[Federal Register Volume 84, Number 103 (Wednesday, May 29, 2019)]
[Proposed Rules]
[Pages 24926-24968]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-10965]



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Vol. 84

Wednesday,

No. 103

May 29, 2019

Part III





 Department of Commerce





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National Oceanic and Atmospheric Administration





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50 CFR Part 217





 Taking and Importing Marine Mammals; Taking Marine Mammals Incidental 
to Construction and Operation of the Liberty Drilling and Production 
Island, Beaufort Sea, Alaska; Proposed Rule

  Federal Register / Vol. 84 , No. 103 / Wednesday, May 29, 2019 / 
Proposed Rules  

[[Page 24926]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 217

[Docket No. 180627584-9388-01]
RIN 0648-BI00


Taking and Importing Marine Mammals; Taking Marine Mammals 
Incidental to Construction and Operation of the Liberty Drilling and 
Production Island, Beaufort Sea, Alaska

AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and 
Atmospheric Administration (NOAA), Commerce.

ACTION: Proposed rule; request for comments.

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SUMMARY: NMFS has received a request from Hilcorp Alaska (Hilcorp) for 
authorization to take marine mammals incidental to construction and 
operation of the Liberty Drilling and Production Island (LDPI), over 
the course of five years. Pursuant to the Marine Mammal Protection Act 
(MMPA), NMFS is proposing regulations to govern that take, and requests 
comments on the proposed regulations. NMFS will consider public 
comments prior to making any final decision on the issuance of the 
requested MMPA authorization and agency responses will be summarized in 
the final notice of our decision.

DATES: Comments and information must be received no later than June 28, 
2019.

ADDRESSES: You may submit comments on this document, identified by 
NOAA-NMFS-2018-0053, by any of the following methods:
     Electronic submission: Submit all electronic public 
comments via the Federal e-Rulemaking Portal. Go to 
www.regulations.gov/#!docketDetail;D=NOAA-NMFS-2019-0053 click the 
``Comment Now!'' icon, complete the required fields, and enter or 
attach your comments.
     Mail: Submit written comments to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service, 1315 East West Highway, Silver 
Spring, MD 20910.
    Instructions: Comments sent by any other method, to any other 
address or individual, or received after the end of the comment period, 
may not be considered by NMFS. All comments received are a part of the 
public record and will generally be posted for public viewing on 
www.regulations.gov without change. All personal identifying 
information (e.g., name, address), confidential business information, 
or otherwise sensitive information submitted voluntarily by the sender 
will be publicly accessible. NMFS will accept anonymous comments (enter 
``N/A'' in the required fields if you wish to remain anonymous). 
Attachments to electronic comments will be accepted in Microsoft Word, 
Excel, or Adobe PDF file formats only.

FOR FURTHER INFORMATION CONTACT: Jaclyn Daly, Office of Protected 
Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Availability

    A copy of Hilcorp's application and any supporting documents, as 
well as a list of the references cited in this document, may be 
obtained online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act. In case of 
problems accessing these documents, please call the contact listed 
above (see FOR FURTHER INFORMATION CONTACT).

Purpose and Need for Regulatory Action

    NMFS received an application from Hilcorp requesting five-year 
regulations and authorization to incidentally take multiple species of 
marine mammals in Foggy Island Bay, Beaufort Sea, by Level A harassment 
(non-serious injury) and Level B harassment (behavioral disturbance), 
incidental to construction and operation of the LDPI and associated 
infrastructure. Please see ``Background'' below for definitions of 
harassment. In addition, a limited unintentional take involving the 
mortality or serious injury of no more than two ringed seals (Phoca 
hispida) would be authorized to occur during annual ice road 
construction and maintenance. This proposed rule establishes a 
framework under the authority of the MMPA (16 U.S.C. 1361 et seq.) to 
allow for the authorization of take of marine mammals incidental to 
Hilcorp's activities related to construction and operation of the LDPI.

Legal Authority for the Proposed Action

    Section 101(a)(5)(A) of the MMPA (16 U.S.C. 1371(a)(5)(A)) directs 
the Secretary of Commerce to allow, upon request, the incidental, but 
not intentional taking of small numbers of marine mammals by U.S. 
citizens who engage in a specified activity (other than commercial 
fishing) within a specified geographical region for up to five years 
if, after notice and public comment, the agency makes certain findings 
and issues regulations that set forth permissible methods of taking 
pursuant to that activity and other means of effecting the ``least 
practicable adverse impact'' on the affected species or stocks and 
their habitat (see the discussion below in the ``Proposed Mitigation'' 
section), as well as monitoring and reporting requirements. Section 
101(a)(5)(A) of the MMPA and the implementing regulations at 50 CFR 
part 216, subpart I provide the legal basis for issuing this proposed 
rule containing five-year regulations, and for any subsequent Letters 
of Authorization (LOAs). As directed by this legal authority, this 
proposed rule contains mitigation, monitoring, and reporting 
requirements.

Summary of Major Provisions Within the Proposed Rule

    Following is a summary of the major provisions of this proposed 
rule Hilcorp would be required to implement. These measures include:
     Use of soft start during impact pile driving to allow 
marine mammals the opportunity to leave the area prior to beginning 
impact pile driving at full power;
     Implementation of shutdowns of construction activities 
under certain circumstances to minimize harassment, including injury;
     Prohibition on impact pile driving during the fall Cross 
Island bowhead whale hunt and seasonal drilling restrictions to 
minimize impacts to marine mammals and subsistence users;
     Implementation of best management practices to avoid and 
minimize ice seal and habitat disturbance during ice road construction, 
maintenance, and use;
     Use of marine mammal and acoustic monitoring to detect 
marine mammals and verify predicted sound fields;
     Coordination with subsistence users and adherence to a 
Plan of Cooperation (POC); and
     Limitation on vessel speeds and transit areas, where 
appropriate.

Background

    The MMPA prohibits the take of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are issued or, if the taking is limited to

[[Page 24927]]

harassment, a notice of a proposed incidental take authorization is 
provided to the public for review. Under the MMPA, ``take'' is defined 
as meaning to harass, hunt, capture, or kill, or attempt to harass, 
hunt, capture, or kill any marine mammal. ``Harassment'' is statutorily 
defined as any act of pursuit, torment, or annoyance which has the 
potential to injure a marine mammal or marine mammal stock in the wild 
(Level A harassment) or has the potential to disturb a marine mammal or 
marine mammal stock in the wild by causing disruption of behavioral 
patterns, including, but not limited to, migration, breathing, nursing, 
breeding, feeding, or sheltering but which does not have the potential 
to injure a marine mammal or marine mammal stock in the wild (Level B 
harassment).
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other ``means of effecting the least practicable 
[adverse] impact'' on the affected species or stocks and their habitat, 
paying particular attention to rookeries, mating grounds, and areas of 
similar significance, and on the availability of such species or stocks 
for taking for certain subsistence uses (referred to in shorthand as 
``mitigation''); and requirements pertaining to the mitigation, 
monitoring and reporting of such takings are set forth.

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must evaluate our proposed action (i.e., the promulgation of 
regulations and subsequent issuance of incidental take authorization) 
and alternatives with respect to potential impacts on the human 
environment.
    On August 23, 2018, the Bureau of Ocean Energy Management (BOEM) 
released a Final Environmental Impact Statement (EIS) analyzing the 
possible environmental impacts of Hilcorp's proposed Liberty 
development and production plan (DPP). BOEM's Draft EIS was made 
available for public comment from August 18, 2017 through December 8, 
2017. The final EIS may be found at https://www.boem.gov/hilcorp-liberty/. NMFS is a cooperating agency on the EIS. Accordingly, NMFS 
plans to adopt the EIS, provided our independent evaluation of the 
document finds that it includes adequate information analyzing the 
effects on the human environment of issuing the rule. We will review 
all comments submitted in response to this notice prior to concluding 
our NEPA process or making a final decision on the regulations request.

Summary of Request

    On August 2, 2017, Hilcorp petitioned NMFS for rulemaking under 
Section 101(a)(5)(A) of the MMPA to authorize the take of six species 
of marine mammals incidental to construction and operation of the 
proposed LDPI in Foggy Island Bay, Alaska. On April 26, 2018, Hilcorp 
submitted a revised petition which NMFS deemed adequate and complete. 
On May 9, 2018, we published a notice of receipt of Hilcorp's petition 
in the Federal Register, requesting comments and information related to 
the request for thirty days (83 FR 21276). We received comments from 
the Center for Biological Diversity and 15,843 citizens opposing 
issuance of the requested regulations and LOA. We also received 
comments from the Alaska Eskimo Whaling Commission (AEWC) who 
recommended we include subsistence related mitigation and coordination 
requirements in the final rule. The comments and information received 
were considered in development of this proposed rule and are available 
online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act. More recently, 
Hilcorp provided subsequent additional information, including details 
on a previously undescribed component of the project (installation of 
foundation piles in the interior of the LDPI), and revised marine 
mammal density and estimate take numbers on February 4, 2019. Hilcorp 
also updated their proposed Marine Mammal Mitigation and Monitoring 
Plan (4MP) on January 29, 2019.
    To extract oil and gas in the Liberty Oil Field, Hilcorp is 
proposing to construct a 9.3 acre artificial island (the LDPI) in 19 
feet (ft) (5.8 meters (m)) of water in Foggy Island Bay, approximately 
5 miles (mi) (8 kilometers (km)) north of the Kadleroshilik River and 
install supporting infrastructure (e.g., ice roads, pipeline). Ice 
roads would be constructed annually and begin December 2020. Island 
construction, which requires impact and vibratory pile driving, is 
proposed to commence and be completed in 2021. Pile driving would 
primarily occur during ice-covered season (only ice seals are present 
during this time period); however, up to two weeks of pile driving may 
occur during the open-water season. Pipeline installation is 
anticipated to occur in 2022. Drilling and production is proposed to 
occur from 2022 through 2025.
    Hilcorp requests, and NMFS is proposing to authorize, the take, by 
Level A harassment and Level B harassment, of bowhead whales (Balaena 
mysticetus), gray whales (Eschrichtius robustus), beluga whales 
(Delphinapterus leucas), ringed seals (Phoca hispida), bearded seals 
(Erignathus barbatus), and spotted seals (Phoca largha) incidental to 
LDPI construction and operation activities (e.g., pile driving, ice 
road and island construction). Hilcorp also requested, and NMFS is 
proposing to authorize, mortality and serious injury of two ringed 
seals incidental to annual ice road construction over a 5-year period. 
The proposed regulations and LOA would be valid for five years from 
December 1, 2020, through November 30, 2025.

Description of the Specified Activity

Overview

    Hilcorp is proposing to construct and operate the LDPI, a self-
contained offshore drilling and production facility located on an 
artificial gravel island. Infrastructure and facilities necessary to 
drill wells and process and export approximately 60,000 to 70,000 
barrels of oil per day to shore would be installed on the island. To 
transport oil, a pipeline from the island would be installed, tying 
into the existing Bandami pipeline located on shore between the 
Sagavanirktok and Kadleroshilik Rivers on Alaska's North Slope. To 
access the island and move vehicles and equipment, ice roads would be 
constructed annually. All island construction and pipeline installation 
would occur during winter months as much as possible; however, pile 
driving and slope protection could occur during the open water season. 
Drilling and production, once begun, would occur year round. After 
island and pipeline construction, Hilcorp would commence and continue 
drilling and production for approximately 20 to 25 years at which time 
the island would be decommissioned. The proposed regulations and LOA 
would cover the incidental take of marine mammals during LDPI 
construction and operation for the first five years of work. 
Thereafter, data collected during these five years (e.g., acoustic 
monitoring during drilling, ice road marine mammal monitoring) would 
determine

[[Page 24928]]

if future incidental take authorizations are warranted for continuing 
operations.

Dates and Duration

    The proposed regulations would be valid for a period of five years 
from December 1, 2020, through November 30, 2025. Ice road construction 
and pipeline installation would be limited to winter months. Island 
construction would be conducted primarily during winter months; 
however, given construction schedules are subject to delays for 
multiple reasons. Hilcorp anticipates, at most, up to two weeks of 
open-water pile driving may be required in the first year to complete 
any pile driving not finished during the winter. Other work such as 
island slope armoring may also occur during open-water conditions. All 
island construction would commence and is expected to be completed in 
the first year of the proposed regulations (December 2020 through 
November 2021). Pipeline installation would occur in year 2 of the 
proposed regulations (December 2021 through November 2022), while 
drilling and production would begin in year 3 and continue through the 
life of the proposed regulations. Ice road construction and maintenance 
activities would occur each winter.

Specified Geographical Region

    The Liberty field is located in Federal waters of Foggy Island Bay, 
Beaufort Sea about 8.9 km (5.5 mi) offshore in 6.1 m (20 ft) of water 
and approximately 8 to 13 km (5 to 8 mi) east of the existing Endicott 
Satellite Drilling Island (SDI) and approximately 32 km (20 mi) east of 
Prudhoe Bay. Hilcorp would construct the Liberty project on three 
leases, OCS-Y-1650, OCS-Y-1886, and OCS-Y-1585. The proposed LDPI would 
be constructed in 19 ft (5.8 m) of water about 5 mi (8 km) offshore in 
Foggy Island Bay. The LDPI and all associated infrastructure (e.g., ice 
roads) are located inside the McClure barrier island group which 
separates Foggy Island Bay from the Beaufort Sea (Figure 1).
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BILLING CODE 3510-22-C

Detailed Description of Activities

    The Liberty Prospect is located 8.85 km offshore in about 6 m of 
water, inside the Beaufort Sea's barrier islands. Hilcorp, as the 
Liberty operator, is proposing to develop the Liberty Oil Field 
reservoir, located on the Outer Continental Shelf (OCS), in Foggy 
Island Bay, Beaufort Sea, Alaska. The Liberty reservoir is the largest 
delineated but undeveloped light oil reservoir on the North Slope. It 
is projected to deliver a peak production rate of between 60,000 and 
70,000 barrels of oil per day within two years of initial production. 
Total recovery over an estimated field life of 15 to 20 years is 
predicted to be in the range of 80 to 150 million stock tank barrels of 
oil. The Liberty Oil Field leases were previously owned by BP 
Exploration Alaska, Inc. (BPXA). In April 2014, BPXA announced the sale 
of several North Slope assets to Hilcorp including the area where the 
proposed LDPI would be constructed and other existing oil production 
islands (Northstar, Endicott, Milne Point). The Liberty Project has 
many similarities to previous oil and gas islands constructed on the 
North Slope, including Endicott, Northstar and Oooguruk.
    The proposed LDPI project includes development of a mine-site to 
supply gravel for the construction of the LDPI, construction of the 
island and annual ice roads, installation of an undersea pipeline that 
reaches shore from the LDPI and then connects to the existing above-
ground Badami pipeline, drilling, production and operation (for 
simplicity, hence forward we refer to both production and operation as 
``production''). The mine site is located inland of marine mammal 
habitat over which NMFS has jurisdiction; therefore, its development 
will not be discussed further in this proposed rule as no impacts to 
marine mammals under NMFS jurisdiction would be affected by this 
project component. Here, we discuss those activities that have the 
potential to take marine mammals: Ice road construction and 
maintenance, island construction (pile driving and slope armoring), 
pipeline installation, drilling and production. We also describe 
auxiliary activities, including vessel and aircraft transportation. A 
schedule of all phases on the project and summary of equipment and 
activities involved are included in Table 1.

                      Table 1--LDPI Project Components, Schedule, and Associated Equipment
----------------------------------------------------------------------------------------------------------------
                                          Regulation
           Project component                 year                 Season               Equipment and activity
----------------------------------------------------------------------------------------------------------------
Ice road construction, use, and                    1-5  Ice-covered..............  Grader, ice auger, trucks
 maintenance.                                                                       (flood road, haul gravel,
                                                                                    general transit,
                                                                                    maintenance).
Island construction...................             * 1  Ice-covered, open water..  Impact and vibratory pile and
                                                                                    pipe driving, backhoe
                                                                                    (digging), excavator (slope
                                                                                    shaping, armor installation,
                                                                                    ditchwitch (sawing ice).
Pipeline installation.................               2  Ice-covered..............  Ditchwitch (sawing ice),
                                                                                    backhoe (digging), trucks.
Drilling and production...............             3-5  Ice-covered, open water..  Drill rig, land-based
                                                                                    equipment on island (e.g.,
                                                                                    generators).
Marine vessel and aircraft support....             1-5  Open-water, ice-covered    Barge, tugs, crew boats,
                                                         (helicopter only).         helicopter.
Emergency and oil response training...             1-5  Ice-covered, open water..  Vessels, hovercrafts, all-
                                                                                    terrain vehicles, snow
                                                                                    machines, etc.
----------------------------------------------------------------------------------------------------------------
* Hilcorp has indicated a goal to complete all LDPI construction in the first year the regulations would be
  valid; however, they may need to install foundation piles in year 2.

Ice Road and Ice Pad Construction and Maintenance

    Hilcorp will construct ice roads and perform maintenance, as 
necessary. Ice roads are a route across sea ice created by clearing and 
grading snow then pumping seawater from holes drilled through the 
floating ice. Some roads may use grounded ice. Hilcorp would clear away 
snow using a tractor, bulldozer, or similar piece of equipment then 
pump seawater from holes drilled through floating ice, and then flood 
the ice road. The ice roads will generally be constructed by pumper 
units equipped with an ice auger to drill holes in the sea ice and then 
pump water from under the ice to flood the surface of the ice. The ice 
augers and pumping units will continue to move along the ice road 
alignment to flood the entire alignment, returning to a previous area 
as soon as the flooded water has frozen. The ice road will be 
maintained and kept clean of gravel and other solids. Freshwater can be 
sprayed onto the road surface to form a cap over the main road 
structure for the top layer or to repair any cracks.
    Ice roads will be used for onshore and offshore access, installing 
the pipeline, hauling gravel used to construct the island, moving 
equipment on/off island, personnel and supply transit, etc. Ice roads 
are best constructed when weather is -20 degrees Fahrenheit (F) to -30 
degrees F, but temperatures below 0 degree F are considered adequate 
for ice road construction. Ice road construction can typically be 
initiated in mid- to late-December and roads maintained until mid-May. 
At the end of the season, ice roads will be barricaded by snow berm 
and/or slotted at the entrance to prevent access and allowed to melt 
naturally. Figure 1 shows the locations of the proposed ice roads.
     Ice road # 1 will 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 will be approximately 37 m wide (120 ft) with driving 
lane of approximately 12 m (40 ft). It would cover approximately 160 
acres of sea ice.
     Ice road # 2 (approximately 11.3 km (7 mi)) will connect 
the LDPI to the proposed Kadleroshilik River gravel mine site and then 
will continue to the juncture with the Badami ice road (which is ice 
road # 4). It will be approximately 15 m (50 ft) wide.
     Ice road # 3 (approximately 9.6 km [6 mi], termed the 
``Midpoint Access Road'') will intersect the SDI to LDPI ice road and 
the ice road between the LDPI and the mine site. It will be 
approximately 12 m (40 ft) wide.
     Ice road # 4 (approximately 19.3 km (12 mi)), located 
completely onshore, will parallel the Badami pipeline and connect the 
mine site with the Endicott road.
    All four ice roads would be constructed for the first three 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

[[Page 24930]]

mobilized to support LDPI, pipeline, and facility construction 
activities as all island construction and pipeline installation should 
be complete by year 3. Winter sea ice road/trail construction will 
begin as early as possible (typically December 1 through mid-February). 
It is anticipated that all ice road construction activities will be 
initiated prior to March 1, before the time when female ringed seals 
establish birth lairs.
    In addition to the ice roads, three ice pads are proposed to 
support construction activities (year 2 and 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 350 feet by 700 feet) 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 could also 
include spill training exercises, pipeline surveys, snow clearing, and 
work conducted by other snow vehicles such as a Pisten Bully, snow 
machine, or rollagon. Prior to March 1, these activities could occur 
outside of the delineated ice road/trail and shoulder areas.

LDPI Construction

    The LDPI will include a self-contained offshore drilling and 
production facility located on an artificial gravel island with a 
subsea pipeline to shore. The LDPI will be located approximately 8 
kilometers (km) or 5 miles (mi) offshore in Foggy Island Bay and 11.7 
km (7.3 mi) southeast of the existing SDI on the Endicott causeway (see 
Figure 1). The LDPI will be constructed of reinforced gravel in 5.8 
meters (m) (19 feet (ft)) of water and have a working surface of 
approximately 3.8 hectares (ha) (9.3 acres (ac)). A steel sheet pile 
wall would surround the island to stabilize the placed gravel and the 
island would include slope protection bench, dock and ice road access 
and a seawater intake area (Figure 2).
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BILLING CODE 3510-22-C
    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 will 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) 
will 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, bucket-dredge) and divers, Hilcorp would create a slope 
protection profile consisting of a 60-ft (18.3 m) wide bench covered 
with a linked concrete mat that

[[Page 24931]]

extends from a sheet pile wall surrounding the island to slightly above 
mean low low water (MLLW) (Figure 3). 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 will 
be overlapped and tied together side-by-side (requiring diving 
operations) to prevent the panels from separating and exposing the 
underlying gravel fill. Because 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 will be placed 
as an abrasion guard to prevent damage to the fabric by the linked mat 
armor. The concrete mat system would continue another at a 3:1 slope 
another 86.5 ft into the water, terminating at a depth of -19 ft (-5.8 
m). In total, from the sheet pile wall, the bench and concrete mat 
would extend 146.5 ft. Island slope protection is required to assure 
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 will be conducted annually during 
the open-water season to document changes in the condition of the 
island slope protection system that have occurred since the previous 
year's inspection. Any damaged material would be removed. Above-water 
activities will consist of a visual inspection of the dock and sheet 
pile enclosure, and documenting the condition of the island bench and 
ramps. The below-water slopes will be inspected by divers or if water 
clarity allows, remotely by underwater cameras contracted separately by 
Hilcorp. The results of the below water inspection will be recorded for 
repair if needed. No vessels will be required. Multi-beam bathymetry 
and side-scan sonar imagery of the below-water slopes and adjacent sea 
bottom will be acquired using a bathymetry vessel. The sidescan sonar 
would operate at a frequency between 200-400 kilohertz (kHz). The 
single-beam echosounder would operate at a frequency of about 210 kHz.

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[GRAPHIC] [TIFF OMITTED] TP29MY19.009

BILLING CODE 3510-22-C
    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. Hilcorp anticipates driving up to 20 
piles per day to a depth of 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 of impact driving to obtain final desired depth for each sheet 
pile. Per day, this equates to a maximum of 40 minutes and 2,000 
strikes of impact hammering per day. For vibratory driving, pile 
penetration speed can vary depending on ground conditions, but a 
minimum sheet pile penetration speed is 20 inches (0.5 m) per minute to 
avoid damage to pile or hammer (NASSPA 2005). For this project, the 
anticipated duration is based on a preferred penetration speed greater 
than 40 inches (1 m) 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 will be 
higher on the west side than on the east side. At the top of the sheet-
pile wall, overhanging steel ``parapet'' will be installed to prevent 
wave passage over the wall.

[[Page 24932]]

    Within the interior of the island, 16 steel conductor pipes would 
be driven to a depth of 160 ft (49 m) 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 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, Hilcorp anticipates it would take 
two hours of active pile driving per day to install a conductor pipe 
given the 5 to 8.5 hour timeframe at Northstar includes pauses in pile 
driving and occurred in deeper water requiring deeper pile depths. 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.

Pipeline Installation

    Hilcorp would install a pipe-in-pipe subsea pipeline consisting of 
a 12-in diameter inner pipe and a 16-in diameter outer pipe to 
transport oil from the LDPI to the existing Bandami 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 
will extend from the LDPI, across Foggy Island Bay, and terminate 
onshore at the existing Badami Pipeline tie-in location. For the marine 
segment, construction will progress from shallower water to deeper 
water with multiple construction spreads.
    To install the pipeline, a trench will be excavated using ice-road 
based long reach excavators with pontoon tracks. The pipeline bundle 
will be lowered into the trench using side booms to control its 
vertical and horizontal position, and the trench will be backfilled by 
excavators using excavated trench spoils and select backfill. Hilcorp 
intends to place all material back in the trench slot. All work will be 
done from ice roads using conventional excavation and dirt-moving 
construction equipment. The target trench depth is 9 to 11 ft (2.7 to 
3.4 m) with a proposed maximum depth of cover of approximately 7 ft 
(2.1 m). The pipeline will be approximately 5.6 mi (9 km) long. Hydro-
testing (pressure testing using sea water) of the entire pipeline will 
be completed prior to commissioning.

Drilling and Production

    The final drill rig has yet to be chosen by Hilcorp but has been 
narrowed to two options and will 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 to not only 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. We note that while 
Hilcorp is proposing a 16 well design, only 10 wells would be drilled. 
The 6 additional well slots would be available as backups or for 
potential in-fill drilling if needed during the project life.
    Process facilities on the island will separate crude oil from 
produced water and gas. Gas and water will be injected into the 
reservoir to provide pressure support and increase recovery from the 
field. A single-phase subsea pipe-in-pipe pipeline will transport 
sales-quality crude from the LDPI to shore, where an aboveground 
pipeline will transport crude to the existing Badami pipeline. From 
there, crude will be transported to the Endicott Sales Oil Pipeline, 
which ties into Pump Station 1 of the TransAlaska Pipeline System 
(TAPS) for eventual delivery to a refinery.

Description of Marine Mammals in the Area of the Specified Activity

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history of the potentially affected species. 
Additional information regarding population trends and threats may be 
found in NMFS' Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these species 
(e.g., physical and behavioral descriptions) may be found on NMFS' 
website (www.nmfs.noaa.gov/pr/species/mammals/). Additional information 
may be found in BOEM's Final EIS for the project which is available 
online at https://www.boem.gov/Hilcorp-Liberty/.
    Table 2 lists all species with expected potential for occurrence in 
Foggy Island Bay and surrounding Beaufort Sea and summarizes 
information related to the population or stock, including regulatory 
status under the MMPA and ESA and potential biological removal (PBR), 
where known. For taxonomy, we follow Committee on Taxonomy (2016). PBR 
is defined by the MMPA as the maximum number of animals, not including 
natural mortalities, that may be removed from a marine mammal stock 
while allowing that stock to reach or maintain its optimum sustainable 
population (as described in NMFS' SARs). PBR and annual serious injury 
and mortality from anthropogenic sources are included here as gross 
indicators of the status of the species and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS' stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS' U.S. 2017 SAR for Alaska (Muto et al., 2018). All values 
presented in Table 2 are the most recent available at the time of 
publication and are available in the 2017 SARs (Muto et al., 2018).

[[Page 24933]]



                                   Table 2--Marine Mammals With Expected Potential Occurrence in Beaufort Sea, Alaska
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         ESA/MMPA status;   Stock abundance ) (CV,
             Common name                  Scientific name               Stock             strategic (Y/N)      Nmin, most recent       PBR     Annual M/
                                                                                                \1\          abundance survey) \2\               SI \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  Family Eschrichtiidae
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gray whale..........................  Eschrichtius robustus..  Eastern North Pacific..  -;N                 20,990 (0.05, 20,125,         624        132
                                                                                                             2011).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Family Balaenidae
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bowhead whale.......................  Balaena mysticetus.....  Western Arctic.........  E/D; Y              16,820 (0.052, 16,100,        161         46
                                                                                                             2011).
Humpback whale......................  Megaptera novaeangliae.  Central North Pacific    E/D; Y              10,103 (0.3, 7,891,            83         26
                                                                Stock.                                       2006).
Minke whale.........................  .......................  Alaska.................  -;N                 unk...................      undet          0
Fin whale...........................  .......................  Northeast Pacific......  E/D; Y              3,168 (0.26, 2,554,           5.1        0.6
                                                                                                             2013) \6\.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   Family Delphinidae
--------------------------------------------------------------------------------------------------------------------------------------------------------
Beluga whale........................  Delphinapterus leucas..  Beaufort Sea...........  -; N                39,258 (0.229, N/A,           Und        139
                                                                                                             1992).
                                      .......................  Eastern Chukchi........  -; N                20,752 (0.70, 12,194,         244         67
                                                                                                             2012).
Killer whale........................  Orcinus orcas..........  Eastern North Pacific    -;N                 587 (n/a, 587, 2012)..        5.9          0
                                                                Gulf of Alaska,
                                                                Aleutian Islands, and
                                                                Bering Sea Transient.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Family Otariidae (eared seals and sea lions)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Steller sea lion....................  Eumatopias jubatus.....  Eastern U.S............  -; N                41,638 (-, 41,638,          2,498        108
                                                                                                             2015).
                                      .......................  Western U.S............  E/D;Y               53,303 (-, 53,303,            320        241
                                                                                                             2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Family Phocidae (earless seals)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Ringed Seal.........................  Pusa hispida...........  Alaska.................  T, D; Y             170,000 (-, 170,000,          Und      1,054
                                                                                                             2012) \4\.
Bearded seal........................  Erignathus barbatus....  Alaska.................  T, D; Y             299,174 (-, 273,676)          Und        391
                                                                                                             \5\.
Spotted seal........................  Phoca largha...........  Alaska.................  ..................  423,625 (-, 423,237,       12,697        329
                                                                                                             2013).
Ribbon seal.........................  Histriophoca fasciata..  Alaska.................  ..................  184,000 (-, 163,086,        9,785        3.9
                                                                                                             2013).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: www.nmfs.noaa.gov/pr/sars/. CV is coefficient of variation; Nmin is the minimum estimate of
  stock abundance.
\3\ These values, found in NMFS' SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  subsistence use, commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum
  value or range. A CV associated with estimated mortality due to commercial fisheries is presented in some cases.
\4\ The population provided here was derived using a using a very limited sub-sample of the data collected from the U.S. portion of the Bering Sea in
  2012 (Conn et al., 2014). Thus, the actual number of ringed seals in the U.S. sector of the Bering Sea is likely much higher, perhaps by a factor of
  two or more (Muto et al., 2018). Reliable estimates of abundance are not available for the Chukchi and Beaufort seas (Muto et al., 2018).
\5\ 5. In spring of 2012 and 2013, surveys were conducted in the Bering Sea and Sea of Okhotsk; these data do not include seals in the Chukchi and
  Beaufort Seas at the time of the survey.
\6\ NBEST, NMIN, and PBR have been calculated for this stock; however, important caveats exist. See Stock Assessment Report text for details.
Note--Italicized species are not expected to be taken or proposed for authorization.

    All species that could potentially occur in the Beaufort Sea are 
included in Table 2. However, the temporal and/or spatial occurrence of 
minke, fin, humpback whales, killer whales, narwhals, harbor porpoises, 
and ribbon seals are such that take is not expected to occur, and they 
are not discussed further beyond the explanation provided here. These 
species, regularly occur in the Chukchi Sea but not as commonly in the 
Beaufort Sea. Narwhals, Steller sea lions, and hooded seals are 
considered extralimital to the proposed action area These species could 
occur in the Beaufort Sea, but are either uncommon or extralimital east 
of Barrow (located in the Foggy Island Bay area and surveys within the 
Bay have revealed zero sightings).
    In addition, the polar bear may be found in Foggy Island Bay. 
However, this species is managed by the U.S. Fish and Wildlife Service 
and is not considered further in this document.
    On October 11, 2016, NOAA released the Final Environmental Impact 
Statement (FEIS) for the Effects of Oil and Gas Activities in the 
Arctic Ocean (81 FR 72780, October 21, 2016) regarding geological and 
geophysical (i.e., seismic) activities, ancillary activities, and 
exploratory drilling. The Final EIS may be found at https://www.fisheries.noaa.gov/national/marine-mammal-protection/environmental-impact-statement-eis-effects-oil-and-gas-activities. Although no 
seismic activities are proposed by Hilcorp, the EIS contains detailed

[[Page 24934]]

information on marine mammal species proposed to be potentially taken 
by Hilcorp's specified activities. More recently, BOEM released a final 
EIS on the Liberty Project. We incorporate by reference the information 
on the species proposed to be potentially taken by Hilcorp's specified 
activities from these documents and provide a summary and any relevant 
updates on species status here.

Bowhead Whale

    The only bowhead whale stock found within U.S. waters is the 
Western Arctic stock, also known as the Bering-Chukchi-Beaufort stock 
(Rugh et al., 2003) or Bering Sea stock (Burns et al., 1993). The 
majority of the Western Arctic stock migrates annually from wintering 
areas (December to March) in the northern Bering Sea, through the 
Chukchi Sea in the spring (April through May), to the eastern Beaufort 
Sea where they spend much of the summer (June through early to mid-
October) before returning again to the Bering Sea in the fall 
(September through December) to overwinter (Braham et al., 1980, Moore 
and Reeves 1993, Quakenbush et al., 2010a, Citta et al., 2015). Some 
bowhead whales are found in the western Beaufort, Chukchi, and Bering 
seas in summer, and these are thought to be a part of the expanding 
Western Arctic stock (Rugh et al., 2003; Clarke et al., 2013, 2014, 
2015; Citta et al., 2015). The most recent population parameters (e.g., 
abundance, PBR) of western Arctic bowhead whales are provided in Table 
2.
    Bowhead whale distribution in the Beaufort Sea during summer-fall 
has been studied by aerial surveys through the Bowhead Whale Aerial 
Survey Project (BWASP). This project was funded or contracted by the 
Minerals Management Service (MMS)/Bureau of Ocean Energy Management 
(BOEM) and Bureau of Land Management (BLM) annually from 1979 to 2010. 
The focus of the BWASP aerial surveys was the autumn migration of 
bowhead whales through the Alaskan Beaufort Sea, although data were 
collected on all marine mammals sighted. The NMFS National Marine 
Mammal Laboratory (NMML) began coordinating BWASP in 2007, with funding 
from MMS. In 2011, an Interagency Agreement between the BOEM and NMML 
combined BWASP with COMIDA under the auspices of a single survey called 
Aerial Surveys of Arctic Marine Mammals (ASAMM) (Clarke et al., 2012); 
both studies are funded by BOEM. In September to mid-October bowheads 
begin their western migration out of the Canadian Beaufort Sea to the 
Chukchi Sea (Figure 3.2-10). Most westward travel across the Beaufort 
Sea by tagged whales was over the shelf, within 100 km (62 mi) of 
shore, although a few whales traveled farther offshore (Quakenbush et 
al., 2012).
    During winter and spring, bowhead whales are closely associated 
with sea ice (Moore and Reeves 1993, Quakenbush et al., 2010a, Citta et 
al., 2015). The bowhead whale spring migration follows fractures in the 
sea ice around the coast of Alaska, generally in the shear zone between 
the shorefast ice and the mobile pack ice. During summer, most of the 
population is in relatively ice-free waters in the southeastern 
Beaufort Sea (Citta et al., 2015), an area often exposed to industrial 
activity related to petroleum exploration (e.g., Richardson et al., 
1987, Davies, 1997). Summer aerial surveys conducted in the western 
Beaufort Sea during July and August of 2012-2014 have had relatively 
high sighting rates of bowhead whales, including cows with calves and 
feeding animals (Clarke et al., 2013, 2014, 2015). During the autumn 
migration through the Beaufort Sea, bowhead whales generally select 
shelf waters (Citta et al., 2015). In winter in the Bering Sea, bowhead 
whales often use areas with ~100 percent sea-ice cover, even when 
polynyas are available (Quakenbush et al., 2010a, Citta et al., 2015).
    From 2006 through 2014, median distance of bowhead whales from 
shore was 23.6 km (14.7 mi) in the East Region and 24.2 km (15.0 mi) in 
the West Region during previous low-ice years, with annual median 
distances ranging from as close as 6.3 km (3.9 mi) in 2009 to 37.6 km 
(23.4 mi) in 2013 (Clarke et al., 2015b). Median depth of sightings 
during previous low-ice years was 39 m (128 ft) in the East Region and 
21 m (69 ft) in the West Region; in 2014, median depth of on-transect 
sightings was 20 m (66 ft) and 19 m (62 ft), respectively (Clarke et 
al., 2015b). In September and October 2014, bowhead whales in the East 
Region of the study area were sighted in shallower water and closer to 
shore than in previous years of light sea ice cover; in the West 
Region, bowhead sightings in fall 2014 were in shallower water than in 
previous light ice years, but the distance from shore did not differ 
(Clarke et al., 2015b). Behaviors included milling, swimming, and 
feeding, to a lesser degree. Highest numbers of sightings were in the 
central Beaufort Sea and east of Point Barrow. Overall, the most 
shoreward edge of the bowhead migratory corridor for bowhead extends 
approximately 40 km (25 mi) north from the barrier islands, which are 
located approximately 7 km (4 mi) north of Liberty Project. The closest 
approach of a tagged whale occurred in August 2016 when it came within 
16 km of the proposed LDPI (Quakenbush, 2018).
    Historically, there have been few spring, summer, or autumn 
observations of bowheads in larger bays such as Camden, Prudhoe, and 
Harrison Bays, although some groups or individuals have occasionally 
been observed feeding around the periphery of or, less commonly, inside 
the bays as migration demands and feeding opportunities permit. 
Observations indicate that juvenile, sub-adult, and cow-calf pairs of 
bowheads are the individuals most frequently observed in bays and 
nearshore areas of the Beaufort, while more competitive whales are 
found in the Canadian Beaufort and Barrow Canyon, as well as deeper 
offshore waters (Clarke et al., 2011b, 2011c, 2011d, 2012, 2013, 2014, 
2015b; Koski and Miller, 2009; Quakenbush et al., 2010).
    Clarke et al. (2015) evaluated biologically important areas (BIAs) 
for bowheads in the U.S. Arctic region and identified nine BIAs. The 
spring (April-May) migratory corridor BIA for bowheads is far offshore 
of the LDPI but within the transit portion of the action area, while 
the fall (September-October) migratory corridor BIA (western Beaufort 
on and north of the shelf) for bowheads is further inshore and closer 
to the LDPI. Clarke et al. (2015) also identified four BIAs for 
bowheads that are important for reproduction and encompassed areas 
where the majority of bowhead whales identified as calves were observed 
each season; none of these reproductive BIAs overlap with the LDPI, but 
may be encompassed in indirect areas such as vessel transit route. 
Finally, three bowhead feeding BIAs were identified. Again, there is no 
spatial overlap of the activity area with these BIAs.
    From July 8, 2008, through August 25, 2008, BPXA conducted a 3D 
seismic survey in the Liberty Prospect, Beaufort Sea. During the August 
survey a mixed-species group of whales was observed in one sighting 
near the barrier islands that included bowhead and gray whales (Aerts 
et al., 2008). This is the only known survey sighting of bowhead whales 
within Foggy Island Bay despite industry surveys occurring during the 
open water season in 2010, 2014, and 2015 and NMFS aerial surveys flown 
inside Foggy Island Bay in 2016 and 2017.
    Alaska Natives have been taking bowhead whales for subsistence 
purposes for at least 2,000 years (Marquette and Bockstoce, 1980, 
Stoker

[[Page 24935]]

and Krupnik, 1993). Subsistence takes have been regulated by a quota 
system under the authority of the IWC since 1977. Alaska Native 
subsistence hunters, primarily from 11 Alaska communities, take 
approximately 0.1-0.5 percent of the population per annum (Philo et 
al., 1993, Suydam et al., 2011). The average annual subsistence take 
(by Natives of Alaska, Russia, and Canada) during the 5-year period 
from 2011 through 2015 is 43 landed bowhead whales (Muto et al., 2018).

Gray Whale

    The eastern North Pacific population of gray whales migrates along 
the coasts of eastern Siberia, North America, and Mexico (Allen and 
Angliss 2010; Weller et al., 2002) and population size has been 
steadily increasing, potentially reaching carrying capacity (Allen and 
Angliss, 2010, 2012). Abundance estimates will likely rise and fall in 
the future as the population finds a balance with the carrying-capacity 
of the environment (Rugh et al., 2005). The steadily increasing 
population abundance warranted delisting of the eastern North Pacific 
gray whale stock in 1994, as it was no longer considered endangered or 
threatened under the ESA (Rugh et al., 1999). A five-year status review 
determined that the stock was neither in danger of extinction nor 
likely to become endangered in the foreseeable future, thus, retaining 
the non-threatened classification (Rugh et al., 1999). Table 2 provided 
population parameters for this stock.
    The gray whale migration may be the longest of any mammalian 
species. They migrate over 8,000 to 10,000 km (5,000 to 6,200 mi) 
between breeding lagoons in Mexico and Arctic feeding areas each spring 
and fall (Rugh et al., 1999). The southward migration out of the 
Chukchi Sea generally begins during October and November, passing 
through Unimak Pass in November and December, then continues along a 
coastal route to Baja California (Rice et al., 1984). The northward 
migration usually begins in mid-February and continues through May 
(Rice et al. 1984).
    Gray whales are the most coastal of all the large whales and 
inhabit primarily inshore or shallow, offshore continental shelf waters 
(Jones and Swartz, 2009); however, they are more common in the Chukchi 
than in the Beaufort Sea. Throughout the summers of 2010 and 2011, gray 
whales regularly occurred in small groups north of Point Barrow and 
west of Barrow (George et al., 2011; Shelden et al., 2012). In 2011, 
there were no sightings of gray whales east of Point Barrow during 
ASAMM aerial surveys (Clarke et al., 2012); however, they were observed 
east of Point Barrow, primarily in the vicinity of Barrow Canyon, from 
August to October 2012 (Clarke et al., 2013). Gray whales were again 
observed east of Point Barrow in 2013, with all sightings in August 
except for one sighting in late October (Clarke et al., 2014). In 2014, 
sightings in the Beaufort Sea included a few whales east of Point 
Barrow and one north of Cross Island near Prudhoe Bay (Clarke et al., 
2015b). Gray whales prefer shoal areas (<60 m (197 ft) deep) with low 
(<7 percent) ice cover (Moore and DeMaster, 1997). These areas provide 
habitat rich in gray whale prey (amphipods, decapods, and other 
invertebrates).
    From July 8, 2008 through August 25, 2008, BPXA conducted a 3D 
seismic survey in the Liberty Prospect, Beaufort Sea. During the August 
survey a mixed-species group of whales was observed in one sighting 
near the barrier islands that included bowhead and gray whales (Aerts 
et al., 2008). This is the only known survey sighting of gray whales 
within Foggy Island Bay despite industry surveys occurring during the 
open water season in 2010, 2014, and 2015 and NMFS aerial surveys flown 
inside Foggy Island Bay in 2016 and 2017.

Beluga Whale

    Five beluga whale stocks are present in Alaska including the Cook 
Inlet, Bristol Bay, eastern Bering Sea, eastern Chukchi Sea, and 
Beaufort Sea stocks (O'Corry-Crowe et al., 1997, Allen and Angliss, 
2015). The eastern Chukchi and Beaufort Sea stocks are thought to 
overlap in the Beaufort Sea. Both stocks are closely associated with 
open leads and polynyas in ice-covered regions throughout Arctic and 
sub-Arctic waters of the Northern Hemisphere. Distribution varies 
seasonally. Whales from both the Beaufort Sea and eastern Chukchi Sea 
stocks overwinter in the Bering Sea. Belugas of the eastern Chukchi may 
winter in offshore, although relatively shallow, waters of the western 
Bering Sea (Richard et al., 2001), and the Beaufort Sea stock may 
winter in more nearshore waters of the northern Bering Sea (R. Suydam, 
pers. comm. 2012c). In the spring, belugas migrate to coastal 
estuaries, bays, and rivers. Annual migrations may cover thousands of 
kilometers (Allen and Angliss, 2010, 2012a).
    Satellite telemetry data from 23 whales tagged in Kaseguluk Lagoon 
in 1998 through 2002 provided information on movements and migrations 
of eastern Chukchi Sea belugas. Animals initially traveled north and 
east into the northern Chukchi and western Beaufort seas after capture 
(Suydam et al., 2001, 2005). Movement patterns between July and 
September vary by age and/or sex classes. Adult males frequent deeper 
waters of the Beaufort Sea and Arctic Ocean (79-80[deg] N), where they 
remain throughout the summer. Immature males moved farther north than 
immature females but not as far north as adult males. All of the 
belugas frequented water deeper than 200 m (656 ft) along and beyond 
the continental shelf break. Use of the inshore waters within the 
Beaufort Sea Outer Continental Shelf lease sale area was rare (Suydam 
et al., 2005).
    Most information on distribution and movements of belugas of the 
Beaufort Sea stock was similarly derived using satellite tags. A total 
of 30 belugas were tagged in the Mackenzie River Delta, Northwest 
Territories, Canada, during summer and autumn in 1993, 1995, and 1997 
(Richard et al., 2001). Approximately half of the tagged whales 
traveled far offshore of the Alaskan coastal shelf, while the remainder 
traveled on the shelf or near the continental slope (Richard et al., 
2001). Migration through Alaskan waters lasted an average of 15 days. 
In 1997, all of the tagged belugas reached the western Chukchi Sea 
(westward of 170[deg] W) between September 15 and October 9. Overall, 
the main fall migration corridor for beluga whales is believed to be 
approximately 62 mi (100 km) north of the Project Area (Richard et al., 
1997, 2001). Both the spring (April-May) and fall (September-October) 
migratory corridor BIAs for belugas are far north of the proposed 
action area because sightings of belugas from aerial surveys in the 
western Beaufort Sea are primarily on the continental slope, with 
relatively few sightings on the shelf (Clarke et al., 2015). No 
reproductive and feeding BIAs exist for belugas in the action area 
(Clarke et al., 2015).
    O'Corry et al. (2018) studied genetic marker sets in 1,647 beluga 
whales. The data set was from over 20 years and encompassed all of the 
whales' major coastal summering regions in the Pacific Ocean. The 
genetic marker analysis of the migrating whales revealed that while 
both the wintering and summering areas of the eastern Chukchi Sea and 
eastern Beaufort Sea subpopulations may overlap, the timing of spring 
migration differs such that the whales hunted at coastal sites in 
Chukotka, the Bering Strait (i.e., Diomede), and northwest Alaska 
(i.e., Point Hope) in the spring and off of Alaska's Beaufort Sea coast 
in summer were predominantly from the eastern Beaufort Sea population. 
Earlier genetic investigations and recent telemetry

[[Page 24936]]

studies show that the spring migration of eastern Beaufort whales 
occurs earlier and through denser sea ice than eastern Chukchi Sea 
belugas. The discovery that a few individual whales found at some of 
these spring locations had higher likelihood of having eastern Chukchi 
Sea ancestry or being of mixed-ancestry, indicates that the Bering 
Strait region is also an area where the stock mix in spring. Citta et 
al. (2016) also observed that tagged eastern Beaufort Sea whales 
migrated north in spring through the Bering Strait earlier than the 
eastern Chukchi belugas so they had to pass through the latter's 
primary wintering area. Therefore, the eastern Chukchi stock should not 
be present in the action area at any time in general, but especially 
during summer-late fall, when the beluga exposures would be anticipated 
for this project. Therefore, we assume all belugas impacted by the 
proposed project are from the Beaufort Sea stock.
    Beluga whales were regularly sighted during the September-October 
BWASP and the more recent ASAMM aerial surveys of the Alaska Beaufort 
Sea coast. Burns and Seaman (1985) suggest that beluga whales are 
strongly associated with the ice fringe and that the route of the 
autumn migration may be mainly determined by location of the drift ice 
margin. Relatively few beluga whales have been observed in the 
nearshore areas (on the continental shelf outside of the barrier 
islands) of Prudhoe Bay. However, groups of belugas have been detected 
nearshore in September (Clarke et al., 2011a) and opportunistic 
sightings have been recorded from Northstar Island and Endicott. These 
sightings are part of the fall migration which generally occurs farther 
offshore although a few sightings of a few individuals do occur closer 
to the shore, and occasionally inside the barrier islands of Foggy 
Island Bay. During the 2008 seismic survey in Foggy Island Bay, three 
sightings of eight individuals were observed at a location about 3 mi 
(4.8 km) east of the Endicott Satellite Drilling Island (Aerts et al., 
2008). In 2014, during a BPXA 2D HR shallow geohazard survey in July 
and August, PSOs recorded eight groups of approximately 19 individual 
beluga whales, five of which were juveniles (Smultea et al., 2014). 
During the open water season July 9 through July 19, 2015, five 
sightings of belugas occurred (Cate et al., 2015). Also in 2015, 
acoustic monitoring was conducted in Foggy Island Bay between July 6 
and September 22, 2015, to characterize ambient sound conditions and to 
determine the acoustic occurrence of marine mammals near Hilcorp's 
Liberty Prospect in Foggy Island Bay (Frouin-Jouy et al., 2015). Two 
recorders collected underwater sound data before, during, and after 
Hilcorp's 2015 geohazard survey (July 6-Sept. 22). Detected marine 
mammal vocalizations included those from beluga whales and pinnipeds. 
Belugas were detected on five days by passive-recorders inside the bay 
during the three-month survey period (Frouin-Jouy et al., 2015). During 
the 2016 and 2017 ASAMM surveys flown inside Foggy Island Bay, no 
belugas were observed. Beluga whales are the cetacean most likely to be 
encountered during the open-water season in Foggy Island Bay, albeit 
few in abundance.

Ringed Seal

    One of five Arctic ringed seal stocks, the Alaska stock, occurs in 
U.S. waters. The Arctic subspecies of ringed seals was listed as 
threatened under the ESA on December 28, 2012, primarily due to 
expected impacts on the population from declines in sea and snow cover 
stemming from climate change within the foreseeable future (77 FR 
76706). However, on March 11, 2016, the U.S. District Court for the 
District of Alaska issued a decision in a lawsuit challenging the 
listing of ringed seals under the ESA (Alaska Oil and Gas Association 
et al. v. National Marine Fisheries Service, Case No. 4:14-cv-00029-
RRB). The decision vacated NMFS' listing of Arctic ringed seals as a 
threatened species. However, on February 12, 2018, in Alaska Oil & Gas 
Association v. Ross, Case No. 16-35380, the U.S. Court of Appeals for 
the Ninth Circuit reversed the district court's 2016 decision. As such, 
Arctic ringed seals remain listed as threatened under the ESA.
    During winter and spring in the United States, ringed seals are 
found throughout the Beaufort and Chukchi Seas; they occur in the 
Bering Sea as far south as Bristol Bay in years of extensive ice 
coverage. Most ringed seals that winter in the Bering and Chukchi Seas 
are thought to migrate northward in spring with the receding ice edge 
and spend summer in the pack ice of the northern Chukchi and Beaufort 
Seas.
    Ringed seals are resident in the Beaufort Sea year-round, and based 
on results of previous surveys in Foggy Island Bay (Aerts et al., 2008, 
Funk et al., 2008, Savarese et al., 2010, Smultea et al., 2014), and 
monitoring from Northstar Island (Aerts and Richardson, 2009, 2010), 
they are expected to be the most commonly occurring pinniped in the 
action area year-round.
    Ringed seals are present in the nearshore and sea ice year-round, 
maintaining breathing holes and excavating subnivean lairs in the 
landfast ice during the ice-covered season. Ringed seals overwinter in 
the landfast ice in and around the LDPI action area. There is some 
evidence indicating that ringed seal densities are low in water depths 
of less than 3 m, where landfast ice extending from the shoreline 
generally freezes to the sea bottom in very shallow waters during the 
course of the winter (Moulton et al., 2002a, Moulton et al., 2002b, 
Richardson and Williams, 2003). Ringed seals that breed on shorefast 
ice may either forage within 100 km (62.1 mi) of their breeding habitat 
or undertake extensive foraging trips to more productive areas at 
distances of between 100-1,000 kilometers (Kelly et al., 2010b). Adult 
Arctic ringed seals show site fidelity, returning to the same subnivean 
site after the foraging period ends. Movements are limited during the 
ice-bound months, including the breeding season, which limits their 
foraging activities and may minimize gene flow within the species 
(Kelly et al. 2010b). During April to early June (the reproductive 
period), radio-tagged ringed seals inhabiting shorefast ice near 
Prudhoe Bay had home range sizes generally less than 1,336 ac (500 ha) 
in area (Kelly et al., 2005). Sub-adults, however, were not constrained 
by the need to defend territories or maintain birthing lairs and 
followed the advancing ice southward to winter along the Bering Sea ice 
edge where there may be enhanced feeding opportunities and less 
exposure to predation (Crawford et al., 2012). Sub-adult ringed seals 
tagged in the Canadian Beaufort Sea similarly undertook lengthy 
migrations across the continental shelf of the Alaskan Beaufort Sea 
into the Chukchi Sea, passing Point Barrow prior to freeze-up in the 
central Chukchi Sea (Harwood et al., 2012). Factors most influencing 
seal densities during May through June in the central Beaufort Sea 
between Oliktok Point and Kaktovik were water depth, distance to the 
fast ice edge, and ice deformation. Highest densities of seals were at 
depths of 5 to 35 m (16 to 144 ft) and on relatively flat ice near the 
fast ice edge (Frost et al., 2004).
    Sexual maturity in ringed seals varies with population status. It 
can be as early as 3 years for both sexes and as late as 7 years for 
males and 9 years for females. Ringed seals breed annually, with timing 
varying regionally. Mating takes place while mature females are still 
nursing their pups on the ice and

[[Page 24937]]

is thought to occur under the ice near birth lairs. In all subspecies 
except the Okhotsk, females give birth to a single pup hidden from view 
within a snow-covered birth lair. Ringed seals are unique in their use 
of these birth lairs. Pups learn how to dive shortly after birth. Pups 
nurse for 5 to 9 weeks and, when weaned, are four times their birth 
weights. Ringed seal pups are more aquatic than other ice seal pups and 
spend roughly half their time in the water during the nursing period 
(Lydersen and Hammill, 1993). Pups are normally weaned before the 
break-up of spring ice.
    Ringed seals are an important resource for Alaska Native 
subsistence hunters. Approximately 64 Alaska Native communities in 
western and northern Alaska, from Bristol Bay to the Beaufort Sea, 
regularly harvest ice seals (Ice Seal Committee, 2016). Based on the 
harvest data from 12 Alaska Native communities, a minimum estimate of 
the average annual harvest of ringed seals in 2009-2013 is 1,050 seals 
(Muto et al., 2016).
    Other sources of mortality include commercial fisheries and 
predation by marine and terrestrial predators including polar bears, 
arctic foxes, walrus, and killer whales. During 2010-2014, incidental 
mortality and serious injury of ringed seals was reported in 4 of the 
22 federally-regulated commercial fisheries in Alaska monitored for 
incidental mortality and serious injury by fisheries observers: the 
Bering Sea/Aleutian Islands flatfish trawl, Bering Sea/Aleutian Islands 
pollock trawl, Bering Sea/Aleutian Islands Pacific cod trawl, and 
Bering Sea/Aleutian Islands Pacific cod longline fisheries (Muto et 
al., 2016). From May 1, 2011 to December 31, 2016, 657 seals, which 
included 233 dead stranded seals, 179 subsistence hunted seals, and 245 
live seals, stranded or were sampled during permitted health 
assessments studies. Species involved were primarily ice seals 
including ringed, bearded, ribbon, and spotted seals in northern and 
western Alaska. The investigation identified that clinical signs were 
likely due to an abnormality of the molt, but a definitive cause for 
the abnormal molt was not determined.

Bearded Seal

    Two subspecies of bearded seal have been described: E. b. barbatus 
from the Laptev Sea, Barents Sea, North Atlantic Ocean, and Hudson Bay 
(Rice 1998); and E. b. nauticus from the remaining portions of the 
Arctic Ocean and the Bering and Okhotsk seas (Ognev, 1935, Scheffer, 
1958, Manning, 1974, Heptner et al., 1976). On December 28, 2012, NMFS 
listed two distinct population segments (DPSs) of the E. b. nauticus 
subspecies of bearded seals--the Beringia DPS and Okhotsk DPS--as 
threatened under the ESA (77 FR 76740). Similar to ringed seals, the 
primary concern for these DPSs is the ongoing and projected loss of 
sea-ice cover stemming from climate change, which is expected to pose a 
significant threat to the persistence of these seals in the foreseeable 
future (based on projections through the end of the 21st century; 
Cameron et al., 2010). Similar to ringed seals, the ESA listing of the 
Beringia and Okhotsk DPSs of bearded seal was challenged in the U.S. 
District Court for the District of Alaska, and on July 25, 2014, the 
court vacated NMFS' listing of those DPSs of bearded seals as 
threatened under the ESA (Alaska Oil and Gas Association et al. v. 
Pritzker, Case No. 4:13-cv-00018-RRB). However, the U.S. Court of 
Appeals for the Ninth Circuit reversed the district court's 2016 
decision on October 24, 2016 (Alaska Oil & Gas Association v. Pritzer, 
Case No. 14-35806). As such, the Beringia and Okhotsk DPSs of bearded 
seal remain listed as threatened under the ESA.
    For the purposes of MMPA stock assessments, the Beringia DPS is 
considered the Alaska stock of the bearded seal (Muto et al., 2016). 
The Beringia DPS of the bearded seal includes all bearded seals from 
breeding populations in the Arctic Ocean and adjacent seas in the 
Pacific Ocean between 145[deg] E longitude (Novosibirskiye) in the East 
Siberian Sea and 130[deg] W longitude in the Canadian Beaufort Sea, 
except west of 157[deg] W longitude in the Bering Sea and west of the 
Kamchatka Peninsula (where the Okhotsk DPS is found). They generally 
prefer moving ice that produces natural openings and areas of open-
water (Heptner et al., 1976, Fedoseev, 1984, Nelson et al., 1984). They 
usually avoid areas of continuous, thick, shorefast ice and are rarely 
seen in the vicinity of unbroken, heavy, drifting ice or large areas of 
multi-year ice (Fedoseev, 1965, Burns and Harbo, 1972, Burns and Frost, 
1979, Burns, 1981, Smith, 1981, Fedoseev, 1984, Nelson et al., 1984).
    Spring surveys conducted in 1999-2000 along the Alaska coast 
indicate that bearded seals are typically more abundant 20-100 nautical 
miles (nmi) from shore than within 20 nmi from shore, except for high 
concentrations nearshore to the south of Kivalina (Bengtson et al., 
2005; Simpkins et al., 2003).
    Although bearded seal vocalizations (produced by adult males) have 
been recorded nearly year-round in the Beaufort Sea (MacIntyre et al., 
2013, MacIntyre et al., 2015), most bearded seals overwinter in the 
Bering Sea. In addition, during late winter and early spring, Foggy 
Island Bay is covered with shorefast ice and the nearest lead systems 
are at least several kilometers away, making the area unsuitable 
habitat for bearded seals. Therefore, bearded seals are not expected to 
be encountered in or near the LDPI portion of the action area during 
this time (from late winter through early spring).
    During the open-water period, the Beaufort Sea likely supports 
fewer bearded seals than the Chukchi Sea because of the more extensive 
foraging habitat available to bearded seals in the Chukchi Sea. In 
addition, as a result of shallow waters, the sea floor in Foggy Island 
Bay south of the barrier islands is often scoured by ice, which limits 
the presence of bearded seal prey species. Nevertheless, aerial and 
vessel-based surveys associated with seismic programs, barging, and 
government surveys in this area between 2005 and 2010 reported several 
bearded seal sightings (Green and Negri, 2005, Green and Negri 2006, 
Green et al., 2007, Funk et al., 2008, Hauser et al., 2008, Savarese et 
al., 2010, Clarke et al., 2011, Reiser et al., 2011). In addition, 
eight bearded seal sightings were documented during shallow geohazard 
seismic and seabed mapping surveys conducted in July and August 2014 
(Smultea et al., 2014). Frouin-Mouy et al. (2016) conducted acoustic 
monitoring in Foggy Island Bay from early July to late September 2014, 
and detected pinniped vocalizations on 10 days via the nearshore 
recorder and on 66 days via the recorder farther offshore. Although the 
majority of these detections were unidentified pinnipeds, bearded seal 
vocalizations were positively identified on two days (Frouin-Mouy et 
al., 2016).
    Bearded seals are an important resource for Alaska Native 
subsistence hunters. Approximately 64 Alaska Native communities in 
western and northern Alaska, from Bristol Bay to the Beaufort Sea, 
regularly harvest ice seals (Ice Seal Committee, 2016). However, during 
2009-2013, only 12 of 64 coastal communities were surveyed for bearded 
seals; and, of those communities, only 6 were surveyed for two or more 
consecutive years (Ice Seal Committee, 2016). Based on the harvest data 
from these 12 communities (Table 2), a minimum estimate of the average 
annual harvest of bearded seals in 2009-2013 is 390 seals. Harvest 
surveys are designed to estimate harvest within the surveyed community, 
but because of differences in seal availability, cultural hunting 
practices, and environmental

[[Page 24938]]

conditions, extrapolating harvest numbers beyond that community is not 
appropriate (Muto et al., 2016).
    Of the 22 federally-regulated U.S. commercial fisheries in Alaska 
monitored for incidental mortality and serious injury by fisheries 
observers, 12 fisheries could potentially interact with bearded seals. 
During 2010-2014, incidental mortality and serious injury of bearded 
seals occurred in three fisheries: The Bering Sea/Aleutian Islands 
pollock trawl, Bering Sea/Aleutian Islands flatfish trawl, and Bering 
Sea/Aleutian Islands Pacific cod trawl fisheries (Muto et al., 2016). 
This species was also part of the aforementioned 2011-2016 UME.

Spotted Seal

    Spotted seals are distributed along the continental shelf of the 
Bering, Chukchi, and Beaufort seas, and the Sea of Okhotsk south to the 
western Sea of Japan and northern Yellow Sea. Eight main areas of 
spotted seal breeding have been reported (Shaughnessy and Fay, 1977) 
and Boveng et al. (2009) grouped those breeding areas into three DPSs: 
The Bering DPS, which includes breeding areas in the Bering Sea and 
portions of the East Siberian, Chukchi, and Beaufort seas that may be 
occupied outside the breeding period; the Okhotsk DPS; and the Southern 
DPS, which includes spotted seals breeding in the Yellow Sea and Peter 
the Great Bay in the Sea of Japan. For the purposes of MMPA stock 
assessments, NMFS defines the Alaska stock of spotted seals to be that 
portion of the Bering DPS in U.S. waters.
    The distribution of spotted seals is seasonally related to specific 
life-history events that can be broadly divided into two periods: Late-
fall through spring, when whelping, nursing, breeding, and molting 
occur in association with the presence of sea ice on which the seals 
haul out, and summer through fall when seasonal sea ice has melted and 
most spotted seals use land for hauling out (Boveng et al., 2009). 
Spotted seals are most numerous in the Bering and Chukchi seas 
(Quakenbush, 1988), although small numbers do range into the Beaufort 
Sea during summer (Rugh et al., 1997; Lowry et al., 1998).
    At Northstar, few spotted seals have been observed. A total of 12 
spotted seals were positively identified near the source-vessel during 
open-water seismic programs in the central Alaskan Beaufort Sea, 
generally occurring near Northstar from 1996 to 2001 (Moulton and 
Lawson, 2002). The number of spotted seals observed per year ranged 
from zero (in 1998 and 2000) to four (in 1999).
    During a seismic survey in Foggy Island Bay, PSOs recorded 18 
pinniped sightings, of which one was confirmed as a spotted seal (Aerts 
et al., 2008). Spotted seals were the second most abundant seal species 
observed by PSOs during Hilcorp's geohazard surveys in July-August 2014 
(Smultea et al., 2014) and in July 2015 (Cate et al., 2015). Given 
their seasonal distribution and low numbers in the nearshore waters of 
the central Alaskan Beaufort Sea, no spotted seals are expected in the 
action area during late winter and spring, but could be present in low 
numbers during the summer or fall.
    Similar to other ice seal species, spotted seals are an important 
resource for Alaska Native subsistence hunters. Of the 12 communities 
(out of 64) surveyed during 2010-2014, the minimum annual spotted seal 
harvest estimates totaled across 12 out of 64 user communities surveyed 
ranged from 83 (in 2 communities) to 518 spotted seals (in 10 
communities). Based on the harvest data from these 12 communities, a 
minimum estimate of the average annual harvest of spotted seals in 
2010-2014 is 328 seals.
    From 2011-2015, incidental mortality and serious injury of spotted 
seals occurred in 2 of the 22 federally-regulated U.S. commercial 
fisheries in Alaska monitored for incidental mortality and serious 
injury by fisheries observers: The Bering Sea/Aleutian Islands flatfish 
trawl and Bering Sea/Aleutian Islands Pacific cod longline fisheries. 
In 2014, there was one report of a mortality incidental to research on 
the Alaska stock of spotted seals, resulting in a mean annual mortality 
and serious injury rate of 0.2 spotted seals from this stock in 2011-
2015. This species was also part of the aforementioned 2011-2016 UME.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Current data indicate that not all marine 
mammal species have equal hearing capabilities (e.g., Richardson et 
al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect 
this, Southall et al. (2007 and 2019) recommended that marine mammals 
be divided into functional hearing groups based on directly measured or 
estimated hearing ranges on the basis of available behavioral response 
data, audiograms derived using auditory evoked potential techniques, 
anatomical modeling, and other data. Note that no direct measurements 
of hearing ability have been successfully completed for mysticetes 
(i.e., low-frequency cetaceans). Subsequently, NMFS (2016) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 dB 
threshold from the normalized composite audiograms, with an exception 
for lower limits for low-frequency cetaceans where the result was 
deemed to be biologically implausible and the lower bound from Southall 
et al. (2007) retained. The functional groups and the associated 
frequencies are indicated below (note that these frequency ranges 
correspond to the range for the composite group, with the entire range 
not necessarily reflecting the capabilities of every species within 
that group):
     Low-frequency cetaceans (mysticetes): Generalized hearing 
is estimated to occur between approximately 7 (hertz) Hz and 35 kHz;
     Mid-frequency cetaceans (larger toothed whales, beaked 
whales, and most delphinids): Generalized hearing is estimated to occur 
between approximately 150 Hz and 160 kHz;
     High-frequency cetaceans (porpoises, river dolphins, and 
members of the genera Kogia and Cephalorhynchus; including two members 
of the genus Lagenorhynchus, on the basis of recent echolocation data 
and genetic data): Generalized hearing is estimated to occur between 
approximately 275 Hz and 160 kHz;
     Pinnipeds in water; Phocidae (true seals): Functional 
hearing is estimated to occur between approximately 50 Hz to 86 kHz; 
and
     Pinnipeds in water; Otariidae (eared seals): Functional 
hearing is estimated to occur between approximately 60 Hz and 39 kHz.
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information. 
Six marine mammal species (three cetacean and three phocid pinniped) 
have the potential to co-occur with Hilcorp's LDPI project. Of the 
three cetacean species that may be present, two are classified as low-
frequency cetaceans (i.e., all mysticete species) and one is classified 
as a mid-frequency cetacean (beluga whale).

[[Page 24939]]

Potential Effects of the Specified Activity on Marine Mammals and Their 
Habitat

    This section includes a summary and discussion of the ways that 
components of the specified activity may impact marine mammals and 
their habitat. The Estimated Take by Incidental Harassment section 
later in this document includes a quantitative analysis of the number 
of individuals that are expected to be taken by this activity. The 
Negligible Impact Analysis and Determination section considers the 
content of this section, the Estimated Take by Incidental Harassment 
section, and the Proposed Mitigation section, to draw conclusions 
regarding the likely impacts of these activities on the reproductive 
success or survivorship of individuals and how those impacts on 
individuals are likely to impact marine mammal species or stocks.
    The potential impacts of the proposed LDPI on marine mammals 
involve both non-acoustic and acoustic effects. Potential non-acoustic 
effects could result from the physical presence of personnel, 
structures and equipment, construction or maintenance activities, and 
the occurrence of oil spills. The LDPI project also has the potential 
to result in mortality and serious injury of ringed seals via direct 
physical interaction on ice roads and harass (by Level A harassment and 
Level B harassment) cetaceans and seals via acoustic disturbance. We 
first discuss the effects of ice road and ice trail construction and 
maintenance on ringed seals with respect to direct human interaction 
followed by an in-depth discussion on sound and potential effects on 
marine mammals from acoustic disturbance. The potential for and 
potential impacts from both small and large oil spills are discussed in 
more detail later in this section; however, please note Hilcorp did not 
request, nor is NMFS proposing to authorize, take from oil spills.

Mortality, Serious Injury and Non-Acoustic Harassment--Ice Seals

    This section discusses the potential impacts of ice road 
construction, use and maintenance on ringed seals, the only species 
likely to be encountered during this activity. Acoustic impacts from 
this and other activities (e.g., pile driving) are provided later in 
the document. To assess the potential impacts from ice roads, one must 
understand sea ice dynamics, the influence of ice roads on sea ice, and 
ice seal ecology.
    Sea ice is constantly moving and flexing due to winds, currents, 
and snow load. Sea ice grows (thickens) to its maximum in March, then 
begins to degrade once solar heating increases above the necessary 
threshold. Sea ice will thin and crack due to atmospheric pressure and 
temperature changes. In the absence of ice roads, sea ice is constantly 
cracking, deforming (creating pressure ridges and hummocks), and 
thickening or thinning. Ice road construction interrupts this dynamic 
by permanently thickening and stabilizing the sea ice for the season; 
however, it thins and weakens sea ice adjacent to ice roads due to 
weight of the ice road and use as speed and load of vehicles using the 
road creates pressure waves in the ice, cracking natural ice adjacent 
to the road (pers. comm., M. Williams, August 17, 2018). These cracks 
and thinned ice, occurring either naturally or adjacent to ice roads, 
are easily exploitable habitat for ringed seals.
    As discussed in the Description of Marine Mammal section, ringed 
seals build lairs which are typically concentrated along pressure 
ridges, cracks, leads, or other surface deformations (Smith and 
Stirling 1975, Hammill and Smith, 1989, Furgal et al., 1996). To build 
a lair, a pregnant female will first excavate a breathing hole, most 
easily in cracked or thin ice. The lair will then be excavated (snow 
must be present for lair construction). Later in the season, basking 
holes may be created from collapsed lairs or new basking holes will be 
excavated; both of which must have breathing holes and surface access 
(pers. comm., M. Williams, August 17, 2018).
    Williams et al. (2006) provides the most in-depth discussion of 
ringed seal use around Northstar Island, the first offshore oil and gas 
production facility seaward of the barrier islands in the Alaskan 
Beaufort Sea. Northstar is located 9.5 km from the mainland on a 
manmade gravel island in 12 m of water. In late 2000 and early 2001, 
sea ice in areas near Northstar Island where summer water depth was 
greater than 1.5 m was searched for ringed seal structures. At 
Northstar, ringed seals were documented creating and using sea ice 
structures (basking holes, breathing holes, or birthing lairs) within 
11 to 3,500 m (36 to 11,482 ft) of Northstar infrastructure which 
includes ice roads, pipeline, and the island itself (Williams et al., 
2006). Birth lairs closest to Northstar infrastructure were 882 m and 
144 m (2,894 and 374 ft) from the island and ice road, respectively 
(Williams et al., 2006). Two basking holes were found within 11 and 15 
m (36 and 49 ft) from the nominal centerline of a Northstar ice road 
and were still in use by the end of the study (Williams et al., 2006). 
Although located in deeper water outside of the barrier islands, we 
anticipate ringed seals would use ice around the LDPI and associated 
ice roads in a similar manner.
    Since 1998, there have been three documented incidents of ringed 
seal interactions on North Slope ice roads, with one recorded 
mortality. On April 17, 1998, during a vibroseis on-ice seismic 
operation outside of the barrier islands east of Bullen Point in the 
eastern Beaufort Sea, a ringed seal pup was killed when its lair was 
destroyed by a Caterpillar tractor clearing an ice road. The lair was 
located on ice over water 9 m (29 ft) deep with an ice thickness of 1.3 
m (4.3 ft). It was reported that an adult may have been present in the 
lair when it was destroyed. Crew found blood on the ice near an open 
hole approximately 1.3 km (0.8 mi) from the destroyed lair; this could 
have been from a wounded adult (MacLean, 1998). On April 24, 2018, a 
Tucker (a tracked vehicle used in snow conditions) traveling on a 
Northstar sea ice trail broke through a brine pocket. After moving the 
Tucker, a seal pup climbed out of the hole in the ice, but no adult was 
seen in the area. The seal pup remained in the area for the next day 
and a half. This seal was seen in an area with an estimated water depth 
of 6 to 7 m (20 to 24 ft) (Hilcorp, 2018b). The third reported incident 
occurred on April 28, 2018, when a contractor performing routine 
maintenance activities to relocate metal plates beneath the surface of 
the ice road from Oliktok Point to Spy Island Drill site spotted a 
ringed seal pup next to what may have been a lair site. No adult was 
observed in the area. The pup appeared to be acting normally and was 
seen going in and out of the opening several times (Eni, 2018).
    Overall, NMFS does not anticipate the potential for mortality or 
serious injury of ringed seals to be high given there has been only one 
documented mortality over 25 years of ice road construction in the 
Arctic. However, the potential does exist; therefore, we are including 
a small amount of mortality or serious injury (n = 2) in this proposed 
rule over the five-year life of the regulations. To mitigate this risk, 
NMFS and Hilcorp have developed a number of best management practices 
(BMPs) aimed at reducing the potential of disturbing (e.g., crushing) 
ice seal structures on ice roads (see Proposed Mitigation and 
Monitoring).

Potential Acoustic Impacts--Level A Harassment and Level B Harassment

    In the following discussion, we provide general background 
information

[[Page 24940]]

on sound before considering potential effects to marine mammals from 
sound produced by construction and operation of the LDPI.

Description of Sound Sources

    This section contains a brief technical background on sound, on the 
characteristics of certain sound types, and on metrics used in this 
proposal inasmuch as the information is relevant to the specified 
activity and to a discussion of the potential effects of the specified 
activity on marine mammals found later in this document. For general 
information on sound and its interaction with the marine environment, 
please see, e.g., Au and Hastings (2008); Richardson et al. (1995); 
Urick (1983).
    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per unit of time and 
is measured in Hz or cycles per second. Wavelength is the distance 
between two peaks or corresponding points of a sound wave (length of 
one cycle). Higher frequency sounds have shorter wavelengths than lower 
frequency sounds, and typically attenuate (decrease) more rapidly, 
except in certain cases in shallower water. Amplitude is the height of 
the sound pressure wave or the ``loudness'' of a sound and is typically 
described using the relative unit of the decibel (dB). A sound pressure 
level (SPL) in dB is described as the ratio between a measured pressure 
and a reference pressure (for underwater sound, this is 1 microPascal 
([mu]Pa)), and is a logarithmic unit that accounts for large variations 
in amplitude; therefore, a relatively small change in dB corresponds to 
large changes in sound pressure. The source level (SL) represents the 
SPL referenced at a distance of 1 m from the source (referenced to 1 
[mu]Pa), while the received level is the SPL at the listener's position 
(referenced to 1 [mu]Pa).
    Root mean square (rms) is the quadratic mean sound pressure over 
the duration of an impulse. Root mean square is calculated by squaring 
all of the sound amplitudes, averaging the squares, and then taking the 
square root of the average (Urick, 1983). Root mean square accounts for 
both positive and negative values; squaring the pressures makes all 
values positive so that they may be accounted for in the summation of 
pressure levels (Hastings and Popper, 2005). This measurement is often 
used in the context of discussing behavioral effects, in part because 
behavioral effects, which often result from auditory cues, may be 
better expressed through averaged units than by peak pressures.
    Sound exposure level (SEL; represented as dB re 1 [mu]Pa\2\-s) 
represents the total energy in a stated frequency band over a stated 
time interval or event, and considers both intensity and duration of 
exposure. The per-pulse SEL is calculated over the time window 
containing the entire pulse (i.e., 100 percent of the acoustic energy). 
SEL is a cumulative metric; it can be accumulated over a single pulse, 
or calculated over periods containing multiple pulses. Cumulative SEL 
represents the total energy accumulated by a receiver over a defined 
time window or during an event. Peak sound pressure (also referred to 
as zero-to-peak sound pressure or 0-pk) is the maximum instantaneous 
sound pressure measurable in the water at a specified distance from the 
source, and is represented in the same units as the rms sound pressure.
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as the sound wave travels. Underwater sound waves radiate in a 
manner similar to ripples on the surface of a pond and may be either 
directed in a beam or beams or may radiate in all directions 
(omnidirectional sources), as is the case for sound produced by the 
pile driving activity considered here. The compressions and 
decompressions associated with sound waves are detected as changes in 
pressure by aquatic life and man-made sound receptors such as 
hydrophones.
    Even in the absence of sound from the specified activity, the 
underwater environment is typically loud due to ambient sound, which is 
defined as environmental background sound levels lacking a single 
source or point (Richardson et al., 1995). The sound level of a region 
is defined by the total acoustical energy being generated by known and 
unknown sources. These sources may include physical (e.g., wind and 
waves, earthquakes, ice, atmospheric sound), biological (e.g., sounds 
produced by marine mammals, fish, and invertebrates), and anthropogenic 
(e.g., vessels, dredging, construction) sound. A number of sources 
contribute to ambient sound, including wind and waves, which are a main 
source of naturally occurring ambient sound for frequencies between 200 
Hz and 50 kHz (Mitson, 1995). In general, ambient sound levels tend to 
increase with increasing wind speed and wave height. Precipitation can 
become an important component of total sound at frequencies above 500 
Hz, and possibly down to 100 Hz during quiet times. Marine mammals can 
contribute significantly to ambient sound levels, as can some fish and 
snapping shrimp. The frequency band for biological contributions is 
from approximately 12 Hz to over 100 kHz. Sources of ambient sound 
related to human activity include transportation (surface vessels), 
dredging and construction, oil and gas drilling and production, 
geophysical surveys, sonar, and explosions. Vessel noise typically 
dominates the total ambient sound for frequencies between 20 and 300 
Hz. In general, the frequencies of anthropogenic sounds are below 1 kHz 
and, if higher frequency sound levels are created, they attenuate 
rapidly.
    The sum of the various natural and anthropogenic sound sources that 
comprise ambient sound at any given location and time depends not only 
on the source levels (as determined by current weather conditions and 
levels of biological and human activity) but also on the ability of 
sound to propagate through the environment. In turn, sound propagation 
is dependent on the spatially and temporally varying properties of the 
water column and sea floor, and is frequency-dependent. As a result of 
the dependence on a large number of varying factors, ambient sound 
levels can be expected to vary widely over both coarse and fine spatial 
and temporal scales. Sound levels at a given frequency and location can 
vary by 10-20 decibels (dB) from day to day (Richardson et al., 1995). 
The result is that, depending on the source type and its intensity, 
sound from the specified activity may be a negligible addition to the 
local environment or could form a distinctive signal that may affect 
marine mammals.
    Sounds are often considered to fall into one of two general types: 
Pulsed and non-pulsed (defined in the following). The distinction 
between these two sound types is important because they have differing 
potential to cause physical effects, particularly with regard to 
hearing (e.g., Ward, 1997 in Southall et al., 2007). See Southall et 
al. (2007) for an in-depth discussion of these concepts. The 
distinction between these two sound types is not always obvious, as 
certain signals share properties of both pulsed and non-pulsed sounds. 
A signal near a source could be categorized as a pulse, but due to 
propagation effects as it moves farther from the source, the signal 
duration becomes longer (e.g., Greene and Richardson, 1988).
    Pulsed sound sources (e.g., airguns, explosions, gunshots, sonic 
booms, impact pile driving) produce signals

[[Page 24941]]

that are brief (typically considered to be less than one second), 
broadband, atonal transients (ANSI, 1986, 2005; Harris, 1998; NIOSH, 
1998; ISO, 2003) and occur either as isolated events or repeated in 
some succession. Pulsed sounds are all characterized by a relatively 
rapid rise from ambient pressure to a maximal pressure value followed 
by a rapid decay period that may include a period of diminishing, 
oscillating maximal and minimal pressures, and generally have an 
increased capacity to induce physical injury as compared with sounds 
that lack these features.
    Non-pulsed sounds can be tonal, narrowband, or broadband, brief or 
prolonged, and may be either continuous or intermittent (ANSI, 1995; 
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals 
of short duration but without the essential properties of pulses (e.g., 
rapid rise time). Examples of non-pulsed sounds include those produced 
by vessels, aircraft, machinery operations such as drilling or 
dredging, vibratory pile driving, and active sonar systems. The 
duration of such sounds, as received at a distance, can be greatly 
extended in a highly reverberant environment.
    The impulsive sound generated by impact hammers is characterized by 
rapid rise times and high peak levels. Vibratory hammers produce non-
impulsive, continuous noise at levels significantly lower than those 
produced by impact hammers. Rise time is slower, reducing the 
probability and severity of injury, and sound energy is distributed 
over a greater amount of time (e.g., Nedwell and Edwards, 2002; Carlson 
et al., 2005).

Acoustic Effects

    We previously provided general background information on marine 
mammal hearing (see ``Description of Marine Mammals in the Area of the 
Specified Activity''). Here, we discuss the potential effects of sound 
on marine mammals.
    Potential Effects of Underwater Sound--Note that, in the following 
discussion, we refer in many cases to a review article concerning 
studies of noise-induced hearing loss conducted from 1996-2015 (i.e., 
Finneran, 2015). For study-specific citations, please see that work. 
Anthropogenic sounds cover a broad range of frequencies and sound 
levels and can have a range of highly variable impacts on marine life, 
from none or minor to potentially severe responses, depending on 
received levels, duration of exposure, behavioral context, and various 
other factors. The potential effects of underwater sound from active 
acoustic sources can potentially result in one or more of the 
following: Temporary or permanent hearing impairment, non-auditory 
physical or physiological effects, behavioral disturbance, stress, and 
masking (Richardson et al., 1995; Gordon et al., 2004; Nowacek et al., 
2007; Southall et al., 2007; G[ouml]tz et al., 2009). The degree of 
effect is intrinsically related to the signal characteristics, received 
level, distance from the source, and duration of the sound exposure. In 
general, sudden, high level sounds can cause hearing loss, as can 
longer exposures to lower level sounds. Temporary or permanent loss of 
hearing will occur almost exclusively for noise within an animal's 
hearing range. We first describe specific manifestations of acoustic 
effects before providing discussion specific to pile driving.
    Richardson et al. (1995) described zones of increasing intensity of 
effect that might be expected to occur, in relation to distance from a 
source and assuming that the signal is within an animal's hearing 
range. First is the area within which the acoustic signal would be 
audible (potentially perceived) to the animal but not strong enough to 
elicit any overt behavioral or physiological response. The next zone 
corresponds with the area where the signal is audible to the animal and 
of sufficient intensity to elicit behavioral or physiological 
responsiveness. Third is a zone within which, for signals of high 
intensity, the received level is sufficient to potentially cause 
discomfort or tissue damage to auditory or other systems. Overlaying 
these zones to a certain extent is the area within which masking (i.e., 
when a sound interferes with or masks the ability of an animal to 
detect a signal of interest that is above the absolute hearing 
threshold) may occur; the masking zone may be highly variable in size.
    Potential effects from impulsive sound sources can range in 
severity from effects such as behavioral disturbance or tactile 
perception to physical discomfort, slight injury of the internal organs 
and the auditory system, or mortality (Yelverton et al., 1973). Non-
auditory physiological effects or injuries that theoretically might 
occur in marine mammals exposed to high level underwater sound or as a 
secondary effect of extreme behavioral reactions (e.g., change in dive 
profile as a result of an avoidance reaction) caused by exposure to 
sound include neurological effects, bubble formation, resonance 
effects, and other types of organ or tissue damage (Cox et al., 2006; 
Southall et al., 2007; Zimmer and Tyack, 2007; Tal et al., 2015). The 
construction and operational activities associated with the LDPI do not 
involve the use of devices such as explosives or mid-frequency tactical 
sonar that are associated with these types of effects.

Auditory Threshold Shifts

    NMFS defines threshold shift (TS) as a change, usually an increase, 
in the threshold of audibility at a specified frequency or portion of 
an individual's hearing range above a previously established reference 
level (NMFS, 2018). The amount of threshold shift is customarily 
expressed in decibels (ANSI, 1995). Threshold shift can be permanent 
(PTS) or temporary (TTS). As described in NMFS (2018), there are 
numerous factors to consider when examining the consequence of TS, 
including, but not limited to, the signal temporal pattern (e.g., 
impulsive or non-impulsive), likelihood an individual would be exposed 
for a long enough duration or to a high enough level to induce a TS, 
the magnitude of the TS, time to recovery (seconds to minutes or hours 
to days), the frequency range of the exposure (i.e., spectral content), 
the hearing and vocalization frequency range of the exposed species 
relative to the signal's frequency spectrum (i.e., how animal uses 
sound within the frequency band of the signal; e.g., Kastelein et al., 
2014b), and their overlap (e.g., spatial, temporal, and spectral).
    Marine mammals exposed to high-intensity sound, or to lower-
intensity sound for prolonged periods, can experience hearing threshold 
shift (TS), which is the loss of hearing sensitivity at certain 
frequency ranges (Finneran, 2015). TS can be permanent (PTS), in which 
case the loss of hearing sensitivity is not fully recoverable, or 
temporary (TTS), in which case the animal's hearing threshold would 
recover over time (Southall et al., 2007). Repeated sound exposure that 
leads to TTS could cause PTS. In severe cases of PTS, there can be 
total or partial deafness, while in most cases the animal has an 
impaired ability to hear sounds in specific frequency ranges (Kryter, 
1985).
    When PTS occurs, there is physical damage to the sound receptors in 
the ear (i.e., tissue damage), whereas TTS represents primarily tissue 
fatigue and is reversible (Southall et al., 2007). In addition, other 
investigators have suggested that TTS is within the normal bounds of 
physiological variability and tolerance and does not represent physical 
injury (e.g., Ward, 1997).

[[Page 24942]]

Therefore, NMFS does not consider TTS to constitute auditory injury.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals, and there is no PTS data for cetaceans, but such 
relationships are assumed to be similar to those in humans and other 
terrestrial mammals. PTS typically occurs at exposure levels at least 
several decibels above (a 40-dB threshold shift approximates PTS onset; 
e.g., Kryter et al., 1966; Miller, 1974) that inducing mild TTS (a 6-dB 
threshold shift approximates TTS onset; e.g., Southall et al. 2007). 
Based on data from terrestrial mammals, a precautionary assumption is 
that the PTS thresholds for impulse sounds (such as impact pile driving 
pulses as received close to the source) are at least 6 dB higher than 
the TTS threshold on a peak-pressure basis and PTS cumulative sound 
exposure level thresholds are 15 to 20 dB higher than TTS cumulative 
sound exposure level thresholds (Southall et al., 2007). Given the 
higher level of sound or longer exposure duration necessary to cause 
PTS as compared with TTS, it is considerably less likely that PTS could 
occur.
    TTS is the mildest form of hearing impairment that can occur during 
exposure to sound (Kryter, 1985). While experiencing TTS, the hearing 
threshold rises, and a sound must be at a higher level in order to be 
heard. In terrestrial and marine mammals, TTS can last from minutes or 
hours to days (in cases of strong TTS). In many cases, hearing 
sensitivity recovers rapidly after exposure to the sound ends. Few data 
on sound levels and durations necessary to elicit mild TTS have been 
obtained for marine mammals.
    Marine mammal hearing plays a critical role in communication with 
conspecifics, and interpretation of environmental cues for purposes 
such as predator avoidance and prey capture. Depending on the degree 
(elevation of threshold in dB), duration (i.e., recovery time), and 
frequency range of TTS, and the context in which it is experienced, TTS 
can have effects on marine mammals ranging from discountable to 
serious. For example, a marine mammal may be able to readily compensate 
for a brief, relatively small amount of TTS in a non-critical frequency 
range that occurs during a time where ambient noise is lower and there 
are not as many competing sounds present. Alternatively, a larger 
amount and longer duration of TTS sustained during time when 
communication is critical for successful mother/calf interactions could 
have more serious impacts.
    Currently, TTS data only exist for four species of cetaceans 
(bottlenose dolphin (Tursiops truncatus), beluga whale (Delphinapterus 
leucas), harbor porpoise, and Yangtze finless porpoise (Neophocoena 
asiaeorientalis)) and three species of pinnipeds (northern elephant 
seal, harbor seal, and California sea lion) exposed to a limited number 
of sound sources (i.e., mostly tones and octave-band noise) in 
laboratory settings (Finneran, 2015). TTS was not observed in trained 
spotted (Phoca largha) and ringed (Pusa hispida) seals exposed to 
impulsive noise at levels matching previous predictions of TTS onset 
(Reichmuth et al., 2016). In general, harbor seals and harbor porpoises 
have a lower TTS onset than other measured pinniped or cetacean species 
(Finneran, 2015). Additionally, the existing marine mammal TTS data 
come from a limited number of individuals within these species. There 
are no data available on noise-induced hearing loss for mysticetes. For 
summaries of data on TTS in marine mammals or for further discussion of 
TTS onset thresholds, please see Southall et al. (2007), Finneran and 
Jenkins (2012), Finneran (2015), and NMFS (2018).
    NMFS defines TTS as ``a temporary, reversible increase in the 
threshold of audibility at a specified frequency or portion of an 
individual's hearing range above a previously established reference 
level'' (NMFS, 2016). A TTS of 6 dB is considered the minimum threshold 
shift clearly larger than any day-to-day or session-to-session 
variation in a subject's normal hearing ability (Schlundt et al., 2000; 
Finneran et al., 2000; Finneran et al., 2002, as reviewed in Southall 
et al., 2007 for a review). TTS can last from minutes or hours to days 
(i.e., there is recovery), occur in specific frequency ranges (i.e., an 
animal might only have a temporary loss of hearing sensitivity between 
the frequencies of 1 and 10 kHz)), and can be of varying amounts (for 
example, an animal's hearing sensitivity might be temporarily reduced 
by only 6 dB or reduced by 30 dB). Currently, TTS measurements exist 
for only four species of cetaceans (bottlenose dolphins, belugas, 
harbor porpoises, and Yangtze finless porpoise) and three species of 
pinnipeds (Northern elephant seal, harbor seal, and California sea 
lion). These TTS measurements are from a limited number of individuals 
within these species.
    Depending on the degree (elevation of threshold in dB), duration 
(i.e., recovery time), and frequency range of TTS, and the context in 
which it is experienced, TTS can have effects on marine mammals ranging 
from discountable to serious (similar to those discussed in auditory 
masking, below). For example, a marine mammal may be able to readily 
compensate for a brief, relatively small amount of TTS in a non-
critical frequency range that takes place during a time when the animal 
is traveling through the open ocean, where ambient noise is lower and 
there are not as many competing sounds present. Alternatively, a larger 
amount and longer duration of TTS sustained during time when 
communication is critical for successful mother/calf interactions could 
have more serious impacts. We note that reduced hearing sensitivity as 
a simple function of aging has been observed in marine mammals, as well 
as humans and other taxa (Southall et al., 2007), so we can infer that 
strategies exist for coping with this condition to some degree, though 
likely not without cost.
    Behavioral Effects--Behavioral disturbance from elevated noise 
exposure may include a variety of effects, including subtle changes in 
behavior (e.g., minor or brief avoidance of an area or changes in 
vocalizations), more conspicuous changes in similar behavioral 
activities, and more sustained and/or potentially severe reactions, 
such as displacement from or abandonment of high-quality habitat. 
Behavioral responses to sound are highly variable and context-specific 
and any reactions depend on numerous intrinsic and extrinsic factors 
(e.g., species, state of maturity, experience, current activity, 
reproductive state, auditory sensitivity, time of day), as well as the 
interplay between factors (e.g., Richardson et al., 1995; Wartzok et 
al., 2003; Southall et al., 2007; Weilgart, 2007). Behavioral reactions 
can vary not only among individuals but also within an individual, 
depending on previous experience with a sound source, context, and 
numerous other factors (Ellison et al., 2012), and can vary depending 
on characteristics associated with the sound source (e.g., whether it 
is moving or stationary, number of sources, distance from the source). 
Please see Appendices B-C of Southall et al. (2007) for a review of 
studies involving marine mammal behavioral responses to sound.
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al., 2003). Animals are most likely to habituate to 
sounds that are predictable and unvarying. It is important to note that 
habituation is appropriately considered as a ``progressive reduction in 
response to

[[Page 24943]]

stimuli that are perceived as neither aversive nor beneficial,'' rather 
than as, more generally, moderation in response to human disturbance 
(Bejder et al., 2009). The opposite process is sensitization, when an 
unpleasant experience leads to subsequent responses, often in the form 
of avoidance, at a lower level of exposure. As noted, behavioral state 
may affect the type of response. For example, animals that are resting 
may show greater behavioral change in response to disturbing sound 
levels than animals that are highly motivated to remain in an area for 
feeding (Richardson et al., 1995; NRC, 2003; Wartzok et al., 2003). 
Controlled experiments with captive marine mammals have showed 
pronounced behavioral reactions, including avoidance of loud sound 
sources (Ridgway et al., 1997; Finneran et al., 2003). Observed 
responses of wild marine mammals to loud pulsed sound sources 
(typically airguns or acoustic harassment devices) have been varied but 
often consist of avoidance behavior or other behavioral changes 
suggesting discomfort (Morton and Symonds, 2002; see also Richardson et 
al., 1995; Nowacek et al., 2007). However, many delphinids approach 
low-frequency airgun source vessels with no apparent discomfort or 
obvious behavioral change (e.g., Barkaszi et al., 2012), indicating the 
importance of frequency output in relation to the species' hearing 
sensitivity.
    Available studies show wide variation in response to underwater 
sound; therefore, it is difficult to predict specifically how any given 
sound in a particular instance might affect marine mammals perceiving 
the signal. If a marine mammal does react briefly to an underwater 
sound by changing its behavior or moving a small distance, the impacts 
of the change are unlikely to be significant to the individual, let 
alone the stock or population. However, if a sound source displaces 
marine mammals from an important feeding or breeding area for a 
prolonged period, impacts on individuals and populations could be 
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 
2005). However, there are broad categories of potential response, which 
we describe in greater detail here, that include alteration of dive 
behavior, alteration of foraging behavior, effects to breathing, 
interference with or alteration of vocalization, avoidance, and flight.
    Changes in dive behavior can vary widely and may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et 
al.; 2004; Goldbogen et al., 2013a, 2013b). Variations in dive behavior 
may reflect interruptions in biologically significant activities (e.g., 
foraging) or they may be of little biological significance. The impact 
of an alteration to dive behavior resulting from an acoustic exposure 
depends on what the animal is doing at the time of the exposure and the 
type and magnitude of the response.
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al., 
2001; Nowacek et al.; 2004; Madsen et al., 2006; Yazvenko et al., 
2007). A determination of whether foraging disruptions incur fitness 
consequences would require information on or estimates of the energetic 
requirements of the affected individuals and the relationship between 
prey availability, foraging effort and success, and the life history 
stage of the animal.
    Variations in respiration naturally vary with different behaviors 
and alterations to breathing rate as a function of acoustic exposure 
can be expected to co-occur with other behavioral reactions, such as a 
flight response or an alteration in diving. However, respiration rates 
in and of themselves may be representative of annoyance or an acute 
stress response. Various studies have shown that respiration rates may 
either be unaffected or could increase, depending on the species and 
signal characteristics, again highlighting the importance in 
understanding species differences in the tolerance of underwater noise 
when determining the potential for impacts resulting from anthropogenic 
sound exposure (e.g., Kastelein et al., 2001, 2005, 2006; Gailey et 
al., 2007; Gailey et al., 2016).
    Marine mammals vocalize for different purposes and across multiple 
modes, such as whistling, echolocation click production, calling, and 
singing. Changes in vocalization behavior in response to anthropogenic 
noise can occur for any of these modes and may result from a need to 
compete with an increase in background noise or may reflect increased 
vigilance or a startle response. For example, in the presence of 
potentially masking signals, humpback whales and killer whales have 
been observed to increase the length of their songs (Miller et al., 
2000; Foote et al., 2004), while right whales have been observed to 
shift the frequency content of their calls upward while reducing the 
rate of calling in areas of increased anthropogenic noise (Parks et 
al., 2007). In some cases, animals may cease sound production during 
production of aversive signals (Bowles et al., 1994).
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of disturbance 
in marine mammals (Richardson et al., 1995). For example, gray whales 
are known to change direction--deflecting from customary migratory 
paths--in order to avoid noise from airgun surveys (Malme et al., 
1984). Avoidance may be short-term, with animals returning to the area 
once the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996; 
Stone et al., 2000; Morton and Symonds, 2002; Gailey et al., 2007). 
Longer-term displacement is possible, however, which may lead to 
changes in abundance or distribution patterns of the affected species 
in the affected region if habituation to the presence of the sound does 
not occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann 
et al., 2006).
    A flight response is a dramatic change in normal movement to a 
directed and rapid movement away from the perceived location of a sound 
source. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and 
Heithaus, 1996). The result of a flight response could range from 
brief, temporary exertion and displacement from the area where the 
signal provokes flight to, in extreme cases, marine mammal strandings 
(Evans and England, 2001). However, it should be noted that response to 
a perceived predator does not necessarily invoke flight (Ford and 
Reeves, 2008), and whether individuals are solitary or in groups may 
influence the response.
    Behavioral disturbance can also impact marine mammals in more 
subtle ways. Increased vigilance may result in costs related to 
diversion of focus and attention (i.e., when a response consists of 
increased vigilance, it may come at

[[Page 24944]]

the cost of decreased attention to other critical behaviors such as 
foraging or resting). These effects have generally not been 
demonstrated for marine mammals, but studies involving fish and 
terrestrial animals have shown that increased vigilance may 
substantially reduce feeding rates (e.g., Beauchamp and Livoreil, 1997; 
Fritz et al., 2002; Purser and Radford, 2011). In addition, chronic 
disturbance can cause population declines through reduction of fitness 
(e.g., decline in body condition) and subsequent reduction in 
reproductive success, survival, or both (e.g., Harrington and Veitch, 
1992; Daan et al., 1996; Bradshaw et al., 1998). However, Ridgway et 
al. (2006) reported that increased vigilance in bottlenose dolphins 
exposed to sound over a five-day period did not cause any sleep 
deprivation or stress effects.
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption 
of such functions resulting from reactions to stressors such as sound 
exposure are more likely to be significant if they last more than one 
diel cycle or recur on subsequent days (Southall et al., 2007). 
Consequently, a behavioral response lasting less than one day and not 
recurring on subsequent days is not considered particularly severe 
unless it could directly affect reproduction or survival (Southall et 
al., 2007). Note that there is a difference between multi-day 
substantive behavioral reactions and multi-day anthropogenic 
activities. For example, just because an activity lasts for multiple 
days does not necessarily mean that individual animals are either 
exposed to activity-related stressors for multiple days or, further, 
exposed in a manner resulting in sustained multi-day substantive 
behavioral responses.
    Stress Responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle, 1950; 
Moberg, 2000). In many cases, an animal's first and sometimes most 
economical (in terms of energetic costs) response is behavioral 
avoidance of the potential stressor. Autonomic nervous system responses 
to stress typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that 
are affected by stress--including immune competence, reproduction, 
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been 
implicated in failed reproduction, altered metabolism, reduced immune 
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha, 
2000). Increases in the circulation of glucocorticoids are also equated 
with stress (Romano et al., 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficient to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; 
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker, 2000; 
Romano et al., 2002b) and, more rarely, studied in wild populations 
(e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found 
that noise reduction from reduced ship traffic in the Bay of Fundy was 
associated with decreased stress in North Atlantic right whales. These 
and other studies lead to a reasonable expectation that some marine 
mammals will experience physiological stress responses upon exposure to 
acoustic stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC, 2003).
    Auditory Masking--Sound can disrupt behavior through masking, or 
interfering with, an animal's ability to detect, recognize, or 
discriminate between acoustic signals of interest (e.g., those used for 
intraspecific communication and social interactions, prey detection, 
predator avoidance, navigation) (Richardson et al., 1995; Erbe et al., 
2016). Masking occurs when the receipt of a sound is interfered with by 
another coincident sound at similar frequencies and at similar or 
higher intensity, and may occur whether the sound is natural (e.g., 
snapping shrimp, wind, waves, precipitation) or anthropogenic (e.g., 
shipping, sonar, seismic exploration) in origin. The ability of a noise 
source to mask biologically important sounds depends on the 
characteristics of both the noise source and the signal of interest 
(e.g., signal-to-noise ratio, temporal variability, direction), in 
relation to each other and to an animal's hearing abilities (e.g., 
sensitivity, frequency range, critical ratios, frequency 
discrimination, directional discrimination, age or TTS hearing loss), 
and existing ambient noise and propagation conditions.
    Under certain circumstances, marine mammals experiencing 
significant masking could also be impaired from maximizing their 
performance fitness in survival and reproduction. Therefore, when the 
coincident (masking) sound is man-made, it may be considered harassment 
when disrupting or altering critical behaviors. It is important to 
distinguish TTS and PTS, which persist after the sound exposure, from 
masking, which occurs during the sound exposure. Because masking 
(without resulting in TS) is not associated with abnormal physiological 
function, it is not considered a physiological effect, but rather a 
potential behavioral effect.
    The frequency range of the potentially masking sound is important 
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation 
sounds produced by odontocetes but are more likely to affect detection 
of mysticete communication calls and other potentially important 
natural sounds such as those produced by surf and some prey species. 
The masking of communication signals by anthropogenic noise may be 
considered as a reduction in the communication space of animals (e.g., 
Clark et al., 2009) and may result in energetic or other costs as 
animals change their vocalization behavior (e.g., Miller et al., 2000; 
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2009; Holt 
et al., 2009). Masking can be reduced in situations where the signal 
and noise come from different directions (Richardson et al., 1995), 
through amplitude modulation of the signal, or through other 
compensatory behaviors (Houser and Moore, 2014). Masking can

[[Page 24945]]

be tested directly in captive species (e.g., Erbe, 2008), but in wild 
populations it must be either modeled or inferred from evidence of 
masking compensation. There are few studies addressing real-world 
masking sounds likely to be experienced by marine mammals in the wild 
(e.g., Branstetter et al., 2013).
    Masking affects both senders and receivers of acoustic signals and 
can potentially have long-term chronic effects on marine mammals at the 
population level as well as at the individual level. Low-frequency 
ambient sound levels have increased by as much as 20 dB (more than 
three times in terms of SPL) in the world's ocean from pre-industrial 
periods, with most of the increase from distant commercial shipping 
(Hildebrand, 2009). All anthropogenic sound sources, but especially 
chronic and lower-frequency signals (e.g., from vessel traffic), 
contribute to elevated ambient sound levels, thus intensifying masking.
    Potential Effects of Hilcorp's Activity--As described previously 
(see ``Description of the Specified Activity''), Hilcorp proposes to 
build ice roads, install a pipeline, construct and operate a gravel 
island using impact and vibratory pile driving, and drill for oil in 
Foggy Island Bay. These activities would occur under ice and open water 
conditions (with the exception of ice roads). These activities have the 
potential to harass marine mammals from acoustic disturbance (all 
species) and via human disturbance/presence on ice (ice seals). There 
is also potential for ice seals, specifically ringed seals, to be 
killed in the event a lair is crushed during ice road construction and 
maintenance in undisturbed areas after March 1, annually.
    NMFS analyzed the potential effects of oil and gas activities, 
including construction of a gravel island and associated 
infrastructure, in its 2016 EIS on the Effects of Oil and Gas 
Activities in the Arctic Ocean (NMFS, 2016; available at https://www.fisheries.noaa.gov/resource/document/effects-oil-and-gas-activities-arctic-ocean-final-environmental-impact). Although that 
document focuses on seismic exploration, there is a wealth of 
information in that document on marine mammal impacts from 
anthropogenic noise. More specific to the proposed project, BOEM 
provides a more detailed analysis on the potential impacts of the 
Liberty LDPI in its' EIS on the Liberty Development and Production 
Plan, Beaufort Sea, Alaska, on which NMFS was a cooperating agency 
(BOEM, 2018; available at https://www.boem.gov/Hilcorp-Liberty/). We 
refer to those documents, specifically Chapter 4 of each of those 
documents, as a comprehensive impact assessment but provide a summary 
and complimentary analysis here.
    The effects of pile driving on marine mammals are dependent on 
several factors, including the size, type, and depth of the animal; the 
depth, intensity, and duration of the pile driving sound; the depth of 
the water column; the substrate of the habitat; the standoff distance 
between the pile and the animal; and the sound propagation properties 
of the environment. With both types of pile driving, it is likely that 
the onset of pile driving could result in temporary, short term changes 
in an animal's typical behavioral patterns and/or avoidance of the 
affected area. These behavioral changes may include (as summarized in 
Richardson et al., 1995): Changing durations of surfacing and dives, 
number of blows per surfacing, or moving direction and/or speed; 
reduced/increased vocal activities; changing/cessation of certain 
behavioral activities (such as socializing or feeding); visible startle 
response or aggressive behavior (such as tail/fluke slapping or jaw 
clapping); avoidance of areas where sound sources are located; and/or 
flight responses.
    For all noise-related activities, bowhead and gray whales are not 
anticipated to be exposed to noise above NMFS harassment threshold 
often. As previously described, Hilcorp aims to conduct all pile 
driving during the ice-covered season, as was done at Northstar; 
however, they are allowing for unforeseen scheduling delays. Bowheads 
are not present near LDPI during the winter and are not normally found 
in the development area during mid-summer (July through mid-August) 
when the whales are further east in the Canadian Beaufort. Therefore 
there are no impacts on foraging habitat for bowhead whales during mid-
summer. Starting in late August and continuing until late October, 
bowheads may be exposed to sounds from the proposed activities at LDPI 
or may encounter vessel traffic to and from the island. It is unlikely 
that any whales would be displaced from sounds generated by activities 
at the LDPI due to their distance from the offshore migrating whales, 
and the effects of buffering from the barrier islands. Any displacement 
would be subtle and involve no more than a small proportion of the 
passing bowheads, likely less than that found at Northstar (Richardson, 
2003, 2004; Mcdonald et al., 2012). This is due to the baffling-effect 
of the barrier island between the construction activity and the main 
migratory pathway of bowhead whales. Moreover, mitigation such as 
avoiding pile driving during the fall bowhead whale hunt further 
reduces potential for harassment as whales are migrating offshore.
    Ongoing activities such as drilling may also harass marine mammals; 
however, drilling sounds from artificial islands are relatively low. As 
summarized in Richardson et al. (1995), beluga whales (the cetacean 
most likely to occur in Foggy Island Bay) are often observed near 
drillsites within 100 to 150 m (328.1 to 492.1 ft) from artificial 
islands. Drilling operations at Northstar facility during the open-
water season resulted in brief, minor localized effects on ringed seals 
with no consequences to ringed seal populations (Richardson and 
Williams, 2004). Adult ringed seals seem to tolerate drilling 
activities. Brewer et al. (1993) noted ringed seals were the most 
common marine mammal sighted and did not seem to be disturbed by 
drilling operations at the Kuvlum 1 project in the Beaufort Sea. 
Southall et al. (2007) reviewed literature describing responses of 
pinnipeds to continuous sound and reported that the limited data 
suggest exposures between ~90 and 140 dB re 1 [mu]Pa generally do not 
appear to induce strong behavioral responses in pinnipeds exposed to 
continuous sounds in water. Hilcorp will conduct acoustic monitoring 
during drilling to determine if future incidental take authorizations 
are warranted from LDPI operation.
    The biological significance of many of these behavioral 
disturbances is difficult to predict, especially if the detected 
disturbances appear minor. However, the consequences of behavioral 
modification could be expected to be biologically significant if the 
change affects growth, survival, or reproduction. Significant 
behavioral modifications that could lead to effects on growth, 
survival, or reproduction, such as drastic changes in diving/surfacing 
patterns or significant habitat abandonment are extremely unlikely in 
this area (i.e., shallow waters in modified industrial areas).
    The onset of behavioral disturbance from anthropogenic sound 
depends on both external factors (characteristics of sound sources and 
their paths) and the specific characteristics of the receiving animals 
(hearing, motivation, experience, demography) and is difficult to 
predict (Southall et al., 2007).
    Whether impact or vibratory driving, sound sources would be active 
for relatively short durations, with relation to the durations animals 
use sound (either emitting or receiving) on a daily basis, and over a 
small spatial scale

[[Page 24946]]

relative to marine mammal ranges. Therefore, the potential impacts from 
masking are limited in both time and space. Further, the frequencies 
output of pile driving are low relative to the range of frequencies 
used by most species for vital life functions such as communication or 
foraging. In summary, we expect some masking to occur; however, the 
biological impacts of any potential masking are anticipated to be 
negligible. Finally, any masking that might rise to Level B harassment 
under the MMPA would occur concurrently within the zones of behavioral 
harassment already estimated for vibratory and impact pile driving, and 
which have already been taken into account in the exposure analysis.

Oil Spills

    During the life of the proposed regulations, Hilcorp would be 
actively drilling for crude oil in Foggy Island Bay and transporting 
that oil via a single-phase subsea pipe-in-pipe pipeline from the LDPI 
to shore, where an aboveground pipeline will transport crude to the 
existing Badami pipeline. From there, crude will be transported to the 
Endicott Sales Oil Pipeline, which ties into Pump Station 1 of the 
TransAlaska Pipeline System (TAPS) for eventual delivery to a refinery. 
Whenever oil is being extracted or transported, there is potential for 
a spill. Accidental oil spills have a varying potential to occur and 
with varying impacts on marine mammals. For example, if a spill or 
pipeline leak occurs during the winter, oil would be trapped by the 
ice. However, response may be more difficult due in part to the 
presence of ice. If a spill or leak occurs during the open-water 
season, oil may disperse more widely; however, response time may be 
more prompt. Spills may also be large or small. Small spills are 
defined as spills of less than 1,000 barrels (bbls), and a large spill 
is greater than 1,000 bbls. For reference, 1 bbl equates to 42 gallons.
    Based on BOEM's oil spill analyses in its EIS, the only sized 
spills that are reasonably likely to occur in association with the 
proposed action are small spills (<1,000 bbls) (BOEM, 2017a). Small 
spills, although accidental, occur during oil and gas activities with 
generally routine frequency and are considered likely to occur during 
development, production, and/or decommissioning activities associated 
with the proposed action. BOEM estimates about 70 small spills, most of 
which would be less than 10 bbls, would occur over the life of the 
Liberty Project. Small crude oil spills would not likely occur before 
drilling operations begin. Small refined oil spills may occur during 
development, production, and decommissioning. The majority of small 
spills are likely to occur during the approximate 22-year production 
period, which is an average of about 3 spills per year.
    The majority of small spills would be contained on the proposed 
LDPI or landfast ice (during winter). BOEM anticipates that small 
refined spills that reach the open water would be contained by booms or 
absorbent pads; these small spills would also evaporate and disperse 
within hours to a few days. A 3 bbl refined oil spill during summer is 
anticipated to evaporate and disperse within 24 hours, and a 200 bbl 
refined oil spill during summer is anticipated to evaporate and 
disperse within 3 days (BOEM, 2017a).
    A large spill is a statistically unlikely event. The average number 
of large spills for the proposed action was calculated by multiplying 
the spill rate (Bercha International Inc., 2016; BOEM, 2017a), by the 
estimated barrels produced (0.11779 bbl or 117.79 Million Barrels). By 
adding the mean number of large spills from the proposed LDPI and wells 
(~0.0043) and from pipelines (~0.0024), a mean total of 0.0067 large 
spills were calculated for the proposed action. Based on the mean spill 
number, a Poisson distribution indicates there is a 99.33 percent 
chance that no large spill occurs over the development and production 
phases of the project, and a 0.67 percent chance of one or more large 
spills occurring over the same period. The statistical distribution of 
large spills and gas releases shows that it is much more likely that no 
large spills or releases occur than that one or more occur over the 
life of the project. However, a large spill has the potential to 
seriously harm ESA-listed species and their environment. Assuming one 
large spill occurs instead of zero allows BOEM to more fully estimate 
and describe potential environmental effects (BOEM, 2017a).
    Hilcorp is currently developing its oil spill response plan in 
coordination with the Bureau of Safety and Environmental Enforcement 
(BSEE) who must approve the plan. BSEE oversees oil spill planning and 
preparedness for oil and gas exploration, development, and production 
facilities in both state and Federal offshore waters of the United 
States. NMFS provided BSEE with its recommended marine mammal oil spill 
response protocols available at https://www.fisheries.noaa.gov/resource/document/pinniped-and-cetacean-oil-spill-response-guidelines. 
NMFS has provided BSEE with recommended marine mammal protocols should 
a spill occur. BSEE has indicated NMFS will have opportunity to provide 
comments on Hilcorp's plan during a Federal agency public comment 
period. As noted above, Hilcorp did not request, and NMFS is not 
proposing to authorize, take of marine mammals incidental to oil 
spills. NMFS does not authorize incidental take from oil spills under 
section 101(a)(5)(A) of the MMPA in general, and oil spills are not 
part of the specified activity in this case.

Cetaceans

    While direct mortality of cetaceans is unlikely, exposure to 
spilled oil could lead to skin irritation, baleen fouling (which might 
reduce feeding efficiency), respiratory distress from inhalation of 
hydrocarbon vapors, consumption of some contaminated prey items, and 
temporary displacement from contaminated feeding areas. Geraci and St. 
Aubin (1990) summarize effects of oil on marine mammals, and Bratton et 
al. (1993) provides a synthesis of knowledge of oil effects on bowhead 
whales. The number of whales that might be contacted by a spill would 
depend on the size, timing, and duration of the spill. Whales may not 
avoid oil spills, and some have been observed feeding within oil slicks 
(Goodale et al., 1981).
    The potential effects on cetaceans are expected to be less than 
those on seals (described later in this section of the document). 
Cetaceans tend to occur well offshore where cleanup activities (in the 
open-water season) are unlikely to be as concentrated. Also, cetaceans 
are transient and, during the majority of the year, absent from the 
area. Further, drilling would be postponed during the bowhead whale 
hunt every fall; therefore, the risk to cetaceans during this time, 
when marine mammal presence and subsistence use is high, has been fully 
mitigated.

Pinnipeds

    Ringed, bearded, and spotted seals are present in open-water areas 
during summer and early autumn, and ringed seals remain in the area 
through the ice-covered season. Therefore, an oil spill from LDPI or 
its pipeline could affect seals. Any oil spilled under the ice also has 
the potential to directly contact seals. The most relevant data of 
pinnipeds exposed to oil is from the Exxon Valdez oil spill (EVOS).
    The largest documented impact of a spill, prior to the EVOS, was on 
young seals in January in the Gulf of St. Lawrence (St. Aubin, 1990). 
Intensive and long-term studies were conducted after the EVOS in 
Alaska. There may

[[Page 24947]]

have been a long-term decline of 36 percent in numbers of molting 
harbor seals at oiled haulout sites in Prince William Sound following 
EVOS (Frost et al., 1994a). However, in a reanalysis of those data and 
additional years of surveys, along with an examination of assumptions 
and biases associated with the original data, Hoover-Miller et al. 
(2001) concluded that the EVOS effect had been overestimated. Harbor 
seal pup mortality at oiled beaches was 23% to 26%, which may have been 
higher than natural mortality, although no baseline data for pup 
mortality existed prior to EVOS (Frost et al., 1994a).
    Adult seals rely on a layer of blubber for insulation, and oiling 
of the external surface does not appear to have adverse 
thermoregulatory effects (Kooyman et al., 1976, 1977; St. Aubin, 1990). 
However, newborn seal pups rely on their fur for insulation. Newborn 
ringed seal pups in lairs on the ice could be contaminated through 
contact with oiled mothers. There is the potential that newborn ringed 
seal pups that were contaminated with oil could die from hypothermia. 
Further, contact with oil on the external surfaces can potentially 
cause increased stress and irritation of the eyes of ringed seals 
(Geraci and Smith, 1976; St. Aubin, 1990). These effects seemed to be 
temporary and reversible, but continued exposure of eyes to oil could 
cause permanent damage (St. Aubin, 1990). Corneal ulcers and abrasions, 
conjunctivitis, and swollen nictitating membranes were observed in 
captive ringed seals placed in crude oil-covered water (Geraci and 
Smith, 1976), and in seals in the Antarctic after an oil spill (Lillie, 
1954).
    Marine mammals can ingest oil if their food is contaminated. Oil 
can also be absorbed through the respiratory tract (Geraci and Smith, 
1976; Engelhardt et al., 1977). Some of the ingested oil is voided in 
vomit or feces but some is absorbed and could cause toxic effects 
(Engelhardt, 1981). When returned to clean water, contaminated animals 
can depurate this internal oil (Engelhardt, 1978, 1982, 1985). In 
addition, seals exposed to an oil spill are unlikely to ingest enough 
oil to cause serious internal damage (Geraci and St. Aubin, 1980, 
1982).
    Since ringed seals are found year-round in the U.S. Beaufort Sea 
and more specifically in the project area, an oil spill at any time of 
year could potentially have effects on ringed seals. However, they are 
more widely dispersed during the open-water season. Spotted seals are 
unlikely to be found in the project area during late winter and spring. 
Therefore, they are more likely to be affected by a spill in the summer 
or fall seasons. Bearded seals typically overwinter south of the 
Beaufort Sea. However, some have been reported around Northstar during 
early spring (Moulton et al., 2003b).

Oil Spill Cleanup Activities

    Oil spill cleanup activities could increase disturbance effects on 
either whales or seals, causing temporary disruption and possible 
displacement (BOEM, 2018). General issues related to oil spill cleanup 
activities are discussed earlier in this section for cetaceans. In the 
event of a large spill contacting and extensively oiling coastal 
habitats, the presence of response staff, equipment, and the many 
aircraft involved in the cleanup could (depending on the time of the 
spill and the cleanup) potentially displace seals. If extensive cleanup 
operations occur in the spring, they could cause increased stress and 
reduced pup survival of ringed seals. Oil spill cleanup activity could 
exacerbate and increase disturbance effects on subsistence species, 
cause localized displacement of subsistence species, and alter or 
reduce access to those species by hunters. On the other hand, the 
displacement of marine mammals away from oil-contaminated areas by 
cleanup activities would reduce the likelihood of direct contact with 
oil. Impacts to subsistence uses of marine mammals are discussed later 
in this document (see the ``Impact on Availability of Affected Species 
or Stock for Taking for Subsistence Uses'' section).

Potential Take From Oil Spills

    Hilcorp did not request, and NMFS is not proposing to authorize, 
take of marine mammals incidental to oil spills. Should an oil spill 
occur and marine mammals are killed, injured, or harassed by the spill, 
the ``taking'' would be unauthorized. However, NMFS is including 
mitigation and reporting measures within these proposed regulations to 
minimize risk to marine mammals. Should an oil spill occur at the drill 
site and that oil enter the marine environment such that marine mammals 
are at risk of exposure, NMFS is proposing to include a mitigation 
measure that Hilcorp notify NMFS immediately and cease drilling until 
NMFS can assess the severity of the spill and potential impacts to 
marine mammals. Should the pipeline leak, crude oil transport via the 
pipeline would also cease immediately until the pipeline is repaired. 
In the case of any spill, Hilcorp would immediately initiate 
communication and response protocol per its Oil Spill Response Plan. 
Finally, Hilcorp must maintain the frequency of oil spill response 
training at no less than one two hour session per week.

Anticipated Effects on Marine Mammal Habitat

    The footprint of the LPDI would result in permanent impacts to 
habitats used directly by marine mammals; however, the footprint is 
minimal compared to available habitat within Foggy Island Bay and, 
further, few cetaceans use Foggy Island Bay. BOEM has also required 
mitigation designed to reduce impacts to marine mammal habitat, 
including water quality and habitat disturbance. For example, initial 
island construction (fill placement phase) and pipeline installation/
backfill will occur in winter when fewer fish species are present and 
when water currents are low, which will reduce total suspended solids 
(TSS) distribution. In addition, island armoring will serve to reduce 
erosion and the spread of silt or gravel over potential prey habitat. 
However, increased turbidity and suspended solids resulting from 
artificial island construction or exploratory drilling discharges could 
have adverse impacts on water quality and, if increases persisted for 
extended periods of time; these impacts would be localized but could be 
long term (NOAA, 2016). If oil and gas industry operators comply with 
the U.S. Environmental Protection Agency's Clean Water Act 
requirements, then elevations in turbidity and concentrations of total 
suspended solids resulting from exploratory drilling activity would not 
result in unreasonable degradation of the marine environment (NOAA, 
2016).
    The proposed activities could also affect acoustic habitat (see 
Auditory Masking discussion above), but meaningful impacts are unlikely 
given the low usage of the area by marine mammals and limited pile 
driving during open-water conditions (approximately 2 weeks). There are 
no known foraging hotspots, or habitats of significant biological 
importance to marine mammals present in the marine waters in Foggy 
Island Bay. Migratory pathways for cetaceans exist outside the McClure 
Island group; however, the majority of noise from the project would be 
confined to Foggy Island Bay with low levels potentially propagating 
outside of but close to the McClure Islands during vibratory pile 
driving only (see Figure 5 in Appendix A of Hilcorp's application). In 
addition, pile driving would not occur during the fall bowhead whale 
migration (see Proposed Mitigation section); therefore, no impacts to 
migratory habitats during use is anticipated during this time period.

[[Page 24948]]

    Effects to Prey--Sound may affect marine mammals through impacts on 
the abundance, behavior, or distribution of prey species (e.g., 
crustaceans, cephalopods, fish, zooplankton). Marine mammal prey varies 
by species, season, and location and, for some, is not well documented. 
Here, we describe studies regarding the effects of noise on known 
marine mammal prey.
    Fish utilize the soundscape and components of sound in their 
environment to perform important functions such as foraging, predator 
avoidance, mating, and spawning (e.g., Zelick et al., 1999; Fay, 2009). 
Depending on their hearing anatomy and peripheral sensory structures, 
which vary among species, fishes hear sounds using pressure and 
particle motion sensitivity capabilities and detect the motion of 
surrounding water (Fay et al., 2008). The potential effects of noise on 
fishes depends on the overlapping frequency range, distance from the 
sound source, water depth of exposure, and species-specific hearing 
sensitivity, anatomy, and physiology. Key impacts to fishes may include 
behavioral responses, hearing damage, barotrauma (pressure-related 
injuries), and mortality.
    Fish react to sounds which are especially strong and/or 
intermittent low-frequency sounds, and behavioral responses such as 
flight or avoidance are the most likely effects. Short duration, sharp 
sounds can cause overt or subtle changes in fish behavior and local 
distribution. The reaction of fish to noise depends on the 
physiological state of the fish, past exposures, motivation (e.g., 
feeding, spawning, migration), and other environmental factors. 
Hastings and Popper (2005) identified several studies that suggest fish 
may relocate to avoid certain areas of sound energy. Additional studies 
have documented effects of pile driving on fish, although several are 
based on studies in support of large, multiyear bridge construction 
projects (e.g., Scholik and Yan, 2001, 2002; Popper and Hastings, 
2009). Several studies have demonstrated that impulse sounds might 
affect the distribution and behavior of some fishes, potentially 
impacting foraging opportunities or increasing energetic costs (e.g., 
Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski et al., 
1992; Santulli et al., 1999; Paxton et al., 2017). However, some 
studies have shown no or slight reaction to impulse sounds (e.g., Pena 
et al., 2013; Wardle et al., 2001; Jorgenson and Gyselman, 2009). More 
commonly, though, the impacts of noise on fish are temporary.
    SPLs of sufficient strength have been known to cause injury to fish 
and fish mortality. However, in most fish species, hair cells in the 
ear continuously regenerate and loss of auditory function likely is 
restored when damaged cells are replaced with new cells. Halvorsen et 
al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours 
for one species. Impacts would be most severe when the individual fish 
is close to the source and when the duration of exposure is long. 
Injury caused by barotrauma can range from slight to severe and can 
cause death, and is most likely to occur in fish with swim bladders. 
Barotrauma injuries have been documented during controlled exposure to 
impact pile driving (Halvorsen et al., 2012b; Casper et al., 2013).
    The most likely impact to fish from pile driving activities at the 
project areas would be temporary behavioral avoidance of the area. The 
duration of fish avoidance of an area after pile driving stops is 
unknown, but a rapid return to normal recruitment, distribution and 
behavior is anticipated. In general, impacts to marine mammal prey 
species are expected to be minor and temporary due to the expected 
short daily duration of individual pile driving events and the 
relatively small areas being affected.
    The area likely impacted by the activities is relatively small 
compared to the available habitat in inland waters in the region. Any 
behavioral avoidance by fish of the disturbed area would still leave 
significantly large areas of fish and marine mammal foraging habitat in 
the nearby vicinity. As described in the preceding, the potential for 
the LDPI to affect the availability of prey to marine mammals or to 
meaningfully impact the quality of physical or acoustic habitat is 
considered to be insignificant.

Estimated Take

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this proposed rule, which will 
inform both NMFS' consideration of ``small numbers'' and the negligible 
impact determination.
    Except with respect to certain activities not pertinent here, 
section 3(18) of the MMPA defines ``harassment'' as: Any act of 
pursuit, torment, or annoyance which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would primarily be by Level B harassment, as use 
of pile hammers, drill rigs, and ice-based equipment (e.g., augers, 
trucks) have the potential to result in disruption of behavioral 
patterns for individual marine mammals. There is also some potential 
for auditory injury (Level A harassment) to result during pile driving. 
The proposed mitigation and monitoring measures are expected to 
minimize the severity of such taking to the extent practicable.
    No mortality or serious injury is anticipated as a result of 
exposure to acoustic sources; however, mortality and serious injury of 
ringed seals may occur from ice road construction, use, and maintenance 
conducted after March 1, annually. Below we describe how we estimated 
mortality and serious injury from ice road work followed by a detailed 
acoustic harassment estimation method.

Mortality/Serious Injury (Ice Seals)

    The only species with the potential to incur serious injury or 
mortality during the proposed project are ringed seals during ice road 
construction, use, and maintenance. Other ice seal species are not 
known to use ice roads within the action area. As described in the 
Description of Marine Mammals section, pregnant ringed seals establish 
lairs in shorefast sea ice beginning in early March where pups are born 
and nursed throughout spring (March through May).
    As described in the Potential Effects of the Specified Activity on 
Marine Mammals and Their Habitat section above, there have been only 
three documented interactions with ringed seals despite over 20 years 
of ice road construction on the North Slope; one mortality in 1998 and 
two non-lethal interactions in 2018. All three animals involved were 
seal pups in or near their lairs. The two recent interactions in 2018 
led NMFS to work with the companies involved in the interactions, 
including Hilcorp, to better understand the circumstances behind the 
interactions and to develop a list of BMPs designed to avoid and 
minimize potential harassment. Hilcorp has adopted these BMPs (see 
Proposed Mitigation and Monitoring section); however, the potential for 
mortality remains, albeit low. Because lairs can include both a pup and 
its mother, but interactions with ringed seals are relatively uncommon, 
NMFS is proposing to authorize the taking, by mortality or serious 
injury, of two ringed seals over the course of five years of ice road 
construction.

[[Page 24949]]

Acoustic Harassment

    Generally speaking, we estimate take by considering: (1) Acoustic 
thresholds above which NMFS believes the best available science 
indicates marine mammals will be behaviorally harassed or incur some 
degree of permanent hearing impairment; (2) the area or volume of water 
that will be ensonified above these levels in a day; (3) the density or 
occurrence of marine mammals within these ensonified areas; and, (4) 
and the number of days of activities. We note that while these basic 
factors can contribute to a basic calculation to provide an initial 
prediction of takes, additional information that can qualitatively 
inform take estimates is also sometimes available (e.g., previous 
monitoring results or average group size). Below, we describe the 
factors considered here in more detail and present the proposed take 
estimate.

Acoustic Thresholds

    Using the best available science, NMFS has developed acoustic 
thresholds that identify the received level of underwater sound above 
which exposed marine mammals would be reasonably expected to be 
behaviorally harassed (equated to Level B harassment) or to incur PTS 
of some degree (equated to Level A harassment).
    Level B Harassment for non-explosive sources--Though significantly 
driven by received level, the onset of behavioral disturbance from 
anthropogenic noise exposure is also informed to varying degrees by 
other factors related to the source (e.g., frequency, predictability, 
duty cycle), the environment (e.g., bathymetry), and the receiving 
animals (e.g., hearing, motivation, experience, demography, behavioral 
context) and can be difficult to predict (Southall et al., 2007, 
Ellison et al., 2012). Based on what the available science indicates 
and the practical need to use a threshold based on a factor that is 
both predictable and measurable for most activities, NMFS uses a 
generalized acoustic threshold based on received level to estimate the 
onset of Level B harassment. NMFS predicts that marine mammals are 
likely to be harassed in a manner we consider Level B harassment when 
exposed to underwater anthropogenic noise above received levels of 120 
dB re 1 [mu]Pa (rms) for continuous (e.g., vibratory pile-driving, 
drilling) and above 160 dB re 1 [mu]Pa (rms) for non-explosive 
impulsive (e.g., seismic airguns) or intermittent (e.g., scientific 
sonar) sources.
    Hilcorp's Liberty Project includes the use of continuous, non-
impulsive (vibratory pile driving, drilling, auguring) and 
intermittent, impulsive (impact pile driving) sources, and therefore 
the 120 and 160 dB re 1 [mu]Pa (rms) thresholds are applicable.
    Level A harassment for non-explosive sources--NMFS' Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual 
criteria to assess auditory injury (Level A harassment) to five 
different marine mammal groups (based on hearing sensitivity) as a 
result of exposure to noise from two different types of sources 
(impulsive or non-impulsive). Hilcorp's proposed activity includes the 
use of impulsive (e.g., impact pile driving) and non-impulsive (e.g., 
vibratory pile driving, slope shaping, trenching) sources.
    These thresholds are provided in Table 3. The references, analysis, 
and methodology used in the development of the thresholds are described 
in NMFS 2018 Technical Guidance, which may be accessed at https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                     PTS onset acoustic thresholds * (received level)
             Hearing Group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 219 dB;   Cell 2: LE,LF,24h: 199 dB.
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,MF,24h: 198 dB.
                                          LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 232 dB;   Cell 10: LE,OW,24h: 219 dB.
                                          LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
  calculating PTS onset. If a non-impulsive sound has the potential to exceed the peak sound pressure level
  thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa, and cumulative sound exposure level (LE)
  has a reference value of 1[micro]Pa\2\s. In this Table, thresholds are abbreviated to reflect American
  National Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as
  incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript
  ``flat'' is being included to indicate peak sound pressure should be flat weighted or unweighted within the
  generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates
  the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds)
  and that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could
  be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible,
  it is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and transmission loss 
coefficient.
    In shallow water noise propagation is highly dependent on the 
properties of the bottom and the surface, among other things. 
Parameters such as depth and the bottom properties can vary with 
distance from the source. There is a low-frequency cut-off related to 
the water depth, below which energy is transferred directly into the 
sea floor. Overall, the transmission loss in shallow water is a 
combination of cylindrical spreading effects, bottom interaction 
effects at lower frequencies and scattering losses at high frequencies. 
To estimate ensonfied area, Hilcorp used the parabolic equation (PE) 
modelling algorithm RAMGeo (Collins, 1993) to calculate the 
transmission loss between the source and the receiver (SLR, 2017). The 
full modeling report, including details on modeling methodology and 
procedure and ensonification area figures, can be found in the 
Underwater and Airborne Noise Modelling Report attached as Appendix A 
in Hilcorp's application. We provide a summary here.
    RAMGeo is an efficient and reliable PE algorithm for solving range-

[[Page 24950]]

dependent acoustic problems with fluid seabed geo-acoustic properties. 
The noise sources were assumed to be omnidirectional and modelled as 
point sources. In practice many sources are directional, this 
assumption is conservative. To estimate Level A harassment and Level B 
harassment threshold distances, Hilcorp first obtained one-third octave 
source spectral levels via reference spectral curves with their 
subsequent corrections based on their corresponding overall source 
levels. Table 4 contains estimated source levels and Appendix B in 
Hilcorp's acoustic modeling report contains source spectrum shape used 
in the model (SLR, 2018).

                                                      Table 4--Estimated Source Levels and Duration
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                           Underwater source levels (db
                                                 re: 1 [micro]Pa)
                Activity                 --------------------------------  Airborne (db re: 20[micro]Pa)      Number of        Max. duration per day
                                            Ice-covered     Open-water                                      piles per day
                                              season          season
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pipeline installation (trucks on ice,        169.6-179.1             N/A  74.8-78 @100 m.................             N/A  12 hrs.
 backhoe, ditchwitch).
Sheet pile--vibratory...................             221             185  81 @100 m......................              20  2.5 hrs.\1\
Sheet pile--impact......................           235.7             210  93 @160 m......................  ..............  40 min.\2\
Conductor pipe--vibratory...............  ..............  ..............  ...............................              16  2.5 hrs (proxy from sheet
                                                                                                                            piles).
Conductor pipes/foundation piles--impact           171.7             196  ...............................  ..............  2 hrs.\3\
Slope shaping/armoring..................             n/a             167  64.7 @100 m....................             n/a  9.6 hrs.
Drilling and production.................           170.5             151  80 @200 m......................             n/a  24 hrs.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Estimated based on 20 piles per day, 7.5 min per pile.
\2\ Average duration estimate is 20 min per day.
\3\ Hilcorp estimates 440-6,300 strikes per day.

    Hilcorp relied on operational data from Northstar construction 
activities to estimate LDPI construction activity methods and 
durations. Greene et al. (2008) indicates impact pile driving at 
Northstar was required only to finish off each pile after vibratory 
driving it into the frozen material of old Seal Island. Since Liberty 
will be a newly constructed gravel island, driving sheet piles should 
be easier than was the case at Northstar. Impact sheet pile driving 
therefore may not be required at Liberty and is included in the 
application as a precaution. Hilcorp assumed approximately 2 minutes 
and 100 strikes per pile with a maximum of 20 piles installed per day. 
Blackwell et al. (2004a) observed impact pipe driving at Northstar. On 
most days, one conductor pipe was driven in a day over a period of 5 to 
8.5 hours. The longest day of observation was 10.5 hours in which time 
two pipes were driven. The observation period each day included all 
pipe driving time, but driving was never continuous during the entire 
observation period. Hilcorp applied a correction factor to the 
Northstar duration, assuming pipe driving at the LDPI would actually 
occur for 20 percent of the total installation time logged at 
Northstar.
    The scenarios with theoretical potential for PTS onset are slope 
shaping, vibratory driving, and impact pile driving and pipe driving 
during the open water season. Hilcorp did not model distances to PTS 
thresholds during ice-covered conditions because no cetaceans are 
present in the region during this time and noise levels are expected to 
attenuate very rapidly under ice conditions. Hilcorp did not request, 
nor does NMFS anticipate, take by Level A harassment (PTS) during 
island construction conducted under ice conditions. The following 
discussion on PTS potential is limited to the open-water season.
    Table 5 summarizes Hilcorp's modeled distances to NMFS PTS 
thresholds using the maximum durations identified above (see also 
Tables 16 through 18 in Appendix A of Hilcorp's application for shorter 
durations). We note marine mammals would have to be extremely close to 
the island during slope shaping and pile driving for an extended period 
of time to potentially incur PTS. We find these durations at distance 
are highly unlikely and have concluded the potential for PTS from slope 
shaping and vibratory pile driving for any marine mammal hearing group 
does not exist. Table 6 summarizes distances and ensonified areas to 
NMFS Level B harassment thresholds during ice-covered and open water 
conditions.

                                        Table 5--Radial Distances to NMFS Level A Harassment Thresholds and Ensonified Area During the Open-Water Season
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   Activity (duration) and distance to threshold (ensonified area)
    Marine mammal hearing group     ------------------------------------------------------------------------------------------------------------------------------------------------------------
             (species)                       Slope shaping (9.6 hrs)            Vibratory sheet piling (2.5 hrs)         Impact sheet piling (40 min)           Impact pipe driving (2 hrs)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Low frequency cetaceans (bowhead,    <10 m (0 km\2\).......................  50 m (164 ft)........................  1,940 (11.8 km\2\)...................  87 m (2.38 km\2\)
 gray whales).
Mid frequency cetaceans (belugas)..  n/a...................................  <10 m (0 km\2\)......................  60 m (0.01 km\2\)....................  27 m (0.002 km\2\)
Phocid Pinnipeds (bearded, ringed,   <10 m (0 km\2\).......................  20 m (66 ft).........................  526 m (0.87 km\2\)...................  240 m (0.18 km\2\)
 spotted seals).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 24951]]


               Table 6--Radial Distances to NMFS Level B Harassment Thresholds and Ensonified Area
----------------------------------------------------------------------------------------------------------------
                                    Ice-covered                   Open water \1\
                                 ----------------------------------------------------------------
            Activity                Underwater                                                    Airborne noise
                                    noise--ice-       Min (m)       Median (m)        Max (m)
                                    covered (m)
----------------------------------------------------------------------------------------------------------------
Ice road construction and                    170             n/a             n/a             n/a             <15
 maintenance....................
Pipeline construction...........             210             n/a             n/a             n/a             <15
Sheet pile driving--vibratory...             390          12,000          14,800          17,500              15
Sheet pile driving--impact......              90           1,700           2,050           2,250             100
Conductor pipe/foundation pile                11             300             315             400             100
 driving--impact................
Slope shaping/armoring..........             n/a             880           1,160           1,260             <15
Helicopter (take-off/landing)...             n/a             n/a             n/a             n/a              67
Drilling and Production.........             230              20              55              85              30
----------------------------------------------------------------------------------------------------------------
\1\ Open water results are minimum, median and maximum distance to the appropriate noise threshold across all
  depths calculated in the direction of maximum noise propagation from the source, away from shore. Median
  distances were used to estimate ensonified areas and take calculations.

Marine Mammal Occurrence

    Each fall and summer, NMFS and BOEM conduct an aerial survey in the 
Arctic, the Aerial Survey of Arctic Marine Mammals (ASAMM) surveys. The 
goal of these surveys is to document the distribution and relative 
abundance of bowhead, gray, right, fin and beluga whales and other 
marine mammals in areas of potential oil and natural gas exploration, 
development, and production activities in the Alaskan Beaufort and 
northeastern Chukchi Seas. Traditionally, only fall surveys were 
conducted but then, in the summer of 2012 (mid-July), the first 
dedicated summer survey effort began in the ASAMM Beaufort Sea study 
area. Hilcorp used these ASAMM surveys as the data source to estimate 
seasonal densities of cetaceans (bowhead, gray and beluga whales) in 
the project area. The ASAMM surveys are conducted within blocks that 
overlay the Beaufort and Chukchi Seas oil and gas lease sale areas 
offshore of Alaska (Figure 6-1 in Hilcorp's application), and provide 
sighting data for bowhead, gray, and beluga whales during summer and 
fall months. During the summer and fall, NMFS observed for marine 
mammals on effort for 7,990 km and 9,244 km, respectively, from 2011 
through 2016. Data from those surveys are used for this analysis. We 
note the location of the proposed LDPI project is in ASAMM survey block 
1; the inshore boundary of this block terminates at the McClure Island 
group. It was not until 2016 that on-effort surveys began inside the 
McClure Island group (i.e., Foggy Island Bay) since bowhead whales, the 
focus of the surveys, are not likely to enter the bay. During ASAMM 
surveys in Foggy Island Bay, no marine mammals have been observed. 
Therefore, the density estimates provided here are an overestimate 
because they rely on offshore surveys where marine mammals are 
concentrated.
Bowhead Whale
    Summer and fall bowhead whale densities were calculated using the 
results from ASAMM surveys from 2011 through 2017. The surveys provided 
sightings and effort data by month and season (summer and fall), as 
well as each survey block (Clarke et al., 2012, 2013a, 2014, 2015, 
2017). Bowhead whale densities were calculated in a two-step approach; 
they first calculated a sighting rate of whales per km, then they 
multiplied the transect length by the effective strip width using the 
modeled species-specific effective strip width for an aero commander 
aircraft calculated by Ferguson and Clarke (2013). Where the effective 
strip width is the half-strip width, it must be multiplied by 2 in 
order to encompass both sides of the transect line. Thus whale density 
was calculated as follows: Whales per km\2\ = whales per kilometer/(2 x 
the effective strip width). The effective strip width for bowhead 
whales was calculated to be 1.15 km (CV=0.08). Table 7 contains pooled 
data from 2011 through 2017 Block 1 ASAMM surveys and resulting 
densities.
    The resulting densities are expected to be overestimates for the 
LDPI analysis because data is based on sighting effort outside the 
barrier islands, and bowhead and gray whales rarely occur within the 
barrier islands, while belugas also are found in higher abundance 
outside of Foggy Island Bay.

                                   Table 7--Bowhead Whale Sighting Data From 2011 Through 2017 and Resulting Densities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                             Transect        Number of
                 Year                           Season                    Month             effort (km)    whale sighted     Whale/km       Whale/km\2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
2011.................................  Summer..................  Jul-Aug................             346               1           0.003           0.001
                                       Fall....................  Sept-Oct...............           1,476              24           0.016           0.007
2012.................................  Summer..................  Jul-Aug................           1,493               5           0.003           0.001
                                       Fall....................  Sept-Oct...............           1,086              14           0.013           0.006
2013.................................  Summer..................  Jul-Aug................           1,582              21           0.013           0.006
                                       Fall....................  Sept-Oct...............           1,121              21           0.019           0.008
2014.................................  Summer..................  Jul-Aug................           1,393              17           0.012           0.005
                                       Fall....................  Sept-Oct...............           1,538              79           0.051           0.022
2015.................................  Summer..................  Jul-Aug................           1,262              15           0.012           0.005
                                       Fall....................  Sept-Oct...............           1,663              17           0.010           0.004
2016.................................  Summer..................  Jul-Aug................           1,914              74           0.039           0.017
                                       Fall....................  Sept-Oct...............           2,360              19           0.008           0.004
2017.................................  Summer..................  Jul-Aug................           3,003               8           0.003           0.001

[[Page 24952]]

 
                                       Fall....................  Sept-Oct...............           1,803              85           0.047           0.020
                                      ------------------------------------------------------------------------------------------------------------------
    Total............................                        Summer                               10,993             141       \1\ 0.012       \1\ 0.005
                                                              Fall                                11,047             259       \1\ 0.023      \1\ 0.0010
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Value represents average, not total, across all years per relevant season.

Gray Whales

    Gray whales are rare in the project area and ASAMM aerial survey 
block 1. From 2011 through 2017 only two gray whales have been observed 
during ASAMM block 1 surveys despite over 21,000 miles of trackline 
effort, for a resulting density of zero (Table 8). However, a group of 
baleen whales comprised of both bowhead and gray whales was observed 
during industry marine mammal surveys in Foggy Island Bay in 2008. 
Therefore, Hilcorp has requested, and NMFS proposes to authorize, take, 
by Level B harassment, of two gray whales annually during the effective 
period of the proposed regulations on the chance gray whales enter the 
ensonified zone during LDPI activities.

                                    Table 8--Gray Whale Sighting Data From 2011 Through 2017 and Resulting Densities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                             Transect        Number of
                 Year                           Season                    Month             effort (km)   whales sighted     Whale/km       Whale/km\2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
2011.................................  Summer..................  Jul-Aug................             346               0           0.000           0.000
                                       Fall....................  Sept-Oct...............           1,476               0           0.000           0.000
2012.................................  Summer..................  Jul-Aug................           1,493               0           0.000           0.000
                                       Fall....................  Sept-Oct...............           1,086               0           0.000           0.000
2013.................................  Summer..................  Jul-Aug................           1,582               0           0.000           0.000
                                       Fall....................  Sept-Oct...............           1,121               0           0.000           0.000
2014.................................  Summer..................  Jul-Aug................           1,393               0           0.000           0.000
                                       Fall....................  Sept-Oct...............           1,538               1           0.001           0.000
2015.................................  Summer..................  Jul-Aug................           1,262               0           0.000           0.000
                                       Fall....................  Sept-Oct...............           1,663               0           0.000           0.000
2016.................................  Summer..................  Jul-Aug................           1,914               1           0.001           0.000
                                       Fall....................  Sept-Oct...............           2,360               0           0.000           0.000
2017.................................  Summer..................  Jul-Aug................           3,003               0           0.001           0.000
                                       Fall....................  Sept-Oct...............           1,803               0           0.000           0.000
                                      ------------------------------------------------------------------------------------------------------------------
    Total............................                        Summer                               10,993               1               0           0.000
                                                              Fall                                11,047               1               0           0.000
--------------------------------------------------------------------------------------------------------------------------------------------------------

Beluga Whales
    As with the large whales, beluga whale presence is anticipated to 
be higher outside the barrier islands. Sighting data collected during 
industry marine mammal surveys in Foggy Island Bay (as described in the 
Description of Marine Mammals section) are used to estimate likelihood 
of presence when deriving final proposed take numbers; however, these 
data were not collected in a manner that allows for a derivation of 
density inside the bay or integration into the ASAMM survey data. The 
ASAMM surveys were recently extended into Foggy Island Bay; however, no 
beluga whales or any other cetaceans were observed while within the 
Bay. Table 9 presents block 1 ASAMM survey data and resulting densities 
for beluga whales. We note the 2012 and 2013 ASAMM reports stratified 
beluga whale sightings by depth rather than by survey block. Because 
the final beluga whale take numbers presented in this proposed rule are 
adjusted based on expected presence in the entire bay based on marine 
mammal monitoring by industry in Foggy Island Bay, NMFS did not pursue 
investigating the raw data further and believe the values here are a 
reasonable and conservative representation of density in survey block 1 
based on comparison to other ASAMM survey year sighting rates where 
sightings by blocks are available.

                                   Table 9--Beluga Whale Sighting Data From 2011 Through 2017 and Resulting Densities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                             Transect        Number of
                 Year                           Season                    Month             effort (km)   whales sighted     Whale/km       Whale/km\2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
2011.................................  Summer..................  Jul-Aug................             346               0           0.000           0.000
                                       Fall....................  Sept-Oct...............           1,476               0           0.000           0.000
2012.................................  Summer..................  Jul-Aug................           5,001              47           0.009           0.008
                                       Fall....................  Sept-Oct...............           4,868               5           0.001           0.001
2013.................................  Summer..................  Jul-Aug................           4,270              75           0.018           0.014
                                       Fall....................  Sept-Oct...............           3,372               2           0.001          0.0005
2014.................................  Summer..................  Jul-Aug................           1,393              13           0.009           0.008
                                       Fall....................  Sept-Oct...............           1,538               9           0.006           0.005

[[Page 24953]]

 
2015.................................  Summer..................  Jul-Aug................           1,262              37           0.029           0.024
                                       Fall....................  Sept-Oct...............           1,663               3           0.002           0.001
2016.................................  Summer..................  Jul-Aug................           1,914             349           0.182           0.148
                                       Fall....................  Sept-Oct...............           2,360              15           0.006           0.005
2017.................................  Summer..................  Jul-Aug................           3,003               4           0.001           0.001
                                       Fall....................  Sept-Oct...............           1,803               0           0.000           0.000
                                      ------------------------------------------------------------------------------------------------------------------
    Total............................                        Summer                               17,189             521               0           0.029
                                                              Fall                                17,080              34               0           0.002
--------------------------------------------------------------------------------------------------------------------------------------------------------

Ringed Seals
    Limited data are available on ringed seal densities in the southern 
Beaufort Sea during the winter months; however, ringed seals winter 
ecology studies conducted in the 1980s (Kelly et al., 1986, Frost and 
Burns, 1989) and surveys associated with the Northstar development 
(Williams et al., 2001) provide information on both seal ice-structure 
use (where ice structures include both breathing holes and subnivean 
lairs), and on the density of ice structures.
    Kelly et al. (1986) found that in the southern Beaufort Sea and 
Kotzebue Sound, radio-tagged seals used between 1 and at least 4 
subnivean lairs. The distances between lairs was up to 4 km (10 mi), 
with numerous breathing holes in-between (Kelly et al., 1986). While 
Kelly et al. (1986) calculated the average number of lairs used per 
seal to be 2.85, they also suggested that this was likely to be an 
underestimate. To estimate winter ringed seal density within the 
project area, the average ice structure density of 1.45/km\2\ was 
divided by the average number of ice structures used by an individual 
seal of 2.85 (SD=2.51; Kelly et al., 1986). This results in an 
estimated density of 0.510 ringed seals/km\2\ during the winter months. 
This density is likely to be overestimated due to Kelly et al. (1986)'s 
suggestion that their estimate of the average number of lairs used by a 
seal was an underestimate (the denominator used).
    For spring ringed seal densities, aerial surveys flown in 1997 
through 2002 over Foggy Island Bay and west of Prudhoe Bay during late 
May and early June (Frost et al., 2002, Moulton et al., 2002b, 
Richardson and Williams, 2003), when the greatest percentage of seals 
have abandoned their lairs and are hauled out on the ice (Kelly et al., 
2010), provides the best available information on ringed seal 
densities.
    Because densities were consistently very low where water depth was 
less than 3 m (and these areas are generally frozen solid during the 
ice-covered season) densities have been calculated where water depth 
was greater than 3 m deep (Moulton et al., 2002a, Moulton et al., 
2002b, Richardson and Williams, 2003). Based on the average density of 
surveys flown 1997 to 2002, the uncorrected average density of ringed 
seals during the spring is expected to be 0.548 ringed seals/km\2\. 
Because the number of seals is expected to be much lower during the 
open water season, we estimated summer (open-water) ringed seal density 
to be 50 percent of the spring densities, resulting in an estimated 
density of 0.27 ringed seals/km\2\. Ringed seals remain in the water 
through the fall and in to the winter, however, due to the lack of 
available data on fall densities within the LDPI action area we have 
assumed the same density of ringed seals as in the summer; 0.27 ringed 
seals/km\2\ (see Hilcorp's application and NMFS (2018) for more data 
details).
Bearded Seals
    Industry monitoring surveys for the Northstar development during 
the spring seasons in 1999 (Moulton et al., 2000), 2000 (Moulton et 
al., 2001), 2001 (Moulton et al., 2002a), and 2002 (Moulton et al., 
2003) counted 47 bearded seals (annual mean of 11.75 seals during an 
annual mean of 3,997.5 km\2\ of effort); these data were insufficient 
to calculate a reliable density estimate in each year, no other on 
bearded seal presence were available. Annual reports (Richardson, 2008) 
for years 2000 through 2002 include similar figures. A winter and 
spring density using the four years of Northstar development data 
equates to 0.003 bearded seals per km\2\.
    For the open-water season (summer and fall), bearded seal density 
was calculated as a proportion of the ringed seal summer density based 
on the percentage of pinniped sightings during monitoring surveys in 
1996 (Harris et al., 2001), 2008 (Aerts et al., 2008, Hauser et al., 
2008), and 2012 (HDR, 2012). During these surveys, 63 percent were 
ringed seals, 17 percent were bearded seals and 20 percent were spotted 
seals. Thus, the density of bearded seals during the open water season 
(summer and fall) was calculated as 17 percent of the ringed seal 
density of 0.27 seals/km\2\. This results in an estimated summer 
density for bearded seals of 0.05 seals/km\2\.
Spotted Seals
    Given their seasonal distribution and low numbers in the nearshore 
waters of the central Alaskan Beaufort Sea, no spotted seals are 
expected in the action area during late winter and spring, but a few 
individuals could be expected during the summer or fall. Using the same 
monitoring data described in the bearded seal section above, spotted 
seal density during the open water season (summer and fall) was 
calculated as 20 percent of the ringed seal summer density estimate 
(0.27 seals/km\2\) in the LDPI Project Area. This results in an 
estimated density of 0.05 seals/km\2\.
    A summary of marine mammal densities used to estimate exposures is 
provided, by season and species, in Table 10.

                                  Table 10--Summary of Marine Mammal Densities
----------------------------------------------------------------------------------------------------------------
                                                   Winter (Nov-    Spring (Apr-    Summer (Jul-     Fall (Sept-
            Species                   Stock            Mar)            Jun)            Aug)            Oct)
----------------------------------------------------------------------------------------------------------------
Bowhead whale.................  Western Arctic..               0               0           0.006           0.009

[[Page 24954]]

 
Gray whale....................  Eastern N                      0               0               0               0
                                 Pacific.
Beluga whale..................  Beaufort Sea....               0               0           0.029           0.002
Ringed seal...................  Alaska..........            0.51           0.548            0.27            0.27
Bearded seal..................  Alaska..........           0.003           0.003            0.05            0.05
Spotted seal..................  Alaska..........               0               0            0.05               0
----------------------------------------------------------------------------------------------------------------

Exposure Estimates

    To quantitatively assess exposure of marine mammals to noise from 
the various activities associated with the Liberty Project, Hilcorp 
used the median range to which Level A harassment and Level B 
harassment thresholds were reached for ice road construction and 
maintenance, island construction, vibratory and impact sheet pile 
driving, impact conductor pipe driving, slope shaping, drilling, and 
production. Hilcorp considered the potential for take on any given day 
based on the largest Level B harassment zone for that day.
    For each species, exposure estimates were calculated in a multi-
step process. On any given day of the year, the expected take for that 
day per species was calculated as: Density x ensonified area (of the 
largest Level B harassment zone for that day). Results were then summed 
for the year to provide total exposure estimates per species.
    In some cases, however, the calculated densities alone do not 
reflect the full potential of exposure. For example, beluga whale 
densities are quite low; however, previous marine mammal surveys in 
Foggy Island Bay have identified the potential for them to be there in 
greater numbers than reflected based on NMFS survey data alone. In 
other cases, the potential for exposure is almost discountable (e.g., 
calculated gray whale takes are zero) but given they could appear in 
Foggy Island Bay, Hilcorp has requested take authorization. Hilcorp 
also requested take authorization for bowhead whales despite the lack 
of project-related noise above NMFS harassment thresholds extending 
much beyond the McClure Islands (e.g., see Figure 02 in Appendix D of 
Hilcorp's application) where bowheads are more likely to be found. As 
described in the Marine Mammal Occurrence section, we used density 
based on surveys conducted outside of the McClure Islands; therefore, 
Hilcorp has likely overestimated potential take. However, given the 
sensitivities surrounding this species in the Arctic, we believe a 
precautionary approach is appropriate here to conservatively assess the 
potential effects on the stock and subsistence use.
    Bowhead, gray, and beluga whales have the potential to be present 
and exposed to noise during the open-water season. Work during ice 
conditions (e.g., pipeline installation, ice road construction) does 
not have the potential to harass cetaceans because they are not present 
in the action area. Hilcorp anticipates conducting a maximum of 15 days 
of open-water pile driving and could conduct slope shaping throughout 
the summer. The method described above was used to estimate take, by 
Level B harassment, in year 1 when the LDPI would be constructed.
    There is a very low potential for large whale Level A harassment 
(PTS) from the specified activities given the rarity of bowhead and 
gray whales entering Foggy Island Bay. However, in an abundance of 
caution, Hilcorp has requested, and NMFS proposes to authorize, limited 
Level A harassment takes per year of each species potentially exposed 
to impact pile driving noise (Table 11). Group size was considered in 
Level B harassment take requests in cases where sighting data and group 
size indicate potential for a greater amount of take than calculated 
based on density (e.g., beluga whale take request is higher than 
calculated take estimate). A small amount of the Level B harassment 
exposures were allocated to Level A harassment for the first year of 
work (i.e., pile driving during open water).
    For seals, a straight density estimate was used following the 
method described above. In assessing the calculated results; there was 
no need to adjust take numbers for Level B harassment.
    The amount and manner of take Hilcorp requested, and NMFS proposes 
to authorize, for each species is summarized in Table 11 below. In 
addition to the takes listed below, Hilcorp requests, and NMFS is 
proposing to authorize, a total of two ringed seal mortalities over the 
life of the proposed regulations incidental to ice road construction, 
use, and maintenance.

                                 Table 11--Annual and Total Amount of Proposed Take Incidental to Hilcorp's LDPI Project
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                  Species (stock)
                                                         -----------------------------------------------------------------------------------------------
                          Year                              Bowhead (W                        Beluga        Ringed seal    Bearded seal    Spotted seal
                                                              Arctic)       Gray (ENP)      (Beaufort)         (AK)            (AK)            (AK)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   Level A harassment
--------------------------------------------------------------------------------------------------------------------------------------------------------
1.......................................................               2               2              10               5               2               2
2.......................................................               0               0               0               0               0               0
3.......................................................               0               0               0               0               0               0
4.......................................................               0               0               0               0               0               0
5.......................................................               0               0               0               0               0               0
                                                         -----------------------------------------------------------------------------------------------
    Total Level A harassment............................               2               2              10               5               2               2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   Level B harassment
--------------------------------------------------------------------------------------------------------------------------------------------------------
1.......................................................               6               1              40             336              58              58

[[Page 24955]]

 
2.......................................................               1               1              20               8               1               1
3.......................................................               1               1              20              22               1               1
4.......................................................               1               1              20              18               1               1
5.......................................................               1               1              20              17               1               1
                                                         -----------------------------------------------------------------------------------------------
    Total Level B harassment............................              10               5             120             401              62              62
--------------------------------------------------------------------------------------------------------------------------------------------------------

Proposed Mitigation

    In order to issue an IHA under Section 101(a)(5)(A) and (D) of the 
MMPA, NMFS must set forth the permissible methods of taking pursuant to 
such activity, and other means of effecting the least practicable 
impact on such species or stock and its habitat, paying particular 
attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of such species or stock for 
taking for certain subsistence uses.
    NMFS regulations require applicants for incidental take 
authorizations to include information about the availability and 
feasibility (economic and technological) of equipment, methods, and 
manner of conducting such activity or other means of effecting the 
least practicable adverse impact upon the affected species or stocks 
and their habitat (50 CFR 216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, we 
carefully consider two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat, as 
well as subsistence uses. This considers the nature of the potential 
adverse impact being mitigated (likelihood, scope, range). It further 
considers the likelihood that the measure will be effective if 
implemented (probability of accomplishing the mitigating result if 
implemented as planned) the likelihood of effective implementation 
(probability implemented as planned) and;
    (2) the practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    The mitigation measures presented here are a product of Hilcorp's 
application, recommendations from the Arctic peer review panel 
(available at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act), NMFS' 
recommendations, and public comments on the Federal Register Notice of 
Receipt.

Construction Mitigation Measures

    Hilcorp will aim to construct the island, including completing all 
pile driving, during the ice-covered season (as was done for 
Northstar). Should an ice seal be observed on or near the LDPI by any 
Hilcorp personnel, the sighting will be reported to Hilcorp's 
Environmental Specialist. No construction activity should occur within 
10 m of an ice seal and any vehicles used should use precaution and not 
approach any ice seal within 10 m.
    During the open-water season, the following mitigation measures 
apply: Hilcorp will station two protected species observers (PSOs) on 
elevated platforms on the island during all pile driving in open-water 
conditions (see Proposed Monitoring and Reporting for more details). 
Marine mammal monitoring shall take place from 30 minutes prior to 
initiation of pile driving activity through 30 minutes post-completion 
of pile driving activity. Pre-activity monitoring shall be conducted 
for 30 minutes to ensure that the shutdown zone is clear of marine 
mammals, and pile driving may commence when observers have declared the 
shutdown zone (which equates to the Level A harassment zone in Table 5) 
is clear of marine mammals. In the event of a delay or shutdown of 
activity resulting from marine mammals in the shutdown zone, animals 
shall be allowed to remain in the shutdown zone (i.e., must leave of 
their own volition) and their behavior shall be monitored and 
documented.
    If a marine mammal is approaching a Level A harassment zone and 
pile driving has not commenced, pile driving shall be delayed. Pile 
driving may not commence or resume until either the animal has 
voluntarily left and been visually confirmed beyond the shutdown zone; 
15 minutes have passed without subsequent detections of small cetaceans 
and pinnipeds; or 30 minutes have passed without subsequent detections 
of large cetaceans. NMFS may adjust the shutdown zones pending review 
and approval of an acoustic monitoring report (see Monitoring and 
Reporting).
    Hilcorp will use soft start techniques when impact pile driving. 
Soft start requires contractors to provide an initial set of strikes at 
reduced energy, followed by a thirty-second waiting period, then two 
subsequent reduced energy strike sets. A soft start must be implemented 
at the start of each day's impact pile driving and at any time 
following cessation of impact pile driving for a period of thirty 
minutes or longer.
    In the unlikely event a low frequency cetacean (bowhead or gray 
whale) approaches or enters the Level A harassment zone, pile driving 
would be shut down. If a mid-frequency cetacean (beluga) or pinniped 
(seal) enters the Level A harassment zone during pile driving, Hilcorp 
proposes to complete setting the pile (which takes ten to fifteen 
minutes from commencement) but not initiate additional pile driving of 
new piles until the marine mammal has left and is on a path away from 
the Level A harassment zone. Hilcorp would not commence pile driving if 
any species is observed approaching or within the Level A harassment 
zone during the pre-construction monitoring period.
    If a species for which authorization has not been granted, or a 
species for which authorization has been granted but the authorized 
takes are met, is observed approaching or within the monitoring zone 
(which equates to the Level B harassment zone in Table 6),

[[Page 24956]]

pile driving and removal activities must shut down immediately using 
delay and shut-down procedures. Activities must not resume until the 
animal has been confirmed to have left the area or the observation time 
period, as indicated in above, has elapsed.
    Hilcorp shall install the pipeline during the ice-covered season, 
thereby minimizing noise impacts to marine mammals as noise does not 
propagate well in ice and cetaceans are not present in the action area 
during winter.

Proposed Mitigation for Ice Road Construction, Maintenance, and Use

    During ice road construction, Hilcorp would follow several BMPs 
recently developed through a collaborative effort with NMFS. These BMPs 
are informed by the best available information on how ice roads are 
constructed and maintained and ice seal lairing knowledge. They are 
designed to minimize disturbance and set forth a monitoring and 
reporting plan to improve knowledge. The complete BMP document is 
available on our website at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.
    The ice road BMPs are applicable to construction and maintenance of 
Liberty sea ice roads and sea ice trails in areas where water depth is 
greater than 10 feet (ft) (the minimum depth required to establish 
ringed seal lairs) as well as any open leads in the sea ice requiring a 
temporary bridge during the ice road season. They are organized into 
the following categories: (1) Wildlife training; (2) general BMPs 
implemented throughout the ice road season; (3) BMPs to be implemented 
prior to March 1st; (4) BMPs to be implemented after March 1; and (4) 
reporting. We refer the reader to the complete BMP document on our 
website but provide a summary of provisions here.
    Timing--Hilcorp will construct sea ice roads as early as possible 
(typically December 1 through mid-February) so that the entire corridor 
is disturbed prior to March 1, the known onset of lairing season. 
Blading and snow blowing of ice roads/trails will be limited to the 
previously disturbed and delineated areas to the extent safe and 
practicable. Snow will be plowed or blown from the ice surface so as to 
preserve the safety and integrity of the ice surface for continued use.
    After March 1, annually, blading and snow blowing of ice roads will 
be limited to the previously disturbed ice road/shoulder areas to the 
extent safe and practicable. However, when safety requires a new ice 
trail to be constructed after March 1st, construction activities such 
as drilling holes in the ice to determine ice quality and thickness, 
will be conducted only during daylight hours with good visibility. 
Ringed seal structures will be avoided by a minimum of 150 ft during 
ice testing and new trail construction.
    Personnel--Hilcorp will employ a NMFS-approved, trained 
environmental field specialist who will serve as the primary ice seal 
monitor and main point of contact for any ice seal observations made by 
other Hilcorp staff, employees, or contractors. This person shall be in 
charge of conducting monitoring surveys every other day while the ice 
road is being actively used. The specialist will also be responsible 
for alerting all crew to ice seal sightings and reporting to the 
appropriate officials.
    Training--Prior to initiation of annual sea ice road activities, 
all project personnel associated with ice road construction or use 
(i.e., construction workers, surveyors, vehicle drivers security 
personnel, and the environmental team) will receive annual training on 
these BMPs. Annual training also includes reviewing the company's 
Wildlife Interaction Plan which has been modified to include reference 
to the BMPs and reporting protocol. In addition to the BMPs, other 
topics in the training may include ringed seal reproductive ecology 
(e.g., temporal and spatial lairing behavior, habitat characteristics, 
potential disturbance effect, etc.) and summary of applicable laws and 
regulatory requirements including, but not limited to, MMPA incidental 
take authorization requirements.
    General BMPs To Be Implemented Throughout Season--Hilcorp would 
establish ice road speed limits, delineate the roadways with highly 
visible markers (to avoid vehicles from driving off roadway where ice 
seals may be more likely to lair), and clearly mark corners of rig 
mats, steel plates, and other materials used to bridge sections of 
hazardous ice (to allow for easy location of materials when removed, 
minimizing disturbance to potentially nearby ice seals). Construction, 
maintenance or decommissioning activities associated with ice roads and 
trails will not occur within 150 ft of the observed ring seal, but may 
proceed as soon as the ringed seal, of its own accord, moves farther 
than 150 ft distance away from the activities or has not been observed 
within that area for at least 24 hours. All personnel would be 
prohibited from closely approaching any seal and would be required to 
report all seals sighted within 150 ft of the center of the ice road to 
the designated Environmental Specialist.
    Once the new ice trail is established, tracked vehicle operation 
will be limited to the disturbed area to the extent practicable and 
when safety of personnel is ensured. If an ice road or trail is being 
actively used under daylight conditions with good visibility, a 
dedicated observer (not the vehicle operator) will conduct a survey 
along the sea ice road/trail to observe if any ringed seals are within 
500 ft of the roadway corridor.

Mitigation for Subsistence Uses of Marine Mammals or Plan of 
Cooperation

    Regulations at 50 CFR 216.104(a)(12) further require incidental 
take authorization (ITA) applicants conducting activities that take 
place in Arctic waters to provide a Plan of Cooperation (POC) or 
information that identifies what measures have been taken and/or will 
be taken to minimize adverse effects on the availability of marine 
mammals for subsistence purposes. A plan must include the following:
     A statement that the applicant has notified and provided 
the affected subsistence community with a draft plan of cooperation;
     A schedule for meeting with the affected subsistence 
communities to discuss proposed activities and to resolve potential 
conflicts regarding any aspects of either the operation or the plan of 
cooperation;
     A description of what measures the applicant has taken 
and/or will take to ensure that proposed activities will not interfere 
with subsistence whaling or sealing; and
     What plans the applicant has to continue to meet with the 
affected communities, both prior to and while conducting the activity, 
to resolve conflicts and to notify the communities of any changes in 
the operation.
    Hilcorp submitted a POC to NMFS, dated April 18, 2018, which 
includes all the required elements included in the aforementioned 
regulations (available at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act). The 
POC documents Hilcorp's stakeholder engagement activities, which began 
in 2014 for this project, with subsistence communities within the North 
Slope Region including Nuiqsut, Barrow and Kaktovik, the closest 
villages to the Project Area. The POC includes a description of the 
project, how access to the Project Area will occur, pipeline and island 
construction techniques, and drilling operations. The plan also 
describes the ongoing community outreach cooperation and coordination

[[Page 24957]]

and measures that will be implemented by Hilcorp to minimize adverse 
effects on marine mammal subsistence. The POC is a living document and 
will be updated throughout the LDPI review and permitting process. As 
such, Hilcorp intends to maintain open communication with all 
stakeholders throughout the Liberty permitting and development process. 
In addition, Hilcorp, along with several other North Slope Industry 
participants, has entered into a Conflict Avoidance Agreement (CAA) 
with the AEWC for all North Slope oil and gas activities to minimize 
potential interference with bowhead subsistence hunting. By nature of 
the measures, the mitigation described above also minimizes impacts to 
subsistence users and is not repeated here. Additional mitigation 
measures specific to subsistence use include:
     Avoid impact pile driving during the Cross Island bowhead 
whale hunt which usually occurs from the last week of August through 
mid-September;
     Schedule all non-essential boat, hovercraft, barge, and 
air traffic to avoid conflicting with the timing of the Cross Island 
bowhead hunt; and
     Adhere to all communication and coordination measures 
described in the POC.
    During the comment period on BOEM's EIS for this project and our 
NOR announcing receipt of Hilcorp's application, the AEWC submitted 
comments pertaining to potential effects on subsistence use. The AEWC 
indicated Hilcorp's continued participation in the Open Water Season 
CAA and the Good Neighbor Policy (GNP), along with its willingness to 
work with the Nuiqsut Whaling Captains to mitigate subsistence harvest 
concerns are central to the AEWC's support for the Liberty Project. 
Further, recommendations from the peer-review panel recommended the 
existing POC and CAA should be renewed and implemented annually to 
ensure that project activities are coordinated with the North Slope 
Borough and Alaska Native whaling captains. Therefore, in addition to 
the activity specific mitigation measures above, NMFS is requiring 
Hilcorp to abide by the POC, and remain committed to the GNP throughout 
the life of the regulations. In addition, Hilcorp has committed to 
following the CAA.
    Based on our evaluation of the applicant's proposed measures, NMFS 
has preliminarily determined that the proposed mitigation measures 
provide the means effecting the least practicable impact on the 
affected species or stocks and their habitat, paying particular 
attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of such species or stock for 
subsistence uses.

Proposed Monitoring and Reporting

    In order to issue an LOA for an activity, Section 101(a)(5)(A) of 
the MMPA states that NMFS must set forth requirements pertaining to the 
monitoring and reporting of the authorized taking. NMFS' MMPA 
implementing regulations further describe the information that an 
applicant should provide when requesting an authorization (50 CFR 
216.104(a)(13)), including the means of accomplishing the necessary 
monitoring and reporting that will result in increased knowledge of the 
species and the level of taking or impacts on populations of marine 
mammals.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of significant interactions with marine mammal 
species in action area (e.g., animals that came close to the vessel, 
contacted the gear, or are otherwise rare or displaying unusual 
behavior);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) Action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the action; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or important physical components of marine 
mammal habitat); and
     Mitigation and monitoring effectiveness.

Marine Mammal Monitoring During the Open-Water Season

    Hilcorp shall employ NMFS approved PSOs and conduct marine mammal 
monitoring per the Marine Mammal Monitoring Plan, dated February 12, 
2019. Two PSOs will be placed on either side of the island where pile/
pipe-driving or slope shaping activities are occurring. For example, 
one PSO would be placed on the side where construction activities are 
taking place and the other placed on the opposite side to provide 
complete observer coverage around the island. PSO stations will be 
moved around the island as needed during construction activities to 
provide full coverage. PSOs will be switched out such that they will 
observe for no more than 4 hours at a time and no more than 12 hours in 
a 24-hour period.
    A third island-based PSO will work closely with an aviation 
specialist to monitor the Level B harassment zone during all open-water 
pile and pipe driving using an unmanned aircraft system (UAS). This 
third PSO and the UAS pilot will be located on the island. UAS 
monitoring will also be used during slope shaping, which may occur in 
open water intermittently until August 31 the first year the proposed 
regulations are valid. Should foundation piles be installed the 
subsequent year, the requirement for UAS will be dependent upon the 
success of the program in the previous year and results of any 
preliminary acoustic analysis during year 1 construction (e.g., impact 
driving conductor pipes). Should UAS not be deemed effective and 
construction is ongoing during the open-water season, a vessel-based 
PSO shall observe the monitoring zone during pile and pipe driving.
    During the open-water season, marine mammal monitoring will take 
place from 30 minutes prior to initiation of pile and pipe driving 
activity through 30 minutes post-completion of pile driving activity. 
Pile driving may commence when observers have declared the shutdown 
zone clear of marine mammals. In the event of a delay or shutdown of 
activity resulting from marine mammals in the shutdown zone, animals 
must be allowed to remain in the shutdown zone (i.e., must leave of 
their own volition) and their behavior must be monitored and 
documented.
    During the ice-covered season, in addition to ice road monitoring 
(see below), Hilcorp personnel will report any ice seal sightings on or 
near the LDPI to Hilcorp's Environmental Specialist.

Acoustic Monitoring During the Open-Water Season

    Hilcorp will conduct acoustic monitoring of island construction 
activities during the open-water season in accordance with its Acoustic

[[Page 24958]]

Monitoring Plan available on our website. In summary, Hilcorp proposes 
to annually conduct underwater acoustic monitoring during the open 
water season (July through the beginning of October) using Directional 
Autonomous Seafloor Acoustic Recorders (DASARs). One or more DASARs 
will be deployed at a pre-determined GPS location(s) away from the 
LDPI. Each DASAR will be connected by a ground line to an anchor on the 
seafloor. At the end of the open water season, the DASAR will be 
retrieved by dragging grappling hooks on the seafloor, perpendicular to 
and over the location of the ground line, as defined by the GPS 
locations of the anchor and DASAR. All activities conducted during the 
open water season will be monitored. Goals of the acoustic monitoring 
plan are to characterize LDPI construction and operation noises, 
ambient sound levels, and verify (or amend) modeled distances to NMFS 
harassment thresholds. Recorder arrangement will be configured each 
year based on the anticipated activities for that season and the 
modelled sound propagation estimates for the relevant sources. 
Hilcorp's acoustic monitoring plan can be found at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.

Marine Mammal Monitoring During Ice Road Construction, Maintenance and 
Use

    Hilcorp has prepared a comprehensive ice seal monitoring and 
mitigation plan via development of a BMP document which is available at 
https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act. Hilcorp would be required to 
implement these BMPs; we provide a summary here but encourage the 
public to review the full BMP document.
    Seal surveys will be conducted every other day during daylight 
hours. Observers for ice road activities need not be trained PSOs, but 
they must have received the species observation training and understand 
the applicable sections of Hilcorp's Wildlife Management Plan. In 
addition, they must be capable of detecting, observing and monitoring 
ringed seal presence and behaviors, and accurately and completely 
recording data. Observers will have no other primary duty than to watch 
for and report observations related to ringed seals during this survey. 
If weather conditions become unsafe, the observer may be removed from 
the monitoring activity.
    Construction, maintenance or decommissioning activities associated 
with ice roads and trails will not occur within 150 ft of the observed 
ring seal, but may proceed as soon as the ringed seal, of its own 
accord, moves farther than 150 ft distance away from the activities or 
has not been observed within that area for at least 24 hours. Transport 
vehicles (i.e., vehicles not associated with construction, maintenance 
or decommissioning) may continue their route within the designated 
road/trail without stopping.
    If a ringed seal structure (i.e., breathing hole or lair) is 
observed within 150 ft of the ice road/trail, the location of the 
structure will be reported to the Environmental Specialist who will 
then carry out a notification protocol. A qualified observer will 
monitor the structure every six hours on the day of the initial 
sighting to determine whether a ringed seal is present. Monitoring for 
the seal will occur every other day the ice road is being used unless 
it is determined the structure is not actively being used (i.e., a seal 
is not sighted at that location during monitoring).

Monitoring Plan Peer Review

    The MMPA requires that monitoring plans be independently peer 
reviewed where the proposed activity may affect the availability of a 
species or stock for taking for subsistence uses (16 U.S.C. 
1371(a)(5)(D)(ii)(III)). Regarding this requirement, NMFS' implementing 
regulations state, upon receipt of a complete monitoring plan, and at 
its discretion, NMFS will either submit the plan to members of a peer 
review panel for review or within 60 days of receipt of the proposed 
monitoring plan, schedule a workshop to review the plan (50 CFR 
216.108(d)).
    NMFS established an independent peer review panel (PRP) to review 
Hilcorp's 4MP for the proposed LDPI project in Foggy Island Bay. NMFS 
provided the PRP with Hilcorp's ITA application and monitoring plan and 
asked the panel to answer the following questions:
    1. Will the applicant's stated objectives effectively further the 
understanding of the impacts of their activities on marine mammals and 
otherwise accomplish the goals stated above? If not, how should the 
objectives be modified to better accomplish the goals above?
    2. Can the applicant achieve the stated objectives based on the 
methods described in the plan?
    3. Are there technical modifications to the proposed monitoring 
techniques and methodologies proposed by the applicant that should be 
considered to better accomplish their stated objectives?
    4. Are there techniques not proposed by the applicant (i.e., 
additional monitoring techniques or methodologies) that should be 
considered for inclusion in the applicant's monitoring program to 
better accomplish their stated objectives?
    5. What is the best way for an applicant to present their data and 
results (formatting, metrics, graphics, etc.) in the required reports 
that are to be submitted to NMFS (i.e., 90-day report and comprehensive 
report)?
    The PRP met in May 2018 and subsequently provided a final report to 
NMFS containing recommendations that the panel members felt were 
applicable to Hilcorp's monitoring plans. The PRP concluded the 
objectives for both the visual and acoustic monitoring are appropriate, 
and agrees that the objective of real-time mitigation of potential 
disturbance of marine mammals would be met through visual monitoring. 
The PRP's primary recommendations and comments are summarized and 
addressed below. The PRP's full report is available on our website at 
https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.
    The PRP recommended Hilcorp consult with biologists at the NMFS 
Marine Mammal Laboratory and other scientists and users familiar with 
the use and limitations of UAS technology for studying marine mammals 
at sea regarding appropriate protocols and procedures for the proposed 
project. Hilcorp has worked, and will continue to work, with NMFS to 
develop a safe, effective UAS monitoring program.
    The PRP noted marine mammal monitoring would not be conducted 
during the ice-covered season. Since the PRP met, Hilcorp has developed 
a marine mammal monitoring plan that would be enacted during ice-
covered months along the ice roads and ice trails. These roads lead up 
to the LDPI; therefore, marine mammal monitoring would occur during the 
ice-covered season and occur at the LDPI. NMFS has also included a 
provision that should ice seals be observed on or near the LDPI, they 
shall be reported to Hilcorp's Environmental Specialist and no 
personnel shall approach or operate equipment within 10 m of the seal.
    The PRP was concerned no acoustic monitoring would be conducted 
during the winter months and recommended Hilcorp deploy multiple 
acoustic recorders during ice-covered periods to obtain data on both 
presence of marine

[[Page 24959]]

mammals and sound levels generated during pile driving activities. 
Hilcorp is not proposing to deploy long-term bottom mounted hydrophones 
but will collect measurements using hand-held hydrophones lowered in a 
hole drilled through the ice.
    The PRP also encouraged Hilcorp to consider deployment of 
additional acoustic recorders during the open-water season 
approximately 15 km northwest of the project area to facilitate a 
broader, multi-year approach to analyzing the effect of sound exposure 
on marine mammals by various LDPI and non-LDPI sources. The deployment 
of multiple recorders would provide a measure of redundancy and avoid 
the risk of losing all of the season's data if the recorders are lost 
or malfunction. Hilcorp is proposing to position multiple recorders 
simultaneously to record sound levels at multiple ranges from the 
project activities. Data recorded during times with no project 
activities, if such times exist, will be analyzed for ambient sound 
level statistics. The recorder arrangement will be configured each year 
based on the anticipated activities for that season.
    The PRP recommended that the existing POC and CAA be renewed and 
implemented annually to ensure that project activities are coordinated 
with the North Slope Borough and Alaska Native whaling captains. 
Hilcorp is required to implement the POC and has agreed to implement a 
CAA with the AEWC.

Reporting

    General--A draft report would be submitted to NMFS within 90 days 
of the completion of monitoring for each year the regulations are 
valid. The report will include marine mammal observations pre-activity, 
during-activity, and post-activity during pile driving days, and will 
also provide descriptions of any behavioral responses to construction 
activities by marine mammals and a complete description of all 
mitigation shutdowns and the results of those actions and an 
extrapolated total take estimate based on the number of marine mammals 
observed during the course of construction. A final report must be 
submitted within 30 days following resolution of comments on the draft 
report. Hilcorp would also submit a comprehensive annual summary report 
covering all activities conducted under the incidental take regulations 
no more than 90 days after the regulations expire.

Ice Road Reporting

    On an annual basis, Hilcorp will also submit a draft report to NMFS 
AKR and OPR compiling all ringed seal observations within 90 days of 
decommissioning the ice road and ice trails. The report will include 
information about activities occurring at time of sighting, ringed seal 
age class and behavior, and actions taken to mitigate disturbance. In 
addition the report will include an analysis of the effectiveness of 
the BMPs recently developed in coordination with NMFS and any proposed 
updates to the BMPs or Wildlife Management Plan as a result of the 
encounter. A final report shall be prepared and submitted within thirty 
days following resolution of comments on the draft report from NMFS.
    NMFS is also proposing to require Hilcorp to submit more immediate 
reports should a marine mammal be unexpectantly killed or seriously 
injured by the specified activity or a dead or injured marine mammal is 
observed by a PSO or Hilcorp personnel. These are standard measures 
required by NMFS; details on reporting timelines and information can be 
found in the proposed regulations.

LDPI Construction and Operation Reporting

    Each day of marine mammal monitoring, PSOs will complete field 
sheets containing information NMFS typically requires for pile driving 
and construction activities. The full list of data is provided in 
Hilcorp's Marine Mammal Monitoring and Mitigation Plan and in the 
proposed regulations below. Data include, but are not limited to, 
information on daily activities occurring, marine mammal sighting 
information (e.g., species, group size, and behavior), manner and 
amount of take, and any mitigation actions taken. Data in these field 
sheets will be summarized and Hilcorp will provide a draft annual 
report to NMFS no later than 90 days post marine mammal monitoring 
efforts. Hilcorp would also submit an annual acoustic monitoring report 
no later than 90 days after acoustic recorders are recovered each 
season. The acoustic monitoring reports shall contain measured dB rms, 
SEL and peak values as well as ambient noise levels, per the Acoustic 
Monitoring Plan and as described below in the proposed regulations.
    Hilcorp will also submit to NMFS a draft final report on all marine 
mammal monitoring conducted under the proposed regulations no later 
than ninety calendar days of the completion of marine mammal and 
acoustic monitoring or sixty days prior to the issuance of any 
subsequent regulations, if necessary, for this project, whichever comes 
first. A final report shall be prepared and submitted within thirty 
days following resolution of comments on the draft report from NMFS.

Negligible Impact Analysis and Determination

Introduction

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' by mortality, serious injury, and Level A harassment or Level 
B harassment, we consider other factors, such as the likely nature of 
any behavioral responses (e.g., intensity, duration), the context of 
any such responses (e.g., critical reproductive time or location, 
migration), as well as effects on habitat, and the likely effectiveness 
of mitigation. We also assess the number, intensity, and context of 
estimated takes by evaluating this information relative to population 
status. Consistent with the 1989 preamble for NMFS' implementing 
regulations (54 FR 40338; September 29, 1989), the impacts from other 
past and ongoing anthropogenic activities are incorporated into this 
analysis via their impacts on the environmental baseline (e.g., as 
reflected in the regulatory status of the species, population size and 
growth rate where known, ongoing sources of human-caused mortality, and 
specific consideration of take by M/SI previously authorized for other 
NMFS research activities).
Serious Injury and Mortality
    NMFS is proposing to authorize a very small number of serious 
injuries or mortalities that could occur incidental to ice road 
construction, use, and maintenance. We note here that the takes from 
ice road construction, use, and maintenance enumerated below could 
result in non-serious injury, but their worst potential outcome 
(mortality) is analyzed for the purposes of the negligible impact 
determination.
    In addition, we discuss here the connection, and differences, 
between the legal mechanisms for authorizing incidental take under 
section 101(a)(5) for activities such as LDPI construction

[[Page 24960]]

and operation, and for authorizing incidental take from commercial 
fisheries. In 1988, Congress amended the MMPA's provisions for 
addressing incidental take of marine mammals in commercial fishing 
operations. Congress directed NMFS to develop and recommend a new long-
term regime to govern such incidental taking (see MMC, 1994). The need 
to develop a system suited to the unique circumstances of commercial 
fishing operations led NMFS to suggest a new conceptual means and 
associated regulatory framework. That concept, PBR, and a system for 
developing plans containing regulatory and voluntary measures to reduce 
incidental take for fisheries that exceed PBR were incorporated as 
sections 117 and 118 in the 1994 amendments to the MMPA. In 
Conservation Council for Hawaii v. National Marine Fisheries Service, 
97 F. Supp.3d 1210 (D. Haw. 2015), which concerned a challenge to NMFS' 
regulations and LOAs to the Navy for activities assessed in the 2013--
2018 HSTT MMPA rulemaking, the Court ruled that NMFS' failure to 
consider PBR when evaluating lethal takes in the negligible impact 
analysis under section 101(a)(5)(A) violated the requirement to use the 
best available science.
    PBR is defined in section 3 of the MMPA as the maximum number of 
animals, not including natural mortalities, that may be removed from a 
marine mammal stock while allowing that stock to reach or maintain its 
optimum sustainable population (OSP) and, although not controlling, can 
be one measure considered among other factors when evaluating the 
effects of M/SI on a marine mammal species or stock during the section 
101(a)(5)(A) process. OSP is defined in section 3 of the MMPA as the 
number of animals which will result in the maximum productivity of the 
population or the species, keeping in mind the carrying capacity of the 
habitat and the health of the ecosystem of which they form a 
constituent element. Through section 2, an overarching goal of the 
statute is to ensure that each species or stock of marine mammal is 
maintained at or returned to its OSP.
    PBR values are calculated by NMFS as the level of annual removal 
from a stock that will allow that stock to equilibrate within OSP at 
least 95 percent of the time, and is the product of factors relating to 
the minimum population estimate of the stock (Nmin), the 
productivity rate of the stock at a small population size, and a 
recovery factor. Determination of appropriate values for these three 
elements incorporates significant precaution, such that application of 
the parameter to the management of marine mammal stocks may be 
reasonably certain to achieve the goals of the MMPA. For example, 
calculation of the minimum population estimate (Nmin) 
incorporates the level of precision and degree of variability 
associated with abundance information, while also providing reasonable 
assurance that the stock size is equal to or greater than the estimate 
(Barlow et al., 1995), typically by using the 20th percentile of a log-
normal distribution of the population estimate. In general, the three 
factors are developed on a stock-specific basis in consideration of one 
another in order to produce conservative PBR values that appropriately 
account for both imprecision that may be estimated, as well as 
potential bias stemming from lack of knowledge (Wade, 1998).
    Congress called for PBR to be applied within the management 
framework for commercial fishing incidental take under section 118 of 
the MMPA. As a result, PBR cannot be applied appropriately outside of 
the section 118 regulatory framework without consideration of how it 
applies within the section 118 framework, as well as how the other 
statutory management frameworks in the MMPA differ from the framework 
in section 118. PBR was not designed and is not used as an absolute 
threshold limiting commercial fisheries. Rather, it serves as a means 
to evaluate the relative impacts of those activities on marine mammal 
stocks. Even where commercial fishing is causing M/SI at levels that 
exceed PBR, the fishery is not suspended. When M/SI exceeds PBR in the 
commercial fishing context under section 118, NMFS may develop a take 
reduction plan, usually with the assistance of a take reduction team. 
The take reduction plan will include measures to reduce and/or minimize 
the taking of marine mammals by commercial fisheries to a level below 
the stock's PBR. That is, where the total annual human-caused M/SI 
exceeds PBR, NMFS is not required to halt fishing activities 
contributing to total M/SI but rather utilizes the take reduction 
process to further mitigate the effects of fishery activities via 
additional bycatch reduction measures. In other words, under section 
118 of the MMPA, PBR does not serve as a strict cap on the operation of 
commercial fisheries that may incidentally take marine mammals.
    Similarly, to the extent PBR may be relevant when considering the 
impacts of incidental take from activities other than commercial 
fisheries, using it as the sole reason to deny (or issue) incidental 
take authorization for those activities would be inconsistent with 
Congress's intent under section 101(a)(5), NMFS' long-standing 
regulatory definition of ``negligible impact,'' and the use of PBR 
under section 118. The standard for authorizing incidental take for 
activities other than commercial fisheries under section 101(a)(5) 
continues to be, among other things that are not related to PBR, 
whether the total taking will have a negligible impact on the species 
or stock. Nowhere does section 101(a)(5)(A) reference use of PBR to 
make the negligible impact finding or authorize incidental take through 
multi-year regulations, nor does its companion provision at 
101(a)(5)(D) for authorizing non-lethal incidental take under the same 
negligible-impact standard. NMFS' MMPA implementing regulations state 
that take has a negligible impact when it does not ``adversely affect 
the species or stock through effects on annual rates of recruitment or 
survival''--likewise without reference to PBR. When Congress amended 
the MMPA in 1994 to add section 118 for commercial fishing, it did not 
alter the standards for authorizing non-commercial fishing incidental 
take under section 101(a)(5), implicitly acknowledging that the 
negligible impact standard under section 101(a)(5) is separate from the 
PBR metric under section 118. In fact, in 1994 Congress also amended 
section 101(a)(5)(E) (a separate provision governing commercial fishing 
incidental take for species listed under the ESA) to add compliance 
with the new section 118 but retained the standard of the negligible 
impact finding under section 101(a)(5)(A) (and section 101(a)(5)(D)), 
showing that Congress understood that the determination of negligible 
impact and application of PBR may share certain features but are, in 
fact, different.
    Since the introduction of PBR in 1994, NMFS had used the concept 
almost entirely within the context of implementing sections 117 and 118 
and other commercial fisheries management-related provisions of the 
MMPA. Prior to the Court's ruling in Conservation Council for Hawaii v. 
National Marine Fisheries Service and consideration of PBR in a series 
of section 101(a)(5) rulemakings, there were a few examples where PBR 
had informed agency deliberations under other MMPA sections and 
programs, such as playing a role in the issuance of a few scientific 
research permits and subsistence takings. But as the Court found when 
reviewing examples of past PBR consideration in Georgia Aquarium v. 
Pritzker, 135 F. Supp. 3d 1280 (N.D. Ga.

[[Page 24961]]

2015), where NMFS had considered PBR outside the commercial fisheries 
context, ``it has treated PBR as only one `quantitative tool' and [has 
not used it] as the sole basis for its impact analyses.'' Further, the 
agency's thoughts regarding the appropriate role of PBR in relation to 
MMPA programs outside the commercial fishing context have evolved since 
the agency's early application of PBR to section 101(a)(5) decisions. 
Specifically, NMFS' denial of a request for incidental take 
authorization for the U.S. Coast Guard in 1996 seemingly was based on 
the potential for lethal take in relation to PBR and did not appear to 
consider other factors that might also have informed the potential for 
ship strike in relation to negligible impact (61 FR 54157; October 17, 
1996).
    The MMPA requires that PBR be estimated in SARs and that it be used 
in applications related to the management of take incidental to 
commercial fisheries (i.e., the take reduction planning process 
described in section 118 of the MMPA and the determination of whether a 
stock is ``strategic'' as defined in section 3), but nothing in the 
statute requires the application of PBR outside the management of 
commercial fisheries interactions with marine mammals. Nonetheless, 
NMFS recognizes that as a quantitative metric, PBR may be useful as a 
consideration when evaluating the impacts of other human-caused 
activities on marine mammal stocks. Outside the commercial fishing 
context, and in consideration of all known human-caused mortality, PBR 
can help inform the potential effects of M/SI requested to be 
authorized under 101(a)(5)(A). As noted by NMFS and the U.S. Fish and 
Wildlife Service in our implementation regulations for the 1986 
amendments to the MMPA (54 FR 40341, September 29, 1989), the Services 
consider many factors, when available, in making a negligible impact 
determination, including, but not limited to, the status of the species 
or stock relative to OSP (if known); whether the recruitment rate for 
the species or stock is increasing, decreasing, stable, or unknown; the 
size and distribution of the population; and existing impacts and 
environmental conditions. In this multi-factor analysis, PBR can be a 
useful indicator for when, and to what extent, the agency should take 
an especially close look at the circumstances associated with the 
potential mortality, along with any other factors that could influence 
annual rates of recruitment or survival.
    When considering PBR during evaluation of effects of M/SI under 
section 101(a)(5)(A), we first calculate a metric for each species or 
stock that incorporates information regarding ongoing anthropogenic M/
SI from all sources into the PBR value (i.e., PBR minus the total 
annual anthropogenic mortality/serious injury estimate in the SAR), 
which is called ``residual PBR.'' (Wood et al., 2012). We first focus 
our analysis on residual PBR because it incorporates anthropogenic 
mortality occurring from other sources. If the ongoing human-caused 
mortality from other sources does not exceed PBR, then residual PBR is 
a positive number, and we consider how the anticipated or potential 
incidental M/SI from the activities being evaluated compares to 
residual PBR using the framework in the following paragraph. If the 
ongoing anthropogenic mortality from other sources already exceeds PBR, 
then residual PBR is a negative number and we consider the M/SI from 
the activities being evaluated as described further below.
    When ongoing total anthropogenic mortality from the applicant's 
specified activities does not exceed PBR and residual PBR is a positive 
number, as a simplifying analytical tool we first consider whether the 
specified activities could cause incidental M/SI that is less than 10 
percent of residual PBR (the ``insignificance threshold,'' see below). 
If so, we consider M/SI from the specified activities to represent an 
insignificant incremental increase in ongoing anthropogenic M/SI for 
the marine mammal stock in question that alone (i.e., in the absence of 
any other take) will not adversely affect annual rates of recruitment 
and survival. As such, this amount of M/SI would not be expected to 
affect rates of recruitment or survival in a manner resulting in more 
than a negligible impact on the affected stock unless there are other 
factors that could affect reproduction or survival, such as Level A 
and/or Level B harassment, or other considerations such as information 
that illustrates the uncertainty involved in the calculation of PBR for 
some stocks. In a few prior incidental take rulemakings, this threshold 
was identified as the ``significance threshold,'' but it is more 
accurately labeled an insignificance threshold, and so we use that 
terminology here, as we did in the AFTT Proposed (83 FR 10954; March 
13, 2017) and Final Rules (83 FR 57076; November 14, 2018). Assuming 
that any additional incidental take by Level A or Level B harassment 
from the activities in question would not combine with the effects of 
the authorized M/SI to exceed the negligible impact level, the 
anticipated M/SI caused by the activities being evaluated would have a 
negligible impact on the species or stock. However, M/SI above the 10 
percent insignificance threshold does not indicate that the M/SI 
associated with the specified activities is approaching a level that 
would necessarily exceed negligible impact. Rather, the 10 percent 
insignificance threshold is meant only to identify instances where 
additional analysis of the anticipated M/SI is not required because the 
negligible impact standard clearly will not be exceeded on that basis 
alone.
    Where the anticipated M/SI is near, at, or above residual PBR, 
consideration of other factors (positive or negative), including those 
outlined above, as well as mitigation is especially important to 
assessing whether the M/SI will have a negligible impact on the species 
or stock. PBR is a conservative metric and not sufficiently precise to 
serve as an absolute predictor of population effects upon which 
mortality caps would appropriately be based. For example, in some cases 
stock abundance (which is one of three key inputs into the PBR 
calculation) is underestimated because marine mammal survey data within 
the U.S. EEZ are used to calculate the abundance even when the stock 
range extends well beyond the U.S. EEZ. An underestimate of abundance 
could result in an underestimate of PBR. Alternatively, we sometimes 
may not have complete M/SI data beyond the U.S. EEZ to compare to PBR, 
which could result in an overestimate of residual PBR. The accuracy and 
certainty around the data that feed any PBR calculation, such as the 
abundance estimates, must be carefully considered to evaluate whether 
the calculated PBR accurately reflects the circumstances of the 
particular stock. M/SI that exceeds PBR may still potentially be found 
to be negligible in light of other factors that offset concern, 
especially when robust mitigation and adaptive management provisions 
are included.
    In Conservation Council for Hawaii v. National Marine Fisheries 
Service, which involved the challenge to NMFS' issuance of LOAs to the 
Navy in 2013 for activities in the HSTT Study Area, the Court reached a 
different conclusion, stating, ``Because any mortality level that 
exceeds PBR will not allow the stock to reach or maintain its OSP, such 
a mortality level could not be said to have only a `negligible impact' 
on the stock.'' As described above, the Court's statement fundamentally 
misunderstands the two terms and incorrectly indicates that these 
concepts (PBR and ``negligible

[[Page 24962]]

impact'') are directly connected, when in fact nowhere in the MMPA is 
it indicated that these two terms are equivalent.
    Specifically, PBR was designed as a tool for evaluating mortality 
and is defined as the number of animals that can be removed while 
``allowing that stock to reach or maintain its OSP.'' OSP is defined as 
a population that falls within a range from the population level that 
is the largest supportable within the ecosystem to the population level 
that results in maximum net productivity, and thus is an aspirational 
management goal of the overall statute with no specific timeframe by 
which it should be met. PBR is designed to ensure minimal deviation 
from this overarching goal, with the formula for PBR typically ensuring 
that growth towards OSP is not reduced by more than 10 percent (or 
equilibrates to OSP 95 percent of the time). As PBR is applied by NMFS, 
it provides that growth toward OSP is not reduced by more than 10 
percent, which certainly allows a stock to ``reach or maintain its 
OSP'' in a conservative and precautionary manner--and we can therefore 
clearly conclude that if PBR were not exceeded, there would not be 
adverse effects on the affected species or stocks. Nonetheless, it is 
equally clear that in some cases the time to reach this aspirational 
OSP level could be slowed by more than 10 percent (i.e., total human-
caused mortality in excess of PBR could be allowed) without adversely 
affecting a species or stock through effects on its rates of 
recruitment or survival. Thus even in situations where the inputs to 
calculate PBR are thought to accurately represent factors such as the 
species' or stock's abundance or productivity rate, it is still 
possible for incidental take to have a negligible impact on the species 
or stock even where M/SI exceeds residual PBR or PBR.
    As noted above, PBR is helpful in informing the analysis of the 
effects of mortality on a species or stock because it is important from 
a biological perspective to be able to consider how the total mortality 
in a given year may affect the population. However, section 
101(a)(5)(A) of the MMPA indicates that NMFS shall authorize the 
requested incidental take from a specified activity if we find that the 
total of such taking i.e., from the specified activity will have a 
negligible impact on such species or stock. In other words, the task 
under the statute is to evaluate the applicant's anticipated take in 
relation to their take's impact on the species or stock, not other 
entities' impacts on the species or stock. Neither the MMPA nor NMFS' 
implementing regulations call for consideration of other unrelated 
activities and their impacts on the species or stock. In fact, in 
response to public comments on the implementing regulations NMFS 
explained that such effects are not considered in making negligible 
impact findings under section 101(a)(5), although the extent to which a 
species or stock is being impacted by other anthropogenic activities is 
not ignored. Such effects are reflected in the baseline of existing 
impacts as reflected in the species' or stock's abundance, 
distribution, reproductive rate, and other biological indicators.
    NMFS guidance for commercial fisheries provides insight when 
evaluating the effects of an applicant's incidental take as compared to 
the incidental take caused by other entities. Parallel to section 
101(a)(5)(A), section 101(a)(5)(E) of the MMPA provides that NMFS shall 
allow the incidental take of ESA-listed endangered or threatened marine 
mammals by commercial fisheries if, among other things, the incidental 
M/SI from the commercial fisheries will have a negligible impact on the 
species or stock. As discussed earlier, the authorization of incidental 
take resulting from commercial fisheries and authorization for 
activities other than commercial fisheries are under two separate 
regulatory frameworks. However when it amended the statute in 1994 to 
provide a separate incidental take authorization process for commercial 
fisheries, Congress kept the requirement of a negligible impact 
determination for this one category of species, thereby applying the 
standard to both programs. Therefore, while the structure and other 
standards of the two programs differ such that evaluation of negligible 
impact under one program may not be fully applicable to the other 
program (e.g., the regulatory definition of ``negligible impact'' at 50 
CFR 216.103 applies only to activities other than commercial fishing), 
guidance on determining negligible impact for commercial fishing take 
authorizations can be informative when considering incidental take 
outside the commercial fishing context. In 1999, NMFS published 
criteria for making a negligible impact determination pursuant to 
section 101(a)(5)(E) of the MMPA in a notice of proposed permits for 
certain fisheries (64 FR 28800; May 27, 1999). Criterion 2 stated If 
total human-related serious injuries and mortalities are greater than 
PBR, and fisheries-related mortality is less than 0.1 PBR, individual 
fisheries may be permitted if management measures are being taken to 
address non-fisheries-related serious injuries and mortalities. When 
fisheries-related serious injury and mortality is less than 10 percent 
of the total, the appropriate management action is to address 
components that account for the major portion of the total. This 
criterion addresses when total human-caused mortality is exceeding PBR, 
but the activity being assessed is responsible for only a small portion 
of the mortality. In incidental take authorizations in which NMFS has 
recently articulated a fuller description of how we consider PBR under 
section 101(a)(5)(A), this situation had not arisen, and NMFS' 
description of how we consider PBR in the section 101(a)(5) 
authorization process did not, therefore, include consideration of this 
scenario. However, the analytical framework we use here appropriately 
incorporates elements of the one developed for use under section 
101(a)(5)(E) and because the negligible impact determination under 
section 101(a)(5)(A) focuses on the activity being evaluated, it is 
appropriate to utilize the parallel concept from the framework for 
section 101(a)(5)(E).
    Accordingly, we are using a similar criterion in our negligible 
impact analysis under section 101(a)(5)(A) to evaluate the relative 
role of an applicant's incidental take when other sources of take are 
causing PBR to be exceeded, but the take of the specified activity is 
comparatively small. Where this occurs, we may find that the impacts of 
the taking from the specified activity may (alone) be negligible even 
when total human-caused mortality from all activities exceeds PBR if 
(in the context of a particular species or stock): The authorized 
mortality or serious injury would be less than or equal to 10 percent 
of PBR and management measures are being taken to address serious 
injuries and mortalities from the other activities (i.e., other than 
the specified activities covered by the incidental take authorization 
under consideration). We must also determine, though, that impacts on 
the species or stock from other types of take (i.e., harassment) caused 
by the applicant do not combine with the impacts from mortality or 
serious injury to result in adverse effects on the species or stock 
through effects on annual rates of recruitment or survival.
    As discussed above, however, while PBR is useful in informing the 
evaluation of the effects of M/SI in section 101(a)(5)(A) 
determinations, it is just one consideration to be assessed in 
combination with other factors and is not determinative, including 
because, as explained above, the accuracy and certainty of the data 
used to calculate PBR for the species or stock must be

[[Page 24963]]

considered. And we reiterate the considerations discussed above for why 
it is not appropriate to consider PBR an absolute cap in the 
application of this guidance. Accordingly, we use PBR as a trigger for 
concern while also considering other relevant factors to provide a 
reasonable and appropriate means of evaluating the effects of potential 
mortality on rates of recruitment and survival, while acknowledging 
that it is possible to exceed PBR (or exceed 10 percent of PBR in the 
case where other human-caused mortality is exceeding PBR but the 
specified activity being evaluated is an incremental contributor, as 
described in the last paragraph) by some small amount and still make a 
negligible impact determination under section 101(a)(5)(A).
    A stock-wide PBR is unknown since data is only available for the 
Bering Sea. However, PBR for ringed seals in the Bearing Sea alone, 
considering an Nmin of 5,100. Total annual mortality and 
serious injury is 1,054 for an r-PBR of 4,046 (Muto et al., 2018), 
which means that the insignificance threshold is 405. No mortality or 
serious injury of ringed seals is currently authorized under any other 
incidental take authorization issued pursuant to section 101(a)(5)(A) 
of the MMPA. In the case of Liberty, the proposed authorized taking, by 
mortality, of two ringed seals over the course of 5 years, which 
equates to 0.4 mortality takes annually, is less than 10 percent r-PBR 
when considering mortality and serious injuring caused by other 
anthropogenic sources.
Harassment
    Hilcorp requested, and NMFS proposes, to authorize take, by Level A 
harassment and Level B harassment, of six species of marine mammals. 
The amount of taking proposed to be authorized is low compared to 
marine mammal abundance. Potential impacts of LDPI activities include 
PTS, TTS, and behavioral changes due to exposure to construction and 
operation noise. The potential for Level A harassment occurs during 
impact pile driving. As discussed in the Potential Effects of the 
Specified Activity on Marine Mammals and Their Habitat section, PTS is 
a permanent shift in hearing threshold and the severity of the shift is 
determined by a myriad of factors. Here, we expect cetaceans to incur 
only a slightly elevated shift in hearing threshold because we do not 
except them to be close to the source (especially large whales who 
primarily stay outside the McClure Island group) and that impact pile 
driving (the source with greatest potential to cause PTS) would only 
occur for a maximum of 40 minutes per day. Therefore, the potential for 
large threshold shifts in unlikely. Further, the frequency range of 
hearing that may be impaired is limited to the frequency bands of the 
source. Pile driving exhibits energy in lower frequencies. While low 
frequency baleen whales are most susceptible to this, these are the 
species that are unlikely to come very close to the source. Mid-
frequency cetaceans and phocids do not have best hearing within these 
lower frequency bands of pile driving; therefore, the resulting impact 
of any threshold shift is less likely to impair vital hearing. All 
other noise generated from the project is expected to be low level from 
activities such as slope-shaping and drilling and not result in PTS.
    Cetaceans are infrequent visitors to Foggy Island Bay with primary 
habitat use outside of the McClure Islands. Any taking within Foggy 
Island Bay is not expected to impact reproductive or survival 
activities as the bay is not known to contain critical areas such as 
rookeries, mating grounds, or other areas of similar significance. Some 
ringed seals do lair in Foggy Island Bay; however, the area impacted by 
the project is small compared to available habitat. Further, to offset 
impacts to reproductive behaviors by ringed seals (e.g., lairing, 
pupping), Hilcorp would follow a number of ice road BMPs developed in 
coordination with NMFS ringed seal experts. Hilcorp would also not 
impact pile drive during the bowhead whale hunt, thereby minimizing 
impacts to whales during peak migration periods (we note the peak 
migratory pathway for bowhead whales is well outside the McClure 
Islands). Finally, for reasons described above, the taking of two 
ringed seals, by mortality, over the course of 5 years is not expected 
to have impacts on the species' rates of recruitment and survival.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect the species or stock 
through effects on annual rates of recruitment or survival:
     Only two ringed seals are authorized to be taken by 
mortality over 5 years;
     Any PTS would be of a small degree;
     The amount of takes, by harassment, is low compared to 
population sizes;
     The area ensonified by Hilcorp's activities does not 
provide important areas and is a de minimis subset of habitat used by 
and available to marine mammals;
     Critical behaviors such as lairing and pupping by ringed 
seals would be avoided and minimized through implementation of ice road 
BMPs; and
     Hilcorp would avoid noise-generating activities during the 
bowhead whale hunt; thereby minimizing impact to critical behavior 
(i.e., migration).
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the proposed monitoring and 
mitigation measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity will have a negligible impact on 
all affected marine mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under Section 101(a)(5)(A) of the MMPA for specified 
activities. The MMPA does not define small numbers and so, in practice, 
where estimated numbers are available, NMFS compares the number of 
individuals taken to the most appropriate estimation of abundance of 
the relevant species or stock in our determination of whether an 
authorization is limited to small numbers of marine mammals. 
Additionally, other qualitative factors may be considered in the 
analysis, such as the temporal or spatial scale of the activities.
    The amount of total taking (i.e., Level A harassment, Level B 
harassment, and, for ringed seals, mortality) of any marine mammal 
stock over the course of 5 years, is less than one percent of any 
population (Table 12).

              Table 12--Amount of Proposed Authorized Take Relative to Population Estimates (Nbest)
----------------------------------------------------------------------------------------------------------------
                                                                    Population                      Percent of
                Species                           Stock              estimate       Total take      population
----------------------------------------------------------------------------------------------------------------
Bowhead whale.........................  Arctic..................          16,820              12              <1

[[Page 24964]]

 
Gray whale............................  ENP.....................          20,990               7              <1
Beluga whale..........................  Beaufort Sea............          39,258             130              <1
Ringed seal...........................  Alaska..................         170,000             406              <1
Bearded seal..........................  Alaska..................         299,174              64              <1
Spotted seal..........................  Alaska..................         423,625              64              <1
----------------------------------------------------------------------------------------------------------------

    Based on the analysis contained herein of the proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals will be taken relative to the population 
sizes of the affected species or stocks.

Impact on Availability of Affected Species for Taking for Subsistence 
Uses

    As described in the Marine Mammal section of the document, all 
species potentially taken by Hilcorp's specified activities are key 
subsistence species, in particular the bowhead whales and ice seals. 
Hilcorp has proposed and NMFS has included several mitigation measures 
to address potential impacts on the availability of marine mammals for 
subsistence use. The AEWC provided comments during the public comment 
period on the Notice of Receipt of Hilcorp's application and as a 
member of the peer review panel. NMFS incorporated appropriate 
mitigation to address AEWC's concerns, including requirements for 
Hilcorp to remain a signatory to a follow protocols contained with the 
POC. Hilcorp has also indicated they would abide by a CAA. In addition, 
mitigation measures designed to minimize impacts on marine mammals also 
minimize impacts to subsistence users (e.g., avoid impact pile driving 
during the fall bowhead whale hunt). Hilcorp and NMFS have also 
developed a comprehensive set of BMPs to minimize impacts to ice seals 
during ice-covered months. In consideration of coordination with the 
AEWC, Hilcorp's proposed work schedule (i.e., conducting the majority 
of work in winter when bowhead whales are not present) and the 
incorporation of several mitigation measures, we have preliminarily 
determined that the total taking of affected species or stocks would 
not have an unmitigable adverse impact on the availability of such 
species or stocks for taking for subsistence purposes.

Adaptive Management

    The regulations governing the take of marine mammals incidental to 
Hilcorp's LPDI construction and operational activities would contain an 
adaptive management component.
    The reporting requirements associated with this proposed rule are 
designed to provide NMFS with monitoring data from the previous year to 
allow consideration of whether any changes are appropriate. The use of 
adaptive management allows NMFS to consider new information from 
different sources to determine (with input from Hilcorp regarding 
practicability) on an annual or biennial basis if mitigation or 
monitoring measures should be modified (including additions or 
deletions). Mitigation measures could be modified if new data suggests 
that such modifications would have a reasonable likelihood of reducing 
adverse effects to marine mammals and if the measures are practicable.
    The following are some of the possible sources of applicable data 
to be considered through the adaptive management process: (1) Results 
from monitoring reports, as required by MMPA authorizations; (2) 
results from general marine mammal and sound research; and (3) any 
information which reveals that marine mammals may have been taken in a 
manner, extent, or number not authorized by these regulations or 
subsequent LOAs.

Endangered Species Act (ESA)

    The bowhead whale, ringed seal, and bearded seal (Beringia DPS) are 
listed under the ESA (Table 2). On July 31, 2018, NMFS Alaska Region 
(AKR) issued a Biological Opinion to BOEM, Environmental Protection 
Agency (EPA), and U.S. Army Corps of Engineers (USACE) for the 
permitting of the LDPI Project in its entirety (mobilization to 
decommissioning). The Biological Opinion concluded construction, 
operation, and decommissioning of the LDPI would not jeopardize the 
continued existence of the aforementioned species or adversely modify 
critical habitat. OPR has requested consultation with NMFS Alaska 
Regional Office under section 7 of the ESA on the promulgation of five-
year regulations and the subsequent issuance of LOAs to Hilcorp under 
section 101(a)(5)(A) of the MMPA. This consultation will be concluded 
prior to issuing any final rule.

Request for Information

    NMFS requests interested persons to submit comments, information, 
and suggestions concerning Hilcorp's request and the proposed 
regulations (see ADDRESSES). All comments will be reviewed and 
evaluated as we prepare a final rule and make final determinations on 
whether to issue the requested authorization. This notice and 
referenced documents provide all environmental information relating to 
our proposed action for public review.

Classification

    Pursuant to the procedures established to implement Executive Order 
12866, the Office of Management and Budget has determined that this 
proposed rule is not significant.
    Pursuant to section 605(b) of the Regulatory Flexibility Act (RFA), 
the Chief Counsel for Regulation of the Department of Commerce has 
certified to the Chief Counsel for Advocacy of the Small Business 
Administration that this proposed rule, if adopted, would not have a 
significant economic impact on a substantial number of small entities. 
Hilcorp is the sole entity that would be subject to the requirements in 
these proposed regulations, and the Hilcorp is not a small governmental 
jurisdiction, small organization, or small business, as defined by the 
RFA. Because of this certification, a regulatory flexibility analysis 
is not required and none has been prepared.
    Notwithstanding any other provision of law, no person is required 
to respond to nor shall a person be subject to a penalty for failure to 
comply with a collection of information subject to the requirements of 
the Paperwork Reduction Act (PRA) unless that collection of information 
displays a currently valid OMB control number. This proposed rule 
contains collection-of-information requirements subject to the 
provisions of the PRA. These requirements have been approved by OMB 
under control number 0648-0151

[[Page 24965]]

and include applications for regulations, subsequent LOAs, and reports.

List of Subjects in 50 CFR Part 218

    Marine mammals, Wildlife, Endangered and threatened species, 
Alaska, Oil and gas exploration, Indians, Reporting and recordkeeping 
requirements, Administrative practice and procedure.

    Dated: May 21, 2019.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs, National Marine 
Fisheries Service.

    For reasons set forth in the preamble, 50 CFR part 217 is proposed 
to be amended as follows:

PART 217--REGULATIONS GOVERNING THE TAKING AND IMPORTING OF MARINE 
MAMMALS

0
1. The authority citation for part 217 continues to read as follows:

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

0
2. Add subpart D to part 217 to read as follows:

Subpart D--Taking Marine Mammals Incidental to Construction and 
Operation of the Liberty Drilling and Production Island

Sec.
217.30 Specified activity and specified geographical region.
217.31 Effective dates.
217.32 Permissible methods of taking.
217.33 Prohibitions.
217.34 Mitigation requirements.
217.35 Requirements for monitoring and reporting.
217.36 Letters of Authorization.
217.37 Renewals and modifications of Letters of Authorization.
217.38-217.39 [Reserved]

Subpart D--Taking Marine Mammals Incidental to Construction and 
Operation of the Liberty Drilling and Production Island


Sec.  217.30  Specified activity and specified geographical region.

    (a) Regulations in this subpart apply only to Hilcorp LLC (Hilcorp) 
and those persons it authorizes or funds to conduct activities on its 
behalf for the taking of marine mammals that occurs in the areas 
outlined in paragraph (b) of this section and that occurs incidental to 
construction, maintenance, and operation of the Liberty Drilling and 
Production Island (LDPI) and associated infrastructure.
    (b) The taking of marine mammals by Hilcorp may be authorized in a 
Letter of Authorization (LOA) only if it occurs within the Beaufort 
Sea, Alaska.


Sec.  217.31  Effective dates.

    Regulations in this subpart are effective from December 1, 2020, 
through November 30, 2025.


Sec.  217.32  Permissible methods of taking.

    Under LOAs issued pursuant to Sec. Sec.  216.106 of this chapter 
and 217.36, the Holder of the LOA (hereinafter ``Hilcorp'') may 
incidentally, but not intentionally, take marine mammals within the 
area described in Sec.  217.30(b) by mortality, serious injury, Level A 
harassment, or Level B harassment associated with the LDPI construction 
and operation activities, including associated infrastructure, provided 
the activities are in compliance with all terms, conditions, and 
requirements of the regulations in this subpart and the appropriate 
LOA.


Sec.  217.33  Prohibitions.

    Notwithstanding takings contemplated in Sec.  217.32 and authorized 
by a LOA issued under Sec. Sec.  216.106 of this chapter and 217.36, no 
person in connection with the activities described in Sec.  217.30 may:
    (a) Violate, or fail to comply with, the terms, conditions, and 
requirements of this subpart or a LOA issued under Sec. Sec.  216.106 
of this chapter and 217.36;
    (b) Take any marine mammal not specified in such LOAs;
    (c) Take any marine mammal specified in such LOAs in any manner 
other than as specified;
    (d) Take a marine mammal specified in such LOAs if NMFS determines 
such taking results in more than a negligible impact on the species or 
stocks of such marine mammal; or
    (e) Take a marine mammal specified in such LOAs if NMFS determines 
such taking results in an unmitigable adverse impact on the species or 
stock of such marine mammal for taking for subsistence uses.


Sec.  217.34  Mitigation requirements.

    When conducting the activities identified in Sec.  217.30(a), the 
mitigation measures contained in any LOA issued under Sec.  216.106 of 
this chapter must be implemented. These mitigation measures shall 
include but are not limited to:
    (a) General conditions. (1) Hilcorp must renew, on an annual basis, 
the Plan of Cooperation (POC), throughout the life of the regulations;
    (2) A copy of any issued LOA must be in the possession of Hilcorp, 
its designees, and work crew personnel operating under the authority of 
the issued LOA;
    (3) Hilcorp must conduct briefings for construction and ice road 
supervisors and crews, and the marine mammal and acoustic monitoring 
teams prior to the start of annual ice road or LDPI construction, and 
when new personnel join the work, in order to explain responsibilities, 
communication procedures, the marine mammal monitoring protocol, and 
operational procedures;
    (4) Hilcorp must allow subsistence hunters to use the LDPI for safe 
harbor during severe storms, if requested by hunters;
    (5) In the unanticipated event of an oil spill during LDPI 
operational years, Hilcorp must notify NMFS of the spill within 48 
hours, regardless of size, and implement measures contained within the 
Liberty Oil Spill Response Plan; and
    (6) Hilcorp must strive to complete pile driving and pipeline 
installation during the ice-covered season.
    (b) Ice road construction, maintenance, and operation. (1) Hilcorp 
must implement the NMFS-approved Ice Road and Ice Trail Best Management 
Practices (BMPs) and the Wildlife Action Plan. These documents may be 
updated as needed throughout the life of the regulations, in 
consultation with NMFS.
    (2) [Reserved]
    (c) Liberty Drilling Production Island Construction. (1) For all 
pile driving, Hilcorp shall implement a minimum shutdown zone of a 10 
meter (m) radius from piles being driven. If a marine mammal comes 
within or is about to enter the shutdown zone, such operations shall 
cease immediately;
    (2) For all pile driving activity, Hilcorp shall implement shutdown 
zones with radial distances as identified in any LOA issued under 
Sec. Sec.  216.106 of this chapter and 217.36. If a marine mammal comes 
within or is about to enter the shutdown zone, such operations must 
cease immediately;
    (3) Hilcorp must employ NMFS-approved protected species observers 
(PSOs) and designate monitoring zones with radial distances as 
identified in any LOA issued under Sec. Sec.  216.106 of this chapter 
and 217.36. NMFS may adjust the shutdown zones pending review and 
approval of an acoustic monitoring report (see Sec.  217.35 
Requirements for Monitoring and Reporting);
    (4) If a bowhead whale or other low frequency cetacean enters the 
Level A harassment zone, pile or pipe driving must be shut down 
immediately. If a beluga whale or pinniped enters the Level A 
harassment zone while pile driving is ongoing, work may continue until 
the pile is completed (estimated to require approximately 15-20 
minutes), but additional pile driving must not be initiated until the 
animal has left the

[[Page 24966]]

Level A harassment zone. During this time, PSOs must monitor the animal 
and record behavior;
    (5) If a marine mammal is approaching a Level A harassment zone and 
pile driving has not commenced, pile driving shall be delayed. Pile 
driving may not commence or resume until either the animal has 
voluntarily left and been visually confirmed beyond the shutdown zone; 
15 minutes have passed without subsequent detections of small cetaceans 
and pinnipeds; or 30 minutes have passed without subsequent detections 
of large cetaceans;
    (6) If a species for which authorization has not been granted, or a 
species for which authorization has been granted but the authorized 
takes are met, is observed approaching or within the monitoring zone 
(which equates to the Level B harassment zone), pile driving and 
removal activities must shut down immediately using delay and shut-down 
procedures. Activities must not resume until the animal has been 
confirmed to have left the area or the observation time period, as 
indicated in 217.34(c)(5), has elapsed;
    (7) Hilcorp will use soft start techniques when impact pile 
driving. Soft start requires contractors to provide an initial set of 
strikes at reduced energy, followed by a thirty-second waiting period, 
then two subsequent reduced energy strike sets. A soft start must be 
implemented at the start of each day's impact pile driving and at any 
time following cessation of impact pile driving for a period of thirty 
minutes or longer;
    (8) No impact driving must occur during the Nuiqsut Cross Island 
bowhead whale hunt. Hilcorp must coordinate annually with subsistence 
users on the dates of these hunts; and
    (9) Should an ice seal be observed on or near the LDPI by any 
Hilcorp personnel, during construction or operation, the sighting must 
be reported to Hilcorp's Environmental Specialist. No construction 
activity should occur within 10 m of an ice seal and any vehicles used 
should use precaution and not approach any ice seal within 10 m.
    (d) Vessel restrictions. When operating vessels, Hilcorp must:
    (1) Reduce vessel speed to 5 knots (kn) if a whale is observed with 
500 m (1641 feet (ft)) of the vessel and is on a potential collision 
course with vessel, or if a whale is within 275 m (902 ft) of whales, 
regardless of course relative to the vessel;
    (2) Avoid multiple changes in vessel direction;
    (3) Not approach within 800 m (2,624 ft) of a North Pacific right 
whale or within 5.6 km (3 nautical miles) of Steller sea lion rookeries 
or major haulouts; and
    (4) Avoid North Pacific right whale critical habitat or, if 
critical habitat cannot be avoided, reduce vessel speed during transit.


Sec.  217.35  Requirements for monitoring and reporting.

    (a) All marine mammal and acoustic monitoring must be conducted in 
accordance to Hilcorp's Marine Mammal Mitigation and Monitoring Plan 
(4MP). This plan may be modified throughout the life of the regulations 
upon NMFS review and approval.
    (b) Monitoring must be conducted by NMFS-approved PSOs, who must 
have no other assigned tasks during monitoring periods. At minimum, two 
PSOs must be placed on elevated platforms on the island during the 
open-water season when island construction activities are occurring. 
These observers will monitor for marine mammals and implement shutdown 
or delay procedures when applicable through communication with the 
equipment operator.
    (c) One PSO will be placed on the side where construction 
activities are taking place and the other placed on the opposite side 
of the LDPI; both observers will be on elevated platforms.
    (d) PSOs will rotate duties such that they will observe for no more 
than 4 hours at a time and no more than 12 hours in a 24-hour period.
    (e) An additional island-based PSO will work with an aviation 
specialist to use an unmanned aircraft system (UAS) to detect marine 
mammals in the monitoring zones during pile and pipe driving and slope 
shaping. Should UAS monitoring not be feasible or deemed ineffective, a 
boat-based PSO must monitor for marine mammals during pile and pipe 
driving.
    (f) During the open-water season, marine mammal monitoring must 
take place from 30 minutes prior to initiation of pile and pipe driving 
activity through 30 minutes post-completion of pile driving activity. 
Pile driving may commence when observers have declared the shutdown 
zone clear of marine mammals. In the event of a delay or shutdown of 
activity resulting from marine mammals in the shutdown zone, animals 
must be allowed to remain in the shutdown zone (i.e., must leave of 
their own volition) and their behavior must be monitored and 
documented.
    (g) After island construction is complete but drilling activities 
are occurring, a PSO will be stationed on the LDPI for approximately 4 
weeks during the month of August to monitor for the presence of marine 
mammals around the island in the monitoring zone.
    (1) Marine mammal monitoring during pile driving and removal must 
be conducted by NMFS-approved PSOs in a manner consistent with the 
following:
    (i) At least one observer must have prior experience working as an 
observer;
    (ii) Other observers may substitute education (degree in biological 
science or related field) or training for experience;
    (iii) Where a team of three or more observers are required, one 
observer must be designated as lead observer or monitoring coordinator. 
The lead observer must have prior experience working as an observer; 
and
    (iv) Hilcorp must submit PSO CVs for approval by NMFS prior to the 
onset of pile driving;
    (2) PSOs must have the following additional qualifications:
    (i) Ability to conduct field observations and collect data 
according to assigned protocols;
    (ii) Experience or training in the field identification of marine 
mammals, including the identification of behaviors;
    (iii) Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
    (iv) Writing skills sufficient to prepare a report of observations 
including but not limited to the number and species of marine mammals 
observed; dates and times when in-water construction activities were 
conducted; dates, times, and reason for implementation of mitigation 
(or why mitigation was not implemented when required); and marine 
mammal behavior; and
    (v) Ability to communicate orally, by radio or in person, with 
project personnel to provide real-time information on marine mammals 
observed in the area as necessary.
    (h) Hilcorp must deploy autonomous sound recorders on the seabed to 
conduct underwater passive acoustic monitoring in the open water season 
the first four years of the project such that island construction 
activities, including pile driving, and drilling operations are 
recorded. Acoustic monitoring will be conducted for the purposes of 
sound source verification, to verify distances from noise sources at 
which underwater sound levels reach thresholds for potential marine 
mammal harassment.
    (i) Hilcorp must submit incident and monitoring reports.
    (1) Hilcorp must submit a draft annual marine mammal and acoustic 
summary

[[Page 24967]]

report to NMFS not later than 90 days following the end of each 
calendar year. Hilcorp must provide a final report within 30 days after 
receipt of NMFS' comments on the draft report. The reports must 
contain, at minimum, the following:
    (i) Date and time that monitored activity begins or ends;
    (ii) Description of construction activities occurring during each 
observation period;
    (iii) Weather parameters (e.g., wind speed, percent cloud cover, 
visibility);
    (iv) Water conditions (e.g., sea state, tide state);
    (v) Species, numbers, and, if possible, sex and age class of marine 
mammals;
    (vi) Description of any observable marine mammal behavior patterns, 
including bearing and direction of travel and distance from 
construction activity;
    (vii) Distance from construction activities to marine mammals and 
distance from the marine mammals to the observation point;
    (viii) Histograms of the perpendicular distance at which marine 
mammals were sighted by the PSOs;
    (ix) Description of implementation of mitigation measures (e.g., 
shutdown or delay);
    (x) Locations of all marine mammal observations;
    (xi) An estimate of the effective strip width of the island-based 
PSOs and the UAS imagery; and
    (xii) Sightings and locations of marine mammals associated with 
acoustic detections.
    (2) Annually, Hilcorp must submit a report within 90 days of ice 
road decommissioning. The report must include the following:
    (i) Date, time, location of observation;
    (ii) Ringed seal characteristics (i.e., adult or pup, behavior 
(avoidance, resting, etc.));
    (iii) Activities occurring during observation including equipment 
being used and its purpose, and approximate distance to ringed seal(s);
    (iv) Actions taken to mitigate effects of interaction emphasizing: 
(A) Which BMPs were successful; (B) which BMPs may need to be improved 
to reduce interactions with ringed seals; (C) the effectiveness and 
practicality of implementing BMPs; (D) any issues or concerns regarding 
implementation of BMPs; and (E) potential effects of interactions based 
on observation data;
    (v) Proposed updates (if any) to the NMFS-approved Wildlife 
Management Plan(s) or the ice-road BMPs;
    (vi) Reports should be able to be queried for information;
    (3) Hilcorp must submit a final 5-year comprehensive summary report 
to NMFS not later than 90 days following expiration of these 
regulations and LOA.
    (4) Hilcorp must submit acoustic monitoring reports per the 
Acoustic Monitoring Plan.
    (5) Hilcorp must report on observed injured or dead marine mammals.
    (i) In the unanticipated event that the activity defined in Sec.  
217.30 clearly causes the take of a marine mammal in a prohibited 
manner, Hilcorp must immediately cease such activity and report the 
incident to the Office of Protected Resources (OPR), NMFS, and to the 
Alaska Regional Stranding Coordinator, NMFS. Activities must not resume 
until NMFS is able to review the circumstances of the prohibited take. 
NMFS will work with Hilcorp to determine what measures are necessary to 
minimize the likelihood of further prohibited take and ensure MMPA 
compliance. Hilcorp may not resume their activities until notified by 
NMFS. The report must include the following information:
    (A) Time, date, and location (latitude/longitude) of the incident;
    (B) Description of the incident;
    (C) Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, visibility);
    (D) Description of all marine mammal observations in the 24 hours 
preceding the incident;
    (E) Species identification or description of the animal(s) 
involved;
    (F) Fate of the animal(s); and
    (G) Photographs or video footage of the animal(s). Photographs may 
be taken once the animal has been moved from the waterfront area.
    (H) In the event that Hilcorp discovers an injured or dead marine 
mammal and determines that the cause of the injury or death is unknown 
and the death is relatively recent (e.g., in less than a moderate state 
of decomposition), Hilcorp must immediately report the incident to OPR 
and the Alaska Regional Stranding Coordinator, NMFS. The report must 
include the information identified in paragraph (k)(5) of this section. 
Activities may continue while NMFS reviews the circumstances of the 
incident. NMFS will work with Hilcorp to determine whether additional 
mitigation measures or modifications to the activities are appropriate.
    (ii) In the event Hilcorp discovers an injured or dead marine 
mammal and determines that the injury or death is not associated with 
or related to the activities defined in Sec.  217.30 (e.g., previously 
wounded animal, carcass with moderate to advanced decomposition, 
scavenger damage), Hilcorp must report the incident to OPR and the 
Alaska Regional Stranding Coordinator, NMFS, within 24 hours of the 
discovery. Hilcorp must provide photographs or video footage or other 
documentation of the stranded animal sighting to NMFS. Photographs may 
be taken once the animal has been moved from the waterfront area.


Sec.  217.36  Letters of Authorization.

    (a) To incidentally take marine mammals pursuant to these 
regulations, Hilcorp must apply for and obtain an LOA.
    (b) An LOA, unless suspended or revoked, may be effective for a 
period of time not to exceed the expiration date of these regulations.
    (c) If an LOA expires prior to the expiration date of these 
regulations, Hilcorp may apply for and obtain a renewal of the LOA.
    (d) In the event of projected changes to the activity or to 
mitigation and monitoring measures required by an LOA, Hilcorp must 
apply for and obtain a modification of the LOA as described in Sec.  
217.37.
    (e) The LOA shall set forth:
    (1) Permissible methods of incidental taking;
    (2) Means of effecting the least practicable adverse impact (i.e., 
mitigation) on the species, its habitat, and on the availability of the 
species for subsistence uses; and
    (3) Requirements for monitoring and reporting.
    (f) Issuance of the LOA shall be based on a determination that the 
level of taking will be consistent with the findings made for the total 
taking allowable under these regulations.
    (g) Notice of issuance or denial of an LOA shall be published in 
the Federal Register within thirty days of a determination.


Sec.  217.37  Renewals and modifications of Letters of Authorization.

    (a) An LOA issued under Sec. Sec.  216.106 of this chapter and 
217.36 for the activity identified in Sec.  217.30(a) shall be renewed 
or modified upon request by the applicant, provided that:
    (1) The proposed specified activity and mitigation, monitoring, and 
reporting measures, as well as the anticipated impacts, are the same as 
those described and analyzed for these regulations (excluding changes 
made pursuant to the adaptive management provision in paragraph (c)(1) 
of this section); and
    (2) NMFS determines that the mitigation, monitoring, and reporting 
measures required by the previous LOA under these regulations were 
implemented.
    (b) For LOA modification or renewal requests by the applicant that 
include

[[Page 24968]]

changes to the activity or the mitigation, monitoring, or reporting 
(excluding changes made pursuant to the adaptive management provision 
in paragraph (c)(1) of this section) that do not change the findings 
made for the regulations or result in no more than a minor change in 
the total estimated number of takes (or distribution by species or 
years), NMFS may publish a notice of proposed LOA in the Federal 
Register, including the associated analysis of the change, and solicit 
public comment before issuing the LOA.
    (c) An LOA issued under Sec. Sec.  216.106 of this chapter and 
217.36 for the activity identified in Sec.  217.30(a) may be modified 
by NMFS under the following circumstances:
    (1) Adaptive management. NMFS may modify (including augment) the 
existing mitigation, monitoring, or reporting measures (after 
consulting with Hilcorp regarding the practicability of the 
modifications) if doing so creates a reasonable likelihood of more 
effectively accomplishing the goals of the mitigation and monitoring 
set forth in the preamble for these regulations.
    (i) Possible sources of data that could contribute to the decision 
to modify the mitigation, monitoring, or reporting measures in an LOA:
    (A) Results from Hilcorp's monitoring from the previous year(s).
    (B) Results from other marine mammal and/or sound research or 
studies.
    (C) Any information that reveals marine mammals may have been taken 
in a manner, extent or number not authorized by these regulations or 
subsequent LOAs.
    (ii) If, through adaptive management, the modifications to the 
mitigation, monitoring, or reporting measures are substantial, NMFS 
will publish a notice of proposed LOA in the Federal Register and 
solicit public comment.
    (2) Emergencies. If NMFS determines that an emergency exists that 
poses a significant risk to the well-being of the species or stocks of 
marine mammals specified in LOAs issued pursuant to Sec. Sec.  216.106 
of this chapter and 217.36, an LOA may be modified without prior notice 
or opportunity for public comment. Notice would be published in the 
Federal Register within thirty days of the action.


Sec. Sec.  217.38-217.39  [Reserved]

[FR Doc. 2019-10965 Filed 5-28-19; 8:45 am]
 BILLING CODE 3510-22-P