[Federal Register Volume 84, Number 62 (Monday, April 1, 2019)]
[Proposed Rules]
[Pages 12330-12377]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-05781]



[[Page 12329]]

Vol. 84

Monday,

No. 62

April 1, 2019

Part II





Department of Commerce





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National Oceanic and Atmospheric Administration





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50 CFR Part 217





Takes of Marine Mammals Incidental to Specified Activities; Taking 
Marine Mammals Incidental to Oil and Gas Activities in Cook Inlet, 
Alaska; Proposed Rule

  Federal Register / Vol. 84 , No. 62 / Monday, April 1, 2019 / 
Proposed Rules  

[[Page 12330]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 217

[Docket No. 190214112-9112-01]
RIN 0648-BI62


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Oil and Gas Activities in Cook 
Inlet, Alaska

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

ACTION: Proposed rule; request for comments.

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SUMMARY: NMFS has received a request from Hilcorp Alaska LLC (Hilcorp) 
for authorization to take marine mammals incidental to oil and gas 
activities in Cook Inlet, Alaska, over the course of five years (2019-
2024). As required by the Marine Mammal Protection Act (MMPA), NMFS is 
proposing regulations to govern that take, and requests comments on the 
proposed regulations. NMFS will consider public comments prior to 
making any final decision on the issuance of the requested MMPA 
authorization, and agency responses will be summarized in the final 
notice of our decision.

DATES: Comments and information must be received no later than May 1, 
2019.

ADDRESSES: You may submit comments, identified by NOAA-NMFS-2019-0026, 
by any of the following methods:
     Electronic submissions: Submit all electronic public 
comments via the Federal eRulemaking Portal, Go to www.regulations.gov/#!docketDetail;D=NOAA-NMFS-2019-0026, click the ``Comment Now!'' icon, 
complete the required fields, and enter or attach your comments.
     Mail: Submit comments to Jolie Harrison, Chief, Permits 
and Conservation Division, Office of Protected Resources, National 
Marine Fisheries Service, 1315 East-West Highway, Silver Spring, MD 
20910-3225.
    Instructions: Comments sent by any other method, to any other 
address or individual, or received after the end of the comment period, 
may not be considered by NMFS. All comments received are a part of the 
public record and will generally be posted for public viewing on 
www.regulations.gov without change. All personal identifying 
information (e.g., name, address, etc.), confidential business 
information, or otherwise sensitive information submitted voluntarily 
by the sender may be publicly accessible. Do not submit Confidential 
Business Information or otherwise sensitive or protected information. 
NMFS will accept anonymous comments (enter ``N/A'' in the required 
fields if you wish to remain anonymous). Attachments to electronic 
comments will be accepted in Microsoft Word, Excel, or Adobe PDF file 
formats only.

FOR FURTHER INFORMATION CONTACT: Sara Young, Office of Protected 
Resources, NMFS, (301) 427-8401. Electronic copies of the application 
and supporting documents, as well as a list of the references cited in 
this document, may be obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-oil-and-gas. In case of problems accessing these 
documents, please call the contact listed above.

SUPPLEMENTARY INFORMATION:

Purpose and Need for Regulatory Action

    This proposed rule would establish a framework under the authority 
of the MMPA (16 U.S.C. 1361 et seq.) to allow for the authorization of 
take of marine mammals incidental to Hilcorp's oil and gas activities 
in Cook Inlet, Alaska.
    We received an application from Hilcorp requesting five-year 
regulations and authorization to take multiple species of marine 
mammals. Take would occur by Level A and Level B harassment incidental 
to a variety of sources including: 2D and 3D seismic surveys, geohazard 
surveys, vibratory sheet pile driving, and drilling of exploratory 
wells. Please see ``Background'' below for definitions of harassment.

Legal Authority for the Proposed Action

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

Summary of Major Provisions Within the Proposed Rule

    Following is a summary of the major provisions of this proposed 
rule regarding Hilcorp's activities. These measures include:
     Required monitoring of the ensonified areas to detect the 
presence of marine mammals before beginning activities;
     Shutdown of activities under certain circumstances to 
minimize injury of marine mammals;
     Ramp up at the beginning of seismic surveying to allow 
marine mammals the opportunity to leave the area prior to beginning the 
survey at full power, as well as power downs, and vessel strike 
avoidance;
     Ramp up of impact hammering of the drive pipe for the 
conductor pipe driven from the drill rig; and
     Ceasing noise producing activities within 10 miles (16 km) 
of the mean higher high water (MHHW) line of the Susitna Delta (Beluga 
River to the Little Susitna River) between April 15 and October 15.

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 may be provided to the public 
for review.
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other means of effecting the least practicable adverse 
impact on the

[[Page 12331]]

affected species or stocks and their habitat, paying particular 
attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of such species or stocks for 
taking for certain subsistence uses (referred to in shorthand as 
``mitigation''); and requirements pertaining to the mitigation, 
monitoring and reporting of such takings are set forth.
    NMFS has defined ``negligible impact'' in 50 CFR 216.103 as an 
impact resulting from the specified activity that cannot be reasonably 
expected to, and is not reasonably likely to, adversely affect the 
species or stock through effects on annual rates of recruitment or 
survival.
    The MMPA states that the term ``take'' means to harass, hunt, 
capture, kill or attempt to harass, hunt, capture, or kill any marine 
mammal. Except with respect to certain activities not pertinent here, 
the MMPA defines ``harassment'' as any act of pursuit, torment, or 
annoyance which (i) has the potential to injure a marine mammal or 
marine mammal stock in the wild (Level A harassment); or (ii) has the 
potential to disturb a marine mammal or marine mammal stock in the wild 
by causing disruption of behavioral patterns, including, but not 
limited to, migration, breathing, nursing, breeding, feeding, or 
sheltering (Level B harassment).

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must review our proposed action (i.e., the issuance of an 
incidental harassment authorization) with respect to potential impacts 
on the human environment.
    Accordingly, NMFS is preparing an Environmental Assessment (EA) to 
consider the environmental impacts associated with the issuance of the 
proposed rule. NMFS' EA will be made available at https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-oil-and-gas on the date of publication of the 
proposed rule.
    We will review all comments submitted in response to this notice 
prior to concluding our NEPA process or making a final decision on the 
rulemaking request.

Summary of Request

    On April 17, 2018, NMFS received an application from Hilcorp 
requesting authorization to incidentally take marine mammals, by Level 
A and Level B harassment, incidental to noise exposure resulting from 
oil and gas activities in Cook Inlet, Alaska, from May 2019 to April 
2024. These regulations would be valid for a period of five years. On 
October 8, 2018, NMFS deemed the application adequate and complete.
    The use of sound sources such as those described in the application 
(e.g., seismic airguns) may result in the take of marine mammals 
through disruption of behavioral patterns or may cause auditory injury 
of marine mammals. Therefore, incidental take authorization under the 
MMPA is warranted.

Description of Proposed Activity

Overview

    The scope of Hilcorp's Petition includes four stages of activity, 
including exploration, development, production, and decommissioning 
activities within the Applicant's area of operations in and adjacent to 
Cook Inlet within the Petition's geographic area (Figures 3 and 8 in 
the application). Table 1 summarizes the planned activities within the 
geographic scope of this Petition, and the following text describes 
these activities in more detail. This section is organized into two 
primary areas within Cook Inlet: lower Cook Inlet (south of the 
Forelands to Homer) and middle Cook Inlet (north of the Forelands to 
Susitna/Point Possession).

                              Table 1--Summary of Planned Activities Included in Incidental Take Regulations (ITR) Petition
--------------------------------------------------------------------------------------------------------------------------------------------------------
           Project name               Cook Inlet region        Year(s) planned        Seasonal timing    Anticipated duration  Anticipated noise sources
--------------------------------------------------------------------------------------------------------------------------------------------------------
Anchor Point 2D seismic survey....  Lower Cook Inlet,      2021 or 2022..........  April-October.......  30 days.............  Marine: 1 source vessel
                                     Anchor Point to                                                                            with airgun, 1 node
                                     Kasilof.                                                                                   vessel Onshore/
                                                                                                                                Intertidal: Shot holes,
                                                                                                                                tracked vehicles,
                                                                                                                                helicopters.
Outer Continental Shelf (OCS) 3D    Lower Cook Inlet OCS.  2019..................  April-June..........  45-60 days..........  1 source vessel with
 seismic survey.                                                                                                                airguns, 2 support
                                                                                                                                vessels, 1 mitigation
                                                                                                                                vessel potentially.
OCS geohazard survey..............  Lower Cook Inlet OCS.  2019 or 2020..........  Fall 2019 or spring   30 days.............  1 vessel with chosounders
                                                                                    20202.                                      and/or sub-bottom
                                                                                                                                profilers.
OCS exploratory wells.............  Lower Cook Inlet OCS.  2020-2022.............  April-October.......  40-60 days per well,  1 jack-up rig, drive pipe
                                                                                                          2-4 wells per year.   installation, vertical
                                                                                                                                seismic profiling, 2-3
                                                                                                                                tugs for towing rig,
                                                                                                                                support vessels,
                                                                                                                                helicopters.
Iniskin Peninsula exploration and   Lower Cook Inlet,      2019-2020.............  April-October.......  180 days............  Construction of causeway,
 development.                        west side.                                                                                 vibratory sheet pile
                                                                                                                                driving, dredging,
                                                                                                                                vessels.
Platform & pipeline maintenance...  Middle Cook Inlet....  2019-2024.............  April-October.......  180 days............  Vessels, water jets,
                                                                                                                                hydraulic grinders,
                                                                                                                                pingers, helicopters,
                                                                                                                                and/or sub-bottom
                                                                                                                                profilers.
North Cook Inlet Unit subseawell    Middle Cook Inlet....  2020..................  May.................  14 days.............  1 vessel with
 geohazard survey.                                                                                                              echosounders and/or sub-
                                                                                                                                bottom profilers.
North Cook Inlet Unit well          Middle Cook Inlet....  2020..................  May-July............  90 days.............  1 jack-up rig, tugs
 abandonment activity.                                                                                                          towing rig, support
                                                                                                                                vessel, helicopters.
Trading Bay area geohazard survey.  Middle Cook Inlet....  2020..................  May.................  30 days.............  1 vessel with
                                                                                                                                echosounders and/or sub-
                                                                                                                                bottom profilers.
Trading Bay area exploratory wells  Middle Cook Inlet....  2020..................  May-October.........  120-150 days........  1 jack-up rig, drive pipe
                                                                                                                                installation, vertical
                                                                                                                                seismic profiling, tugs
                                                                                                                                towing rig, support
                                                                                                                                vessel, helicopters.
Drift River terminal                Lower Cook Inlet,      2023..................  April-October.......  120 days............  Vessels.
 decommissioning.                    west side.
--------------------------------------------------------------------------------------------------------------------------------------------------------


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Dates and Duration

    The scope of the Petition includes exploration, development, 
production, and decommissioning activities within the Applicant's area 
of operations in and adjacent to Cook Inlet within the Petition's 
geographic area (Figures 3 and 8 in the application) for the period of 
five years beginning May 1, 2019, extending through April 30, 2024.

Specific Geographic Region

    The geographic area of activity covers a total of approximately 2.7 
million acres (10,926 km\2\) in Cook Inlet. It includes land and 
adjacent waters in Cook Inlet including both State of Alaska and 
Federal OCS waters (Figure 3 and 8 in the application). The area 
extends from the north at the Susitna Delta on the west side 
(61[deg]10' 48 N, 151[deg]0' 55 W) and Point Possession on the east 
side (61[deg]2' 11 N, 150[deg]23' 30 W) to the south at Ursus Cove on 
the west side (59[deg]26' 20 N, 153[deg]45' 5 W) and Nanwalek on the 
east side (59[deg]24' 5 N, 151[deg]56' 30 W). The area is depicted in 
Figures 3 amd 8 of the application.

Detailed Description of Specific Activity

Activities in Lower Cook Inlet
    Based on potential future lease sales in both State and Federal 
waters, operators collect two-dimensional (2D) seismic data to 
determine the location of possible oil and gas prospects. Generally, 2D 
survey lines are spaced farther apart than three-dimensional (3D) 
surveys and are conducted in a regional pattern that provides less 
detailed geological information. 2D surveys are used to cover wider 
areas to map geologic structures on a regional scale. Airgun array 
sizes used during 2D surveys are similar to those used during 3D 
surveys.
Activities in Middle Cook Inlet
2D Seismic Survey
    During the timeframe of this Petition, the region of interest for 
the 2D survey is the marine, intertidal, and onshore area on the 
eastern side of Cook Inlet from Anchor Point to Kasilof. The area of 
interest is approximately 8 km (5 miles) offshore of the coastline. The 
anticipated timing of the planned 2D survey is in the open water season 
(April through October) in either 2020 or 2021. The actual survey 
duration is approximately 30 days in either year.
    The 2D seismic data are acquired using airguns in the marine zone, 
airguns in the intertidal zone when the tide is high and drilled shot 
holes in the intertidal zone when the tide is low and drilled shot 
holes in the land zone. The data are recorded using an autonomous nodal 
system (i.e., no cables) that are deployed in the marine, intertidal, 
and land zones. The planned source lines (airgun and shot holes) are 
approximately 16 km (10 mi) in length running perpendicular to the 
coastline (see Figure 1 in application). The source lines are spaced 
every 8 km (5 mi) in between Anchor Point and Kasilof, with 
approximately 9-10 lines over the area of interest.
    In the marine and high tide intertidal zones, data will be acquired 
using a shallow water airgun towed behind one source vessel. Although 
the precise volume of the airgun array is unknown at this time, Hilcorp 
will use an airgun array similar to what has been used for surveys in 
Cook Inlet by Apache (2011-2013) and SAExploration (2015): Either a 
2,400 cubic inch (cui) or 1,760 cui array. A 2,400 cui airgun was 
assumed for analysis in this proposed rule to be conservative in take 
estimation. In addition, the source vessel will be equipped with a 440 
cui shallow water source which it can deploy at high tide in the 
intertidal area in less than 1.8 meter (6 feet) of water. Source lines 
are oriented along the node line. A single vessel is capable of 
acquiring a source line in approximately 1-2 hours (hrs). In general, 
only one source line will be collected in one day to allow for all the 
node deployments and retrievals, and intertidal and land zone shot 
holes drilling. There are up to 10 source lines, so if all operations 
run smoothly, there will only be 2 hr per day over 10 days of airgun 
activity. Hilcorp anticipates the entire operation to take 
approximately 30 days to complete to account for weather and equipment 
contingencies.
    The recording system that will be employed is an autonomous system 
``nodal'' (i.e., no cables), which is expected to be made up of at 
least two types of nodes; one for the land and one for the intertidal 
and marine environment. For the intertidal and marine zone, this will 
be a submersible multi-component system made up of three velocity 
sensors and a hydrophone. These systems have the ability to record 
continuous data. Inline receiver intervals for the node systems are 
approximately 50 m (165 ft). For 2D seismic surveys, the nodes are 
deployed along the same line as the seismic source. The deployment 
length is restricted by battery duration and data storage capacity. The 
marine nodes will be placed using one node vessel. The vessels required 
for the 2D seismic survey include just a source vessel and a node 
vessel that is conducting only passive recording.
    In the marine environment, once the nodes are placed on the 
seafloor, the exact position of each node is required. In very shallow 
water, the node positions are either surveyed by a land surveyor when 
the tide is low, or the position is accepted based on the position at 
which the navigator has laid the unit. In deeper water, a hull or pole 
mounted pinger to send a signal to the transponder which is attached to 
each node will be used. The transponders are coded and the crew knows 
which transponder goes with which node prior to the layout. The 
transponders response (once pinged) is added together with several 
other responses to create a suite of range and bearing between the 
pinger boat and the node. Those data are then calculated to precisely 
position the node. In good conditions, the nodes can be interrogated as 
they are laid out. It is also common for the nodes to be pinged after 
they have been laid out. Onshore and intertidal locating of source and 
receivers will be accomplished with Differential Global Positioning 
System/roving units (DGPS/RTK) equipped with telemetry radios which 
will be linked to a base station established on the source vessel. 
Survey crews will have both helicopter and light tracked vehicle 
support. Offshore source and receivers will be positioned with an 
integrated navigation system (INS) utilizing DGPS/RTK link to the land 
base stations. The integrated navigation system will be capable of many 
features that are critical to efficient safe operations. The system 
will include a hazard display system that can be loaded with known 
obstructions, or exclusion zones. Apache conducted a sound source 
verification (SSV) for the 440 cui and 2,400 cui arrays in 2012 (Austin 
and Warner 2012; 81 FR 47239). The location of the SSV was in Beshta 
Bay on the western side of Cook Inlet (between Granite Point and North 
Forelands). Water depths ranged from 30-70 m (98-229 ft).
    For the 440 cui array, the measured levels for the broadside 
direction were 217 decibel (dB) re: 1microPa ([mu]Pa) peak, 190 dB 
sound exposure level (SEL), and 201 dB root mean square (rms) at a 
distance of 50 m. The estimated distance to the 160 dB rms (90th 
percentile) threshold assuming the empirically measured transmission 
loss of 20.4 log R (Austin and Warner, 2012) was 2,500 m. Sound level 
near the source were highest between 30 and 300 hertz (Hz) in the 
endfire direction and between 20 Hz and 300 Hz in the broadside 
direction.
    For the 2,400 cui array, the measured levels for the endfire 
direction were 217

[[Page 12333]]

dB peak, 185 dB SEL, and 197 dB rms at a distance of 100 m. The 
estimate distance to the 160 dB rms (90th percentile) thresholds 
assuming the empirically measured transmission loss of 16.9 log R was 
7,770 m. Sound levels near the source were highest between 30 and 150 
Hz in the endfire direction and between 50 and 200 Hz in the broadside 
direction. These measured levels were used to evaluate potential Level 
A (217 dB peak and 185 dB SEL at 100 m assuming 15 log transmission 
loss) and Level B (7,330 m distance to 160 dB threshold) harassment 
isopleths from these sound sources (see Estimated Take section).
3D Seismic Survey
    During the timeframe of this Petition, Hilcorp plans to collect 3D 
seismic data for approximately 45-60 days starting May 1, 2019 over 8 
of the 14 OCS lease blocks in lower Cook Inlet. The 3D seismic survey 
is comprised of an area of approximately 790 km\2\ (305 mi\2\) through 
8 lease blocks (6357, 6405, 6406, 6407, 6455, 6456, 6457, 6458). 
Hilcorp submitted an application for an Incidental Harassment 
Authorization (IHA) in late 2017 for a planned survey in 2018 but 
withdrew the application and now plan for the survey to take place in 
2019 and cover several years of surveying and development. The survey 
program is anticipated to begin May 1, 2019, and last for approximately 
45-60 days through June 2019 in compliance with identified Bureau of 
Ocean Energy Management (BOEM) lease stipulations. The length of the 
survey will depend on weather, equipment, and marine mammal delays 
(contingencies of 20 percent weather, 10 percent equipment, 10 percent 
marine mammal were assumed in this analysis, or a 40 percent increase 
in expected duration to account for the aforementioned delays).
    Polarcus is the intended seismic contractor, and the general 
seismic survey design is provided below. The 3D seismic data will be 
acquired using a specially designed marine seismic vessel towing 
between 8 and 12 ~2,400-m (1.5 mi) recording cables with a dual air gun 
array. The survey will involve one source vessel, one support vessel, 
one chase vessel, and potentially one mitigation vessel. The 
anticipated seismic source to be deployed from the source vessel is a 
14-airgun array with a total volume of 1,945 cui. Crew changes are 
expected to occur every four to six weeks using a helicopter or support 
vessel from shore bases in lower Cook Inlet. The proposed seismic 
survey will be active 24 hrs per day. The array will be towed at a 
speed of approximately 7.41 km/hr (4 knots), with seismic data 
collected continuously. Data acquisition will occur for approximately 5 
hrs, followed by a 1.5-hr period to turn and reposition the vessel for 
another pass. The turn radius on the seismic vessel is approximately 
3,200 m (2 mi).
    The data will be shot parallel to the Cook Inlet shorelines in a 
north/south direction. This operational direction will keep recording 
equipment/streamers in line with Cook Inlet currents and tides and keep 
the equipment away from shallow waters on the east and west sides. The 
program may be modified if the survey cannot be conducted as a result 
of noise conditions onsite (i.e., ambient noise). The airguns will 
typically be turned off during the turns. However, depending on the 
daylight hours and length of the turn, Hilcorp may use the smallest gun 
in the array (45 cui) as a mitigation airgun where needed for no longer 
than 3 hours. The vessel will turn into the tides to ensure the 
recording cables/streamers remain in line behind the vessel.
    Hilcorp plans to use an array that provides for the lowest possible 
sound source to collect the target data. The proposed array is a Bolt 
1900 LLXT dual gun array. The airguns will be configured as two linear 
arrays or ``strings;'' each string will have 7 airguns shooting in a 
``flip-flop'' configuration for a total of 14 airguns. The airguns will 
range in volume from 45 to 290 cui for a total of 1,945 cui. The first 
and last are spaced approximately 14 m (45.9 ft) apart and the strings 
are separated by approximately 10 m (32.8 ft). The two airgun strings 
will be distributed across an approximate area of 30 x 14 m (98.4 x 
45.9 ft) behind the source vessel and will be towed 300-400 m (984-
1,312 ft) behind the vessel at a depth of 5 m (16.4 ft). The firing 
pressure of the array is 2,000 pounds per square inch (psi). The airgun 
will fire every 4.5 to 6 seconds, depending on the exact speed of the 
vessel. When fired, a brief (25 milliseconds [ms] to 140 ms) pulse of 
sound is emitted by all airguns nearly simultaneously. Hilcorp proposes 
to use a single 45 cui airgun, the smallest airgun in the array, for 
mitigation purposes.
    Hilcorp intends to use 8 Sercel-type solid streamers or 
functionally similar for recording the seismic data (Figure 5 in the 
application). Each streamer will be approximately 2,400 m (150 mi) in 
length and will be towed approximately 8-15 m (26.2-49.2 ft) or deeper 
below the surface of the water. The streamers will be placed 
approximately 50 m (165 ft) apart to provide a total streamer spread of 
400 m (1,148 ft). Hilcorp recognizes solid streamers as best in class 
for marine data acquisition because of unmatched reliability, signal to 
noise ratio, low frequency content, and noise immunity.
    The survey will involve one source vessel, one support vessel, one 
or two chase vessels, and potentially one mitigation vessel. The source 
vessel tows the airgun array and the streamers. The support vessel 
provides general support for the source vessel, including supplies, 
crew changes, etc. The chase vessel monitors the in-water equipment and 
maintains a security perimeter around the streamers. The mitigation 
vessel provides a viewing platform to augment the marine mammal 
monitoring program.
    The planned volume of the airgun array is 1,945 cui. Hilcorp and 
their partners will be conducting detailed modeling of the array 
output, but a detailed SSV has not been conducted for this array in 
Cook Inlet. Therefore, for the purposes of estimating acoustic 
harassment, results from previous seismic surveys in Cook Inlet by 
Apache and SAExploration, particularly the 2,400 cui array, were used. 
Apache conducted an SSV for the 440 cui and 2,400 cui arrays in 2012 
(Austin and Warner 2012; 81 FR 47239). The location of the SSV was in 
Beshta Bay on the western side of Cook Inlet (between Granite Point and 
North Forelands). Water depths ranged from 30-70 m (98-229 ft). For the 
2,400 cui array, the measured levels for the endfire direction were 217 
dB peak, 185 dB SEL, and 197 dB rms at a distance of 100 m. The 
estimate distance to the 160 dB rms (90th percentile) thresholds 
assuming the empirically measured transmission loss of 16.9 log R was 
7,770 m. Sound levels near the source were highest between 30 and 150 
Hz in the endfire direction and between 50 and 200 Hz in the broadside 
direction.
    These measured levels were used to evaluate potential Level A (217 
dB peak and 185 dB SEL at 100 m assuming 15 log transmission loss) and 
B (7,330 m distance to 160 dB threshold) acoustic harassment of marine 
mammals in this Petition.
Geohazard and Geotechnical Surveys
    Upon completion of the 3D seismic survey over the lower Cook Inlet 
OCS leases, Hilcorp plans to conduct a geohazard survey on site-
specific regions within the area of interest prior to conducting 
exploratory drilling. The precise location is not known, as it depends 
on the results of the 3D seismic survey, but the location will be 
within the lease blocks. The anticipated timing of the activity is in 
either the fall of 2019

[[Page 12334]]

or the spring of 2020. The actual survey duration will take 
approximately 30 days.
    The suite of equipment used during a typical geohazards survey 
consists of single beam and multi-beam echosounders, which provide 
water depths and seafloor morphology; a side scan sonar that provides 
acoustic images of the seafloor; a sub-bottom profiler which provides 
20 to 200 m (66 to 656 ft) sub-seafloor penetration with a 6- to 20-
centimeter (cm, 2.4-7.9-inch [in]) resolution. Magnetometers, to detect 
ferrous items, may also be used. Geotechnical surveys are conducted to 
collect bottom samples to obtain physical and chemical data on surface 
and near sub-surface sediments. Sediment samples typically are 
collected using a gravity/piston corer or grab sampler. The surveys are 
conducted from a single support vessel.
    The echosounders and sub-bottom profilers are generally hull-
mounted or towed behind a single vessel. The ship travels at 3-4.5 
knots (5.6-8.3 km/hr). Surveys are site specific and can cover less 
than one lease block in a day, but the survey extent is determined by 
the number of potential drill sites in an area. BOEM guidelines at NTL-
A01 require data to be gathered on a 150 by 300 m (492 by 984 ft) grid 
within 600 m (1,969 ft) of the surface location of the drill site, a 
300 by 600 m (984 by 1,969 ft) grid along the wellbore path out to 
1,200 m (3,937 ft) beyond the surface projection of the conductor 
casing, and extending an additional 1,200 m beyond that limit with a 
1,200 by 1,200 m grid out to 2,400 m (7,874 ft) from the well site.
    The multibeam echosounder, single beam echosounder, and side scan 
sonar operate at frequencies of greater than 200 kHz. Based on the 
frequency ranges of these pieces of equipment and the hearing ranges of 
the marine mammals that have the potential to occur in the action area, 
the noise produced by the echosounders and side scan sonar are not 
likely to result in take of marine mammals and are not considered 
further in this document.
    The geophysical surveys include use of a low resolution and high 
resolution sub-bottom profiler. The proposed high-resolution sub-bottom 
profiler operates at source level of 210 dB re 1 [mu]Pa RMS at 1 m. The 
proposed system emits energy in the frequency bands of 2 to 24 kHz. The 
beam width is 15 to 24 degrees. Typical pulse rate is between 3 and 10 
Hz. The secondary low-resolution sub-bottom profiler will be utilized 
as necessary to increase sub-bottom profile penetration. The proposed 
system emits energy in the frequency bands of 1 to 4 kHz.
Exploratory Drilling
    Operators will drill exploratory wells based on mapping of 
subsurface structures using 2D and 3D seismic data and historical well 
information. Hilcorp plans to conduct the exploratory drilling program 
April to October between 2020 and 2022. The exact start date is 
currently unknown and is dependent on the results of the seismic 
survey, geohazard survey, and scheduling availability of the drill rig. 
It is expected that each well will take approximately 40-60 days to 
drill and test. Beginning in spring 2020, Hilcorp Alaska plans to 
possibly drill two and as many as four exploratory wells, pending 
results of the 3D seismic survey in the lower Cook Inlet OCS leases. 
After testing, the wells may be plugged and abandoned.
    Hilcorp Alaska proposes to conduct its exploratory drilling using a 
rig similar to the Spartan 151 drill rig. The Spartan 151 is a 150 H 
class independent leg, cantilevered jack-up drill rig with a drilling 
depth capability of 7,620 m (25,000 ft) that can operate in maximum 
water depths up to 46 m (150 ft). Depending on the rig selection and 
location, the drilling rig will be towed on site using up to three 
ocean- going tugs licensed to operate in Cook Inlet. Rig moves will be 
conducted in a manner to minimize any potential risk regarding safety 
as well as cultural or environmental impact. While under tow to the 
well sites, rig operations will be monitored by Hilcorp and the 
drilling contractor management. Very High Frequency (VHF) radio, 
satellite, and cellular phone communication systems will be used while 
the rig is under tow. Helicopter transport will also be available.
    Similarly to transiting vessels, although some marine mammals could 
receive sound levels in exceedance of the general acoustic threshold of 
120 dB from the tugs towing the drill rig during this project, take is 
unlikely to occur, primarily because of the predictable movement of 
vessels and tugs. Marine mammal population density in the project area 
is low (see Estimated Take section below), and those that are present 
are likely habituated to the existing baseline of commercial ship 
traffic. Further, there are no activity-, location-, or species-
specific circumstances or other contextual factors that would increase 
concern and the likelihood of take from towing of the drill rig.
    The drilling program for the well will be described in detail in an 
Exploration Plan to BOEM. The Exploration Plan will present information 
on the drilling mud program; casing design, formation evaluation 
program; cementing programs; and other engineering information. After 
rig up/rig acceptance by Hilcorp Alaska, the wells will be spudded and 
drilled to bottom-hole depths of approximately 2,100 to 4,900 m (7,000 
to 16,000 ft) depending on the well. It is expected that each well will 
take about 40-60 days to drill and up to 10-21 days of well testing. If 
two wells are drilled, it will take approximately 80-120 days to 
complete the full program; if four wells are drilled, it will take 
approximately 160-240 days to complete the full program.
    Primary sources of rig-based acoustic energy were identified as 
coming from the D399/D398 diesel engines, the PZ-10 mud pump, 
ventilation fans (and associated exhaust), and electrical generators. 
The source level of one of the strongest acoustic sources, the diesel 
engines, was estimated to be 137 dB re 1 [micro]Pa rms at 1 m in the 
141-178 Hz bandwidth. Based on this measured level, the 120 dB rms 
acoustic received level isopleth would be 50 m (154 ft) away from where 
the energy enters the water (jack-up leg or drill riser). Drilling and 
well construction sounds are similar to vessel sounds in that they are 
relatively low-level and low-frequency. Since the rig is stationary in 
a location with low marine mammal density, the impact of drilling and 
well construction sounds produced from the jack up rig is expected to 
be lower than a typical large vessel. There is open water in all 
directions from the drilling location. Any marine mammal approaching 
the rig would be fully aware of its presence long before approaching or 
entering the zone of influence for behavioral harassment, and we are 
unaware of any specifically important habitat features (e.g., 
concentrations of prey or refuge from predators) within the rig's zone 
of influence that would encourage marine mammal use and exposure to 
higher levels of noise closer to the source. Given the absence of any 
activity-, location-, or species-specific circumstances or other 
contextual factors that would increase concern, we do not expect 
routine drilling noise to result in the take of marine mammals.
    When planned and permitted operations are completed, the well will 
be suspended according to Bureau of Safety and Environmental 
Enforcement (BSEE) regulations. The well casings will be landed in a 
mudline hanger after each hole section is drilled. When the well is 
abandoned, the production casing is sealed with mechanical plugging 
devices and cement to prevent the movement of any reservoir fluids

[[Page 12335]]

between various strata. Each casing string will be cutoff below the 
surface and sealed with a cement plug. A final shallow cement plug will 
be set to approximately 3.05 m (10 ft) below the mudline. At this 
point, the surface casing, conductor, and drive pipe will be cutoff and 
the three cutoff casings and the mudline hanger are pulled to the deck 
of the jack-up rig for final disposal. The plugging and abandonment 
procedures are part of the Well Plan which is reviewed by BSEE prior to 
being issued an approved Permit to Drill.
    A drive pipe is a relatively short, large-diameter pipe driven into 
the sediment prior to the drilling of oil wells. The drive pipe serves 
to support the initial sedimentary part of the well, preventing the 
looser surface layer from collapsing and obstructing the wellbore. 
Drive pipes are installed using pile driving techniques. Hilcorp 
proposed to drive approximately 60 m of 76.2-cm pipe at each well site 
prior to drilling using a Delmar D62-22 impact hammer (or similar). 
This hammer has an impact weight of 6,200 kg (13,640 lbs). The drive 
pipe driving event is expected to last one to three days at each well 
site, although actual pounding of the pipe will only occur 
intermittently during this period. Conductors are slightly smaller 
diameter pipes than the drive pipes used to transport or ``conduct'' 
drill cuttings to the surface. For these wells, a 50.8-cm [20-in] 
conductor pipe may be drilled, not hammered, inside the drive pipe, 
dependent on the integrity of surface formations.
    Illingworth & Rodkin (2014) measured the hammer noise for hammering 
the drive pipe operating from the rig Endeavour for Buccaneer in 2013 
and report the source level at 190 dB at 55 m, with underwater levels 
exceeding 160 dB rms threshold at 1.63 km (1 mi). The measured sound 
levels for the pipe driving were used to evaluate potential Level A 
(source level of 221dB @1m and assuming 15 logR transmission loss) and 
Level B (1,630 m distance to the 160 dB threshold) acoustic harassment 
of marine mammals. Conductors are slightly smaller diameter pipes than 
the drive pipes used to transport or ``conduct'' drill cuttings to the 
surface. For these wells, a 50.8-cm (20-in) conductor pipe may be 
drilled, not hammered, inside the drive pipe, dependent on the 
integrity of surface formations. There are no noise concerns associated 
with the conductor pipe drilling.
    Once the well is drilled, accurate follow-up seismic data may be 
collected by placing a receiver at known depths in the borehole and 
shooting a seismic airgun at the surface near the borehole, called 
vertical seismic profiling (VSP). These data provide high-resolution 
images of the geological layers penetrated by the borehole and can be 
used to accurately correlate original surface seismic data. The actual 
size of the airgun array is not determined until the final well depth 
is known, but typical airgun array volumes are between 600 and 880 cui. 
VSP typically takes less than two full days at each well site. 
Illingworth & Rodkin (2014) measured a 720 cui array for Buccaneer in 
2013 and report the source level at 227 dB at 1 m, with underwater 
levels exceeding 160 dB rms threshold at 2.47 km (1.54 mi). The 
measured sound levels for the VSP were used to evaluate potential Level 
A (227 dB rms at 1 m assuming 15 logR transmission loss) and Level B 
(2,470 m distance to the 160 dB threshold) harassment isopleths.
Iniskin Peninsula Exploration
    Hilcorp Alaska initiated baseline exploratory data collection in 
2013 for a proposed land-based oil and gas exploration and development 
project on the Iniskin Peninsula of Alaska, near Chinitna Bay. The 
proposed project is approximately 97 km (60 mi) west of Homer on the 
west side of Cook Inlet in the Fitz Creek drainage. New project 
infrastructure includes material sites, a 6.9 km (4.3 mi) long access 
road, prefabricated bridges to cross four streams, an air strip, barge 
landing/staging areas, fuel storage facilities, water wells and 
extraction sites, an intertidal causeway, a camp/staging area, and a 
drill pad. Construction is anticipated to start in 2020.
    An intertidal rock causeway is proposed to be constructed adjacent 
to the Fitz Creek staging area to improve the accessibility of the 
barge landing during construction and drilling operations. The causeway 
will extend seaward from the high tide line approximately 366 m (1,200 
ft) to a landing area 46 m (150 ft) wide. A dock face will be 
constructed around the rock causeway so that barges will be able to 
dock along the causeway. Rock placement for the causeway is not known 
to generate sound at levels expected to disturb marine mammals. The 
causeway is also not proposed at a known pinniped haulout or other 
biologically significant location for local marine mammals. Therefore, 
rock laying for the causeway is not considered further in this 
document.
    The causeway will need to be 75 percent built before the 
construction of the dock face will start. The dock face will be 
constructed with 18-m (60-ft) tall Z-sheet piles, all installed using a 
vibratory hammer. It will take approximately 14-25 days, depending on 
the length of the work shift, assuming approximately 25 percent of the 
day actual pile driving. The timing of pile driving will be in late 
summer or early winter, after the causeway has been partially 
constructed. Illingworth & Rodkin (2007) compiled measured near-source 
(10 m [32.8 ft]) SPL data from vibratory pile driving for different 
pile sizes ranging in diameter from 30.5 to 243.8 cm (12 to 96 in). For 
this petition, the source level of the 61.0-cm (24-in) AZ steel sheet 
pile from Illingworth & Rodkin (2007) was used for the sheet pile. The 
measured sound levels of 160 dB rms at 10 m assuming 15 logR 
transmission loss for the vibratory sheet pile driving was used to 
evaluate potential Level A and B harassment isopleths.
Activities in Middle Cook Inlet
Offshore Production Platforms
    Of the 17 production platforms in central Cook Inlet, 15 are owned 
by Hilcorp. Hilcorp performs routine construction on their platforms, 
depending on needs of the operations. Construction activities may take 
place up to 24 hrs a day. In-water activities include support vessels 
bringing supplies five days a week up to two trips per day between 
offshore systems at Kenai (OSK) and the platform. Depending on the 
needs, there may also be barges towed by tugs with equipment and 
helicopters for crew and supply changes. Routine supply-related 
transits from vessels and helicopters are not substantially different 
from routine vessel and air traffic already occurring in Cook Inlet, 
and take is not expected to occur from these activities.
Offshore Production Drilling
    Hilcorp routinely conducts development drilling activities at 
offshore platforms on a regular basis to meet the asset's production 
needs. Development drilling activities occurs from existing platforms 
within the Cook Inlet through either open well slots or existing 
wellbores in existing platform legs. Drilling activities from platforms 
within Cook Inlet are accomplished by using conventional drilling 
equipment from a variety of rig configurations.
    Some other platforms in Cook inlet have permanent drilling rigs 
installed that operate under power provided by the platform power 
generation systems, while others do not have drill rigs, and the use of 
a mobile drill rig is required. Mobile offshore drill rigs may be 
powered by the platform power generation (if compatible with the

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platform power system) or self-generate power with the use of diesel 
fired generators. For the reasons outlined above for the Lower Inlet, 
noise from routine drilling is not considered further in this document.
    Helicopter logistics for development drilling programs operations 
will include transportation for personnel and supplies. The helicopter 
support will be managed through existing offshore services based at the 
OSK Heliport to support rig crew changes and cargo handling. Helicopter 
flights to and from the platform while drilling is occurring is 
anticipated to increase (on average) by two flights per day from normal 
platform operations.
    Major supplies will be staged on-shore at the OSK Dock in Nikiski. 
Required supplies and equipment will be moved from the staging area to 
the platform in which drilling occurring by existing supply vessels 
that are currently in use supporting offshore operations within Cook 
Inlet. Vessel trips to and from the platform while drilling is 
occurring is anticipated to increase (on average) by two trips per day 
from normal platform operations. During mobile drill rig mobilization 
and demobilization, one support vessel is used continuously for 
approximately 30 days to facilitate moving rig equipment and materials.
Oil and Gas Pipeline Maintenance
    Each year, Hilcorp Alaska must verify the structural integrity of 
their platforms and pipelines located within Cook Inlet. Routine 
maintenance activities include: subsea pipeline inspections, 
stabilizations, and repairs; platform leg inspections and repairs; and 
anode sled installations and/or replacement. In general, pipeline 
stabilization and pipeline repair are anticipated to occur in 
succession for a total of 6-10 weeks. However, if a pipeline 
stabilization location also requires repair, the divers will repair the 
pipeline at the same time they are stabilizing it. Pipeline repair 
activities are only to be conducted on an as-needed basis whereas 
pipeline stabilization activities will occur annually. During 
underwater inspections, if the divers identify an area of the pipeline 
that requires stabilization, they will place Sea-Crete bags at that 
time rather than waiting until the major pipeline stabilization effort 
that occurs later in the season.
    Natural gas and oil pipelines located on the seafloor of the Cook 
Inlet are inspected on an annual basis using ultrasonic testing (UT), 
cathodic protection surveys, multi-beam sonar surveys, and sub-bottom 
profilers. Deficiencies identified are corrected using pipeline 
stabilization methods or USDOT-approved pipeline repair techniques. The 
Applicant employs dive teams to conduct physical inspections and 
evaluate cathodic protection status and thickness of subsea pipelines 
on an annual basis. If required for accurate measurements, divers may 
use a water jet to provide visual access to the pipeline. For 
stabilization, inspection dive teams may place Sea-Crete bags beneath 
the pipeline to replace any materials removed by the water jet. Results 
of the inspections are recorded and significant deficiencies are noted 
for repair.
    Multi-beam sonar and sub-bottom profilers may also be used to 
obtain images of the seabed along and immediately adjacent to all 
subsea pipelines. Elements of pipeline inspections that could produce 
underwater noise include: the dive support vessel, water jet, multi-
beam sonar/sub-bottom profiler and accompanying vessel.
    A water jet is a zero-thrust water compressor that is used for 
underwater removal of marine growth or rock debris underneath the 
pipeline. The system operates through a mobile pump which draws water 
from the location of the work. Water jets likely to be used in Cook 
Inlet include, but are not limited to, the CaviDyne CaviBlaster[supreg] 
and the Gardner Denver Liqua-Blaster. Noise generated during the use of 
the water jets would be very short in duration (30 minutes or less at 
any given time) and intermittent.
    Hilcorp Alaska conducted underwater measurements during 13 minutes 
of CaviBlaster[supreg] use in Cook Inlet in April 2017 (Austin 2017). 
Received sound levels were measured up to 143 dB re 1 [micro]Pa rms at 
170 m and up to 127 dB re 1 [micro]Pa rms at 1,100 m. Sounds from the 
Caviblaster[supreg] were clearly detectable out to the maximum 
measurement range of 1.1 km. Using the measured transmission loss of 
19.5 log R (Austin 2017), the source level for the Caviblaster[supreg] 
was estimated as 176 dB re 1 [mu]Pa at 1 m. The sounds were broadband 
in nature, concentrated above 500 Hz with a dominant tone near 2 kHz.
    Specifications for the GR 29 Underwater Hydraulic Grinder state 
that the SPL at the operator's position would be 97 dB in air (Stanley 
2014). There are no underwater measurements available for the grinder, 
so using a rough estimate of converting sound level in dB in air to 
water by adding 61.5 dB would result in an underwater level of 
approximately 159 dB2. The measured sound levels for the water jet and 
grinder were used to evaluate potential Level A and B acoustic 
harassment isopleths.
    If necessary, Hilcorp may use an underwater pipe cutter to replace 
existing pipeline segments in Cook Inlet. The following tools are 
likely to be used for pipeline cutting activities:
     A diamond wire saw used for remote cutting underwater 
structures such as pipes and I-Beams. These saws use hydraulic power 
delivered by a dedicated power source. The saw usually uses a method 
that pushes the spinning wire through the pipe.
     A hydraulically-powered Guillotine saw which uses an 
orbital cutting movement similar to traditional power saws.
    Generally, sound radiated from the diamond wire cutter is not 
easily discernible from the background noise during the cutting 
operation. The Navy measured underwater sound levels when the diamond 
saw was cutting caissons for replacing piles at an old fuel pier at 
Naval Base Point Loma (Naval Base Point Loma Naval Facilities 
Engineering Command Southwest 2017). They reported an average SPL for a 
single cutter at 136.1-141.4 dB rms at 10 m.
    Specifications for the Guillotine saw state that the SPL at the 
operator's position would be 86 dB in air (Wachs 2014). There are no 
underwater measurements available for the grinder, so using a rough 
estimate of converting sound level in dB in air to water by adding 61.5 
dB would result in an underwater level of approximately 148 dB.
    Because the measured levels for use of underwater saws do not 
exceed the NMFS criteria, the noise from underwater saws was not 
considered further in this document. Scour spans beneath pipelines 
greater than 23 m (75 ft) have the potential to cause pipeline 
failures. To be conservative, scour spans of 15 m (50 ft) or greater 
identified using multi-beam sonar surveys are investigated using dive 
teams. Divers perform tactile inspections to confirm spans greater than 
15 m (50 ft). The pipeline is stabilized along these spans with Sea-
Crete concrete bags. While in the area, the divers will also inspect 
the external coating of the pipeline and take cathodic protection 
readings if corrosion wrap is found to be absent. Elements of pipeline 
stabilization that could produce underwater noise include: Dive support 
vessel and water jet.
    Significant pipeline deficiencies identified during pipeline 
inspections are repaired as soon as practicable using methods 
including, but not limited to, USDOT-approved clamps and/or fiber glass 
wraps, bolt/flange replacements,

[[Page 12337]]

and manifold replacements. In some cases, a water jet may be required 
to remove sand and gravel from under or around the pipeline to allow 
access for assessment and repair. The pipeline surface may also require 
cleaning using a hydraulic grinder to ensure adequate repair. If 
pipeline replacement is required, an underwater pipe cutter such as a 
diamond wire saw or hydraulically-powered Guillotine saw may be used. 
Elements of pipeline repair that could produce underwater noise 
include: Dive support vessel, water jet, hydraulic grinder, and 
underwater pipe cutter.
Platform Leg Inspection and Repair
    Hilcorp's platforms in Cook Inlet are inspected on a routine basis. 
Divers and certified rope access technicians visually inspect subsea 
platform legs. These teams also identify and correct significant 
structural deficiencies. Platform leg integrity and pipeline-to-
platform connections beneath the water surface are evaluated by divers 
on a routine basis. Platform legs, braces, and pipeline-to-platform 
connections are evaluated for cathodic protection status, structure 
thickness, excessive marine growth, damage, and scour. If required, 
divers may use a water jet to clean or provide access to the structure. 
If necessary, remedial grinding using a hydraulic under water grinder 
may be required to determine extent damage and/or to prevent further 
crack propagation. All inspection results are recorded and significant 
deficiencies are noted for repair. Elements of subsea platform leg 
inspection and repair that could produce underwater noise include: Dive 
support vessel, hydraulic grinder, water jet.
    Platform leg integrity along the tidal zone is inspected on a 
routine basis. Difficult-to-reach areas may be accessed using either 
commercially-piloted unmanned aerial systems (UAS). Commercially-
piloted UASs may be deployed from the top-side of the platform to 
obtain images of the legs. Generally, the UAS is in the air for 15-20 
minutes at a time due to battery capacity, which allows for two legs 
and part of the underside of the platform to be inspected. The total 
time to inspect a platform is approximately 1.5 hrs of flight time. The 
UAS is operated at a distance of up to 30.5 m (100 ft) from the 
platform at an altitude of 9-15 m (30-50 ft) above sea level. To reduce 
potential harassment of marine mammals, the area around the platform 
would be inspected prior to launch of the UAS to ensure there are no 
flights directly above marine mammals. As no flights will be conducted 
directly over marine mammals, the effects of drone use for routine 
maintenance are not considered further in this application.
Anode Sled Installation and Replacement
    Galvanic and impressed current anode sleds are used to provide 
cathodic protection for the pipelines and platforms in Cook Inlet. 
Galvanic anode sleds do not require a power source and may be installed 
along the length of the pipelines on the seafloor. Impressed current 
anode sleds are located on the seafloor at each of the corners of each 
platform and are powered by rectifiers located on the platform. Anodes 
are placed at the seafloor using dive vessels and hand tools. If 
necessary, a water jet may be used to provide access for proper 
installation. Anodes and/or cables may be stabilized using Sea-Crete 
bags.
Pingers
    Several types of moorings are deployed in support of Hilcorp 
operations; all of which require an acoustic pinger for location or 
release. The pinger is deployed over the side of a vessel and a short 
signal is emitted to the mooring device. The mooring device responds 
with a short signal to indicate that the device is working, to indicate 
range and bearing data, or to illicit a release of the unit from the 
anchor. These are used for very short periods of time when needed.
    The types of moorings requiring the use of pingers anticipated to 
be used in the Petition period include acoustic moorings during the 3D 
seismic survey (assumed 2-4 moorings), node placement for the 2D survey 
(used with each node deployment), and potential current profilers 
deployed each season (assumed 2-4 moorings). The total amount of time 
per mooring device is less than 10 minutes during deployment and 
retrieval. To avoid disturbance, the pinger would not be deployed if 
marine mammals have been observed within 135 m (443 ft) of the vessel. 
The short duration of the pinger deployment as well as Hilcorp's 
mitigation suggests take of marine mammals from pinger use is unlikely 
to occur and pingers are not considered further in this analysis.
North Cook Inlet Unit Subsea Well Plugging and Abandonment
    The discovery well in the North Cook Inlet Unit was drilled over 50 
years ago and is planned to be abandoned, so Hilcorp Alaska plans to 
conduct a geohazard survey to locate the well and conduct plugging and 
abandonment (P&A) activities for a previously drilled subsea 
exploration well in 2020. The geohazard survey location is 
approximately 402-804 m (\1/4\-\1/2\ mi) south of the Tyonek platform 
and will take place over approximately seven days with a grid spacing 
of approximately 250 m (820 ft). The suite of equipment used during a 
typical geohazards survey consists of single beam and multi-beam 
echosounders, which provide water depths and seafloor morphology; a 
side scan sonar that provides acoustic images of the seafloor; a sub-
bottom profiler which provides 20 to 200 m (66 to 656 ft) sub-seafloor 
penetration with a 6- to 20-cm (2.4-7.9-in) resolution. The 
echosounders and sub-bottom profilers are generally hull-mounted or 
towed behind a single vessel. The vessel travels at 3-4.5 knots (5.6-
8.3 km/hr).
    After the well has been located, Hilcorp plans to conduct plugging 
and abandonment activities over a 60-90 day time period in May through 
July in 2020. The jack-up rig will be similar to what is described 
above (the Spartan 151 drill rig, or similar). The rig will be towed 
onsite using up to three ocean-going tugs. Once the jack-up rig is on 
location, divers working off a boat will assist in preparing the subsea 
wellhead and mudline hanger for the riser to tie the well to the jack-
up. Once the riser is placed, the BOP equipment is made up to the 
riser. At this point, the well will be entered and well casings will be 
plugged with mechanical devices and cement and then cutoff and pulled. 
A shallow cement plug will be set in the surface casing to 3.05 m (10 
ft) below the mudline hanger. The remaining well casings will be cutoff 
and the mudline hanger will be recovered to the deck of the jack-up rig 
for disposal. The well abandonment will be performed in accordance to 
Alaska Oil and Gas Conservation Commission (AOGCC) regulations.
Trading Bay Exploratory Drilling
    Hilcorp plans to conduct exploratory drilling activities in the 
Trading Bay area. The specific sites of interest have not yet been 
identified, but the general area is shown in Figure 3 in the 
application. Hilcorp will conduct geohazard surveys over the areas of 
interest to locate potential hazards prior to drilling with the same 
suite of equipment as described above for exploratory drilling in the 
lower Inlet. The survey is expected to take place over 30-60 days in 
2019 from a single vessel.
    The exploratory drilling and well completion activities will take 
place in site-specific areas based on the geohazard survey. Hilcorp 
plans to drill 1-2 exploratory wells in this area in the

[[Page 12338]]

open water season of 2020 with the same equipment and methods as 
described above for lower Inlet exploratory drilling. The noise of 
routine drilling is not considered further as explained in the 
description of activities in the Lower Inlet. However, drive pipe 
installation and vertical seismic profiling will be considered further.
    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see Proposed 
Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

    Eleven species of marine mammal have the potential to occur in the 
action area during the five year period of activities proposed by 
Hilcorp. These species are described in further detail below.

Fin Whales

    For management purposes, three stocks of fin whales are currently 
recognized in U.S. Pacific waters: Alaska (Northeast Pacific), 
California/Washington/Oregon, and Hawaii. Recent analyses provide 
evidence that the population structure should be reviewed and possibly 
updated. However, substantially new data on the stock structure is 
lacking (Muto et al. 2017). Fin whales, including the Northeastern 
Pacific stock, are listed as endangered under the ESA.
    Mizroch et al. (2009) provided a comprehensive summary of fin whale 
sightings data, including whaling catch data and determined there could 
be at least six populations of fin whales. Evidence suggests two 
populations are migratory (eastern and western North Pacific) and two 
to four more are year-round residents in peripheral seas such as the 
Gulf of California, East China Sea, Sanriku-Hokkaido, and possibly the 
Sea of Japan. The two migratory stocks are likely mingling in the 
Bering Sea in July and August. Moore et al. (1998, 2006), Watkins et 
al. (2000), and Stafford et al. (2007) documented high rates of calling 
along the Alaska coast beginning in August/September and lasting 
through February. Fin whales are regularly observed in the Gulf of 
Alaska during the summer months, even though calls are seldom detected 
during this period (Stafford et al. 2007). Instruments moored in the 
southeast Bering Sea detected calls over the course of a year and found 
peaks from September to November as well as in February and March 
(Stafford et al. 2010). Delarue et al. (2013) detected calls in the 
northeastern Chukchi Sea from instruments moored from July through 
October from 2007 through 2010.
    Fin whales are found seasonally in the Gulf of Alaska, Bering Sea, 
and as far north as the northern Chukchi Sea (Muto et al. 2017). 
Surveys conducted in coastal waters of the Aleutians and the Alaska 
Peninsula found that fin whales occurred primarily from the Kenai 
Peninsula to the Shumagin Islands and were abundant near the Semidi 
Islands and Kodiak Island (Zerbini et al. 2006). An opportunistic 
survey conducted on the shelf of the Gulf of Alaska found fin whales 
concentrated west of Kodiak Island in Shelikof Strait, and in the 
southern Cook Inlet region. Smaller numbers were also observed over the 
shelf east of Kodiak to Prince William Sound (AFSC, 2003). In the 
northeastern Chukchi Sea, visual sightings and acoustic detections have 
been increasing, which suggests the stock may be re-occupying habitat 
used prior to large-scale commercial whaling (Muto et al. 2017). Most 
of these areas are feeding habitat for fin whales. Fin whales are 
rarely observed in Cook Inlet, and most sightings occur near the 
entrance of the inlet. During the NMFS aerial surveys in Cook Inlet 
from 2000-2016, 10 sightings of 26 estimated individual fin whales in 
lower Cook Inlet were observed (Shelden et al. 2013, 2015, 2016).

Humpback Whales

    Currently, three populations of humpback whales are recognized in 
the North Pacific, migrating between their respective summer/fall 
feeding areas and winter/spring calving and mating areas as follows 
(Baker et al. 1998; Calambokidis et al. 1997). Although there is 
considerable distributional overlap in the humpback whale stocks that 
use Alaska, the whales seasonally found in lower Cook Inlet are 
probably of the Central North Pacific stock (Muto et al. 2017). Listed 
as endangered under the ESA, this stock has recently been estimated at 
7,890 animals (Muto et al. 2017). The Central North Pacific stock 
winters in Hawaii and summers from British Columbia to the Aleutian 
Islands (Calambokidis et al. 1997), including Cook Inlet.
    Humpback whales in the high latitudes of the North Pacific Ocean 
are seasonal migrants that feed on euphausiids and small schooling 
fishes (Muto et al. 2017). During the spring, these animals migrate 
north and spend the summer feeding in the prey-rich sub-polar waters of 
southern Alaska, British Columbia, and the southern Chukchi Sea. 
Individuals from the Western North Pacific (endangered), Hawaii (not 
listed under the ESA), and the Mexico (threatened) DPSs migrate to 
areas near and potentially in the Petition region. However, most of the 
individuals that migrate to the Cook Inlet area are likely from the 
Hawaii DPS and not the Western North Pacific or Mexico DPSs (NMFS 
2017).
    In the summer, humpback whales are regularly present and feeding in 
the Cook Inlet region, including Shelikof Strait, Kodiak Island bays, 
and the Barren Islands, in addition to Gulf of Alaska regions adjacent 
to the southeast side of Kodiak Island (especially Albatross Banks), 
the Kenai and Alaska peninsulas, Elizabeth Island, as well as south of 
the Aleutian Islands. Humpbacks also may be present in some of these 
areas throughout autumn (Muto et al. 2017).
    Humpback whales have been observed during marine mammal surveys 
conducted in Cook Inlet. However, their presence is largely confined to 
lower Cook Inlet. Recent monitoring by Hilcorp in upper Cook Inlet has 
also included sightings of humpbacks near Tyonek. During 
SAExploration's 2015 seismic program, three humpback whales were 
observed in Cook Inlet; two near the Forelands and one in Kachemak Bay 
(Kendall et al. 2015). During NMFS' Cook Inlet beluga whale aerial 
surveys from 2000-2016, there were 88 sightings of 191 estimated 
individual humpback whales in lower Cook Inlet (Shelden et al. 2017). 
They have been regularly seen near Kachemak Bay during the summer 
months (Rugh et al. 2005). There are observations of humpback whales as 
far north as Anchor Point, with recent summer observations extending to 
Cape Starichkof (Owl Ridge 2014). Although several humpback whale 
sightings occurred mid-inlet between Iniskin Peninsula and Kachemak 
Bay, most sightings occurred outside of the Petition region near 
Augustine, Barren, and Elizabeth Islands (Shelden et al. 2013, 2015, 
2017).
    Ferguson et al. (2015) has established Biologically Important Areas 
(BIAs) as part of the NOAA Cetacean Density and Distribution Mapping 
Working Group (CetMap) efforts. This information supplements the 
quantitative information on cetacean density, distribution, and 
occurrence by: (1) Identifying areas where cetacean species or 
populations are known to concentrate for specific behaviors, or be 
range-limited, but for which there is not sufficient data for their 
importance to be reflected in the quantitative mapping effort; and (2) 
providing additional context within which to examine potential 
interactions between cetaceans and human activities. A ``Feeding Area''

[[Page 12339]]

BIA for humpback whales in the Gulf of Alaska region encompasses the 
waters east of Kodiak Island (the Albatross and Portlock Banks), a 
target for historical commercial whalers based out of Port Hobron, 
Alaska (Ferguson et al. 2015; Reeves et al. 1985; Witteveen et al. 
2007). This BIA also includes waters along the southeastern side of 
Shelikof Strait and in the bays along the northwestern shore of Kodiak 
Island. The highest densities of humpback whales around the Kodiak 
Island BIA occur from July-August (Ferguson et al. 2015).

Minke Whale

    Minke whales are most abundant in the Gulf of Alaska during summer 
and occupy localized feeding areas (Zerbini et al. 2006). 
Concentrations of minke whales have occurred along the north coast of 
Kodiak Island (and along the south coast of the Alaska Peninsula 
(Zerbini et al. 2006). The current estimate for minke whales between 
Kenai Fjords and the Aleutian Islands is 1,233 individuals (Zerbini et 
al. 2006). During shipboard surveys conducted in 2003, three minke 
whale sightings were made, all near the eastern extent of the survey 
from nearshore Prince William Sound to the shelf break (NMML 2003).
    Minke whales become scarce in the Gulf of Alaska in fall; most 
whales are thought to leave the region by October (Consiglieri et al. 
1982). Minke whales are migratory in Alaska, but recently have been 
observed off Cape Starichkof and Anchor Point year-round (Muto et al. 
2017). During Cook Inlet-wide aerial surveys conducted from 1993 to 
2004, minke whales were encountered three times (1998, 1999, and 2006), 
both times off Anchor Point 16 miles northwest of Homer (Shelden et al. 
2013, 2015, 2017). A minke whale was also reported off Cape Starichkof 
in 2011 (A. Holmes, pers. comm.) and 2013 (E. Fernandez and C. 
Hesselbach, pers. comm.), suggesting this location is regularly used by 
minke whales, including during the winter. Several minke whales were 
recorded off Cape Starichkof in early summer 2013 during exploratory 
drilling (Owl Ridge 2014), suggesting this location is regularly used 
by minke whales year-round. During Apache's 2014 survey, a total of 2 
minke whale groups (3 individuals) were observed during this time 
period, one sighting to the southeast of Kalgin Island and another 
sighting near Homer (Lomac-MacNair et al. 2014). SAExploration noted 
one minke whale near Tuxedni Bay in 2015 (Kendall et al. 2015). This 
species is unlikely to be seen in upper Cook Inlet but may be 
encountered in the mid and lower Inlet.

Killer Whales

    Two different stocks of killer whales inhabit the Cook Inlet region 
of Alaska: the Alaska Resident Stock and the Gulf of Alaska, Aleutian 
Islands, Bering Sea Transient Stock (Muto et al 2017). Seasonal and 
year-round occurrence has been noted for killer whales throughout 
Alaska (Braham and Dahlheim 1982), where whales have been labeled as 
``resident,'' ``transient,'' and ``offshore'' type killer whales 
(Dahlheim et al. 2008; Ford et al. 2000). The killer whales using Cook 
Inlet are thought to be a mix of resident and transient individuals 
from two different stocks: the Alaska Resident Stock, and the Gulf of 
Alaska, Aleutian Islands, and Bering Sea Transient Stock (Allen and 
Angliss 2015). Although recent studies have documented movements of 
Alaska Resident killer whales from the Bering Sea into the Gulf of 
Alaska as far north as southern Kodiak Island, none of these whales 
have been photographed further north and east in the Gulf of Alaska 
where regular photo-identification studies have been conducted since 
1984 (Muto et al. 2017).
    Killer whales are occasionally observed in lower Cook Inlet, 
especially near Homer and Port Graham (Shelden et al. 2003; Rugh et al. 
2005). The few whales that have been photographically identified in 
lower Cook Inlet belong to resident groups more commonly found in 
nearby Kenai Fjords and Prince William Sound (Shelden et al. 2003). The 
availability of these prey species largely determines the likeliest 
times for killer whales to be in the area. During aerial surveys 
conducted between 1993 and 2004, killer whales were observed on only 
three flights, all in the Kachemak and English Bay area (Rugh et al. 
2005). However, anecdotal reports of killer whales feeding on belugas 
in upper Cook Inlet began increasing in the 1990s, possibly in response 
to declines in sea lion and harbor seal prey elsewhere (Shelden et al. 
2003).
    One killer whale group of two individuals was observed during the 
2015 SAExploration seismic program near the North Foreland (Kendall et 
al. 2015). During NMFS aerial surveys, killer whales were observed in 
1994 (Kamishak Bay), 1997 (Kachemak Bay), 2001 (Port Graham), 2005 
(Iniskin Bay), 2010 (Elizabeth and Augustine Islands), and 2012 
(Kachemak Bay; Shelden et al. 2013). Eleven killer whale strandings 
have been reported in Turnagain Arm, six in May 1991, and five in 
August 1993. This species is expected to be rarely seen in upper Cook 
Inlet but may be encountered in the mid and lower Inlet.

Gray Whales

    Gray whales have been reported feeding near Kodiak Island, in 
southeastern Alaska, and south along the Pacific Northwest (Allen and 
Angliss 2013). Because most gray whales migrating through the Gulf of 
Alaska region are thought to take a coastal route, BIA boundaries for 
the migratory corridor in this region were defined by the extent of the 
continental shelf (Ferguson et al. 2015).
    Most gray whales calve and breed from late December to early 
February in protected waters along the western coast of Baja 
California, Mexico. In spring, the ENP stock of gray whales migrates 
approximately 8,000 km (5,000 mi) to feeding grounds in the Bering and 
Chukchi seas before returning to their wintering areas in the fall 
(Rice and Wolman 1971). Northward migration, primarily of individuals 
without calves, begins in February; some cow/calf pairs delay their 
departure from the calving area until well into April (Jones and Swartz 
1984).
    Gray whales approach the proposed action area in late March, April, 
May, and June, and leave again in November and December (Consiglieri et 
al. 1982; Rice and Wolman 1971) but migrate past the mouth of Cook 
Inlet to and from northern feeding grounds. Some gray whales do not 
migrate completely from Baja to the Chukchi Sea but instead feed in 
select coastal areas in the Pacific Northwest, including lower Cook 
Inlet (Moore et al. 2007). Most of the population follows the outer 
coast of the Kodiak Archipelago from the Kenai Peninsula in spring or 
the Alaska Peninsula in fall (Consiglieri et al. 1982; Rice and Wolman 
1971). Though most gray whales migrate past Cook Inlet, small numbers 
have been noted by fishers near Kachemak Bay, and north of Anchor Point 
(BOEM 2015). During the NMFS aerial surveys, gray whales were observed 
in the month of June in 1994, 2000, 2001, 2005 and 2009 on the east 
side of Cook Inlet near Port Graham and Elizabeth Island but also on 
the west side near Kamishak Bay (Shelden et al. 2013). One gray whale 
was sighted as far north at the Beluga River. Additionally, summering 
gray whales were seen offshore of Cape Starichkof by marine mammal 
observers monitoring Buccaneer's Cosmopolitan drilling program in 2013 
(Owl Ridge 2014). During Apache's 2012 seismic program, nine gray 
whales were observed in June and July (Lomac-MacNair et al. 2013). 
During Apache's seismic program in 2014, one gray whale was observed 
(Lomac- MacNair et al. 2014). During SAExploration's seismic survey in 
2015,

[[Page 12340]]

no gray whales were observed (Kendall et al. 2015). This species is 
unlikely to be seen in upper Cook Inlet but may be encountered in the 
mid and lower Inlet.

Cook Inlet Beluga Whales

    The Cook Inlet beluga whale DPS is a small geographically isolated 
population that is separated from other beluga populations by the 
Alaska Peninsula. The population is genetically distinct from other 
Alaska populations suggesting the peninsula is an effective barrier to 
genetic exchange (O'Corry-Crowe et al. 1997). The Cook Inlet beluga 
whale population is estimated to have declined from 1,300 animals in 
the 1970s (Calkins 1989) to about 340 animals in 2014 (Shelden et al. 
2015). The precipitous decline documented in the mid-1990s was 
attributed to unsustainable subsistence practices by Alaska Native 
hunters (harvest of >50 whales per year) (Mahoney and Shelden 2000). In 
2006, a moratorium to cease hunting was agreed upon to protect the 
species. In April 2011, NMFS designated critical habitat for the beluga 
under the ESA (76 FR 20180) as shown on Figure 13 of the application. 
NMFS finalized the Conservation Plan for the Cook Inlet beluga in 2008 
(NMFS 2008a). NMFS finalized the Recovery Plan for Cook Inlet beluga 
whales in 2016 (NMFS 2016a).
    The Cook Inlet beluga stock remains within Cook Inlet throughout 
the year (Goetz et al. 2012a). Two areas, consisting of 7,809 km\2\ 
(3,016 mi\2\) of marine and estuarine environments considered essential 
for the species' survival and recovery were designated critical 
habitat. However, in recent years the range of the beluga whale has 
contracted to the upper reaches of Cook Inlet because of the decline in 
the population (Rugh et al. 2010). Area 1 of the Cook Inlet beluga 
whale critical habitat encompasses all marine waters of Cook Inlet 
north of a line connecting Point Possession (61.04[deg] N, 150.37[deg] 
W) and the mouth of Three Mile Creek (61.08.55[deg] N, 151.04.40[deg] 
W), including waters of the Susitna, Little Susitna, and Chickaloon 
Rivers below mean higher high water (MHHW). This area provides 
important habitat during ice-free months and is used intensively by 
Cook Inlet beluga between April and November (NMFS 2016a).
    Since 1993, NMFS has conducted annual aerial surveys in June, July 
or August to document the distribution and abundance of beluga whales 
in Cook Inlet. The collective survey results show that beluga whales 
have been consistently found near or in river mouths along the northern 
shores of upper Cook Inlet (i.e., north of East and West Foreland). In 
particular, beluga whale groups are seen in the Susitna River Delta, 
Knik Arm, and along the shores of Chickaloon Bay. Small groups had also 
been recorded seen farther south in Kachemak Bay, Redoubt Bay (Big 
River), and Trading Bay (McArthur River) prior to 1996 but very rarely 
thereafter. Since the mid-1990s, most (96 to 100 percent) beluga whales 
in upper Cook Inlet have been concentrated in shallow areas near river 
mouths, no longer occurring in the central or southern portions of Cook 
Inlet (Hobbs et al. 2008). Based on these aerial surveys, the 
concentration of beluga whales in the northernmost portion of Cook 
Inlet appears to be consistent from June to October (Rugh et al. 2000, 
2004a, 2005, 2006, 2007).
    Though Cook Inlet beluga whales can be found throughout the inlet 
at any time of year, they spend the ice-free months generally in the 
upper Cook Inlet, shifting into the middle and lower Inlet in winter 
(Hobbs et al. 2005). In 1999, one beluga whale was tagged with a 
satellite transmitter, and its movements were recorded from June 
through September of that year. Since 1999, 18 beluga whales in upper 
Cook Inlet have been captured and fitted with satellite tags to provide 
information on their movements during late summer, fall, winter, and 
spring. Using location data from satellite-tagged Cook Inlet belugas, 
Ezer et al. (2013) found most tagged whales were in the lower to middle 
inlet (70 to 100 percent of tagged whales) during January through 
March, near the Susitna River Delta from April to July (60 to 90 
percent of tagged whales) and in the Knik and Turnagain Arms from 
August to December.
    During the spring and summer, beluga whales are generally 
concentrated near the warmer waters of river mouths where prey 
availability is high and predator occurrence is low (Moore et al. 
2000). Beluga whales in Cook Inlet are believed to mostly calve between 
mid-May and mid-July, and concurrently breed between late spring and 
early summer (NMFS 2016a), primarily in upper Cook Inlet. Movement was 
correlated with the peak discharge of seven major rivers emptying into 
Cook Inlet. Boat-based surveys from 2005 to the present (McGuire and 
Stephens 2017), and initial results from passive acoustic monitoring 
across the entire inlet (Castellote et al. 2016) also support seasonal 
patterns observed with other methods. Other surveys also confirm Cook 
Inlet belugas near the Kenai River during summer months (McGuire and 
Stephens 2017).
    During the summer and fall, beluga whales are concentrated near the 
Susitna River mouth, Knik Arm, Turnagain Arm, and Chickaloon Bay 
(Nemeth et al. 2007) where they feed on migrating eulachon 
(Thaleichthys pacificus) and salmon (Onchorhyncus spp.) (Moore et al. 
2000). Data from tagged whales (14 tags between July and March 2000 
through 2003) show beluga whales use upper Cook Inlet intensively 
between summer and late autumn (Hobbs et al. 2005). Critical Habitat 
Area 1 reflects this summer distribution.
    As late as October, beluga whales tagged with satellite 
transmitters continued to use Knik Arm and Turnagain Arm and Chickaloon 
Bay, but some ranged into lower Cook Inlet south to Chinitna Bay, 
Tuxedni Bay, and Trading Bay (McArthur River) in the fall (Hobbs et al. 
2005). Data from NMFS aerial surveys, opportunistic sighting reports, 
and satellite-tagged beluga whales confirm they are more widely 
dispersed throughout Cook Inlet during the winter months (November-
April), with animals found between Kalgin Island and Point Possession. 
In November, beluga whales moved between Knik Arm, Turnagain Arm, and 
Chickaloon Bay, similar to patterns observed in September (Hobbs et al. 
2005). By December, beluga whales were distributed throughout the upper 
to mid-inlet. From January into March, they moved as far south as 
Kalgin Island and slightly beyond in central offshore waters. Beluga 
whales also made occasional excursions into Knik Arm and Turnagain Arm 
in February and March despite ice cover greater than 90 percent (Hobbs 
et al. 2005).
    During Apache's seismic test program in 2011 along the west coast 
of Redoubt Bay, lower Cook Inlet, a total of 33 beluga whales were 
sighted during the survey (Lomac-MacNair et al. 2013). During Apache's 
2012 seismic program in mid-inlet, a total of 151 sightings of 
approximately 1,463 estimated individual beluga whales were observed 
(Lomac-MacNair et al. 2013). During SAExploration's 2015 seismic 
program, a total of eight sightings of approximately 33 estimated 
individual beluga whales were visually observed during this time period 
and there were two acoustic detections of beluga whales (Kendall et al. 
2015). Hilcorp recently reported 143 sightings of beluga whales while 
conducting pipeline work near Ladd Landing in upper Cook Inlet, which 
is not near the area that seismic surveys are proposed but near some 
potential well sites.
    Ferguson et al. (2015) delineated one ``Small'' and ``Resident'' 
BIA for Cook Inlet beluga whales. Small and Resident BIAs are defined 
as ``areas and time within which small and resident

[[Page 12341]]

populations occupy a limited geographic extent'' (Ferguson et al. 
2015). The Cook Inlet beluga whale BIA was delineated using the habitat 
model results of Goetz et al. 2012 and the critical habitat boundaries 
(76 FR 20180).

Harbor Porpoise

    In Alaskan waters, three stocks of harbor porpoises are currently 
recognized for management purposes: Southeast Alaska, Gulf of Alaska, 
and Bering Sea Stocks (Muto et al. 2017). Porpoises found in Cook Inlet 
belong to the Gulf of Alaska Stock which is distributed from Cape 
Suckling to Unimak Pass and most recently was estimated to number 
31,046 individuals (Muto et al. 2017). They are one of the three marine 
mammals (the other two being belugas and harbor seals) regularly seen 
throughout Cook Inlet (Nemeth et al. 2007), especially during spring 
eulachon and summer salmon runs.
    Harbor porpoises primarily frequent the coastal waters of the Gulf 
of Alaska and Southeast Alaska (Dahlheim et al. 2000, 2008), typically 
occurring in waters less than 100 m deep (Hobbs and Waite 2010). The 
range of the Gulf of Alaska stock includes the entire Cook Inlet, 
Shelikof Strait, and the Gulf of Alaska. Harbor porpoises have been 
reported in lower Cook Inlet from Cape Douglas to the West Foreland, 
Kachemak Bay, and offshore (Rugh et al. 2005a). Although they have been 
frequently observed during aerial surveys in Cook Inlet (Shelden et al. 
2014), most sightings are of single animals, and are concentrated at 
Chinitna and Tuxedni bays on the west side of lower Cook Inlet (Rugh et 
al. 2005) and in the upper inlet. The occurrence of larger numbers of 
porpoise in the lower Cook Inlet may be driven by greater availability 
of preferred prey and possibly less competition with beluga whales, as 
belugas move into upper inlet waters to forage on Pacific salmon during 
the summer months (Shelden et al. 2014).
    The harbor porpoise frequently has been observed during summer 
aerial surveys of Cook Inlet, with most sightings of individuals 
concentrated at Chinitna and Tuxedni Bays on the west side of lower 
Cook Inlet (Figure 14 of the application; Rugh et al. 2005). Mating 
probably occurs from June or July to October, with peak calving in May 
and June (as cited in Consiglieri et al. 1982). Small numbers of harbor 
porpoises have been consistently reported in the upper Cook Inlet 
between April and October, except for a recent survey that recorded 
higher numbers than typical. NMFS aerial surveys have identified many 
harbor porpoise sightings throughout Cook Inlet.
    During Apache's 2012 seismic program, 137 sightings (190 
individuals) were observed between May and August (Lomac-MacNair et al. 
2013). Lomac-MacNair et al. 2014 identified 77 groups of harbor 
porpoise totaling 13 individuals during Apache's 2014 seismic survey, 
both from vessels and aircraft, during the month of May. During 
SAExploration's 2015 seismic survey, 52 sightings (65 individuals) were 
observed north of the Forelands (Kendall et al. 2015).
    Recent passive acoustic research in Cook Inlet by Alaska Department 
of Fish and Game (ADF&G) and the Marine Mammal Laboratory (MML) have 
indicated that harbor porpoises occur more frequently than expected, 
particularly in the West Foreland area in the spring (Castellote et al. 
2016), although overall numbers are still unknown at this time.

Dall's Porpoise

    Dall's porpoises are widely distributed throughout the North 
Pacific Ocean including preferring deep offshore and shelf-slopes, and 
deep oceanic waters (Muto et al. 2017). The Dall's porpoise range in 
Alaska extends into the southern portion of the Petition region (Figure 
14 of the application). Dall's porpoises are present year-round 
throughout their entire range in the northeast including the Gulf of 
Alaska, and occasionally the Cook Inlet area (Morejohn 1979). This 
porpoise also has been observed in lower Cook Inlet, around Kachemak 
Bay, and rarely near Anchor Point (Owl Ridge 2014; BOEM 2015).
    Throughout most of the eastern North Pacific they are present 
during all months of the year, although there may be seasonal onshore-
offshore movements along the west coast of the continental United 
States and winter movements of populations out of areas with ice such 
as Prince William Sound (Muto et al. 2017). Dall's porpoises were 
observed (2 groups, 3 individuals) during Apache's 2014 seismic survey 
which occurred in the summer months (Lomac-MacNair et al. 2014). Dall's 
porpoises were observed during the month of June in 1997 (Iniskin Bay), 
199 (Barren Island), and 2000 (Elizabeth Island, Kamishak Bay and 
Barren Island) (Shelden et al. 2013). Dall's porpoises have been 
observed in lower Cook Inlet, including Kachemak Bay and near Anchor 
Point (Owl Ridge 2014). One Dall's porpoise was observed in August 
north of Nikiski in the middle of the Inlet during SAExploration's 2015 
seismic program (Kendall et al. 2015).

Harbor Seal

    Harbor seals occupy a wide variety of habitats in freshwater and 
saltwater in protected and exposed coastlines and range from Baja 
California north along the west coasts of Washington, Oregon, and 
California, British Columbia, and Southeast Alaska; west through the 
Gulf of Alaska, Prince William Sound, and the Aleutian Islands; and 
north in the Bering Sea to Cape Newenham and the Pribilof Islands. 
Harbor seals are found throughout the entire lower Cook Inlet 
coastline, hauling out on beaches, islands, mudflats, and at the mouths 
of rivers where they whelp and feed (Muto et al. 2017).
    The major haul out sites for harbor seals are located in lower Cook 
Inlet. The presence of harbor seals in upper Cook Inlet is seasonal. In 
Cook Inlet, seal use of western habitats is greater than use of the 
eastern coastline (Boveng et al. 2012). NMFS has documented a strong 
seasonal pattern of more coastal and restricted spatial use during the 
spring and summer for breeding, pupping, and molting, and more wide- 
ranging seal movements within and outside of Cook Inlet during the 
winter months (Boveng et al. 2012). Large-scale patterns indicate a 
portion of harbor seals captured in Cook Inlet move out of the area in 
the fall, and into habitats within Shelikof Strait, Northern Kodiak 
Island, and coastal habitats of the Alaska Peninsula, and are most 
concentrated in Kachemak Bay, across Cook Inlet toward Iniskin and 
Iliamna Bays, and south through the Kamishak Bay, Cape Douglas and 
Shelikof Strait regions (Boveng et al. 2012).
    A portion of the Cook Inlet seals move into the Gulf of Alaska and 
Shelikof Strait during the winter months (London et al. 2012). Seals 
move back into Cook Inlet as the breeding season approaches and their 
spatial use is more concentrated around haul-out areas (Boveng et al. 
2012; London et al. 2012). Some seals expand their use of the northern 
portion of Cook Inlet. However, in general, seals that were captured 
and tracked in the southern portion of Cook Inlet remained south of the 
Forelands (Boveng et al. 2012). Important harbor seal haul-out areas 
occur within Kamishak and Kachemak Bays and along the coast of the 
Kodiak Archipelago and the Alaska Peninsula. Chinitna Bay, Clearwater 
and Chinitna Creeks, Tuxedni Bay, Kamishak Bay, Oil Bay, Pomeroy and 
Iniskin Islands, and Augustine Island are also important spring- summer 
breeding and molting areas and known haul-outs sites (Figure

[[Page 12342]]

15 of the application). Small-scale patterns of movement within Cook 
Inlet also occur (Boveng et al. 2012). Montgomery et al. (2007) 
recorded over 200 haul out sites in lower Cook Inlet alone. However, 
only a few dozen to a couple hundred seals seasonally occur in upper 
Cook Inlet (Rugh et al. 2005), mostly at the mouth of the Susitna River 
where their numbers vary in concert with the spring eulachon and summer 
salmon runs (Nemeth et al. 2007; Boveng et al. 2012).
    The Cook Inlet/Shelikof Stock is distributed from Anchorage into 
lower Cook Inlet during summer and from lower Cook Inlet through 
Shelikof Strait to Unimak Pass during winter (Boveng et al. 2012). 
Large numbers concentrate at the river mouths and embayments of lower 
Cook Inlet, including the Fox River mouth in Kachemak Bay, and several 
haul outs have been identified on the southern end of Kalgin Island in 
lower Cook Inlet (Rugh et al. 2005; Boveng et al. 2012). Montgomery et 
al. (2007) recorded over 200 haul-out sites in lower Cook Inlet alone. 
During Apache's 2012 seismic program, harbor seals were observed in the 
project area from early May until the end of the seismic operations in 
late September (Lomac-MacNair et al. 2013). Also in 2012, up to 100 
harbor seals were observed hauled out at the mouths of the Theodore and 
Lewis rivers during monitoring activity associated with Apache's 2012 
Cook Inlet seismic program. During Apache's 2014 seismic program, 492 
groups of harbor seals (613 individuals) were observed. This was the 
highest sighting rate of any marine mammal observed during the summer 
of 2014 (Lomac-MacNair et al. 2014). During SAExploration's 2015 
seismic survey, 823 sightings (1,680 individuals) were observed north 
and between the Forelands (Kendall et al. 2015).

Steller Sea Lions

    The western DPS (WDPS) stock of Steller sea lions most likely 
occurs in Cook Inlet (78 FR 66139). The center of abundance for the 
Western DPS is considered to extend from Kenai to Kiska Island (NMFS 
2008b). The WDPS of the Steller sea lion is defined as all populations 
west of longitude 144[deg] W to the western end of the Aleutian 
Islands. The range of the WDPS includes 38 rookeries and hundreds of 
haul out sites. The Hilcorp action area only considers the WDPS stock. 
The most recent comprehensive aerial photographic and land-based 
surveys of WDPS Steller sea lions in Alaska were conducted during the 
2014 and 2015 breeding seasons (Fritz et al. 2015).
    The WDPS of Steller sea lions is currently listed as endangered 
under the ESA (55 FR 49204) and designated as depleted under the MMPA. 
Critical habitat was designated on August 27, 1993 (58 FR 45269) south 
of the proposed project area in the Cook Inlet region (Figure 16 of the 
application). The critical habitat designation for the WDPS of Steller 
sea lions was determined to include a 37 km (20 nm) buffer around all 
major haul outs and rookeries, and associated terrestrial, atmospheric, 
and aquatic zones, plus three large offshore foraging areas (Figure 16 
of the application). NMFS also designated no entry zones around 
rookeries (50 CFR 223.202). Designated critical habitat is located 
outside Cook Inlet at Gore Point, Elizabeth Island, Perl Island, and 
Chugach Island (NMFS 2008b).
    The geographic center of Steller sea lion distribution is the 
Aleutian Islands and the Gulf of Alaska, although as the WDPS has 
declined, rookeries in the west became progressively smaller (NMFS 
2008b). Steller sea lion habitat includes terrestrial sites for 
breeding and pupping (rookeries), resting (haul outs), and marine 
foraging areas. Nearly all rookeries are at sites inaccessible to 
terrestrial predators on remote rocks, islands, and reefs. Steller sea 
lions inhabit lower Cook Inlet, especially near Shaw Island and 
Elizabeth Island (Nagahut Rocks) haul out sites (Rugh et al. 2005) but 
are rarely seen in upper Cook Inlet (Nemeth et al. 2007). Steller sea 
lions occur in Cook Inlet but south of Anchor Point around the offshore 
islands and along the west coast of the upper inlet in the bays 
(Chinitna Bay, Iniskin Bay, etc.) (Rugh et al. 2005). Portions of the 
southern reaches of the lower inlet are designated as critical habitat, 
including a 20-nm buffer around all major haulout sites and rookeries. 
Rookeries and haul out sites in lower Cook Inlet include those near the 
mouth of the inlet, which are far south of the project area.
    Steller sea lions feed largely on walleye pollock, salmon, and 
arrowtooth flounder during the summer, and walleye pollock and Pacific 
cod during the winter (Sinclair and Zeppelin 2002). Except for salmon, 
none of these are found in abundance in upper Cook Inlet (Nemeth et al. 
2007).
    Steller sea lions can travel considerable distances (Baba et al. 
2000). Steller sea lions are not known to migrate annually, but 
individuals may widely disperse outside of the breeding season (late 
May to early July; Jemison et al. 2013; Allen and Angliss 2014). Most 
adult Steller sea lions inhabit rookeries during the breeding season 
(late May to early July). Some juveniles and non-breeding adults occur 
at or near rookeries during the breeding season, but most are on haul 
outs. Adult males may disperse widely after the breeding season and, 
during fall and winter, many sea lions increase use of haul outs, 
especially terrestrial sites but also on sea ice in the Bering Sea 
(NMFS 2008b).
    Steller sea lions have been observed during marine mammal surveys 
conducted in Cook Inlet. In 2012, during Apache's 3D Seismic surveys, 
there were three sightings of approximately four individuals in upper 
Cook Inlet (Lomac-MacNair et al. 2013). Marine mammal observers 
associated with Buccaneer's drilling project off Cape Starichkof 
observed seven Steller sea lions during the summer of 2013 (Owl Ridge 
2014). During SAExploration's 3D Seismic Program in 2015, four Steller 
sea lions were observed in Cook Inlet. One sighting occurred between 
the West and East Forelands, one near Nikiski and one northeast of the 
North Foreland in the center of Cook Inlet (Kendall et al. 2015). 
During NMFS Cook Inlet beluga whale aerial surveys from 2000-2016, 
there were 39 sightings of 769 estimated individual Steller sea lions 
in lower Cook Inlet (Shelden et al. 2017). Sightings of large 
congregations of Steller sea lions during NMFS aerial surveys occurred 
outside the Petition region, on land in the mouth of Cook Inlet (e.g., 
Elizabeth and Shaw Islands).

California Sea Lions

    There is limited information on the presence of California sea 
lions in Alaska. From 1973 to 2003, a total of 52 California sea lions 
were reported in Alaska, with sightings increasing in the later years. 
Most sightings occurred in the spring; however, they have been observed 
during all seasons. California sea lion presence in Alaska was 
correlated with increasing population numbers within their southern 
breeding range (Maniscalco et al. 2004).
    There have been relatively few California sea lions observed in 
Alaska, most are often alone or occasionally in small groups of two or 
more and usually associated with Steller sea lions at their haulouts 
and rookeries (Maniscalco et al. 2004). California sea lions are not 
typically observed farther north than southeast Alaska, and sightings 
are very rare in Cook Inlet. California sea lions have not been 
observed during the annual NMFS aerial surveys in Cook Inlet. However, 
a sighting of two California sea lions was documented during the Apache 
2012 seismic survey (Lomac-MacNair et al. 2013). Additionally, NMFS' 
anecdotal sighting

[[Page 12343]]

database has four sightings in Seward and Kachemak Bay.
    The California sea lion breeds from the southern Baja Peninsula 
north to A[ntilde]o Nuevo Island, California. Breeding season lasts 
from May to August, and most pups are born from May through July. Their 
nonbreeding range extends northward into British Columbia and 
occasionally farther north into Alaskan waters. California sea lions 
have been observed in Alaska during all four seasons; however, most of 
the sightings have occurred during the spring (Maniscalco et al. 2004).
    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's Stock Assessment Reports (SAR; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region), and more general information about 
these species (e.g., physical and behavioral descriptions) may be found 
on NMFS' website (https://www.fisheries.noaa.gov/species-directory/).
    Table 2 lists all species with expected potential for occurrence in 
Cook Inlet 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). While no mortality is anticipated or authorized here, PBR and 
annual serious injury and mortality from anthropogenic sources are 
included here as gross indicators of the status of the species and 
other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS' 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' 2017 U.S. Alaska and Pacific SARs (Muto et al, 2017; Carretta et 
al, 2017). All values presented in Table 2 are the most recent 
available at the time of publication and are available in the 2017 SARs 
and draft 2018 SARs (available online at: https://www.fisheries.noaa.gov/action/2018-draft-marine-mammal-stock-assessment-reports-available).

                                           Table 2--Species With the Potential To Occur in Cook Inlet, Alaska
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                             Stock abundance (CV,
             Common name                  Scientific name               Stock            ESA/ MMPA status;     Nmin, most recent       PBR     Annual M/
                                                                                        Strategic (Y/N)\1\   abundance survey) \2\               SI \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Eschrichtiidae:
    Gray whale......................  Eschrichtius robustus..  Eastern Pacific........  -/-; N              20,990 (0.05, 20,125,         624       4.25
                                                                                                             2011).
Family Balaenopteridae (rorquals):
    Fin whale.......................  Balaenoptera physalus..  Northeastern Pacific...  E/D; Y              3,168 (0.26,2,554             5.1        0.4
                                                                                                             2013).
    Minke whale.....................  Balaenoptera             Alaska.................  -/-; N              N/A...................        N/A          0
                                       acutorostrata.
    Humpback whale..................  Megaptera novaeangliae.  Western North Pacific..  E/D; Y              1,107 (0.3, 865, 2006)          3        3.2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Beluga whale....................  Delphinapterus leucas..  Cook Inlet.............  E/D; Y              312 (0.1, 287, 2014)..       0.54       0.57
    Killer whale....................  Orcinus orca...........  Alaska Resident........  -/-; N              2,347 (N/A, 2,347,             24          1
                                                                                                             2012).
                                                               Alaska Transient.......  -/-; N              587 (N/A, 587, 2012)..        5.9          1
Family Phocoenidae (porpoises):
    Harbor porpoise.................  Phocoena phocoena......  Gulf of Alaska.........  -/-; Y              31,046 (0.214, N/A,         Undet         72
                                                                                                             1998).
    Dall's porpoise.................  Phocoenoides dalli.....  Alaska.................  -/-; N              83,400 (0.097, N/A,         Undet         38
                                                                                                             1993).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
 sea lions):
    Steller sea lion................  Eumetopias jubatus.....  Western................  E/D; Y              53,303 (N/A, 53,303,          320        241
                                                                                                             2016).
    California sea lion.............  Zalophus californianus.  U.S....................  -/-; N              296,750 (153,337, N/A,      9,200        331
                                                                                                             2011).
Family Phocidae (earless seals):
    Harbor seal.....................  Phoca vitulina.........  Cook Inlet/Shelikof....  -/-; N              27,386 (25,651, N/A,          770        234
                                                                                                             2011).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: www.nmfs.noaa.gov/pr/sars/. CV is coefficient of variation; Nmin is the minimum estimate of
  stock abundance. In some cases, CV is not applicable [explain if this is the case]
\3\ These values, found in NMFS' SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial
  fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV associated
  with estimated mortality due to commercial fisheries is presented in some cases.
Note: Italicized species are not expected to be taken or proposed for authorization.

    All species that could potentially occur in the proposed survey 
areas are included in Table 2. As described below, all 11 species (with 
12 managed stocks) temporally and spatially co-occur with the activity 
to the degree that

[[Page 12344]]

take is reasonably likely to occur, and we have proposed authorizing 
it.
    In addition, sea otters may be found in Cook Inlet. However, sea 
otters are managed by the U.S. Fish and Wildlife Service and are not 
considered further in this document.

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) 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 (2018) 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 the exception 
for lower limits for low-frequency cetaceans where the lower bound 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 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): generalized 
hearing is estimated to occur between approximately 50 Hz to 86 kHz; 
and
     Pinnipeds in water; Otariidae (eared seals): generalized 
hearing is estimated to occur between 60 Hz and 39 kHz.
    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information. 
Eleven marine mammal species (eight cetacean and three pinniped (two 
otariid and one phocid) species) have the reasonable potential to co-
occur with the proposed survey activities. Please refer to Table 2. Of 
the cetacean species that may be present, four are classified as low-
frequency cetaceans (i.e., all mysticete species), two are classified 
as mid-frequency cetaceans (i.e., all delphinid and ziphiid species and 
the sperm whale), and two are classified as high-frequency cetaceans 
(i.e., harbor porpoise and Kogia spp.).

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section includes a summary and discussion of the ways that 
components of the specified activity may impact marine mammals and 
their habitat. The Estimated Take by Incidental Harassment section 
later in this document includes a quantitative analysis of the number 
of individuals that are expected to be taken by this activity. The 
Negligible Impact Analysis and Determination section considers the 
content of this section, the Estimated Take by Incidental Harassment 
section, and the Proposed Mitigation section, to draw conclusions 
regarding the likely impacts of these activities on the reproductive 
success or survivorship of individuals and how those impacts on 
individuals are likely to impact marine mammal species or stocks.

Description of Active Acoustic Sound Sources

    This section contains a brief technical background on sound, the 
characteristics of certain sound types, and on metrics used in this 
proposal in as much 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.
    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per unit of time and 
is measured in Hz or cycles per second. Wavelength is the distance 
between two peaks or corresponding points of a sound wave (length of 
one cycle). Higher frequency sounds have shorter wavelengths than lower 
frequency sounds, and typically attenuate (decrease) more rapidly, 
except in certain cases in shallower water. Amplitude is the height of 
the sound pressure wave or the ``loudness'' of a sound and is typically 
described using the relative unit of the dB. A sound pressure level 
(SPL) in dB is described as the ratio between a measured pressure and a 
reference pressure (for underwater sound, this is 1 microPascal 
([mu]Pa)) and is a logarithmic unit that accounts for large variations 
in amplitude; therefore, a relatively small change in dB corresponds to 
large changes in sound pressure. The source level (SL) represents the 
SPL referenced at a distance of 1 m from the source (referenced to 1 
[mu]Pa) while the received level is the SPL at the listener's position 
(referenced to 1 [mu]Pa).
    Root mean square (rms) is the quadratic mean sound pressure over 
the duration of an impulse. Root mean square is calculated by squaring 
all of the sound amplitudes, averaging the squares, and then taking the 
square root of the average (Urick, 1983). Root mean square accounts for 
both positive and negative values; squaring the pressures makes all 
values positive so that they may be accounted for in the summation of 
pressure levels (Hastings and Popper, 2005). This measurement is often 
used in the context of discussing behavioral effects, in part because 
behavioral effects, which often result from auditory cues, may be 
better expressed through averaged units than by peak pressures.
    Sound exposure level (SEL; represented as dB re 1 [mu]Pa2-s) 
represents the total energy contained within a pulse and considers both 
intensity and duration of exposure. Peak sound pressure (also referred 
to as zero-to-peak sound pressure or 0-p) is the maximum instantaneous 
sound pressure measurable in the water at a specified distance from the 
source and is represented in the same units as the rms sound pressure. 
Another common metric is peak-to-peak sound pressure (pk-pk), which is 
the algebraic difference between the peak positive and peak negative 
sound pressures.

[[Page 12345]]

Peak-to-peak pressure is typically approximately 6 dB higher than peak 
pressure (Southall et al., 2007).
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as the sound wave travels. Underwater sound waves radiate in a 
manner similar to ripples on the surface of a pond and may be either 
directed in a beam or beams or may radiate in all directions 
(omnidirectional sources), as is the case for pulses produced by the 
airgun arrays considered here. The compressions and decompressions 
associated with sound waves are detected as changes in pressure by 
aquatic life and man-made sound receptors such as hydrophones.
    Even in the absence of sound from the specified activity, the 
underwater environment is typically loud due to ambient sound. Ambient 
sound is defined as environmental background sound levels lacking a 
single source or point (Richardson et al., 1995), and the sound level 
of a region is defined by the total acoustical energy being generated 
by known and unknown sources. These sources may include physical (e.g., 
wind and waves, earthquakes, ice, atmospheric sound), biological (e.g., 
sounds produced by marine mammals, fish, and invertebrates), and 
anthropogenic (e.g., vessels, dredging, construction) sound. A number 
of sources contribute to ambient sound, including the following 
(Richardson et al., 1995):
     Wind and waves: The complex interactions between wind and 
water surface, including processes such as breaking waves and wave-
induced bubble oscillations and cavitation, are a main source of 
naturally occurring ambient sound for frequencies between 200 Hz and 50 
kilohertz (kHz) (Mitson, 1995). In general, ambient sound levels tend 
to increase with increasing wind speed and wave height. Surf sound 
becomes important near shore, with measurements collected at a distance 
of 8.5 km from shore showing an increase of 10 dB in the 100 to 700 Hz 
band during heavy surf conditions;
     Precipitation: Sound from rain and hail impacting the 
water surface can become an important component of total sound at 
frequencies above 500 Hz, and possibly down to 100 Hz during quiet 
times;
     Biological: Marine mammals can contribute significantly to 
ambient sound levels, as can some fish and snapping shrimp. The 
frequency band for biological contributions is from approximately 12 Hz 
to over 100 kHz; and
     Anthropogenic: Sources of ambient sound related to human 
activity include transportation (surface vessels), dredging and 
construction, oil and gas drilling and production, seismic surveys, 
sonar, explosions, and ocean acoustic studies. Vessel noise typically 
dominates the total ambient sound for frequencies between 20 and 300 
Hz. In general, the frequencies of anthropogenic sounds are below 1 kHz 
and, if higher frequency sound levels are created, they attenuate 
rapidly. Sound from identifiable anthropogenic sources other than the 
activity of interest (e.g., a passing vessel) is sometimes termed 
background sound, as opposed to ambient sound.
    The sum of the various natural and anthropogenic sound sources at 
any given location and time--which comprise ``ambient'' or 
``background'' sound--depends not only on the source levels (as 
determined by current weather conditions and levels of biological and 
human activity) but also on the ability of sound to propagate through 
the environment. In turn, sound propagation is dependent on the 
spatially and temporally varying properties of the water column and sea 
floor and is frequency-dependent. As a result of the dependence on a 
large number of varying factors, ambient sound levels can be expected 
to vary widely over both coarse and fine spatial and temporal scales. 
Sound levels at a given frequency and location can vary by 10-20 dB 
from day to day (Richardson et al., 1995). The result is that, 
depending on the source type and its intensity, sound from a given 
activity may be a negligible addition to the local environment or could 
form a distinctive signal that may affect marine mammals. Details of 
source types are described in the following text.
    Sounds are often considered to fall into one of two general types: 
Pulsed and non-pulsed (defined in the following). The distinction 
between these two sound types is important because they have differing 
potential to cause physical effects, particularly with regard to 
hearing (e.g., Ward, 1997 in Southall et al., 2007). Please see 
Southall et al. (2007) for an in-depth discussion of these concepts.
    Pulsed sound sources (e.g., airguns, explosions, gunshots, sonic 
booms, impact pile driving) produce signals that are brief (typically 
considered to be less than one second), broadband, atonal transients 
(ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur 
either as isolated events or repeated in some succession. Pulsed sounds 
are all characterized by a relatively rapid rise from ambient pressure 
to a maximal pressure value followed by a rapid decay period that may 
include a period of diminishing, oscillating maximal and minimal 
pressures and generally have an increased capacity to induce physical 
injury as compared with sounds that lack these features.
    Non-pulsed sounds can be tonal, narrowband, or broadband, brief or 
prolonged, and may be either continuous or non-continuous (ANSI, 1995; 
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals 
of short duration but without the essential properties of pulses (e.g., 
rapid rise time). Examples of non-pulsed sounds include those produced 
by vessels, aircraft, machinery operations such as drilling or 
dredging, vibratory pile driving, and active sonar systems (such as 
those used by the U.S. Navy). The duration of such sounds, as received 
at a distance, can be greatly extended in a highly reverberant 
environment.
    Airgun arrays produce pulsed signals with energy in a frequency 
range from about 10-2,000 Hz, with most energy radiated at frequencies 
below 200 Hz. The amplitude of the acoustic wave emitted from the 
source is equal in all directions (i.e., omnidirectional), but airgun 
arrays do possess some directionality due to different phase delays 
between guns in different directions. Airgun arrays are typically tuned 
to maximize functionality for data acquisition purposes, meaning that 
sound transmitted in horizontal directions and at higher frequencies is 
minimized to the extent possible.
    As described above, two types of sub-bottom profiler would also be 
used by Hilcorp during the geotechnical and geohazard surveys: A low 
resolution unit (1-4 kHz) and a high resolution unit (2-24 kHz).
    Potential Effects of Underwater Sound--Please refer to the 
information given previously (``Description of Active Acoustic Sound 
Sources'') regarding sound, characteristics of sound types, and metrics 
used in this document. Note that, in the following discussion, we refer 
in many cases to a recent review article concerning studies of noise-
induced hearing loss conducted from 1996-2015 (i.e., Finneran, 2015). 
For study-specific citations, please see that work. Anthropogenic 
sounds cover a broad range of frequencies and sound levels and can have 
a range of highly variable impacts on marine life, from none or minor 
to potentially severe responses, depending on received levels, duration 
of exposure, behavioral context, and various other factors. The 
potential effects of underwater sound

[[Page 12346]]

from active acoustic sources can potentially result in one or more of 
the following: Temporary or permanent hearing impairment, non-auditory 
physical or physiological effects, behavioral disturbance, stress, and 
masking (Richardson et al., 1995; Gordon et al., 2004; Nowacek et al., 
2007; Southall et al., 2007; G[ouml]tz et al., 2009). The degree of 
effect is intrinsically related to the signal characteristics, received 
level, distance from the source, and duration of the sound exposure. In 
general, sudden, high level sounds can cause hearing loss, as can 
longer exposures to lower level sounds. Temporary or permanent loss of 
hearing will occur almost exclusively for noise within an animal's 
hearing range. We first describe specific manifestations of acoustic 
effects before providing discussion specific to the use of airguns.
    Richardson et al. (1995) described zones of increasing intensity of 
effect that might be expected to occur, in relation to distance from a 
source and assuming that the signal is within an animal's hearing 
range. First is the area within which the acoustic signal would be 
audible (potentially perceived) to the animal but not strong enough to 
elicit any overt behavioral or physiological response. The next zone 
corresponds with the area where the signal is audible to the animal and 
of sufficient intensity to elicit behavioral or physiological 
responsiveness. Third is a zone within which, for signals of high 
intensity, the received level is sufficient to potentially cause 
discomfort or tissue damage to auditory or other systems. Overlaying 
these zones to a certain extent is the area within which masking (i.e., 
when a sound interferes with or masks the ability of an animal to 
detect a signal of interest that is above the absolute hearing 
threshold) may occur; the masking zone may be highly variable in size.
    We describe the more severe effects certain non-auditory physical 
or physiological effects only briefly as we do not expect that use of 
airgun arrays, sub-bottom profilers, drill rig construction, or sheet 
pile driving are reasonably likely to result in such effects (see below 
for further discussion). Potential effects from impulsive sound sources 
can range in severity from effects such as behavioral disturbance or 
tactile perception to physical discomfort, slight injury of the 
internal organs and the auditory system, or mortality (Yelverton et 
al., 1973). Non-auditory physiological effects or injuries that 
theoretically might occur in marine mammals exposed to high level 
underwater sound or as a secondary effect of extreme behavioral 
reactions (e.g., change in dive profile as a result of an avoidance 
reaction) caused by exposure to sound include neurological effects, 
bubble formation, resonance effects, and other types of organ or tissue 
damage (Cox et al., 2006; Southall et al., 2007; Zimmer and Tyack, 
2007; Tal et al., 2015). The suite of activities considered here do not 
involve the use of devices such as explosives or mid-frequency tactical 
sonar that are associated with these types of effects.
    1. Threshold Shift--Marine mammals exposed to high-intensity sound, 
or to lower-intensity sound for prolonged periods, can experience 
hearing threshold shift (TS), which is the loss of hearing sensitivity 
at certain frequency ranges (Finneran, 2015). TS can be permanent 
(PTS), in which case the loss of hearing sensitivity is not fully 
recoverable, or temporary (TTS), in which case the animal's hearing 
threshold would recover over time (Southall et al., 2007). Repeated 
sound exposure that leads to TTS could cause PTS. In severe cases of 
PTS, there can be total or partial deafness, while in most cases the 
animal has an impaired ability to hear sounds in specific frequency 
ranges (Kryter, 1985).
    When PTS occurs, there is physical damage to the sound receptors in 
the ear (i.e., tissue damage), whereas TTS represents primarily tissue 
fatigue and is reversible (Southall et al., 2007). In addition, other 
investigators have suggested that TTS is within the normal bounds of 
physiological variability and tolerance and does not represent physical 
injury (e.g., Ward, 1997). Therefore, NMFS does not consider TTS to 
constitute auditory injury.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals. There is no PTS data for cetaceans, but such 
relationships are assumed to be similar to those in humans and other 
terrestrial mammals. PTS typically occurs at exposure levels at least 
several decibels above (a 40-dB threshold shift approximates PTS onset; 
e.g., Kryter et al., 1966; Miller, 1974) which would induce mild TTS (a 
6-dB threshold shift approximates TTS onset; e.g., Southall et al. 
2007). Based on data from terrestrial mammals, a precautionary 
assumption is that the PTS thresholds for impulse sounds (such as 
airgun pulses as received close to the source) are at least 6 dB higher 
than the TTS threshold on a peak-pressure basis, and PTS cumulative 
sound exposure level (SELcum) thresholds are 15 to 20 dB higher than 
TTS SELcum thresholds (Southall et al., 2007). Given the higher level 
of sound combined with longer exposure duration necessary to cause PTS, 
it is expected that limited PTS could occur from the proposed 
activities. For mid-frequency cetaceans in particular, potential 
protective mechanisms may help limit onset of TTS or prevent onset of 
PTS. Such mechanisms include dampening of hearing, auditory adaptation, 
or behavioral amelioration (e.g., Nachtigall and Supin, 2013; Miller et 
al., 2012; Finneran et al., 2015; Popov et al., 2016). Given the higher 
level of sound, longer durations of exposure necessary to cause PTS, it 
is possible but unlikely PTS would occur during the proposed seismic 
surveys, geotechnical surveys, or other exploratory drilling 
activities.
    TTS is the mildest form of hearing impairment that can occur during 
exposure to sound (Kryter, 1985). While experiencing TTS, the hearing 
threshold rises, and a sound must be at a higher level in order to be 
heard. In terrestrial and marine mammals, TTS can last from minutes or 
hours to days (in cases of strong TTS). In many cases, hearing 
sensitivity recovers rapidly after exposure to the sound ends. Few data 
on sound levels and durations necessary to elicit mild TTS have been 
obtained for marine mammals.
    Marine mammal hearing plays a critical role in communication with 
conspecifics, and interpretation of environmental cues for purposes 
such as predator avoidance and prey capture. Depending on the degree 
(elevation of threshold in dB), duration (i.e., recovery time), and 
frequency range of TTS, and the context in which it is experienced, TTS 
can have effects on marine mammals ranging from discountable to 
serious. For example, a marine mammal may be able to readily compensate 
for a brief, relatively small amount of TTS in a non-critical frequency 
range that occurs during a time where ambient noise is lower and there 
are not as many competing sounds present. Alternatively, a larger 
amount and longer duration of TTS sustained during time when 
communication is critical for successful mother/calf interactions could 
have more serious impacts.
    Finneran et al. (2015) measured hearing thresholds in three captive 
bottlenose dolphins before and after exposure to ten pulses produced by 
a seismic airgun in order to study TTS induced after exposure to 
multiple pulses. Exposures began at relatively low levels and gradually 
increased over a period of several months, with the highest exposures 
at peak SPLs from 196 to 210 dB and cumulative (unweighted) SELs from 
193-195 dB. No substantial TTS was observed. In addition, behavioral 
reactions were

[[Page 12347]]

observed that indicated that animals can learn behaviors that 
effectively mitigate noise exposures (although exposure patterns must 
be learned, which is less likely in wild animals than for the captive 
animals considered in this study). The authors note that the failure to 
induce more significant auditory effects is likely due to the 
intermittent nature of exposure, the relatively low peak pressure 
produced by the acoustic source, and the low-frequency energy in airgun 
pulses as compared with the frequency range of best sensitivity for 
dolphins and other mid-frequency cetaceans.
    Currently, TTS data only exist for four species of cetaceans 
(bottlenose dolphin (Tursiops truncatus), beluga whale (Delphinapterus 
leucas), harbor porpoise, and Yangtze finless porpoise (Neophocoena 
asiaeorientalis)) and five species of pinnipeds (northern elephant 
seal, harbor seal, and California sea lion) exposed to a limited number 
of sound sources (i.e., mostly tones and octave-band noise) in 
laboratory settings (Finneran, 2015). TTS was not observed in trained 
spotted (Phoca largha) and ringed (Pusa hispida) seals exposed to 
impulsive noise at levels matching previous predictions of TTS onset 
(Reichmuth et al., 2016). In general, harbor seals and harbor porpoises 
have a lower TTS onset than other measured pinniped or cetacean species 
(Finneran, 2015). Additionally, the existing marine mammal TTS data 
come from a limited number of individuals within these species. There 
are no data available on noise-induced hearing loss for mysticetes. For 
summaries of data on TTS in marine mammals or for further discussion of 
TTS onset thresholds, please see Southall et al. (2007), Finneran and 
Jenkins (2012), Finneran (2015), and Table 5 in NMFS (2018).
    Critical questions remain regarding the rate of TTS growth and 
recovery after exposure to intermittent noise and the effects of single 
and multiple pulses. Data at present are also insufficient to construct 
generalized models for recovery and determine the time necessary to 
treat subsequent exposures as independent events. More information is 
needed on the relationship between auditory evoked potential and 
behavioral measures of TTS for various stimuli. For summaries of data 
on TTS in marine mammals or for further discussion of TTS onset 
thresholds, please see Southall et al. (2007), Finneran and Jenkins 
(2012), Finneran (2015), and NMFS (2016).
    Marine mammals in the action area during the proposed activities 
are less likely to incur TTS hearing impairment from some of the 
sources proposed to be used due to the characteristics of the sound 
sources, particularly sources such as the water jets, which include 
lower source levels (176 dB @1m) and generally very short pulses and 
duration of the sound. Even for high-frequency cetacean species (e.g., 
harbor porpoises), which may have increased sensitivity to TTS (Lucke 
et al., 2009; Kastelein et al., 2012b), individuals would have to make 
a very close approach and also remain very close to vessels operating 
these sources in order to receive multiple exposures at relatively high 
levels, as would be necessary to cause TTS. Intermittent exposures--as 
would occur due to the brief, transient signals produced by these 
sources--require a higher cumulative SEL to induce TTS than would 
continuous exposures of the same duration (i.e., intermittent exposure 
results in lower levels of TTS) (Mooney et al., 2009a; Finneran et al., 
2010). Moreover, most marine mammals would more likely avoid a loud 
sound source rather than swim in such close proximity as to result in 
TTS (much less PTS). Kremser et al. (2005) noted that the probability 
of a cetacean swimming through the area of exposure when a sub-bottom 
profiler emits a pulse is small--because if the animal was in the area, 
it would have to pass the transducer at close range in order to be 
subjected to sound levels that could cause temporary threshold shift 
and would likely exhibit avoidance behavior to the area near the 
transducer rather than swim through at such a close range. Further, the 
restricted beam shape of the sub-bottom profiler and other geophysical 
survey equipment makes it unlikely that an animal would be exposed more 
than briefly during the passage of the vessel. Boebel et al. (2005) 
concluded similarly for single and multibeam echosounders, and more 
recently, Lurton (2016) conducted a modeling exercise and concluded 
similarly that likely potential for acoustic injury from these types of 
systems is negligible, but that behavioral response cannot be ruled 
out. Animals may avoid the area around the survey vessels, thereby 
reducing exposure. Effects of non-pulsed sound on marine mammals, such 
as vibratory pile driving, are less studied. In a study by Malme et al. 
(1986) on gray whales as well as Richardson et al. (1997) on beluga 
whales, the only reactions documented in response to drilling sound 
playbacks were behavioral reactions. Any disturbance to marine mammals 
is likely to be in the form of temporary avoidance or alteration of 
opportunistic foraging behavior near the survey location.
    2. Behavioral Effects--Behavioral disturbance may include a variety 
of effects, including subtle changes in behavior (e.g., minor or brief 
avoidance of an area or changes in vocalizations), more conspicuous 
changes in similar behavioral activities, and more sustained and/or 
potentially severe reactions, such as displacement from or abandonment 
of high-quality habitat. Behavioral responses to sound are highly 
variable and context-specific and any reactions depend on numerous 
intrinsic and extrinsic factors (e.g., species, state of maturity, 
experience, current activity, reproductive state, auditory sensitivity, 
time of day), as well as the interplay between factors (e.g., 
Richardson et al., 1995; Wartzok et al., 2003; Southall et al., 2007; 
Weilgart, 2007; Archer et al., 2010). Behavioral reactions can vary not 
only among individuals but also within an individual, depending on 
previous experience with a sound source, context, and numerous other 
factors (Ellison et al., 2012), and can vary depending on 
characteristics associated with the sound source (e.g., whether it is 
moving or stationary, number of sources, distance from the source). 
Please see Appendices B-C of Southall et al. (2007) for a review of 
studies involving marine mammal behavioral responses to sound.
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al., 2003). Animals are most likely to habituate to 
sounds that are predictable and unvarying. It is important to note that 
habituation is appropriately considered as a ``progressive reduction in 
response to stimuli that are perceived as neither aversive nor 
beneficial,'' rather than as, more generally, moderation in response to 
human disturbance (Bejder et al., 2009). The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure. As noted, behavioral state may affect the type of response. 
For example, animals that are resting may show greater behavioral 
change in response to disturbing sound levels than animals that are 
highly motivated to remain in an area for feeding (Richardson et al., 
1995; NRC, 2003; Wartzok et al., 2003). Controlled experiments with 
captive marine mammals have showed pronounced behavioral reactions, 
including avoidance of loud sound sources (Ridgway et al., 1997). 
Observed responses of wild marine mammals to

[[Page 12348]]

loud pulsed sound sources (typically seismic airguns or acoustic 
harassment devices) have been varied but often consist of avoidance 
behavior or other behavioral changes suggesting discomfort (Morton and 
Symonds, 2002; see also Richardson et al., 1995; Nowacek et al., 2007). 
However, many delphinids approach acoustic source vessels with no 
apparent discomfort or obvious behavioral change (e.g., Barkaszi et 
al., 2012).
    Available studies show wide variation in response to underwater 
sound; therefore, it is difficult to predict specifically how any given 
sound in a particular instance might affect marine mammals perceiving 
the signal. If a marine mammal does react briefly to an underwater 
sound by changing its behavior or moving a small distance, the impacts 
of the change are unlikely to be significant to the individual, let 
alone the stock or population. However, if a sound source displaces 
marine mammals from an important feeding or breeding area for a 
prolonged period, impacts on individuals and populations could be 
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 
2005). However, there are broad categories of potential response, which 
we describe in greater detail here, that include alteration of dive 
behavior, alteration of foraging behavior, effects to breathing, 
interference with or alteration of vocalization, avoidance, and flight.
    Changes in dive behavior can vary widely, and may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark 2000; Ng and Leung 2003; Nowacek et al. 2004; Goldbogen et 
al. 2013). Variations in dive behavior may reflect interruptions in 
biologically significant activities (e.g., foraging) or they may be of 
little biological significance. The impact of an alteration to dive 
behavior resulting from an acoustic exposure depends on what the animal 
is doing at the time of the exposure and the type and magnitude of the 
response.
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al. 
2001; Nowacek et al. 2004; Madsen et al. 2006; Yazvenko et al. 2007). A 
determination of whether foraging disruptions incur fitness 
consequences would require information on or estimates of the energetic 
requirements of the affected individuals and the relationship between 
prey availability, foraging effort and success, and the life history 
stage of the animal.
    Visual tracking, passive acoustic monitoring, and movement 
recording tags were used to quantify sperm whale behavior prior to, 
during, and following exposure to airgun arrays at received levels in 
the range 140-160 dB at distances of 7-13 km, following a phase-in of 
sound intensity and full array exposures at 1-13 km (Madsen et al., 
2006; Miller et al., 2009). Sperm whales did not exhibit horizontal 
avoidance behavior at the surface. However, foraging behavior may have 
been affected. The sperm whales exhibited 19 percent less vocal (buzz) 
rate during full exposure relative to post exposure, and the whale that 
was approached most closely had an extended resting period and did not 
resume foraging until the airguns had ceased firing. The remaining 
whales continued to execute foraging dives throughout exposure; 
however, swimming movements during foraging dives were six percent 
lower during exposure than control periods (Miller et al., 2009). These 
data raise concerns that seismic surveys may impact foraging behavior 
in sperm whales, although more data are required to understand whether 
the differences were due to exposure or natural variation in sperm 
whale behavior (Miller et al., 2009).
    Variations in respiration naturally vary with different behaviors 
and alterations to breathing rate as a function of acoustic exposure 
can be expected to co-occur with other behavioral reactions, such as a 
flight response or an alteration in diving. However, respiration rates 
in and of themselves may be representative of annoyance or an acute 
stress response. Various studies have shown that respiration rates may 
either be unaffected or could increase, depending on the species and 
signal characteristics, again highlighting the importance in 
understanding species differences in the tolerance of underwater noise 
when determining the potential for impacts resulting from anthropogenic 
sound exposure (e.g., Kastelein et al., 2001, 2005, 2006; Gailey et 
al., 2007).
    Marine mammals vocalize for different purposes and across multiple 
modes, such as whistling, echolocation click production, calling, and 
singing. Changes in vocalization behavior in response to anthropogenic 
noise can occur for any of these modes and may result from a need to 
compete with an increase in background noise or may reflect increased 
vigilance or a startle response. For example, in the presence of 
potentially masking signals, humpback whales and killer whales have 
been observed to increase the length of their songs (Miller et al., 
2000; Fristrup et al., 2003; Foote et al., 2004), while right whales 
have been observed to shift the frequency content of their calls upward 
while reducing the rate of calling in areas of increased anthropogenic 
noise (Parks et al., 2007). In some cases, animals may cease sound 
production during production of aversive signals (Bowles et al., 1994).
    Cerchio et al. (2014) used passive acoustic monitoring to document 
the presence of singing humpback whales off the coast of northern 
Angola and to opportunistically test for the effect of seismic survey 
activity on the number of singing whales. Two recording units were 
deployed between March and December 2008 in the offshore environment, 
and the numbers of singers were counted every hour. Generalized 
Additive Mixed Models were used to assess the effect of survey day 
(seasonality), hour (diel variation), moon phase, and received levels 
of noise (measured from a single pulse during each ten minute sampled 
period) on singer number. The number of singers significantly decreased 
with increasing received level of noise, suggesting that humpback whale 
breeding activity was disrupted to some extent by the survey activity.
    Castellote et al. (2012) reported acoustic and behavioral changes 
by fin whales in response to shipping and airgun noise. Acoustic 
features of fin whale song notes recorded in the Mediterranean Sea and 
northeast Atlantic Ocean were compared for areas with different 
shipping noise levels and traffic intensities and during a seismic 
airgun survey. During the first 72 hours of the survey, a steady 
decrease in song received levels and bearings to singers indicated that 
whales moved away from the acoustic source and out of the study area. 
This displacement persisted for a time period well beyond the 10-day 
duration of seismic airgun activity, providing evidence that fin whales 
may avoid an area for an extended period in the presence of increased 
noise. The authors hypothesize that fin whale acoustic communication is 
modified to compensate for increased background noise and that a 
sensitization process may play a role in the observed temporary 
displacement.

[[Page 12349]]

    Seismic pulses at average received levels of 131 dB re 1 
[micro]Pa2-s caused blue whales to increase call production (Di Iorio 
and Clark, 2010). In contrast, McDonald et al. (1995) tracked a blue 
whale with seafloor seismometers and reported that it stopped 
vocalizing and changed its travel direction at a range of 10 km from 
the acoustic source vessel (estimated received level 143 dB pk-pk). 
Blackwell et al. (2013) found that bowhead whale call rates dropped 
significantly at onset of airgun use at sites with a median distance of 
41-45 km from the survey. Blackwell et al. (2015) expanded this 
analysis to show that whales actually increased calling rates as soon 
as airgun signals were detectable before ultimately decreasing calling 
rates at higher received levels (i.e., 10-minute SELcum of ~127 dB). 
Overall, these results suggest that bowhead whales may adjust their 
vocal output in an effort to compensate for noise before ceasing 
vocalization effort and ultimately deflecting from the acoustic source 
(Blackwell et al., 2013, 2015). These studies demonstrate that even low 
levels of noise received far from the source can induce changes in 
vocalization and/or behavior for mysticetes.
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of disturbance 
in marine mammals (Richardson et al., 1995). For example, gray whales 
are known to change direction--deflecting from customary migratory 
paths--in order to avoid noise from seismic surveys (Malme et al., 
1984). Humpback whales showed avoidance behavior in the presence of an 
active seismic array during observational studies and controlled 
exposure experiments in western Australia (McCauley et al., 2000). 
Avoidance may be short-term, with animals returning to the area once 
the noise has ceased (e.g., Bowles et al., 1994; Stone et al., 2000; 
Morton and Symonds, 2002; Gailey et al., 2007). Longer-term 
displacement is possible, however, which may lead to changes in 
abundance or distribution patterns of the affected species in the 
affected region if habituation to the presence of the sound does not 
occur (e.g., Bejder et al., 2006; Teilmann et al., 2006).
    A flight response is a dramatic change in normal movement to a 
directed and rapid movement away from the perceived location of a sound 
source. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and 
Heithaus, 1996). The result of a flight response could range from 
brief, temporary exertion and displacement from the area where the 
signal provokes flight to, in extreme cases, marine mammal strandings 
(Evans and England, 2001). However, it should be noted that response to 
a perceived predator does not necessarily invoke flight (Ford and 
Reeves, 2008), and whether individuals are solitary or in groups may 
influence the response.
    Behavioral disturbance can also impact marine mammals in more 
subtle ways. Increased vigilance may result in costs related to 
diversion of focus and attention (i.e., when a response consists of 
increased vigilance, it may come at the cost of decreased attention to 
other critical behaviors such as foraging or resting). These effects 
have generally not been demonstrated for marine mammals, but studies 
involving fish and terrestrial animals have shown that increased 
vigilance may substantially reduce feeding rates (e.g., Beauchamp and 
Livoreil 1997; Purser and Radford 2011). In addition, chronic 
disturbance can cause population declines through reduction of fitness 
(e.g., decline in body condition) and subsequent reduction in 
reproductive success, survival, or both (e.g., Harrington and Veitch 
1992; Daan et al. 1996; Bradshaw et al. 1998). However, Ridgway et al. 
(2006) reported that increased vigilance in bottlenose dolphins exposed 
to sound over a five-day period did not cause any sleep deprivation or 
stress effects.
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption 
of such functions resulting from reactions to stressors such as sound 
exposure are more likely to be significant if they last more than one 
diel cycle or recur on subsequent days (Southall et al., 2007). 
Consequently, a behavioral response lasting less than one day and not 
recurring on subsequent days is not considered particularly severe 
unless it could directly affect reproduction or survival (Southall et 
al., 2007). Note that there is a difference between multi-day 
substantive behavioral reactions and multi-day anthropogenic 
activities. For example, just because an activity lasts for multiple 
days does not necessarily mean that individual animals are either 
exposed to activity-related stressors for multiple days or, further, 
exposed in a manner resulting in sustained multi-day substantive 
behavioral responses.
    Stone (2015) reported data from at-sea observations during 1,196 
seismic surveys from 1994 to 2010. When large arrays of airguns 
(considered to be 500 cui or more) were firing, lateral displacement, 
more localized avoidance, or other changes in behavior were evident for 
most odontocetes. However, significant responses to large arrays were 
found only for the minke whale and fin whale. Behavioral responses 
observed included changes in swimming or surfacing behavior, with 
indications that cetaceans remained near the water surface at these 
times. Cetaceans were recorded as feeding less often when large arrays 
were active. Behavioral observations of gray whales during a seismic 
survey monitored whale movements and respirations pre-, during and 
post-seismic survey (Gailey et al., 2016). Behavioral state and water 
depth were the best `natural' predictors of whale movements and 
respiration and, after considering natural variation, none of the 
response variables were significantly associated with seismic survey or 
vessel sounds.
    Marine mammals are likely to avoid the proposed activities, 
especially harbor porpoises, while the harbor seals might be attracted 
to them out of curiosity. However, because the sub-bottom profilers and 
seismic equipment operate from moving vessels, the area (relative to 
the available habitat in Cook Inlet) and time that this equipment would 
be affecting a given location is very small. Further, for mobile 
sources, once an area has been surveyed, it is not likely that it will 
be surveyed again, therefore reducing the likelihood of repeated 
geophysical and geotechnical survey impacts within the survey area. The 
isopleths for harassment for the stationary sources considered in this 
document are small relative to those for mobile sources. Therefore, 
while the sound is concentrated in the same area for the duration of 
the activity (duration of pile driving, VSP, etc), the amount of area 
affected by noise levels which we expect may cause harassment are small 
relative to the mobile sources. Additionally, animals may more 
predictably avoid the area of the disturbance as the source is 
stationary. Overall duration of these sound sources is still short and 
unlikely to cause more than temporary disturbance.
    We have also considered the potential for severe behavioral 
responses such as stranding and associated indirect injury or mortality 
from Hilcorp's use of high resolution geophysical survey equipment, on 
the basis of a 2008 mass stranding of approximately one hundred melon-
headed whales in a Madagascar lagoon system. An investigation of the

[[Page 12350]]

event indicated that use of a high-frequency mapping system (12-kHz 
multibeam echosounder) was the most plausible and likely initial 
behavioral trigger of the event, while providing the caveat that there 
is no unequivocal and easily identifiable single cause (Southall et 
al., 2013). The investigatory panel's conclusion was based on (1) very 
close temporal and spatial association and directed movement of the 
survey with the stranding event; (2) the unusual nature of such an 
event coupled with previously documented apparent behavioral 
sensitivity of the species to other sound types (Southall et al., 2006; 
Brownell et al., 2009); and (3) the fact that all other possible 
factors considered were determined to be unlikely causes. Specifically, 
regarding survey patterns prior to the event and in relation to 
bathymetry, the vessel transited in a north-south direction on the 
shelf break parallel to the shore, ensonifying large areas of deep-
water habitat prior to operating intermittently in a concentrated area 
offshore from the stranding site. This may have trapped the animals 
between the sound source and the shore, thus driving them towards the 
lagoon system. The investigatory panel systematically excluded or 
deemed highly unlikely nearly all potential reasons for these animals 
leaving their typical pelagic habitat for an area extremely atypical 
for the species (i.e., a shallow lagoon system). Notably, this was the 
first time that such a system has been associated with a stranding 
event. The panel also noted several site- and situation-specific 
secondary factors that may have contributed to the avoidance responses 
that led to the eventual entrapment and mortality of the whales. 
Specifically, shoreward-directed surface currents and elevated 
chlorophyll levels in the area preceding the event may have played a 
role (Southall et al., 2013). The report also notes that prior use of a 
similar system in the general area may have sensitized the animals and 
also concluded that, for odontocete cetaceans that hear well in higher 
frequency ranges where ambient noise is typically quite low, high-power 
active sonars operating in this range may be more easily audible and 
have potential effects over larger areas than low frequency systems 
that have more typically been considered in terms of anthropogenic 
noise impacts. It is, however, important to note that the relatively 
lower output frequency, higher output power, and complex nature of the 
system implicated in this event, in context of the other factors noted 
here, likely produced a fairly unusual set of circumstances that 
indicate that such events would likely remain rare and are not 
necessarily relevant to use of lower-power, higher-frequency systems 
more commonly used for high resolution geophysical (HRG) survey 
applications. The risk of similar events recurring may be very low, 
given the extensive use of active acoustic systems used for scientific 
and navigational purposes worldwide on a daily basis and the lack of 
direct evidence of such responses previously reported.
    3. Stress Responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle, 1950; 
Moberg 2000). In many cases, an animal's first and sometimes most 
economical (in terms of energetic costs) response is behavioral 
avoidance of the potential stressor. Autonomic nervous system responses 
to stress typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that 
are affected by stress--including immune competence, reproduction, 
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been 
implicated in failed reproduction, altered metabolism, reduced immune 
competence, and behavioral disturbance (e.g., Moberg 1987; Blecha 
2000). Increases in the circulation of glucocorticoids are also equated 
with stress (Romano et al. 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficiently to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; 
Lankford et al., 2005). Stress responses due to exposure to 
anthropogenic sounds or other stressors and their effects on marine 
mammals have also been reviewed (Fair and Becker, 2000; Romano et al., 
2002) and, more rarely, studied in wild populations (e.g., Romano et 
al., 2002). For example, Rolland et al. (2012) found that noise 
reduction from reduced ship traffic in the Bay of Fundy was associated 
with decreased stress in North Atlantic right whales. These and other 
studies lead to a reasonable expectation that some marine mammals will 
experience physiological stress responses upon exposure to acoustic 
stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC, 2003).
    In general, there are few data on the potential for strong, 
anthropogenic underwater sounds to cause non-auditory physical effects 
in marine mammals. Such effects, if they occur at all, would presumably 
be limited to short distances and to activities that extend over a 
prolonged period. The available data do not allow identification of a 
specific exposure level above which non-auditory effects can be 
expected (Southall et al., 2007). There is no definitive evidence that 
any of these effects occur even for marine mammals in close proximity 
to an anthropogenic sound source. In addition, marine mammals that show 
behavioral avoidance of survey vessels and related sound sources, are 
unlikely to incur non-auditory impairment or other physical effects. 
NMFS does not expect that the generally short-term, intermittent, and 
transitory seismic and geophysical surveys would create conditions of 
long-term, continuous noise and chronic acoustic exposure leading to 
long-term physiological stress responses in marine mammals. While the 
noise from drilling related activities are more continuous and longer 
term, those sounds are generated at a much lower level than the mobile 
sources discussed earlier.
    4. Auditory Masking--Sound can disrupt behavior through masking, or 
interfering with, an animal's ability to detect, recognize, or 
discriminate between acoustic signals of interest (e.g., those used for 
intraspecific communication and social interactions, prey detection, 
predator avoidance,

[[Page 12351]]

navigation) (Richardson et al., 1995; Erbe et al., 2016). Masking 
occurs when the receipt of a sound is interfered with by another 
coincident sound at similar frequencies and at similar or higher 
intensity, and may occur whether the sound is natural (e.g., snapping 
shrimp, wind, waves, precipitation) or anthropogenic (e.g., shipping, 
sonar, seismic exploration) in origin. The ability of a noise source to 
mask biologically important sounds depends on the characteristics of 
both the noise source and the signal of interest (e.g., signal-to-noise 
ratio, temporal variability, direction), in relation to each other and 
to an animal's hearing abilities (e.g., sensitivity, frequency range, 
critical ratios, frequency discrimination, directional discrimination, 
age or TTS hearing loss), and existing ambient noise and propagation 
conditions.
    Under certain circumstances, marine mammals experiencing 
significant masking could also be impaired from maximizing their 
performance fitness in survival and reproduction. Therefore, when the 
coincident (masking) sound is man-made, it may be considered harassment 
when disrupting or altering critical behaviors. It is important to 
distinguish TTS and PTS, which persist after the sound exposure, from 
masking, which occurs during the sound exposure. Because masking 
(without resulting in TS) is not associated with abnormal physiological 
function, it is not considered a physiological effect, but rather a 
potential behavioral effect.
    The frequency range of the potentially masking sound is important 
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation 
sounds produced by odontocetes but are more likely to affect detection 
of mysticete communication calls and other potentially important 
natural sounds, such as those produced by surf and some prey species. 
The masking of communication signals by anthropogenic noise may be 
considered as a reduction in the communication space of animals (e.g., 
Clark et al., 2009) and may result in energetic or other costs as 
animals change their vocalization behavior (e.g., Miller et al. 2000; 
Foote et al. 2004; Parks et al. 2007; Holt et al. 2009). Masking can be 
reduced in situations where the signal and noise come from different 
directions (Richardson et al. 1995), through amplitude modulation of 
the signal, or through other compensatory behaviors (Houser and Moore 
2014). Masking can be tested directly in captive species (e.g., Erbe 
2008) but, in wild populations, it must be either modeled or inferred 
from evidence of masking compensation. There are few studies addressing 
real-world masking sounds likely to be experienced by marine mammals in 
the wild (e.g., Branstetter et al. 2013).
    Masking affects both senders and receivers of acoustic signals and 
can potentially have long-term chronic effects on marine mammals at the 
population level as well as at the individual level. Low-frequency 
ambient sound levels have increased by as much as 20 dB (more than 
three times in terms of SPL) in the world's ocean from pre-industrial 
periods, with most of the increase from distant commercial shipping 
(Hildebrand 2009). All anthropogenic sound sources, but especially 
chronic and lower-frequency signals (e.g., from vessel traffic), 
contribute to elevated ambient sound levels, thus intensifying masking.
    Marine mammal communications would not likely be masked appreciably 
by the sub-profiler or seismic survey's signals given the 
directionality of the signal and the brief period when an individual 
mammal is likely to be within its beam. The probability for conductor 
pipe driving masking acoustic signals important to the behavior and 
survival of marine mammal species is low. Vibratory pile driving is 
also relatively short-term, with rapid oscillations occurring for short 
durations. It is possible that vibratory pile driving resulting from 
this proposed action may mask acoustic signals important to the 
behavior and survival of marine mammal species, but the short-term 
duration and limited affected area would result in insignificant 
impacts from masking. Any masking event that could possibly rise to 
Level B harassment under the MMPA would occur concurrently within the 
zones of behavioral harassment already estimated for vibratory pile and 
conductor pipe driving, and which have already been taken into account 
in the exposure analysis. Pile driving would occur for limited 
durations across multiple widely dispersed sites, thus we do not 
anticipate masking to significantly affect marine mammals.

Ship Strike

    Vessel collisions with marine mammals, or ship strikes, can result 
in death or serious injury of the animal. Wounds resulting from ship 
strike may include massive trauma, hemorrhaging, broken bones, or 
propeller lacerations (Knowlton and Kraus 2001). An animal at the 
surface may be struck directly by a vessel, a surfacing animal may hit 
the bottom of a vessel, or an animal just below the surface may be cut 
by a vessel's propeller. Superficial strikes may not kill or result in 
the death of the animal. These interactions are typically associated 
with large whales (e.g., fin whales), which are occasionally found 
draped across the bulbous bow of large commercial ships upon arrival in 
port. Although smaller cetaceans are more maneuverable in relation to 
large vessels than are large whales, they may also be susceptible to 
strike. The severity of injuries typically depends on the size and 
speed of the vessel, with the probability of death or serious injury 
increasing as vessel speed increases (Knowlton and Kraus 2001; Laist et 
al. 2001; Vanderlaan and Taggart 2007; Conn and Silber 2013). Impact 
forces increase with speed, as does the probability of a strike at a 
given distance (Silber et al. 2010; Gende et al. 2011).
    Pace and Silber (2005) also found that the probability of death or 
serious injury increased rapidly with increasing vessel speed. 
Specifically, the predicted probability of serious injury or death 
increased from 45 to 75 percent as vessel speed increased from 10 to 14 
kn, and exceeded 90 percent at 17 kn. Higher speeds during collisions 
result in greater force of impact, but higher speeds also appear to 
increase the chance of severe injuries or death through increased 
likelihood of collision by pulling whales toward the vessel (Clyne and 
Kennedy, 1999;). In a separate study, Vanderlaan and Taggart (2007) 
analyzed the probability of lethal mortality of large whales at a given 
speed, showing that the greatest rate of change in the probability of a 
lethal injury to a large whale as a function of vessel speed occurs 
between 8.6 and 15 kt. The chances of a lethal injury decline from 
approximately 80 percent at 15 kt to approximately 20 percent at 8.6 
kt. At speeds below 11.8 kt, the chances of lethal injury drop below 50 
percent, while the probability asymptotically increases toward one 
hundred percent above 15 kt.
    Hilcorp's seismic vessels would travel at approximately 4 knots 
(7.41 km/hour) while towing seismic survey gear and a maximum of 4.5 
knots (8.3 km/hr) while conducting geotechnical and geohazard surveys 
(Faithweather, 2018). At these speeds, both the possibility of striking 
a marine mammal and the possibility of a strike resulting in serious 
injury or mortality are discountable. At average transit speed, the 
probability of serious injury or mortality resulting from a strike is 
less than 50 percent. However, the likelihood of a strike actually 
happening is again discountable. Ship strikes, as analyzed in the 
studies cited

[[Page 12352]]

above, generally involve commercial shipping, which is much more common 
in both space and time than is geophysical survey activity. Jensen and 
Silber (2004) summarized ship strikes of large whales worldwide from 
1975-2003 and found that most collisions occurred in the open ocean and 
involved large vessels (e.g., commercial shipping). Commercial fishing 
vessels were responsible for three percent of recorded collisions, 
while no such incidents were reported for geophysical survey vessels 
during that time period.
    It is possible for ship strikes to occur while traveling at slow 
speeds. For example, a hydrographic survey vessel traveling at low 
speed (5.5 kt) while conducting mapping surveys off the central 
California coast struck and killed a blue whale in 2009. The State of 
California determined that the whale had suddenly and unexpectedly 
surfaced beneath the hull, with the result that the propeller severed 
the whale's vertebrae, and that this was an unavoidable event. This 
strike represents the only such incident in approximately 540,000 hours 
of similar coastal mapping activity (p = 1.9 x 10-6; 95% CI = 0-5.5 x 
10-6; NMFS, 2013b). In addition, a research vessel reported a fatal 
strike in 2011 of a dolphin in the Atlantic, demonstrating that it is 
possible for strikes involving smaller cetaceans to occur. In that 
case, the incident report indicated that an animal apparently was 
struck by the vessel's propeller as it was intentionally swimming near 
the vessel. While indicative of the type of unusual events that cannot 
be ruled out, neither of these instances represents a circumstance that 
would be considered reasonably foreseeable or that would be considered 
preventable.
    Although the likelihood of the vessel striking a marine mammal is 
low, we require a robust ship strike avoidance protocol (see ``Proposed 
Mitigation''), which we believe eliminates any foreseeable risk of ship 
strike. We anticipate that vessel collisions involving a seismic data 
acquisition vessel towing gear, while not impossible, represent 
unlikely, unpredictable events for which there are no preventive 
measures. Given the required mitigation measures, the relatively slow 
speed of the vessel towing gear, the presence of marine mammal 
observers, and the short duration of the survey, we believe that the 
possibility of ship strike is discountable. Further, were a strike of a 
large whale to occur, it would be unlikely to result in serious injury 
or mortality. No incidental take resulting from ship strike is 
anticipated, and this potential effect of the specified activity will 
not be discussed further in the following analysis.

Stranding

    When a living or dead marine mammal swims or floats onto shore and 
becomes ``beached'' or incapable of returning to sea, the event is a 
``stranding'' (Geraci et al. 1999; Perrin and Geraci 2002; Geraci and 
Lounsbury 2005). The legal definition for a stranding under the MMPA is 
(A) a marine mammal is dead and is (i) on a beach or shore of the 
United States; or (ii) in waters under the jurisdiction of the United 
States (including any navigable waters); or (B) a marine mammal is 
alive and is (i) on a beach or shore of the United States and is unable 
to return to the water; (ii) on a beach or shore of the United States 
and, although able to return to the water, is in need of apparent 
medical attention; or (iii) in the waters under the jurisdiction of the 
United States (including any navigable waters), but is unable to return 
to its natural habitat under its own power or without assistance.
    Marine mammals strand for a variety of reasons, such as infectious 
agents, biotoxicosis, starvation, fishery interaction, ship strike, 
unusual oceanographic or weather events, sound exposure, or 
combinations of these stressors sustained concurrently or in series. 
However, the cause or causes of most strandings are unknown (Eaton, 
1979; Best 1982). Numerous studies suggest that the physiology, 
behavior, habitat relationships, age, or condition of cetaceans may 
cause them to strand or might pre-dispose them to strand when exposed 
to another phenomenon. These suggestions are consistent with the 
conclusions of numerous other studies that have demonstrated that 
combinations of dissimilar stressors commonly combine to kill an animal 
or dramatically reduce its fitness, even though one exposure without 
the other does not produce the same result (Fair and Becker 2000; 
Moberg, 2000; Romero 2004; Sih et al. 2004).
    Use of military tactical sonar has been implicated in a majority of 
investigated stranding events, although one stranding event was 
associated with the use of seismic airguns. This event occurred in the 
Gulf of California, coincident with seismic reflection profiling by the 
R/V Maurice Ewing operated by Lamont-Doherty Earth Observatory (LDEO) 
of Columbia University and involved two Cuvier's beaked whales 
(Hildebrand 2004). The vessel had been firing an array of 20 airguns 
with a total volume of 8,500 cui (Hildebrand 2004). Most known 
stranding events have involved beaked whales, though a small number 
have involved deep-diving delphinids or sperm whales (e.g., Southall et 
al. 2013). In general, long duration (~1 second) and high-intensity 
sounds (>235 dB SPL) have been implicated in stranding events 
(Hildebrand 2004). With regard to beaked whales, mid-frequency sound 
has been implicated in a few specific cases (when causation can be 
determined) (Hildebrand 2004). Although seismic airguns create 
predominantly low-frequency energy, the signal does include a mid-
frequency component. Based on the information presented above, we have 
considered the potential for the proposed survey to result in marine 
mammal stranding and have concluded that, based on the best available 
information, stranding is not expected to occur.

Other Potential Impacts

    Here, we briefly address the potential risks due to entanglement 
and contaminant spills. We are not aware of any records of marine 
mammal entanglement in towed arrays such as those considered here. The 
discharge of trash and debris is prohibited (33 CFR 151.51-77) unless 
it is passed through a machine that breaks up solids such that they can 
pass through a 25-mm mesh screen. All other trash and debris must be 
returned to shore for proper disposal with municipal and solid waste. 
Some personal items may be accidentally lost overboard. However, U.S. 
Coast Guard and Environmental Protection Act regulations require 
operators to become proactive in avoiding accidental loss of solid 
waste items by developing waste management plans, posting informational 
placards, manifesting trash sent to shore, and using special 
precautions such as covering outside trash bins to prevent accidental 
loss of solid waste. There are no meaningful entanglement risks posed 
by the described activity, and entanglement risks are not discussed 
further in this document.
    Marine mammals could be affected by accidentally spilled diesel 
fuel from a vessel associated with proposed survey activities. 
Quantities of diesel fuel on the sea surface may affect marine mammals 
through various pathways: Surface contact of the fuel with skin and 
other mucous membranes, inhalation of concentrated petroleum vapors, or 
ingestion of the fuel (direct ingestion or by the ingestion of oiled 
prey) (e.g., Geraci and St. Aubin, 1980, 1990). However, the likelihood 
of a fuel spill during any particular geophysical survey is considered 
to be remote, and

[[Page 12353]]

the potential for impacts to marine mammals would depend greatly on the 
size and location of a spill and meteorological conditions at the time 
of the spill. Spilled fuel would rapidly spread to a layer of varying 
thickness and break up into narrow bands or windows parallel to the 
wind direction. The rate at which the fuel spreads would be determined 
by the prevailing conditions such as temperature, water currents, tidal 
streams, and wind speeds. Lighter, volatile components of the fuel 
would evaporate to the atmosphere almost completely in a few days. 
Evaporation rate may increase as the fuel spreads because of the 
increased surface area of the slick. Rougher seas, high wind speeds, 
and high temperatures also tend to increase the rate of evaporation and 
the proportion of fuel lost by this process (Scholz et al., 1999). We 
do not anticipate potentially meaningful effects to marine mammals as a 
result of any contaminant spill resulting from the proposed survey 
activities, and contaminant spills are not discussed further in this 
document.
    Similarly, marine mammals could be affected by spilled hazardous 
materials generated by the drilling process. Large and small quantities 
of hazardous materials, including diesel fuel and gasoline, would be 
handled, transported, and stored following the rules and procedures 
described in the Spill Prevention, Control, and Countermeasure (SPCC) 
Plan. Spills and leaks of oil or wastewater arising from the proposed 
activities that reach marine waters could result in direct impacts to 
the health of exposed marine mammals. Individual marine mammals could 
show acute irritation or damage to their eyes, blowhole or nares, and 
skin; fouling of baleen, which could reduce feeding efficiency; and 
respiratory distress from the inhalation of vapors (Geraci and St. 
Aubin 1990). Long-term impacts from exposure to contaminants to the 
endocrine system could impair health and reproduction (Geraci and St. 
Aubin 1990). Ingestion of contaminants could cause acute irritation to 
the digestive tract, including vomiting and aspiration into the lungs, 
which could result in pneumonia or death (Geraci and St. Aubin 1990). 
However, the measures outlined in Hilcorp's spill plan minimize the 
risk of a spill such that we do not anticipate potentially meaningful 
effects to marine mammals as a result of oil spills from this activity, 
and oil spills are not discussed further in this document.

Anticipated Effects on Marine Mammal Habitat

    Effects to Prey--Marine mammal prey varies by species, season, and 
location and, for some, is not well documented. Fish react to sounds 
which are especially strong and/or intermittent low-frequency sounds. 
Short duration, sharp sounds can cause overt or subtle changes in fish 
behavior and local distribution. Hastings and Popper (2005) identified 
several studies that suggest fish may relocate to avoid certain areas 
of sound energy. Additional studies have documented effects of pulsed 
sound on fish, although several are based on studies in support of 
construction projects (e.g., Scholik and Yan 2001, 2002; Popper and 
Hastings 2009). Sound pulses at received levels of 160 dB may cause 
subtle changes in fish behavior, although the behavioral threshold 
currently observed is < 150 dB RMA re 1 [micro]Pa. SPLs of 180 dB may 
cause noticeable changes in behavior (Pearson et al. 1992; Skalski et 
al. 1992). SPLs of sufficient strength have been known to cause injury 
to fish and fish mortality. The most likely impact to fish from survey 
activities at the project area would be temporary avoidance of the 
area. The duration of fish avoidance of a given area after survey 
effort stops is unknown, but a rapid return to normal recruitment, 
distribution and behavior is anticipated.
    Information on seismic airgun impacts to zooplankton, which 
represent an important prey type for mysticetes, is limited. However, 
McCauley et al. (2017) reported that experimental exposure to a pulse 
from a 150 cui airgun decreased zooplankton abundance when compared 
with controls, as measured by sonar and net tows, and caused a two- to 
threefold increase in dead adult and larval zooplankton. Although no 
adult krill were present, the study found that all larval krill were 
killed after air gun passage. Impacts were observed out to the maximum 
1.2 km range sampled. The reaction of fish to airguns depends on the 
physiological state of the fish, past exposures, motivation (e.g., 
feeding, spawning, migration), and other environmental factors. While 
we agree that some studies have demonstrated that airgun sounds might 
affect the distribution and behavior of some fishes, potentially 
impacting foraging opportunities or increasing energetic costs (e.g., 
Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski et al., 
1992; Santulli et al., 1999; Paxton et al., 2017), other studies have 
shown no or slight reaction to airgun sounds (e.g., Pena et al., 2013; 
Wardle et al., 2001; Jorgenson and Gyselman, 2009; Cott et al., 2012).
    In general, impacts to marine mammal prey are expected to be 
limited due to the relatively small temporal and spatial overlap 
between the proposed survey and any areas used by marine mammal prey 
species. The proposed activities would occur over a relatively short 
time period in a given area and would occur over a very small area 
relative to the area available as marine mammal habitat in Cook Inlet. 
We do not have any information to suggest the proposed survey area 
represents a significant feeding area for any marine mammal, and we 
believe any impacts to marine mammals due to adverse effects to their 
prey would be insignificant due to the limited spatial and temporal 
impact of the proposed activities. However, adverse impacts may occur 
to a few species of fish and to zooplankton. Packard et al. (1990) 
showed that cephalopods were sensitive to particle motion, not sound 
pressure, and Mooney et al. (2010) demonstrated that squid statocysts 
act as an accelerometer through which particle motion of the sound 
field can be detected. Auditory injuries (lesions occurring on the 
statocyst sensory hair cells) have been reported upon controlled 
exposure to low-frequency sounds, suggesting that cephalopods are 
particularly sensitive to low-frequency sound (Andre et al., 2011; Sole 
et al., 2013). However, these controlled exposures involved long 
exposure to sounds dissimilar to airgun pulses (i.e., 2 hours of 
continuous exposure to 1-second sweeps, 50-400 Hz). Behavioral 
responses, such as inking and jetting, have also been reported upon 
exposure to low-frequency sound (McCauley et al., 2000b; Samson et al., 
2014).
    Indirect impacts from spills or leaks could occur through the 
contamination of lower-trophic-level prey, which could reduce the 
quality and/or quantity of marine mammal prey. In addition, individuals 
that consume contaminated prey could experience long-term effects to 
health (Geraci and St. Aubin 1990). However, the likelihood of spills 
and leaks, as described above, is low. This likelihood, in combination 
with Hilcorp's spill plan to reduce the risk of hazardous material 
spills, is such that its effect on prey is not considered further in 
this document.
    Acoustic Habitat--Acoustic habitat is the soundscape--which 
encompasses all of the sound present in a particular location and time, 
as a whole--when considered from the perspective of the animals 
experiencing it. Animals produce sound for, or listen for sounds 
produced by, conspecifics

[[Page 12354]]

(communication during feeding, mating, and other social activities), 
other animals (finding prey or avoiding predators) and the physical 
environment (finding suitable habitats, navigating). Together, sounds 
made by animals and the geophysical environment (e.g., produced by 
earthquakes, lightning, wind, rain, waves) make up the natural 
contributions to the total acoustics of a place. These acoustic 
conditions, termed acoustic habitat, are one attribute of an animal's 
total habitat.
    Soundscapes are also defined by, and acoustic habitat influenced 
by, the total contribution of anthropogenic sound. This may include 
incidental emissions from sources such as vessel traffic or may be 
intentionally introduced to the marine environment for data acquisition 
purposes (as in the use of airgun arrays or other sources). 
Anthropogenic noise varies widely in its frequency content, duration, 
and loudness and these characteristics greatly influence the potential 
habitat-mediated effects to marine mammals (please see also the 
previous discussion on masking under ``Acoustic Effects''), which may 
range from local effects for brief periods of time to chronic effects 
over large areas and for long durations. Depending on the extent of 
effects to habitat, animals may alter their communications signals 
(thereby potentially expending additional energy) or miss acoustic cues 
(either conspecific or adventitious). For more detail on these concepts 
see, e.g., Barber et al., 2010; Pijanowski et al. 2011; Francis and 
Barber 2013; Lillis et al. 2014.
    Problems arising from a failure to detect cues are more likely to 
occur when noise stimuli are chronic and overlap with biologically 
relevant cues used for communication, orientation, and predator/prey 
detection (Francis and Barber 2013). Although the signals emitted by 
seismic airgun arrays are generally low frequency, they would also 
likely be of short duration and transient in any given area due to the 
nature of these surveys. Sub-bottom profiler use is also expected to be 
short term and not concentrated in one location for an extended period 
of time. The activities related to exploratory drilling, while less 
transitory in nature, are anticipated to have less severe effects due 
to lower source levels and therefore smaller disturbance zones than the 
mobile sources considered here. Nonetheless, we acknowledge the general 
addition of multiple sound source types into the area, which are 
expected to have intermittent impacts on the soundscape, typically of 
relatively short duration in any given area.
    In summary, activities associated with the proposed action are not 
likely to have a permanent, adverse effect on any fish habitat or 
populations of fish species or on the quality of acoustic habitat. 
Thus, any impacts to marine mammal habitat are not expected to cause 
significant or long-term consequences for individual marine mammals or 
their populations.

Estimated Take

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this proposed rule, which will 
inform both NMFS' consideration of ``small numbers'' and the negligible 
impact determination.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as: Any act of 
pursuit, torment, or annoyance which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would primarily be by Level B harassment, as use 
of seismic survey and construction equipment has the potential to 
result in disruption of behavioral patterns for individual marine 
mammals. There is also some potential for auditory injury (Level A 
harassment) to result from equipment such as seismic airguns, primarily 
for mysticetes and high frequency species, because predicted auditory 
injury zones are larger than for mid-frequency species and otariids. 
Auditory injury is unlikely to occur for mid-frequency cetaceans. The 
proposed mitigation and monitoring measures are expected to minimize 
the severity of such taking to the extent practicable.
    As described previously, no mortality is anticipated or proposed to 
be authorized for this activity. Below we describe how the take is 
estimated.
    Generally speaking, we estimate take by considering: (1) Acoustic 
thresholds above which NMFS believes the best available science 
indicates marine mammals will be behaviorally harassed or incur some 
degree of permanent hearing impairment; (2) the area or volume of water 
that will be ensonified above these levels in a day; (3) the density or 
occurrence of marine mammals within these ensonified areas; and, (4) 
and the number of days of activities. We note that while these basic 
factors can contribute to a basic calculation to provide an initial 
prediction of takes, additional information that can qualitatively 
inform take estimates is also sometimes available (e.g., previous 
monitoring results or average group size). Below, we describe the 
factors considered here in more detail and present the proposed take 
estimate.

Acoustic Thresholds

    Using the best available science, NMFS has developed acoustic 
thresholds that identify the received level of underwater sound above 
which exposed marine mammals would be reasonably expected to experience 
behavioral disturbance (equated to Level B harassment) or to incur PTS 
of some degree (equated to Level A harassment).
    Level B Harassment for non-explosive sources--Though significantly 
driven by received level, the onset of behavioral disturbance from 
anthropogenic noise exposure is also informed to varying degrees by 
other factors related to the source (e.g., frequency, predictability, 
duty cycle), the environment (e.g., bathymetry), and the receiving 
animals (hearing, motivation, experience, demography, behavioral 
context) and can be difficult to predict (Southall et al., 2007, 
Ellison et al., 2012). Based on the available science and the practical 
need to use a threshold based on a factor that is both predictable and 
measurable for most activities, NMFS uses a generalized acoustic 
threshold based on received level to estimate the onset of behavioral 
disturbance rising to the level of Level B Harassment. NMFS predicts 
that marine mammals are likely to experience behavioral disturbance 
sufficient to constitute Level B harassment when exposed to underwater 
anthropogenic noise above received levels of 120 dB re 1 [mu]Pa (rms) 
for continuous (e.g., vibratory pile-driving, drilling) and above 160 
dB re 1 [mu]Pa (rms) for non-explosive impulsive (e.g., seismic 
airguns) or intermittent (e.g., scientific sonar) sources.
    Hilcorp's proposed activity includes the use of continuous 
(vibratory pile driving, water jet) and impulsive (seismic airguns, 
sub-bottom profiler, conductor pipe driving, VSP) sources, and 
therefore the 120 and 160 dB re 1 [mu]Pa (rms) are applicable.
    Level A harassment for non-explosive sources--NMFS' Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual 
criteria to assess auditory injury

[[Page 12355]]

(Level A harassment) to five different marine mammal groups (based on 
hearing sensitivity) as a result of exposure to noise from two 
different types of sources (impulsive or non-impulsive). Hilcorp's 
proposed activity includes the use of impulsive (seismic airguns, sub-
bottom profiler, conductor pipe driving, VSP) and non-impulsive 
(vibratory pile driving, water jet) sources.
    These thresholds for PTS are provided in the table below. The 
references, analysis, and methodology used in the development of the 
thresholds are described in NMFS 2018 Technical Guidance, which may be 
accessed at: http://www.nmfs.noaa.gov/pr/acoustics/guidelines.htm.
BILLING CODE 3510-22-P
[GRAPHIC] [TIFF OMITTED] TP01AP19.000

BILLING CODE 3510-22-C

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and transmission loss 
coefficient.
    2D Seismic Survey--The area of ensonification for the 2D seismic 
survey was calculated by multiplying the distances (in km) to the NMFS 
thresholds (Level A harassment distances from the User spreadsheet and 
Level B harassment distances to the 160dB isopleth) on both sides of 
the vessel by the distance of the line (in km) to be surveyed each day. 
The in-water source line is 6 km in length and only one line will be 
surveyed each day. Therefore, the line length surveyed each day for the 
2D seismic survey is 6 km.
    3D Seismic Survey--The area of ensonification for the 3D seismic 
survey was calculated by multiplying the distances (in km) to the NMFS 
thresholds by the distance of the line (in km) to be surveyed each day. 
The line length is approximately 27.78 km (15 nm), which will take 
approximately 3.75 hrs to survey at a vessel speed of

[[Page 12356]]

4 knots (7.5 km/hr) with a turn of 1.5 hrs. In a 24-hr period, assuming 
no delays, the survey team will be able to collect data on 4.5 lines or 
approximately 127 km. The distance in between line lengths is 3.7 km (2 
nm), so there will be overlap of the area of Level B ensonification, 
resulting in an overestimation of exposures. Instead, the total daily 
area of ensonification was calculated using GIS. The Level B radii were 
added to each track line estimated to be traveled in a 24-hour period, 
and when there was overlapping areas, the resulting polygons were 
merged to one large polygon to eliminate the chance that the areas 
could be summed multiple times over the same area. The results of the 
overall area are summarized in Table 6 below and shown on Figure 19 in 
the application (only showing Level B).
    Geohazard Sub-bottom Profiler for Well Sites--The area of 
ensonification for the sub-bottom profiler used during the geohazard 
surveys for the well sites was calculated by multiplying the distances 
(in km) to the NMFS thresholds by the distance of the line (in km) to 
be surveyed each day. The maximum required monitoring distance from the 
well site per BOEM is 2,400 m (or a total length of 4,800 m in 
diameter) and the minimum transect width is 150 m, so the total maximum 
number of transects to be surveyed is 32 (4,800 m/150 m). The total 
distance to be surveyed is 153.60 km (4.8 km x 32 transects). Assuming 
a vessel speed of 4 knots (7.41 km/hr), it will take approximately 0.65 
hrs (38 minutes) to survey a single transect of 4.8 km (time = 
distance/rate). Assuming the team is surveying for 50 percent of the 
day (or 12 hrs), the total number of days it will take to survey the 
total survey grid is 7.77 days (0.65 hr x 12 hr). Similar to the 3D 
seismic survey, there will be overlap in the Level B ensonification of 
the sound because of the distance in between the transects. However, 
because the area and grid to be surveyed depends on the results of the 
3D survey and the specific location, Hilcorp Alaska proposes to use 
this overestimate for purposes of this proposed rulemaking. The total 
line length to be surveyed per day is 19.76 km (total distance to be 
surveyed 153.6 km/total days 7.77).
    Geohazard Sub-bottom Profiler for Pipeline Maintenance--The area of 
ensonification for the sub-bottom profiler used during geohazard 
surveys for the pipeline maintenance was calculated by multiplying the 
distances (in km) to the NMFS thresholds by the distance of the line 
(in km) to be surveyed each day. The assumed transect grid is 300 m by 
300 m with 150 m transect widths, so the total to be surveyed is 2,400 
m (2.4 km). Assuming a vessel speed of 4 knots (7.41 km/hr), it will 
take approximately 0.08 hrs (4.86 min) to survey a single transect. The 
total number of days it will take to survey the grid is 1 day. Similar 
to the 3D seismic survey, there will be overlap of the Level B 
ensonification area because of the distance in between the transects. 
However, because the area and grid to be surveyed depends on the 
results of the 3D survey and the specific location, Hilcorp Alaska 
proposes to use this overestimate for purposes of this proposed rule. 
The total line length to be surveyed per day is 2.4 km.
    Other sources--For stationary sources, area of a circle to the 
relevant Level A or Level B harassment isopleths was used to determine 
ensonified area. These sources include: Conductor pipe driving, VSP, 
vibratory sheet pile driving, and water jets.
    When the NMFS Technical Guidance (2016) was published, in 
recognition of the fact that ensonified area/volume could be more 
technically challenging to predict because of the duration component in 
the new thresholds, we developed a User Spreadsheet that includes tools 
to help predict a simple isopleth that can be used in conjunction with 
marine mammal density or occurrence to help predict takes by Level A 
harassment. We note that because of some of the assumptions included in 
the methods used for these tools, we anticipate that isopleths produced 
are typically going to be overestimates of some degree, which may 
result in some degree of overestimate of Level A harassment take. 
However, these tools offer the best way to predict appropriate 
isopleths when more sophisticated 3D modeling methods are not 
available; and NMFS continues to develop ways to quantitatively refine 
these tools and will qualitatively address the output where 
appropriate. For stationary sources such as conductor pipe driving or 
vibratory pile driving, NMFS User Spreadsheet predicts the closest 
distance at which, if a marine mammal remained at that distance the 
whole duration of the activity, it would not incur PTS. For mobile 
sources such as seismic airguns or sub-bottom profilers, the User 
Spreadsheet predicts the closest distance at which a stationary animal 
would not incur PTS if the sound source traveled by the animal in a 
straight line at a constant speed. Inputs used in the User Spreadsheet, 
and the resulting isopleths are reported below (Tables 4, 5, and 6). 
Transmission loss used for all calculation was practical spreading (15 
LogR).

                                                          Table 4--NMFS User Spreadsheet Inputs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      Weighting
           Activity             Type of source     Source level        factor          Source         Pulse        Repetition rate      Duration per day
                                                                     adjustment       velocity       duration
--------------------------------------------------------------------------------------------------------------------------------------------------------
2D/3D seismic................  mobile,           217 dB peak @100  1 kHz.........  2.05 m/s......  N/A........  every 6 s............  N/A.
                                impulsive.        m; 185 dB SEL
                                                  @100 m.
Sub-bottom profiler..........  mobile,           212 dB rms @1 m.  4 kHz.........  2.05 m/s......  0.02 s.....  every 0.30 s.........  N/A.
                                impulsive.
Pipe driving.................  stationary,       195 dB rms @55 m  2 kHz.........  N/A...........  0.02 s.....  600 strikes/hr.......  2 hrs/day.
                                impulsive.
VSP..........................  stationary,       227 dB rms @1m..  1 kHz.........  N/A...........  0.02 s.....  Every 6 s............  4 hrs/day.
                                impulsive.
Vibratory sheet pile driving.  stationary, non-  160 dB rms @10 m  2.5 kHz.......  N/A...........  N/A........  N/A..................  4 hrs/day.
                                impulsive.
Water jet....................  stationary, non-  176 dB rms @1 m.  2 kHz.........  N/A...........  N/A........  N/A..................  0.5 hrs/day.
                                impulsive.
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 12357]]


                                                               Table 5--Calculated Distances to NMFS Level A Harassment Thresholds
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                Level A
                                      ----------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Low frequency cetaceans        Mid frequency cetaceans        High frequency cetaceans               Phocids                        Otariids
                                      ----------------------------------------------------------------------------------------------------------------------------------------------------------
               Activity                    Impulsive         Non-         Impulsive         Non-         Impulsive         Non-         Impulsive         Non-         Impulsive         Non-
                                      ------------------  impulsive  ------------------  impulsive  ------------------  impulsive  ------------------  impulsive  ------------------  impulsive
                                        219 dB   183 dB -------------  230 dB   185 dB -------------  202 dB   155 dB -------------  218 dB   185 dB -------------  232 dB   203 dB ------------
                                          pk      SEL     199 dB SEL     pk      SEL     198 dB SEL     pk      SEL     173 dB SEL     pk      SEL     201 dB SEL     pk      SEL     219 dB SEL
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
2D/3D seismic........................       74      399  ...........       14       <1  ...........    1,000       45  ...........       86       66  ...........       10        1  ...........
Sub-bottom profiler..................       <1       77  ...........       <1        4  ...........        5    1,108  ...........       <1       48  ...........       <1       <1  ...........
Pipe driving.........................        1      134  ...........       <1      103  ...........       19    3,435  ...........        2    1,543  ...........       <1      112  ...........
VSP..................................        3   11,217  ...........       <1       96  ...........       46    2,617  ...........        4    3,371  ...........       <1      249  ...........
Vibratory sheet pile driving.........  .......  .......           15  .......  .......            1  .......  .......           22  .......  .......            9  .......  .......           <1
Water jet............................  .......  .......           14  .......  .......           <1  .......  .......           13  .......  .......            8  .......  .......            1
Hydraulic grinder....................  .......  .......            1  .......  .......           <1  .......  .......            1  .......  .......           <1  .......  .......           <1
Tugs towing..........................  .......  .......           <1  .......  .......           <1  .......  .......           <1  .......  .......           <1  .......  .......           <1
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


        Table 6--Calculated Distances to NMFS Level B Thresholds
------------------------------------------------------------------------
                                                   Level B
                                   -------------------------------------
             Activity                   Impulsive        Non-impulsive
                                   -------------------------------------
                                        160 dB rms         120 dB rms
------------------------------------------------------------------------
2D/3D seismic.....................              7,330  .................
Sub-bottom profiler...............              2,929  .................
Pipe driving......................              1,630  .................
VSP...............................              2,470  .................
Vibratory sheet pile driving......  .................              4,642
Water jet.........................  .................              5,411
Hydraulic grinder.................                 <1                398
Tugs towing.......................  .................              2,514
------------------------------------------------------------------------

Marine Mammal Occurrence

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations.
    Beluga whale--Historically, beluga whales were observed in both 
upper and lower Cook Inlet in June and July (Rugh et al. 2000). 
However, between 1993 and 1995, less than 3 percent of all of the 
annual sightings were in the lower inlet, south of the East and West 
Forelands, hardly any (one whale in Tuxedni Bay in 1997 and two in 
Kachemak Bay in 2001) have been seen in the lower inlet during these 
surveys 1996-2016 (Rugh et al. 2005; Shelden et al. 2013, 2015, 2017). 
Because of the extremely low sighting rates, it is difficult to provide 
an accurate estimate of density for beluga whales in the mid and lower 
Cook Inlet region.
    Goetz et al. (2012b) developed a habitat-based model to estimate 
Cook Inlet beluga density based on seasonally collected data. The model 
was based on sightings, depth soundings, coastal substrate type, 
environmental sensitivity index, anthropogenic disturbance, and 
anadromous fish streams to predict densities throughout Cook Inlet. The 
result of this work is a beluga density map of Cook Inlet, which 
predicts spatially explicit density estimates for Cook Inlet belugas. 
Figure 1 shows the Goetz et al. (2012b) estimates with the project 
area. Using data from the GIS files provided by NMFS and the different 
project locations, the resulting estimated density is shown in Table 7. 
The water jets would be used on pipelines throughout the middle Cook 
Inlet region, so the higher density for the Trading Bay area was used.
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    Densities resulting from this model are summarized in Table 7 
below.

  Table 7--Cook Inlet Beluga Whale Density Based on Goetz Habitat Model
------------------------------------------------------------------------
                                                    Beluga whale density
       Project location          Project activity        (ind/km\2\)
------------------------------------------------------------------------
Lower Cook Inlet (OCS)........  3D seismic,                         0.00
                                 geohazard, pipe
                                 driving.
Lower Cook Inlet (east side)..  2D seismic........         0.00-0.011106
Iniskin Bay area..............  Sheet pile driving              0.024362
North Cook Inlet Unit.........  Geohazard, pipe                 0.001664
                                 driving.
Trading Bay area..............  Geohazard, pipe        0.004453-0.015053
                                 driving, water
                                 jets.
------------------------------------------------------------------------

    Other Marine Mammals--Density estimates of species other than 
beluga whales were estimated from the NMFS June aerial surveys 
conducted for beluga whales between 2000 and 2016 (Rugh et al. 2005; 
Shelden et al. 2013, 2015, 2017). Although these surveys are only flown 
for a few days in one month, they represent the best available 
relatively long-term dataset for marine mammal sightings in Cook Inlet. 
Table 8 below summarizes the maximum marine mammals observed for each 
year for the survey and area covered. To estimate density, the total 
number of individuals per species sighted during surveys was divided by 
the distance flown on the surveys. The total number of animals observed 
accounts for both lower and upper Cook Inlet, so this density estimate 
is higher than what is anticipated for the lower Cook Inlet area. There 
are no density estimates available for California sea lions for Cook 
Inlet so largest potential group size was used.

      Table 8--Density Estimates for Marine Mammals in Action Area
------------------------------------------------------------------------
                                                       Estimated density
                       Species                         (# marine mammals/
                                                           km\2\) \3\
------------------------------------------------------------------------
Beluga whale:
    Lower and Middle Cook Inlet \1\..................            0.00006
    Lower Cook Inlet \2\.............................            0.01111
    North Cook Inlet Unit \2\........................            0.00166
    Trading Bay area \2\.............................            0.01505
    Iniskin Peninsula \2\............................            0.02436
Humpback whale.......................................            0.00009
Minke whale..........................................            0.00000
Gray whale...........................................            0.00001
Fin whale............................................            0.00005
Killer whale.........................................            0.00011
Dall's porpoise......................................            0.00006
Harbor porpoise......................................            0.00037
Harbor seal..........................................            0.00655
Steller sea lion.....................................            0.00035
------------------------------------------------------------------------
\1\ NMFS aerial survey combined lower and middle Cook Inlet density.
\2\ Goetz et al. 2012(b) habitat-based model density.
\3\ When using data from NMFS aerial surveys, the survey year with the
  greatest calculated density was used to calculate exposures.
No density available for California sea lions in Cook Inlet.

Duration

    The duration was estimated for each activity and location. For some 
projects, like the 3D seismic survey, the design of the project is well 
developed; therefore, the duration is well-defined. However, for some 
projects, the duration is not well developed, such as activities around 
the lower Cook Inlet well sites, because the duration depends on the 
results of previous studies and equipment availability. Our assumptions 
regarding these activities, which were used to estimate duration, are 
discussed below.
    2D Seismic--A single vessel is capable of acquiring a source line 
in approximately 1-2 hrs and only one source line will be collected in 
one day to allow for all the node deployments and retrievals, and 
intertidal and land zone shot holes drilling. There are up to 10 source 
lines, so assuming all operations run smoothly, there will only be 2 
hrs per day over 10 days of airgun activity. The duration that was used 
to assess exposures from the 2D seismic survey is 10 days.
    3D Seismic--The total anticipated duration of the survey is 45-60 
days, including delays due to equipment, weather, tides, and marine 
mammal shut downs. The duration that was used to assess exposures from 
the 3D seismic survey is 60 days.
    Geohazard Surveys (Sub-bottom profiler)--Assuming surveying occurs 
50 percent of the day (or 12 hrs), the total number of days it will 
take to survey the total geohazard survey grid for a single well is 
7.77 days. This duration was multiplied by the number of wells per site 
resulting in 31.1 days for the four Lower Cook Inlet OCS wells, 7.7 
days for the North Cook Inlet Unit well, and 15.5 days for the two 
Trading Bay area wells.
    The total number of days it will take to survey the geohazard 
survey grid for a pipeline maintenance is 1 day. This duration was 
multiplied by the number of anticipated surveys per year (high estimate 
of 3 per year), for a total of 3 days.
    Drive Pipe--It takes approximately 3 days to install the drive pipe 
per well with only 25 percent of the day necessary for actual pipe 
driving. This duration was multiplied by the number

[[Page 12360]]

of wells per site resulting in 3 days for the four lower Cook Inlet 
wells and 1.5 days for the two Trading Bay area wells. Drive pipe 
installation is not part of the activities planned at the North Cook 
Inlet site.
    VSP--It takes approximately 2 days to perform the VSP per well with 
only 25 percent of the day necessary for actual seismic work. VSP is 
not part of the plugging and abandonment (P&A) activities at the North 
Cook Inlet site. This duration was multiplied by the number of wells 
per site, resulting in 2 days for the four lower Cook Inlet wells and 1 
day for the two Trading Bay area wells.
    Vibratory Sheet Pile Driving--The total number of days expected to 
install the sheet pile dock face using vibratory hammers on the rock 
causeway is 14 days with only 25 percent of the day for actual pile 
driving, resulting in 3.5 days of sound for the Iniskin project.
    Water jets--Water jets are only used when needed for maintenance; 
therefore, the annual duration was estimated to evaluate exposures. 
Each water jet event was estimated to be 30 minutes or less in 
duration. We acknowledge that due to the short duration of this 
activity, it is possible that take will not occur--however, we are 
including consideration of potential take to conservatively ensure 
coverage for the applicant. It was estimated that a water jet event 
occurs 3 times a month, resulting in only 1.5 hrs per month of water 
jet operation. Water jets are used during ice-free months, so this 
duration was multiplied by 7 months (May-November) resulting in 10.5 
days.

Take Calculation and Estimation

    Here we describe how the information provided above is brought 
together to produce a quantitative take estimate. The numbers of each 
marine mammal species that could potentially be exposed to sounds 
associated with the proposed activities that exceed NMFS' acoustic 
Level A and B harassment criteria were estimated per type of activity 
and per location. The specific years when these activities might occur 
are not known at this time, so this method of per activity per location 
allows for flexibility in operations and provides NMFS with appropriate 
information for assessing potential exposures. Individual animals may 
be exposed to received levels above our harassment thresholds more than 
once per day, but NMFS considers animals only ``taken'' once per day. 
Exposures refer to any instance in which an animal is exposed to sound 
sources above NMFS' Level A or Level B harassment thresholds. The 
estimated exposures (without any mitigation) per activity per location 
were calculated by multiplying the density of marine mammals (# of 
marine mammals/km\2\) by the area of ensonification (km\2\) and the 
duration (days per year). These results of these calculations are 
presented in Tables 9 and 10 below.

                                                            Table 9--Estimated Number of Level A Exposures per Activity and Location
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  3D         2D      Iniskin                          Sub-bottom profiler                 Pipe driving        Vertical seismic
                                                               seismic    seismic   vibratory            ------------------------------------------------------------------       profiling
                                                             ----------------------   sheet      Water                                                                     ---------------------
                           Species                                                     pile     jets \6\
                                                               LCI \1\    LCI \1\  -----------             MCI \4\    LCI \1\    NCI \2\     TB \3\    LCI \1\     TB \3\    LCI \1\     TB \3\
                                                                                     LCI \1\
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale..............................................       6.80       0.05       0.00       0.00       0.00       0.09       0.02       0.04       0.00       0.00       5.97       2.98
Minke whale.................................................       0.04       0.00       0.00       0.00       0.00       0.00       0.00       0.00       0.00       0.00       0.03       0.02
Gray whale..................................................       0.29       0.00       0.00       0.00       0.00       0.00       0.00       0.00       0.00       0.00       0.25       0.13
Fin whale...................................................       1.19       0.01       0.00       0.00       0.00       0.02       0.00       0.01       0.00       0.00       1.05       0.52
Killer whale................................................       0.07       0.00       0.00       0.00       0.00       0.00       0.00       0.00       0.00       0.00       0.00       0.00
Beluga whale................................................       0.00       0.01       0.00       0.00       0.00       0.00       0.00       0.02       0.00       0.00       0.00       0.00
Dall's porpoise.............................................       1.31       0.01       0.00       0.00       0.00       0.11       0.03       0.06       0.00       0.00       0.03       0.01
Harbor porpoise.............................................      37.25       0.29       0.00       0.00       0.04       3.20       0.80       1.60       0.00       0.00       0.81       0.40
Harbor seal.................................................     287.11       2.26       0.00       0.00       0.09       7.39       1.85       3.69       0.05       0.02       5.80       2.90
Steller sea lion............................................       0.70       0.01       0.00       0.00       0.00       0.00       0.00       0.00       0.00       0.00       0.01       0.01
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ LCI--Lower Cook Inlet Wells, \2\ NCI--North Cook Inlet Unit well, \3\ TB = Trading Bay wells, \4\ MCI--Middle Cook Inlet Pipeline Maintenance.


                                                            Table 10--Estimated Number of Level B Exposures per Activity and Location
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  3D         2D      Iniskin                          Sub-bottom profiler                 Pipe driving        Vertical seismic
                                                               seismic    seismic   vibratory            ------------------------------------------------------------------       profiling
                                                             ----------------------   sheet      Water                                                                     ---------------------
                           Species                                                     pile     jets \6\
                                                               LCI \1\    LCI \1\  -----------             MCI \4\    LCI \1\    NCI \2\     TB \3\    LCI \1\     TB \3\    LCI \1\     TB \3\
                                                                                     LCI \1\
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale..............................................      85.43       0.83       0.64       0.01       0.04       3.40       0.85       1.70       0.05       0.02       0.07       0.04
Minke whale.................................................       0.45       0.00       0.00       0.00       0.00       0.02       0.00       0.01       0.00       0.00       0.00       0.04
Gray whale..................................................       3.60       0.04       0.03       0.00       0.00       0.14       0.04       0.07       0.00       0.00       0.00       0.04
Fin whale...................................................      14.99       0.15       0.11       0.00       0.01       0.60       0.15       0.30       0.01       0.00       0.01       0.04
Killer whale................................................      29.02       0.28       0.22       0.00       0.01       1.15       0.29       0.58       0.02       0.01       0.02       0.04
Beluga whale................................................       0.00       0.00       8.24       0.05       0.00       0.00       0.75      13.54       0.00       0.19       0.00       0.04
Dall's porpoise.............................................       7.42       0.07       0.06       0.00       0.00       0.30       0.07       0.15       0.00       0.00       0.01       0.04
Harbor porpoise.............................................     211.70       2.06       1.58       0.02       0.10       8.42       2.10       4.21       0.12       0.06       0.18       0.04
Harbor seal.................................................  11,255.01     109.38      84.17       0.83       5.24     447.52     111.88     223.76       6.23       3.11       9.53       0.04
Steller sea lion............................................     366.99       3.57       2.74       0.03       0.17      14.59       3.65       7.30       0.20       0.10       0.31       0.04
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ LCI--Lower Cook Inlet Wells, \2\ NCI--North Cook Inlet Unit well, \3\ TB = Trading Bay wells, \4\ MCI--Middle Cook Inlet Pipeline Maintenance.

    The take estimates by activity and location discussed in the 
previous section are not representative of the estimated takes per year 
(i.e., annual takes). It is difficult to characterize each year 
accurately because many of the activities are progressive (i.e., they 
depend on results and/or completion of the previous activity). This 
results in much uncertainty in the timing, duration, and complete scope 
of work. Each year, the applicant will submit an application for an LOA 
with the specific details of the planned work for that year with 
estimated take numbers. The most realistic scenario used to estimate 
annual takes includes 3D seismic surveys in the first season, 
activities for one well in the second season in lower Cook Inlet, as 
well as the plugging and abandonment activities in North Cook Inlet 
Unit and the two wells in the Trading Bay area. For the third season, 
we have included activities for drilling

[[Page 12361]]

two wells in lower Cook Inlet and the final well in the fourth season. 
Table 17 summarizes the activities included in this second scenario.

           Table 11--Summary of Activities Considered by Year
------------------------------------------------------------------------
             Year                    Activity               Area
------------------------------------------------------------------------
May 2019-2020.................  3D seismic.......  LCI.
                                Geohazard........  LCI.
                                Sheet pile         Iniskin (LCI).
                                 driving.
                                Pipeline           MCI.
                                 maintenance
                                 (geohazard,
                                 water jet,
                                 grinder).
April 2020-2021...............  Drilling           LCI.
                                 activities
                                 (tugs,
                                 geohazard, pipe
                                 driving, VSP) at
                                 all 1 well.
                                Drilling           TB.
                                 activities
                                 (tugs,
                                 geohazard, pipe
                                 driving, VSP) at
                                 2 wells.
                                P&A activities     NCI.
                                 (tugs,
                                 geohazard) at 1
                                 well.
                                Pipeline           MCI
                                 maintenance
                                 (geohazard,
                                 water jet,
                                 grinder).
April 2021-2022...............  Drilling           LCI.
                                 activities
                                 (tugs,
                                 geohazard, pipe
                                 driving, VSP) at
                                 2wells.
                                2D seismic.......  LCI.
                                Pipeline           MCI.
                                 maintenance
                                 (geohazard,
                                 water jet,
                                 grinder).
April 2022-2023...............  Drilling           LCI.
                                 activities
                                 (tugs,
                                 geohazard, pipe
                                 driving, VSP) at
                                 1 well.
                                Pipeline           MCI.
                                 maintenance
                                 (geohazard,
                                 water jet,
                                 grinder).
April 2023-2024...............  Pipeline           MCI.
                                 maintenance
                                 (geohazard,
                                 water jet,
                                 grinder).
------------------------------------------------------------------------
LCI--Lower Cook Inlet Wells, NCI--North Cook Inlet Unit well, TB =
  Trading Bay wells, MCI--Middle Cook Inlet Pipeline Maintenance.


                                                                    Table 12--Estimated Exposures for First Year of Activity
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         Level A                                                            Level B
                                                           -------------------------------------------------------------------------------------------------------------------------------------
                          Species                               MCI        MCI                 LCI sub-  LCI sheet                 MCI        MCI                 LCI sub-  LCI sheet
                                                             pipeline    pipeline    LCI 3D     bottom      pile      Total     pipeline    pipeline    LCI 3D     bottom      pile      Total
                                                             geohazard  water jet   seismic    profiler   driving               geohazard  water jet   seismic    profiler   driving
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale............................................           0          0        6.8       0.09          0       6.89        0.04       0.15      85.43        3.4       2.56      91.57
Minke whale...............................................           0          0       0.04          0          0       0.04           0          0       0.45       0.02       0.01       0.48
Gray whale................................................           0          0       0.29          0          0       0.29           0       0.01       3.60       0.14       0.11       3.86
Fin whale.................................................           0          0       0.29       0.02          0       0.31        0.01       0.03       3.60       0.60       0.45       4.68
Killer whale..............................................           0          0       1.19          0          0       1.19        0.01       0.05      14.99       1.15       0.87      17.08
Beluga whale..............................................           0          0          0          0          0          0           0        1.2          0          0      32.98      34.18
Dall's porpoise...........................................           0          0       1.31       0.11          0       1.42           0       0.01       7.42        0.3       0.22       7.95
Harbor porpoise...........................................        0.04          0      37.25        3.2          0      40.49         0.1       0.37     211.70       8.42       6.33     226.92
Harbor seal...............................................        0.09          0     287.11       7.39          0     294.58        5.24      19.85   11255.01     447.52     336.67   12064.29
Steller sea lion..........................................           0          0        0.7          0          0        0.7        0.17       0.65     366.99      14.59      10.98     393.38
California sea lion.......................................           0          0          0          0          0          0           0          0          0          0          0          0
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


                                                                    Table 13--Estimated Exposures for Second Year of Activity
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                      Level A                                                          Level B
                                                               ----------------------------------------------------             ----------------------------------------------------
                                                                                              LCI                                                              LCI
                                                                                           geohazard,                                                       geohazard,
                                                                    MCI          MCI          pipe                                   MCI          MCI          pipe
                                                                  pipeline     pipeline     driving,                               pipeline     pipeline     driving,
                                                                 geohazard    water jet   VSP (1 well                             geohazard    water jet   VSP (1 well
                                                                                             only)                                                            only)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale................................................            0            0         1.51  ...........  ...........         0.04         0.15         0.97  ...........  ...........
Minke whale...................................................            0            0         0.01  ...........  ...........            0            0         0.01  ...........  ...........
Gray whale....................................................            0            0         0.06  ...........  ...........            0         0.01         0.04  ...........  ...........
Fin whale.....................................................            0            0         0.27  ...........  ...........         0.01         0.03         0.17  ...........  ...........
Killer whale..................................................            0            0            0  ...........  ...........         0.01         0.05         0.33  ...........  ...........
Beluga whale..................................................            0            0            0  ...........  ...........            0          1.2            0  ...........  ...........
Dall's porpoise...............................................            0            0         0.04  ...........  ...........            0         0.01         0.08  ...........  ...........
Harbor porpoise...............................................         0.04            0            1  ...........  ...........         0.10         0.37          2.4  ...........  ...........
Harbor seal...................................................         0.09            0         3.31  ...........  ...........         5.24        19.85       127.64  ...........  ...........
Steller sea lion..............................................            0            0            0  ...........  ...........         0.17         0.65         4.16  ...........  ...........
California sea lion...........................................            0            0            0  ...........  ...........            0            0            0  ...........  ...........
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                      Level A                          Subtotal                                                         Subtotal
                                                                                                                        for all                                                          for all
                                                                                                                     activities                        Level B                        activities
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                        NCI           TB      TB pipe       TB VSP                       NCI           TB      TB pipe       TB VSP
                                                                  geohazard    geohazard      driving                              geohazard    geohazard      driving
                                                                   (1 well)    (2 wells)    (2 wells)                               (1 well)    (2 wells)    (2 wells)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale................................................          .02          .04            0         2.98         4.57         0.85          1.7         0.09         0.14         3.95
Minke whale...................................................            0            0            0         0.02         0.02            0         0.01            0            0         0.02
Gray whale....................................................            0            0            0         0.13         0.19         0.04         0.07            0         0.01         0.17
Fin whale.....................................................            0         0.01            0         0.52          0.8         0.15          0.3         0.02         0.03         0.69
Killer whale..................................................            0            0            0            0            0         0.85         0.58         0.03         0.05          1.9
Beluga whale..................................................         0.02         0.02            0            0         0.04         0.85        13.54         0.75         1.15         17.5

[[Page 12362]]

 
Dall's porpoise...............................................         0.02         0.06            0         0.01         0.13         0.85         0.15         0.01         0.01         1.12
Harbor porpoise...............................................         0.02          1.6            0          0.4         3.07         0.85         4.21         0.23         0.36         8.52
Harbor seal...................................................         0.02         3.69         0.02          2.9        10.04         0.85       223.76        12.46        19.07       408.87
Steller sea lion..............................................         0.02            0            0         0.01         0.03         0.85          7.3         0.41         0.62        14.15
California sea lion...........................................            0            0            0            0            0            0            0            0            0            0
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


                                                                    Table 14--Estimated Exposures for Third Year of Activity
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                      Level A                                                          Level B
                                                               ----------------------------------------------------             ----------------------------------------------------
                                                                                              LCI                                                              LCI
                                                                                           geohazard,                                                       geohazard,
                                                                    MCI          MCI          pipe        LCI 2D       Total         MCI          MCI          pipe        LCI 2D       Total
                                                                  pipeline     pipeline     driving,     seismic                   pipeline     pipeline     driving,     seismic
                                                                 geohazard    water jet      VSP (2                               geohazard    water jet      VSP (2
                                                                                          wells only)                                                      wells only)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale................................................            0            0         3.03         0.05         3.08         0.04         0.15         1.94         0.83         2.96
Minke whale...................................................            0            0         0.02            0         0.02            0            0         0.01            0         0.02
Gray whale....................................................            0            0         0.13            0         0.13            0         0.01         0.08         0.04         0.12
Fin whale.....................................................            0            0         0.53         0.01         0.54         0.01         0.03         0.34         0.15         0.52
Killer whale..................................................            0            0            0            0            0         0.01         0.05         0.66         0.28         1.01
Beluga whale..................................................            0            0            0         0.01         0.01            0          1.2            0          4.8         6.09
Dall's porpoise...............................................            0            0         0.07         0.01         0.08            0         0.01         0.17         0.07         0.26
Harbor porpoise...............................................         0.04            0            2         0.29         2.34          0.1         0.37          4.8         2.06         7.33
Harbor seal...................................................         0.09            0         6.62         2.26         8.97         5.24        19.85       255.28       109.38       389.76
Steller sea lion..............................................            0            0         0.01         0.01         0.01         0.17         0.65         8.32         3.57        12.71
California sea lion...........................................            0            0            0            0            0            0            0            0            0            0
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


                                                Table 15--Estimated Exposures for Fourth Year of Activity
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Level A                                             Level B
                                                 ---------------------------------------             ---------------------------------------
                                                                                LCI                                                 LCI
                                                                             geohazard,                                          geohazard,
                                                      MCI          MCI          pipe        Total         MCI          MCI          pipe        Total
                                                    pipeline     pipeline     driving,                  pipeline     pipeline     driving,
                                                   geohazard    water jet   VSP (1 well                geohazard    water jet   VSP (1 well
                                                                               only)                                               only)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale..................................            0            0         1.51         1.52         0.04         0.15         0.97         1.16
Minke whale.....................................            0            0         0.01         0.01            0            0         0.01         0.01
Gray whale......................................            0            0         0.06         0.06            0         0.01         0.04         0.05
Fin whale.......................................            0            0         0.27         0.27         0.01         0.03         0.17          0.2
Killer whale....................................            0            0            0            0         0.01         0.05         0.33         0.39
Beluga whale....................................            0            0            0            0            0          1.2            0          1.2
Dall's porpoise.................................            0            0         0.04         0.04            0         0.01         0.08         0.10
Harbor porpoise.................................         0.04            0            1         1.04          0.1         0.37         2.40         2.87
Harbor seal.....................................         0.09            0         3.31         3.40         5.24        19.85       127.64       152.74
Steller sea lion................................            0            0            0            0         0.17         0.65         4.16         4.98
California sea lion.............................            0            0            0            0            0            0            0            0
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                                Table 16--Estimated Exposures for Fifth Year of Activity
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              Level A                                         Level B
                                                         -----------------------------------------------------------------------------------------------
                                                           MCI pipeline    MCI pipeline                    MCI pipeline    MCI pipeline
                                                             geohazard       water jet         Total         geohazard       water jet         Total
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale..........................................               0               0               0            0.04            0.15            0.19
Minke whale.............................................               0               0               0               0               0               0
Gray whale..............................................               0               0               0               0            0.01            0.01
Fin whale...............................................               0               0               0            0.01            0.03            0.03
Killer whale............................................               0               0               0            0.01            0.05            0.06
Beluga whale............................................               0               0               0               0             1.2             1.2
Dall's porpoise.........................................               0               0               0               0            0.01            0.02
6.09+Harbor porpoise....................................            0.04               0            0.04             0.1            0.37            0.47
Harbor seal.............................................            0.09               0            0.09            5.24           19.85           25.10
Steller sea lion........................................               0               0               0            0.17            0.65            0.82
California sea lion.....................................               0               0               0               0               0               0
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 12363]]


                        Table 17--Estimated Maximum Exposures That May Be Authorized in One Year, Based on First Year of Activity
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Level A                                                 Level B
                                         ---------------------------------------------------------------------------------------------------------------
                 Species                       Total           Total        Percent of         Total           Total
                                            calculated      authorized         stock        calculated      authorized           Percent of stock
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale..........................            6.89               7            0.63           91.57              92  8.31
Minke whale.............................            0.04               0               0            0.48               1  0.08
Gray whale..............................            0.29               0               0            3.86               4  0.02
Fin whale...............................            0.31               0               0            4.68               5  0.16
Killer whale............................            1.19               0               0           17.08              17  0.72 (resident) or 2.90
                                                                                                                           (transient)
Beluga whale............................               0               0               0           34.18              30  9.62
Dall's porpoise.........................            1.42               2          0.0024            7.95               8  0.01
Harbor porpoise.........................           40.49              40            0.13          226.92             227  0.73
Harbor seal.............................          294.58             295             1.1        12064.29           6,000  21.91
Steller sea lion........................             0.7               1               0          393.38             394  0.74
California sea lion.....................               0               0               0               0               5  0
--------------------------------------------------------------------------------------------------------------------------------------------------------


                 Table 18--Total Exposures Calculated and Requested Over the 5-year Regulations
----------------------------------------------------------------------------------------------------------------
                                                       Calculated Exposures            Authorized Exposures
             Group                   Species     ---------------------------------------------------------------
                                                      Level A         Level B         Level A         Level B
----------------------------------------------------------------------------------------------------------------
LF Cetaceans..................  Humpback whale..           16.06           99.82              16             100
                                Minke whale.....            0.08            0.53               0               5
                                Gray whale......            0.68            4.21               0               5
                                Fin whale.......            1.91            6.93               0               7
MF Cetaceans..................  Killer whale....             0.2           20.44               0              20
                                Beluga whale....            0.05           60.17               0              35
HF Cetaceans..................  Dall's porpoise.            1.67            9.45               5              10
                                Harbor porpoise.           46.97          246.12              47             246
Phocids.......................  Harbor seal.....          317.07        13040.77             317            6847
Otariids......................  Steller sea lion            0.76          426.04               5             426
                                California sea                 0               0               0               5
                                 lion.
----------------------------------------------------------------------------------------------------------------

    Based on the results of the acoustic harassment analysis, Hilcorp 
Alaska is requesting a small number of takes by Level A harassment for 
humpback whales, Dall's porpoises, harbor porpoises, Steller sea lions, 
and harbor seals. Hilcorp Alaska does not anticipate that any of the 
activities will result in mortality or serious injury to marine 
mammals, but these species may be exposed to levels exceeding the Level 
A harassment thresholds. Seals are highly curious and exhibit high 
tolerance for anthropogenic activity, so they are likely to enter 
within the larger Level A harassment isopleths. Porpoises are difficult 
to observer at greater distances and usually only remain in an area for 
a short period of time. The total requested takes by Level A harassment 
are for 16 humpback whales, 5 Dall's porpoises, 47 harbor porpoises, 
and 317 harbor seals. Note this is not a request for annual takes, but 
total takes over the 5-year period.
    The requested takes by Level B harassment for minke and gray whale 
are rounded up to 5 animals, based on the assumption that one could be 
taken per year for five years. The requested takes by Level B 
harassment for humpback whales is 100 animals, although it is not 
expected to approach this number as humpbacks are easily observable 
during monitoring efforts. The requested takes by Level B harassment 
for killer whales are rounded up to 20 animals to allow for small 
groups. The requested takes by Level B harassment for Dall's and harbor 
porpoise are rounded up to 10 and 246 animals, respectively, due to the 
inconspicuous nature of porpoises.
    The requested takes by Level B harassment for harbor seals is 6,847 
animals. The estimated number of instances of takes by Level B 
harassment of 13,041 resulting from the calculations outlined above is 
an overestimate due to the inclusion of haul out sites numbers in the 
underlying density estimate used to calculate take. Using the daily 
ensonified area x number of survey days x density method results in a 
reasonable estimate of the instances of take, but likely significantly 
overestimates the number of individual animals expected to be taken. 
With most species, even this overestimated number is still very small, 
and additional analysis is not really necessary to ensure minor 
impacts. However, because of the number and density of harbor seals in 
the area, a more accurate understanding of the number of individuals 
likely taken is necessary to fully analyze the impacts and ensure that 
the total number of harbor seals taken is small.
    As described below, based on monitoring results from the area, it 
is likely that the modeled number of estimated instances of harbor seal 
take referenced above is overestimated. The density estimate from NMFS 
aerial surveys includes harbor seal haulouts far south of the action 
area that may never move to an ensonified area. Further, we believe 
that we can reasonably estimate the comparative number of individual 
harbor seals that will likely be taken, based both on monitoring data, 
operational information, and a general understanding of harbor seal 
habitat use.
    Using the daily ensonified area x number of survey days x density, 
the number of instances of exposure above the 160-dB threshold 
estimated for Hilcorp's activity in Cook Inlet is large.

[[Page 12364]]

However, when we examine monitoring data from previous activities, it 
is clear this number is an overestimate--compared to both aerial and 
vessel based observation efforts. Apache's monitoring report from 2012 
details that they saw 2,474 harbor seals from 29 aerial flights (over 
29 days) in the vicinity of the survey during the month of June, which 
is the peak month for harbor seal haulout. In surveying the literature, 
correction factors to account for harbor seals in water based on land 
counts vary from 1.2 to 1.65 (Harvey & Goley, 2011). Using the most 
conservative factor of 1.65 (allowing us to consider that some of the 
other individuals on land may have entered the water at other points in 
day), if Apache saw 2,474 seals hauled out then there were an estimated 
1,500 seals in the water during those 29 days. To account for the 
limited number of surveys (29 surveys), NMFS conservatively multiplied 
the number of seals by 5.5 to estimate the number of seals that might 
have been seen if the aerial surveys were conducted for 160 days. This 
yields an estimate of 8,250 instances of seal exposure in the water, 
which is far less than the exposure estimate resulting from Hilcorp's 
calculations. NMFS further reduced the estimate given the context of 
the activity. The activity with the highest potential take of harbor 
seal according to calculations is 3D seismic surveying, primarily due 
to the high source levels. However, the 3D seismic surveying is 
occurring primarily offshore, which is also the area where they are 
least likely to encounter harbor seals. The calculated exposures from 
3D seismic surveying account for 92 percent of the total calculated 
harbor seal exposures across the five years of the project, accounting 
for a high proportion of the takes allocated to deeper water seismic 
activity which is less likely to spatially overlap with harbor seals. 
That the number of potential instances of exposure is likely less than 
calculated is also supported by the visual observations from Protected 
Species Observers (PSOs) on board vessels. PSOs in Cook Inlet sighted a 
total of 285 seals in water over 147 days of activity, which would rise 
to about 310 if adjusted to reflect 160 days of effort. Given the size 
of the disturbance zone for these activities, it is likely that not all 
harbor seals that were exposed were seen by PSOs. However 310 is still 
far less than the estimate given by the density calculations.
    Further, based on the residential nature of harbor seals and the 
number of offshore locations included in Hilcorp's project, where 
harbor seals are unlikely to reside, NMFS estimated the number of 
individual harbor seals exposed, given the instances of exposures. 
Given these multiple methods, as well as the behavioral preferences of 
harbor seals for haulouts in certain parts of the Inlet (Montgomery et 
al., 2007), and high concentrations at haulouts in the lower Inlet, it 
is unreasonable to expect that more than 25 percent of the population, 
or 6,847 individuals, will be taken by Level B harassment during 
Hilcorp's activity. Therefore, we estimate that 6,847 individuals are 
taken, which equates to 25 percent of the estimated abundance in NMFS 
stock assessment report.

Effects of Specified Activities on Subsistence Uses of Marine Mammals

    The availability of the affected marine mammal stocks or species 
for subsistence uses may be impacted by this activity. The subsistence 
uses that may be affected and the potential impacts of the activity on 
those uses are described below. Measures included in this proposed rule 
to reduce the impacts of the activity on subsistence uses are described 
in the Proposed Mitigation section. Last, the information from this 
section and the Proposed Mitigation section is analyzed to determine 
whether the necessary findings may be made in the Unmitigable Adverse 
Impact Analysis and Determination section.
    The ADF&G conducted studies to document the harvest and use of wild 
resources by residents of communities on the east and west sides of 
Cook Inlet (Jones and Kostick 2016). Data on wild resource harvest and 
use were collected, including basic information about who, what, when, 
where, how, and how much wild resources are being used to develop 
fishing and hunting opportunities for Alaska residents. Tyonek was 
surveyed in 2013 (Jones et al., 2015), and Nanwalek, Port Graham, and 
Seldovia were surveyed in 2014 (Jones and Kostick 2016). Marine mammals 
were harvested by three (Seldovia, Nanwalek, Port Graham) of the four 
communities but at relatively low rates. The harvests consisted of 
harbor seals, Steller sea lions, and northern sea otters (Enhydra 
lutris), the latter of which is managed by the U.S. Fish and Wildlife 
Service and not mentioned further.

                       Table 19--Marine Mammal Harvest by Tyonek in 2013 and Nikiski, Port Graham, Seldovia, and Nanwalek in 2014
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                            Households                  Number of marine mammals harvested
                                                              Harvest       attempting   ---------------------------------------------------------------
                         Village                            (pounds per   harvest number
                                                              capita)          (% of        Harbor seal     Steller sea    Northern sea    Beluga whale
                                                                            residents)                         lion            otter
--------------------------------------------------------------------------------------------------------------------------------------------------------
Tyonek..................................................               2          6 (6%)               6               0               0               0
Seldovia................................................               1          2 (1%)               5               0               3               0
Nanwalek................................................              11         17 (7%)              22               6               1               0
Port....................................................               8        27 (18%)              16               1              24               0
Graham..................................................
--------------------------------------------------------------------------------------------------------------------------------------------------------

    In Tyonek, harbor seals were harvested between June and September 
by 6 percent of the households (Jones et al. 2015). Seals were 
harvested in several areas, encompassing an area stretching 20 miles 
along the Cook Inlet coastline from the McArthur River Flats north to 
the Beluga River. Seals were searched for or harvested in the Trading 
Bay areas as well as from the beach adjacent to Tyonek (Jones et al. 
2015). In Seldovia, the harvest of harbor seals (5 total) occurred 
exclusively in December (Jones and Kostick 2016).
    In Nanwalek, 22 harbor seals were harvested in 2014 between March 
and October, the majority of which occur in April. Nanwalek residents 
typically hunt harbor seals and Steller sea lions at Bear Cove, China 
Poot Bay, Tutka Bay, Seldovia Bay, Koyuktolik Bay, Port Chatam, in 
waters south of Yukon Island, and along the shorelines close to

[[Page 12365]]

Nanwalek, all south of the Petition region (Jones and Kosick 2016).
    According to the results presented in Jones and Kostick (2016) in 
Port Graham, harbor seals were the most frequently used marine mammal; 
tribal members harvested 16 in the survey year. Harbor seals were 
harvested in January, February, July, August, September, November, and 
December. Steller sea lions were used noticeably less and harvested in 
November and December.
    The Cook Inlet beluga whale has traditionally been hunted by Alaska 
Natives for subsistence purposes. For several decades prior to the 
1980s, the Native Village of Tyonek residents were the primary 
subsistence hunters of Cook Inlet beluga whales. During the 1980s and 
1990s, Alaska Natives from villages in the western, northwestern, and 
North Slope regions of Alaska either moved to or visited the south-
central region and participated in the yearly subsistence harvest 
(Stanek 1994). From 1994 to 1998, NMFS estimated 65 whales per year 
were taken in this harvest, including those successfully taken for 
food, and those struck and lost. NMFS has concluded that this number is 
high enough to account for the estimated 14 percent annual decline in 
population during this time (Hobbs et al. 2008). Actual mortality may 
have been higher, given the difficulty of estimating the number of 
whales struck and lost during the hunts. In 1999, a moratorium was 
enacted (Pub. L. 106-31) prohibiting the subsistence take of Cook Inlet 
beluga whales except through a cooperative agreement between NMFS and 
the affected Alaska Native organizations.
    On October 15, 2008, NMFS published a final rule that established 
long-term harvest limits on the Cook Inlet beluga whales that may be 
taken by Alaska Natives for subsistence purposes (73 FR 60976). That 
rule prohibits harvest for a 5-year period (2008-2012), if the average 
abundance for the Cook Inlet beluga whales from the prior five years 
(2003-2007) is below 350 whales. The next 5-year period that could 
allow for a harvest (2013-2017) would require the previous five-year 
average (2008-2012) to be above 350 whales. Since the Cook Inlet beluga 
whale harvest was regulated in 1999 requiring cooperative agreements, 
five beluga whales have been struck and harvested. Those beluga whales 
were harvested in 2001 (one animal), 2002 (one animal), 2003 (one 
animal), and 2005 (two animals). The Native Village of Tyonek agreed 
not to hunt or request a hunt in 2007, when no co-management agreement 
was to be signed (NMFS 2008).
    The 2008 Cook Inlet Beluga Whale Subsistence Harvest Final 
Supplemental Environmental Impact Statement (NMFS 2008a) authorizes how 
many beluga whales can be taken during a 5-year interval based on the 
5-year population estimates and 10-year measure of the population 
growth rate. Based on the 2008-2012 5-year abundance estimates, no hunt 
occurred between 2008 and 2012 (NMFS 2008a). The Cook Inlet Marine 
Mammal Council, which managed the Alaska Native Subsistence fishery 
with NMFS, was disbanded by a unanimous vote of the Tribes' 
representatives on June 20, 2012. No harvest has occurred since then 
and no harvest is likely in 2018.
    Residents of the Native Village of Tyonek are the primary 
subsistence users in Knik Arm area (73 FR 60976). No households hunted 
beluga whale locally in Cook Inlet due to conservation concerns (Jones 
et al. 2015). The proposed project should not have any effect because 
no beluga harvest has taken place since 2005, and beluga hunts are not 
expected during the next five-year period.

Proposed Mitigation

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

Mitigation for Marine Mammals and Their Habitat

    Hilcorp has reviewed mitigation measures employed during seismic 
research surveys authorized by NMFS under previous incidental 
harassment authorizations, as well as recommended best practices in 
Richardson et al. (1995), Pierson et al. (1998), Weir and Dolman 
(2007), Nowacek et al. (2013), Wright (2014), and Wright and Cosentino 
(2015), and has incorporated a suite of proposed mitigation measures 
into their project description based on the above sources.
    To reduce the potential for disturbance from acoustic stimuli 
associated with the activities, Hilcorp has proposed to implement the 
following mitigation measures for marine mammals:
    (1) Vessel-based and shore-based visual mitigation monitoring;
    (2) Establishment of a marine mammal exclusion zone (EZ) and safety 
zone (SZ);
    (3) Shutdown procedures;
    (4) Power down procedures;
    (5) Ramp-up procedures; and
    (6) Vessel strike avoidance measures.
    In addition to the measures proposed by Hilcorp, NMFS has proposed 
the following mitigation measures: Aerial overflights for pre-clearance 
and seasonal closure of the Susitna River Delta.
    Exclusion and safety zones--The Exclusion Zone (EZ) is defined as 
the area in which all operations are shut down in the event a marine 
mammal enters or is about to enter this zone based on distances to the 
Level A harassment threshold or what can be effectively monitored for 
the species. The Safety Zone (SZ) is an area larger than the EZ and is 
defined as the area within which operations may power down in the event 
a marine mammal enters or is about to enter, and may be considered a 
Level B harassment. For all activities, if a marine mammal for which

[[Page 12366]]

take is not authorized is seen within or entering the SZ, operations 
will shut down. A minimum 10 meter shutdown zone will be observed for 
all in-water construction and heavy machinery.
    The distances for the EZ and SZ for the activities are summarized 
in Table 20 and described in the following text:

    (1) The distances to the Level A harassment thresholds for the 2D/
3D seismic activity were calculated using the methods described above 
and are indicated in Table 5 above. As in several recent IHAs 
authorizing take from seismic surveys (e.g., five surveys in the 
Atlantic (82 FR 26244) and NSF (83 FR 44578)), we have proposed a more 
standardized 500-m EZ, which is practicable to implement and minimizes 
the likelihood of injury or more severe behavioral responses. The SZ 
for all marine mammals is 1,000 m. The distances to the thresholds for 
the sub-bottom profiler were calculated using the methods described 
above. The EZ for all marine mammals is rounded up to 100 m.
    (2) The distances to the Level A harassment thresholds for the pipe 
driving were calculated using methods above and the distance to the 
Level B harassment threshold is based on Illingworth & Rodkin (2014) 
measurements of 1,600 m to the 160 dB zone. The EZ for all marine 
mammals is rounded up to 100 m. The SZ for all marine mammals is 1,600 
m.
    (3) The distances to the Level A harassment thresholds for VSP were 
calculated using methods described in above and the distance to the 
Level B harassment threshold is based on Illingworth & Rodkin (2014) 
measurements of 2,470 m to the 160 dB zone. The EZ for all marine 
mammals is 500 m.
    (4) The distances to the Level A and B harassment thresholds for 
the vibratory sheet pile driving were calculated using the methods 
described above. The EZ for all marine mammals is 100 m. The SZ for all 
marine mammals is 2,500 m.
    (5) The distances to the Level A harassment thresholds for the 
water jet were calculated using methods described above and the 
distance to the Level B harassment threshold is based on Austin (2017) 
measurements of 860 m to the 120 dB zone. The EZ for all marine mammals 
is rounded up to 15 m. The SZ for all marine mammals is 860 m.
    (6) NMFS proposes that Hilcorp shut down if a beluga is observed 
within or entering the EZ or SZ for seismic airgun or sub-bottom 
profiler use.

     Table 20--Radii of Exclusion Zone (EZ) and Safety Zone (SZ) for
                          Hilcorp's Activities
------------------------------------------------------------------------
                                          Exclusion zone    Safety zone
                Activity                    (EZ) radius     (SZ) radius
                                                (m)             (m)
------------------------------------------------------------------------
2D/3D seismic survey....................             500           1,000
Sub-bottom profilers....................             100           1,000
Pipe driving............................             100           1,600
VSP.....................................             500           2,500
Sheet pile driving......................             100           2,500
Water jet...............................              15             860
------------------------------------------------------------------------

    PSO Placement--For the 2D survey, PSOs will be stationed on the 
source vessel during all seismic operations and geohazard surveys when 
the sub-bottom profilers are used. Because of the proximity to land, 
PSOs may also be stationed on land to augment the viewing area. For the 
3D survey, PSOs will be stationed on at least two of the project 
vessels, the source vessel and the chase vessel. For the VSP, PSOs will 
be stationed on the drilling rig. For geohazard surveys, PSOs will be 
stationed on the survey vessel. The viewing area may be augmented by 
placing PSOs on a vessel specifically for mitigation purposes.
Seismic and Geohazard Survey Mitigation
    Aircraft (Seismic only)--NMFS proposes to require aerial 
overflights to clear the intended area of seismic survey activity of 
beluga whales on a daily basis. Hilcorp will fly over the action area 
searching for belugas prior to ramp up of seismic airguns and ramp up 
will not commence until the flights have confirmed the area appears 
free of beluga whales. This measure would only apply to 2D and 3D 
seismic surveying, not to other sound sources related to geohazard 
survey or well construction.
    Clearing the Exclusion Zone--Prior to the start of daily activities 
for which take has been requested or if activities have been stopped 
for longer than a 30-minute period, the PSOs will ensure the EZ is 
clear of marine mammals for a period of 30 minutes. Clearing the EZ 
means no marine mammals have been observed within the EZ for that 30-
minute period. If any marine mammals have been observed within the EZ, 
ramp up cannot start until the marine mammal has left the EZ or has not 
been observed for a 30-minute period prior to the start of the survey.
    Power Downs--A power down procedure involves reducing the number of 
airguns in use, which reduces the SZ radius and was proposed by Hilcorp 
in their application. In contrast, a shut down procedure occurs when 
all airgun activity is suspended immediately. During a power down, a 
mitigation airgun is operated for no longer than three hours. Operation 
of the mitigation gun allows the size of the SZ to decrease to the size 
of the EZ for marine mammals other than beluga whales. If a marine 
mammal is detected outside the original SZ but is likely to enter that 
zone, the airguns may be powered down before the animal is within the 
safety radius, as an alternative to a complete shutdown. Likewise, if a 
marine mammal is already within the original SZ when first detected, 
the airguns may be powered down if the PSOs determine it is a 
reasonable alternative to an immediate shutdown. If a marine mammal is 
already within the EZ when first detected, the airguns will be shut 
down immediately.
    Following a power down, airgun activity will not resume until the 
marine mammal has cleared the original SZ. The animal will be 
considered to have cleared the original SZ if it:
     Is visually observed to have left the SZ,
     Has not been seen within the SZ for 15 min in the case of 
pinnipeds, and porpoises, or
     Has not been seen within the SZ for 30 min in the case of 
cetaceans.
    Shutdowns--A shutdown is defined as suspending all airgun and sub-
bottom profiler activities. Shutdowns are not implemented for the other 
activities in

[[Page 12367]]

Hilcorp's petition that are unlikely to result in take as they are not 
easily turned off instantaneously. The operating airguns or profiler 
will be shut down completely if a marine mammal is within or enters the 
EZ. The operations will shut down completely if a beluga whale is 
sighted within or entering the SZ or EZ. The shutdown procedure must be 
accomplished within several seconds (of a ``one shot'' period) of the 
determination that a marine mammal is within or enters the EZ.
    Following a shutdown, airgun or sub-bottom profiler activity may be 
reactivated only after the protected species has been observed exiting 
the applicable EZ. The animal will be considered to have cleared the EZ 
if it:
     Is visually observed to have left the EZ, or
     Has not been seen within the EZ for 15 min in the case of 
pinnipeds and porpoises
     Has not been seen within the EZ for 30 min in the case of 
cetaceans (except for beluga whales which cannot not be seen in the EZ 
or SZ).
    Ramp up--A ``ramp up'' procedure gradually increases airgun volume 
at a specified rate. Ramp up is used at the start of airgun operations, 
including after a power down, shutdown, and after any period greater 
than 10 minutes in duration without airgun operations. The rate of ramp 
up will be no more than 6 dB per 5-minute period. Ramp up will begin 
with the smallest gun in the array that is being used for all airgun 
array configurations. During the ramp up, the EZ for the full airgun 
array will be maintained.
    If the complete EZ has not been visible for at least 30 minutes 
prior to the start of operations, ramp up will not commence unless the 
mitigation gun has been operating since the power down of seismic 
survey operations. This means that it will not be permissible to ramp 
up the 24-gun source from a complete shut down in thick fog or at other 
times when the outer part of the EZ is not visible. Ramp up of the 
airguns will not be initiated if a marine mammal is sighted within or 
entering the EZ at any time.
    Speed or Course Alteration--If a marine mammal is detected outside 
the EZ and, based on its position and relative motion, is likely to 
enter the EZ, the vessel's speed and/or direct course may, when 
practical and safe, be changed. This technique also minimizes the 
effect on the seismic program. This technique can be used in 
coordination with a power down procedure. The marine mammal activities 
and movements relative to the seismic and support vessels will be 
closely monitored to ensure that the marine mammal does not enter the 
EZ. If the mammal appears likely to enter the EZ, further mitigation 
actions must be taken, i.e., either further course alterations, power 
down, or shutdown of the airguns.
Pipe and Sheet Pile Driving Mitigation
    Soon after the drill rig is positioned on the well head, the 
conductor pipe will be driven as the first stage of the drilling 
operation. Two PSOs (one operating at a time) will be stationed aboard 
the rig during this two to three day operation monitoring the EZ and 
the SZ. The impact hammer operator will be notified to shut down 
hammering operations if a marine mammal is sighted within or enters the 
EZ. A soft start of the hammering will begin at the start of each 
hammering session. The soft start procedure involves initially starting 
with three soft strikes, 30 seconds apart. This delayed-strike start 
alerts marine mammals of the pending hammering activity and provides 
them time to vacate the area. Monitoring will occur during all 
hammering sessions.
    A dock face will be constructed on the rock causeway in Iniskin 
Bay. Two PSOs will be stationed either on a vessel or on land during 
the 14-21 day operation observing an EZ of 4.6 km for beluga whales. 
PSOs will implement similar monitoring and mitigation strategies as for 
the pipe installation.
    For impact hammering, ``soft-start'' technique must be used at the 
beginning of each day's pipe/pile driving activities to allow any 
marine mammal that may be in the immediate area to leave before pile 
driving reaches full energy.
     Clear the EZ 30 minutes prior to a soft-start to ensure no 
marine mammals are within or entering the EZ.
     Begin impact hammering soft-start with an initial set of 
three strikes from the impact hammer at 40 percent energy, followed by 
a one minute waiting period, then two subsequent 3-strike sets.
     Immediately shut down all hammers at any time a marine 
mammal is detected entering or within the EZ.
     Initial hammering starts will not begin during periods of 
poor visibility (e.g., night, fog, wind).
     Any shutdown due to a marine mammal sighting within the EZ 
must be followed by a 30-minute all-clear period and then a standard, 
full ramp-up.
     Any shutdown for other reasons resulting in the cessation 
of the sound source for a period greater than 30 minutes, must also be 
followed by full ramp-up procedures.
Water Jet Mitigation
    A PSO will be present on the dive support vessel when divers are 
using the water jet. Prior to in-water use of the water jet, the EZ 
around the DSV will be established. The water jet will be shut down if 
marine mammals are observed within the EZ.
Beluga Critical Habitat Mitigation
    Hilcorp must not operate noise producing activities within 10 miles 
(16 km) of the mean higher high water (MHHW) line of the Susitna Delta 
(Beluga River to the Little Susitna River) between April 15 and October 
15. The purpose of this mitigation measure is to protect beluga whales 
in the designated critical habitat in this area that is important for 
beluga whale feeding and calving during the spring and fall months. The 
range of the setback required by NMFS was designated to protect this 
important habitat area and also to create an effective buffer where 
sound does not encroach on this habitat. This seasonal exclusion is 
proposed to be in effect from April 15-October 15. Activities can occur 
within this area from October 16-April 14.

Mitigation for Subsistence Uses of Marine Mammals or Plan of 
Cooperation

    Regulations at 50 CFR 216.104(a)(12) further require Incidental 
Take Authorization applicants conducting activities that take place in 
Arctic waters to provide a Plan of Cooperation or information that 
identifies what measures have been taken and/or will be taken to 
minimize adverse effects on the availability of marine mammals for 
subsistence purposes. A plan must include the following:
     A statement that the applicant has notified and provided 
the affected subsistence community with a draft plan of cooperation;
     A schedule for meeting with the affected subsistence 
communities to discuss proposed activities and to resolve potential 
conflicts regarding any aspects of either the operation or the plan of 
cooperation;
     A description of what measures the applicant has taken 
and/or will take to ensure that proposed activities will not interfere 
with subsistence whaling or sealing; and
     What plans the applicant has to continue to meet with the 
affected communities, both prior to and while conducting the activity, 
to resolve conflicts and to notify the communities of any changes in 
the operation.
    Hilcorp Alaska has developed a Stakeholder Engagement Plan (SEP) 
and

[[Page 12368]]

will implement this plan throughout the duration of the Petition. The 
SEP will help coordinate activities with local stakeholders and thus 
subsistence users, minimize the risk of interfering with subsistence 
hunting activities, and keep current as to the timing and status of the 
subsistence hunts. The Plan is provided in Appendix B of Hilcorp's 
application.
    Presentations will be given at various local forums. Hilcorp Alaska 
is working with a contractor to update/verify our existing stakeholder 
list. Meetings and communication will be coordinated with: commercial 
and sport fishing groups/associations, various Native fisheries and 
entities as it pertains to subsistence fishing and/or hunting, marine 
mammal co-management groups, Cook Inlet Regional Citizens Advisory 
Council, local landowners, government and community organizations, and 
environmental NGOs.
    Based on our evaluation of the applicant's proposed measures, as 
well as other measures considered by NMFS, NMFS has preliminarily 
determined that the proposed mitigation measures provide the means 
effecting the least practicable impact on the affected species or 
stocks and their habitat, paying particular attention to rookeries, 
mating grounds, and areas of similar significance, and on the 
availability of such species or stock for subsistence uses.

Proposed Monitoring and Reporting

    In order to issue an LOA for an activity, section 101(a)(5)(A) of 
the MMPA states that NMFS must set forth, requirements pertaining to 
the monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104 (a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing the 
necessary monitoring and reporting that will result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present in the 
proposed action area. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    The PSOs will observe and collect data on marine mammals in and 
around the project area for 15 (well activity) or 30 minutes (seismic 
activity) before, during, and for 30 minutes after all of Hilcorp's 
activities for which take has been requested.
Protected Species Observer Qualifications
    NMFS-approved PSOs must meet the following requirements:
    1. Independent observers (i.e., not construction personnel) are 
required;
    2. At least one observer must have prior experience working as an 
observer;
    3. Other observers may substitute education (undergraduate degree 
in biological science or related field) or training for experience;
    4. Where a team of three or more observers are required, one 
observer should be designated as lead observer or monitoring 
coordinator. The lead observer must have prior experience working as an 
observer; and
    5. NMFS will require submission and approval of observer CVs.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) Action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the action; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
     Mitigation and monitoring effectiveness.

Proposed Monitoring Measures

    Sound Source Verification--When site-specific measurements are not 
available for noise sources of concern for acoustic exposure, NMFS 
often requires a sound source verification (SSV) to characterize the 
sound levels, propagation, and to verify the monitoring zones (EZ and 
SZ). Hilcorp Alaska plans to perform an SSV for the 3D seismic survey 
and sub-bottom profiler in lower Cook Inlet. Hilcorp Alaska will work 
with NMFS to determine if an SSV is needed for other activities 
occurring in the action area.
    Hilcorp will implement a robust monitoring and mitigation program 
for marine mammals using NMFS-approved PSOs for Petition activities. 
Much of the activities will use vessel-based PSOs, but land- or 
platform-based PSOs may also be used to augment project-specific 
activities. Marine mammal monitoring and mitigation methods have been 
designed to meet the requirements and objectives which will be 
specified in the Incidental Take Regulations promulgated by NMFS. Some 
details of the monitoring and mitigation program may change upon 
receipt of the individual LOAs issued by NMFS each year.
    The main purposes of PSOs are: To conduct visual watches for marine 
mammals; to serve as the basis for implementation of mitigation 
measures; to document numbers of marine mammals present; to record any 
reactions of marine mammals to Hilcorp's activities; and, to identify 
whether there was any possible effect on accessibility of marine 
mammals to subsistence hunters in Cook Inlet. These observations will 
provide the real-time data needed to implement some of the key 
measures.
    PSOs will be on watch during all daylight periods for project-
specific activities. Generally, work is conducted 24-hrs a day, 
depending on the specific activity.
     For 2D seismic surveys, the airgun operations will be 
conducted during daylight hours.
     For 3D seismic surveys, airgun operations will continue 
during the waning nighttime hours (ranges from 2230-0600 in early April 
to 0100-0300 in mid-May) as long as the full array or mitigation gun is 
operating prior to nightfall and mitigation airgun use cannot be longer 
than three hours. Night vision and infrared have been suggested for low 
visibility conditions, but these have not been useful in Cook Inlet or 
other Alaska-based programs. Passive acoustic monitoring has also been 
used in Cook Inlet and is typically required for seismic surveys but 
has not shown to be an effective solution in Cook Inlet's specific 
environmental conditions. A further discussion of previous passive 
acoustic monitoring efforts by several entities in Cook Inlet is 
provided in Section 13 of Hilcorp's application.
     For the sub-bottom profiler, operations will generally be 
conducted during daylight hours but may continue into the low 
visibility period as long as the profiler is operating prior to

[[Page 12369]]

nightfall. Sub-bottom profiler operations may not begin under low 
visibility conditions.
     For pipe driving, VSP, and sheet pile driving, operations 
will generally be conducted during daylight hours.
     Water jet and hydraulic grinder are operated over a 24-
hour period as they are limited to low tide conditions. Activities will 
not start during nighttime but will continue if already started.
    Pre-Activity Monitoring--The exclusion zone will be monitored for 
30 minutes prior to in-water construction/demolition activities. If a 
marine mammal is present within the exclusion zone, the activity will 
be delayed until the animal(s) leave the exclusion zone. Activity will 
resume only after the PSO has determined that, through sighting or by 
waiting (15 minutes for pinnipeds and porpoises, 30 minutes for 
cetaceans) without re-sighting, the animal(s) has moved outside the 
exclusion zone. If a marine mammal is observed within or entering the 
exclusion zone, the PSO who sighted that animal will notify all other 
PSOs and Hilcorp of its presence.
    Post-Activity Monitoring--Monitoring of all zones will continue for 
30 minutes following the completion of the activity.
    For all activities, the PSOs will watch for marine mammals from the 
best available vantage point on the vessel or station. Ideally this 
vantage point is an elevated stable platform from which the PSO has an 
unobstructed 360[deg] view of the water. The PSOs will scan 
systematically with the naked eye and with binoculars. When a mammal 
sighting is made, the following information about the sighting will be 
carefully and accurately recorded:
     Species, group size, age/size/sex categories (if 
determinable), behavior when first sighted and after initial sighting, 
heading (if consistent), bearing and distance from the PSO, apparent 
reaction to activities (e.g., none, avoidance, approach, paralleling), 
closest point of approach, and behavioral pace.
     Time, location, speed, activity of the vessel, sea state, 
ice cover, visibility, and sun glare.
     The positions of other vessel(s) in the vicinity of the 
PSO location.
     The vessel's position, speed, water depth, sea state, ice 
cover, visibility, and sun glare will also be recorded at the start and 
end of each observation watch, every 30 minutes during a watch, and 
whenever there is a change in any of those variables.
    An electronic database or paper form will be used to record and 
collate data obtained from visual observations.
    The results of the PSO monitoring, including estimates of exposure 
to key sound levels, will be presented in weekly, monthly, and 90-day 
reports. Reporting will address the requirements established by NMFS in 
the LOAs. The technical report(s) will include the list below.
     Summaries of monitoring effort: Total hours, total 
distances, and distribution of marine mammals throughout the study 
period compared to sea state, and other factors affecting visibility 
and detectability of marine mammals;
     Analyses of the effects of various factors influencing 
detectability of marine mammals: sea state, number of observers, and 
fog/glare;
     Species composition, occurrence, and distribution of 
marine mammal sightings including date, water depth, numbers, age/size/
gender categories (when discernable), group sizes, and ice cover; and
     Analyses of the effects of seismic program:
    [cir] Sighting rates of marine mammals during periods with and 
without project activities (and other variables that could affect 
detectability);
    [cir] Initial sighting distances versus project activity;
    [cir] Closest point of approach versus project activity;
    [cir] Observed behaviors and types of movements versus project 
activity;
    [cir] Numbers of sightings/individuals seen versus project 
activity;
    [cir] Distribution around the vessels versus project activity;
    [cir] Summary of implemented mitigation measures; and
    [cir] Estimates of ``take by harassment.''
Proposed Reporting Measures
    Immediate reports will be submitted to NMFS if 30 or more belugas 
are detected over the course of annual operations in the safety and 
exclusion zones during operation of sound sources to evaluate and make 
necessary adjustments to monitoring and mitigation. If the number of 
detected takes for any marine mammal species is met or exceeded, 
Hilcorp will immediately cease survey operations involving the use of 
active sound sources (e.g., airguns and pingers) and notify NMFS Office 
of Protected Resources (OPR).
    1. Weekly Reports (during years with seismic surveying only)--
Hilcorp would submit a weekly field report to NMFS Headquarters as well 
as the Alaska Regional Office, no later than close of business each 
Thursday during the weeks when in-water seismic survey activities take 
place. The weekly field reports would summarize species detected 
(number, location, distance from seismic vessel, behavior), in-water 
activity occurring at the time of the sighting (discharge volume of 
array at time of sighting, seismic activity at time of sighting, visual 
plots of sightings, and number of power downs and shutdowns), 
behavioral reactions to in-water activities, and the number of marine 
mammals exposed.
    2. Monthly Reports- Monthly reports will be submitted to NMFS for 
all months during which in-water seismic activities take place. The 
monthly report will contain and summarize the following information:
     Dates, times, locations, heading, speed, weather, sea 
conditions (including Beaufort sea state and wind force), and 
associated activities during all seismic operations and marine mammal 
sightings.
     Species, number, location, distance from the vessel, and 
behavior of any sighted marine mammals, as well as associated seismic 
activity (number of power-downs and shutdowns), observed throughout all 
monitoring activities.
     An estimate of the number (by species) exposed to the 
seismic activity (based on visual observation) at received levels 
greater than or equal to the NMFS thresholds discussed above with a 
discussion of any specific behaviors those individuals exhibited.
     A description of the implementation and effectiveness of 
the: (i) Terms and conditions of the Biological Opinion's Incidental 
Take Statement (ITS); and (ii) mitigation measures of the LOA. For the 
Biological Opinion, the report must confirm the implementation of each 
Term and Condition, as well as any conservation recommendations, and 
describe their effectiveness for minimizing the adverse effects of the 
action on ESA-listed marine mammals.
    3. Annual Reports--Hilcorp must submit an annual report within 90 
days after each activity year, starting from the date when the LOA is 
issued (for the first annual report) or from the date when the previous 
annual report ended. The annual report would include:
     Summaries of monitoring effort (e.g., total hours, total 
distances, and marine mammal distribution through the study period, 
accounting for sea state and other factors affecting visibility and 
detectability of marine mammals).
     Analyses of the effects of various factors influencing 
detectability of marine mammals (e.g., sea state, number of observers, 
and fog/glare).
     Species composition, occurrence, and distribution of 
marine mammal sightings, including date, water depth, numbers, age/
size/gender categories (if

[[Page 12370]]

determinable), group sizes, and ice cover.
     Analyses of the effects of survey operations.
     Sighting rates of marine mammals during periods with and 
without seismic survey activities (and other variables that could 
affect detectability), such as: (i) Initial sighting distances versus 
survey activity state; (ii) closest point of approach versus survey 
activity state; (iii) observed behaviors and types of movements versus 
survey activity state; (iv) numbers of sightings/individuals seen 
versus survey activity state; (v) distribution around the source 
vessels versus survey activity state; and (vi) numbers of animals 
detected in the harassment/safety zone.
    NMFS would review the draft annual reports. Hilcorp must then 
submit a final annual report to the Chief, Permits and Conservation 
Division, Office of Protected Resources, NMFS, within 30 days after 
receiving comments from NMFS on the draft annual report. If NMFS 
decides that the draft annual report needs no comments, the draft 
report will be considered to be the final report.
    3. Discovery of Injured or Dead Marine Mammals--In the event that 
personnel involved in the survey activities covered by the 
authorization discover an injured or dead marine mammal, Hilcorp must 
report the incident to the Office of Protected Resources (OPR), NMFS 
and to the Alaska Regional stranding coordinator as soon as feasible. 
The report must include the following information:
     Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
     Species identification (if known) or description of the 
animal(s) involved;
     Condition of the animal(s) (including carcass condition if 
the animal is dead);
     Observed behaviors of the animal(s), if alive;
     If available, photographs or video footage of the 
animal(s); and
     General circumstances under which the animal was 
discovered.
    Vessel Strike--In the event of a ship strike of a marine mammal by 
any vessel involved in the activities covered by the authorization, 
Hilcorp must report the incident to OPR, NMFS and to regional stranding 
coordinator as soon as feasible. The report must include the following 
information:
     Time, date, and location (latitude/longitude) of the 
incident;
     Species identification (if known) or description of the 
animal(s) involved;
     Vessel's speed during and leading up to the incident;
     Vessel's course/heading and what operations were being 
conducted (if applicable);
     Status of all sound sources in use;
     Description of avoidance measures/requirements that were 
in place at the time of the strike and what additional measures were 
taken, if any, to avoid strike;
     Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, visibility) immediately preceding the 
strike;
     Estimated size and length of animal that was struck;
     Description of the behavior of the marine mammal 
immediately preceding and following the strike;
     If available, description of the presence and behavior of 
any other marine mammals immediately preceding the strike;
     Estimated fate of the animal (e.g., dead, injured but 
alive, injured and moving, blood or tissue observed in the water, 
status unknown, disappeared); and
     To the extent practicable, photographs or video footage of 
the animal(s).
    Actions to Minimize Additional Harm to Live-Stranded (or Milling) 
Marine Mammals--In the event of a live stranding (or near-shore 
atypical milling) event within 50 km of the survey operations, where 
the NMFS stranding network is engaged in herding or other interventions 
to return animals to the water, the Director of OPR, NMFS (or designee) 
will advise the Hilcorp of the need to implement shutdown procedures 
for all active acoustic sources operating within 50 km of the 
stranding. Shutdown procedures for live stranding or milling marine 
mammals include the following:
     If at any time, the marine mammals die or are euthanized, 
or if herding/intervention efforts are stopped, the Director of OPR, 
NMFS (or designee) will advise Hilcorp that the shutdown around the 
animals' location is no longer needed.
     Otherwise, shutdown procedures will remain in effect until 
the Director of OPR, NMFS (or designee) determines and advises Hilcorp 
that all live animals involved have left the area (either of their own 
volition or following an intervention).
     If further observations of the marine mammals indicate the 
potential for re- stranding, additional coordination with Hilcorp will 
be required to determine what measures are necessary to minimize that 
likelihood (e.g., extending the shutdown or moving operations farther 
away) and to implement those measures as appropriate.
    Shutdown procedures are not related to the investigation of the 
cause of the stranding and their implementation is not intended to 
imply that the specified activity is the cause of the stranding. 
Rather, shutdown procedures are intended to protect marine mammals 
exhibiting indicators of distress by minimizing their exposure to 
possible additional stressors, regardless of the factors that 
contributed to the stranding.

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any responses (e.g., intensity, duration), the context 
of any responses (e.g., critical reproductive time or location, 
migration), as well as effects on habitat, and the likely effectiveness 
of the mitigation. We also assess the number, intensity, and context of 
estimated takes by evaluating this information relative to population 
status. Consistent with the 1989 preamble for NMFS's implementing 
regulations (54 FR 40338; September 29, 1989), the impacts from other 
past and ongoing anthropogenic activities are incorporated into this 
analysis via their impacts on the environmental baseline (e.g., as 
reflected in the regulatory status of the species, population size and 
growth rate where known, ongoing sources of human-caused mortality, or 
ambient noise levels).
    Given the nature of activities, proposed mitigation and related 
monitoring, no serious injuries or mortalities are anticipated to occur 
as a result of Hilcorp's proposed oil and gas activities in Cook Inlet, 
and none are proposed to be authorized. The number of takes that are 
anticipated and proposed to be authorized are expected to be limited 
mostly to short-term Level B harassment, although some PTS may occur. 
The seismic airguns and other

[[Page 12371]]

sound sources do not operate continuously over a 24-hour period. Rather 
the airguns are operational for a few hours at a time with breaks in 
between, as surveys can only be conducted during slack tides, totaling 
a maximum of 12 hours a day for the most frequently used equipment. 
Sources other than airguns are likely to be used for much shorter 
durations daily than the 12 potential hours of airgun use.
    Cook Inlet beluga whales, the Mexico DPS of humpback whales, fin 
whales, and the western stock of Steller sea lions are listed as 
endangered under the ESA. These stocks are also considered depleted 
under the MMPA. Beluga-specific mitigation measures, such as shutting 
down whenever beluga whales are sighted by PSOs and an exclusion zone 
at the Susitna River Delta months of high beluga concentrations, aim to 
minimize the effects of this activity on the population. Zerbini et al. 
(2006) estimated rates of increase of fin whales in coastal waters 
south of the Alaska, and data from Calambokidis et al. (2008) suggest 
the population of humpback whales by also be increasing. Steller sea 
lion trends for the western stock are variable throughout the region 
with some decreasing and others remaining stable or even indicating 
slight increases. The other species that may be taken by harassment 
during Hilcorp's proposed oil and gas program are not listed as 
threatened or endangered under the ESA nor as depleted under the MMPA.
    Odontocete (including Cook Inlet beluga whales, killer whales, and 
harbor porpoises) reactions to seismic energy pulses are usually 
assumed to be limited to shorter distances from the airgun(s) than are 
those of mysticetes, in part because odontocete low-frequency hearing 
is assumed to be less sensitive than that of mysticetes. When in the 
Canadian Beaufort Sea in summer, belugas appear to be fairly responsive 
to seismic energy, with few being sighted within 10-20 km (6-12 mi) of 
seismic vessels during aerial surveys (Miller et al., 2005). However, 
as noted above, Cook Inlet belugas are more accustomed to anthropogenic 
sound than beluga whales in the Beaufort Sea. Therefore, the results 
from the Beaufort Sea surveys may be less applicable to potential 
reactions of Cook Inlet beluga whales. Also, due to the dispersed 
distribution of beluga whales in Cook Inlet during winter and the 
concentration of beluga whales in upper Cook Inlet from late April 
through early fall (i.e., far north of the proposed seismic surveys), 
belugas would likely occur in small numbers in the majority of 
Hilcorp's proposed survey area during the majority of Hilcorp's annual 
operational timeframe.
    Taking into account the mitigation measures that are planned, 
effects on cetaceans are generally expected to be restricted to 
avoidance of a limited area around the survey operation and short-term 
changes in behavior, falling within the MMPA definition of ``Level B 
harassment.'' It is possible that Level A take of marine mammals from 
sound sources such as seismic airguns may also occur. Due to the short 
term duration of activities in any given area and the small geographic 
area in which Hilcorp's activities would be occurring at any one time, 
it is unlikely that these activities would affect reproduction or 
survival of cetaceans in Cook Inlet. Animals are not expected to 
permanently abandon any area that is surveyed, and any behaviors that 
are interrupted during the activity are expected to resume once the 
activity ceases. Only a small portion of marine mammal habitat will be 
affected at any time, and other areas within Cook Inlet will be 
available for necessary biological functions including breeding, 
foraging, and mating. In addition, NMFS proposes to seasonally restrict 
seismic survey operations in locations known to be important for beluga 
whale feeding, calving, or nursing. One of the primary locations for 
these biological life functions occur in the Susitna Delta region of 
upper Cook Inlet. NMFS proposes to implement a 16 km (10 mi) seasonal 
exclusion from activities for which take has been requested in this 
region from April 15 to October 15 annually. The highest concentrations 
of belugas are typically found in this area from early May through 
September each year. NMFS has incorporated a 2-week buffer on each end 
of this seasonal use timeframe to account for any anomalies in 
distribution and marine mammal usage.
    Mitigation measures, such as dedicated marine mammal observers, and 
shutdowns or power downs when marine mammals are seen within defined 
ranges, are designed both to further reduce short-term reactions and 
minimize any effects on hearing sensitivity. In all cases, the effects 
of these activities are expected to be short-term, with no lasting 
biological consequence. Therefore, the exposure of cetaceans to sounds 
produced by Hilcorp's proposed oil and gas activities is not 
anticipated to have an effect on annual rates of recruitment or 
survival of the affected species or stocks.
    Some individual pinnipeds may be exposed to sound from the proposed 
activities more than once during the timeframe of the project. Taking 
into account the mitigation measures that are planned, effects on 
pinnipeds are generally expected to be restricted to avoidance of a 
limited area around the survey operation and short-term changes in 
behavior, falling within the MMPA definition of ``Level B harassment,'' 
although some pinnipeds may approach close enough to sound sources 
undetected and incur PTS. Due to the solitary nature of pinnipeds in 
water, this is expected to be a small number of individuals and the 
calculated distances to the PTS thresholds incorporate a relatively 
long duration, making them conservative. Animals are not expected to 
permanently abandon any area that is surveyed, and any behaviors that 
are interrupted during the activity are expected to resume once the 
activity ceases. Only a small portion of pinniped habitat will be 
affected at any time, and other areas within Cook Inlet will be 
available for necessary biological functions. In addition, the areas 
where the activities will take place are largely offshore and not known 
to be biologically important areas for pinniped populations. Therefore, 
the exposure of pinnipeds to sounds produced by this phase of 
Hilcorps's proposed activity is not anticipated to have an effect on 
annual rates of recruitment or survival on those species or stocks.
    The addition of multiple source and supply vessels, and noise due 
to vessel operations associated with the activities, would not be 
outside the present experience of marine mammals in Cook Inlet, 
although levels may increase locally. Given the large number of vessels 
in Cook Inlet and the apparent habituation to vessels by Cook Inlet 
beluga whales and the other marine mammals that may occur in the area, 
vessel activity and its associated noise is not expected to have 
effects that could cause significant or long-term consequences for 
individual marine mammals or their populations.
    Potential impacts to marine mammal habitat were discussed 
previously in this document (see the ``Anticipated Effects on Habitat'' 
section). Although some disturbance is possible to food sources of 
marine mammals, the impacts are anticipated to be minor enough as to 
not affect annual rates of recruitment or survival of marine mammals in 
the area. Based on the size of Cook Inlet where feeding by marine 
mammals occurs versus the localized area of the marine survey 
activities, any missed feeding opportunities in the direct project area 
would be minor based on the fact that other feeding areas exist 
elsewhere. Additionally,

[[Page 12372]]

operations will not occur in the primary beluga feeding and calving 
habitat during times of high use by those animals. The proposed 
mitigation measure of limiting activities around the Susistna Delta 
would also protect beluga whale prey and their foraging habitat.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect the species or stock 
through effects on annual rates of recruitment or survival:
     No mortality is anticipated or authorized;
     Increased mitigation for beluga whales, including 
shutdowns at any distance and exclusion zones and avoiding exposure 
during critical foraging periods around the Susitna Delta;
     Location of activities offshore which minimizes effects of 
activity on resident pinnipeds at haulouts,
     Concentration of seismic surveying in the lower portions 
of Cook Inlet going into open water where densities of marine mammals 
are less than other parts of the Inlet; and
     Comprehensive land, sea, and aerial-based monitoring 
maximizing marine mammal detection rates as well as acoustic SSV to 
verify exposure levels.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the proposed monitoring and 
mitigation measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity will have a negligible impact on 
all affected marine mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under section 101(a)(5)(A) of the MMPA for specified 
activities other than military readiness activities. The MMPA does not 
define small numbers and so, in practice, NMFS compares the number of 
individuals taken within a year to the most appropriate estimation of 
abundance of the relevant species or stock in our determination of 
whether an authorization is limited to small numbers of marine mammals. 
Additionally, other qualitative factors may be considered in the 
analysis, such as the temporal or spatial scale of the activities.
    As described above in Table 18, the takes proposed to be authorized 
represent less than 25 percent of any stock of population in the year 
of maximum activity. Further, takes are expected to be significantly 
lower in the years without 3D seismic activities. For species listed as 
endangered under the ESA, takes proposed to be authorized represent no 
more than nine percent of the stock of humpback whales, ten percent of 
the stock of Cook Inlet beluga whales, and less than one percent of the 
Northeastern Pacific stock of fin whales and Western DPS of Steller sea 
lions.
    NMFS finds that any incidental take reasonably likely to result 
annually from the effects of the proposed activities, as proposed to be 
mitigated through this rulemaking and LOA process, will be limited to 
small numbers of the affected species or stock. In addition to the 
quantitative methods used to estimate take, NMFS also considered 
qualitative factors that further support the ``small numbers'' 
determination, including: (1) The seasonal distribution and habitat use 
patterns of Cook Inlet beluga whales, which suggest that for much of 
the time only a small portion of the population would be accessible to 
impacts from Hilcorp's activity, as most animals are found in the 
Susitna Delta region of Upper Cook Inlet from early May through 
September; (2) other cetacean species and Steller sea lions are not 
common in the action area; (3) the proposed mitigation requirements, 
which provide spatio-temporal limitations that avoid impacts to large 
numbers of belugas feeding and calving in the Susitna Delta and limit 
exposures to sound levels associated with Level B harassment; (4) the 
proposed monitoring requirements and mitigation measures described 
earlier in this document for all marine mammal species that will 
further reduce impacts and the amount of takes; and (5) monitoring 
results from previous activities that indicated low numbers of beluga 
whale sightings within the Level B disturbance exclusion zone and low 
levels of Level B harassment takes of other marine mammals. 
Additionally, the rationale provided in the Estimated Take section 
above, estimates that the number of individual harbor seals like to be 
exposed to noise that may cause harassment is significantly less than 
the number of calculated exposure due to the resident nature of harbor 
seals, offshore locations of the sound sources, and likelihood of 
harbor seals to be hauled out on land at the time sound sources are 
deployed.
    Based on the analysis contained herein of the proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals will be taken relative to the population size 
of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    In order to issue an ITA, NMFS must find that the specified 
activity will not have an ``unmitigable adverse impact'' on the 
subsistence uses of the affected marine mammal species or stocks by 
Alaskan Natives. NMFS has defined ``unmitigable adverse impact'' in 50 
CFR 216.103 as an impact resulting from the specified activity: (1) 
That is likely to reduce the availability of the species to a level 
insufficient for a harvest to meet subsistence needs by: (i) Causing 
the marine mammals to abandon or avoid hunting areas; (ii) Directly 
displacing subsistence users; or (iii) placing physical barriers 
between the marine mammals and the subsistence hunters; and (2) that 
cannot be sufficiently mitigated by other measures to increase the 
availability of marine mammals to allow subsistence needs to be met.
    The project is unlikely to affect beluga whale harvests because no 
beluga harvest will take place in 2019, nor is one likely to occur in 
the other years that would be covered by the 5-year regulations and 
associated LOAs. Additionally, the proposed action area is not an 
important native subsistence site for other subsistence species of 
marine mammals. Also, because of the relatively small number of marine 
mammals harvested in Cook Inlet, the number affected by the proposed 
action is expected to be extremely low. Therefore, because the proposed 
action would result in only temporary disturbances, the proposed action 
would not impact the availability of these other marine mammal species 
for subsistence uses.
    The timing and location of subsistence harvest of Cook Inlet harbor 
seals may coincide with Hilcorp's project but, because this subsistence 
hunt is conducted opportunistically and at such a low level (NMFS, 
2013c), Hilcorp's program is not expected to have an impact on the 
subsistence use of harbor seals.
    NMFS anticipates that any effects from Hilcorp's proposed 
activities on marine mammals, especially harbor seals and Cook Inlet 
beluga whales, which are or have been taken for subsistence uses, would 
be short-term, site specific, and limited to inconsequential changes in 
behavior and mild stress responses. NMFS does not anticipate that the 
authorized taking of affected species or stocks will reduce the 
availability of the species to a level insufficient for a harvest to 
meet subsistence needs by: (1) Causing the

[[Page 12373]]

marine mammals to abandon or avoid hunting areas; (2) directly 
displacing subsistence users; or (3) placing physical barriers between 
the marine mammals and the subsistence hunters. And any such potential 
reductions could be sufficiently mitigated by other measures to 
increase the availability of marine mammals to allow subsistence needs 
to be met. Based on the description of the specified activity, the 
measures described to minimize adverse effects on the availability of 
marine mammals for subsistence purposes, and the proposed mitigation 
and monitoring measures, NMFS has preliminarily determined that there 
will not be an unmitigable adverse impact on subsistence uses from 
Hilcorp's proposed activities.

Adaptive Management

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

Endangered Species Act (ESA)

    Section 7(a)(2) of the Endangered Species Act of 1973 (ESA: 16 
U.S.C. 1531 et seq.) requires that each Federal agency insure that any 
action it authorizes, funds, or carries out is not likely to jeopardize 
the continued existence of any endangered or threatened species or 
result in the destruction or adverse modification of designated 
critical habitat. To ensure ESA compliance for the issuance of ITAs, 
NMFS consults internally, in this case with the Alaska Protected 
Resources Division Office, whenever we propose to authorize take for 
endangered or threatened species.
    NMFS is proposing to authorize take of Cook Inlet beluga whale, 
Northeastern Pacific stock of fin whales, Western North Pacific, 
Hawaii, and Mexico DPS of humpback whales, and western DPS of Steller 
sea lions, which are listed under the ESA.
    The Permit and Conservation Division has requested initiation of 
section 7 consultation with the Alaska Region for the promulgation of 
5-year regulations and the subsequent issuance of annual LOAs. NMFS 
will conclude the ESA consultation prior to reaching a determination 
regarding the proposed issuance of the authorization.

Classification

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

List of Subjects in 50 CFR Part 217

    Penalties, Reporting and recordkeeping requirements, Seafood, 
Transportation.

    Dated: March 21, 2019.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs, National Marine 
Fisheries Service.
    For reasons set forth in the preamble, 50 CFR part 217 is proposed 
to be amended as follows:

PART 217--REGULATIONS GOVERNING THE TAKE OF MARINE MAMMALS 
INCIDENTAL TO SPECIFIED ACTIVITIES

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

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

0
2. Add subpart Q to part 217 to read as follows:
Subpart Q--Taking and Importing Marine Mammals; Taking Marine Mammals 
Incidental to Oil and Gas Activities in Cook Inlet, Alaska
Sec.
217.160 Specified activity and specified geographical region.
217.161 Effective dates.
217.162 Permissible methods of taking.
217.163 Prohibitions.
217.164 Mitigation requirements.
217.165 Requirements for monitoring and reporting.
217.166 Letters of Authorization.
217.167 Renewals and modifications of Letters of Authorization
217.168--217.169 [Reserved]

Subpart Q--Taking and Importing Marine Mammals; Taking Marine 
Mammals Incidental to Oil and Gas Activities in Cook Inlet, Alaska


Sec.  217.160   Specified activity and specified geographical region.

    (a) Regulations in this subpart apply only to Hilcorp Alaska LLC 
(Hilcorp) and those persons it authorizes or funds to conduct 
activities on its behalf for the taking of marine mammals that occurs 
in the area outlined in paragraph (b) of this section and that occurs 
incidental to the activities described in paragraph (c) of this 
section.
    (b) The taking of marine mammals by Hilcorp may be authorized in 
Letters of Authorization (LOAs) only if it occurs within the action 
area defined in Cook Inlet, Alaska.
    (c) The taking of marine mammals by Hilcorp is only authorized if 
it occurs incidental to Hilcorp's oil and gas activities including use 
of seismic airguns, sub-bottom profiler, vertical seismic profiling, 
pile driving, conductor pipe driving, and water jets.

[[Page 12374]]

Sec.  217.161   Effective dates and definitions.

    Regulations in this subpart are effective [EFFECTIVE DATE OF FINAL 
RULE] through [DATE 5 YEARS AFTER EFFECTIVE DATE OF FINAL RULE].


Sec.  217.162   Permissible methods of taking.

    Under LOAs issued pursuant to Sec.  216.106 of this chapter and 
Sec.  217.166, the Holder of the LOAs (hereinafter ``Hilcorp'') may 
incidentally, but not intentionally, take marine mammals within the 
area described in Sec.  217.160(b) by Level A harassment and Level B 
harassment associated with oil and gas activities, provided the 
activity is in compliance with all terms, conditions, and requirements 
of the regulations in this subpart and the applicable LOAs.


Sec.  217.163   Prohibitions.

    Notwithstanding takings contemplated in Sec.  217.162 and 
authorized by LOAs issued under Sec. Sec.  216.106 of this chapter and 
217.166, no person in connection with the activities described in Sec.  
217.160 may:
    (a) Violate, or fail to comply with, the terms, conditions, and 
requirements of this subpart or a LOA issued under Sec. Sec.  216.106 
of this chapter and 217.166;
    (b) Take any marine mammal not specified in such LOAs;
    (c) Take any marine mammal specified in such LOAs in any manner 
other than as specified;
    (d) Take a marine mammal specified in such LOAs if NMFS determines 
such taking results in more than a negligible impact on the species or 
stocks of such marine mammal; or
    (e) Take a marine mammal specified in such LOAs if NMFS determines 
such taking results in an unmitigable adverse impact on the 
availability of such species or stock of marine mammal for taking for 
subsistence uses.


Sec.  217.164   Mitigation requirements.

    When conducting the activities identified in Sec.  217.160(c), the 
mitigation measures contained in any LOAs issued under Sec. Sec.  
216.106 of this chapter and 217.166 must be implemented. These 
mitigation measures must include but are not limited to:
    (a) If any marine mammal species for which take is not authorized 
are sighted within or entering the relevant zones within which they 
would be exposed to sound above the 120 dB re 1 [micro]Pa (rms) 
threshold for continuous (e.g., vibratory pile-driving, drilling) 
sources or the 160 dB re 1 [micro]Pa (rms) threshold for non-explosive 
impulsive (e.g., seismic airguns) or intermittent (e.g., scientific 
sonar) sources, Hilcorp must take appropriate action to avoid such 
exposure (e.g., by altering speed or course or by power down or 
shutdown of the sound source).
    (b) If the allowable number of takes in an LOA listed for any 
marine mammal species is met or exceeded, Hilcorp must immediately 
cease survey operations involving the use of active sound source(s), 
record the observation, and notify NMFS Office of Protected Resources.
    (c) Hilcorp must notify NMFS Office of Protected Resources at least 
48 hours prior to the start of oil and gas activities each year.
    (d) Hilcorp must conduct briefings as necessary between vessel 
crews, marine mammal monitoring team, and other relevant personnel 
prior to the start of all survey activity, and when new personnel join 
the work, in order to explain responsibilities, communication 
procedures, marine mammal monitoring protocol, and operational 
procedures.
    (e) Establishment of monitoring and exclusion zones. (1) For all 
relevant in-water construction and demolition activity, Hilcorp must 
implement shutdown zones/exclusion zones (EZs) with radial distances as 
identified in any LOA issued under Sec. Sec.  216.106 of this chapter 
and 217.166. If a marine mammal is sighted within or entering the EZ, 
such operations must cease.
    (2) For all relevant in-water construction and demolition activity, 
Hilcorp must designate safety zones for monitoring (SZ)with radial 
distances as identified in any LOA issued under Sec. Sec.  216.106 of 
this chapter and 217.166 and record and report occurrence of marine 
mammals within these zones.
    (3) For all in-water construction and demolition activity, Hilcorp 
must implement a minimum EZ of a 10 m radius around the source.
    (f) Shutdown measures. (1) Hilcorp must deploy protected species 
observers (PSOs) and PSOs must be posted to monitor marine mammals 
within the monitoring zones during use of active acoustic sources and 
pile driving in water.
    (2) Monitoring must begin 15 minutes prior to initiation of 
stationary source activity and 30 minutes prior to initiation of mobile 
source activity, occur throughout the time required to complete the 
activity, and continue through 30 minutes post-completion of the 
activity. Pre-activity monitoring must be conducted to ensure that the 
EZ is clear of marine mammals, and activities may only commence once 
observers have declared the EZ clear of marine mammals. In the event of 
a delay or shutdown of activity resulting from marine mammals in the 
EZ, the marine mammals' behavior must be monitored and documented.
    (3) A determination that the EZ is clear must be made during a 
period of good visibility (i.e., the entire EZ must be visible to the 
naked eye).
    (4) If a marine mammal is observed within or entering the EZ, 
Hilcorp must halt all noise producing activities for which take is 
authorized at that location. If activity is delayed due to the presence 
of a marine mammal, the activity may not commence or resume until 
either the animal has voluntarily left and been visually confirmed 
outside the EZ or the required amount of time (15 for porpoises and 
pinnipeds, 30 minutes for cetaceans) have passed without re-detection 
of the animal.
    (5) Monitoring must be conducted by trained observers, who must 
have no other assigned tasks during monitoring periods. Trained 
observers must be placed at the best vantage point(s) practicable to 
monitor for marine mammals and implement shutdown or delay procedures 
when applicable through communication with the equipment operator. 
Hilcorp must adhere to the following additional observer 
qualifications:
    (i) Hilcorp must use independent, dedicated, trained visual PSOs, 
meaning that the PSOs must be employed by a third-party observer 
provider, must not have tasks other than to conduct observational 
effort, collect data, and communicate with and instruct relevant vessel 
crew with regard to the presence of protected species and mitigation 
requirements (including brief alerts regarding maritime hazards), and 
must have successfully completed an approved PSO training course 
appropriate for their designated task.
    (ii) Hilcorp must submit PSO resumes for NMFS review and approval. 
Resumes must be accompanied by a relevant training course information 
packet that includes the name and qualifications (i.e., experience, 
training completed, or educational background) of the instructor(s), 
the course outline or syllabus, and course reference material as well 
as a document stating successful completion of the course. NMFS is 
allowed one week to approve PSOs from the time that the necessary 
information is received by NMFS, after which PSOs meeting the minimum 
requirements will automatically be considered approved.
    (iii) To the maximum extent practicable, the lead PSO must devise 
the duty schedule such that experienced PSOs are on duty with those 
PSOs with appropriate training but who have not yet gained relevant 
experience.
    (6) Hilcorp must implement shutdown measures if the number of

[[Page 12375]]

authorized takes for any particular species reaches the limit under the 
applicable LOA and if such marine mammals are sighted within the 
vicinity of the project area and are entering the SZ during activities.
    (7) Hilcorp must implement a shutdown if a beluga whale is seen 
within or entering the EZ or SZ.
    (g) Impact driving soft start. (1) Hilcorp must implement soft 
start techniques for impact pile driving. Hilcorp must conduct an 
initial set of three strikes from the impact hammer 30 seconds apart, 
at 40 percent energy, followed by a 1-minute waiting period, then two 
subsequent three strike sets.
    (2) Soft start is required for any impact driving, including at the 
beginning of the day, after 30 minutes of pre-activity monitoring, and 
at any time following a cessation of impact pile driving of 30 minutes 
or longer.
    (h) Airgun ramp up. (1) Ramp up must be used at the start of airgun 
operations, including after a power down, shutdown, and after any 
period greater than 10 minutes in duration without airgun operations.
    (2) The rate of ramp up must be no more than 6 dB per 5-minute 
period.
    (3) Ramp up must begin with the smallest gun in the array that is 
being used for all airgun array configurations.
    (4) During the ramp up, the EZ for the full airgun array must be 
implemented.
    (5) If the complete EZ has not been visible for at least 30 minutes 
prior to the start of operations, ramp up must not commence.
    (6) Ramp up of the airguns must not be initiated if a marine mammal 
is sighted within or entering the EZ at any time.
    (i) Airgun power down. (1) If a marine mammal, other than a beluga 
whale, is detected outside the safety zone (SZ) but is likely to enter 
that zone, the airguns may be powered down before the animal is within 
the safety zone, as an alternative to a complete shutdown. Likewise, if 
a marine mammal is already within the SZ when first detected, the 
airguns may be powered down if the PSOs determine it is a reasonable 
alternative to an immediate shutdown. If a marine mammal is already 
within the EZ when first detected, the airguns must be shut down 
immediately.
    (2) Following a power down, airgun activity must not resume until 
the marine mammal has cleared the SZ. The animal will be considered to 
have cleared the SZ if it:
    (i) Is visually observed to have left the SZ; or
    (ii) Has not been seen within the SZ for 15 min in the case of 
pinnipeds and porpoises; or
    (iii) Has not been seen within the SZ for 30 min in the case of 
cetaceans.
    (3) A mitigation airgun must not operate for longer than three 
hours.
    (j) Aircraft mitigation. (1) Hilcorp must use aircraft daily to 
survey the planned seismic survey area prior to the start of seismic 
surveying. Surveying must not begin unless the aerial flights confirm 
the proposed survey area for that day is clear of beluga whales.
    (2) If beluga whales are sighted during flights, start of seismic 
surveying must be delayed until it is confirmed the area is free of 
beluga whales.
    (k) Beluga exclusion zone. Hilcorp must not operate with noise 
producing activity within 10 miles (16 km) of the mean higher high 
water (MHHW) line of the Susitna Delta (Beluga River to the Little 
Susitna River) between April 15 and October 15.


Sec.  217.165   Requirements for monitoring and reporting.

    (a) Marine Mammal Monitoring Protocols. Hilcorp must conduct 
briefings between construction supervisors and crews and the observer 
team prior to the start of all pile driving and removal activities, and 
when new personnel join the work. Trained observers must receive a 
general environmental awareness briefing conducted by Hilcorp staff. At 
minimum, training must include identification of marine mammals that 
may occur in the project vicinity and relevant mitigation and 
monitoring requirements. All observers must have no other construction-
related tasks while conducting monitoring.
    (b) Activities must only commence when the entire exclusion zone 
(EZ) is visible to the naked eye and can be adequately monitored. If 
conditions (e.g., fog) prevent the visual detection of marine mammals, 
activities must not be initiated. For activities other than seismic 
surveying, activity would be halted in low visibility but vibratory 
pile driving or removal would be allowed to continue if started in good 
visibility.
    (c) Monitoring must begin 15 minutes prior to initiation of 
stationary source activity and 30 minutes prior to initiation of mobile 
source activity, occur throughout the time required to complete the 
activity, and continue through 30 minutes post-completion of the 
activity. Pre-activity monitoring must be conducted to ensure that the 
EZ is clear of marine mammals, and activities may only commence once 
observers have declared the EZ clear of marine mammals. In the event of 
a delay or shutdown of activity resulting from marine mammals in the 
EZ, the animals' behavior must be monitored and documented.
    (d) Reporting Measures. (1) Weekly reports. Hilcorp must submit 
weekly reports during the weeks when in-water seismic survey activities 
take place. The weekly field reports would summarize species detected 
(number, location, distance from seismic vessel, behavior), in-water 
activity occurring at the time of the sighting (discharge volume of 
array at time of sighting, seismic activity at time of sighting, visual 
plots of sightings, and number of power downs and shutdowns), 
behavioral reactions to in-water activities, and the number of marine 
mammals exposed.
    (2) Monthly reports. Monthly reports must be submitted to NMFS for 
all months during which in-water seismic activities take place. The 
monthly report must contain and summarize the following information: 
Dates, times, locations, heading, speed, weather, sea conditions 
(including Beaufort sea state and wind force), and associated 
activities during all seismic operations and marine mammal sightings; 
Species, number, location, distance from the vessel, and behavior of 
any sighted marine mammals, as well as associated seismic activity 
(number of power-downs and shutdowns), observed throughout all 
monitoring activities; An estimate of the number (by species) exposed 
to the seismic activity (based on visual observation) at received 
levels greater than or equal to the NMFS thresholds discussed above 
with a discussion of any specific behaviors those individuals 
exhibited; A description of the implementation and effectiveness of the 
terms and conditions of the Biological Opinion's Incidental Take 
Statement (ITS) and mitigation measures of the LOA.
    (3) Annual Reports. (i) Hilcorp must submit an annual report within 
90 days after each activity year, starting from the date when the LOA 
is issued (for the first annual report) or from the date when the 
previous annual report ended.
    (ii) Annual reports would detail the monitoring protocol, summarize 
the data recorded during monitoring, and estimate the number of marine 
mammals that may have been harassed during the period of the report.
    (iii) NMFS would provide comments within 30 days after receiving 
annual reports, and Hilcorp must address the comments and submit 
revisions within 30 days after receiving NMFS comments. If no comment 
is received from the NMFS within 30 days, the annual report will be 
considered completed.
    (4) Final report. (i) Hilcorp must submit a comprehensive summary

[[Page 12376]]

report to NMFS not later than 90 days following the conclusion of 
marine mammal monitoring efforts described in this subpart.
    (ii) The final report must synthesize all data recorded during 
marine mammal monitoring, and estimate the number of marine mammals 
that may have been harassed through the entire project.
    (iii) NMFS would provide comments within 30 days after receiving 
this report, and Hilcorp must address the comments and submit revisions 
within 30 days after receiving NMFS comments. If no comment is received 
from the NMFS within 30 days, the final report will be considered as 
final.
    (5) Reporting of injured or dead marine mammals. (i) In the event 
that personnel involved in the survey activities discover an injured or 
dead marine mammal, Hilcorp must report the incident to the Office of 
Protected Resources (OPR), NMFS (301-427-8401) and to regional 
stranding network (877-925-7773) as soon as feasible. The report must 
include the following information:
    (A) Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
    (B) Species identification (if known) or description of the 
animal(s) involved;
    (C) Condition of the animal(s) (including carcass condition if the 
animal is dead);
    (D) Observed behaviors of the animal(s), if alive;
    (E) If available, photographs or video footage of the animal(s); 
and
    (F) General circumstances under which the animal was discovered.
    (ii) In the event of a ship strike of a marine mammal by any vessel 
involved in the survey activities, Hilcorp must report the incident to 
OPR, NMFS and to regional stranding networks as soon as feasible. The 
report must include the following information:
    (A) Time, date, and location (latitude/longitude) of the incident;
    (B) Species identification (if known) or description of the 
animal(s) involved;
    (C) Vessel's speed during and leading up to the incident;
    (D) Vessel's course/heading and what operations were being 
conducted (if applicable);
    (E) Status of all sound sources in use;
    (F) Description of avoidance measures/requirements that were in 
place at the time of the strike and what additional measures were 
taken, if any, to avoid strike;
    (G) Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, visibility) immediately preceding the 
strike;
    (H) Estimated size and length of animal that was struck;
    (I) Description of the behavior of the marine mammal immediately 
preceding and following the strike;
    (J) If available, description of the presence and behavior of any 
other marine mammals immediately preceding the strike;
    (K) Estimated fate of the animal (e.g., dead, injured but alive, 
injured and moving, blood or tissue observed in the water, status 
unknown, disappeared); and
    (L) To the extent practicable, photographs or video footage of the 
animal(s).
    (iii) In the event of a live stranding (or near-shore atypical 
milling) event within 50 km of the survey operations, where the NMFS 
stranding network is engaged in herding or other interventions to 
return animals to the water, the Director of OPR, NMFS (or designee) 
will advise Hilcorp of the need to implement shutdown procedures for 
all active acoustic sources operating within 50 km of the stranding. 
Shutdown procedures for live stranding or milling marine mammals 
include the following:
    (A) If at any time, the marine mammal(s) die or are euthanized, or 
if herding/intervention efforts are stopped, the Director of OPR, NMFS 
(or designee) will advise Hilcorp that the shutdown around the animals' 
location is no longer needed.
    (B) Otherwise, shutdown procedures must remain in effect until the 
Director of OPR, NMFS (or designee) determines and advises Hilcorp that 
all live animals involved have left the area (either of their own 
volition or following an intervention).
    (C) If further observations of the marine mammals indicate the 
potential for re-stranding, additional coordination with Hilcorp must 
occur to determine what measures are necessary to minimize that 
likelihood (e.g., extending the shutdown or moving operations farther 
away) and Hilcorp must implement those measures as appropriate.
    (iv) If NMFS determines that the circumstances of any marine mammal 
stranding found in the vicinity of the activity suggest investigation 
of the association with survey activities is warranted, and an 
investigation into the stranding is being pursued, NMFS will submit a 
written request to Hilcorp indicating that the following initial 
available information must be provided as soon as possible, but no 
later than 7 business days after the request for information.
    (A) Status of all sound source use in the 48 hours preceding the 
estimated time of stranding and within 50 km of the discovery/
notification of the stranding by NMFS; and
    (B) If available, description of the behavior of any marine 
mammal(s) observed preceding (i.e., within 48 hours and 50 km) and 
immediately after the discovery of the stranding.
    (C) In the event that the investigation is still inconclusive, the 
investigation of the association of the survey activities is still 
warranted, and the investigation is still being pursued, NMFS may 
provide additional information requests, in writing, regarding the 
nature and location of survey operations prior to the time period 
above.


Sec.  217.166   Letters of authorization.

    (a) To incidentally take marine mammals pursuant to these 
regulations, Hilcorp must apply for and obtain (LOAs) in accordance 
with Sec.  216.106 of this chapter for conducting the activity 
identified in Sec.  217.160(c).
    (b) LOAs, unless suspended or revoked, may be effective for a 
period of time not to extend beyond the expiration date of these 
regulations.
    (c) An LOA application must be submitted to the Director, Office of 
Protected Resources, NMFS, by December 31st of the year preceding the 
desired start date.
    (d) An LOA application must include the following information:
    (1) The date(s), duration, and the area(s) where the activity will 
occur;
    (2) The species and/or stock(s) of marine mammals likely to be 
found within each area;
    (3) The estimated number of takes for each marine mammal stock 
potentially affected in each area for the period of effectiveness of 
the Letter of Authorization.
    (4) If an application is for an LOA renewal, it must meet the 
requirements set forth in Sec.  217.167.
    (e) In the event of projected changes to the activity or to 
mitigation, monitoring, reporting (excluding changes made pursuant to 
the adaptive management provision of Sec.  217.97(c)(1)) required by an 
LOA, Hilcorp must apply for and obtain a modification of LOAs as 
described in Sec.  217.167.
    (f) Each LOA must set forth:
    (1) Permissible methods of incidental taking;
    (2) Means of effecting the least practicable adverse impact (i.e., 
mitigation) on the species, their habitat, and the availability of the 
species for subsistence uses; and
    (3) Requirements for monitoring and reporting.

[[Page 12377]]

    (g) Issuance of the LOA(s) must be based on a determination that 
the level of taking must be consistent with the findings made for the 
total taking allowable under these regulations.
    (h) If NMFS determines that the level of taking is resulting or may 
result in more than a negligible impact on the species or stocks of 
such marine mammal, the LOA may be modified or suspended after notice 
and a public comment period.
    (i) Notice of issuance or denial of the LOA(s) must be published in 
the Federal Register within 30 days of a determination.


Sec.  217.167   Renewals and modifications of letters of authorization 
and adaptive management.

    (a) An LOA issued under Sec. Sec.  216.106 of this chapter and 
217.166 for the activity identified in Sec.  217.160(c) may be renewed 
or modified upon request by the applicant, provided that the following 
are met:
    (1) Notification to NMFS that the activity described in the 
application submitted under Sec.  217.160(a) will be undertaken and 
that there will not be a substantial modification to the described 
work, mitigation or monitoring undertaken during the upcoming or 
remaining LOA period;
    (2) Timely receipt (by the dates indicated) of monitoring reports, 
as required under Sec.  217.165(C)(3);
    (3) A determination by the NMFS that the mitigation, monitoring and 
reporting measures required under Sec.  217.165(c) and the LOA issued 
under Sec. Sec.  216.106 of this chapter and 217.166, were undertaken 
and are expected to be undertaken during the period of validity of the 
LOA.
    (b) If a request for a renewal of a Letter of Authorization 
indicates that a substantial modification, as determined by NMFS, to 
the described work, mitigation or monitoring undertaken during the 
upcoming season will occur, NMFS will provide the public a period of 30 
days for review and comment on the request as well as the proposed 
modification to the LOA. Review and comment on renewals of Letters of 
Authorization are restricted to:
    (1) New cited information and data indicating that the original 
determinations made for the regulations are in need of reconsideration; 
and
    (2) Proposed changes to the mitigation and monitoring requirements 
contained in these regulations or in the current Letter of 
Authorization.
    (c) A notice of issuance or denial of a renewal of a Letter of 
Authorization will be published in the Federal Register within 30 days 
of a determination.
    (d) An LOA issued under Sec. Sec.  216.16 of this chapter and 
217.166 for the activity identified in Sec.  217.160 may be modified by 
NMFS under the following circumstances:
    (1) Adaptive management. NMFS, in response to new information and 
in consultation with Hilcorp, may modify the mitigation or monitoring 
measures in subsequent LOAs if doing so creates a reasonable likelihood 
of more effectively accomplishing the goals of mitigation and 
monitoring set forth in the preamble of these regulations.
    (i) Possible sources of new data that could contribute to the 
decision to modify the mitigation or monitoring measures include:
    (A) Results from Hilcorp's monitoring from the previous year(s).
    (B) Results from marine mammal and/or sound research or studies.
    (C) Any information that reveals marine mammals may have been taken 
in a manner, extent or number not authorized by these regulations or 
subsequent LOAs.
    (ii) If, through adaptive management, the modifications to the 
mitigation, monitoring, or reporting measures are substantial, NMFS 
will publish a notice of proposed LOA in the Federal Register and 
solicit public comment.
    (2) NMFS will withdraw or suspend an LOA if, after notice and 
opportunity for public comment, NMFS determines these regulations are 
not being substantially complied with or that the taking allowed is or 
may be having more than a negligible impact on an affected species or 
stock specified in Sec.  217.162(b) or an unmitigable adverse impact on 
the availability of the species or stock for subsistence uses. The 
requirement for notice and comment will not apply if NMFS determines 
that an emergency exists that poses a significant risk to the well-
being of the species or stocks of marine mammals. Notice would be 
published in the Federal Register within 30 days of such action.


Sec. Sec.  217.168--217.169  [Reserved]

[FR Doc. 2019-05781 Filed 3-29-19; 8:45 am]
 BILLING CODE 3510-22-P