42982 Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 18 

Docket No. FWS–R7–ES–2021–0037; 

FXES111607MRG01–212–FF07CAMM00] 

RIN 1018–BF13 

Marine Mammals; Incidental Take 

During Specified Activities; North 

Slope, Alaska 

AGENCY: Fish and Wildlife Service, 

Interior. 

ACTION: Final rule. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service, in response to a 

request from the Alaska Oil and Gas 

Association, finalize regulations 

authorizing the nonlethal, incidental, 

unintentional take by harassment of 

small numbers of polar bears and Pacific 

walruses during year-round oil and gas 

industry activities in the Beaufort Sea 

(Alaska and the Outer Continental 

Shelf) and adjacent northern coast of 

Alaska. Take may result from oil and gas 

exploration, development, production, 

and transportation activities occurring 

for a period of 5 years. These activities 

are similar to those covered by the 

previous 5-year Beaufort Sea incidental 

take regulations effective from August 5, 

2016, through August 5, 2021. This rule 

authorizes take by harassment only. No 

lethal take is authorized. We will issue 

Letters of Authorization, upon request, 

for specific activities in accordance with 

these regulations. 

DATES: This rule is effective August 5, 

2021, and remains effective through 

August 5, 2026. 

ADDRESSES: You may view this rule, the 

associated final environmental 

assessment and U.S. Fish and Wildlife 

Service finding of no significant impact 

(FONSI), and other supporting material 

at http://www.regulations.gov under 

Docket No. FWS–R7–ES–2021–0037, or 

these documents may be requested as 

described under FOR FURTHER

INFORMATION CONTACT. 

FOR FURTHER INFORMATION CONTACT: 

Marine Mammals Management, U.S. 

Fish and Wildlife Service, 1011 East 

Tudor Road, MS–341, Anchorage, AK 

99503, Telephone 907–786–3844, or 

Email: R7mmmregulatory@fws.gov. 

Persons who use a telecommunications 

device for the deaf (TDD) may call the 

Federal Relay Service (FRS) at 1–800– 

877–8339, 24 hours a day, 7 days a 

week. 

SUPPLEMENTARY INFORMATION: 

Immediate Promulgation 

In accordance with the 

Administrative Procedure Act (APA; 5 

U.S.C. 553(d)(3)), we find that we have 

good cause to make this rule effective 

less than 30 days after publication. 

Immediate promulgation of the rule will 

ensure that the applicant will 

implement mitigation measures and 

monitoring programs in the geographic 

region that reduce the risk of 

harassment of polar bears (Ursus 

maritimus) and Pacific walruses 

(Odobenus rosmarus divergens) by their 

activities. 

Executive Summary 

In accordance with the Marine 

Mammal Protection Act (MMPA) of 

1972, as amended, and its implementing 

regulations, we, the U.S. Fish and 

Wildlife Service (Service or we), finalize 

incidental take regulations (ITRs) that 

authorize the nonlethal, incidental, 

unintentional take of small numbers of 

Pacific walruses and polar bears during 

oil and gas industry (hereafter referred 

to as ‘‘Industry’’) activities in the 

Beaufort Sea and adjacent northern 

coast of Alaska, not including lands 

within the Arctic National Wildlife 

Refuge, for a 5-year period. Industry 

operations include similar types of 

activities covered by the previous 5-year 

Beaufort Sea ITRs effective from August 

5, 2016, through August 5, 2021 (81 FR 

52276). 

This rule is based on our findings that 

the total takings of Pacific walruses 

(walruses) and polar bears during 

Industry activities will impact no more 

than small numbers of animals, will 

have a negligible impact on these 

species or stocks, and will not have an 

unmitigable adverse impact on the 

availability of these species or stocks for 

taking for subsistence uses by Alaska 

Natives. We base our findings on past 

and proposed future monitoring of the 

encounters and interactions between 

these species and Industry; species 

research; oil spill risk assessments; 

potential and documented Industry 

effects on these species; natural history 

and conservation status information of 

these species; and data reported from 

Alaska Native subsistence hunters. We 

have prepared a National Environmental 

Policy Act (NEPA) environmental 

assessment (EA) in conjunction with 

this rulemaking and determined that 

this final action will result in a finding 

of no significant impact (FONSI). 

These regulations include permissible 

methods of nonlethal taking; mitigation 

measures to ensure that Industry 

activities will have the least practicable 

adverse impact on the species or stock, 

their habitat, and their availability for 

subsistence uses; and requirements for 

monitoring and reporting. Compliance 

with this rule is not expected to result 

in significant additional costs to 

Industry, and any costs are minimal in 

comparison to those related to actual oil 

and gas exploration, development, and 

production operations. 

Background 

Section 101(a)(5)(A) of the Marine 

Mammal Protection Act (MMPA; 16 

U.S.C. 1371(a)(5)(A)) gives the Secretary 

of the Interior (Secretary) the authority 

to allow the incidental, but not 

intentional, taking of small numbers of 

marine mammals, in response to 

requests by U.S. citizens (as defined in 

50 CFR 18.27(c)) engaged in a specified 

activity (other than commercial fishing) 

within a specified geographic region. 

The Secretary has delegated authority 

for implementation of the MMPA to the 

U.S. Fish and Wildlife Service. 

According to the MMPA, the Service 

shall allow this incidental taking if we 

find the total of such taking for a 5-year 

period or less: 

(1) Will affect only small numbers of 

marine mammals of a species or 

population stock; 

(2) will have no more than a 

negligible impact on such species or 

stocks; 

(3) will not have an unmitigable 

adverse impact on the availability of 

such species or stocks for taking for 

subsistence use by Alaska Natives; and 

(4) we issue regulations that set forth: 

(a) Permissible methods of taking; 

(b) other means of effecting the least 

practicable adverse impact on the 

species or stock and its habitat, and on 

the availability of such species or stock 

for subsistence uses; and 

(c) requirements for monitoring and 

reporting of such taking. 

If final regulations allowing such 

incidental taking are issued, we may 

then subsequently issue Letters of 

Authorization (LOAs), upon request, to 

authorize incidental take during the 

specified activities. 

The term ‘‘take’’ as defined by the 

MMPA, means to harass, hunt, capture, 

or kill, or attempt to harass, hunt, 

capture, or kill any marine mammal (16 

U.S.C. 1362(13)). Harassment, as 

defined by the MMPA, for activities 

other than military readiness activities 

or scientific research conducted by or 

on behalf of the Federal Government, 

means ‘‘any act of pursuit, torment, or 

annoyance which (i) has the potential to 

injure a marine mammal or marine 

mammal stock in the wild’’ (the MMPA 

defines this as Level A harassment); or 

‘‘(ii) has the potential to disturb a 


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Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 42983 

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’’ (the MMPA defines this as 

Level B harassment) (16 U.S.C. 

1362(18)). 

The terms ‘‘negligible impact’’ and 

‘‘unmitigable adverse impact’’ are 

defined in title 50 of the CFR at 50 CFR 

18.27 (the Service’s regulations 

governing small takes of marine 

mammals incidental to specified 

activities). ‘‘Negligible impact’’ is 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. ‘‘Unmitigable 

adverse impact’’ means 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. 

The term ‘‘small numbers’’; is also 

defined in 50 CFR 18.27. However, we 

do not rely on that definition here as it 

conflates ‘‘small numbers’’ with 

‘‘negligible impacts.’’ We recognize 

‘‘small numbers’’ and ‘‘negligible 

impacts’’ as two separate and distinct 

requirements for promulgating 

incidental take regulations (ITRs) under 

the MMPA (see Natural Res. Def. 

Council, Inc. v. Evans, 232 F. Supp. 2d 

1003, 1025 (N.D. Cal. 2003)). Instead, for 

our small numbers determination, we 

estimate the likely number of takes of 

marine mammals and evaluate if that 

take is small relative to the size of the 

species or stock. 

The term ‘‘least practicable adverse 

impact’’ is not defined in the MMPA or 

its enacting regulations. For this ITR, we 

ensure the least practicable adverse 

impact by requiring mitigation measures 

that are effective in reducing the impact 

of Industry activities but are not so 

restrictive as to make Industry activities 

unduly burdensome or impossible to 

undertake and complete. 

In this ITR, the term ‘‘Industry’’ 

includes individuals, companies, and 

organizations involved in exploration, 

development, production, extraction, 

processing, transportation, research, 

monitoring, and support services of the 

petroleum industry that were named in 

the request for this regulation. Industry 

activities may result in the incidental 

taking of Pacific walruses and polar 

bears. 

The MMPA does not require Industry 

to obtain an incidental take 

authorization; however, any taking that 

occurs without authorization is a 

violation of the MMPA. Since 1993, the 

oil and gas industry operating in the 

Beaufort Sea and the adjacent northern 

coast of Alaska has requested and we 

have issued ITRs for the incidental take 

of Pacific walruses and polar bears 

within a specified geographic region 

during specified activities. For a 

detailed history of our current and past 

Beaufort Sea ITRs, refer to the Federal 

Register at 81 FR 52276, August 5, 2016; 

76 FR 47010, August 3, 2011; 71 FR 

43926, August 2, 2006; and 68 FR 

66744, November 28, 2003. The current 

regulations are codified at 50 CFR part 

18, subpart J (§§ 18.121 to 18.129). 

Summary of Request 

On June 15, 2020, the Service 

received a request from the Alaska Oil 

and Gas Association (AOGA) on behalf 

of its members and other participating 

companies to promulgate regulations for 

nonlethal incidental take of small 

numbers of walruses and polar bears in 

the Beaufort Sea and adjacent northern 

coast of Alaska for a period of 5 years 

(2021–2026) (hereafter referred to as 

‘‘the Request’’). We received an 

amendment to the Request on March 9, 

2021, which was deemed adequate and 

complete. The amended Request is 

available at www.regulations.gov at 

Docket No. FWS–R7–ES–2021–0037. 

The AOGA Request requested 

regulations that will be applicable to the 

oil and gas exploration, development, 

and production, extraction, processing, 

transportation, research, monitoring, 

and support activities of multiple 

companies specified in the Request. 

This includes AOGA member and other 

non-member companies that have 

applied for these regulations and their 

subcontractors and subsidiaries that 

plan to conduct oil and gas operations 

in the specified geographic region. 

Members of AOGA represented in the 

Request are: Alyeska Pipeline Service 

Company, BlueCrest Energy, Inc., 

Chevron Corporation, ConocoPhillips 

Alaska, Inc. (CPAI), Eni U.S. Operating 

Co. Inc. (Eni Petroleum), ExxonMobil 

Alaska Production Inc. (ExxonMobil), 

Furie Operating Alaska, LLC, Glacier Oil 

and Gas Corporation (Glacier), Hilcorp 

Alaska, LLC (Hilcorp), Marathon 

Petroleum, Petro Star Inc., Repsol, and 

Shell Exploration and Production 

Company (Shell). 

Non-AOGA companies represented in 

the Request are: Alaska Gasline 

Development Corporation (AGDC), 

Arctic Slope Regional Corporation 

(ASRC) Energy Services, Oil Search 

(Alaska), LLC, and Qilak LNG, Inc. This 

rule applies only to AOGA members, 

the non-members noted above, their 

subsidiaries and subcontractors, and 

companies that have been or will be 

acquired by any of the above. The 

activities and geographic region 

specified in AOGA’s Request and 

considered in this rule are described 

below in the sections titled Description 

of Specified Activities and Description 

of Specified Geographic Region. 

Summary of Changes From the 

Proposed ITR 

In preparing this final rule for the 

incidental take of polar bears and 

Pacific walruses, we reviewed and 

considered comments and information 

from the public on our proposed rule 

published in the Federal Register on 

June 1, 2021 (86 FR 29364). We also 

reviewed and considered comments and 

information from the public for our draft 

environmental assessment (EA). Based 

on those considerations, we are 

finalizing these regulations with the 

following changes from our proposed 

rule: 

• The Service revised language to 

state: ‘‘Aircraft operations within the 

ITR area should maintain an altitude of 

1,500 ft above ground level when safe 

and operationally possible.’’ The 

inclusion of ‘‘safe and’’ is essential to 

clarify that this altitude 

recommendation applies only when it is 

safe to do so (in addition to when it is 

‘‘operationally possible’’). 

• The Service added language to state 

that, where information is insufficient to 

evaluate the potential effects of 

activities on walruses, polar bears, and 

the subsistence use of these species, 

holders of an LOA may be required to 

participate in joint monitoring and/or 

research efforts to address these 

information needs and ensure the least 

practicable impact to these resources. 

• The Service added language 

specifying that a group be defined for 

both walruses and polar bears as being 

two or more individuals. 

• The Service added language that 

clarifies that the correct geographic 

region to which the ITRs will apply is 

50 miles offshore, not 200 miles 

offshore. 

• The Service has revised Table 1 in 

the preamble to include details 

regarding the sound measurement units 

and included peak SPL for impulsive 

sound sources. The Service has also 


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revised references to past ITR Level B 

harassment and TTS thresholds. 

• The Service has added clarifying 

language to reflect the numbers of leases 

and land area in the NPR–A to reflect 

307 leases covering 2.6 million acres. 

• The Service added a recent peerreviewed article, ‘‘Polar bear behavioral 

response to vessel surveys in 

northeastern Chukchi Sea, 2008–2014’’ 

by Lomac-MacNair et al. (2021), which 

assisted with the analysis of behavioral 

responses of polar bears to vessel 

activity. 

• The Service has clarified our 

discussion regarding the conclusions we 

drew from the peer-reviewed article 

‘‘Aquatic behaviour of polar bears 

(Ursus maritimus) in an increasingly 

ice-free Arctic.’’ Lone, et al. 2018. 

• The Service added language to 

clarify information requirements from 

applicants for LOAs and have clarified 

our discussion regarding monthly 

human occupancy. 

• The Service added clarifying 

language to § 18.126(b)(4) to limit 

disturbance around dens, including 

putative and verified dens. 

• The Service has removed the term 

‘‘other substantially similar’’ when 

describing what proposed activities are 

covered under these ITRs. 

Description of the Regulations 

This rule does not authorize or 

‘‘permit’’ the specified activities to be 

conducted by the applicant. Rather, it 

authorizes the nonlethal, incidental, 

unintentional take of small numbers of 

Pacific walruses and polar bears that 

may result from Industry activities 

based on standards set forth in the 

MMPA. The Bureau of Ocean Energy 

Management (BOEM), the Bureau of 

Safety and Environmental Enforcement, 

the U.S. Army Corps of Engineers, and 

the Bureau of Land Management (BLM) 

are responsible for permitting activities 

associated with Industry activities in 

Federal waters and on Federal lands. 

The State of Alaska is responsible for 

permitting Industry activities on State 

lands and in State waters. The 

regulations include: 

• Permissible methods of nonlethal 

taking; 

• Measures designed to ensure the 

least practicable adverse impact on 

Pacific walruses and polar bears and 

their habitat, and on the availability of 

these species or stocks for subsistence 

uses; and 

• Requirements for monitoring and 

reporting. 

Description of Letters of Authorization 

(LOAs) 

An LOA is required to conduct 

activities pursuant to an ITR. Under this 

ITR, entities intending to conduct the 

specific activities described in these 

regulations may request an LOA for the 

authorized nonlethal, incidental Level B 

harassment of walruses and polar bears. 

Per AOGA’s Request, such entities 

would be limited to the companies, 

groups, individuals specified in AOGA’s 

Request, their subsidiaries or 

subcontractors, and their successors-ininterest. Requests for LOAs must be 

consistent with the activity descriptions 

and mitigation and monitoring 

requirements of the ITR and be received 

in writing at least 90 days before the 

activity is to begin. Requests must 

include (1) an operational plan for the 

activity; (2) a digital geospatial file of 

the project footprint, (3) estimates of 

monthly human occupancy (i.e., a 

percentage that represents the amount of 

the month that at least one human is 

occupying a given location) of project 

area; (4) a walrus and/or polar bear 

interaction plan, (5) a site-specific 

marine mammal monitoring and 

mitigation plan that specifies the 

procedures to monitor and mitigate the 

effects of the activities on walruses and/ 

or polar bears, including frequency and 

dates of aerial infrared (AIR) surveys if 

such surveys are required, and (6) Plans 

of Cooperation (described below). Once 

this information has been received, we 

will evaluate each request and issue the 

LOA if we find that the level of taking 

will be consistent with the findings 

made for the total taking allowable 

under the ITR and all other 

requirements of these regulations are 

met. We must receive an after-action 

report on the monitoring and mitigation 

activities within 90 days after the LOA 

expires. For more information on 

requesting and receiving an LOA, refer 

to 50 CFR 18.27. 

Description of Plans of Cooperation 

(POCs) 

A POC is a documented plan 

describing measures to mitigate 

potential conflicts between Industry 

activities and Alaska Native subsistence 

hunting. The circumstances under 

which a POC must be developed and 

submitted with a request for an LOA are 

described below. 

To help ensure that Industry activities 

do not have an unmitigable adverse 

impact on the availability of the species 

for subsistence hunting opportunities, 

all applicants requesting an LOA under 

this ITR must provide the Service 

documentation of communication and 

coordination with Alaska Native 

communities potentially affected by the 

Industry activity and, as appropriate, 

with representative subsistence hunting 

and co-management organizations, such 

as the North Slope Borough, the Alaska 

Nannut Co-Management Council 

(ANCC), and Eskimo Walrus 

Commission (EWC), among others. If 

Alaska Native communities or 

representative subsistence hunting 

organizations express concerns about 

the potential impacts of project 

activities on subsistence activities, and 

such concerns are not resolved during 

this initial communication and 

coordination process, then a POC must 

be developed and submitted with the 

applicant’s request for an LOA. In 

developing the POC, Industry 

representatives will further engage with 

Alaska Native communities and/or 

representative subsistence hunting 

organizations to provide information 

and respond to questions and concerns. 

The POC must provide adequate 

measures to ensure that Industry 

activities will not have an unmitigable 

adverse impact on the availability of 

walruses and polar bears for Alaska 

Native subsistence uses. 

Description of Specified Geographic 

Region 

The specified geographic region 

covered by the requested ITR (Beaufort 

Sea ITR region (Figure 1)) encompasses 

all Beaufort Sea waters (including State 

waters and Outer Continental Shelf 

waters as defined by BOEM) east of a 

north-south line extending from Point 

Barrow (N71.39139, W156.475, BGN 

1944) to the Canadian border, except for 

marine waters located within the Arctic 

National Wildlife Refuge (ANWR). The 

offshore boundary extends 80.5 km (50 

mi) offshore. The onshore boundary 

includes land on the North Slope of 

Alaska from Point Barrow to the western 

boundary of ANWR. The onshore 

boundary is 40 km (25 mi) inland. No 

lands or waters within the exterior 

boundaries of ANWR are included in 

the Beaufort Sea ITR region. The 

geographical extent of the Beaufort Sea 

ITR region (approximately 7.9 million 

hectares (ha) (∼19.8 million acres (ac))) 

is smaller than the region covered in 

previous regulations (approximately 

29.8 million ha (∼73.6 million ac) were 

included in the ITR set forth via the 

final rule that published at 81 FR 52276, 

August 5, 2016). 

BILLING CODE 4333–15–P 


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BILLING CODE 4333–15–C 

Description of Specified Activities 

This section first summarizes the type 

and scale of Industry activities 

anticipated to occur in the Beaufort Sea 

ITR region from 2021 to 2026 and then 

provides more detailed specific 

information on these activities. Yearround onshore and offshore Industry 

activities are anticipated. During the 5 

years that the ITR will be in place, 

Industry activities are expected to be 

generally similar in type, timing, and 

effect to activities evaluated under the 

prior ITRs. Due to the large number of 

variables affecting Industry activities, 

prediction of exact dates and locations 

of activities is not possible in a request 

for a 5-year ITR. However, operators 

must provide specific dates and 

locations of activities in their requests 

for LOAs. Requests for LOAs for 

activities and impacts that exceed the 

scope of analysis and determinations for 

this ITR will not be issued. Additional 

information is available in the AOGA 

Request for an ITR at: 

www.regulations.gov in Docket No. 

FWS–R7–ES–2021–0037. 

Exploration Activities 

AOGA’s exploration activities 

specified in the Request are for the 

purpose of exploring subsurface 

geology, water depths, and seafloor 

conditions to help inform development 

and production projects that may occur 

in those areas. Exploration survey 

activities include geotechnical site 

investigations, reflection seismic 

exploration, vibroseis, vertical seismic 

profiles, seafloor imagery collection, 

and offshore bathymetry collection. 

Exploratory drilling and development 

activities include onshore ice pad and 

road development, onshore gravel pad 

and road development, offshore ice road 

development, and artificial island 

development. 

The location of new exploration 

activities within the specified 

geographic region of this rule will be 

influenced by the location of current 

leases as well as any new leases 

acquired via potential future Federal 

and State of Alaska oil and gas lease 

sales. 

BOEM Outer Continental Shelf Lease 

Sales 

BOEM manages oil and gas leases in 

the Alaska Outer Continental Shelf 

(OCS) region, which encompasses 242 

million ha (600 million ac). Of that 

acreage, approximately 26 million ha 

(∼65 million ac) are within the Beaufort 

Sea Planning Area. Ten lease sales have 

been held in this area since 1979, 

resulting in 147 active leases, where 32 

exploratory wells were drilled. 

Production has occurred on one joint 


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72°N 

7lON 

69°N 

120 Miles 

Figure 1-Map of the Beaufort Sea ITR region. 
42986 Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 

Federal/State unit, with Federal oil 

production accounting for more than 

28.7 million barrels (bbl) (1 bbl = 42 

U.S. gallons or 159 liters) of oil since 

2001 (BOEM 2016). Details regarding 

availability of future leases, locations, 

and acreages are not yet available, but 

exploration of the OCS may continue 

during the 2021–2026 timeframe of the 

ITR. Lease Sale 242, previously planned 

in the Beaufort Sea during 2017 (BOEM 

2012), was cancelled in 2015. BOEM 

issued a notice of intent to prepare an 

environmental impact statement (EIS) 

for the 2019 Beaufort Sea lease sale in 

2018 (83 FR 57749, November 16, 2018). 

The 2019–2024 Draft Proposed Program 

included three OCS lease sales, with 

one each in 2019, 2021, and 2023, but 

has not been approved. Information on 

the Alaska OCS Leasing Program can be 

found at: https://www.boem.gov/aboutboem/alaska-leasing-office. 

National Petroleum Reserve—Alaska 

The BLM manages the 9.2 million-ha 

(22.8 million-ac) Natural Petroleum 

Reserve—Alaska (NPR–A), of which 1.3 

million ha (3.2 million ac) occur within 

the Beaufort Sea ITR region. Lease sales 

have occurred regularly in the NPR–A; 

15 oil and gas lease sales have been held 

in the NPR–A since 1999. There are 

currently 307 leases covering more than 

1,052,182 ha (2.6 million ac) in the 

NPR–A. Current operator/ownership 

information is available on the BLM 

NPR–A website at https://www.blm.gov/ 

programs/energy-and-minerals/oil-andgas/leasing/regional-lease-sales/alaska. 

State of Alaska Lease Sales 

The State of Alaska Department of 

Natural Resources (ADNR), Oil and Gas 

Division, holds annual lease sales of 

State lands available for oil and gas 

development. Lease sales are organized 

by planning area. Under areawide 

leasing, the State offers all available 

State acreage not currently under lease 

within each area annually. AOGA’s 

Request includes activities in the State’s 

North Slope and Beaufort Sea planning 

areas. Lease sale data are available on 

the ADNR website at: https://

dog.dnr.alaska.gov/Services/BIFAnd

LeaseSale. Projected activities may 

include exploration, facility 

maintenance and construction, and 

operation activities. 

The North Slope planning area has 

1,225 tracts that lie between the NPR– 

A and the ANWR. The southern 

boundary of the North Slope sale area is 

the Umiat baseline. Several lease sales 

have been held to date in this leasing 

area. As of May 2020, there are 1,505 

active leases on the North Slope, 

encompassing 1.13 ha (2.8 million ac), 

and 220 active leases in the State waters 

of the Beaufort Sea, encompassing 

244,760 ha (604,816 ac). The Beaufort 

Sea Planning Area encompasses a gross 

area of approximately 687,966 ha (1.7 

million ac) divided into 572 tracts 

ranging in size from 210 to 2,330 ha 

(520 to 5,760 ac). 

Development Activities 

Industry operations during oil and gas 

development may include construction 

of roads, pipelines, waterlines, gravel 

pads, work camps (personnel, dining, 

lodging, and maintenance facilities), 

water production and wastewater 

treatment facilities, runways, and other 

support infrastructure. Activities 

associated with the development phase 

include transportation activities 

(automobile, airplane, and helicopter); 

installation of electronic equipment; 

well drilling; drill rig transport; 

personnel support; and demobilization, 

restoration, and remediation work. 

Industry development activities are 

often planned or coordinated by unit. A 

unit is composed of a group of leases 

covering all or part of an accumulation 

of oil and/or gas. Alaska’s North Slope 

oil and gas field primary units include: 

Duck Island Unit (Endicott), Kuparuk 

River Unit, Milne Point Unit, 

Nikaitchuq Unit, Northstar Unit, Point 

Thomson Unit, Prudhoe Bay Unit, 

Badami Unit, Oooguruk Unit, Bear 

Tooth Unit, Pikka Unit, and the Colville 

River and Greater Mooses Tooth Units, 

which for the purposes of this ITR are 

combined into the Western North Slope. 

Production Activities 

North Slope production facilities 

occur between the oilfields of the 

Alpine Unit in the west to Badami and 

Point Thomson in the east. Production 

activities include building operations, 

oil production, oil transport, facilities, 

maintenance and upgrades, restoration, 

and remediation. Production activities 

are long-term and year-round activities 

whereas exploration and development 

activities are usually temporary and 

seasonal. Alpine and Badami are not 

connected to the road system and must 

be accessed by airstrips, barges, and 

seasonal ice roads. Transportation on 

the North Slope is by automobile, 

airplanes, helicopters, boats, vehicles 

with large, low-pressure tires called 

Rolligons, tracked vehicles, and 

snowmobiles. Aircraft, both fixed wing 

and helicopters, are used for movement 

of personnel, mail, rush-cargo, and 

perishable items. Most equipment and 

materials are transported to the North 

Slope by truck or barge. Much of the 

barge traffic during the open-water 

season unloads from West Dock. 

Oil pipelines extend from each 

developed oilfield to the Trans-Alaska 

Pipeline System (TAPS). The 122-cm 

(48-in)-diameter TAPS pipeline extends 

1,287 km (800 mi) from the Prudhoe Bay 

oilfield to the Valdez Marine Terminal. 

Alyeska Pipeline Service Company 

conducts pipeline operations and 

maintenance. Access to the pipeline is 

primarily from established roads, such 

as the Spine Road and the Dalton 

Highway, or along the pipeline right-ofway. 

Oil and Gas Support Activities 

In addition to oil and gas production 

and development activities, support 

activities are often performed on an 

occasional, seasonal, or daily basis. 

Support activities streamline and 

provide direct assistance to other 

activities and are necessary for Industry 

working across the North Slope and 

related areas. Several support activities 

are defined in AOGA’s Request and 

include: Placement and maintenance of 

gravel pads, roads, and pipelines; 

supply operations that use trucks or 

buses, aircraft (fixed-wing or rotorwing), hovercrafts, and barges/tugs to 

transport people, personal incidentals 

(food, mail, cargo, perishables, and 

personal items) between Units and 

facilities; pipeline inspections, 

maintenance dredging and screeding 

operations; and training for emergency 

response and oil spill response. Some of 

these activities are seasonal and 

performed in the winter using tundraappropriate vehicles, such as road, pad, 

and pipeline development and 

inspections. Field and camp-specific 

support activities include: Construction 

of snow fences; corrosion and 

subsidence control and management; 

field maintenance campaigns; drilling; 

well work/work-overs; plugging and 

abandonment of existing wells; waste 

handling (oil field wastes or camp 

wastes); camp operations 

(housekeeping, billeting, dining, 

medical services); support infrastructure 

(warehousing and supplies, shipping 

and receiving, road and pad 

maintenance, surveying, inspection, 

mechanical shops, aircraft support and 

maintenance); emergency response 

services and trainings; construction 

within existing fields to support oil field 

infrastructure and crude oil extraction; 

and transportation services by a variety 

of vehicles. Additional details on each 

of these support activities can be found 

in AOGA’s Request. 


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Specific Ongoing and Planned Activities 

at Existing Oil and Gas Facilities for 

2021–2026 

During the regulatory period, 

exploration and development activities 

are anticipated to occur in the offshore 

and continue in the current oil field 

units, including those projects 

identified by Industry, below. 

Badami Unit 

The Badami oilfield resides between 

the Point Thomson Unit and the 

Prudhoe Bay Unit, approximately 56 km 

(35 mi) east of Prudhoe Bay. No 

permanent road connections exist from 

Badami to other Units, such as Prudhoe 

Bay or the Dalton Highway. The Badami 

Unit consists of approximately 34 ha (85 

ac) of tundra, including approximately 

9.7 km (6 mi) of established industrial 

duty roads connecting all infrastructure, 

56 km (35 mi) of pipeline, one gravel 

mine site, and two gravel pads with a 

total of 10 wells. The oilfield consists of 

the following infrastructure and 

facilities: A central processing facility 

(CPF) pad, a storage pad, the Badami 

airstrip pad, the Badami barge landing, 

and a 40.2-km (25-mi) pipeline that 

connects to Endicott. 

During the summer, equipment and 

supplies are transported to Badami by 

contract aircraft from Merrill Field in 

Anchorage or by barge from the West 

Dock in Prudhoe Bay. During winter 

drilling activities, a tundra ice road is 

constructed near the Badami/Endicott 

Pipeline to tie-in to the Badami CPF 

pad. This winter tundra ice road is the 

only land connection to the Dalton 

Highway and the Badami Unit. Light 

passenger trucks, dump trucks, vacuum 

trucks, tractor trailers, fuel trucks, and 

heavy equipment (e.g., large drill rigs, 

well simulation equipment) travel on 

this road during the winter season. This 

road also opens as an ADNR-permitted 

trail during off-years where Tuckers (a 

brand of tracked vehicle) or tracked 

Steigers (a brand of tractor) use it with 

sleds and snow machines. Activities 

related to this opening would be limited 

to necessary resupply and routine valve 

station maintenance along the oil sales 

pipeline corridor. 

Flights from Anchorage land at 

Badami Airfield (N70.13747, 

W147.0304) for a total of 32 flight legs 

monthly. Additionally, Badami 

transports personnel and equipment 

from Deadhorse to Badami Airfield. 

Approximately 24 cargo flights land at 

Badami Airfield annually depending on 

Unit activities and urgency. Badami also 

conducts aerial pipeline inspections. 

These flights are typically flown by 

smaller, charter aircrafts at a minimum 

altitude of 305 m (1,000 ft) at ground 

level. 

Tundra travel at Badami takes place 

during both the summer and winter 

season. Rolligons and Tuckers (off-road 

vehicles) are used during the summer 

for cargo and resupply activities but 

may also be used to access any pipelines 

and valve pads that are not located 

adjacent to the gravel roads. During 

periods of 24-hour sunlight, these 

vehicles may operate at any hour. 

Similar off-road vehicles are used 

during the winter season for 

maintenance and inspections. 

Temporary ice roads and ice pads may 

be built for the movement of heavy 

equipment to areas that are otherwise 

inaccessible for crucial maintenance 

and drilling. Ice road construction 

typically occurs in December or January; 

however, aside from the previously 

mentioned road connecting Badami to 

the Dalton Highway, ice roads are not 

routinely built for Badami. Roads are 

only built on an as-needed basis based 

on specific projects. Other activities 

performed during the winter season 

include pipeline inspections, culvert 

work, pigging, ground surveillance, 

geotechnical investigations, vertical 

support member (VSM) leveling, 

reconnaissance routes (along snow 

machine trails), and potentially spill 

response exercises. Road vehicles used 

include pickup trucks, vacuum trucks, 

loaders, box vans, excavators, and hot 

water trucks. Standard off-road vehicles 

include, but are not limited to, Tuckers, 

Rolligons, and snow machines. 

On occasion, crew boats, landing 

craft, and barges may transport 

personnel and equipment from West 

Dock to Badami from July through 

September, pending the open-water 

window. Tugs and barges may also be 

used depending on operational needs. 

These trips typically go from Badami to 

other coastal Units, including Endicott 

and Point Thomson. 

Badami performs emergency response 

and oil spill trainings during both openwater and ice-covered seasons. Smaller 

vessels (i.e., zodiacs, aluminum work 

boats, air boats, and bay-class boats) 

typically participate in these exercises. 

Future classes may utilize other 

additional equipment or vessels as 

needed. 

Currently, 10 wells have been drilled 

across the lifespan of the Badami Unit. 

Repair and maintenance activities on 

pipelines, culverts, ice roads, and pads 

are routine within the Badami Unit and 

occur year-round. Badami’s current 

operator has received a permit from the 

U.S. Army Corps of Engineers to permit 

a new gravel pad (4.04 ha [10 ac]) 

located east of the Badami Barge 

Landing and a new gravel pit. This new 

pad would allow the drilling of seven 

more deployment wells at Badami. All 

new wells would be tied back to the 

CPF. 

Duck Island Unit (Endicott) 

Historically called the Endicott 

Oilfield, the Duck Island Unit is located 

approximately 16 km (10 mi) northeast 

of Prudhoe Bay. Currently, Hilcorp 

Alaska, LLC operates the oilfield. 

Endicott is the first offshore oilfield to 

continuously produce oil in the Arctic 

area of the United States and includes 

a variety of facilities, infrastructure, and 

islands. Endicott consists of 210 ha (522 

ac) of land, 24 km (15 mi) of roads, 43 

km (24 mi) of pipelines, two pads, and 

no gravel mine sites. The operations 

center and the processing center are 

situated on the 24-ha (58-ac) Main 

Production Island (MPI). To date, 113 

wells have been drilled in efforts to 

develop the field, of which 73 still 

operate. Additionally, two satellite 

fields (Eider and Sag Delta North) are 

drilled from the Endicott MPI. Regular 

activities at Endicott consist of 

production and routine repair on the 

Endicott Sales Oil Pipeline, culverts, 

bridges, and bench bags. A significant 

repair on a bridge called the ‘‘Big 

Skookum’’ is expected to occur during 

the duration of this ITR. 

Endicott’s facilities are connected by 

gravel roads and are accessible through 

the Dalton Highway year-round via a 

variety of vehicles (pickup trucks, 

vacuum trucks, loaders, box vans, 

excavators, hot water trucks). Required 

equipment and supplies are brought in 

first from Anchorage and Fairbanks, 

through Deadhorse, and then into 

Endicott. Traffic is substantial, with 

heavy traffic on routes between 

processing facilities and camps. 

Conversely, drill site access routes 

experience much less traffic with 

standard visits occurring twice daily 

(within a 24-hour period). Traffic at drill 

sites increases during active drilling, 

maintenance, or other related projects 

and tends to subside during normal 

operations. Hilcorp uses a variety of 

vehicles on these roads, including light 

passenger trucks, heavy tractor-trailer 

trucks, heavy equipment, and very large 

drill rigs. Ice roads are only built on an 

as-needed basis for specific projects. 

Air travel via helicopter from an 

established pad on Endicott to 

Deadhorse Airport is necessary only if 

the access bridges are washed out 

(typically mid to late May to the start of 

June). During such instances, 

approximately 20–30 crew flights would 

occur along with cargo flights about 

once a week. Hilcorp also performs 


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maternal polar bear den surveys via 

aircraft. 

Hilcorp performs tundra travel work 

during the winter season (December– 

May; based on the tundra opening 

dates). Activities involving summer 

tundra travel are not routine, and 

pipeline inspections can be performed 

using established roads. During the 

winter season, off-road vehicles (e.g., 

Tuckers, snow machines, or tracked 

utility vehicles called Argo centaurs) 

perform maintenance, pipeline 

inspections, culvert work, pigging, 

ground surveillance, VSM leveling, 

reconnaissance routes (snow machine 

trails), spill response exercises, and 

geotechnical investigations across 

Endicott. 

Tugs and barges are used to transport 

fuel and cargo between Endicott, West 

Dock, Milne, and Northstar during the 

July to September period (pending the 

open-water period). Trips have been as 

many as over 80 or as few as 3 annually 

depending on the needs in the Unit, and 

since 2012, the number of trips between 

these fields has ranged from 6 to 30. 

However, a tug and barge have been 

historically used once a year to 

transport workover rigs between West 

Dock, Endicott, and Northstar. Endicott 

performs emergency response and oil 

spill trainings during both the openwater and ice-covered seasons. Smaller 

vessels (i.e., zodiacs, Kiwi Noreens, bayclass boats) participate in these 

exercises; however, future classes may 

utilize other additional equipment or 

vessels (e.g., the ARKTOS amphibious 

emergency escape vehicle) as needed. 

ARKTOS training will not be conducted 

during the summer. 

Kuparuk River Unit 

ConocoPhillips Alaska, Inc., operates 

facilities in the Kuparuk River Unit. 

This Unit is composed of several 

additional satellite oilfields (Tarn, Palm, 

Tabasco, West Sak, and Meltwater) 

containing 49 producing drill sites. 

Collectively, the Greater Kuparuk Area 

consists of approximately 1,013 ha 

(2,504 ac) made up of 209 km (130 mi) 

of gravel roads, 206 km (128 mi) of 

pipelines, 4 gravel mine sites, and over 

73 gravel pads. A maximum of 1,200 

personnel can be accommodated at the 

Kuparuk Operations Center and the 

Kuparuk Construction Camp. The 

camps at the Kuparuk Industrial Center 

are used to accommodate overflow 

personnel. 

Kuparuk’s facilities are all connected 

by gravel road and are accessible from 

the Dalton Highway year-round. 

ConocoPhillips utilizes a variety of 

vehicles on these roads, including light 

passenger trucks, heavy tractor-trailer 

trucks, heavy equipment, and very large 

drill rigs. Required equipment and 

supplies are flown in through 

Deadhorse and then transported via 

vehicle into the Kuparuk River Unit. 

Traffic has been noted to be substantial, 

with specific arterial routes between 

processing facilities and camps 

experiencing the heaviest use. 

Conversely, drill site access routes 

experience much less traffic with 

standard visits to drill sites occurring at 

least twice daily (within a 24-hour 

period). Traffic at drill sites increases 

during drilling activities, maintenance, 

or other related projects and tends to 

subside during normal operations. 

The Kuparuk River Unit uses its own 

private runway (Kuparuk Airstrip; 

N70.330708, W149.597688). Crew and 

personnel are transported to Kuparuk on 

an average of two flights per day. Flights 

arrive into Kuparuk only on the 

weekdays (Monday through Friday). 

Year round, approximately 34 flights 

per week transport crew and personnel 

between Kuparuk and Alpine Airport. 

ConocoPhillips plans to replace the 

passenger flights from Alpine to 

Kuparuk in 2021 with direct flights to 

both Alpine and Kuparuk from 

Anchorage. These flights are expected to 

occur five times weekly and will replace 

the weekly flights from Alpine to 

Kuparuk. Cargo is also flown into 

Kuparuk on personnel flights. The 

single exception would be for special 

and specific flights when the Spine road 

is blocked. Occasionally, a helicopter 

will be used to transport personnel and 

equipment within the Kuparuk River 

Unit. These flights generally occur 

between mid-May and mid-September 

and account for an estimated 50 

landings annually in Kuparuk. The 

location and duration of these flights are 

variable, and helicopters could land at 

the Kuparuk Airstrip or remote 

locations on the tundra. However, only 

4 of the estimated 50 landings are 

within 3.2 km (5 mi) of the coast. 

ConocoPhillips flies surveys of remote 

sections of the Kuparuk crude pipeline 

one to two times weekly during summer 

months as well as during winter months 

when there is reduced visibility from 

snow cover. During winter months, 

maternal den surveys are also performed 

using aircraft with mounted AIR 

cameras. Off-road vehicles (such as 

Rolligons and Tuckers) are used for 

maintenance and inspection of 

pipelines and power poles that are not 

located adjacent to the gravel roads. 

These vehicles operate near the road 

(152 m [500 ft]) and may operate for 24 

hours a day during summer months. 

During winter months, temporary ice 

roads and pads are built to move heavy 

equipment to areas that may be 

inaccessible. Winter tundra travel 

distances average approximately 1,931 

km (1,200 mi) with ice roads averaging 

approximately 17.7 km (11 mi) and may 

occur at any hour of the day. Dredging 

and screeding occur annually to the 

extent necessary for safety, continuation 

of seawater flow, and dock stability at 

the Kuparuk saltwater treatment plant 

intake and at Oliktok dock. Dredging 

occurs within a 1.5-ha (3.7-ac) area, and 

screeding occurs within a 1-ha (2.5-ac) 

area. Operations are conducted during 

the open-water season (May to October 

annually). Removed material from 

screeding and dredging is deposited in 

upland areas above the high tide, such 

as along the Oliktok causeway and 

saltwater treatment plant (STP) pad. 

ConocoPhillips removes approximately 

0.6 to 1.1 m (2 to 3.5 ft) of sediment per 

year. Dredging activities typically last 

for 21 days, and screeding activities 

typically last 12 days annually. Boats 

are also used to perform routine 

maintenance as needed on the STP 

outfalls and inlets. ConocoPhillips 

infrequently has marine vessel traffic at 

the Oliktok Dock. 

ConocoPhillips performs emergency 

response and oil spill trainings during 

both open-water and ice-covered 

seasons. Smaller vessels (i.e., zodiacs, 

aluminum work boats, air boats, and 

bay-class boats) typically participate in 

these exercises. Future classes may 

utilize other additional equipment or 

vessels as needed. 

The Willow Development Project, 

which is described in full in Planned 

Activities at New Oil and Gas Facilities 

for 2021–2026, would lead to increased 

activity through the Kuparuk River Unit. 

Prefabricated modules would be 

transported through the Unit. Module 

transportation involves an increase in 

road, aircraft, and vessel traffic resulting 

in the need for gravel road and gravel 

pad modifications, ice road and ice pad 

construction, and sea floor screeding. 

During the 2023 summer season, gravel 

hauling and placement to modify 

existing roads and pads used in support 

of the Willow Development would take 

place. An existing 12-acre gravel pad 

located 13.2 km (2 mi) south of the 

Oliktok Dock would require the 

addition of 33,411 cubic m (43,700 

cubic yd) of gravel, increasing pad 

thickness to support the weight of the 

modules during staging. However, this 

addition of gravel would not impact the 

current footprint of the pad. 

Additionally, ConocoPhillips plans to 

widen six road curves and add four 0.2- 

ha (0.5-ac) pullouts between the Oliktok 

Dock and Drill Site 2P as well as 

increase the thickness of the 3.2-km (2- 


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mi) gravel road from the Oliktok Dock 

to the staging pad—requiring 

approximately 30,811 cubic m (40,300 

yd) of gravel and resulting in an 

increase in footprint of the gravel road 

by <0.4 ha (<0.1 ac). Twelve culverts are 

estimated to be extended within this 

part of the gravel road to accommodate 

the additional thickness (approximately 

five culverts per mile). This would yield 

a new gravel footprint with an 

additional 2 ha (5.0 ac) and 90,752 cubic 

m (118,700 cubic yd). In 2025, a 6.1-ha 

(15-ac) ice pad, for camp placement, and 

an ice road for module transportation, 

would be constructed in association 

with the Willow Project. The planned 

location is near Drill Site 2P, over 32.2 

km (20 mi) away from the coastline. 

An increase in road traffic to Kuparuk 

is expected to begin in 2023 and 

continue into the summer of 2026. 

Activities would mostly consist of the 

transportation of freight, equipment, 

and support crews between Oliktok 

Point, the Kuparuk Airport, and the 

NPR–A. The number of weekly flights 

will also increase with an average of 6 

additional weekly flights in 2023, 4 

additional flights per week in 2024, 14 

additional flights per week in 2025, and 

4 additional flights per week in 2026. 

Eight barges would deliver the 

prefabricated modules and bulk material 

to Oliktok Dock using existing and 

regularly used marine transportation 

routes in the summer of 2024 and 2026. 

Due to the current depths of water at 

the Oliktok Dock (2.4 m [8 ft]), 

lightering barges (barges that transfer 

cargo between vessels to reduce a 

vessel’s draft) would be used to support 

the delivery of large modules to the 

Dock. The location of the lightering 

transfer would be approximately 3.7 km 

(2.3 mi) north of Oliktok Dock in 3.05 

m (10 ft) of water. Screeding operations 

would occur during the summer openwater season 2022–2024 and 2026 

starting mid-July and take 

approximately one week to complete. 

The activities would impact an area of 

3.9 ha (9.6 ac) and an additional hectare 

(2.5 ac) in front of the Oliktok Dock to 

facilitate the unloading of the lightering 

barges. Bathymetry measurements 

would be taken after to confirm the 

appropriate conditions of the screeded 

seafloor surface. 

Milne Point Unit 

The Milne Point Unit is located 56 km 

(35 mi) northwest of Prudhoe Bay, 

producing from three main pools, 

including Kuparuk, Schrader Bluff, and 

Sag River. The total development area of 

Milne Point is 182 ha (450 ac), 

including 80 ha (198 ac) of 14 gravel 

pads, 54 km (33 mi) of gravel roads and 

mines, 161 km (100 mi) of pipelines, 

and over 330 wells. 

Milne Point’s facilities are connected 

by gravel roads and are accessible by the 

Dalton Highway year-round via a variety 

of vehicles (pickup trucks, vacuum 

trucks, loaders, box vans, excavators, 

hot water trucks). Required equipment 

and supplies are brought in first from 

Anchorage and Fairbanks, through 

Deadhorse, and then into the Milne 

Point Unit. Arterial roads between 

processing facilities and camps 

experience heavy traffic use. 

Conversely, drill site access routes 

experience much less traffic, with 

standard visits to drill sites occurring 

twice daily (within a 24-hour period). 

Traffic at drill sites increases during 

drilling activities, maintenance, or other 

related projects and tends to subside 

during normal operations. Industry uses 

a variety of vehicles on these roads, 

including light passenger trucks, heavy 

tractor-trailer trucks, heavy equipment, 

and very large drill rigs. 

Air travel via helicopter from an 

established pad (N70.453268, 

W149.447530) to Deadhorse Airport is 

necessary only if the access bridges are 

washed out (typically mid to late May 

to the start of June). During such 

instances, approximately 20–30 crew 

flights would occur, along with cargo 

flights, about once a week. Hilcorp also 

performs maternal polar bear den 

surveys via aircraft. 

Hilcorp uses off-road vehicles 

(Rolligons and Tuckers) for tundra 

travel during summer months to access 

any pipelines and power poles not 

found adjacent to the gravel roads. 

During the winter seasons, temporary 

ice roads and ice pads are built as 

needed across the Unit to move heavy 

equipment to areas otherwise 

inaccessible. Hilcorp also uses their offroad vehicles (Tuckers, snow machines, 

and Argo centaurs) during the winter to 

perform maintenance and inspections. 

Additionally, road vehicles (pickup 

trucks, vacuum trucks, loaders, box 

vans, excavators, and hot water trucks) 

are used to perform pipeline 

inspections, culvert work, pigging, 

ground surveillance, VSM leveling, 

reconnaissance routes (snow machine 

trails), potential spill response 

exercises, and geotechnical 

investigations. 

There are 14 pads and 2 gravel mine 

sites within the Milne Point Unit. 

Twenty-eight new wells are expected to 

be drilled over the next 7 years. Repair 

activities are routine at Milne Point and 

occur on pipelines, culverts, ice roads, 

and pads. Hilcorp also has plans to 

continue development on Milne Point 

and will be running two to three more 

drilling rigs over the next 5 years— 

requiring several pad expansions to 

support them. Hilcorp plans to expand 

six pads, including: S Pad (4.5 ha [11 

ac]), I Pad (0.81 ha [2 ac]), L Pad (0.81 

ha [2 ac]), Moose Pad (0.81 ha [2 ac]), 

B Pad (2.1 ha [5.3 ac]), and E Pad (0.4 

ha [1 ac]). Additionally, Hillcorp’s 

proposed Raven Pad is projected to be 

built in 2021 between the L and F Pads. 

This pad will be 12.1 ha (30 ac) and 

contain various facilities, pipelines, tieins, a new pipeline/VSM along existing 

routes connecting F Pad to CFP and 45 

wells. 

Hilcorp is also planning to drill at 

least 28 new wells with a potential for 

more over the period of the ITR. New 

facilities will be installed for polymer 

injections, flowlines for new wells, 

pipelines, camps, tanks, and main 

facility improvements. This will require 

the development of new gravel pits for 

mining. Some of the new facilities 

planned to be built include: Upgrades to 

Moose pad; F Pad Polymer facility 

installation and startup; 2020 shutdown 

for A-Train process vessel inspections 

and upgrades; LM2500 turbine overhaul 

completion; Raven Pad design and civil 

work; S Pad facility future expansion; S 

Pad polymer engineering and 

procurement; diesel to slop oil tank 

conversion; and I Pad redevelopment. 

Repair activities will be routinely 

performed on pipelines, culverts, ice 

roads, and pads. Power generation and 

infrastructure at L Pad and polymer 

injection facilities are also planned on 

Moose Pad, F Pad, J Pad, and L Pad. 

Hilcorp plans to expand the size of 

the Milne mine site up to 9 ha (22.37 

ac). Approximately 6.3 ha (15.15 ac) 

will be mined for gravel. Overburden 

store will require about 1 ha (2.5 ac) and 

will be surrounded by a 1.3-ha (3.4-ac) 

buffer. Around 0.5 ha (1.32 ac) will be 

used to expand the Dalton Highway. 

The Ugnu Mine Site E, located 

approximately 8 km (5 mi) southeast of 

Oliktok Point and 3.2 km (2 mi) south 

of Simpson Lagoon, will also be 

expanded during the 2021–2026 ITR. 

Hilcorp’s planned expansion for the 

new cell is approximately 259 m long by 

274 m wide (850 ft long by 900 ft wide) 

or 7.1 ha (17.56 ac). This would produce 

an estimated 434,267 cubic m (568,000 

cubic yd) of overburden including a 20 

percent swell factor, and approximately 

764,554 cubic m (1,000,000 cubic yd) of 

gravel. The footprint of the Phase I 

Material Site is expected to be 6.5 ha (16 

ac). Overburden storage, a thermal 

barrier, and access road would require 

approximately 4.2 ha (10.3 ac). The final 

site layout will be dependent on gravel 

needs. 


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Marine vessels (specifically crew 

boats) are used to transport workers 

from West Dock to Milne Point if 

bridges are washed out. Additionally, 

vessels (tugs/barges) are used to 

transport fuel and cargo between 

Endicott, West Dock, Milne Point, and 

Northstar from July to September. While 

the frequency of these trips is 

dependent on operational needs in a 

given year, they are typically sparse. 

Hilcorp performs several emergency 

response and oil spill trainings 

throughout the year during both the 

open-water and ice-covered season. 

Smaller vessels (i.e., zodiacs, Kiwi 

Noreens, bay-class boats) typically 

participate in these exercises; however, 

future classes may utilize other 

additional equipment or vessels (e.g., 

the ARKTOS amphibious emergency 

escape vehicle) as needed. ARKTOS 

training will not be conducted during 

the summer, though Hilcorp notes that 

some variation in activities and 

equipment can be expected. 

Nikaitchuq Unit 

Eni U.S. Operating Co., Inc., is the 100 

percent working interest owner and 

operator of the Nikaitchuq Unit. The 

Nikaitchuq Unit includes the following 

infrastructure: Oliktok Production Pad 

(OPP), Spy Island Drill site (SID), 

Nikaitchuq Operations Center (NOC), a 

subsea pipeline bundle, an onshore 

crude oil transmission pipeline (COTP), 

and an onshore pad that ties into the 

Kuparuk Pipeline (known as KPP). 

Currently, the SID includes 19 

production wells, one exploration well 

on a Federal offshore lease, 14 injection 

wells, one Class-1 disposal well, and 

two shallow water wells. The OPP 

includes 12 production wells, 8 

injection wells, 3 source water wells, 1 

Class-1 disposal well, and 2 shallow 

water wells. 

Road access in the Nikaichuq Unit for 

the OPP, NOC, and KPP are through 

connected gravel roads from the Dalton 

Highway year-round and maintained by 

Kuparuk. Equipment and cargo are 

brought in from Anchorage and 

Fairbanks after a stopover in Deadhorse. 

Traffic levels vary depending on 

ongoing activities but do not change 

significantly with time of year. 

Crew and cargo are primarily 

transported using commercial flights to 

Deadhorse and then by vehicle. A 

helicopter may be used for 

transportation of personnel, the delivery 

and movement of supplies and 

equipment from Deadhorse when the 

Kuparuk Bridge is unavailable, or in the 

event of a medical emergency; however, 

these flights are infrequent. Eni utilizes 

off-road vehicles (Rolligons and other 

track vehicles) for both the summer and 

winter seasons for tundra travel; 

however, tundra travel is infrequent. 

Primarily, these activities would occur 

when access to the COTP between OPP 

and KPP is being inspected or under 

maintenance. Eni utilizes off-road 

vehicles during winter to conduct 

maintenance and inspections on COTP 

and to transport personnel, equipment, 

and supplies between the OPP and SID 

during periods where a sea ice road 

between the two locations is being 

constructed. Until the sea ice road is 

completed, vehicles travel by a single 

snow trail (approximately 6.8 km [4.25 

mi]). 

Two to three ice roads are constructed 

within the Nikaichuq Unit annually. 

These ice roads are typically around 6.8 

km (4.25 mi) long and 18.3 m (60 ft) 

wide. Traffic occurs at all hours, 

consisting of a variety of light vehicles, 

such as pickup trucks and sport-utility 

vehicles (SUVs), high-capacity 

personnel transport vehicles (busses), 

ice road construction equipment (road 

graders, water tankers, snow blowers, 

front end loaders, and dump trucks), 

vacuum trucks, and tractor trailers. To 

build the sea ice road, Eni harvests ice 

chips from Lake K–304 after 

constructing a 0.3-km (0.2-mi) long, 9.1- 

m (30-ft) wide tundra ice road. In the 

past, a short tundra ice road was also 

constructed and used to access a lake to 

obtain water for maintenance of a sea 

ice road, and such an ice road may be 

used in the future. 

Maintenance activities, such as gravel 

and gravel bag placement along the 

subsea pipeline, may occur as needed. 

Routine screeding is generally 

performed near barge landings at OPP 

and SID. Dredging is also possible in 

this area, although not likely. 

Hovercrafts are used to transport both 

cargo and personnel year round but 

generally occur daily between Oliktok 

Point and SID during October through 

January and May through July. Crew 

boats with passengers, tugs, and barges 

are used to transport cargo from Oliktok 

Point to the SID daily during open-water 

months (July through September) as 

needed. Eni also performs emergency 

response and oil spill trainings during 

both open-water and ice seasons. 

Northstar Unit 

The Northstar Unit is made up of a 

15,360-ha (38,400-ac) reservoir, and 

Hilcorp Alaska, Inc., currently operates 

it. Northstar is an artificial island 

located approximately 6 km (4 mi) 

northwest of Point McIntyer and 10 km 

(6 mi) from Prudhoe Bay. The water 

depth surrounding the island is 

approximately 11.9 m (39 ft) deep. 

Thirty wells have been drilled to 

develop Northstar, of which 23 are still 

operable. A buried subsea pipeline (58 

km [36 mi] long) connects the facilities 

from Northstar to the Prudhoe Bay 

oilfield. Access to the island is through 

helicopter, hovercraft, boat, Tucker, and 

vehicle (only during the winter ice road 

season). Routine activities include 

maintenance and bench/block repairs 

on culvert, road, and pipelines. 

There are no established roads on 

Northstar Island. Loaders, cranes, and a 

telescopic material handler are used to 

move cargo and equipment. Hilcorp 

exclusively uses helicopters for all 

aircraft operations around the Northstar 

Unit, with an estimated 800 landings 

per year. Crew and cargo flights travel 

daily from May to January to Northstar 

Island from Deadhorse Airport. Slingloading equipment and supplies may 

also occur from May through December. 

Pipeline inspections via aircraft are 

performed once weekly—generally with 

no landings. However, once per quarter, 

the helicopter lands to inspect the end 

of the pipeline where it enters the water 

(N70.404220, W148.692130). 

Only winter tundra travel occurs at 

Northstar. Hilcorp typically builds 

several unimproved ice trails to 

Northstar, including a trail along the 

pipeline corridor from the valve pad 

near the Dew Line site to Northstar (9.5 

km [5.93 mi]); a trail from West Dock to 

the pipeline shore crossing, grounded 

ice along the coastline (7.8 km [4.82 

mi]); two unimproved ice road paths 

from the hovercraft tent at the 

dockhead; one trail under the West 

Dock Causeway (WDC) bridge to well 

pad DH3 (1.4 km [0.86 mi]); and a trail 

around West Dock to intersect the main 

ice road north of the STP (4.6 km [2.85 

mi]). Hilcorp may also construct any 

number of shorter trails into 

undisturbed areas to avoid unstable/ 

unsafe areas throughout the ice season. 

These detours may be constructed after 

March 1st due to safety considerations 

and may deviate approximately 23–46 

m (75–150 ft) from the original road or 

trail. 

Hilcorp typically constructs an 

approximately 11.7-km (7.3-mi) long ice 

road each year between Northstar and 

Prudhoe Bay (specifically West Dock) to 

allow for the transportation of 

personnel, equipment, materials, and 

supplies. This ice road generally allows 

standard vehicles (SUVs, pickup trucks, 

buses, other trucks) to transport crew 

and equipment to and from the island; 

however, Hilcorp may elect to construct 

an ice trail that supports only lightweight vehicles depending on 

operational needs and weather 

conditions. 


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During December or January before 

ice roads are built, Tucker tracked 

vehicles transport cargo and crew daily. 

During ice road construction, work will 

occur for 24 hours a day, 7 days a week, 

and is stopped only when unsafe 

conditions are presented (e.g., high 

winds, extremely low temperatures). Ice 

road construction typically begins 

around January 1st when the ice is 

considered thick enough (minimum of 

61 cm [24 in]) and is typically 

completed within 45 days of the start 

date. 

Once the ice road is built, tractortrailer trucks transport freight, 

chemicals for resupplies (occurs every 2 

weeks using 10 truckloads), diesel, and 

other equipment. Additional personnel 

and smaller freight travel multiple times 

a day in light passenger traffic buses and 

pickup trucks. A grader and snow 

blower maintain the ice road daily, and 

in the event of cracks in the ice road, a 

loader may be used. Tucker tracked 

vehicles and hovercraft are used 

beginning mid-May as ice becomes 

unstable, then, as weather warms, boats 

and helicopters are used. Hilcorp uses 

hovercraft daily between West Dock and 

Northstar Island to transport crew and 

cargo (October through January and May 

through July) when broken-ice 

conditions are present. Crew boats have 

also been used to carry crew and cargo 

daily from West Dock to Northstar 

Island during open-water months (July 

to September) when hovercraft are not 

in use. Tugs and barges transport fuel 

and cargo from West Dock and Endicott 

to Northstar Island during the openwater season (July through September) 

and may be used once a year to 

transport workover rigs. There are 

typically 6–30 trips per year. 

Northstar performs emergency 

response and oil spill trainings during 

both open-water and ice-covered 

seasons. Smaller vessels (i.e., zodiacs, 

aluminum work boats, air boats, and 

bay-class boats) typically participate in 

these exercises. Future classes may 

utilize other additional equipment or 

vessels (e.g., the ARKTOS amphibious 

emergency escape vehicle) as needed. 

However, the ARKTOS training will not 

be conducted during the summer. 

Oooguruk Unit 

The Oooguruk Unit was originally 

developed in 2008 and is operated by 

Eni, consisting of several developments 

and facilities including the Oooguruk 

Drill site (ODS), a 13-km (8.1-mi) long 

pipeline bundle, and the Oooguruk Tiein Pad (OTP). The OTP is an onshore 

production facility that consists of 

tanks, flowlines, support infrastructure, 

and power generation facilities. The 

pipeline bundle consists of two oil 

pipelines, a 30.5-cm (12-in) inner 

diameter production flowline, and a 5.1- 

cm (2-in) inner diameter diesel/base oil 

flowline. The bundle sits about 61 m 

(200 ft) from the shoreline when 

onshore and runs about 3.8 km (2.4 mi) 

on vertical supports to the OTP. A 30.5- 

cm (12-in) product sales line enters a 

metering skid on the southeast side of 

the OTP. This metering skid represents 

the point where the custody of the oil 

is transferred to ConocoPhillips Alaska, 

Inc. Diesel fuels and base oil are stored 

at the OTP to resupply the ODS as 

needed. 

The ODS is a manmade island located 

approximately 9.2 km (5.7 mi) offshore 

and measuring approximately 5.7 ha (14 

ac) and is found approximately 12.9 km 

(8 mi) northwest of the OTP. The site 

includes living quarters with 150 beds, 

a helicopter landing site, various 

production and injection wells, and a 

grind and inject facility. A Nabors rig is 

also located on the pad and the rig is 

currently not in use. The ocean 

surrounding the island is about 3.05 m 

(10 ft) in depth and considered 

relatively shallow. 

Oooguruk relies on interconnected 

gravel roads maintained by Kuparuk to 

gain access to the Dalton Highway 

throughout the year. Equipment and 

supplies travel from Anchorage and 

Fairbanks to the OTP through 

Deadhorse. The ODS is connected to the 

road system only when an ice road is 

developed and available from February 

to May. 

Eni uses helicopters from May to 

January for cargo transport, which is 

limited to flights between the OTP and 

the ODS. Work personnel depart from 

the Nikaitchuq Unit’s NOC pad; Eni 

estimates about 700 flights occur during 

the helicopter season for both crew and 

field personnel. 

Eni occasionally utilizes off-road 

vehicles (e.g., Rolligons and track 

vehicles) during the summer tundra 

months with activities limited to 

cleanup on ice roads or required 

maintenance of the pipeline bundle. 

During winter months, track vehicles 

transport personnel, equipment, and 

supplies between the OTP and ODS 

during the ice road construction period. 

The ice road is approximately 9.8-m (32- 

ft) wide, and traffic and activity are 

constant—most notably from light 

vehicles (pickup trucks, SUVs), highcapacity personnel transport (buses), ice 

road construction equipment (road 

graders, water tankers, snow blowers, 

front-end loaders, dump trucks), and 

well maintenance equipment (coil 

tubing units, wire-line units, hot oil 

trucks). Eni estimates over 3,500 

roundtrips occur annually. 

Eni will add 2,294 cubic m (3,000 

cubic yd) of gravel to facilitate a 

hovercraft landing zone on island east 

and will also conduct additional gravel 

maintenance at the ‘‘shoreline crossing’’ 

of the pipeline or the area where the 

pipeline transitions from the aboveground section to the subsea pipeline. 

Maintenance in these areas is necessary 

to replace gravel lost to erosion from 

ocean wave action. Additionally, Eni 

performs gravel placement on the 

subsea pipeline to offset strudel scour— 

pending the results of annual surveys. 

Island ‘‘armor’’ (i.e., gravel bags) 

requires maintenance throughout the 

year as well. 

Eni utilizes some in-water vessel 

traffic to transport crew and cargo from 

Oliktok Point to the ODS during the 

open-water season (typically July to 

September). These trips occur daily (or 

less if hovercraft are used). 

Additionally, Eni uses tugs and barges 

to transport cargo from Oliktok Point to 

the ODS from July to September. These 

vessels make varying amounts of trips, 

from a few trips annually up to 50 trips 

depending on operational needs at the 

time. 

Like the trainings performed at the 

Nikaitchuq Unit, Eni would also 

conduct emergency and oil spill 

response trainings throughout the ITR 

period at various times. Trainings will 

be conducted during both open-water 

and ice-covered seasons with training 

exercises occurring on both the land and 

the water depending on current ice 

conditions. Further information on 

these trainings can be found on the 

submitted AOGA Request for 2021– 

2026. 

Point Thomson Unit 

The Point Thomson Unit (PTU) is 

located approximately 32 km (20 mi) 

east of the Badami field and 96 km (60 

mi) east of Deadhorse and is operated by 

ExxonMobil. The Unit includes the 

Point Thomson initial production 

system (IPS), Sourdough Wells, and 

legacy exploration sites (i.e., PTU 1–4, 

Alaska C–1, West Staines State 2 and 

18–9–23). The total Point Thomson IPS 

area is approximately 91 ha (225 ac), 

including 12.4 km (7.7 mi) of gravel 

roads, 35 km (22 mi) of pipelines, one 

gravel mine site, and three gravel pads 

(Central, West, and C–1). 

The Point Thomson IPS facilities are 

interconnected by gravel roads but are 

not connected to other oilfields or 

developments. Equipment and supplies 

are brought in via air, barge, ice road, or 

tundra travel primarily from Deadhorse. 

Traffic on gravel roads within the PTU 


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occurs daily with roads from Central 

Pad to the airstrip experiencing the 

heaviest use. This consistent heavy use 

is not influenced by time of year. 

Vehicle types include light passenger 

trucks/vans, heavy tractor-trailer trucks, 

and heavy equipment usage on pads, 

particularly for snow removal and dust 

control. 

Personnel and most cargo are 

transported to Point Thomson using 

aircraft departing from Deadhorse. 

During normal operations, an average of 

two to four passenger flights per week 

land at the Point Thomson Airport. 

Typically, there are 12 cargo flights per 

year (or one per month) that may land 

at Point Thomson, but frequency is 

reduced January to April when tundra is 

open. Aerial pipeline inspection surveys 

are conducted weekly, and 

environmental surveys and operations 

typically occur for one to two weeks 

each summer. The environmental 

surveys are generally performed at 

remediation sites such as West Staines 

State 2 and 18–9–23, areas of pipeline 

maintenance, and tundra travel routes. 

Off-road vehicles (e.g., Rolligons and 

track vehicles) are only used during the 

summer tundra months for emergency 

purposes such as accessing the pipeline. 

During winter months, off-road vehicles 

provide access to spill response 

conexes, deliver cargo supplies from 

Deadhorse, and maintain and inspect 

the PTU. Tundra travel includes a route 

south of the pipeline from Deadhorse to 

Point Thomson, a route along the 

pipeline right-of-way (ROW), spur roads 

as needed between the southern route 

and the pipeline ROW, and a route to 

spill conexes totaling approximately 

146.5 km (91 mi). Travel along these 

routes can occur at any time of day. 

Temporary ice roads and pads near 

the Point Thomson Facility are built to 

move heavy equipment to areas 

otherwise inaccessible for maintenance 

and construction activities. Ice road and 

ice pad construction typically begins in 

December or January. An ice road to 

Point Thomson is typically needed in 

the event that a drilling rig needs to be 

mobilized and extends east from the 

Endicott Road, connects to the Badami 

facilities, and continues east along the 

coast to Point Thomson. 

Barging usually occurs from mid-July 

through September. In the event 

additional barging operations are 

needed, dredging and screeding 

activities may occur to allow barges to 

dock at Point Thomson. If dredging and 

screeding activities are necessary, the 

work would take place during the openwater season and would last less than a 

week. ExxonMobil also performs 

emergency response and oil spill 

trainings during the summer season. On 

occasion, spill response boats are used 

to transport operations and maintenance 

personnel to Badami for pipeline 

maintenance. 

Expansion activities are expected to 

occur over 4 years and would consist of 

new facilities and new wells on the 

Central Pad to increase gas and 

condensate production. The Central Pad 

would require a minor expansion of 

only 2.8 ha (7 ac) to the southwest. 

Minor size increases on infield 

pipelines will also occur, but the facility 

footprint would not otherwise increase. 

To support this project, an annual ice 

road would be constructed, and summer 

barging activities would occur to 

transport a drilling rig, additional 

construction camps, field personnel, 

fuel, equipment, and other supplies or 

materials. Gravel would be sourced from 

an existing stockpile, supplemented by 

additional gravel volume that would be 

sourced offsite as necessary. Drilling of 

wells is expected to occur during the 

later years of construction, and new 

modular production facilities would be 

fabricated offsite and then delivered via 

sealift. 

A small number of barge trips (<10 

annually) are expected to deliver 

equipment, fuel, and supplies during 

the open-water season (mid-July 

through September) from Deadhorse and 

may occur at any time of day. 

Additional development activities are 

planned within PTU and are described 

in the section Alaska Liquefied Natural 

Gas Project (Alaska LNG). 

Prudhoe Bay Unit 

The Prudhoe Bay Unit (PBU) is the 

largest producing oilfield in North 

America and is operated by Hilcorp. 

The PBU includes satellite oilfields 

Aurora, Borealis, Midnight Sun, Polaris, 

and Orion. The total development area 

is approximately 1,778 ha (4,392 ac), 

including 450 km (280 mi) of gravel 

roads, 2,543 km (1,580 mi) of pipelines, 

4 gravel mines, and over 113 gravel 

pads. Camp facilities such as the 

Prudhoe Bay Operations Center, Main 

Construction Camp, Base Operations 

Center, and Tarmac camp are also 

within the PBU. 

PBU facilities are connected by gravel 

roads and can be accessed from the 

Dalton Highway year-round. Equipment 

and supplies are flown or transported 

over land from Anchorage and 

Fairbanks to Deadhorse before they are 

taken to the PBU over land. Traffic is 

constant across the PBU with arterial 

routes between processing facilities and 

camps experiencing the heaviest use 

while drill site access roads are traveled 

far less except during active drilling, 

maintenance, or other projects. Traffic is 

not influenced by the time of year. 

Vehicle types include light passenger 

trucks, heavy tractor-trailer trucks, 

heavy equipment, and very large drill 

rigs. 

Personnel and cargo are transported to 

the PBU on regularly scheduled, 

commercial passenger flights through 

Deadhorse and then transported to camp 

assignments via bus. Pipeline surveys 

are flown every 7 days departing from 

CPAI’s Alpine airstrip beginning the 

flight route at Pump Station 1 and 

covering a variety of routes in and 

around the Gathering Center 2, Flow 

Station 2, Central Compressor Pad, West 

Gas Injection, and East Sag facilities. 

Pipelines are also surveyed once per day 

from the road system using a truckmounted forward-looking infrared 

camera system. Various environmental 

studies are also conducted using 

aircraft. Surveys include polar bear den 

detection and tundra rehabilitation and 

revegetation studies. Tundra 

environmental studies occur annually 

each summer in July and August with 

field personnel being transported to 

sites over an average of 4 days. Flights 

take off and return to Deadhorse airport, 

and field landings include seven tundra 

sites an average of 25.7 km (16 mi) from 

Deadhorse airport. Only four of the 

seven tundra landing sites are within 8 

km (5 mi) of the Beaufort coast. 

Unmanned aerial systems (UAS) are 

used for subsidence, flare, stack, and 

facility inspections from June to 

September as well as annual flood 

surveillance in the spring. UAS depart 

and arrive at the same location and only 

fly over roads, pipeline ROWs, and/or 

within 1.6 km (1 mi) or line of sight of 

the pad. 

Off-road vehicles (such as Rolligons 

and Tuckers) are used for maintenance 

and inspection activities during the 

summer to access pipelines and/or 

power poles that are not located 

adjacent to the gravel roads. These 

vehicles typically operate near the road 

(152 m [500 ft]) and may operate for 24 

hours a day during summer months. 

During winter months, temporary ice 

roads and pads are built to move heavy 

equipment to areas that may be 

inaccessible. Winter tundra travel 

distances and cumulative ice road 

lengths average about 120.7 and 12.1 km 

(75 and 7.5 mi), respectively, and may 

occur at any hour of the day. An 

additional 0.8 ha (2 ac) of ice pads are 

constructed each winter. 

West Dock is the primary marine 

gateway to the greater Prudhoe Bay area 

with users including Industry vessels, 

cargo ships, oil spill responders, 

subsistence users, and to a lesser degree, 


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public and commercial vessels. Routine 

annual maintenance dredging of the 

seafloor around the WDC occurs to 

maintain navigational access to DH2 

and DH3 and to insure continued intake 

of seawater to the existing STP. 

Approximately 15,291 cubic m (20,000 

cubic yd) of material is anticipated to be 

dredged over 56.6 ha (140 ac); however, 

up to 172,024 cubic m (225,000 cubic 

yd) of material is authorized to be 

removed in a single year. All dredged 

material is placed as fill on the WDC for 

beach replenishment and erosion 

protection. Some sediments are moved 

but remain on the seafloor as part of the 

screeding process. Much of the dredging 

work takes place during the open-water 

season between May and October and 

will be completed in less than 30 

working days. Annual installation and 

floats, moorings, and buoys are installed 

at the beginning of the open-water 

season and are removed at the end of 

the open-water season. Up to three 

buoys may be installed to each side of 

the breach (up to six buoys total). 

During the 2021–2022 winter tundra 

travel period, an additional 8-km (5-mi) 

ice road, 0.8-ha (2-ac) ice pad, up to 8- 

km (5-mi) pipeline, and pad space are 

expected to be constructed to support IPad expansion totaling 12.1 ha (30 ac) 

for the ice road and ice pad and 8.5 ha 

(21 ac) for the pad space, pipeline, and 

VSM footprints. Other pad expansions 

include approximately 0.8 ha (2 ac) per 

year 2021–2026 at DS3–DS0 and P-Pad. 

Additionally, the construction of up 

to a 56.7-ha (140-ac) mine site is 

expected. Construction will occur on a 

need-based, phased approach over 40 

years with no more than 24.3 ha (60 ac) 

of gravel developed by 2026. A 4.3-km 

(2.7-mi) long and 24.4-m (80-ft) wide 

gravel access road will also be built for 

a total impacted area of 10.5 ha (26 ac) 

over 1 year. 

Trans-Alaska Pipeline System (TAPS) 

TAPS is a 122-cm (48-in) diameter 

crude oil transportation pipeline system 

that extends 1,287 km (800 mi) from 

Pump Station 1 in Prudhoe Bay Oilfield 

to the Valdez Marine Terminal. The 

lands occupied by TAPS are Stateowned, and the ROWs are leased 

through April 2034. Alyeska Pipeline 

Service Company operates the pipeline 

ROW. Approximately 37 km (23 mi) of 

pipeline are located within 40 km (25 

mi) of the Beaufort Sea coastline. A 238- 

km (148-mi) natural gas line that 

extends from Pump Station 1 provides 

support for pipeline operations and 

facilities. The TAPS mainline pipe ROW 

includes a gravel work pad and drive 

lane that crosses the Dalton Highway 

approximately 29 km (18 mi) south of 

Pump Station 1. 

Travel primarily occurs along 

established rounds, four pipeline access 

roads, or along the pipeline ROW work 

pad. Ground-based surveillance on the 

TAPS ROW occurs once per week 

throughout the year. Equipment and 

supplies are transported via commercial 

carriers on the Dalton Highway. In the 

summer, travel is primarily restricted to 

the gravel work pad and access roads. 

There are occasional crossings of 

unvegetated gravel bars to repair remote 

flood control structures on the 

Sagavanirktok River. Transport of smallvolume gravel material from the active 

river floodplain to the TAPS work pad 

may occur. Vehicles used during the 

summer include typical highway 

vehicles, maintenance equipment, and 

off-road trucks for gravel material 

transport. In the winter, travel occurs in 

similar areas compared to summer in 

addition to maintenance activities, such 

as subsurface pipeline excavations. 

Short (<0.4 km, <0.25 mi) temporary ice 

roads and ice pads are built to move 

heavy equipment when necessary. 

Vehicles used during the winter include 

off-road tracked vehicles so that snow 

plowing on the ROW is not required. 

The amount of traffic is generally not 

influenced by the time of year. 

The Deadhorse Airport is the primary 

hub used for personnel transport and 

airfreight to TAPS facilities in the 

northern pipeline area. Commercial and 

charter flights are used for personnel 

transport, and crew change-outs 

generally occur every 2 weeks. Other 

aviation activities include pipeline 

surveillance, oil spill exercise/training/ 

response, and seasonal hydrology 

observations. Aerial surveillance of the 

pipeline occurs once each week during 

daylight hours throughout the year. 

Approximately 50 hours per year are 

flown within 40 km (25 mi) of the 

Beaufort Sea coastline. 

No TAPS-related in-water activities 

occur in the Beaufort Sea. Instead, these 

activities will be limited to the 

Sagavanirktok River and its tributaries. 

In-water construction and dredging may 

take place occasionally, and they are 

generally associated with flood control 

structures and repairs to culverts, low 

water crossings, and eroded work pads. 

Gravel mining may also occur on dry 

unvegetated bars of the active floodplain 

or in established gravel pits. On river 

bars, up to a 0.9-m (3-ft) deep layer of 

alluvial gravel is removed when the 

river is low, and this layer is allowed to 

naturally replenish. Additional 

construction of flood structures may be 

needed to address changes in the 

hydrology of the Sagavanirktok River 

and its tributaries during the 2021–2026 

period. 

Western North Slope—Colville River 

and Greater Mooses Tooth Units 

The Western North Slope (WNS) 

consists of the CPAI’s Alpine and 

Alpine satellite operations in the 

Colville River Unit (CRU) and the 

Greater Mooses Tooth Unit (GMTU). 

The Alpine reservoir covers 50,264 ha 

(124,204 ac), but the total developed 

area is approximately 153 ha (378 ac), 

which contains 45 km (28 mi) of gravel 

roads, 51.5 km (32 mi) of pipelines, and 

14 gravel pads. The CRU has a 

combined production pad/drill site and 

four additional drill sites. The GMTU 

contains one producing drill site and a 

second drill site undergoing 

construction. Roads and pads are 

generally constructed during winter. 

There are no permanent roads 

connecting WNS to industrial hubs or 

other oilfields. Gravel roads connect 

four of the five CRU drill sites. An ice 

road is constructed each winter to 

connect to the fifth CRU drill site. 

Gravel roads also connect the GMTU 

drill sites to the CRU, and gravel roads 

connect the two GMTU drill sites to 

each other. Each drill site with gravel 

road access is visited at least twice 

during a 24-hour period, depending on 

the weather. Drill site traffic levels 

increase during active drilling, 

maintenance, or other projects. Vehicles 

that use the gravel roads include light 

passenger trucks, heavy tractor-trailer 

trucks, heavy equipment, and very large 

drill rigs. The amount of traffic is 

generally not influenced by the time of 

year, but there may be increased 

amounts of traffic during the 

exploration season. 

In the winter, off-road vehicles are 

used to access equipment for 

maintenance and inspections. 

Temporary ice roads and ice pads are 

built to move heavy equipment for 

maintenance and construction activities. 

An ice road is constructed to connect 

WNS to the Kuparuk oilfield (KRU) to 

move supplies for the rest of the year. 

More than 1,500 truckloads of modules, 

pipeline, and equipment are moved to 

WNS over this ice road, which is 

approximately 105 km (65 mi) in length. 

As mentioned previously, an ice road is 

constructed each winter to connect one 

of the CRU drill sites to the other CRU 

facilities in order to facilitate 

maintenance, drilling, and operations at 

this drill site. WNS ice roads typically 

operate from mid-January until lateApril. 

The Alpine Airstrip is a private 

runway that is used to transport 

personnel and cargo. An average of 60 


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to 80 personnel flights to/from the 

Alpine Airstrip occur each week. 

Within the CRU, the Alpine Airport 

transports personnel and supplies to 

and from the CRU drill site that is only 

connected by an ice road during the 

winter. There are approximately 700 

cargo flights into Alpine each year. 

Cargo flight activity varies throughout 

the year with October through December 

being the busiest months. Aerial visual 

surveillance of the Alpine crude 

pipeline is conducted weekly for 

sections of the pipeline that are not 

accessible either by road or during 

winter months. These aerial 

surveillance inspections generally occur 

one to two times each week, and they 

average between two and four total 

flight hours each week. CPAI also uses 

aircraft to conduct environmental 

studies, including polar den detection 

surveys in the winter and caribou and 

bird surveys in the summer. These 

environmental surveys cover 

approximately 1,287 linear km (800 

linear mi) over the CRU each year. In 

the summer from mid-May to midSeptember, CPAI uses helicopters to 

transport personnel and equipment 

within the CRU (approximately 2,000 

flights) and GMTU (approximately 650 

flights). 

There are no offshore or coastal 

facilities in the CRU. However, there are 

multiple bridges in the CRU and GMTU 

that required pilings which were driven 

into stream/riverbeds during 

construction. In-water activities may 

occur during emergency and oil spill 

response training exercises. During the 

ice-covered periods, training exercises 

may involve using equipment to detect, 

contain, and recover oil on and under 

ice. During the open-water season, air 

boats, shallow-draft jet boats and 

possibly other vessels may be used in 

the Nigliq Channel, the Colville River 

Main Channel, and other channels and 

tributaries connected to the Colville 

River. Vessels may occasionally enter 

the nearshore Beaufort Sea to transit 

between channels and/or tributaries of 

the Colville River Delta. 

In the 2021–2026 period, two 4-ha 

(10-ac) multiseason ice pads would be 

located in the WNS in order to support 

the Willow Development construction 

in the NPR–A. Possible expansion 

activities for this period may include 

small pad expansions or new pads (<6.1 

ha (15 ac)) to accommodate additional 

drilling and development of small pads 

and gravel roads to accommodate 

additional facilities and operational 

needs. Two gravel mine sources in the 

Ti>miaqsiug ̇vik area have been 

permitted to supply gravel for the 

Willow Development. The new gravel 

source would be accessed seasonally by 

an ice road. Increases in the amount of 

traffic within WNS are expected from 

2023 to 2026. The increase in traffic is 

due to the transport of freight, 

equipment, and support crew between 

the Willow Development, the Oliktok 

Dock, and the Kuparuk Airport. The 

planned Willow Development is 

projected to add several flights to/from 

the Alpine Airstrip from 2021 to 2026. 

It is estimated that the number of annual 

flights may increase by a range of 49 to 

122 flights. There are plans to replace 

passenger flights connecting Alpine and 

Kuparuk oilfields in 2021 with direct 

flights to these oilfields. This change 

would reduce the number of connector 

flights between these oilfields from 18 

flights to 5 flights each week. 

Planned Activities at New Oil and Gas 

Facilities for 2021–2026 

AOGA’s Request includes several new 

oil and gas facilities being planned for 

leases obtained by Industry (see the 

section about Lease Sales) in which 

development and exploration activities 

would occur. The information discussed 

below was provided by AOGA and is 

the best available information at the 

time AOGA’s Request was finalized. 

Bear Tooth Unit (Willow) 

Located 45.1 km (28 mi) from Alpine, 

the Willow Development is currently 

owned and operated by ConocoPhillips 

Alaska, Inc. Willow is found in the Bear 

Tooth Unit (BTU) located within the 

northeastern area of the NPR–A. 

Discovered in 2016 after the drilling of 

the Ti>miaq 2 and 6 wells, Willow is 

estimated to contain 400–750 million 

barrels of oil and has the potential to 

produce over 100,000 barrels of oil per 

day. The Willow Project would require 

the development of several different 

types of infrastructure, including gravel 

roads, airstrips, ice roads, and ice pads, 

that would benefit seismic surveys, 

drilling, operations, production, piledriving, dredging, and construction. 

ConocoPhillips plans to develop the 

hydrocarbon resources within the BTU 

during the 2021–2026 timeline under 

this ITR. The proposed development at 

Willow would consist of five drill sites 

along with associated infrastructure, 

including flowlines, a CPF, a personnel 

camp, an airstrip, a sales oil pipeline, 

and various roads across the area. 

Additionally, Willow would require the 

development of a new gravel mine site 

and would use sea lifts for large 

modules at Oliktok Dock requiring 

transportation over gravel and ice roads 

in the winter. 

Access to the Willow Development 

project area to Alpine, Kuparuk, or 

Deadhorse would be available by 

ground transportation along ice roads. 

Additionally, access to the Alpine Unit 

would occur by gravel road. The 

Development Plan requires 61.5 km 

(38.2 mi) of gravel road and seven 

bridges to connect the five drill sites to 

the Greater Mooses Tooth 2 (GMT2). 

The Willow Development would also 

require approximately 59.7 km (37.1 mi) 

or 104 ha (257.2 ac) of gravel roads to 

the Willow Central Processing Facility 

(WCF), the WCF to the Greater Mooses 

Tooth 2 (GMT2), to water sources, and 

to airstrip access roads. The gravel 

needed for any gravel-based 

development would be mined from a 

newly developed gravel mine site and 

then placed for the appropriate 

infrastructure during winter for the first 

3 to 4 years of the construction. 

Gravel mining and placement would 

occur almost exclusively in the winter 

season. Prepacked snow and ice road 

construction will be developed to access 

the gravel mine site, the gravel road, and 

pad locations in December and January 

yearly from 2021 to 2024, and again in 

2026. Ice roads would be available for 

use by February 1 annually. The Willow 

plan would require gravel for several 

facilities, including Bear Tooth 1 (BT1), 

Bear Tooth 2 (BT2), Bear Tooth 3 (BT3), 

Bear Tooth 4 (BT4), roads, WCF, Willow 

Operations Center (WOC), and the 

airstrip. Additionally, an all-season 

gravel road would be present from the 

GMT2 development and extend 

southwest towards the Willow 

Development area. This access road 

would end at BT3, located west from the 

WCF, WOC, and the airstrip. More 

gravel roads are planned to extend to 

the north, connecting BT1, BT2, and 

BT4. An infield road at BT3 would 

provide a water-source access road that 

would extend to the east to a freshwater 

reservoir access pad and water intake 

system developed by ConocoPhillips. 

Further east from the planned airstrip, 

an infield road is planned to extend 

north to BT1, continue north to BT2, 

and end at BT4. This road would 

intersect Judy (Iqalliqpik) Creek and 

Fish (Uvlutuuq) Creek at several points. 

Culvert locations would be identified 

and installed during the first 

construction season prior to breakup. 

Gravel pads would be developed before 

on-pad facilities are constructed. Gravel 

conditions and re-compaction would 

occur later in the year. 

The Willow area is expected to have 

year-round aircraft operations and 

access from the Alpine Unit, Kuparuk 

Unit, Deadhorse, Anchorage, Fairbanks, 

and several other locations. Aircraft 

would primarily be used for support 

activities and transporting workers, 


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materials, equipment, and waste from 

the Willow Development to Fairbanks, 

Anchorage, Kuparuk, and Deadhorse. To 

support these operations, a 1,890-m 

(6,200-ft)-long gravel airstrip would be 

developed and is expected to be located 

near the WOC. Aircraft flight paths 

would be directed to the north of 

Nuiqsut. The construction for the 

airstrip is expected to begin during the 

2021 winter season and completed by 

the summer of 2022. Before its 

completion, ConocoPhillips would 

utilize the airstrip at the Colville Delta 

1 at the Alpine CPF. After completion 

of the airstrip, helicopters would be 

used to support various projects within 

the Willow Development starting in 

2023. An estimated 82 helicopter flights 

would occur annually during 2023– 

2026 between April and August. After 

the development of planned gravel 

roads and during activities such as 

drilling and related operations, 

helicopters would be limited to support 

environmental monitoring and spill 

response support. ConocoPhillips 

estimates that 50 helicopter trips to and 

from Alpine would occur in 2021, and 

25 helicopter trips would occur from 

Alpine in 2022. 

ConocoPhillips plans to develop and 

utilize ice roads to support gravel 

infrastructure and pipeline construction 

to access lakes and gravel sources and 

use separate ice roads for construction 

and general traffic due to safety 

considerations regarding traffic 

frequency and equipment size. The ice 

road used to travel to the Willow 

Development is estimated to be shorter 

in length than previously built ice roads 

at Kuparuk and Alpine, and 

ConocoPhillips expects the ice road use 

season at Willow to be approximately 90 

days, from January 25 to April 25. In the 

winter ice road season (February 

through April), material resupply and 

waste would be transported to Kuparuk 

and to the rest of the North Slope gravel 

road system via the annual Alpine 

Resupply Ice Road. Additionally, during 

drilling and operations, there would be 

seasonal ground access from Willow to 

Deadhorse and Kuparuk from the 

annually constructed Alpine Resupply 

Ice Road and then to the Alpine and 

GMT gravel roads. 

Seasonal ice roads would be 

developed and used during construction 

at Willow’s gravel mine, bridge 

crossings, horizontal directional drilling 

crossing, and other locations as needed. 

A 4-ha (10-ac) multiseason ice pad 

would be developed and used 

throughout construction. This ice pad 

would be constructed near the WOC 

from 2021 to 2022 and rotated on an 

annual basis. 

Pipelines for the Willow Development 

would be installed during the winter 

season from ice roads. Following VSMs 

and horizontal support members 

(HSMs) assembly and installation; 

pipelines would be placed, welded, 

tested, and installed on pipe saddles on 

top of the HSMs. ConocoPhillips 

expects that the Colville River 

horizontal directional drilling pipeline 

crossing would be completed during the 

2022 winter season. Pipeline 

installation would take approximately 1 

to 3 years per pipeline, depending on 

several parameters such as pipeline 

length and location. 

In 2024 at BT1, a drill rig would be 

mobilized, and drilling would begin 

prior to the WCF and drill site facilities 

being completed. ConocoPhillips 

estimates about 18 to 24 months of ‘‘predrilling’’ activities to occur, allowing 

the WCF to be commissioned 

immediately after its construction. 

Wells would be drilled consecutively 

from BT1, BT3, and BT2; however, the 

timing and order is based upon drill rig 

availability and economic 

decisionmaking. A second drilling rig 

may be utilized during the drilling 

phase of the Willow Development as 

well. ConocoPhillips estimates that 

drilling would occur year-round 

through 2030, with approximately 20 to 

30 days of drilling per well. 

Post-drilling phase and WCF startup, 

standard production and operation 

activities would take place. 

ConocoPhillips estimates that 

production would begin in the fourth 

quarter of 2025 with well maintenance 

operations occurring intermittently 

throughout the oilfield’s lifespan. 

ConocoPhillips plans to develop 

several bridges, installed via in-water 

pile-driving at Judy Creek, Fish Creek, 

Judy Creek Kayyaaq, Willow Creek 2, 

and Willow Creek 4. Pilings would be 

located above the ordinary high-water 

level and consist of sheet pile abutments 

done in sets of four, positioned 

approximately 12.2 to 21.3 m (40 to 70 

ft) apart. Crossings over Willow Creek 

4a and Willow Creek 8 would be 

constructed as single-span bridges, 

approximately 15.2 to 18.3 m (50 to 60 

ft) apart using sheet pile abutments. 

Additionally, bridges would be 

constructed during the winter season 

from ice roads and pads. Screeding 

activities and marine traffic for the 

Willow project may also take place at 

the Oliktok Dock in the KRU. 

Liberty Drilling and Production Island 

The Liberty reservoir is located in 

Federal waters in Foggy Island Bay 

about 13 km (8 mi) east of the Endicott 

Satellite Drilling Island (SDI). Hilcorp 

plans to build a gravel island situated 

over the reservoir with a full on-island 

processing facility (similar to Northstar). 

The Liberty pipeline includes an 

offshore segment that would be buried 

in the seafloor for approximately 9.7 km 

(6 mi), and an onshore, VSM-mounted 

segment extending from the shoreline 

approximately 3.2 km (2 mi) to the 

Badami tie-in. Onshore infrastructure 

would include a gravel mine site, a 0.29- 

ha (0.71-ac) gravel pad at the Badami 

pipeline tie-in and a 6.1-ha (0.15-ac) 

gravel pad to allow for winter season ice 

road crossing. Environmental, 

archeological, and geotechnical work 

activities would take place to support 

the development and help inform 

decisionmaking. Development of the 

Liberty Island would include impact 

driving for conductor pipes/foundation 

pipes, vibratory drilling for conductor 

pipes, and vibratory and impact driving 

for sheet pile. 

Road vehicles would use the Alaska 

Highway System to transport material 

and equipment from supply points in 

Fairbanks, Anchorage, or outside of 

Alaska to the supply hub of Deadhorse. 

Additionally, North Slope gravel roads 

would be used for transport from 

Deadhorse to the Endicott SDI. Existing 

gravel roads within the Endicott field 

between the MPI and the SDI would 

also be used to support the project. 

During the winter seasons, workers 

would access the Liberty Island area 

from existing facilities via gravel roads 

and the ice road system. Construction 

vehicles would be staged at the 

construction sites, including the gravel 

mine. Access to the Liberty Drilling and 

Production Island (LDPI) by surface 

transportation is limited by periods 

when ice roads can be constructed and 

used. Additionally, surface 

transportation to the onshore pipeline 

can take place in winter on ice roads 

and can also occur in summer by 

approved tundra travel vehicles (e.g., 

Rolligons). The highest volume of traffic 

would occur during gravel hauls to 

create the LDPI. Gravel hauling to the 

island would require approximately 14 

trucks working for 76 days (BOEM 

2018). An estimated 21,400 surface 

vehicle trips would occur per season 

during island construction. 

In general, ice roads would be used in 

the winter seasons, marine vessels 

would be used in the summer seasons, 

helicopters would be used across both 

seasons, and hovercraft (if necessary) 

would be used during the shoulder 

season when ice roads and open water 

are not available. By spring breakup, all 

materials needed to support the ongoing 

construction would have been 

transported over the ice road system. 


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Additionally, personnel would access 

the island by helicopter (likely a Bell 

212) or if necessary, via hovercraft. 

During the open-water season, 

continued use of helicopter and 

hovercraft would be utilized to transport 

personnel—however, crew boats may 

also be used. 

Construction materials and supplies 

would be mobilized to the site by barge 

from West Dock or Endicott. Larger 

barges and tugs can over-winter in the 

Prudhoe Bay area and travel to the LDPI 

in the open-water season, generally 

being chartered on a seasonal basis or 

long-term contract. Vessels would 

include coastal and ocean-going barges 

and tugs to move large modules and 

equipment and smaller vessels to move 

personnel, supplies, tools, and smaller 

equipment. Barge traffic consisting of 

large ocean-going barges originating 

from Dutch Harbor is likely to consist of 

one-to-two vessels, approximately twoto-five times per year during 

construction, and only one trip every 5 

years during operations. During the first 

2 years following LDPI construction, 

hovercraft may make up to three trips 

per day from Endicott SDI to LDPI. After 

those 2 years, hovercraft may make up 

to two trips per day from Endicott SDI 

to LDPI (approximately 11.3 km [7 mi]). 

Air operations are often limited by 

weather conditions and visibility. In 

general, air access would be used for 

movement of personnel and foodstuffs 

and for movement of supplies or 

equipment when necessary. Fixed-wing 

aircraft may be used on an as-needed 

basis for purposes of spill response 

(spill delineation) and aerial 

reconnaissance of anomalous conditions 

or unless otherwise required by 

regulatory authority. Helicopter use is 

planned for re-supply during the 

broken-ice seasons and access for 

maintenance and inspection of the 

onshore pipeline system. In the period 

between completion of hydro-testing 

and facilities startup, an estimated oneto-two helicopter flights per week are 

also expected for several weeks for 

personnel access and to transport 

equipment to the tie-in area. Typically, 

air traffic routing is as direct as possible 

from departure locations such as the 

SDI, West Dock, or Deadhorse to the 

LDPI, with routes and altitude adjusted 

to accommodate weather, other air 

traffic, and subsistence activities. 

Hilcorp would minimize potential 

disturbance to mammals from helicopter 

flights to support LDPI construction by 

limiting the flights to an established 

corridor from the LPDI to the mainland 

and except during landing and takeoff, 

and these flights would maintain a 

minimum altitude of 457 m (1,500 ft) 

above ground level (AGL) unless 

inclement weather requires deviation. 

Equipment located at the pipeline tie-in 

location and the pipeline shore landing 

would be accessed by helicopter or 

approved tundra travel vehicles to 

minimize impacts to the tundra. 

Additionally, Hilcorp may use 

unmanned aerial surveys (UASs) during 

pile driving, pipe driving, and slope 

shaping and armament activities during 

the open-water season in Year 2 of 

construction and subsequently during 

decommissioning to monitor for whales 

or seals that may occur in incidental 

Level B harassment zones as described 

in the 2019 LOA issued by the National 

Marine Fisheries Service (NMFS 2020). 

Recent developments in the technical 

capacity and civilian use of UASs 

(defined as vehicles flying without a 

human pilot on board) have led to some 

investigations into potential use of these 

systems for monitoring and conducting 

aerial surveys of marine mammals 

(Koski et al. 2009; Hodgson et al. 2013). 

UASs, operating under autopilot and 

mounted with Global Positioning 

System (GPS) and imaging systems, 

have been used and evaluated in the 

Arctic (Koski et al. 2009) and have 

potential to replace traditional manned 

aerial surveys and provide an improved 

method for monitoring marine mammal 

populations. Hilcorp plans to seek a 

waiver, if necessary, from the Federal 

Aviation Administration (FAA) to 

operate the UAS above 122 m (400 ft) 

and beyond the line of sight of the pilot. 

Ground control for the UAS would be 

located at Liberty Island, Endicott, or 

another shore-based facility close to 

Liberty (NMFS 2020). 

After construction, aircraft, land 

vehicle, and marine traffic may be at 

similar levels as those described for 

Northstar Island, although specific 

details beyond those presented here are 

not presently known. 

Ice roads would be used for onshore 

and offshore access, installing the 

pipeline, hauling gravel used to 

construct the island, moving equipment 

on/off the island, and personnel and 

supply transit. Ice road construction can 

typically be initiated in mid- to lateDecember and can be maintained until 

mid-May, weather depending. Ice road 

#1 would extend approximately 11.3 km 

(7 mi) over shorefast sea ice from the 

Endicott SDI to the LDPI (the SDI to 

LDPI ice road). It would be 

approximately 37 m wide (120 ft) with 

a driving lane of approximately 12 m 

(40 ft) and cover approximately 64.8 ha 

(160 ac) of sea ice. Ice road #2 

(approximately 11.3 km [7 mi]) would 

connect the LDPI to the proposed 

Kadleroshilik River gravel mine site and 

then would continue to the juncture 

with the Badami ice road (which is ice 

road #4). It would be approximately 15 

m (50 ft) wide. Ice road #3 

(approximately 9.6 km [6 mi], termed 

the ‘‘Midpoint Access Road’’) would 

intersect the SDI to LDPI ice road and 

the ice road between the LDPI and the 

mine site. It would be approximately 12 

m (40 ft) wide. Ice road #4 

(approximately 19.3 km [12 mi]), 

located completely onshore, would 

parallel the Badami pipeline and 

connect the mine site with the Endicott 

road. 

All four ice roads would be 

constructed for the first 3 years to 

support pipeline installation and 

transportation from existing North Slope 

roads to the proposed gravel mine site, 

and from the mine site to the proposed 

LDPI location in the Beaufort Sea. After 

Year 3, only ice road #1 would be 

constructed to allow additional 

materials and equipment to be 

mobilized to support LDPI, pipeline, 

and facility construction activities as all 

island construction and pipeline 

installation should be complete by Year 

3. In addition to the ice roads, three ice 

pads are proposed to support 

construction activities (Year 2 and Year 

3). These would be used to support 

LDPI, pipeline (including pipe stringing 

and two stockpile/disposal areas), and 

facilities construction. A fourth staging 

area ice pad (approximately 107 by 213 

m (350 by 700 ft) would be built on the 

sea ice on the west side of the LDPI 

during production well drilling 

operations. 

Other on-ice activities occurring prior 

to March 1 may include spill training 

exercises, pipeline surveys, snow 

clearing, and work conducted by other 

snow vehicles such as a Pisten Bully, 

snow machine, or Rolligon. Prior to 

March 1, these activities would occur 

outside of the delineated ice road/trail 

and shoulder areas. 

The LDPI would include a selfcontained offshore drilling and 

production facility located on an 

artificial gravel island with a subsea 

pipeline to shore. The LDPI would be 

located approximately 8 km (5 mi) 

offshore in Foggy Island Bay and 11.7 

km (7.3 mi) southeast of the existing SDI 

on the Endicott causeway. The LDPI 

would be constructed of reinforced 

gravel in 5.8 m (19 ft) of water and have 

a working surface of approximately 3.8 

ha (9.3 ac). A steel sheet pile wall would 

surround the island to stabilize the 

placed gravel, and the island would 

include a slope protection bench, dock 

and ice road access, and a seawater 

intake area. 


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Hilcorp would begin constructing the 

LDPI during the winter immediately 

following construction of the ice road 

from the mine site to the island location. 

Sections of sea ice at the island’s 

location would be cut using a 

ditchwitch and removed. A backhoe and 

support trucks using the ice road would 

move ice away. Once the ice is removed, 

gravel would be poured through the 

water column to the sea floor, building 

the island structure from the bottom up. 

A conical pile of gravel (hauled in from 

trucks from the mine site using the ice 

road) would form on the sea floor until 

it reaches the surface of the ice. Gravel 

hauling over the ice road to the LDPI 

construction site is estimated to 

continue for 50 to 70 days and conclude 

mid-April or earlier depending on road 

conditions. The construction would 

continue with a sequence of removing 

additional ice and pouring gravel until 

the surface size is achieved. 

Following gravel placement, slope 

armoring and protection installation 

would occur. Using island-based 

equipment (e.g., backhoe, bucketdredge) and divers, Hilcorp would 

create a slope protection profile 

consisting of an 18.3-m (60-ft)-wide 

bench covered with a linked concrete 

mat that extends from a sheet pile wall 

surrounding the island to slightly above 

medium lower low water. The linked 

concrete mat requires a high-strength, 

yet highly permeable, woven polyester 

fabric under layer to contain the gravel 

island fill. The filter fabric panels would 

be overlapped and tied together side-byside (requiring diving operations) to 

prevent the panels from separating and 

exposing the underlying gravel fill. 

Because the fabric is overlapped and 

tied together, no slope protection debris 

would enter the water column should it 

be damaged. Above the fabric under 

layer, a robust geo-grid would be placed 

as an abrasion guard to prevent damage 

to the fabric by the linked mat armor. 

The concrete mat system would 

continue at a 3:1 slope another 26.4 m 

(86.5 ft) into the water, terminating at a 

depth of 5.8 m (19 ft). In total, from the 

sheet pile wall, the bench and concrete 

mat would extend 44.7 m (146.5 ft). 

Island slope protection is required to 

ensure the integrity of the gravel island 

by protecting it from the erosive forces 

of waves, ice ride-up, and currents. A 

detailed inspection of the island slope 

protection system would be conducted 

annually during the open-water season 

to document changes in the condition of 

this system that have occurred since the 

previous year’s inspection. Any 

damaged material would be removed. 

Above-water activities would consist of 

a visual inspection of the dock and 

sheet pile enclosure that would 

document the condition of the island 

bench and ramps. The below-water 

slopes would be inspected by divers or, 

if water clarity allows, remotely by 

underwater cameras contracted 

separately by Hilcorp. The results of the 

below-water inspection would be 

recorded for repair if needed. No vessels 

would be required. Multi-beam 

bathymetry and side-scan sonar imagery 

of the below-water slopes and adjacent 

sea bottom would be acquired using a 

bathymetry vessel. The sidescan sonar 

would operate at a frequency between 

200 and 400 kHz. The single-beam 

echosounder would operate at a 

frequency of about 210 kHz. 

Once the slope protection is in place, 

Hilcorp would install the sheet pile wall 

around the perimeter of the island using 

vibratory and, if necessary, impact 

hammers. Sheet pile driving is 

anticipated to be conducted between 

March and August, during 

approximately 4 months of the icecovered season and, if necessary, 

approximately 15 days during the openwater season. Sheet pile driving 

methods and techniques are expected to 

be similar to the installation of sheet 

piles at Northstar during which all pile 

driving was completed during the icecovered season. Therefore, Hilcorp 

anticipates most or all sheet pile would 

be installed during ice-covered 

conditions. Hilcorp anticipates driving 

up to 20 piles per day to a depth of 7.62 

m (25 ft). A vibratory hammer would be 

used first, followed by an impact 

hammer to ‘‘proof’’ the pile. Hilcorp 

anticipates each pile needing 100 

hammer strikes over approximately 2 

minutes (100 strikes) of impact driving 

to obtain the final desired depth for 

each sheet pile. To finish installing up 

to 20 piles per day, the impact hammer 

would be used a maximum of 40 

minutes per day with an anticipated 

duration of 20 minutes per day. 

For vibratory driving, pile penetration 

speed can vary depending on ground 

conditions, but a minimum sheet pile 

penetration speed is 0.5 m (20 in) per 

minute to avoid damage to the pile or 

hammer (NASSPA 2005). For this 

project, the anticipated duration is 

based on a preferred penetration speed 

greater than 1 m (40 in) per minute, 

resulting in 7.5 minutes to drive each 

pile. Given the high storm surge and 

larger waves that are expected to arrive 

at the LDPI site from the west and 

northwest, the wall would be higher on 

the west side than on the east side. At 

the top of the sheet-pile wall, 

overhanging steel ‘‘parapet’’ would be 

installed to prevent wave passage over 

the wall. 

Within the interior of the island, 16 

steel conductor pipes would be driven 

to a depth of 49 m (160 ft) to provide 

the initial stable structural foundation 

for each oil well. They would be set in 

a well row in the middle of the island. 

Depending on the substrate, the 

conductor pipes would be driven by 

impact or vibratory methods or both. 

During the construction of the nearby 

Northstar Island (located in deeper 

water), it took 5 to 8.5 hours to drive 

one conductor pipe (Blackwell et al. 

2004). For the Liberty LDPI, based on 

the 20 percent impact hammer usage 

factor (USDOT 2006.), it is expected that 

two cumulative hours of impact pipe 

driving (4,400 to 3,600 strikes) would 

occur over a 10.5 non-consecutive hour 

day. Conductor pipe driving is 

anticipated to be conducted between 

March and August and take 16 days 

total, installing one pipe per day. In 

addition, approximately 700 to 1,000 

foundation piles may also be installed 

within the interior of the island should 

engineering determine they are 

necessary for island support. 

The LDPI layout includes areas for 

staging, drilling, production, utilities, a 

camp, a relief well, a helicopter landing 

pad, and two docks to accommodate 

barges, a hovercraft, and small crew 

boats. It would also have ramps for ice 

road and amphibious vehicle access. An 

STP would also be located at the facility 

to treat seawater and then commingle it 

with produced water to be injected into 

the Liberty Reservoir to maintain 

reservoir pressure. Treated seawater 

would be used to create potable water 

and utility water for the facility. A 

membrane bioreactor would treat 

sanitary wastewater, and remaining 

sewage solids would be incinerated on 

the island or stored in enclosed tanks 

prior to shipment to Deadhorse for 

treatment. 

All modules, buildings, and material 

for onsite construction would be 

trucked to the North Slope via the 

Dalton Highway and staged at West 

Dock, Endicott SDI, or in Deadhorse. 

Another option is to use ocean-going 

barges from Dutch Harbor to transport 

materials or modules to the island 

during the open-water season. 

Depending on the season, equipment 

and material would be transported via 

coastal barges in open water, or ice 

roads from SDI in the winter. The first 

modules would be delivered in the third 

quarter of Year 2 to support the 

installation of living, drilling, and 

production facilities. Remaining process 

modules would be delivered to 


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correspond with first oil and the rampup in drilling capacity. 

Onsite facility installation would 

commence in August of Year 2 and be 

completed by the end of Year 4 (May) 

to accommodate the overall 

construction and production ramp-up 

schedule. Some facilities that are 

required early would be barged in the 

third quarter of Year 2 and would be 

installed and operational by the end of 

the fourth quarter of Year 2. Other 

modules would be delivered as soon as 

the ice road from SDI is in place. The 

drilling unit and associated equipment 

would be transferred by barge through 

Dutch Harbor or from West Dock to the 

LDPI during the open-water season in 

Year 2 using a seagoing barge and ocean 

class tug. The seagoing barge is ∼30.5 m 

(100 ft) wide and ∼122 m (400 ft) long, 

and the tug is ∼30.5 m (100 ft) long. 

Although the exact vessels to be used 

are unknown, Crowley lists Ocean class 

tugs at <1,600 gross registered tonnage. 

The weight of the seagoing barge is not 

known at this time. 

Hilcorp would install a pipe-in-pipe 

subsea pipeline consisting of a 30.5-cm 

(12-in)-diameter inner pipe and a 40.6- 

cm (16-in)-diameter outer pipe to 

transport oil from the LDPI to the 

existing Badami pipeline. Pipeline 

construction is planned for the winter 

after the island is constructed. A 

schematic of the pipeline can be found 

in Figure 2–3 of BOEM’s Final EIS 

available at https://www.boem.gov/ 

Hilcorp-Liberty/. The pipeline would 

extend from the LDPI, across Foggy 

Island Bay, and terminate onshore at the 

existing Badami Pipeline tie-in location. 

For the marine segment, construction 

would progress from shallower water to 

deeper water with multiple construction 

spreads. 

To install the pipeline, a trench 

would be excavated using ice-roadbased long-reach excavators with 

pontoon tracks. The pipeline bundle 

would be lowered into the trench using 

side booms to control its vertical and 

horizontal position, and the trench 

would be backfilled by excavators using 

excavated trench spoils and select 

backfill. Hilcorp intends to place all 

material back in the trench slot. All 

work would be done from ice roads 

using conventional excavation and dirtmoving construction equipment. The 

target trench depth is 2.7 to 3.4 m (9 to 

11 ft) with a proposed maximum depth 

of cover of approximately 2.1 m (7 ft). 

The pipeline would be approximately 9 

km (5.6 mi) long. 

At the pipeline landfall (where the 

pipeline transitions from onshore to 

offshore), Hilcorp would construct an 

approximately 0.6-ha (1.4-ac) trench to 

protect against coastal erosion and ice 

ride-up associated with onshore sea ice 

movement and to accommodate the 

installation of thermosiphons (heat 

pipes that circulate fluid based on 

natural convection to maintain or cool 

ambient ground temperature) along the 

pipeline. The onshore pipeline would 

cross the tundra for almost 2.4 km (1.5 

mi) until it intersects the existing 

Badami pipeline system. The single wall 

30.5-cm (12-in) pipeline would rest on 

150 to 170 VSMs, spaced approximately 

15 m (50 ft) apart to provide the 

pipeline a minimum 2.1-m (7-ft) 

clearance above the tundra. Hydrotesting (pressure testing using sea water) 

of the entire pipeline would be required 

to complete pipeline commissioning. 

The final drill rig has yet to be chosen 

but has been narrowed to 2 options and 

would accommodate drilling of 16 

wells. The first option is the use of an 

existing platform-style drilling unit that 

Hilcorp owns and operates in the Cook 

Inlet. Designated as Rig 428, the rig has 

been used recently and is well suited in 

terms of depth and horsepower rating to 

drill the wells at Liberty. A second 

option that is being investigated is a 

new build drilling unit that would be 

built not only to drill Liberty 

development wells but would be more 

portable and more adaptable to other 

applications on the North Slope. 

Regardless of drill rig type, the well row 

arrangement on the island is designed to 

accommodate up to 16 wells. While 

Hilcorp is proposing a 16-well design, 

only 10 wells would be drilled. The six 

additional well slots would be available 

as backups or for potential in-fill 

drilling if needed during the project life. 

Drilling would be done using a 

conventional rotary drilling rig, initially 

powered by diesel, and eventually 

converted to fuel gas produced from the 

third well. Gas from the third well 

would also replace diesel fuel for the 

grind-and-inject facility and production 

facilities. A location on the LDPI is 

designated for drilling a relief well, if 

needed. 

Process facilities on the island would 

separate crude oil from produced water 

and gas. Gas and water would be 

injected into the reservoir to provide 

pressure support and increase recovery 

from the field. A single-phase subsea 

pipe-in-pipe pipeline would transport 

sales-quality crude from the LDPI to 

shore, where an aboveground pipeline 

would transport crude to the existing 

Badami pipeline. From there, crude 

would be transported to the Endicott 

Sales Oil Pipeline, which ties into Pump 

Station 1 of the TAPS for eventual 

delivery to a refinery. 

North Slope Gas Development 

The AOGA Request discusses two 

projects currently submitted for 

approval and permitting that would 

transport natural gas from the North 

Slope via pipeline. Only a small fraction 

of this project would fall within the 40- 

km (25-mi) inland jurisdiction area of 

this ITR. The two projects are the Alaska 

Liquified Natural Gas Project (Alaska 

LNG) and the Alaska Stand Alone 

Pipeline (ASAP). Both of these projects 

are discussed below and their effects 

analyzed in this ITR, but only one 

project could be constructed during the 

2021–2026 period. 

Alaska Liquefied Natural Gas Project 

(Alaska LNG) 

The Alaska LNG project has been 

proposed by the Alaska Gasline 

Development Corporation (AGDC) to 

serve as a single integrated project with 

several facilities designed to liquefy 

natural gas. The fields of interest are the 

Point Thomson Unit (PTU) and PBU 

production fields. The Alaska LNG 

project would consist of a Gas 

Treatment Plant (GTP); a Point 

Thomson Transmission Line (PTTL) to 

connect the GTP to the PTU gas 

production facility; a Prudhoe Bay 

Transmission Line (PBTL) to connect 

the GTP to the PBU gas production 

facility; a liquefaction facility in 

southcentral Alaska; and a 1,297-km 

(807-mi)-long, 107-cm (42-in)-diameter 

pipeline (called the Mainline) that 

would connect the GTP to the 

liquefaction facility. Only the GTP, 

PTTL, PBTL, a portion of the Mainline, 

and related ancillary facilities would be 

located within the geographic scope of 

AOGA’s Request. Related components 

would require the construction of ice 

roads, ice pads, gravel roads, gravel 

pads, camps, laydown areas, and 

infrastructure to support barge and 

module offloading. 

Barges would be used to transport 

GTP modules at West Dock at Prudhoe 

Bay several times annually, with GTP 

modules being offloaded and 

transported by land to the proposed 

GTP facility in the PBU. However, 

deliveries would require deep draft tug 

and barges to a newly constructed 

berthing site at the northeast end of 

West Dock. Additionally, some barges 

would continue to deliver small 

modules and supplies to Point 

Thomson. Related activities include 

screeding, shallow draft tug use, sea ice 

cutting, gravel placement, sea ice road 

and sea ice pad development, vibratory 

and impact pile driving, and the use of 

an offshore barge staging area. 


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A temporary bridge (developed from 

ballasted barges) would be developed to 

assist in module transportation. Barges 

would be ballasted when the area is icefree and then removed and 

overwintered at West Dock before the 

sea freezes over. A staging area would 

then be used to prepare modules for 

transportation, maintenance, and gravel 

road development. Installation of ramps 

and fortification would utilize vibratory 

and impact pile driving. Seabed 

preparations and level surface 

preparations (i.e., ice cutting, ice road 

development, gravel placement, 

screeding) would take place as needed. 

Breasting/mooring dolphins would be 

installed at the breach point via pile 

driving to anchor and stabilize the 

ballasted barges. 

A gravel pad would be developed to 

assist construction of the GTP, adjacent 

camps, and other relevant facilities 

where work crews utilize heavy 

equipment and machinery to assemble, 

install, and connect the GTP modules. 

To assist, gravel mining would use 

digging and blasting, and gravel would 

be placed to create pads and develop or 

improve ice and gravel roads. 

Several types of development and 

construction would be required at 

different stages of the project. The 

construction of the Mainline would 

require the use of ice pads, ice roads, 

gravel roads, chain trenchers, crane 

booms, backhoes, and other heavy 

equipment. The installation of the PTTL 

and PBTL would require ice roads, ice 

pads, gravel roads, crane booms, mobile 

drills or augers, lifts, and other heavy 

equipment. After installation, crews 

would work on land and streambank 

restoration, revegetation, hydrostatic 

testing, pipeline security, and 

monitoring efforts. The development of 

the ancillary facility would require the 

construction of ice roads, ice pads, as 

well as minimal transportation and 

gravel placement. 

Alaska Stand Alone Pipeline (ASAP) 

The ASAP is the alternative project 

option that AGDC could utilize, 

allowing North Slope natural gas to be 

supplied to Alaskan communities. 

ASAP would require several 

components, including a Gas 

Conditioning Facility (GCF) at Prudhoe 

Bay; a 1,180-km (733-mi)-long, 0.9-m 

(36-in)-diameter pipeline that would 

connect the GCF to a tie-in found in 

southcentral Alaska (called the 

Mainline); and a 48-km (30-m), 0.3-m 

(12-in)-diameter lateral pipeline 

connecting the Mainline pipeline to 

Fairbanks (referred to as the Fairbanks 

Lateral). Similar to the Alaska LNG 

pipeline, only parts of this project 

would fall within the geographic scope 

of this ITR. These relevant project 

components are the GCF, a portion of 

the ASAP Mainline, and related 

ancillary facilities. Construction would 

include the installation of supporting 

facilities and infrastructure, ice road 

and pad development, gravel road and 

pad development, camp establishment, 

laydown area establishment, and 

additional infrastructure to support 

barge and module offloading. 

Barges would be used to transport the 

GCF modules to West Dock in Prudhoe 

Bay and would be offloaded and 

transported by ground to the proposed 

facility site within the PBU. Module and 

supply deliveries would utilize deep 

draft tugs and barges to access an 

existing berthing location on the 

northeast side of West Dock called DH3. 

Maintenance on DH3 would be required 

to accommodate the delivery of larger 

loads and would consist of 

infrastructure reinforcement and 

elevation increases on one of the berths. 

In the winter, a navigational channel 

and turn basin would be dredged to a 

depth of 2.7 m (9 ft). Dredged material 

would be disposed of on ground-fast ice 

found in 0.6–1.2 m (2–4 ft) deep water 

in Prudhoe Bay. An offshore staging 

area would be developed approximately 

4.8–8 km (3–5 mi) from West Dock to 

allow deep draft tugs and barges to stage 

before further transportation to DH3 and 

subsequent offload by shallow draft 

tugs. Other activities include seabed 

screeding, gravel placement, 

development of a sea ice road and pads, 

and pile driving (vibratory and impact) 

to install infrastructure at West Dock. 

A temporary bridge (composed of 

ballasted barges and associated 

infrastructure) paralleling an existing 

weight-limited bridge would be 

developed to assist in transporting large 

modules off West Dock. Barges would 

be ballasted when the area is ice-free 

and then removed and overwintered at 

West Dock before the sea freezes over. 

A staging area would be used to prepare 

modules for transportation, 

maintenance, and gravel road 

development. The bridge construction 

would require ramp installation, 

fortification through impact, and 

vibratory pile driving. Support activities 

(development of ice roads and pads, 

gravel roads and pads, ice cutting, 

seabed screeding) would also take place. 

Breasting/mooring dolphins would be 

installed at the breach point via pile 

driving to anchor and stabilize the 

ballasted barges. 

A gravel facility pad would be formed 

to assist in the construction of the GCF. 

Access roads would then be developed 

to allow crews and heavy equipment to 

install and connect various GCF 

modules. Gravel would be obtained 

through digging, blasting, 

transportation, gravel pad placement, 

and improvements to other ice and 

gravel roads. 

The construction of the Mainline 

pipeline would require the construction 

of ice pads, ice roads, and gravel roads 

along with the use of chain trenchers, 

crane booms, backhoes, and other heavy 

equipment. Block valves would be 

installed above ground along the length 

of the Mainline. After installation, crews 

would work on land and streambank 

restoration, revegetation, hydrostatic 

testing, pipeline security, and 

monitoring efforts. 

Pikka Unit 

The Pikka Development (formally 

known as the Nanshuk Project) is 

located approximately 83.7 km (52 mi) 

west of Deadhorse and 11.3 km (7 mi) 

northeast of Nuiqsut. Oil Search Alaska 

operates leases held jointly between the 

State of Alaska and ASRC located 

southeast of the East Channel of the 

Colville River. Pikka is located further 

southwest from the existing Oooguruk 

Development Project, west of the 

existing KRU, and east of Alpine and 

Alpine’s Satellite Development Projects. 

Most of the infrastructure is located over 

8 km (5 mi) from the coast within the 

Pikka Unit; however, Oil Search Alaska 

expects some smaller projects and 

activities to occur outside the unit to the 

south, east, and at Oliktok Point. 

The Pikka Project would include a 

total of 3 drill-sites for approximately 

150 (production, injectors, underground 

injection) wells, as well as the Nanshuk 

Processing Facility (NPF), the Nanushuk 

Operations Pad, a tie-in pad (TIP), 

various camps, warehouses, facilities on 

pads, infield pipelines, pipelines for 

import and export activities, various 

roads (ice, infield, access), a boat ramp, 

and a portable water system. 

Additionally, there are plans to expand 

the Oliktok Dock and to install an STP 

adjacent to the already existing 

infrastructure. A make-up water 

pipeline would also be installed from 

the STP to the TIP. Oil Search Alaska 

also plans to perform minor upgrades 

and maintenance, as necessary, to the 

existing road systems to facilitate 

transportation of sealift modules from 

Oliktok Point to the Pikka Unit. 

Oil Search Alaska plans to develop a 

pad to station the NPF and all relevant 

equipment and operations (i.e., phase 

separation, heating and cooling, 

pumping, gas treatment and 

compression for gas injections, water 

treatment for injection). All oil 

procured, processed, and designated for 


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sale would travel from the NPF to the 

TIP near Kuparuk’s CPF 2 via the Pikka 

Project pipeline that would tie in to the 

Kuparuk Sales Pipeline and would then 

be transported to TAPS. Construction of 

the pad would allow for additional 

space that could be repurposed for 

drilling or for operational use during the 

development of the Pikka Project. This 

pad would contain other facilities 

required for project operation and 

development, including: Metering and 

pigging facilities; power generation 

facilities; a truck fill station; 

construction material staging areas; 

equipment staging areas; a tank farm 

(contains diesel, refined fuel, crude oil, 

injection water, production chemicals, 

glycol, and methanol storage tanks); and 

a central control room. All major 

components required for the 

development of the NPF would be 

constructed off-site and brought in via 

truck or barge during the summer 

season. Barges would deliver and 

offload necessary modules at Oliktok 

Dock, which would travel to the NPF 

site during summer months. Seabed 

screeding would occur at Oliktok Point 

to maintain water depth for necessary 

barges. 

Pikka would use gravel roads to the 

Unit, which would allow year-round 

access from the Dalton Highway. All 

gravel needed for project activities 

(approximately 112 ha [276 ac]) would 

be sourced from several existing gravel 

mine sites. A majority of gravel 

acquisition and laying would occur 

during the winter season and then be 

compacted in the summer. All 

equipment and supplies necessary 

would be brought in on existing roads 

from Anchorage or Fairbanks to 

Deadhorse. Supplies and equipment 

would then be forwarded to the Pikka 

Unit; no aerial transportation for 

supplies is expected. Regular traffic is 

expected once construction of the roads 

is completed; Oil Search Alaska expects 

arterial routes between the processing 

facilities and camps to experience the 

heaviest use of traffic. Drill-site access 

roads are expected to experience the 

least amount of traffic; however, drillsite traffic is expected to increase 

temporarily during periods of active 

drilling, maintenance, or other relevant 

aspects of the project. Standard vehicles 

would include light passenger trucks, 

heavy tractor-trailer trucks, heavy 

equipment, and oil rigs. 

Several types of aircraft operations are 

expected at the Pikka Unit throughout 

the 2021–2026 period. Personnel would 

be transported to Pikka via commercial 

flights from Deadhorse Airport and by 

ground-based vehicle transport. 

Currently, there is no plan to develop an 

airstrip at Pikka. Personnel flights are 

expected to be infrequent to and from 

the Pikka Unit; however, Oil Search 

Alaska expects that some transport 

directly to the Unit may be required. 

Several environmental studies 

performed via aircraft are expected 

during the ITR period. Some of these 

include AIR surveys, cultural resources, 

stick-picking, and hydrology studies. 

AIR surveys in support of the Pikka Unit 

would occur annually to locate polar 

bear dens. 

Summer travel would utilize vehicles 

such as Rolligons and Tuckers to assess 

pipelines not found adjacent to the 

gravel roads. During 24-hour sunlight 

periods, these vehicles would operate 

across all hours. Stick-picking and 

thermistor retrieval would also occur in 

the summer. In the winter, ice roads 

would be constructed across the Unit. 

These ice roads would be developed to 

haul gravel from existing mine sites to 

haul gravel for road and pad 

construction. Ice roads would also be 

constructed to support the installation 

of VSM and pipelines. Off-road winter 

vehicles would be used when the tundra 

is frozen and covered with snow to 

provide maintenance and access for 

inspection. Temporary ice roads and ice 

pads would be built to allow for the 

movement and staging of heavy 

equipment, maintenance, and 

construction. Oil Search Alaska would 

perform regular winter travel to support 

operations across the Pikka Unit. 

Oil Search Alaska plans to install a 

bridge over the Kachemach River (more 

than 8 km [5 mi] from the coast) and 

install the STP at Oliktok Point. Both 

projects would require in-water pile 

driving, which is expected to take place 

during the winter seasons. In-water pile 

driving (in the winter), placement of 

gravel fill (open-water period), and 

installation of the STP barge outfall 

structure (open-water period) would 

take place at Oliktok Point. Dredging 

and screeding activities would prepare 

the site for STP and module delivery via 

barge. Annual maintenance screeding 

and dredging (expected twice during the 

Request period) may be needed to 

maintain the site. Dredging spoils would 

be transported away, and all work 

would occur during the open-water 

season between May and October. 

Screeding activities are expected to take 

place annually over the course of a 2- 

week period, depending on stability and 

safety needs. 

Gas Hydrate Exploration and Research 

The U.S. Geological Survey (USGS) 

estimates that the North Slope contains 

over 54 trillion cubic feet of recoverable 

gas assets (Collette et al. 2019). Over the 

last 5 years, Industry has demonstrated 

a growing interest in the potential to 

explore and extract these reserves. 

Federal funds from the Department of 

Energy have been provided in the past 

to support programs on domestic gas 

hydrate exploration, research, and 

development. Furthermore, the State of 

Alaska provides support for gas hydrate 

research and development through the 

development of the Eileen hydrate trend 

deferred area near Milne Point, with 

specific leases being offered for gas 

hydrate research and exploration. 

As of 2021, a few gas hydrate 

exploration and test wells have been 

drilled within the Beaufort Sea region. 

Due to the support the gas hydrate 

industry has received, AOGA expects 

continued interest to grow over the 

years. As such, AOGA expects that a 

relatively low but increasing amount of 

gas hydrate exploration and research is 

expected throughout the 2021–2026 

period. 

Environmental Studies 

Per AOGA’s Request, Industry would 

continue to engage in various 

environmental studies throughout the 

life of the ITR. Such activities include: 

Geological and geotechnical surveys 

(i.e., seismic surveys); surveys on 

geomorphology (soils, ice content, 

permafrost), archeology and cultural 

resources; vegetation mapping; analysis 

of fish, avian, and mammal species and 

their habitats; acoustic monitoring; 

hydrology studies; and various other 

freshwater, marine, and terrestrial 

studies of the coastal and offshore 

regions within the Arctic. These studies 

typically include various stakeholders, 

including consultants and consulting 

companies; other industries; 

government; academia (universitylevel); nonprofits and nongovernmental 

organizations; and local community 

parties. However, AOGA’s 2021–2026 

ITR Request seeks coverage only for 

environmental studies directly related 

to Industry activities (e.g., monitoring 

studies in response to regulatory 

requirements). No third-party studies 

will be covered except by those 

mentioned in this ITR and the AOGA 

Request. 

During the 2021–2026 lifespan of the 

ITR, Industry would continue studies 

that are conducted for general 

monitoring purposes for regulatory and/ 

or permit requirements and for expected 

or planned exploration and 

development activities within the 

Beaufort Sea region. Environmental 

studies are anticipated to occur during 

the summer season as to avoid overlap 

with any denning polar bears. Activities 


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may utilize vessels, fixed-wing aircrafts, 

or helicopters to access research sites. 

Mitigation Measures 

AOGA has included in their Request 

a number of measures to mitigate the 

effects of the proposed activities on 

Pacific walruses and polar bears. Many 

of these measures have been historically 

used by oil and gas entities throughout 

the North Slope of Alaska and have 

been developed as a part of past 

coordination with the Service. Measures 

include: Development and adherence to 

polar bear and Pacific walrus interaction 

plans; design of facilities to reduce the 

possibility of polar bears reaching 

attractants; avoidance of operating 

equipment near potential den locations; 

flying aircraft at a minimum altitude 

and distance from polar bears and 

hauled out Pacific walruses; employing 

trained protected species observers; and 

reporting all polar bear or Pacific walrus 

encounters to the Service. Additional 

descriptions of these measures can be 

found in the AOGA Request for an ITR 

at: www.regulations.gov in Docket No. 

FWS–R7–ES–2021–0037. 

Maternal Polar Bear Den Survey Flights 

Per AOGA’s Request, Industry will 

also conduct aerial infrared (AIR) 

surveys to locate maternal polar bear 

dens in order to mitigate potential 

impacts to mothers and cubs during the 

lifetime of this ITR. AIR surveys are 

used to detect body heat emitted by 

polar bears, which, in turn, is used to 

determine potential denning polar 

bears. AIR surveys are performed in 

winter months (December or January) 

before winter activities commence. AIR 

imagery is analyzed in real-time during 

the flight and then reviewed post-flight 

with the Service to identify any 

suspected maternal den locations, 

ensure appropriate coverage, and check 

the quality of the images and recordings. 

Some sites may need to be resurveyed 

if a suspected hotspot (heat signature 

detectable in a snowdrift) is observed. 

These followup surveys of hotspots are 

conducted in varying weather 

conditions or using an electro-optical 

camera during daylight hours. On-theground reconnaissance or the use of 

scent-training dogs may also be used to 

recheck the suspected den. 

Surveys utilize AIR cameras on fixedwing aircrafts with flights typically 

flown between 245–457 meters (800– 

1,500 feet) above ground level at a speed 

of <185 km/h (<115 mph). Surveys 

typically occur twice a day (weather 

permitting) during periods of darkness 

(civil twilight) across the North Slope 

for less than 4.5 hours per survey. 

Surveys are highly dependent on the 

weather as it can affect the image 

quality of the AIR video and the safety 

of the participants. These surveys do not 

follow a typical transect configuration; 

instead they are concentrated on areas 

that would be suitable for polar bear 

denning activity such as drainages, 

banks, bluffs, or other areas of 

topographic relief around sites where 

Industry has winter activities, tundra 

travel, or ice road construction planned 

or anticipated. As part of AOGA’s 

Request and as described in the 

mitigation measures included in this 

ITR, all denning habitat within 1 mile 

of the ice-season industrial footprint 

will be surveyed twice each year. In 

years where seismic surveys are 

proposed, all denning habitat within the 

boundaries of the seismic surveys will 

be surveyed three times, and a third 

survey will be conducted on denning 

habitat along the pipeline between 

Badami and the road to Endicott Island. 

Greater detail on the timing of these 

surveys can be found in Methods for 

Modeling the Effects of Den 

Disturbance. 

A suspected heat signature observed 

in a potential den found via AIR is 

classified into three categories: A 

hotspot, a revisit, or a putative den. The 

following designations are discussed 

below. 

A ‘‘hotspot’’ is a warm spot found on 

the AIR camera indicative of a polar 

bear den through the examination of the 

size and shape near the middle of the 

snow drift. Signs of wildlife presence 

(e.g., digging, tracks) may be present and 

visible. Suspected dens that are open 

(i.e., not drifted closed by the snow) are 

considered hotspots because polar bears 

may dig multiple test evacuation sites 

when searching for an appropriate place 

to den and unused dens will cool down 

and be excluded from consideration. 

Hotspots are reexamined and either 

eliminated or upgraded to a ‘‘putative 

den’’ designation. Industry 

representatives, in coordination and 

compliance with the Service, may 

utilize other methods outside of AIR to 

gather additional information on a 

suspected hotspot. 

A ‘‘revisit’’ is a designation for a 

warm spot in a snowdrift but lacking 

signs of a polar bear den (e.g., tailings 

pile, signs of animal activity, 

appropriate shape or size). These 

categorizations are often revisited 

during a subsequent survey, upgraded to 

a ‘‘hotspot’’ designation, or eliminated 

from further consideration pending the 

evidence presented. 

A ‘‘putative den’’ is a hotspot that has 

maintained a distinct heat signature 

longer than a day and is found within 

the appropriate habitat. The area may 

show evidence of an animal’s presence 

that may not definitively be attributed to 

a non-polar bear species or cause (e.g., 

a fox or other animal digging). The final 

determination is often unknown as 

these sites are not investigated further, 

monitored, or revisited in the spring. 

When and if a putative den is found 

near planned or existing infrastructure 

or activities, the Industry 

representatives will immediately cease 

operations within 1 mile of the location 

and coordinate with the Service to 

mitigate any potential disturbances 

while further information is obtained. 

Evaluation of the Nature and Level of 

Activities 

The annual level of activity at existing 

production facilities in the Request will 

be similar to that which occurred under 

the previous regulations. The increase 

in the area of the industrial footprint 

with the addition of new facilities, such 

as drill pads, pipelines, and support 

facilities, is at a rate consistent with 

prior 5-year regulatory periods. 

Additional onshore and offshore 

facilities are projected within the 

timeframe of these regulations and will 

add to the total permanent activities in 

the area. This rate of expansion is 

similar to prior production schedules. 

Description of Marine Mammals in the 

Specified Geographic Region 

Polar Bear 

Polar bears are distributed throughout 

the ice-covered seas and adjacent coasts 

of the Arctic region. The current total 

polar bear population is estimated at 

approximately 26,000 individuals (95 

percent Confidence Interval (CI) = 

22,000–31,000, Wiig et al. 2015; Regehr 

et al. 2016) and comprises 19 stocks 

ranging across 5 countries and 4 

ecoregions that reflect the polar bear 

dependency on sea-ice dynamics and 

seasonality (Amstrup et al. 2008). Two 

stocks occur in the United States 

(Alaska) with ranges that extend to 

adjacent countries: Canada (the 

Southern Beaufort Sea (SBS) stock) and 

the Russia Federation (the Chukchi/ 

Bering Seas stock). The discussion 

below is focused on the Southern 

Beaufort Sea stock of polar bears, as the 

proposed activities in this ITR would 

overlap only their distribution. 

Polar bears typically occur at low, 

uneven densities throughout their 

circumpolar range (DeMaster and 

Stirling 1981, Amstrup et al. 2011, 

Hamilton and Derocher 2019) in areas 

where the sea is ice-covered for all or 

part of the year. They are typically most 

abundant on sea-ice, near polynyas (i.e., 

areas of persistent open water) and 


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fractures in the ice, and over relatively 

shallow continental shelf waters with 

high marine productivity (Durner et al. 

2004). This sea-ice habitat favors 

foraging for their primary prey, ringed 

seals (Pusa hispida), and other species 

such as bearded seals (Erignathus 

barbatus) (Thiemann et al. 2008, Cherry 

et al. 2011, Stirling and Derocher 2012). 

Although over most of their range polar 

bears prefer to remain on the sea-ice 

year-round, an increasing proportion of 

stocks are spending prolonged periods 

of time onshore (Rode et al. 2015, 

Atwood et al. 2016b). While time spent 

on land occurs primarily in late summer 

and autumn (Rode et al. 2015, Atwood 

et al. 2016b), they may be found 

throughout the year in the onshore and 

nearshore environments. Polar bear 

distribution in coastal habitats is often 

influenced by the movement of seasonal 

sea ice (Atwood et al. 2016b, Wilson et 

al. 2017) and its direct and indirect 

effects on foraging success and, in the 

case of pregnant females, also 

dependent on availability of suitable 

denning habitat (Durner et al. 2006, 

Rode et al. 2015, Atwood et al. 2016b). 

In Alaska during the late summer/fall 

period (July through November), polar 

bears from the Southern Beaufort Sea 

stock often occur along the coast and 

barrier islands, which serve as travel 

corridors, resting areas, and to some 

degree, foraging areas. Based on 

Industry observations and coastal 

survey data acquired by the Service 

(Wilson et al. 2017), encounter rates 

between humans and polar bears are 

higher during the fall (July to 

November) than in any other season, 

and an average of 140 polar bears may 

occur on shore during any week during 

the period July through November 

between Utqiagvik and the Alaska— 

Canada border (Wilson et al. 2017). The 

length of time bears spend in these 

coastal habitats has been linked to sea 

ice dynamics (Rode et al. 2015, Atwood 

et al. 2016b). The remains of 

subsistence-harvested bowhead whales 

at Cross and Barter islands provide a 

readily available food attractant in these 

areas (Schliebe et al. 2006). However, 

the contribution of bowhead carcasses 

to the diet of SBS polar bears varies 

annually (e.g., estimated as 11–26 

percent and 0–14 percent in 2003 and 

2004, respectively) and by sex, likely 

depending on carcass and seal 

availability as well as ice conditions 

(Bentzen et al. 2007). 

Polar bears have no natural predators 

(though cannibalism is known to occur; 

Stirling et al. 1993, Amstrup et al. 

2006b). However, their life-history (e.g., 

late maturity, small litter size, 

prolonged breeding interval) is 

conducive to low intrinsic population 

growth (i.e., growth in the absence of 

human-caused mortality), which was 

estimated at 6 percent to 7.5 percent for 

the SBS stock during 2004–2006 (Regehr 

et al. 2010; Hunter et al. 2010). The 

lifespan of wild polar bears is 

approximately 25 years (Rode et al. 

2020). Females reach sexual maturity at 

3–6 years old giving birth 1 year later 

(Ramsay and Stirling 1988). In the SBS 

region, females typically give birth at 5 

years old (Lentfer & Hensel 1980). On 

average, females in the SBS produce 

litter sizes of 1.9 cubs (SD=0.5; Smith et 

al. 2007, 2010, 2013; Robinson 2014) at 

intervals that vary from 1 to 3 or more 

years depending on cub survival 

(Ramsay and Stirling 1988) and foraging 

conditions. For example, when foraging 

conditions are unfavorable, polar bears 

may delay reproduction in favor of 

survival (Derocher and Stirling 1992; 

Eberhardt 2002). The determining factor 

for growth of polar bear stocks is adult 

female survival (Eberhardt 1990). In 

general, rates above 90 percent are 

essential to sustain polar bear stocks 

(Amstrup and Durner 1995) given low 

cub litter survival, which was estimated 

at 50 percent (90 percent CI: 33–67 

percent) for the SBS stock during 2001– 

2006 (Regehr et al. 2010). In the SBS, 

the probability that adult females will 

survive and produce cubs-of-the-year is 

negatively correlated with ice-free 

periods over the continental shelf 

(Regehr et al. 2007a). In general, 

survival of cubs-of-the-year is positively 

related to the weight of the mother and 

their own weight (Derocher and Stirling 

1996; Stirling et al. 1999). 

Females without dependent cubs 

typically breed in the spring (Amstrup 

2003, Stirling et al. 2016). Pregnant 

females enter maternity dens between 

October and December (Durner et al. 

2001; Amstrup 2003), and young are 

usually born between early December 

and early January (Van de Velde et al. 

2003). Only pregnant females den for an 

extended period during the winter 

(Rode et al. 2018). Other polar bears 

may excavate temporary dens to escape 

harsh winter conditions; however, 

shelter denning is rare for Alaskan polar 

bear stocks (Olson et al. 2017). 

Typically, SBS females denning on 

land emerge from the den with their 

cubs around mid-March (median 

emergence: March 11, Rode et al. 2018, 

USGS 2018), and commonly begin 

weaning when cubs are approximately 

2.3–2.5 years old (Ramsay and Stirling 

1986, Arnould and Ramsay 1994, 

Amstrup 2003, Rode 2020). Cubs are 

born blind, with limited fat reserves, 

and are able to walk only after 60–70 

days (Blix and Lentfer 1979; Kenny and 

Bickel 2005). If a female leaves a den 

during early denning, cub mortality is 

likely to occur due to a variety of factors 

including susceptibility to cold 

temperatures (Blix and Lentfer 1979, 

Hansson and Thomassen 1983, Van de 

Velde 2003), predation (Derocher and 

Wiig 1999, Amstrup et al. 2006b), and 

mobility limitations (Lentfer 1975). 

Therefore, it is thought that successful 

denning, birthing, and rearing activities 

require a relatively undisturbed 

environment. A more detailed 

description of the potential 

consequences of disturbance to denning 

females can be found below in Potential 

Effects of Oil and Gas Industry Activities 

on Pacific Walrus, Polar Bear, and Prey 

Species: Polar Bear: Effects to Denning 

Bears. Radio and satellite telemetry 

studies indicate that denning can occur 

in multiyear pack ice and on land 

(Durner et al. 2020). The proportion of 

dens on land has been increasing along 

the Alaska region (34.4 percent in 1985– 

1995 to 55.2 percent in 2007–2013; 

Olson et al. 2017) likely in response to 

reductions in stable old ice, which is 

defined as sea ice that has survived at 

least one summer’s melt (Bowditch 

2002), increases in unconsolidated ice, 

and lengthening of the melt season 

(Fischbach et al. 2007, Olson et al. 

2017). If sea-ice extent in the Arctic 

continues to decrease and the amount of 

unstable ice increases, a greater 

proportion of polar bears may seek to 

den on land (Durner et al. 2006, 

Fischbach et al. 2007, Olson et al. 2017). 

In Alaska, maternal polar bear dens 

occur on barrier islands (linear features 

of low-elevation land adjacent to the 

main coastline that are separated from 

the mainland by bodies of water), river 

bank drainages, and deltas (e.g., those 

associated with the Colville and 

Canning Rivers), much of the North 

Slope coastal plain (in particular within 

the 1002 Area, i.e., the land designated 

in section 1002 of the Alaska National 

Interest Lands Conservation Act—part 

of ANWR in northeastern Alaska; 

Amstrup 1993, Durner et al. 2006), and 

coastal bluffs that occur at the interface 

of mainland and marine habitat (Durner 

et al. 2006, 2013, 2020; Blank 2013; 

Wilson and Durner 2020). These types 

of terrestrial habitat are also designated 

as critical habitat for the polar bear 

under the Endangered Species Act (75 

FR 76086, December 7, 2010). 

Management and conservation concerns 

for the SBS and Chukchi/Bering Seas 

(CS) polar bear stocks include sea-ice 

loss due to climate change, human–bear 

conflict, oil and gas industry activity, oil 

spills and contaminants, marine 

shipping, disease, and the potential for 


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overharvest (Regehr et al. 2017; U.S. 

Fish and Wildlife Service 2016). 

Notably, reductions in physical 

condition, growth, and survival of polar 

bears have been associated with 

declines in sea-ice (Rode et al. 2014, 

Bromaghin et al. 2015, Regehr et al. 

2007, Lunn et al. 2016). The attrition of 

summer Arctic sea-ice is expected to 

remain a primary threat to polar bear 

populations (Amstrup et al. 2008, 

Stirling and Derocher 2012), since 

projections indicate continued climate 

warming at least through the end of this 

century (Atwood et al. 2016a, IPCC 

2014) (see section on Climate Change for 

further details). 

In 2008, the Service listed polar bears 

as threatened under the Endangered 

Species Act of 1973, as amended (16 

U.S.C. 1531 et seq.; ESA) due to the loss 

of sea-ice habitat caused by climate 

change (73 FR 28212, May 15, 2008). 

The Service later published a final rule 

under section 4(d) of the ESA for the 

polar bear, which was vacated and then 

reinstated when procedural 

requirements were satisfied (78 FR 

11766, February 20, 2013). This section 

4(d) rule provides for measures that are 

necessary and advisable for the 

conservation of polar bears. Specifically, 

the 4(d) rule: (a) Adopts the 

conservation regulatory requirements of 

the MMPA and the Convention on 

International Trade in Endangered 

Species of Wild Fauna and Flora 

(CITES) for the polar bear as the 

appropriate regulatory provisions, in 

most instances; (b) provides that 

incidental, nonlethal take of polar bears 

resulting from activities outside the 

bear’s current range is not prohibited 

under the ESA; (c) clarifies that the 4(d) 

rule does not alter the section 7 

consultation requirements of the ESA; 

and (d) applies the standard ESA 

protections for threatened species when 

an activity is not covered by an MMPA 

or CITES authorization or exemption. 

The Service designated critical habitat 

for polar bear populations in the United 

States effective January 6, 2011 (75 FR 

76086, December 7, 2010). The 

designation of critical habitat identifies 

geographic areas that contain features 

that are essential for the conservation of 

a threatened or endangered species and 

that may require special management or 

protection. Under section 7 of the ESA, 

if there is a Federal action, the Service 

will analyze the potential impacts of the 

action upon polar bears and any 

designated critical habitat. Polar bear 

critical habitat units include barrier 

island habitat, sea-ice habitat (both 

described in geographic terms), and 

terrestrial denning habitat (a functional 

determination). Barrier island habitat 

includes coastal barrier islands and 

spits along Alaska’s coast; it is used for 

denning, refuge from human 

disturbance, access to maternal dens 

and feeding habitat, and travel along the 

coast. Sea-ice habitat is located over the 

continental shelf and includes water 

300 m (∼984 ft) or less in depth. 

Terrestrial denning habitat includes 

lands within 32 km (∼20 mi) of the 

northern coast of Alaska between the 

Canadian border and the Kavik River 

and within 8 km (∼5 mi) between the 

Kavik River and Utqiag ̇vik. The total 

area designated under the ESA as 

critical habitat covers approximately 

484,734 km2 (∼187,157 mi2) and is 

entirely within the lands and waters of 

the United States. Polar bear critical 

habitat is described in detail in the final 

rule that designated polar bear critical 

habitat (75 FR 76086, December 7, 

2010). A digital copy of the final critical 

habitat rule is available at: http:// 

www.fws.gov/r7/fisheries/mmm/

polarbear/pdf/ 

federal_register_notice.pdf. 

Stock Size and Range 

In Alaska, polar bears have 

historically been observed as far south 

in the Bering Sea as St. Matthew Island 

and the Pribilof Islands (Ray 1971). A 

detailed description of the SBS polar 

bear stock can be found in the Service’s 

revised Polar Bear (Ursus maritimus) 

Stock Assessment Report (86 FR 33337, 

June 24, 2021). Digital copies of these 

Stock Assessment Report is are available 

at: https://www.fws.gov/alaska/sites/

default/files/2021-06/Southern%20

Beaufort%20Sea%20SAR%20Final_

May%2019rev.pdf. and https:// 

www.fws.gov/alaska/sites/default/files/ 

2021-06/Chukchi_Bering%20Sea%

20SAR%20

Final%20May%2019%20rev.pdf. 

Southern Beaufort Sea Stock 

The SBS polar bear stock is shared 

between Canada and Alaska. Radiotelemetry data, combined with ear tag 

returns from harvested bears, suggest 

that the SBS stock occupies a region 

with a western boundary near Icy Cape, 

Alaska (Scharf et al. 2019), and an 

eastern boundary near Tuktoyaktuk, 

Northwest Territories, Canada (Durner 

et al. 2018). 

The most recent population estimates 

for the Alaska SBS stock were produced 

by the U.S. Geological Survey (USGS) in 

2020 (Atwood et al. 2020) and are based 

on mark-recapture and collared bear 

data collected from the SBS stock from 

2001 to 2016. The SBS stock declined 

from 2003 to 2006 (this was also 

reported by Bromaghin et al. 2015) but 

stabilized from 2006 through 2015. The 

stock may have increased in size from 

2009 to 2012; however, low survival in 

2013 appears to have offset those gains. 

Atwood et al. (2020) provide estimates 

for the portion of the SBS stock only 

within the State of Alaska; however, 

their updated abundance estimate from 

2015 is consistent with the estimate 

from Bromaghin et al. (2015) for 2010. 

Thus, the number of bears in the SBS 

stock is thought to have remained 

constant since the Bromaghin et al. 

(2015) estimate of 907 bears. This 

number is also supported by survival 

rate estimates provided by Atwood et al. 

(2020) that were relatively high in 2001– 

2003, decreased during 2004–2008, then 

improved in 2009, and remained high 

until 2015, except for much lower rates 

in 2012. 

Pacific Walrus 

Pacific walruses constitute a single 

panmictic population (Beatty et al. 

2020) primarily inhabiting the shallow 

continental shelf waters of the Bering 

and Chukchi Seas where their 

distribution is largely influenced by the 

extent of the seasonal pack ice and prey 

densities (Lingqvist et al. 2009; Berta 

and Churchill 2012; USFWS 2017). 

From April to June, most of the 

population migrates from the Bering Sea 

through the Bering Strait and into the 

Chukchi Sea along lead systems that 

develop in the sea-ice and that are 

closely associated with the edge of the 

seasonal pack ice during the open-water 

season (Truhkin and Simokon 2018). By 

July, tens of thousands of animals can 

be found along the edge of the pack ice 

from Russian waters to areas west of 

Point Barrow, Alaska (Fay 1982; Gilbert 

et al. 1992; Belikov et al. 1996; USFWS 

2017). The pack ice has historically 

advanced rapidly southward in late fall, 

and most walruses return to the Bering 

Sea by mid- to late-November. During 

the winter breeding season, walruses are 

found in three concentration areas in 

the Bering Sea where open leads, 

polynyas, or thin ice occur (Fay 1982; 

Fay et al. 1984, Garlich-Miller et al. 

2011a; Duffy-Anderson et al. 2019). 

While the specific location of these 

groups varies annually and seasonally 

depending upon the extent of the seaice, generally one group occurs near the 

Gulf of Anadyr, another south of St. 

Lawrence Island, and a third in the 

southeastern Bering Sea south of 

Nunivak Island into northwestern 

Bristol Bay (Fay 1982; Mymrin et al. 

1990; Garlich-Miller et al. 2011 USFWS 

2017). 

Although most walruses remain either 

in the Chukchi (for adult females and 

dependent young) or Bering (for adult 

males) Seas throughout the summer 


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months, a few occasionally range into 

the Beaufort Sea in late summer 

(Mymrin et al. 1990; Garlich-Miller and 

Jay 2000; USFWS 2017). Industry 

monitoring reports have observed no 

more than 38 walruses in the Beaufort 

Sea ITR geographic region between 1995 

and 2015, with only a few instances of 

disturbance to those walruses (AES 

Alaska 2015, Kalxdorff and Bridges 

2003, USFWS unpubl. data). The USGS 

and the Alaska Department of Fish and 

Game (ADF&G) have fitted between 30– 

60 walruses with satellite transmitters 

each year during spring and summer 

since 2008 and 2013 respectively. In 

2014, a female tagged by ADF&G spent 

about 3 weeks in Harrison Bay, Beaufort 

Sea (ADF&G 2014). The USGS tracking 

data indicates that at least one tagged 

walrus ventured into the Beaufort Sea 

for brief periods in all years except 

2011. Most of these movements extend 

northeast of Utqiagvik to the continental 

shelf edge north of Smith Bay (USGS 

2015). All available information 

indicates that few walruses currently 

enter the Beaufort Sea and those that do, 

spend little time there. The Service and 

USGS are conducting multiyear studies 

on the walrus population to investigate 

movements and habitat use patterns, as 

it is possible that as sea-ice diminishes 

in the Chukchi Sea beyond the 5-year 

period of this rule, walrus distribution 

and habitat use may change. 

Walruses are generally found in 

waters of 100 m (328 ft) or less where 

they utilize sea-ice for passive 

transportation and rest over feeding 

areas, avoid predators, and birth and 

nurse their young (Fay 1982; Ray et al. 

2006; Rosen 2020). The diet of walruses 

consists primarily of benthic 

invertebrates, most notably mollusks 

(Class Bivalvia) and marine worms 

(Class Polychaeta) (Fay 1982; Fay 1985; 

Bowen and Siniff 1999; Born et al. 2003; 

Dehn et al. 2007; Sheffield and 

Grebmeier 2009; Maniscalco et al. 2020). 

When foraging, walruses are capable of 

diving to great depths with most dives 

lasting between 5 and 10 minutes with 

a 1–2-minute surface interval (Fay 1982; 

Bowen and Siniff 1999; Born et al. 2003; 

Dehn et al. 2007; Sheffield and 

Grebmeier 2009). The foraging activity 

of walruses is thought to have a 

significant influence on the ecology of 

the Bering and Chukchi Seas by 

disturbing the sea floor, thereby 

releasing nutrients into the water 

column that provide food for scavenger 

organisms and contributing to the 

diversity of the benthic community 

(Oliver et al. 1983; Klaus et al. 1990; Ray 

et al. 2006). In addition to feeding on 

benthic invertebrates, native hunters 

have also reported incidences of 

walruses preying on seals, fish, and 

other vertebrates (Fay 1982; Sheffield 

and Grebmeier 2009; Seymour et al. 

2014). 

Walruses are social and gregarious 

animals that often travel and haul-out 

onto ice or land in groups where they 

spend approximately 20–30 percent of 

their time out of the water (Gilbert 1999; 

Kastelien 2002; Jefferson et al. 2008; 

Monson et al. 2013; USFWS 2017). 

Hauled-out walruses tend to be in close 

physical contact, with groups ranging 

from a few animals up to tens of 

thousands of individuals—the largest 

aggregations occurring at land haul-outs 

(Gilbert 1999; Monson et al. 2013; 

MacCracken 2017). In recent years, the 

barrier islands north of Point Lay, 

Alaska, have held large aggregations of 

walruses (20,000–40,000) in late 

summer and fall (Monson et al. 2013; 

USFWS 2017). 

The size of the walrus population has 

never been known with certainty. Based 

on large sustained harvests in the 18th 

and 19th centuries, Fay (1957) 

speculated that the pre-exploitation 

population was represented by a 

minimum of 200,000 animals. Since that 

time, population size following 

European contact fluctuated markedly 

in response to varying levels of human 

exploitation. Large-scale commercial 

harvests are thought to have reduced the 

population to 50,000–100,000 animals 

in the mid-1950s (Fay et al. 1989). 

Following the implementation of 

harvest regulations in the 1960s and 

1970s, which limited the take of 

females, the population increased 

rapidly and likely reached or exceeded 

the food-based carrying capacity of the 

region by 1980 (Fay et al. 1989, Fay et 

al. 1997, Garlich-Miller et al. 2006, 

MacCracken et al. 2014). 

Between 1975 and 1990, aerial 

surveys conducted jointly by the United 

States and Russia at 5-year intervals 

produced population estimates ranging 

from about 200,000 to 255,000 

individuals with large confidence 

intervals (Fay 1957; Fay 1982; 

Speckman et al. 2011). Efforts to survey 

the walrus population were suspended 

by both countries after 1990 following 

problems with survey methods that 

severely limited their utility. In 2006, 

the United States and Russia conducted 

another joint aerial survey in the pack 

ice of the Bering Sea using thermal 

imaging systems to more accurately 

count walruses hauled out on sea-ice 

and applied satellite transmitters to 

account for walruses in the water 

(Speckman et al. 2011). In 2013, the 

Service began a genetic mark-recapture 

study to estimate population size. An 

initial analysis of data in the period 

2013–2015 led to the most recent 

estimate of 283,213 Pacific walruses 

with a 95% confidence interval of 

93,000 to 478,975 individuals (Beatty 

2017). Although this is the most recent 

estimate of Pacific walrus population 

size, it should be used with caution as 

it is preliminary. 

Taylor and Udevitz (2015) used data 

from five aerial surveys and with shipbased age and sex composition counts 

that occurred in 1981–1984, 1998, and 

1999 (Citta et al. 2014) in a Bayesian 

integrated population model to estimate 

population trends and vital rates in the 

period 1975–2006. They recalculated 

the 1975–1990 aerial survey estimates 

based on a lognormal distribution for 

inclusion in their model. Their results 

generally agreed with the large-scale 

population trends identified by Citta et 

al. (2014) but with slightly different 

population estimates in some years 

along with more precise confidence 

intervals. Ultimately, Taylor and 

Udevitz (2015) concluded (i) that 

though their model provides improved 

clarity on past walrus population trends 

and vital rates, it cannot overcome the 

large uncertainties in the available 

population size data, and (ii) that the 

absolute size of the Pacific walrus 

population will continue to be 

speculative until accurate empirical 

estimation of the population size 

becomes feasible. 

A detailed description of the Pacific 

walrus stock can be found in the Pacific 

Walrus (Odobenus rosmarus divergens) 

Species Status Assessment (USFWS 

2017). A digital copy of the Species 

Status Assessment is available at: 

https://ecos.fws.gov/ServCat/ 

DownloadFile/ 

132114?Reference=86869. 

Polar bears are known to prey on 

walruses, particularly calves, and killer 

whales (Orcinus orca) have been known 

to take all age classes of walruses (Frost 

et al. 1992, Melnikov and Zagrebin 

2005; Rode et al. 2014; Truhkin and 

Simokon 2018). Predation rates are 

unknown but are thought to be highest 

near terrestrial haulout sites where large 

aggregations of walruses can be found; 

however, few observations exist of 

predation upon walruses further 

offshore. 

Walruses have been hunted by coastal 

Alaska Natives and native people of the 

Chukotka, Russian Federation, for 

thousands of years (Fay et al. 1989). 

Exploitation of the walrus population by 

Europeans has also occurred in varying 

degrees since the arrival of exploratory 

expeditions (Fay et al. 1989). 

Commercial harvest of walruses ceased 

in the United States in 1941, and sport 


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hunting ceased in 1972 with the passage 

of the MMPA and ceased in 1990 in 

Russia. Presently, walrus hunting in 

Alaska is restricted to subsistence use 

by Alaska Natives. Harvest mortality 

during 2000–2018 for both the United 

States and Russian Federation averaged 

3,207 (SE = 194) walruses per year. This 

mortality estimate includes corrections 

for under-reported harvest and struck 

and lost animals. Harvests have been 

declining by about 3 percent per year 

since 2000 and were exceptionally low 

in the United States in 2012–2014. 

Resource managers in Russia have 

concluded that the population has 

declined and have reduced harvest 

quotas in recent years accordingly 

(Kochnev 2004; Kochnev 2005; Kochnev 

2010; pers. comm.; Litovka 2015, pers. 

comm.) based in part on the lower 

abundance estimate generated from the 

2006 survey. Total harvest quotas in 

Russia were further decreased in 2020 to 

1,088 walruses (Ministry of Agriculture 

of the Russian Federation Order of 

March 23, 2020). Intra-specific trauma at 

coastal haulouts is also a known source 

of injury and mortality (Garlich-Miller 

et al. 2011). The risk of stampederelated injuries increases with the 

number of animals hauled out and with 

the duration spent on coastal haulouts, 

with calves and young being the most 

vulnerable to suffer injuries and/or 

mortality (USFWS 2017). However, 

management and protection programs in 

both the United States and the Russian 

Federation have been somewhat 

successful in reducing disturbances and 

large mortality events at coastal 

haulouts (USFWS 2015). 

Climate Change 

Global climate change will impact the 

future of both Pacific walrus and polar 

bear populations. As atmospheric 

greenhouse gas concentrations increase 

so will global temperatures 

(Pierrehumbert 2011; IPCC 2014) with 

substantial implications for the Arctic 

environment and its inhabitants (Bellard 

et al. 2012, Scheffers et al. 2016, 

Harwood et al. 2001, Nunez et al. 2019). 

The Arctic has warmed at twice the 

global rate (IPCC 2014), and long-term 

data sets show that substantial 

reductions in both the extent and 

thickness of Arctic sea-ice cover have 

occurred over the past 40 years (Meier 

et al. 2014, Frey et al. 2015). Stroeve et 

al. (2012) estimated that, since 1979, the 

minimum area of fall Arctic sea-ice 

declined by over 12 percent per decade 

through 2010. Record low minimum 

areas of fall Arctic sea-ice extent were 

recorded in 2002, 2005, 2007, and 2012. 

Further, observations of sea-ice in the 

Beaufort Sea have shown a trend since 

2004 of sea-ice break-up earlier in the 

year, re-formation of sea-ice later in the 

year, and a greater proportion of firstyear ice in the ice cover (Galley et al. 

2016). The overall trend of decline of 

Arctic sea-ice is expected to continue 

for the foreseeable future (Stroeve et al. 

2007; Amstrup et al. 2008; Hunter et al. 

2010; Overland and Wang 2013; 73 FR 

28212, May 15, 2008; IPCC 2014). 

Decline in Arctic sea ice affects Arctic 

species through habitat loss and altered 

trophic interactions. These factors may 

contribute to population distribution 

changes, population mixing, and 

pathogen transmission (Post et al. 2013), 

which further impact population health. 

For polar bears, sea-ice habitat loss 

due to climate change has been 

identified as the primary cause of 

conservation concern (e.g., Stirling and 

Derocher 2012, Atwood et al. 2016b, 

USFWS 2016). A 42 percent loss of 

optimal summer polar bear habitat 

throughout the Arctic is projected for 

the decade of 2045–2054 (Durner et al. 

2009). A recent global assessment of the 

vulnerability of the 19 polar bear stocks 

to future climate warming ranked the 

SBS as one of the three most vulnerable 

stocks (Hamilton and Derocher 2019). 

The study, which examined factors such 

as the size of the stock, continental shelf 

area, ice conditions, and prey diversity, 

attributed the high vulnerability of the 

SBS stock primarily to deterioration of 

ice conditions. The SBS polar bear stock 

occurs within the Polar Basin Divergent 

Ecoregion (PBDE), which is 

characterized by extensive sea-ice 

formation during the winters and the 

sea ice melting and pulling away from 

the coast during the summers (Amstrup 

et al. 2008). Projections show that polar 

bear stocks within the PBDE may be 

extirpated within the next 45–75 years 

at current rates of sea-ice declines 

(Amstrup et al. 2007, Amstrup et al. 

2008). Atwood et al. (2016) also 

predicted that polar bear stocks within 

the PBDE will be more likely to greatly 

decrease in abundance and distribution 

as early as the 2020–2030 decade 

primarily as a result of sea-ice habitat 

loss. 

Sea-ice habitat loss affects the 

distribution and habitat use patterns of 

the SBS polar bear stock. When sea ice 

melts during the summer, polar bears in 

the PBDE may either stay on land 

throughout the summer or move with 

the sea ice as it recedes northward 

(Durner et al. 2009). The SBS stock, and 

to a lesser extent the Chukchi Sea stock, 

are increasingly utilizing marginal 

habitat (i.e., land and ice over less 

productive waters) (Ware et al. 2017). 

Polar bear use of Beaufort Sea coastal 

areas has increased during the fall openwater period (June through October). 

Specifically, the percentage of radiocollared adult females from the SBS 

stock utilizing terrestrial habitats has 

tripled over 15 years, and SBS polar 

bears arrive onshore earlier, stay longer, 

and leave to the sea ice later (Atwood 

et al. 2016b). This change in polar bear 

distribution and habitat use has been 

correlated with diminished sea ice and 

the increased distance of the pack ice 

from the coast during the open-water 

period (i.e., the less sea ice and the 

farther from shore the leading edge of 

the pack ice is, the more bears are 

observed onshore) (Schliebe et al. 2006; 

Atwood et al. 2016b). 

The current trend for sea-ice in the 

SBS region will result in increased 

distances between the ice edge and 

land, likely resulting in more bears 

coming ashore during the open-water 

period (Schliebe et al. 2008). More polar 

bears on land for a longer period of time 

may increase both the frequency and the 

magnitude of polar bear exposure to 

human activities, including an increase 

in human–bear interactions (Towns et 

al. 2009, Schliebe et al. 2008, Atwood et 

al. 2016b). Polar bears spending more 

time in terrestrial habitats also increases 

their risk of exposure to novel 

pathogens that are expanding north as a 

result of a warmer Arctic (Atwood et al. 

2016b, 2017). Heightened immune 

system activity and more infections 

(indicated by elevated number of white 

blood cells) have been reported for the 

SBS polar bears that summer on land 

when compared to those on sea ice 

(Atwood et al. 2017; Whiteman et al. 

2019). The elevation in immune system 

activity represents additional energetic 

costs that could ultimately impact stock 

and individual fitness (Atwood et al. 

2017; Whiteman et al. 2019). Prevalence 

of parasites such as the nematode 

Trichinella nativa in many Arctic 

species, including polar bears, pre-dates 

the recent global warming. However, 

parasite prevalence could increase as a 

result of changes in diet (e.g., increased 

reliance on conspecific scavenging) and 

feeding habits (e.g., increased 

consumption of seal muscle) associated 

with climate-induced reduction of 

hunting opportunities for polar bears 

(Penk et al. 2020, Wilson et al. 2017). 

The continued decline in sea-ice is 

also projected to reduce connectivity 

among polar bear stocks and potentially 

lead to the impoverishment of genetic 

diversity that is key to maintaining 

viable, resilient wildlife populations 

(Derocher et al. 2004, Cherry et al. 2013, 

Kutchera et al. 2016). The circumpolar 

polar bear population has been divided 

into six genetic clusters: The Western 

Polar Basin (which includes the SBS 


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and CS stocks), the Eastern Polar Basin, 

the Western and Eastern Canadian 

Archipelago, and Norwegian Bay 

(Malenfant et al. 2016). There is 

moderate genetic structure among these 

clusters, suggesting polar bears broadly 

remain in the same cluster when 

breeding. While there is currently no 

evidence for strong directional gene 

flow among the clusters (Malenfant et 

al. 2016), migrants are not uncommon 

and can contribute to gene flow across 

clusters (Kutschera et al. 2016). 

Changing sea-ice conditions will make 

these cross-cluster migrations (and the 

resulting gene flow) more difficult in the 

future (Kutschera et al. 2016). 

Additionally, habitat loss from 

decreased sea-ice extent may impact 

polar bear reproductive success by 

reducing or altering suitable denning 

habitat and extending the polar bear 

fasting season (Rode et al. 2018, Stirling 

and Derocher 2012, Molna ́r et al. 2020). 

In the early 1990s, approximately 50 

percent of the annual maternal dens of 

the SBS polar bear stock occurred on 

land (Amstrup and Gardner 1994). 

Along the Alaskan region the proportion 

of terrestrial dens increased from 34.4 

percent in 1985–1995 to 55.2 percent in 

2007–2013 (Olson et al. 2017). Polar 

bears require a stable substrate for 

denning. As sea-ice conditions 

deteriorate and become less stable, seaice dens can become vulnerable to 

erosion from storm surges (Fischbach et 

al. 2007). Under favorable autumn 

snowfall conditions, SBS females 

denning on land had higher 

reproductive success than SBS females 

denning on sea-ice. Factors that may 

influence the higher reproductive 

success of females with land-based dens 

include longer denning periods that 

allow cubs more time to develop, higher 

snowfall conditions that strengthen den 

integrity throughout the denning period 

(Rode et al. 2018), and increased 

foraging opportunities on land (e.g., 

scavenging on Bowhead whale 

carcasses) (Atwood et al. 2016b). While 

SBS polar bear females denning on land 

may experience increased reproductive 

success, at least under favorable 

snowfall conditions, it is possible that 

competition for suitable denning habitat 

on land may increase due to sea-ice 

decline (Fischbach et al. 2007) and landbased dens may be more vulnerable to 

disturbance from human activities 

(Linnell et al. 2000). 

Polar bear reproductive success may 

also be impacted by declines in sea ice 

through an extended fasting season 

(Molna ́r et al. 2020). By 2100, 

recruitment is predicted to become 

jeopardized in nearly all polar bear 

stocks if greenhouse gas emissions 

remain uncurbed (RCP8.5 

[Representative Concentration Pathway 

8.5] scenario) as fasting thresholds are 

increasingly exceeded due to declines in 

sea-ice across the Arctic circumpolar 

range (Molna ́r et al. 2020). As the fasting 

season increases, most of these 12 

stocks, including in the SBS, are 

expected to first experience significant 

adverse effects on cub recruitment 

followed by effects on adult male 

survival and lastly on adult female 

survival (Molna ́r et al. 2020). Without 

mitigation of greenhouse gas emissions 

and assuming optimistic polar bear 

responses (e.g., reduced movement to 

conserve energy), cub recruitment in the 

SBS stock has possibly been already 

adversely impacted since the late 1980s, 

while detrimental impacts on male and 

female survival are forecasted to 

possibly occur in the late 2030s and 

2040s, respectively. 

Extended fasting seasons are 

associated with poor body condition 

(Stirling and Derocher 2012), and a 

female’s body condition at den entry is 

a critical factor that determines whether 

the female will produce cubs and the 

cubs’ chance of survival during their 

first year (Rode et al. 2018). 

Additionally, extended fasting seasons 

will cause polar bears to depend more 

heavily on their lipid reserves for 

energy, which can release lipid-soluble 

contaminants, such as persistent organic 

pollutants and mercury, into the 

bloodstream and organ tissues. The 

increased levels of contaminants in the 

blood and tissues can affect polar bear 

health and body condition, which has 

implications for reproductive success 

and survival (Jenssen et al. 2015). 

Changes in sea-ice can impact polar 

bears by altering trophic interactions. 

Differences in sea-ice dynamics, such as 

the timing of ice formation and breakup, 

as well as changes in sea-ice type and 

concentration, may impact the 

distribution of polar bears and/or their 

prey’s occurrence and reduce polar 

bears’ access to prey. A climate-induced 

reduction in overlap between female 

polar bears and ringed seals was 

detected after a sudden sea-ice decline 

in Norway that limited the ability of 

females to hunt on sea-ice (Hamilton et 

al. 2017). While polar bears are 

opportunistic and hunt other species, 

their reliance on ringed seals is 

prevalent across their range (Thiemann 

et al. 2007, 2008; Florko et al. 2020; 

Rode et al. 2021). Male and female polar 

bears exhibit differences in prey 

consumption. Females typically 

consume more ringed seals compared to 

males, which is likely related to more 

limited hunting opportunities for 

females (e.g., prey size constraints) 

(McKinney et al. 2017, Bourque et al. 

2020). Female body condition has been 

positively correlated with consumption 

of ringed seals, but negatively correlated 

with the consumption of bearded seals 

(Florko et al. 2020). Consequently, 

females are more prone to decreased 

foraging and reproductive success than 

males during years in which 

unfavorable sea-ice conditions limit 

polar bears’ access to ringed seals 

(Florko et al. 2020). 

In the SBS stock, adult female and 

juvenile polar bear consumption of 

ringed seals was negatively correlated 

with winter Arctic oscillation, which 

affects sea-ice conditions. This trend 

was not observed for male polar bears. 

Instead, male polar bears consumed 

more bowhead whale as a result of 

scavenging the carcasses of subsistenceharvested bowhead whales during years 

with a longer ice-free period over the 

continental shelf. It is possible that 

these alterations in sea-ice conditions 

may limit female polar bears’ access to 

ringed seals, and male polar bears may 

rely more heavily on alternative onshore 

food resources in the southern Beaufort 

Sea region (McKinney et al. 2017). 

Changes in the availability and 

distribution of seals may influence polar 

bear foraging efficiency. Reduction in 

sea ice is expected to render polar bear 

foraging energetically more demanding, 

as moving through fragmented sea ice 

and open-water swimming require more 

energy than walking across consolidated 

sea ice (Cherry et al. 2009, Pagano et al. 

2012, Rode et al. 2014, Durner et al. 

2017). Inefficient foraging can 

contribute to nutritional stress and poor 

body condition, which can have 

implications for reproductive success 

and survival (Regehr et al. 2010). 

The decline in Arctic sea ice is 

associated with the SBS polar bear stock 

spending more time in terrestrial 

habitats (Schliebe et al. 2008). Recent 

changes in female denning habitat and 

extended fasting seasons as a result of 

sea-ice decline may affect the 

reproductive success of the SBS polar 

bear stock (Rode et al. 2018; Stirling and 

Derocher 2012; Molna ́r et al. 2020). 

Other relevant factors that could 

negatively affect the SBS polar bear 

stock include changes in prey 

availability, reduced genetic diversity 

through limited population connectivity 

and/or hybridization with other bear 

species, increased exposure to disease 

and parasite prevalence and/or 

dissemination, impacts of human 

activities (oil and gas exploration/ 

extraction, shipping, harvesting, etc.) 

and pollution (Post et al. 2013; 

Hamilton and Derocher 2019). Based on 

the projections of sea-ice decline in the 


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Beaufort Sea region and demonstrated 

impacts on SBS polar bear utilization of 

sea-ice and terrestrial habitats, the 

Service anticipates that polar bear use of 

the Beaufort Sea coast will continue to 

increase during the open-water season. 

For walruses, climate change may 

affect habitat and prey availability. The 

loss of Arctic sea ice has affected walrus 

distribution and habitat use in the 

Bering and Chukchi Seas (Jay et al. 

2012). Walruses use sea ice as a 

breeding site, a location to birth and 

nurse young, and a protective cover 

from storms and predation; however, if 

the sea ice retreats north of the 

continental shelf break in the Chukchi 

Sea, walruses can no longer use it for 

these purposes. Thus, loss of sea ice is 

associated with increased use of coastal 

haul-outs during the summer, fall, and 

early winter (Jay et al. 2012). Coastal 

haulouts are potentially dangerous for 

walruses, as they can stampede toward 

the water when disturbed, resulting in 

injuries and mortalities (Garlich-Miller 

et al. 2011). Use of land haulouts is also 

more energetically costly, with walruses 

hauled out on land spending more time 

in water but not foraging than those 

hauled out on sea ice. This difference 

has been attributed to an increase in 

travel time in the water from land 

haulouts to foraging areas (Jay et al. 

2017). Higher walrus abundance at these 

coastal haulouts may also increase 

exposure to environmentally and 

density-dependent pathogens (Post et al. 

2013). Climate change impacts through 

habitat loss and changes in prey 

availability could affect walrus 

population stability. It is unknown if 

walruses will utilize the Beaufort Sea 

more heavily in the future due to 

climate change effects; however, 

considering the low number of walruses 

observed in the Beaufort Sea (see Take 

Estimates for Pacific Walruses and Polar 

Bears), it appears that walruses will 

remain uncommon in the Beaufort Sea 

for the next 5 years. 

Potential Effects of the Specified 

Activities on Subsistence Uses 

Polar Bear 

Based on subsistence harvest reports, 

polar bear hunting is less prevalent in 

communities on the north coast of 

Alaska than it is in west coast 

communities. There are no quotas under 

the MMPA for Alaska Native polar bear 

harvest in the Southern Beaufort Sea; 

however, there is a Native-to-Native 

agreement between the Inuvialuit in 

Canada and the Inupiat in Alaska. This 

agreement, the Inuvialuit-Inupiat Polar 

Bear Management Agreement, 

established quotas and 

recommendations concerning protection 

of denning females, family groups, and 

methods of take. Although this 

Agreement is voluntary in the United 

States and does not have the force of 

law, legally enforceable quotas are 

administered in Canada. In Canada, 

users are subject to provincial 

regulations consistent with the 

Agreement. Commissioners for the 

Agreement set the original quota at 76 

bears in 1988, split evenly between the 

Inuvialuit in Canada and the Inupiat in 

the United States. In July 2010, the 

quota was reduced to 70 bears per year. 

Subsequently, in Canada, the boundary 

of the SBS stock with the neighboring 

Northern Beaufort Sea stock was 

adjusted through polar bear 

management bylaws in the Inuvialuit 

Settlement Region in 2013, affecting 

Canadian quotas and harvest levels from 

the SBS stock. The current subsistence 

harvest established under the 

Agreement of 56 bears total (35 in the 

United States and 21 in Canada) reflect 

this change. 

The Alaska Native subsistence harvest 

of polar bears from the SBS population 

has declined. From 1990 to 1999, an 

average of 42 bears were taken annually. 

The average subsistence harvest 

decreased to 21 bears annually in the 

period 2000–2010 and 11 bears annually 

during 2015–2020. The reason for the 

decline of harvested polar bears from 

the SBS population is unknown. Alaska 

Native subsistence hunters and harvest 

reports have not indicated a lack of 

opportunity to hunt polar bears or 

disruption by Industry activity. 

Pacific Walrus 

Few walruses are harvested in the 

Beaufort Sea along the northern coast of 

Alaska since their primary range is in 

the Bering and Chukchi Seas. Walruses 

constitute a small portion of the total 

marine mammal harvest for the village 

of Utqiagvik. Hunters from Utqiagvik 

have harvested 407 walruses since the 

year 2000 with 65 harvested since 2015. 

Walrus harvest from Nuiqsut and 

Kaktovik is opportunistic. They have 

reported taking four walruses since 

1993. None of the walrus harvests for 

Utqiagvik, Nuiqsut, or Kaktovik from 

2014 to 2020 occurred within the 

Beaufort Sea ITR region. 

Evaluation of Effects of the Specified 

Activities on Subsistence Uses 

There are three primary Alaska Native 

communities on the Beaufort Sea whose 

residents rely on Pacific walruses and 

polar bears for subsistence use: 

Utqiagvik, Nuiqsut, and Kaktovik. 

Utqiagvik and Kaktovik are expected to 

be less affected by the Industry’s 

proposed activities than Nuiqsut. 

Nuiqsut is located within 5 mi of 

ConocoPhillips’ Alpine production field 

to the north and ConocoPhillips’ Alpine 

Satellite development field to the west. 

However, Nuiqsut hunters typically 

harvest polar bears from Cross Island 

during the annual fall bowhead 

whaling. Cross Island is approximately 

16 km (∼10 mi) offshore from the coast 

of Prudhoe Bay. We have received no 

evidence or reports that bears are 

altering their habitat use patterns, 

avoiding certain areas, or being affected 

in other ways by the existing level of oil 

and gas activity near communities or 

traditional hunting areas that would 

diminish their availability for 

subsistence use. However, as is 

discussed in Evaluation of Effects of 

Specified Activities on Pacific Walruses, 

Polar Bears, and Prey Species below, the 

Service has found some evidence of 

fewer maternal polar bear dens near 

industrial infrastructure than expected. 

Changes in Industry activity locations 

may trigger community concerns 

regarding the effect on subsistence uses. 

Industry must remain proactive to 

address potential impacts on the 

subsistence uses by affected 

communities through consultations and, 

where warranted, POCs. Evidence of 

communication with the public about 

activities will be required as part of an 

LOA. Current methods of 

communication are variable and include 

venues such as public forums, which 

allow communities to express feedback 

prior to the initiation of operations, the 

employ of subsistence liaisons, and 

presentations to regional commissions. 

If community subsistence use concerns 

arise from new activities, appropriate 

mitigation measures, such as cessation 

of activities in key locations during 

hunting seasons, are available and will 

be applied as a part of the POC. 

No unmitigable concerns from the 

potentially affected communities 

regarding the availability of walruses or 

polar bears for subsistence uses have 

been identified through Industry 

consultations with the potentially 

affected communities of Utqiagvik, 

Kaktovik, or Nuiqsut. During the 2016– 

2021 ITR period, Industry groups have 

communicated with Native 

communities and subsistence hunters 

through subsistence representatives, 

community liaisons, and village 

outreach teams as well as participation 

in community and commission 

meetings. Based on information 

gathered from these sources, it appears 

that subsistence hunting opportunities 

for walruses and polar bears have not 

been affected by past Industry activities 

conducted pursuant to the 2016–2021 


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Beaufort ITR and are not likely to be 

affected by the activities described in 

this ITR. Given the similarity between 

the nature and extent of Industry 

activities covered by the prior Beaufort 

Sea ITR and those specified in AOGA’s 

pending Request, and the continued 

requirement for Industry to consult and 

coordinate with Alaska Native 

communities and representative 

subsistence hunting and co-management 

organizations (and develop a POC if 

necessary), we do not anticipate that the 

activities specified in AOGA’s pending 

Request will have any unmitigable 

effects on the availability of Pacific 

walruses or polar bears for subsistence 

uses. 

Potential Effects of the Specified 

Activities on Pacific Walruses, Polar 

Bears, and Prey Species 

Industry activities can affect 

individual walruses and polar bears in 

numerous ways. Below, we provide a 

summary of the documented and 

potential effects of oil and gas industrial 

activities on both polar bears and 

walruses. The effects analyzed included 

harassment, lethal take, and exposure to 

oil spills. 

Polar Bear: Human–Polar Bear 

Encounters 

Oil and gas industry activities may 

affect individual polar bears in 

numerous ways during the open-water 

and ice-covered seasons. Polar bears are 

typically distributed in offshore areas 

associated with multiyear pack ice from 

mid-November to mid-July. From midJuly to mid-November, polar bears can 

be found in large numbers and high 

densities on barrier islands, along the 

coastline, and in the nearshore waters of 

the Beaufort Sea, particularly on and 

around Barter and Cross Islands. This 

distribution leads to a significantly 

higher number of human–polar bear 

encounters on land and at offshore 

structures during the open-water period 

than other times of the year. Bears that 

remain on the multiyear pack ice are not 

typically present in the ice-free areas 

where vessel traffic occurs, as barges 

and vessels associated with Industry 

activities travel in open water and avoid 

large ice floes. 

On land, the majority of Industry’s 

bear observations occur within 2 km 

(1.2 mi) of the coastline. Industry 

facilities within the offshore and coastal 

areas are more likely to be approached 

by polar bears and may act as physical 

barriers to movements of polar bears. As 

bears encounter these facilities, the 

chances for human–bear interactions 

increase. The Endicott and West Dock 

causeways, as well as the facilities 

supporting them, have the potential to 

act as barriers to movements of polar 

bears because they extend continuously 

from the coastline to the offshore 

facility. However, polar bears have 

frequently been observed crossing 

existing roads and causeways. Offshore 

production facilities, such as Northstar, 

Spy Island, and Oooguruk, have 

frequently been approached by polar 

bears but appear to present only an 

inconsequential small-scale, local 

obstruction to the bears’ movement. Of 

greater concern is the increased 

potential for human–polar bear 

interaction at these facilities. 

Encounters are more likely to occur 

during the fall at facilities on or near the 

coast. Polar bear interaction plans, 

training, and monitoring required by 

past ITRs have proven effective at 

reducing human–polar bear encounters 

and the risks to bears and humans when 

encounters occur. Polar bear interaction 

plans detail the policies and procedures 

that Industry facilities and personnel 

will implement to avoid attracting and 

interacting with polar bears as well as 

minimizing impacts to the bears. 

Interaction plans also detail how to 

respond to the presence of polar bears, 

the chain of command and 

communication, and required training 

for personnel. Industry uses technology 

to aid in detecting polar bears including 

bear monitors, closed-circuit television, 

video cameras, thermal cameras, radar 

devices, and motion-detection systems. 

In addition, some companies take steps 

to actively prevent bears from accessing 

facilities by using safety gates and 

fences. 

The noises, sights, and smells 

produced by the proposed project 

activities could disturb and elicit 

variable responses from polar bears. 

Noise disturbance can originate from 

either stationary or mobile sources. 

Stationary sources include construction, 

maintenance, repair and remediation 

activities, operations at production 

facilities, gas flaring, and drilling 

operations. Mobile sources include 

aircraft traffic, geotechnical surveys, ice 

road construction, vehicle traffic, 

tracked vehicles, and snowmobiles. 

The potential behavioral reaction of 

polar bears to the proposed activities 

can vary by activity type. Camp odors 

may attract polar bears, potentially 

resulting in human–bear encounters, 

intentional hazing, or possible lethal 

take in defense of human life (see 50 

CFR 18.34 for further guidance on 

passive polar bear deterrence measures). 

Noise generated on the ground by 

industrial activity may cause a 

behavioral (e.g., escape response) or 

physiologic (e.g., increased heart rate, 

hormonal response) (Harms et al. 1997; 

Tempel and Gutierrez 2003) response. 

The available studies of polar bear 

behavior indicate that the intensity of 

polar bear reaction to noise disturbance 

may be based on previous interactions, 

sex, age, and maternal status (Anderson 

and Aars 2008; Dyck and Baydack 

2004). 

Polar Bear: Effects of Aircraft 

Overflights 

Bears on the surface experience 

increased noise and visual stimuli when 

planes or helicopters fly above them, 

both of which may elicit a biologically 

significant behavioral response. Sound 

frequencies produced by aircraft will 

likely fall within the hearing range of 

polar bears (see Nachtigall et al. 2007) 

and will thus be audible to animals 

during flyovers or when operating in 

proximity to polar bears. Polar bears 

likely have acute hearing with previous 

sensitivities demonstrated between 1.4– 

22.5 kHz (tests were limited to 22.5 kHz; 

Nachtigall et al. 2007). This range, 

which is wider than that seen in 

humans, supports the idea that polar 

bears may experience temporary (called 

temporary threshold shift, or TTS) or 

permanent (called permanent threshold 

shift, or PTS) hearing impairment if they 

are exposed to high-energy sound. 

While species-specific TTS and PTS 

thresholds have not been established for 

polar bears, thresholds have been 

established for the general group ‘‘other 

marine carnivores’’ which includes both 

polar bears and walruses (Southall et al. 

2019). Through a series of systematic 

modeling procedures and 

extrapolations, Southall et al. (2019) 

have generated modified noise exposure 

thresholds for both in-air and 

underwater sound (Table 1). 


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TABLE 1—TEMPORARY THRESHOLD SHIFT (TTS) AND PERMANENT THRESHOLD SHIFT (PTS) THRESHOLDS ESTABLISHED

BY SOUTHALL ET AL. (2019) THROUGH MODELING AND EXTRAPOLATION FOR ‘‘OTHER MARINE CARNIVORES,’’ WHICH

INCLUDES BOTH POLAR BEARS AND WALRUSES

TTS PTS 

Non-impulsive Impulsive Non-impulsive Impulsive 

SELCUM SELCUM Peak SPL SELCUM SELCUM Peak SPL 

Air ............................................................. 157 146 161 177 161 167 

Water ........................................................ 199 188 226 219 203 232 

Values are weighted for other marine carnivores’ hearing thresholds and given in cumulative sound exposure level (SELCUM dB re (20μPa)2s 

in air and SELCUM dB re (1 μPa)2s in water) for impulsive and non-impulsive sounds, and unweighted peak sound pressure level in air (dB re 

20μPa) and water (dB 1μPa) (impulsive sounds only). 

During an FAA test, test aircraft 

produced sound at all frequencies 

measured (50 Hz to 10 kHz) (Healy 

1974; Newman 1979). At frequencies 

centered at 5 kHz, jets flying at 300 m 

(984 ft) produced 1⁄3 octave band noise 

levels of 84 to 124 dB, propeller-driven 

aircraft produced 75 to 90 dB, and 

helicopters produced 60 to 70 dB 

(Richardson et al. 1995). Thus, the 

frequency and level of airborne sounds 

typically produced by Industry is 

unlikely to cause temporary or 

permanent hearing damage unless 

marine mammals are very close to the 

sound source. Although temporary or 

permanent hearing damage is not 

anticipated, impacts from aircraft 

overflights have the potential to elicit 

biologically significant behavioral 

responses from polar bears. 

Observations of polar bears during fall 

coastal surveys, which flew at much 

lower altitudes than typical Industry 

flights (see Estimating Take Rates of 

Aircraft Activities), indicate that the 

reactions of non-denning polar bears is 

typically varied but limited to shortterm changes in behavior ranging from 

no reaction to running away. Bears 

associated with dens have been shown 

to increase vigilance, initiate rapid 

movement, and even abandon dens 

when exposed to low-flying aircraft (see 

Effects to Denning Bears for further 

discussion). Aircraft activities can 

impact bears over all seasons; however, 

during the summer and fall seasons, 

aircraft have the potential to disturb 

both individuals and congregations of 

polar bears. These onshore bears spend 

most of their time resting and limiting 

their movements on land. Exposure to 

aircraft traffic is expected to result in 

changes in behavior, such as going from 

resting to walking or running and, 

therefore, has the potential to be 

energetically costly. Mitigation 

measures, such as minimum flight 

elevations over polar bears and habitat 

areas of concern as well as flight 

restrictions around known polar bear 

aggregations when safe, are included in 

this ITR to achieve least practicable 

adverse impact to polar bears by aircraft. 

Polar Bear: Effects of In-Water Activities 

In-water sources of sound, such as 

pile driving, screeding, dredging, or 

vessel movement, may disturb polar 

bears. In the open-water season, 

Industry activities are generally limited 

to relatively ice-free, open water. During 

this time in the Beaufort Sea, polar bears 

are typically found either on land or on 

the pack ice, which limits the chances 

of the interaction of polar bears with 

offshore Industry activities. Though 

polar bears have been observed in open 

water miles from the ice edge or ice 

floes, the encounters are relatively rare 

(although the frequency of such 

observations may increase due to sea ice 

change). However, if bears come in 

contact with Industry operations in 

open water, the effects of such 

encounters likely include no more than 

short-term behavioral disturbance. 

While polar bears swim in and hunt 

from open water, they spend less time 

in the water than most marine 

mammals. Stirling (1974) reported that 

polar bears observed near Devon Island 

during late July and early August spent 

4.1 percent of their time swimming and 

an additional 0.7 percent engaged in 

aquatic stalking of prey. More recently, 

application of tags equipped with timedepth recorders indicate that aquatic 

activity of polar bears is greater than 

was previously thought. In a study 

published by Lone et al. (2018), 75 

percent of polar bears swam daily 

during open-water months, with 

animals spending 9.4 percent of their 

time in July in the water. Both coastaland pack-ice-dwelling animals were 

tagged, and there were no significant 

differences in the time spent in the 

water by animals in the two different 

habitat types. While polar bears 

typically swim with their ears above 

water, Lone et al. (2018) found polar 

bears in this study that were fitted with 

depth recorders (n=6) spent 

approximately 24 percent of their time 

in the water with their head underwater. 

Thus, for the individuals followed as a 

part of the study, an average of 2.2 

percent of the day, or 31 minutes, were 

spent with their heads underwater. 

The pile driving, screeding, dredging, 

and other in-water activities proposed 

by Industry introduce substantial levels 

of noise into the marine environment. 

Underwater sound levels from 

construction along the North Slope have 

been shown to range from 103 decibels 

(dB) at 100 m (328 ft) for auguring to 

143 dB at 100 m (328 ft) for pile driving 

(Greene et al. 2008) with most of the 

energy below 100 Hz. Airborne sound 

levels from these activities range from 

65 dB at 100 m (328 ft) for a bulldozer 

and 81 dB at 100 m (328 ft) for pile 

driving, with most of the energy for inair levels also below 100 Hz (Greene et 

al. 2008). Therefore, in-water activities 

are not anticipated to result in 

temporary or permanent damage to 

polar bear hearing. 

In 2012, during the open-water 

season, Shell vessels encountered a few 

polar bears swimming in ice-free water 

more than 70 mi (112.6 km) offshore in 

the Chukchi Sea. In those instances, the 

bears were observed to either swim 

away from or approach the Shell 

vessels. Sometimes a polar bear would 

swim around a stationary vessel before 

leaving. In at least one instance a polar 

bear approached, touched, and 

investigated a stationary vessel from the 

water before swimming away. 

Polar bears are more likely to be 

affected by on-ice or in-ice Industry 

activities versus open-water activities. 

From 2009 through 2014, there were a 

few Industry observation reports of 

polar bears during on-ice activities. 

Those observations were primarily of 

bears moving through an area during 

winter seismic surveys on near-shore 

ice. The disturbance to bears moving 

across the surface is frequently minimal, 

short-term, and temporary due to the 

mobility of such projects and limited to 


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small-scale alterations to bear 

movements. 

Polar Bear: Effects to Denning Bears 

Known polar bear dens in the 

Beaufort Sea ITR region, whether 

discovered opportunistically or as a 

result of planned surveys such as 

tracking marked bears or den detection 

surveys, are monitored by the Service. 

However, these known denning sites are 

only a small percentage of the total 

active polar bear dens for the SBS stock 

in any given year. Each year, Industry 

coordinates with the Service to conduct 

surveys to determine the location of 

Industry’s activities relative to known 

dens and denning habitat. Under past 

ITRs Industry activities have been 

required to avoid known polar bear dens 

by 1.6 km (1 mi). However, occasionally 

an unknown den may be encountered 

during Industry activities. When a 

previously unknown den is discovered 

in proximity to Industry activity, the 

Service implements mitigation measures 

such as the 1.6-km (1-mi) activity 

exclusion zone around the den and 24- 

hour monitoring of the site. 

The responses of denning bears to 

disturbance and the consequences of 

these responses can vary throughout the 

denning process. Consequently, we 

divide the denning period into four 

stages when considering impacts of 

disturbance: Den establishment, early 

denning, late denning, and postemergence. 

Den Establishment 

The den establishment period begins 

in autumn near the time of implantation 

when pregnant females begin scouting 

for, excavating, and occupying a den. 

The timing of den establishment is 

likely governed by a variety of 

environmental factors, including 

snowfall events (Zedrosser et al. 2006; 

Evans et al. 2016; Pigeon et al. 2016), 

accumulation of snowpack (Amstrup 

and Gardner 1994; Durner et al. 2003, 

2006), temperature (Rode et al. 2018), 

and timing of sea ice freeze-up (Webster 

et al. 2014). Spatial and temporal 

variation in these factors may explain 

variability in the timing of den 

establishment, which occurs between 

October and December in the SBS stock 

(Durner et al. 2001; Amstrup 2003). 

Rode et al. (2018) estimated November 

15 as the mean date of den entry for 

bears in the SBS stock. 

The den establishment period ends 

with the birth of cubs in early to midwinter (Ramsay and Stirling 1988) after 

a gestation period that is likely similar 

to the ∼60-day period documented for 

brown bears (Tsubota et al. 1987). Curry 

et al. (2015) found the mean and median 

birth dates for captive polar bears in the 

Northern Hemisphere were both 

November 29. Similarly, Messier et al. 

(1994) estimated that most births had 

occurred by December 15 in the 

Canadian Arctic Archipelago based on 

activity levels recorded by sensors on 

females in maternity dens. 

Much of what is known of the effects 

of disturbance during the den 

establishment period comes from 

studies of polar bears captured by 

researchers in autumn. Although 

capture is a severe form of disturbance 

atypical of events likely to occur during 

oil and gas activities, responses to 

capture can inform our understanding of 

how polar bears respond to substantial 

levels of disturbance. Ramsay and 

Stirling (1986) reported that 10 of 13 

pregnant females that were captured 

and collared at dens in October or 

November abandoned their existing 

dens. Within 1–2 days after their 

release, these bears moved a median 

distance of 24.5 km and excavated new 

maternal dens. The remaining three 

polar bears reentered their initial dens 

or different dens <2 km from their 

initial den soon after being released. 

Amstrup (1993, 2003) documented a 

similar response in Alaska and reported 

5 of 12 polar bears abandoned den sites 

and subsequently denned elsewhere 

following disturbance during autumn, 

with the remaining 7 bears remaining at 

their original den site. 

The observed high rate of den 

abandonment during autumn capture 

events suggests that polar bears have a 

low tolerance threshold for intense 

disturbance during den initiation and 

are willing to expend energy to avoid 

further disturbance. Energy 

expenditures during den establishment 

are not replenished because female 

ursids do not eat or drink during 

denning and instead rely solely on 

stored body fat (Nelson et al.1983; 

Spady et al. 2007). Consequently, 

because female body condition during 

denning affects the size and subsequent 

survival of cubs at emergence from the 

den (Derocher and Stirling 1996; 

Robbins et al. 2012), disturbances that 

cause additional energy expenditures in 

fall could have latent effects on cubs in 

the spring. 

The available published research does 

not conclusively demonstrate the extent 

to which capture or den abandonment 

during den initiation is consequential 

for survival and reproduction. Ramsay 

and Stirling (1986) reported that 

captures (also known as handling) of 

females did not significantly affect 

numbers and mean weights of cubs, but 

the overall mean litter size and weights 

of cubs born to previously handled 

mothers consistently tended to be 

slightly lower than those of mothers not 

previously handled. Amstrup (1993) 

found no significant effect of handling 

on cub weight, litter size, or survival. 

Similarly, Seal et al. (1970) reported no 

loss of pregnancy among captive ursids 

following repeated chemical 

immobilization and handling. However, 

Lunn et al. (2004) concluded that 

handling and observations of pregnant 

female polar bears in the autumn 

resulted in significantly lighter female, 

but not male, cubs in spring. Swenson 

et al. (1997) found that pregnant female 

grizzly bears (U. arctos horribilis) that 

abandoned excavated dens pre-birth lost 

cubs at a rate 10 times higher (60%) 

than bears that did not abandon dens 

(6%). 

Although disturbances during the den 

establishment period can result in 

pregnant females abandoning a den site 

and/or incurring energetic or 

reproductive costs, fitness consequences 

are relatively small during this period 

compared to after the birth of cubs 

because females are often able to 

identify and excavate new sites within 

the temporal period that den 

establishment occurs under undisturbed 

conditions (Amstrup 1993; Lunn et al. 

2004). Consequently, prior to giving 

birth, disturbances are unlikely to result 

in injury or a reduction in the 

probability of survival of a pregnant 

female or her cubs. However, responses 

by polar bears to anthropogenic 

activities can lead to the disruption of 

biologically important behaviors 

associated with denning. 

Early Denning 

The second denning period we 

identified, early denning, begins with 

the birth of cubs and ends 60 days after 

birth. Polar bear cubs are altricial and 

are among the most undeveloped 

placental mammals at birth (Ramsay 

and Dunbrack 1986). Newborn polar 

bears weigh ∼0.6 kg, are blind, and have 

limited fat reserves and fur, which 

provides little thermoregulatory value 

(Blix and Lentfer 1979; Kenny and 

Bickel 2005). Roughly 2 weeks after 

birth, their ability to thermoregulate 

begins to improve as they grow longer 

guard hairs and an undercoat (Kenny 

and Bickel 2005). Cubs first open their 

eyes at approximately 35 days after birth 

(Kenny and Bickel 2005) and achieve 

sufficient musculoskeletal development 

to walk at 60–70 days (Kenny and 

Bickel 2005), but movements may still 

be clumsy at this time (Harington 1968). 

At approximately 2 months of age, their 

capacity for thermoregulation may 

facilitate survival outside of the den and 

is the minimum time required for cubs 


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to be able to survive outside of the den. 

However, further development inside 

the den greatly enhances the probability 

of survival (Amstrup 1993, Amstrup and 

Gardner 1994, Smith et al. 2007, Rode 

et al. 2018). Cubs typically weigh 10–12 

kg upon emergence from the den in the 

spring at approximately 3.5 months old 

(Harington 1968, L<n< 1970). 

Based on these developmental 

milestones, we consider 60 days after 

birth to mark the end of the early 

denning period. Currently, we are not 

aware of any studies directly 

documenting birth dates of polar bear 

cubs in the wild; however, several 

studies have estimated parturition based 

on indirect metrics. Van de Velde et al. 

(2003) evaluated historic records of 

bears legally harvested in dens. Their 

findings suggest that cubs were born 

between early December and early 

January. Additionally, Messier et al. 

(1994) found that the activity levels of 

radio-collared females dropped 

significantly in mid-December, leading 

the authors to conclude that a majority 

of births occurred before or around 15 

December. Because cub age is not 

empirically known, we consider early 

denning to end on 13 February, which 

is 60 days after the estimated average 

birth date of 15 December. 

Although disturbance to denning 

bears can be costly at any stage in the 

denning process, consequences in early 

denning can be especially high because 

of the vulnerability of cubs early in their 

development (Elowe and Dodge 1989, 

Amstrup and Gardner 1994, Rode et al. 

2018). If a female leaves a den during 

early denning, cub mortality is likely to 

occur due to a variety of factors 

including susceptibility to cold 

temperatures (Blix and Lentfer 1979, 

Hansson and Thomassen 1983, Van de 

Velde 2003), predation (Derocher and 

Wiig 1999, Amstrup et al. 2006b), and 

mobility limitations (Lentfer 1975). 

Thus, we can expect a high probability 

that cubs will suffer lethal take if they 

emerge early during this stage. Further, 

adult females that depart the den site 

during early denning are likely to 

experience physiological stresses such 

as increased heart rate (Craighead et al. 

1976, Laske et al. 2011) or increased 

body temperature (Reynolds et al. 1986) 

that can result in significant energy 

expenditures (Karprovich et al. 2009, 

Geiser 2013, Evans et al. 2016) thus 

likely resulting in Level B harassment. 

Late Denning 

The third denning period, late 

denning, begins when cubs are ≥60 days 

old and ends at den emergence in the 

spring, which coincides with increases 

in prey availability (Rode et al. 2018b). 

In the SBS, March 15th is the median 

estimated emergence date for landdenning bears (Rode et al. 2018b). 

During late denning, cubs develop the 

ability to travel more efficiently and 

become less susceptible to heat loss, 

which enhances their ability to survive 

after leaving the den (Rode et al. 2018b). 

For example, date of den emergence was 

identified as the most important 

variable influencing cub survival in a 

study of marked polar bears in the CS 

and SBS stocks (Rode et al. 2018b). The 

authors reported that all females that 

denned through the end of March had 

≥ one cub when re-sighted ≤100 days 

after den emergence. Conversely, 

roughly half of the females that emerged 

from dens before the end of February 

did not have cubs when resighted ≤100 

days after emergence, suggesting that 

later den emergence likely results in a 

greater likelihood of cub survival (Rode 

et al. 2018b). Rode et al. (2018b) do note 

several factors that could affect their 

findings; for example, it was not always 

known whether a female emerged from 

a den with cubs (i.e., cubs died before 

re-sighting during the spring surveys). 

Although the potential responses of 

bears to disturbance events (e.g., 

emerging from dens early, abandoning 

dens, physiological changes) during 

early and late denning are the same, 

consequences to cubs differ based on 

their developmental progress. In 

contrast to emergences during early 

denning, which are likely to result in 

cub mortality, emergences during late 

denning do not necessarily result in cub 

mortality because cubs potentially can 

survive outside the den after reaching 

approximately 60 days of age. However, 

because survival increases with time 

spent in the den during late denning, 

disturbances that contribute to an early 

emergence during late denning are 

likely to increase the probability of cub 

mortality, thus leading to a serious 

injury Level A harassment. Similar to 

the early denning period, this form of 

disturbance would also likely lead to 

Level B harassment for adult females. 

Post-Emergence 

The post-emergence period begins at 

den emergence and ends when bears 

leave the den site and depart for the sea 

ice, which can occur up to 30 days after 

emergence (Harington 1968, Jonkel et al. 

1972, Kolenoski and Prevett 1980, 

Hansson and Thomassen 1983, 

Ovsyanikov 1998, Robinson 2014). 

During the post-emergence period, bears 

spend time in and out of the den where 

they acclimate to surface conditions and 

engage in a variety of activities, 

including grooming, nursing, walking, 

playing, resting, standing, digging, and 

foraging on vegetation (Harington 1968; 

Jonkel et al. 1972; Hansson and 

Thomassen 1983; Ovsyanikov 1998; 

Smith et al. 2007, 2013). While mothers 

outside the den spend most of their time 

resting, cubs tend to be more active, 

which likely increases strength and 

locomotion (Harington 1968, Lentfer 

and Hensel 1980, Hansson and 

Thomassen 1983, Robinson 2014). 

Disturbances that elicit an early 

departure from the den site may hinder 

the ability of cubs to travel (Ovsyanikov 

1998), thereby increasing the chances 

for cub abandonment (Haroldson et al. 

2002) or susceptibility to predation 

(Derocher and Wiig 1999, Amstrup et al. 

2006b). 

Considerable variation exists in the 

duration of time that bears spend at 

dens post-emergence, and the 

relationship between the duration and 

cub survival has not been formally 

evaluated. However, a maternal female 

should be highly motivated to return to 

the sea ice to begin hunting and 

replenish her energy stores to support 

lactation, thus, time spent at the den site 

post emergence likely confers some 

fitness benefit to cubs. A disturbance 

that leads the family group to depart the 

den site early during this period 

therefore is likely to lead to a nonserious Level A harassment for the cubs 

and a Level B harassment for the adult 

female. 

Walrus: Human-Walrus Encounters 

Walruses do not inhabit the Beaufort 

Sea frequently and the likelihood of 

encountering walruses during Industry 

operations is low and limited to the 

open-water season. During the time 

period of this ITR, Industry operations 

may occasionally encounter small 

groups of walruses swimming in open 

water or hauled out onto ice floes or 

along the coast. Industry monitoring 

data have reported 38 walruses between 

1995 and 2015, with only a few 

instances of disturbance to those 

walruses (AES Alaska 2015, USFWS 

unpublished data). From 2009 through 

2014, no interactions between walrus 

and Industry were reported in the 

Beaufort Sea ITR region. We have no 

evidence of any physical effects or 

impacts to individual walruses due to 

Industry activity in the Beaufort Sea. 

However, in the Chukchi Sea, where 

walruses are more prevalent, Level B 

harassment is known to sometimes 

occur during encounters with Industry. 

Thus, if walruses are encountered 

during the activities proposed in this 

ITR, the interaction it could potentially 

result in disturbance. 

Human encounters with walruses 

could occur during Industry activities, 


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although such encounters would be rare 

due to the limited distribution of 

walruses in the Beaufort Sea. These 

encounters may occur within certain 

cohorts of the population, such as calves 

or animals under stress. In 2004, a 

suspected orphaned calf hauled-out on 

the armor of Northstar Island numerous 

times over a 48-hour period, causing 

Industry to cease certain activities and 

alter work patterns before the walrus 

disappeared in stormy seas. 

Additionally, a walrus calf was 

observed for 15 minutes during an 

exploration program 60 ft from the dock 

at Cape Simpson in 2006. From 2009 

through 2020, Industry reported no 

similar interactions with walruses. 

In the nearshore areas of the Beaufort 

Sea, stationary offshore facilities could 

produce high levels of noise that have 

the potential to disturb walruses. These 

include Endicott, Hilcorp’s Saltwater 

Treatment Plant (located on the West 

Dock Causeway), Oooguruk, and 

Northstar facilities. The Liberty project 

will also have this potential when it 

commences operations. From 2009 

through 2020, there were no reports of 

walruses hauling out at Industry 

facilities in the Beaufort Sea ITR region. 

Previous observations have been 

reported of walruses hauled out on 

Northstar Island and swimming near the 

Saltwater Treatment Plant. In 2007, a 

female and a subadult walrus were 

observed hauled-out on the Endicott 

Causeway. The response of walruses to 

disturbance stimuli is highly variable. 

Anecdotal observations by walrus 

hunters and researchers suggest that 

males tend to be more tolerant of 

disturbances than females and 

individuals tend to be more tolerant 

than groups. Females with dependent 

calves are considered least tolerant of 

disturbances. In the Chukchi Sea, 

disturbance events are known to cause 

walrus groups to abandon land or ice 

haulouts and occasionally result in 

trampling injuries or cow-calf 

separations, both of which are 

potentially fatal. Calves and young 

animals at terrestrial haulouts are 

particularly vulnerable to trampling 

injuries. However, due to the scarcity of 

walrus haulouts in the ITR area, the 

most likely potential impacts of 

Industry activities include displacement 

from preferred foraging areas, increased 

stress, energy expenditure, interference 

with feeding, and masking of 

communications. Any impact of 

Industry presence on walruses is likely 

to be limited to a few individuals due 

to their geographic range and seasonal 

distribution. 

The reaction of walruses to vessel 

traffic is dependent upon vessel type, 

distance, speed, and previous exposure 

to disturbances. Walruses in the water 

appear to be less readily disturbed by 

vessels than walruses hauled out on 

land or ice. Furthermore, barges and 

vessels associated with Industry 

activities travel in open water and avoid 

large ice floes or land where walruses 

are likely to be found. In addition, 

walruses can use a vessel as a haulout 

platform. In 2009, during Industry 

activities in the Chukchi Sea, an adult 

walrus was observed hauled out on the 

stern of a vessel. 

Walrus: Effects of In-Water Activities 

Walruses hear sounds both in air and 

in water. They have been shown to hear 

from 60 hertz (Hz) to 23 kilohertz (kHz) 

in air (Reichmuth et al. 2020). Tests of 

underwater hearing have shown their 

range to be between 1 kHz and 12 kHz 

with greatest sensitivity at 12 kHz 

(Kastelein et al. 2002). The underwater 

hearing abilities of the Pacific walrus 

have not been studied sufficiently to 

develop species-specific criteria for 

preventing harmful exposure. However, 

sound pressure level thresholds have 

been developed for members of the 

‘‘other carnivore’’ group of marine 

mammals (Table 1). 

When walruses are present, 

underwater noise from vessel traffic in 

the Beaufort Sea may prevent ordinary 

communication between individuals by 

preventing them from locating one 

another. It may also prevent walruses 

from using potential habitats in the 

Beaufort Sea and may have the potential 

to impede movement. Vessel traffic will 

likely increase if offshore Industry 

expands and may increase if warming 

waters and seasonally reduced sea-ice 

cover alter northern shipping lanes. 

The most likely response of walruses 

to acoustic disturbances in open water 

will be for animals to move away from 

the source of the disturbance. 

Displacement from a preferred feeding 

area may reduce foraging success, 

increase stress levels, and increase 

energy expenditures. 

Walrus: Effects of Aircraft Overflights 

Aircraft overflights may disturb 

walruses. Reactions to aircraft vary with 

range, aircraft type, and flight pattern as 

well as walrus age, sex, and group size. 

Adult females, calves, and immature 

walruses tend to be more sensitive to 

aircraft disturbance. Walruses are 

particularly sensitive to changes in 

engine noise and are more likely to 

stampede when planes turn or fly low 

overhead. Researchers conducting aerial 

surveys for walruses in sea-ice habitats 

have observed little reaction to fixedwinged aircraft above 457 m (1,500 ft) 

(USFWS unpubl. data). Although the 

intensity of the reaction to noise is 

variable, walruses are probably most 

susceptible to disturbance by fastmoving and low-flying aircraft (100 m 

(328 ft) above ground level) or aircraft 

that change or alter speed or direction. 

In the Chukchi Sea, there are recent 

examples of walruses being disturbed by 

aircraft flying in the vicinity of 

haulouts. It appears that walruses are 

more sensitive to disturbance when 

hauled out on land versus sea-ice. 

Effects to Prey Species 

Industry activity has the potential to 

impact walrus prey, which are primarily 

benthic invertebrates including 

bivalves, snails, worms, and crustaceans 

(Sheffield and Grebmeier 2009). The 

effects of Industry activities on benthic 

invertebrates would most likely result 

from disturbance of seafloor substrate 

from activities such as dredging or 

screeding, and if oil was illegally 

discharged into the environment. 

Substrate-borne vibrations associated 

with vessel noise and Industry 

activities, such as pile driving and 

drilling, can trigger behavioral and 

physiological responses in bivalves and 

crustaceans (Roberts et al. 2016, Tidau 

and Briffa 2016). In the case of an oil 

spill, oil has the potential to impact 

benthic invertebrate species in a variety 

of ways including, but not limited to, 

mortality due to smothering or toxicity, 

perturbations in the composition of the 

benthic community, as well as altered 

metabolic and growth rates. 

Additionally, bivalves and crustaceans 

can bioaccumulate hydrocarbons, which 

could increase walrus exposure to these 

compounds (Engelhardt 1983). 

Disturbance from Industry activity and 

effects from oil exposure may alter the 

availability and distribution of benthic 

invertebrate species. An increasing 

number of studies are examining 

benthic invertebrate communities and 

food web structure within the Beaufort 

Sea (Rand and Logerwell 2011, Divine et 

al. 2015). The low likelihood of an oil 

spill large enough to affect walrus prey 

populations (see the section titled Risk 

Assessment of Potential Effects Upon 

Polar Bears from a Large Oil Spill in the 

Beaufort Sea) combined with the low 

density of walruses that feed on benthic 

invertebrates in this region during openwater season indicates that Industry 

activities will likely have limited effects 

on walruses through impacted prey 

species. 

The effects of Industry activity upon 

polar bear prey, primarily ringed seals 

and bearded seals, will be similar to that 

of effects upon walruses and primarily 

through noise disturbance or exposure 


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to an oil spill. Seals respond to vessel 

noise and potentially other Industry 

activities. Some seals exhibited a flush 

response, entering water when 

previously hauled out on ice, when 

noticing an icebreaker vessel that ranged 

from 100 m to 800 m away from the seal 

(Lomac-MacNair et al. 2019). This 

disturbance response in addition to 

other behavioral responses could extend 

to other Industry vessels and activities, 

such as dredging (Todd et al. 2015). 

Sounds from Industry activity are 

probably audible to ringed seals and 

harbor seals at distances up to 

approximately 1.5 km in the water and 

approximately 5 km in the air 

(Blackwell et al. 2004). Disturbance 

from Industry activity may cause seals 

to avoid important habitat areas, such as 

pupping lairs or haulouts, and to 

abandon breathing holes near Industry 

activity. However, these disturbances 

appear to have minor, short-term, and 

temporary effects (NMFS 2013). 

Consumption of oiled seals may 

impact polar bears through their 

exposure to oil spills during Industry 

activity (see Evaluation of Effects on Oil 

Spills on Pacific Walruses and Polar 

Bears). Ingestion of oiled seals would 

cause polar bears to ingest oil and 

inhale oil fumes, which can cause tissue 

and organ damage for polar bears 

(Engelhardt 1983). If polar bear fur were 

to become oiled during ingestion of 

oiled seals, this may lead to 

thermoregulation issues, increased 

metabolic activity, and further ingestion 

of oil during grooming (Engelhardt 

1983). Ringed seals that have been 

exposed to oil or ingested oiled prey can 

accumulate hydrocarbons in their 

blubber and liver (Engelhardt 1983). 

These increased levels of hydrocarbons 

may affect polar bears even if seals are 

not oiled during ingestion. Polar bears 

could be impacted by reduced seal 

availability, displacement of seals in 

response to Industry activity, increased 

energy demands to hunt for displaced 

seals, and increased dependency on 

limited alternative prey sources, such as 

scavenging on bowhead whale carcasses 

harvested during subsistence hunts. If 

seal availability were to decrease, then 

the survival of polar bears may be 

drastically affected (Fahd et al. 2021). 

However, apart from a large-scale illegal 

oil spill, impacts from Industry activity 

on seals are anticipated to be minor and 

short-term, and these impacts are 

unlikely to substantially reduce the 

availability of seals as a prey source for 

polar bears. The risk of large-scale oil 

spills is discussed in Risk Assessment of 

Potential Effects upon Polar Bears from 

a Large Oil Spill in the Beaufort Sea. 

Evaluation of Effects of Specified 

Activities on Pacific Walruses, Polar 

Bears, and Prey Species 

Definitions of Incidental Take Under the 

Marine Mammal Protection Act 

Below we provide definitions of three 

potential types of take of Pacific 

walruses or polar bears. The Service 

does not anticipate and is not 

authorizing lethal take or Level A 

harassment as a part of the rule; 

however, the definitions of these take 

types are provided for context and 

background. 

Lethal Take 

Human activity may result in 

biologically significant impacts to polar 

bears or Pacific walruses. In the most 

serious interactions, human actions can 

result in mortality of polar bears or 

Pacific walruses. We also note that, 

while not considered incidental, in 

situations where there is an imminent 

threat to human life, polar bears may be 

killed. Additionally, though not 

considered incidental, polar bears have 

been accidentally killed during efforts to 

deter polar bears from a work area for 

safety and from direct chemical 

exposure (81 FR 52276, August 5, 2016). 

Incidental lethal take could result from 

human activity such as a vehicle 

collision or collapse of a den if it were 

run over by a vehicle. Unintentional 

disturbance of a female by human 

activity during the denning season may 

cause the female either to abandon her 

den prematurely with cubs or abandon 

her cubs in the den before the cubs can 

survive on their own. Either scenario 

may result in the incidental lethal take 

of the cubs. Incidental lethal take of 

Pacific walrus could occur if the animal 

were directly struck by a vessel, or 

trampled by other walruses in a humancaused stampede. 

Level A Harassment 

Human activity may result in the 

injury of polar bears or Pacific walruses. 

Level A harassment, for nonmilitary 

readiness activities, is defined as any act 

of pursuit, torment, or annoyance that 

has the potential to injure a marine 

mammal or marine mammal stock in the 

wild. Take by Level A harassment can 

be caused by numerous actions such as 

creating an annoyance that separates 

mothers from dependent cub(s)/calves 

(Amstrup 2003), results in polar bear 

mothers leaving the den early (Amstrup 

and Gardner 1994, Rode et al. 2018b), or 

interrupts the nursing or resting of cubs/ 

calves. For this ITR, we have also 

distinguished between non-serious and 

serious Level A harassment. Serious 

Level A harassment is defined here as 

an injury that is likely to result in 

mortality. 

Level A harassment to bears on the 

surface is extremely rare within the ITR 

region. From 2012 through 2018, one 

instance of Level A harassment occurred 

within the ITR region associated with 

defense of human life while engaged in 

non-Industry activity. No Level A 

harassment to Pacific walruses has been 

reported in the Beaufort Sea ITR region. 

Given this information, the Service does 

not estimate Level A harassment to 

polar bears or Pacific walruses will 

result from the activities specified in 

AOGA’s Request. Nor has Industry 

anticipated or requested authorization 

for such take in their Request for ITRs. 

Level B Harassment 

Level B Harassment for nonmilitary 

readiness activities means any act of 

pursuit, torment, or annoyance that has 

the potential to disturb a marine 

mammal or marine mammal stock in the 

wild by causing disruption of behaviors 

or activities, including, but not limited 

to, migration, breathing, nursing, 

feeding, or sheltering. Changes in 

behavior that disrupt biologically 

significant behaviors or activities for the 

affected animal meet the criteria for take 

by Level B harassment under the 

MMPA. Reactions that indicate take by 

Level B harassment of polar bears in 

response to human activity include, but 

are not limited to, the following: 

• Fleeing (running or swimming away 

from a human or a human activity); 

• Displaying a stress-related behavior 

such as jaw or lip-popping, front leg 

stomping, vocalizations, circling, 

intense staring, or salivating; 

• Abandoning or avoiding preferred 

movement corridors such as ice floes, 

leads, polynyas, a segment of coastline, 

or barrier islands; 

• Using a longer or more difficult 

route of travel instead of the intended 

path; 

• Interrupting breeding, sheltering, or 

feeding; 

• Moving away at a fast pace (adult) 

and cubs struggling to keep up; 

• Ceasing to nurse or rest (cubs); 

• Ceasing to rest repeatedly or for a 

prolonged period (adults); 

• Loss of hunting opportunity due to 

disturbance of prey; or 

• Any interruption in normal denning 

behavior that does not cause injury, den 

abandonment, or early departure of the 

family group from the den site. 

This list is not meant to encompass all 

possible behaviors; other behavioral 

responses may equate to take by Level 

B harassment. Relatively minor changes 

in behavior such as increased vigilance 

or a short-term change in direction of 


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43014 Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 

travel are not likely to disrupt 

biologically important behavioral 

patterns, and the Service does not view 

such minor changes in behavior as 

resulting in a take by Level B 

harassment. It is also important to note 

that depending on the duration, 

frequency, or severity of the abovedescribed behaviors, such responses 

could constitute take by Level A 

harassment (e.g., repeatedly disrupting a 

polar bear versus a single interruption). 

Evaluation of Take 

The general approach for quantifying 

take in this ITR was as follows: (1) 

Determine the number of animals in the 

project area; (2) assess the likelihood, 

nature, and degree of exposure of these 

animals to project-relative activities; (3) 

evaluate these animals’ probable 

responses; and (4) calculate how many 

of these responses constitute take. Our 

evaluation of take included quantifying 

the probability of either lethal take or 

Level A harassment (potential injury) 

and quantifying the number of 

responses that met the criteria for Level 

B harassment (potential disruption of a 

biologically significant behavioral 

pattern), factoring in the degree to 

which effective mitigation measures that 

may be applied will reduce the amount 

or consequences of take. To better 

account for differences in how various 

aspects of the project could impact polar 

bears, we performed separate take 

estimates for Surface-Level Impacts, 

Aircraft Activities, Impacts to Denning 

Bears, and Maritime Activities. These 

analyses are described in more detail in 

the subsections below. Once each of 

these categories of take were quantified, 

the next steps were to: (5) Determine 

whether the total take will be of a small 

number relative to the size of the 

species or stock; and (6) determine 

whether the total take will have a 

negligible impact on the species or 

stock, both of which are determinations 

required under the MMPA. 

Pacific Walrus: All Interactions 

With the low occurrence of walruses 

in the Beaufort Sea and the adoption of 

the mitigation measures required by this 

ITR, the Service concludes that the only 

anticipated effects from Industry noise 

in the Beaufort Sea would be short-term 

behavioral alterations of small numbers 

of walruses. All walrus encounters 

within the ITR geographic area in the 

past 10 years have been of solitary 

walruses or groups of two. The closest 

sighting of a grouping larger than two 

was outside the ITR area in 2013. The 

vessel encountered a group of 15 

walrus. Thus, while it is highly unlikely 

that a group of walrus will be 

encountered during the proposed 

activities, we estimate that no more than 

one group of 15 Pacific walruses will be 

taken as a result of Level B harassment 

each year during the ITR period. 

Polar Bear: Surface Interactions 

Encounter Rate 

The most comprehensive dataset of 

human–polar bear encounters along the 

coast of Alaska consists of records of 

Industry encounters during activities on 

the North Slope submitted to the 

Service under existing and previous 

ITRs. This database is referred to as the 

‘‘LOA database’’ because it aggregates 

data reported by the oil and gas industry 

to the Service pursuant to the terms and 

conditions of LOAs issued under 

current and previous incidental take 

regulations (50 CFR part 18, subpart J). 

We have used records in the LOA 

database in the period 2014–2018, in 

conjunction with bear density 

projections for the entire coastline, to 

generate quantitative encounter rates in 

the project area. This 5-year period was 

used to provide metrics that reflected 

the most recent patterns of polar bear 

habitat use within the Beaufort Sea ITR 

region. Each encounter record includes 

the date and time of the encounter, a 

general description of the encounter, 

number of bears encountered, latitude 

and longitude, weather variables, and a 

take determination made by the Service. 

If latitude and longitude were not 

supplied in the initial report, we 

georeferenced the encounter using the 

location description and a map of North 

Slope infrastructure. 

Spatially Partitioning the North Slope 

Into ‘‘Coastal’’ and ‘‘Inland’’ Zones 

The vast majority of SBS polar bear 

encounters along the Alaskan coast 

occur along the shore or immediately 

offshore (Atwood et al. 2015, Wilson et 

al. 2017). Thus, encounter rates for 

inland operations should be 

significantly lower than those for 

offshore or coastal operations. To 

partition the North Slope into ‘‘coastal’’ 

and ‘‘inland’’ zones, we calculated the 

distance to shore for all encounter 

records in the period 2014–2018 in the 

Service’s LOA database using a 

shapefile of the coastline and the 

dist2Line function found in the R 

geosphere package (Hijmans 2019). 

Linked sightings of the same bear(s) 

were removed from the analysis, and 

individual records were created for each 

bear encountered. However, because we 

were able to identify and remove only 

repeated sightings that were designated 

as linked within the database, it is likely 

that some repeated encounters of the 

same bear remained in our analysis. 

From 2014 through 2018, of the 1,713 

bears encountered, 1,140 (66.5 percent) 

were offshore. While these bears were 

encountered offshore, the encounters 

were reported by onshore or island 

operations (i.e., docks, drilling and 

production islands, or causeways). We 

examined the distribution of bears that 

were onshore and up to 10 km (6.2 mi) 

inland to determine the distance at 

which encounters sharply decreased 

(Figure 2). 

BILLING CODE 4333–15–P 


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The histogram illustrates a steep 

decline in human–polar bear encounters 

at 2 km (1.2 mi) from shore. Using this 

data, we divided the North Slope into 

the ‘‘coastal zone,’’ which includes 

offshore operations and up to 2 km (1.2 

mi) inland, and the ‘‘inland zone,’’ 

which includes operations more than 2 

km (1.2 mi) inland. 

Dividing the Year Into Seasons 

As we described in our review of 

polar bear biology above, the majority of 

polar bears spend the winter months on 

the sea ice, leading to few polar bear 

encounters on the shore during this 

season. Many of the proposed activities 

are also seasonal, and only occur either 

in the winter or summer months. In 

order to develop an accurate estimate of 

the number of polar bear encounters 

that may result from the proposed 

activities, we divided the year into 

seasons of high bear activity and low 

bear activity using the Service’s LOA 

database. Below is a histogram of all 

bear encounters from 2014 through 2018 

by day of the year (Julian date). Two 

clear seasons of polar bear encounters 

can be seen: an ‘‘open-water season’’ 

that begins in mid-July and ends in midNovember, and an ‘‘ice season’’ that 

begins in mid-November and ends in 

mid-July. The 200th and 315th days of 

the year were used to delineate these 

seasons when calculating encounter 

rates (Figure 3). 


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Histogram of Onshore Encounters 

200-

150-

50-

o- I 

0.0 I 2.5 I 5.0 

Distance to Shore (km) 

I 

7.5 

Figure 2-Distribution of onshore polar bear encounters on the North Slope of Alaska in 

the period 2014--2018 by distance to shore (km). The decrease in encounters was used to 

designate a "coastal" zone up to 2.0 km (1.2 mi) from shore and an "inland" zone greater 

than 2.0 km (1.2 mi) from shore. 
43016 Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 

North Slope Encounter Rates 

Encounter rates in bears/season/km2

were calculated using a subset of the 

Industry encounter records maintained 

in the Service’s LOA database. The 

following formula was used to calculate 

encounter rate (Equation 1): 

The subset consisted of encounters in 

areas that were constantly occupied 

year-round to prevent artificially 

inflating the denominator of the 

equation and negatively biasing the 

encounter rate. To identify constantly 

occupied North Slope locations, we 

gathered data from a number of sources. 

We used past LOA requests to find 

descriptions of projects that occurred 

anywhere within 2014–2018 and the 

final LOA reports to determine the 

projects that proceeded as planned and 

those that were never completed. 

Finally, we relied upon the institutional 

knowledge of our staff, who have 

worked with operators and inspected 

facilities on the North Slope. To 

determine the area around industrial 

facilities in which a polar bear can be 

seen and reported, we queried the 

Service LOA database for records that 

included the distance to an encountered 

polar bear. It is important to note that 

these values may represent the closest 

distance a bear came to the observer or 

the distance at initial contact. Therefore, 

in some cases, the bear may have been 

initially encountered farther than the 

distance recorded. The histogram of 

these values shows a drop in the 

distance at which a polar bear is 

encountered at roughly 1.6 km (1 mi) 

(Figure 4). 


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Histogram of Encounters by Day of Year 

40· 

30· 

§ 

0 

0 20-

10· 

o200 

Day of Year 

Figure 3-Distribution of polar bear encounters in the Southern Beaufort Sea and 

adjacent North Slope of Alaska in the period 2014-2018 by Julian day of year. Dotted 

lines delineate the "open" vs. "ice" seasons. Open season begins on the 200th day of the 

year (July 19th) and ends on the 315th day of the year (November 11th). 

Bears Encountered by Season 

Area Occupied (km2 ) 

Equation 1 
Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 43017 

BILLING CODE 4333–15–C 

Using this information, we buffered 

the 24-hour occupancy locations listed 

above by 1.6 km (1 mi) and calculated 

an overall search area for both the 

coastal and inland zones. The coastal 

and inland occupancy buffer shapefiles 

were then used to select encounter 

records that were associated with 24- 

hour occupancy locations, resulting in 

the number of bears encountered per 

zone. These numbers were then 

separated into open-water and ice 

seasons (Table 2). 

TABLE 2—SUMMARY OF ENCOUNTERS OF POLAR BEARS ON THE NORTH SLOPE OF ALASKA IN THE PERIOD 2014–2018 

WITHIN 1.6 KM (1 MI) OF THE 24-HOUR OCCUPANCY LOCATIONS AND SUBSEQUENT ENCOUNTER RATES FOR COASTAL

(A) AND INLAND (B) ZONES

Year Ice season 

encounters 

Open-water 

season 

encounters 

(A) Coastal Zone (Area = 133 km2) 

2014 ............................................................................................................................................................. 2 193 

2015 ............................................................................................................................................................. 8 49 

2016 ............................................................................................................................................................. 4 227 

2017 ............................................................................................................................................................. 7 313 

2018 ............................................................................................................................................................. 13 205 

Average ........................................................................................................................................................ 6.8 197.4 

Seasonal Encounter Rate ............................................................................................................................ 0.05 bears/km2 1.48 bears/km2

(B) Inland Zone (Area = 267 km2) 

2014 ............................................................................................................................................................. 3 3 

2015 ............................................................................................................................................................. 0 0 

2016 ............................................................................................................................................................. 0 2 

2017 ............................................................................................................................................................. 3 0 

2018 ............................................................................................................................................................. 0 2 

Average ........................................................................................................................................................ 1.2 1.4 

Seasonal Encounter Rate ............................................................................................................................ 0.004 bears/km2 0.005 bears/km2


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Distance to polar bears when encountered 

1::! 

::, 

0 

20-

15· 

u 10-

o- I 

0 

I 

2000 I 4000 

Distance to Bear (m) 

I 

6000 

Figure 4-Distribution of polar bear encounters on the North Slope of Alaska in the 

period 2014--2018 by distance to bear (m). 
43018 Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 

Harassment Rate 

The Level B harassment rate or the 

probability that an encountered bear 

will experience either incidental or 

intentional Level B harassment, was 

calculated using the 2014–2018 dataset 

from the LOA database. A binary 

logistic regression of harassment 

regressed upon distance to shore was 

not significant (p = 0.65), supporting the 

use of a single harassment rate for both 

the coastal and inland zones. However, 

a binary logistic regression of 

harassment regressed upon day of the 

year was significant. This significance 

held when encounters were binned into 

either ice or open-water seasons 

(p<0.0015). 

We subsequently estimated the 

harassment rate for each season with a 

Bayesian probit regression with season 

as a fixed effect (Hooten and Hefley 

2019). Model parameters were estimated 

using 10,000 iterations of a Markov 

chain Monte Carlo algorithm composed 

of Gibbs updates implemented in R (R 

core team 2021, Hooten and Hefley 

2019). We used Normal (0,1) priors, 

which are uninformative on the prior 

predictive scale (Hobbs and Hooten 

2015), to generate the distribution of 

open-water and ice-season marginal 

posterior predictive probabilities of 

harassment. The upper 99 percent 

quantile of each probability distribution 

can be interpreted as the upper limit of 

the potential harassment rate supported 

by our dataset (i.e., there is a 99 percent 

chance that given the data the 

harassment rate is lower than this 

value). We chose to use 99 percent 

quantiles of the probability distributions 

to account for any negative bias that has 

been introduced into the dataset 

through unobserved harassment or 

variability in the interpretation of polar 

bear behavioral reactions by multiple 

observers. The final harassment rates 

were 0.19 during the open-water season 

and 0.37 during the ice season (Figure 

5). 

Impact Area 

As noted above, we have calculated 

encounter rates depending on the 

distance from shore and season and take 

rates depending on season. To properly 

assess the area of potential impact from 

the project activities, we must calculate 

the area affected by project activities to 

such a degree that harassment is 

possible. This is sometimes referred to 

as a zone or area of influence. 

Behavioral response rates of polar bears 

to disturbances are highly variable, and 

data to support the relationship between 

distance to bears and disturbance is 

limited. Dyck and Baydack (2004) found 

sex-based differences in the frequencies 

of vigilant bouts of polar bears in the 

presence of vehicles on the tundra. 

However, in their summary of polar bear 

behavioral response to ice-breaking 

vessels in the Chukchi Sea, Smultea et 

al. (2016) found no difference between 

reactions of males, females with cubs, or 

females without cubs. During the 

Service’s coastal aerial surveys, 99 

percent of polar bears that responded in 

a way that indicated possible Level B 

harassment (polar bears that were 

running when detected or began to run 

or swim in response to the aircraft) did 

so within 1.6 km (1 mi), as measured 

from the ninetieth percentile horizontal 

detection distance from the flight line. 

Similarly, Andersen and Aars (2008) 

found that female polar bears with cubs 

(the most conservative group observed) 

began to walk or run away from 

approaching snowmobiles at a mean 

distance of 1,534 m (0.95 mi). Thus, 

while future research into the reaction 

of polar bears to anthropogenic 

disturbance may indicate a different 

zone of potential impact is appropriate, 

the current literature supports the use of 

a 1.6 km (1.0 mi) impact area, as it will 

encompass the vast majority of polar 

bear harassment events. 

Correction Factor 

While the locations that were used to 

calculate encounter rates are thought to 

have constant human occupancy, it is 

possible that bears may be in the 


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~ ·w 

~ 20 +·l~····~---~--1----: 

"'C 

0.0 0.1 0.2 0.3 0.4 

P( level B I encounter ) 

season 

■ ice 

■ openwater 

0.5 

Figure 5-Estimated marginal posterior predictive probabilities from the Bayesian pro bit 

regression of Level B harassment of polar bears on the North Slope of Alaska in the 

period 2014-2018. Vertical grey lines correspond to the upper 99% quantiles for each 

distribution, which were used as the estimates of harassment rates. 
Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 43019 

vicinity of industrial infrastructure and 

not be noticed by humans. These 

unnoticed bears may also experience 

Level B harassment. To determine 

whether our calculated encounter rate 

should be corrected for unnoticed bears, 

we compared our encounter rates to 

Wilson et al.’s (2017) weekly average 

polar bear estimates along the northern 

coast of Alaska and the South Beaufort 

Sea. 

Wilson et al.’s weekly average 

estimate of polar bears across the coast 

was informed by aerial surveys 

conducted by the Service in the period 

2000–2014 and supplemented by daily 

counts of polar bears in three highdensity barrier islands (Cross, Barter, 

and Cooper Islands). Using a Bayesian 

hierarchical model, the authors 

estimated 140 polar bears would be 

along the coastline each week between 

the months of August and October. 

These estimates were further partitioned 

into 10 equally sized grids along the 

coast. Grids 4–7 overlap the SBS ITR 

area, and all three encompass several 

industrial facilities. Grid 6 was 

estimated to account for 25 percent of 

the weekly bear estimate (35 bears); 

however, 25 percent of the bears in grid 

6 were located on Cross Island. Grids 5 

and 7 were estimated to contain seven 

bears each, weekly. Using raw aerial 

survey data, we calculated the number 

of bears per km of surveyed mainland 

and number of bears per km of surveyed 

barrier islands for each Service aerial 

survey from 2010 through 2014 to 

determine the proportion of bears on 

barrier islands versus the mainland. On 

average, 1.7 percent, 7.2 percent, and 14 

percent of bears were sighted on the 

mainland in grids 5, 6, and 7, 

respectively. 

While linked encounter records in the 

LOA database were removed in earlier 

formatting, it is possible that a single 

bear may be the focus of multiple 

encounter records, particularly if the 

bear moves between facilities operated 

by different entities. To minimize 

repeated sightings, we designated a 

single industrial infrastructure location 

in each grid: Oliktok Point in grid 5, 

West Beach in grid 6, and Point 

Thomson’s CP in grid 7. These locations 

were determined in earlier analyses to 

have constant 24-occupancy; thus, if a 

polar bear were within the viewing area 

of these facilities, it must be reported as 

a condition of each entity’s LOA. 

Polygons of each facility were 

buffered by 1.6 km (1 mi) to account for 

the industrial viewing area (see above), 

and then clipped by a 400-m (0.25-mi) 

buffer around the shoreline to account 

for the area in which observers were 

able to reliably detect polar bears in the 

Service’s aerial surveys (i.e., the specific 

area to which the Wilson et al.’s model 

predictions applied). Industrial 

encounters within this area were used to 

generate the average weekly number of 

polar bears from August through 

October. Finally, we divided these 

numbers by area to generate average 

weekly bears/km2 and multiplied this 

number by the total coastal Service 

aerial survey area. The results are 

summarized in the table below 

(Table 3). 

TABLE 3—COMPARISON OF POLAR BEAR ENCOUNTERS TO NUMBER OF POLAR BEARS PROJECTED BY WILSON ET AL. 

2017 AT DESIGNATED POINT LOCATIONS ON THE COAST OF THE NORTH SLOPE OF ALASKA

Grid 5 Grid 6 Grid 7 

Total coastline viewing area (km2) .............................................................................................. 34 45 33.4 

Industry viewing area (km2) ......................................................................................................... 0.31 0.49 1.0 

Proportion of coastline area viewed by point location ................................................................ 0.009 0.011 0.030 

Average number of bears encountered August–October at point location ................................. 3.2 4.6 28.8 

Number of weeks in analysis ...................................................................................................... 13 13 13 

Average weekly number of bears reported at point location ...................................................... 0.246 0.354 2.215 

Average weekly number of bears projected in grid* ................................................................... 7 26 7 

Average weekly number of bears projected for point location .................................................... 0.064 0.283 0.210 

These comparisons show a greater 

number of industrial sightings than 

would be estimated by the Wilson et al. 

2017 model. There are several potential 

explanations for higher industrial 

encounters than projected by model 

results. Polar bears may be attracted to 

industrial infrastructure, the encounters 

documented may be multiple sightings 

of the same bear, or specifically for the 

Point Thomson location, higher 

numbers of polar bears may be 

travelling past the pad to the Kaktovik 

whale carcass piles. However, because 

the number of polar bears estimated 

within the point locations is lower than 

the average number of industrial 

sightings, these findings cannot be used 

to create a correction factor for 

industrial encounter rate. To date, the 

data needed to create such a correction 

factor (i.e., spatially explicit polar bear 

densities across the North Slope) have 

not been generated. 

Estimated Harassment 

We estimated Level B harassment 

using the spatio-temporally specific 

encounter rates and temporally specific 

take rates derived above in conjunction 

with AOGA supplied spatially and 

temporally specific data. Table 4 

provides the definition for each variable 

used in the take formulas. 


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43020 Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 

The variables defined above were 

used in a series of formulas to 

ultimately estimate the total harassment 

from surface-level interactions. 

Encounter rates were originally 

calculated as bears encountered per 

square kilometer per season (see North 

Slope Encounter Rates above). As a part 

of their Request, AOGA provided the 

Service with digital geospatial files that 

included the maximum expected human 

occupancy (i.e., rate of occupancy (ro)) 

for each individual structure (e.g., each 

road, pipeline, well pad, etc.) of their 

proposed activities for each month of 

the ITR period. Months were averaged 

to create open-water and ice-season 

occupancy rates. For example, 

occupancy rates for July 2022, August 

2022, September 2022, October 2022, 

and November 2022 were averaged to 

calculate the occupancy rate for a given 

structure during the open-water 2022 

season. Using the buffer tool in ArcGIS, 

we created a spatial file of a 1.6-km (1- 

mi) buffer around all industrial 

structures. We binned the structures 

according to their seasonal occupancy 

rates by rounding them up into tenths 

(10 percent, 20 percent, etc.). We 

determined the impact area of each bin 

by first calculating the area within the 

buffers of 100 percent occupancy 

locations. We then removed the spatial 

footprint of the 100 percent occupancy 

buffers from the dataset and calculated 

the area within the 90 percent 

occupancy buffers. This iterative 

process continued until we calculated 

the area within all buffers. The areas of 

impact were then clipped by coastal and 

inland zone shapefiles to determine the 

coastal areas of impact (ac) and inland 

areas of impact (ai) for each activity 

category. We then used spatial files of 

the coastal and inland zones to 

determine the area in coastal verse 

inland zones for each occupancy 

percentage. This process was repeated 

for each season from open-water 2021 to 

open-water 2026. 

Impact areas were multiplied by the 

appropriate encounter rate to obtain the 

number of bears expected to be 

encountered in an area of interest per 

season (Bes). The equation below 

(Equation 3) provides an example of the 

calculation of bears encountered in the 

ice season for an area of interest in the 

coastal zone. 

To generate the number of estimated 

Level B harassments for each area of 

interest, we multiplied the number of 

bears in the area of interest per season 

by the proportion of the season the area 

is occupied, the rate of occupancy, and 

the harassment rate (Equation 4). 


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Table 4-Definitions of variables used in take estimates of polar bears on the coast of the 

North Slope of Alaska. 

Variable 

Bes 

Ge 

Gi 

ro 

eco 

eci 

eio 

eii 

fi 

fa 

Bt 

Br 

Definition 

bears encountered in an area of interest for the entire season 

coastal exposure area 

inland exposure area 

occupancy rate 

coastal open-water season bear-encounter rate in bears/season 

coastal ice season bear-encounter rate in bears/season 

inland open-water season bear-encounter rate in bears/season 

inland ice season bear-encounter rate in bears/season 

ice season harassment rate 

open-water season harassment rate 

number of estimated Level B harassment events 

total bears harassed for activit e 

Equation 3 

Equation 4 
Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 43021 

The estimated harassment values for 

the open-water 2021 and open-water 

2026 seasons were adjusted to account 

for incomplete seasons as the 

regulations will be effective for only 85 

and 15 percent of the open-water 2021 

and 2026 seasons, respectively. 

Aircraft Impact to Surface Bears 

Polar bears in the project area will 

likely be exposed to the visual and 

auditory stimulation associated with 

AOGA’s fixed-wing and helicopter flight 

plans; however, these impacts are likely 

to be minimal and not long-lasting to 

surface bears. Flyovers may cause 

disruptions in the polar bear’s normal 

behavioral patterns, thereby resulting in 

incidental Level B harassment. Sudden 

changes in direction, elevation, and 

movement may also increase the level of 

noise produced from the helicopter, 

especially at lower altitudes. This 

increased level of noise could disturb 

polar bears in the area to an extent that 

their behavioral patterns are disrupted 

and Level B harassment occurs. 

Mitigation measures, such as minimum 

flight altitudes over polar bears and 

restrictions on sudden changes to 

helicopter movements and direction, 

will be required to reduce the likelihood 

that polar bears are disturbed by aircraft. 

Once mitigated, such disturbances are 

expected to have no more than shortterm, temporary, and minor impacts on 

individual bears. 

Estimating Harassment Rates of Aircraft 

Activities 

To predict how polar bears will 

respond to fixed-wing and helicopter 

overflights during North Slope oil and 

gas activities, we first examined existing 

data on the behavioral responses of 

polar bears during aircraft surveys 

conducted by the Service and U.S. 

Geological Survey (USGS) between 

August and October during most years 

from 2000 to 2014 (Wilson et al. 2017, 

Atwood et al. 2015, and Schliebe et al. 

2008). Behavioral responses due to sight 

and sound of the aircraft have both been 

incorporated into this analysis as there 

was no ability to differentiate between 

the two response sources during aircraft 

survey observations. Aircraft types used 

for surveys during the study included a 

fixed-wing Aero-Commander from 2000 

to 2004, a R–44 helicopter from 2012 to 

2014, and an A-Star helicopter for a 

portion of the 2013 surveys. During 

surveys, all aircraft flew at an altitude 

of approximately 90 m (295 ft) and at a 

speed of 150 to 205 km per hour (km/ 

h) or 93 to 127 mi per hour (mi/h). 

Reactions indicating possible incidental 

Level B harassment were recorded when 

a polar bear was observed running from 

the aircraft or began to run or swim in 

response to the aircraft. Of 951 polar 

bears observed during coastal aerial 

surveys, 162 showed these reactions, 

indicating that the percentage of Level 

B harassments during these low-altitude 

coastal survey flights was as high as 17 

percent. 

Detailed data on the behavioral 

responses of polar bears to the aircraft 

and the distance from the aircraft each 

polar bear was observed were available 

for only the flights conducted between 

2000 to 2004 (n = 581 bears). The AeroCommander 690 was used during this 

period. The horizontal detection 

distance from the flight line was 

recorded for all groups of bears 

detected. To determine if there was an 

effect of distance on the probability of 

a response indicative of potential Level 

B harassment, we modeled the binary 

behavioral response by groups of bears 

to the aircraft with Bayesian probit 

regression (Hooten and Hefley 2019). 

We restricted the data to those groups 

observed less than 10 km from the 

aircraft, which is the maximum distance 

at which behavioral responses were 

likely to be reliably recorded. 

In nearly all cases when more than 

one bear was encountered, every 

member of the group exhibited the same 

response, so we treated the group as the 

sampling unit, yielding a sample size of 

346 groups. Of those, 63 exhibited 

behavioral responses. Model parameters 

were estimated using 10,000 iterations 

of a Markov chain Monte Carlo 

algorithm composed of Gibbs updates 

implemented in R (R core team 2021, 

Hooten and Hefley 2019). Normal (0,1) 

priors, which are uninformative on the 

prior predictive scale (Hobbs and 

Hooten 2015), were placed on model 

parameters. Distance to bear as well as 

squared distance (to account for 

possible non-linear decay of probability 

with distance) were included as 

covariates. However, the 95 percent 

confidence intervals for the estimated 

coefficients overlapped zero suggesting 

no significant effect of distance on polar 

bears’ behavioral responses. While it is 

likely that bears do respond differently 

to aircraft at different distances, the data 

available is heavily biased towards very 

short distances because the coastal 

surveys are designed to observe bears 

immediately along the coast. We were 

thus unable to detect any effect of 

distance. Therefore, to estimate a single 

rate of harassment, we fit an interceptonly model and used the distribution of 

the marginal posterior predictive 

probability to compute a point estimate. 

Because the data from the coastal 

surveys were not systematically 

collected to study polar bear behavioral 

responses to aircraft, the data likely bias 

the probability of behavioral response 

low. We, therefore, chose the upper 99th 

percentile of the distribution as our 

point estimate of the probability of 

potential harassment. This equated to a 

harassment rate of 0.23. Because we 

were not able to detect an effect of 

distance, we could not correlate 

behavioral responses with profiles of 

sound pressure levels for the AeroCommander (the aircraft used to collect 

the survey data). Therefore, we could 

also not use that relationship to 

extrapolate behavioral responses to 

sound profiles for takeoffs and landings 

nor sound profiles of other aircraft. 

Accordingly, we applied the single 

harassment rate to all portions of all 

aircraft flight paths. 

General Approach to Estimating 

Harassment for Aircraft Activities 

Aircraft information was determined 

using details provided in AOGA’s 

Request, including flight paths, flight 

take-offs and landings, altitudes, and 

aircraft type. More information on the 

altitudes of future flights can be found 

in the Request. If no location or 

frequency information was provided, 

flight paths were approximated based 

on the information provided. Of the 

flight paths that were described clearly 

or were addressed through assumptions, 

we marked the approximate flight path 

start and stop points using ArcGIS Pro 

(version 2.4.3), and the paths were 

drawn. For flights traveling between two 

airstrips, the paths were reviewed and 

duplicated as closely as possible to the 

flight logs obtained from 

www.FlightAware.com (FlightAware), a 

website that maintains flight logs in the 

public domain. For flight paths where 

airstrip information was not available, a 

direct route was assumed. Activities 

such as pipeline inspections followed a 

route along the pipeline with the 

assumption the flight returned along the 

same route unless a more direct path 

was available. 

Flight paths were broken up into 

segments for landing, take-off, and 

traveling to account for the length of 

time the aircraft may be impacting an 

area based on flight speed. The distance 

considered the ‘‘landing’’ area is based 

on approximately 4.83 km (3 mi) per 

305 m (1,000 ft) of altitude descent 

speed. For all flight paths at or 

exceeding an altitude of 152.4 m (500 

ft), the ‘‘take-off’’ area was marked as 

2.41 km (1.5 mi) derived from flight logs 

found through FlightAware, which 

suggested that ascent to maximum flight 

altitude took approximately half the 

time of the average descent. The 

remainder of the flight path that 


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43022 Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 

stretches between two air strips was 

considered the ‘‘traveling’’ area. We 

then applied the exposure area of 1,610 

m (1 mi) along the flight paths. The data 

used to estimate the probability of Level 

B harassments due to aircraft (see 

section Estimating Harassment Rates of 

Aircraft Activities) suggested 99% of 

groups of bears were observed within 

1.6 km of the aircraft. 

We then differentiated the coastal and 

inland zones. The coastal zone was the 

area offshore and within 2 km (1.2 mi) 

of the coastline (see section Spatially 

Partitioning the North Slope into 

‘‘coastal’’ and ‘‘inland’’ zones), and the 

inland zone was anything greater than 2 

km (1.2 mi) from the coastline. We 

calculated the areas in square kilometers 

for the exposure area within the coastal 

zone and the inland zone for all takeoffs, landings, and traveling areas. For 

flights that involve an inland and a 

coastal airstrip, we considered landings 

to occur at airstrips within the coastal 

zone. Seasonal encounter rates 

developed for both the coastal and 

inland zones (see section Search Effort 

Buffer) were applied to the appropriate 

segments of each flight path. 

Surface encounter rates were 

calculated based on the number of bears 

per season (see section Search Effort 

Buffer). To apply these rates to aircraft 

activities, we needed to calculate a 

proportion of the season in which 

aircraft were flown. However, the 

assumption involved in using a seasonal 

proportion is that the area is impacted 

for an entire day (i.e., for 24 hours). 

Therefore, to prevent estimating impacts 

along the flight path over periods of 

time where aircraft are not present, we 

calculated a proportion of the day the 

area will be impacted by aircraft 

activities for each season (Table 5). 

BILLING CODE 4333–15–P 


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Table 5-Variable definitions and constant values used in polar bear harassment 

estimates for winter and summer aircraft activities on the coast of the North Slope of 

Alaska. 

Variable Definition Value 

ds days in each season open-water season= 116, 

ice season = 249 

Sp proportion of the season an area of interest is varies by flight 

impacted 

f flight frequency varies by flight 

Dp(LT) proportion of the day landing/take-off areas varies by flight 

are impacted by aircraft activities 

tLT amount of time an aircraft is impacting 10 minutes per flight 

landing/take-off areas within a day 

Dp(TR) proportion of the day traveling areas are varies by flight 

impacted by aircraft activities 

tTR amount of time an aircraft is impacting 1.5 minutes per 3.22 km 

traveling areas f2 mil segment per flight 

X number of 3.22-km (2-mi) segments within varies by flight 

each traveling area 

Bes bears encountered in an area of interest for the varies by flight 

entire season 

B; bears impacted by aircraft activities varies by flight 

ac coastal exposure area 1,610 m (1 mi) 

a; inland exposure area 1,610 m (1 mi) 

eco coastal open-water season bear-encounter rate 3.45 bears/km2/season 

in bears/season 

eci coastal ice season bear-encounter rate in 0 .118 bears/km2 I season 

bears/ season 

eio inland open-water season bear-encounter rate 0.0116 bears/km2 I season 

in bears/season 

eii inland ice season bear-encounter rate in 0.0104 bears/km2 I season 

bears/ season 

fa aircraft harassment rate 0.23 

B1 number of estimated level B harassments varies by flight 
Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 43023 

The number of times each flight path 

was flown (i.e., flight frequency) was 

determined from the Request. We used 

the description combined with the 

approximate number of weeks and 

months within the open-water season 

and the ice season to determine the total 

number of flights per season for each 

year (f). We then used flight frequency 

and number of days per season (ds) to 

calculate the seasonal proportion of 

flights (Sp; Equation 6). 

After we determined the seasonal 

proportion of flights, we estimated the 

amount of time an aircraft would be 

impacting the landing/take-off areas 

within a day (tLT). Assuming an aircraft 

is not landing at the same time another 

is taking off from the same airstrip, we 

estimated the amount of time an aircraft 

would be present within the landing or 

take-off zone would be tLT = 10 minutes. 

We then calculated how many minutes 

within a day an aircraft would be 

impacting an area and divided by the 

number of minutes within a 24-hour 

period (1,440 minutes). This determined 

the proportion of the day in which a 

landing/take-off area is impacted by an 

aircraft for each season (Dp(LT); 

Equation 7). 

To estimate the amount of time an 

aircraft would be impacting the travel 

areas (tTR, we calculated the minimum 

amount of time it would take for an 

aircraft to travel the maximum exposure 

area at any given time, 3.22 km (2.00 

mi). We made this estimate using 

average aircraft speeds at altitudes less 

than 305 m (1,000 ft) to account for 

slower flights at lower altitudes, such as 

summer cleanup activities and 

determined it would take approximately 

1.5 minutes. We then determined how 

many 3.22-km (2-mi) segments are 

present along each traveling path (x). 

We determined the total number of 

minutes an aircraft would be impacting 

any 3.22-km (2-mi) segment along the 

travel area in a day and divided by the 

number of minutes in a 24-hour period. 

This calculation determined the 

proportion of the day in which an 

aircraft would impact an area while 

traveling during each season (Dp(TR); 

Equation 8). 

We then used observations of 

behavioral reactions from aerial surveys 

(see section Estimating Harassment 

Rates of Aircraft Activities) to determine 

the appropriate harassment rate in the 

exposure area (1,610 m (1 mi) from the 

center of the flight line; see above in this 

section). The harassment rate areas were 

then calculated separately for the 

landing and take-off areas along each 

flight path as well as the traveling area 

for all flights with altitudes at or below 

457.2 m (1,500 ft). 

To estimate number of polar bears 

harassed due to aircraft activities, we 

first calculated the number of bears 

encountered (Bes) for the landing/takeoff and traveling sections using both 

coastal (eci or co) and inland (eii or io) 

encounter rates within the coastal (ac) 

and inland (ai) exposure areas 

(Equation 9). 


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f s--

p - ds 

1440 

Sp* (tTR * x) 

Dp(TR) = 1440 

Equation 6 

Equation 7 

Equation 8 

Equation 9 
43024 Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 

Using the calculated number of 

coastal and inland bears encountered for 

each season, we applied the daily 

seasonal proportion for both landings/ 

take-offs and traveling areas to 

determine the daily number of bears 

impacted due to aircraft activities (Bi). 

We then applied the aircraft harassment 

rate (ta) associated with the exposure 

area (see section Estimating Harassment 

Rates of Aircraft Activities), resulting in 

a number of bears harassed during each 

season (Bt; Equation 10). Harassment 

associated with AIR surveys was 

analyzed separately. 

BILLING CODE 4333–15–C 

Analysis Approach for Estimating 

Harassment During Aerial Infrared 

Surveys 

Typically, during every ice season 

Industry conducts polar bear den 

surveys using AIR. Although the target 

for these surveys is polar bear dens, 

bears on the surface can be impacted by 

the overflights. These surveys are not 

conducted along specific flight paths 

and generally overlap previously flown 

areas within the same trip. Therefore, 

the harassment estimates for surface 

bears during AIR surveys were 

estimated using a different 

methodology. 

Rather than estimate potential flight 

paths, we used the maximum amount of 

flight time that is likely to occur for AIR 

surveys during each year. The period of 

AIR surveys lasts November 25th to 

January 15th (52 days), and we 

estimated a maximum of 6 hours of 

flight time per day, resulting in a total 

of 312 flight hours per year. To 

determine the amount of time AIR 

flights are likely to survey coastal and 

inland zones, we found the area where 

industry activities and denning habitat 

overlap and buffered by 1.6 km (1 mi). 

We then split the buffered denning 

habitat by zone and determined the 

proportion of coastal and inland 

denning habitat. Using this proportion, 

we estimated the number of flight hours 

spent within each zone and determined 

the proportion of the ice season in 

which AIR surveys were impacting the 

survey areas (see General Approach to 

Estimating Harassment for Aircraft 

Activities). We then estimated the 

aircraft footprint to determine the area 

that would be impacted at any given 

time as well as the area accounting for 

two take-offs and two landings. Using 

the seasonal bear encounter rates for the 

appropriate zones multiplied by the area 

impacted and the proportion of the 

season AIR flights were flown, we 

determined the number of bears 

encountered. We then applied the 

aircraft harassment rate to the number of 

bears encountered per zone to 

determine number of bears harassed. 

Estimated Harassment From Aircraft 

Activities 

Using the approach described in 

General Approach to Estimating 

Harassment for Aircraft Activities and 

Analysis Approach for Estimating 

Harassment during Aerial Infrared 

Surveys, we estimated the total number 

of bears expected to be harassed by the 

aircraft activities included in the 

analyses during the Beaufort Sea ITR 

period of 2021–2026 (Table 6). 

TABLE 6—ESTIMATED LEVEL B HARASSMENT OF POLAR BEARS ON THE NORTH SLOPE OF ALASKA BY YEAR AS A RESULT

OF AIRCRAFT OPERATIONS DURING THE 2021–2026 ITR PERIOD

[Average estimated polar bear harassments per year = 1.09 bears] 

21–22 22–23 23–24 24–25 25–26 26 Total 

Est. Harassment .......... 0.89 0.95 0.95 1.09 1.09 0.15 5.45 

Methods for Modeling the Effects of Den 

Disturbance 

Case Studies Analysis 

To assess the likelihood and degree of 

exposure and predict probable 

responses of denning polar bears to 

activities proposed in the AOGA 

Request, we characterized, evaluated, 

and prioritized a series of rules and 

definitions towards a predictive model 

based on knowledge of published and 

unpublished information on denning 

ecology, behavior, and cub survival. 

Contributing information came from 

literature searches in several major 

research databases and data compiled 

from polar bear observations submitted 

by the oil and gas Industry. We 

considered all available scientific and 

observational data we could find on 

polar bear denning behavior and effects 

of disturbance. 

From these sources, we identified 57 

case studies representing instances 

where polar bears at a maternal den may 

have been exposed to human activities. 

For each den, we considered the four 

denning periods separately, and for each 

period, determined whether adequate 

information existed to document 

whether (1) the human activity met our 

definition of an exposure and (2) the 

response of the bear(s) could be 

classified according to our rules and 

definitions. From these 57 dens, 80 

denning period-specific events met 

these criteria. For each event, we 

classified the type and frequency (i.e., 

discrete or repeated) of the exposure, 

the response of the bear(s), and the level 

of take associated with that response. 

From this information, we calculated 

the probability that a discrete or 

repeated exposure would result in each 

possible level of take during each 

denning period, which informed the 

probabilities for outcomes in the 

simulation model (Table 7). 


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Equation 10 
Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 43025 

TABLE 7—PROBABILITY THAT A DISCRETE OR REPEATED EXPOSURE ELICITED A RESPONSE BY DENNING POLAR BEARS

THAT WOULD RESULT IN LEVEL B HARASSMENT, LEVEL A HARASSMENT (INCLUDING SERIOUS AND NON-SERIOUS INJURY), OR LETHAL TAKE

[Level B harassment was applicable to both adults and cubs, if present; Level A harassment and lethal take were applicable to cubs only. Probabilities were calculated from the analysis of 57 case studies of polar bear responses to human activity. Cells with NAs indicate these types 

of take were not possible during the given denning period.] 

Exposure type Period None Level B Non-serious 

Level A 

Serious 

Level A Lethal 

Discrete ................ Den Establishment ............................ 0.400 0.600 NA NA NA 

Early Denning .................................... 1.000 0.000 NA NA 0.000 

Late Denning ..................................... 0.091 0.000 NA 0.909 0.000 

Post-emergence ................................ 0.000 0.000 0.750 NA 0.250 

Repeated ............. Den Establishment ............................ 1.000 0.000 NA NA NA 

Early Denning .................................... 0.800 0.000 NA NA 0.200 

Late Denning ..................................... 0.708 0.000 NA 0.292 0.000 

Post-emergence ................................ 0.000 0.267 0.733 NA 0.000 

Case Study Analysis Definitions 

Below, we provide definitions for 

terms used in this analysis, a general 

overview of denning chronology and 

periods (details are provided in the 

Potential Effects to Pacific Walrus, Polar 

Bears and Prey Species: Effects on 

denning bears), and the rules 

established for using the case studies to 

inform the model. 

Exposure and Response Definitions 

Exposure: Any human activity within 

1.6 km (1 mi) of a polar bear den site. 

In the case of aircraft, an overflight 

within 457 m (0.3 mi) above ground 

level. 

Discrete exposure: An exposure that 

occurs only once and of short duration 

(<30 minutes). It can also be a shortduration exposure that happens 

repeatedly but that is separated by 

sufficient time that exposures can be 

treated as independent (e.g., aerial 

pipeline surveys that occur weekly). 

Repeated exposure: An exposure that 

occurs more than once within a time 

period where exposures cannot be 

considered independent or an exposure 

that occurs due to continuous activity 

during a period of time (e.g., traffic 

along a road, or daily visits to a well 

pad). 

Response probability: The probability 

that an exposure resulted in a response 

by denning polar bears. 

We categorized each exposure into 

categories based on polar bear response: 

• No response: No observed or 

presumed behavioral or physiological 

response to an exposure. 

• Likely physiological response: An 

alteration in the normal physiological 

function of a polar bear (e.g., elevated 

heart rate or stress hormone levels) that 

is typically unobservable but is likely to 

occur in response to an exposure. 

• Behavioral response: A change in 

behavior in response to an exposure. 

Behavioral responses can range from 

biologically insignificant (e.g., a resting 

bear raising its head in response to a 

vehicle driving along a road) to 

substantial (e.g., cub abandonment) and 

concomitant levels of take vary 

accordingly. 

Timing Definitions 

Entrance date: The date a female first 

enters a maternal den after excavation is 

complete. 

Emergence date: The date a maternal 

den is first opened and a bear is exposed 

directly to external conditions. 

Although a bear may exit the den 

completely at emergence, we considered 

even partial-body exits (e.g., only a 

bear’s head protruding above the surface 

of the snow) to represent emergence in 

order to maintain consistency with 

dates derived from temperature sensors 

on collared bears (e.g., Rode et al. 

2018b). For dens located near regularly 

occurring human activity, we 

considered the first day a bear was 

observed near a den to be the emergence 

date unless other data were available to 

inform emergence dates (e.g., GPS collar 

data). 

Departure date: The date when bears 

leave the den site to return to the sea 

ice. If a bear leaves the den site after a 

disturbance but later returns, we 

considered the initial movement to be 

the departure date. 

Definition of Various Denning Periods 

Den establishment period: Period of 

time between the start of maternal den 

excavation and the birth of cubs. Unless 

evidence indicates otherwise, all dens 

that are excavated by adult females in 

the fall or winter are presumed to be 

maternal dens. In the absence of other 

information, this period is defined as 

denning activity prior to December 1 

(i.e., estimated earliest date cubs are 

likely present in dens (Derocher et al. 

1992, Van de Velde et al. 2003)). 

Early denning period: Period of time 

from the birth of cubs until they reach 

60 days of age and are capable of 

surviving outside the den. In the 

absence of other information, this 

period is defined as any denning 

activity occurring between December 1 

and February 13 (i.e., 60 days after 15 

December, the estimated average date of 

cub birth; Van de Velde et al. 2003, 

Messier et al. 1994). 

Late denning period: Period of time 

between when cubs reach 60 days of age 

and den emergence. In the absence of 

other information, this period is defined 

as any denning activity occurring 

between 14 February and den 

emergence. 

Post-emergence period: Period of time 

between den emergence and den site 

departure. We considered a ‘‘normal’’ 

duration at the den site between 

emergence and departure to be greater 

than or equal to 8 days and classified 

departures that occurred post emergence 

‘‘early’’ if they occurred less than 8 days 

after emergence. 

Descriptions of Potential Outcomes 

Cub abandonment: Occurs when a 

female leaves all or part of her litter, 

either in the den or on the surface, at 

any stage of the denning process. We 

classified events where a female left her 

cubs but later returned (or was returned 

by humans) as cub abandonment. 

Early emergence: Den emergence that 

occurs as the result of an exposure (see 

‘Rules’ below). 

Early departure: Departure from the 

den site post-emergence that occurs as 

the result of an exposure (see ‘Rules’ 

below). 

Predictive Model Rules for Determining 

Den Outcomes and Assigning Take 

• We considered any exposure in a 

24-hour period that did not result in a 

Level A harassment or lethal take to 

potentially be a Level B harassment take 


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if a behavioral response was observed. 

However, multiple exposures do not 

result in multiple Level B harassment 

takes unless the exposures occurred in 

two different denning periods. 

• If comprehensive dates of specific 

exposures are not available and daily 

exposures were possible (e.g., the den 

was located within 1.6 km [1 mi] of an 

ice road), we assumed exposures 

occurred daily. 

• In the event of an exposure that 

resulted in a disturbance to denning 

bears, take was assigned for each bear 

(i.e., female and each cub) associated 

with that den. Whereas assigned take for 

cubs could range from Level B 

harassment to lethal take, for adult 

females only Level B harassment was 

possible. 

• In the absence of additional 

information, we assumed dens did not 

contain cubs prior to December 1 but 

did contain cubs on or after December 

1. 

• If an exposure occurred and the 

adult female subsequently abandoned 

her cubs, we assigned a lethal take for 

each cub. 

• If an exposure occurred during the 

early denning period and bears emerged 

from the den before cubs reached 60 

days of age, we assigned a lethal take for 

each cub. In the absence of information 

about cub age, a den emergence that 

occurred between December 1 and 

February 13 was considered to be an 

early emergence and resulted in a lethal 

take of each cub. 

• If an exposure occurred during the 

late denning period (i.e., after cubs 

reached 60 days of age) and bears 

emerged from the den before their 

intended (i.e., undisturbed) emergence 

date, we assigned a serious injury Level 

A harassment take for each cub. In the 

absence of information about cub age 

and intended emergence date (which 

was known only for simulated dens), 

den emergences that occurred between 

(and including) February 14 and March 

14 were considered to be early 

emergences and resulted in a serious 

injury Level A harassment take of each 

cub. If a den emergence occurred after 

March 14 but was clearly linked to an 

exposure (e.g., bear observed emerging 

from the den when activity initiated 

near the den), we considered the 

emergence to be early and resulted in a 

serious injury Level A harassment take 

of each cub. 

• For dens where emergence was not 

classified as early, if an exposure 

occurred during the post-emergence 

period and bears departed the den site 

prior to their intended (i.e., 

undisturbed) departure date, we 

assigned a non-serious injury Level A 

harassment take for each cub. In the 

absence of information about the 

intended departure date (which was 

known only for simulated dens), den 

site departures that occurred less than 8 

days after the emergence date were 

considered to be early departures and 

resulted in a non-serious injury Level A 

harassment take of each cub. 

Den Simulation 

We simulated dens across the entire 

north slope of Alaska, ranging from the 

areas identified as denning habitat 

(Blank 2013, Durner et al. 2006, 2013) 

contained within the National 

Petroleum Reserve—Alaska (NPRA) in 

the west to the Canadian border in the 

east. While AOGA’s Request does not 

include activity inside ANWR, we still 

simulated dens in that area to ensure 

that any activities directly adjacent to 

the refuge that might impact denning 

bears inside the refuge would be 

captured. To simulate dens on the 

landscape, we relied on the estimated 

number of dens in three different 

regions of northern Alaska provided by 

Atwood et al. (2020). These included 

the NPRA, the area between the Colville 

and Canning Rivers (CC), and ANWR. 

The mean estimated number of dens in 

each region during a given winter were 

as follows: 12 dens (95% CI: 3–26) in 

the NPRA, 26 dens (95% CI: 11–48) in 

the CC region, and 14 dens (95% CI: 5– 

30) in ANWR (Atwood et al. 2020). For 

each iteration of the model (described 

below), we drew a random sample from 

a gamma distribution for each of the 

regions based on the above parameter 

estimates, which allowed uncertainty in 

the number of dens in each area to be 

propagated through the modeling 

process. Specifically, we used the 

method of moments (Hobbs and Hooten 

2015) to develop the shape and rate 

parameters for the gamma distributions 

as follows: NPRA (122/5.82,12/5.82), CC 

(262/9.52,26/9.52), and ANWR (142/ 

6.32,14/6.32). 

Because not all areas in northern 

Alaska are equally used for denning and 

some areas do not contain the requisite 

topographic attributes required for 

sufficient snow accumulation for den 

excavation, we did not randomly place 

dens on the landscape. Instead, we 

followed a similar approach to that used 

by Wilson and Durner (2020) with some 

additional modifications to account for 

differences in denning ecology in the CC 

region related to a preference to den on 

barrier islands and a general (but not 

complete) avoidance of actively used 

industrial infrastructure. Using the 

USGS polar bear den catalogue (Durner 

et al. 2020), we identified polar bear 

dens that occurred on land in the CC 

region and that were identified either by 

GPS-collared bears or through 

systematic surveys for denning bears 

(Durner et al. 2020). This resulted in a 

sample of 37 dens of which 22 (i.e., 60 

percent) occurred on barrier islands. For 

each iteration of the model, we then 

determined how many of the estimated 

dens in the CC region occurred on 

barrier islands versus the mainland. 

To accomplish this, we first took a 

random sample from a binomial 

distribution to determine the expected 

number of dens from the den catalog 

(Durner et al. 2020) that should occur on 

barrier islands in the CC region during 

that given model iteration; nbarrier = 

Binomial(37,22/37), where 37 represents 

the total number of dens in the den 

catalogue (Durner et al. 2020) in the CC 

region suitable for use (as described 

above) and 22/37 represents the 

observed proportion of dens in the CC 

region that occurred on barrier islands. 

We then divided nbarrier by the total 

number of dens in the CC region 

suitable for use (i.e., 37) to determine 

the proportion of dens in the CC region 

that should occur on barrier islands (i.e., 

pbarrier). We then multiplied pbarrier with 

the simulated number of dens in the CC 

region (rounded to the nearest whole 

number) to determine how many dens 

were simulated to occur on barriers 

islands in the region. 

In the NPRA, the den catalogue 

(Durner et al. 2020) data indicated that 

two dens occurred outside of defined 

denning habitat (Durner et al. 2013), so 

we took a similar approach as with the 

barrier islands to estimate how many 

dens occur in areas of the NPRA with 

the den habitat layer during each 

iteration of the model; nhabitat ∼ 

Binomial(15, 13/15), where 15 

represents the total number of dens in 

NPRA from the den catalogue (Durner et 

al. 2020) suitable for use (as described 

above), and 13/15 represents the 

observed proportion of dens in NPRA 

that occurred in the region with den 

habitat coverage (Durner et al. 2013). We 

then divided nhabitat by the total number 

of dens in NPRA from the den catalogue 

(i.e., 15) to determine proportion of dens 

in the NPRA region that occurred in the 

region of the den habitat layer (phabitat). 

We then multiplied phabitat with the 

simulated number of dens in NPRA 

(rounded to the nearest whole number) 

to determine the number of dens in 

NPRA that occurred in the region with 

the den habitat layer. Because no 

infrastructure exists and no activities 

are proposed to occur in the area of 

NPRA without the den habitat layer, we 

only considered the potential impacts of 

activity to those dens simulated to occur 


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Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 43027 

in the region with denning habitat 

identified (Durner et al. 2013). 

To account for the potential influence 

of industrial activities and infrastructure 

on the distribution of polar bear 

selection of den sites, we again relied on 

the subset of dens from the den 

catalogue (Durner et al. 2020) discussed 

above. We further restricted the dens to 

only those occurring on the mainland 

because no permanent infrastructure 

occurred on barrier islands with 

identified denning habitat (Durner et al. 

2006). We then determined the 

minimum distance to permanent 

infrastructure that was present when the 

den was identified. This led to an 

estimate of a mean minimum distance of 

dens to infrastructure being 21.59 km 

(SD = 16.82). From these values, we 

then parameterized a gamma 

distribution: Gamma(21.592/16.822, 

21.59/16.822). We then obtained 

100,000 samples from this distribution 

and created a discretized distribution of 

distances between dens and 

infrastructure. We created 2.5-km 

intervals between 0 and 45 km, and one 

bin for areas >45 km from infrastructure 

and determined the number of samples 

that occurred within each distance bin. 

We then divided the number of samples 

in each bin by the total number of 

samples to determine the probability of 

a simulated den occurring in a given 

distance bin. The choice of 2.5 km for 

distance bins was based on a need to 

ensure that kernel density grid cells 

occurred in each distance bin. 

To inform where dens are most likely 

to occur on the landscape, we 

developed a kernel density map by 

using known den locations in northern 

Alaska identified either by GPS-collared 

bears or through systematic surveys for 

denning bears (Durner et al. 2020). To 

approximate the distribution of dens, 

we used an adaptive kernel density 

estimator (Terrell and Scott 1992) 

applied to n observed den location, 

which took the form 

where the adaptive bandwidth h(s) = (b0

+ b1I(si ∈ M)I(s ∈ M))b2 for the location 

of the ith den and each location s in the 

study area. The indicator functions 

allowed the bandwidth to vary abruptly 

between the mainland M and barrier 

islands. The kernel k was the Gaussian 

kernel, and the parameters q, b0, b1, b2

were chosen based on visual assessment 

so that the density estimate 

approximated the observed density of 

dens and our understanding of likely 

den locations in areas with low 

sampling effort. 

The kernel density map we used for 

this analysis differs slightly from the 

version used in previous analyses, 

specifically our differentiation of barrier 

islands from mainland habitat. We used 

this modified version because previous 

analyses did not require us to consider 

denning habitat in the CC region, which 

has a significant amount of denning that 

occurs on barrier islands compared to 

the other two regions. If barrier islands 

were not differentiated for the kernel 

density estimate, density from the 

barrier island dens would spill over 

onto the mainland, which was deemed 

to be biologically unrealistic given the 

clear differences in den density between 

the barrier islands and the mainland in 

the region. For each grid cell in the 

kernel density map within the CC 

region, we then determined the 

minimum distance to roads and pads 

that had occupancy ≥0.50 identified by 

AOGA during October through 

December (i.e., the core period when 

bears were establishing their dens). We 

restricted the distance to infrastructure 

component to only the CC region 

because it is the region that contains the 

vast majority of oil and gas 

infrastructure and has had some form of 

permanent industrial infrastructure 

present for more than 50 years. Thus, 

denning polar bears have had a 

substantial amount of time to modify 

their selection of where to den related 

to the presence of human activity. 

To simulate dens on the landscape, 

we first sampled in which kernel grid 

cell a den would occur based on the 

underlying relative probability (Figure 

6) within a given region using a 

multinomial distribution. Once a cell 

was selected, the simulated den was 

randomly placed on the denning habitat 

(Blank 2013, Durner et al. 2006, 2013) 

located within that grid cell. For dens 

being simulated on mainland in the CC 

region, an additional step was required. 

We first assigned a simulated den a 

distance bin using a multinomial 

distribution of probabilities of being 

located in a given distance bin based on 

the discretized distribution of distances 

described above. Based on the distance 

to infrastructure bin assigned to a 

simulated den, we subset the kernel 

density grid cells that occurred in the 

same distance bin and then selected a 

grid cell from that subset based on their 

underlying probabilities using a 

multinomial distribution. Then, similar 

to other locations, a den was randomly 

placed on denning habitat within that 

grid cell. 


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8 Il (S-Si) f(s) oc -;;- Li k h(s) ' 
43028 Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 

For each simulated den, we assigned 

dates of key denning events; den 

entrance, birth of cubs, when cubs 

reached 60 days of age, den emergence, 

and departure from the den site after 

emergence. These represent the 

chronology of each den under 

undisturbed conditions. We selected the 

entrance date for each den from a 

normal distribution parameterized by 

entrance dates of radio-collared bears in 

the Southern Beaufort subpopulation 

that denned on land included in Rode 

et al. (2018) and published in USGS 

(2018; n = 52, mean = 11 November, SD 

= 18 days). These data were restricted to 

those dens with both an entrance and 

emergence data identified and where a 

bear was in the den for greater than or 

equal to 60 days to reduce the chances 

of including non-maternal bears using 

shelter dens. Sixty days represents the 

minimum age of cubs before they have 

a chance of survival outside of the den. 

Thus, periods less than 60 days in the 

den have a higher chance of being 

shelter dens. 

We truncated this distribution to 

ensure that all simulated dates occurred 

within the range of observed values (i.e., 

12 September to 22 December) 

identified in USGS (2018) to ensure that 

entrance dates were not simulated 

during biologically unreasonable 

periods given that the normal 

distribution allows some probability 

(albeit small) of dates being 

substantially outside a biologically 

reasonable range. We selected a date of 

birth for each litter from a normal 

distribution with the mean set to ordinal 

date 348 (i.e., 15 December) and 

standard deviation of 10, which allowed 

the 95 percent CI to approximate the 

range of birth dates (i.e., December 1 to 

January 15) identified in the peerreviewed literature (Messier et al. 1994, 

Van de Velde et al. 2003). We ensured 

that simulated birth dates occurred after 

simulated den entrance dates. We 

selected the emergence date as a random 

draw from an asymmetric Laplace 

distribution with parameters m = 81.0, s 

= 4.79, and p = 0.79 estimated from the 

empirical emergence dates in Rode et al. 

(2018) and published in USGS (2018, n 

= 52) of radio-collared bears in the 

Southern Beaufort Sea stock that 

denned on land using the mleALD 

function from package ‘ald’ (Galarzar 

and Lachos 2018) in program R (R Core 

Development Team 2021). We 

constrained simulated emergence dates 

to occur within the range of observed 

emergence dates (January 9 to April 9, 

again to constrain dates to be 

biologically realistic) and to not occur 

until after cubs were 60 days old. 

Finally, we assigned the number of days 

each family group spent at the den site 

post-emergence based on values 

reported in four behavioral studies, 

Smith et al. (2007, 2010, 2013) and 

Robinson (2014), which monitored dens 

near immediately after emergence (n = 

25 dens). Specifically, we used the 

mean (8.0) and SD (5.5) of the dens 

monitored in these studies to 

parameterize a gamma distribution 

using the method of moments (Hobbs 

and Hooten 2015) with a shape 

parameter equal to 8.02/5.52 and a rate 

parameter equal to 8.0/5.52; we selected 

a post-emergence, pre-departure time for 

each den from this distribution. We 

restricted time at the den post 

emergence to occur within the range of 

times observed in Smith et al. (2007, 

2010, 2013) and Robinson (2014) (i.e., 

2–23 days, again to ensure biologically 

realistic times spent at the den site were 

simulated). Additionally, we assigned 

each den a litter size by drawing the 

number of cubs from a multinomial 

distribution with probabilities derived 

from litter sizes (n = 25 litters) reported 

in Smith et al. (2007, 2010, 2013) and 

Robinson (2014). 

Because there is some probability that 

a female naturally emerges with 0 cubs, 

we also wanted to ensure this scenario 

was captured. It is difficult to 

parameterize the probability of litter 

size equal to 0 because it is rarely 

observed. We, therefore, assumed that 

dens in the USGS (2018) dataset that 

had denning durations less than the 

shortest den duration where a female 


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Relative Den Density 

:h 

Project Area 

- Polenlial OM Habilat 

Figure 6-Depiction of the proposed project area with the underlying relative density of 

polar bear dens and potential polar bear den habitat as identified by Durner et al. (2006, 

2013) and Blank (2013). 
Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 43029 

was later observed with cubs (i.e., 79 

days) had a litter size of 0. There were 

only 3 bears in the USGS (2018) data 

that met this criteria, leading to an 

assumed probability of a litter size of 0 

at emergence being 0.07. We, therefore, 

assigned the probability of 0, 1, 2, or 3 

cubs as 0.07, 0.15, 0.71, and 0.07, 

respectively. 

Infrastructure and Human Activities 

The model developed by Wilson and 

Durner (2020) provides a template for 

estimating the level of potential impact 

to denning polar bears of proposed 

activities while also considering the 

natural denning ecology of polar bears 

in the region. The approach developed 

by Wilson and Durner (2020) also 

allows for the incorporation of 

uncertainty in both the metric 

associated with denning bears and in 

the timing and spatial patterns of 

proposed activities when precise 

information on those activities is 

unavailable. Below we describe the 

different sources of potential 

disturbance we considered within the 

model. We considered infrastructure 

and human activities only within the 

area of proposed activity in the ITR 

Request. However, given that activity on 

the border of this region could still 

affect dens falling outside of the area 

defined in the ITR Request, we also 

considered the impacts to denning bears 

within a 1-mile buffer outside of the 

proposed activity area. 

Roads and Pads 

We obtained shapefiles of existing 

and proposed road and pad 

infrastructure associated with industrial 

activities from AOGA. Each attribute in 

the shapefiles included a monthly 

occupancy rate that ranged from 0 to 1. 

For this analysis, we assumed that any 

road or pad with occupancy greater than 

0 for a given month had the potential for 

human activity during the entire month 

unless otherwise noted. 

Ice Roads and Tundra Travel 

We obtained shapefiles of proposed 

ice road and tundra travel routes from 

AOGA. We also received information on 

the proposed start and end dates for ice 

roads and tundra routes each winter 

from AOGA with activity anticipated to 

occur at least daily along each. 

Seismic Surveys 

Seismic surveys are planned to occur 

in the central region of the project area 

proposed by AOGA (Figure 7). The 

region where seismic surveys would 

occur were split into two different 

portions representing relatively high 

and relatively low probabilities of polar 

bear dens being present (Figure 7). 

During any given winter, no more than 

766 km2 and 1183 km2 will be surveyed 

in the high- and low-density areas, 

respectively. Therefore, for this analysis, 

we estimated take rates by assuming 

that seismic surveys would occur in the 

portions of those areas with the highest 

underlying probabilities of denning 

occurring and covering the largest area 

proposed in each (i.e., 766 km2 and 

1183 km2). All seismic surveys could 

start as early as January 1 and operate 

until April 15. 


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Relative Den Density 

High 

low 

Project Area 

~ High Density Seismic 

~ low Density Seismic 

-, 

Figure 7-Depiction of areas where seismic surveys occurred in simulations with 

underlying map of relative den density. The high-density seismic area covers a region 

with relatively high probability of denning, and the low-density seismic area covers a 

region with relatively low probability of denning. During any given winter, no more than 

766 km2 and 1,183 km2 will be surveyed in the high-density and low-density areas, 

respectively. 
43030 Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 

Pipelines 

We obtained shapefiles of existing 

and proposed pipelines, as well as 

which months and years each pipeline 

would be operational, from AOGA. 

Based on the description in the Request, 

we assumed that all pipelines would 

have aerial surveys conducted weekly 

with aircraft flying at altitudes <457.2 m 

(<1,500 ft) and potentially exposing 

polar bears to disturbance. 

Other Aircraft Activities 

Aside from flights to survey pipelines, 

the majority of aircraft flights are 

expected to occur at altitudes >457.2 m 

(>1,500 ft). After reviewing current and 

proposed flight patterns for flights likely 

to occur at altitudes <457.2 m (<1,500 

ft), we found one flight path that we 

included in the model. The flight path 

is between the Oooguruk drill site and 

the onshore tie-in pad with at least daily 

flights between September 1 and 

January 31. We, therefore, also 

considered these flights as a continuous 

source of potential exposure to denning 

bears. 

Aerial Infrared Surveys 

Based on AOGA’s Request, we 

assumed that all permanent 

infrastructure (i.e., roads, pipelines, and 

pads), tundra travel routes, and ice 

roads would receive two aerial infrared 

(AIR) surveys of polar bear den habitat 

within 1 mile of those features each 

winter. The first survey could occur 

between December 1 and 25 and the 

second between December 15 through 

January 10 with at least 24 hours 

between the completion of the first 

survey and the beginning of the second. 

During winters when seismic surveys 

occur, additional AIR surveys would be 

required. A total of three AIR surveys of 

any den habitat within 1 mile of the 

seismic survey area would be required 

prior to any seismic-related activities 

occurring (e.g., advance crews checking 

ice conditions). The first AIR survey 

would need to occur between November 

25 and December 15, the second 

between December 5 and 31, and the 

third between December 15 and January 

15 with the same minimum of 24 hours 

between subsequent surveys. Similarly, 

during winters when seismic surveys 

occur, an additional AIR survey would 

be required of denning habitat within 1 

mile of the pipeline between Badami 

and the road to Endicott Island. The 

additional survey of the pipeline (to 

create a total of three) would need to 

occur between December 5 and January 

10. 

During each iteration of the model, 

each AIR survey was randomly assigned 

a probability of detecting dens. Whereas 

previous analyses have used the results 

of Wilson and Durner (2020) to inform 

this detection probability, two 

additional studies (Smith et al. 2020, 

Woodruff et al. in prep.) have been 

conducted since Wilson and Durner 

(2020) was published that require an 

updated approach. The study by 

Woodruff et al. (in prep.) considered the 

probability of detecting heat signatures 

from artificial polar bear dens. They did 

not find a relationship between den 

snow depth and detection and estimated 

a mean detection rate of 0.24. A recent 

study by Smith et al. (2020) estimated 

that the detection rate for actual polar 

bear dens in northern Alaska was 0.45 

and also did not report any relationship 

between detection and den snow depth. 

Because the study by Wilson and 

Durner (2020) reported detection 

probability only for dens with less than 

100 cm snow depth, we needed to 

correct it to also include those dens 

with greater than 100 cm snow depth. 

Based on the distribution of snow 

depths used by Wilson and Durner 

(2020) derived from data in Durner et al. 

(2003), we determined that 24 percent of 

dens have snow depths greater than 100 

cm. After taking these into account, the 

overall detection probability from 

Wilson and Durner (2020) including 

dens with snow depths greater than 100 

cm was estimated to be 0.54. This led 

to a mean detection of 0.41 and standard 

deviation of 0.15 across the three 

studies. We used these values, and the 

method of moments (Hobbs and Hooten 

2015), to inform a Beta distribution (i.e., 

from which we drew a detection 

probability for each of the simulated 

AIR surveys during each iteration of the 

model. 

Model Implementation 

For each iteration of the model, we 

first determined which dens were 

exposed to each of the simulated 

activities and infrastructure. We 

assumed that any den within 1.6 km (1 

mi) of infrastructure or human activities 

was exposed and had the potential to be 

disturbed as numerous studies have 

suggested a 1.6-km buffer is sufficient to 

reduce disturbance to denning polar 

bears (MacGillivray et al. 2003, Larson 

et al. 2020, Owen et al. 2021). If, 

however, a den was detected by an AIR 

survey prior to activity occurring within 

1.6 km of it, we assumed a 1.6-km buffer 

would be established to restrict activity 

adjacent to the den and there would be 

no potential for future disturbance. If a 

den was detected by an AIR survey after 

activity occurred within 1.6 km of it, as 

long as the activity did not result in a 

Level A harassment or lethal take, we 

assumed a 1.6-km buffer would be 

applied to prevent disturbance during 

future denning periods. For dens 

exposed to human activity (i.e., not 

detected by an AIR survey), we then 

identified the stage in the denning cycle 

when the exposure occurred based on 

the date range of the activities the den 

was exposed to. We then determined 

whether the exposure elicited a 

response by the denning bear based on 

probabilities derived from the reviewed 

case studies (Table 7). Level B 

harassment was applicable to both 

adults and cubs, if present, whereas 

Level A harassment (i.e., serious injury 

and non-serious injury) and lethal take 

were applicable only to cubs because 

the proposed activities had a 

discountable risk of running over dens 

and thus killing a female or impacting 

her future reproductive potential. The 

majority of proposed activities occur on 

established, permanent infrastructure 

that would not be suitable for denning 

and therefore, pose no risk of being run 

over (i.e., an existing road). For those 

activities off permanent infrastructure 

(i.e., ice roads and tundra travel routes), 

crews will constantly be on the lookout 

for signs of denning, use vehicle-based 

forward looking infrared cameras to 

scan for dens, and will largely avoid 

crossing topographic features suitable 

for denning given operational 

constraints. Thus, the risk of running 

over a den was deemed to have a 

probability so low that it was 

discountable. 

Based on AOGA’s description of their 

proposed activities, we only considered 

AIR surveys and pipeline inspection 

surveys as discrete exposures given that 

surveys occur quickly (i.e., the time for 

an airplane to fly over) and infrequently. 

For all other activities, we applied 

probabilities associated with repeated 

exposure (Table 7). For the pipeline 

surveys, we made one modification to 

the probabilities applied compared to 


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Beta (o.412 -o.413 -o.41xo.15392 o.41-zxo.412 +o.413 -0.15392 +o.41xo.15392 )) 

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Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 43031 

those listed in Table 7. The case studies 

used to inform the post-emergence 

period include one where an individual 

fell into a den and caused the female to 

abandon her cubs. Given that pipeline 

surveys would either occur with a plane 

or a vehicle driving along an established 

path adjacent to a pipeline, there would 

be no chance of falling into a den. 

Therefore, we excluded this case study 

from the calculation of disturbance 

probabilities applied to our analysis, 

which led to a 0 percent probability of 

lethal take and a 100 percent probability 

of non-serious injury Level A 

harassment. 

For dens exposed to human activity, 

we used a multinomial distribution with 

the probabilities of different levels of 

take for that period (Table 7). If a Level 

A harassment or lethal take was 

simulated to occur, a den was not 

allowed to be disturbed again during the 

subsequent denning periods because the 

outcome of that denning event was 

already determined. As noted above, 

Level A harassments and lethal takes 

only applied to cubs because proposed 

activities would not result in those 

levels of take for adult females. Adult 

females, however, could still receive 

Level B harassment during the den 

establishment period or any time cubs 

received Level B harassment, Level A 

harassment (i.e., serious injury and nonserious injury), or lethal take. 

We developed the code to run this 

model in program R (R Core 

Development Team 2021) and ran 

10,000 iterations of the model (i.e., 

Monte Carlo simulation) to derive the 

estimated number of animals disturbed 

and associated levels of take. We ran the 

model for each of the five winters 

covered by the ITR (i.e., 2021/2022, 

2022/2023, 2023/2024, 2024/2025, 

2025/2026). For each winter’s analysis, 

we analyzed the most impactful 

scenario that was possible. For example, 

seismic surveys may not occur every 

winter, but it is unclear which winters 

would have seismic surveys and which 

would not. Therefore, each of the 

scenarios were run with the inclusion of 

seismic surveys (and their additional 

AIR surveys) knowing that take rates 

will be less for a given winter if seismic 

surveys did not occur. Similarly, in 

some winters, winter travel between 

Deadhorse and Point Thomson will 

occur along an ice road running roughly 

parallel to the pipeline connecting the 

two locations. However, in other 

winters, the two locations will be 

connected via a tundra travel route 

farther south. Through preliminary 

analyses, we found that the tundra 

travel route led to higher annual take 

estimates. Therefore, for each of the 

scenarios, we only considered the 

tundra travel route knowing that take 

rates will be less when the more 

northern ice road is used. 

Model Results 

On average, we estimated 52 (median 

= 51; 95% CI: 30–80) land-based dens in 

the area of proposed activity in AOGA’s 

Request within a 1.6-km (1-mi) buffer. 

Annual estimates for different levels of 

take are presented in Table 8. We also 

estimated that Level B harassment take 

from AIR surveys was never greater than 

a mean of 1.53 (median = 1; 95% CI: 0– 

5) during any winter. The distributions 

of both non-serious Level A and serious 

Level A/Lethal possible takes were nonnormal and heavily skewed, as 

indicated by markedly different mean 

and median values. The heavily skewed 

nature of these distributions has led to 

a mean value that is not representative 

of the most common model result (i.e., 

the median value), which for both nonserious Level A and serious Level A/ 

Lethal takes is 0.0 takes. Due to the low 

(<0.29 for non-serious Level A and 

≤0.462 for serious Level A/Lethal takes) 

probability of greater than or equal to 1 

non-serious or serious injury Level A 

harassment/Lethal take each year of the 

proposed ITR period, combined with 

the median of 0.0 for each, we do not 

estimate the proposed activities will 

result in non-serious or serious injury 

Level A harassment or lethal take of 

polar bears. 

TABLE 8—RESULTS OF THE DEN DISTURBANCE MODEL FOR EACH WINTER OF PROPOSED ACTIVITY

Winter (20XX) 

Level B harassment Non-serious Level A Serious Level A/lethal 

Prob Mean Med 95% CI Prob Mean Med 95% CI Prob Mean Med 95% CI 

21–22 ................ 0.89 3.1 3.0 0–9 0.28 0.7 0.0 0–4 0.45 1.2 0.0 0–5 

22–23 ................ 0.90 3.2 3.0 0–9 0.29 0.7 0.0 0–4 0.46 1.2 0.0 0–6 

23–24 ................ 0.90 3.1 3.0 0–9 0.28 0.6 0.0 0–4 0.46 1.2 0.0 0–5 

24–25 ................ 0.90 3.1 3.0 0–9 0.28 0.6 0.0 0–4 0.46 1.2 0.0 0–6 

25–26 ................ 0.90 3.2 3.0 0–9 0.28 0.7 0.0 0–4 0.46 1.2 0.0 0–5 

Estimates are provided for the probability (Prob), mean, median (Med), and 95% Confidence Intervals (CI) for Level B, Non-Serious Level A, and Serious Level A/ 

Lethal take. The probabilities represent the probability of ≥1 take of a bear occurring during a given winter. 

Maritime Activities 

Vessel Traffic 

Maritime activities were divided into 

two categories of potential impact: 

vessel traffic and in-water construction. 

Vessel traffic was further divided into 

two categories: Repeated, frequent trips 

by small boats and hovercraft for crew 

movement and less frequent trips to 

move fuel and equipment by tugs and 

barges. We estimated the potential Level 

B harassment take from the repeated, 

frequent trips by crew boats and 

hovercraft in Polar Bear: Surface 

Interactions as marine roads using an 

occupancy rate of 0.2. This occupancy 

rate accounts for 20 percent of the 

impact area (i.e., the length of the route 

buffered by 1.6 km (1 mi)) being 

impacted at any given point throughout 

the year, which is consistent with the 

daily trips described by AOGA. 

For less frequent trips for fuel and 

equipment resupply by tugs and barges, 

AOGA has supplied the highest 

expected number of trips that may be 

taken each year. Because we have been 

supplied with a finite number of 

potential trips, we used the impact area 

of the barge/tug combination as it moves 

in its route from one location to the 

next. We estimated a 16.5-km2 (6.37- 

mi2) take area for the barge, tug, and 

associated tow line, which accounts for 

a barge, tow, and tug length of 200 m 

(656 ft), width of 100 m (328 ft), and a 

1.6-km (1-mi) buffer surrounding the 

vessels. We calculated the total hours of 

impact using an average vessel speed of 

two knots (3.7 km/hr), and then 

calculated the proportion of the openwater season that would be impacted 

(Table 9). 


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43032 Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 

TABLE 9—CALCULATION OF THE TOTAL NUMBER OF BARGE AND TUG VESSEL TRIP HOURS AND THE PROPORTION OF THE

SEASON POLAR BEARS MAY BE IMPACTED IN A 16.5-KM2 IMPACT AREA BY BARGE/TUG PRESENCE

Origin Destination Frequency Est. length 

(km) Time/trip (hr) Total time (hr) 

West Dock ......................................... Milne Point ....................................... 1 38 10 10 

Milne Point ........................................ West Dock ........................................ 1 38 10 10 

West Dock ......................................... Endicott ............................................ 30 22 6 178 

Endicott ............................................. Badami ............................................. 10 42 11 114 

Badami .............................................. Pt. Thomson ..................................... 10 32 9 86 

Pt. Thomson ...................................... West Dock ........................................ 10 96 26 259 

Total Hours ................................ ........................................................... ........................ ........................ ........................ 658 

Proportion of Season Impacted by Barge/Tug Use 0.24 

The number of estimated takes was 

then calculated using Equation 4, in 

which the impact area is multiplied by 

encounter rate, proportion of season, 

and harassment rate for the open-water 

season. The final number of estimated 

Level B harassment events from barge/ 

tug trips was 1.12 bears per year. 

In-Water Construction 

Polar bears are neither known to 

vocalize underwater nor to rely 

substantially upon underwater sounds 

to locate prey. However, for any 

predator, loss of hearing is likely to be 

an impediment to successful foraging. 

The Service has applied a 190 dB re 1 

mPa threshold for TTS and a 180 dB 

re1mPa threshold for Level B harassment 

arising from exposure of polar bears to 

underwater sounds for previous 

authorizations in the Beaufort and 

Chukchi Seas; seas. However, given the 

projection of polar bear TTS at 188 dB 

by Southall et al. (2019) referenced in 

Figure 1, we used a threshold of Level 

B harassment at 180 dB re 1 mPa in our 

analysis for these regulations. 

The proposal for the 2021–2026 ITR 

period includes several activities that 

will create underwater sound, including 

dredging, screeding, pile driving, gravel 

placement, and geohazard surveys. 

Underwater sounds and the spatial 

extent to which they propagate are 

variable and dependent upon the sound 

source (e.g., size and composition of a 

pile for pile driving, equipment type for 

geophysical surveys, etc.), the 

installation method, substrate type, 

presence of sea ice, and water depth. 

Source levels range from less than 160 

dB re 1 mPa to greater than 200 dB re 

1 mPa (Rodkin and Pommerenck, 2014), 

meaning some sounds reach the level of 

TTS, however they do not reach the 

level of PTS (Table 1). Although these 

activities result in underwater areas that 

are above the 180 dB Level B 

harassment threshold for polar bears, 

the areas above the threshold will be 

small and fall within the current impact 

area (1.6 km) used to estimate polar bear 

harassment due to surface interactions. 

Thus, additional harassment 

calculations based on in-water noise are 

not necessary. Similarly, any in-air 

sounds generated by underwater sources 

are not expected to propagate above the 

Level B harassment thresholds listed in 

Table 1 beyond the 1.6-km (1.0-mi) 

impact area established in Polar Bear: 

Surface Interactions. 

Sum of Harassment From All Sources 

A summary of total numbers of 

estimated take by Level B harassments 

during the duration of the project by 

season and take category is provided in 

Table 10. The potential for lethal or 

Level A harassment was explored. The 

highest probability of greater than or 

equal to 1 lethal or serious Level A 

harassment take of polar bears over the 

5-year ITR period was 0.462. 

TABLE 10—TOTAL ESTIMATED LEVEL B HARASSMENT EVENTS OF POLAR BEARS PER YEAR AND SOURCE

Year 

Level B harassment of polar bears on the surface or in water 

Total Surface 

activity 

Seismic 

exploration 

Vessel 

activity 

Aircraft 

overflights Denning bears 

Open water 2021–Ice 2021/2022 ............ 56.54 1.94 1.12 0.82 3.1 65 

Open water 2022–Ice 2022/2023 ............ 83.77 1.94 1.12 0.95 3.2 91 

Open water 2023–Ice 2023/2024 ............ 84.28 1.94 1.12 0.95 3.1 92 

Open water 2024–Ice 2024/2025 ............ 84.23 1.94 1.12 1.09 3.1 92 

Open water 2025–Ice 2025/2026 ............ 84.48 1.94 1.12 1.09 3.2 92 

Open water 2026 ..................................... 12 0.00 1.12 0.15 0 14 

Critical Assumptions 

To conduct this analysis and estimate 

the potential amount of Level B 

harassment, several critical assumptions 

were made. 

Level B harassment is equated herein 

with behavioral responses that indicate 

harassment or disturbance. There is 

likely a portion of animals that respond 

in ways that indicate some level of 

disturbance but do not experience 

significant biological consequences. Our 

estimates do not account for variable 

responses by polar bear age and sex; 

however, sensitivity of denning bears 

was incorporated into the analysis. The 

available information suggests that polar 

bears are generally resilient to low 

levels of disturbance. Females with 

dependent young and juvenile polar 

bears are physiologically the most 

sensitive (Andersen and Aars 2008) and 

most likely to experience harassment 

from disturbance. There is not enough 

information on composition of the SBS 

polar bear stock in the ITR area to 

incorporate individual variability based 

on age and sex or to predict its influence 

on harassment estimates. Our estimates 

are derived from a variety of sample 

populations with various age and sex 

structures, and we assume the exposed 

population will have a similar 


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composition and therefore, the response 

rates are applicable. 

The estimates of behavioral response 

presented here do not account for the 

individual movements of animals away 

from the ITR area or habituation of 

animals to noise or human presence. 

Our assessment assumes animals remain 

stationary, (i.e., density does not 

change). There is not enough 

information about the movement of 

polar bears in response to specific 

disturbances to refine this assumption. 

This situation could result in 

overestimation of harassment; however, 

we cannot account for harassment 

resulting from a polar bear moving into 

less preferred habitat due to 

disturbance. 

Potential Effects of Oil Spills on Pacific 

Walruses and Polar Bears 

Walrus and polar bear ranges overlap 

with many active and planned Industry 

activities—resulting in associated risks 

of oil spills from facilities, ships, and 

pipelines in both offshore and onshore 

habitat. To date, no major offshore oil 

spills have occurred in the Alaska 

Beaufort Sea. Although numerous small 

onshore spills have occurred on the 

North Slope. To date, there have been 

no documented effects to polar bears. 

Oil spills are unintentional releases of 

oil or petroleum products. In 

accordance with the National Pollutant 

Discharge Elimination System Permit 

Program, all North Slope oil companies 

must submit an oil spill contingency 

plan. It is illegal to discharge oil into the 

environment, and a reporting system 

requires operators to report spills. 

Between 1977 and 1999, an average of 

70 oil and 234 waste product spills 

occurred annually on the North Slope 

oilfields. Although most spills have 

been small by Industry standards (less 

than 50 bbl), larger spills (more than 500 

bbl) accounted for much of the annual 

volume. In the North Slope, a total of 

seven large spills occurred between 

1985 and 2009. The largest of these 

spills occurred in the spring of 2006 

when approximately 6,190 bbl leaked 

from flow lines near an oil gathering 

center. More recently, several large 

spills have occurred. In 2012, 1,000 bbl 

of drilling mud and 100 bbl of crude 

were spilled in separate incidents; in 

2013, approximately 166 bbl of crude oil 

was spilled; and in 2014, 177 bbl of 

drilling mud was spilled. In 2016, 160 

bbl of mixed crude oil and produced 

water was spilled. These spills occurred 

primarily in the terrestrial environment 

in heavily industrialized areas not 

utilized by walruses or polar bears and 

therefore, posed little risk to the 

animals. 

The two largest onshore oil spills 

were in the terrestrial environment and 

occurred because of pipeline failures. In 

the spring of 2006, approximately 6,190 

bbl of crude oil spilled from a corroded 

pipeline operated by BP Exploration 

(Alaska). The spill impacted 

approximately 0.8 ha (∼2 ac). In 

November 2009, a spill of 

approximately 1,150 bbl from a 

‘‘common line’’ carrying oil, water, and 

natural gas operated by BP occurred as 

well, impacting approximately 780 m2

(∼8,400 ft2). None of these spills were 

known to impact polar bears, in part 

due to the locations and timing. Both 

sites were within or near Industry 

facilities not frequented by polar bears, 

and polar bears are not typically 

observed in the affected areas during the 

time of the spills and subsequent 

cleanup. 

Nonetheless, walruses and polar bears 

could encounter spilled oil from 

exploratory operations, existing offshore 

facilities, pipelines, or from marine 

vessels. The shipping of crude oil, oil 

products, or other toxic substances, as 

well as the fuel for the shipping vessels, 

increases the risk of a spill. 

As additional offshore Industry 

projects are planned, the potential for 

large spills in the marine environment 

increases. Oil spills in the sea-ice 

environment, at the ice edge, in leads, 

polynyas, and similar areas of 

importance to walruses and polar bears 

present an even greater challenge 

because of both the difficulties 

associated with cleaning oil in sea-ice 

along with the presence of wildlife in 

those areas. 

Oiling of food sources, such as ringed 

seals, may result in indirect effects on 

polar bears, such as a local reduction in 

ringed seal numbers, or a change to the 

local distribution of seals and bears. 

More direct effects on polar bears could 

occur from: (1) Ingestion of oiled prey, 

potentially resulting in reduced survival 

of individual bears; (2) oiling of fur and 

subsequent ingestion of oil from 

grooming; (3) oiling and fouling of fur 

with subsequent loss of insulation, 

leading to hypothermia; and (4) 

disturbance, injury, or death from 

interactions with humans during oil 

spill response activities. Polar bears may 

be particularly vulnerable to 

disturbance when nutritionally stressed 

and during denning. Cleanup operations 

that disturb a den could result in death 

of cubs through abandonment, and 

perhaps, death of the female as well. In 

spring, females with cubs of the year 

that denned near or on land and migrate 

to contaminated offshore areas may 

encounter oil following a spill (Stirling 

in Geraci and St. Aubin 1990). 

In the event of an oil spill, the Service 

follows oil spill response plans, 

coordinates with partners, and reduces 

the impact of a spill on wildlife. Several 

factors will be considered when 

responding to an oil spill—including 

spill location, magnitude, oil viscosity 

and thickness, accessibility to spill site, 

spill trajectory, time of year, weather 

conditions (i.e., wind, temperature, 

precipitation), environmental 

conditions (i.e., presence and thickness 

of ice), number, age, and sex of walruses 

and polar bears that are (or are likely to 

be) affected, degree of contact, 

importance of affected habitat, cleanup 

proposal, and likelihood of human–bear 

interactions. Response efforts will be 

conducted under a three-tier approach 

characterized as: (1) Primary response, 

involving containment, dispersion, 

burning, or cleanup of oil; (2) secondary 

response, involving hazing, herding, 

preventative capture/relocation, or 

additional methods to remove or deter 

wildlife from affected or potentially 

affected areas; and (3) tertiary response, 

involving capture, cleaning, treatment, 

and release of wildlife. If the decision is 

made to conduct response activities, 

primary and secondary response options 

will be vigorously applied. Tertiary 

response capability has been developed 

by the Service and partners, though 

such response efforts would most likely 

be able to handle only a few animals at 

a time. More information is available in 

the Service’s oil spill response plans for 

walruses and polar bears in Alaska, 

which is located at: https://

www.fws.gov/r7/fisheries/contaminants/ 

pdf/Polar%20Bear%20WRP%20

final%20v8_Public%20website.pdf. 

BOEM has acknowledged that there 

are difficulties in effective oil-spill 

response in broken-ice conditions, and 

the National Academy of Sciences has 

determined that ‘‘no current cleanup 

methods remove more than a small 

fraction of oil spilled in marine waters, 

especially in the presence of broken 

ice.’’ BOEM advocates the use of nonmechanical methods of spill response, 

such as in-situ burning during periods 

when broken ice would hamper an 

effective mechanical response (MMS 

2008). An in-situ burn has the potential 

to rapidly remove large quantities of oil 

and can be employed when broken-ice 

conditions may preclude mechanical 

response. However, the resulting smoke 

plume may contain toxic chemicals and 

high levels of particulates that can pose 

health risks to marine mammals, birds, 

and other wildlife as well as to humans. 

As a result, smoke trajectories must be 

considered before making the decision 

to burn spilled oil. Another potential 


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non-mechanical response strategy is the 

use of chemical dispersants to speed 

dissipation of oil from the water surface 

and disperse it within the water column 

in small droplets. However, dispersant 

use presents environmental trade-offs. 

While walruses and polar bears would 

likely benefit from reduced surface or 

shoreline oiling, dispersant use could 

have negative impacts on the aquatic 

food chain. Oil spill cleanup in the 

broken-ice and open-water conditions 

that characterize Arctic waters is 

problematic. 

Evaluation of Effects of Oil Spills on 

Pacific Walruses and Polar Bears 

The MMPA does not authorize the 

incidental take of marine mammals as 

the result of illegal actions, such as oil 

spills. Nor do the specified activities in 

AOGA’s request include oil spills. Any 

event that results in an injurious or 

lethal outcome to a marine mammal is 

not authorized under this ITR. However, 

for the purpose of developing a more 

complete context for evaluating 

potential effects on walruses and polar 

bears, the Service evaluated the 

potential impacts of oil spills within the 

Beaufort Sea ITR region. 

Pacific Walrus 

As stated earlier, the Beaufort Sea is 

not within the primary range for 

walruses. Therefore, the probability of 

walruses encountering oil or waste 

products as a result of a spill from 

Industry activities is low. Onshore oil 

spills would not impact walruses unless 

they occurred on or near beaches or oil 

moved into the offshore environment. 

However, in the event of a spill that 

occurs during the open-water season, oil 

in the water column could drift offshore 

and possibly encounter a small number 

of walruses. Oil spills from offshore 

platforms could also contact walruses 

under certain conditions. For example, 

spilled oil during the ice-covered season 

that isn’t cleaned up could become part 

of the ice substrate and could eventually 

be released back into the environment 

during the following open-water season. 

Additionally, during spring melt, oil 

would be collected by spill response 

activities, but it could eventually 

contact a limited number of walruses. 

Little is known about the effects of oil, 

specifically on walruses, as no studies 

have been conducted to date. 

Hypothetically, walruses may react to 

oil much like other pinnipeds. Walruses 

are not likely to ingest oil while 

grooming since walruses have very little 

hair and exhibit no grooming behavior. 

Adult walruses may not be severely 

affected by the oil spill through direct 

contact, but they will be extremely 

sensitive to any habitat disturbance by 

human noise and response activities. In 

addition, due to the gregarious nature of 

walruses, an oil spill would most likely 

affect multiple individuals in the area. 

Walruses may also expose themselves 

more often to the oil that has 

accumulated at the edge of a 

contaminated shore or ice lead if they 

repeatedly enter and exit the water. 

Walrus calves are most likely to suffer 

the ill-effects of oil contamination. 

Female walruses with calves are very 

attentive, and the calf will always stay 

close to its mother—including when the 

female is foraging for food. Walrus 

calves can swim almost immediately 

after birth and will often join their 

mother in the water. It is possible that 

an oiled calf will be unrecognizable to 

its mother either by sight or by smell 

and be abandoned. However, the greater 

threat may come from an oiled calf that 

is unable to swim away from the 

contamination and a devoted mother 

that would not leave without the calf, 

resulting in the potential mortality of 

both animals. Further, a nursing calf 

might ingest oil if the mother was oiled, 

also increasing the risk of injury or 

mortality. 

Walruses have thick skin and blubber 

layers for insulation. Heat loss is 

regulated by control of peripheral blood 

flow through the animal’s skin and 

blubber. The peripheral blood flow is 

decreased in cold water and increased at 

warmer temperatures. Direct exposure 

of walruses to oil is not believed to have 

any effect on the insulating capacity of 

their skin and blubber, although it is 

unknown if oil could affect their 

peripheral blood flow. 

Damage to the skin of pinnipeds can 

occur from contact with oil because 

some of the oil penetrates the skin, 

causing inflammation and death of some 

tissue. The dead tissue is discarded, 

leaving behind an ulcer. While these 

skin lesions have only rarely been found 

on oiled seals, the effects on walruses 

may be greater because of a lack of hair 

to protect the skin. Direct exposure to 

oil can also result in conjunctivitis. Like 

other pinnipeds, walruses are 

susceptible to oil contamination in their 

eyes. Continuous exposure to oil will 

quickly cause permanent eye damage. 

Inhalation of hydrocarbon fumes 

presents another threat to marine 

mammals. In studies conducted on 

pinnipeds, pulmonary hemorrhage, 

inflammation, congestion, and nerve 

damage resulted after exposure to 

concentrated hydrocarbon fumes for a 

period of 24 hours. If the walruses were 

also under stress from molting, 

pregnancy, etc., the increased heart rate 

associated with the stress would 

circulate the hydrocarbons more 

quickly, lowering the tolerance 

threshold for ingestion or inhalation. 

Walruses are benthic feeders, and 

much of the benthic prey contaminated 

by an oil spill would be killed 

immediately. Others that survived 

would become contaminated from oil in 

bottom sediments, possibly resulting in 

slower growth and a decrease in 

reproduction. Bivalve mollusks, a 

favorite prey species of the walrus, are 

not effective at processing hydrocarbon 

compounds, resulting in highly 

concentrated accumulations and longterm retention of the contamination 

within the organism. Specifically, 

bivalve mollusks bioconcentrate 

polycyclic aromatic hydrocarbons 

(PAHs). These compounds are a 

particularly toxic fraction of oil that 

may cause a variety of chronic toxic 

effects in exposed organisms, including 

enzyme induction, immune impairment, 

or cancer, among others. In addition, 

because walruses feed primarily on 

mollusks, they may be more vulnerable 

to a loss of this prey species than other 

pinnipeds that feed on a larger variety 

of prey. Furthermore, complete recovery 

of a bivalve mollusk population may 

take 10 years or more, forcing walruses 

to find other food resources or move to 

nontraditional areas. 

The relatively few walruses in the 

Beaufort Sea and the low potential for 

a large oil spill (1,000 bbl or more), 

which is discussed in the following Risk 

Assessment Analysis, limit potential 

impacts to walruses to only certain 

events (i.e., a large oil spill), which is 

further limited to only a handful of 

individuals. Fueling crews have 

personnel that are trained to handle 

operational spills and contain them. If a 

small offshore spill occurs, spill 

response vessels are stationed in close 

proximity and respond immediately. 

Polar Bear 

To date, large oil spills from Industry 

activities in the Beaufort Sea and coastal 

regions that would impact polar bears 

have not occurred, although the interest 

in and the development of offshore 

hydrocarbon reservoirs has increased 

the potential for large offshore oil spills. 

With limited background information 

available regarding oil spills in the 

Arctic environment, the outcome of 

such a spill is uncertain. For example, 

in the event of a large spill equal to a 

rupture in the Northstar pipeline and a 

complete drain of the subsea portion of 

the pipeline (approximately 5,900 bbl), 

oil would be influenced by seasonal 

weather and sea conditions including 

temperature, winds, wave action, and 

currents. Weather and sea conditions 


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also affect the type of equipment needed 

for spill response and the effectiveness 

of spill cleanup. Based on the 

experiences of cleanup efforts following 

the Exxon Valdez oil spill, where 

logistical support was readily available, 

spill response may be largely 

unsuccessful in open-water conditions. 

Indeed, spill response drills have been 

unsuccessful in the cleanup of oil in 

broken-ice conditions. 

Small spills of oil or waste products 

throughout the year have the potential 

to impact some bears. The effects of 

fouling fur or ingesting oil or wastes, 

depending on the amount of oil or 

wastes involved, could be short term or 

result in death. For example, in April 

1988, a dead polar bear was found on 

Leavitt Island, northeast of Oliktok 

Point. The cause of death was 

determined to be a mixture that 

included ethylene glycol and 

Rhodamine B dye (Amstrup et al. 1989). 

Again, in 2012, two dead polar bears 

that had been exposed to Rhodamine B 

were found on Narwhal Island, 

northwest of Endicott. While those 

bears’ deaths were clearly humancaused, investigations were unable to 

identify a source for the chemicals. 

Rhodamine B is commonly used on the 

North Slope of Alaska by many people 

for many uses, including Industry. 

Without identified sources of 

contamination, those bear deaths cannot 

be attributed to Industry activity. 

During the ice-covered season, 

mobile, non-denning bears would have 

a higher probability of encountering oil 

or other production wastes than nonmobile, denning females. Current 

management practices by Industry, such 

as requiring the proper use, storage, and 

disposal of hazardous materials, 

minimize the potential occurrence of 

such incidents. In the event of an oil 

spill, it is also likely that polar bears 

would be intentionally hazed to keep 

them away from the area, further 

reducing the likelihood of impacting the 

population. 

In 1980, Oritsland et al. (1981) 

performed experiments in Canada that 

studied the effects of oil exposure on 

polar bears. Effects on experimentally 

oiled bears (where bears were forced to 

remain in oil for prolonged periods of 

time) included acute inflammation of 

the nasal passages, marked epidermal 

responses, anemia, anorexia, and 

biochemical changes indicative of 

stress, renal impairment, and death. 

Many effects did not become evident 

until several weeks after the experiment. 

Oiling of the pelt causes significant 

thermoregulatory problems by reducing 

insulation value. Irritation or damage to 

the skin by oil may further contribute to 

impaired thermoregulation. 

Experiments on live polar bears and 

pelts showed that the thermal value of 

the fur decreased significantly after 

oiling, and oiled bears showed 

increased metabolic rates and elevated 

skin temperature. Oiled bears are also 

likely to ingest oil as they groom to 

restore the insulation value of the oiled 

fur. 

Oil ingestion by polar bears through 

consumption of contaminated prey, and 

by grooming or nursing, could have 

pathological effects depending on the 

amount of oil ingested and the 

individual’s physiological state. Death 

could occur if a large amount of oil was 

ingested or if volatile components of oil 

were aspirated into the lungs. In the 

Canadian experiment (Ortisland et al. 

1981), two of three bears died. A 

suspected contributing factor to their 

deaths was ingestion of oil. 

Experimentally oiled bears ingested 

large amounts of oil through grooming. 

Much of the oil was eliminated by 

vomiting and defecating; some was 

absorbed and later found in body fluids 

and tissues. 

Ingestion of sublethal amounts of oil 

can have various physiological effects 

on polar bears, depending on whether 

the animal is able to excrete or detoxify 

the hydrocarbons. Petroleum 

hydrocarbons irritate or destroy 

epithelial cells lining the stomach and 

intestine, thereby affecting motility, 

digestion, and absorption. 

Polar bears swimming in or walking 

adjacent to an oil spill could inhale 

toxic, volatile organic compounds from 

petroleum vapors. Vapor inhalation by 

polar bears could result in damage to 

the respiratory and central nervous 

systems depending on the amount of 

exposure. 

Oil may also affect food sources of 

polar bears. Seals that die as a result of 

an oil spill could be scavenged by polar 

bears. This food source would increase 

exposure of the bears to hydrocarbons 

and could result in lethal impacts or 

reduced survival to individual bears. A 

local reduction in ringed seal numbers 

as a result of direct or indirect effects of 

oil could temporarily affect the local 

distribution of polar bears. A reduction 

in density of seals as a direct result of 

mortality from contact with spilled oil 

could result in polar bears not using a 

particular area for hunting. Further, 

possible impacts from the loss of a food 

source could reduce recruitment and/or 

survival. 

Spilled oil can concentrate and 

accumulate in leads and openings that 

occur during spring break-up and 

autumn freeze-up periods. Such a 

concentration of spilled oil would 

increase the likelihood that polar bears 

and their principal prey would be oiled. 

To access ringed and bearded seals, 

polar bears in the SBS concentrate in 

shallow waters less than 300 m (984 ft) 

deep over the continental shelf and in 

areas with greater than 50 percent ice 

cover (Durner et al. 2004). 

Due to their seasonal use of nearshore 

habitat, the times of greatest impact 

from an oil spill to polar bears are likely 

the open-water and broken-ice periods 

(summer and fall), extending into the 

ice-covered season (Wilson et al. 2018). 

This scenario is important because 

distributions of polar bears are not 

uniform through time. Nearshore and 

offshore polar bear densities are greatest 

in fall, and polar bear use of coastal 

areas during the fall open-water period 

has increased in recent years in the 

Beaufort Sea. An analysis of data 

collected from the period 2001–2005 

during the fall open-water period 

concluded: (1) On average 

approximately 4 percent of the 

estimated polar bears in the Southern 

Beaufort Sea stock were observed 

onshore in the fall; (2) 80 percent of 

bears onshore occurred within 15 km (9 

mi) of subsistence-harvested bowhead 

whale carcasses, where large 

congregations of polar bears have been 

observed feeding; and (3) sea-ice 

conditions affected the number of bears 

on land and the duration of time they 

spent there (Schliebe et al. 2006). 

Hence, bears concentrated in areas 

where beach-cast marine mammal 

carcasses occur during the fall would 

likely be more susceptible to oiling. 

Wilson et al. (2018) analyzed the 

potential effects of a ‘‘worst case 

discharge’’ (WCD) on polar bears in the 

Chukchi Sea. Their WCD scenario was 

based on an Industry oil spill response 

plan for offshore development in the 

region and represented underwater 

blowouts releasing 25,000 bbls of crude 

oil per day for 30 days beginning in 

October. The results of this analysis 

suggested that between 5 and 40 percent 

of a stock of 2,000 polar bears in the 

Chukchi Sea could be exposed to oil if 

a WCD occurred. A similar analysis has 

not been conducted for the Beaufort Sea; 

however, given the extremely low 

probability (i.e., 0.0001) that an 

unmitigated WCD event would occur 

(BOEM 2016, Wilson et al. 2017), the 

likelihood of such effects on polar bears 

in the Beaufort Sea is extremely low. 

The persistence of toxic subsurface oil 

and chronic exposures, even at 

sublethal levels, can have long-term 

effects on wildlife (Peterson et al. 2003). 

Exposure to PAHs can have chronic 

effects because some effects are 

sublethal (e.g., enzyme induction or 


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immune impairment) or delayed (e.g., 

cancer). Although it is true that some 

bears may be directly affected by spilled 

oil initially, the long-term impact could 

be much greater. Long-term effects 

could be substantial through complex 

environmental interactions— 

compromising the health of exposed 

animals. For example, PAHs can impact 

the food web by concentrating in filterfeeding organisms, thus affecting fish 

that feed on those organisms, and the 

predators of those fish, such as the 

ringed seals that polar bears prey upon. 

How these complex interactions would 

affect polar bears is not well 

understood, but sublethal, chronic 

effects of an oil spill may affect the 

polar bear population due to reduced 

fitness of surviving animals. 

Polar bears are biological sinks for 

some pollutants, such as 

polychlorinated biphenyls or 

organochlorine pesticides, because polar 

bears are an apex predator of the Arctic 

ecosystem and are also opportunistic 

scavengers of other marine mammals. 

Additionally, their diet is composed 

mostly of high-fat sealskin and blubber 

(Norstrom et al. 1988). The highest 

concentrations of persistent organic 

pollutants in Arctic marine mammals 

have been found in seal-eating walruses 

and polar bears near Svalbard (Norstrom 

et al. 1988, Andersen et al. 2001, Muir 

et al. 1999). As such, polar bears would 

be susceptible to the effects of 

bioaccumulation of contaminants, 

which could affect their reproduction, 

survival, and immune systems. 

In addition, subadult polar bears are 

more vulnerable than adults to 

environmental effects (Taylor et al. 

1987). Therefore, subadults would be 

most prone to the lethal and sublethal 

effects of an oil spill due to their 

proclivity for scavenging (thus 

increasing their exposure to oiled 

marine mammals) and their 

inexperience in hunting. Due to the 

greater maternal investment a weaned 

subadult represents, reduced survival 

rates of subadult polar bears have a 

greater impact on population growth 

rate and sustainable harvest than 

reduced litter production rates (Taylor 

et al. 1987). 

Evaluation of the potential impacts of 

spilled Industry waste products and oil 

suggest that individual bears could be 

adversely impacted by exposure to these 

substances (Oritsland et al. 1981). The 

major concern regarding a large oil spill 

is the impact such a spill would have on 

the rates of recruitment and survival of 

the SBS polar bear stock. Polar bear 

deaths from an oil spill could be caused 

by direct exposure to the oil. However, 

indirect effects, such as a reduction of 

prey or scavenging contaminated 

carcasses, could also cause health 

effects, death, or otherwise affect rates 

of recruitment and survival. Depending 

on the type and amount of oil or wastes 

involved and the timing and location of 

a spill, impacts could be acute, chronic, 

temporary, or lethal. For the rates of 

polar bear reproduction, recruitment, or 

survival to be impacted, a large-volume 

oil spill would have to take place. The 

following section analyzes the 

likelihood and potential effects of such 

a large-volume oil spill. 

Risk Assessment of Potential Effects 

Upon Polar Bears From a Large Oil 

Spill in the Beaufort Sea 

In this section, we qualitatively assess 

the likelihood that polar bear 

populations on the North Slope may be 

affected by large oil spills. We 

considered: (1) The probability of a large 

oil spill occurring in the Beaufort Sea; 

(2) the probability of that oil spill 

impacting coastal polar bear habitat; (3) 

the probability of polar bears being in 

the area and coming into contact with 

that large oil spill; and (4) the number 

of polar bears that could potentially be 

impacted by the spill. Although most of 

the information in this evaluation is 

qualitative, the probability of all factors 

occurring sequentially in a manner that 

impacts polar bears in the Beaufort Sea 

is low. Since walruses are not often 

found in the Beaufort Sea, and there is 

little information available regarding the 

potential effects of an oil spill upon 

walruses, this analysis emphasizes polar 

bears. 

The analysis was based on polar bear 

distribution and habitat use using four 

sources of information that, when 

combined, allowed the Service to make 

conclusions on the risk of oil spills to 

polar bears. This information included: 

(1) The description of existing offshore 

oil and gas production facilities 

previously discussed in the Description 

of Activities section; (2) polar bear 

distribution information previously 

discussed in the Biological Information 

section; (3) BOEM Oil-Spill Risk 

Analysis (OSRA) for the OCS (Li and 

Smith 2020), including polar bear 

environmental resource areas (ERAs) 

and land segments (LSs); and (4) the 

most recent polar bear risk assessment 

from the previous ITRs. 

Development of offshore production 

facilities with supporting pipelines 

increases the potential for large offshore 

spills. The probability of a large oil spill 

from offshore oil and gas facilities and 

the risk to polar bears is a scenario that 

has been considered in previous 

regulations (71 FR 43926, August 2, 

2006; 76 FR 47010, August 3, 2011; 81 

FR 52275, August 5, 2016). Although 

there is a slowly growing body of 

scientific literature (e.g., Amstrup et al. 

2006, Wilson et al. 2017), the 

background information available 

regarding the effects of large oil spills on 

polar bears in the marine arctic 

environment is still limited, and thus 

the impact of a large oil spill is 

uncertain. As far as is known, polar 

bears have not been affected by oil 

spilled as a result of North Slope 

Industry activities. 

The oil-spill scenarios for this 

analysis include the potential impacts of 

a large oil spill (i.e., 1,000 bbl or more) 

from one of the offshore Industry 

facilities: Northstar, Spy Island, 

Oooguruk, Endicott, or the future 

Liberty. Estimating a large oil-spill 

occurrence is accomplished by 

examining a variety of factors and 

associated uncertainty, including 

location, number, and size of a large oil 

spill and the wind, ice, and current 

conditions at the time of a spill. 

BOEM Oil Spill Risk Analysis 

Because the BOEM OSRA provides 

the most current and rigorous treatment 

of potential oil spills in the Beaufort Sea 

Planning Area, our analysis of potential 

oil spill impacts applied the results of 

BOEM’s OSRA (Li and Smith 2020) to 

help analyze potential impacts of a large 

oil spill originating in the Beaufort Sea 

ITR region to polar bears. The OSRA 

quantitatively assesses how and where 

large offshore spills will likely move by 

modeling effects of the physical 

environment, including wind, sea-ice, 

and currents, on spilled oil. (Smith et al. 

1982, Amstrup et al. 2006a). 

A previous OSRA estimated that the 

mean number of large spills is less than 

one over the 20-year life of past, present, 

and reasonably foreseeable 

developments in the Beaufort Sea 

Planning Area (Johnson et al. 2002). In 

addition, large spills are more likely to 

occur during development and 

production than during exploration in 

the Arctic (MMS 2008). Our oil spill 

assessment during a 5-year regulatory 

period is predicated on the same 

assumptions. 

Trajectory Estimates of Large Offshore 

Oil Spills 

Although it is reasonable to conclude 

that the chance of one or more large 

spills occurring during the period of 

these regulations on the Alaskan OCS 

from production activities is low, for 

analysis purposes, we assume that a 

large spill does occur in order to 

evaluate potential impacts to polar 

bears. The BOEM OSRA modeled the 

trajectories of 3,240 oil spills from 581 


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possible launch points in relation to the 

shoreline and biological, physical, and 

sociocultural resource areas specific to 

the Beaufort Sea. The chance that a large 

oil spill will contact a specific ERA of 

concern within a given time of travel 

from a certain location (launch area or 

pipeline segment) is termed a 

‘‘conditional probability.’’ Conditional 

probabilities assume that no cleanup 

activities take place and there are no 

efforts to contain the spill. 

We used two BOEM launch areas 

(LAs), LA 2 and LA 3, and one pipeline 

segment (PL), PL 2, from Appendix A of 

the OSRA (Figure A–2; Li and Smith 

2020) to represent the oil spills moving 

from hypothetical offshore areas. These 

LAs and PLs were selected because of 

their proximity to current and proposed 

offshore facilities. 

Oil-Spill-Trajectory Model Assumptions 

For purposes of its oil spill trajectory 

simulation, BOEM made the following 

assumptions: All spills occur 

instantaneously; large oil spills occur in 

the hypothetical origin areas or along 

the hypothetical PLs noted above; large 

spills do not weather (i.e., become 

degraded by weather conditions) for 

purposes of trajectory analysis; 

weathering is calculated separately; the 

model does not simulate cleanup 

scenarios; the oil spill trajectories move 

as though no oil spill response action is 

taken; and large oil spills stop when 

they contact the mainland coastline. 

Analysis of the Conditional Probability 

Results 

As noted above, the chance that a 

large oil spill will contact a specific 

ERA of concern within a given time of 

travel from a certain location (LA or PL), 

assuming a large spill occurs and that 

no cleanup takes place, is termed a 

‘‘conditional probability.’’ From the 

OSRA, Appendix B, we chose ERAs and 

land segments (LSs) to represent areas of 

concern pertinent to polar bears (MMS 

2008a). Those ERAs and LSs and the 

conditional probabilities that a large oil 

spill originating from the selected LAs 

or PLs could affect those ERAs and LSs 

are presented in a supplementary table 

titled ‘‘Conditional Oil Spill 

Probabilities’’ that can be found on 

http://www.regulations.gov under 

Docket No. FWS–R7–ES–2021–0037. 

From the information in this table, we 

note the highest chance of contact and 

the range of chances of contact that 

could occur should a large spill occur 

from LAs or PLs. 

Polar bears are vulnerable to a large 

oil spill during the open-water period 

when bears form aggregations onshore. 

In the Beaufort Sea, these aggregations 

often form in the fall near subsistenceharvested bowhead whale carcasses. 

Specific aggregation areas include Point 

Utqigvik, Cross Island, and Kaktovik. In 

recent years, more than 60 polar bears 

have been observed feeding on whale 

carcasses just outside of Kaktovik, and 

in the autumn of 2002, North Slope 

Borough and Service biologists 

documented more than 100 polar bears 

in and around Utqigvik. In order for 

significant impacts to polar bears to 

occur, (1) a large oil spill would have to 

occur, (2) oil would have to contact an 

area where polar bears aggregate, and (3) 

the aggregation of polar bears would 

have to occur at the same time as the 

spill. The risk of all three of these events 

occurring simultaneously is low. 

We identified polar bear aggregations 

in environmental resource areas and 

non-grouped land segments (ERA 55, 

93, 95, 96, 100; LS 85, 102, 107). The 

OSRA estimates the chance of 

contacting these aggregations is 18 

percent or less (see Table 1, 

‘‘Conditional Oil Spill Probabilities,’’ in 

the Supporting and Related Material in 

Docket No. FWS–R7–ES–2021–0037). 

The OSRA estimates for LA 2 and LA 

3 have the highest chance of a large spill 

contacting ERA 96 in summer (Midway, 

Cross, and Bartlett islands). Some polar 

bears will aggregate at these islands 

during August–October (3-month 

period). If a large oil spill occurred and 

contacted those aggregation sites outside 

of the timeframe of use by polar bears, 

potential impacts to polar bears would 

be reduced. 

Coastal areas provide important 

denning habitat for polar bears, such as 

the ANWR and nearshore barrier islands 

(containing tundra habitat) (Amstrup 

1993, Amstrup and Gardner 1994, 

Durner et al. 2006, USFWS unpubl. 

data). Considering that 65 percent of 

confirmed terrestrial dens found in 

Alaska in the period 1981–2005 were on 

coastal or island bluffs (Durner et al. 

2006), oiling of such habitats could have 

negative effects on polar bears, although 

the specific nature and ramifications of 

such effects are unknown. 

Assuming a large oil spill occurs, 

tundra relief barrier islands (ERA 92, 93, 

and 94, LS 97 and 102) have up to an 

18 percent chance of a large spill 

contacting them from PL 2. The OSRA 

estimates suggest that there is a 12 

percent chance that oil would contact 

the coastline of the ANWR (GLS 166). 

The Kaktovik area (ERA 95 and 100, LS 

107) has up to a one percent chance of 

a spill contacting the coastline. The 

chance of a spill contacting the coast 

near Utqiagvik (ERA 55, LS 85) would 

be as high as 15 percent (see Table 1, 

‘‘Conditional Oil Spill Probabilities,’’ in 

the Supporting and Related Material in 

Docket No. FWS–R7–ES–2021–0037). 

All barrier islands are important 

resting and travel corridors for polar 

bears, and larger barrier islands that 

contain tundra relief are also important 

denning habitat. Tundra-bearing barrier 

islands within the geographic region 

and near oilfield development are the 

Jones Island group of Pingok, 

Bertoncini, Bodfish, Cottle, Howe, 

Foggy, Tigvariak, and Flaxman Islands. 

In addition, Cross Island has gravel 

relief where polar bears have denned. 

The Jones Island group is located in 

ERA 92 and LS 97. If a spill were to 

originate from an LA 2 pipeline segment 

during the summer months, the 

probability that this spill would contact 

these land segments could be as great as 

15 percent. The probability that a spill 

from LA 3 would contact the Jones 

Island group would range from 1 

percent to as high as 12 percent. 

Likewise, for PL 2, the range would be 

from 3 percent to as high as 12 percent. 

Risk Assessment From Prior ITRs 

In previous ITRs, we used a risk 

assessment method that considered oil 

spill probability estimates for two sites 

(Northstar and Liberty), oil spill 

trajectory models, and a polar bear 

distribution model based on location of 

satellite-collared females during 

September and October (68 FR 66744, 

November 28, 2003; 71 FR 43926, 

August 2, 2006; 76 FR 47010, August 3, 

2011; and 81 FR 52275, August 5, 2016). 

To support the analysis for this action, 

we reviewed the previous analysis and 

used the data to compare the potential 

effects of a large oil spill in a nearshore 

production facility (less than 5 mi), such 

as Liberty, and a facility located further 

offshore, such as Northstar. Even though 

the risk assessment of 2006 did not 

specifically model spills from the 

Oooguruk or Nikaitchuq sites, we 

believe it was reasonable to assume that 

the analysis for Liberty and indirectly, 

Northstar, adequately reflected the 

potential impacts likely to occur from 

an oil spill at either of these additional 

locations due to the similarity in the 

nearshore locations. 

Methodology of Prior Risk Assessment 

The first step of the risk assessment 

analysis was to examine oil spill 

probabilities at offshore production sites 

for the summer (July–October) and 

winter (November–June) seasons based 

on information developed for the 

original Northstar and Liberty EISs. We 

assumed that one large spill occurred 

during the 5-year period covered by the 

regulations. A detailed description of 

the methodology can be found at 71 FR 


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43926 (August 2, 2006). The second step 

in the risk assessment was to estimate 

the number of polar bears that could be 

impacted by a large spill. All modeled 

polar bear grid cell locations that were 

intersected by one or more cells of a 

rasterized spill path (a modeled group of 

hundreds of oil particles forming a 

trajectory and pushed by winds and 

currents and impeded by ice) were 

considered ‘‘oiled’’ by a spill. For 

purposes of the analysis, if a bear 

contacted oil, the contact was assumed 

to be lethal. This analysis involved 

estimating the distribution of bears that 

could be in the area and overlapping 

polar bear distributions and seasonal 

aggregations with oil spill trajectories. 

The trajectories previously calculated 

for Northstar and Liberty sites were 

used. The trajectories for Northstar and 

Liberty were provided by the BOEM and 

were reported in Amstrup et al. (2006a). 

BOEM estimated probable sizes of oil 

spills from a pinhole leak to a rupture 

in the transportation pipeline. These 

spill sizes ranged from a minimum of 

125 to a catastrophic release event of 

5,912 bbl. Researchers set the size of the 

modeled spill at the scenario of 5,912 

bbl caused by a pinhole or small leak for 

60 days under ice without detection. 

The second step of the risk 

assessment analysis incorporated polar 

bear densities overlapped with the oil 

spill trajectories. To accomplish this, in 

2004, USGS completed an analysis 

investigating the potential effects of 

hypothetical oil spills on polar bears. 

Movement and distribution information 

were derived from radio and satellite 

locations of collared adult females. 

Density estimates were used to 

determine the distribution of polar bears 

in the Beaufort Sea. Researchers then 

created a grid system centered over the 

Northstar production island and the 

Liberty site to estimate the number of 

bears expected to occur within each 1- 

km2 grid cell. Each of the simulated oil 

spills were overlaid with the polar bear 

distribution grid. Finally, the likelihood 

of occurrence of bears oiled during the 

duration of the 5-year ITRs was 

estimated. This likelihood was 

calculated by multiplying the number of 

polar bears oiled by the spill by the 

percentage of time bears were at risk for 

each period of the year. 

In summary, the maximum numbers 

of bears potentially oiled by a 5,912-bbl 

spill during the September open-water 

season from Northstar was 27, and the 

maximum from Liberty was 23, 

assuming a large oil spill occurred and 

no cleanup or mitigation measures took 

place. Potentially oiled polar bears 

ranged up to 74 bears with up to 55 

bears during October in mixed-ice 

conditions for Northstar and Liberty, 

respectively. Median number of bears 

oiled by the 5,912-bbl spill from the 

Northstar simulation site in September 

and October were 3 and 11 bears, 

respectively. Median numbers of bears 

oiled from the Liberty simulation site 

for September and October were 1 and 

3 bears, respectively. Variation occurred 

among oil spill scenarios, resulting from 

differences in oil spill trajectories 

among those scenarios and not the 

result of variation in the estimated bear 

densities. For example, in October, 75 

percent of trajectories from the 5,912-bbl 

spill affected 20 or fewer polar bears 

from spills originating at the Northstar 

simulation site and 9 or fewer bears 

from spills originating at the Liberty 

simulation site. 

When calculating the probability that 

a 5,912-bbl spill would oil five or more 

bears during the annual fall period, we 

found that oil spills and trajectories 

were more likely to affect fewer than 

five bears versus more than five bears. 

Thus, for Northstar, the chance that a 

5,912-bbl oil spill affected (resulting in 

mortality) 5 or more bears was 1.0–3.4 

percent; 10 or more bears was 0.7–2.3 

percent; and 20 or more bears was 0.2– 

0.8 percent. For Liberty, the probability 

of a spill that would affect 5 or more 

bears was 0.3–7.4 percent; 10 or more 

bears, 0.1–0.4 percent; and 20 or more 

bears, 0.1–0.2 percent. 

Discussion of Prior Risk Assessment 

Based on the simulations, a nearshore 

island production site (less than 5 mi 

from shore) would potentially involve 

less risk of polar bears being oiled than 

a facility located farther offshore (greater 

than 5 mi). For any spill event, 

seasonality of habitat use by bears will 

be an important variable in assessing 

risk to polar bears. During the fall 

season when a portion of the SBS bear 

stock aggregate on terrestrial sites and 

use barrier islands for travel corridors, 

spill events from nearshore industrial 

facilities may pose more chance of 

exposing bears to oil due to its 

persistence in the nearshore 

environment. Conversely, during the 

ice-covered and summer seasons, 

Industry facilities located farther 

offshore (greater than 5 mi) may 

increase the chance of bears being 

exposed to oil as bears will be 

associated with the ice habitat. 

Conclusion of Risk Assessment 

To date, documented oil spill-related 

impacts in the marine environment to 

polar bears in the Beaufort Sea by the 

oil and gas Industry are minimal. No 

large spills by Industry in the marine 

environment have occurred in Arctic 

Alaska. Nevertheless, the possibility of 

oil spills from Industry activities and 

the subsequent impacts on polar bears 

that contact oil remain a major concern. 

There has been much discussion 

about effective techniques for 

containing, recovering, and cleaning up 

oil spills in Arctic marine 

environments, particularly the concern 

that effective oil spill cleanup during 

poor weather and broken-ice conditions 

has not been proven. Given this 

uncertainty, limiting the likelihood of a 

large oil spill becomes an even more 

important consideration. Industry oil 

spill contingency plans describe 

methodologies put in place to prevent a 

spill from occurring. For example, all 

current offshore production facilities 

have spill containment systems in place 

at the well heads. In the event an oil 

discharge should occur, containment 

systems are designed to collect the oil 

before it makes contact with the 

environment. 

With the limited background 

information available regarding oil 

spills in the Arctic environment, it is 

unknown what the outcome of such a 

spill event would be if one were to 

occur. For example, polar bears could 

encounter oil spills during the openwater and ice-covered seasons in 

offshore or onshore habitat. Although 

most polar bears in the SBS stock spend 

a large amount of their time offshore on 

the pack ice, it is likely that some bears 

would encounter oil from a large spill 

that persisted for 30 days or more. 

An analysis of the potential effects of 

a ‘‘worst case discharge’’ (WCD) on 

polar bears in the Chukchi Sea 

suggested that between 5 and 40 percent 

of a stock of 2,000 polar bears could be 

exposed to oil if a WCD occurred 

(Wilson et al. 2017). A similar analysis 

has not been conducted for the Beaufort 

Sea; however, given the extremely low 

probability (i.e., 0.0001) that an 

unmitigated WCD event would occur 

(BOEM 2015, Wilson et al. 2017), the 

likelihood of such effects on polar bears 

in the Beaufort Sea is extremely low. 

Although the extent of impacts from 

a large oil spill would depend on the 

size, location, and timing of spills 

relative to polar bear distributions along 

with the effectiveness of spill response 

and cleanup efforts, under some 

scenarios, stock-level impacts could be 

expected. A large spill originating from 

a marine oil platform could have 

significant impacts on polar bears if an 

oil spill contacted an aggregation of 

polar bears. Likewise, a spill occurring 

during the broken-ice period could 

significantly impact the SBS polar bear 

stock in part because polar bears may be 

more active during this season. 


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If an offshore oil spill contaminated 

numerous bears, a potentially 

significant impact to the SBS stock 

could result. This effect would be 

magnified in and around areas of polar 

bear aggregations. Bears could also be 

affected indirectly either by food 

contamination or by chronic lasting 

effects caused by exposure to oil. During 

the 5-year period of these regulations, 

however, the chance of a large spill 

occurring is low. 

While there is uncertainty in the 

analysis, certain factors must align for 

polar bears to be impacted by a large oil 

spill occurring in the marine 

environment. First, a large spill must 

occur. Second, the large spill must 

contaminate areas where bears may be 

located. Third, polar bears must be 

seasonally distributed within the 

affected region when the oil is present. 

Assuming a large spill occurs, BOEM’s 

OSRA estimated that there is up to a 6 

percent chance that a large spill from 

the analyzed sites would contact Cross 

Island (ERA 96) within 360 days, as 

much as a 12 percent chance that it 

would contact Barter Island and/or the 

coast of the ANWR (ERA 95 and 100, LS 

107, and GLS 166), and up to a 15 

percent chance that an oil spill would 

contact the coast near Utqigvik (ERA 55, 

LS 85) during the summer time period. 

Data from polar bear coastal surveys 

indicate that polar bears are unevenly 

and seasonally distributed along the 

coastal areas of the Beaufort Sea ITR 

region. Seasonally, only a portion of the 

SBS stock utilizes the coastline between 

the Alaska-Canada border and Utqiagvik 

and only a portion of those bears could 

be in the oil-spill-affected region. 

As a result of the information 

considered here, the Service concludes 

that the likelihood of an offshore spill 

from an offshore production facility in 

the next 5 years is low. Moreover, in the 

unlikely event of a large spill, the 

likelihood that spills would 

contaminate areas occupied by large 

numbers of bears is low. While 

individual bears could be negatively 

affected by a spill, the potential for a 

stock-level effect is low unless the spill 

contacted an area where large numbers 

of polar bears were gathered. Known 

polar bear aggregations tend to be 

seasonal during the fall, further 

minimizing the potential of a spill to 

impact the stock. Therefore, we 

conclude that the likelihood of a large 

spill occurring is low, but if a large spill 

does occur, the likelihood that it would 

contaminate areas occupied by large 

numbers of polar bears is also low. If a 

large spill does occur, we conclude that 

only small numbers of polar bears are 

likely to be affected, though some bears 

may be killed, and there would be only 

a negligible impact to the SBS stock. 

Take Estimates for Pacific Walruses 

and Polar Bears 

Small Numbers Determinations and 

Findings 

The following analysis concludes that 

only small numbers of walruses and 

polar bears are likely to be subjected to 

take incidental to the described Industry 

activities relative to their respective 

stocks. For our small numbers 

determination, we consider whether the 

estimated number of marine mammals 

to be subjected to incidental take is 

small relative to the population size of 

the species or stock. 

1. The estimated number of walruses 

and polar bears that will be harassed by 

Industry activity is small relative to the 

number of animals in their stocks. 

As stated previously, walruses are 

extralimital in the Beaufort Sea with 

nearly the entire walrus population 

found in the Chukchi and Bering Seas. 

Industry monitoring reports have 

observed no more than 38 walruses 

between 1995 and 2015, with only a few 

observed instances of disturbance to 

those walruses (AES Alaska 2015, 

USFWS unpublished data). Between 

those years, Industry walrus 

observations in the Beaufort Sea ITR 

region averaged approximately two 

walruses per year, although the actual 

observations were of a single or two 

animals, often separated by several 

years. At most, only a tiny fraction of 

the Pacific walrus population—which is 

comprised of hundreds of thousands of 

animals—may be found in areas 

potentially affected by AOGA’s 

specified activities. We do not 

anticipate that seasonal movements of a 

few walruses into the Beaufort Sea will 

significantly increase over the 5-year 

period of this ITR. The estimated take of 

15 Pacific walruses per year from a 

population numbering approximately 

283,213 animals represents 0.005 

percent of that population. We therefore 

find that the Industry activities 

specified in AOGA’s Request would 

result in only a small number of 

incidental harassments of walruses. 

The Beaufort Sea ITR region is 

completely within the range of the SBS 

stock of polar bears, and during some 

portions of the year polar bears can be 

frequently encountered by Industry. 

From 2014 through 2018, Industry made 

1,166 reports of polar bears comprising 

1,698 bears. However, when we 

evaluated the effects upon the 1,698 

bears observed, we found that 84 

percent (1,434) did not result in take. 

Over those 5 years, Level B harassments 

of polar bears totaled 264, 

approximately 15.5 percent of the 

observed bears. No other forms of take 

or harassment were observed. Annually 

an average of 340 polar bears were 

observed during Industry activities. The 

number of Level B harassment events 

has averaged 53 per year from 2014 to 

2018. We conclude that over the 5-year 

period of this ITR, Industry activities 

will result in a similarly small number 

of incidental harassments of polar bears, 

and that those events will be similarly 

limited to Level B harassment. 

Based on this information derived 

from Industry observations, along with 

the results of the Service’s own 

predictive modeling analysis described 

above, we estimate that there will be no 

more than 443 Level B harassment takes 

of polar bears during the 5-year period 

of this ITR, with no more than 92 

occurring within a single year. 

Conservatively assuming that each 

estimates take will accrue to a different 

individual polar bear, we note that take 

of 92 animals is 10.14 percent of the 

best available estimate of the current 

stock size of 907 animals in the 

Southern Beaufort Sea stock (Bromaghin 

et al. 2015, Atwood et al. 2020) ((92 ÷ 

907) × 100 ≈ 10.14), and find that this 

proportion represents a ‘‘small number’’ 

of polar bears of that stock. The 

incidental Level B harassment of no 

more than 92 polar bears each year is 

unlikely to lead to significant 

consequences for the health, 

reproduction, or survival of affected 

animals. All takes are anticipated to be 

incidental Level B harassment involving 

short-term and temporary changes in 

bear behavior. The required mitigation 

and monitoring measures described in 

the regulations are expected to prevent 

any lethal or injurious takes. 

2. Within the specified geographical 

region, the area of Industry activity is 

expected to be small relative to the 

range of walruses and polar bears. 

Walruses and polar bears range well 

beyond the boundaries of the Beaufort 

Sea ITR region. As such, the ITR region 

itself represents only a subset of the 

potential area in which these species 

may occur. Further, only seven percent 

of the ITR area (518,800 ha of 7.9 

million ha) is estimated to be impacted 

by the proposed Industry activities, 

even accounting for a disturbance zone 

surrounding industrial facility and 

transit routes. Thus, the Service 

concludes that the area of Industry 

activity will be relatively small 

compared to the range of walruses and 

polar bears. 


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Conclusion 

We expect that only small numbers of 

Pacific walruses and SBS polar bears 

stocks would be taken by the Industry 

activities specified in AOGA’s Request 

because: (1) Walruses are extralimital in 

the Beaufort Sea and SBS polar bears are 

widely distributed throughout their 

expansive range, which encompasses 

areas beyond the Beaufort Sea ITR 

region, meaning only a small proportion 

of the walrus or polar bear stocks will 

occur in the areas where Industry 

activities will occur; and (2) the 

estimated number of walruses and polar 

bears that could be impacted by the 

specified activities is small relative the 

size of the species (walruses) or stock 

(polar bears). 

Negligible Impacts Determination and 

Finding 

Based on the best scientific 

information available, the results of 

Industry monitoring data from the 

previous ITRs, the review of the 

information generated by the listing of 

the polar bear as a threatened species 

and the designation of polar bear critical 

habitat, the results of our modeling 

assessments, and the status of the 

species and stocks, we find that the 

incidental take we have estimated to 

occur and authorize through this ITR 

will have no more than a negligible 

impact on walruses and polar bears. We 

do not expect that the total of these 

disturbances will individually or 

collectively affect rates of recruitment or 

survival for walruses or polar bears. 

Factors considered in our negligible 

impacts determination include: 

1. The behavior and distribution of 

walruses and polar bears in areas that 

overlap with Industry activities are 

expected to limit interactions of 

walruses and polar bears with those 

activities. 

The distribution and habitat use 

patterns of walruses and polar bears 

indicate that relatively few animals will 

occur in the proposed areas of Industry 

activity at any particular time, and 

therefore, few animals are likely to be 

affected. As discussed previously, only 

small numbers of walruses are likely to 

be found in the Beaufort Sea where and 

when offshore Industry activities are 

proposed. Likewise, SBS polar bears are 

widely distributed across a range that is 

much greater than the geographic scope 

of the ITR, are most often closely 

associated with pack ice, and are 

unlikely to interact with the open water 

industrial activities specified in AOGA’s 

Request, much less the majority of 

activities that would occur onshore. 

2. The predicted effects of Industry 

activities on walruses and polar bears 

will be incidental nonlethal, temporary 

takes of animals. 

The documented impacts of previous 

Industry activities on walruses and 

polar bears, taking into consideration 

cumulative effects, suggests that the 

types of activities analyzed for this ITR 

will have minimal effects and will be 

short-term, temporary behavioral 

changes. The vast majority of reported 

polar bear observations have been of 

polar bears moving through the Beaufort 

Sea ITR region, undisturbed by the 

Industry activity. 

3. The footprint of the proposed 

Industry activities is expected to be 

small relative to the range of the walrus 

and polar bear stocks. 

The relatively small area of Industry 

activity compared to the ranges of 

walruses and polar bears will reduce the 

potential of their exposure to and 

disturbance from Industry activities. 

4. The type of harassment that is 

estimated is not expected to have effects 

on annual rates of recruitment of 

survival. 

The Service does not anticipate any 

lethal or injurious take that would 

remove individual polar bears or Pacific 

walruses from the population or prevent 

their successful reproduction. In fact, 

the majority of the Service’s model runs 

result in no serious injury Level A 

harassment or lethal takes and the 

median of the model runs is 0.0. Level 

B harassment events lead only to shortterm, non-injurious behavioral 

disturbances that do not reduce the 

affected animals’ probability of 

surviving or reproducing. These 

disturbances would not, therefore, affect 

the rates of recruitment or survival for 

the walrus and polar bear stocks. These 

regulations do not authorize lethal take, 

and we do not anticipate any lethal take 

will occur. 

5. Mitigation measures will limit 

potential effects of Industry activities. 

Under this regulation, holders of an 

LOA will be required to adopt 

monitoring requirements and mitigation 

measures designed to reduce the 

potential impacts of their operations on 

walruses and polar bears. Seasonal 

restrictions, early detection monitoring 

programs, den detection surveys for 

polar bears, and adaptive mitigation and 

management responses based on realtime monitoring information (described 

in these regulations) will be used to 

avoid or minimize interactions with 

walruses and polar bears and, therefore, 

limit potential Industry disturbance of 

these animals. 

In making this finding, we considered 

the following: The distribution of the 

species; the biological characteristics of 

the species; the nature of Industry 

activities; the potential effects of 

Industry activities and potential oil 

spills on the species; the probability of 

oil spills occurring; the documented 

impacts of Industry activities on the 

species, taking into consideration 

cumulative effects; the potential impacts 

of climate change, where both walruses 

and polar bears can potentially be 

displaced from preferred habitat; 

mitigation measures designed to 

minimize Industry impacts through 

adaptive management; and other data 

provided by Industry monitoring 

programs in the Beaufort and Chukchi 

Seas. 

We also considered the specific 

Congressional direction in balancing the 

potential for a significant impact with 

the likelihood of that event occurring. 

The Service has previously explained 

that Congressional direction that 

justifies balancing probabilities with 

impacts follows: 

If potential effects of a specified activity 

are conjectural or speculative, a finding of 

negligible impact may be appropriate. A 

finding of negligible impact may also be 

appropriate if the probability of occurrence is 

low but the potential effects may be 

significant. In this case, the probability of 

occurrence of impacts must be balanced with 

the potential severity of harm to the species 

or stock when determining negligible impact. 

In applying this balancing test, the Service 

will thoroughly evaluate the risks involved 

and the potential impacts on marine mammal 

populations. Such determination will be 

made based on the best available scientific 

information (53 FR 8474, March 15, 1988; 

accord 132 Cong. Rec. S 16305 (October. 15, 

1986)). 

We reviewed the effects of the oil and 

gas Industry activities on walruses and 

polar bears, including impacts from 

surface interactions, aircraft overflights, 

maritime activities, and oil spills. Based 

on our review of these potential 

impacts, past LOA monitoring reports, 

and the biology and natural history of 

walrus and polar bear, we conclude that 

any incidental take reasonably likely to 

occur as a result of projected activities 

will be limited to short term behavioral 

disturbances that would not affect the 

rates of recruitment or survival for the 

walrus and polar bear stocks. This 

regulation does not authorize lethal 

take, and we do not anticipate any lethal 

take will occur. 

The probability of an oil spill that will 

cause significant impacts to walruses 

and polar bears appears extremely low. 

We have included information from 

both offshore and onshore projects in 

our oil spill analysis. We have analyzed 

the likelihood of a marine oil spill of the 

magnitude necessary to lethally take a 


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significant number of polar bears for 

offshore projects and, through a risk 

assessment analysis, found that it is 

unlikely that there will be any lethal 

take associated with a release of oil. In 

the unlikely event of a catastrophic 

spill, we will take immediate action to 

minimize the impacts to these species 

and reconsider the appropriateness of 

authorizations for incidental taking 

through section 101(a)(5)(A) of the 

MMPA. 

We have evaluated climate change 

regarding walruses and polar bears. 

Climate change is a global phenomenon 

and was considered as the overall driver 

of effects that could alter walrus and 

polar bear habitat and behavior. 

Although climate change is a pressing 

conservation issue for walruses and 

polar bears, we have concluded that the 

authorized taking of walruses and polar 

bears during the activities proposed by 

Industry during this 5-year rule will not 

adversely impact the survival of these 

species and will have no more than 

negligible effects. 

Conclusion 

We find that the impacts of these 

specified activities cannot be reasonably 

expected to, and are not reasonably 

likely to, adversely affect Pacific walrus 

or SBS polar bears through effects on 

annual rates of recruitment or survival. 

We therefore find that the total of the 

taking estimated above and authorized 

by this ITR will have a negligible impact 

on Pacific walrus and SBS polar bears. 

These regulations do not authorize 

lethal take, and we do not anticipate 

that any lethal take will occur. 

Least Practicable Adverse Impacts 

We evaluated the practicability and 

effectiveness of mitigation measures 

based on the nature, scope, and timing 

of Industry activities; the best available 

scientific information; and monitoring 

data during Industry activities in the 

specified geographic region. We have 

determined that the mitigation measures 

included within AOGA’s Request—plus 

one additional mitigation measure noted 

below—will ensure the least practicable 

adverse impacts on polar bears and 

Pacific walruses (AOGA 2021). 

AOGA’s initial request reflected the 

mitigation measures identified in prior 

Beaufort Sea ITRs as necessary to effect 

the least practicable adverse impact on 

Pacific walrus and SBS polar bears. The 

Service also collaborated extensively 

with AOGA concerning prior iterations 

of its Request in order to identify 

additional effective and practicable 

mitigation measures, which AOGA then 

incorporated into its final Request. Polar 

bear den surveys before activities begin 

during the denning season, and the 

resulting 1.6-km (1-mi) operational 

exclusion zone around all known polar 

bear dens and restrictions on the timing 

and types of activities in the vicinity of 

dens will ensure that impacts to 

denning female polar bears and their 

cubs are minimized during this critical 

time. In addition to conducting den 

detection surveys, during seismic 

operations, AOGA will use advance 

crews that use denning habitat maps 

and trained observers to scout for 

potential denning habitat including 

deep snow and steep bluffs in order to 

increase avoidance of these areas. 

Minimum flight elevations over polar 

bear areas and flight restrictions around 

known polar bear dens would reduce 

the potential for bears to be disturbed by 

aircraft. Additionally, during certain 

vessel based operations, or while 

conducting significant activities along to 

the coast that could introduce sound 

into the marine environment, AOGA 

will use trained protected species 

observers to alert crews when Pacific 

walruses or polar bears are in the 

vicinity. If they observe Pacific walruses 

or polar bears, they will shut down, 

reduce, or modify activities as needed to 

mitigate potential impacts. Protected 

species observers may also be required 

by the Service for use during other 

activities including aircraft operations 

or surface operations to also reduce 

potential impacts. Finally, AOGA will 

implement mitigation measures to 

prevent the presence and impact of 

attractants such as the use of wildliferesistant waste receptacles and 

enclosing access doors and stairs. These 

measures will be outlined in polar bear 

and walrus interaction plans that are 

developed in coordination with the 

Service prior to starting activities. Based 

on the information we currently have 

regarding den and aircraft disturbance 

and polar bear attractants, we concluded 

that the mitigation measures outlined in 

AOGA’s Request (AOGA 2021) and 

incorporated into this final rule will 

practically and effectively minimize 

disturbance from the specified oil and 

gas activities. 

The only additional mitigation 

measure not already included in 

AOGA’s request but warranted to effect 

the least practicable adverse impact on 

polar bears and walruses is the 

requirement that aircraft operations 

within the ITR area will maintain an 

altitude of 1,500 ft above ground level 

when safe and operationally possible. 

Whereas AOGA’s request committed to 

fly at such levels under ideal 

conditions, and the Proposed ITR stated 

that aircraft ‘‘should’’ fly at such levels 

when safe and operationally possible, 

this Final Rule replaces the Proposed 

Rule’s use of ‘‘should’’ with ‘‘will’’. The 

Service determined that this revision 

could further reduce the extent to which 

aircraft are permitted to fly below 1,500 

ft above ground level and thus further 

minimizes potential disturbances to 

polar bears and walruses while 

preserving safety and continuity of 

operations at minimal to no extra cost. 

A number of additional mitigation 

measures were considered but 

determined not to be practicable means 

of reducing impacts. These measures are 

listed below: 

• Required use of helicopters for AIR 

surveys—Use of helicopters to survey 

active dens might actually lead to 

greater levels of disturbance and take 

compared to fixed-wing aircraft. 

Additionally, there have been no 

published data to indicate increased den 

detection efficacy of helicopter AIR. 

• Grounding all flights if they must fly 

below 1,500 feet—Requiring all aircraft 

to maintain an altitude of 1,500 ft is not 

practicable as some necessary 

operations may require flying below 

1,500 ft in order to perform inspections 

or maintain safety of flight crew. 

• Spatial and temporal restrictions on 

surface activity—Some spatial and 

temporal restrictions of operations were 

included in the ITR as a result of the 

Service’s collaboration with the 

applicant, but it was made clear during 

that process additional restrictions 

would not be practicable for oil and gas 

operations based on other regulatory 

and safety requirements. 

• One mile buffer around all known 

polar bear denning habitat—One mile 

buffer around all known polar bear 

denning habitat is not practicable as 

many existing operations occur within 

denning habitat and it would not be able 

to shut down all operations based on 

other regulatory and safety 

requirements. 

• Restriction of vessel speed to 10 

knots or less—Restricting the speed of 

all industry vessels to 10 knots or less 

is not practicable for safe and efficient 

operations. The Service analyzed take of 

walruses and polar bears for in-water 

activities within a 1-mile radius around 

a vessel at operational vessel speeds. 

Restricting vessel speeds unnecessarily 

will result in vessels spending more 

time in the water and it will increase the 

likelihood that marine mammals will be 

exposed to vessel disturbance for a 

longer period of time. 

• Requirements for pile driving sound 

mitigation—Additional mitigation 

measures to reduce in-water sound were 

not required as the area of sound 

propagation would not extend beyond 


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the impact area for visual disturbance 

that is already included in the analysis. 

Therefore, there is no additional 

mitigative benefit to requiring this 

measure. 

• Prohibition of driving over high 

relief areas, embankments, or stream 

and river crossings—While the denning 

habitat must be considered in tundra 

travel activities, complete prohibition of 

travel across such areas is not 

practicable because it would preclude 

necessary access to various operational 

areas and pose potential safety 

concerns. Moreover, not all high relief 

areas, embankments, and stream and 

river crossing constitute suitable polar 

bear denning habitat. 

• Use of a broader definition of 

‘‘denning habitat’’ for operational 

offsets—There is no available data to 

support broadening the defining 

features of denning habitat beyond that 

established by USGS. Such a 

redefinition would cause an increase in 

the area surveyed for maternal dens and 

increase potential harassment of bears 

on the surface. 

• Establishment of corridors for sow 

and cub transit to the sea ice—As there 

is no data to support the existence of 

natural transit corridors to the sea ice, 

establishment of corridors in the ITR 

area would be highly speculative. 

Therefore, there would be no mitigative 

benefit realized by their establishment. 

• Requirement of third-party neutral 

marine mammal observers—It is often 

not practicable to hire third-party 

marine mammal observers due to 

operational constraints. Additional crew 

may require additional transit vehicles, 

which could increase disturbance. 

• Require all activities to cease if a 

polar bear or walrus is injured or killed 

until an investigation is completed— 

The Service has incorporated into this 

rule reporting requirements for all polar 

bear and Pacific walrus interactions. 

While it may aid in any subsequent 

investigation, ceasing activities in an 

active oil field may not be practicable or 

safe in certain circumstances, and thus 

will not be mandated. 

• Require use of den detection dogs— 

It is not practicable to require scent 

trained dogs to detect dens due to the 

large spatial extent that would need to 

be surveyed each year. 

• Require the use of handheld or 

vehicle-mounted FLIR—The efficacy 

rates for AIR has been found to be four 

times more likely to detect dens versus 

ground-based FLIR (handheld or 

vehicle-mounted FLIR) due to impacts 

of blowing snow on detection. While 

use of handheld or vehicle-mounted 

FLIR could increase the potential of 

detecting active dens in some 

circumstances, in other circumstances 

these potential benefits could be 

outweighed by the additional 

disturbances created by increasing 

vehicle use or human presence in the 

vicinity of dens. The safety of personnel 

tasked to prolong their presence in such 

areas is also an important consideration. 

The Service therefore finds that use of 

such techniques should remain at the 

discretion of operators on a case-by-case 

basis. 

Impacts on Subsistence Uses 

We based our findings on past 

experience, requirements concerning 

community consultations through the 

Plan of Cooperation (POC) process, the 

limited anticipated overlap of hunting 

areas and Industry projects, the best 

scientific information available, 

anticipated 5-year effects of Industry 

activities on subsistence hunting, and 

the results of monitoring data and the 

Service’s Marking, Tagging, and 

Reporting Program. Through these data, 

we find that any incidental harassment 

that may result from oil and gas 

exploration, development, and 

production activities in the specified 

geographic region will not have an 

unmitigable adverse impact on the 

availability of walruses and polar bears 

for taking for subsistence uses during 

the regulatory timeframe. 

While walruses and polar bears 

represent a small portion, in terms of 

the number of animals, of the total 

subsistence harvest for the communities 

of Utqiagvik, Nuiqsut, and Kaktovik, the 

harvest of these species is important to 

Alaska Natives. Prior to receipt of an 

LOA, Industry must provide evidence to 

us that community consultations have 

occurred or that an adequate POC has 

been presented to the subsistence 

communities. Industry will be required 

to contact subsistence communities that 

may be affected by its activities to 

discuss potential conflicts caused by 

location, timing, and methods of 

proposed operations. Industry must 

make reasonable efforts to ensure that 

activities do not interfere with 

subsistence hunting and that adverse 

effects on the availability of walruses 

and polar bear are minimized. Although 

multiple meetings for multiple projects 

from numerous operators have already 

taken place, no official concerns have 

been voiced by the Alaska Native 

communities regarding Industry 

activities limiting availability of 

walruses or polar bears for subsistence 

uses. However, should such a concern 

be voiced as Industry continues to reach 

out to the Alaska Native communities, 

development of POCs, which must 

identify measures to minimize any 

adverse effects, will be required. The 

POC will ensure that oil and gas 

activities will not have an unmitigable 

adverse impact on the availability of the 

species or stock for subsistence uses. 

This POC must provide the procedures 

addressing how Industry will work with 

the affected Alaska Native communities 

and what actions will be taken to avoid 

interference with subsistence hunting of 

walruses and polar bears, as warranted. 

The Service has not received any 

reports and is aware of no information 

that indicates that walruses or polar 

bears are being or will be deflected from 

hunting areas or impacted in any way 

that diminishes their availability for 

subsistence use by the expected level of 

oil and gas activity. If there is evidence 

during the 5-year period of the 

regulations that oil and gas activities are 

affecting the availability of walruses or 

polar bears for take for subsistence uses, 

we will reevaluate our findings 

regarding permissible limits of take and 

the measures required to ensure 

continued subsistence hunting 

opportunities. 

Monitoring and Reporting 

The purpose of monitoring 

requirements is to assess the effects of 

industrial activities on walruses and 

polar bears, ensure that the number of 

takes and the effects of taking are 

consistent with that anticipated in the 

ITR, and detect any unanticipated 

effects on the species or stocks. 

Monitoring plans document when and 

how bears and walruses are 

encountered, the number of bears and 

walruses, and their behavior during the 

encounter. This information allows the 

Service to measure encounter rates and 

trends of walrus and polar bear activity 

in the industrial areas (such as numbers 

and gender, activity, seasonal use) and 

to estimate numbers of animals 

potentially affected by Industry. 

Monitoring plans are site-specific, 

dependent on the proximity of the 

activity to important habitat areas, such 

as den sites, travel corridors, and food 

sources; however, Industry is required 

to report all sightings of walruses and 

polar bears. To the extent possible, 

monitors will record group size, age, 

sex, reaction, duration of interaction, 

and closest approach to Industry 

onshore. Activities within the specified 

geographic region may incorporate daily 

watch logs as well, which record 24- 

hour animal observations throughout 

the duration of the project. Polar bear 

monitors will be incorporated into the 

monitoring plan if bears are known to 

frequent the area or known polar bear 

dens are present in the area. At offshore 

Industry sites, systematic monitoring 


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1The use of DiscoverText does not convey or 

imply that the Service directly or indirectly 

endorses any product or service provided. 

protocols will be implemented to 

statistically monitor observation trends 

of walruses or polar bears in the 

nearshore areas where they usually 

occur. 

Monitoring activities will be 

summarized and reported in a formal 

report each year. The applicant must 

submit an annual monitoring and 

reporting plan at least 90 days prior to 

the initiation of a proposed activity, and 

the applicant must submit a final 

monitoring report to us no later than 90 

days after the expiration of the LOA. We 

base each year’s monitoring objective on 

the previous year’s monitoring results. 

We require an approved plan for 

monitoring and reporting the effects of 

oil and gas Industry exploration, 

development, and production activities 

on polar bears and walruses prior to 

issuance of an LOA. Since production 

activities are continuous and long term, 

upon approval, LOAs and their required 

monitoring and reporting plans will be 

issued for the life of the activity or until 

the expiration of the regulations, 

whichever occurs first. Each year, prior 

to January 15, we will require that the 

operator submit development and 

production activity monitoring results 

of the previous year’s activity. We 

require approval of the monitoring 

results for continued operation under 

the LOA. 

We find that this regulation will 

establish monitoring and reporting 

requirements to evaluate the potential 

impacts of planned activities and to 

ensure that the effects of the activities 

remain consistent with the rest of the 

findings. 

Summary of and Response to 

Comments and Recommendations 

Response to Comments 

The Service published a proposed 

rule in the Federal Register (FR) on June 

1, 2021, with a 30-day period seeking 

comments on both the proposed ITR 

and the draft EA (86 FR 79082). The 

comment period closed on July 1, 2021. 

The Service received 30,271 comments. 

Comments were received from two 

Federal agencies, the Marine Mammal 

Commission, the State of Alaska, the 

North Slope Borough, various trade and 

environmental organizations, and 

interested members of the public. 

We reviewed all comments, which are 

part of the docket for this ITR, for 

substantive issues, new information, 

and recommendations regarding this 

ITR and EA. The Service used 

‘‘DiscoverText’’ 1 to aggregate the 

comments submitted by the public. The 

Service determined that of the 

comments received, 30,251, aggregated 

and submitted by the Center for 

Biological Diversity, consisted of 

comments all of which expressed 

opposition to the promulgation of the 

regulation. All 30,251 of these 

comments either repeated, summarized, 

or provided edits to a standardized 

message. The Service notes that these 

modified form letters provided no new 

information or specific comments but 

rather brief to lengthy statements 

expressing the writer’s general 

opposition to the ITR. 

The comments are aggregated by 

subject matter, summarized and 

addressed below, and changes have 

been incorporated into the final rule and 

final EA as appropriate. A summary of 

the changes to this final ITR from the 

proposed ITR is found in the preamble 

section entitled, Summary of Changes 

from the Proposed Rule. 

Response to Comments 

MMPA Requirements 

Comment 1: One commenter 

suggested that the Service’s definition of 

harassment does not consider the 

‘‘potential’’ to disrupt biologically 

important behaviors, which results in an 

underestimation of the amount of take 

from activities. 

Response: The Service acknowledges 

that the definitions of harassment 

relevant to AOGA’s specified activities 

are those found at 16 U.S.C. 

1362(18)(A)(i)–(ii). These definitions are 

cited in the ITR and were employed in 

the Service’s analysis. The Service 

disagrees with the commenter’s 

assertion that the Service misapplied 

these definitions in the ITR. The ITR 

language quoted by the comment is a 

partial quote that is not portrayed in 

appropriate context. The Service stands 

by its assumption that not all minor 

changes in behavior (i.e., 

‘‘disturbances’’) are of a type that can 

result in harassment, even Level B 

harassment, because they simply would 

not disrupt natural behavioral patterns. 

By way of a simple example, where a 

polar bear perceived noise from an 

industrial source located several miles 

away, the bear could potentially 

manifest a ‘‘disturbance’’ by briefly 

pausing travel and/or looking toward 

the noise source, but it would quickly 

resume what it was doing a moment 

prior, without any disruption to its 

pattern of natural behavior. That said, 

where the noise source is sufficiently 

loud or close to the polar bear such that 

the polar bear may flee, express stressrelated behavior, abandon a hunt, find 

itself unable to rest for long periods, or 

react in one of the numerous other 

manners cited by the ITR as indicative 

of a disruption of natural behavioral 

patterns, the Service assumes that a take 

by Level B harassment occurs. 

Meanwhile, the Service disagrees 

with the commenter’s apparent 

suggestion to use the most sensitive 

individual (an ‘‘outlier’’ in statistical 

terms) in the SBS population as the 

basis for all of its modeling 

assumptions. Doing so would ignore the 

best available scientific evidence about 

how the vast majority of polar bears 

react to industrial stimuli, effectively 

replace the implementing regulations’ 

use of the terms ‘‘likely’’ and 

‘‘anticipated’’ with the term ‘‘possible’’ 

(See 50 CFR 18.27(d)), result in vast 

overestimations of take, and fail to 

reflect what the Service or any other 

objective party could reasonably 

anticipate occurring. When conducting 

complex acoustic modeling of potential 

marine mammal responses to industrial 

stimuli, one must necessarily make a 

series of reasonable assumptions 

(including development and application 

of acoustic thresholds) in order to 

evaluate and quantify the potential for 

harassment. The Service’s general 

approach and assumptions here are 

analogous to those typically utilized by 

the National Marine Fisheries Service 

(NMFS) when assessing the potential for 

anthropogenic noise to harass marine 

mammals. 

While it is possible that some animals 

do in fact experience disruption of 

behavioral patterns upon exposure to 

intermittent sounds at received levels 

less than [the 160dB acoustic threshold 

used by NMFS], this is not in and of 

itself adequate justification for using a 

lower threshold. Implicit in the use of 

a step function for quantifying Level B 

harassment is the realistic assumption, 

due to behavioral context and other 

factors, that some animals exposed to 

received levels below the threshold will 

in fact experience harassment, while 

others exposed to levels above the 

threshold will not. The Service 

reiterates two key concepts 

underpinning NMFS’s modeling 

approach and comment response—that 

modeling assumptions must be realistic 

as opposed to based on outliers, and 

that not all disturbances lead to 

disruption of behavioral patterns and 

Level B harassment. 

Comment 2: One commenter 

suggested that the Service acknowledges 

a marine mammal’s movement away 

from an area as take by Level B 

harassment, but they do not account for 

this movement in their take estimates. 


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Response: We disagree. As a nomadic 

species, any assumptions of an 

individual polar bear’s intent to inhabit 

a specific location would be arbitrary. 

Included in our estimates of takes by 

level B harassment are instances when 

a polar bear changes course and moves 

in a different direction due to human 

interaction. However, the Service does 

not consider only ‘‘increased vigilance’’ 

to be a form of Level B harassment, 

because increased awareness of 

potential hazards in an animal’s 

environment does not constitute a 

disruption of biologically significant 

behaviors as defined in the MMPA. 

Further, the Service does not classify a 

lower probability of denning near 

industrial infrastructure as a form of 

Level B harassment. We explain in the 

proposed rule that denning habitat 

adjacent to industrial activity has not 

been removed as a potential denning 

location. This is evidenced by our use 

of a probability distribution to 

determine potential offsets from active 

industrial sites when placing simulated 

dens, as opposed to a strict rule of 

simulating dens a fixed distance away 

from industry. We include the potential 

impact from new oil and gas 

infrastructure when simulating dens 

during our denning analysis as well. 

Comment 3: One commenter 

suggested that the Service should 

reevaluate their determinations and 

either deny the Request to issue an 

authorization or issue a revised 

proposed ITR after addressing public 

comments before promulgating the ITR. 

Response: The Service disagrees. The 

ITR includes a thorough and robust 

analysis based on detailed descriptions 

from the applicant of specified activities 

and the best available science. The 

Service has reasonably determined that 

the taking associated with AOGA’s 

specified activities meets all applicable 

MMPA standards and will therefore 

issue the requested ITR, subject to 

appropriate conditions, pursuant to its 

statutory directive. There are no 

significant changes to AOGA’s Request 

or the Service’s assumptions, or analysis 

that would require publishing a revised 

proposed ITR. 

Comment 4: Commenters suggested 

that the Service is applying new and 

unreasonable interpretation of ‘‘small 

numbers’’ and should define their small 

numbers determination as well as 

explain why the Service anticipates an 

increase in harassment during this 5- 

year regulation period compared to the 

previous 5-year regulation period. 

Response: The Service’s ‘‘small 

numbers’’ determination is consistent 

with applicable law, policy, and 

longstanding practice. There are several 

considerations relevant to the Service’s 

‘‘small numbers’’ standard, but the 

number of takes estimated in prior 

regulatory processes is not one of them. 

The SBS population estimate, calculated 

by USGS in 2020, is calculated using a 

number of annual metrics, including 

annual survival probabilities, annual 

number of dens, and annual denning 

success. The resulting value is an 

estimate of the number of individuals in 

the population in any given 

contemporary year. Appropriately, the 

Service has divided annual take 

estimates by the annual population 

estimate, to calculate a percentage of the 

population potentially taken for its 

small numbers determination. 

The Service has explained at length 

the quantitative methods that have been 

used to estimate the number of Level B 

harassment events projected in the 

proposed ITR. 

Comment 5: One commenter 

suggested that the Service combined the 

small numbers determination with the 

negligible impact determination, and 

these determinations should be 

addressed separately. 

Response: The Service rendered 

separate determinations for ‘‘small 

numbers’’ and ‘‘negligible impact’’ 

based on the distinct considerations 

relevant to each standard. It did not 

‘‘conflate’’ these findings. This was 

explained in the proposed rule and 

remains true in the Final ITR. 

Comment 6: One commenter 

suggested that the Service’s small 

number determination is inconsistent 

with the number of takes by Level B 

harassment anticipated for SBS polar 

bears and that polar bears repeatedly 

harassed should be considered in the 

Service’s determination. 

Response: The potential that 

individual polar bears could experience 

multiple incidents of Level B 

harassment was acknowledged and 

accounted for in this analysis. The 

effects of each incident of Level B 

harassment (as opposed to more severe 

forms of take) are inherently limited and 

short term, and the Service does not 

anticipate that the effects of multiple 

Level B harassments of the same polar 

bear would aggregate or combine with 

each other in a manner that causes 

anything greater than Level B 

harassment. Per the MMPA, ‘‘small 

numbers’’ refers to the number of 

animals incidentally taken, not the 

number of incidental takes as the 

comment here suggests. That said, 

because the Service could not reliably 

calculate how many of the anticipated 

Level B harassments would accrue to 

the same animals, it conservatively 

assumed for the purposes of its ‘‘small 

numbers’’ determination that each of the 

anticipated takes would accrue to a 

different animal. 

Comment 7: Commenters suggested 

that the Service ignores the potential 

negligible impact implications for a 

skew within the model used to analyze 

denning impacts and the potential for 

take by Level A harassment. 

Response: The ITR does not authorize 

any Level A harassment or lethal take of 

polar bears (nor did AOGA request 

authorization for such take). The Service 

did employ a complex model to analyze 

the probability that harassing a denning 

or post-emergent bear could result in 

lethal take of her cubs. We provided all 

of the output data from the simulations 

as part of the proposed rule to be 

transparent and allow commenters to 

see for themselves where take comes 

from and why there is such a significant 

skew in the data on the number of 

estimated lethal take or serious take by 

Level A harassment. The reason for the 

skew is because the majority (i.e., 54%) 

of model iterations estimated 0 serious 

takes by Level A harassment or lethal 

takes occurring annually. We disagree 

with the commenter that the skew is 

caused by a combination of the number 

of dens and the number of bears in dens 

that are disturbed. In reality, the skew 

is the result of the high number of 

iterations where 0 take is estimated. It 

is true that the tail of the distribution is 

a function of the number of dens 

disturbed and the number of cubs in 

those dens. We disagree that the Service 

is ignoring the potential for take by 

Level A harassment. We presented all of 

the output of the model to be as 

transparent as possible, and to fully 

assess the potential that estimated and 

authorized Level B harassment of a 

denning or post-emergent sow could 

result in abandonment of her cubs. We 

also disagree that the mean is the 

appropriate metric to consider when 

estimating the expected level of take 

associated with the proposed activities. 

Means are the appropriate measure of 

central tendency when data are 

normally distributed or some other 

symmetric distribution. In these cases, 

the mean and median are nearly the 

same. However, when the data are 

significantly skewed, as our results are, 

the median is a more appropriate 

informative measure of the central 

tendency in the data. 

Comment 8: Commenters suggested 

that the Service should consider the 

effects of potential take by Level A 

harassment and potential lethal take of 

polar bear cubs for the negligible 

impact. 

Response: The Service has conducted 

a thorough analysis using detailed 


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project descriptions from the applicant 

and quantitative estimates of take 

developed using the best available 

science. As is explained in the proposed 

rule, due to the low (<0.29 for nonserious Level A and ≤0.462 for serious 

take by Level A harassment/lethal takes) 

probability of greater than or equal to 1 

non-serious or serious injury Level A 

harassment/lethal take each year of the 

proposed ITR period, combined with 

the median of 0.0 for each, we do not 

estimate the proposed activities will 

result in non-serious or serious injury 

Level A harassment or lethal take of 

polar bears. 

The Service is not authorizing any 

lethal take (or any forms of take other 

than by Level B harassment). The 

Service fully considers the probability 

that the authorized take will adversely 

affect the species or stock through 

effects on annual rates of recruitment or 

survival. 50 CFR 18.27(c). 

Comment 9: One commenter 

suggested that the Service used outdated 

polar bear survey data for the Service’s 

small number and negligible impact 

determinations and the Service should 

use more recent data on the SBS polar 

bear stock in order to make the small 

numbers and negligible impact 

determinations. 

Response: The Service is obligated to 

render its MMPA determinations based 

on the best available scientific evidence. 

The most recent population estimate 

available for the SBS stock of polar 

bears is contained within a 2020 report 

from USGS, and this estimate was 

utilized in the Service’s analysis. 

Comment 10: One commenter 

suggested that the Service should 

conduct further research on the 

availability of polar bears for 

subsistence uses. 

Response: The Service acknowledges 

that more studies on the current 

availability of polar bears for 

subsistence hunting on the Coastal Plain 

of Alaska could improve our analysis. 

However, as discussed in the proposed 

rule, and reaffirmed in this final rule, 

the Service has based our 

determinations on the best information 

currently available. 

Comment 11: One commenter 

suggested the Service should conduct 

further research on human-polar bear 

interactions during oil and gas activities 

in order to reduce polar bear take during 

these interactions and to better inform 

the Service’s small numbers and 

negligible impact determinations. 

Response: The Service acknowledges 

that additional information to better 

understand human-polar bear 

interactions and how to avoid, reduce, 

and mitigate the number of bears taken 

as a result of conflicts with oil and gas 

activities would be beneficial. However, 

as discussed in the proposed rule, and 

reaffirmed in this final rule, the Service 

has based our determinations on the 

best information currently available. 

Comment 12: One commenter 

suggested that the Service should 

analyze the impacts of incidental takes 

during previous regulation periods in 

order to assess cumulative impacts of 

those previous takes on the SBS polar 

bear stock and the Service should use 

this information to inform the Service’s 

small numbers and negligible impact 

determinations for the current 

regulation period. 

Response: The Service appreciates the 

concerns raised in this comment. As 

discussed in the proposed rule, and 

affirmed in this final rule, the Service 

requires holders of an LOA to report, as 

soon as possible, but within 48 hours, 

all LOA incidents during any Industry 

activity. The Service, in turn, monitors 

these reports to ensure the type of take, 

if any, are consistent with the terms of 

the LOA. The Service also monitors the 

cumulative takes reported by all LOA 

holders to ensure the total number of 

takes, authorized under an ITR, do not 

exceed those authorized/estimated. The 

Service used this information when it 

considered the environmental baseline 

and status of the species and when it 

evaluated the impacts of AOGA’s 

specified activities. 

Comment 13: One commenter 

suggested that the Service should 

consider including take from other 

sources not related to oil and gas 

activities, such as subsistence take and 

unknown mortality events, as part of the 

Service’s environmental baseline, which 

is used to estimate take and determine 

negligible impact. 

Response: The Service adequately 

considered the potential for all forms of 

take—including take for subsistence 

uses—as well as natural mortality when 

conducting its analysis and making its 

negligible impact finding. 

Comment 14: One commenter 

suggested that the Service should 

include climate change impacts as part 

of the Service’s analysis to estimate take 

for the regulation period. 

Response: The Service presented a 

thorough discussion on the baseline 

conditions for the population, including 

the potential effects of climate change 

on polar bears, Pacific walruses, and 

prey species. The ITR authorizes only 

Level B harassment of small numbers of 

the population. Such take would result 

in only temporary behavioral changes 

even considering the current baseline 

stressors experienced by the population 

due to climate change. No Level A 

harassment or lethal take is estimated as 

a result of the proposed activities, and 

none is authorized by this ITR. 

Comment 15: Commenters suggested 

that the Service should base the 

Service’s small numbers determination 

on the total estimated take number for 

the 5-year regulation period instead of 

the annual take estimates across the 5- 

year regulation period. 

Response: The SBS population 

estimate, calculated by USGS in 2020, is 

calculated using a number of annual 

metrics, including annual survival 

probabilities, annual number of dens, 

and annual denning success. The 

resulting value is an estimate of the 

number of individuals in the population 

in any given contemporary year. 

Appropriately, the Service has divided 

annual take estimates by the annual 

population estimate, to calculate a 

percentage of the population potentially 

taken for its small numbers 

determination. This approach best 

enables the Service to assess whether 

the number of animals taken is small 

relative to the species or stock. 

Consideration of annual estimates tracks 

with the use of ‘‘each’’ in 16 U.S.C. 

1371(a)(5)(A)(i) and the use of annual 

LOAs to authorize the incidental take. 

Comparing the aggregate number of 

takes over 5 years with a population 

estimate specific to 1 year, as 

commenter suggest doing, is a less 

suitable comparison. In previous 

Beaufort Sea ITRs, the Service has 

always relied on annual estimates based 

on encounters during previous years 

and the proportion of those individuals 

that experienced take by Level B 

harassment. This ITR differs in that it 

uses the best available science and 

additional details associated with each 

project to more accurately estimate 

encounters and takes anticipated by the 

specified activities. The Service’s ‘‘small 

numbers’’ determination here is 

consistent with applicable law, policy, 

and longstanding practice. 

Comment 16: One commenter 

suggested that the Service should clarify 

that the scope of the proposed rule is 

the issuance of the proposed ITR and 

that the proposed ITR does not 

authorize proposed activities. 

Response: The Service agrees that the 

proposed action analyzed in the EA is 

the issuance of an ITR and authorization 

of incidental take associated with 

AOGA’s specified activities, and not 

approval of the oil and gas activities 

themselves. The Service also agrees that 

the ITR does not authorize intentional 

take and agrees that oil spills are not a 

consequence of ITR or the Proposed 

Action analyzed in the Service’s EA. 


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Comment 17: One commenter 

suggested that the Service should clarify 

the activities that exceed the scope of 

the Service’s analysis and 

determinations and will not be issued 

an LOA. 

Response: The Service has provided 

language to this final rule that clarifies 

the activities addressed in this ITR and 

the incidental take that may be 

authorized via LOAs. 

Comment 18: One commenter 

suggested that the Service should 

broaden the list of entities associated 

with the Request that are able to apply 

for LOAs. 

Response: We agree. This final rule 

has been revised to clarify what entities 

may request LOAs under these 

regulations. 

Comment 19: One commenter 

suggested that the Service’s larger take 

estimate for polar bears compared to the 

previous ITR’s polar bear take estimate 

and the reduced polar bear population 

size is inconsistent with the Service’s 

negligible impact determination. 

Response: ‘‘Negligible impact’’ 

determinations are based on several 

considerations, but the number of takes 

estimated in prior regulatory processes 

is not one of them. The Service rendered 

its negligible impact determination here 

based on the effects of the taking from 

the activities specified in the pending 

Request. 

Comment 20: Commenters suggested 

that the Service did not ensure that the 

proposed activities will have the least 

adverse impact practicable. 

Response: We disagree. As explained 

in the proposed rule, and affirmed in 

this final rule, the Service conducted a 

robust analysis, on the proposed 

activities and, based on that analysis, 

prescribed the means that will effect the 

least practicable adverse impact on 

Pacific walrus and SBS polar bears, 

their habitat, and their availability for 

taking for subsistence use by Alaska 

Natives. 

Comment 21: One commenter 

suggested that the Service arbitrarily 

and capriciously underestimated the 

likelihood of take other than that by 

Level B harassment to occur during the 

regulation period. 

Response: We disagree. As explained 

in the proposed rule, and affirmed in 

this final rule, the Service conducted a 

robust analysis of the potential effects of 

AOGA’s specified activities. Further, we 

sought public comment on our analysis, 

affording interested parties the 

opportunity to provide new information 

on our analysis and considered all 

information provided to the Service 

prior to finalizing these regulations. The 

Service’s actions are therefore lawful 

and, in no way, arbitrary and capricious. 

Comment 22: One commenter 

suggested that the Service’s analysis of 

activity impacts was too specific, which 

exceeds the scope of the ITR, and this 

approach inappropriately merges the 

LOA process, which requests 

authorization for incidental take during 

specific activities, into the ITR analysis. 

Response: The Service acknowledges 

that it requested and analyzed more 

detailed information concerning the 

requestor’s specified activities than is 

typically provided, but maintains that 

doing so was necessary to rigorously 

analyze these activities and confirm that 

applicable MMPA standards are met. 

The Service’s enhanced analytical 

approach utilized newly-available 

information and predictive modeling 

techniques that better account for 

potential effects to polar bears that may 

occur but remain beyond observers’ 

capacity to perceive. A comparatively 

greater degree of specificity concerning 

the requestors’ specified activities was 

required to (1) ensure that the Service 

accounted for both observable and 

unobservable take, and (2) reduce 

uncertainties about the level, location, 

and duration of the specified activities 

and thus limit the use of overlyconservative assumptions that result in 

inappropriate overestimation of take. 

The Service conducted this more indepth analysis at the ITR stage so the 

results could inform its MMPA-required 

determinations (e.g., small numbers, 

negligible impact, no unmitigable 

adverse impact on availability for 

subsistence uses, least practicable 

adverse impact). 

Comment 23: One commenter 

suggested that the Service should 

remove language that potentially limits 

which U.S. citizens can apply for LOAs 

under the ITR. 

Response: We disagree. Section 

101(5)(A)(i) of the MMPA and the 

Service’s implementing regulations 

afford requestors with broad discretion 

in delineating scope of the activities 

specified in their request. U.S. citizens 

intending to engage in activities not 

encompassed by a particular request can 

submit their own request, which the 

Service will review accordingly. 

The Service acknowledges that under 

past ITRs we have issued LOAs to 

entities not specifically named in the 

request for regulations. This practice 

was permissible under the applicable 

ITR. 

Comment 24: One commenter 

suggested that the Service did not 

provide oil and gas operators not 

specified in the ITR with a sufficiently 

advance notice to apply for a separate 

incidental take authorization without a 

gap in coverage. 

Response: We disagree with the 

notion that the Service is obligated to 

inform operators that they will not be 

covered by an ITR they did not request. 

The Service does acknowledge that 

under past ITRs we have issued LOAs 

to entities not specifically named in the 

request for regulations. However, the 

narrower scope of the current request 

and the Service’s ensuing analysis does 

not allow for that practice. We note that 

the MMPA and our regulations allow 

other qualifying companies to request 

ITRs or IHAs for their activities. 

Comment 25: One commenter 

suggested that the Service should 

reconsider its small numbers 

determination based on the estimated 

number of takes by Level B harassment. 

Response: As was stated in the 

proposed rule, take of 92 animals is 

10.14 percent of the best available 

estimate of the current stock size of 907 

animals in the Southern Beaufort Sea 

stock (Bromaghin et al. 2015, Atwood et 

al. 2020) ((92 ÷ 907) × 100 ≈ 10.14), and 

represents a ‘‘small number’’ of polar 

bears of that stock. 

Comment 26: One commenter 

suggested that the Service makes 

inadequate assumptions and 

underestimated the number of polar 

bears that may be taken by Level A and 

Level B harassment during activities 

and that the Service should reconsider 

its small numbers and negligible impact 

determinations. 

Response: The Service’s assumptions 

were reasonable and consistent with the 

MMPA. 

Comment 27: One commenter 

suggested that the percentage (40%) of 

SBS polar bear maternal land dens 

estimated to be exposed to potential 

take by Level B harassment was 

inconsistent with the Service’s small 

numbers determination. 

Response: As is described under 

Evaluation of Effects of Specified 

Activities on Pacific Walruses, Polar 

Bears, and Prey Species, the Service has 

estimated less than 3.2 Level B 

harassment events to denning bears 

each year as a result of the proposed 

activities. This does not represent ‘‘40% 

of all the maternal land dens’’ for the 

SBS stock. 

Comment 28: One commenter 

suggested that the Service should 

account for harassment of undetected 

polar bear maternal dens in their take 

estimates in order to avoid 

underestimating the number of takes for 

the regulation period and affecting the 

Service’s small numbers determination. 

Response: The Service’s analysis 

properly accounts for the anticipated 


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number and potential locations of 

maternal dens and applies reasonable 

assumptions concerning their rate of 

detection. The Service disagrees with 

the notion that it grossly underestimated 

the number of polar bears that will be 

taken under the ITR. 

Comment 29: A commenter suggested 

that the Service should consider 

whether the estimated number of takes 

exceeds the potential biological removal 

for the SBS polar bear stock in order to 

make its negligible impact 

determination and the Service should 

also consider other sources of 

anthropogenic take as part of the 

Service’s baseline to evaluate negligible 

impacts on the SBS polar bear stock 

from oil and gas activities. 

Response: The only take anticipated 

and authorized by the Service from 

AOGA’s specified activities is Level B 

harassment. The Service does not 

anticipate or authorize any taking that 

will impair the survival of any polar 

bears. The Service did not identify any 

mechanism through which impacts 

associated with authorized Level B 

harassment (which are inherently shortterm and limited) could interact with 

impacts from other sources of 

anthropogenic take such that serious 

injury or death could result (nor does 

the commenter establish such 

possibility). 

Comment 30: Commenters suggested 

that the Service should account for take 

by Level A harassment for the duration 

of the 5-year regulation period in order 

to determine whether there would be 

more than a negligible impact. 

Response: The Service evaluated the 

probability of take by Level A 

harassment for each of the 5 years 

covered by this ITR. In determining 

whether the authorized take will have a 

negligible impact on the SBS stock of 

polar bears, the Service applies the 

definition in its implementing 

regulations, which define a negligible 

impact as an impact resulting from the 

specific activities that cannot be 

reasonably expected to, and is not 

reasonably likely to, adversely affect the 

stock through effects on annual rates of 

recruitment or survival. 50 CFR 

18.27(c). Not all Level A harassment 

events affect annual rates of recruitment 

or survival. Hence the distinction 

between serious and non-serious take by 

Level A harassment. The Service 

estimates a 46% probability of take that 

is pertinent to the negligible impact 

standard (i.e., take that results in serious 

injury of mortality). The probability of 

harassing denning bears such that lethal 

take of one or more cubs occurs is 

appropriately assessed on an annual 

basis in order to give effect to the term 

‘‘annual’’ as it appears in these 

regulations. While the Service is always 

concerned with any potential for 

mortality to cubs, it has worked with the 

applicant to integrate numerous 

mitigation measures to further reduce 

the potential for such events, and it does 

not reasonably expect such events to 

affect annual rates of recruitment or 

survival. The Service further notes that 

its approach to applying the ‘‘negligible 

impact’’ standard here is consistent with 

the 1-year duration of any LOAs (which 

actually authorize the incidental take 

pursuant to the framework established 

in the ITR) as well as the manner in 

which the Service applies the 

‘‘negligible impact’’ standard in the 

context of IHAs, which would remain 

available as an alternative approach for 

requesting and authorizing take were 

the Service unable to make the requisite 

determination for this ITR. 

Comment 31: One commenter 

suggested that the Service should clarify 

the explanations for their small numbers 

and negligible impact determinations 

and the consistency of these 

determinations with their regulations. 

Response: The Service reasonably 

applied the relevant statutory and 

regulatory standards and not 

impermissibly relied on any limitations 

not included in the regulations. Further 

clarification of these issues is provided 

in various comment responses. 

Comment 32: One commenter 

suggested that the Service should clarify 

whether take during activities under the 

previous ITR (2016–2021) was included 

in the Service’s baseline to evaluate 

Industry impacts on marine mammals. 

Response: Consistent with the MMPA 

and its implementing regulations, the 

Service makes its ‘‘negligible impact’’ 

on a request-by-request basis. In other 

words, it does not aggregate take 

associated with the current request with 

take associated with prior 

authorizations. That said, the Service’s 

ITR and NEPA analyses do consider the 

current status of the relevant stock or 

species (here, SBS polar bears), to 

include any residual impacts caused by 

prior taking, when rendering its MMPA 

determinations and NEPA conclusions. 

Comment 33: One commenter 

suggested that the Service should clarify 

why they do not anticipate take by Level 

A harassment to occur during Industry 

activities given the 0.46 probability of 

take by Level A harassment of a polar 

bear cub and how the potential for take 

by Level A harassment will impact the 

SBS polar bear stock. 

Response: The Service applied the 

relevant statutory and regulatory terms 

in a reasonable manner and determined 

for the purpose of applying the 

‘‘negligible impact’’ standard that the 

authorized take ‘‘cannot be reasonably 

expected to, and is not reasonably likely 

to’’ adversely affect the SBS stock of 

polar bears through effects on annual 

rates of recruitment or survival. 

Considering annual probability rates is 

the most appropriate way to address the 

applicable regulatory standard, which is 

expressed in annual terms. And the fact 

the zero Level A harassment or lethal 

takes is the most likely result in any 

given year precludes a reasonable 

expectation that such take will, in fact, 

occur. Level A harassment (either nonserious or serious) to bears on the 

surface is extremely rare within the ITR 

region. The Service further notes that 

the mitigative effect of certain measures 

described in AOGA’s request—i.e., 

avoidance of steep slopes and use of 

trained observers to clear potential 

denning areas prior to road 

construction—could not be reliably 

quantified and thus integrated into the 

Service’s modelling analysis, but may 

further reduce the probability of den 

disturbance. 

Comment 34: One commenter 

suggested that the Service should clarify 

how the probability of take of polar 

bears by Level A harassment during 

industry activities will impact the SBS 

polar bear stock from reaching or 

maintaining its optimum sustainable 

population and whether this impact is 

consistent with the Service’s negligible 

impact determination. 

Response: The Service has conducted 

a thorough analysis using detailed 

project descriptions from the applicant 

and quantitative estimates of take 

developed using the best available 

science. As is explained in the proposed 

rule, due to the low (<0.29 for nonserious Level A and ≤0.462 for serious 

take by Level A harassment/lethal takes) 

probability of greater than or equal to 1 

non-serious or serious injury take by 

Level A harassment/lethal take each 

year of the ITR period, combined with 

the median of 0.0 for each, we do not 

estimate the proposed activities will 

result in non-serious or serious injury 

take by Level A harassment or lethal 

take of polar bears. 

Comment 35: One commenter 

suggested that the Service should 

reevaluate its determinations and either 

deny the Request to issue an 

authorization or issue a revised 

proposed ITR after addressing public 

comments before promulgating the ITR. 

Response: The Service disagrees. The 

ITR includes a thorough and robust 

analysis based on detailed descriptions 

from the applicant of specified activities 

and the best available science. The 

Service has found no basis to deny the 


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Request and statutorily ‘‘shall’’ 

authorize incidental take of marine 

mammals for specified activities where 

the requisite MMPA determinations are 

made. There are no significant changes 

to AOGA’s Request, the Service’s 

assumptions, or analysis that would 

require publishing a revised proposed 

ITR. 

Comment 36: Commenters suggested 

that in the EA the Service should 

account for climate change impacts in 

order to assess impacts on polar bears 

and walruses potentially affected by 

Industry activities, and one commenter 

suggested the Service clarify impacts 

from other Industry activities and 

associated risks and cumulative impacts 

beyond the 5-year regulation period. 

Response: The EA appropriately 

focuses on the reasonably foreseeable 

impacts of the Proposed Action, i.e., 

issuing the ITR. The ITR authorizes the 

Level B harassment associated with 

certain oil and gas activities, and does 

not authorize the oil and gas activities 

themselves. That said, the EA analyzes 

reasonably foreseeable impacts in the 

context of an environmental baseline 

that includes climate change-related 

impacts to polar bears and walruses. 

Climate change-related effects were also 

considered in the EA’s analysis of 

cumulative impacts. As is explained in 

the ITR and the EA, the effects of the 

authorized level B harassment are 

inherently limited and temporary and 

are not expected to persist beyond the 

5-year period addressed in the ITR. 

Comment 37: One commenter 

suggested that the Service should 

consider additional factors, such as 

population trends, increased land use, 

and increased potential for human-polar 

bear conflicts, as part of the baseline to 

determine negligible impacts on polar 

bears. 

Response: We agree with the 

commenter that changing sea ice 

conditions have affected and will 

continue to affect polar bears in the SBS 

subpopulation in various ways. We 

disagree, however, that we failed to 

consider these factors or that all of them 

are relevant to estimating potential 

impacts from AOGA’s Request. For 

example, we account for changes in the 

subpopulation’s demographics by using 

the best available science (e.g., Atwood 

et al. 2020) to inform the denning 

impact analysis and for setting the 

potential biological removal level (PBR). 

We also account for changes in the 

spatial distribution of bears (i.e., more 

bears on land) in both our denning 

analysis (i.e., Olson et al. 2017) and 

surface analysis (i.e., Wilson et al. 2017). 

Many of the other factors listed do not 

have published or verified relationships 

with industrial activity, so it’s unclear 

how exactly to incorporate those factors 

into estimating the effects of industrial 

activities on polar bear disturbance 

levels. Even so, this does not mean that 

the effects are not implicitly accounted 

for as most of the studies we rely on to 

parameterize our analysis are based on 

data collected during the period when 

population-level effects of sea ice loss 

have been observed for the SBS (i.e., 

2000 onwards). For example, our case 

study analysis contains a significant 

number of observations from this period 

and should thus reflect any changes on 

how bears respond or are affected by 

disturbance. Similarly, for our analysis 

of surface-level interactions, 

observations come from our LOA 

database in the period 2014–2018, a 

period that reflects the potential for 

increases in encounters between bears 

and humans and modified polar bear 

behavior as a result of potential 

nutritional stress. 

Comment 38: One commenter 

suggested that the Service used an 

outdated and highly criticized 

population estimate for SBS polar bears 

and that the levels of take determined 

for this population likely reflect an 

overestimated percentage of the 

population being impacted by Industry 

activities. 

Response: We do not rely on the 

results of Bromaghin et al. (2015) for 

analysis but rather on Atwood et al. 

(2020). Bromaghin et al. (2015) does not 

apply just to the U.S. portion of the SBS, 

and while Atwood et al. (2020) does, it 

provides evidence that the abundance in 

that area is similar to that found in 

Bromaghin et al. (2015), thus providing 

support for stability in the overall subpopulation estimate and, therefore, 

being no different from that published 

in Bromaghin et al. Without additional 

details on how those estimates are 

biased low, we do not address them, 

and instead rely on the best available 

scientific evidence. Currently, 

Bromaghin et al. (2015) and Atwood et 

al. (2020) represent the best available 

science on the status of the SBS 

subpopulation. 

The Service does not calculate 

‘‘maximum allowable’’ levels of lethal 

take or take by Level A or Level B 

harassment. Instead, the Service bases 

its determinations on the effects of the 

estimated incidental take from the 

activities specified in the Request. Here, 

no lethal take or Level A harassment is 

anticipated to occur or authorized, and 

the Level B harassment that is 

anticipated and authorized meets 

applicable MMPA standards. The 

Service is unaware of any information 

that supports a low bias in the Atwood 

et al. (2020) estimates. 

Comment 39: Commenters suggested 

that the Service’s cautious approach to 

determine take estimations resulted in 

overestimating take of polar bears and 

this overestimation may impact the 

availability of polar bears for 

subsistence harvest, which may lead to 

conflicts between Industry entities and 

subsistence communities. 

Response: The Service disagrees with 

the commenter’s suggestion that the ITR 

inappropriately overestimated take, may 

lead to conflict between industry and 

subsistence communities, and may 

impact the availability of polar bears for 

subsistence harvest. 

Comment 40: One commenter 

suggested that the Service should 

explain how their quantitative 

evaluation of Industry impacts on polar 

bears is valid and address the 

inconsistency with their statement in 

NPR–A that states that quantitative 

evaluation of the potential effects of 

disturbance of polar bears is constrained 

by various factors. 

Response: The Service has worked 

with AOGA to gather the necessary 

information on the nature, location, and 

timing of activities for the quantitative 

analyses presented in the ITR. The 

Service’s polar bear sighting database 

was incorporated into the analyses to 

provide information on abundance, 

distribution, and response of polar bears 

within the ITR area. While no projection 

of effects of future activities is perfect, 

the Service utilized best available 

scientific evidence, to include robust 

and peer-reviewed predictive modeling 

techniques, to perform a comprehensive 

analysis of estimated impacts, and to 

render reasoned determinations. 

Comment 41: Commenters suggested 

that the Service overestimated the 

number of incidental polar bear takes 

and that actual instances of polar bear 

take will be much less over the 5-year 

regulation period, and requested the 

Service clarify whether this 

overestimation of take will affect 

additional Industry entities seeking take 

authorizations. 

Response: We disagree that the 

methodology we use leads to an 

inappropriate overestimate of take. The 

Service has used best available science 

to generate quantitative take estimates 

that represent the total potential take 

that may occur as a result of the 

activities included in the applicant’s 

Request. Under the existing and 

previous ITRs, AOGA was required to 

survey for dens only along ice road and 

tundra travel routes. Therefore, the 

majority of their project area was not 

surveyed for dens, and, consequently, 


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their status was not monitored. While 

additional dens have been observed 

upon emergence, it is clear that without 

dedicated observers across the entire 

project area, it would be impossible to 

observe the vast majority of denning 

bears and their response to potential 

disturbance. This is especially true 

given the limited light conditions 

present during the majority of the 

denning period. Additionally, a large 

portion of the estimated take would not 

be observable to Industry. Rode et al. 

(2018) showed that when bears emerge 

early from dens, there is a survival 

consequence to cubs when subsequent 

observations are made ∼100 days post 

emergence. Thus, the ultimate effects of 

the disturbance would likely not 

manifest themselves until after the bears 

had left the area and are no longer 

observable by industry. With respect to 

the Larson et al. (2020) study, we did 

consider it in our analysis, but the study 

did not consider the well-documented 

differences in responses across different 

denning periods, which we accounted 

for, and it was unclear what periods 

their observations were from. Thus, it 

was unclear what level of bias was 

present in their response data. 

Analyzing the extent—if any—to 

which this ITR may affect the activities 

not described in AOGA’s Request is 

beyond the scope of this analysis. 

Comment 42: One commenter 

suggested that the Service should 

reconsider including intentional takes 

as part of their data to estimate the 

number of incidental takes because their 

inclusion will lead to an overestimation 

of the number of takes by Level B 

harassment anticipated for the 

regulations and ITRs may authorize only 

incidental, but not intentional, take by 

harassment. 

Response: The Service does not 

authorize intentional take under this 

ITR. But as the quoted language 

indicates, the Service did consider data 

concerning expected intentional take 

(i.e., hazing) rates in its analysis of 

incidental take. It did so because 

intentional take events are usually 

preceded by events that qualify as Level 

B harassment, and it is necessary to 

account for such instances of incidental 

take in the larger estimate of incidental 

take rates. In other words, the Service 

used intentional take rates as a proxy for 

the incidental take that generally 

proceeds intentional take (i.e., hazing) 

events. The Service recognizes that not 

all instances of intentional take are 

preceded by incidental take, but does 

not have data sufficient to support 

application of a reliable correction 

factor, and therefore made this 

conservative assumption to help ensure 

that its analysis accounts for all 

incidental take. 

Comment 43: One commenter 

suggested that the Service overestimated 

the probability of take of polar bears by 

Level A harassment during Industry 

activities because the Service does not 

account for habituation of polar bears to 

Industry activities, adaptive mitigation 

measures, and the variability of received 

stimuli within a polar bear den. 

Response: We disagree with the 

suggestion that bears choosing to den 

near industrial infrastructure and 

activities can be assumed to be 

indifferent to human activity. In fact, in 

our review of case studies, we found 

numerous instances of bears denning 

adjacent to industrial activities that 

exhibited disturbance indicative of 

harassment. We agree that stimuli 

received by bears in dens is highly 

variable, as shown in Owen et al. (2020). 

However, just because a bear detects a 

signal (as was the scope of Owen et al. 

2020) doesn’t indicate whether it is 

likely to respond to that stimuli. Thus, 

it is not possible to use the data from 

Owen et al. (2020) to estimate more 

refined distances at which bears react to 

different types of activities while 

denning. Even Owen et al. (2020) 

acknowledges that a 1-mile no 

disturbance buffer is still supported by 

their research. There is currently no 

study that establishes a curve 

establishing a relationship between the 

distance to a potential source of 

disturbance and the probability that it 

leads to disturbance. Therefore, we used 

the best available information to 

develop response rates of bears within 

1-mile of potential exposures. Those 

response rates incorporate bears that 

never perceived the activity and 

therefore never responded, those that 

perceived the activity but never 

responded, and those that perceived the 

activity and responded. We then 

applied these responses to dens within 

1 mile of an activity to determine 

potential disturbances. 

Comment 44: One commenter 

suggested that the Service should clarify 

how the estimated number of takes will 

be evaluated to determine LOA issuance 

under these regulations. 

Response: The Service will issue 

LOAs in the manner described in its 

implementing regulations at 50 CFR 

18.27(f). The Service does not intend to 

conduct predictive modeling of the 

potential effects of the activities 

described in each request for an LOA. 

Nor does the Service intend to prosecute 

recipients of LOAs for unauthorized 

take that is suggested by modeling but 

not supported by observations or any 

other evidence. 

Comment 45: One commenter 

suggested that the Service should 

consider that the SBS polar bear 

abundance estimate upon which the 

Service based its small numbers and 

negligible impact determinations is 

biased low. 

Response: Bromaghin et al. (2015) 

does not apply just to the U.S. portion 

of the SBS and while Atwood et al. 

(2020) does, it provides evidence that 

the abundance in that area is similar to 

that found in Bromaghin et al. (2015), 

thus providing support for stability in 

the overall sub-population estimate and, 

therefore, being no different from that 

published in Bromaghin et al. Currently 

Bromaghin et al. (2015) and Atwood et 

al. (2020) represent the best available 

science on the status of the SBS 

subpopulation. 

Comment 46: One commenter 

suggested that the Service should clarify 

why they used the cited SBS polar bear 

population estimate for their EA and 

ITR and discuss whether more recent 

polar bear population abundance data 

exist. 

Response: The Service used the most 

current reliable population estimates of 

SBS polar bears in both its ITR and 

NEPA analyses. This was not 

Bromaghin et al. (2015) but rather 

Atwood et al. (2020). In their 

assessment, Atwood et al. (2020) did not 

find any significant differences in the 

size of the subpopulation between the 

two studies. The Atwood et al. (2020) 

study updated Bromaghin et al. (2015) 

but included additional years of data 

(through 2016) to provide a population 

estimate for the year 2015. Based on its 

ongoing monitoring of studies, 

observation reports, and related 

information, the Service believes these 

estimates continue to reflect a reliable 

estimate of the current population. In 

other words, the Service is not aware of 

any reliable information suggesting that 

the SBS population of polar bears has 

significantly declined over the last 6 

years such that the 2015 estimate is 

unreliable, nor has such information 

been submitted through the public 

comment process. The population 

estimate published in Atwood et al. 

(2020) is currently the best available 

information for the status of the SBS 

subpopulation. The Service disagrees 

with the commenter’s unsupported 

assertion that there is a ‘‘dearth’’ of 

abundance data and a ‘‘great deal of 

uncertainty in estimating population 

numbers.’’ 

Comment 47: One commenter 

suggested that the Service should 

address how polar bears are impacted 

by reduced access to their prey as a 

result of Industry activities and how this 


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factor was evaluated during take 

estimations. 

Response: The availability of prey was 

considered in the environmental 

baseline that informed the Service’s 

analysis of potential effects of AOGA’s 

specified activities and issuing the ITR. 

The Service does not foresee Level B 

harassment appreciably reducing polar 

bears’ access to prey. 

Comment 48: One commenter 

suggested that the Service should clarify 

how serious take by Level A harassment 

and lethal take were determined in their 

take estimates. 

Response: While the probabilities of 

serious take by Level A harassment and 

Lethal takes were separated in Table 7, 

when summarizing model results in 

Table 8 these values were reported as a 

combined result. All necessary MMPA 

determinations were made using take 

estimates that combined serious take by 

Level A harassment and lethal take into 

the same general category. 

Comment 49: One commenter 

suggested that the Service should clarify 

the explanation for take by Level A 

harassment and lethal take probabilities. 

Response: As is stated in the ITR, the 

Service does not estimate the proposed 

activities will result in non-serious or 

serious injury take by Level A 

harassment or lethal take due to the low 

(<0.29 for non-serious take by Level A 

harassment and ≤0.462 for serious take 

by Level A harassment/lethal takes) 

probability of greater than or equal to 1 

non-serious or serious injury Level A 

harassment/lethal take each year of the 

ITR period, and a median of 0.0 for 

each. 

Comment 50: Paragraph 1 under the 

heading ‘‘Level A Harassment’’ states: 

Level A harassment to bears on the 

surface is extremely rare within the ITR 

region. From 2012 through 2018, one 

instance of Level A harassment occurred 

within the ITR region associated with 

defense of human life while engaged in 

non-Industry activity. This statement 

and its context are unclear, and we 

suggest clarifying in the final rule. 

Response: The referenced instance of 

Level A harassment represented an 

intentional take. This ITR process 

authorizes only incidental Level B 

harassment. We do not find that further 

clarification is warranted. 

Analysis 

Comment 51: One commenter 

suggested that the Service should 

systematically collect data on polar bear 

dens rather than using opportunistic 

data to assess impacts. 

Response: Consistent with is 

regulations implementing the MMPA, 

the Service reviewed AOGA’s Request 

using the ‘‘best available scientific 

evidence.’’ See 50 CFR 18.27(d)(3). The 

Service finds that the monitoring and 

reporting requirements specified in the 

ITR are sufficient. The Service will 

continue to evaluate opportunities for 

enhanced data collection but the extent 

to which the Service itself should 

engage in more systematic data 

collection is beyond the scope of this 

analysis. 

Comment 52: One commenter 

suggested that the Service should 

reevaluate the assumption to estimate 

take by Level A harassment for denning 

polar bears. 

Response: As was explained in the 

proposed ITR, the Service employed a 

set of reasonable assumptions derived 

from the best available scientific 

evidence to analyze what would happen 

if denning bears were disturbed by 

AOGA’s specified activities. 

Comment 53: One commenter 

suggested that the Service should 

account for the increased risk of 

predation on polar bear cubs after den 

emergence as part of the Service’s 

impact assessment for polar bears. 

Response: We disagree. We know of 

no instance or circumstance where a 

cub, recently leaving the den regardless 

of circumstances, would be able to 

successfully resist a predation attack. 

The only likely predators of young cubs 

in this environment at this time are 

other polar bears, wolves, or other large 

carnivores. Cubs at this age rely on their 

mothers for protection from predation. 

Comment 54: One commenter 

suggested that the Service should 

account for the potential lethal take of 

a polar bear as a result of a defense of 

human life during a human-polar bear 

encounter in the Service’s negligible 

impact determination. 

Response: Under Section 101(a)(5)(A) 

of the MMPA, negligible impact 

determinations consider the effect of the 

specified activities and the incidental 

take to be authorized, and not the effects 

of intentional take described by the 

commenter. Defense of human life takes 

are authorized under a separate 

provision of the Act. 

Comment 55: One commenter 

suggested that the Service should 

reevaluate Industry impacts on denning 

polar bears. 

Response: The Service has conducted 

a thorough and robust analysis based on 

detailed descriptions from the applicant 

of activities occurring within the 

specified geographical region and the 

best available science. All activities 

within the ITR region that have the 

potential to impact denning polar bears 

have been included in this analysis. 

Comment 56: One commenter 

suggested that the Service should 

consider that estimating the number of 

polar bear dens for this ITR using 

historic observations may lead to 

underestimation due to the increased 

land use reported for the SBS polar bear 

stock. 

Response: The analysis does take into 

account the potential for >52 dens to 

occur in the region. As stated in the text 

of the document detailing the den 

simulations (pp. 86 FR 29407–29408, 

June 1, 2021), we use statistical 

distributions for each region in the ITR 

(i.e., NPR–A, Colville to Canning, the 

1002 area) to simulate a number of dens 

in each region during each iteration of 

the model. Based on how these 

distributions were parameterized, it is 

possible to have up to ∼102 dens 

simulated during any given iteration of 

the model. That is the sum of the upper 

95% CI for each of the three regions 

where dens were simulated. 

Additionally, the data used in the den 

simulation portion of the model uses the 

best available information derived from 

the most up-to-date den catalogue 

published by Durner et al. (2020). Olson 

et al. (2017) shows that in the period 

2007–2013 55% of dens occurred on 

land, and this did not differ from the 

period of 1996–2006 (i.e., 54.5%). So, 

our results are consistent with these 

studies, based on the most recent data, 

and reflective of what we expect to 

occur during the five-year period of this 

ITR. 

Comment 57: One commenter 

suggested that the Service should 

consider the energetic costs of denning 

female polar bears relocating to 

alternative den sites and the associated 

impacts of these energetic costs on the 

survival for both mother polar bears and 

their cubs. 

Response: While we agree with the 

commenter that these types of 

relationships are conceivable, we are 

unaware of any research to support or 

document these claims. Further, these 

statements are just conjectures, and it’s 

equally feasible that females have 

sufficient energetic reserves to find a 

new den site given that they already 

spend energy scouting for ideal den 

sites. We are therefore required to use 

the currently best-available information, 

which indicates minimal impacts to 

denning females if forced to find a new 

den site after being disturbed. 

Comment 58: One commenter 

suggested that the Service should 

consider whether the number of cubs 

affected by premature den departure is 

underestimated. 

Response: We disagree with the 

notion that we have underestimated 


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such impacts. We use the best available 

science to address this question. While 

we agree that there are likely local 

factors at a den site that could play a 

role in triggering when bears decide to 

depart the den site, those relationships 

have not been established, nor would 

there be any way to project those 

conditions to all future denning bears. 

We use real-world data on den 

emergence dates and time spent at the 

den site post-emergence but prior to 

permanently departing the area. These 

observations already contain natural 

variation in the timing of these events, 

possibly based on the local conditions 

or the specific attributes of denning 

females (e.g., nutritional condition). 

Thus, drawing from these distributions 

should allow for the level of natural 

variation to be accounted for in the 

analysis. While it’s true a larger sample 

size would always be better, polar bears 

are difficult to study and we must 

therefore use what we have available. It 

is also worth mentioning that the 

sample sizes are not so small as to be 

unreliable. In fact they were deemed 

sufficient for inclusion into multiple 

peer-reviewed studies (e.g., Rode et al. 

2014, Smith et al. 2007). 

Comment 59: One commenter 

suggested that the Service should 

consider the potential impacts of take by 

Level A harassment that may result from 

a mother abandoning her cubs in 

response to disturbance. 

Response: The dataset that was used 

to analyze potential take from surface 

interactions encompassed all recorded 

human-polar bear interactions 

throughout the year, including the 

months when sows are moving toward 

the sea ice with cubs of the year. There 

are no recorded interactions in the 

2014–2018 dataset between Industry 

and these bears that resulted in Level A 

harassment. The Service has also 

accounted for these potential 

interactions when establishing 

mitigation measures. Under the 

mitigation measures established in the 

proposed rule, Industry must survey for 

maternal polar bear dens, create 

exclusion zones around known dens, 

and report all polar bear interactions 

(including those with sows and cubs) to 

the Service within 48 hours of the event. 

Comment 60: One commenter 

suggested that the Service should 

consider the most recent evidence of 

cub survival and recruitment in the SBS 

polar bear population as part of their 

baseline to assess impacts to SBS polar 

bears. 

Response: We agree with the 

commenter that over the past ∼20 years, 

cub-of-the-year survival in the SBS has 

been low relative to other 

subpopulations and is the primary 

driver of concomitant decreases in 

abundance. Survival was especially low 

in the period 2004–2008 (mean = ∼0.24), 

a period of marked population decline, 

but was relatively higher in the period 

2009–2014 (mean = 0.50), the last year 

for which estimates are available 

(Atwood et al. 2020). 

Comment 61: One commenter 

suggested that the Service should clarify 

the explanation for distinguishing lethal 

take of polar bear cubs if cubs are 

abandoned before 60 days of age and 

serious take by Level A harassment of 

cubs if cubs are abandoned after 60 of 

age. 

Response: We disagree with the 

commenter that our different treatment 

of cubs emerging early during the early 

vs. late denning periods is 

inappropriate. We used 60 days based 

on published literature indicating that 

cubs have developed the basic functions 

to survive outside of the den by the time 

they reach ∼2 months (60 days) of age. 

Prior to 60 days, the literature indicates 

that survival of cubs outside of the den 

is not possible. Serious Level A 

harassment is harassment that is likely 

to result in mortality. Based on the 

results of Rode et al. (2018), we know 

that early emergence from the den can 

lead to survival consequences for cubs. 

However, it is clear from the results of 

Rode et al. (2018) that not all cubs die 

as a result of early emergence (assuming 

they are >60 days old), thus, there is a 

different outcome to cubs emerging 

early during the early denning vs. the 

late denning periods. Hence, we treated 

early emergence during the late denning 

period as a serious Level A harassment 

because of the potential for a lethal 

outcome and lethal take for early 

emergence during the early denning 

period because of nearly 100% 

probability of cubs dying then. 

Comment 62: One commenter 

suggested that the Service should use 

systematically collected survey data that 

has been peer-reviewed in order to 

evaluate disturbance impacts to denning 

polar bears during Industry activities 

rather than use opportunistic 

observations of polar bear disturbance 

during Industry activities. 

Response: The case studies include 

published literature and reports of 

observations made by Industry and 

research and provided to USFWS. The 

published literature includes peerreviewed literature, including literature 

by Amstrup (1993), which states that 

‘‘10 of 12 polar bears tolerated exposure 

to exceptional levels of activity’’ and 

‘‘most bears in this study showed 

substantial tolerance to activity.’’ They 

also state ‘‘. . . live capture and 

marking were probably more disruptive 

to bears than other possible 

perturbations. Yet recruitment of cubs 

through the time of emergence from the 

den and sizes of cubs were not 

affected.’’ In our analysis, we utilized 

the best available information, which 

included internal reports and 

observations, as well as peer-reviewed 

literature (e.g., Amstrup 1993). Thus, we 

used past reports to inform our findings, 

but the reports alone did not provide the 

basis for our findings as noted in the 

‘‘Info Source’’ column of the AOGA 

ITR—Case Studies Summary Table— 

061621, document ID FWS–R7–ES– 

2021–0037–0011. 

Comment 63: One commenter 

suggested that the Service should clarify 

the explanation for not classifying 

disturbance during early denning that 

did not result in den abandonment as 

take by Level A harassment. 

Response: The early denning period 

begins with the birth of cubs and ends 

60 days after birth. Because cubs cannot 

survive outside the den prior to 

reaching 60 days of age, any exposure 

during early denning that resulted in an 

emergence was classified as lethal take. 

Of the 10 cases in the repeated-exposure 

category that occurred during the late 

denning period, 2 resulted in cub 

mortality; in the other 8 cases, 

exposures did not result in 

emergences—the bears remained in 

their dens until after 13 February, the 

date that marked the end of the early 

denning period in cases where cub age 

was not known. Although possible, no 

studies have clearly demonstrated latent 

effects of disturbance on denning bears 

that did not respond to the disturbance 

in observable manners. In these eight 

cases, negative response (e.g., early 

emergence) were not observed during 

early denning. The purpose of 

evaluating these case studies was to 

inform the probabilities of responses to 

exposures during different periods. In 

this case, simulated dens that were 

exposed to repeated exposures before 

cubs reached 60 days of age had a 20% 

probability, on average, of resulting in 

cub mortality and an 80% probability of 

remaining in the den until the beginning 

of the late denning period. 

Comment 64: One commenter 

suggested that the Service should clarify 

their explanation for the dates assigned 

to the early denning period. 

Response: We used the best available 

information to inform average 

parturition date of 15 December. 

Messier et al. (1994) concluded that a 

majority of births occurred before or 

around 15 December as indicated by the 

drop in activity levels of instrumented 

females. 


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Comment 65: One commenter 

suggested that the Service should collect 

more extensive followup information on 

polar bear den disturbance case studies 

in order to determine whether cubs 

survived a den disturbance event. 

Response: For most of the case 

studies, we had documentation of only 

the immediate outcome of the exposure 

to a disturbance, which was sufficient 

for determining the immediate outcome. 

For most cases, there is no 

documentation of the outcome of the 

cubs beyond the immediate timeframe 

of the disturbance. We used the best 

available information, and it would not 

be appropriate to assume an outcome in 

the absence of information. 

Comment 66: Several commenters 

suggested that the Service did not 

adequately consider the possibility of 

lethal take or serious injury take by 

Level A harassment arising from direct 

contact of a vehicle with a den and 

varying reactions of denning animals to 

vehicles in close proximity. 

Response: We do not use only Smith 

et al. (2020) for estimates of AIR 

efficacy, but rather we include the 

results from Smith et al. (2020) and 

Amstrup et al. (2004) in our analysis, as 

well as a new study on artificial dens 

(Woodruff and Wilson 2021). We do 

take into account potential disturbance 

from ground noise and vibrations from 

drill and exploration in the form of our 

disturbance probabilities derived from 

our review of relevant case studies. 

While it is true that Amstrup et al. 

(2004) suggest helicopters may have 

higher detection rates than fixed-wing 

aircraft, the average detection rates from 

Amstrup et al. (2004) do not differ 

significantly from results obtained with 

a fixed-wing aircraft (Smith et al. 2020) 

when accounting for the proportion of 

dens that are unlikely to be available for 

detection given snow depth. 

Additionally, AOGA proposed using 

only fixed-wing aircraft, so that is what 

we considered in our analysis. The EA 

serves to assess the impacts of the 

Federal action of issuing the ITR. The 

ITR does not authorize the specified 

activities; therefore, the EA focuses its 

discussion on the effects of takes to be 

authorized pursuant to the ITR. The 

impacts from the activities themselves 

could proceed without MMPA coverage 

at the discretion of the applicant and are 

not effects of the Proposed Action, but 

were nevertheless considered as part of 

the environmental baseline and in the 

cumulative impacts analysis. 

Based on the output of the den 

disturbance analysis, we estimated the 

number of dens and probability of ≥1 

den being run over by equipment used 

while driving off established roads in 

the project area. Because it is possible 

to run over dens only when driving off 

established roads, we restricted our 

analysis to only those simulated dens 

that occurred adjacent to proposed ice 

roads, tundra travel routes, and seismic 

grids. Because the applicant did not 

specify how seismic grids would be laid 

out, we followed a similar approach as 

Wilson and Durner (2020) and 

simulated seismic grids across the highand low-density seismic areas (Fig. 7). 

We simulated E–W and N–S seismic 

track lines, each separated by 201.2 m 

(660 ft). We assumed vehicles traveling 

seismic grids, ice roads, and tundra 

travel routes would have a width of 3.4 

m (11.2 ft; Wilson and Durner 2020). 

For each iteration of the model, we 

determined which dens occurred within 

the footprint (i.e., 3.4 m) of the different 

movement paths. We then determined if 

dens had been identified by AIR 

surveys. If a den was identified on an 

AIR survey, we excluded it from further 

analysis. Lastly, we restricted the set of 

dens available to be run over to those 

that did not previously have a take by 

Level A harassment or lethal take 

assigned to it during the early or late 

denning periods. That is, those dens 

that did not previously respond to 

disturbance and, therefore, would be 

vulnerable to being run over by 

equipment. We did not consider the 

potential for running over dens during 

the den establishment period or postemergence period because during both 

of these periods bears are known to be 

on the surface and would likely be 

visible to operators and the bears would 

be able to readily detect the potential 

risk of the vehicles and respond 

appropriately. 

Our approach for estimating the 

number of dens potentially run over by 

equipment can be considered 

conservative because it does not account 

for the fact that operators have stated 

they will avoid crossing denning habitat 

whenever possible, which would further 

reduce the probability of running over a 

den. Similarly, the seismic grids we 

simulated likely cover a greater area 

than a normal seismic layout, but 

because information was not provided 

by the applicant, we used the more 

liberal layout. 

We found that the probability of 

running over a den is exceedingly low 

each year of the ITR. The probability of 

running over ≥1 den each winter ranged 

from 0.0041 to 0.0059. This makes sense 

given the existing mitigation measures 

analyzed take some dens off the table 

because they are found prior to the 

commencement of activities that could 

run over them. Additionally, the actual 

footprint of vehicles is very small 

compared to the scale of the project 

area, thus, there is a very low risk to 

begin with that a den would even 

overlap a vehicle’s footprint on the 

landscape. 

When additional mitigation measures 

proposed by the applicant are 

considered, including the avoidance of 

steep terrain and the training of 

personnel for identifying den site 

characteristics, which cannot be 

quantified, the Service determined that 

the probability of running over a den 

was sufficiently small so that it could be 

dismissed and therefore was not 

included in this ITR. 

Comment 67: One commenter 

suggested that the Service should use 

randomized case studies for their polar 

bear denning analysis. 

Response: It is not clear exactly what 

the commenter means by the ‘‘case 

studies used for the case studies are not 

randomized.’’ There was no way to use 

‘‘randomized’’ data in this case. The use 

of randomized data in this case would 

require conducting a study by radiocollaring denning females and then 

observing their response to any den 

disturbance. This runs the risk of 

substantial disturbance in both the 

capture and collaring (see Amstrup 

1993, Lunn et al. 2004) and the 

observation (see Smith et al. 2007, 2010, 

2013; Robinson 2014). Instead we relied 

on the case studies, the best available 

information, to inform our model and 

take probabilities. 

Comment 68: One commenter 

suggested that the Service should 

reevaluate the most recent scientific 

evidence on the number of land-based 

dens for the SBS polar bear stock to 

avoid underestimating the number of 

dens used for the denning analysis. 

Response: We are not sure what leads 

the commenter to believe that the 

results of Atwood et al. (2020) are an 

underestimate of the number of dens on 

shore. Atwood et al. (2020) represents 

the best available science and updates 

the approach developed by Wilson and 

Durner (2020) to incorporate newer data 

that was not available for Wilson and 

Durner (2020) and which does a better 

job incorporating uncertainty into the 

parameters used in the approach. The 

reason Atwood et al. (2020) is used over 

Wilson and Durner (2020) is two-fold. 

First, an updated den catalogue (i.e., 

Durner et al. 2020) wasn’t available 

when Wilson and Durner (2020) 

conducted their analysis. This new set 

of dens is the primary reason that the 

estimate from Atwood et al. differs from 

Wilson and Durner. Second, multiple 

public comments on the analysis of 

Wilson and Durner noted that 

uncertainty in underlying parameters 


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were not adequately accounted for. 

Atwood et al. (2020) overcame this 

problem to present a more robust 

estimate. We agree with the commenter 

that, in the long term, land-based 

denning is likely to increase due to loss 

of sea ice. However, the most recent 

study of land-based denning in the SBS, 

Olson et al. (2017) found that rates of 

land-based denning have been constant 

(i.e., not statistically different) between 

the periods 1996–2006 and 2007–2013. 

Given that the lowest sea ice minimum 

extent was observed in 2012, it’s 

unlikely that there has been a significant 

increase in land-based denning since 

the data used in Olson et al. (2017). 

Comment 69: One commenter 

suggested the Service should consider 

including more recent years of denning 

data in their denning analysis in order 

to account for the increased number of 

land-based dens. 

Response: Atwood et al. (2020) are 

clear about their methods and what data 

they used to calculate the 54% of dens 

occurring on land. This estimate 

conforms to those found in Olson et al. 

(2017), which is the most recently 

published study on the percent of SBS 

bears denning on land. Olson et al. 

(2017) found that on average, in the 

period 1996–2006, 54% of bears in the 

SBS denned on land, and in the period 

2007–2013, 55% denned on land. Thus, 

these data nearly perfectly conform to 

the values used by Atwood et al. (2020; 

which also included uncertainty around 

those estimates). The reason Atwood 

only used data through 2015 is because 

that is the last year when bears received 

GPS collars, which are required to 

obtain an unbiased estimate of the 

distribution of denning. The graph the 

commenters present in their letter is not 

an accurate way to represent the data in 

the den catalogue. While it’s true that 

there are additional years of dens in the 

den catalogue, beyond 2015 they are 

based on firsthand observations, which 

are going to show a positive bias 

towards land-based dens given that 

limited search effort is conducted 

offshore. Thus, the best available data 

are used by Atwood et al. 2020, and the 

approach used by the commenters is 

likely biased high and not a proper way 

to summarize the data. 

Comment 70: One commenter 

suggested that the Service should clarify 

their methods for accounting for the 

variation and uncertainty in their polar 

bear population estimate and the 

interannual variation in the number of 

denning female polar bears that was 

used in the denning analysis. 

Response: We agree that Wilson and 

Durner (2020) failed to account for 

uncertainty associated with many of the 

underlying parameters used to estimate 

the number of dens on shore. That is 

why we relied on the estimate provided 

by Atwood et al. (2020) that does 

account for that uncertainty. The 

uncertainty accounted for by Atwood et 

al. (2020) incorporates annual 

variability in environmental conditions, 

which could lead to differences in the 

use of land. So, the Atwood et al. (2020) 

methods and results are robust to the 

issues presented by the commenter. 

Comment 71: One commenter 

suggested that the Service should 

consider accounting for the number of 

dens containing females without cubs 

and reevaluating the den emergence 

date to include only successful dens in 

order to not underestimate the number 

of takes for denning polar bears. 

Response: We disagree that the model 

does not account for dens with only a 

female bear. In fact we provide some 

probability (∼7%) for a den to have 0 

cubs. So, we do account for the 

probability of a female emerging 

without cubs. As for the incorrect skew 

of emergence dates, we again disagree 

with the commenter. We use den 

emergence data from Rode et al. 2018 

and restrict the data to only those that 

were in the den for a sufficient amount 

of time to indicate the den was more 

than a shelter den. Additionally, even 

though Rode et al. identify some of the 

dens as not being observed with cubs 

∼100 days after emergence, it does not 

indicate that the dens were 

unsuccessful, only that they were later 

observed without cubs. Cubs could 

easily have been lost between 

emergence and subsequent reobservation. There is currently no way 

to know if a bear emerged without a 

cub. If those data were available, we 

would include them, but they don’t 

exist. 

Comment 72: One commenter 

suggested that the Service’s denning 

analysis using the Wilson and Durner 

(2020) model framework does not 

accurately predict impacts to denning 

polar bears throughout the geographic 

scope for project activities and the 

model does not account for uncertainty 

in the timing and location of Industry 

activities that may impact denning polar 

bears. 

Response: We disagree with the 

commenter that the general framework 

provided by Wilson and Durner (2020) 

is not suitable for use in this ITR. The 

approach developed by Wilson and 

Durner (2020) provides a general 

framework for how to incorporate 

different sources of information (as well 

as associated uncertainty) to analyze 

how different types of activity and 

infrastructure might affect denning 

polar bears. The specific model 

discussed in Wilson and Durner (2020) 

has been significantly modified to 

account for the proposed activities in 

this Request as well as additional 

sources of information (e.g., different 

denning periods) to increase the realism 

of the model. While it is true that 

Wilson and Durner (2020) only used the 

model to analyze impacts to polar bears 

over a smaller activity area, with one 

type of industrial activity, the model we 

published as part of this ITR clearly 

shows that it is capable of being applied 

to a larger area and suite of activities. 

We also disagree that the ITR does not 

provide reliable information on where 

and when activities will occur. Both the 

code and objects associated with the 

den disturbance model and the 

associated shapefiles published with the 

proposed ITR provide both spatial and 

temporal information on when/where 

activities will occur. In instances where 

specific dates or areas were unknown 

(e.g., seismic surveys), we accounted for 

that uncertainty by analyzing the 

seismic to occur in the ‘‘worst’’ place 

possible for polar bears (within the 

range provided by AOGA in their 

Request) as well as accounting for 

variability in the timing of activity 

within prescribed bounds. We also 

disagree with the commenter that the 

Service did not account for the 

possibility of a larger seismic survey. 

This is not true. We clearly state on page 

29410 of the Federal Register 

publication of the Proposed ITR that 

during any given winter, the areas 

surveyed would be <766 km2 and 

<1,183 km2 in the areas identified as 

‘‘relatively high’’ and ‘‘relatively low’’ 

den probabilities, respectively. 

Comment 73: Commenters suggested 

that the Service should reevaluate their 

take determination for early den 

departures as potentially lethal take for 

polar bear cubs. 

Response: We do allow for potential 

survival consequence from early 

emergence. In fact, if a den is disturbed 

that leads to early emergence, cubs are 

always given a serious take by Level A 

harassment. There are currently no data 

to support that an early departure from 

the den itself leads to reduced survival. 

That would take a similar-type analysis 

that Rode et al. (2018) conducted. While 

we agree cubs have been observed being 

killed by conspecifics and other 

predators after leaving the den site, 

there is currently no linkage with time 

spent at the den post-emergence and 

pre-departure. 

Comment 74: One commenter 

suggested that the Service should clarify 

their explanation for how non-serious 

take by Level A harassment was 


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accounted for in the Service’s take 

determinations. 

Response: Table 8 shows the 

breakdown of estimated take by the 

level of take. We provided this table so 

readers could see the relative 

differences. As is discussed in the 

description of take by Level A 

harassment within the proposed rule, 

Level A harassment (either non-serious 

or serious) to bears on the surface is 

extremely rare within the ITR region, 

and no Level A harassment to Pacific 

walruses has been reported in the 

Beaufort Sea ITR region. Thus, the best 

available information does not support 

Level A harassment to occur due to 

surface interactions for polar bears, or in 

general for walrus given the proposed 

activities. 

Comment 75: One commenter 

suggested that the Service should 

consider the probability of take by Level 

A harassment for polar bear adult 

females during a den disturbance event. 

Response: We disagree that there is a 

significant probability of an adult 

female experiencing Level A harassment 

due to disturbance at the den site. 

During our review of case studies, we 

observed no examples where an adult 

female experienced any sort of 

harassment that had the potential to 

injure her. There are also no examples 

that we are aware of in the literature. 

Whereas disruptions to the normal 

timing of den phenology have clearly 

published negative relationships to cub 

survival, no such relationships exist for 

adult females. 

Comment 76: One commenter 

suggested that the Service should clarify 

their explanation for the impact sources 

assessed in the denning analysis and 

whether take by Level A harassment and 

lethal take are underestimated. 

Response: We disagree that our use of 

disturbance probabilities from the 

‘‘repeated’’ set of probabilities is 

inappropriate. During our review of case 

studies used to estimate these 

probabilities, the types of activity 

classified as ‘‘repeated’’ are analogous to 

those expected from seismic surveys. 

The commenter’s assessment that any 

activity ‘‘will experience the 

disturbance first as a discrete event’’ is 

inaccurate. For the case studies we 

reviewed, the same (inaccurate) 

argument could be made, but as a result 

the probabilities in the repeated 

category inherently incorporate that first 

exposure and its potential to cause 

disturbance. Based on our definition of 

what constituted repeated exposure, and 

therefore whether a case study was 

classified as repeated/discrete, it would 

be inappropriate to apply the discrete 

probabilities to seismic given the 

unquestionable repeated nature of those 

activities. We should also note that 

depending on a simulated den’s 

phenology and the proposed dates of 

seismic activity, dens could have 

disturbance applied multiple times (if 

previous exposures did not result in 

lethal take or take by Level A 

harassment response). 

We also disagree with the commenter 

that our decisions on how case studies 

were classified was arbitrary. We 

developed clear rules based on a large 

body of scientific literature to help 

classify whether a response to an 

exposure was larger than expected 

under unexposed conditions. Similarly, 

we did not ‘‘arbitrarily’’ decide when to 

exclude case studies from consideration. 

A significant amount of deliberation 

went into the assessment of each case 

study, and only two factors would 

disqualify a case study from being 

included in the final probability 

calculations: (1) There was insufficient 

information to identify when 

disturbance occurred or what the 

outcome was to the den under 

consideration, or (2) the type of activity 

was deemed to be outside of the 

activities proposed by AOGA (e.g., 

physical capture of polar bears in dens). 

We disagree with the commenter’s 

assessment that the Service was overly 

arbitrary in how the different case 

studies were summarized. They cite our 

assessment of case study 47 as an 

example of there being sufficient 

information but the Service classifying 

it as ’insufficient information’. The 

reality is, this case study did not 

provide information on how far the 

crews were from the den, nor the date 

that the bears emerged from the den. 

Given our published criteria, we 

couldn’t reliably assign take to this case. 

We agree that take was certainly 

possible, but insufficient information 

precluded us from coming to that 

conclusion. 

The commenter highlights case study 

7 as another example. Yet, there were 

clear reasons we didn’t include this case 

study. First, it was unclear whether the 

‘‘hunter’’ identified in the case study 

actually observed the same bear as 

Amstrup did given the time lapse 

between observations. That would be 

another explanation for why there were 

no cubs observed. Thus, there was 

incomplete information to fully assess 

this case study. We disagree with the 

commenter that it is inappropriate to 

assume that once a Level A harassment 

or lethal take occurs that subsequent 

harassment/take is not considered. This 

really applies to only one period, the 

late denning period, because lethal take/ 

take by Level A harassment is not 

possible in the den establishment 

period; the only disturbance outcome 

during the early denning period is 

‘‘lethal’’ thus future take/harassment is 

not possible, and during the postemergence period, any additional take is 

accounted for in the surface analysis 

(i.e., not the denning analysis). During 

the late denning period, we believe it is 

appropriate to not consider additional 

harassment/take if Level A harassment 

is simulated to occur. In the late 

denning period, Level A harassment is 

considered serious take by Level A 

harassment, thus it already assumes a 

likely lethal outcome. Thus, applying 

additional lethal take when it has 

already been accounted for is not 

appropriate. 

Comment 77: One commenter 

suggested that the Service should 

consider the size of cubs, which may 

indicate poor body condition and lower 

survival likelihood, as factors to 

determine take for den disturbance 

events. 

Response: The commenter outlines 

some well-established ecological 

relationships (e.g., cub size and 

survival, sea ice and body condition), 

but fails to understand the purpose of 

the case study analysis, the underlying 

assumptions, and how the results are 

utilized in the simulation model. The 

case study analysis was used to estimate 

the probability of a disturbance eliciting 

a specific response during each denning 

period; we then used those probabilities 

in the model to determine how 

simulated dens would respond to 

disturbances at specific times. For 

example, from the case study analysis, 

we found that dens exposed to a 

discrete exposure during the late 

denning period resulted in early 

emergences 90.9% of the time. 

Consequently, in the simulation model, 

dens exposed to a discrete exposure 

between the time cubs were 60 day old 

and their intended emergence date had 

a 90.9% chance, on average, of emerging 

early. Because the best available science 

indicates that early emergences are 

associated with decreased cub survival 

(e.g., Rode et al. 2018), we classified 

those dens as incurring serious take by 

Level A harassment. The commenter 

argues that cubs today are smaller than 

in the past because of environmental 

changes and are therefore more likely to 

be impacted negatively by early 

emergences and departures. Although 

that assertion may be correct, no studies 

have demonstrated that cub size 

influences when a disturbance elicits an 

early emergence, and no studies have 

evaluated the relationship between cub 

size at emergence and survival 

probability in a manner that would 


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allow us to refine our treatment of early 

emergences (e.g., separating those that 

ultimately resulted in mortality from 

those that did not). See below for our 

response to the ‘‘known outcomes’’ 

statement. 

Comment 78: One commenter 

suggested that the Service should 

consider followup information from den 

case studies and reevaluate take 

determinations based on latent effects of 

den disturbance to polar bear cubs. 

Response: The commenter does not 

indicate which cases they consider to 

have ‘‘known outcomes’’ or ‘‘followup,’’ 

so we cannot address those directly. We 

are also unclear about which cases 

correspond to claims about observer 

opinion on cub size and survival. For 

example, the commenter states that 

‘‘observers thought the cub of another 

female was too small to survive,’’ and 

the outcome for this case was an 

observed behavioral response. This 

statement seems to correspond with a 

case where the final outcome was 

‘insufficient information’ and was not 

used in calculating the response 

probabilities. It is possible that the cases 

the commenter is referring to elicited no 

observable response in a particular 

period but were subjected to 

disturbances in later periods that did 

elicit negative responses (the 

commenter’s claim that a bear that 

departed a den without cubs was 

classified as a non-serious response 

supports this possibility because that 

classification would not be possible 

during a period when the bear left the 

den). 

The general argument the commenter 

is expressing seems to be that latent 

effects from disturbance could manifest 

later, and, therefore, our harassment 

classifications for early departure in the 

post-emergence period should be higher 

(presumably serious take by Level A 

harassment as opposed to non-serious 

take by Level A harassment). Survival of 

cubs-of-the-year is often low, and this is 

especially true in the Southern Beaufort 

Sea subpopulation, even for those cubs 

from undisturbed dens. It should be 

expected, therefore, that some cubs that 

departed den sites early during the postemergence period would die before 

reaching independence and others 

would not. Although an early departure 

from a den due to disturbance may 

incur a fitness cost (hence the nonserious take by Level A harassment 

classification), the probability or degree 

of that cost has not been evaluated. 

Consequently, assigning a higher level 

of take (i.e., serious take by Level A 

harassment) is inappropriate because 

that would signify an injury that is 

likely to result in mortality. 

Comment 79: One commenter 

suggested that the Service should clarify 

their explanation for the dates to 

distinguish the early denning period 

from the late denning period because 

this date may be later. 

Response: The specific data range 

cited by the commenter is only related 

to the review of case studies because 

individual birth dates couldn’t be 

known. We therefore had to rely on 

means obtained from the scientific 

literature to represent the natural range 

of den phenology data. The actual 

analysis to estimate disturbance and 

take to denning bears allowed for 

variability in denning phenology dates 

that match the published range of 

values. The actual start/end dates for the 

given denning periods in the analysis 

are based on the simulated dates for 

specific life history events. For example, 

bears are given a simulated birth date 

ranging from 1 December to 15 January 

(i.e., the start of the early denning 

period). The late denning period then 

begins on the date those simulated cubs 

turn 60 days old. 

Comment 80: One commenter 

suggested that the Service should 

consider whether climate change may 

cause a greater impact on polar bears 

that relocate their dens in response to 

disturbance. 

Response: While we agree with the 

commenter that these types of 

relationships are conceivable, we are 

unaware of any information to support 

or document these claims. Further, 

these statements are just conjectures, 

and it’s equally feasible that females 

have sufficient energetic reserves to find 

a new den site given that they already 

spend energy scouting for ideal den 

sites. We are therefore required to use 

the currently best-available information, 

which indicates minimal impacts to 

denning females if forced to find a new 

den site after being disturbed. 

Comment 81: One commenter 

suggested that the Service should 

consider whether the opportunistically 

collected data on polar bear dens is an 

accurate representation of polar bear 

responses to den disturbance and 

whether the Service developed accurate 

model assumptions based on polar bear 

responses to den disturbance. 

Response: We use the best available 

information to calculate the 

probabilities of different levels of 

response to industrial activities. It is 

important to consider the variability 

across individuals and how they 

respond. The Service does not assume 

only minor behavioral responses, but 

provides estimates varying from lethal 

take of cubs to minor behavioral 

responses because that is the range of 

responses observed in real-world 

examples. 

Comment 82: One commenter 

suggested that the Service should 

classify all cases in which denning polar 

bears are disturbed by industry 

activities as take by Level A harassment. 

Response: We agree that there are 

sufficient data to show variability in 

responses to human activity. That is 

what we show with our case study 

assessment (i.e., see table 7 with 

disturbance probabilities). There’s 

always some probability of no response 

and others of varying levels of 

disturbance. We also agree that the case 

study review didn’t allow for 

accounting for bears that chose not to 

den near existing infrastructure/activity 

nor every single den that may have been 

adjacent to activities but going 

undetected. There is no way to ever 

detect all dens. However, we do account 

for bears that avoid denning near 

infrastructure. We detail this on pages 

86 FR 29407–29408 of the proposed rule 

(June 1, 2021). Using historical den data, 

we found that dens occurred less 

frequently than expected adjacent to 

existing infrastructure, so that is 

accounted for in the model. It is simply 

an assumption (with no published 

information to back it up) that bears 

choosing to den away from Industry 

would be more sensitive to disturbance. 

Again, it may be the case, but it’s also 

possible that it is not. So, without any 

data to support this claim, it would be 

inappropriate to incorporate it into the 

analysis. We disagree that we should 

treat all bears that are exposed to 

disturbance as having the potential for 

injury or death. The case study data and 

other published studies (e.g., Amstrup 

1993, Larson et al. 2020) clearly show 

this is not the case. And, as the 

commenter suggests, we know that there 

is a great deal of variability in responses 

to human activity. So, it would be 

inappropriate, and not based on the 

best-available science, to assume all 

bears are subject to potential injury or 

death. 

Comment 83: One commenter 

suggested that the Service should 

consider that specific Industry activities 

may have different levels of impact on 

denning polar bears. 

Response: The probabilities in Table 7 

are drawn from a wide range of 

activities ranging from very minimal 

human activity, to very invasive. In our 

model framework, the varied and 

multiple sources of activity are 

accounted for. Briefly, a den is allowed 

to be exposed to disturbance until it is 

either disturbed and assigned a take by 

Level A harassment or greater, or bears 

emerge and depart their den by the 


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expected (i.e., undisturbed) dates. Thus, 

we do account for the suite of activities 

that can disturb a den. We agree with 

the commenter that no studies exist 

looking at how denning bears respond 

to specific activities. We agree that it 

would be ideal to know the probability 

of different levels of response to 

different types of activity. 

Unfortunately, those data do not 

currently exist. While Owen et al. (2020) 

shows varied distances that denning 

bears can detect different types of 

activities, there are no associated data 

with the distances at which bears will 

display a disturbance response once a 

stimulus is detected. So, we had to take 

the average approach across activity 

types. This likely leads to overestimate 

of take for more limited activities and 

underestimate of take for more 

significant activities. But on average, the 

results would be accurate. 

Comment 84: One commenter 

suggested that the Service should 

consider individual variability and local 

weather conditions when determining 

the time period in which polar bears 

emerge and depart from their dens. 

Response: We agree that local 

conditions may influence when bears 

choose to depart their den sites. 

Unfortunately those relationships have 

not been established so are currently 

just conjecture. We use the best 

available data to establish the range of 

emergence and departure dates so they 

capture the natural range of variability 

in when bears decide to emerge from 

and depart their dens. We simulate each 

individual den with specific dates when 

key activities occur (e.g., emergence, 

departure), so we incorporate the 

individual decision on what constitutes 

‘‘early’’ and do not base it on an overall 

population-level mean. 

Comment 85: One commenter 

suggested that the Service should 

consider Industry impacts on mother 

polar bears and cubs as they are 

traveling from den sites to the sea ice. 

Response: The encounter rates used 

by the Service were generated using 

records of polar bear encounters that 

encompass the dates when sows and 

cubs are likely moving from den sites to 

the sea ice (i.e., the best available 

information). Thus, these individuals 

are currently incorporated in the take 

estimates presented in the ITR. While 

we agree that the type of encounter 

described by the commenter is possible, 

we found no evidence in the encounter 

data used that shows instances of 

females abandoning cubs while after 

departing the den site as a result of 

disturbance from industrial activities. 

This indicates these types of impacts are 

likely very rare. The research operation 

flights referenced by the commenter are 

typically at a much lower elevation than 

industrial flights, and the potential take 

of these flights has been discussed in 

Aircraft Impact to Surface Bears. 

Comment 86: Two commenters 

suggested that the Service should clarify 

the operational constraints of Industry 

vehicles in polar bear denning habitat 

and whether vehicle activity was 

evaluated as an impact factor in the 

denning analysis. 

Response: We disagree with the 

commenter that an attempt would be 

made to identify denning habitat in the 

winter once snow fell. Instead, we rely 

on studies that have already occurred to 

identify areas with suitable conditions 

for capturing snow. The commenter 

cites the comments from Steve Amstrup, 

yet he is a co-author on most of the 

studies that have identified these areas 

in advance of activities. The overall 

probability of running over a den is 

exceptionally small. First, two to three 

AIR surveys must occur before activity 

commences in an area. Given the 

detection probability of AIR, this leads 

to 65–80% (on average) of dens being 

detected. Then, given the overall 

avoidance by Industry of crossing areas 

suitable for denning and the relatively 

small footprint of off-road travel in the 

project area, and the likelihood of bears 

abandoning a den before vehicles 

physically run over it leads to a very 

low risk of this occurring. Operators 

will be required to have and use the 

USGS denning habitat layer to avoid 

denning habitat whenever possible. See 

also Analysis and Assumptions 

Regarding Den Collapse, above. 

Comment 87: One commenter 

suggested that there is insufficient 

information regarding the vulnerability 

of denning habitat to vehicle travel, and 

that the Service should restrict Industry 

vehicle activities in all potential polar 

bear denning habitat defined by USGS 

in order to reduce impacts to denning 

polar bears. 

Response: We disagree that there is 

insufficient information in the ITR to 

ascertain how much denning habitat 

will be vulnerable to vehicle travel. We 

provided all of the tundra travel, ice 

road, and seismic survey region spatial 

data that are part of this ITR. One could 

easily use those files and calculate how 

much denning habitat might be exposed 

to activities. We note, however, that just 

because there is sufficient topographic 

relief to capture snow doesn’t mean that 

bears will use it for denning. Thus, it’s 

inappropriate to consider any area with 

sufficient slope to be off limits. That 

requires some additional assessment of 

the probability of a bear using that area. 

We also provided the layer on relative 

probability of denning. We account for 

the number of dens that go undetected 

and are likely to be disturbed by 

activities. See also comments and 

responses above. 

Comment 88: Two commenters 

suggested that the Service should 

evaluate the limitations of ground-based 

den detection, such as difficulty visibly 

distinguishing dens and suitable 

denning habitat in winter and low 

efficacy of hand-held infrared detectors, 

as part of the Service’s risk assessment 

for industry vehicles causing den 

disturbance. 

Response: We disagree. The applicant 

stated that they would avoid steep 

banks so we also considered this in our 

analysis, which, along with the other 

mitigation measures in place (i.e., aerial 

infrared surveys, trained observers, etc.) 

reduced the probability of running over 

a den to such a small level that it could 

be dismissed and not considered in the 

analysis. See also the comments and 

responses above. 

Comment 89: One commenter 

suggested that the Service should clarify 

how the multiple disturbance events 

during seismic surveys are evaluated in 

order to determine impacts to denning 

polar bears and whether the Service’s 

assumption for seismic survey impacts 

accurately represents realistic impacts. 

Response: The proposed ITR does 

account for the activity associated with 

advance crews during seismic surveys. 

The start date for seismic activities is 

when the advance crews first enter the 

seismic areas, so those are the first dates 

that dens are exposed to disturbance 

and a determination is made (in the 

model framework) whether a den is 

disturbed or not. The response 

probabilities we used for seismic were 

derived from case studies where the 

activities occurred repeatedly, similar to 

activities related to seismic surveys. 

Thus, the repeated activities associated 

with seismic were accounted for based 

on the set of response probabilities we 

used. 

Comment 90: One commenter 

suggests that the Service should account 

for take of polar bears during AIR 

calibration flights, in which aircraft 

calibrate their infrared instruments over 

known polar bear dens. 

Response: The AOGA did not include 

flights over known dens on barrier 

islands in their Request for an ITR. 

Thus, potential take from this practice 

was not analyzed, and any potential 

take that may occur as a result of these 

calibration flights would not be covered 

by the ITR. 

Comment 91: One commenter 

suggested that the Service should more 

thoroughly evaluate the distance at 


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which take is estimated as well as fully 

evaluate whether additional take could 

result from activities requisite to tundra 

travel. 

Response: As stated in the discussion 

of ‘‘Impact Area’’ within the ITR, 

behavioral response rates of polar bears 

to disturbances are highly variable, and 

data that support the relationship 

between distance to bears and 

disturbance is limited. The Service has 

relied upon a number of studies, 

representing the best available science, 

to arrive at the potential impact area of 

1.6 km, including the study cited by the 

commenter. The authors found that 

female polar bears with cubs (the most 

conservative group observed) began to 

walk or run away at a mean distance of 

1,534 m. Importantly, these bears were 

reacting to researchers directly 

approaching them with snowmobiles, 

which is an intentional (as opposed to 

incidental) act, and simply walking 

away from an area may not rise to the 

threshold of Level B harassment under 

the MMPA. The rates of harassment 

used to quantitatively estimate potential 

take were developed using a dataset that 

includes observations of human-polar 

bear encounters on the North Slope of 

Alaska. These encounters include 

observations of polar bear responses to 

snowmachines, trucks, Tuckers, 

bulldozers, and other industrial 

equipment. As such, the effects of these 

noise sources are incorporated into the 

Service’s take estimates. 

Comment 92: One commenter 

suggested that the Service should clarify 

their take evaluation of repeated 

disturbances to the same polar bear. 

Response: As the Service described in 

their description of critical assumptions 

in the ITR, the available studies of polar 

bear behavior indicate that the intensity 

of polar bear reaction to noise 

disturbance may be based on previous 

interactions, sex, age, and maternal 

status. However, as it is impossible 

(without unique identifiers such as 

collars or ear tags) to record repeated 

observations of the same bear, the 

Service has estimated the number of 

Level B harassment events from the 

proposed activities using the 

assumption that each event involves a 

different bear. The Service 

acknowledges bears may be harassed 

repeatedly. Each harassment event is 

classified as a separate take and is 

included in small numbers 

determinations. 

Comment 93: Commenters suggested 

that the Service did not have 

information on the specific Industry 

activities planned during this regulation 

period, which is needed to make the 

Service’s determinations. 

Response: The Service has provided 

detailed descriptions of the proposed 

activities within the ITR. We have also 

provided the public with geospatial files 

of these proposed activities during the 

public comment period in additional to 

monthly human occupancy rates. 

Further, under Description of Letters of 

Authorization (LOAs) in the ITR, the 

Service explains that requests for LOAs 

must be consistent with the activity 

descriptions and mitigation and 

monitoring requirements of the ITR. 

Thus, the Service used detailed 

descriptions of what, where, and when 

activities will occur to calculate 

quantitative take estimates. 

Comment 94: One commenter 

suggested that the Service should 

address how uncertainty and natural 

environmental variation are accounted 

for in the surface interaction model. 

Response: The Service used best 

available science to estimate ice season 

encounter rates. As the commenter has 

noted, observation in the Arctic during 

polar night or severe weather conditions 

is difficult, and as such there are no 

known studies that have conducted sitespecific surveys in the winter months 

within the project area. The Service 

used the most comprehensive database 

available, its LOA database, to develop 

encounter rates and quantitative take 

estimates. Statistical uncertainty was 

accounted for when developing level B 

harassment rates. Furthermore, by 

averaging the number of encounters 

over the past 5 years, the Service has 

encompassed year-to-year differences in 

bear density. 

Comment 95: One commenter 

suggested that the Service should 

consider whether take by Level A 

harassment will occur if Industryrelated noise disturbs walruses hauled 

out on land causing them to stampede 

towards the water and potentially 

trampling walruses during the stampede 

and the basis for the take estimate. 

Response: The Service does not 

dispute that walruses may stampede if 

disturbed while hauled out on land. 

This behavior was discussed in the 

proposed ITR under Description of 

Marine Mammals in the Specified 

Geographic Region: Pacific Walruses. 

However, as is also noted in that 

section, Pacific walruses are extralimital 

in the Southern Beaufort Sea and are 

rarely encountered. There are no records 

of haulouts within the area of proposed 

activities. Thus, using the best available 

records of Pacific walrus abundance in 

the South Beaufort Sea, the Service 

estimated that the potential existed for 

a group of up to 15 walrus to be 

encountered by humans in the project 

area during the open-water season. 

Comment 96: Commenters suggested 

that the Service should clarify how the 

polar bears’ increased use of land in 

recent years is accounted for in the 

surface interaction model. 

Response: The Service used the best 

available data to calculate encounter 

and take rates. In ‘‘Description of 

Marine Mammals in the Specified 

Geographic Region,’’ the Service 

describes an increase in the percentage 

of the Southern Beaufort Sea stock that 

comes ashore in the summer and fall 

(Atwood et al. 2016). By using an 

average of 5 years of reports, the Service 

captured variability in the number of 

encounters that may occur year to year. 

By using encounters in the period 2014– 

2018, the Service has generated 

encounter rates that represent 

contemporary terrestrial habitat use. 

Comment 97: One commenter 

suggests that the Service underestimated 

potential take and suggests clarification 

on the explanation for determining take 

from surface interactions. 

Response: We disagree. The Service 

conducted a robust analysis of surfacelevel interactions related to human-bear 

encounters. The Service discussed that 

analysis in our Evaluation of Effects of 

Specified Activities on Polar Bears, 

Pacific Walruses, and Prey Species: 

Polar Bear: Surface Interactions, and we 

reaffirm that analysis in this final rule. 

Comment 98: One commenter 

suggested that the Service should clarify 

how Industry activity impacts on nondenning polar bears, specifically mother 

bears with cubs traveling to the sea ice 

after den departure, are evaluated as 

take in the surface interaction analysis. 

Response: The dataset that was used 

to analyze potential take from surface 

interactions encompassed all recorded 

human-polar bear interactions 

throughout the year, including the 

months when sows are moving toward 

the sea ice with cubs of the year. There 

are no recorded interactions in the 

2014–2018 dataset between Industry 

and these bears that resulted in Level A 

harassment. The Service has also 

accounted for these potential 

interactions when establishing 

mitigation measures. Under the 

mitigation measures established in the 

proposed rule, Industry must survey for 

maternal polar bear dens, create 

exclusion zones around known dens, 

and report all polar bear interactions 

(including those with sows and cubs) to 

the Service within 48 hours of the event. 

Comment 99: One commenter 

suggested that the Service should clarify 

that infrared methods include both 

aerial and ground-based technology 

methods in order to provide Industry 

entities the flexibility to use the most 


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practicable means for required infrared 

surveys. 

Response: Ground-based infrared 

surveys are not directly comparable to 

AIR surveys and should not be 

considered to have equivalent detection 

rates. We are not aware of any studies 

that have directly estimated infrared 

detection from ground-based surveys. 

But studies have documented that 

ground-based infrared is likely to lower 

detection probability given the greater 

impacts of blowing snow on detection 

than when doing aerial surveys 

(Robinson et al. 2014). Pedersen et al. 

(2020) found that infrared from a 

vertical position (i.e., aerial) was four 

times more likely to detect a den than 

infrared from a horizontal position (i.e., 

from the ground). Given that our 

analysis was based on AOGA’s proposal 

to conduct AIR surveys, we did not 

estimate what the expected level of take 

would be if ground-based infrared was 

used instead on a case-by-case basis. 

Based on what has been published on 

the topic, it would not be appropriate to 

treat ground-based infrared detection as 

equivalent to aerial-based efforts. 

Comment 100: One commenter 

suggested that the Service should revise 

their language for the time period in 

which AIR surveys are to be conducted 

in order to allow for flexibility due to 

poor weather and operational 

complications. 

Response: The results of Wilson and 

Durner (2020) show that specificity in 

dates when activities occur can 

significantly affect the level of 

disturbance expected from industrial 

activities. The Service worked with 

AOGA to find date ranges for AIR that 

met their constraints but that also 

provided sufficient protection for 

denning polar bears in light of their 

proposed activities. AOGA stated they 

were amenable to these dates. 

Unfortunately, the Service’s analysis is 

contingent on AIR surveys being 

conducted within the date ranges in the 

draft ITR and any deviation from those 

dates could lead to increased levels of 

take and harassment of denning bears. 

Thus, the Service will not be able to 

accommodate this request. 

Comment 101: One commenter 

suggested that the Service should clarify 

whether a third AIR survey is required 

for seismic survey activities. 

Response: The Service is requiring 

three AIR surveys to occur prior to all 

seismic activities. The Service has 

worked together with the applicant to 

develop mitigation measures that ensure 

the least practicable adverse impact on 

polar bears. The applicant agreed that 

three surveys are practicable and will be 

conducted prior to all seismic activities 

as a condition of the LOA. 

Comment 102: One commenter 

suggested that the Service should 

address whether the reported efficacy of 

AIR is sufficient to detect polar bear 

dens prior to the commencement of 

Industry activities. 

Response: We incorporate these 

different studies cited in the comment 

that rely on aerial surveys to establish 

our AIR efficacy used in the model. We 

don’t assume complete detection of 

dens, but rather a value of 41% (with 

associated uncertainty). So, we account 

for the inability of an AIR survey to 

detect all dens in our modeling 

framework, and the value we use is 

actually lower than that published in 

Smith et al. (2020). Robinson et al. 

(2014) is inappropriate to include 

because it was based on hand-held 

ground-based infrared, which is not as 

effective as aerial surveys, and they do 

not provide an estimate of detection 

probability. But we do include the 

results from Smith et al. (2020) and 

Amstrup et al. (2004) in our analysis, as 

well as a new study on artificial dens 

(Woodruff and Wilson 2021). 

Comment 103: One commenter 

suggested that the Service should 

consider how the variation in weather 

conditions will affect the efficacy of AIR 

to detect polar bear dens. 

Response: The AIR efficacy values we 

use are from a suite of weather 

conditions and not just optimal 

conditions, so they cover the range of 

possible conditions that surveys are 

flown. For example, Amstrup et al. 2004 

found that AIR efficacy was >80% for 

optimal weather conditions, but we 

don’t use that value. We use the average 

AIR efficacy, which is closer to 55% for 

Amstrup. Because a range of weather 

conditions is used, our estimates are 

able to provide inference across those 

conditions. Additionally, while we 

agree that weather conditions in 

northern Alaska are likely to change 

with climate change, surveys are still 

required to be flown under conditions 

that have been found to be suitable. 

Comment 104: One commenter 

suggested that the Service should 

address that polar bear dens can remain 

undetected despite multiple AIR 

surveys in the area and whether the 

requirement for multiple AIR surveys 

will effectively increase the den 

detection rate. 

Response: We agree that more AIR 

surveys do not make them more 

effective. Dens in the model can 

continue to go undetected even after 

multiple surveys. But, the laws of 

probability indicate that if you do the 

surveys multiple times over a den that 

is available to be detected, the 

probability that it will be detected (at 

least once) increases. Similar to 

Amstrup et al. (2004), when you apply 

two AIR surveys to our simulated dens, 

the overall probability of detection is 

only ∼65%. So, it is incorrect that more 

surveys do not equal more dens 

detected. 

Comment 105: One commenter 

suggested that the Service should 

address how the efficacy of AIR for 

detecting dens with various depths of 

snow cover was accounted for in their 

den detection model. 

Response: We don’t assume that dens 

with snow depth >100 cm can’t be 

detected for the current analysis. AIR 

efficacy rates are for all dens (i.e., 

independent of snow depth), so by 

default includes those dens that are 

unable to be detected for whatever 

reason. Smith et al. (2020) did not 

account for snow depth in their 

detection probability, and Woodruff and 

Wilson (2021) did not find a 

relationship between detection and 

snow depth. That is why we don’t take 

into account snow depth for the 

approach we took in this model. 

Comment 106: One commenter 

suggested that the Service should clarify 

their explanation for the sources used to 

inform their estimation of den detection 

probability and how uncertainty was 

accounted for during their estimation of 

den detection probability. 

Response: Our approach is not 

arbitrary. We are aware of only three 

studies that utilize AIR detection 

estimates. Although Scheidler and 

Perham published a report on aerial 

survey detections, they had significant 

issues (published in their report) that 

precluded our use of their results. Other 

studies use drones (Pedersen et al. 2020) 

or handheld infrared (Robinson et al. 

2014), which are likely not comparable 

and don’t actually provide detection 

probabilities. With respect to the 

Woodruff and Wilson (2021) study, the 

Service published the white paper to 

give readers details on how the 

probabilities were derived, but the 

greater context of the study was not 

provided because it is currently under 

peer-review. Many limitations to the 

study make the use of the lower 

estimate questionable (e.g., onboard 

navigation equipment was not allowed 

for observers compared to real surveys). 

Thus, we used the detection estimate 

from that study as the most reliable (i.e., 

dens that were determined to have been 

covered by the AIR camera). So, the 

decision was not arbitrary, but based on 

our in-depth knowledge of the study 

and its limitations. Lastly, the Service 

doesn’t ignore the uncertainty in den 


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detection depending on people on the 

survey crew. Those differences are 

already incorporated into the estimates 

in Woodruff and Wilson (2021). All 

three surveyors had significant 

experience using AIR to detect polar 

bear dens. Thus, our estimate represents 

the average detection rates for people 

with training in the use of AIR to detect 

polar bear dens. 

Comment 107: One commenter 

suggested that the Service 

underestimated the number of polar 

bear dens that would remain 

undetected, which may affect their take 

estimations. 

Response: First, the den model does 

not assume only 52 dens are on the land 

in any given year. That is the mean 

value we used, but we accounted for the 

uncertainty in this estimate, so the 

number of dens simulated during each 

iteration is highly variable. We agree 

with the assessment by the commenter 

that the results of Woodruff and Wilson 

(2021) show that only 50% of dens were 

detected at least once during the study. 

While that is not the correct metric to 

use in the analysis, our approach to 

estimating infrared efficacy took into 

account the lower detection rates for 

this study in combination with the two 

other studies that provide an aerial 

detection rate of dens with AIR. 

Comment 108: Two commenters 

suggested that the Service should clarify 

the optimal weather conditions for AIR 

surveys to be conducted in order to 

avoid AIR surveys being conducted in 

suboptimal conditions and affecting 

polar bear den detection rates. 

Response: The estimates of AIR 

detection used in the analysis were not 

obtained under optimal weather 

conditions, but under a range of weather 

conditions that AIR surveys are 

possible. Thus, optimal weather 

conditions are not required based on the 

estimates of detection we used. That 

said, it has been standard practice for 

Industry operators to conduct their AIR 

surveys within parameters outlined by 

Amstrup et al., 2004 and York et al., 

2004. This has been added to the 

Mitigation and Monitoring requirements 

in the ITR. 

Comment 109: The regulatory text in 

the proposed rule at § 18.120(a) 

describes the offshore boundary of the 

ITR as matching the boundary of the 

BOEM Beaufort Sea Planning area. 

However, the preamble text and the 

maps in both the preamble and the 

proposed rule describe the geographic 

region as extending 80.5 km (50 mi) 

offshore rather than matching the BOEM 

Planning Area boundary. This 

discrepancy should be corrected. 

Response: We agree and have clarified 

this final rule so that the preamble text 

reflects the boundaries of the geographic 

area in the regulatory language. 

Comment 110: One commenter 

suggested that the Service should 

request that helicopters be used for AIR 

surveys because it has been reported 

that polar bear den detection rates are 

higher when helicopters are used 

compared to fixed-wing aircraft. 

Response: Use of helicopters to survey 

active dens might actually lead to 

greater levels of disturbance and take 

than with fixed-wing aircraft. While it’s 

true that helicopters are more 

maneuverable than airplanes, we have 

not seen any published data (only 

conjecture) that detection rates for dens 

are higher when a helicopter is used vs. 

a fixed-wing aircraft. Interestingly, 

Amstrup et al. (2004) used a helicopter 

and Smith et al. (2020) used a fixedwing, yet when accounting for likely 

undetectable dens, Amstrup et al. (2004) 

has a mean detection of ∼55% compared 

to Smith et al. (2020)’s ∼45%. These are 

likely statistically insignificant as the 

95% CI for the Amstrup et al. (2004) 

estimate largely overlaps the Smith et al. 

(2004) point estimate, which does not 

provide an estimate of the associated 

uncertainty. Lastly, it is incorrect that 

fixed-wings create contrails and 

helicopters do not. We have run into 

issues with helicopters causing 

contrails, which impede visibility while 

circling bears during capture operations 

in the Arctic when temperatures are 

<0 °F. 

Comment 111: One commenter 

suggested that the Service overestimated 

their polar bear den detection rate for 

AIR surveys, which may underestimate 

take estimates resulting from den 

disturbance. 

Response: We rely on the best 

available information to obtain 

estimates of AIR efficacy to detect 

established dens. The mean value used 

is in line with those studies, and the 

associated variability allows detection 

to be as low as 1.5% in some iterations 

of the model. 

Comment 112: One commenter 

suggested that the Service overestimated 

their polar bear den detection rate for 

AIR surveys, which underestimates the 

number of undetected polar bear dens 

that may be potentially disturbed by 

Industry activities. 

Response: We disagree with this 

characterization of the Wilson and 

Durner (2020) estimate derived from 

Amstrup et al. (2004). As noted in the 

ITR, the estimate derived by Wilson and 

Durner (2020), i.e., ∼74%, is only for 

dens available to be detected (i.e., those 

with snow shallow enough to allow AIR 

detection). For the current analysis, 

given that Woodruff and Wilson (2021) 

didn’t find a relationship between 

detection and snow depth, and Smith et 

al. (2020) did not account for dens 

unavailable to be detected (e.g., due to 

snow depth), we corrected the Wilson 

and Durner (2020) estimate to be an 

average detection rate regardless of 

whether a den was available to be 

detected or not. That led to an estimate 

∼55%, with confidence intervals that 

overlap the Smith et al. (2020) estimate. 

Smith et al. (2020) did not provide an 

estimate of uncertainty for their mean 

den detection rate. But overall the 

estimates are very similar and not 

statistically different. The Wilson and 

Durner (2020) approach has been peerreviewed and published in the peerreviewed literature, so it constitutes the 

best available information and warrants 

inclusion in our analysis along with the 

two other studies that exist to estimate 

detection of dens using AIR. 

Comment 113: One commenter 

suggested that the Service clarify their 

requirements for AIR survey flight paths 

in order to ensure all polar bear denning 

habitat is adequately surveyed. 

Response: Our analysis is predicated 

on the fact that AOGA will survey all 

polar bear denning habitat that has been 

identified in the areas with proposed/ 

current infrastructure and industrial 

activities. We make this requirement 

clear in our description of our analytical 

approach. Thus, AOGA will be required 

to ensure that all denning habitat is 

surveyed the requisite number of times 

to be covered under the ITR. 

Comment 114: One commenter 

suggested that the Service overestimated 

their polar bear den detection rate 

because they did not account for the 

depth of the dens in snow and 

deterioration of weather conditions 

during AIR surveys. 

Response: As occurs during Industry 

surveys, AIR surveys were paused when 

conditions such as wind and fog 

affected visibility and/or safety of flying. 

Because of the requirement for the 

surveys to be ‘‘blind,’’ Woodruff and 

Wilson (2021) did not measure snow 

depth at the time of den surveys. This 

would have made tracks in the snow 

alerting AIR observers to the den 

location. They did not find a 

relationship between snow depth and 

detection and highlight that the deepest 

den (145-cm snow ceiling thickness) 

was detected whereas a nearby den with 

snow ceiling thickness of 66 cm was 

not. The authors acknowledge there may 

be other factors not accounted for in the 

study that are affecting den detection 

besides snow depth. 


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Additionally, in the Woodruff and 

Wilson study, an attempt was made to 

reduce the influence of subsequent 

snowfall on their ability to estimate the 

relationship. Thus, they restricted their 

assessment of snow depth to data from 

the first two surveys, to minimize the 

effects of additional snowfall 

accumulation on the relationship with 

detection. We disagree that the study by 

Woodruff and Wilson suggests ‘‘AIR 

surveys are unlikely to detect dens.’’ 

Instead, the study shows that dens can 

be detected, but that the efficacy may 

not be as high as previously thought. 

Hence, they actually state ‘‘unlikely to 

detect all dens.’’ However, we take this 

into account in our analysis and 

consider the range of studies that have 

addressed AIR efficacy to derive AIR 

efficacy used in this analysis. Also see 

Optimal Weather Conditions for AIR. 

Comment 115: One commenter 

suggested that the Service should 

consider requesting additional AIR 

surveys to increase their polar bear den 

detection rate. 

Response: We rely on the best 

available science regarding the efficacy 

of aerial IR surveys to detect established 

polar bear dens. The Service considered 

multiple options for the number of AIR 

flights that would be required and found 

the number published in the ITR 

adequate for reducing take sufficiently 

while still feasible for Industry to 

conduct during the short period of the 

winter when AIR flights can be reliably 

done. 

Comment 116: One commenter 

suggested that the Service overestimated 

their polar bear den detection rate for 

AIR surveys based on comparisons to 

other studies. 

Response: The 74% detection 

estimate was only for dens with snow 

depth <100 cm. The actual probability 

when ignoring snow depth is closer to 

55%. Wilson and Durner are clear how 

they derived these estimates, and they 

rely on standard probability methods. 

The commenter states that the 

appropriate metric to use from Amstrup 

et al. (2004) is the overall number of 

dens detected at least once, divided by 

the total number of dens surveyed. This 

is inappropriate, however, because it 

doesn’t take into account how many 

times each den was surveyed. With 

increasing search effort, the probability 

of detecting the den increases. Wilson 

and Durner (2020) obtained an estimate 

for the probability of detecting a den on 

a single survey. We disagree that our 

mathematic approach ‘‘defies logic,’’ or 

that the approach is sophisticated (it’s a 

simple binomial model) because some 

dens were detected on multiple 

occasions. Thus, it is inappropriate to 

ignore those detections by simply 

looking at the overall number of dens 

detected at least once. Wilson and 

Durner (2020) provide a thorough 

explanation of their approach, and it 

went through numerous rounds of peerreview during which the method was 

deemed appropriate and published in a 

well-respected peer-reviewed journal. 

Comment 117: Two commenters 

suggested that the Service should clarify 

their explanation for averaging the polar 

bear den detection rates across multiple 

studies considering that each study was 

conducted in a different situation that 

may not be applicable to the AIR 

surveys required for these regulations. 

Response: We disagree. Our approach 

actually tries to accommodate the 

different limitations of each of the 

studies. Amstrup was based on real 

dens; Woodruff was based on artificial 

dens. Amstrup used all of the tools an 

aircraft had to offer, but Woodruff didn’t 

to try and control observer learning 

where dens were. Smith didn’t include 

any estimate of uncertainty in their 

estimate of detection, nor did they 

provide much information on methods 

or underlying data and search effort. So, 

each study has their own set of 

limitations, but to our knowledge, these 

are the only data from AIR surveys. So, 

it represents the best available 

information. And the overall probability 

used wasn’t significantly different from 

the results of Smith et al. (2020). 

Comment 118: One commenter 

suggested that the Service should clarify 

their explanation for their polar bear 

den detection rate and recommended 

that this detection rate is unlikely to 

exceed 50%. 

Response: Unfortunately, 50% is not 

an appropriate metric from the 

Woodruff and Wilson study because it 

doesn’t account for search effort nor 

multiple detections of a den across 

surveys. Both of those factors need to be 

considered when estimating a detection 

probability. Additionally, the public 

was given only a brief overview of the 

study and methods because the actual 

study is still under journal peer review. 

Thus, the commenter doesn’t have all of 

the caveats associated with that study 

and why it is likely inappropriate to 

consider only the results from the 

Woodruff and Wilson study and ignore 

the previously published works that 

have different study designs and pros/ 

cons. The detection probability we 

derived and used from Amstrup et al. is 

also very similar to Smith et al. We 

agree with the commenter that it is 

unlikely that real-world AIR will have a 

detection >50%. As we showed in our 

analysis, our mean detection was 41% 

and could go as low as 1.5% during any 

given iteration of the model. 

Comment 119: One commenter 

suggested that the Service should 

specify flight paths for AIR surveys to 

ensure complete coverage of all polar 

bear denning habitat and require that 

AIR surveys conduct multiple passes 

across denning habitat as well as use 

helicopters for AIR surveys to increase 

den detection rates. 

Response: Because the estimates used 

for AIR efficacy are based on the range 

of suitable weather conditions under 

which AIR surveys are acceptable, and 

the analytical approach requires that all 

den habitat (as identified in the studies 

cited) is adequately surveyed, the ITR 

already implicitly requires these to 

occur. 

Comment 120: One commenter 

suggested that the Service should 

address how the efficacy of AIR for 

detecting polar bear dens with more 

than 90 cm of snow cover was 

accounted for in their den detection 

model. 

Response: While one study (Robinson 

et al. 2014) showed lower detectability 

for dens in snow deeper than 90 cm, it 

was based on handheld infrared, not 

aerial. And in the Woodruff and Wilson 

study, a den with snow ∼145 cm deep 

was detected, so a simple cutoff based 

on ground-based infrared is likely not 

appropriate. 

Comment 121: One commenter 

suggested that the Service should 

consider the practicality of requesting 

Industry entities to complete three AIR 

surveys prior to commencing activities 

in polar bear denning habitat. 

Response: The ITR does not indicate 

that industry will conduct three AIR 

surveys of all habitat. Three surveys are 

required only for areas receiving seismic 

surveys, and in years when seismic 

occurs, along the pipeline corridor 

between Deadhorse and Pt. Thomson. 

Regardless, our analysis requires that all 

den habitat within 1 mile of industrial 

activity/infrastructure will receive at 

least two AIR surveys under conditions 

suitable for detecting dens. Only if 

industry flies all of the AIR surveys 

required per the analysis will they have 

coverage under the ITR. 

The Service notes that the extent of 

AIR surveys required by this ITR 

significantly exceeds what has been 

required under prior iterations of the 

ITR and is sufficient to ensure that all 

applicable MMPA standards are met, 

including the requirement to prescribe 

means to effect the least practicable 

adverse impact on the species or stock 

and its habitat. 

Comment 122: One commenter 

suggested that the Service should 


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consider whether AIR efficacy and den 

detection rates will be lower in areas 

adjacent to the Arctic National Wildlife 

Refuge because snow cover in these 

areas are greater than other areas and 

polar bear denning density is 

anticipated to be greater and more 

complex in these areas. 

Response: We take into account in the 

model the fact that some dens inside 

ANWR will go undetected because AIR 

surveys are not planned there and the 

area is outside of the activity area 

proposed by AOGA. We clearly stated 

this in the Proposed ITR document (see 

page 29407 of the FR publication). We 

allow dens to be simulated in the refuge, 

even though activity does not occur 

there as part of this Request. But they 

were put there because they could be 

disturbed by activities in the petition 

area and go undetected by AIR. Any den 

within a mile of activity proposed in the 

ITR, but that occurred inside the refuge, 

was accounted for in our estimates of 

take. Because we account for these dens 

but assume that no AIR surveys will 

take place, differences in habitat 

conditions that could affect AIR 

detection rates are not relevant. 

Comment 123: One commenter 

suggested that the Service continue to 

evaluate and refine their polar bear 

denning model assumptions used to 

determine take estimates for their 

regulations as more data become 

available. 

Response: The Service has used a 

comprehensive dataset of polar bear 

observations to develop estimates of 

Level B harassment, and will continue 

to refine these methods and our 

database for future ITRs. Comparing 

denning model results to historic 

Industry–polar bear encounter records is 

not possible because a systematic effort 

has never been undertaken by Industry 

to find all dens adjacent to existing 

infrastructure, not just ice roads and 

tundra travel routes as is the current 

requirement under the existing ITR. 

Additionally, even when a den is found, 

monitoring has not occurred 

systematically (or frequently) to look at 

dates of den emergence and departure. 

Further, given that the effects of early 

emergence can lead to lower cub 

survival, there is no way for Industry to 

document all cub mortality events that 

are associated with den disturbance as 

this would require constantly 

monitoring a family group until at least 

100 days post emergence (as Rode et al. 

2018 did). 

Comment 124: One commenter 

suggested that the polar bear den case 

studies used to determine responses to 

den disturbance do not accurately 

represent the polar bear responses 

expected during Industry activities 

because these case studies were 

collected during scientific studies in 

which polar bears were captured and 

collared. 

Response: The goal of the case study 

analysis was to inform the consequences 

of den disturbance due to industrial 

activities. Including incidents spanning 

a range of activities (i.e., Industry and 

research-related) was reasonable as 

there are correlations between 

disturbance caused by research and that 

caused by Industry, such as 

inadvertently approaching a den at close 

distance. Additionally, the premise of 

some research was to evaluate the 

response of denning bears to 

remediation activities. Capture events 

likely are more intrusive than any 

disturbance related to industrial or other 

human activities and were not used in 

the calculation of take probabilities. 

Bear responses to capture events can, 

however, help inform our 

understanding of how polar bears 

respond to any type of disturbance. 

Other activities, such as disturbance 

caused by people approaching dens or 

accidental intrusion, are also possible 

when a den’s location is unknown. 

Consequently, exposures by researchers 

are useful in understanding how bears 

respond to disturbance and allowed us 

to better estimate the response 

probabilities that informed the 

simulation model. 

Comment 125: One commenter 

suggested that the Service’s use of the 

upper 99 percent quantile of each 

probability distribution is too 

conservative to determine polar bear 

responses to disturbance and does not 

accurately reflect observer bias and the 

number of unobserved takes and this 

approach results in overestimation of 

polar bear incidental take. 

Response: We disagree. The Service 

did not use the 99-percent quantiles to 

account for perceived directional bias 

by observers (which can neither be 

confirmed nor denied due to lack of 

neutral third party observational data), 

instead, the Service used the 99-percent 

quantiles to encompass the number of 

potential Level B harassment events as 

directed by the MMPA. 

Comment 126: One commenter 

suggested that the Service overestimated 

the take of polar bears during aircraft 

activities by assuming a lower flight 

altitude than is typically flown by 

Industry aircraft as part of their take 

determination analyses. 

Response: When reviewing the dataset 

from coastal polar bear surveys, the 

Service found there was not enough 

data to identify a significant 

relationship between polar bear 

response and distance to the aircraft. 

The Service applied a constant 

harassment rate to all flights listed as 

being flown at 1,500 ft AGL or lower. 

Many flights were listed with a 

minimum altitude of 1,500 ft AGL, 

which would be within the scope of the 

analysis. Flights that are expected to be 

above 1,500 ft (generally originating 

from outside of the ITR region) were 

described as remaining at this altitude 

until descent. Without more information 

on each individual flight’s altitude, 

point of descent, and the present 

weather conditions, we made the 

assumption that an aircraft could 

descend to 1,500 ft AGL or less 

anywhere within the ITR region. 

Comment 127: One commenter 

suggested that the Service overestimated 

the number of polar bears observed by 

vessels during in-water activities and 

this approach resulted in an 

overestimation of polar bear encounter 

rates and take estimates during offshore 

activities. 

Response: There is no data to indicate 

the number of bears present in the water 

at any given time; however, we do have 

data for the number of bears located 

along the coast, which was used in the 

analyses. These bears frequently swim 

between barrier islands and may be 

impacted by these offshore activities. 

Comment 128: One commenter 

suggested that the Service should 

reconsider whether the addition of new 

Industry facilities and infrastructure 

will correlate with an increase in 

incidental harassment of polar bears. 

Response: We disagree. While AOGA 

has drawn this conclusion in their 

Request, the relationship described by 

the Service between distance to shore 

and polar bear encounters indicates that 

an increase in coastal infrastructure will 

increase the number of encounters and 

subsequent harassment events. This 

issue was described at length within the 

proposed rule. 

Comment 129: One commenter 

suggested that the Service should clarify 

how they accounted for the uncertainty 

of non-responses of polar bears to 

disturbance and whether the likely 

underrepresentation of non-responses 

may lead to overestimation of take by 

Level A harassment. 

Response: The case study analysis 

included all well-documented records 

of human activity that occurred within 

1.6 km of active polar bear dens. We do 

not believe that exposures that elicited 

detrimental responses were more likely 

to be documented than those that 

seemingly did not. Consequently, the 

probabilities of exposures resulting in 

lethal take or Level A harassment are 

unlikely to be biased. Further, cases that 


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did not result in an observed 

detrimental response (i.e., ‘nonresponses’ in the comment) do not 

necessarily indicate that the animals 

were unaffected (Frid and Dill 2002, 

Bejder et al. 2006, Laske et al. 2011); 

hence, our classification of ‘likely 

physiological response.’ Arousals 

during denning can lead to some 

increases in body temperature 

(Craighead et al. 1976, Laske et al. 2011, 

Evans et al. 2016b) and heart rate 

(Reynolds et al. 1986, Evans et al. 

2016b), both of which require use of 

valuable energy reserves. Across taxa, 

unobserved effects, including higher 

levels of stress hormones (Moberg 2000, 

Keay et al. 2006) and others have been 

shown to have the potential to be 

equally as consequential for 

reproduction (Carney and Sydeman 

1999, Ellenberg et al. 2006, Rode et al. 

2018b). Decreased reproductive success 

or reproductive failure in bears is 

documented as a consequence of 

denning disturbance (Ramsay and 

Dunbrack 1986, Amstrup and Gardner 

1994, Linnell et al. 2000, Swenson et al. 

1997). 

Comment 130: One commenter 

suggested that the Service should 

consider additional factors that may 

cause a polar bear to emerge early from 

her den without necessarily resulting in 

reduced cub production and survival, 

which are referenced in the Rode et al. 

(2018) study. 

Response: We agree with the 

commenter that there are other 

hypotheses that may explain the results 

of Rode et al. (2018), as we acknowledge 

in the proposed ITR (p. 29393). 

However, Rode et al. (2018) does 

indicate that the most likely explanation 

for their results is the earlier emergence 

leading to survival consequences for 

cubs. This makes sense given the 

altricial nature of cubs when born and 

the time bears spend at the den site after 

emergence to allow cubs time to grow 

more and become acclimated to the 

outside environment. We do attempt to 

take into account some of the other 

causes of emerging from a den without 

cubs. We allow an average of 7% of 

simulated dens to emerge without any 

cubs, so we do account for some females 

naturally emerging without any 

offspring, which are not attributed to 

any form of disturbance from industrial 

activity. We disagree, however, that 

because there are other potential 

hypotheses for the relationship 

presented in Rode et al. (2018) that we 

have to ignore the relationship she 

published. As it currently stands, we 

don’t have any additional data to 

suggest that the relationship 

documented in Rode et al. (2018) isn’t 

accurate as portrayed. However, if 

additional information is published in 

the future, that would be considered the 

best scientific information available and 

we would use it accordingly. 

Comment 131: One commenter 

suggested that the Service should 

consider whether the variability of 

mobile activities will affect occupancy 

rates used to determine take estimates 

and whether take estimates are 

overestimated from a conservative 

occupancy rate. 

Response: Occupancy rates for all of 

the different infrastructure was 

provided by AOGA as part of their 

Request. 

Comment 132: One commenter 

suggested that the Service should 

estimate take for Level A and Level B 

harassment zones for in-water activities. 

Response: The Service has revised 

Table 1 to include details regarding the 

sound measurement units and included 

peak SPL for impulsive sound sources. 

The Service has also revised references 

to past ITR Level B harassment and TTS 

thresholds. With regards to the need for 

Level A harassment zones, the Service 

did not calculate this area as no sound 

sources identified in the proposed 

activities would produce Level A 

threshold noise. As was stated in the 

proposed rule, the Level B harassment 

zone was smaller than the impact area 

of surface activities, so we estimated 

take using the more conservative impact 

area. 

Comment 133: One commenter 

suggested that the Service should 

consider whether the number of takes 

during aircraft overflights is 

underestimated considering the 

increased use of helicopters compared 

to previous years and the higher polar 

bear response rate to helicopters. 

Response: Any flight paths associated 

with major construction activities have 

been incorporated into the aircraft 

analysis. AOGA provided the Service 

with a list of aircraft that would likely 

be used for each activity—an increase in 

helicopter use is speculative. While the 

harassment rates were calculated using 

data from AeroCommander flights, the 

Service discusses results from 

observational flights using helicopters. 

The harassment rates associated with 

these helicopter flights were found to be 

lower than the rates used in the AOGA 

Request. No significant relationship 

between polar bear response and 

distance to aircraft was concluded from 

the dataset. We are working to further 

refine our take rates associated with 

these analyses; however, more data is 

needed before we can differentiate take 

rates based on the type of aircraft. More 

detailed information on behavioral 

responses from these overflights can be 

found in the ITR section Aircraft 

Impacts to Surface Bears. 

Comment 134: A recent peer-reviewed 

article, ‘‘Polar bear behavioral response 

to vessel surveys in northeastern 

Chukchi Sea, 2008–2014’’ by LomacMacNair et al. (2021), should be 

incorporated into the Service’s analysis 

of behavioral responses of polar bears to 

vessel activity as information in the 

publication could be used to improve 

the in-water analysis and could also 

supplement and support established 

mitigation measures, such as set-back 

distances for polar bears, as well. 

Response: We agree Lomac-MacNair 

et al. 2021 is a valuable addition to the 

body of polar bear disturbance 

literature. However, the paper published 

after the proposed rule was published 

for public comment. We have reviewed 

the publication, and the authors’ 

findings are consistent with the current 

impact areas used in the proposed and 

final rules. 

Comment 135: The Service’s 

discussion of the peer-reviewed article 

‘‘Aquatic behaviour of polar bears 

(Ursus maritimus) in an increasingly 

ice-free Arctic.’’ Lone, et al. 2018, 

appears to misstate or overstate 

conclusions contained in that article. 

Response: The Service has clarified 

our discussion regarding the 

conclusions we draw from this article as 

needed. 

Comment 136: The Service should 

supplant the Southall et al. (2019) 

modeled and extrapolated approach by 

gathering hearing data (i.e., TTS and 

PTS) specific to polar bears, rather than 

relying solely on information attributed 

to ‘‘other marine carnivores,’’ and use 

polar bear-specific acoustic information 

for future analyses. 

Response: We agree that our analysis 

could be improved with species-specific 

information for polar bear responses to 

sound. We also recognize that such 

efforts may be challenging to obtain on 

polar bears in the wild or held in 

captivity. However, we will continue to 

improve our understanding of polar bear 

hearing acuity as feasible. 

Comment 137: The Service should 

supplant the Southall et al. (2019) 

modeled and extrapolated approach by 

gathering hearing data (i.e., TTS and 

PTS) specific to walruses, rather than 

relying solely on information attributed 

to ‘‘other marine carnivores,’’ and use 

walrus-specific acoustic information for 

future analyses. 

Response: As noted above, we agree 

that our analysis could be improved 

with species-specific information for 

Pacific walrus responses to sound. We 

also recognize that such efforts may be 


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challenging to obtain on Pacific walrus 

in the wild or held in captivity. 

However, we will continue to improve 

our understanding of Pacific walrus 

hearing acuity as feasible. 

Comment 138: The Service should 

consider the report ‘‘Simulation of Oil 

Spill Trajectories During the Broken Ice 

Period in the Chukchi and Beaufort 

Seas’’ (French-McCay et al. 2016) to 

better inform our analysis of potential 

polar bear oil spill exposure and effects 

in the Beaufort Sea. 

Response: We have used BOEM’s 

2020 Oil Spill Risk Assessment because 

it provides the most current and 

rigorous treatment of potential oil spills 

in the Beaufort Sea Planning Area. We 

agree analysis similar to Wilson et al. 

2018 would be a valuable addition to 

future regulations. 

NEPA and ESA 

Comment 139: One commenter 

suggested that the Service’s EA is 

inadequate because it does not present 

a reasoned explanation for the 

determinations of polar bear take and 

requests the Service to prepare an EIS. 

Response: We disagree. The Service’s 

EA and FONSI reasonably reflect 

considerations important to SBS polar 

bears and Pacific walrus, and are 

scientifically and legally adequate. It is 

appropriate for the EA to reference and 

summarize the ITR’s analysis and 

determinations rather than duplicate 

them in their entirety. 

Comment 140: One commenter 

suggested that the Service did not 

consider restricting the geographic 

scope and timing of activities as an 

alternative to reduce impacts in their 

EA. 

Response: We disagree. Temporal and 

geographic constraints were 

incorporated into AOGA’s revised 

request in light of collaboration with the 

Service. The Service also considered the 

use of further time and space 

restrictions for oil and gas activities to 

limit the impact on denning bears. 

These restrictions were not determined 

to be practicable as they may interfere 

with human health and safety as well as 

the continuity of oil and gas operations. 

The Service found that no additional 

mitigation measures are required to be 

imposed through the ITR, other than 

those described, in order to effect the 

lease practicable adverse impact on 

polar bears and walruses. 

Comment 141: One commenter 

suggested that the Service should 

reevaluate the EA’s no action alternative 

to account for baseline conditions in 

which the commenter suggests that this 

alternative will result in a curtailment of 

activities as opposed to activities 

proceeding without requested 

mitigation measures and potentially 

unauthorized take. 

Response: The EA’s characterization 

of the No Action Alternative is 

appropriate and meets all NEPA 

requirements. Oil and gas exploration, 

development, and production activities 

have occurred at various locations on 

the North Slope and adjacent Beaufort 

Sea waters for several decades and will 

continue to occur in the future, with or 

without this ITR. Hence, they are 

necessarily recognized as part of the 

environmental baseline. The notion that 

denying AOGA’s Request for this ITR 

would cause the specified oil and gas 

activities to cease or not occur has no 

basis in law or practical reality. 

Operators may proceed without an 

incidental take authorization (albeit at 

the risk of enforcement actions), modify 

their activities in a manner that avoids 

incidental take, and/or obtain other 

forms of incidental take authorization 

(i.e., IHAs or a different ITR). 

Comment 142: One commenter 

suggested that the Service does not 

adequately discuss the effectiveness of 

the requested mitigation measures in the 

EA. 

Response: The ‘‘mitigation measures’’ 

integrated into the ITR are already 

incorporated into the proposed action 

analyzed in the EA. The case cited by 

the commenter appears to address the 

manner in which an action agency must 

evaluate additional mitigation measures 

that are not already incorporated into 

the proposed action, and thus seems offpoint. The EA’s references to ‘‘spatial 

and temporal restrictions’’ encompass 

limitations inherent to AOGA’s 

specified activities, e.g., finite project 

footprints, the seasonal rather than yearround nature of certain activities, buffer 

zones, etc. These limitations are 

described in detail in AOGA’s Request, 

the ITR, and Section 2.3.1 of the EA. 

The EA need not comprehensively relist each limitation in the Summary 

sections quoted by the commenter. 

Comment 143: One commenter 

suggested that the Service should 

account for the potential of take by 

Level A harassment and discuss the 

associated impacts on SBS polar bears 

in the EA. 

Response: The Service does not ignore 

the potential for lethal injurious take to 

occur. Rather, it quantitatively 

estimated the probability of such 

impacts occurring. The commenter 

acknowledges as much when it 

references the Service’s own estimate. 

The Service does not assume that no 

‘‘take by Level A harassment’’ will 

occur; rather, it does not anticipate that 

any take beyond take by Level B 

harassment will occur. The Service 

disagrees with the commenter’s broad 

and unsupported assertion that it greatly 

underestimated ‘‘take by Level A 

harassment.’’ The Service analyzed all 

potential impacts using a rigorous 

methodology and the best available 

scientific evidence. 

Comment 144: One commenter 

suggested that the Service should 

account for additional impacts, such as 

planned development and increased 

emissions from future activities, when 

determining what level of take is 

permitted in order to be considered a 

negligible impact. 

Response: The MMPA directs the 

authorization of incidental take where 

the requestor’s specified activities meet 

specific MMPA standard (e.g., small 

numbers, negligible impact, no 

unmitigable adverse impact on the 

availability of the stock for subsistence 

purposes). Here, the Service has 

reasonably determined that the 

incidental take associated with the 

specific activities described in AOGA’s 

Request adhere to applicable MMPA 

standards. The possibility that other 

activities (e.g., hypothetical activities at 

ANWR, Liberty, or greenhouse gas 

emission sources around the world) 

could independently impact the SBS 

stock of polar bears sometime in the 

future does not preclude the issuance of 

this ITR. 

Comment 145: One commenter 

suggested that the Service should 

conduct a more thorough site-specific 

analysis of impacts to polar bears and 

their ESA-designated critical habitat. 

Response: We disagree. As explained 

in the proposed rule, and affirmed in 

this final rule, the Service conducted a 

robust analysis of potential impacts to 

polar bears and their habitat under this 

rulemaking. Further, and as we 

acknowledged in the proposed rule, the 

Service recognized that the proposed 

regulation could impact polar bears and 

their ESA-designated critical habitat. 

Therefore, prior to finalizing this 

regulation, the Service conducted an 

intra-Service ESA section 7 consultation 

on our proposed regulation. The ESA 

section 7 biological opinion and its 

determinations issued prior to finalizing 

these regulations is available as a 

supporting document in the 

www.regulations.gov docket as well as 

on the web at: https://ecos.fws.gov/ecp/ 

report/biological-opinion. 

Comment 146: One commenter 

suggested that the Service should 

include an environmental impact 

statement as part of their authorization. 

Response: We disagree. As explained 

in the proposed rule, and affirmed in 

this final rule, the Service fully 


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complied with our NEPA 

responsibilities and determined that the 

preparation of an EIS was not required 

for these regulations. Additionally, the 

Service notes that the polar bear is 

considered threatened, not endangered, 

under the ESA. The Service likewise 

fully complied with the consultation 

requirements under section 7 of the 

ESA, finalizing this regulation only after 

receipt of required determinations 

under that consultation. 

Comment 147: One commenter 

suggested that the Service should 

broaden the purpose and need specified 

in the EA in order to consider additional 

alternatives for their environmental 

analysis. 

Response: The Service’s statement of 

purpose and need is appropriate and not 

impermissibly narrow. Further 

explanation of the Service’s efforts to 

identify other reasonable alternatives is 

provided in the final EA. The Service’s 

summaries of (1) its early coordination 

with AOGA, which resulted in AOGA 

revising its Request in a manner that 

further limited the scope of its specified 

activities, and (2) its analysis conducted 

under the MMPA’s least practicable 

adverse impacts standard further 

established that the Service complies 

with the letter and spirit of NEPA’s 

requirement to analyze all reasonable 

alternatives. 

Comment 148: One commenter 

suggested that the Service should clarify 

the EA’s purpose and need to ensure 

that these statements are consistent with 

the Service’s requirements under the 

MMPA and these statements are 

separate from the applicant’s interests. 

Response: The Service’s EA reflects 

the fact that the agency’s interest is 

distinct from the applicant’s. The 

Service’s interest is in fulfilling its 

obligations under the MMPA and taking 

a hard look at its proposed action under 

NEPA. The Service will render its 

decision based on the relevant statutory 

and regulatory authorities whether or 

not that decision is in the applicant’s 

interest. 

Comment 149: One commenter 

suggested that the Service should revise 

the purpose and need statements in the 

EA to clarify that the environmental 

impact analysis was conducted to limit 

impacts of Industry activities on polar 

bears and walruses rather than 

supporting the ITR determinations for 

authorization. 

Response: The Service did not 

‘‘predetermine’’ anything in this 

process. The Service’s EA analyzes the 

potential impacts of a proposed action, 

i.e., issuing an ITR, and not a decision 

that was already made. Were the Service 

(on the basis of its own initial review or 

additional information submitted via 

public comment) to find itself unable to 

make the requisite determinations under 

the MMPA, it would not issue a final 

ITR. While this much is clear from the 

larger context of the proposed ITR and 

draft EA, the Service has revised the 

final EA so as to review any reasonable 

implication to the contrary. 

Comment 150: One commenter 

suggested that the Service should 

consider as alternatives in their EA 

additional mitigation measures that 

include restricting Industry activities 

during the polar bear denning season, 

implementing a buffer around denning 

habitat, and only authorizing Industry 

activities that are compliant with the 

Nation’s climate goals to limit global 

warming. 

Response: The Service has worked 

with the applicant to identify areas of 

high denning density and incorporate 

later start dates for seismic activity in 

this region. We also worked with the 

applicant to develop ideal temporal 

windows for maternal denning surveys. 

While further restrictions of 

operations during winter and 

implementation of a buffer around all 

potential denning habitat are not 

practicable given the location of existing 

facilities and roads that must be utilized 

during winter to ensure the continuity 

of operations and protection of tundra 

and wetlands, the ITR contemplates a 

suite of mitigation measures to protect 

denning bears (i.e., avoidance measures, 

multiple AIR surveys, exclusion zones 

around known or putative dens). Since 

the Service does not have authority to 

approve or disapprove the oil and gas 

activities themselves, it cannot pick and 

choose which activities may continue in 

order to meet climate goals. 

Comment 151: One commenter 

suggested that the Service should clarify 

how the physical environment will be 

impacted by Industry activities in the 

EA. 

Response: The commenter appears to 

unduly conflate potential impacts from 

the proposed action—i.e., issuing an 

ITR—with potential impacts from the 

underlying oil and gas activities, which 

the Service does not authorize and 

which are not an effect of the action. In 

developing the EA, the Service 

considered whether issuing the ITR and 

authorizing the incidental take 

contemplated therein would cause any 

reasonably foreseeable impacts to the 

physical environment, and reasonably 

determined that it would not. None of 

the on-the-ground activities cited in the 

comment would be approved by the 

Service or caused by the ITR. 

Comment 152: One commenter 

suggested that the Service should 

address how additional oil and gas 

activities will impact the climate as part 

of the EA. 

Response: The scope of the EA is to 

describe impacts from the Federal 

action of issuing the ITR. Effects of the 

oil and gas activities themselves, to 

include upstream and downstream GHG 

emissions, are not effects of the 

Service’s Proposed Action. 

Mitigation Measures 

Comment 153: One commenter 

suggested that the Service should 

include mitigation measures that restrict 

Industry activities. 

Response: While reviewing prior 

iterations of AOGA’s Request, the 

Service discussed the appropriateness of 

further limiting the scope of AOGA’s 

specified activities so as to reduce the 

potential taking of polar bears. AOGA 

subsequently made several revisions to 

its Request, which the Service 

accounted for in its analyses under the 

MMPA and NEPA. The Service also 

attempted to identify further operational 

restrictions in satisfaction of the 

MMPA’s least practicable adverse 

impacts standard and NEPA’s 

requirement to analyze reasonable 

alternatives and mitigation measures. 

The results of those efforts are described 

in the various analyses supporting the 

ITR process. 

Comment 154: One commenter 

suggested that the Service should 

address the inconsistency in the number 

of required AIR surveys in the EA and 

ITR. 

Response: We will provide further 

clarification in the EA on the number of 

AIR flights required for each activity. 

Comment 155: One commenter 

suggested that the Service should revise 

the mitigation measure at proposed 

§ 18.126(d)(2) to include ‘‘safe and 

operationally possible’’ in regards to 

maintaining the minimum aircraft flight 

altitude. 

Response: We have made this 

revision. 

Comment 156: One commenter 

suggested that the Service should revise 

the mitigation measure at 

§ 18.126(4)(c)(1) to include that vessel 

crew members may also qualify as 

dedicated marine mammal observers in 

order to accommodate vessels with 

limited crew capacity. 

Response: The Service recognizes the 

limited crew member capacity aboard 

certain vessels and that it may not 

always be possible to take on an 

additional crew member to conduct 

watches for marine mammals. 

Requirements for marine mammal 

observers will be evaluated upon 

submission of applications for LOAs. 


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Comment 157: One commenter 

suggested that the Service should 

consider additional infrared technology 

alternatives in addition to AIR in order 

to increase the detectability of polar 

bear dens. 

Response: AIR efficacy rates used in 

our estimates for take of denning bears 

were based upon surveys using both 

helicopters and fixed wing aircraft. 

AOGA proposed using only fixed wing 

aircraft for IR so that is what the Service 

analyzed. While visual observations and 

on-the-ground surveys are commonly 

implemented mitigation measures in 

addition to AIR surveys, we currently 

lack the data needed to analyze the den 

detection efficacy rates of visual and 

handheld infrared methods. 

Comment 158: One commenter 

suggested that the Service should clarify 

the required mitigation measures 

regarding offshore seismic surveys. 

Response: No offshore seismic 

operations were included in the 

proposed activities, thus take will not be 

authorized for offshore seismic projects 

in this rule. As such the Service did not 

need to include mitigation measures 

such as ramp-up and shutdown 

procedures. 

Comment 159: One commenter 

suggested that the Service should clarify 

whether the requirement for Industry 

entities to cooperate with the Service 

and participate in joint research efforts 

to assess Industry impacts on marine 

mammals was removed. 

Response: This language was 

erroneously omitted. We have revised 

the final rule to include this language. 

Comment 160: One commenter 

suggested that the Service should clarify 

whether human—polar bear encounters 

that occur during this regulation period 

will be submitted to the Polar Bear— 

Human Information Management 

System (PBHIMS) in order to contribute 

to international efforts for polar bear 

conservation. 

Response: The Service represents the 

United States as a participant in the 

Polar Bear Range States. We will 

continue to submit applicable human— 

polar bear encounter records to PBHIMS 

as part of our participation in this effort. 

Comment 161: One commenter 

suggested that the Service should 

request stricter mitigation measures for 

minimum aircraft flight altitudes and 

maximum vessel speeds to reduce 

potential impacts on marine mammals. 

Response: The Service has worked 

with the applicant to develop mitigation 

measures that create the least 

practicable adverse impact on polar 

bears and Pacific walruses. The ITR 

requires aircraft to fly high enough, and 

vessels to travel slow enough, to greatly 

reduce the potential for impacts. Further 

restrictions were deemed unnecessary to 

achieve the least practicable adverse 

impact because they were precluded 

either by safety considerations or they 

would not discernably reduce the 

potential for effects to marine mammals. 

Comment 162: Commenters suggested 

that the Service should request more 

specific mitigation measures to reduce 

impacts on marine mammals during 

project activities. 

Response: The ITR already prescribed 

the means of effecting the least 

practicable adverse impact on Pacific 

walruses and SBS polar bears. Further, 

the Service retains discretion to impose 

additional mitigation measures on an 

activity-specific basis through the LOA 

process. 

Comment 163: One commenter 

suggested that the Service should 

address how the requested mitigation 

measures reduce Industry impacts on 

polar bear and walrus and their habitat. 

Response: The Service has worked 

with the applicant to identify areas of 

high denning density and incorporate 

later start dates for seismic activity in 

this region. We also worked with the 

applicant to develop ideal temporal 

windows for maternal denning surveys. 

These mitigation measures have been 

designed to impart the least practicable 

adverse impact from the proposed 

activities on polar bears. 

Comment 164: One commenter 

suggested that the Service should 

evaluate the effectiveness of monitoring 

by protected species observers (PSOs) to 

detect marine mammals during periods 

of restricted visibility. 

Response: While we acknowledge 

some weather conditions may hinder 

their ability to identify animals, the 

Service believes that PSOs contribute 

information important to the safety of 

humans, polar bears, and Pacific 

walruses. 

Comment 165: One commenter 

suggested that the Service should revise 

language in the mitigation measures to 

be more specific about Industry activity 

restrictions in order to reduce impacts 

on marine mammals. 

Response: There is an iterative 

process of communication between the 

Service and applicants when applying 

for individual LOAs and upon the 

receipt of results from maternal den 

surveys. The Service is unaware of the 

exact location dens may be occurring 

each year and is unable to make specific 

regulations based on these locations. 

Comment 166: One commenter 

suggested that the Service should 

consider all habitat characterized by a 1- 

meter elevation difference and a slope of 

eight degrees or greater as suitable polar 

bear denning habitat that should be 

avoided by Industry activities. 

Response: The applicant is required to 

consult the USGS map of potential 

denning habitat prior to activities. 

Mitigation measures outlined by the ITR 

must also be implemented to reduce 

disturbance to unknown dens. 

Comment 167: One commenter 

suggested that the Service should 

request that all Industry entities should 

hire PSOs to monitor Industry impacts 

on marine mammals. 

Response: Hiring of separate PSOs is 

not always practicable for the 

applicant’s proposed activities. The 

Service has included training, 

monitoring, and reporting requirements 

in the rule. 

Comment 168: One commenter 

suggested that the Service should 

consider designating certain areas that 

are important to marine mammals as offlimits to Industry activities. 

Response: We appreciate the 

recommendation and will continue to 

research and incorporate innovative 

measures for achieving the least 

practicable impact in future ITRs. 

Comment 169: One commenter 

suggested that the Service should 

request a 1-mile buffer around all 

suitable polar bear denning habitat in 

order to prevent Industry activities 

disturbing undetected polar bear dens 

and reduce impacts to denning polar 

bears. 

Response: Proper denning habitat 

requires the creation of snow drifts, 

which can differ from year-to-year as it 

is based on terrain and weather 

conditions. The ability to identify areas 

in which these snow drifts may occur 

each year prior to operations is not 

practicable. 

Comment 170: One commenter 

suggested that the Service should 

analyze the results of polar bear den 

monitoring AIR surveys and human– 

polar bear encounters reported during 

this regulation period in a timely 

manner in order to better evaluate the 

effectiveness of the requested mitigation 

measures. 

Response: We appreciate the 

recommendation. 

Comment 171: One commenter 

suggested that the Service should 

request that Industry activities be shut 

down if an injured or dead walrus or 

polar bear is reported and activities not 

resume until the Service investigates the 

circumstances that caused the injury or 

death of the walrus or polar bear. 

Response: The Service has included 

in the rule a reporting requirement upon 

the injury or death of a walrus of polar 

bear as soon as possible but within 48 

hours. While it may aid in any 


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subsequent investigation, ceasing 

activities in an active oil field may not 

be practicable or safe in certain 

circumstances, and thus will not be 

mandated. 

Comment 172: One commenter 

suggested that the Service should clarify 

their definition for a concentration or 

group of walruses or polar bears, and 

the commenter recommended this 

definition be two or more individuals. 

Response: We have added this 

revision. 

Comment 173: Paragraph 4 under 

‘‘Mitigation measures for operational 

and support vessels’’ notes the 1 July 

date to allow oil and gas vessels to enter 

the Beaufort Sea, which is based on past 

information that could become less 

relevant and accurate in the future. We 

recommend the Service consider other 

metrics to meet the intention of this 

measure. A more flexible approach, for 

example, would be to restrict entry into 

the Beaufort Sea until a sufficient 

percentage of shorefast ice has melted. 

Response: We have considered this 

request and recognize that in the future 

changing sea ice conditions, especially 

if the impacts of climate change are not 

ameliorated, may reflect a different 

metric. However, and because these 

regulations are issued for a period of 5 

years only, at this time we believe the 

July 1 date best reflects our current 

understanding of sea ice changes. We 

also have determined that providing this 

date will provide better certainty to the 

regulated public for planning purposes. 

Comment 174: One commenter 

suggested that the Service should 

account for polar bears becoming 

habituated to Industry activities to avoid 

overestimating take. 

Response: We are not aware of any 

studies that have shown that bears 

become habituated to humans after 

denning in industrial areas or that this 

type of habituation leads to reduced 

disturbance. If the information existed, 

we would have incorporated it into the 

model. Harassment rate calculations 

incorporated the Service’s polar bear 

sighting database, which contains all 

reports of Industry sightings of walrus 

and polar bears (as directed by the 

Service of all LOA holders). Assuming 

the practices of training, monitoring, 

and adaptive measures have previously 

been implemented, the sightings data 

would have somewhat incorporated 

their implementation. However, at this 

time there is no way to explicitly 

incorporate this data into the analysis. 

Comment 175: One commenter 

suggested that the Service should 

account for the effectiveness of 

mitigation measures in their take 

estimations in order to avoid 

overestimating the number of incidental 

takes of polar bears during Industry 

activities. 

Response: We agree that mitigation 

measures are important for reducing 

disturbance to polar bears, and we 

currently require each applicant to have 

a polar bear interaction plan and to have 

taken approved polar bear deterrence 

training. However, it is unclear how to 

integrate the measures into our 

quantitative modeling approach. The 

implementation of these mitigation 

measures is key to ensuring the least 

practicable adverse impact on polar 

bears and Pacific walrus as directed by 

the MMPA. 

Policy and Procedure 

Comment 176: This proposed ITR 

appears to include new information 

requirements from applicants seeking 

LOAs. New items include: (1) A digital 

geospatial file of the project footprint, 

(2) estimates of monthly human 

occupancy of the project area, and (3) 

dates of AIR surveys if such surveys are 

required. However, the text in the actual 

proposed rule, i.e., §§ 18.122–18.123, 

does not clearly indicate a requirement 

for these items. We recommend that this 

requirement be clarified in the final 

rule. Similarly, the preamble of the 

proposed rule introduces a new concept 

of ‘‘monthly human occupancy’’; 

however, this new concept as written 

may be confusing, and we similarly 

recommend that it be better described in 

the final rule to ensure applicants can 

provide the requested information. 

Response: We have revised this final 

rule to clarify information requirements 

from applicants for LOAs and have 

clarified our discussion regarding 

monthly human occupancy. 

Comment 177: Section 18.126(b)(4) of 

the proposed regulation states that 

applicants will restrict timing of the 

activity to limit disturbance around 

dens. We recommend clarifying whether 

this will apply to an unoccupied den, 

putative dens, or verified occupied dens 

only and describing what types of 

timing restrictions can be expected. 

Response: We agree and have added 

clarifying language to § 18.126(b)(4) of 

this final rule. 

Comment 178: The term ‘‘other 

substantially similar’’ activities is used 

in the title of subpart J of the proposed 

rule as well as in §§ 18.119, 18.121, 

18.122, and 18.124. This term follows 

the description of the activities from 

which take may occur but is not found 

in the preamble text. We recommend 

the Service provide examples of these 

activities in the proposed rule or define 

this term in the preamble to add clarity. 

Response: We agree and have revised 

this final rule to provide clarity. 

Comment 179: The proposed ITR 

incorrectly reflects the numbers of 

leases and land area covered by those 

leases in the NPR–A. 

Response: We agree. This final rule 

has been revised to reflect 307 leases 

covering 2.6 million acres. 

Comment 180: In regard to 

compliance with international 

conservation agreements, one 

commenter suggested that the Service 

should consider transboundary impacts 

on polar bears under international polar 

bear conservation agreements. 

Response: While we acknowledge 

polar bears in the Southern Beaufort Sea 

move between the United States and 

Canada, our analysis determined that 

authorizing the Level B harassment of a 

small number of polar bears in the 

Beaufort ITR region will not have any 

transboundary impacts, much less 

impacts that violate international 

obligations. The Service has also 

reasonably determined that these Level 

B harassments will not have any 

unmitigable adverse impacts on the 

availability of SBS polar bears for 

subsistence uses. Additionally, while 

we acknowledge the important 

management provisions accomplished 

under the 1988 Inuvialuit-Inupiat Polar 

Bear Management Agreement, we note 

that this is a voluntary agreement and 

therefore not binding on the U.S. 

Government. 

Comment 181: One commenter 

suggested that the Service should 

evaluate activity impacts for a larger 

geographic region that extends beyond 

areas of Industry activity. 

Response: The Service has conducted 

a thorough and robust analysis using the 

best available science to calculate the 

number of incidental harassments of 

polar bears and walrus due to Industry 

activities within the specified 

geographical region. The ITR refers 

specifically to ‘‘the area of Industry 

activity’’ as it is the source of the 

impact, which is not uniformly 

distributed across the specified 

geographical region. The Service is 

unable to calculate take from Industry 

activities in areas where Industry 

activities do not occur within the 

specified geographical region. While the 

range of a species may be larger than the 

specified activity area, the distribution 

is rarely (if ever) uniform within that 

space, especially in migratory species. 

Small numbers determinations are 

based on the number of individual bears 

exhibiting a Level B response and the 

appropriate stock population estimate. 

Comment 182: One commenter 

suggested that the Service did not 


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provide the allotted time for the public 

comment period that is specified in the 

MMPA, APA, and NEPA regulations. 

Response: The Service provided the 

public with a sufficient opportunity to 

comment on the proposed ITR and draft 

EA. The numerous, in-depth public 

comments that the Service received on 

the proposed ITR modeling analysis 

appear to corroborate the Service’s 

judgment on this issue. ITRs establish 

important mitigation measures and 

provide significant conservation 

benefits to polar bears, and it is 

important that the Service finish its 

process and render a decision in a 

timely manner. 

We also note that the commenter has 

in fact had access to the referenced 57 

case studies—which were provided as 

part of the administrative record in the 

Willow litigation in which they are a 

plaintiff—for several months. These 

studies have also been in the Service’s 

Freedom of Information Act reading 

room for the duration of the proposed 

ITR comment period. With respect to 

the Woodruff and Wilson study, the 

Service gained access to a draft 

manuscript and preliminary results 

during the later stages of development 

of the proposed ITR and thought it was 

important to include this information as 

part of the best available scientific 

evidence. Although we expected a final 

manuscript would be available for 

public release prior to publication of the 

proposed ITR, this did not occur. In the 

interest of providing information for 

public review, the Service then 

developed its own summary of relevant 

findings and uploaded that summary to 

the docket as soon as it could. The 

Service adjusted the assumed AIR 

efficacy rate utilized in the ITR process 

based on this new information. Because 

the results of this study suggest an 

efficacy rate lower than that previously 

assumed, the Service’s integration of 

this information resulted in a slight 

downward refinement of the assumed 

AIR efficacy rate. 

Comment 183: One commenter 

suggested that the Service should 

include a list of entities conducting 

activities under this authorization and a 

description with the accompanying 

analysis of expected impacts from these 

Industry activities in the authorization. 

Response: No entities may conduct 

activities under coverage of this ITR 

until they receive an LOA from the 

Service. The ITR provides sufficient 

description of the specified activities 

and those entities that qualify for LOAs. 

Comment 184: One commenter 

suggested that the Service should 

include a list of specific oil and gas 

activities that the Service evaluated and 

that would be authorized under LOAs 

issued under these regulations. 

Response: The description of 

specified activities provided in the ITR 

is sufficiently detailed. Additional 

information is available in AOGA’s 

request. 

Comment 185: One commenter 

suggested that the Service should revise 

their language to exclude listing specific 

subsistence communities or 

organizations that may be consulted 

during a Plan of Cooperation and add a 

general requirement in order to avoid 

potentially excluding other 

communities or organizations. 

Response: Comment noted. 

Comment 186: One commenter 

suggested that the Service should 

complete government-to-government 

consultations with Alaska Native 

communities to ensure that the Service 

mitigates the impacts on subsistence use 

of marine mammals prior to finalizing 

this ITR. 

Response: The Service has 

determined that issuing this ITR would 

not cause any potential effects that 

trigger the obligation to engage in 

government-to-government consultation 

or government-to-ANCSA (Alaska 

Native Claims Settlement Act) 

corporation consultation. The effects of 

the Service’s action is limited; it only 

authorizes the Level B harassment of 

small numbers of polar bears. Any 

resulting effects to individual polar 

bears would be inherently limited and 

short-term and, as explained in more 

detail elsewhere, would not cause more 

than a negligible impact to the SBS 

stock of polar bears and or any 

unmitigable adverse impacts on the 

availability of SBS polar bears for 

subsistence uses. As such, the Service 

has determined that promulgating this 

ITR will not have any substantial direct 

effects on any federally recognized 

Tribes or ANCSA corporations. 

That said, in the interest of 

cooperation and ensuring that the views 

and concerns of Alaska Native 

communities are heard and considered 

in its decision-making process, the 

Service sent notification of its proposed 

action to promulgate the ITR to federally 

recognized tribes and ANCSA 

corporations with interests in the 

Beaufort ITR area and surrounding areas 

on May 27, 2021. The Service did not 

receive any replies indicating interest in 

government-to-government consultation 

or government-to-ANCSA corporation 

consultation. The Service remains open 

to consulting with these parties at any 

time, including prior to the issuance of 

LOAs and further notes the regulatory 

requirement that LOA applicants 

conduct their own outreach with 

potentially affected subsistence 

communities. While the commenter is 

correct that communications with 

Industry are not government-togovernment consultations or 

government-to-ANCSA corporation 

consultations, such communications 

have proven to be a productive means 

of resolving potential conflicts and 

identifying issues that may warrant 

formal consultation with the Service. 

Comment 187: One commenter 

suggested that the Service should 

reconsider whether Industry activities 

will have an unmitigable adverse impact 

on subsistence use of marine mammals 

considering the limit on the harvest of 

SBS polar bears due to their declining 

population abundance. 

Response: The Service disagrees. The 

ITR concludes that there will be no 

unmitigable adverse impacts on the 

availability of polar bears and has relied 

on the best scientific information 

available, monitoring data, locations of 

hunting areas relative to Industry 

activities, community consultation, 

Plans of Cooperation, and harvest 

records to reach this conclusion. 

Comment 188: One commenter 

suggested that the Service should 

reconsider whether the addition of new 

Industry facilities and infrastructure 

will correlate with an increase in 

incidental harassment of polar bears. 

Response: We disagree. While AOGA 

has drawn a contrary conclusion in their 

Request, the relationship described by 

the Service between distance to shore 

and polar bear encounters indicates an 

increase in coastal infrastructure will 

increase the number of encounters and 

subsequent harassment events. This was 

described at length within the ITR. 

Comment 189: Commenters suggested 

that the Service should clarify their 

explanation for the lack of an oil spill 

risk assessment. 

Response: Please note that the Service 

does not authorize the incidental take of 

marine mammals as the result of illegal 

actions, such as oil spills. A detailed, 

activity-specific analysis of potential 

take arising from a hypothetical oil spill 

is beyond the scope of this ITR. That 

said, the Service did consider available 

oil spill risk assessments to inform its 

ITR analysis. References to the various 

materials considered by the Service are 

provided in the ITR. While we used a 

timeframe ending in 1999 to present one 

summary statistic, we also considered 

data as recent as 2020. BOEM’s OSRA 

represents the best available information 

on the risk of oil spills to polar bears in 

the Southern Beaufort Sea. We detailed 

a sample of cases of recent onshore oil 

spills and potential effects on polar 

bears. The commenter is correct that the 


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focus of our oil spill analysis was on 

large oil spills greater than 1,000 barrels. 

Spills less than 1,000 barrels are 

unlikely to cause the widespread 

impacts discussed in the oil spill 

analysis. Industry is required to notify 

multiple agencies, including the 

Service, of all spills on the North Slope 

and coordinates spill response 

accordingly. Lastly, as explained in the 

ITR, ‘‘no major offshore oil spills have 

occurred in the Alaska Beaufort Sea. 

Although numerous small onshore 

spills have occurred on the North Slope, 

to date, there have been no documented 

effects to polar bears’’. 

Comment 190: One commenter 

suggested that the Service should clarify 

the requirement for Industry entities to 

submit a Plan of Cooperation. 

Response: We agree. The Service 

included this information in the 

Description of Letters of Authorization 

section of the proposed and this final 

rule. 

Comment 191: One commenter 

suggested that the Service should 

request Industry entities to engage in 

outreach with subsistence communities, 

including communities in the Bering 

Strait and Chukchi Sea, to ensure 

Industry vessel activity does not 

interfere with subsistence activities. 

Response: While the Service has 

included vessel traffic restrictions in the 

ITR as a precautionary measure, AOGA 

has not requested take authorizations for 

vessel activity through the Bering Strait 

and Chukchi Sea; therefore, no take has 

been estimated or authorized for these 

activities. 

Comment 192: One commenter 

suggested that the Service should 

suspend the proposed rulemaking and 

request AOGA to submit a revised 

request that addresses shortcomings 

before moving forward with this action. 

Response: Thank you for the 

recommendation, but the Service 

already determined AOGA’s revised 

request to be adequate and complete 

and finds no basis for requiring further 

revisions. 

Comment 193: One commenter 

suggested that the Service should be 

more collaborative with NMFS in order 

to develop, review, and implement 

acoustic and behavior thresholds for 

marine mammal species. 

Response: Comment noted. 

Required Determinations 

Treaty Obligations 

This ITR is consistent with the 1973 

Agreement on the Conservation of Polar 

Bears, a multilateral treaty executed in 

Oslo, Norway, among the Governments 

of Canada, Denmark, Norway, the Soviet 

Union, and the United States. Article II 

of this Polar Bear Agreement lists three 

obligations of the Parties in protecting 

polar bear habitat. Parties are obliged to: 

(1) Take appropriate action to protect 

the ecosystem of which polar bears are 

a part; (2) give special attention to 

habitat components such as denning 

and feeding sites and migration 

patterns; and (3) manage polar bear 

subpopulations in accordance with 

sound conservation practices based on 

the best available scientific data. 

This rule will further consistency 

with the Service’s treaty obligations 

through incorporation of mitigation 

measures that ensure the protection of 

polar bear habitat. Any LOAs issued 

pursuant to this rule would adhere to 

the requirements of the rule and would 

be conditioned upon including area or 

seasonal timing limitations or 

prohibitions, such as placing 1.6-km (1- 

mi) avoidance buffers around known or 

observed dens (which halts or limits 

activity until the bear naturally leaves 

the den) and monitoring the effects of 

the activities on polar bears. Available 

denning habitat maps are provided by 

the USGS. 

National Environmental Policy Act 

(NEPA) 

Per the National Environmental 

Policy Act (NEPA; 42 U.S.C. 4321, et 

seq.), the Service must evaluate the 

effects of the proposed action on the 

human environment. We have prepared 

an environmental assessment (EA) in 

conjunction with this rulemaking and 

have concluded that the issuance of an 

ITR for the nonlethal, incidental, 

unintentional take by harassment of 

small numbers of polar bears and Pacific 

walruses in Alaska during activities 

conducted by the applicant is not a 

major Federal action significantly 

affecting the quality of the human 

environment. A copy of the EA and the 

Service’s FONSI can be obtained from 

the locations described in ADDRESSES. 

Endangered Species Act 

Under the ESA, all Federal agencies 

are required to ensure the actions they 

authorize are not likely to jeopardize the 

continued existence of any threatened 

or endangered species or result in 

destruction or adverse modification of 

critical habitat. In 2008, the Service 

listed the polar bear as a threatened 

species under the ESA (73 FR 28212, 

May 15, 2008) and later designated 

critical habitat for polar bear 

subpopulations in the United States, 

effective January 6, 2011 (75 FR 76086, 

December 7, 2010). Consistent with 

these statutory requirements, prior to 

issuance of this final ITR, we completed 

intra-Service section 7 consultation 

regarding the effects of these regulations 

on polar bears with the Service’s 

Fairbanks’ Ecological Services Field 

Office. The Service has found the 

issuance of the ITR will not jeopardize 

the continued existence of polar bears or 

adversely modify their designated 

critical habitat, nor will it affect other 

listed species or designated critical 

habitat. The evaluations and findings 

that resulted from this consultation are 

available on the Service’s website and at 

https://www.regulations.gov. 

Regulatory Planning and Review 

Executive Order 12866 provides that 

the Office of Information and Regulatory 

Affairs (OIRA) in the Office of 

Management and Budget (OMB) will 

review all significant rules for a 

determination of significance. OMB has 

designated this rule as not significant. 

Executive Order 13563 reaffirms the 

principles of Executive Order 12866 

while calling for improvements in the 

nation’s regulatory system to promote 

predictability, reduce uncertainty, and 

use the best, most innovative, and least 

burdensome tools for achieving 

regulatory ends. The Executive order 

directs agencies to consider regulatory 

approaches that reduce burdens and 

maintain flexibility and freedom of 

choice for the public where these 

approaches are relevant, feasible, and 

consistent with regulatory objectives. 

Executive Order 13563 emphasizes 

further that regulations must be based 

on the best available science and that 

the rulemaking process must allow for 

public participation and an open 

exchange of ideas. We have developed 

this rule in a manner consistent with 

these requirements. 

OIRA bases its determination of 

significance upon the following four 

criteria: (a) Whether the rule will have 

an annual effect of $100 million or more 

on the economy or adversely affect an 

economic sector, productivity, jobs, the 

environment, or other units of the 

government; (b) whether the rule will 

create inconsistencies with other 

Federal agencies’ actions; (c) whether 

the rule will materially affect 

entitlements, grants, user fees, loan 

programs, or the rights and obligations 

of their recipients; (d) whether the rule 

raises novel legal or policy issues. 

Expenses will be related to, but not 

necessarily limited to: The development 

of requests for LOAs; monitoring, 

recordkeeping, and reporting activities 

conducted during Industry oil and gas 

operations; development of polar bear 

interaction plans; and coordination with 

Alaska Natives to minimize effects of 

operations on subsistence hunting. 


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Compliance with the rule is not 

expected to result in additional costs to 

Industry that it has not already borne 

under all previous ITRs. Realistically, 

these costs are minimal in comparison 

to those related to actual oil and gas 

exploration, development, and 

production operations. The actual costs 

to Industry to develop the request for 

promulgation of regulations and LOA 

requests probably do not exceed 

$500,000 per year, short of the ‘‘major 

rule’’ threshold that would require 

preparation of a regulatory impact 

analysis. As is presently the case, profits 

will accrue to Industry; royalties and 

taxes will accrue to the Government; 

and the rule will have little or no impact 

on decisions by Industry to relinquish 

tracts and write off bonus payments. 

Small Business Regulatory Enforcement 

Fairness Act 

We have determined that this rule is 

not a major rule under 5 U.S.C. 804(2), 

the Small Business Regulatory 

Enforcement Fairness Act. The rule is 

also not likely to result in a major 

increase in costs or prices for 

consumers, individual industries, or 

government agencies or have significant 

adverse effects on competition, 

employment, productivity, innovation, 

or on the ability of United States-based 

enterprises to compete with foreignbased enterprises in domestic or export 

markets. 

Regulatory Flexibility Act 

We have also determined that this 

rule will not have a significant 

economic effect on a substantial number 

of small entities under the Regulatory 

Flexibility Act (5 U.S.C. 601 et seq.). Oil 

companies and their contractors 

conducting exploration, development, 

and production activities in Alaska have 

been identified as the only likely 

applicants under the regulations, and 

these potential applicants have not been 

identified as small businesses. 

Therefore, neither a regulatory 

flexibility analysis nor a small entity 

compliance guide is required. 

Takings Implications 

This rule does not have takings 

implications under Executive Order 

12630 because it authorizes the 

nonlethal, incidental, but not 

intentional, take of walruses and polar 

bears by Industry and thereby, exempts 

these companies from civil and criminal 

liability as long as they operate in 

compliance with the terms of their 

LOAs. Therefore, a takings implications 

assessment is not required. 

Federalism Effects 

This rule does not contain policies 

with federalism implications sufficient 

to warrant preparation of a federalism 

assessment under Executive Order 

13132. The MMPA gives the Service the 

authority and responsibility to protect 

walruses and polar bears. 

Unfunded Mandates Reform Act 

In accordance with the Unfunded 

Mandates Reform Act (2 U.S.C. 1501 et 

seq.), this rule will not ‘‘significantly or 

uniquely’’ affect small governments. A 

Small Government Agency Plan is not 

required. The Service has determined 

and certifies pursuant to the Unfunded 

Mandates Reform Act that this 

rulemaking will not impose a cost of 

$100 million or more in any given year 

on local or State governments or private 

entities. This rule will not produce a 

Federal mandate of $100 million or 

greater in any year, i.e., it is not a 

‘‘significant regulatory action’’ under 

the Unfunded Mandates Reform Act. 

Government-to-Government 

Coordination 

It is our responsibility to 

communicate and work directly on a 

Government-to-Government basis with 

federally recognized Tribes in 

developing programs for healthy 

ecosystems. We are also required to 

consult with Alaska Native 

Corporations. We seek their full and 

meaningful participation in evaluating 

and addressing conservation concerns 

for protected species. It is our goal to 

remain sensitive to Alaska Native 

culture and to make information 

available to Alaska Natives. Our efforts 

are guided by the following policies and 

directives: 

(1) The Native American Policy of the 

Service (January 20, 2016); 

(2) the Alaska Native Relations Policy 

(currently in draft form); 

(3) Executive Order 13175 (January 9, 

2000); 

(4) Department of the Interior 

Secretarial Orders 3206 (June 5, 1997), 

3225 (January 19, 2001), 3317 

(December 1, 2011), and 3342 (October 

21, 2016); 

(5) the Department of the Interior’s 

policies on consultation with Tribes and 

with Alaska Native Corporations; and 

(6) the Presidential Memorandum on 

Tribal Consultation and Strengthening 

Nation-to-Nation Relationships (January 

21, 2021). 

We have evaluated possible effects of 

the ITR on federally recognized Alaska 

Native Tribes and corporations and have 

concluded the issuance of the ITR does 

not require formal consultation with 

Alaska Native Tribes and corporations. 

Through the ITR process identified in 

the MMPA, the AOGA has presented a 

communication process, culminating in 

a POC if needed, with the Native 

organizations and communities most 

likely to be affected by their work. The 

applicant has engaged these groups in 

informational communications. We 

invite continued discussion about the 

ITR and sent an outreach letter 

regarding this ITR to Alaska Native 

Tribes and corporations on May 27, 

2021. 

In addition, to facilitate comanagement activities, the Service 

maintains cooperative agreements with 

the Eskimo Walrus Commission (EWC) 

and the Qayassiq Walrus Commission 

(QWC) and is working towards 

developing such an agreement with the 

newly formed Alaska Nannut CoManagement Council (ANCC). The 

cooperative agreements fund a wide 

variety of management issues, 

including: Commission co-management 

operations; biological sampling 

programs; harvest monitoring; collection 

of Native knowledge in management; 

international coordination on 

management issues; cooperative 

enforcement of the MMPA; and 

development of local conservation 

plans. To help realize mutual 

management goals, the Service, EWC, 

ANCC, and QWC regularly hold 

meetings to discuss future expectations 

and outline a shared vision of comanagement. 

The Service also has ongoing 

cooperative relationships with the North 

Slope Borough and the InupiatInuvialuit Game Commission where we 

work cooperatively to ensure that data 

collected from harvest and research are 

used to ensure that polar bears are 

available for harvest in the future; 

provide information to co-management 

partners that allows them to evaluate 

harvest relative to their management 

agreements and objectives; and provide 

information that allows evaluation of 

the status, trends, and health of polar 

bear subpopulations. 

Civil Justice Reform 

The Department’s Office of the 

Solicitor has determined that these 

regulations do not unduly burden the 

judicial system and meet the applicable 

standards provided in sections 3(a) and 

3(b)(2) of Executive Order 12988. 

Paperwork Reduction Act 

This rule does not contain any new 

collections of information that require 

approval by the Office of Management 

and Budget (OMB) under the Paperwork 

Reduction Act of 1995 (44 U.S.C. 3501 


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et seq.). OMB has previously approved 

the information collection requirements 

associated with incidental take of 

marine mammals and assigned OMB 

control number 1018–0070 (expires 

January 31, 2022). An agency may not 

conduct or sponsor, and a person is not 

required to respond to, a collection of 

information unless it displays a 

currently valid OMB control number. 

Energy Effects 

Executive Order 13211 requires 

agencies to prepare statements of energy 

effects when undertaking certain 

actions. This rule provides exceptions 

from the MMPA’s taking prohibitions 

for Industry engaged in specified oil and 

gas activities in the specified geographic 

region. By providing certainty regarding 

compliance with the MMPA, this rule 

will have a positive effect on Industry 

and its activities. Although the rule 

requires Industry to take a number of 

actions, these actions have been 

undertaken by Industry for many years 

as part of similar past regulations. 

Therefore, this rule is not expected to 

significantly affect energy supplies, 

distribution, or use and does not 

constitute a significant energy action. 

No statement of energy effects is 

required. 

References 

For a list of the references cited in this 

rule, see Docket No. FWS–R7–ES–2021– 

0037, available at http://

www.regulations.gov. 

List of Subjects in 50 CFR Part 18 

Administrative practice and 

procedure, Alaska, Imports, Indians, 

Marine mammals, Oil and gas 

exploration, Reporting and 

recordkeeping requirements, 

Transportation. 

Regulation Promulgation 

For the reasons set forth in the 

preamble, the Service amends part 18, 

subchapter B of chapter I, title 50 of the 

Code of Federal Regulations as set forth 

below. 

PART 18—MARINE MAMMALS 

■ 1. The authority citation of part 18 

continues to read as follows: 

Authority: 16 U.S.C. 1361 et seq. 

■ 2. Revise subpart J of part 18 to read 

as follows: 

Subpart J—Nonlethal Taking of Marine 

Mammals Incidental to Oil and Gas 

Exploration, Development, and 

Production Activities in the Beaufort 

Sea and Adjacent Northern Coast of 

Alaska 

Sec. 

18.119 Specified activities covered by this 

subpart. 

18.120 Specified geographic region where 

this subpart applies. 

18.121 Dates this subpart is in effect. 

18.122 Procedure to obtain a Letter of 

Authorization (LOA). 

18.123 How the Service will evaluate a 

request for a Letter of Authorization 

(LOA). 

18.124 Authorized take allowed under a 

Letter of Authorization (LOA). 

18.125 Prohibited take under a Letter of 

Authorization (LOA). 

18.126 Mitigation. 

18.127 Monitoring. 

18.128 Reporting requirements. 

18.129 Information collection requirements. 

§ 18.119 Specified activities covered by 

this subpart. 

Regulations in this subpart apply to 

the nonlethal incidental, but not 

intentional, take of small numbers of 

polar bear and Pacific walrus by certain 

U.S. citizens while engaged in oil and 

gas exploration, development, and 

production activities in the Beaufort Sea 

and adjacent northern coast of Alaska. 

§ 18.120 Specified geographic region 

where this subpart applies. 

This subpart applies to the specified 

geographic region that encompasses all 

Beaufort Sea waters east of a northsouth line through Point Barrow, Alaska 

(N71.39139, W156.475, BGN 1944), and 

80.5 km (50 mi) north of Point Barrow, 

including Alaska State waters and Outer 

Continental Shelf waters, and east of 

that line to the Canadian border. 

(a) The offshore boundary of the 

Beaufort Sea incidental take regulations 

(ITR) region extends 80.5 km (50 mi) 

offshore. The onshore region is the same 

north/south line at Utqiagvik, 40.2 km 

(25 mi) inland and east to the Canning 

River. 

(b) The Arctic National Wildlife 

Refuge and the associated offshore 

waters within the refuge boundaries are 

not included in the Beaufort Sea ITR 

region. Figure 1 shows the area where 

this subpart applies. 

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BILLING CODE 4333–15–C 

§ 18.121 Dates this subpart is in effect. 

Regulations in this subpart are 

effective from August 5, 2021, through 

August 5, 2026, for year-round oil and 

gas exploration, development, and 

production. 

§ 18.122 Procedure to obtain a Letter of 

Authorization (LOA). 

(a) An applicant must be a U.S. 

citizen as defined in § 18.27(c) and 

among: 

(1) Those entities specified in the 

request for this rule as set forth in 

paragraph (b) of this section; 

(2) Any of their corporate affiliates; or 

(3) Any of their respective contractors, 

subcontractors, partners, owners, colessees, designees, or successors-ininterest. 

(b) The entities specified in the 

request are the Alaska Oil and Gas 

Association, which includes Alyeska 

Pipeline Service Company, BlueCrest 

Energy, Inc., Chevron Corporation, 

ConocoPhillips Alaska, Inc., Eni U.S. 

Operating Co. Inc., ExxonMobil Alaska 

Production Inc., Furie Operating Alaska, 

LLC, Glacier Oil and Gas Corporation, 

Hilcorp Alaska, LLC, Marathon 

Petroleum, Petro Star Inc., Repsol, and 

Shell Exploration and Production 

Company, Alaska Gasline Development 

Corporation, Arctic Slope Regional 

Corporation Energy Services, Oil Search 

(Alaska), LLC, and Qilak LNG, Inc. 

(c) If an applicant proposes to conduct 

oil and gas industry exploration, 

development, and production in the 

Beaufort Sea ITR region described in 

§ 18.120 that may cause the taking of 

Pacific walruses and/or polar bears and 

wants nonlethal incidental take 

authorization under the regulations in 

this subpart J, the applicant must 

request an LOA. The applicant must 

submit the request for authorization to 

the Service’s Alaska Region Marine 

Mammals Management Office (see § 2.2 

for address) at least 90 days prior to the 

start of the activity. 

(d) The request for an LOA must 

comply with the requirements set forth 

in §§ 18.126 through 18.128 and must 

include the following information: 

(1) A plan of operations that describes 

in detail the activity (e.g., type of 

project, methods, and types and 

numbers of equipment and personnel, 

etc.), the dates and duration of the 

activity, and the specific locations of 

and areas affected by the activity. 

(2) A site-specific marine mammal 

monitoring and mitigation plan to 

monitor and mitigate the effects of the 

activity on Pacific walruses and polar 

bears. 

(3) A site-specific Pacific walrus and 

polar bear safety, awareness, and 

interaction plan. The plan for each 

activity and location will detail the 


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Figure 1 to§ 18.120-Map ofthe Beaufort SeaITRregion 

120 Miles 
43072 Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations 

policies and procedures that will 

provide for the safety and awareness of 

personnel, avoid interactions with 

Pacific walruses and polar bears, and 

minimize impacts to these animals. 

(4) A plan of cooperation to mitigate 

potential conflicts between the activity 

and subsistence hunting, where 

relevant. Applicants must provide 

documentation of communication with 

potentially affected subsistence 

communities along the Beaufort Sea 

coast (i.e., Kaktovik, Nuiqsut, and 

Utqigvik) and appropriate subsistence 

user organizations (i.e., the Alaska 

Nannut Co-Management Council, the 

Eskimo Walrus Commission, or North 

Slope Borough) to discuss the location, 

timing, and methods of activities and 

identify and mitigate any potential 

conflicts with subsistence walrus and 

polar bear hunting activities. Applicants 

must specifically inquire of relevant 

communities and organizations if the 

activity will interfere with the 

availability of Pacific walruses and/or 

polar bears for the subsistence use of 

those groups. Requests for an LOA must 

include documentation of all 

consultations with potentially affected 

user groups. Documentation must 

include a summary of any concerns 

identified by community members and 

hunter organizations and the applicant’s 

responses to identified concerns. 

§ 18.123 How the Service will evaluate a 

request for a Letter of Authorization (LOA). 

(a) We will evaluate each request for 

an LOA based on the specific activity 

and the specific geographic location. We 

will determine whether the level of 

activity identified in the request exceeds 

that analyzed by us in considering the 

number of animals estimated to be taken 

and evaluating whether there will be a 

negligible impact on the species or stock 

and an unmitigable adverse impact on 

the availability of the species or stock 

for subsistence uses. If the level of 

activity is greater, we will reevaluate 

our findings to determine if those 

findings continue to be appropriate 

based on the combined estimated take of 

the greater level of activity that the 

applicant has requested and all other 

activities proposed during the time of 

the activities in the LOA request. 

Depending on the results of the 

evaluation, we may grant the 

authorization, add further conditions, or 

deny the authorization. 

(b) In accordance with § 18.27(f)(5), 

we will make decisions concerning 

withdrawals of an LOA, either on an 

individual or class basis, only after 

notice and opportunity for public 

comment. 

(c) The requirement for notice and 

public comment in paragraph (b) of this 

section will not apply should we 

determine that an emergency exists that 

poses a significant risk to the well-being 

of the species or stocks of polar bears or 

Pacific walruses. 

§ 18.124 Authorized take allowed under a 

Letter of Authorization (LOA). 

(a) An LOA allows for the nonlethal, 

non-injurious, incidental, but not 

intentional take by Level B harassment, 

as defined in § 18.3 and under section 

3 of the Marine Mammal Protection Act 

(16 U.S.C. 1362), of Pacific walruses 

and/or polar bears while conducting oil 

and gas industry exploration, 

development, and production within 

the Beaufort Sea ITR region described in 

§ 18.120. 

(b) Each LOA will identify terms and 

conditions for each activity and 

location. 

§ 18.125 Prohibited take under a Letter of 

Authorization (LOA). 

Except as otherwise provided in this 

subpart, prohibited taking is described 

in § 18.11 as well as: 

(a) Intentional take, Level A 

harassment, as defined in section 3 of 

the Marine Mammal Protection Act (16 

U.S.C. 1362), and lethal incidental take 

of polar bears or Pacific walruses; and 

(b) Any take that fails to comply with 

this subpart or with the terms and 

conditions of an LOA. 

§ 18.126 Mitigation. 

(a) Mitigation measures for all Letters 

of Authorization (LOAs). Holders of an 

LOA must implement policies and 

procedures to conduct activities in a 

manner that affects the least practicable 

adverse impact on Pacific walruses and/ 

or polar bears, their habitat, and the 

availability of these marine mammals 

for subsistence uses. Adaptive 

management practices, such as temporal 

or spatial activity restrictions in 

response to the presence of marine 

mammals in a particular place or time 

or the occurrence of Pacific walruses 

and/or polar bears engaged in a 

biologically significant activity (e.g., 

resting, feeding, denning, or nursing, 

among others), must be used to avoid 

interactions with and minimize impacts 

to these animals and their availability 

for subsistence uses. 

(1) All holders of an LOA must: 

(i) Cooperate with the Service’s 

Marine Mammals Management Office 

and other designated Federal, State, and 

local agencies to monitor and mitigate 

the impacts of oil and gas industry 

activities on Pacific walruses and polar 

bears. Where information is insufficient 

to evaluate the potential effects of 

activities on walruses, polar bears, and 

the subsistence use of these species, 

holders of an LOA may be required to 

participate in joint monitoring and/or 

research efforts to address these 

information needs and ensure the least 

practicable impact to these resources. 

(ii) Designate trained and qualified 

personnel to monitor for the presence of 

Pacific walruses and polar bears, initiate 

mitigation measures, and monitor, 

record, and report the effects of oil and 

gas industry activities on Pacific 

walruses and/or polar bears. 

(iii) Have an approved Pacific walrus 

and polar bear safety, awareness, and 

interaction plan on file with the 

Service’s Marine Mammals Management 

Office and onsite and provide polar bear 

awareness training to certain personnel. 

Interaction plans must include: 

(A) The type of activity and where 

and when the activity will occur (i.e., a 

summary of the plan of operation); 

(B) A food, waste, and other ‘‘bear 

attractants’’ management plan; 

(C) Personnel training policies, 

procedures, and materials; 

(D) Site-specific walrus and polar bear 

interaction risk evaluation and 

mitigation measures; 

(E) Walrus and polar bear avoidance 

and encounter procedures; and 

(F) Walrus and polar bear observation 

and reporting procedures. 

(2) All applicants for an LOA must 

contact affected subsistence 

communities and hunter organizations 

to discuss potential conflicts caused by 

the activities and provide the Service 

documentation of communications as 

described in § 18.122. 

(b) Mitigation measures for onshore 

activities. Holders of an LOA must 

undertake the following activities to 

limit disturbance around known polar 

bear dens: 

(1) Attempt to locate polar bear dens. 

Holders of an LOA seeking to carry out 

onshore activities during the denning 

season (November–April) must conduct 

two separate surveys for occupied polar 

bear dens in all denning habitat within 

1.6 km (1 mi) of proposed activities 

using aerial infrared (AIR) imagery. 

Further, all denning habitat within 1.6 

km (1 mi) of areas of proposed seismic 

surveys must be surveyed three separate 

times with AIR technology. 

(i) The first survey must occur 

between the dates of November 25 and 

December 15, the second between the 

dates of December 5 and December 31, 

and the third (if required) between the 

dates of December 15 and January 15. 

(ii) AIR surveys will be conducted 

during darkness or civil twilight and not 

during daylight hours. Ideal 


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environmental conditions during 

surveys would be clear, calm, and cold. 

If there is blowing snow, any form of 

precipitation, or other sources of 

airborne moisture, use of AIR detection 

is not advised. Flight crews will record 

and report environmental parameters 

including air temperature, dew point, 

wind speed and direction, cloud ceiling, 

and percent humidity, and a flight log 

will be provided to the Service within 

48 hours of the flight. 

(iii) A scientist with experience in the 

in-air interpretation of AIR imagery will 

be on board the survey aircraft to 

analyze the AIR data in real-time. The 

data (infrared video) will be made 

available for viewing by the Service 

immediately upon return of the survey 

aircraft to the base of operations. 

(iv) All observed or suspected polar 

bear dens must be reported to the 

Service prior to the initiation of 

activities. 

(2) Observe the exclusion zone around 

known polar bear dens. Operators must 

observe a 1.6-km (1-mi) operational 

exclusion zone around all putative polar 

bear dens during the denning season 

(November–April, or until the female 

and cubs leave the areas). Should 

previously unknown occupied dens be 

discovered within 1 mile of activities, 

work must cease, and the Service 

contacted for guidance. The Service will 

evaluate these instances on a case-bycase basis to determine the appropriate 

action. Potential actions may range from 

cessation or modification of work to 

conducting additional monitoring, and 

the holder of the authorization must 

comply with any additional measures 

specified. 

(3) Use the den habitat map 

developed by the USGS. A map of 

potential coastal polar bear denning 

habitat can be found at: https://

www.usgs.gov/centers/asc/science/ 

polar-bear-maternal-denning?qtscience_center_objects=4#qt-science_

center_objects. This measure ensures 

that the location of potential polar bear 

dens is considered when conducting 

activities in the coastal areas of the 

Beaufort Sea. 

(4) Polar bear den restrictions. Restrict 

the timing of the activity to limit 

disturbance around dens, including 

putative and known dens. 

(c) Mitigation measures for 

operational and support vessels. (1) 

Operational and support vessels must be 

staffed with dedicated marine mammal 

observers to alert crew of the presence 

of walruses and polar bears and initiate 

adaptive mitigation responses. 

(2) At all times, vessels must maintain 

the maximum distance possible from 

concentrations of walruses or polar 

bears. Under no circumstances, other 

than an emergency, should any vessel 

approach within an 805-m (0.5-mi) 

radius of walruses or polar bears 

observed on land or ice. 

(3) Vessel operators must take every 

precaution to avoid harassment of 

concentrations of feeding walruses 

when a vessel is operating near these 

animals. Vessels should reduce speed 

and maintain a minimum 805-m (0.5- 

mi) operational exclusion zone around 

feeding walrus groups. Vessels may not 

be operated in such a way as to separate 

members of a group of walruses (i.e., 

greater than two) from other members of 

the group. When weather conditions 

require, such as when visibility drops, 

vessels should adjust speed accordingly 

to avoid the likelihood of injury to 

walruses. 

(4) Vessels bound for the Beaufort Sea 

ITR region may not transit through the 

Chukchi Sea prior to July 1. This 

operating condition is intended to allow 

walruses the opportunity to move 

through the Bering Strait and disperse 

from the confines of the spring lead 

system into the Chukchi Sea with 

minimal disturbance. It is also intended 

to minimize vessel impacts upon the 

availability of walruses for Alaska 

Native subsistence hunters. Exemption 

waivers to this operating condition may 

be issued by the Service on a case-bycase basis, based upon a review of 

seasonal ice conditions and available 

information on walrus and polar bear 

distributions in the area of interest. 

(5) All vessels must avoid areas of 

active or anticipated walrus or polar 

bear subsistence hunting activity as 

determined through community 

consultations. 

(6) In association with marine 

activities, we may require trained 

marine mammal monitors on the site of 

the activity or onboard ships, aircraft, 

icebreakers, or other support vessels or 

vehicles to monitor the impacts of oil 

and gas industry activity on polar bear 

and Pacific walruses. 

(d) Mitigation measures for aircraft. 

(1) Operators of support aircraft shall, at 

all times, conduct their activities at the 

maximum distance possible from 

concentrations of walruses or polar 

bears. 

(2) Aircraft operations within the ITR 

area will maintain an altitude of 1,500 

ft above ground level when safe and 

operationally possible. 

(3) Under no circumstances, other 

than an emergency, will aircraft operate 

at an altitude lower than 457 m (1,500 

ft) within 805 m (0.5 mi) of walruses or 

polar bears observed on ice or land. 

Helicopters may not hover or circle 

above such areas or within 805 m (0.5 

mi) of such areas. When weather 

conditions do not allow a 457-m (1,500- 

ft) flying altitude, such as during severe 

storms or when cloud cover is low, 

aircraft may be operated below this 

altitude. However, when weather 

conditions necessitate operation of 

aircraft at altitudes below 457 m (1,500 

ft), the operator must avoid areas of 

known walrus and polar bear 

concentrations and will take 

precautions to avoid flying directly over 

or within 805 m (0.5 mile) of these 

areas. 

(4) Plan all aircraft routes to minimize 

any potential conflict with active or 

anticipated walrus or polar bear hunting 

activity as determined through 

community consultations. 

(e) Mitigation measures for the 

subsistence use of walruses and polar 

bears. Holders of an LOA must conduct 

their activities in a manner that, to the 

greatest extent practicable, minimizes 

adverse impacts on the availability of 

Pacific walruses and polar bears for 

subsistence uses. 

(1) Community consultation. Prior to 

receipt of an LOA, applicants must 

consult with potentially affected 

communities and appropriate 

subsistence user organizations to 

discuss potential conflicts with 

subsistence walrus and polar bear 

hunting caused by the location, timing, 

and methods of operations and support 

activities (see § 18.122 for details). If 

community concerns suggest that the 

activities may have an adverse impact 

on the subsistence uses of these species, 

the applicant must address conflict 

avoidance issues through a plan of 

cooperation as described in paragraph 

(e)(2) of this section. 

(2) Plan of cooperation (POC). When 

appropriate, a holder of an LOA will be 

required to develop and implement a 

Service-approved POC. 

(i) The POC must include a 

description of the procedures by which 

the holder of the LOA will work and 

consult with potentially affected 

subsistence hunters and a description of 

specific measures that have been or will 

be taken to avoid or minimize 

interference with subsistence hunting of 

walruses and polar bears and to ensure 

continued availability of the species for 

subsistence use. 

(ii) The Service will review the POC 

to ensure that any potential adverse 

effects on the availability of the animals 

are minimized. The Service will reject 

POCs if they do not provide adequate 

safeguards to ensure the least 

practicable adverse impact on the 

availability of walruses and polar bears 

for subsistence use. 


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§ 18.127 Monitoring. 

Holders of an LOA must develop and 

implement a site-specific, Serviceapproved marine mammal monitoring 

and mitigation plan to monitor and 

evaluate the effectiveness of mitigation 

measures and the effects of activities on 

walruses, polar bears, and the 

subsistence use of these species and 

provide trained, qualified, and Serviceapproved onsite observers to carry out 

monitoring and mitigation activities 

identified in the marine mammal 

monitoring and mitigation plan. 

§ 18.128 Reporting requirements. 

Holders of a Letter of Authorization 

(LOA) must report the results of 

monitoring and mitigation activities to 

the Service’s Marine Mammals 

Management Office via email at: fw7_

mmm_reports@fws.gov. 

(a) In-season monitoring reports. (1) 

Activity progress reports. Holders of an 

LOA must: 

(i) Notify the Service at least 48 hours 

prior to the onset of activities; 

(ii) Provide the Service weekly 

progress reports of any significant 

changes in activities and/or locations; 

and 

(iii) Notify the Service within 48 

hours after ending of activities. 

(2) Walrus observation reports. 

Holders of an LOA must report, on a 

weekly basis, all observations of 

walruses during any industry activity. 

Upon request, monitoring report data 

must be provided in a common 

electronic format (to be specified by the 

Service). Information in the observation 

report must include, but is not limited 

to: 

(i) Date, time, and location of each 

walrus sighting; 

(ii) Number of walruses; 

(iii) Sex and age (if known); 

(iv) Observer name and contact 

information; 

(v) Weather, visibility, sea state, and 

sea-ice conditions at the time of 

observation; 

(vi) Estimated range at closest 

approach; 

(vii) Industry activity at time of 

sighting; 

(viii) Behavior of animals sighted; 

(ix) Description of the encounter; 

(x) Duration of the encounter; and 

(xi) Mitigation actions taken. 

(3) Polar bear observation reports. 

Holders of an LOA must report, within 

48 hours, all observations of polar bears 

and potential polar bear dens, during 

any industry activity. Upon request, 

monitoring report data must be 

provided in a common electronic format 

(to be specified by the Service). 

Information in the observation report 

must include, but is not limited to: 

(i) Date, time, and location of 

observation; 

(ii) Number of bears; 

(iii) Sex and age of bears (if known); 

(iv) Observer name and contact 

information; 

(v) Weather, visibility, sea state, and 

sea-ice conditions at the time of 

observation; 

(vi) Estimated closest distance of 

bears from personnel and facilities; 

(vii) Industry activity at time of 

sighting; 

(viii) Possible attractants present; 

(ix) Bear behavior; 

(x) Description of the encounter; 

(xi) Duration of the encounter; and 

(xii) Mitigation actions taken. 

(b) Notification of LOA incident 

report. Holders of an LOA must report, 

as soon as possible, but within 48 hours, 

all LOA incidents during any industry 

activity. An LOA incident is any 

situation when specified activities 

exceed the authority of an LOA, when 

a mitigation measure was required but 

not enacted, or when injury or death of 

a walrus or polar bear occurs. Reports 

must include: 

(1) All information specified for an 

observation report; 

(2) A complete detailed description of 

the incident; and 

(3) Any other actions taken. 

(c) Final report. The results of 

monitoring and mitigation efforts 

identified in the marine mammal 

monitoring and mitigation plan must be 

submitted to the Service for review 

within 90 days of the expiration of an 

LOA, or for production LOAs, an annual 

report by January 15th of each calendar 

year. Upon request, final report data 

must be provided in a common 

electronic format (to be specified by the 

Service). Information in the final (or 

annual) report must include, but is not 

limited to: 

(1) Copies of all observation reports 

submitted under the LOA; 

(2) A summary of the observation 

reports; 

(3) A summary of monitoring and 

mitigation efforts including areas, total 

hours, total distances, and distribution; 

(4) Analysis of factors affecting the 

visibility and detectability of walruses 

and polar bears during monitoring; 

(5) Analysis of the effectiveness of 

mitigation measures; 

(6) Analysis of the distribution, 

abundance, and behavior of walruses 

and/or polar bears observed; and 

(7) Estimates of take in relation to the 

specified activities. 

§ 18.129 Information collection 

requirements. 

(a) We may not conduct or sponsor 

and a person is not required to respond 

to a collection of information unless it 

displays a currently valid Office of 

Management and Budget (OMB) control 

number. OMB has approved the 

collection of information contained in 

this subpart and assigned OMB control 

number 1018–0070. You must respond 

to this information collection request to 

obtain a benefit pursuant to section 

101(a)(5) of the Marine Mammal 

Protection Act. We will use the 

information to: 

(1) Evaluate the request and 

determine whether or not to issue 

specific Letters of Authorization; and 

(2) Monitor impacts of activities and 

effectiveness of mitigation measures 

conducted under the Letters of 

Authorization. 

(b) Comments regarding the burden 

estimate or any other aspect of this 

requirement must be submitted to the 

Information Collection Clearance 

Officer, U.S. Fish and Wildlife Service, 

at the address listed in 50 CFR 2.1. 

Shannon A. Estenoz, 

Assistant Secretary for Fish and Wildlife and 

Parks. 

[FR Doc. 2021–16452 Filed 8–4–21; 8:45 am] 

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