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

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 217

[Docket No. 191210-0105]

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:

Final rule; notification of issuance.

SUMMARY:

NMFS hereby issues regulations to govern the unintentional taking of marine mammals incidental to construction and operation of the Liberty Drilling and Production Island (LDPI) in the Beaufort Sea, Alaska over the course of five years. These regulations, which allow for the issuance of a Letter of Authorization for the incidental take of marine mammals during the described activities and specified timeframes, prescribe the permissible methods of taking and other means of effecting the least practicable adverse impact on marine mammal species or stocks and their habitat, as well as requirements pertaining to the monitoring and reporting of such taking.

DATES:

This rule is effective December 1, 2021 through November 30, 2026.

FOR FURTHER INFORMATION CONTACT:

Jaclyn Daly, Office of Protected Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

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 final rule establishes a framework under the authority of the Marine Mammal Protection Act (MMPA) (16 U.S.C. 1361

et seq.

) to allow for the issuance of a Letter of Authorization (LOA) for the 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 “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 rule containing five-year regulations, and for any subsequent Letters of Authorization (LOAs). As directed by this legal authority, this rule contains mitigation, monitoring, and reporting requirements.

Summary of Major Provisions Within the Final Rule

The following is a summary of the major provisions of this final 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 all pile and pipe driving at the island site and vessel movement outside the barrier islands 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 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 ensure that requirements pertaining to the mitigation, monitoring, and reporting of such takings are set forth.

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. On May 29, 2019, NMFS issued a notice of proposed rulemaking in the

Federal Register

(84 FR 24926), soliciting public comments for 30 days. The 30-day comment period was subsequently extended to July 31, 2019, in response to a request from the AEWC (84 FR 32697; July 9, 2019). All public comments were considered in developing this final rule. 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 2021. Island construction, which requires impact and vibratory pile driving, is proposed to take one year to complete, beginning in 2022. 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 2023. Drilling and production is proposed to occur from 2023 through 2026.

Hilcorp requests, and NMFS is authorizing, 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 authorizing, mortality and serious injury of two ringed seals incidental to annual ice road construction over a 5-year period. The regulations are effective from December 1, 2021, through November 30, 2026.

Changes From Proposed to Final Rule

There are minor changes from the proposed rule to the final rule. While more detail can be found later in this document, we summarize the changes here.

We modified the amount of authorized takes, by Level B harassment, of bowhead whales in years two through five from one animal to five animals per year. This change was to account for a potentially large group of whales in lieu of a single animal entering the Level B harassment isopleth. While these whales are extremely rare to Foggy Island Bay, we believe this is a more conservative approach and allows the applicant sufficient take coverage.

We also corrected the take table for gray whales to authorize the take, by Level B harassment, of two gray whales per year. The proposed rule preamble text indicated that two gray whales could be taken by Level B harassment per year; however, the table incorrectly indicated that only one gray whale take was authorized per year. Two animals per year more adequately reflects average group size.

We also modified the mitigation measures during the Cross Island bowhead whale hunt to comport with the Bureau of Ocean Energy Management's (BOEM) Record of Decision for permitting the project. This resulted in additional mitigation to ensure the taking of marine mammals authorized in these regulations will effect the least practicable adverse impact on subsistence uses as well as the least practicable adverse impact on the species and their habitat. Specifically, the proposed rule required Hilcorp to cease impact pile driving during the Cross Island hunt. The new mitigation measure mirrors BOEM's measure, which requires that all pile driving (impact and vibratory) must cease by August 1 and not resume until the official end of the hunt or when the quota is met. In addition, Hilcorp may not operate LDPI-related vessels outside the McClure Island Group during this time.

We also modified other mitigation and monitoring measures (

e.g.,

requiring ice road observers be equipped with binoculars and protected species observers (PSOs) be equipped with laser range finders) in consideration of input provided in public comments.

Public comments on the proposed rule indicated some confusion over the mitigation and monitoring distances for both ringed seal structures and ringed seals themselves in the Ice Road and Ice Trail Best Management Practices (BMPs). In light of public comments, Hilcorp modified the BMPs to provide clarity and consistency with mitigation and monitoring distances. Those changes, made to both the BMPs and these final regulations, reflect a standard 150-m set back distance to ringed seal structures (both lairs and breathing holes) and a 50-m setback distance to ringed seals on ice.

Finally, the effective date of this final rule is advanced one year from that in the proposed rule, as described in the

Federal Register

document announcing our re-opening of the public comment period on the proposed rule (84 FR 32697, July 9, 2019), to accommodate Hilcorp's most recent construction schedule. The regulations are effective from December 1, 2021, through November 30, 2026.

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 as much as possible during the winter months; 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 regulations and LOA 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 if future incidental take authorizations are warranted for continuing operations.

Dates and Duration

The regulations are valid for a period of five years from December 1, 2021, through November 30, 2026. Ice road construction and pipeline installation would be limited to winter months. Island construction would be conducted primarily during winter months; however, given that construction schedules are subject to delays for multiple reasons, Hilcorp anticipates, at most, up to two weeks of open-water sheet 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 regulations (December 2021 through November 2022). Pipeline installation would occur in year 2 of the regulations (December 2022 through November 2023), while drilling and production would begin in year 3 and continue through the life of the 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, 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).

BILLING CODE 3510-22-P

ER20DE19.000

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 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 of the project and a summary of equipment and activities involved are included in Table 1a with more details on schedule provided in Table 1b.

Table

1a

—LDPI Project Components, Schedule, and Associated Equipment

Project component

Regulation year

Season

Equipment and activity

Ice road construction, use, and maintenance

1-5

Ice-covered

Grader, ice auger, trucks (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 (helicopter only)

Barge, tugs, crew boats, 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.

Table

1b

—Dominant Noise Source by Month and Days of Each Activity

Season

Month

Year 1

Year 2

Year 3

Year 4

Year 5

Ice-covered Season

Dec, Jan

Ice Road Construction (62 days)

Ice Road Construction (62 days)

Drilling and Production (212 days)

Drilling and Production (212 days)

Drilling and Production (212 days)

Feb, March, April

Island Construction (89 days)

Facility Construction (150 days)

May

Island Construction (14 days).

Vibratory Sheet Pile Driving

(17 days)

June

Vibratory Sheet Pile Driving (30 days)

Open-water Season

July

Vibratory Sheet Pile Driving (15 days).

Foundation Piles Installation (31 days)

Drilling and Production (123 days)

Drilling and Production (123 days)

Production (123 days).

Slope Shaping (16 days)

Aug

Slope Shaping (31 days)

Rig Mobilization & Well Prep (92 days)

Sept, Oct

Rig Mobilization & Well Prep (61 days)

Ice-covered Season

Nov

Rig Mobilization & Well Prep (30 days)

Drilling and Production (30 days)

Drilling and Production (30 days)

Drilling and Production (30 days)

Production (30 days)

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 can be 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 a 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 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).

ER20DE19.001

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 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 the fabric is overlapped and tied together, no slope protection debris would enter the water column should it be damaged. Above the fabric under layer, a robust geo-grid will be placed as an abrasion guard to prevent damage to the fabric by the linked mat armor. The concrete mat system would continue at a 3:1 slope another 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 this 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 that will document 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.

ER20DE19.002

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 the final desired depth for each sheet pile. 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 the 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.

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 the construction of the nearby Northstar Island (located in deeper water), it took 5 to 8.5 hours to drive one conductor pipe (Blackwell

et al.,

2004). For the Liberty LDPI, 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 Environmental Impact Statement (FEIS) 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.

Comments and Responses

Notice of NMFS's proposal to issue regulations to Hilcorp was published in the

Federal Register

on May 29, 2019 (84 FR 24926). That document described, in detail, Hilcorp's proposed activity, the marine mammal species that may be affected by the activity, and the anticipated effects on marine mammals. At the request of the Alaska Eskimo Whaling Commission (AEWC), NMFS reopened the public comment period until July 31, 2019 (84 FR 32697; July 9, 2019). During the public comment period, NMFS received comments from the Marine Mammal Commission (the Commission); Alaska Wilderness League (AWL), on behalf of the Animal Welfare Institute, Center for Biological Diversity, Defenders of Wildlife, Earthjustice, Environmental Investigation Agency, Eyak Preservation Council, Friends of the Earth, and Northern Alaska Environmental Center; AEWC; North Slope Borough (NSB); and seven private citizens. These comments and our responses are described below.

Comment 1:

The Commission recommends that NMFS consult with external scientists and acousticians to determine the appropriate accumulation time that action proponents should use to determine the extent of the Level A harassment zones based on the associated cumulative sound exposure level (SELcum) thresholds for the various types of sound sources, including stationary sound sources.

Response:

The Commission has raised this concern before and NMFS has previously responded that NMFS considers this a priority and has formed a Working Group to focus on the issue of accumulation time. Once the NMFS internal Working Group develops a proposal, it will be shared with Federal partners and other stakeholders. However, in the meantime, as we have described previously, Hilcorp used a sophisticated modeling approach that considered the full duration of activity within a day which allows for a conservative estimate of the distances at which marine mammals could potentially experience injurious sound levels if they were subject to the full duration of exposure.

Comment 2:

The Commission recommends that NMFS include in the preamble of the final rule all of the inputs it used to estimate takes by Level A and B harassment, including the type of activity that will occur during each season and the number of days each season that each activity will occur.

Response:

All of the inputs into the Level A harassment analysis, including ensonified areas, are included in the final rule. NMFS also provided a table in the final rule that lists the activities with the greatest potential for take and the number of days each season that the activities are anticipated to occur in each year of the 5-year regulations (Table 1b).

Comment 3:

The Commission believes that the number of Level A harassment takes for ringed seals have been underestimated and claims there is the potential for at least one ringed seal to be taken by Level A harassment each day that impact pile driving occurs, particularly since it appears that impact pile driving could occur intermittently throughout a given day. The Commission recommends that NMFS increase the number of Level A harassment takes of ringed seals from 5 to at least 15 during Year 1 considering 15 days of open-water pile driving could occur.

Response:

The estimated number of marine mammals that may be potentially exposed to noises exceeding NMFS' established thresholds was calculated based on marine mammal density estimates, the ensonified area, and the duration of each project activity. The Commission's recommendation does not provide reason for why this standard approach is not acceptable. In addition, the Commission has inaccurately characterized the Level A harassment distance output of the model as the distance at which an animal will immediately incur permanent threshold shift (PTS) if it crosses that distance. However, this is not the case as described in the Technical Guidance (NMFS 2018). The Level A threshold distance represents the distance at which an animal could incur PTS if it remains at that distance for the duration considered in the model. An animal crossing this distance for a shorter period of time does not necessarily incur PTS. The Level A isopleth calculations included a conservative 40 minutes of active impact pile driving per day, which does not consider the time it takes to reset for piles, and Footnote 2 in Table 4 indicates the average duration of impact driving per day is closer to 20 minutes, which would result in a much smaller Level A harassment distance and, again, the animal would have to remain at that distance for that period of time. The Commission also states that Hilcorp would not be required to shut down if a seal comes within the Level A harassment isopleth; however, as described in Hilcorp's application, the proposed rule, and this final rule, if a seal 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 Level A harassment zone. The Commission also does not consider seasonal density of ringed seals, which is very low during the summer when impact pile driving during open-water could occur, further reducing the potential for Level A harassment take. For these reasons, NMFS does not agree with the Commission's recommendation and, as in the proposed rule, the final rule authorizes the take, by Level A harassment, of five ringed seals in year 1 incidental to pile driving as this is the calculated Level A harassment take based on seal density, the ensonified area, and the number of impact pile driving days.

Comment 4:

The Commission recommends that NMFS revise the numbers of Level B harassment takes for all species to account for vibratory driving occurring at any of the five sides of the island during the open-water season and, unless Hilcorp has contrary data regarding how many days vibratory driving would occur at each of the five sides of the island, assume that pile driving would occur for three days at each of the five sides. This recommendation is based on the proposed rule's approach that Level B harassment takes during sheet pile driving during the open-water season were based on an ensonified area of 64 km

2

for each of the estimated 15 days of pile driving. That ensonified area is associated with the southwest side of the island, which was the smallest of the ensonified areas associated with each of the five sides of the island.

Response:

Hilcorp stated several times in their application, correspondence with NMFS, and during the peer-review panel that they intend to conduct all sheet pile driving during the ice-covered season, as was done with Northstar. This information is provided in their description of the specified activity. However, as a precautionary measure, two weeks to complete sheet piling driving during open water (early July) have been included for estimating potential marine mammal takes. Hilcorp's construction process validates the reason for using the southwest perimeter acoustic model results (64 km

2

) in the take estimate. Hilcorp proposes to begin vibratory sheet pile driving on the north end of LDPI during ice-covered conditions, progressing around the island perimeter and finishing with sheet pile driving on the southwest side of the island. Therefore, although ideally all pile driving would be done during the ice-covered season, the only part of the island which could be unfinished by the open-water period is the southwest side of the island. The Commission's recommendation to assume three days of pile driving at each of the five sides is inconsistent with Hilcorp's construction plan. For these reasons, NMFS used the SW ensonified area of 64 km

2

to estimate marine mammal takes while also accounting for group size in its take authorization, as presented in the proposed rule. In addition, we note that NMFS adjusted cetacean take numbers from a simple density estimate, which uses an ensonified area, to one that accounts for group size and previous monitoring data, raising all take numbers born from estimates that solely relied on ensonified area. For example, the estimated density of gray whales in Foggy Island Bay is zero, therefore even if different ensonified areas were used, the outcome of takes based solely on the ensonified area would always be zero; however, by also including group size and previous monitoring data, the Level B harassment take estimate for gray whales is two per year.

Comment 5:

The Commission recommends that NMFS increase the Level B harassment takes of gray whales from one to two annually in Years 1 through 5 and that NMFS increase the Level B harassment takes of bowhead whales to account for the typical group size of two to five whales annually in Years 2 through 5.

Response:

Although gray whales and bowhead whales are extremely rare in Foggy Island Bay, NMFS agrees to conservatively account for group sizes of these species in the open Beaufort Sea. This final rule authorizes the take, by Level B harassment, of two gray whales, annually for the life of the regulations, and five bowhead whales, annually in years 2-5 of the final rule, incidental to the proposed project. As in the proposed rule, NMFS estimates that six bowhead whales may be taken by Level B harassment in year 1 of the regulations.

Comment 6:

If there is a possibility that pile driving could occur after the Nuiqsut Cross Island hunt, the Commission recommends that NMFS re-estimate the number of Level B harassment takes, as well as Level A harassment takes for bowhead whales since they occur in greater numbers, and thus higher densities, in the fall (September through October).

Response:

Other than to account for large group size (see above), NMFS did not adjust bowhead whale take numbers. It is very unlikely Hilcorp would conduct pile driving after the Cross Island hunt as this is not in their project plan. Hilcorp intends to conduct all sheet pile driving during the ice-covered months as was done with Northstar. Some sheet pile driving during the open-water season was included in the rulemaking analysis to conservatively account for any delays resulting in the need for sheet pile driving during that time.

Comment 7:

The Commission recommends that NMFS specify in the final rule that the Level A harassment zones equate to the shut-down zones and the relevant circumstances when they apply. The AWL made a similar comment and we address both here.

Response:

As described in the proposed rule (84 FR 24955) and this final rule, 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. This measure is designed to provide the most protection practicable for large whales included in subsistence uses. If a mid-frequency cetacean (beluga) or pinniped (seal) enters the Level A harassment zone during pile driving, Hilcorp could 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. This measure is also included in section 217.34 of the proposed and final regulations. As such, the Commission's recommendation to specify the Level A harassment zones equate to the shut-down zones is not necessary. The Commission and AWL's confusion appears to be generated by one statement in parentheses in the proposed rule preamble that did not clearly identify that the shut-down zone is equal to Level A harassment zone only for low frequency cetaceans. NMFS corrected this statement in the final rule to clarify the Level A zone is equal to the shut-down zone only for low frequency cetaceans.

Comment 8.

The Commission recommends that NMFS make the Wildlife Action Plan available to the public and provide an additional opportunity for review and comment on both the BMPs and the Wildlife Action Plan prior to issuing the final rule.

Response:

NMFS posted both the BMPs and the relevant sections of the Wildlife Action Plan during the initial public comment period. These documents were also available during the second public comment period.

Comment 9:

The Commission recommends that NMFS include the following requirements in the final rule: (1) That Hilcorp conduct PAM [passive acoustic monitoring] using a hand-held hydrophone deployed through the ice during the ice-covered season and (2) Hilcorp include in its annual reports and final report an extrapolated total take estimate for each species based on the number of marine mammals observed and the extent of the harassment zones during the applicable construction activities.

Response:

The proposed and final rule includes the requirement that Hilcorp conduct PAM using a hand-held hydrophone. This requirement is also in both the Marine Mammal Mitigation and Monitoring Plan (4MP) and the Acoustic Monitoring Plan which the Commission reviewed concurrently with the proposed rule. In the final rule, NMFS has added a requirement that Hilcorp provide in its annual and final

report an extrapolated total take estimate for each species.

Comment 10:

The Commission recommends that NMFS ensure the minimum distance specified in the final rule, 4MP, and BMPs for avoidance of ringed seals and lairs is at least 150 m, not 150 ft (we note AWL provided a similar comment) and that NMFS clarify in the preamble to the final rule its rationale for not incorporating the peer-review panel's recommendations to (1) increase the avoidance distance for ringed seals and lairs to 300 m and (2) investigate the availability of laser range finders that would improve the resolution and range of detections of marine mammals beyond 600 m.

Response:

The final rule makes corrections and clarifies the minimum distances of approach for ringed seals and ringed seal structures. The minimum distance to avoid ringed seals remains as stated in the proposed rule and BMPs as 50 m. The minimum distance to avoid ringed seal structures (

e.g.,

lairs, breathing holes) in this final rule is 150 m. The BMP entries, which appear to be the source of confusion for the Commission and AWL, have been modified and are available at

https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.

With respect to the peer-review panel's recommendation, they provided no justification for why the proposed avoidance distances were not appropriate nor did they provide justification for the 300-m recommendation. A 300-m avoidance distance of both seals and lairs is three times greater than the NMFS marine mammal viewing guidelines recommendation and is not practicable for the applicant to carry out ice-road work. For these reasons, NMFS did not accept the peer-review panel's 300-m avoidance recommendation.

We note that the peer-review panel's report made one mention of range finders and recommended user range finders that would improve resolution and range detections of marine mammals beyond 600 m. The 4MP indicates distances to nearby marine mammals will be estimated with binoculars containing a reticle to measure the vertical angle of the line of sight to the animal relative to the horizon. However, for a more immediate distance estimator tool, NMFS has included the requirement for PSOs to be equipped with rangefinders.

Comment 10:

AWL asserts the proposed rule employs an unlawful small numbers analysis that arbitrarily fails to consider the full suite of impacts from the operation of the Liberty project on marine mammals in that NMFS ignores takes that will occur from operation of the Liberty project.

Response:

Hilcorp requested authorization for the take of six species of marine mammals incidental to construction and operation of the proposed LDPI during the five-year period from December 1, 2021, through November 30, 2026. NMFS does not ignore takes that will occur from operation of the Liberty project during that period. The acoustic models indicate there is potential for NMFS Level B harassment thresholds to be reached during drilling (

i.e.,

operation) approximately 230 m and 55 m from the island during ice and open-water conditions, respectively. Animal density, by species, was considered with respect to these ensonified areas and accounted for in the take estimates. Therefore, NMFS has analyzed and authorized takes for operation (

i.e.,

drilling) of the Liberty project. During the onset of drilling and production, Liberty will perform acoustic measurements to determine if the model accurately predicted these harassment isopleths, and future requests for take authorizations after the regulations have expired will be contingent upon those measurements.

Comment 11:

AWL expressed concern that NMFS used the median range of radial distances to NMFS Level B harassment thresholds to determine the ensonified area in which takes would occur. They assert that use of the median range could lead to roughly 50 percent of an exposed cohort experiencing impacts that are not accounted for in NMFS's analysis. They assert NMFS' approach contravenes the precautionary nature of the MMPA and the statutory definition of harassment, which includes not only those actions that will injure or disturb marine mammals, but those that have the potential to do so.

Response:

It is NMFS standard practice to apply median source levels when determining distances to NMFS harassment thresholds. By using the median, we eliminate the few loud outliers in the data, better representing the overall acoustic footprint of the project. NMFS notes that using the median harassment isopleth also does not translate into underestimating an exposed cohort by 50 percent as the AWL asserts. This is because the median harassment isopleth distance is not half of the maximum isopleth (which is derived by applying the absolute maximum source level). For example, the median Level B harassment isopleth for impact driving sheet piles is 2,050 m while the maximum is 2,250 m. Similarly, the median Level B harassment isopleth for impact driving pipe piles is 315 m while the maximum is 400 m. Because take is based on the density of animals in a given area, the area (which is derived from isopleth distances) would have to be 50 percent less to have a 50 percent reduction in take. More importantly, all predicted cetacean takes were adjusted upwards to account for group size so the actual take authorized is greater than any predicted take based on density and harassment isopleth distances. For these reasons, we believe we have accurately accounted for the potential for takes of all species.

Regarding Level B harassment, based on the language and structure of the definition of Level B harassment, we interpret the concept of “potential to disturb” as embedded in the assessment of the behavioral response that results from an act of pursuit, torment, or annoyance (collectively referred to hereafter as an “annoyance”). The definition refers to a “potential to disturb” by causing disruption of behavioral patterns. Thus, an analysis that indicates a disruption in behavioral patterns establishes the “potential to disturb.” A separate analysis of “potential to disturb” is not needed.

Comment 12:

AWL believes NMFS ignores takes that will occur from ship strikes and noise pollution from vessel and air traffic associated with the Liberty project. These activities may cause takes of all the species analyzed in the agency's proposed rule—bowhead whales, gray whales, beluga whales, spotted seals, ringed seals, and bearded seals—as well as a host of other species (North Pacific right whales, humpback whales, minke whales, fin whales, killer whales, sperm whales, harbor porpoise, Dall's porpoise, beaked whales, Steller sea lions, harbor seals, and ribbon seals) not included in the analysis.

Response:

NMFS does not ignore impacts from ship strikes and noise from vessel and air traffic associated with the Liberty project. As described in the analysis, the probability of a ship strike from the specified activities is very low and, further, Hilcorp proposed, and NMFS included, a number of measures to further reduce the likelihood of vessel interactions. Accordingly, takes from ship strikes are neither anticipated nor authorized. Regarding ship traffic noise, the impacts of vessel traffic from these activities are assessed and considered in NMFS' Biological Opinion, Hilcorp's application, and the proposed rule (

e.g.,

84 FR 24945, May 29, 2019), and while marine mammals may respond to vessel traffic, responses rising to the level of a

take are considered unlikely to occur and are not authorized here. As for aircraft, the critical angle necessary for noise to enter the water column from airborne sources is very small. While aircraft flying low directly overhead may be audible to a cetacean (whose ears are adapted to underwater hearing), it is highly unlikely that noise would cause changes to patterns of behavior that would rise to a level of a take. For all species, including pinnipeds, behavioral harassment would be minimized through mitigation measures that establish minimum flight altitudes, as described in the Biological Opinion and which has been added as a mitigation measure to this final rule. Hence, NMFS disagrees these activities have the potential to take the species AWL believes NMFS did not include in the analysis.

Comment 13:

AWL believes NMFS improperly lumps together the take of marine mammals that it acknowledges will occur. For example, NMFS ignores the impacts of masking from pile driving that might rise to Level B harassment because it will occur concurrently with harassment already considered in estimating takes from vibratory and impact pile driving.

Response:

NMFS disagrees with AWL's characterization. A detailed discussion on masking is presented on page 24944 of the proposed rule (84 FR 24926; May 29, 2019) and noted throughout the

Auditory Effects

section of that document. NMFS qualitatively considers masking in its analysis. NMFS does not quantify and authorize separate Level B harassment takes based on the stressor (

e.g.,

masking vs. stress, etc.), rather, we evaluate the number of takes anticipated to occur and then assess the impacts of the authorized take on the individual (and subsequently the population), qualitatively considering the nature of the takes that are anticipated to occur,

e.g.,

whether they are more or less severe, or what kind of stressor or stressors they are resulting from. Accordingly, while all stressors are appropriately considered in the analysis (quantitatively or qualitatively), a total amount of Level B harassment takes are authorized.

Comment 14:

AWL asserts that repeated exposures should be considered as separate takes, because they will repeatedly affect auditory and behavioral responses. AWL is concerned NMFS appears to count any exposure that occurs over the course of a given day as one take.

Response:

While NMFS' analysis fully considers the nature of any takes that will occur (

e.g.,

the severity, whether they are comprised of multiple exposures within a day, the duration of the exposure), for the purposes of consistency in tracking across projects and practicality for applicant implementation, and in consideration of the fact that many marine mammal behaviors and responses are linked to a diel cycle, NMFS appropriately uses a daily metric to count takes for the purposes of authorization. Specifically we do not consider one individual animal as taken more than one time in a day and, the corollary of that—we consider takes that occur in a subsequent 24-hour period a separate instance of take, even if they may be accruing to the same individual. These basic rules allow for consistent and reliable estimation of take and, further, it is rarely the case that there is adequate information to predict impacts with any precision at a more granular level. Accordingly, we count multiple exposures in one day to an individual as one take, but our analysis considers the severity and nature of each take in our negligible impact analysis.

Comment 15:

AWL asserts that NMFS's analysis also improperly ignores the species-particular behaviors and life-stages of animals at the anticipated times and places that takes would occur and that responses of marine mammals to noise generated by the project may be markedly different depending on what the animal is doing, time of year (

i.e.,

season), or life-stage of the animal at the time of exposure.

Response:

NMFS analyzed both species-specific behaviors and life-stages in the proposed rule. For example, cetaceans are not present in Foggy Island Bay during the ice-covered periods; therefore, we determined there was no potential for harassment to cetaceans during this time period. NMFS also investigated and described the potential effects of ice road construction during ringed seal lairing time periods and specifically discussed that 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. During the open-water season, NMFS identified in the proposed rule that cetaceans rarely use Foggy Island Bay and has clarified in the final rule that Foggy Island Bay does not serve as critical reproductive or foraging grounds for any cetacean species.

Comment 16:

AWL believes NMFS's analysis of small numbers improperly conflates this criterion with the separate negligible impact requirement of the statute. By defining small numbers to be relative to the overall population, the criterion ends up being similar to the negligible impact finding.

Response:

We disagree with AWL's characterization of our analysis—NMFS very clearly distinguishes our separate analyses for the small numbers and negligible impact standards. As described in the proposed rule (84 FR 24959, May 29, 2019), wherein the small numbers assessment is based solely on the number of takes in relation to the abundance of the stock (a purely numerical comparison), the negligible impact analysis considers other factors, such as the nature of the anticipated takes, the context of the exposures, the life history and vulnerability of the individuals of different species, effects on habitat, the likely effectiveness of mitigation, and the status of the affected stocks (among other things) to determine if the takes will affect the fitness of any individuals and, if so, whether the scale of any anticipated impacts to reproduction or survivorship will adversely affect the species or stock. For a fuller description of how NMFS conducts its small numbers analysis, please see our final notice of issuance for five IHAs for seismic surveys in the Atlantic (83 FR 63375, December 7, 2018).

Comment 17:

AWL indicates that both NMFS's negligible impact determination and its small numbers analysis ignore the impacts of oil spills. Oil spills are an inevitable part of the Liberty project and should be considered. NMFS ignores the impacts of oil spills in its negligible impact and small numbers analysis by claiming that Hilcorp has not requested authorization of takes from oil spills and oil spills are not part of the “specified activity” for which NMFS is authorizing takes. However, NMFS defines the “specified activity” as the “construct[ion] and operat[ion] of the LPDI, a self-contained offshore drilling and production facility located on an artificial gravel island.” And as the Final EIS makes clear, small oil spills are an inevitable part of the development and production and therefore should be considered part of the “specified activity” for NMFS's authorization.

Response:

The Bureau of Safety and Environmental Enforcement (BSEE) has primary regulatory authority related to safety and prevention of pollution, including accidental oil spills, related to offshore oil and gas operations. Pollution-prevention regulatory requirements for oil, gas, and sulphur operations in the outer continental shelf are in 30 CFR part 250, subpart C, Pollution Prevention and Control. These regulations require operators that engage in activities such as exploration,

development, production, and transportation of oil and gas to take measures to prevent unauthorized discharge of pollutants into offshore waters (30 CFR 250.300). Operators shall not create conditions that will pose unreasonable risks to public health, life, property, aquatic life, wildlife, recreation, navigation, commercial fishing, or other uses of the ocean. If pollution occurs that damages or threatens to damage life (including fish and other aquatic life), property, any mineral deposits in leased and unleased areas, or the marine, coastal, or human environment, immediate corrective action must be taken and the control and removal of the pollution must be to the satisfaction of BSEE . These regulations further mandate that the operator conduct inspections of drilling and production facilities daily, or at other approved or prescribed intervals, to determine if pollution is occurring (30 CFR 250.301). If problems are detected, necessary maintenance or repairs must be made immediately.

BSEE and BOEM considered the potential risk of oil spills from the LDPI project in the 2018 EIS. Based on BOEM and BSEE's oil spill analysis in the EIS, the only sized spills that are reasonably likely to occur in association with the LDPI operation are small spills (<1,000 barrels (bbls)). Any crude oil spill would not occur prior to drilling and operations, which are likely to begin in year 3 of the effective period of the final rule. BOEM estimates about 70 small spills, most of which would be less than 10 bbls, would occur over the life of the Liberty Project, which is 25 years. Because the first 2 years of the project would not involve drilling, the time during which spills could occur is limited to 23 years. Extrapolating this estimate to the effective period of the rule and during a time at which spills could occur (year 3-5), about 9 spills (70 spills/23 years * 3 years) would be estimated to occur in the three years the rule is valid.

BOEM also explains in the EIS that spills are more likely to occur when BOEM is conducting reservoir drilling, which is defined as initial development drilling (as opposed to workovers, recompletions, and other such well operations subsequently conducted on existing wells) beyond the shoe (base) of the last casing string above the Kekiktuk Formation (

i.e.

drilling that exposes the Kekiktuk Formation to an open, uncased wellbore). Hilcorp is required by BOEM to limit reservoir drilling to the ice-covered season. During the ice-covered season, any spill would be contained by the ice and hence have limited impact on marine mammals. Limiting reservoir drilling to solid ice conditions (defined as 18 inches of ice in all areas 500 feet of the LDPI) limits the risk of an oil spill and hence limits potential impacts on pinnipeds (note cetaceans are not present and therefore unaffected by any spills during the ice-covered season).

During the open-water season, when both cetaceans and pinnipeds could be subjected to an oil spill (albeit in low abundance), 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).

In summary, as described in the EIS, BOEM and BSEE evaluated the potential for impacts from oil spills and concluded that any potential oil spills are likely to be small, and there are measures set in place to minimize impacts of any potential spill on environmental resources, including marine mammals. For purposes of this rulemaking, NMFS discussed the potential risk of oil spills in its proposed rule (84 FR 24946; May 29, 2019), but as noted in the proposed rule, the MMPA authorizes NMFS to issue take from otherwise legal activities, of which oil spills are not, and therefore, NMFS cannot authorize, and is not authorizing, takes of marine mammals incidental to oil spills in the final rule.

Comment 18:

AWL believes NMFS ignores the additive effects from other oil and gas activities in the Arctic and climate change. AWL asserts NMFS fails to consider whether the impacts of the Liberty project will be negligible in light of ongoing and future oil and gas development in the Beaufort Sea and NPR-A, including the Endicott and Northstar projects and Colville Delta 5 (CD-5), Greater Mooses Tooth (GMT) 1 and 2, and Willow project in the NPR-A, among others. AWL states the Liberty project will emit greenhouse gases and exacerbate the climate change that is threatening the continued existence of these species through habitat destruction. AWL claims NMFS's negligible impact determination fails to consider such impacts.

Response:

The MMPA requires NMFS to allow, upon request, the incidental take of marine mammals related to the specified activity, which we have identified as the first five years of LDPI construction and operation. The additive effects from other oil and gas activities in the Arctic and climate change are not part of that specified activity, although the potential for them is discussed in the proposed rule and their ongoing influence is considered through their incorporation into the baseline for our analysis (

e.g.,

through the regulatory status of the species, marine mammal densities, and population trends). Further, these factors are considered in NMFS' Biological Opinion (section 5.0) and environmental analysis required under the National Environmental Policy Act (NEPA). In the Biological Opinion, all relevant future climate-related environmental conditions, such as those caused by the projects AWL acknowledges, in the action area are described in the environmental baseline. BOEM's EIS, on which NOAA was a cooperating agency and which NMFS adopted for issuance of the final rule, identifies the potential impacts of the additive effects from other oil and gas activities in the Arctic and climate change on the human environment, including marine mammals. The effects of ongoing and future oil and gas projects in the Arctic, as well as climate change, are all included in BOEM's cumulative impact analysis in the EIS.

Comment 19:

AWL believes the proposed activities will adversely affect Nuiqsut's subsistence activities, including seal and bowhead whale hunting, and these impacts may not be mitigable. AWL asserts NMFS's proposed rule is inadequate because it fails to ensure that the proposed activity will not have an unmitigable adverse impact on Nuiqsut's subsistence harvest of bowhead whales. AWL argues construction and operation may cause: “(1) deflection of whale movements farther offshore, (2) interference from support vessels, (3) avoidance of the Proposed Action Area by Nuiqsut whalers due to the presence of the proposed LDPI and production facilities and potentially contaminated resources, (4) whaling conflicts with summer construction activities such as sheet pile driving (

i.e.,

LDPI slope protection), and (5) oil spills.” AWL also asserts that even if there are whales available near the proposed LDPI, Nuiqsut whalers will likely avoid the area and if whalers avoid the proposed LDPI site in such years their “opportunities to strike whales could be severely reduced for one or more seasons . . . resulting in major impacts to subsistence whaling for Nuiqsut.” AWL also argues that if there were to be a large oil spill from the proposed LDPI, communities across the North Slope would suffer. AWL asserts NMFS' explanation of its subsistence finding cites consultation and mitigation without explaining how

these measures will address the specific adverse impacts of the proposed activity on subsistence activities. AWL believes NMFS's proposed rule is therefore inadequate because NMFS has not demonstrated that the proposed activity will not have an unmitigable adverse impact on subsistence activities.

Response:

AWL makes a number of assumptions that are unsupported and contradictory to NMFS' analysis of the potential impact on subsistence use of marine mammals. Importantly, the North Slope Borough (NSB) raised no significant concerns with the project and both the NSB's and AEWC's comment letters on the project commended Hilcorp for its outreach and commitment to the CAA during the rulemaking process. The proposed project would not deflect whale movement father offshore because the acoustic footprint of the project within which we would expect any disruption of behavioral patterns (

e.g.,

avoidance) is almost entirely confined to within Foggy Island Bay, where bowhead and gray whales do not migrate. In addition, BOEM has included a condition in Hilcorp's permit to minimize interference with subsistence whaling near Cross Island, wherein all pipe- and pile-driving activities and support vessel traffic outside the barrier islands will cease by August 1 and not resume until the official end of the hunt or until the quota has been met, whichever occurs first. This mitigation measure is carried over to this final rule. AWL's assumption that whalers would avoid the area on their own is unfounded and unsupported. NSB and AEWC did not raise this concern and, in contrast to AWL's assumption, requested Hilcorp to allow whalers to use the LDPI for safe harbor during the whaling season. Access to the LDPI by subsistence users was a mitigation measure included in the proposed rule and is included in the final rule to ensure the specified activities do not have an unmitigable adverse impact on subsistence users. In the unlikely event of a large oil spill, impacts could reach both marine mammal and subsistence communities, as with any large oil spill in the Arctic; however, as described in the response to Comment 17 above, large oil spills are neither anticipated during the course of this 5-year rule nor part of Hilcorp's specified activity, and NMFS is not authorizing takes of marine mammals incidental to oil spills. Further, BOEM and BSEE are responsible for permitting the construction and operation of the LDPI and for Hilcorp's oil spill response plan, respectively, not NMFS.

Comment 20:

AWL believes NMFS has failed to implement measures that would effect the least practicable impact on marine mammals, by requiring mitigation measures that are unclear or ineffective, and by failing to adopt additional mitigation measures. AWL states that NMFS must clarify in the final rule that the shutdown zone is coextensive with the Level A harassment zone.

Response:

The Level A harassment threshold distances and ensonified areas are identified in the proposed and final rule. As described in our response to Comment 7 above, which responds to the Commission's comment on this matter, the Level A harassment zone equates to the shutdown zone for gray whales and bowhead whales, and pile-driving cannot commence or continue if a gray whale or bowhead whale is seen within or approaching that zone; if a mid-frequency cetacean (beluga) or pinniped (seal) enters the Level A harassment zone during pile driving, Hilcorp could complete setting the pile 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 is also required to implement a number of mitigation measures that would minimize impacts to marine mammals through both the BOEM permitting process and the final rule as well as throughout their own construction methodology proposals. These include scheduling island construction during the ice-covered season, minimizing impact pile driving, avoiding pile driving during the bowhead whale migration period, reservoir drilling during solid ice conditions, using pile driving ramp-ups, and implementing the aforementioned shut down zones. Hilcorp, in coordination with NMFS and in consideration of the public comments on the proposed rule, has also clarified measures in the ice-road BMPs which must be followed per the final rule. AWL discussed concerns with monitoring but did not propose any specific additional mitigation measures. After evaluating all of the applicable information, NMFS has concluded that the required mitigation measures will effect the least practicable adverse impact on the affected marine mammal species and stocks and their habitat.

Comment 21:

AWL believes NMFS relies on visual monitoring (or lookouts) and other mitigation measures for marine mammals proposed by Hilcorp that are known to be ineffective and inadequate to protect the species at issue. AWL states that in

Conservation Council for Hawaii

v.

National Marine Fisheries Service,

the court determined that NMFS may not choose the lesser mitigation option of lookouts to protect marine mammals (in that case from military sonar), especially knowing that many potential disruptions to marine mammal behavior will be difficult to detect or avoid through lookouts. AWL asserts that, here, NMFS should require Hilcorp to deploy long-term acoustic monitors consistent with the recommendations of the peer-review panel in order to obtain data both on the presence of marine mammals and sound levels generated during pile driving activities. AWL acknowledges NMFS is requiring Hilcorp to collect measurements using hand-held hydrophones lowered in a hole drilled through the ice during pile driving activities; however, AWL feels that, while this option would at least collect some noise monitoring data during the ice-covered season, the peer-review panel noted that it is only feasible in shallower water and would cover a much shorter time frame than acoustic recorders deployed before the start of winter.

Response:

Hilcorp is required to abide by marine mammal mitigation measures NMFS consistently requires in pile driving incidental take authorizations, as they are considered effective at minimizing the impact to marine mammals. While Hilcorp is relying on visual monitoring to detect marine mammals, they are implementing an unmanned aircraft system (UAS) monitoring program that will allow detection farther than island-based observers can monitor. Hilcorp is also conducting acoustic monitoring in accordance with the peer-review panel's recommendations, which will aid in long-term detection analysis. The peer-review panel specifically recommended Hilcorp deploy acoustic recorders during ice-covered periods to obtain data on both the presence of marine mammals and the sound levels generated during pile driving activities. Deployment of autonomous, long-term recorders during winter is not practicable as recorders, and the data housed within them, would likely be lost to sea ice. AWL did not offer alternative methods of recording during winter; therefore, absent any new information, the peer-review panel's recommendation has been adopted and satisfied.

Comment 22:

AWL also notes that the peer-review panel 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. AWL believes it is not clear that Hilcorp's proposal to position recorders at unspecified ranges from the project activities will capture the same level of sound exposure on marine mammals from multiple known sources. AWL argues the final rule must incorporate the peer review panel's monitoring recommendations or otherwise ensure that this exposure is measured.

Response:

Hilcorp's Acoustic Monitoring Plan, dated December 24, 2018, and their 4MP, dated February 12, 2019, and made available during the public comment period, explain that the 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. This approach will provide for the most effective and relevant monitoring each year, and makes a set location unnecessary. The recorders will be onsite during each season and placed to provide data on ambient noise conditions and characterize or verify the long-range propagation of sounds emanating from the LDPI during construction activities at an offshore location. As such, AWL's concern, as well as the peer-review panel's recommendation, are satisfied because the recorders will provide long-term data sets in both the near and far fields.

Comment 23:

AWL notes that the proposed rule requires implementation of BMPs to avoid and minimize ice seal and habitat disturbance during ice road construction, maintenance, and use. AWL claims, however, that the ice road BMPs fail to reflect the best available science and information and thus may not minimize the impacts of these activities on seals.

Response:

The ice road BMPs, developed in consultation with Hilcorp and NMFS' leading ice seal biologist, are specifically designed to minimize impacts to ringed seals. NMFS Office of Protected Resources (OPR) and Alaska Region (AKR) closely coordinated with the leading ice seal experts in our Alaska Fisheries Science Center (AFSC) to better understand the new, best available science regarding how ice seals use ice roads (

e.g.,

how ice road construction can lead to fissures conducive to constructing lairs on the outer edges, general distances from the shoulder where lairs have been found) and detection methods. During development of the BMPs, we investigated detection methods such as the previous requirement to use specially trained dogs and infrared (IR) imagery. AFSC found that IR failed to detect seals in lairs. AFSC also previously investigated the success of using ground penetrating radar over known lairs in order to see whether there was a reliable thermal signal. Ground penetrating radar was not found to be a useful tool in this regard either. The use of trained dogs was also questionable as there was concern over the cost/benefit ratio of effectiveness versus the trace of dog scent potentially attracting polar bears to actively used ice seal structures, but more relevant is the fact that there are currently no trained dogs available. NMFS considered this and other new information obtained during ice road investigations from Northstar to develop a suite of practicable mitigation measures to implement during ice road construction for the Liberty project. Those BMPs reflect the best available science and minimize the impact of the work on ringed seals. Harassment that cannot be avoided through this comprehensive suite of mitigation measures may be authorized in LOAs pursuant to this final rule.

Comment 24:

AWL states that the BMPs assume that seals will avoid the area on their own because of the construction activity, and NMFS should support this assumption with reference to monitoring and reporting information related to the extensive previous ice road construction and use in seal habitat on the North Slope.

Response:

Although AWL did not provide the language in the ice road BMPs to which they are referring, we assume it is the statement, “Prior to establishing lairs, ringed seals are mobile and are expected to generally avoid the ice roads/trails and construction activities.” In our proposed rule (84 FR 24939; May 29, 2019), we discuss how ice seals utilize and may be attracted to ice roads as the construction of such roads tends to create cracks in the ice along the edges. Cracks and thinned ice, occurring either naturally or adjacent to ice roads, are easily exploitable habitat for ringed seals. We supplement that discussion with data from Williams et al. (2006), which compiles monitoring efforts during construction and operation of the Northstar drilling island and the two recent ice seal encounters on ice roads recently reported (voluntarily) by Hilcorp and another industry company. While NMFS has determined that the mitigation and monitoring measures contained in the BMP document support our least practicable adverse impact determination and has included them in these final regulations, the BMP document itself was drafted by Hilcorp, and NMFS' does not necessarily support every statement contained therein.

Comment 25:

AWL notes that if a seal is observed within 150 feet of an ice road or trail, BMP 6 requires the observer to alert Hilcorp's Environmental Specialist, who will then monitor the seal until it is no longer within 150 feet of the road. The AWL believes disruptive activities may simply continue while the seal is within the monitoring buffer, and that the final rule should ensure a sufficient buffer area to avoid disturbance to seals during the pre-March 1 construction season.

Response:

The 150 ft distance referenced by AWL refers to a monitoring area. As described in response to comment #10, corrections and clarifications were made to the original BMPs and proposed rule to clearly state that ice road construction and maintenance activities will avoid a seal structure by 150 m and a seal by 50 m on ice roads regardless of time of year. Therefore, AWL's assumption that activities could simply continue without action prior to March 1 is erroneous. The final rule and final ice road BMPs clarify this requirement

Comment 26:

AWL is concerned that after March 1, the BMPs call for daytime observation of seals and lairs every other day when activity occurs on ice roads or trails and, unlike other observers noted in Hilcorp's Marine Mammal Monitoring and Mitigation plan (4M plan), these observers need not be certified Protected Species Observers (PSOs). AWL believe it is unclear why PSO certification is not required and why the observations only occur every other operation day instead of all days of operation. AWL asserts the final rule and BMPs should require observers to be PSO certified and present on all days of operation, or explain why this would not constitute a best practice.

Response:

Prior to the initiation of sea ice road- and ice trail-related activities, project personnel associated with ice road construction, maintenance, use or decommissioning (

i.e.,

ice road construction workers, surveyors, security personnel, and the environmental team) will receive annual training on mitigation and monitoring measures. In addition to mitigation and monitoring measures, annual training includes: Ringed Seal Identification and Brief Life History; Physical Environment (habitat characteristics and how to potentially identify habitat); Ringed Seal Use in the Ice Road Region (timing, location, habitat use, birthing lairs, breathing holes, basking, etc.); Potential Effects of Disturbance; Importance of Lairs, Breathing Holes and Basking to Ringed Seals; and a Summary of Regulatory Requirements (

i.e.,

MMPA and the Endangered Species Act (ESA)).

Monitoring for ringed seals along the ice road is a considerably simpler task than observing for several species of seal in open water and this training will be sufficient to ensure that any seals within the monitoring zone are recorded. In 2018, Hilcorp reported zero seal observations along the Northstar ice roads. To ensure safe travel, it is important to limit the number of vehicles traveling ice roads. Therefore, for safety reasons and due to the low likelihood of observing seals within the monitoring zone, conducting monitoring every other day will be sufficient to record seals that may occur. In addition, as described in response to the next comment, the dedicated observer is not the single source of reporting. Any seals observed by drivers or workers, both day and night, are also required to report the sighting to Hilcorp's environmental coordinator.

Comment 27:

AWL asserts that seal lairs are difficult to detect, and NMFS should require more vigorous efforts to detect them, for example, that the BMPs should require operators to employ trained dogs or thermal imaging techniques along the ice road routes to better support a conclusion that there are no lairs present. AWL states the Open Water Review Panel specifically recommended that NMFS investigate the viability of these and other potential detection methods. AWL asserts employing observers working only in daylight hours, only after March 1, only every other day of operation, and only equipped with their eyesight does not appear to constitute a best practice.

Response:

See response to Comment 23 regarding the use of trained dogs and thermal imaging as detection methods. As for the use of observers every other day during daylight hours, NMFS believes this is an appropriate amount of coverage because the dedicated observer is not the single source of reporting. Any seals observed by drivers or workers, both day and night, are also required to report the sighting to Hilcorp's environmental coordinator. In addition, we provide subsequent justification of adequate monitoring in response to comment #26 above. Observers would be equipped with binoculars so AWL is incorrect in their assertion that only the naked eye would be used.

Comment 28:

AWL believes BOEM's FEIS is inadequate in numerous respects, does not fully cover the scope of NMFS's proposed rule, and does not consider alternatives to the proposed rule, and therefore, NMFS cannot satisfy its obligations under NEPA by adopting BOEM's FEIS. They assert that the EIS fails to (1) provide meaningful disclosure and analysis of Liberty's contribution to greenhouse gas pollution and climate change; (2) accurately and thoroughly assess the likelihood and potential impacts of a significant oil spill; (3) take a hard look at Liberty's impacts on marine mammals and other species; (4) adequately consider the project's effects on subsistence and its disproportionate effect on environmental justice communities; (5) consider the cumulative effects of the project in combination with all past, present, and reasonably foreseeable actions; and (6) disclose and consider Hilcorp's track record of spills, accidents, and regulatory violations.

Response:

Section 2.2.11 of BOEM's Liberty Drilling and Production Plan EIS clearly explains NMFS' permitting role in the Liberty project. The EIS states that given the widespread presence of several species of marine mammals in the Beaufort Sea and the nature of oil and gas production facility construction and, potentially, operational activities, there is the potential that some activities associated with Hilcorp's LDPI may result in the take of marine mammals incidental to the introduction of noise into the marine environment and ice road construction activities. Because of the potential for these activities to take marine mammals, Hilcorp has submitted an Incidental Take Authorization (ITA) application to NMFS. NMFS provided extensive comments to BOEM on the draft and final EIS to strengthen their analysis of marine mammal impacts in consideration of Hilcorp's request for the authorization to take marine mammals incidental to construction and operation of the LDPI. The EIS describes NMFS' action and no action alternatives, which include issuing the requested incidental take authorization and denying the requested incidental take authorization, respectively. As for the six topical areas AWL raises, the FEIS addresses all of these. The bulk of the EIS is dedicated to discussing the impacts on the human environment from small and very large oil spills (Chapter 4), and Chapter 5 is dedicated solely to a cumulative effects assessment. Greenhouse gases emission from the LDPI are quantified in Chapter 4 (

e.g.,

Table 4-6 in BOEM's EIS) and climate change impacts on marine mammals are addressed in Chapter 4 (

e.g.,

Section 3.2.4.6.6) and Chapter 5 (

e.g.,

section 5.1.3). The impacts of the LDPI on marine mammals is also thoroughly discussed in Chapter 4 which includes both construction and operation analysis. Subsistence uses and potential impacts are described throughout the document relative to each resources and are summarized in Table ES-1. The EIS does not discuss Hilcorp's previous environmental compliance record; however, as described in response to Comment #38, this is beyond the scope of NMFS' action and inclusion in the EIS is not required for us to adopt the EIS for purposes of issuing the regulations.

Comment 29:

AWL notes that NMFS considered new information provided by Hilcorp that was not covered in the EIS. Specifically, on February 4, 2019, Hilcorp provided “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 estimated take numbers.” AWL believes this additional information could affect the agency's analysis of the effects of the project on marine mammals.

Response:

Foundation piles are described in BOEM's EIS on pages 2-12 and, as described in the proposed rule, the installation of foundation piles was found to result in very low noise levels, equivalent to driving conductor pipe piles. Given these piles are driven on the interior of the island, there is no potential for Level A harassment and the Level B harassment isopleth extends only 315 m from the island. Therefore, the potential for take is very limited. The EIS does not contain take estimates, and therefore, despite specific details and the very small amount of additional take for foundation pile installation being absent from the EIS, the information would not alter the analysis in the EIS. Requirements under NEPA are separate from those required to issue an MMPA incidental take authorization, and NMFS has satisfied the requirements for both statutes in issuing this final rule.

Comment 30:

AWL asserts that BOEM's FEIS does not consider alternatives to NMFS's proposed rule. AWL believes NMFS must consider a no action alternative, under which NMFS would deny Hilcorp's request for incidental take authorization, as well as alternatives that would further reduce harm to marine mammals, such as prohibiting construction activity during the open-water season, requiring Hilcorp to cease pile driving if an ice seal is seen in the area, requiring the use of long-term acoustic monitors, or requiring all vessels associated with the Liberty project to travel at no more than 10 knots.

Response:

As described above, BOEM's FEIS included NMFS' action and no action alternatives, which are, respectively, to issue the requested incidental take authorization, with

required mitigation measures, or to deny the requested incidental take authorization. Both the EIS and/or NMFS' regulations include a suite of mitigation measures to reduce adverse impacts to marine mammals, including no pile driving just before and during the bowhead whale hunt, long-term acoustic monitoring, and vessel speed restrictions where appropriate. These measures were included in both the FEIS and the final rule. Hilcorp will also minimize disturbance to ice seals through the incorporation of mitigation measures such as ramp-up. We have authorized Level A harassment and Level B harassment for ice seals, however; therefore, Hilcorp is not required to cease pile driving should a seal be observed in the area, as suggested by the AWL.

Comment 31:

The NSB requested the regulations require Hilcorp to participate in the annual in-person peer review sponsored by NMFS for companies operating in areas subject to marine mammal subsistence harvest and to annually meet with Borough representatives to discuss the results and findings from Hilcorp's Marine Mammal Mitigation and Monitoring Plan. The AEWC similarly recommended findings from the mitigation and monitoring plan be reviewed annually by NMFS.

Response:

Hilcorp is required to submit annual monitoring reports to NMFS in a timely manner. NMFS conducts peer-review panels when activities are proposed in Arctic waters, and whether the meetings are in-person or virtual depends on the level of expected activity necessitating MMPA authorization and the availability of travel resources for NMFS staff. For the LDPI, NMFS will provide the NSB and the public all of Hilcorp's annual monitoring reports as well as any interim reports (

e.g.,

initial acoustic monitoring reports) for their review. Throughout the life of the regulations, NMFS will engage with Hilcorp as well as the NSB to address any deficiencies or issues with those reports. In addition, Hilcorp has committed to participating in the annual peer-review panel, of which NSB is an invitee, to discuss data collected during marine mammal and acoustic monitoring as a means to carry out this coordination.

Comment 33:

The NSB recommends the regulations prohibit any pile driving during, and two weeks prior to, the whale hunting season in Nuiqsut, unless Hilcorp can conclusively demonstrate that such vibratory pile driving does not alter the migratory paths of bowheads.

Response:

Per the BOEM permit conditions, Hilcorp shall cease all pipe- and pile- driving by August 1, annually, and not resume until the end of the official hunt season or if subsistence users have met the whale quota. This mitigation measure is included in the final rule.

Comment 34:

The AEWC commended Hilcorp for keeping the AEWC informed throughout their planning process for Liberty, their commitment to continuing their participation in the Open Water Season Conflict Avoidance Agreement (CAA) and the Annual CAA Process, and expressed their appreciation for Hilcorp's work with the AEWC, the community of Nuiqsut, and the North Slope Borough.

Response:

NMFS will work with Hilcorp throughout the life of the regulations to support communication and coordination with the AEWC, the community of Nuiqst, and the NSB continues.

Comment 35:

Several members of the public opposed drilling due to the potential for an oil spill.

Response:

NMFS' authority and these final regulations allow for issuance of a Letter of Authorization to authorize takes of marine mammals incidental to island construction and operation. NMFS has no authority over whether this project, or any other drilling, is permitted. BOEM is the entity responsible for deciding whether to permit the project.

Comment 36:

One commenter was concerned about polar bear impacts and discussed incidental take permit requirements for this species.

Response:

Polar bears, and any permit related to the taking of polar bears under the MMPA or ESA, fall within the jurisdiction of the U.S. Fish and Wildlife Service. Therefore, this comment is outside NMFS' authority and the scope of the rulemaking.

Comment 37:

One commenter urged review of the drilling plan for oil spill protection and earthquake contingencies and indicated that if a Deepwater Horizon event occurred in the Beaufort Sea, it would take decades to recover.

Response:

NMFS remains interested in reviewing Hilcorp's oil spill response plan and, as indicated on page 24946 of the proposed rule, we have proactively engaged with BSEE (the Federal agency charged with reviewing and approving Hilcorp's oil spill response plan) and recommended measures to be included in the oil spill response plan. BSEE has indicated that NMFS will have an opportunity to review the oil spill response plan once they receive all the information necessary to move forward with their process.

Comment 38:

One commenter had concerns about Hilcorp's ability to build and manage the project. Their concerns stem from an incident earlier this year when Hilcorp's underwater gas pipeline in Alaska's Cook Inlet leaked for nearly four months because the company said the presence of sea ice prevented its repair.

Response:

NMFS' authority and these final regulations allow for issuance of a Letter of Authorization to authorize takes of marine mammals incidental to island construction and operation. BOEM and BSEE have authority over the permitting of the project and Hilcorp's oil spill response plan, respectively; therefore, this comment is beyond the scope of NMFS's authority under this rulemaking.

NMFS notes, however, that Cook Inlet presents different ice conditions than the Arctic where the Liberty project is to be located. Ice roads are not constructed in Cook Inlet which limited response capabilities. However, in the Arctic, ice roads and thick sea ice allow for other means of spill response. As analyzed by BOEM, the effectiveness of cleanup operations is highly dependent on volume, location, and time of year in Alaska. A small spill occurring during winter on solid ice and snow can be readily cleaned up using conventional land-based equipment such as shovels, snow blowers, and bulldozers, resulting in a near 100% recovery rate. In the event of a winter blowout, response methods would be similar to those employed on shore. Instead of using boats and skimmers to mount a response, responders would utilize front-end loaders, bulldozers, vacuum trucks, dump trucks, and front-end mounted ice trimmers to collect and remove the oil contaminated snow and ice. To facilitate response, ice roads would have to be constructed to adequately support the equipment and maintain safe operating conditions. In addition to heavy equipment, response operations would also include the use of snow blowers, shovels, and snow machines/ATVs with sleds to collect and remove the oil. In situ burning would also be utilized to remove oil from the ice surface. A release in solid ice conditions is easier to respond to because ice contains oil, limiting its dispersal into the marine environment.

Comment 39:

One commenter recommended the LDPI project should not be implemented until further technology can promise this project will not impact the ocean negatively.

Response:

Under the MMPA, NMFS must evaluate each request for an incidental take authorization on the merits of the application and the specified activity. Here, NMFS is not authorizing the take of marine mammals

from activities other than island construction and operation for 5 years. NMFS found, through a robust analysis of the potential effects of these activities on marine mammals and their habitat, that: The specified activities would have a negligible impact on the affected species and stocks and would not have an unmitigable adverse impact on subsistence uses, and; that the prescribed mitigation measures would effect the least practicable adverse impact on such species and stocks. NMFS has no authority to delay issuance of an ITA if the findings described above are made.

Comment 40:

One commenter recommended the project should not be allowed to proceed unless it does not harm or kill marine life.

Response:

NMFS does not issue permits to construct and operate the LDPI (

i.e.,

allow or not allow the underlying activity). NMFS issues authorization to take marine mammals incidental to the specified activity. The MMPA prohibits, with certain exceptions, the take of marine mammals. However, the MMPA allows, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity within a specified geographic region. Hilcorp applied for an incidental take authorization in accordance with the MMPA and its implementing regulations and NMFS followed the required process in promulgating incidental take regulations. Accordingly, NMFS is issuing regulations and will issue an LOA authorizing the take of marine mammals incidental to the construction and operation of the LDPI in accordance with the MMPA.

Comment 41:

One commenter was concerned that allowing Hilcorp to harass and harm belugas, possibly resulting in their deaths, would decrease the beluga population in that area, and that this population would also not be able to recover losses. The commenter referred to the Cook Inlet beluga whale population status and lack of recovery after subsistence hunting was restricted as justification for the comment.

Response:

The commenter believes the specified activities would result in beluga whale mortality and inappropriately compares a very small, isolated and critically endangered stock of beluga whales in Cook Inlet to a robust, far-ranging, non-ESA listed, stock in the Arctic. The final rule does not authorize any mortality or serious injury of beluga whales incidental to the construction and operations of the LDPI and NMFS does not believe any would potentially occur. The population of the Beaufort Sea stock of beluga whales is estimated at 39,258 individuals (compared to the Cook Inlet beluga whale stock of 327 whales) and has a much greater habitat range than Cook Inlet belugas. Any harassment to belugas in Foggy Island Bay incidental to pile driving or operations (

e.g.,

drilling) would be very limited, as pile driving would primarily occur during the ice-covered months when beluga whales are not present and, if any belugas are present during any pile driving or drilling activity, that activity would only impact a very small number of whales, as Foggy Island Bay is not heavily used by cetaceans, including beluga whales.

Comment 42:

One commenter believed Hilcorp's activity may also affect the salmon populations upon which endangered whales depend and that allowing Hilcorp to take even a small number of protected animals will result in a psychological acceptance of harming these creatures and thus lead to even more animals being harmed.

Response:

The potential impacts to marine mammal prey from the LDPI are evaluated in a number of assessments including the proposed rule, ESA section 7 consultation completed for issuance of the rule (see NMFS Biological Opinion issued August 30, 2019), and BOEM's EIS. Those assessments determined the LDPI would have a minimal impact on marine mammal prey, given, among other things, the LDPI's location outside critical foraging habitats and implementation of measures designed to reduce impacts to marine mammals and their habitat, including prey. The regulations, issued pursuant to the MMPA, allow the taking of marine mammals incidental to the specified activity. NMFS evaluates and, if appropriate, issues an ITA based on the information contained within an ITA application and the best available science. The take authorized is limited to the 5-year period the regulations are effective.

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 the 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).

Table 2—Marine Mammals With Expected Potential Occurrence in Beaufort Sea, Alaska

Common name

Scientific name

Stock

ESA/

MMPA

status;

strategic

(Y/N)

1

Stock abundance

(CV, N

min

, most recent

abundance survey)

2

PBR

Annual

M/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, 2011)

624

132

Family Balaenidae:

Bowhead whale

Balaena mysticetus

Western Arctic

E/D; Y

16,820 (0.052, 16,100, 2011)

161

46

Humpback whale

Megaptera novaeangliae

)

Central North Pacific Stock

E/D; Y

10,103 (0.3, 7,891, 2006)

83

26

Minke whale

Alaska

-;N

unk

undet.

0

Fin whale

Northeast Pacific

E/D; Y

3,168 (0.26, 2,554, 2013)

6

5.1

0.6

Superfamily Odontoceti (toothed whales, dolphins, and porpoises)

Family Delphinidae:

Beluga whale

Delphinapterus leucas

Beaufort Sea

-; N

39,258 (0.229, N/A, 1992)

Und.

139

Eastern Chukchi

-; N

20,752 (0.70, 12,194, 2012)

244

67

Killer whale

Orcinus orcas

Eastern North Pacific Gulf of Alaska, Aleutian Islands, and Bering Sea Transient

-;N

587 (n/a, 587, 2012)

5.9

0

Order Carnivora—Superfamily Pinnipedia

Family Otariidae (eared seals and sea lions):

Steller sea lion

Eumatopias jubatus

Eastern U.S

-; N

41,638 (-, 41,638, 2015)

2,498

108

Western U.S

E/D;Y

53,303 (-, 53,303, 2016)

320

241

Family Phocidae (earless seals):

Ringed Seal

Pusa hispida

Alaska

T, D; Y

170,000 (-, 170,000, 2012)

4

Und.

1,054

Bearded seal

Erignathus barbatus

Alaska

T, D; Y

299,174 (-, 273,676)

5

Und.

391

Spotted seal

Phoca largha

Alaska

423,625 (-, 423,237, 2013)

12,697

329

Ribbon seal

Histriophoca fasciata

Alaska

184,000 (-, 163,086, 2013)

9,785

3.9

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 the 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 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

In the spring of 2012 and 2013, surveys were conducted in the Bering Sea and the Sea of Okhotsk; these data do not include seals in the Chukchi and Beaufort Seas at the time of the survey.

6

N

BEST

, N

MIN

, and PBR have been calculated for this stock; however, important caveats exist. See Stock Assessment Report text for details.

Note

Italicized species are not authorized to be taken.

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 a 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 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 authorized to be 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. The 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 they may be encompassed in indirect areas such as vessel transit routes. 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 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 its 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 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 provides 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° 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 200m (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 the 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° 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 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 a 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 the 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 the 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 between July 9 and 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. The 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 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, were stranded or sampled during permitted health assessments studies. The 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° E longitude (Novosibirskiye) in the East Siberian Sea and 130° W longitude in the Canadian Beaufort Sea, except west of 157° 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 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 they 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).

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

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 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, takes 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 the weight of the ice road and use as the 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 Mammals

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 were 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 rule over the five-year life of the regulations. To mitigate this risk, NMFS and Hilcorp have developed a number of BMPs aimed at reducing the potential of disturbing (

e.g.,

crushing) ice seal structures on ice roads (see Mitigation and Monitoring sections).

Potential Acoustic Impacts—Level A Harassment and Level B Harassment

In the following discussion, we provide general background information 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 sh

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