioning the jack-up rig occurs. A 

draft marine mammal monitoring report 

would be submitted to NMFS within 90 

days after the completion of the tug 

towing jack-up rig activities for the year. 

It will include an overall description of 

work completed, a narrative regarding 

marine mammal sightings, and 

associated marine mammal observation 

data sheets. Specifically, the report must 

include: 

• Date and time that monitored 

activity begins or ends; 

• Construction activities occurring 

during each observation period; 

• Weather parameters (e.g., percent 

cover, visibility); 

• Water conditions (e.g., sea state, 

tide state); 

• Species, numbers, and, if possible, 

sex and age class of marine mammals; 

• Description of any observable 

marine mammal behavior patterns, 

including bearing and direction of travel 

and distance from pile driving activity; 

• Distance from pile driving activities 

to marine mammals and distance from 

the marine mammals to the observation 

point; 

• Locations of all marine mammal 

observations; and 

• Other human activity in the area. 

If no comments are received from 

NMFS within 30 days, the draft final 

report will constitute the final report. If 

NMFS submits comments, Hilcorp will 

submit a final report addressing NMFS 

comments within 30 days after receipt 

of comments. 

In the unanticipated event that the 

specified activity clearly causes the take 

of a marine mammal in a manner 

prohibited by the IHAs (if issued), such 

as an injury, serious injury or mortality, 

Hilcorp would immediately cease the 

specified activities and report the 

incident to the Chief of the Permits and 

Conservation Division, Office of 

Protected Resources, NMFS, and the 

Alaska Regional Stranding Coordinator. 

The report would include the following 

information: 

• Description of the incident; 

• Environmental conditions (e.g., 

Beaufort sea state, visibility); 

• Description of all marine mammal 

observations in the 24 hours preceding 

the incident; 

• Species identification or 

description of the animal(s) involved; 

• Fate of the animal(s); and 

• Photographs or video footage of the 

animal(s) (if equipment is available). 

Activities would not resume until 

NMFS is able to review the 

circumstances of the prohibited take. 

NMFS would work with Hilcorp to 

determine what is necessary to 

minimize the likelihood of further 

prohibited take and ensure MMPA 

compliance. Hilcorp would not be able 

to resume their activities until notified 

by NMFS via letter, email, or telephone. 

In the event that Hilcorp discovers an 

injured or dead marine mammal, and 

the lead PSO determines that the cause 

of the injury or death is unknown and 

the death is relatively recent (e.g., in 

less than a moderate state of 

decomposition as described in the next 

paragraph), Hilcorp would immediately 

report the incident to the Chief of the 

Permits and Conservation Division, 

Office of Protected Resources, NMFS, 

and the NMFS Alaska Stranding Hotline 

and/or by email to the Alaska Regional 

Stranding Coordinator. The report 

would include the same information 

identified in the paragraph above. 

Activities would be able to continue 

while NMFS reviews the circumstances 

of the incident. NMFS would work with 

Hilcorp to determine whether 

modifications in the activities are 

appropriate. 

In the event that Hilcorp discovers an 

injured or dead marine mammal and the 

lead PSO determines that the injury or 

death is not associated with or related 

to the activities authorized in the IHAs 

(e.g., previously wounded animal, 

carcass with moderate to advanced 

decomposition, or scavenger damage), 

Hilcorp would report the incident to the 

Chief of the Permits and Conservation 

Division, Office of Protected Resources, 

NMFS, and the NMFS Alaska Stranding 

Hotline and/or by email to the Alaska 

Regional Stranding Coordinator, within 

24 hours of the discovery. Hilcorp 

would provide photographs or video 

footage (if available) or other 

documentation of the stranded animal 

sighting to NMFS and the Marine 

Mammal Stranding Network. 

Negligible Impact Analysis and 

Determination 

NMFS has defined negligible impact 

as an impact resulting from the 

specified activity that cannot be 

reasonably expected to, and is not 

reasonably likely to, adversely affect the 

species or stock through effects on 

annual rates of recruitment or survival 

(50 CFR 216.103). A negligible impact 

finding is based on the lack of likely 

adverse effects on annual rates of 

recruitment or survival (i.e., populationlevel effects). An estimate of the number 

of takes alone is not enough information 

on which to base an impact 

determination. In addition to 

considering estimates of the number of 

marine mammals that might be ‘‘taken’’ 

through harassment, NMFS considers 

other factors, such as the likely nature 

of any impacts or responses (e.g., 

intensity, duration), the context of any 

impacts or responses (e.g., critical 

reproductive time or location, foraging 

impacts affecting energetics), as well as 

effects on habitat, and the likely 

effectiveness of the mitigation. We also 

assess the number, intensity, and 

context of estimated takes by evaluating 

this information relative to population 

status. Consistent with the 1989 

preamble for NMFS’ implementing 

regulations (54 FR 40338; September 29, 

1989), the impacts from other past and 

ongoing anthropogenic activities are 

incorporated into this analysis via their 

impacts on the baseline (e.g., as 

reflected in the regulatory status of the 

species, population size and growth rate 

where known, ongoing sources of 

human-caused mortality, or ambient 

noise levels). 

To avoid repetition, the discussion of 

our analysis applies to all the species 


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listed in Table 15, given that the 

anticipated effects of this activity on 

these different marine mammal stocks 

are expected to be similar. There is little 

information about the nature or severity 

of the impacts, or the size, status, or 

structure of any of these species or 

stocks that would lead to a different 

analysis for this activity. 

To avoid repetition, this introductory 

section of our analysis applies to all the 

species listed in Table 15, given that 

many of the anticipated effects of this 

project on different marine mammal 

stocks are expected to be relatively 

similar in nature. Where there are 

meaningful differences between species 

or stocks, or groups of species, in 

anticipated individual responses to 

activities, impact of expected take on 

the population due to differences in 

population status, or impacts on habitat, 

they are described independently in the 

analysis below. 

Potential impacts to marine mammal 

habitat were discussed previously in 

this document (see Potential Effects of 

Specified Activities on Marine 

Mammals and their Habitat). Marine 

mammal habitat may be impacted by 

elevated sound levels, but these impacts 

would be temporary. In addition to 

being temporary and short in overall 

duration, the acoustic footprint of both 

years of the proposed activity is small 

relative to the overall distribution of the 

animals in the area and their use of the 

area. Feeding behavior is not likely to be 

significantly impacted, as no areas of 

biological significance for marine 

mammal feeding are known to exist in 

the project area and individual marine 

mammals are not expected to be 

exposed to the noise from the activities 

repeatedly or in long durations. 

The proposed project would create an 

acoustic footprint around the project 

area for a total of sixteen days per year 

from approximately April through 

October. Noise levels within the 

footprint would reach or exceed 120 dB 

rms. We anticipate the 120 dB footprint 

to be limited to no more than 45km2

around the tugs positioning the jackup 

rig or approximately 7 km in all 

directions along a towing trajectory of 

approximately 37 km. The habitat 

within the footprint is not heavily used 

by marine mammals during the project 

time frame (e.g., Cook Inlet beluga 

whale Critical Habitat Area 2, within 

which the activity resulting in the take 

of marine mammals is anticipated to 

potentially occur, is designated for 

beluga fall and winter use) and marine 

mammals are not known to engage in 

critical behaviors associated with this 

portion of Cook Inlet (e.g., no known 

breeding grounds, foraging habitat, etc.). 

Most animals will likely be transiting 

through the area; therefore, exposure 

would be brief. Animals may swim 

around the project area but we do not 

expect them to abandon any intended 

path. We also expect the number of 

animals exposed to be small relative to 

population sizes. Finally, Hilcorp will 

minimize potential exposure of marine 

mammals to elevated noise levels by not 

commencing operational activities if 

marine mammals are observed within 

the immediate starting area. Hilcorp is 

also able to reduce the impact of their 

activity by conducting tugging 

operations with favorable tides 

whenever feasible. In summary and as 

described above, the following factors 

primarily support our preliminary 

determinations that the impacts 

resulting from the activities described 

for these two IHAs are not expected to 

adversely affect the species or stock 

through effects on annual rates of 

recruitment or survival: 

• No mortality is anticipated or 

authorized. 

• The mobile portion of the project 

does not involve noise sources capable 

of inducing PTS in any species other 

than high frequency cetaceans; 

• Exposure would likely be brief 

given transiting behavior of marine 

mammals in the action area; 

• Marine mammal densities are low 

in the project area; therefore, there will 

not be substantial numbers of marine 

mammals exposed to the noise from the 

project compared to the affected 

population sizes; and 

• Hilcorp would monitor for marine 

mammals daily and minimize exposure 

to operational activities. 

Based on the analysis contained 

herein of the likely effects of the 

specified activity on marine mammals 

and their habitat, and taking into 

consideration the implementation of the 

proposed monitoring and mitigation 

measures, NMFS preliminarily finds 

that the total marine mammal take from 

the proposed activity described in the 

Year 1 IHA will have a negligible impact 

on all affected marine mammal species 

or stocks. Also, separately, NMFS 

preliminarily finds that the total marine 

mammal take from the proposed activity 

described in the Year 2 IHA will have 

a negligible impact on all affected 

marine mammal species or stocks. 

Small Numbers 

As noted above, only small numbers 

of incidental take may be authorized 

under sections 101(a)(5)(A) and (D) of 

the MMPA for specified activities other 

than military readiness activities. The 

MMPA does not define small numbers 

and so, in practice, where estimated 

numbers are available, NMFS compares 

the number of individuals taken to the 

most appropriate estimation of 

abundance of the relevant species or 

stock in our determination of whether 

an authorization is limited to small 

numbers of marine mammals. When the 

predicted number of individuals to be 

taken is fewer than one third of the 

species or stock abundance (as it is for 

all stocks in both the Year 1 and Year 

2 IHAs), the take is considered to be of 

small numbers. Additionally, other 

qualitative factors may be considered in 

the analysis, such as the temporal or 

spatial scale of the activities. 

Table 15 provides the quantitative 

analysis informing our small numbers 

determinations for the Year 1 and Year 

2 IHAs. For most species, the amount of 

take proposed represents less than 

approximately two percent of the 

population for each IHA. For beluga 

whales, the amount of take proposed 

represents slightly under eight percent 

of the population for each IHA. 

TABLE 15—PERCENT OF STOCK PROPOSED TO BE TAKEN BY LEVEL B HARASSMENT UNDER EACH IHA 

Species Stock Abundance 

(Nbest) 

Proposed take 

(Level B) 

Percent of 

stock 

Year 1: 

Humpback whale ..................................... Western North Pacific .................................... 11,571 6 0.05 

Minke whale ............................................. Alaska ............................................................. 1,233 6 0.49 

Gray whale ............................................... Eastern Pacific ............................................... 26,960 2 0.01 

Fin whale ................................................. Northeastern Pacific ....................................... 2,554 4 0.16 

Killer whale .............................................. Alaska Resident Gulf of Alaska, Aleutian Islands, and Bering Sea Transient.587 

2,347 

10 1.7 

0.43 

Beluga whale ........................................... Cook Inlet ....................................................... 279 22 7.89 


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TABLE 15—PERCENT OF STOCK PROPOSED TO BE TAKEN BY LEVEL B HARASSMENT UNDER EACH IHA—Continued 

Species Stock Abundance 

(Nbest) 

Proposed take 

(Level B) 

Percent of 

stock 

Dall’s porpoise ......................................... Alaska ............................................................. 83,400 6 0.01 

Harbor porpoise ....................................... Gulf of Alaska ................................................. 31,046 44 0.14 

Harbor seal .............................................. Cook Inlet/Shelikof ......................................... 26,907 554 2.06 

Steller sea lion ......................................... Western .......................................................... 53,624 17 0.03 

California sea lion .................................... U.S. ................................................................ 233,515 5 0.00 

Year 2: 

Humpback whale ..................................... Western North Pacific .................................... 11,571 6 0.05 

Minke whale ............................................. Alaska ............................................................. 1,233 6 0.49 

Gray whale ............................................... Eastern Pacific ............................................... 26,960 2 0.01 

Fin whale ................................................. Northeastern Pacific ....................................... 2,554 4 0.16 

Killer whale .............................................. Alaska Resident Gulf of Alaska, Aleutian Islands, and Bering Sea Transient.587 10 1.7 

0.43 

Beluga whale ........................................... Cook Inlet ....................................................... 279 22 7.89 

Dall’s porpoise ......................................... Alaska ............................................................. 83,400 6 0.01 

Harbor porpoise ....................................... Gulf of Alaska ................................................. 31,046 44 0.14 

Harbor seal .............................................. Cook Inlet/Shelikof ......................................... 26,907 554 2.06 

Steller sea lion ......................................... Western .......................................................... 53,624 17 0.03 

California sea lion .................................... U.S. ................................................................ 233,515 2 0.00 

Based on the analysis contained 

herein of the proposed activity 

(including the proposed mitigation and 

monitoring measures) and the 

anticipated take of marine mammals, 

NMFS preliminarily finds that small 

numbers of marine mammals will be 

taken relative to the population size of 

the affected species or stocks for the 

Year 1 IHA. Separately, NMFS also 

preliminarily finds that small numbers 

of marine mammals will be taken 

relative to the population size of the 

affected species or stocks for the Year 2 

IHA. 

Unmitigable Adverse Impact Analysis 

and Determination 

In order to issue an IHA, NMFS must 

find that the specified activity will not 

have an unmitigable adverse impact on 

the availability of such species or stock 

for taking for subsistence uses by Alaska 

Natives. NMFS has defined 

‘‘unmitigable adverse impact’’ in 50 CFR 

216.103 as an impact resulting from the 

specified activity: (1) That is likely to 

reduce the availability of the species to 

a level insufficient for a harvest to meet 

subsistence needs by: (i) Causing the 

marine mammals to abandon or avoid 

hunting areas; (ii) Directly displacing 

subsistence users; or (iii) Placing 

physical barriers between the marine 

mammals and the subsistence hunters; 

and (2) That cannot be sufficiently 

mitigated by other measures to increase 

the availability of marine mammals to 

allow subsistence needs to be met. 

To further minimize any potential 

effects of their action on subsistence 

activities, Hilcorp has outlined their 

communication plan for engaging with 

subsistence users in their Stakeholder 

Engagement Plan (Appendix B of 

Hilcorp’s application). Hilcorp will be 

required to abide by this plan and 

update the plan accordingly. 

Subsistence communities identified 

as project stakeholders near Hilcorp’s 

middle Cook Inlet and Trading Bay 

activities include the Village of 

Salamatof and the Native Village of 

Tyonek. The ADF&G Community 

Subsistence Information System does 

not contain data for Salamatof. For the 

purposes of our analyses for the Year 1 

and Year 2 IHAs, we can assume the 

subsistence uses are similar to those of 

nearby communities such as Kenai. At 

3.5 km away from the closest point of 

approach, Tyonek is the closest 

subsistence community to Hilcorp’s 

proposed tug route. Tyonek, on the 

western side of lower Cook Inlet, has a 

subsistence harvest area that extends 

from the Susitna River south to Tuxedni 

Bay (BOEM 2016). In Tyonek, harbor 

seals were harvested between June and 

September by 6 percent of the 

households (Jones et al. 2015). Seals 

were harvested in several areas, 

encompassing an area stretching 32.2 

km (20 miles) along the Cook Inlet 

coastline from the McArthur Flats north 

to the Beluga River. Seals were searched 

for or harvested in the Trading Bay areas 

as well as from the beach adjacent to 

Tyonek (Jones et al. 2015). 

Subsistence hunting of whales is not 

known to currently occur in Cook Inlet. 

Hilcorp’s tug towing jack-up rig 

activities may overlap with subsistence 

hunting of seals. However, these 

activities typically occur along the 

shoreline or very close to shore near 

river mouths, whereas most of Hilcorp’s 

tugging is in the middle of the Inlet and 

rarely near the shoreline or river 

mouths. Any harassment to harbor seals 

is anticipated to be short-term, mild, 

and not result in any abandonment or 

behaviors that would make the animals 

unavailable to Alaska Natives. 

Based on the description of the 

specified activity, the measures 

described to minimize adverse effects 

on the availability of marine mammals 

for subsistence purposes, and the 

proposed mitigation and monitoring 

measures, NMFS has preliminarily 

determined that there will not be an 

unmitigable adverse impact on 

subsistence uses from Hilcorp’s’s 

proposed activities under the Year 1 

IHA. Separately, NMFS has also 

preliminarily determined that there will 

not be an unmitigable adverse impact on 

subsistence uses from Hilcorp’s 

proposed activities under the Year 2 

IHA. 

Endangered Species Act 

Section 7(a)(2) of the Endangered 

Species Act of 1973 (ESA; 16 U.S.C. 

1531 et seq.) requires that each Federal 

agency insure that any action it 

authorizes, funds, or carries out is not 

likely to jeopardize the continued 

existence of any endangered or 

threatened species or result in the 

destruction or adverse modification of 

designated critical habitat. To ensure 

ESA compliance for the issuance of 

IHAs, NMFS consults internally 

whenever we propose to authorize take 

for endangered or threatened species, in 

this case with the Alaska Regional 

Protected Resources Division Office. 

NMFS is proposing to authorize take 

of humpback whales (Mexico DPS, 

Western North Pacific DPS), fin whales 

(Northeastern Pacific stock), beluga 

whales (Cook Inlet stock), and Steller 


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27624 Federal Register / Vol. 87, No. 89 / Monday, May 9, 2022 / Notices 

sea lion (Western DPS), which are listed 

under the ESA. 

The Permit and Conservation Division 

has requested initiation of Section 7 

consultation with the NMFS Alaska 

Region for the issuance of these two 

IHAs. NMFS will conclude the ESA 

consultation prior to reaching a 

determination regarding the proposed 

issuance of the authorization. 

Proposed Authorization 

As a result of these preliminary 

determinations, NMFS proposes to issue 

two consecutive IHAs to Hilcorp for its 

tugs towing a jack-up rig in Cook Inlet 

in 2022–2023 and 2023–2024 open 

water seasons, provided the previously 

mentioned mitigation, monitoring, and 

reporting requirements are incorporated. 

Drafts of the proposed IHAs can be 

found at https://www.fisheries.

noaa.gov/permit/incidental-takeauthorizations-under-marine-mammalprotection-act. 

Request for Public Comments 

We request comment on our analyses, 

the proposed authorizations, and any 

other aspect of this notice of proposed 

IHAs for the proposed tug towing jackup rig activity. We also request at this 

time comment on the potential renewal 

of this proposed IHA as described in the 

paragraph below. Please include with 

your comments any supporting data or 

literature citations to help inform 

decisions on the request for this IHA or 

a subsequent Renewal IHA. 

On a case-by-case basis, NMFS may 

issue a one-time, one-year Renewal IHA 

following notice to the public providing 

an additional 15 days for public 

comments when (1) up to another year 

of identical or nearly identical activities 

as described in the Description of 

Proposed Activities section of this 

notice is planned or (2) the activities as 

described in the Description of 

Proposed Activities section of this 

notice would not be completed by the 

time the IHA expires and a renewal 

would allow for completion of the 

activities beyond that described in the 

Dates and Duration section of this 

notice, provided all of the following 

conditions are met: 

• A request for renewal is received no 

later than 60 days prior to the needed 

Renewal IHA effective date (recognizing 

that the Renewal IHA expiration date 

cannot extend beyond one year from 

expiration of the initial IHA). 

• The request for renewal must 

include the following: 

(1) An explanation that the activities 

to be conducted under the requested 

Renewal IHA are identical to the 

activities analyzed under the initial 

IHA, are a subset of the activities, or 

include changes so minor (e.g., 

reduction in pile size) that the changes 

do not affect the previous analyses, 

mitigation and monitoring 

requirements, or take estimates (with 

the exception of reducing the type or 

amount of take). 

(2) A preliminary monitoring report 

showing the results of the required 

monitoring to date and an explanation 

showing that the monitoring results do 

not indicate impacts of a scale or nature 

not previously analyzed or authorized. 

Upon review of the request for 

renewal, the status of the affected 

species or stocks, and any other 

pertinent information, NMFS 

determines that there are no more than 

minor changes in the activities, the 

mitigation and monitoring measures 

will remain the same and appropriate, 

and the findings in the initial IHA 

remain valid. 

Dated: May 4, 2022. 

Kimberly Damon-Randall, 

Acting Director, Office of Protected Resources, 

National Marine Fisheries Service. 

[FR Doc. 2022–09916 Filed 5–6–22; 8:45 am] 

BILLING CODE 3510–22–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XB989] 

Atlantic Coastal Fisheries Cooperative 

Management Act Provisions; General 

Provisions for Domestic Fisheries; 

Application for Exempted Fishing 

Permits 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice; request for comments. 

SUMMARY: The Assistant Regional 

Administrator for Sustainable Fisheries, 

Greater Atlantic Region, NMFS, has 

made a preliminary determination that 

an Exempted Fishing Permit renewal 

application from the Massachusetts 

Division of Marine Fisheries contains all 

of the required information and 

warrants further consideration. 

Regulations under the MagnusonStevens Fishery Conservation and 

Management Act and the Atlantic 

Coastal Fisheries Cooperative 

Management Act require publication of 

this notice to provide interested parties 

the opportunity to comment on 

applications for proposed Exempted 

Fishing Permits. 

DATES: Comments must be received on 

or before May 24, 2022. 

ADDRESSES: You may submit written 

comments by any of the following 

methods: 

• Email: NMFS.GAR.EFP@noaa.gov. 

Include in the subject line ‘‘Comments 

on MA DMF Ventless Trap EFP.’’ If you 

cannot submit a comment through this 

method, please contact Allison Murphy 

at (978) 281–9122, or email at 

allison.murphy@noaa.gov. 

FOR FURTHER INFORMATION CONTACT: 

Allison Murphy, Fishery Policy Analyst, 

978–281–9122, allison.murphy@

noaa.gov. 

SUPPLEMENTARY INFORMATION: The 

Massachusetts Division of Marine 

Fisheries (MA DMF) submitted a 

complete application on April 8, 2022, 

for an Exempted Fishing Permit (EFP) to 

conduct a lobster abundance survey that 

Federal regulations would otherwise 

restrict. The purpose of this study is to 

provide fishery-independent data on 

lobster growth and abundance in 

Massachusetts state waters of statistical 

areas 514 and 538. This EFP would 

authorize up to seven vessels to conduct 

larval sampling in Lobster Conservation 

Management Area 1 and 2. A map of 

this area is available at: https://

www.fisheries.noaa.gov/resource/map/ 

lobster-management-areas. 

For this project, MA DMF is 

requesting exemptions from the 

following Federal lobster regulations: 

1. Gear specification requirements to 

allow for the use of traps without escape 

vents (50 CFR 697.21(c)(1) for Lobster 

Management Area 1 and § 697.21(c)(2) 

for Area 2); 

2. Trap limit requirements to allow for 

trap limits to be exceeded (§ 697.19(a) 

for Area 1 and § 697.19(b) for Lobster 

Management Area 2); 

3. Trap tag requirements to allow for 

alternatively-tagged traps (§ 697.19(i)); 

4. Minimum and maximum carapace 

length requirements to allow sub-legal 

and over-sized lobsters to be landed for 

research purposes (§ 697.20(a)(2) and 

697.20(b)(2) for Area 1, and 

§ 697.20(a)(3) and 697.20(b)(3) for Area 

2); 

5. V-notch possession requirement to 

allow landing of female lobsters for 

research purposes (§ 697.20(g)(1) for 

Area 1 and § 697.20(g)(3) for Area 2); 

6. Berried female possession 

requirement to allow landing of eggbearing female lobsters for research 

purposes (§ 697.20(d)(1)and(3)); 

7. Minimum carapace width 

requirements to allow sub-legal Jonah 

crabs to be landed for research purposes 

(§ 697.20(h)(1)); and 


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