[Federal Register Volume 80, Number 42 (Wednesday, March 4, 2015)]
[Notices]
[Pages 11726-11775]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-04427]



[[Page 11725]]

Vol. 80

Wednesday,

No. 42

March 4, 2015

Part II





Department of Commerce





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National Oceanic and Atmospheric Administration





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Takes of Marine Mammals Incidental to Specified Activities; Taking 
Marine Mammals Incidental to an Exploration Drilling Program in the 
Chukchi Sea, Alaska; Notice

Federal Register / Vol. 80 , No. 42 / Wednesday, March 4, 2015 / 
Notices

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XD655


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to an Exploration Drilling Program in 
the Chukchi Sea, Alaska

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

ACTION: Notice; proposed incidental harassment authorization; request 
for comments.

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SUMMARY: NMFS received an application from Shell Gulf of Mexico Inc. 
(Shell) for an Incidental Harassment Authorization (IHA) to take marine 
mammals, by harassment, incidental to offshore exploration drilling on 
Outer Continental Shelf (OCS) leases in the Chukchi Sea, Alaska. 
Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting 
comments on its proposal to issue an IHA to Shell to take, by Level B 
harassment only, 12 species of marine mammals during the specified 
activity.

DATES: Comments and information must be received no later than April 3, 
2015.

ADDRESSES: Comments on the application should be addressed to Jolie 
Harrison, Chief, Permits and Conservation Division, Office of Protected 
Resources, National Marine Fisheries Service, 1315 East-West Highway, 
Silver Spring, MD 20910. The mailbox address for providing email 
comments is <a href="/cdn-cgi/l/email-protection#f4bda0a4dab381959ab49a9b9595da939b82"><span class="__cf_email__" data-cfemail="501904007e1725313e103e3f31317e373f26">[email protected]</span></a>. NMFS is not responsible for email 
comments sent to addresses other than the one provided here. Comments 
sent via email, including all attachments, must not exceed a 10-
megabyte file size.
    Instructions: All comments received are a part of the public record 
and will generally be posted to http://www.nmfs.noaa.gov/pr/permits/incidental.htm without change. All Personal Identifying Information 
(for example, name, address, etc.) voluntarily submitted by the 
commenter may be publicly accessible. Do not submit Confidential 
Business Information or otherwise sensitive or protected information.
    A copy of the application, which contains several attachments, 
including Shell's marine mammal mitigation and monitoring plan (4MP) 
and Plan of Cooperation, used in this document may be obtained by 
writing to the address specified above, telephoning the contact listed 
below (see FOR FURTHER INFORMATION CONTACT), or visiting the internet 
at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm. Documents cited 
in this notice may also be viewed, by appointment, during regular 
business hours, at the aforementioned address.

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

SUPPLEMENTARY INFORMATION:

Background

    Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) 
direct 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 if certain 
findings are made and either regulations are issued or, if the taking 
is limited to harassment, a notice of a proposed authorization is 
provided to the public for review.
    An authorization for incidental takings shall be granted if NMFS 
finds that the taking will have a negligible impact on the species or 
stock(s), will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for subsistence uses (where 
relevant), and if the permissible methods of taking 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.''
    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].

Summary of Request

    On September 18, 2014, Shell submitted an application to NMFS for 
the taking of marine mammals incidental to exploration drilling 
activities in the Chukchi Sea, Alaska. After receiving comments and 
questions from NMFS, Shell revised its IHA application and 4MP on 
December 17, 2014. NMFS determined that the application was adequate 
and complete on January 5, 2015.
    The proposed activity would occur between July and October 2015. 
The following specific aspects of the proposed activities are likely to 
result in the take of marine mammals: Exploration drilling, supply and 
drilling support vessels using dynamic positioning, mudline cellar 
construction, anchor handling, ice management activities, and zero-
offset vertical seismic profiling (ZVSP) activities.
    Shell has requested an authorization to take 13 marine mammal 
species by Level B harassment. However, the narwhal (Monodon monoceros) 
is not expected to be found in the activity area. Therefore, NMFS is 
proposing to authorize take of 12 marine mammal species, by Level B 
harassment, incidental to Shell's offshore exploration drilling in the 
Chukchi Sea. These species are: beluga whale (Delphinapterus leucas); 
bowhead whale (Balaena mysticetus); gray whale (Eschrichtius robustus); 
killer whale (Orcinus orca); minke whale (Balaenoptera acutorostrata); 
fin whale (Balaenoptera physalus); humpback whale (Megaptera 
novaeangliae); harbor porpoise (Phocoena phocoena); bearded seal 
(Erignathus barbatus); ringed seal (Phoca hispida); spotted seal (P. 
largha); and ribbon seal (Histriophoca fasciata).
    In 2012, NMFS issued two IHAs to Shell to conducted two exploratory 
drilling activities at exploration wells in the Beaufort (77 FR 27284; 
May 9, 2012) and Chukchi (77 FR 27322; May 9, 2012) Seas, Alaska, 
during the 2012 Arctic open-water season (July through October). 
Shell's proposed 2015 exploration drilling program is similar to those 
conducted in 2012. In December 2012, Shell submitted two additional IHA 
applications to take marine mammals incidental to its proposed 
exploratory drilling in Beaufort and Chukchi Seas during the 2013 open-
water season. However, Shell withdrew its application in February 2013.

Description of the Specified Activity

Overview

    Shell proposes to conduct exploration drilling at up to four 
exploration drill sites at Shell's Burger Prospect on the OCS leases 
acquired from the U.S. Department of Interior, Bureau of Ocean Energy 
Management (BOEM). The exploration drilling planned for the

[[Page 11727]]

2015 season is a continuation of the Chukchi Sea exploration drilling 
program that began in 2012, and resulted in the completion of a partial 
well at the location known as Burger A. Exploration drilling will be 
done pursuant to Shell's Chukchi Sea Exploration Plan, Revision 2 (EP).
    Shell plans to use two drilling units, the drillship Noble 
Discoverer (Discoverer) and semi-submersible Transocean Polar Pioneer 
(Polar Pioneer) to drill at up to four locations on the Burger 
Prospect. Both drilling units will be attended to by support vessels 
for the purposes of ice management, anchor handling, oil spill response 
(OSR), refueling, support to drilling units, and resupply. The drilling 
units will be accompanied by an expanded number of support vessels, 
aircraft, and oil spill response vessels (OSRV) greater than the number 
deployed during the 2012 drilling season.

Dates and Duration

    Shell anticipates that its exploration drilling program will occur 
between July 1 and approximately October 31, 2015. The drilling units 
will move through the Bering Strait and into the Chukchi Sea on or 
after July 1, 2015, and then onto the Burger Prospect as soon as ice 
and weather conditions allow. Exploration drilling activities will 
continue until about October 31, 2015, the drilling units and support 
vessels will exit the Chukchi Sea at the conclusion of the exploration 
drilling season. Transit entirely out of the Chukchi Sea by all vessels 
associated with exploration drilling may take well into the month of 
November due to ice, weather, and sea states.

Specified Geographic Region

    All drill sites at which exploration drilling would occur in 2015 
will be at Shell's Burger Prospect (see Figure 1-1 on page 1-2 of 
Shell's IHA application). Shell has identified a total of six Chukchi 
Sea lease blocks on the Burger Prospect. All six drill sites are 
located more than 64 mi (103 km) off the Chukchi Sea coast. During 
2015, the Discoverer and Polar Pioneer will be used to conduct 
exploration drilling activities at up to four exploration drill sites. 
As with any Arctic exploration program, weather and ice conditions will 
dictate actual operations.
    Activities associated with the Chukchi Sea exploration drilling 
program and analyzed herein include operation of the Discoverer, Polar 
Pioneer, and associated support vessels. The drilling units will remain 
at the location of the designated exploration drill sites except when 
mobilizing and demobilizing to and from the Chukchi Sea, transiting 
between drill sites, and temporarily moving off location if it is 
determined ice conditions require such a move to ensure the safety of 
personnel and/or the environment.

Detailed Description of Activities

    The specific activities that may result in incidental taking of 
marine mammals based on the IHA application are limited to Shell's 
exploration drilling program and related activities. Activities include 
exploration drilling sounds, MLC construction, anchor handling while 
mooring a drilling unit at a drill site, vessels on DP when tending to 
a drilling unit, ice management, and zero-offset vertical seismic 
profile (ZVSP) surveys.
(1) Exploration Drilling
    In 2015 Shell plans to continue its exploration drilling program on 
BOEM Alaska OCS leases at drill sites greater than 64 mi (103 km) from 
the Chukchi Sea coast during the 2015 drilling season. Shell plans to 
conduct exploration drilling activities at up to four drill sites at 
the Burger Prospect utilizing two drilling units, the drillship 
Discoverer and the semi-submersible Polar Pioneer.
    During 2012, Shell drilled a partial well at the Burger A drill 
site. Drilling at Burger A did not reach a depth at which a ZVSP survey 
would be conducted. Consequently one was not performed.
    A mudline cellar (MLC) will be constructed at each drill site. The 
MLCs will be constructed in the seafloor using a large diameter bit 
operated by hydraulic motors and suspended from the Discoverer or Polar 
Pioneer.
(2) Support Vessels
    During exploration drilling, the Discoverer and Polar Pioneer will 
be supported by the types of vessels listed in Table 1-1 of Shell's IHA 
application. These drilling units would be accompanied by greater 
number of support vessels and oil spill response vessels than were 
deployed by Shell during 2012 exploration drilling in the Chukchi Sea.
    Two ice management vessels will support the drilling units. These 
vessels will enter and exit the Chukchi Sea with or ahead of the 
drilling units, and will generally remain in the vicinity of the 
drilling units during the drilling season. Ice management and ice 
scouting is expected to occur at distances of 20 mi (32 km) and 30 mi 
(48 km) respectively from drill site locations. However, these vessels 
may have to range beyond these distances depending on ice conditions.
    Up to three anchor handlers will support the drilling units. These 
vessels will enter and exit the Chukchi Sea with or ahead of the 
drilling units, and will generally remain in the vicinity of the 
drilling units during the drilling season. When the vessels are not 
anchor handling, they will be available to provide other general 
support. Two of the three anchor handlers may be used to perform 
secondary ice management tasks if needed.
    The planned exploration drilling activities will use three offshore 
supply vessels (OSVs) for resupply of the drilling units and support 
vessels. Drilling materials, food, fuel, and other supplies will be 
picked up in Dutch Harbor (with possible minor resupply coming out of 
Kotzebue) and transported to the drilling units and support vessels.
    Shell plans to use up to two science vessels; one for each drilling 
unit, from which sampling of ocean water and sediments prior to and 
following drilling discharges would be conducted. The science vessel 
specifications are based on larger OSVs, but smaller vessels may be 
used.
    Two tugs will tow the Polar Pioneer from Dutch Harbor to the Burger 
Prospect. After the Polar Pioneer is moored, the tugs will remain in 
the vicinity of the drilling units to help move either drilling unit in 
the event they need to be moved off of a drilling site due to ice or 
any other event.
    Shell may deploy a MLC ROV system from an OSV type vessel that 
could be used to construct MLCs prior to a drilling units arriving. If 
used, this vessel would be located at a drill site on the Burger 
Prospect. When not in use, the vessel would be outside of the Chukchi 
Sea
(3) Oil Spill Response Vessels
    The oil spill response (OSR) vessel types supporting the 
exploration drilling program are listed in Table 1.2 of Shell's IHA 
application.
    One dedicated OSR barge and on-site oil spill response vessel 
(OSRV) will be staged in the vicinity of the drilling unit(s) when 
drilling into potential liquid hydrocarbon bearing zones. This will 
enable the OSRV to respond to a spill and provide containment, 
recovery, and storage for the initial response period in the unlikely 
event of a well control incident.
    The OSR barge, associated tug, and OSRV possess sufficient storage 
capacity to provide containment, recovery, and storage for the initial 
response period. Shell plans to use two

[[Page 11728]]

oil storage tankers (OSTs). An OST will be staged at the Burger 
Prospect. The OST will hold fuel for Shell's drilling units, support 
vessels, and have space for storage of recovered liquids in the 
unlikely event of a well control incident. A second OST will be 
stationed in the Chukchi Sea and sited such that it will be able to 
respond to a well control event before the first tanker reaches its 
recovered liquid capacity.
    The tug and barge will be used for nearshore OSR. The nearshore tug 
and barge will be moored near Goodhope Bay, Kotzebue Sound. The 
nearshore tug and barge will also carry response equipment, including 
one 47 ft. (14 m) skimming vessel, 34 ft. (10 m) workboats, mini-
barges, boom and duplex skimming units for nearshore recovery and 
possibly support nearshore protection. The nearshore tug and barge will 
also carry designated response personnel and will mobilize to recovery 
areas, deploy equipment, and begin response operations.
(4) Aircraft
    Offshore operations will be serviced by up to three helicopters 
operated out of an onshore support base in Barrow. The helicopters are 
not yet contracted. Sikorsky S-92s (or similar) will be used to 
transport crews between the onshore support base, the drilling units 
and support vessels with helidecks. The helicopters will also be used 
to haul small amounts of food, materials, equipment, samples and waste 
between vessels and the shorebase. Approximately 40 Barrow to Burger 
Prospect round trip flights will occur each week to support the 
additional crew change necessities for an additional drilling unit, 
support vessels, and required sampling.
    The route chosen will depend on weather conditions and whether 
subsistence users are active on land or at sea. These routes may be 
modified depending on weather and subsistence uses.
    Shell will also have a dedicated helicopter for Search and Rescue 
(SAR). The SAR helicopter is expected to be a Sikorsky S-92 (or 
similar). This aircraft will stay grounded at the Barrow shore base 
location except during training drills, emergencies, and other non-
routine events. The SAR helicopter and crew plan training flights for 
approximately 40 hr/month.
    A fixed wing propeller or turboprop aircraft, such as the Saab 340-
B, Beechcraft 1900, or De Havilland Dash 8, will be used to transport 
crews, materials, and equipment between Wainwright and hub airports 
such as Barrow or Fairbanks. It is anticipated that there will be one 
round trip flight every three weeks.
    A fixed wing aircraft, Gulfstream Aero-Commander (or similar), will 
be used for photographic surveys of marine mammals. These flights will 
take place daily depending on weather conditions. Flight paths are 
located in the Marine Mammal Monitoring and Mitigation Plan (4MP).
    An additional Gulfstream Aero Commander may be used to provide ice 
reconnaissance flights to monitor ice conditions around the Burger 
Prospect. Typically, the flights will focus on the ice conditions 
within 50 mi (80 km) of the drill sites, but more extensive ice 
reconnaissance may occur beyond 50 mi (80 km).
    These flights will occur at an altitude of approximately 3,000 ft. 
(915 m).
(5) Vertical Seismic Profile
    Shell may conduct a geophysical survey referred to as a vertical 
seismic profile (VSP) survey at each drill site where a well is drilled 
in 2015. During VSP surveys, an airgun array is deployed at a location 
near or adjacent to the drilling units, while receivers are placed 
(temporarily anchored) in the wellbore. The sound source (airgun array) 
is fired, and the reflected sonic waves are recorded by receivers 
(geophones) located in the wellbore. The geophones, typically a string 
of them, are then raised up to the next interval in the wellbore and 
the process is repeated until the entire wellbore has been surveyed. 
The purpose of the VSP is to gather geophysical information at various 
depths, which can then be used to tie-in or groundtruth geophysical 
information from the previous seismic surveys with geological data 
collected within the wellbore.
    Shell will be conducting a particular form of VSP referred to as a 
zero-offset VSP (ZVSP), in which the sound source is maintained at a 
constant location near the wellbore (Figure 1-2 in IHA application). 
Shell may use one of two typical sound sources: (1) A three-airgun 
array consisting of three, 150 cubic inches (in\3\) (2,458 cm\3\) 
airguns, or (2) a two-airgun array consisting of two, 250 in\3\ (4,097 
cm\3\) airguns. Typical receivers would consist of a standard wireline 
four-level vertical seismic imager (VSI) tool, which has four receivers 
50 ft (15.2 m) apart.
    A ZVSP survey is normally conducted at each well after total depth 
is reached, but may be conducted at a shallower depth. For each survey, 
Shell would deploy the sound source (airgun array) over the side of the 
Discoverer or Polar Pioneer with a crane, the sound source will be 50-
200 ft (15-61 m) from the wellhead depending on crane location, and 
reach a depth of approximately 10-23 ft (3-7 m) below the water 
surface. The VSI along with its four receivers will be temporarily 
anchored in the wellbore at depth.
    The sound source will be pressured up to 3,000 pounds per square 
inch (psi), and activated 5-7 times at approximately 20-second 
intervals. The VSI will then be moved to the next interval of the 
wellbore and re-anchored, after which the airgun array will again be 
activated 5-7 times. This process will be repeated until the entire 
wellbore is surveyed. The interval between anchor points for the VSI is 
usually 200-300 ft. (61-91 m). A normal ZVSP survey is conducted over a 
period of about 10-14 hours depending on the depth of the well and the 
number of anchoring points.
(6) Ice Management and Forecasting
    The exploration drilling program is located in an area that is 
characterized by active sea ice movement, ice scouring, and storm 
surges. In anticipation of potential ice hazards that may be 
encountered, Shell will implement a Drilling Ice Management Plan (DIMP) 
to ensure real-time ice and weather forecasting that will identify 
conditions that could put operations at risk, allowing Shell to modify 
its activities accordingly.
    Shell's ice management fleet will consist of four vessels: two ice 
management vessels and two anchor handler/icebreakers. Ice management 
that is necessary for safe operations during Shell's planned 
exploration drilling program will occur far out in the OCS, remote from 
the vicinities of any routine marine vessel traffic in the Chukchi Sea, 
thereby resulting in no threat to public safety or services that occur 
near to shore. Shell vessels will also communicate movements and 
activities through the 2015 North Slope Communications Centers (Com 
Centers). Management of ice will occur during the drilling season 
predominated by open water, thus it will not contribute to ice hazards, 
such as ridging, override, or pileup in an offshore or nearshore 
environment.
    The ice-management/anchor handling vessels will manage the ice by 
deflecting any ice floes that could affect the Discoverer or Polar 
Pioneer when they are drilling or anchor mooring buoys even if the 
drilling units are not anchored at a drill site. When managing ice, the 
ice management vessels will generally operate upwind of the drilling 
units, since the wind and currents contribute to the direction of ice

[[Page 11729]]

movement. Ice reconnaissance or ice scouting forays may occur out to 
48.3km (30mi) from the drilling units and are conducted by the ice 
management vessels into ice that may move into the vicinity of 
exploration drilling activities. This will provide the vessel and 
shore-based ice advisors with the information required to decide 
whether or not active ice management is necessary. The actual distances 
from the drilling units and the patterns of ice management (distances 
between vessels, and width of the swath in which ice management occurs) 
will be determined by the ice floe speed, size, thickness, and 
character, and wind forecast.
    Ice floe frequency and intensity is unpredictable and could range 
from no ice to ice densities that exceed ice-management capabilities, 
in which case drilling activities might be stopped and the drilling 
units disconnected from their moorings and moved off site. The 
Discoverer was disconnected from its moorings once during the 2012 
season to avoid a potential encounter with multi-year ice flows of 
sufficient size to halt activities. Advance scouting of ice primarily 
north and east of the Burger A well by the ice management vessels did 
not detect ice of sufficient size or thickness to warrant disconnecting 
the Discoverer from its moorings during the remainder of the 2012 
season. If ice is present, ice management activities may be necessary 
in early July, at discrete intervals at other times during the season, 
and towards the end of operations in late October. However, data 
regarding historic ice patterns in the area of activities indicate that 
it will not be required throughout the planned 2015 drilling season.
    During the 2012 drilling season, a total of seven days of active 
ice management by vessels occurred in support of Shell's exploration 
drilling program in the Chukchi Sea.
    When ice is present at a drill site, ice disturbance will be 
limited to the minimum amount needed to allow drilling to continue. 
First-year ice will be the type most likely to be encountered. The ice-
management vessel will be tasked with managing the ice so that it flows 
easily around the drilling units and their anchor moorings without 
building up in front of either. This type of ice is managed by the ice-
management vessel continually moving back and forth across the drift 
line, directly up drift of the drilling units and making turns at both 
ends, or in circular patterns. During ice-management, the vessel's 
propeller is rotating at approximately 15 to 20% of the vessel's 
propeller rotation capacity. Ice management occurs with slow movements 
of the vessel using lower power and therefore slower propeller rotation 
speed (i.e., lower cavitation), allowing for fewer repositions of the 
vessel, and thereby reducing cavitation effects in the water. 
Occasionally, there may be multi-year ice features that would be 
managed at a much slower speed than that used to manage first-year ice.
    As detailed in Shell's Drilling Ice Management Plan (DIMP), in 2012 
Shell's ice management vessels conducted ice management to protect 
moorings for the Discoverer after the drilling unit was moved off of 
the Burger A well. This work consisted of re-directing flows as 
necessary to avoid potential impact with mooring buoys, without the 
necessity to break up multi-year ice flowbergs. Actual breaking of ice 
may need to occur in the event that ice conditions in the immediate 
vicinity of activities create a safety hazard for the drilling unit, or 
its moorings. In such a circumstance, operations personnel will follow 
the guidelines established in the DIMP to evaluate ice conditions and 
make the formal designation of a hazardous ice alert condition, which 
would trigger the procedures that govern any actual icebreaking 
operations. Despite Shell's experience in 2012, historical data 
relative to ice conditions in the Chukchi Sea in the vicinity of 
Shell's planned 2015 activities, establishes that there is a low 
probability for the type of hazardous ice conditions that might 
necessitate icebreaking (e.g., records of the National Naval Ice Center 
archives; Shell/SIWAC). The probability could be greater at the 
beginning and/or the end of the drilling season (early July or late 
October). For the purposes of evaluating possible impacts of the 
planned activities, Shell has assumed icebreaking activities for a 
limited period of time, and estimated incidental exposures of marine 
mammals from such activities.

Description of Marine Mammals in the Area of the Specified Activity

    The Chukchi Sea supports a diverse assemblage of marine mammals, 
including: Bowhead, gray, beluga, killer, minke, humpback, and fin 
whales; harbor porpoise; ringed, ribbon, spotted, and bearded seals; 
narwhals; polar bears (Ursus maritimus); and walruses (Odobenus 
rosmarus divergens; see Table 4-1 in Shell's application). The bowhead, 
humpback, and fin whales are listed as ``endangered'' under the 
Endangered Species Act (ESA) and as depleted under the MMPA. The ringed 
seal is listed as ``threatened'' under the ESA. Certain stocks or 
populations of gray, beluga, and killer whales and spotted seals are 
listed as endangered or are proposed for listing under the ESA; 
however, none of those stocks or populations occur in the proposed 
activity area. Both the walrus and the polar bear are managed by the 
U.S. Fish and Wildlife Service (USFWS) and are not considered further 
in this proposed IHA notice.
    Of these species, 12 are expected to occur in the area of Shell's 
proposed operations. These species are: The bowhead, gray, humpback, 
minke, fin, killer, and beluga whales; harbor porpoise; and the ringed, 
spotted, bearded, and ribbon seals. Beluga, bowhead, and gray whales, 
harbor porpoise, and ringed, bearded, and spotted seals are anticipated 
to be encountered more than the other marine mammal species mentioned 
here. The marine mammal species that is likely to be encountered most 
widely (in space and time) throughout the period of the proposed 
drilling program is the ringed seal. Encounters with bowhead and gray 
whales are expected to be limited to particular seasons, as discussed 
later in this document. Where available, Shell used density estimates 
from peer-reviewed literature in the application. In cases where 
density estimates were not readily available in the peer-reviewed 
literature, Shell used other methods to derive the estimates. NMFS 
reviewed the density estimate descriptions and articles from which 
estimates were derived and requested additional information to better 
explain the density estimates presented by Shell in its application. 
This additional information was included in the revised IHA 
application. The explanation for those derivations and the actual 
density estimates are described later in this document (see the 
``Estimated Take by Incidental Harassment'' section).
    The narwhal occurs in Canadian waters and occasionally in the 
Alaskan Beaufort Sea and the Chukchi Sea, but it is considered 
extralimital in U.S. waters and is not expected to be encountered. 
There are scattered records of narwhal in Alaskan waters, including 
reports by subsistence hunters, where the species is considered 
extralimital (Reeves et al., 2002). Due to the rarity of this species 
in the proposed project area and the remote chance it would be affected 
by Shell's proposed Chukchi Sea drilling activities, this species is 
not discussed further in this proposed IHA notice.
    Shell's application contains information on the status, 
distribution, seasonal distribution, abundance, and life history of 
each of the species under NMFS jurisdiction mentioned in this

[[Page 11730]]

document. When reviewing the application, NMFS determined that the 
species descriptions provided by Shell correctly characterized the 
status, distribution, seasonal distribution, and abundance of each 
species. Please refer to the application for that information (see 
ADDRESSES). Additional information can also be found in the NMFS Stock 
Assessment Reports (SAR). The Alaska 2013 SAR is available at: http://www.nmfs.noaa.gov/pr/sars/pdf/ak2013_final.pdf.
    Table 1 lists the 12 marine mammal species or stocks under NMFS 
jurisdiction with confirmed or possible occurrence in the proposed 
project area.

                Table 1--Marine Mammal Species and Stocks With Confirmed or Possible Occurrence in the Proposed Exploration Drilling Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
           Common name                Scientific name           Status             Occurrence          Seasonality             Range          Abundance
--------------------------------------------------------------------------------------------------------------------------------------------------------
Odontocetes:
    Beluga whale (Eastern Chukchi  Dephinapterus leucas  ...................  Common.............  Mostly spring and    Russia to Canada...        3,710
     Sea stock).                                                                                    fall with some in
                                                                                                    summer.
    Beluga whale (Beaufort Sea     Delphinapterus        ...................  Common.............  Mostly spring and    Russia to Canada...       39,258
     stock).                        leucas.                                                         fall with some in
                                                                                                    summer.
    Killer whale.................  Orcinus orca........  ...................  Occasional/          Mostly summer and    California to              2,084
                                                                               Extralimital.        early fall.          Alaska.
    Harbor porpoise..............  Phocoena phocoena...  ...................  Occasional/          Mostly summer and    California to             48,215
                                                                               Extralimital.        early fall.          Alaska.
Mysticetes:
    Bowhead whale................  Balaena mysticetus..  Endangered;          Common.............  Mostly spring and    Russia to Canada...       19,534
                                                          Depleted.                                 fall with some in
                                                                                                    summer.
    Gray whale...................  Eschrichtius          ...................  Somewhat common....  Mostly summer......  Mexico to the U.S.        19,126
                                    robustus.                                                                            Arctic Ocean.
    Minke whale..................  Balaenoptera          ...................  Rare...............  Summer.............  North Pacific......    810-1,003
                                    acutorostrata.
    Fin whale (North Pacific       B. physalus.........  Endangered;          Rare...............  Summer.............  North Pacific......        1,652
     stock).                                              Depleted.
    Humpback whale (Central North  Megaptera             Endangered;          Rare...............  Summer.............  Central to North          20,800
     Pacific stock).                novaeangliae.         Depleted.                                                      Pacific.
Pinnipeds:
    Bearded seal (Beringia         Erigathus barbatus..  Candidate..........  Common.............  Spring and summer..  Bering, Chukchi,         155,000
     distinct population segment).                                                                                       and Beaufort Seas.
    Ringed seal (Arctic stock)...  Phoca hispida.......  Threatened;          Common.............  Year round.........  Bering, Chukchi,         300,000
                                                          Depleted.                                                      and Beaufort Seas.
    Spotted seal.................  Phoca largha........  ...................  Common.............  Summer.............  Japan to U.S.            141,479
                                                                                                                         Arctic Ocean.
    Ribbon seal..................  Histriophoca          Species of concern.  Occasional.........  Summer.............  Russia to U.S.            49,000
                                    fasciata.                                                                            Arctic Ocean.
--------------------------------------------------------------------------------------------------------------------------------------------------------

Potential Effects of the Specified Activity on Marine Mammals

    This section includes a summary and discussion of the ways that the 
types of stressors associated with the specified activity (e.g., 
drilling, seismic airgun, vessel movement) have been observed to or are 
thought to impact marine mammals. This section is intended as a 
background of potential effects and does not consider either the 
specific manner in which this activity will be carried out or the 
mitigation that will be implemented or how either of those will shape 
the anticipated impacts from this specific activity. The ``Estimated 
Take by Incidental Harassment'' section later in this document will 
include a quantitative analysis of the number of individuals that are 
expected to be taken by this activity. The ``Negligible Impact 
Analysis'' section will include the analysis of how this specific 
activity will impact marine mammals and will consider the content of 
this section, the ``Estimated Take by Incidental Harassment'' section, 
the ``Mitigation'' section, and the ``Anticipated Effects on Marine 
Mammal Habitat'' section to draw conclusions regarding the likely 
impacts of this activity on the reproductive success or survivorship of 
individuals and from that on the affected marine mammal populations or 
stocks.

Background on Sound

    Sound is a physical phenomenon consisting of minute vibrations that 
travel through a medium, such as air or water, and is generally 
characterized by several variables. Frequency describes the sound's 
pitch and is measured in hertz (Hz) or kilohertz (kHz), while sound 
level describes the sound's intensity and is measured in decibels (dB). 
Sound level increases or decreases exponentially with each dB of 
change. The logarithmic nature of the scale means that each 10-dB 
increase is a 10-fold increase in acoustic power (and a 20-dB increase 
is then a 100-fold increase in power). A 10-fold increase in acoustic 
power does not mean that the

[[Page 11731]]

sound is perceived as being 10 times louder, however. Sound levels are 
compared to a reference sound pressure (micro-Pascal) to identify the 
medium. For air and water, these reference pressures are ``re 20 
[micro] Pa'' and ``re 1 [micro] Pa,'' respectively. Root mean square 
(RMS) is the quadratic mean sound pressure over the duration of an 
impulse. RMS is calculated by squaring all of the sound amplitudes, 
averaging the squares, and then taking the square root of the average 
(Urick, 1983). RMS 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 rather than by peak pressures.

Exploration Drilling Program Sound Characteristics

(1) Drilling Sounds
    Exploration drilling will be conducted from the drilling units 
Discoverer and Polar Pioneer. Underwater sound propagation during the 
activities results from the use of generators, drilling machinery, and 
the drilling units themselves. Sound levels during vessel-based 
operations may fluctuate depending on the specific type of activity at 
a given time and aspect from the vessel. Underwater sound levels may 
also depend on the specific equipment in operation. Lower sound levels 
have been reported during well logging than during drilling operations 
(Greene 1987b), and underwater sound appeared to be lower at the bow 
and stern aspects than at the beam (Greene 1987a).
    Most drilling sounds generated from vessel-based operations occur 
at relatively low frequencies below 600 Hz although tones up to 1,850 
Hz were recorded by Greene (1987a) during drilling operations in the 
Beaufort Sea. At a range of 0.17 km, the 20-1000 Hz band level was 122-
125 dB re 1[mu] Pa rms for the drillship Explorer I. Underwater sound 
levels were slightly higher (134 db re 1[mu] Pa rms) during drilling 
activity from the Explorer II at a range of 0.20 km; although tones 
were only recorded below 600 Hz. Underwater sound measurements from the 
Kulluk in 1986 at 0.98 km were higher (143 dB re 1[mu] Pa rms) than 
from the other two vessels. Measurements of the Discoverer on the 
Burger prospect in 2012, without any support vessels operating nearby, 
showed received sound levels of 120 dB re 1 [mu] Pa rms at 1.5 km. The 
Polar Pioneer, a semi-submersible drilling unit, is expected to 
introduce less sound into the water than the Discoverer during drilling 
and related activities.
(2) Airgun Sounds
    Two sound sources have been proposed by Shell for the ZVSP surveys 
in 2015. The first is a small airgun array that consists of three 150 
in\3\ (2,458 cm\3\) airguns for a total volume of 450 in\3\ (7,374 
cm\3\). The second ZVSP sound source consists of two 250 in\3\ (4097 
cm\3\) airguns with a total volume of 500 in\3\ (8,194 cm\3\). 
Typically, a single ZVSP survey will be performed when the well has 
reached PTD or final depth although, in some instances, a prior ZVSP 
will have been performed at a shallower depth. A typical survey, would 
last 10-14 hours, depending on the depth of the well and the number of 
anchoring points, and include firings of up to the full array, plus 
additional firing of the smallest airgun in the array to be used as a 
``mitigation airgun'' while the geophones are relocated within the 
wellbore.
    Airguns function by venting high-pressure air into the water. The 
pressure signature of an individual airgun consists of a sharp rise and 
then fall in pressure, followed by several positive and negative 
pressure excursions caused by oscillation of the resulting air bubble. 
The sizes, arrangement, and firing times of the individual airguns in 
an array are designed and synchronized to suppress the pressure 
oscillations subsequent to the first cycle. A typical high-energy 
airgun arrays emit most energy at 10-120 Hz. However, the pulses 
contain energy up to 500-1000 Hz and some energy at higher frequencies 
(Goold and Fish 1998; Potter et al. 2007).
(3) Aircraft Noise
    Helicopters may be used for personnel and equipment transport to 
and from the drilling units and support vessels. Under calm conditions, 
rotor and engine sounds are coupled into the water within a 26[deg] 
cone beneath the aircraft. Some of the sound will transmit beyond the 
immediate area, and some sound will enter the water outside the 26[deg] 
area when the sea surface is rough. However, scattering and absorption 
will limit lateral propagation in the shallow water.
    Dominant tones in noise spectra from helicopters are generally 
below 500 Hz (Greene and Moore 1995). Harmonics of the main rotor and 
tail rotor usually dominate the sound from helicopters; however, many 
additional tones associated with the engines and other rotating parts 
are sometimes present. Because of doppler shift effects, the 
frequencies of tones received at a stationary site diminish when an 
aircraft passes overhead. The apparent frequency is increased while the 
aircraft approaches and is reduced while it moves away.
    Aircraft flyovers are not heard underwater for very long, 
especially when compared to how long they are heard in air as the 
aircraft approaches an observer. Helicopters flying to and from the 
drilling units will generally maintain straight-line routes at 
altitudes of 1,500 ft. (457 m) above sea level, thereby limiting the 
received levels at and below the surface.
(4) Vessel Noise
    In addition to the drilling units, various types of vessels will be 
used in support of the operations including ice management vessels, 
anchor handlers, OSVs, and OSR vessels. Sounds from boats and vessels 
have been reported extensively (Greene and Moore 1995; Blackwell and 
Greene 2002, 2005, 2006). Numerous measurements of underwater vessel 
sound have been performed in support of recent industry activity in the 
Chukchi and Beaufort Seas. Results of these measurements were reported 
in various 90-day and comprehensive reports since 2007. For example, 
Garner and Hannay (2009) estimated sound pressure levels of 100 dB re 1 
[mu] Pa rms at distances ranging from ~1.5 to 2.3 mi (~2.4 to 3.7 km) 
from various types of barges. MacDonnell et al. (2008) estimated higher 
underwater sound pressure levels from the seismic vessel Gilavar of 120 
dB re 1 [mu] Pa rms at ~13 mi (~21 km) from the source, although the 
sound level was only 150 dB re 1 [mu] Pa rms at 85 ft (26 m) from the 
vessel. Like other industry-generated sound, underwater sound from 
vessels is generally at relatively low frequencies. During 2012, 
underwater sound from ten (10) vessels in transit, and in two instances 
towing or providing a tow-assist, were recorded by JASCO in the Chukchi 
Sea as a function of the sound source characterization (SSC) study 
required in the Shell 2012 Chukchi Sea drilling IHA. SSC transit and 
tow results from 2012 include ice management vessels, an anchor 
handler, OSR vessels, the OST, support tugs, and OSVs. The recorded 
sound pressure levels to 120 dB re 1 [mu] Pa rms for vessels in transit 
primarily range from ~0.8-4.3 mi (1.3-6.9 km), whereas the measured 120 
dB re 1 [mu] Pa rms for the drilling unit Kulluk under tow by the Aiviq 
in the Chukchi Sea was approximately 11.8 mi (19 km) on its way to the 
Beaufort Sea (O'Neil and McCrodan 2012a, b). Measurements of vessel 
sounds from

[[Page 11732]]

Shell's 2012 exploration drilling program in the Chukchi Sea are 
presented in detail in the 2012 Comprehensive Monitoring Report (LGL 
2013).
    The primary sources of sounds from all vessel classes are propeller 
cavitation, propeller singing, and propulsion or other machinery. 
Propeller cavitation is usually the dominant noise source for vessels 
(Ross 1976). Propeller cavitation and singing are produced outside the 
hull, whereas propulsion or other machinery noise originates inside the 
hull. There are additional sounds produced by vessel activity, such as 
pumps, generators, flow noise from water passing over the hull, and 
bubbles breaking in the wake. Icebreakers contribute greater sound 
levels during ice-breaking activities than ships of similar size during 
normal operation in open water (Richardson et al. 1995a). This higher 
sound production results from the greater amount of power and propeller 
cavitation required when operating in thick ice.

Acoustic Impacts

    When considering the influence of various kinds of sound on the 
marine environment, it is necessary to understand that different kinds 
of marine life are sensitive to different frequencies of sound. Based 
on available behavioral data, audiograms have been derived using 
auditory evoked potentials, anatomical modeling, and other data, 
Southall et al. (2007) designate ``functional hearing groups'' for 
marine mammals and estimate the lower and upper frequencies of 
functional hearing of the groups. The functional groups and the 
associated frequencies are indicated below (though animals are less 
sensitive to sounds at the outer edge of their functional range and 
most sensitive to sounds of frequencies within a smaller range 
somewhere in the middle of their functional hearing range):
    <bullet> Low frequency cetaceans (13 species of mysticetes): 
functional hearing is estimated to occur between approximately 7 Hz and 
30 kHz;
    <bullet> Mid-frequency cetaceans (32 species of dolphins, six 
species of larger toothed whales, and 19 species of beaked and 
bottlenose whales): functional hearing is estimated to occur between 
approximately 150 Hz and 160 kHz;
    <bullet> High frequency cetaceans (eight species of true porpoises, 
six species of river dolphins, Kogia, the franciscana, and four species 
of cephalorhynchids): functional hearing is estimated to occur between 
approximately 200 Hz and 180 kHz;
    <bullet> Phocid pinnipeds in Water: functional hearing is estimated 
to occur between approximately 75 Hz and 100 kHz; and
    <bullet> Otariid pinnipeds in Water: functional hearing is 
estimated to occur between approximately 100 Hz and 40 kHz.
    As mentioned previously in this document, 12 marine mammal species 
or stocks (nine cetaceans and four phocid pinnipeds) may occur in the 
proposed seismic survey area. Of the nine cetacean species or stocks 
likely to occur in the proposed project area and for which take is 
requested, two are classified as low-frequency cetaceans (i.e., bowhead 
and gray whales), two are classified as mid-frequency cetaceans (i.e., 
both beluga stocks and killer whales), and one is classified as a high-
frequency cetacean (i.e., harbor porpoise) (Southall et al., 2007). A 
species functional hearing group is a consideration when we analyze the 
effects of exposure to sound on marine mammals.
(1) Tolerance
    Numerous studies have shown that underwater sounds from industry 
activities are often readily detectable by marine mammals in the water 
at distances of many kilometers. Numerous studies have also shown that 
marine mammals at distances more than a few kilometers away often show 
no apparent response to industry activities of various types (Miller et 
al., 2005; Bain and Williams, 2006). This is often true even in cases 
when the sounds must be readily audible to the animals based on 
measured received levels and the hearing sensitivity of that mammal 
group. Although various baleen whales, toothed whales, and (less 
frequently) pinnipeds have been shown to react behaviorally to 
underwater sound such as airgun pulses or vessels under some 
conditions, at other times mammals of all three types have shown no 
overt reactions (e.g., Malme et al., 1986; Richardson et al., 1995; 
Madsen and Mohl, 2000; Croll et al., 2001; Jacobs and Terhune, 2002; 
Madsen et al., 2002; Miller et al., 2005). In general, pinnipeds and 
small odontocetes seem to be more tolerant of exposure to some types of 
underwater sound than are baleen whales. Richardson et al. (1995a) 
found that vessel noise does not seem to strongly affect pinnipeds that 
are already in the water. Richardson et al. (1995a) went on to explain 
that seals on haul-outs sometimes respond strongly to the presence of 
vessels and at other times appear to show considerable tolerance of 
vessels, and Brueggeman et al. (1992, cited in Richardson et al., 
1995a) observed ringed seals hauled out on ice pans displaying short-
term escape reactions when a ship approached within 0.25-0.5 mi (0.4-
0.8 km).
(2) Masking
    Masking is the obscuring of sounds of interest by other sounds, 
often at similar frequencies. Marine mammals are highly dependent on 
sound, and their ability to recognize sound signals amid other noise is 
important in communication, predator and prey detection, and, in the 
case of toothed whales, echolocation. Even in the absence of manmade 
sounds, the sea is usually noisy. Background ambient noise often 
interferes with or masks the ability of an animal to detect a sound 
signal even when that signal is above its absolute hearing threshold. 
Natural ambient noise includes contributions from wind, waves, 
precipitation, other animals, and (at frequencies above 30 kHz) thermal 
noise resulting from molecular agitation (Richardson et al., 1995a). 
Background noise also can include sounds from human activities. Masking 
of natural sounds can result when human activities produce high levels 
of background noise. Conversely, if the background level of underwater 
noise is high (e.g., on a day with strong wind and high waves), an 
anthropogenic noise source will not be detectable as far away as would 
be possible under quieter conditions and will itself be masked.
    Although some degree of masking is inevitable when high levels of 
manmade broadband sounds are introduced into the sea, marine mammals 
have evolved systems and behavior that function to reduce the impacts 
of masking. Structured signals, such as the echolocation click 
sequences of small toothed whales, may be readily detected even in the 
presence of strong background noise because their frequency content and 
temporal features usually differ strongly from those of the background 
noise (Au and Moore, 1988, 1990). The components of background noise 
that are similar in frequency to the sound signal in question primarily 
determine the degree of masking of that signal.
    Redundancy and context can also facilitate detection of weak 
signals. These phenomena may help marine mammals detect weak sounds in 
the presence of natural or manmade noise. Most masking studies in 
marine mammals present the test signal and the masking noise from the 
same direction. The sound localization abilities of

[[Page 11733]]

marine mammals suggest that, if signal and noise come from different 
directions, masking would not be as severe as the usual types of 
masking studies might suggest (Richardson et al., 1995a). The dominant 
background noise may be highly directional if it comes from a 
particular anthropogenic source such as a ship or industrial site. 
Directional hearing may significantly reduce the masking effects of 
these noises by improving the effective signal-to-noise ratio. In the 
cases of high-frequency hearing by the bottlenose dolphin, beluga 
whale, and killer whale, empirical evidence confirms that masking 
depends strongly on the relative directions of arrival of sound signals 
and the masking noise (Penner et al., 1986; Dubrovskiy, 1990; Bain et 
al., 1993; Bain and Dahlheim, 1994). Toothed whales, and probably other 
marine mammals as well, have additional capabilities besides 
directional hearing that can facilitate detection of sounds in the 
presence of background noise. There is evidence that some toothed 
whales can shift the dominant frequencies of their echolocation signals 
from a frequency range with a lot of ambient noise toward frequencies 
with less noise (Au et al., 1974, 1985; Moore and Pawloski, 1990; 
Thomas and Turl, 1990; Romanenko and Kitain, 1992; Lesage et al., 
1999). A few marine mammal species are known to increase the source 
levels or alter the frequency of their calls in the presence of 
elevated sound levels (Dahlheim, 1987; Au, 1993; Lesage et al., 1993, 
1999; Terhune, 1999; Foote et al., 2004; Parks et al., 2007, 2009; Di 
Iorio and Clark, 2009; Holt et al., 2009).
    These data demonstrating adaptations for reduced masking pertain 
mainly to the very high frequency echolocation signals of toothed 
whales. There is less information about the existence of corresponding 
mechanisms at moderate or low frequencies or in other types of marine 
mammals. For example, Zaitseva et al. (1980) found that, for the 
bottlenose dolphin, the angular separation between a sound source and a 
masking noise source had little effect on the degree of masking when 
the sound frequency was 18 kHz, in contrast to the pronounced effect at 
higher frequencies. Directional hearing has been demonstrated at 
frequencies as low as 0.5-2 kHz in several marine mammals, including 
killer whales (Richardson et al., 1995a). This ability may be useful in 
reducing masking at these frequencies. In summary, high levels of noise 
generated by anthropogenic activities may act to mask the detection of 
weaker biologically important sounds by some marine mammals. This 
masking may be more prominent for lower frequencies. For higher 
frequencies, such as that used in echolocation by toothed whales, 
several mechanisms are available that may allow them to reduce the 
effects of such masking.
    Masking effects of underwater sounds from Shell's proposed 
activities on marine mammal calls and other natural sounds are expected 
to be limited. For example, beluga whales primarily use high-frequency 
sounds to communicate and locate prey; therefore, masking by low-
frequency sounds associated with drilling activities is not expected to 
occur (Gales, 1982, as cited in Shell, 2009). If the distance between 
communicating whales does not exceed their distance from the drilling 
activity, the likelihood of potential impacts from masking would be low 
(Gales, 1982, as cited in Shell, 2009). At distances greater than 660-
1,300 ft (200-400 m), recorded sounds from drilling activities did not 
affect behavior of beluga whales, even though the sound energy level 
and frequency were such that it could be heard several kilometers away 
(Richardson et al., 1995b). This exposure resulted in whales being 
deflected from the sound energy and changing behavior. These minor 
changes are not expected to affect the beluga whale population 
(Richardson et al., 1991; Richard et al., 1998). Brewer et al. (1993) 
observed belugas within 2.3 mi (3.7 km) of the drilling unit Kulluk 
during drilling; however, the authors do not describe any behaviors 
that may have been exhibited by those animals. Please refer to the 
Arctic Multiple-Sale Draft Environmental Impact Statement (USDOI MMS, 
2008), available on the Internet at: http://www.mms.gov/alaska/ref/EIS%20EA/ArcticMultiSale_209/_DEIS.htm, for more detailed information.
    There is evidence of other marine mammal species continuing to call 
in the presence of industrial activity. Annual acoustical monitoring 
near BP's Northstar production facility during the fall bowhead 
migration westward through the Beaufort Sea has recorded thousands of 
calls each year (for examples, see Richardson et al., 2007; Aerts and 
Richardson, 2008). Construction, maintenance, and operational 
activities have been occurring from this facility for over 10 years. To 
compensate and reduce masking, some mysticetes may alter the 
frequencies of their communication sounds (Richardson et al., 1995a; 
Parks et al., 2007). Masking processes in baleen whales are not 
amenable to laboratory study, and no direct measurements on hearing 
sensitivity are available for these species. It is not currently 
possible to determine with precision the potential consequences of 
temporary or local background noise levels. However, Parks et al. 
(2007) found that right whales (a species closely related to the 
bowhead whale) altered their vocalizations, possibly in response to 
background noise levels. For species that can hear over a relatively 
broad frequency range, as is presumed to be the case for mysticetes, a 
narrow band source may only cause partial masking. Richardson et al. 
(1995a) note that a bowhead whale 12.4 mi (20 km) from a human sound 
source, such as that produced during oil and gas industry activities, 
might hear strong calls from other whales within approximately 12.4 mi 
(20 km), and a whale 3.1 mi (5 km) from the source might hear strong 
calls from whales within approximately 3.1 mi (5 km). Additionally, 
masking is more likely to occur closer to a sound source, and distant 
anthropogenic sound is less likely to mask short-distance acoustic 
communication (Richardson et al., 1995a).
    Although some masking by marine mammal species in the area may 
occur, the extent of the masking interference will depend on the 
spatial relationship of the animal and Shell's activity. Almost all 
energy in the sounds emitted by drilling and other operational 
activities is at low frequencies, predominantly below 250 Hz with 
another peak centered around 1,000 Hz. Most energy in the sounds from 
the vessels and aircraft to be used during this project is below 1 kHz 
(Moore et al., 1984; Greene and Moore, 1995; Blackwell et al., 2004b; 
Blackwell and Greene, 2006). These frequencies are mainly used by 
mysticetes but not by odontocetes. Therefore, masking effects would 
potentially be more pronounced in the bowhead and gray whales that 
might occur in the proposed project area. If, as described later in 
this document, certain species avoid the proposed drilling locations, 
impacts from masking are anticipated to be low.
(3) Behavioral Disturbance Reactions
    Behavioral responses to sound are highly variable and context-
specific. Many different variables can influence an animal's perception 
of and response to (in both nature and magnitude) an acoustic event. An 
animal's prior experience with a sound or sound source affects whether 
it is less likely (habituation) or more likely (sensitization) to 
respond to certain sounds in the future (animals can also be innately 
pre-disposed to respond to

[[Page 11734]]

certain sounds in certain ways; Southall et al., 2007). Related to the 
sound itself, the perceived nearness of the sound, bearing of the sound 
(approaching vs. retreating), similarity of a sound to biologically 
relevant sounds in the animal's environment (i.e., calls of predators, 
prey, or conspecifics), and familiarity of the sound may affect the way 
an animal responds to the sound (Southall et al., 2007). Individuals 
(of different age, gender, reproductive status, etc.) among most 
populations will have variable hearing capabilities and differing 
behavioral sensitivities to sounds that will be affected by prior 
conditioning, experience, and current activities of those individuals. 
Often, specific acoustic features of the sound and contextual variables 
(i.e., proximity, duration, or recurrence of the sound or the current 
behavior that the marine mammal is engaged in or its prior experience), 
as well as entirely separate factors such as the physical presence of a 
nearby vessel, may be more relevant to the animal's response than the 
received level alone.
    Exposure of marine mammals to sound sources can result in (but is 
not limited to) no response or any of the following observable 
responses: Increased alertness; orientation or attraction to a sound 
source; vocal modifications; cessation of feeding; cessation of social 
interaction; alteration of movement or diving behavior; avoidance; 
habitat abandonment (temporary or permanent); and, in severe cases, 
panic, flight, stampede, or stranding, potentially resulting in death 
(Southall et al., 2007). On a related note, many animals perform vital 
functions, such as feeding, resting, traveling, and socializing, on a 
diel cycle (24-hr cycle). Behavioral reactions to noise exposure (such 
as disruption of critical life functions, displacement, or avoidance of 
important habitat) 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).
    Detailed studies regarding responses to anthropogenic sound have 
been conducted on humpback, gray, and bowhead whales and ringed seals. 
Less detailed data are available for some other species of baleen 
whales, sperm whales, small toothed whales, and sea otters. The 
following sub-sections provide examples of behavioral responses that 
demonstrate the variability in behavioral responses that would be 
expected given the different sensitivities of marine mammal species to 
sound.
    Baleen Whales--Richardson et al. (1995b) reported changes in 
surfacing and respiration behavior and the occurrence of turns during 
surfacing in bowhead whales exposed to playback of underwater sound 
from drilling activities. These behavioral effects were localized and 
occurred at distances up to 1.2-2.5 mi (2-4 km).
    Some bowheads appeared to divert from their migratory path after 
exposure to projected icebreaker sounds. Other bowheads however, 
tolerated projected icebreaker sound at levels 20 dB and more above 
ambient sound levels. The source level of the projected sound however, 
was much less than that of an actual icebreaker, and reaction distances 
to actual icebreaking may be much greater than those reported here for 
projected sounds.
    Brewer et al. (1993) and Hall et al. (1994) reported numerous 
sightings of marine mammals including bowhead whales in the vicinity of 
offshore drilling operations in the Beaufort Sea. One bowhead whale 
sighting was reported within approximately 1,312 ft (400 m) of a 
drilling vessel although most other bowhead sightings were at much 
greater distances. Few bowheads were recorded near industrial 
activities by aerial observers. After controlling for spatial 
autocorrelation in aerial survey data from Hall et al. (1994) using a 
Mantel test, Schick and Urban (2000) found that the variable describing 
straight line distance between the rig and bowhead whale sightings was 
not significant but that a variable describing threshold distances 
between sightings and the rig was significant. Thus, although the 
aerial survey results suggested substantial avoidance of the operations 
by bowhead whales, observations by vessel-based observers indicate that 
at least some bowheads may have been closer to industrial activities 
than was suggested by results of aerial observations.
    Richardson et al. (2008) reported a slight change in the 
distribution of bowhead whale calls in response to operational sounds 
on BP's Northstar Island. The southern edge of the call distribution 
ranged from 0.47 to 1.46 mi (0.76 to 2.35 km) farther offshore, 
apparently in response to industrial sound levels. This result however, 
was only achieved after intensive statistical analyses, and it is not 
clear that this represented a biologically significant effect.
    Patenaude et al. (2002) reported fewer behavioral responses to 
aircraft overflights by bowhead compared to beluga whales. Behaviors 
classified as reactions consisted of short surfacings, immediate dives 
or turns, changes in behavior state, vigorous swimming, and breaching. 
Most bowhead reaction resulted from exposure to helicopter activity and 
little response to fixed-wing aircraft was observed. Most reactions 
occurred when the helicopter was at altitudes <=492 ft (150 m) and 
lateral distances <=820 ft (250 m; Nowacek et al., 2007).
    During their study, Patenaude et al. (2002) observed one bowhead 
whale cow-calf pair during four passes totaling 2.8 hours of the 
helicopter and two pairs during Twin Otter overflights. All of the 
helicopter passes were at altitudes of 49-98 ft (15-30 m). The mother 
dove both times she was at the surface, and the calf dove once out of 
the four times it was at the surface. For the cow-calf pair sightings 
during Twin Otter overflights, the authors did not note any behaviors 
specific to those pairs. Rather, the reactions of the cow-calf pairs 
were lumped with the reactions of other groups that did not consist of 
calves.
    Richardson et al. (1995b) and Moore and Clarke (2002) reviewed a 
few studies that observed responses of gray whales to aircraft. Cow-
calf pairs were quite sensitive to a turboprop survey flown at 1,000 ft 
(305 m) altitude on the Alaskan summering grounds. In that survey, 
adults were seen swimming over the calf, or the calf swam under the 
adult (Ljungblad et al., 1983, cited in Richardson et al., 1995b and 
Moore and Clarke, 2002). However, when the same aircraft circled for 
more than 10 minutes at 1,050 ft (320 m) altitude over a group of 
mating gray whales, no reactions were observed (Ljungblad et al., 1987, 
cited in Moore and Clarke, 2002). Malme et al. (1984, cited in 
Richardson et al., 1995b and Moore and Clarke, 2002) conducted playback 
experiments on migrating gray whales. They exposed the animals to 
underwater noise recorded from a Bell 212 helicopter (estimated 
altitude=328 ft [100 m]), at an average of three simulated passes per 
minute. The authors observed that whales changed their swimming course 
and sometimes slowed down in response to the playback sound but 
proceeded to migrate past the transducer. Migrating gray whales did not 
react overtly to a Bell 212 helicopter at greater than 1,394 ft (425 m) 
altitude, occasionally reacted when the helicopter was at 1,000-1,198 
ft (305-365 m), and usually reacted when it was below 825 ft (250 m; 
Southwest Research Associates, 1988, cited in Richardson et al., 1995b 
and Moore and Clarke, 2002). Reactions noted in that study included 
abrupt turns or dives or

[[Page 11735]]

both. Green et al. (1992, cited in Richardson et al., 1995b) observed 
that migrating gray whales rarely exhibited noticeable reactions to a 
straight-line overflight by a Twin Otter at 197 ft (60 m) altitude. 
Restrictions on aircraft altitude will be part of the proposed 
mitigation measures (described in the ``Proposed Mitigation'' section 
later in this document) during the proposed drilling activities, and 
overflights are likely to have little or no disturbance effects on 
baleen whales. Any disturbance that may occur would likely be temporary 
and localized.
    Southall et al. (2007, Appendix C) reviewed a number of papers 
describing the responses of marine mammals to non-pulsed sound, such as 
that produced during exploratory drilling operations. In general, 
little or no response was observed in animals exposed at received 
levels from 90-120 dB re 1 [micro]Pa (rms). Probability of avoidance 
and other behavioral effects increased when received levels were from 
120-160 dB re 1 [micro]Pa (rms). Some of the relevant reviews contained 
in Southall et al. (2007) are summarized next.
    Baker et al. (1982) reported some avoidance by humpback whales to 
vessel noise when received levels were 110-120 dB (rms) and clear 
avoidance at 120-140 dB (sound measurements were not provided by Baker 
but were based on measurements of identical vessels by Miles and Malme, 
1983).
    Malme et al. (1983, 1984) used playbacks of sounds from helicopter 
overflight and drilling rigs and platforms to study behavioral effects 
on migrating gray whales. Received levels exceeding 120 dB induced 
avoidance reactions. Malme et al. (1984) calculated 10%, 50%, and 90% 
probabilities of gray whale avoidance reactions at received levels of 
110, 120, and 130 dB, respectively. Malme et al. (1986) observed the 
behavior of feeding gray whales during four experimental playbacks of 
drilling sounds (50 to 315 Hz; 21-min overall duration and 10% duty 
cycle; source levels of 156-162 dB). In two cases for received levels 
of 100-110 dB, no behavioral reaction was observed. However, avoidance 
behavior was observed in two cases where received levels were 110-120 
dB.
    Richardson et al. (1990) performed 12 playback experiments in which 
bowhead whales in the Alaskan Arctic were exposed to drilling sounds. 
Whales generally did not respond to exposures in the 100 to 130 dB 
range, although there was some indication of minor behavioral changes 
in several instances.
    McCauley et al. (1996) reported several cases of humpback whales 
responding to vessels in Hervey Bay, Australia. Results indicated clear 
avoidance at received levels between 118 to 124 dB in three cases for 
which response and received levels were observed/measured.
    Palka and Hammond (2001) analyzed line transect census data in 
which the orientation and distance off transect line were reported for 
large numbers of minke whales. The authors developed a method to 
account for effects of animal movement in response to sighting 
platforms. Minor changes in locomotion speed, direction, and/or diving 
profile were reported at ranges from 1,847 to 2,352 ft (563 to 717 m) 
at received levels of 110 to 120 dB.
    Biassoni et al. (2000) and Miller et al. (2000) reported behavioral 
observations for humpback whales exposed to a low-frequency sonar 
stimulus (160- to 330-Hz frequency band; 42-s tonal signal repeated 
every 6 min; source levels 170 to 200 dB) during playback experiments. 
Exposure to measured received levels ranging from 120 to 150 dB 
resulted in variability in humpback singing behavior. Croll et al. 
(2001) investigated responses of foraging fin and blue whales to the 
same low frequency active sonar stimulus off southern California. 
Playbacks and control intervals with no transmission were used to 
investigate behavior and distribution on time scales of several weeks 
and spatial scales of tens of kilometers. The general conclusion was 
that whales remained feeding within a region for which 12 to 30 percent 
of exposures exceeded 140 dB.
    Frankel and Clark (1998) conducted playback experiments with 
wintering humpback whales using a single speaker producing a low-
frequency ``M-sequence'' (sine wave with multiple-phase reversals) 
signal in the 60 to 90 Hz band with output of 172 dB at 1 m. For 11 
playbacks, exposures were between 120 and 130 dB re 1 [micro]Pa (rms) 
and included sufficient information regarding individual responses. 
During eight of the trials, there were no measurable differences in 
tracks or bearings relative to control conditions, whereas on three 
occasions, whales either moved slightly away from (n = 1) or towards (n 
= 2) the playback speaker during exposure. The presence of the source 
vessel itself had a greater effect than did the M-sequence playback.
    Finally, Nowacek et al. (2004) used controlled exposures to 
demonstrate behavioral reactions of northern right whales to various 
non-pulse sounds. Playback stimuli included ship noise, social sounds 
of conspecifics, and a complex, 18-min ``alert'' sound consisting of 
repetitions of three different artificial signals. Ten whales were 
tagged with calibrated instruments that measured received sound 
characteristics and concurrent animal movements in three dimensions. 
Five out of six exposed whales reacted strongly to alert signals at 
measured received levels between 130 and 150 dB (i.e., ceased foraging 
and swam rapidly to the surface). Two of these individuals were not 
exposed to ship noise, and the other four were exposed to both stimuli. 
These whales reacted mildly to conspecific signals. Seven whales, 
including the four exposed to the alert stimulus, had no measurable 
response to either ship sounds or actual vessel noise.
    Toothed Whales--Most toothed whales have the greatest hearing 
sensitivity at frequencies much higher than that of baleen whales and 
may be less responsive to low-frequency sound commonly associated with 
oil and gas industry exploratory drilling activities. Richardson et al. 
(1995b) reported that beluga whales did not show any apparent reaction 
to playback of underwater drilling sounds at distances greater than 
656-1,312 ft (200-400 m). Reactions included slowing down, milling, or 
reversal of course after which the whales continued past the projector, 
sometimes within 164-328 ft (50-100 m). The authors concluded (based on 
a small sample size) that the playback of drilling sounds had no 
biologically significant effects on migration routes of beluga whales 
migrating through pack ice and along the seaward side of the nearshore 
lead east of Point Barrow in spring.
    At least six of 17 groups of beluga whales appeared to alter their 
migration path in response to underwater playbacks of icebreaker sound 
in the Arctic (Richardson et al., 1995b). Received levels from the 
icebreaker playback were estimated at 78-84 dB in the 1/3-octave band 
centered at 5,000 Hz, or 8-14 dB above ambient. If beluga whales 
reacted to an actual icebreaker at received levels of 80 dB, reactions 
would be expected to occur at distances on the order of 6.2 mi (10 km). 
Finley et al. (1990) also reported beluga avoidance of icebreaker 
activities in the Canadian High Arctic at distances of 22-31 mi (35-50 
km). In addition to avoidance, changes in dive behavior and pod 
integrity were also noted.
    Patenaude et al. (2002) reported that beluga whales appeared to be 
more responsive to aircraft overflights than bowhead whales. Changes 
were observed in diving and respiration behavior, and some whales 
veered away when a helicopter passed at <=820 ft (250 m) lateral 
distance at altitudes up to 492

[[Page 11736]]

ft (150 m). However, some belugas showed no reaction to the helicopter. 
Belugas appeared to show less response to fixed-wing aircraft than to 
helicopter overflights.
    In reviewing responses of cetaceans with best hearing in mid-
frequency ranges, which includes toothed whales, Southall et al. (2007) 
reported that combined field and laboratory data for mid-frequency 
cetaceans exposed to non-pulse sounds did not lead to a clear 
conclusion about received levels coincident with various behavioral 
responses. In some settings, individuals in the field showed profound 
(significant) behavioral responses to exposures from 90-120 dB, while 
others failed to exhibit such responses for exposure to received levels 
from 120-150 dB. Contextual variables other than exposure received 
level, and probable species differences, are the likely reasons for 
this variability. Context, including the fact that captive subjects 
were often directly reinforced with food for tolerating noise exposure, 
may also explain why there was great disparity in results from field 
and laboratory conditions--exposures in captive settings generally 
exceeded 170 dB before inducing behavioral responses. A summary of some 
of the relevant material reviewed by Southall et al. (2007) is next.
    LGL and Greeneridge (1986) and Finley et al. (1990) documented 
belugas and narwhals congregated near ice edges reacting to the 
approach and passage of icebreaking ships in the Arctic. Beluga whales 
responded to oncoming vessels by (1) fleeing at speeds of up to 12.4 
mi/hr (20 km/hr) from distances of 12.4-50 mi (20-80 km), (2) 
abandoning normal pod structure, and (3) modifying vocal behavior and/
or emitting alarm calls. Narwhals, in contrast, generally demonstrated 
a ``freeze'' response, lying motionless or swimming slowly away (as far 
as 23 mi [37 km] down the ice edge), huddling in groups, and ceasing 
sound production. There was some evidence of habituation and reduced 
avoidance 2 to 3 days after onset.
    The 1982 season observations by LGL and Greeneridge (1986) involved 
a single passage of an icebreaker with both ice-based and aerial 
measurements on June 28, 1982. Four groups of narwhals (n = 9 to 10, 7, 
7, and 6) responded when the ship was 4 mi (6.4 km) away (received 
levels of approximately 100 dB in the 150- to 1,150-Hz band). At a 
later point, observers sighted belugas moving away from the source at 
more than 12.4 mi (20 km; received levels of approximately 90 dB in the 
150- to 1,150-Hz band). The total number of animals observed fleeing 
was about 300, suggesting approximately 100 independent groups (of 
three individuals each). No whales were sighted the following day, but 
some were sighted on June 30, with ship noise audible at spectrum 
levels of approximately 55 dB/Hz (up to 4 kHz).
    Observations during 1983 (LGL and Greeneridge, 1986) involved two 
icebreaking ships with aerial survey and ice-based observations during 
seven sampling periods. Narwhals and belugas generally reacted at 
received levels ranging from 101 to 121 dB in the 20- to 1,000-Hz band 
and at a distance of up to 40.4 mi (65 km). Large numbers (100s) of 
beluga whales moved out of the area at higher received levels. As noise 
levels from icebreaking operations diminished, a total of 45 narwhals 
returned to the area and engaged in diving and foraging behavior. 
During the final sampling period, following an 8-h quiet interval, no 
reactions were seen from 28 narwhals and 17 belugas (at received levels 
ranging up to 115 dB).
    The final season (1984) reported in LGL and Greeneridge (1986) 
involved aerial surveys before, during, and after the passage of two 
icebreaking ships. During operations, no belugas and few narwhals were 
observed in an area approximately 16.8 mi (27 km) ahead of the vessels, 
and all whales sighted over 12.4-50 mi (20-80 km) from the ships were 
swimming strongly away. Additional observations confirmed the spatial 
extent of avoidance reactions to this sound source in this context.
    Buckstaff (2004) reported elevated dolphin whistle rates with 
received levels from oncoming vessels in the 110 to 120 dB range in 
Sarasota Bay, Florida. These hearing thresholds were apparently lower 
than those reported by a researcher listening with towed hydrophones. 
Morisaka et al. (2005) compared whistles from three populations of 
Indo-Pacific bottlenose dolphins. One population was exposed to vessel 
noise with spectrum levels of approximately 85 dB/Hz in the 1- to 22-
kHz band (broadband received levels approximately 128 dB) as opposed to 
approximately 65 dB/Hz in the same band (broadband received levels 
approximately 108 dB) for the other two sites. Dolphin whistles in the 
noisier environment had lower fundamental frequencies and less 
frequency modulation, suggesting a shift in sound parameters as a 
result of increased ambient noise.
    Morton and Symonds (2002) used census data on killer whales in 
British Columbia to evaluate avoidance of non-pulse acoustic harassment 
devices (AHDs). Avoidance ranges were about 2.5 mi (4 km). Also, there 
was a dramatic reduction in the number of days ``resident'' killer 
whales were sighted during AHD-active periods compared to pre- and 
post-exposure periods and a nearby control site.
    Monteiro-Neto et al. (2004) studied avoidance responses of tucuxi 
(Sotalia fluviatilis) to Dukane[supreg] Netmark acoustic deterrent 
devices. In a total of 30 exposure trials, approximately five groups 
each demonstrated significant avoidance compared to 20 pinger off and 
55 no-pinger control trials over two quadrats of about 0.19 mi\2\ (0.5 
km\2\). Estimated exposure received levels were approximately 115 dB.
    Awbrey and Stewart (1983) played back semi-submersible drillship 
sounds (source level: 163 dB) to belugas in Alaska. They reported 
avoidance reactions at 984 and 4,921 ft (300 and 1,500 m) and approach 
by groups at a distance of 2.2 mi (3.5 km; received levels were 
approximately 110 to 145 dB over these ranges assuming a 15 log R 
transmission loss). Similarly, Richardson et al. (1990) played back 
drilling platform sounds (source level: 163 dB) to belugas in Alaska. 
They conducted aerial observations of eight individuals among 
approximately 100 spread over an area several hundred meters to several 
kilometers from the sound source and found no obvious reactions. 
Moderate changes in movement were noted for three groups swimming 
within 656 ft (200 m) of the sound projector.
    Two studies deal with issues related to changes in marine mammal 
vocal behavior as a function of variable background noise levels. Foote 
et al. (2004) found increases in the duration of killer whale calls 
over the period 1977 to 2003, during which time vessel traffic in Puget 
Sound, and particularly whale-watching boats around the animals, 
increased dramatically. Scheifele et al. (2005) demonstrated that 
belugas in the St. Lawrence River increased the levels of their 
vocalizations as a function of the background noise level (the 
``Lombard Effect'').
    Several researchers conducting laboratory experiments on hearing 
and the effects of non-pulse sounds on hearing in mid-frequency 
cetaceans have reported concurrent behavioral responses. Nachtigall et 
al. (2003) reported that noise exposures up to 179 dB and 55-min 
duration affected the trained behaviors of a bottlenose dolphin 
participating in a TTS experiment. Finneran and Schlundt (2004) 
provided a detailed, comprehensive analysis of the behavioral responses 
of belugas and

[[Page 11737]]

bottlenose dolphins to 1-s tones (received levels 160 to 202 dB) in the 
context of TTS experiments. Romano et al. (2004) investigated the 
physiological responses of a bottlenose dolphin and a beluga exposed to 
these tonal exposures and demonstrated a decrease in blood cortisol 
levels during a series of exposures between 130 and 201 dB. 
Collectively, the laboratory observations suggested the onset of a 
behavioral response at higher received levels than did field studies. 
The differences were likely related to the very different conditions 
and contextual variables between untrained, free-ranging individuals 
vs. laboratory subjects that were rewarded with food for tolerating 
noise exposure.
    Pinnipeds--Pinnipeds generally seem to be less responsive to 
exposure to industrial sound than most cetaceans. Pinniped responses to 
underwater sound from some types of industrial activities such as 
seismic exploration appear to be temporary and localized (Harris et 
al., 2001; Reiser et al., 2009).
    Blackwell et al. (2004) reported little or no reaction of ringed 
seals in response to pile-driving activities during construction of a 
man-made island in the Beaufort Sea. Ringed seals were observed 
swimming as close as 151 ft (46 m) from the island and may have been 
habituated to the sounds which were likely audible at distances <9,842 
ft (3,000 m) underwater and 0.3 mi (0.5 km) in air. Moulton et al. 
(2003) reported that ringed seal densities on ice in the vicinity of a 
man-made island in the Beaufort Sea did not change significantly before 
and after construction and drilling activities.
    Southall et al. (2007) reviewed literature describing responses of 
pinnipeds to non-pulsed sound and reported that the limited data 
suggest exposures between approximately 90 and 140 dB generally do not 
appear to induce strong behavioral responses in pinnipeds exposed to 
non-pulse sounds in water; no data exist regarding exposures at higher 
levels. It is important to note that among these studies, there are 
some apparent differences in responses between field and laboratory 
conditions. In contrast to the mid-frequency odontocetes, captive 
pinnipeds responded more strongly at lower levels than did animals in 
the field. Again, contextual issues are the likely cause of this 
difference.
    Jacobs and Terhune (2002) observed harbor seal reactions to AHDs 
(source level in this study was 172 dB) deployed around aquaculture 
sites. Seals were generally unresponsive to sounds from the AHDs. 
During two specific events, individuals came within 141 and 144 ft (43 
and 44 m) of active AHDs and failed to demonstrate any measurable 
behavioral response; estimated received levels based on the measures 
given were approximately 120 to 130 dB.
    Costa et al. (2003) measured received noise levels from an Acoustic 
Thermometry of Ocean Climate (ATOC) program sound source off northern 
California using acoustic data loggers placed on translocated elephant 
seals. Subjects were captured on land, transported to sea, instrumented 
with archival acoustic tags, and released such that their transit would 
lead them near an active ATOC source (at 939-m depth; 75-Hz signal with 
37.5- Hz bandwidth; 195 dB maximum source level, ramped up from 165 dB 
over 20 min) on their return to a haul-out site. Received exposure 
levels of the ATOC source for experimental subjects averaged 128 dB 
(range 118 to 137) in the 60- to 90-Hz band. None of the instrumented 
animals terminated dives or radically altered behavior upon exposure, 
but some statistically significant changes in diving parameters were 
documented in nine individuals. Translocated northern elephant seals 
exposed to this particular non-pulse source began to demonstrate subtle 
behavioral changes at exposure to received levels of approximately 120 
to 140 dB.
    Kastelein et al. (2006) exposed nine captive harbor seals in an 
approximately 82 x 98 ft (25 x 30 m) enclosure to non-pulse sounds used 
in underwater data communication systems (similar to acoustic modems). 
Test signals were frequency modulated tones, sweeps, and bands of noise 
with fundamental frequencies between 8 and 16 kHz; 128 to 130 [<plus-
minus> 3] dB source levels; 1- to 2-s duration [60-80 percent duty 
cycle]; or 100 percent duty cycle. They recorded seal positions and the 
mean number of individual surfacing behaviors during control periods 
(no exposure), before exposure, and in 15-min experimental sessions (n 
= 7 exposures for each sound type). Seals generally swam away from each 
source at received levels of approximately 107 dB, avoiding it by 
approximately 16 ft (5 m), although they did not haul out of the water 
or change surfacing behavior. Seal reactions did not appear to wane 
over repeated exposure (i.e., there was no obvious habituation), and 
the colony of seals generally returned to baseline conditions following 
exposure. The seals were not reinforced with food for remaining in the 
sound field.
    Potential effects to pinnipeds from aircraft activity could involve 
both acoustic and non-acoustic effects. It is uncertain if the seals 
react to the sound of the helicopter or to its physical presence flying 
overhead. Typical reactions of hauled out pinnipeds to aircraft that 
have been observed include looking up at the aircraft, moving on the 
ice or land, entering a breathing hole or crack in the ice, or entering 
the water. Ice seals hauled out on the ice have been observed diving 
into the water when approached by a low-flying aircraft or helicopter 
(Burns and Harbo, 1972, cited in Richardson et al., 1995a; Burns and 
Frost, 1979, cited in Richardson et al., 1995a). Richardson et al. 
(1995a) note that responses can vary based on differences in aircraft 
type, altitude, and flight pattern. Additionally, a study conducted by 
Born et al. (1999) found that wind chill was also a factor in level of 
response of ringed seals hauled out on ice, as well as time of day and 
relative wind direction.
    Blackwell et al. (2004a) observed 12 ringed seals during low-
altitude overflights of a Bell 212 helicopter at Northstar in June and 
July 2000 (9 observations took place concurrent with pipe-driving 
activities). One seal showed no reaction to the aircraft while the 
remaining 11 (92%) reacted either by looking at the helicopter (n=10) 
or by departing from their basking site (n=1). Blackwell et al. (2004a) 
concluded that none of the reactions to helicopters were strong or long 
lasting, and that seals near Northstar in June and July 2000 probably 
had habituated to industrial sounds and visible activities that had 
occurred often during the preceding winter and spring. There have been 
few systematic studies of pinniped reactions to aircraft overflights, 
and most of the available data concern pinnipeds hauled out on land or 
ice rather than pinnipeds in the water (Richardson et al., 1995a; Born 
et al., 1999).
    Born et al. (1999) determined that 49 percent of ringed seals 
escaped (i.e., left the ice) as a response to a helicopter flying at 
492 ft (150 m) altitude. Seals entered the water when the helicopter 
was 4,101 ft (1,250 m) away if the seal was in front of the helicopter 
and at 1,640 ft (500 m) away if the seal was to the side of the 
helicopter. The authors noted that more seals reacted to helicopters 
than to fixed-wing aircraft. The study concluded that the risk of 
scaring ringed seals by small-type helicopters could be substantially 
reduced if they do not approach closer than 4,921 ft (1,500 m).
    Spotted seals hauled out on land in summer are unusually sensitive 
to aircraft overflights compared to other species. They often rush into 
the water when an aircraft flies by at altitudes up to 984-2,461 ft 
(300-750 m). They

[[Page 11738]]

occasionally react to aircraft flying as high as 4,495 ft (1,370 m) and 
at lateral distances as far as 1.2 mi (2 km) or more (Frost and Lowry, 
1990; Rugh et al., 1997).
(4) Hearing Impairment and Other Physiological Effects
    Temporary or permanent hearing impairment is a possibility when 
marine mammals are exposed to very strong sounds. Non-auditory 
physiological effects might also occur in marine mammals exposed to 
strong underwater sound. Possible types of non-auditory physiological 
effects or injuries that theoretically might occur in mammals close to 
a strong sound source include stress, neurological effects, bubble 
formation, and other types of organ or tissue damage. It is possible 
that some marine mammal species (i.e., beaked whales) may be especially 
susceptible to injury and/or stranding when exposed to strong pulsed 
sounds. However, as discussed later in this document, there is no 
definitive evidence that any of these effects occur even for marine 
mammals in close proximity to industrial sound sources, and beaked 
whales do not occur in the proposed activity area. Additional 
information regarding the possibilities of TTS, permanent threshold 
shift (PTS), and non-auditory physiological effects, such as stress, is 
discussed for both exploratory drilling activities and ZVSP surveys in 
the following section (``Potential Effects from Zero-Offset Vertical 
Seismic Profile Activities'').

Potential Effects From Zero-Offset Vertical Seismic Profile Activities

(1) Tolerance
    Numerous studies have shown that pulsed sounds from airguns are 
often readily detectable in the water at distances of many kilometers. 
Weir (2008) observed marine mammal responses to seismic pulses from a 
24 airgun array firing a total volume of either 5,085 in\3\ or 3,147 
in\3\ in Angolan waters between August 2004 and May 2005. Weir recorded 
a total of 207 sightings of humpback whales (n = 66), sperm whales (n = 
124), and Atlantic spotted dolphins (n = 17) and reported that there 
were no significant differences in encounter rates (sightings/hr) for 
humpback and sperm whales according to the airgun array's operational 
status (i.e., active versus silent). For additional information on 
tolerance of marine mammals to anthropogenic sound, see the previous 
subsection in this document (``Potential Effects from Exploratory 
Drilling Activities'').
(2) Masking
    As stated earlier in this document, masking is the obscuring of 
sounds of interest by other sounds, often at similar frequencies. For 
full details about masking, see the previous subsection in this 
document (``Potential Effects from Exploratory Drilling Activities''). 
Some additional information regarding pulsed sounds is provided here.
    There is evidence of some marine mammal species continuing to call 
in the presence of industrial activity. McDonald et al. (1995) heard 
blue and fin whale calls between seismic pulses in the Pacific. 
Although there has been one report that sperm whales cease calling when 
exposed to pulses from a very distant seismic ship (Bowles et al., 
1994), a more recent study reported that sperm whales off northern 
Norway continued calling in the presence of seismic pulses (Madsen et 
al., 2002). Similar results were also reported during work in the Gulf 
of Mexico (Tyack et al., 2003). Bowhead whale calls are frequently 
detected in the presence of seismic pulses, although the numbers of 
calls detected may sometimes be reduced (Richardson et al., 1986; 
Greene et al., 1999; Blackwell et al., 2009a). Bowhead whales in the 
Beaufort Sea may decrease their call rates in response to seismic 
operations, although movement out of the area might also have 
contributed to the lower call detection rate (Blackwell et al., 
2009a,b). Additionally, there is increasing evidence that, at times, 
there is enough reverberation between airgun pulses such that detection 
range of calls may be significantly reduced. In contrast, Di Iorio and 
Clark (2009) found evidence of increased calling by blue whales during 
operations by a lower-energy seismic source, a sparker.
    There is little concern regarding masking due to the brief duration 
of these pulses and relatively longer silence between airgun shots (9-
12 seconds) near the sound source. However, at long distances (over 
tens of kilometers away) in deep water, due to multipath propagation 
and reverberation, the durations of airgun pulses can be ``stretched'' 
to seconds with long decays (Madsen et al., 2006; Clark and Gagnon, 
2006). Therefore it could affect communication signals used by low 
frequency mysticetes when they occur near the noise band and thus 
reduce the communication space of animals (e.g., Clark et al., 2009a,b) 
and cause increased stress levels (e.g., Foote et al., 2004; Holt et 
al., 2009). Nevertheless, the intensity of the noise is also greatly 
reduced at long distances. Therefore, masking effects are anticipated 
to be limited, especially in the case of odontocetes, given that they 
typically communicate at frequencies higher than those of the airguns.
(3) Behavioral Disturbance Reactions
    As was described in more detail in the previous sub-section 
(``Potential Effects of Exploratory Drilling Activities''), behavioral 
responses to sound are highly variable and context-specific. Summaries 
of observed reactions and studies related to seismic airgun activity 
are provided next.
    Baleen Whales--Baleen whale responses to pulsed sound (e.g., 
seismic airguns) have been studied more thoroughly than responses to 
continuous sound (e.g., drillships). Baleen whales generally tend to 
avoid operating airguns, but avoidance radii are quite variable. Whales 
are often reported to show no overt reactions to pulses from large 
arrays of airguns at distances beyond a few kilometers, even though the 
airgun pulses remain well above ambient noise levels out to much 
greater distances (Miller et al., 2005). However, baleen whales exposed 
to strong noise pulses often react by deviating from their normal 
migration route (Richardson et al., 1999). Migrating gray and bowhead 
whales were observed avoiding the sound source by displacing their 
migration route to varying degrees but within the natural boundaries of 
the migration corridors (Schick and Urban, 2000; Richardson et al., 
1999; Malme et al., 1983). Baleen whale responses to pulsed sound 
however may depend on the type of activity in which the whales are 
engaged. Some evidence suggests that feeding bowhead whales may be more 
tolerant of underwater sound than migrating bowheads (Miller et al., 
2005; Lyons et al., 2009; Christie et al., 2010).
    Results of studies of gray, bowhead, and humpback whales have 
determined that received levels of pulses in the 160-170 dB re 1 
[micro]Pa rms range seem to cause obvious avoidance behavior in a 
substantial fraction of the animals exposed. In many areas, seismic 
pulses from large arrays of airguns diminish to those levels at 
distances ranging from 2.8-9 mi (4.5-14.5 km) from the source. For the 
much smaller airgun array used during the ZVSP survey (total discharge 
volume of 760 in\3\), distances to received levels in the 170-160 dB re 
1 [micro]Pa rms range are estimated to be 1.44-2.28 mi (2.31-3.67 km). 
Baleen whales within those distances may show avoidance or other strong 
disturbance reactions to the airgun array. Subtle behavioral changes 
sometimes become evident at somewhat lower received levels, and recent 
studies have shown

[[Page 11739]]

that some species of baleen whales, notably bowhead and humpback 
whales, at times show strong avoidance at received levels lower than 
160-170 dB re 1 [mu]Pa rms. Bowhead whales migrating west across the 
Alaskan Beaufort Sea in autumn, in particular, are unusually 
responsive, with avoidance occurring out to distances of 12.4-18.6 mi 
(20-30 km) from a medium-sized airgun source (Miller et al., 1999; 
Richardson et al., 1999). However, more recent research on bowhead 
whales (Miller et al., 2005) corroborates earlier evidence that, during 
the summer feeding season, bowheads are not as sensitive to seismic 
sources. In summer, bowheads typically begin to show avoidance 
reactions at a received level of about 160-170 dB re 1 [micro]Pa rms 
(Richardson et al., 1986; Ljungblad et al., 1988; Miller et al., 2005).
    Malme et al. (1986, 1988) studied the responses of feeding eastern 
gray whales to pulses from a single 100 in\3\ airgun off St. Lawrence 
Island in the northern Bering Sea. They estimated, based on small 
sample sizes, that 50% of feeding gray whales ceased feeding at an 
average received pressure level of 173 dB re 1 [micro]Pa on an 
(approximate) rms basis, and that 10% of feeding whales interrupted 
feeding at received levels of 163 dB. Those findings were generally 
consistent with the results of experiments conducted on larger numbers 
of gray whales that were migrating along the California coast and on 
observations of the distribution of feeding Western Pacific gray whales 
off Sakhalin Island, Russia, during a seismic survey (Yazvenko et al., 
2007).
    Data on short-term reactions (or lack of reactions) of cetaceans to 
impulsive noises do not necessarily provide information about long-term 
effects. While it is not certain whether impulsive noises affect 
reproductive rate or distribution and habitat use in subsequent days or 
years, certain species have continued to use areas ensonified by 
airguns and have continued to increase in number despite successive 
years of anthropogenic activity in the area. Gray whales continued to 
migrate annually along the west coast of North America despite 
intermittent seismic exploration and much ship traffic in that area for 
decades (Appendix A in Malme et al., 1984). Bowhead whales continued to 
travel to the eastern Beaufort Sea each summer despite seismic 
exploration in their summer and autumn range for many years (Richardson 
et al., 1987). Populations of both gray whales and bowhead whales grew 
substantially during this time. Bowhead whales have increased by 
approximately 3.4% per year for the last 10 years in the Beaufort Sea 
(Allen and Angliss, 2011). In any event, the brief exposures to sound 
pulses from the proposed airgun source (the airguns will only be fired 
for a period of 10-14 hours for each of the three, possibly four, 
wells) are highly unlikely to result in prolonged effects.
    Toothed Whales--Few systematic data are available describing 
reactions of toothed whales to noise pulses. Few studies similar to the 
more extensive baleen whale/seismic pulse work summarized earlier in 
this document have been reported for toothed whales. However, 
systematic work on sperm whales is underway (Tyack et al., 2003), and 
there is an increasing amount of information about responses of various 
odontocetes to seismic surveys based on monitoring studies (e.g., 
Stone, 2003; Smultea et al., 2004; Moulton and Miller, 2005).
    Seismic operators and marine mammal observers sometimes see 
dolphins and other small toothed whales near operating airgun arrays, 
but, in general, there seems to be a tendency for most delphinids to 
show some limited avoidance of seismic vessels operating large airgun 
systems. However, some dolphins seem to be attracted to the seismic 
vessel and floats, and some ride the bow wave of the seismic vessel 
even when large arrays of airguns are firing. Nonetheless, there have 
been indications that small toothed whales sometimes move away or 
maintain a somewhat greater distance from the vessel when a large array 
of airguns is operating than when it is silent (e.g., Goold, 1996a,b,c; 
Calambokidis and Osmek, 1998; Stone, 2003). The beluga may be a species 
that (at least at times) shows long-distance avoidance of seismic 
vessels. Aerial surveys during seismic operations in the southeastern 
Beaufort Sea recorded much lower sighting rates of beluga whales within 
6.2-12.4 mi (10-20 km) of an active seismic vessel. These results were 
consistent with the low number of beluga sightings reported by 
observers aboard the seismic vessel, suggesting that some belugas might 
be avoiding the seismic operations at distances of 6.2-12.4 mi (10-20 
km) (Miller et al., 2005).
    Captive bottlenose dolphins and (of more relevance in this project) 
beluga whales exhibit changes in behavior when exposed to strong pulsed 
sounds similar in duration to those typically used in seismic surveys 
(Finneran et al., 2002, 2005). However, the animals tolerated high 
received levels of sound (pk-pk level >200 dB re 1 [mu]Pa) before 
exhibiting aversive behaviors.
    Reactions of toothed whales to large arrays of airguns are variable 
and, at least for delphinids, seem to be confined to a smaller radius 
than has been observed for mysticetes. However, based on the limited 
existing evidence, belugas should not be grouped with delphinids in the 
``less responsive'' category.
    Pinnipeds--Pinnipeds are not likely to show a strong avoidance 
reaction to the airgun sources proposed for use. Visual monitoring from 
seismic vessels has shown only slight (if any) avoidance of airguns by 
pinnipeds and only slight (if any) changes in behavior. Ringed seals 
frequently do not avoid the area within a few hundred meters of 
operating airgun arrays (Harris et al., 2001; Moulton and Lawson, 2002; 
Miller et al., 2005). Monitoring work in the Alaskan Beaufort Sea 
during 1996-2001 provided considerable information regarding the 
behavior of seals exposed to seismic pulses (Harris et al., 2001; 
Moulton and Lawson, 2002). These seismic projects usually involved 
arrays of 6 to 16 airguns with total volumes of 560 to 1,500 in\3\. The 
combined results suggest that some seals avoid the immediate area 
around seismic vessels. In most survey years, ringed seal sightings 
tended to be farther away from the seismic vessel when the airguns were 
operating than when they were not (Moulton and Lawson, 2002). However, 
these avoidance movements were relatively small, on the order of 328 ft 
(100 m) to a few hundreds of meters, and many seals remained within 
328-656 ft (100-200 m) of the trackline as the operating airgun array 
passed by. Seal sighting rates at the water surface were lower during 
airgun array operations than during no-airgun periods in each survey 
year except 1997. Similarly, seals are often very tolerant of pulsed 
sounds from seal-scaring devices (Mate and Harvey, 1987; Jefferson and 
Curry, 1994; Richardson et al., 1995a). However, initial telemetry work 
suggests that avoidance and other behavioral reactions by two other 
species of seals to small airgun sources may at times be stronger than 
evident to date from visual studies of pinniped reactions to airguns 
(Thompson et al., 1998). Even if reactions of the species occurring in 
the present study area are as strong as those evident in the telemetry 
study, reactions are expected to be confined to relatively small 
distances and durations, with no long-term effects on pinniped 
individuals or populations. Additionally, the airguns are only proposed 
to be used for a short time during the exploration drilling program 
(approximately 10-14 hours for

[[Page 11740]]

each well, for a total of 40-56 hours, and more likely to be 30-42 
hours if the fourth well is not completed, over the entire open-water 
season, which lasts for approximately 4 months).
(4) Hearing Impairment and Other Physiological Effects
    TTS--TTS is the mildest form of hearing impairment that can occur 
during exposure to a strong sound (Kryter, 1985). While experiencing 
TTS, the hearing threshold rises, and a sound must be stronger in order 
to be heard. At least in terrestrial mammals, TTS can last from minutes 
or hours to (in cases of strong TTS) days, can be limited to a 
particular frequency range, and can be in varying degrees (i.e., a loss 
of a certain number of dBs of sensitivity). For sound exposures at or 
somewhat above the TTS threshold, hearing sensitivity in both 
terrestrial and marine mammals recovers rapidly after exposure to the 
noise ends. Few data on sound levels and durations necessary to elicit 
mild TTS have been obtained for marine mammals, and none of the 
published data concern TTS elicited by exposure to multiple pulses of 
sound.
    Marine mammal hearing plays a critical role in communication with 
conspecifics and in 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 takes place during a time when the animal is traveling 
through the open ocean, where ambient noise is lower and there are not 
as many competing sounds present. Alternatively, a larger amount and 
longer duration of TTS sustained during a time when communication is 
critical for successful mother/calf interactions could have more 
serious impacts if it were in the same frequency band as the necessary 
vocalizations and of a severity that it impeded communication. The fact 
that animals exposed to levels and durations of sound that would be 
expected to result in this physiological response would also be 
expected to have behavioral responses of a comparatively more severe or 
sustained nature is also notable and potentially of more importance 
than the simple existence of a TTS.
    Researchers have derived TTS information for odontocetes from 
studies on the bottlenose dolphin and beluga. For the one harbor 
porpoise tested, the received level of airgun sound that elicited onset 
of TTS was lower (Lucke et al., 2009). If these results from a single 
animal are representative, it is inappropriate to assume that onset of 
TTS occurs at similar received levels in all odontocetes (cf. Southall 
et al., 2007). Some cetaceans apparently can incur TTS at considerably 
lower sound exposures than are necessary to elicit TTS in the beluga or 
bottlenose dolphin.
    For baleen whales, there are no data, direct or indirect, on levels 
or properties of sound that are required to induce TTS. The frequencies 
to which baleen whales are most sensitive are assumed to be lower than 
those to which odontocetes are most sensitive, and natural background 
noise levels at those low frequencies tend to be higher. As a result, 
auditory thresholds of baleen whales within their frequency band of 
best hearing are believed to be higher (less sensitive) than are those 
of odontocetes at their best frequencies (Clark and Ellison, 2004), 
meaning that baleen whales require sounds to be louder (i.e., higher dB 
levels) than odontocetes in the frequency ranges at which each group 
hears the best. From this, it is suspected that received levels causing 
TTS onset may also be higher in baleen whales (Southall et al., 2007). 
Since current NMFS practice assumes the same thresholds for the onset 
of hearing impairment in both odontocetes and mysticetes, NMFS' onset 
of TTS threshold is likely conservative for mysticetes. For this 
proposed activity, Shell expects no cases of TTS given the strong 
likelihood that baleen whales would avoid the airguns before being 
exposed to levels high enough for TTS to occur. The source levels of 
the drilling units are far lower than those of the airguns.
    In pinnipeds, TTS thresholds associated with exposure to brief 
pulses (single or multiple) of underwater sound have not been measured. 
However, systematic TTS studies on captive pinnipeds have been 
conducted (Bowles et al., 1999; Kastak et al., 1999, 2005, 2007; 
Schusterman et al., 2000; Finneran et al., 2003; Southall et al., 
2007). Initial evidence from more prolonged (non-pulse) exposures 
suggested that some pinnipeds (harbor seals in particular) incur TTS at 
somewhat lower received levels than do small odontocetes exposed for 
similar durations (Kastak et al., 1999, 2005; Ketten et al., 2001; cf. 
Au et al., 2000). The TTS threshold for pulsed sounds has been 
indirectly estimated as being a sound exposure level (SEL) of 
approximately 171 dB re 1 [mu]Pa\2\[middot]s (Southall et al., 2007) 
which would be equivalent to a single pulse with a received level of 
approximately 181 to 186 dB re 1 [mu]Pa (rms), or a series of pulses 
for which the highest rms values are a few dB lower. Corresponding 
values for California sea lions and northern elephant seals are likely 
to be higher (Kastak et al., 2005). For harbor seal, which is closely 
related to the ringed seal, TTS onset apparently occurs at somewhat 
lower received energy levels than for odonotocetes. The sound level 
necessary to cause TTS in pinnipeds depends on exposure duration, as in 
other mammals; with longer exposure, the level necessary to elicit TTS 
is reduced (Schusterman et al., 2000; Kastak et al., 2005, 2007). For 
very short exposures (e.g., to a single sound pulse), the level 
necessary to cause TTS is very high (Finneran et al., 2003). For 
pinnipeds exposed to in-air sounds, auditory fatigue has been measured 
in response to single pulses and to non-pulse noise (Southall et al., 
2007), although high exposure levels were required to induce TTS-onset 
(SEL: 129 dB re: 20 [mu]Pa\2.\s; Bowles et al., unpub. data).
    NMFS has established acoustic thresholds that identify the received 
sound levels above which hearing impairment or other injury could 
potentially occur, which are 180 and 190 dB re 1 [mu]Pa (rms) for 
cetaceans and pinnipeds, respectively (NMFS 1995, 2000). The 
established 180- and 190-dB criteria were established before additional 
TTS measurements for marine mammals became available, and represent the 
received levels above which one could not be certain there would be no 
injurious effects, auditory or otherwise, to marine mammals. TTS is 
considered by NMFS to be a type of Level B (non-injurious) harassment. 
The 180- and 190-dB levels are also typically used as shutdown criteria 
for mitigation applicable to cetaceans and pinnipeds, respectively, as 
specified by NMFS (2000) and are used to establish exclusion zones 
(EZs), as appropriate. Additionally, based on the summary provided here 
and the fact that modeling indicates the back-propagated source level 
for the Discoverer to be between 177 and 185 dB re 1 [mu]Pa at 1 m 
(Austin and Warner, 2010), TTS is not expected to occur in any marine 
mammal species that may occur in the proposed drilling area since the 
source level will not reach levels thought to induce even mild TTS. 
While the source level of the airgun is higher than the 190-dB 
threshold level, an animal would have to be in very close

[[Page 11741]]

proximity to be exposed to such levels. Additionally, the 180- and 190-
dB radii for the airgun are 0.8 mi (1.24 km) and 0.3 mi (524 m), 
respectively, from the source. Because of the short duration that the 
airguns will be used (no more than 30-56 hours throughout the entire 
open-water season) and mitigation and monitoring measures described 
later in this document, hearing impairment is not anticipated.
    PTS--When PTS occurs, there is physical damage to the sound 
receptors in the ear. In some cases, there can be total or partial 
deafness, whereas in other cases, the animal has an impaired ability to 
hear sounds in specific frequency ranges (Kryter, 1985).
    There is no specific evidence that exposure to underwater 
industrial sound associated with oil exploration can cause PTS in any 
marine mammal (see Southall et al., 2007). However, given the 
possibility that mammals might incur TTS, there has been further 
speculation about the possibility that some individuals occurring very 
close to such activities might incur PTS (e.g., Richardson et al., 
1995, p. 372ff; Gedamke et al., 2008). Single or occasional occurrences 
of mild TTS are not indicative of permanent auditory damage in 
terrestrial mammals. Relationships between TTS and PTS thresholds have 
not been studied in marine mammals but are assumed to be similar to 
those in humans and other terrestrial mammals (Southall et al., 2007; 
Le Prell, in press). PTS might occur at a received sound level at least 
several decibels above that inducing mild TTS. Based on data from 
terrestrial mammals, a precautionary assumption is that the PTS 
threshold for impulse sounds (such as airgun pulses as received close 
to the source) is at least 6 dB higher than the TTS threshold on a 
peak-pressure basis and probably greater than 6 dB (Southall et al., 
2007).
    It is highly unlikely that marine mammals could receive sounds 
strong enough (and over a sufficient duration) to cause PTS during the 
proposed exploratory drilling program. As mentioned previously in this 
document, the source levels of the drilling units are not considered 
strong enough to cause even slight TTS. Given the higher level of sound 
necessary to cause PTS, it is even less likely that PTS could occur. In 
fact, based on the modeled source levels for the drilling units, the 
levels immediately adjacent to the drilling units may not be sufficient 
to induce PTS, even if the animals remain in the immediate vicinity of 
the activity. The modeled source level from the Discoverer suggests 
that marine mammals located immediately adjacent to a drilling unit 
would likely not be exposed to received sound levels of a magnitude 
strong enough to induce PTS, even if the animals remain in the 
immediate vicinity of the proposed activity location for a prolonged 
period of time. Because the source levels do not reach the threshold of 
190 dB currently used for pinnipeds and is at the 180 dB threshold 
currently used for cetaceans, it is highly unlikely that any type of 
hearing impairment, temporary or permanent, would occur as a result of 
the exploration drilling activities. Additionally, Southall et al. 
(2007) proposed that the thresholds for injury of marine mammals 
exposed to ``discrete'' noise events (either single or multiple 
exposures over a 24-hr period) are higher than the 180- and 190-dB re 1 
[mu]Pa (rms) in-water threshold currently used by NMFS.
    Non-auditory Physiological Effects--Non-auditory physiological 
effects or injuries that theoretically might occur in marine mammals 
exposed to strong underwater sound include stress, neurological 
effects, bubble formation, and other types of organ or tissue damage 
(Cox et al., 2006; Southall et al., 2007). Studies examining any such 
effects are limited. If any such effects do occur, they probably would 
be limited to unusual situations when animals might be exposed at close 
range for unusually long periods. It is doubtful that any single marine 
mammal would be exposed to strong sounds for sufficiently long that 
significant physiological stress would develop.
    Classic stress responses begin when an animal's central nervous 
system perceives a potential threat to its homeostasis. That perception 
triggers stress responses regardless of whether a stimulus actually 
threatens the animal; the mere perception of a threat is sufficient to 
trigger a stress response (Moberg, 2000; Sapolsky et al., 2005; Seyle, 
1950). Once an animal's central nervous system perceives a threat, it 
mounts a biological response or defense that consists of a combination 
of the four general biological defense responses: behavioral responses; 
autonomic nervous system responses; neuroendocrine responses; or immune 
responses.
    In the case of many stressors, an animal's first and most 
economical (in terms of biotic costs) response is behavioral avoidance 
of the potential stressor or avoidance of continued exposure to a 
stressor. An animal's second line of defense to stressors involves the 
sympathetic part of the autonomic nervous system and the classical 
``fight or flight'' response, which includes the cardiovascular system, 
the gastrointestinal system, the exocrine glands, and the adrenal 
medulla to produce changes in heart rate, blood pressure, and 
gastrointestinal activity that humans commonly associate with 
``stress.'' These responses have a relatively short duration and may or 
may not have significant long-term effects on an animal's welfare.
    An animal's third line of defense to stressors involves its 
neuroendocrine or sympathetic nervous systems; the system that has 
received the most study has been the hypothalmus-pituitary-adrenal 
system (also known as the HPA axis in mammals or the hypothalamus-
pituitary-interrenal axis in fish and some reptiles). Unlike stress 
responses associated with the autonomic nervous 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 (Moberg, 
1987; Rivier, 1995), altered metabolism (Elasser et al., 2000), reduced 
immune competence (Blecha, 2000), and behavioral disturbance. Increases 
in the circulation of glucocorticosteroids (cortisol, corticosterone, 
and aldosterone in marine mammals; see Romano et al., 2004) have been 
equated with stress for many years.
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and distress is the biotic 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 a 
risk to the animal's welfare. 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 biotic 
functions, which impair those functions that experience the diversion. 
For example, when mounting a stress response diverts energy away from 
growth in young animals, those animals may experience stunted growth. 
When mounting a stress response diverts energy from a fetus, an 
animal's reproductive success and fitness will suffer. In these cases, 
the animals will have entered a pre-pathological or pathological state 
which is called ``distress'' (sensu Seyle, 1950) or ``allostatic 
loading'' (sensu McEwen and Wingfield, 2003). This pathological state 
will last until the animal replenishes its biotic reserves sufficient 
to restore normal function. Note that these

[[Page 11742]]

examples involved a long-term (days or weeks) stress response exposure 
to stimuli.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses have also been documented 
fairly well through controlled experiment; because this physiology 
exists in every vertebrate that has been studied, it is not surprising 
that stress responses and their costs have been documented in both 
laboratory and free-living animals (for examples see, Holberton et al., 
1996; Hood et al., 1998; Jessop et al., 2003; Krausman et al., 2004; 
Lankford et al., 2005; Reneerkens et al., 2002; Thompson and Hamer, 
2000). Although no information has been collected on the physiological 
responses of marine mammals to anthropogenic sound exposure, studies of 
other marine animals and terrestrial animals would lead us to expect 
some marine mammals to experience physiological stress responses and, 
perhaps, physiological responses that would be classified as 
``distress'' upon exposure to anthropogenic sounds.
    For example, Jansen (1998) reported on the relationship between 
acoustic exposures and physiological responses that are indicative of 
stress responses in humans (e.g., elevated respiration and increased 
heart rates). Jones (1998) reported on reductions in human performance 
when faced with acute, repetitive exposures to acoustic disturbance. 
Trimper et al. (1998) reported on the physiological stress responses of 
osprey to low-level aircraft noise while Krausman et al. (2004) 
reported on the auditory and physiology stress responses of endangered 
Sonoran pronghorn to military overflights. Smith et al. (2004a, 2004b) 
identified noise-induced physiological transient stress responses in 
hearing-specialist fish (i.e., goldfish) that accompanied short- and 
long-term hearing losses. Welch and Welch (1970) reported physiological 
and behavioral stress responses that accompanied damage to the inner 
ears of fish and several mammals.
    Hearing is one of the primary senses marine mammals use to gather 
information about their environment and communicate with conspecifics. 
Although empirical information on the relationship between sensory 
impairment (TTS, PTS, and acoustic masking) on marine mammals remains 
limited, it seems reasonable to assume that reducing an animal's 
ability to gather information about its environment and to communicate 
with other members of its species would be stressful for animals that 
use hearing as their primary sensory mechanism. Therefore, we assume 
that acoustic exposures sufficient to trigger onset PTS or TTS would be 
accompanied by physiological stress responses because terrestrial 
animals exhibit those responses under similar conditions (NRC, 2003). 
More importantly, marine mammals might experience stress responses at 
received levels lower than those necessary to trigger onset TTS. Based 
on empirical studies of the time required to recover from stress 
responses (Moberg, 2000), NMFS also assumes that stress responses could 
persist beyond the time interval required for animals to recover from 
TTS and might result in pathological and pre-pathological states that 
would be as significant as behavioral responses to TTS. However, as 
stated previously in this document, the source levels of the drilling 
units are not loud enough to induce PTS or likely even TTS.
    Resonance effects (Gentry, 2002) and direct noise-induced bubble 
formations (Crum et al., 2005) are implausible in the case of exposure 
to an impulsive broadband source like an airgun array. If seismic 
surveys disrupt diving patterns of deep-diving species, this might 
result in bubble formation and a form of the bends, as speculated to 
occur in beaked whales exposed to sonar. However, there is no specific 
evidence of this upon exposure to airgun pulses. Additionally, no 
beaked whale species occur in the proposed exploration drilling area.
    In general, very little is known about 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) or any meaningful quantitative 
predictions of the numbers (if any) of marine mammals that might be 
affected in those ways. The low levels of continuous sound that will be 
produced by the drilling units are not expected to cause such effects. 
Additionally, marine mammals that show behavioral avoidance of the 
proposed activities, including most baleen whales, some odontocetes 
(including belugas), and some pinnipeds, are especially unlikely to 
incur auditory impairment or other physical effects.
(5) Stranding and Mortality
    Marine mammals close to underwater detonations of high explosives 
can be killed or severely injured, and the auditory organs are 
especially susceptible to injury (Ketten et al., 1993; Ketten, 1995). 
However, explosives are no longer used for marine waters for commercial 
seismic surveys; they have been replaced entirely by airguns or related 
non-explosive pulse generators. Underwater sound from drilling, support 
activities, and airgun arrays is less energetic and has slower rise 
times, and there is no proof that they can cause serious injury, death, 
or stranding, even in the case of large airgun arrays. However, the 
association of mass strandings of beaked whales with naval exercises 
involving mid-frequency active sonar, and, in one case, coinciding with 
a Lamont-Doherty Earth Observatory (L-DEO) seismic survey (Malakoff, 
2002; Cox et al., 2006), has raised the possibility that beaked whales 
exposed to strong pulsed sounds may be especially susceptible to injury 
and/or behavioral reactions that can lead to stranding (e.g., 
Hildebrand, 2005; Southall et al., 2007).
    Specific sound-related processes that lead to strandings and 
mortality are not well documented, but may include:
    (1) Swimming in avoidance of a sound into shallow water;
    (2) A change in behavior (such as a change in diving behavior) that 
might contribute to tissue damage, gas bubble formation, hypoxia, 
cardiac arrhythmia, hypertensive hemorrhage or other forms of trauma;
    (3) A physiological change, such as a vestibular response leading 
to a behavioral change or stress-induced hemorrhagic diathesis, leading 
in turn to tissue damage; and
    (4) Tissue damage directly from sound exposure, such as through 
acoustically-mediated bubble formation and growth or acoustic resonance 
of tissues.
    Some of these mechanisms are unlikely to apply in the case of 
impulse sounds. However, there are indications that gas-bubble disease 
(analogous to ``the bends''), induced in supersaturated tissue by a 
behavioral response to acoustic exposure, could be a pathologic 
mechanism for the strandings and mortality of some deep-diving 
cetaceans exposed to sonar. However, the evidence for this remains 
circumstantial and is associated with exposure to naval mid-frequency 
sonar, not seismic surveys or exploratory drilling programs (Cox et 
al., 2006; Southall et al., 2007).
    Both seismic pulses and continuous drillship sounds are quite 
different from mid-frequency sonar signals, and some mechanisms by 
which sonar sounds have been hypothesized to affect beaked whales are 
unlikely to apply to airgun pulses or drillships. Sounds produced by 
airgun arrays are broadband impulses

[[Page 11743]]

with most of the energy below 1 kHz, and the low-energy continuous 
sounds produced by drillships have most of the energy between 20 and 
1,000 Hz. Additionally, the non-impulsive, continuous sounds produced 
by the drilling units proposed to be used by Shell do not have rapid 
rise times. Rise time is the fluctuation in sound levels of the source. 
The type of sound that would be produced during the proposed drilling 
program will be constant and will not exhibit any sudden fluctuations 
or changes. Typical military mid-frequency sonar emits non-impulse 
sounds at frequencies of 2-10 kHz, generally with a relatively narrow 
bandwidth at any one time. A further difference between them is that 
naval exercises can involve sound sources on more than one vessel. 
Thus, it is not appropriate to assume that there is a direct connection 
between the effects of military sonar and oil and gas industry 
operations on marine mammals. However, evidence that sonar signals can, 
in special circumstances, lead (at least indirectly) to physical damage 
and mortality (e.g., Balcomb and Claridge, 2001; NOAA and USN, 2001; 
Jepson et al., 2003; Fern[aacute]ndez et al., 2004, 2005; Hildebrand, 
2005; Cox et al., 2006) suggests that caution is warranted when dealing 
with exposure of marine mammals to any high-intensity ``pulsed'' sound.
    There is no conclusive evidence of cetacean strandings or deaths at 
sea as a result of exposure to seismic surveys, but a few cases of 
strandings in the general area where a seismic survey was ongoing have 
led to speculation concerning a possible link between seismic surveys 
and strandings. Suggestions that there was a link between seismic 
surveys and strandings of humpback whales in Brazil (Engel et al., 
2004) were not well founded (IAGC, 2004; IWC, 2007). In September 2002, 
there was a stranding of two Cuvier's beaked whales in the Gulf of 
California, Mexico, when the L-DEO vessel R/V Maurice Ewing was 
operating a 20 airgun (8,490 in\3\) array in the general area. The link 
between the stranding and the seismic surveys was inconclusive and not 
based on any physical evidence (Hogarth, 2002; Yoder, 2002). 
Nonetheless, the Gulf of California incident, plus the beaked whale 
strandings near naval exercises involving use of mid-frequency sonar, 
suggests a need for caution in conducting seismic surveys in areas 
occupied by beaked whales until more is known about effects of seismic 
surveys on those species (Hildebrand, 2005). No injuries of beaked 
whales are anticipated during the proposed exploratory drilling program 
because none occur in the proposed area.

Potential Impacts From Drilling Wastes

    Shell will discharge drilling wastes to the Chukchi Sea. These 
discharges will be authorized under the EPA's National Pollutant 
Discharge Elimination System (NPDES) General Permit for Oil and Gas 
Exploration Activities on the Outer Continental Shelf in the Chukchi 
Sea (AKG-28-8100; ``NPDES exploration facilities GP''). This permit 
establishes various limits and conditions on the authorized discharges, 
and the EPA has determined that with these limits and conditions the 
discharges will not result in any unreasonable degradation of ocean 
waters.
    Under the NPDES exploration facilities GP, drilling wastes to be 
discharged must have a 96-hr Lethal Concentration 50 percent (LC50) 
toxicity of 30,000 parts per million or greater at the point of 
discharge. Both modeling and field studies have shown that discharged 
drilling wastes are diluted rapidly in receiving waters (Ayers et al. 
1980a, 1980b, Brandsma et al. 1980, NRC 1983, O'Reilly et al. 1989, 
Nedwed et al. 2004, Smith et al. 2004; Neff 2005). The dilution is 
strongly affected by the discharge rate. The NPDES exploration 
facilities GP limits the discharge of drilling wastes to 1,000 bbl/hr 
(159 m\3\/hr). For example, TetraTech (2011) modeled hypothetical 1,000 
bbl/hr (159 m\3\/hr) discharges of drilling wastes in water depths of 
131-164 ft (40-50 m) in the Beaufort and Chukchi Seas for the EPA and 
predicted dilution factors of 950-17,500 at a distance of 330 ft (100 
m) from the discharge point.
    The primary effect of the drilling waste discharges will be 
increases in total suspended solids (TSS) in the water column and 
localized increase in sedimentation on the sea floor. Shell conducted 
dispersion modeling of the drilling waste discharges using the Offshore 
Operators Committee Mud and Produced Water Discharge (OOC) model (Fluid 
Dynamix 2014). Simulations were performed for each of the six discrete 
drilling intervals with two discharge locations: Seafloor and sea 
surface. The Burger Prospect wells are all very similar in well design 
and site conditions so the simulation approximates the results for the 
all drill sites. The model results indicate that most of the increase 
in TSS will be ameliorated within 984 ft (300 m) of the discharge 
locations through settling and dispersion. Impacts to water quality 
will cease when the discharge is concluded.
    Modeling of similar discharges offshore of Sakhalin Island 
predicted a 1,000-fold dilution within 10 minutes and 330 ft (100 m) of 
the discharge. In a field study (O'Reilly et al. 1989) of a drilling 
waste discharge offshore of California, a 270 bbl (43 m\3\) discharge 
of drilling wastes was found to be diluted 183-fold at 33 ft (10 m) and 
1,049-fold at 330 ft (100 m). Neff (2005) concluded that concentrations 
of discharged drilling waste would diminish to levels that would have 
no effect within about two minutes of discharge and within 16 ft (5 m) 
of the discharge location.
    Discharges of drilling wastes could potentially displace marine 
mammals a short distance from a drilling location. However, it is 
likely that marine mammals will have already avoided the area due to 
sound energy generated by the drilling activities.
    Baleen whales, such as bowheads, tend to avoid drilling units at 
distances up to 12 mi (20 km). Therefore, it is highly unlikely that 
the whales will swim or feed in close enough proximity of discharges to 
be affected. The levels of drilling waste discharges are regulated by 
the NPDES exploration facilities GP. The impact of drilling waste 
discharges would be localized and temporary. Drilling waste discharges 
could displace endangered whales (bowhead and humpback whales) a short 
distance from a drill site. Effects on the whales present within a few 
meters of the discharge point would be expected, primarily due to 
sedimentation. However, endangered whales are not likely to have long-
term exposures to drilling wastes because of the episodic nature of 
discharges (typically only a few hours in duration).
    Like other baleen whales, gray whales will more than likely avoid 
drilling activities and therefore not come into close contact with 
drilling wastes. Gray whales are benthic feeders and the seafloor area 
covered by accumulations of discharged drilling wastes will be 
unavailable to the whales for foraging purposes, and represents an 
indirect impact on these animals. Such indirect impacts are negligible 
resulting in little effect on individual whales and no effect on the 
population, because such areas of disturbance will be few and in total 
will occur over a very small area representing an extremely small 
portion of available foraging habitat in the Chukchi Sea. Other baleen 
whales such as the minke whale, which could be found near the drill 
site, would not be expected to be affected.
    Discharges of drilling wastes are not likely to affect beluga 
whales and other odontocetes such as harbor porpoises

[[Page 11744]]

and killer whales. These marine mammals will likely avoid the immediate 
areas where drilling wastes will be discharged. Discharge modeling 
performed for both the Discoverer and the Polar Pioneer based on 
maximum prevailing current speeds of 9.84 in/s (25 cm/s), shows that 
sedimentation depth of drilling wastes at greater than 0.4 in (1 cm) 
thickness will occur within approximately 1,641 (500 m) of the drilling 
unit discharge point (Fluid Dynamix, 2014b). Concentrations of TSS, a 
transient feature of the discharge, are modeled to be below 15 mg/L at 
distances approximately 3,281 ft (1,000 m) from the drilling unit 
discharge point. Therefore, it is highly unlikely that beluga whales 
will come into contact with any drilling discharge and impacts are not 
expected.
    Seals are also not expected to be impacted by the discharges of 
drilling wastes. It is highly unlikely that a seal would remain within 
330 ft (100 m) of the discharge source for any extended period of time 
but if they were to remain within 330 ft (100 m) of the discharge 
source for an extended period of time, it is possible that 
physiological effects due to toxins could impact the animal.

Potential Impacts From Drilling Units' Presence

    The length of the Discoverer at 514 ft (156.7 m) and Polar Pioneer 
at 279 ft (85m) are not large enough to cause large-scale diversions 
from the animals' normal swim and migratory paths. The drilling units' 
physical footprints are small relative to the size of the geographic 
region either would occupy, and will likely not cause marine mammals to 
deflect greatly from their typical migratory routes.
    Any deflection of bowhead whales or other marine mammal species due 
to the physical presence of the drilling units or support vessels would 
be extremely small. Even if animals may deflect because of the presence 
of the drilling units, the Chukchi Sea's migratory corridor is much 
larger in size than the length of the drilling units, and animals would 
have other means of passage around the drilling units. In sum, the 
physical presence of the drilling units is not likely to cause a 
material deflection to migrating marine mammals. Moreover, any impacts 
would last only as long as the drilling units are actually present.
    Seal species which may be encountered during ice management 
activities include ringed seals, bearded seals, spotted seals, and the 
much less common ribbon seal. Ringed seals are found in the activity 
area year-around. Bearded seals spend the winter season in the Bering 
Sea, and then follow the ice edge as it retreats in spring. Spotted 
seals are found in the Bering Sea in winter and spring where they 
breed, molt, and pup in large groups. Few spotted seals are expected to 
be encountered in the Chukchi Sea until July. Even then, they are 
rarely seen on pack ice but are commonly observed hauled out on land or 
swimming in open water.
    Based on extensive analysis of digital imagery taken during aerial 
surveys in support of Shell's 2012 operations in the Chukchi and 
Beaufort Seas, ice seals are very infrequently observed hauled out on 
the ice in groups of greater than one individual. Tens of thousands of 
images from 17 flights that took place from July through October were 
reviewed in detail. Of 107 total observations of spotted or ringed 
seals on ice, only three of those sightings were of a group of two or 
more individuals. Since seals are found as individuals or in very small 
groups when they are in the activity area, the chance of a stampede 
event is very unlikely. Finally, ice seals are well adapted to move 
between ice and water without injury, including ``escape reactions'' to 
avoid predators.

Exploratory Drilling Program and Potential for Oil Spill

    As noted above, the specified activity involves the drilling of 
exploratory wells and associated activities in the Chukchi Sea during 
the 2015 open-water season. The impacts to marine mammals that are 
reasonably expected to occur will be behavioral in nature. The 
likelihood of a large or very large (i.e., [gteqt]1,000 barrels or 
[gteqt]150,000 barrels, respectively) oil spill occurring during 
Shell's proposed program has been estimated to be low. A total of 35 
exploration wells have been drilled between 1982 and 2003 in the 
Chukchi and Beaufort seas, and there have been no blowouts. In 
addition, no blowouts have occurred from the approximately 98 
exploration wells drilled within the Alaskan OCS (MMS, 2007a). Based on 
modeling conducted by Bercha (2008), the predicted frequency of an 
exploration well oil spill in waters similar to those in the Chukchi 
Sea, Alaska, is 0.000612 per well for a blowout sized between 10,000 
barrels (bbl) to 149,000 bbl and 0.000354 per well for a blowout 
greater than 150,000 bbl.
    Shell has implemented several design standards and practices to 
reduce the already low probability of an oil spill occurring as part of 
its operations. The wells proposed to be drilled in the Arctic are 
exploratory and will not be converted to production wells; thus, 
production casing will not be installed, and the well will be 
permanently plugged and abandoned once exploration drilling is 
complete. Shell has also developed and will implement the following 
plans and protocols: Shell's Critical Operations Curtailment Plan; 
DIMP; Well Control Plan; and Fuel Transfer Plan. Many of these safety 
measures are required by the Department of the Interior's interim final 
rule implementing certain measures to improve the safety of oil and gas 
exploration and development on the Outer Continental Shelf in light of 
the Deepwater Horizon event (see 75 FR 63346, October 14, 2010). 
Operationally, Shell has committed to the following to help prevent an 
oil spill from occurring in the Chukchi Sea:
    <bullet> Shell's Blow Out Preventer (BOP) was inspected and tested 
by an independent third party specialist;
    <bullet> Further inspection and testing of the BOP have been 
performed to ensure the reliability of the BOP and that all functions 
will be performed as necessary, including shearing the drill pipe;
    <bullet> Shell will conduct a function test of annular and ram BOPs 
every 7 days between pressure tests;
    <bullet> A second set of blind/shear rams will be installed in the 
BOP stack;
    <bullet> Full string casings will typically not be installed 
through high pressure zones;
    <bullet> Liners will be installed and cemented, which allows for 
installation of a liner top packer;
    <bullet> Testing of liners prior to installing a tieback string of 
casing back to the wellhead;
    <bullet> Utilizing a two-barrier policy; and
    <bullet> Testing of all casing hangers to ensure that they have two 
independent, validated barriers at all times.
    NMFS has considered Shell's proposed action and has concluded that 
there is no reasonable likelihood of serious injury or mortality of 
marine mammals from the proposed 2015 Chukchi Sea exploration drilling 
program. NMFS has consistently interpreted the term ``potential,'' as 
used in 50 CFR 216.107(a), to only include impacts that have more than 
a discountable probability of occurring, that is, impacts must be 
reasonably expected to occur. Hence, NMFS has regularly issued IHAs in 
cases where it found that the potential for serious injury or mortality 
was ``highly unlikely'' (See 73 FR 40512, 40514, July 15, 2008; 73 FR 
45969, 45971, August 7, 2008; 73 FR 46774, 46778, August 11, 2008; 73 
FR 66106, 66109, November 6, 2008; 74 FR 55368, 55371, October 27,

[[Page 11745]]

2009; 77 FR 27322, May 9, 2012; and 77 FR 27284, May 9, 2012).
    Interpreting ``potential'' to include impacts with any probability 
of occurring (i.e., speculative or extremely low probability events) 
would nearly preclude the issuance of IHAs in every instance. For 
example, NMFS would be unable to issue an IHA whenever vessels were 
involved in the marine activity since there is always some, albeit 
remote, possibility that a vessel could strike and seriously injure or 
kill a marine mammal. This would also be inconsistent with the dual-
permitting scheme Congress created and undesirable from a policy 
perspective, as limited agency resources would be used to issue 
regulations that provide no additional benefit to marine mammals beyond 
what is proposed in this IHA.
    Despite concluding that the risk of serious injury or mortality 
from an oil spill in this case is extremely remote, NMFS has 
nonetheless evaluated the potential effects of an oil spill on marine 
mammals. While an oil spill is not a component of Shell's specified 
activity, potential impacts on marine mammals from an oil spill are 
discussed in more detail below and will be addressed in the 
Environmental Assessment.

Potential Effects of Oil on Cetaceans

    The specific effects an oil spill would have on cetaceans are not 
well known. While mortality is unlikely, exposure to spilled oil could 
lead to skin irritation, baleen fouling (which might reduce feeding 
efficiency), respiratory distress from inhalation of hydrocarbon 
vapors, consumption of some contaminated prey items, and temporary 
displacement from contaminated feeding areas. Geraci and St. Aubin 
(1990) summarize effects of oil on marine mammals, and Bratton et al. 
(1993) provides a synthesis of knowledge of oil effects on bowhead 
whales. The number of cetaceans that might be contacted by a spill 
would depend on the size, timing, and duration of the spill and where 
the oil is in relation to the animals. Whales may not avoid oil spills, 
and some have been observed feeding within oil slicks (Goodale et al., 
1981). These topics are discussed in more detail next.
    In the case of an oil spill occurring during migration periods, 
disturbance of the migrating cetaceans from cleanup activities may have 
more of an impact than the oil itself. Human activity associated with 
cleanup efforts could deflect whales away from the path of the oil. 
However, noise created from cleanup activities likely will be short 
term and localized. Moreover, whale avoidance of clean-up activities 
may benefit whales by displacing them from the oil spill area.
    There is no direct evidence that oil spills, including the much 
studied Santa Barbara Channel and Exxon Valdez spills, have caused any 
deaths of cetaceans (Geraci, 1990; Brownell, 1971; Harvey and Dahlheim, 
1994). It is suspected that some individually identified killer whales 
that disappeared from Prince William Sound during the time of the Exxon 
Valdez spill were casualties of that spill. However, no clear cause and 
effect relationship between the spill and the disappearance could be 
established (Dahlheim and Matkin, 1994). The AT-1 pod of transient 
killer whales that sometimes inhabits Prince William Sound has 
continued to decline after the Exxon Valdez Oil Spill. Matkin et al. 
(2008) tracked the AB resident pod and the AT-1 transient group of 
killer whales from 1984 to 2005. The results of their photographic 
surveillance indicate a much higher than usual mortality rate for both 
populations the year following the spill (33% for AB Pod and 41% for 
AT-1 Group) and lower than average rates of increase in the 16 years 
after the spill (annual increase of about 1.6% for AB Pod compared to 
an annual increase of about 3.2% for other Alaska killer whale pods). 
In killer whale pods, mortality rates are usually higher for non-
reproductive animals and very low for reproductive animals and 
adolescents (Olesiuk et al., 1990, 2005; Matkin et al., 2005). No 
effects on humpback whales in Prince William Sound were evident after 
the Exxon Valdez Oil Spill (von Ziegesar et al., 1994). There was some 
temporary displacement of humpback whales out of Prince William Sound, 
but this could have been caused by oil contamination, boat and aircraft 
disturbance, displacement of food sources, or other causes.
    Migrating gray whales were apparently not greatly affected by the 
Santa Barbara spill of 1969. There appeared to be no relationship 
between the spill and mortality of marine mammals. The higher than 
usual counts of dead marine mammals recorded after the spill likely 
represented increased survey effort and therefore cannot be 
conclusively linked to the spill itself (Brownell, 1971; Geraci, 1990). 
The conclusion was that whales were either able to detect the oil and 
avoid it or were unaffected by it (Geraci, 1990).
(1) Oiling of External Surfaces
    Whales rely on a layer of blubber for insulation, so oil would have 
little if any effect on thermoregulation by whales. Effects of oiling 
on cetacean skin appear to be minor and of little significance to the 
animal's health (Geraci, 1990). Histological data and ultrastructural 
studies by Geraci and St. Aubin (1990) showed that exposures of skin to 
crude oil for up to 45 minutes in four species of toothed whales had no 
effect. They switched to gasoline and applied the sponge up to 75 
minutes. This produced transient damage to epidermal cells in whales. 
Subtle changes were evident only at the cell level. In each case, the 
skin damage healed within a week. They concluded that a cetacean's skin 
is an effective barrier to the noxious substances in petroleum. These 
substances normally damage skin by getting between cells and dissolving 
protective lipids. In cetacean skin, however, tight intercellular 
bridges, vital surface cells, and the extraordinary thickness of the 
epidermis impeded the damage. The authors could not detect a change in 
lipid concentration between and within cells after exposing skin from a 
white-sided dolphin to gasoline for 16 hours in vitro.
    Bratton et al. (1993) synthesized studies on the potential effects 
of contaminants on bowhead whales. They concluded that no published 
data proved oil fouling of the skin of any free-living whales, and 
conclude that bowhead whales contacting fresh or weathered petroleum 
are unlikely to suffer harm. Although oil is unlikely to adhere to 
smooth skin, it may stick to rough areas on the surface (Henk and 
Mullan, 1997). Haldiman et al. (1985) found the epidermal layer to be 
as much as seven to eight times thicker than that found on most whales. 
They also found that little or no crude oil adhered to preserved 
bowhead skin that was dipped into oil up to three times, as long as a 
water film stayed on the skin's surface. Oil adhered in small patches 
to the surface and vibrissae (stiff, hairlike structures), once it made 
enough contact with the skin. The amount of oil sticking to the 
surrounding skin and epidermal depression appeared to be in proportion 
to the number of exposures and the roughness of the skin's surface. It 
can be assumed that if oil contacted the eyes, effects would be similar 
to those observed in ringed seals; continued exposure of the eyes to 
oil could cause permanent damage (St. Aubin, 1990).
(2) Ingestion
    Whales could ingest oil if their food is contaminated, or oil could 
also be absorbed through the respiratory tract. Some of the ingested 
oil is voided in vomit or feces but some is absorbed and could cause 
toxic effects (Geraci, 1990).

[[Page 11746]]

When returned to clean water, contaminated animals can depurate this 
internal oil (Engelhardt, 1978, 1982). Oil ingestion can decrease food 
assimilation of prey eaten (St. Aubin, 1988). Cetaceans may swallow 
some oil-contaminated prey, but it likely would be only a small part of 
their food. It is not known if whales would leave a feeding area where 
prey was abundant following a spill. Some zooplankton eaten by bowheads 
and gray whales consume oil particles and bioaccumulation can result. 
Tissue studies by Geraci and St. Aubin (1990) revealed low levels of 
naphthalene in the livers and blubber of baleen whales. This result 
suggests that prey have low concentrations in their tissues, or that 
baleen whales may be able to metabolize and excrete certain petroleum 
hydrocarbons. Whales exposed to an oil spill are unlikely to ingest 
enough oil to cause serious internal damage (Geraci and St. Aubin, 
1980, 1982) and this kind of damage has not been reported (Geraci, 
1990).
(3) Fouling of Baleen
    Baleen itself is not damaged by exposure to oil and is resistant to 
effects of oil (St. Aubin et al., 1984). Crude oil could coat the 
baleen and reduce filtration efficiency; however, effects may be 
temporary (Braithwaite, 1983; St. Aubin et al., 1984). If baleen is 
coated in oil for long periods, it could cause the animal to be unable 
to feed, which could lead to malnutrition or even death. Most of the 
oil that would coat the baleen is removed after 30 min, and less than 
5% would remain after 24 hr (Bratton et al., 1993). Effects of oiling 
of the baleen on feeding efficiency appear to be minor (Geraci, 1990). 
However, a study conducted by Lambertsen et al. (2005) concluded that 
their results highlight the uncertainty about how rapidly oil would 
depurate at the near zero temperatures in arctic waters and whether 
baleen function would be restored after oiling.
(4) Avoidance
    Some cetaceans can detect oil and sometimes avoid it, but others 
enter and swim through slicks without apparent effects (Geraci, 1990; 
Harvey and Dahlheim, 1994). Bottlenose dolphins in the Gulf of Mexico 
apparently could detect and avoid slicks and mousse but did not avoid 
light sheens on the surface (Smultea and Wursig, 1995). After the Regal 
Sword spill in 1979, various species of baleen and toothed whales were 
observed swimming and feeding in areas containing spilled oil southeast 
of Cape Cod, MA (Goodale et al., 1981). For months following Exxon 
Valdez Oil Spill, there were numerous observations of gray whales, 
harbor porpoises, Dall's porpoises, and killer whales swimming through 
light-to-heavy crude-oil sheens (Harvey and Dalheim, 1994, cited in 
Matkin et al., 2008). However, if some of the animals avoid the area 
because of the oil, then the effects of the oiling would be less severe 
on those individuals.
(5) Factors Affecting the Severity of Effects
    Effects of oil on cetaceans in open water are likely to be minimal, 
but there could be effects on cetaceans where both the oil and the 
whales are at least partly confined in leads or at ice edges (Geraci, 
1990). In spring, bowhead and beluga whales migrate through leads in 
the ice. At this time, the migration can be concentrated in narrow 
corridors defined by the leads, thereby creating a greater risk to 
animals caught in the spring lead system should oil enter the leads. 
This situation would only occur if there were an oil spill late in the 
season and Shell could not complete cleanup efforts prior to ice 
covering the area. The oil would likely then be trapped in the ice 
until it began to thaw in the spring.
    In fall, the migration route of bowheads can be close to shore 
(Blackwell et al., 2009c). If fall migrants were moving through leads 
in the pack ice or were concentrated in nearshore waters, some bowhead 
whales might not be able to avoid oil slicks and could be subject to 
prolonged contamination. However, the autumn migration through the 
Chukchi Sea extends over several weeks, and some of the whales travel 
along routes north or inland of the area, thereby reducing the number 
of whales that could approach patches of spilled oil. Additionally, 
vessel activity associated with spill cleanup efforts may deflect 
whales traveling near the Burger prospect in the Chukchi Sea, thereby 
reducing the likelihood of contact with spilled oil.
    Bowhead and beluga whales overwinter in the Bering Sea (mainly from 
November to March). In the summer, the majority of the bowhead whales 
are found in the Canadian Beaufort Sea, although some have recently 
been observed in the U.S. Beaufort and Chukchi Seas during the summer 
months (June to August). Data from the Barrow-based boat surveys in 
2009 (George and Sheffield, 2009) showed that bowheads were observed 
almost continuously in the waters near Barrow, including feeding groups 
in the Chukchi Sea at the beginning of July. The majority of belugas in 
the Beaufort stock migrate into the Beaufort Sea in April or May, 
although some whales may pass Point Barrow as early as late March and 
as late as July (Braham et al., 1984; Ljungblad et al., 1984; 
Richardson et al., 1995a). Therefore, a spill in summer would not be 
expected to have major impacts on these species. Additionally, humpback 
and fin whales are only sighted in the Chukchi Sea in small numbers in 
the summer, as this is thought to be the extreme northern edge of their 
range. Therefore, impacts to these species from an oil spill would be 
extremely limited.

Potential Effects of Oil on Pinnipeds

    Ice seals are present in open-water areas during summer and early 
autumn. Externally oiled phocid seals often survive and become clean, 
but heavily oiled seal pups and adults may die, depending on the extent 
of oiling and characteristics of the oil. Prolonged exposure could 
occur if fuel or crude oil was spilled in or reached nearshore waters, 
was spilled in a lead used by seals, or was spilled under the ice when 
seals have limited mobility (NMFS, 2000). Adult seals may suffer some 
temporary adverse effects, such as eye and skin irritation, with 
possible infection (MMS, 1996). Such effects may increase stress, which 
could contribute to the death of some individuals. Ringed seals may 
ingest oil-contaminated foods, but there is little evidence that oiled 
seals will ingest enough oil to cause lethal internal effects. There is 
a likelihood that newborn seal pups, if contacted by oil, would die 
from oiling through loss of insulation and resulting hypothermia. These 
potential effects are addressed in more detail in subsequent 
paragraphs.
    Reports of the effects of oil spills have shown that some mortality 
of seals may have occurred as a result of oil fouling; however, large 
scale mortality had not been observed prior to the Exxon Valdez Oil 
Spill (St. Aubin, 1990). Effects of oil on marine mammals were not well 
studied at most spills because of lack of baseline data and/or the 
brevity of the post-spill surveys. The largest documented impact of a 
spill, prior to Exxon Valdez Oil Spill Exxon Valdez Oil Spill, was on 
young seals in January in the Gulf of St. Lawrence (St. Aubin, 1990). 
Brownell and Le Boeuf (1971) found no marked effects of oil from the 
Santa Barbara oil spill on California sea lions or on the mortality 
rates of newborn pups.
    Intensive and long-term studies were conducted after the Exxon 
Valdez Oil Spill in Alaska. There may have been a long-term decline of 
36% in numbers of molting harbor seals at oiled haul-out sites in 
Prince William Sound following

[[Page 11747]]

Exxon Valdez Oil Spill Exxon Valdez Oil Spill (Frost et al., 1994a). 
However, in a reanalysis of those data and additional years of surveys, 
along with an examination of assumptions and biases associated with the 
original data, Hoover-Miller et al. (2001) concluded that the Exxon 
Valdez Oil Spill effect had been overestimated. The decline in 
attendance at some oiled sites was more likely a continuation of the 
general decline in harbor seal abundance in Prince William Sound 
documented since 1984 (Frost et al., 1999) rather than a result of 
Exxon Valdez Oil Spill. The results from Hoover-Miller et al. (2001) 
indicate that the effects of Exxon Valdez Oil Spill were largely 
indistinguishable from natural decline by 1992. However, while Frost et 
al. (2004) concluded that there was no evidence that seals were 
displaced from oiled sites, they did find that aerial counts indicated 
26% fewer pups were produced at oiled locations in 1989 than would have 
been expected without the oil spill. Harbor seal pup mortality at oiled 
beaches was 23% to 26%, which may have been higher than natural 
mortality, although no baseline data for pup mortality existed prior to 
Exxon Valdez Oil Spill (Frost et al., 1994a). There was no conclusive 
evidence of spill effects on Steller sea lions (Calkins et al., 1994). 
Oil did not persist on sea lions themselves (as it did on harbor 
seals), nor did it persist on sea lion haul-out sites and rookeries 
(Calkins et al., 1994). Sea lion rookeries and haul out sites, unlike 
those used by harbor seals, have steep sides and are subject to high 
wave energy (Calkins et al., 1994).
(1) Oiling of External Surfaces
    Adult seals rely on a layer of blubber for insulation, and oiling 
of the external surface does not appear to have adverse 
thermoregulatory effects (Kooyman et al., 1976, 1977; St. Aubin, 1990). 
Contact with oil on the external surfaces can potentially cause 
increased stress and irritation of the eyes of ringed seals (Geraci and 
Smith, 1976; St. Aubin, 1990). These effects seemed to be temporary and 
reversible, but continued exposure of eyes to oil could cause permanent 
damage (St. Aubin, 1990). Corneal ulcers and abrasions, conjunctivitis, 
and swollen nictitating membranes were observed in captive ringed seals 
placed in crude oil-covered water (Geraci and Smith, 1976) and in seals 
in the Antarctic after an oil spill (Lillie, 1954).
    Newborn seal pups rely on their fur for insulation. Newborn ringed 
seal pups in lairs on the ice could be contaminated through contact 
with oiled mothers. There is the potential that newborn ringed seal 
pups that were contaminated with oil could die from hypothermia.
(2) Ingestion
    Marine mammals can ingest oil if their food is contaminated. Oil 
can also be absorbed through the respiratory tract (Geraci and Smith, 
1976; Engelhardt et al., 1977). Some of the ingested oil is voided in 
vomit or feces but some is absorbed and could cause toxic effects 
(Engelhardt, 1981). When returned to clean water, contaminated animals 
can depurate this internal oil (Engelhardt, 1978, 1982, 1985). In 
addition, seals exposed to an oil spill are unlikely to ingest enough 
oil to cause serious internal damage (Geraci and St. Aubin, 1980, 
1982).
(3) Avoidance and Behavioral Effects
    Although seals may have the capability to detect and avoid oil, 
they apparently do so only to a limited extent (St. Aubin, 1990). Seals 
may abandon the area of an oil spill because of human disturbance 
associated with cleanup efforts, but they are most likely to remain in 
the area of the spill. One notable behavioral reaction to oiling is 
that oiled seals are reluctant to enter the water, even when intense 
cleanup activities are conducted nearby (St. Aubin, 1990; Frost et al., 
1994b, 2004).
(4) Factors Affecting the Severity of Effects
    Seals that are under natural stress, such as lack of food or a 
heavy infestation by parasites, could potentially die because of the 
additional stress of oiling (Geraci and Smith, 1976; St. Aubin, 1990; 
Spraker et al., 1994). Female seals that are nursing young would be 
under natural stress, as would molting seals. In both cases, the seals 
would have reduced food stores and may be less resistant to effects of 
oil than seals that are not under some type of natural stress. Seals 
that are not under natural stress (e.g., fasting, molting) would be 
more likely to survive oiling. In general, seals do not exhibit large 
behavioral or physiological reactions to limited surface oiling or 
incidental exposure to contaminated food or vapors (St. Aubin, 1990; 
Williams et al., 1994). Effects could be severe if seals surface in 
heavy oil slicks in leads or if oil accumulates near haul-out sites 
(St. Aubin, 1990). An oil spill in open-water is less likely to impact 
seals.
    The potential effects to marine mammals described in this section 
of the document do not take into consideration the proposed monitoring 
and mitigation measures described later in this document (see the 
``Proposed Mitigation'' and ``Proposed Monitoring and Reporting'' 
sections).
Anticipated Effects on Marine Mammal Habitat
    The primary potential impacts to marine mammals and other marine 
species are associated with elevated sound levels produced by the 
exploratory drilling program (i.e. the drilling units and the airguns). 
However, other potential impacts are also possible to the surrounding 
habitat from physical disturbance and an oil spill (should one occur). 
This section describes the potential impacts to marine mammal habitat 
from the specified activity. Because the marine mammals in the area 
feed on fish and/or invertebrates there is also information on the 
species typically preyed upon by the marine mammals in the area.

Potential Impacts on Habitat From Seafloor Disturbance (Mooring and MLC 
Construction)

    Mooring of the drilling units and construction of MLCs will result 
in some seafloor disturbance and temporary increases in water column 
turbidity.
    The drilling units would be held in place during operations with 
systems of eight anchors for each unit. The embedment type anchors are 
designed to embed into the seafloor thereby providing the required 
resistance. The anchors will penetrate the seafloor on contact and may 
drag 2-3 or more times their length while being set. Both the anchor 
and anchor chain will disturb sediments in this process creating a 
trench or depression with surrounding berms where the displaced 
sediment is mounded. Some sediments will be suspended in the water 
column during the setting and subsequent removal of the anchors. The 
depression with associated berm, collectively known as an anchor scar, 
remains when the anchor is removed.
    Dimensions of future anchor scars can be estimated based on the 
dimensions of the anchor. Shell estimates that each anchor may impact a 
seafloor area of up to about 2,510 ft\2\ (233m\2\). Impact estimates 
associated with mooring a drilling unit by its eight anchors is 20,078 
ft\2\ (1,865 m\2\) of seafloor assuming that the 15 metric ton anchors 
are used and set only once. Shell plans to pre-set anchors and deploy 
mooring lines at each drill site prior to arrival of the drilling 
units. Unless moved by an outside force such as sea current, anchors 
should only need to be set once per drill site.

[[Page 11748]]

    Once the drilling units end operation, the Polar Pioneer anchors 
will be retrieved and the Discoverer anchors may be left on site for 
wet storage. Over time the anchor scars will be filled through natural 
movement of sediment. The duration of the scars depends upon the energy 
of the system, water depth, ice scour, and sediment type. Anchor scars 
were visible under low energy conditions in the North Sea for five to 
ten years after retrieval. Scars typically do not form or persist in 
sandy mud or sand sediments but may last for nine years in hard clays 
(Centaur Associates, Inc 1984). Surficial sediments in Shell's Burger 
Prospect consist of soft sandy mud (silt and clay) with lesser amounts 
of gravel (Battelle Memorial Institute 2010; Blanchard et al. 2010a, 
b). The energy regime, plus possible effects of ice gouge in the 
Chukchi Sea suggests that anchor scars would be refilled faster than in 
the North Sea.
    Excavation of each MLC by the drilling units using a large diameter 
drill bit will displace about 589m\3\ of seafloor sediments and 
directly disturb approximately 1,075 ft\2\ (100 m\2\) of seafloor. 
Pressurized air and seawater (no drilling mud used) will be used to 
assist in the removal of the excavated materials from the MLC. Some of 
the excavated sediments will be displaced to adjacent seafloor areas 
and some will be pumped and discharged on the seafloor away from the 
MLC. These excavated materials will also have some indirect effects as 
they are suspended in the water and deposited on the seafloor in the 
vicinity of the MLCs. Direct and indirect effects would include slight 
changes in seafloor relief and sediment consistency, and smothering of 
benthic organisms.

Potential Impacts on Habitat From Sound Generation

    Underwater noise generated from Shell's proposed exploration 
drilling activity may potentially affect marine mammal prey species, 
which are fish species and various invertebrates in the action area.
(1) Zooplankton
    Zooplankton are food sources for several endangered species, 
including bowhead, fin, and humpback whales. The primary generators of 
sound energy associated with the exploration drilling program are the 
airgun array during the conduct of ZVSPs, the drilling units during 
drilling, and marine vessels, particularly during ice management and 
DP. Sound energy generated by these activities will not negatively 
impact the diversity and abundance of zooplankton, and will therefore 
have no direct effect on marine mammals.
    Sound energy generated by the airgun arrays to be used for the 
ZVSPs will have no more than negligible effects on zooplankton. Studies 
on euphausiids and copepods, which are some of the more abundant and 
biologically important groups of zooplankton in the Chukchi Sea, have 
documented the use of hearing receptors to maintain schooling 
structures (Wiese 1996) and detection of predators (Hartline et al. 
1996, Wong 1996) respectively, and therefore have some sensitivity to 
sound; however any effects of airguns on zooplankton would be expected 
to be restricted to the area within a few feet or meters of the airgun 
array and would likely be sublethal. Studies on brown shrimp in the 
Wadden Sea (Webb and Kempf 1998) revealed no particular sensitivity to 
sounds generated by airguns at sound levels of 190 dB re 1 [mu]Pa rms 
at 3.3 ft. (1.0 m) in water depths of 6.6 ft. (2.0 m). Koshleva (1992) 
reported no detectable effects on the amphipod (Gammarus locusta) at 
distances as close as 0.5 m from an airgun with a source level of 223 
dB re 1 [mu]Pa rms. A recent Canadian government review of the impacts 
of seismic sound on invertebrates and other organisms (CDFO 2004) 
included similar findings; this review noted ``there are no documented 
cases of invertebrate mortality upon exposure to seismic sound under 
field operating conditions'' (CDFO 2004). Some sublethal effects (e.g., 
reduced growth, behavioral changes) were noted (CDFO 2004).
    The energy from airguns has sometimes been shown to damage eggs and 
fry of some fish. Eggs and larvae of some fish may apparently sustain 
sublethal to lethal effects if they are within very close proximity to 
the seismic-energy-discharge point. These types of effects have been 
demonstrated by some laboratory experiments using single airguns (e.g., 
Kosheleva 1992, Matishov 1992, Holliday et al. 1987), while other 
similar studies have found no material increases in mortality or 
morbidity due to airgun exposure (Dalen and Knutsen 1986, Kostyuvchenko 
1973). The effects, where they do occur, are apparently limited to the 
area within 3-6 ft. (1-2 m) from the airgun-discharge ports. In their 
detailed review of studies on the effects of airguns on fish and 
fisheries, Dalen et al. (1996) concluded that airguns can have 
deleterious effects on fish eggs and larvae out to a distance of 16 ft 
(5.0 m), but that the most frequent and serious injuries are restricted 
to the area within 5.0 ft (1.5 m) of the airguns. Most investigators 
and reviewers (Gausland 2003, Thomson and Davis 2001, Dalen et al. 
1996) have concluded that even seismic surveys with much larger airgun 
arrays than are used for shallow hazards and site clearance surveys, 
have no impact to fish eggs and larvae discernible at the population or 
fisheries level.
    These studies indicate that some zooplankton within a distance of 
about 16 ft. (5.0 m) or less from the airgun array may sustain 
sublethal or lethal injuries but there would be no population effects 
even over small areas. Therefore there would be no indirect effect on 
marine mammals.
    Ice management is likely to be the most intense sources of sound 
associated with the exploration drilling program Richardson et al. 
(1995a). Ice management vessels, during active ice management, may have 
to adjust course forward and astern while moving ice and thereby create 
greater variability in propeller cavitation than other vessels that 
maintain course with less adjustment. The drilling units maintain 
station during drilling without activation of propulsion propellers. 
Richardson (et al.1995a) reported that the noise generated by an 
icebreaker pushing ice was 10-15 dB re 1 [mu]Pa rms greater than the 
noise produced by the ship underway in open water. It is expected that 
the lower level of sound produced by the drilling units, ice 
management, or other vessels would have less impact on zooplankton than 
would 3D seismic (survey) sound.
    No appreciable adverse impact on zooplankton populations will occur 
due in part to large reproductive capacities and naturally high levels 
of predation and mortality of these populations. Any mortality or 
impacts on zooplankton as a result of Shell's operations is immaterial 
as compared to the naturally occurring reproductive and mortality rates 
of these species. This is consistent with previous conclusions that 
crustaceans (such as zooplankton) are not particularly sensitive to 
sound produced by seismic sounds (Wiese 1996). Impact from sound energy 
generated by an ice breaker, other marine vessels, and drill ships 
would have less impact, as these activities produce lower sound energy 
levels (Burns 1993). Historical sound propagation studies performed on 
the Kulluk by Hall et al. (1994) also indicate the Kulluk and similar 
drilling units would have lower sound energy output than three-
dimensional seismic sound sources (Burns et al. 1993). The drilling 
units Discoverer and Polar Pioneer would emit sounds at a lower level 
than the Kulluk and therefore the impacts

[[Page 11749]]

due to drilling noise would be even lower than the Kulluk. Therefore, 
zooplankton organisms would not likely be affected by sound energy 
levels by the vessels to be used during Shell's exploration drilling 
activities in the Chukchi Sea.
(2) Benthos
    There was no indication from post-drilling benthic biomass or 
density studies that previous drilling activities at the Hammerhead 
Prospect have had a measurable impact on the ecology of the immediate 
local area. To the contrary, the abundance of benthic communities in 
the Sivulliq area would suggest that the benthos were actually thriving 
there (Dunton et al. 2008).
    Sound energy generated by exploration drilling and ice management 
activities will not appreciably affect diversity and abundance of 
plants or animals on the seafloor. The primary generators of sound 
energy are the drilling units and marine vessels. Ice management 
vessels are likely to be the loudest sources of sounds associated with 
the exploration drilling program (Richardson et al. 1995a). Ice 
management vessels, during active ice management, may have to adjust 
course forward and astern while moving ice and thereby create greater 
variability in propeller cavitation than other vessels that maintain 
course with less adjustment. The drilling units maintain station during 
drilling without activation of propulsion propellers. Richardson et al. 
(1995a) reported that the noise generated by an icebreaker pushing ice 
was 10-15 dB re 1 [mu]Pa rms greater than the noise produced by the 
ship underway in open water. The lower level of sound produced by the 
drilling units, ice management vessels, or other vessels will have less 
impact on bottom-dwelling organisms than would 3D seismic (survey) 
sound.
    No appreciable adverse impacts on benthic populations would be 
expected due in part to large reproductive capacities and naturally 
high levels of predation and mortality of these populations. Any 
mortalities or impacts that might occur as a result of Shell's 
operations is immaterial compared to the naturally occurring high 
reproductive and mortality rates. This is consistent with previous BOEM 
conclusions that the effect of seismic exploration on benthic organisms 
probably would be immeasurable (USDI/MMS 2007). Impacts from sound 
energy generated by ice breakers, other marine vessels, and drilling 
units would have less impact, as these activities produce much lower 
sound energy levels (Burns et al. 1993).
(3) Fish
    Fish react to sound and use sound to communicate (Tavolga et al. 
1981). Experiments have shown that fish can sense both the intensity 
and direction of sound (Hawkins 1981). Whether or not fish can hear a 
particular sound depends upon its frequency and intensity. Wavelength 
and the natural background sound also play a role. The intensity of 
sound in water decreases with distance as a result of geometrical 
spreading and absorption. Therefore, the distance between the sound 
source and the fish is important. Physical conditions in the sea, such 
as temperature thermoclines and seabed topography, can influence 
transmission loss and thus the distance at which a sound can be heard.
    The impact of sound energy from exploration drilling and ice 
management activities will be negligible and temporary. Fish typically 
move away from sound energy above a level that is at 120 dB re 1 [mu]Pa 
rms or higher (Ona 1988).
    Drilling unit sound source levels during drilling can range from 90 
dB re 1 [mu]Pa rms within 31 mi (50 km) of the drilling unit to 138 dB 
re 1 [mu]Pa rms within a distance of 0.06 mi (0.01 km) from the 
drilling unit (Greene 1985, 1987b). These are predicted sound levels at 
various distances based on modeled transmission loss equations in the 
literature (Greene 1987b). Ice management vessel sound source levels 
can range from 174-184 dB re 1 [mu]Pa rms. At these intensity levels, 
fish may avoid the drilling unit, ice management vessels, or other 
large support vessels. This avoidance behavior is temporary and limited 
to periods when a vessel is underway or drilling. There have been no 
studies of the direct effects of ice management vessel sounds on fish. 
However, it is known that the ice management vessels produce sounds 
generally 10-15 dB re 1 [mu]Pa rms higher when moving through ice 
rather than open water (Richardson et al. 1995b). In general, fish show 
greater reactions to a spike in sound energy levels, or impulse sounds, 
rather than a continuous high intensity signal (Blaxter et al. 1981).
    Fish sensitivity to impulse sound such as that generated by ZVSPs 
varies depending on the species of fish. Cod, herring and other species 
of fish with swim bladders have been found to be relatively sensitive 
to sound, while mackerel, flatfish, and many other species that lack 
swim bladders have been found to have poor hearing (Hawkins 1981, 
Hastings and Popper 2005). An alarm response in these fish is elicited 
when the sound signal intensity rises rapidly compared to sound rising 
more slowly to the same level (Blaxter et al. 1981). Any such effects 
on fish would be negligible and have no indirect effect on marine 
mammals.

Potential Impacts on Habitat From Drilling Wastes

    Discharges of drilling wastes must be authorized by the NPDES 
exploration facilities GP, and this GP places numerous conditions and 
limitations on such discharges. The EPA (2012) has determined that with 
these limits and conditions in place, the discharges will not result in 
any unreasonable degradation of ocean waters. The primary impacts of 
the discharges are increases in TSS in the water column and the 
deposition of drilling wastes on the seafloor. These impacts would be 
localized to the drill sites and temporary.
(1) Zooplankton
    Reviews by EPA (2006) and Neff (2005) indicate that though 
planktonic organisms are sensitive to environmental conditions (e.g., 
temperature, light, availability of nutrients, and water quality), 
there is little or no evidence of effects from drilling waste 
discharges on plankton in the ocean. In the laboratory, high 
concentrations of drilling wastes have been shown to have lethal or 
sublethal effects on zooplankton due to toxicity and abrasion by 
suspended sediments. These effects are minimized at the drill site by 
limits and conditions placed on the discharges by the NPDES exploration 
facilities GP, which include discharge rate limits and toxicity limits.
    Any impact by drilling waste discharges on zooplankton would be 
localized and temporary. Fine-grained particulates and other solids in 
drilling wastes could cause sublethal effects to organisms in the water 
column. Responses observed in the laboratory following exposure to 
drilling mud include alteration of respiration and filtration rates and 
altered behavior. Zooplankton in the immediate area of discharge from 
drilling operations could potentially be adversely impacted by 
sediments in the water column, which could clog respiratory and feeding 
structures, cause abrasions to gills and other sensitive tissues, or 
alter behavior or development. However, the planktonic organisms are 
not likely to have long-term exposures to the drilling waste because of 
the episodic nature of discharges (typically only a few hours in 
duration), the small area affected, and the movement of the organisms 
with the ocean currents. The discharged waste

[[Page 11750]]

must have low toxicities to meet permit requirements and modeling 
studies indicate dilution factors of >1,000 within 328 ft (100 m). 
Modeling and monitoring studies have demonstrated that increased TSS in 
the water column from the discharges would largely be limited to the 
area within 984 ft (300 m) from the discharge. This impact would likely 
not have more than a short-term impact on zooplankton and no effect on 
zooplankton populations, and therefore no indirect effects on marine 
mammals.
(2) Benthos
    Benthic organisms would primarily be affected by the discharges 
through the deposition of the discharged drilling waste on the seafloor 
resulting in the smothering of organisms, changes in the consistency of 
sediments on the seafloor, and possible elevation in heavy metal 
concentrations in the accumulations.
    Drilling waste discharges are regulated by the EPA's NPDES 
exploration facilities GP. The impact of drilling waste discharges 
would be localized and temporary. Effects on benthic organisms present 
within a few meters of the discharge point would be expected, primarily 
due to sedimentation. However, benthic animals are not likely to have 
long-term exposures to drilling wastes because of the episodic nature 
of discharges (typically only a few hours in duration).
    Shell conducted dispersion modeling of the drilling waste 
discharges using the Offshore Operators Committee Mud and Produced 
Water Discharge (OOC) model (Fluid Dynamix 2014a, b). The modeling 
effort provided predictions of the area and thickness of accumulations 
of discharged drilling waste on the seafloor. The USA EPA has performed 
an evaluation of drilling waste in support of the issuance of NPDES GP 
AKG-28-8100 for exploration facilities (EPA, 2012b) (October 2012), and 
determined these accumulations will not result in any unreasonable 
degradation of the marine environment.
    Heavy metal contamination of sediments and resulting effects on 
benthic organisms is not expected. The NPDES exploration facilities GP 
contains stringent limitations on the concentrations of mercury, 
cadmium, chromium, silver, and thallium allowed in discharged drilling 
waste. Additional limitations are placed on free oil, diesel oil, and 
total aromatic hydrocarbons allowed in discharged drilling waste. 
Discharge rates are also controlled by the permit. Baseline studies at 
the 1985 Hammerhead drill site (Trefry and Trocine 2009) detected 
background levels Al, Fe, Zn, Cd and Hg in all surface and subsurface 
sediment samples. Considering the relatively small area that drilling 
waste discharges will be deposited, no material impacts on sediment are 
expected to occur. The expected increased concentrations of Zn, Cd, and 
Cr in sediments near the drill site due to the discharge are in the 
range where no or low effects would result.
    Studies in the 1980s, 1999, 2000, and 2002 (Brown et al. 2001 in 
USDI/MMS 2003) also found that benthic organism near drill sites in the 
Beaufort Sea have accumulated neither petroleum hydrocarbon nor heavy 
metals. In 2008 Shell investigated the benthic communities (Dunton et 
al. 2008) and sediments (Trefry and Trocine 2009) around the Sivulliq 
Prospect including the location of the historical Hammerhead drill site 
that was drilled in 1985. Benthic communities at the historical 
Hammerhead drill site were found not to differ statistically in 
abundance, community structure, or diversity, from benthic communities 
elsewhere in this portion of the Beaufort Sea, indicating that there 
was no long term effect.
    Sediment samples taken in the Chukchi Sea Environmental Studies 
Program Burger Study Area were analyzed for metal and hydrocarbon 
concentrations (Neff et al. 2010). Concentrations of all measured 
hydrocarbon types were found to be well within the range of non-toxic 
background concentrations reported by other Alaskan and Arctic coastal 
and shelf sediment studies (Neff et al. 2010, Dunton et al. 2012). 
Metal concentrations were found to be quite variable. Average 
concentrations of all metals except for arsenic and barium were found 
to be lower than those reported for average marine sediment.
    Trefry et al. (2012) confirmed findings by Neff et al. 2010 that 
concentrations of all measured hydrocarbon types were well within the 
range of non-toxic background concentrations reported by other Alaskan 
and Arctic coastal and shelf sediment studies.
    Neff et al. (2010) assessed the concentrations of metals and 
various hydrocarbons in sediments at the historic Burger and Klondike 
wells in the Chukchi Sea, which were drilled in 1989-1990. Surface and 
subsurface sediments collected in 2008 at the historic drill sites 
contained higher concentrations of all types of analyzed hydrocarbon in 
comparison to the surrounding area. The same pattern was found for the 
metal barium, with concentrations 2-3 times greater at the historic 
drill sites (mean = 1,410 [mu]/g and 1,300 [mu]/g) than in the 
surrounding areas (639 [mu]/g and 595 [mu]/g). Concentrations of 
copper, mercury, and lead, were elevated in a few samples from the 
historic drill sites where barium was also elevated. All observed 
concentrations of hydrocarbons or metals in the sediment samples from 
the historic drill sites were below levels (below ERL or Effects Range 
Low of Long 1995) believed to have adverse ecological effects (Neff et 
al. 2010). Similar results were reported by Trefry and Trocine (2009) 
for the historic Hammerhead drill sites in the Beaufort Sea.
    These data show that the potential accumulation of heavy metals in 
discharged drilling waste on the Chukchi seafloor associated with 
drilling exploration wells is very limited and does not pose a threat. 
Impacts to seafloor sediments from the discharge of drilling wastes 
will be minor, as they would be restricted to a very small portion of 
the activity area and will not result in contamination.
    The drilling waste discharges will be conducted as authorized by 
the EPA's NPDES exploration facilities GP, which limits the metal 
content and flow rate for such discharges. The EPA (2012b) analyzed the 
effects of these types of discharges, including potential transport of 
pollutants such as metals by biological, physical, or chemical 
processes, and has concluded that these types of discharges do not 
result in unreasonable degradation of ocean waters. The physical 
effects of mooring and MLC construction would be restricted to a very 
small portion of the Chukchi Sea seafloor (15.7-33.2 ac in total for 
the exploration program) which represents less than 0.000011%-0.000024% 
of the seafloor of the Chukchi Sea. However, the predicted small 
increases in concentrations of metals will likely be evident for a 
number of years until gouged by ice, redistributed by currents, or 
buried under natural sedimentation.
    There is relatively little information on the effects of various 
deposition depths on arctic biota (Hurley and Ellis 2004); most such 
studies have investigated the effects of deposition of dredged 
materials (Wilbur 1992). Burial depths as low as 1.0 in (2.54 cm) have 
been found to be lethal for some benthic organisms (Wilbur 1992, EPA 
2006). Accumulations of drilling waste to depths > 1.0 in (>2.54 cm) 
will be restricted to very small areas of the seafloor around each 
drill site and in total represent an extremely small portion of the 
Chukchi Sea. These areas would be re-colonized by benthic organisms 
rather quickly. Impacts to benthic organisms are therefore

[[Page 11751]]

considered to be negligible with no indirect effects on marine mammals. 
As required by the NPDES exploration facilities GP, Shell will 
implement an environmental monitoring program (EMP), to assess the 
recovery of the benthos from impacts drilling waste discharges.
(3) Fish
    Drilling waste discharges are regulated by the NPDES exploration 
facilities GP. The impact of drilling waste discharges would be 
localized and temporary. Drilling waste discharges could displace fish 
a short distance from a drill site. Effects on fish and fish larvae 
present within a few meters of the discharge point would be expected, 
primarily due to sedimentation. However, fish and fish larvae that live 
in the water column are not likely to have long-term exposures to 
drilling wastes because of the episodic nature of the discharges 
(typically only a few hours in duration).
    Although unlikely at deeper offshore drilling locations, demersal 
fish eggs could be smothered if discharges occur in a spawning area 
during the period of egg production. No specific demersal fish spawning 
locations have been identified at the Burger drill site locations. The 
most abundant and trophically important marine fish, the Arctic cod, 
spawns with planktonic eggs and larvae under the sea ice during winter 
and will therefore have little exposure to discharges.
    Habitat alteration concerns apply to special or relatively uncommon 
habitats, such as those important for spawning, nursery, or 
overwintering. Important fish overwintering habitats are located in 
coastal rivers and nearshore coastal waters, but are not found in the 
proposed exploration drilling areas. Important spawning areas have not 
been identified in the Chukchi Sea. Impacts on fish will be negligible, 
with no indirect effects on marine mammals.

Potential Impacts on Habitat From Ice Management/Icebreaking Activities

    Ice management or icebreaking activities include the physical 
pushing or moving of ice in the proposed exploration drilling area and 
to prevent ice floes from striking the drilling unit. Ringed, bearded, 
spotted, and ribbon seals) are dependent on sea ice for at least part 
of their life history. Sea ice is important for life functions such as 
resting, breeding, and molting. These species are dependent on two 
different types of ice: Pack ice and landfast ice. Shell does not 
expect to have to manage pack ice during the majority of the drilling 
season. The majority of the ice management or icebreaking should occur 
in the early and latter portions of the drilling season. Landfast ice 
would not be present during Shell's proposed operations.
    The ringed seal is the most common pinniped species in the Chukchi 
Sea activity area. While ringed seals use ice year-round, they do not 
construct lairs for pupping until late winter/early spring on the 
landfast ice. Shell plans to conclude drilling on or before 31 October, 
therefore Shell's activities would not impact ringed seal lairs or 
habitat needed for breeding and pupping in the Chukchi Sea. Ringed 
seals can be found on the pack ice surface in the late spring and early 
summer in the Chukchi Sea, the latter part of which may overlap with 
the start of Shell's planned exploration drilling activities. 
Management of pack ice that contains hauled out seals may result in the 
animals becoming startled and entering the water, but such effects 
would be brief.
    Ice management or icebreaking would occur during a time when ringed 
seal life functions such as breeding, pupping, and molting do not occur 
in the proposed project area. Additionally, these life functions occur 
more commonly on landfast ice, which will not be impacted by Shell's 
activity.
    Bearded seals breed in the Bering and Chukchi Seas, but would not 
be plentiful in the area of the Chukchi Sea exploration drilling 
program. Spotted seals are even less common in the Chukchi Sea activity 
area. Ice is used by bearded and spotted seals for critical life 
functions such as breeding and molting, but it is unlikely these life 
functions would occur in the proposed project area, during the time in 
which drilling activities will take place. The availability of ice 
would not be impacted as a result of Shell's exploration drilling 
program.
    Ice-management or icebreaking related to Shell's planned 
exploration drilling program in the Chukchi Sea is not expected to have 
any habitat-related effects that could cause material or long-term 
consequences for individual marine mammals or on the food sources that 
they utilize.

Potential Impacts From an Oil Spill

    Lower trophic organisms and fish species are primary food sources 
for Arctic marine mammals. However, as noted earlier in this document, 
the offshore areas of the Chukchi Sea are not primary feeding grounds 
for many of the marine mammals that may pass through the area. 
Therefore, impacts to lower trophic organisms (such as zooplankton) and 
marine fishes from an oil spill in the proposed drilling area would not 
be likely to have long-term or significant consequences to marine 
mammal prey. Impacts would be greater if the oil moves closer to shore, 
as many of the marine mammals in the area have been seen feeding at 
nearshore sites (such as bowhead whales). Gray whales do feed in more 
offshore locations in the Chukchi Sea; therefore, impacts to their prey 
from oil could have some impacts.
    Due to their wide distribution, large numbers, and rapid rate of 
regeneration, the recovery of marine invertebrate populations is 
expected to occur soon after the surface oil passes. Spill response 
activities are not likely to disturb the prey items of whales or seals 
sufficiently to cause more than minor effects. Spill response 
activities could cause marine mammals to avoid the disturbed habitat 
that is being cleaned. However, by causing avoidance, animals would 
avoid impacts from the oil itself. Additionally, the likelihood of an 
oil spill is expected to be very low, as discussed earlier in this 
document.

Proposed Mitigation

    In order to issue an incidental take authorization (ITA) under 
Sections 101(a)(5)(A) and (D) of the MMPA, NMFS must, where applicable, 
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 (where relevant). This section summarizes the contents 
of Shell's Marine Mammal Monitoring and Mitigation Plan (4MP). Later in 
this document in the ``Proposed Incidental Harassment Authorization'' 
section, NMFS lays out the proposed conditions for review, as they 
would appear in the final IHA (if issued).
    Shell submitted a 4MP as part of its application (see ADDRESSES). 
Shell's planned offshore drilling program incorporates both design 
features and operational procedures for minimizing potential impacts on 
marine mammals and on subsistence hunts. The 4MP is a combination of 
active monitoring in the area of operations and the implementation of 
mitigation measures designed to minimize project impacts to marine 
resources. Monitoring will provide information on marine mammals 
potentially affected by exploration activities, in addition to 
facilitating real time mitigation to

[[Page 11752]]

prevent injury of marine mammals by industrial sounds or activities.

Vessel Based Marine Mammal Monitoring for Mitigation

    The objectives of the vessel based marine mammal monitoring are to 
ensure that disturbance to marine mammals and subsistence hunts is 
minimized, that effects on marine mammals are documented, and that data 
is collected on the occurrence and distribution of marine mammals in 
the project area.
    The marine mammal monitoring will be implemented by a team of 
experienced protected species observers (PSOs). The PSOs will be 
experienced biologists and Alaska Native personnel trained as field 
observers. PSOs will be stationed on both drilling units, ice 
management vessels, anchor handlers and other drilling support vessels 
engaged in transit to and between drill sites to monitor for marine 
mammals. The duties of the PSOs will include; watching for and 
identifying marine mammals, recording their numbers, recording 
distances and reactions of marine mammals to exploration drilling 
activities, initiating mitigation measures when appropriate, and 
reporting results of the vessel based monitoring program, which will 
include the estimation of the number of marine mammal ``exposures'' as 
defined by the NMFS and stipulated in the IHA.
    The vessel based work will provide:
    <bullet> The basis for initiating real-time mitigation, if 
necessary, as required by the various permits that Shell receives;
    <bullet> Information needed to estimate the number of ``exposures'' 
of marine mammals to sound levels that may result in harassment, which 
must be reported to NMFS;
    <bullet> Data on the occurrence, distribution, and activities of 
marine mammals in the areas where drilling activity is conducted;
    <bullet> Information to compare the distances, distributions, 
behavior, and movements of marine mammals relative to the drilling unit 
during times with and without drilling activity occurring;
    <bullet> A communication channel to coastal communities including 
whalers; and
    <bullet> Employment and capacity building for local residents, with 
one objective being to develop a larger pool of experienced Alaska 
Native PSOs.
    The vessel based monitoring will be operated and administered 
consistent with monitoring programs conducted during past exploration 
drilling activities, seismic and shallow hazards surveys, or 
alternative requirements stipulated in permits issued to Shell. 
Agreements between Shell and other agencies will also be fully 
incorporated. PSOs will be provided training through a program approved 
by the NMFS.

Mitigation Measures During the Exploration Drilling Program

    Shell's planned exploration drilling activities incorporate design 
features and operational procedures aimed at minimizing potential 
impacts on marine mammals and subsistence hunts. Some of the mitigation 
design features include:
    <bullet> Conducting pre-season acoustic modeling to establish the 
appropriate exclusion and disturbance zones;
    <bullet> Vessel based PSO monitoring to implement appropriate 
mitigation if necessary, and to determine the effects of the drilling 
program on marine mammals;
    <bullet> Passive acoustic monitoring of drilling and vessel sounds 
and marine mammal vocalizations; and
    <bullet> Aerial surveys with photographic equipment over operations 
and in coastal and nearshore waters with photographic equipment to help 
determine the effects of project activities on marine mammals; and 
seismic activity mitigation measures during acquisition of the ZVSP 
surveys.
    The potential disturbance of marine mammals during drilling 
activities will be mitigated through the implementation of several 
vessel based mitigation measures as necessary.
(1) Exclusion and Disturbance Zones
    Mitigation for NMFS' incidental take authorizations typically 
includes ``safety radii'' or ``exclusion zones'' for marine mammals 
around airgun arrays and other impulsive industrial sound sources where 
received levels are >=180 dB re 1 [mu]Pa (rms) for cetaceans and >=190 
dB re 1 [mu]Pa (rms) for pinnipeds. These zones are based on a 
cautionary assumption that sound energy at lower received levels will 
not injure these animals or impair their hearing abilities, but that 
higher received levels might have some such effects. Disturbance or 
behavioral effects to marine mammals from underwater sound may occur 
from exposure to sound at distances greater than these zones 
(Richardson et al. 1995). The NMFS assumes that marine mammals exposed 
to pulsed airgun sounds with received levels >=160 dB re 1 [mu]Pa (rms) 
or continuous sounds from vessel activities with received levels >=120 
dB re 1 [mu]Pa (rms) have the potential to be disturbed. These sound 
level thresholds are currently used by NMFS to define acoustic 
disturbance (harassment) criteria.
(A) Exploration Drilling Activities
    The areas exposed to sounds produced by the drilling units 
Discoverer and Polar Pioneer were determined by measurements from 
drilling in 2012 or were modeled by JASCO Applied Sciences. The 2012 
measurement of the distance to the 120 dB (rms) threshold for normal 
drilling activity by the Discoverer was 0.93 mi (1.5 km) while the 
distance of the >=120 dB (rms) radius during MLC construction was 5.1 
mi (8.2 km).
    Measured sound levels for the Polar Pioneer were not available. Its 
sound footprint was estimated with JASCOs Marine Operations Noise Model 
(MONM) using an average source level derived from a number of reported 
acoustic measurements of comparable semi-submersible drill units, 
including the Ocean Bounty (Gales, 1982), SEDCO 708 (Greene, 1986), and 
Ocean General (McCauley, 1998). The model yielded a propagation range 
of 0.22 mi (0.35 km) for rms sound pressure levels of 120 dB for the 
Polar Pioneer while drilling at the Burger Prospect.
    In addition to drilling and MLC construction, numerous activities 
in support of exploration drilling produce continuous sounds above 120 
dB (rms). These activities in direct support of the moored drilling 
units include ice management, anchor handling, and supply/discharge 
sampling vessels using DP thrusters. Detailed sound characterizations 
for each of these activities are presented in the 2012 Comprehensive 
Report for NMFS' 2012 IHA (LGL et al. 2013).
    The source levels for exploration drilling and related support 
activities are not high enough to cause temporary reduction in hearing 
sensitivity or permanent hearing damage to marine mammals. 
Consequently, mitigation as described for seismic activities including 
ramp ups, power downs, and shut downs should not be necessary for 
exploration drilling activities. However, Shell plans to use PSOs 
onboard the drilling units, ice management, and anchor handling vessels 
to monitor marine mammals and their responses to industry activities, 
in addition to initiating mitigation measures should in-field 
measurements of the activities indicate conditions that may present a 
threat to the health and well-being of marine mammals.
(B) ZVSP Surveys
    Two sound sources have been proposed by Shell for the ZVSP surveys. 
The first is a small airgun array that consists of three 150 in\3\ 
(2,458 cu cm\3\) airguns for a total volume of 450 in\3\

[[Page 11753]]

(7,374 cm\3\). The second ZVSP sound source consists of two 250 in\3\ 
(4,097 cm\3\) airguns with a total volume of 500 in\3\ (8,194 cm\3\). 
Sound footprints of the ZVSP airgun array configurations were estimated 
using JASCO Applied Sciences' Marine Operations Noise Model (MONM). The 
model results were maximized over all water depths between 9.9 and 23 
ft (3 and 7 m) to yield sound level isopleths as a function of range 
and direction from the source. The 450 in\3\ airgun array at a source 
depth of 23 ft (7 m) yielded the maximum ranges to the >=190, >=180, 
and >=160 dB (rms) isopleths. The estimated 95th percentile distances 
to these thresholds were: 190 dB = 558 ft (170 m), 180 dB = 3,018 ft 
(920 m), and 160 dB = 39,239 ft (11,960 m). These distances were 
multiplied by 1.5 as a conservative measure, and the resulting radii 
are shown in Table 1.
    PSOs on the drilling units will initially use the radii in Table 1 
for monitoring and mitigation purposes during ZVSP surveys. An 
acoustics contractor will perform direct measurements of the received 
levels of underwater sound versus distance and direction from the ZVSP 
array using calibrated hydrophones. The acoustic data will be analyzed 
as quickly as reasonably practicable and used to verify (and if 
necessary adjust) the threshold radii distances during later ZVSP 
surveys. The mitigation measures to be implemented will include pre-
ramp up watches, ramp ups, power downs and shut downs as described 
below.

    Table 1--Estimated Distances of the >=190, 180, and 160, dB (rms)
 Isopleths To Be Used for Mitigation Purposes During ZVSP Surveys Until
                        SSV Results Are Available
------------------------------------------------------------------------
                                                              Estimated
          Threshold levels in dB re 1 [mu]Pa (rms)             distance
                                                                 (m)
------------------------------------------------------------------------
>=190......................................................          255
>=180......................................................        1,380
>=160......................................................       11,960
------------------------------------------------------------------------

(2) Ramp Ups
    A ramp up of an airgun array provides a gradual increase in sound 
levels, and involves a step-wise increase in the number and total 
volume of airguns firing until the full volume is achieved. The purpose 
of a ramp up (or ``soft start'') is to ``warn'' cetaceans and pinnipeds 
in the vicinity of the airguns and to provide time for them to leave 
the area, thus avoiding any potential injury or impairment of their 
hearing abilities.
    During the proposed ZVSP surveys, the operator will ramp up the 
airgun arrays slowly. Full ramp ups (i.e., from a cold start when no 
airguns have been firing) will begin by firing a single airgun in the 
array. A full ramp up will not begin until there has been observation 
of the exclusion zone by PSOs for a minimum of 30 minutes to ensure 
that no marine mammals are present. The entire exclusion zones must be 
visible during the 30 minutes leading into to a full ramp up. If the 
entire exclusion zone is not visible, a ramp up from a cold start 
cannot begin. If a marine mammal is sighted within the relevant 
exclusion zone during the 30 minutes prior to ramp up, ramp up will be 
delayed until the marine mammal is sighted outside of the exclusion 
zone or is not sighted for at least 15-30 minutes: 15 minutes for small 
odontocetes and pinnipeds, or 30 minutes for baleen whales and large 
odontocetes.
(3) Power Downs and Shut Downs
    A power down is the immediate reduction in the number of operating 
energy sources from all firing to some smaller number. A shut down is 
the immediate cessation of firing of all energy sources. The arrays 
will be immediately powered down whenever a marine mammal is sighted 
approaching close to or within the applicable exclusion zone of the 
full arrays, but is outside the applicable exclusion zone of the single 
source. If a marine mammal is sighted within the applicable exclusion 
zone of the single energy source, the entire array will be shut down 
(i.e., no sources firing).

Mitigation Conclusions

    NMFS has carefully evaluated the applicant's proposed mitigation 
measures and considered a range of other measures in the context of 
ensuring that NMFS prescribes the means of effecting the least 
practicable impact on the affected marine mammal species and stocks and 
their habitat. Our evaluation of potential measures included 
consideration of the following factors in relation to one another:
    <bullet> The manner in which, and the degree to which, the 
successful implementation of the measure is expected to minimize 
adverse impacts to marine mammals,
    <bullet> The proven or likely efficacy of the specific measure to 
minimize adverse impacts as planned, and
    <bullet> The practicability of the measure for applicant 
implementation.
    Any mitigation measure(s) prescribed by NMFS should be able to 
accomplish, have a reasonable likelihood of accomplishing (based on 
current science), or contribute to the accomplishment of one or more of 
the general goals listed below:
    1. Avoidance or minimization of injury or death of marine mammals 
wherever possible (goals 2, 3, and 4 may contribute to this goal).
    2. A reduction in the numbers of marine mammals (total number or 
number at biologically important time or location) exposed to received 
levels of noises generated from exploration drilling and associated 
activities, or other activities expected to result in the take of 
marine mammals (this goal may contribute to 1, above, or to reducing 
harassment takes only).
    3. A reduction in the number of times (total number or number at 
biologically important time or location) individuals would be exposed 
to received levels of noises generated from exploration drilling and 
associated activities, or other activities expected to result in the 
take of marine mammals (this goal may contribute to 1, above, or to 
reducing harassment takes only).
    4. A reduction in the intensity of exposures (either total number 
or number at biologically important time or location) to received 
levels of noises generated from exploration drilling and associated 
activities, or other activities expected to result in the take of 
marine mammals (this goal may contribute to a, above, or to reducing 
the severity of harassment takes only).
    5. Avoidance or minimization of adverse effects to marine mammal 
habitat, paying special attention to the food base, activities that 
block or limit passage to or from biologically important areas, 
permanent destruction of habitat, or temporary destruction/disturbance 
of habitat during a biologically important time.
    6. For monitoring directly related to mitigation--an increase in 
the probability of detecting marine mammals, thus allowing for more 
effective implementation of the mitigation.
    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 of 
effecting the least practicable impact on marine mammals species or 
stocks and their habitat, paying particular attention to rookeries, 
mating grounds, and areas of similar significance.
    Proposed measures to ensure availability of such species or stock 
for

[[Page 11754]]

taking for certain subsistence uses are discussed later in this 
document (see ``Impact on Availability of Affected Species or Stock for 
Taking for Subsistence Uses'' section).

Proposed Monitoring and Reporting

    In order to issue an ITA for an activity, section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth, ``requirements pertaining to 
the monitoring and reporting of such taking.'' The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for ITAs 
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. 
Shell submitted a marine mammal monitoring plan as part of the IHA 
application. It can be found in Appendix B of the Shell's IHA 
application. The plan may be modified or supplemented based on comments 
or new information received from the public during the public comment 
period or from the peer review panel (see the ``Monitoring Plan Peer 
Review'' section later in this document).
    Monitoring measures prescribed by NMFS should accomplish one or 
more of the following general goals:
    1. An increase in the probability of detecting marine mammals, both 
within the mitigation zone (thus allowing for more effective 
implementation of the mitigation) and in general to generate more data 
to contribute to the analyses mentioned below;
    2. An increase in our understanding of how many marine mammals are 
likely to be exposed to levels of noises generated from exploration 
drilling and associated activities that we associate with specific 
adverse effects, such as behavioral harassment, TTS, or PTS;
    3. An increase in our understanding of how marine mammals respond 
to stimuli expected to result in take and how anticipated adverse 
effects on individuals (in different ways and to varying degrees) may 
impact the population, species, or stock (specifically through effects 
on annual rates of recruitment or survival) through any of the 
following methods:
    [ssquf] Behavioral observations in the presence of stimuli compared 
to observations in the absence of stimuli (need to be able to 
accurately predict received level, distance from source, and other 
pertinent information);
    [ssquf] Physiological measurements in the presence of stimuli 
compared to observations in the absence of stimuli (need to be able to 
accurately predict received level, distance from source, and other 
pertinent information);
    [ssquf] Distribution and/or abundance comparisons in times or areas 
with concentrated stimuli versus times or areas without stimuli;
    4. An increased knowledge of the affected species; and
    5. An increase in our understanding of the effectiveness of certain 
mitigation and monitoring measures.

Proposed Monitoring Measures

1. Protected Species Observers
    Vessel based monitoring for marine mammals will be done by trained 
PSOs on both drilling units and ice management and anchor handler 
vessels throughout the exploration drilling activities. The observers 
will monitor the occurrence and behavior of marine mammals near the 
drilling units, ice management and anchor handling vessels, during all 
daylight periods during the exploration drilling operation, and during 
most periods when exploration drilling is not being conducted. PSO 
duties will include watching for and identifying marine mammals; 
recording their numbers, distances, and reactions to the exploration 
drilling activities; and documenting exposures to sound levels that may 
constitute harassment as defined by NMFS. PSOs will help ensure that 
the vessel communicates with the Communications and Call Centers (Com 
Centers) in Native villages along the Chukchi Sea coast.
(A) Number of Observers
    A sufficient number of PSOs will be onboard to meet the following 
criteria:
    <bullet> 100 percent monitoring coverage during all periods of 
exploration drilling operations in daylight;
    <bullet> Maximum of four consecutive hours on watch per PSO; and
    <bullet> Maximum of approximately 12 hours on watch per day per 
PSO.
    PSO teams will consist of trained Alaska Natives and field 
biologist observers. An experienced field crew leader will be on every 
PSO team aboard the drilling units, ice management and anchor handling 
vessels, and other support vessels during the exploration drilling 
program. The total number of PSOs aboard may decrease later in the 
season as the duration of daylight decreases.
(B) Crew Rotation
    Shell anticipates that there will be provisions for crew rotation 
at least every three to six weeks to avoid observer fatigue. During 
crew rotations detailed notes will be provided to the incoming crew 
leader. Other communications such as email, fax, and/or phone 
communication between the current and oncoming crew leaders during each 
rotation will also occur when necessary. In the event of an unexpected 
crew change Shell will facilitate such communications to insure 
monitoring consistency among shifts.
(C) Observer Qualifications and Training
    Crew leaders serving as PSOs will have experience from one or more 
projects with operators in Alaska or the Canadian Beaufort.
    Biologist-observers will have previous PSO experience, and crew 
leaders will be highly experienced with previous vessel based marine 
mammal monitoring projects. Resumes for those individuals will be 
provided to the NMFS for approval. All PSOs will be trained and 
familiar with the marine mammals of the area. A PSO handbook, adapted 
for the specifics of the planned Shell drilling program, will be 
prepared and distributed beforehand to all PSOs.
    PSOs will also complete a two-day training and refresher session on 
marine mammal monitoring, to be conducted shortly before the 
anticipated start of the drilling season. The training sessions will be 
conducted by marine mammalogists with extensive crew leader experience 
from previous vessel based seismic monitoring programs in the Arctic.
    Primary objectives of the training include:
    <bullet> Review of the 4MP for this project, including any 
amendments adopted or specified by NMFS in the final IHA or other 
agreements in which Shell may elect to participate;
    <bullet> Review of marine mammal sighting, identification, 
(photographs and videos) and distance estimation methods, including any 
amendments specified by NMFS in the IHA (if issued);
    <bullet> Review operation of specialized equipment (e.g., reticle 
binoculars, big eye binoculars, night vision devices, GPS system); and
    <bullet> Review of data recording and data entry systems, including 
procedures for recording data on mammal sightings, exploration drilling 
and monitoring activities, environmental conditions, and entry error 
control. These procedures will be implemented through use of a 
customized computer databases and laptop computers.
(D) PSO Handbook
    A PSO Handbook will be prepared for Shell's monitoring program. The

[[Page 11755]]

Handbook will contain maps, illustrations, and photographs as well as 
copies of important documents and descriptive text and are intended to 
provide guidance and reference information to trained individuals who 
will participate as PSOs. The following topics will be covered in the 
PSO Handbook:
    <bullet> Summary overview descriptions of the project, marine 
mammals and underwater sound energy, the 4MP (vessel-based, aerial, 
acoustic measurements, special studies), the IHA (if issued) and other 
regulations/permits/agencies, the Marine Mammal Protection Act;
    <bullet> Monitoring and mitigation objectives and procedures, 
including initial exclusion and disturbance zones;
    <bullet> Responsibilities of staff and crew regarding the 4MP;
    <bullet> Instructions for staff and crew regarding the 4MP;
    <bullet> Data recording procedures: codes and coding instructions, 
common coding mistakes, electronic database; navigational, marine 
physical, and drilling data recording, field data sheet;
    <bullet> Use of specialized field equipment (e.g., reticle 
binoculars, Big-eye binoculars, NVDs, laser rangefinders);
    <bullet> Reticle binocular distance scale;
    <bullet> Table of wind speed, Beaufort wind force, and sea state 
codes;
    <bullet> Data storage and backup procedures;
    <bullet> List of species that might be encountered: identification, 
natural history;
    <bullet> Safety precautions while onboard;
    <bullet> Crew and/or personnel discord; conflict resolution among 
PSOs and crew;
    <bullet> Drug and alcohol policy and testing;
    <bullet> Scheduling of cruises and watches;
    <bullet> Communications;
    <bullet> List of field gear provided;
    <bullet> Suggested list of personal items to pack;
    <bullet> Suggested literature, or literature cited;
    <bullet> Field reporting requirements and procedures;
    <bullet> Copies of the IHA will be made available; and
    <bullet> Areas where vessels need permission to operate such as the 
Ledyard Bay Critical Habitat Unit (LBCHU).
2. Vessel-Based Monitoring Methodology
    The observer(s) will watch for marine mammals from the best 
available vantage point on the drilling units and support vessels. 
Ideally this vantage point is an elevated stable platform from which 
the PSO has an unobstructed 360o view of the water. The observer(s) 
will scan systematically with the naked eye and 7 x 50 reticle 
binoculars, supplemented with Big-eye binoculars and night-vision 
equipment when needed. Personnel on the bridge will assist the marine 
mammal observer(s) in watching for pinnipeds and cetaceans. New or 
inexperienced PSOs will be paired with an experienced PSO or 
experienced field biologist so that the quality of marine mammal 
observations and data recording is kept consistent.
    Information to be recorded by marine mammal observers will include 
the same types of information that were recorded during previous 
monitoring projects (e.g., Moulton and Lawson 2002; Reiser et al. 2010, 
2011; Bisson et al. 2013). When a mammal sighting is made, the 
following information about the sighting will be carefully and 
accurately recorded:
    <bullet> Species, group size, age/size/sex categories (if 
determinable), physical description of features that were observed or 
determined not to be present in the case of unknown or unidentified 
animals;
    <bullet> Behavior when first sighted and after initial sighting;
    <bullet> Heading (if consistent), bearing and distance from 
observer;
    <bullet> Apparent reaction to activities (e.g., none, avoidance, 
approach, paralleling, etc.), closest point of approach, and behavioral 
pace;
    <bullet> Time, location, speed, and activity of the vessel, sea 
state, ice cover, visibility, and sun glare, on support vessels the 
distance and bearing to the drilling unit will also be recorded; and
    <bullet> Positions of other vessel(s) in the vicinity of the 
observer 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.
    Distances to nearby marine mammals will be estimated with 
binoculars (Fujinon 7 x 50 binoculars) containing a reticle to measure 
the vertical angle of the line of sight to the animal relative to the 
horizon.
    An electronic database will be used to record and collate data 
obtained from visual observations during the vessel-based study. The 
PSOs will enter the data into the custom data entry program installed 
on field laptops. The data entry program automates the data entry 
process and reduces data entry errors and maximizes PSO time spent 
looking at the water. PSOs also have voice recorders available to them. 
This is another tool that will allow PSOs to maximize time spent 
focused on the water.
    PSO's are instructed to identify animals as unknown when 
appropriate rather than strive to identify an animal when there is 
significant uncertainty. PSOs should also provide any sightings cues 
they used and any distinguishable features of the animal even if they 
are not able to identify the animal and record it as unidentified. 
Emphasis will also be placed on recording what was not seen, such as 
dorsal features.
(A) Monitoring at Night and in Poor Visibility
    Night-vision equipment ``Generation 3'' binocular image 
intensifiers or equivalent units will be available for use when needed. 
However, past experience with night-vision devices (NVDs) in the 
Beaufort Sea and elsewhere indicates that NVDs are not nearly as 
effective as visual observation during daylight hours (e.g., Harris et 
al. 1997, 1998; Moulton and Lawson 2002; Hartin et al. 2013).
(B) Specialized Field Equipment
    Shell will provide the following specialized field equipment for 
use by the onboard PSOs: reticle binoculars, Big-eye binoculars, GPS 
unit, laptop computers, night vision binoculars, and possibly digital 
still and digital video cameras. Big eye binoculars will be mounted and 
used on key monitoring vessels including the drilling units, ice 
management vessels and the anchor handler.
(C) Field Data-Recording, Verification, Handling, and Security
    The observers on the drilling units and support vessels will record 
their observations directly into computers using a custom software 
package. The accuracy of the data entry will be verified in the field 
by computerized validity checks as the data are entered, and by 
subsequent manual checking. These procedures will allow initial 
summaries of data to be prepared during and shortly after the field 
season, and will facilitate transfer of the data to statistical, 
graphical or other programs for further processing. Quality control of 
the data will be facilitated by (1) the start-of-season training 
session, (2) subsequent supervision by the onboard field crew leader, 
and (3) ongoing data checks during the field season.
    The data will be sent off of the vessel to Anchorage on a daily 
basis and backed up regularly onto storage devices on the vessel, and 
stored at separate locations on the vessel. If practicable, hand-
written data sheets will be photocopied daily during the field season. 
Data will be secured further by

[[Page 11756]]

having data sheets and backup data devices carried back to the 
Anchorage office during crew rotations.
    In addition to routine PSO duties, observers will be encouraged to 
record comments about their observations into the ``comment'' field in 
the database. Copies of these records will be available to the 
observers for reference if they wish to prepare a statement about their 
observations. If prepared, this statement would be included in the 90-
day and comprehensive reports documenting the monitoring work.
    PSOs will be able to plot sightings in near real-time for their 
vessel. Significant sightings from key vessels including drilling 
units, ice management, anchor handlers and aircraft will be relayed 
between platforms to keep observers aware of animals that may be in or 
near the area but may not be visible to the observer at any one time. 
Emphasis will be placed on relaying sightings with the greatest 
potential to involve mitigation or reconsideration of a vessel's course 
(e.g., large group of bowheads).
    Observer training will emphasize the use of ``comments'' for 
sightings that may be considered unique or not fully captured by 
standard data codes. In addition to the standard marine mammal 
sightings forms, a specialized form was developed for recording 
traditional knowledge and natural history observations. PSOs will be 
encouraged to use this form to capture observations related to any 
aspect of the arctic environment and the marine mammals found within 
it. Examples might include relationships between ice and marine mammal 
sightings, marine mammal behaviors, comparisons of observations among 
different years/seasons, etc. Voice recorders will also be available 
for observers to use during periods when large numbers of animals may 
be present and it is difficult to capture all of the sightings on 
written or digital forms. These recorders can also be used to capture 
traditional knowledge and natural history observations should 
individuals feel more comfortable using the recorders rather than 
writing down their comments. Copies of these records will be available 
to all observers for reference if they wish to prepare a statement 
about their observations for reporting purposes. If prepared, this 
statement would be included in the 90-day and final reports documenting 
the monitoring work.
3. Acoustic Monitoring Plan
Exploration Drilling, ZVSP, and Vessel Noise Measurements
    Exploration drilling sounds are expected to vary significantly with 
time due to variations in the level of operations and the different 
types of equipment used at different times onboard the drilling units. 
The goals of these measurements are:
    <bullet> To quantify the absolute sound levels produced by 
exploration drilling and to monitor their variations with time, 
distance and direction from the drilling unit;
    <bullet> To measure the sound levels produced by vessels while 
operating in direct support of exploration drilling operations. These 
vessels will include crew change vessels, tugs, ice-management vessels, 
and spill response vessels not measured in 2012; and
    <bullet> To measure the sound levels produced by an end-of-hole 
zero-offset vertical seismic profile (ZVSP) survey using a stationary 
sound source.
    Sound characterization and measurements of all exploration drilling 
activities will be performed using five Autonomous Multichannel 
Acoustic Recorders (AMAR) deployed on the seabed along the same radial 
at distances of 0.31, 0.62, 1.2, 2.5 and 5 mi (0.5,1, 2, 4 and 8 km) 
from each drilling unit. All five recording stations will sample at 
least at 32 kHz, providing calibrated acoustic measurements in the 5 Hz 
to 16 kHz frequency band. The logarithmic spacing of the recorders is 
designed to sample the attenuation of drilling unit sounds with 
distance. The autonomous recorders will sample through completion of 
the first well, to provide a detailed record of sounds emitted from all 
activities. These recorders will be retrieved and their data analyzed 
and reported in the project's 90-day report.
    The deployment of drilling sound monitoring equipment will occur 
before, or as soon as possible after the Discoverer and the Polar 
Pioneer are on site. Activity logs of exploration drilling operations 
and nearby vessel activities will be maintained to correlate with these 
acoustic measurements. All results, including back-propagated source 
levels for each operation, will be reported in the 90-day report.
(A) Vessel Sound Characterization
    Vessel sound characterizations will be performed using dedicated 
recorders deployed at sufficient distances from exploration drilling 
operations so that sound produced by those activities does not 
interfere. Three AMAR acoustic recorders will be deployed on and 
perpendicular to a sail track on which all Shell contracted vessels 
will transit. This geometry is designed to obtain sound level 
measurements as a function of distance and direction. The fore and aft 
directions are sampled continuously over longer distances to 3 and 6 
miles (5 and 10 km) respectively, while broadside and other directions 
are sampled as the vessels pass closer to the recorders.
    Vessel sound measurements will be processed and reported in a 
manner similar to that used by Shell and other operators in the 
Beaufort and Chukchi Seas during seismic survey operations. The 
measurements will further be analyzed to calculate source levels. 
Source directivity effects will be examined and reported. Preliminary 
vessel characterization measurements will be reported in a field report 
to be delivered 120 hours after the recorders are retrieved and data 
downloaded. Those results will include sound level data but not source 
level calculations. All vessel characterization results, including 
source levels, will be reported in 1/3-octave bands in the project 90-
day report.
(B) Zero-Offset Vertical Seismic Profiling Sound Monitoring
    Shell states that it may conduct a geophysical survey referred to 
as a zero-offset vertical seismic profile, or ZVSP, at two drill sites 
in 2015. During ZVSP surveys, an airgun array, which is much smaller 
than those used for routine seismic surveys, is deployed at a location 
near or adjacent to the drilling unit, while receivers are placed 
(temporarily anchored) in the wellbore. The sound source (airgun array) 
is fired repeatedly, and the reflected sonic waves are recorded by 
receivers (geophones) located in the wellbore. The geophones, typically 
a string of them, are then raised up to the next interval in the 
wellbore and the process is repeated until the entire wellbore has been 
surveyed. The purpose of the ZVSP survey is to gather geophysical 
information at various depths in the wellbore, which can then be used 
to tie-in or ground truth geophysical information from the previously 
collected 2D and 3D seismic surveys with geological data collected 
within the wellbore.
    Shell will conduct a ZVSP surveys in which the sound source is 
maintained at a constant location near the wellbore. Two sound sources 
have been proposed by Shell for the ZVSP surveys in 2015. The first is 
a small airgun array that consists of three 150 in\3\ (2,458 cu cm\3\) 
airguns for a total volume of 450 in\3\ (7,374 cm\3\). The second ZVSP 
sound

[[Page 11757]]

source consists of two 250 in\3\ (4,097 cu cm\3\) airguns with a total 
volume of 500 in\3\ (8,194 cm\3\).
    A ZVSP survey is typically conducted at each well after total depth 
is reached but may be conducted at a shallower depth. For each survey, 
the sound source (airgun array) would be deployed over the side of the 
Discoverer or the Polar Pioneer with a crane. The sound source will be 
positioned 50-200ft (15-61 m) from the wellhead (depending on crane 
location), at a depth of ~10-23ft (3-7 m) below the water surface. 
Receivers will be temporarily anchored in the wellbore at depth. The 
sound source will be pressured up to 3,000 pounds per square inch 
(psi), and activated 5-7 times at approximately 20-second intervals. 
The receivers will then be moved to the next interval of the wellbore 
and re-anchored, after which the airgun array will again be activated 
5-7 times. This process will be repeated until the entire wellbore has 
been surveyed in this manner. The interval between anchor points for 
the receiver array is usually 200-300ft (61-91 m). A typical ZVSP 
survey takes about 10-14 hours to complete per well (depending on the 
depth of the well and the number of anchoring points in each well).
    ZVSP sound verification measurements will be performed using either 
the AMARs that are deployed for drilling unit sound characterizations, 
or by JASCO Ocean Bottom Hydrophone (OBH) recorders. The use of AMARS 
or OBHs depends on the specific timing these measurements will be 
required by NMFS; the AMARs will not be retrieved until several days 
after the ZVSP as they are intended to monitor during retrievals of 
drilling unit anchors and related support activities. If the ZVSP 
acoustic measurements are required sooner, four OBH recorders would be 
deployed at the same locations and those could be retrieved immediately 
following the ZVSP measurement. The ZVSP measurements can be delivered 
within 120 hours of retrieval and download of the data from either 
instrument type.
(C) Acoustic Data Analyses
    Exploration drilling sound data will be analyzed to extract a 
record of the frequency-dependent sound levels as a function of time. 
These results are useful for correlating measured sound energy events 
with specific survey operations. The analysis provides absolute sound 
levels in finite frequency bands that can be tailored to match the 
highest-sensitivity hearing ranges for species of interest. The 
analyses will also consider sound level integrated through 1-hour 
durations (referred to as sound energy equivalent level Leq (1-hour). 
Similar graphs for long time periods will be generated as part of the 
data analysis performed for indicating drilling sound variation with 
time in selected frequency bands.
(D) Reporting of Results
    Acoustic sound level results will be reported in the 90-day and 
comprehensive reports for this program. The results reported will 
include:
    <bullet> Sound source levels for the drilling units and all 
drilling support vessels;
    <bullet> Spectrogram and band level versus time plots computed from 
the continuous recordings obtained from the hydrophone systems;
    <bullet> Hourly Leq levels at the hydrophone locations; and
    <bullet> Correlation of exploration drilling source levels with the 
type of exploration drilling operation being performed. These results 
will be obtained by observing differences in drilling sound associated 
with differences in drilling unit activities as indicated in detailed 
drilling unit logs.

Acoustic ``Net'' Array in Chukchi Sea

    This section describes acoustic studies that were undertaken from 
2006 through 2013 in the Chukchi Sea as part of the Joint Monitoring 
Program and that will be continued by Shell during exploration drilling 
activities. The acoustic ``net'' array used during the 2006-2013 field 
seasons in the Chukchi Sea was designed to accomplish two main 
objectives. The first was to collect information on the occurrence and 
distribution of marine mammals (including beluga whale, bowhead whale, 
and other species) that may be available to subsistence hunters near 
villages along the Chukchi Sea coast and to document their relative 
abundance, habitat use, and migratory patterns. The second objective 
was to measure the ambient soundscape throughout the eastern Chukchi 
Sea and to record received levels of sounds from industry and other 
activities further offshore in the Chukchi Sea.
    A net array configuration similar to that deployed in 2007-2013 is 
again proposed. The basic components of this effort consist of 
autonomous acoustic recorders deployed widely across the U.S. Chukchi 
Sea during the open water season and then more limited arrays during 
the winter season. These calibrated systems sample at 16 kHz with 24-
bit resolution, and are capable of recording marine mammal sounds and 
making anthropogenic noise measurements. The net array configuration 
will include a regional array of 23 AMAR recorders deployed July-
October off the four main transect locations: Cape Lisburne, Point Lay, 
Wainwright and Barrow. All of these offshore systems will capture 
sounds associated with exploration drilling, where present, over large 
distances to help characterize the sound transmission properties in the 
Chukchi Sea. Six additional summer AMAR recorders will be deployed 
around the Burger drill sites to monitor directional variations and 
longer-range propagation of drilling-related sounds. These recorders 
will also be used to examine marine mammal vocalization patterns in 
vicinity of exploration drilling activities. The regional recorders 
will be retrieved in early October 2015; acoustic monitoring will 
continue through the winter with 8 AMAR recorders deployed October 
2015-August 2016. The winter recorders will sample at 16 kHz on a 17% 
duty cycle (40 minutes every 4 hours). The winter recorders deployed in 
previous years have provided important information about fall and 
spring migrations of bowhead, beluga, walrus and several seal species.
    The Chukchi acoustic net array will produce an extremely large 
dataset comprising several Terabytes of acoustic data. The analyses of 
these data require identification of marine mammal vocalizations. 
Because of the very large amount of data to be processed, the analysis 
methods will incorporate automated vocalization detection algorithms 
that have been developed over several years. While the hydrophones used 
in the net array are not directional, and therefore not capable of 
accurate localization of detections, the number of vocalizations 
detected on each of the sensors provides a measure of the relative 
spatial distribution of some marine mammal species, assuming that 
vocalization patterns are consistent within a species across the 
spatial and geographic distribution of the hydrophone array. These 
results therefore provide information such as timing of migrations and 
routes of migration for belugas and bowheads.
    A second purpose of the Chukchi net array is to monitor the 
amplitude of exploration drilling sound propagation over a very large 
area. It is expected that sounds from exploratory drilling activities 
will be detectable on hydrophone systems within approximately 30 km of 
the drilling units when ambient sound energy conditions are low. The 
drilling sound levels at recorder locations will be quantified and 
reported.
    Analysis of all acoustic data will be prioritized to address the 
primary questions. The primary data analysis

[[Page 11758]]

questions are to (a) determine when, where, and what species of animals 
are acoustically detected on each recorder (b) analyze data as a whole 
to determine offshore distributions as a function of time, (c) quantify 
spatial and temporal variability in the ambient sound energy, and (d) 
measure received levels of exploration drilling survey events and 
drilling unit activities. The detection data will be used to develop 
spatial and temporal animal detection distributions. Statistical 
analyses will be used to test for changes in animal detections and 
distributions as a function of different variables (e.g., time of day, 
season, environmental conditions, ambient sound energy, and drilling or 
vessel sound levels).
4. Chukchi Offshore Aerial Photographic Monitoring Program
    Shell has been reticent to conduct manned aerial surveys in the 
offshore Chukchi Sea because conducting those surveys puts people at 
risk. There is a strong desire, however, to obtain data on marine 
mammal distribution in the offshore Chukchi Sea and Shell will conduct 
a photographic aerial survey that would put fewer people at risk as an 
alternative to the fully-manned aerial survey. The photographic survey 
would reduce the number of people on board the aircraft from six 
persons to two persons (the pilot and copilot) and would serve as a 
pilot study for future surveys that would use an Unmanned Aerial System 
(UAS) to capture the imagery.
    Aerial photographic surveys have been used to monitor distribution 
and estimate densities of marine mammals in offshore areas since the 
mid-1980s, and before that, were used to estimate numbers of animals in 
large concentration areas. Digital photographs provide many advantages 
over observations made by people if the imagery has sufficient 
resolution (Koski et al. 2013). With photographs there is constant 
detectability across the imagery, whereas observations by people 
decline with distance from the center line of the survey area. 
Observations at the outer limits of the transect can decline to 5-10% 
of the animals present for real-time observations by people during an 
aerial survey. The distance from the trackline of sightings is more 
accurately determined from photographs; group size can be more 
accurately determined; and sizes of animals can be measured, and hence 
much more accurately determined, in photographs. As a result of the 
latter capability, the presence or absence of a calf can be more 
accurately determined from a photograph than by in-the-moment visual 
observations. Another benefit of photographs over visual observations 
is that photographs can be reviewed by more than one independent 
observer allowing quantification of detection, identification and group 
size biases.
    The proposed photographic survey will provide imagery that can be 
used to evaluate the ability of future studies to use the same image 
capturing systems in an UAS where people would not be put at risk. 
Although the two platforms are not the same, the slower airspeed and 
potentially lower flight altitude of the UAS would mean that the data 
quality would be better from the UAS. Initial comparisons have been 
made between data collected by human observers on board both the 
Chukchi and Beaufort aerial survey aircraft and the digital imagery 
collected in 2012. Overall, the imagery provided better estimates of 
the number of large cetaceans and pinnipeds present but fewer sightings 
were identified to species in the imagery than by PSOs, because the 
PSOs had sightings in view for a longer period of time and could use 
behavior to differentiate species. The comparisons indicated that some 
cetaceans that were not seen by PSOs were detected in the imagery; 
errors in identification were made by the PSOs during the survey that 
could be resolved from examination of the imagery; cetaceans seen by 
PSOs were visible in the imagery; and during periods with large numbers 
of sightings, the imagery provided much better estimates of numbers of 
sightings and group size than the PSO data.
    Photographic surveys would start as soon as the ice management, 
anchor handler and drilling units are at or near the first drill site 
and would continue throughout the drilling period and until the 
drilling related vessels have left the exploration drilling area. Since 
the current plans are for vessels to enter the Chukchi Sea on or about 
1 July, surveys would be initiated on or about 3 July. This start date 
differs from past practices of beginning five days prior to initiation 
of an activity and continuing until five days after cessation of the 
activity because the presence of vessels with helidecks in the area 
where overflights will occur is one of the main mitigations that will 
allow for safe operation of the overflight program this far offshore. 
The surveys will be based out of Barrow and the same aircraft will 
conduct the offshore surveys around the drilling units and the coastal 
saw-tooth pattern. The surveys of offshore areas around the drilling 
units will take precedence over the sawtooth survey, but if weather 
does not permit surveying offshore, the nearshore survey will be 
conducted if weather permits.
    The aerial survey grids are designed to maximize coverage of the 
sound level fields of the drilling units during the different 
exploratory drilling activities. The survey grids can be modified as 
necessary based on weather and whether a noisy activity or quiet 
activity is taking place. The intensive survey design maximizes the 
effort over the area where sound levels are highest. The outer survey 
grid covers an elliptical area with a 45 km radius near the center of 
the ellipse. The spacing of the outer survey lines is 10 km, and the 
spacing between the intensive and outer lines is 5 km. The expanded 
survey grid covers a larger survey area, and the design is based on an 
elliptical area with a 50 km radius centered on the well sties. For 
both survey designs the main transects will be spaced 10 km apart which 
will allow even coverage of the survey area during a single flight if 
weather conditions permit completion of a survey. A random starting 
point will be selected for each survey and the evenly spaced lines will 
be shifted NE or SW along the perimeter of the elliptical survey area 
based on the start point. The total length of survey lines will be 
about 1,000 km and the exact length will depend on the location of the 
randomly selected start point.
    Following each survey, the imagery will be downloaded from the 
memory card to a portable hard drive and then backed up on a second 
hard drive and stored at accommodations in Barrow until the second hard 
drive can be transferred to Anchorage. In Anchorage, the imagery will 
be processed through a computer-assisted analysis program to identify 
where marine mammal sightings might be located among the many images 
obtained. A team of trained photo analysts will review the photographs 
identified as having potential sightings and record the appropriate 
data on each sighting. If time permits, a second review of some of the 
images will be conducted while in the field, but the sightings recorded 
during the second pass will be identified in the database as secondary 
sightings, so that biases associated with the detection in the imagery 
can be quantified. If time does not permit that review to be conducted 
while in the field, the review will be conducted by personnel in the 
office during or after the field season. A sample of images that are 
not identified by the computer-assisted analysis program will be 
examined in detail by the image analysts to determine if the program 
has missed marine mammal sightings. If the analysis program has missed 
mammal

[[Page 11759]]

sightings, these data will be to develop correction factors to account 
for these missed sightings among the images that were not examined.
5. Chukchi Sea Coastal Aerial Survey
    Nearshore aerial surveys of marine mammals in the Chukchi Sea were 
conducted over coastal areas to approximately 23 miles (mi) [37 
kilometers (km)] offshore in 2006-2008 and in 2010 in support of 
Shell's summer seismic exploration activities. In 2012 these surveys 
were flown when it was not possible to fly the photographic transects 
out over the Burger well site due to weather or rescue craft 
availability. These surveys provided data on the distribution and 
abundance of marine mammals in nearshore waters of the Chukchi Sea. 
Shell plans to conduct these nearshore aerial surveys in the Chukchi 
Sea as opportunities unfold and surveys will be similar to those 
conducted during previous years except that no PSOs will be onboard the 
aircraft. As noted above, the first priority will be to conduct 
photographic surveys around the offshore exploration drilling 
activities, but nearshore surveys will be conducted whenever weather 
does not permit flying offshore. As in past years, surveys in the 
southern part of the nearshore survey area will depend on the end of 
the beluga hunt near Point Lay. In past years, Point Lay has requested 
that aerial surveys not be conducted until after the beluga hunt has 
ended and so the start of surveys has been delayed until mid-July.
    Alaskan Natives from villages along the east coast of the Chukchi 
Sea hunt marine mammals during the summer and Native communities are 
concerned that offshore oil and gas exploration activities may 
negatively impact their ability to harvest marine mammals. Of 
particular concern are potential impacts on the beluga harvest at Point 
Lay and on future bowhead harvests at Point Hope, Point Lay, Wainwright 
and Barrow. Other species of concern in the Chukchi Sea include the 
gray whale; bearded, ringed, and spotted seals. Gray whale and harbor 
porpoise are expected to be the most numerous cetacean species 
encountered during the proposed aerial survey; although harbor porpoise 
are abundant they are difficult to detect from aircraft because of 
their small size and brief surfacing. Beluga whales may occur in high 
numbers early in the season. The ringed seal is likely to be the most 
abundant pinniped species. The current aerial survey program will be 
designed to collect distribution data on cetaceans but will be limited 
in its ability to collect similar data on pinnipeds and harbor 
porpoises because they are not reliably detectable during review of the 
collected images unless a third camera with a 50 mm or similar lens is 
deployed.
    Transects will be flown in a saw-toothed pattern between the shore 
and 23 mi (37 km) offshore as well as along the coast from Point Barrow 
to Point Hope. This design will permit completion of the survey in one 
to two days and will provide representative coverage of the nearshore 
region. Sawtooth transects were designed by placing transect start/end 
points every 34 mi (55 km) along the offshore boundary of this 23 mi 
(37 km) wide nearshore zone, and at midpoints between those points 
along the coast. The transect line start/end points will be shifted 
along both the coast and the offshore boundary for each survey based 
upon a randomized starting location, but overall survey distance will 
not vary substantially. The coastline transect will simply follow the 
coastline or barrier islands. As with past surveys of the Chukchi Sea 
coast, coordination with coastal villages to avoid disturbance of the 
beluga whale subsistence hunt will be extremely important. ``No-fly'' 
zones around coastal villages or other hunting areas established during 
communications with village representatives will be in place until the 
end of the hunting season.
    Standard aerial survey procedures used in previous marine mammal 
projects (by Shell as well as by others) will be followed. This will 
facilitate comparisons and (as appropriate) pooling with other data, 
and will minimize controversy about the chosen survey procedures. The 
aircraft will be flown at 110-120 knots ground speed and usually at an 
altitude of 1,000 ft (305 m). Aerial surveys at an altitude of 1,000 
ft. (305 m) do not provide much information about seals but are 
suitable for bowhead, beluga, and gray whales. The need for a 1,000+ ft 
(305+ m) or 1,500+ ft (454+ m) cloud ceiling will limit the dates and 
times when surveys can be flown. Selection of a higher altitude for 
surveys would result in a significant reduction in the number of days 
during which surveys would be possible, impairing the ability of the 
aerial program to meet its objectives.
    The surveyed area will include waters where belugas are usually 
available to subsistence hunters. If large concentrations of belugas 
are encountered during the survey, the aircraft will climb to ~10,000 
ft (3,050 m) altitude to avoid disturbing the cetaceans. If cetaceans 
are in offshore areas, the aircraft will climb high enough to include 
all cetaceans within a single photograph; typically about 3,000 ft (914 
m) altitude. When in shallow water, belugas and other marine mammals 
are more sensitive to aircraft over flights and other forms of 
disturbance than when they are offshore (see Richardson et al. 1995 for 
a review). They frequently leave shallow estuaries when over flown at 
altitudes of 2,000-3,000 ft (610-904 m); whereas they rarely react to 
aircraft at 1,500 ft (457 m) when offshore in deeper water.

Monitoring Plan Peer Review

    The MMPA requires that monitoring plans be independently peer 
reviewed ``where the proposed activity may affect the availability of a 
species or stock for taking for subsistence uses'' (16 U.S.C. 
1371(a)(5)(D)(ii)(III)). Regarding this requirement, NMFS' implementing 
regulations state, ``Upon receipt of a complete monitoring plan, and at 
its discretion, [NMFS] will either submit the plan to members of a peer 
review panel for review or within 60 days of receipt of the proposed 
monitoring plan, schedule a workshop to review the plan'' (50 CFR 
216.108(d)).
    NMFS has established an independent peer review panel to review 
Shell's 4MP for Exploration Drilling of Selected Lease Areas in the 
Alaskan Chukchi Sea in 2015. The panel is scheduled to meet in early 
March 2015, and will provide comments to NMFS shortly after they meet. 
After completion of the peer review, NMFS will consider all 
recommendations made by the panel, incorporate appropriate changes into 
the monitoring requirements of the IHA (if issued), and publish the 
panel's findings and recommendations in the final IHA notice of 
issuance or denial document.

Reporting Measures

(1) SSV Report
    A report on the results of the acoustic verification measurements, 
including at a minimum the measured 190-, 180-, 160-, and 120-dB (rms) 
radii of the drilling units, and support vessels, will be reported in 
the 90-day report. A report of the acoustic verification measurements 
of the ZVSP airgun array will be submitted within 120 hr after 
collection and analysis of those measurements once that part of the 
program is implemented. The ZVSP acoustic array report will specify the 
distances of the exclusion zones that were adopted for the ZVSP 
program. Prior to completion of these measurements, Shell will use the 
radii outlined in their application and proposed in Tables 2 and 3 of 
this document.

[[Page 11760]]

(2) Field Reports
    Throughout the exploration drilling program, the biologists will 
prepare a report each day or at such other interval as required 
summarizing the recent results of the monitoring program. The reports 
will summarize the species and numbers of marine mammals sighted. These 
reports will be provided to NMFS as required.
(3) Technical Reports
    The results of Shell's 2015 Chukchi Sea exploratory drilling 
monitoring program (i.e., vessel-based, aerial, and acoustic) will be 
presented in the ``90-day'' and Final Technical reports under the 
proposed IHA. Shell proposes that the Technical Reports will include: 
(1) Summaries of monitoring effort (e.g., total hours, total distances, 
and marine mammal distribution through study period, accounting for sea 
state and other factors affecting visibility and detectability of 
marine mammals); (2) analyses of the effects of various factors 
influencing detectability of marine mammals (e.g., sea state, number of 
observers, and fog/glare); (3) species composition, occurrence, and 
distribution of marine mammal sightings, including date, water depth, 
numbers, age/size/gender categories (if determinable), group sizes, and 
ice cover; (4) sighting rates of marine mammals during periods with and 
without drilling activities (and other variables that could affect 
detectability); (5) initial sighting distances versus drilling state; 
(6) closest point of approach versus drilling state; (7) observed 
behaviors and types of movements versus drilling state; (8) numbers of 
sightings/individuals seen versus drilling state; (9) distribution 
around the drilling units and support vessels versus drilling state; 
and (10) estimates of take by harassment. This information will be 
reported for both the vessel-based and aerial monitoring.
    Analysis of all acoustic data will be prioritized to address the 
primary questions, which are to: (a) Determine when, where, and what 
species of animals are acoustically detected on each AMAR ; (b) analyze 
data as a whole to determine offshore bowhead distributions as a 
function of time; (c) quantify spatial and temporal variability in the 
ambient noise; and (d) measure received levels of drilling unit 
activities. The detection data will be used to develop spatial and 
temporal animal distributions. Statistical analyses will be used to 
test for changes in animal detections and distributions as a function 
of different variables (e.g., time of day, time of season, 
environmental conditions, ambient noise, vessel type, operation 
conditions).
    The initial technical report is due to NMFS within 90 days of the 
completion of Shell's Chukchi Sea exploration drilling program. The 
``90-day'' report will be subject to review and comment by NMFS. Any 
recommendations made by NMFS must be addressed in the final report 
prior to acceptance by NMFS.
(4) Notification of Injured or Dead Marine Mammals
    Shell will be required to notify NMFS' Office of Protected 
Resources and NMFS' Stranding Network of any sighting of an injured or 
dead marine mammal. Based on different circumstances, Shell may or may 
not be required to stop operations upon such a sighting. Shell will 
provide NMFS with the species or description of the animal(s), the 
condition of the animal(s) (including carcass condition if the animal 
is dead), location, time of first discovery, observed behaviors (if 
alive), and photo or video (if available). The specific language 
describing what Shell must do upon sighting a dead or injured marine 
mammal can be found in the ``Proposed Incidental Harassment 
Authorization'' section later in this document.

Estimated Take by Incidental Harassment

    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]. Only take by Level B behavioral 
harassment is anticipated as a result of the proposed drilling program. 
Noise propagation from the drilling units, associated support vessels 
(including during icebreaking if needed), and the airgun array are 
expected to harass, through behavioral disturbance, affected marine 
mammal species or stocks. Additional disturbance to marine mammals may 
result from aircraft overflights and visual disturbance of the drilling 
units or support vessels. However, based on the flight paths and 
altitude, impacts from aircraft operations are anticipated to be 
localized and minimal in nature.
    The full suite of potential impacts to marine mammals from various 
industrial activities was described in detail in the ``Potential 
Effects of the Specified Activity on Marine Mammals'' section found 
earlier in this document. The potential effects of sound from the 
proposed exploratory drilling program without any mitigation might 
include one or more of the following: tolerance; masking of natural 
sounds; behavioral disturbance; non-auditory physical effects; and, at 
least in theory, temporary or permanent hearing impairment (Richardson 
et al., 1995a). As discussed earlier in this document, NMFS estimates 
that Shell's activities will most likely result in behavioral 
disturbance, including avoidance of the ensonified area or changes in 
speed, direction, and/or diving profile of one or more marine mammals. 
For reasons discussed previously in this document, hearing impairment 
(TTS and PTS) is highly unlikely to occur based on the fact that most 
of the equipment to be used during Shell's proposed drilling program 
does not have source levels high enough to elicit even mild TTS and/or 
the fact that certain species are expected to avoid the ensonified 
areas close to the operations. Additionally, non-auditory physiological 
effects are anticipated to be minor, if any would occur at all.
    For continuous sounds, such as those produced by drilling 
operations and during icebreaking activities, NMFS uses a received 
level of 120-dB (rms) to indicate the onset of Level B harassment. For 
impulsive sounds, such as those produced by the airgun array during the 
ZVSP surveys, NMFS uses a received level of 160-dB (rms) to indicate 
the onset of Level B harassment. Shell provided calculations for the 
120-dB isopleths produced by aggregate sources and then used those 
isopleths to estimate takes by harassment. Additionally, Shell provided 
calculations for the 160-dB isopleth produced by the airgun array and 
then used that isopleth to estimate takes by harassment. Shell provides 
a full description of the methodology used to estimate takes by 
harassment in its IHA application (see ADDRESSES), which is also 
provided in the following sections.
    Shell has requested authorization to take bowhead, gray, fin, 
humpback, minke, killer, and beluga whales, harbor porpoise, and 
ringed, spotted, bearded, and ribbon seals incidental to exploration 
drilling, ice management/icebreaking, and ZVSP activities. 
Additionally, Shell provided exposure estimates and requested takes of 
narwhal. However, as stated previously in this document, sightings of 
this species are rare, and the likelihood of occurrence of narwhals in 
the proposed

[[Page 11761]]

drilling area is minimal. Therefore, NMFS is not proposing to authorize 
take of this species.

Basis for Estimating ``Take by Harassment''

    ``Take by Harassment'' is described in this section and was 
calculated in Shell's application by multiplying the expected densities 
of marine mammals that may occur near the exploratory drilling 
operations by the area of water likely to be exposed to continuous, 
non-pulse sounds >=120 dB re 1 [micro]Pa (rms) during drilling unit 
operations or icebreaking activities and impulse sounds >=160 dB re 1 
[micro]Pa (rms) created by seismic airguns during ZVSP activities. NMFS 
evaluated and critiqued the methods provided in Shell's application and 
determined that they were appropriate to conduct the requisite MMPA 
analyses. This section describes the estimated densities of marine 
mammals that may occur in the project area. The area of water that may 
be ensonified to the above sound levels is described further in the 
``Estimated Area Exposed to Sounds <ls-thn-eq>120 dB or <ls-thn-eq>160 
dB re 1 [micro]Pa rms'' subsection.

Marine Mammal Density Estimates

    Marine mammal density estimates in the Chukchi Sea have been 
derived for two time periods, the summer period covering July and 
August, and the fall period including September and October. Animal 
densities encountered in the Chukchi Sea during both of these time 
periods will further depend on the habitat zone within which the 
activities are occurring: open water or ice margin. More ice is likely 
to be present in the area of activities during the July-August period, 
so summer ice-margin densities have been applied to 50% of the area 
that may be ensonified from drilling and ZVSP activities in those 
months. Open water densities in the summer were applied to the 
remaining 50 percent of the area. Less ice is likely to be present 
during the September-October period, so fall ice-margin densities have 
been applied to only 20% of the area that may be ensonified from 
drilling and ZVSP activities in those months. Fall open-water densities 
were applied to the remaining 80 percent of the area. Since ice 
management activities would only occur within ice-margin habitat, the 
entire area potentially ensonified by ice management activities has 
been multiplied by the ice-margin densities in both seasons.
    There is some uncertainty about the representativeness of the data 
and assumptions used in the calculations. To provide some allowance for 
the uncertainties, ``maximum estimates'' as well as ``average 
estimates'' of the numbers of marine mammals potentially affected have 
been derived. For a few marine mammal species, several density 
estimates were available. In those cases, the mean and maximum 
estimates were determined from the reported densities or survey data. 
In other cases only one or no applicable estimate was available, so 
correction factors were used to arrive at ``average'' and ``maximum'' 
estimates. These are described in detail in the following subsections.
    Detectability bias, quantified in part by f(0), is associated with 
diminishing sightability with increasing lateral distance from the 
survey trackline. Availability bias, g(0), refers to the fact that 
there is <100% probability of sighting an animal that is present along 
the survey trackline. Some sources below included these correction 
factors in the reported densities (e.g. ringed seals in Bengtson et al. 
2005) and the best available correction factors were applied to 
reported results when they had not already been included (e.g. Moore et 
al. 2000).
(1) Cetaceans
    Eight species of cetaceans are known to occur in the activity area. 
Three of the nine species, bowhead, fin, and humpback whales, are 
listed as ``endangered'' under the ESA.
(a) Beluga Whales
    Summer densities of beluga whales in offshore waters are expected 
to be low, with somewhat higher densities in ice-margin and nearshore 
areas. Past aerial surveys have recorded few belugas in the offshore 
Chukchi Sea during the summer months (Moore et al. 2000). More recent 
aerial surveys of the Chukchi Sea from 2008-2012 flown by the NMML as 
part of the COMIDA project, now part of the Aerial Surveys of Arctic 
Marine Mammals (ASAMM) project, reported 10 beluga sightings (22 
individuals) in offshore waters during 22,154 km of on-transect effort. 
Larger groups of beluga whales were recorded in nearshore areas, 
especially in June and July during the spring migration (Clarke et al. 
2012, 2013). Additionally, only one beluga sighting was recorded during 
>80,000 km of visual effort during good visibility conditions from 
industry vessels operating in the Chukchi Sea in September-October of 
2006-2010 (Hartin et al. 2013). If belugas are present during the 
summer, they are more likely to occur in or near the ice edge or close 
to shore during their northward migration. Effort and sightings 
reported by Clarke et al. (2012, 2013) were used to calculate the 
average open-water density estimate. The mean group size of the 
sightings was 2.2. A f(0) value of 2.841 and g(0) value of 0.58 from 
Harwood et al. (1996) were also used in the density calculation 
resulting in an average open-water density of 0.0024 belugas/km\2\ 
(Table 6-1 of Shell's IHA application). The highest density from the 
reported survey periods (0.0049 belugas/km\2\, in 2012) has been used 
as the maximum density that may occur in open-water habitat (Table 6-1 
in Shell's IHA application). Specific data on the relative abundance of 
beluga in open-water versus ice-margin habitat during the summer in the 
Chukchi Sea is not available. However, belugas are commonly associated 
with ice, so an inflation factor of four was used to estimate the ice-
margin densities from the open-water densities. Very low densities 
observed from vessels operating in the Chukchi Sea during non-seismic 
periods and locations in July-August of 2006-2010 (0.0-0.0003/mi\2\, 
0.0-0.0001/km\2\; Hartin et al. 2013), also suggest the number of 
beluga whales likely to be present near the planned activities will not 
be large.
    In the fall, beluga whale densities offshore in the Chukchi Sea are 
expected to be somewhat higher than in the summer because individuals 
of the eastern Chukchi Sea stock and the Beaufort Sea stock will be 
migrating south to their wintering grounds in the Bering Sea (Allen and 
Angliss 2012). Densities derived from survey results in the northern 
Chukchi Sea in Clarke and Ferguson (in prep, cited in Shell 2014) and 
Clarke et al. (2012, 2013) were used as the average density for open-
water season estimates (Table 6-2 in Shell's IHA application). Clarke 
and Ferguson (in prep, cited in Shell 2014) and Clarke et al. (2012, 
2013) reported 17 beluga sightings (28 individuals) during 22,255 km of 
on-transect effort in water depths 36-50 m during the months of July 
through September. The mean group size of those three sightings was 
1.6. A f(0) value of 2.841 and a g(0) value of 0.58 from Harwood et al. 
(1996) were used to calculate the average open-water density of 0.0031 
belugas/km\2\ (Table 6-2 in Shell IHA application). The highest density 
from the reported periods (0.0053 belugas/km\2\, in 2012) was again 
used as the maximum density that may occur in open-water habitat. Moore 
et al. (2000) reported lower than expected beluga sighting rates in 
open-water during fall surveys in the Beaufort and Chukchi seas, so an 
inflation value of four was used to estimate the ice-margin densities 
from the open-water densities. Based on the few beluga sightings from 
vessels operating in the Chukchi Sea

[[Page 11762]]

during non-seismic periods and locations in September-November of 2006-
2010 (Hartin et al. 2013), the relatively low densities shown in Table 
6-2 in Shell's IHA application are consistent with what is likely to be 
observed form vessels during the planned exploration drilling 
activities.
(b) Bowhead Whales
    By July, most bowhead whales are northeast of the Chukchi Sea, 
within or migrating toward their summer feeding grounds in the eastern 
Beaufort Sea. No bowheads were reported during 10,686 km of on-transect 
effort in the Chukchi Sea by Moore et al. (2000). Bowhead whales were 
also rarely sighted in July-August of 2006-2010 during aerial surveys 
of the Chukchi Sea coast (Thomas et al. 2011). This is consistent with 
movements of tagged whales (ADFG 2010), all of which moved through the 
Chukchi Sea by early May 2009, and tended to travel relatively close to 
shore, especially in the northern Chukchi Sea.
    The estimate of the July-August open-water bowhead whale density in 
the Chukchi Sea was calculated from the three bowhead sightings (3 
individuals) and 22,154 km of survey effort in waters 36-50 m deep in 
the Chukchi Sea during July-August reported in Clarke and Ferguson (in 
prep, cited in Shell 2014) and Clarke et al. (2012, 2013). The mean 
group size from those sightings was 1. The group size value, along with 
a f(0) value of 2 and a g(0) value of 0.07, both from Thomas et al. 
(2002) were used to estimate a summer density of 0.0019 bowheads/km\2\ 
(Table 6-1 in Shell's IHA application). The two sightings recorded 
during 4,209 km of survey effort in 2011 (Clarke et al. 2012) produced 
the highest annual bowhead density during July-August (0.0068 bowheads/
km\2\) which was used as the maximum open-water density (Table 6-1 in 
Shell's IHA application). Bowheads are not expected to be encountered 
in higher densities near ice in the summer (Moore et al. 2000), so the 
same density estimates have been used for open-water and ice-margin 
habitats. Densities from vessel based surveys in the Chukchi Sea during 
non-seismic periods and locations in July-August of 2006-2010 (Hartin 
et al. 2013) ranged from 0.0002-0.0008/km\2\ with a maximum 95% CI of 
0.0085/km\2\. This suggests the densities used in the calculations and 
shown in Table 6-1 in Shell's IHA application are similar to what are 
likely to be observed from vessels near the area of planned exploration 
drilling activities.
    During the fall, bowhead whales that summered in the Beaufort Sea 
and Amundsen Gulf migrate west and south to their wintering grounds in 
the Bering Sea, making it more likely those bowheads will be 
encountered in the Chukchi Sea at this time of year. Moore et al. 
(2000) reported 34 bowhead sightings during 44,354 km of on-transect 
survey effort in the Chukchi Sea during September-October. Thomas et 
al. (2011) also reported increased sightings on coastal surveys of the 
Chukchi Sea during October and November of 2006-2010. GPS tagging of 
bowheads appear to show that migration routes through the Chukchi Sea 
are more variable than through the Beaufort Sea (Quakenbush et al. 
2010). Some of the routes taken by bowheads remain well north of the 
planned drilling activities while others have passed near to or through 
the area. Kernel densities estimated from GPS locations of whales 
suggest that bowheads do not spend much time (e.g. feeding or resting) 
in the north-central Chukchi Sea near the area of planned activities 
(Quakenbush et al. 2010). However, tagged whales did spend a 
considerable amount of time in the north-central Chukchi Sea in 2012, 
despite ongoing industrial activities in the region (ADFG 2012). Clarke 
and Ferguson (in prep, cited in Shell 2014) and Clarke et al. (2012, 
2013) reported 72 sightings (86 individuals) during 22,255 km of on-
transect aerial survey effort in waters 36-50 m deep in 2008-2012, the 
majority of which (53 sightings) were recorded in 2012. The mean group 
size of the 72 sightings was 1.2. The same f(0) and g(0) values that 
were used for the summer estimates above were used for the fall 
estimates resulting in an average September-October estimate of 0.0552 
bowheads/km\2\ (Table 6-2 in Shell's IHA application). The highest 
density form the survey periods (0.1320 bowheads/km\2\; in 2012) was 
used as the maximum open-water density during the fall period. Moore et 
al. (2000) found that bowheads were detected more often than expected 
in association with ice in the Chukchi Sea in September-October, so the 
ice-margin densities that are used are twice the open-water densities. 
Densities from vessel based surveys in the Chukchi Sea during non-
seismic periods and locations in September-November of 2006-2010 
(Hartin et al. 2013) ranged from 0.0003 to 0.0052/km\2\ with a maximum 
95 percent CI of 0.051/km\2\. This suggests the densities used in the 
calculations and shown in Table 6-2 in Shell's IHA application are 
somewhat higher than are likely to be observed from vessels near the 
area of planned exploration drilling activities.
(c) Gray Whales
    Gray whale densities are expected to be much higher in the summer 
months than during the fall. Moore et al. (2000) found the distribution 
of gray whales in the planned operational area was scattered and 
limited to nearshore areas where most whales were observed in water 
less than 35 m deep. Thomas et al. (2011) also reported substantial 
declines in the sighting rates of gray whales in the fall. The average 
open-water summer density (Table 6-1 in Shell's IHA application) was 
calculated from 2008-2012 aerial survey effort and sightings in Clarke 
and Ferguson (in prep, cited in Shell 2014) and Clarke et al. (2012, 
2013) for water depths 36-50 m including 98 sightings (137 individuals) 
during 22,154 km of on-transect effort. The average group size of those 
sightings was 1.4. Correction factors f(0) = 2.49 (Forney and Barlow 
1998) and g(0) = 0.30 (Forney and Barlow 1998, Mallonee 1991) were used 
to calculate and average open-water density of 0.0253 gray whales/km2 
(Table 6-1 in Shell's IHA application). The highest density from the 
survey periods reported in Clarke and Ferguson (in prep, cited in Shell 
2014) and Clarke et al. (2012, 2013) was 0.0268 gray whales/km\2\ in 
2012 and this was used as the maximum open-water density. Gray whales 
are not commonly associated with sea ice, but may be present near it, 
so the same densities were used for ice-margin habitat as were derived 
for open-water habitat during both seasons. Densities from vessel based 
surveys in the Chukchi Sea during non-seismic periods and locations in 
July-August of 2006-2010 (Hartin et al. 2013) ranged from 0.0008/km\2\ 
to 0.0085/km\2\ with a maximum 95 percent CI of 0.0353 km\2\.
    In the fall, gray whales may be dispersed more widely through the 
northern Chukchi Sea (Moore et al. 2000), but overall densities are 
likely to be decreasing as the whales begin migrating south. A density 
calculated from effort and sightings (46 sightings [64 individuals] 
during 22,255 km of on-transect effort) in water 36-50 m deep during 
September-October reported by Clarke and Ferguson (in prep, cited in 
Shell 2014) and Clarke et al. (2012, 2013) was used as the average 
estimate for the Chukchi Sea during the fall period (0.0118 gray 
whales/km\2\; Table 6-2 in Shell's IHA application). The corresponding 
group size value of 1.39, along with the same f(0) and g(0) values 
described above were used in the calculation. The maximum density from 
the survey periods (0.0248 gray whales/km\2\) was reported in 2011 
(Clarke et al.

[[Page 11763]]

2012) and used as the maximum fall open-water density (Table 6-2 in 
Shell's IHA application). Densities from vessel based surveys in the 
Chukchi Sea during non-seismic periods and locations in September-
November of 2006-2010 (Hartin et al. 2013) ranged from 0.0/km\2\ to 
0.0044/km\2\ with a maximum 95% CI of 0.0335 km\2\.
(d) Harbor Porpoises
    Harbor Porpoise densities were estimated from industry data 
collected during 2006-2010 activities in the Chukchi Sea. Prior to 
2006, no reliable estimates were available for the Chukchi Sea and 
harbor porpoise presence was expected to be very low and limited to 
nearshore regions. Observers on industry vessels in 2006-2010, however, 
recorded sightings throughout the Chukchi Sea during the summer and 
early fall months. Density estimates from 2006-2010 observations during 
non-seismic periods and locations in July-August ranged from 0.0013/
km\2\ to 0.0029/km\2\ with a maximum 95% CI of 0.0137/km\2\ (Hartin et 
al. 2013). The average density from the summer season of those three 
years (0.0022/km\2\) was used as the average open-water density 
estimate while the high value (0.0029/km\2\) was used as the maximum 
estimate (Table 6-1 in Shell's IHA application). Harbor porpoise are 
not expected to be present in higher numbers near ice, so the open-
water densities were used for ice-margin habitat in both seasons. 
Harbor porpoise densities recorded during industry operations in the 
fall months of 2006-2010 were slightly lower and ranged from 0.0/km\2\ 
to 0.0044/km\2\ with a maximum 95% CI of 0.0275/km\2\. The average of 
those years (0.0021/km\2\) was again used as the average density 
estimate and the high value (0.0044/km\2\) was used as the maximum 
estimate (Table 6-2 in Shell's IHA application).
(e) Other Whales
    The remaining five cetacean species that could be encountered in 
the Chukchi Sea during Shell's planned exploration drilling program 
include the humpback whale, killer whale, minke whale, and fin whale. 
Although there is evidence of the occasional occurrence of these five 
cetacean species in the Chukchi Sea, it is unlikely that more than a 
few individuals will be encountered during the planned exploration 
drilling program and therefore minimum densities have been assigned to 
these species (Tables 6-1 and 6-2 in Shell's IHA application). Clarke 
et al. (2011, 2013) and Hartin et al. (2013) reported humpback whale 
sightings; George and Suydam (1998) reported killer whales; Brueggeman 
et al. (1990), Hartin et al. (2013), Clarke et al. (2012, 2013), and 
Reider et al. (2013) reported minke whales; and Clarke et al. (2011, 
2013) and Hartin et al. (2013) reported fin whales. With regard to 
humpback and fin whales, NMFS (2013) recently concluded these whales 
occur in very low numbers in the project area, but may be regular 
visitors.
    Of these uncommon cetacean species, minke whale has the potential 
to be the most common based on recent industry surveys. Reider et al. 
(2013) reported 13 minke whale sightings in the Chukchi Sea in 2013 
during Shell's marine survey program. All but one minke whale sighting 
in 2013, however, were observed in nearshore areas despite only minimal 
monitoring effort in nearshore areas compared to more offshore 
locations near the Burger prospect (Reider et al. 2013).
(2) Pinnipeds
    Three species of pinnipeds under NMFS jurisdiction are likely to be 
encountered in the Chukchi Sea during Shell's planned exploration 
drilling program: Ringed seal, bearded seal, and spotted seal. Ringed 
and bearded seals are associated with both the ice margin and the 
nearshore area. The ice margin is considered preferred habitat (as 
compared to the nearshore areas) for ringed and bearded seals during 
most seasons. Spotted seals are often considered to be predominantly a 
coastal species except in the spring when they may be found in the 
southern margin of the retreating sea ice. However, satellite tagging 
has shown that they sometimes undertake long excursions into offshore 
waters during summer (Lowry et al. 1994, 1998). Ribbon seals have been 
reported in very small numbers within the Chukchi Sea by observers on 
industry vessels (Patterson et al. 2007, Hartin et al. 2013).
(a) Ringed and Bearded Seals
    Ringed seal and bearded seals ``average'' and ``maximum'' summer 
ice-margin densities were available in Bengtson et al. (2005) from 
spring surveys in the offshore pack ice zone (zone 12P) of the northern 
Chukchi Sea. However, corrections for bearded seal availability, g(0), 
based on haulout and diving patterns were not available. Densities of 
ringed and bearded seals in open water are expected to be somewhat 
lower in the summer when preferred pack ice habitat may still be 
present in the Chukchi Sea. Average and maximum open-water densities 
have been estimated as 3/4 of the ice margin densities during both 
seasons for both species. The fall density of ringed seals in the 
offshore Chukchi Sea has been estimated as 2/3 the summer densities 
because ringed seals begin to reoccupy nearshore fast ice areas as it 
forms in the fall. Bearded seals may also begin to leave the Chukchi 
Sea in the fall, but less is known about their movement patterns so 
fall densities were left unchanged from summer densities. For 
comparison, the ringed seal density estimates calculated from data 
collected during summer 2006-2010 industry operations ranged from 
0.0138/km\2\ to 0.0464/km\2\ with a maximum 95 percent CI of 0.1581/
km\2\ (Hartin et al. 2013).
(b) Spotted Seals
    Little information on spotted seal densities in offshore areas of 
the Chukchi Sea is available. Spotted seal densities in the summer were 
estimated by multiplying the ringed seal densities by 0.02. This was 
based on the ratio of the estimated Chukchi populations of the two 
species. Chukchi Sea spotted seal abundance was estimated by assuming 
that 8% of the Alaskan population of spotted seals is present in the 
Chukchi Sea during the summer and fall (Rugh et al. 1997), the Alaskan 
population of spotted seals is 59,214 (Allen and Angliss 2012), and 
that the population of ringed seals in the Alaskan Chukchi Sea is 
~208,000 animals (Bengtson et al. 2005). In the fall, spotted seals 
show increased use of coastal haulouts so densities were estimated to 
be 2/3 of the summer densities.
(c) Ribbon Seals
    Four ribbon seal sightings were reported during industry vessel 
operations in the Chukchi Sea in 2006-2010 (Hartin et al. 2013). The 
resulting density estimate of 0.0007/km\2\ was used as the average 
density and 4 times that was used as the maximum for both seasons and 
habitat zones.

Individual Sound Sources and Level B Radii

    The assumed start date of Shell's exploration drilling program in 
the Chukchi Sea using the drilling units Discoverer and Polar Pioneer 
with associated support vessels is 4 July. Shell may conduct 
exploration drilling activities at up to four drill sites at the 
prospect known as Burger. Drilling activities are expected to be 
conducted through approximately 31 October 2015.
    Previous IHA applications for offshore Arctic exploration programs 
estimated areas potentially ensonified to >=120 or >=160 dB re 1 [mu]Pa 
rms independently for each continuous or pulsed sound

[[Page 11764]]

source, respectively (e.g., drilling, ZVSP, etc.). The primary method 
used in this IHA application for estimating areas ensonified to 
continuous sound levels >=120 dB re 1 [mu]Pa rms by drilling-related 
activities involved sound propagation modeling of a variety of 
scenarios consisting of multiple, concurrently-operating sound sources. 
These ``activity scenarios'' consider additive acoustic effects from 
multiple sound sources at nearby locations, and more closely capture 
the nature of a dynamic acoustic environment where numerous activities 
are taking place simultaneously. The area ensonified to >=160 dB re 1 
[mu]Pa rms from ZVSP, a pulsed sound source, was treated independently 
from the activity scenarios for continuous sound sources.
    The continuous sound sources used for sound propagation modeling of 
activity scenarios included (1) drilling unit and drilling sounds, (2) 
supply and drilling support vessels using DP when tending to a drilling 
unit, (3) MLC construction, (4) anchor handling in support of mooring a 
drilling unit, and (5) ice management activities. The information used 
to generate sound level characteristics for each continuous sound 
source is summarized below to provide background on the model inputs. A 
``safety factor'' of 1.3 dB re 1 [mu]Pa rms was added to the source 
level for each sound source prior to modeling activity scenarios to 
account for variability across the project area associated with 
received levels at different depths, geoacoustical properties, and 
sound-speed profiles. The addition of the 1.3 dB re 1 [mu]Pa rms safety 
factor to source levels resulted in an approximate 20 percent increase 
in the distance to the 120 dB re 1 [mu]Pa rms threshold for each 
continuous source.
    Table 2 summarizes the 120 dB re 1 [mu]Pa rms radii for individual 
sound sources, both the ``original'' radii as measured in the field, 
and the ``adjusted'' values that were calculated by adding the ``safety 
factor'' of 1.3 dB re 1 [mu]Pa rms to each source. The adjusted source 
levels were then used in sound propagation modeling of activity 
scenarios to estimate ensonified areas and associated marine mammal 
exposure estimates. Additional details for each of the continuous sound 
sources presented in Table 2 are discussed below.
    The pulsed sound sources used for sound propagation modeling of 
activity scenarios consisted of two small airgun arrays proposed for 
ZVSP activities. All possible array configurations and operating depths 
were modeled to identify the arrangement with the greatest sound 
propagation characteristics. The resulting >=160 dB re 1 [mu]Pa rms 
radius was multiplied by 1.5 as a conservative measure prior to 
estimating exposed areas, which is discussed in greater detail below.

     Table 2--Measured and Adjusted 120 dB re 1 [micro]Pa Radii for
                  Individual, Continuous Sound Sources
------------------------------------------------------------------------
                                    Radii of 120 dB re 1 [micro]Pa (rms)
                                             isopleth  (meters)
 Activity/continuous sound source  -------------------------------------
                                         Original         With 1.3 dB
                                       measurement     correction factor
------------------------------------------------------------------------
Drilling at 1 site................              1,500              1,800
Vessel in DP......................              4,500              5,500
Mudline cellar construction at 1                8,200              9,300
 site.............................
Anchor handling at 1 site (assumed             19,000             22,000
 to be 2 vessels).................
Single vessel ice management......              9,600             11,000
------------------------------------------------------------------------

    Two sound sources have been proposed by Shell for the ZVSP surveys 
in 2015. The first is a small airgun array that consists of three 150 
in3 (2,458 cm\3\) airguns for a total volume of 450 in\3\ (7,374 
cm\3\). The second ZVSP sound source consists of two 250 in\3\ (4,097 
cm\3\) airguns with a total volume of 500 in\3\ (8,194 cm\3\). Sound 
footprints for each of the two proposed ZVSP airgun array 
configurations were estimated using JASCO Applied Sciences' MONM. The 
model results were maximized over all water depths from 9.8 to 23 ft (3 
to 7 m) to yield precautionary sound level isopleths as a function of 
range and direction from the source. The 450 in\3\ airgun array at a 
source depth of 7 m yielded the maximum ranges to the >=190, >=180, and 
>=160 dB re 1 [mu]Pa rms isopleths.
    There are two reasons that the radii for the 450 in\3\ airgun array 
are larger than those for the 500 in\3\ array. First, the sound energy 
does not scale linearly with the airgun volume, rather it is 
proportional to the cube root of the volume. Thus, the total sound 
energy from three airguns is larger than the total energy from two 
airguns, even though the total volume is smaller. Second, larger volume 
airguns emit more low-frequency sound energy than smaller volume 
airguns, and low-frequency airgun sound energy is strongly attenuated 
by interaction with the surface reflection. Thus, the sound energy for 
the larger-volume array experiences more reduction and results in 
shorter sound threshold radii.
    The estimated 95th percentile distances to the following thresholds 
for the 450 in\3\ airgun array were: >=190 dB re 1 [mu]Pa rms = 170 m, 
>=180 dB re 1 [mu]Pa rms = 920 m, and >=160 dB re 1 [mu]Pa rms = 7,970 
m. The >=160 dB re 1 [mu]Pa rms distance was multiplied by 1.5 for a 
distance of 11,960 m. This radius was used for estimating areas 
ensonified by pulsed sounds to >=160 dB re 1 [mu]Pa rms during a single 
ZVSP survey. ZVSP surveys may occur at up to two different drill sites 
during Shell's planned 2015 exploration drilling program in the Chukchi 
Sea.
    As noted above, previous IHA applications for Arctic offshore 
exploration programs estimated areas potentially ensonified to 
continuous sound levels >=120 dB re 1 [mu]Pa rms independently for each 
sound source. This method was appropriate for assessing a small number 
of continuous sound sources that did not consistently overlap in time 
and space. However, many of the continuous sound sources described 
above will operate concurrently at one or more nearby locations in 2015 
during Shell's planned exploration drilling program in the Chukchi Sea. 
It is therefore appropriate to consider the concurrent operation of 
numerous sound sources and the additive acoustic effects from combined 
sound fields when estimating areas potentially exposed to levels >=120 
dB re 1 [mu]Pa rms.
    A range of potential ``activity scenarios'' was derived from a 
realistic operational timeline by considering the

[[Page 11765]]

various combinations of different continuous sound sources that may 
operate at the same time at one or more locations. The total number of 
possible activity combinations from all sources at up to four different 
drill sites would not be practical to assess or present in a meaningful 
way. Additionally, combinations such as concurrent drilling and anchor 
handling in close proximity do not add meaning to the analysis given 
the negligible contribution of drilling sounds to the total area 
ensonified by such a scenario. For these reasons, various combinations 
of similar activities were grouped into representative activity 
scenarios shown in Table 3. Ensonified areas for these representative 
activity scenarios were estimated through sound propagation modeling. 
Activity scenarios were modeled for different drill site combinations 
and, as a conservative measure, the locations corresponding to the 
largest ensonified area were chosen to represent the given activity 
scenario. In other words, by binning all potential scenarios into the 
most conservative representative scenario, the largest possible 
ensonified areas for all activities were identified for analysis. A 
total of nine representative activity scenarios were modeled to 
estimate areas exposed to continuous sounds >=120 dB re 1 [mu]Pa rms 
for Shell's planned 2015 exploration drilling program in the Chukchi 
Sea (Table 3). A tenth scenario was included for the ZVSP activities.

 Table 3--Sound Propagation Modeling Results of Representative Drilling Related Activity Scenarios and Estimates
   of the Total Area Potentially Ensonified Above Threshold Levels at the Burger Prospect in the Chukchi Sea,
                        Alaska, During Shell's Proposed 2015 Exploration Drilling Program
----------------------------------------------------------------------------------------------------------------
                                                          Threshold level   Area potentially ensonified  (km\2\)
             Activity scenario description                    (dB re 1     -------------------------------------
                                                           [micro]Pa rms)         Summer              Fall
----------------------------------------------------------------------------------------------------------------
Drilling at 1 site.....................................                120               10.2               10.2
Drilling and DP vessel at 1 site.......................                120              111.8              111.8
Drilling and DP vessel (1 site) + drilling and DP                      120              295.5              295.5
 vessel (2nd site).....................................
Mudline cellar construction at 2 different sites.......                120              575.5              575.5
Anchor handling at 1 site..............................                120            1,534.9            1,534.9
Drilling and DP vessel at 1 site + anchor handling at                  120            1,759.2            1,759.2
 2nd site..............................................
Mudline cellar construction at 2 different sites +                     120            2,046.3            2,046.3
 anchor handling at 3rd site...........................
Two-vessel ice management..............................                120              937.4              937.4
Four-vessel ice management.............................                120            1,926.0            1,926.0
ZVSP at 2 different sites..............................                160                0.0              898.0
----------------------------------------------------------------------------------------------------------------

Potential Number of ``Takes by Harassment''

    This section provides estimates of the number of individuals 
potentially exposed to continuous sound levels >=120 dB re 1 [mu]Pa rms 
from exploration drilling related activities and pulsed sound levels 
>=160 dB re 1 [mu]Pa rms by ZVSP activities. The estimates are based on 
a consideration of the number of marine mammals that might be affected 
by operations in the Chukchi Sea during 2015 and the anticipated area 
exposed to those sound levels.
    To account for different densities in different habitats, Shell has 
assumed that more ice is likely to be present in the area of operations 
during the July-August period than in the September-October period, so 
summer ice-margin densities have been applied to 50% of the area that 
may be exposed to sounds from exploration drilling activities in those 
months. Open water densities in the summer were applied to the 
remaining 50% of the area.
    Less ice is likely to be present during the September-October 
period than in the July-August period, so fall ice-margin densities 
have been applied to only 20% of the area that may be exposed to sounds 
from exploration drilling activities in those months. Fall open-water 
densities were applied to the remaining 80% of the area. Since 
icebreaking activities would only occur within ice-margin habitat, the 
entire area potentially ensonified by icebreaking activities has been 
multiplied by the ice-margin densities in both seasons.
    Estimates of the numbers of marine mammals potentially exposed to 
continuous sounds >=120 dB re 1 [mu]Pa rms or pulsed sounds >=160 dB re 
1 [mu]Pa rms are based on assumptions that include upward scaling of 
source levels for all sound sources, no avoidance of activities/sounds 
by individual marine mammals, and 100% turnover of individuals in 
ensonified areas every 24 hours (except for bowhead whales, as 
discussed below). NMFS considers that these assumptions are overly 
conservative, especially for non-migratory species/periods and for 
cetaceans in particular, which are known to avoid anthropogenic 
activities and associated sounds at varying distances depending on the 
context in which activities and sounds are encountered (Koski and 
Miller 2009; Moore 2000; Moore et al. 2000; Treacy et al. 2006). 
Although we recognize these assumptions may be overly conservative, it 
is difficult to scale variables in a more precise fashion until recent 
evidence can be incorporated into newer estimation methods.
    The following sections present a range of exposure estimates for 
bowhead whales and ringed seals. Estimates were generated based on an 
evaluation of the best available science and a consideration of the 
assumptions surrounding avoidance behavior and the frequency of 
turnover. In addition to demonstrating the sensitivity of exposure 
estimates to variable assumptions, the wide range of estimates is more 
informative for assessing negligible impact compared to a single 
estimated value with a high degree of uncertainty.
    It is difficult to determine an appropriate, precise average 
turnover time for a population of animals in a particular area of the 
Chukchi Sea. Reasons for this include differences in residency time for 
migratory and non-migratory species, changes in distribution of food 
and other factors such as behavior that influence animal movement, 
variation among individuals of the same species, etc. Complete turnover 
of individual bowhead whales in the project area each 24-hour period 
may occur during fall migration when bowheads are traveling through the 
area. Even during this fall period, bowheads often move in pulses with 
one to several days between major pulses of whales (Miller et al. 
2002). Gaps between groups of whales can probably be

[[Page 11766]]

accounted for partially by bowhead whales stopping to feed 
opportunistically when food is encountered. The extent of feeding by 
bowhead whales during fall migration across the Beaufort and Chukchi 
Seas varies greatly from year to year based on the location and 
abundance of prey (Shelden and Mocklin 2013). For example, if a 
turnover rate of 48 hours to account for intermittent periods of 
migrating and feeding individuals is assumed, then the number of 
bowhead whale being exposed would be reduced accordingly by 50%. Due to 
changes in the turnover rate across time, a conservative turnover rate 
of 24 hours has been selected to estimate the number of bowhead whales 
exposed.
    During the summer, relatively few bowhead or beluga whales are 
present in the Chukchi Sea and in most cases, given that the operations 
area is not known to be a critical feeding area (Citta et al. 2014; 
Allen and Angliss 2014), whales would be likely to simply avoid the 
area of operations (Schick and Urban 2000; Richardson et al. 1995a). 
Similarly, during migration many whales would likely travel around the 
area (i.e., avoid it) as it is not known to be important habitat for 
either bowheads or belugas during any portion of the year (Citta et al. 
2014; Allen and Angliss 2014). There is a large body of evidence 
indicating that bowhead whales avoid anthropogenic activities and 
associated underwater sounds depending on the context in which these 
activities are encountered (LGL et al. 2014; Koski and Miller 2009; 
Moore 2000; Moore et al. 2000; Treacy et al. 2006). Increasing evidence 
suggests that proximity to an activity or sound source, coupled with an 
individual's behavioral state (e.g., feeding vs traveling) among other 
contextual variables, as opposed to received sound level alone, 
strongly influences the degree to which an individual whale 
demonstrates aversion or other behaviors (reviewed in Richardson et al. 
1995b; Gordon et al. 2004; Koski and Miller 2009).
    Several historical studies provide valuable information on the 
distribution and behavior of bowhead whales relative to drilling 
activities in the Alaskan Arctic offshore. One is a 1986 study by Shell 
at Hammerhead and Corona prospects (Davis 1987) and another is an 
analysis by Schick and Urban (2000) of 1993 aerial survey data 
collected by Coastal Offshore and Pacific Corporation. Both studies 
suggest that few whales approached within ~18 km of an offshore 
drilling operation in the Beaufort Sea. Davis (1987) reported that the 
surfacing and respiration variables that are often used as indicators 
of behavioral disturbance seemed normal when whales were >18.5 km from 
the active drill site and as they circumnavigated the drilling 
operation. The Schick and Urban (2000) study found whales as close as 
18.5-20.3 km in all directions around the active operation, suggesting 
that whales that had diverted returned to their normal migration routes 
shortly after passing the operation.
    If bowhead whales avoid drilling and related support activities at 
distances of approximately 20 km in 2015, as was noted consistently by 
Davis (1987) and Schick and Urban (2002), this would preclude exposure 
of the vast majority of individuals to continuous sounds >=120 dB re 1 
[mu]Pa rms or pulsed sounds >=160 dB re 1 [mu]Pa rms. The largest 
ensonified areas during Shell's 2012 exploration drilling program were 
produced by mudline cellar construction, ice management, and anchor 
handling (JASCO Applied Sciences and Greeneridge Sciences 2014). Only 
anchor handling is expected to result in the lateral propagation of 
continuous sound levels >=120 dB re 1 [mu]Pa rms to distances of 20 km 
or greater from the source.
    By assuming half of the individual bowhead whales would avoid areas 
with sounds at or above Level B thresholds, the exposure estimate would 
be reduced accordingly by 50% even if 100% turnover of migrating whales 
was still assumed to take place every 24 hours. Taking into 
consideration what is known from studies documenting temporary 
diversion around drilling activities, and conservative assumptions with 
regards to turnover rates, NMFS considers the conservative estimate 
associated with a 24 hour turnover and 50% avoidance to be the most 
reasonable estimate of individual exposures.
    Table 4 presents the exposure estimates for Shell's proposed 2015 
exploration drilling program in the Chukchi Sea. The table also 
summarizes abundance estimates for each species and the corresponding 
percent of each population that may be exposed to continuous sounds 
>=120 dB re 1 [mu]Pa rms or pulsed sounds >=160 dB re 1 [mu]Pa rms. 
With the exception of the exposure estimate for bowhead whales 
described above, estimates for all other species assumed 100% daily 
turnover and no avoidance of activities or ensonified areas.

 Table 4--The Total Number of Potential Exposures of Marine Mammals to Sound Levels >=120 dB re 1 [mu]Pa rms or
 <ls-thn-eq>=160 dB re 1 [mu]Pa rms During the Shell's Proposed Drilling Activities in the Chukchi Sea, Alaska,
                                                      2015
                           [Estimates are also shown as a percent of each population]
----------------------------------------------------------------------------------------------------------------
                                                                                      Number          Percent
                             Species                                 Abundance       potential       estimated
                                                                                     exposure       population
----------------------------------------------------------------------------------------------------------------
Beluga..........................................................          42,968             974             2.3
Killer whale....................................................           2,084              14             0.8
Harbor porpoise.................................................          48,215             294             0.6
Bowhead whale...................................................          19,534           2,582            13.2
Fin whale.......................................................           1,652              14             0.8
Gray whale......................................................          19,126           2,581            13.5
Humpback whale..................................................          20,800              14             0.1
Minke whale.....................................................             810              41             5.1
Bearded seal....................................................         155,000           1,722             1.1
Ribbon seal.....................................................          49,000              96             0.2
Ringed seal.....................................................         300,000          50,433            16.8
Spotted seal....................................................         141,479           1,007             0.7
----------------------------------------------------------------------------------------------------------------


[[Page 11767]]

    In summary, several precautionary methods were applied when 
calculating exposure estimates. These conservative methods and related 
considerations include:
    <bullet> Application of a 1.3 dB re 1 [mu]Pa rms safety factor to 
the source level of each continuous sound source prior to sound 
propagation modeling of areas exposed to Level B thresholds;
    <bullet> Binning of similar activity scenarios into a 
representative scenario, each of which reflected the largest exposed 
area for a related group of activities;
    <bullet> Modeling numerous iterations of each activity scenario at 
different drill site locations to identify the spatial arrangement with 
the largest exposed area for each;
    <bullet> Assuming 100 percent daily turnover of populations, which 
likely overestimates the number of different individuals that would be 
exposed, especially during non-migratory periods;
    <bullet> Expected marine mammal densities assume no avoidance of 
areas exposed to Level B thresholds (with the exception of bowhead 
whale, for which 50% of individuals were assumed to demonstrate 
avoidance behavior); and
    <bullet> Density estimates for some cetaceans include nearshore 
areas where more individuals would be expected to occur than in the 
offshore Burger Prospect area (e.g., gray whales).
    Additionally, post-season estimates of the number of marine mammals 
exposed to Level B thresholds per Shell 90-Day Reports from the 2012 
IHA consistently support the methods used in Shell's IHA applications 
as precautionary. Most recently, exposure estimates reported by Reider 
et al. (2013) from Shell's 2012 exploration activities in the Chukchi 
Sea were considerably lower than those requested in Shell's 2012 IHA 
application. The following summary of the numbers of cetaceans and 
pinnipeds that may be exposed to sounds above Level B thresholds is 
best interpreted as conservatively high, particularly the larger value 
for each species that assumes a new population of individuals each day.

Analysis and Preliminary Determinations

Negligible Impact

    Negligible impact is ``an impact resulting from the specified 
activity that cannot be reasonably expected to, and is not reasonably 
likely to, adversely affect the species or stock through effects on 
annual rates of recruitment or survival'' (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 Level B harassment 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 behavioral harassment, 
NMFS must consider other factors, such as the likely nature of any 
responses (their intensity, duration, etc.), the context of any 
responses (critical reproductive time or location, migration, etc.), as 
well as the number and nature of estimated Level A harassment takes, 
the number of estimated mortalities, effects on habitat, and the status 
of the species.
    No injuries or mortalities are anticipated to occur as a result of 
Shell's proposed Chukchi Sea exploratory drilling program, and none are 
proposed to be authorized. Injury, serious injury, or mortality could 
occur if there were a large or very large oil spill. However, as 
discussed previously in this document, the likelihood of a spill is 
extremely remote. Shell has implemented many design and operational 
standards to mitigate the potential for an oil spill of any size. NMFS 
does not propose to authorize take from an oil spill, as it is not part 
of the specified activity. Additionally, animals in the area are not 
expected to incur hearing impairment (i.e., TTS or PTS) or non-auditory 
physiological effects. Instead, any impact that could result from 
Shell's activities is most likely to be behavioral harassment and is 
expected to be of limited duration. Although it is possible that some 
individuals may be exposed to sounds from drilling operations more than 
once, during the migratory periods it is less likely that this will 
occur since animals will continue to move across the Chukchi Sea 
towards their wintering grounds.
    Bowhead and beluga whales are less likely to occur in the proposed 
project area in July and August, as they are found mostly in the 
Canadian Beaufort Sea at this time. The animals are more likely to 
occur later in the season (mid-September through October), as they head 
west towards Russia or south towards the Bering Sea. Additionally, 
while bowhead whale tagging studies revealed that animals occurred in 
the LS 193 area, a higher percentage of animals were found outside of 
the LS 193 area in the fall (Quakenbush et al., 2010). Bowhead whales 
are not known to feed in areas near Shell's leases in the Chukchi Sea. 
The closest primary feeding ground is near Point Barrow, which is more 
than 150 mi (241 km) east of Shell's Burger prospect. Therefore, if 
bowhead whales stop to feed near Point Barrow during Shell's proposed 
operations, the animals would not be exposed to continuous sounds from 
the drilling units or icebreaker above 120 dB or to impulsive sounds 
from the airguns above 160 dB, as those sound levels only propagate 1.8 
km, 11 km, and 11.9 km, respectively, which includes the inflation 
factor. Therefore, sounds from the operations would not reach the 
feeding grounds near Point Barrow.
    Gray whales occur in the northeastern Chukchi Sea during the summer 
and early fall to feed. Hanna Shoals, an area northeast of Shell's 
proposed drill sites, is a common gray whale feeding ground. This 
feeding ground lies outside of the 120-dB and 160-dB ensonified areas 
from Shell's activities. While some individuals may swim through the 
area of active drilling, it is not anticipated to interfere with their 
feeding at Hanna Shoals or other Chukchi Sea feeding grounds. Other 
cetacean species are much rarer in the proposed project area. The 
exposure of cetaceans to sounds produced by exploratory drilling 
operations (i.e., drilling units, ice management/icebreaking, and 
airgun operations) is not expected to result in more than Level B 
harassment.
    Few seals are expected to occur in the proposed project area, as 
several of the species prefer more nearshore waters. Additionally, as 
stated previously in this document, pinnipeds appear to be more 
tolerant of anthropogenic sound, especially at lower received levels, 
than other marine mammals, such as mysticetes. Shell's proposed 
activities would occur at a time of year when the ice seal species 
found in the region are not molting, breeding, or pupping. Therefore, 
these important life functions would not be impacted by Shell's 
proposed activities. The exposure of pinnipeds to sounds produced by 
Shell's proposed exploratory drilling operations in the Chukchi Sea is 
not expected to result in more than Level B harassment of the affected 
species or stock.
    Of the 12 marine mammal species or stocks likely to occur in the 
proposed drilling area, four are listed as endangered under the ESA: 
the bowhead, humpback, fin whales, and ringed seal. All four species 
are also designated as ``depleted'' under the MMPA. Despite these 
designations, the Bering-Chukchi-Beaufort stock of bowheads has been 
increasing at a rate of 3.4% annually for nearly a decade (Allen and 
Angliss, 2011), even in the face of ongoing industrial activity. 
Additionally, during the 2001 census, 121 calves were counted, which 
was the

[[Page 11768]]

highest yet recorded. The calf count provides corroborating evidence 
for a healthy and increasing population (Allen and Angliss, 2011). An 
annual increase of 4.8% was estimated for the period 1987-2003 for 
North Pacific fin whales. While this estimate is consistent with growth 
estimates for other large whale populations, it should be used with 
caution due to uncertainties in the initial population estimate and 
about population stock structure in the area (Allen and Angliss, 2011). 
Zeribini et al. (2006, cited in Allen and Angliss, 2011) noted an 
increase of 6.6% for the Central North Pacific stock of humpback whales 
in Alaska waters. Certain stocks or populations of gray and beluga 
whales and spotted seals are listed as endangered or are proposed for 
listing under the ESA; however, none of those stocks or populations 
occur in the proposed activity area. Ringed seals were recently listed 
under the ESA as threatened species, and are considered depleted under 
the MMPA. On July 25, 2014, the U.S. District Court for the District of 
Alaska vacated NMFS' rule listing the Beringia bearded seal DPS as 
threatened and remanded the rule to NMFS to correct the deficiencies 
identified in the opinion. None of the other species that may occur in 
the project area is listed as threatened or endangered under the ESA or 
designated as depleted under the MMPA. There is currently no 
established critical habitat in the proposed project area for any of 
these 12 species.
    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. Based on the 
vast size of the Arctic Ocean where feeding by marine mammals occurs 
versus the localized area of the drilling program, any missed feeding 
opportunities in the direct project area would be of little 
consequence, as marine mammals would have access to other feeding 
grounds.
    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 Shell's proposed 2015 open-water exploration drilling 
program in the Chukchi Sea will have a negligible impact on the 
affected marine mammal species or stocks.

Small Numbers

    The estimated takes proposed to be authorized represent less than 
1% of the affected population or stock for 6 of the species and less 
than 5.5% for three additional species. The estimated takes for bowhead 
and gray whales and for ringed seals are 13.2%, 13.5%, and 16.8%, 
respectively. These estimates represent the percentage of each species 
or stock that could be taken by Level B behavioral harassment if each 
animal is taken only once.
    The estimated take numbers are likely somewhat of an overestimate 
for several reasons. First, an application of a 1.3 dB safety factor to 
the source level of each continuous sound source prior to sound 
propagation modeling of areas exposed to Level B thresholds, which make 
the effective zones for take calculation larger than they likely would 
be. In addition, Shell applied binning of similar activity scenarios 
into a representative scenario, each of which reflected the largest 
exposed area for a related group of activities. Further, the take 
estimates assume 100% daily turnover of populations, which likely 
overestimates the number of different individuals that would be 
exposed, especially during non-migratory periods. In addition, the take 
estimates assume no avoidance of marine mammals in areas exposed to 
Level B thresholds (with the exception of bowhead whale, for which 50% 
of individuals were assumed to demonstrate avoidance behavior). 
Finally, density estimates for some cetaceans include nearshore areas 
where more individuals would be expected to occur than in the offshore 
Burger Prospect area (e.g., gray whales).
    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 mitigation and monitoring 
measures, NMFS preliminarily finds that small numbers of marine mammals 
will be taken relative to the populations of the affected species or 
stocks.

Impact on Availability of Affected Species or Stock for Taking for 
Subsistence Uses

Relevant Subsistence Uses

    The disturbance and potential displacement of marine mammals by 
sounds from drilling activities are the principal concerns related to 
subsistence use of the area. Subsistence remains the basis for Alaska 
Native culture and community. Marine mammals are legally hunted in 
Alaskan waters by coastal Alaska Natives. In rural Alaska, subsistence 
activities are often central to many aspects of human existence, 
including patterns of family life, artistic expression, and community 
religious and celebratory activities. Additionally, the animals taken 
for subsistence provide a significant portion of the food that will 
last the community throughout the year. The main species that are 
hunted include bowhead and beluga whales, ringed, spotted, and bearded 
seals. The importance of each of these species varies among the 
communities and is largely based on availability.
    The subsistence communities in the Chukchi Sea that have the 
potential to be impacted by Shell's offshore drilling program include 
Point Hope, Point Lay, Wainwright, Barrow, and possibly Kotzebue and 
Kivalina (however, these two communities are much farther to the south 
of the proposed project area).
(1) Bowhead Whales
    Sound energy and general activity associated with drilling and 
operation of vessels and aircraft have the potential to temporarily 
affect the behavior of bowhead whales. Monitoring studies (Davis 1987, 
Brewer et al. 1993, Hall et al. 1994) have documented temporary 
diversions in the swim path of migrating bowheads near drill sites; 
however, the whales have generally been observed to resume their 
initial migratory route within a distance of 6-20 mi (10-32 km). 
Drilling noise has not been shown to block or impede migration even in 
narrow ice leads (Davis 1987, Richardson et al. 1991).
    Behavioral effects on bowhead whales from sound energy produced by 
drilling, such as avoidance, deflection, and changes in surface/dive 
ratios, have generally been found to be limited to areas around the 
drill site that are ensonified to >160 dB re 1 [mu]Pa rms, although 
effects have infrequently been observed out as far as areas ensonified 
to 120 dB re 1 [mu]Pa rms. Ensonification by drilling to levels >120 dB 
re 1 [mu]Pa rms will be limited to areas within about 0.93 mi (1.5 km) 
of either drilling units during Shell's exploration drilling program. 
Shell's proposed drill sites are located more than 64 mi (103 km) from 
the Chukchi Sea coastline, whereas mapping of subsistence use areas 
indicates bowhead hunts are conducted within about 30 mi (48 km) of 
shore; there is therefore little or no opportunity for the proposed 
exploration drilling activities to affect bowhead hunts.
    Vessel traffic along planned travel corridors between the drill 
sites and marine support facilities in Barrow and Wainwright would 
traverse some areas used during bowhead harvests by

[[Page 11769]]

Chukchi villages. Bowhead hunts by residents of Wainwright, Point Hope 
and Point Lay take place almost exclusively in the spring prior to the 
date on which Shell would commence the proposed exploration drilling 
program. From 1984 through 2009, all bowhead harvests by these Chukchi 
Sea villages occurred only between April 14 and June 24 (George and 
Tarpley 1986; George et al. 1987, 1988, 1990, 1992, 1995, 1998, 1999, 
2000; Philo et al. 1994; Suydam et al. 1995, 1996, 1997, 2001, 2002, 
2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010), while Shell will not 
enter the Chukchi Sea prior to July 1. However, fall whaling by some of 
these Chukchi Sea villages has occurred since 2010 and is likely to 
occur in the future, particularly if bowhead quotas are not completely 
filled during the spring hunt, and fall weather is accommodating. A 
Wainwright whaling crew harvested the first fall bowhead for these 
villages in 90 years or more on October 7, 2010, and another in October 
of 2011 (Suydam et al. 2011, 2012, 2013). No bowhead whales were 
harvested during fall in 2012, but 3 were harvested by Wainwright in 
fall 2013.
    Barrow crews have traditionally hunted bowheads during both spring 
and fall; however spring whaling by Barrow crews is normally finished 
before the date on which Shell operations would commence. From 1984 
through 2011 whales were harvested in the spring by Barrow crews only 
between April 23 and June 15 (George and Tarpley 1986; George et al. 
1987, 1988, 1990, 1992, 1995, 1998, 1999, 2000; Philo et al. 1994; 
Suydam et al. 1995, 1996, 1997, 2001, 2002, 2003, 2004, 2005, 2006, 
2007, 2008, 2009, 2010, 2011, 2012, 2103). Fall whaling by Barrow crews 
does take place during the time period when vessels associated with 
Shell's exploration drilling program would be in the Chukchi Sea. From 
1984 through 2011, whales were harvested in the fall by Barrow crews 
between August 31 and October 30, indicating that there is potential 
for vessel traffic to affect these hunts. Most fall whaling by Barrow 
crews, however, takes place east of Barrow along the Beaufort Sea 
coast, therefore providing little opportunity for vessel traffic 
associated with Shell's exploration drilling program to affect them. 
For example, Suydam et al. (2008) reported that in the previous 35 
years, Barrow whaling crews harvested almost all their whales in the 
Beaufort Sea to the east of Point Barrow. Shell's mitigation measures, 
which include a system of Subsistence Advisors (SAs), Community 
Liaisons, and Com Centers, will be implemented to avoid any effects 
from vessel traffic on fall whaling in the Chukchi Sea by Barrow and 
Wainwright.
    Aircraft traffic (helicopters and small fixed wing airplanes) 
between the drill sites and facilities in Wainwright and Barrow would 
also traverse these subsistence areas. Flights between the drill sites 
and Wainwright or other shoreline locations would take place after the 
date on which spring bowhead whaling out of Point Hope, Point Lay, and 
Wainwright is typically finished for the year; however, Wainwright has 
harvested bowheads in the fall since 2010 and aircraft may traverse 
areas sometimes utilized for these fall hunts. Aircraft overflights 
between the drill sites and Barrow or other shoreline locations could 
also occur over areas used by Barrow crews during fall whaling, but 
again, most fall whaling by Barrow crews takes place to the east of 
Barrow in the Beaufort Sea. The most commonly observed reactions of 
bowheads to aircraft traffic are hasty dives, but changes in 
orientation, dispersal, and changes in activity are sometimes noted. 
Such reactions could potentially affect subsistence hunts if the 
flights occurred near and at the same time as the hunt, but Shell has 
developed and proposes to implement a number of mitigation measures to 
avoid such impacts. These mitigation measures include minimum flight 
altitudes, employment of SAs, and Com Centers. Twice-daily calls are 
held during the exploration drilling program and are attended by 
operations staff, logistics staff, and SAs. Vessel movements and 
aircraft flights are adjusted as needed and planned in a manner that 
avoids potential impacts to bowhead whale hunts and other subsistence 
activities.
(2) Beluga Whale
    Beluga whales typically do not represent a large proportion of the 
subsistence harvests by weight in the communities of Wainwright and 
Barrow, the nearest communities to Shell's planned exploration drilling 
program. Barrow residents hunt beluga in the spring (normally after the 
bowhead hunt) in leads between Point Barrow and Skull Cliffs in the 
Chukchi Sea, primarily in April-June and later in the summer (July-
August) on both sides of the barrier island in Elson Lagoon/Beaufort 
Sea (Minerals Management Service [MMS] 2008), but harvest rates 
indicate the hunts are not frequent. Wainwright residents hunt beluga 
in April-June in the spring lead system, but this hunt typically occurs 
only if there are no bowheads in the area. Communal hunts for beluga 
are conducted along the coastal lagoon system later in July-August.
    Belugas typically represent a much greater proportion of the 
subsistence harvest in Point Lay and Point Hope. Point Lay's primary 
beluga hunt occurs from mid-June through mid-July, but can sometimes 
continue into August if early success is not sufficient. Point Hope 
residents hunt beluga primarily in the lead system during the spring 
(late March to early June) bowhead hunt, but also in open water along 
the coastline in July and August. Belugas are harvested in coastal 
waters near these villages, generally within a few miles from shore. 
Shell's proposed drill sites are located more than 60 mi (97 km) 
offshore, therefore proposed exploration drilling in the Burger 
Prospect would have no or minimal impacts on beluga hunts. Aircraft and 
vessel traffic between the drill sites and support facilities in 
Wainwright, and aircraft traffic between the drill sites and air 
support facilities in Barrow, would traverse areas that are sometimes 
used for subsistence hunting of belugas.
    Disturbance associated with vessel and aircraft traffic could 
therefore potentially affect beluga hunts. However, all of the beluga 
hunt by Barrow residents in the Chukchi Sea, and much of the hunt by 
Wainwright residents, would likely be completed before Shell activities 
would commence. Additionally, vessel and aircraft traffic associated 
with Shell's planned exploration drilling program will be restricted 
under normal conditions to designated corridors that remain onshore or 
proceed directly offshore thereby minimizing the amount of traffic in 
coastal waters where beluga hunts take place. The designated vessel and 
aircraft traffic corridors do not traverse areas indicated in recent 
mapping as utilized by Point Lay or Point Hope for beluga hunts, and 
avoids important beluga hunting areas in Kasegaluk Lagoon that are used 
by Wainwright. Shell has developed and proposes to implement a number 
of mitigation measures, e.g., PSOs on board vessels, minimum flight 
altitudes, and the SA and Com Center programs, to ensure that there is 
no impact on the availability of the beluga whale as a subsistence 
resource.
(3) Pinnipeds
    Seals are an important subsistence resource and ringed seals make 
up the bulk of the seal harvest. Most ringed and bearded seals are 
harvested in the winter or in the spring before Shell's exploration 
drilling program would

[[Page 11770]]

commence, but some harvest continues during open water and could 
possibly be affected by Shell's planned activities. Spotted seals are 
also harvested during the summer. Most seals are harvested in coastal 
waters, with available maps of recent and past subsistence use areas 
indicating seal harvests have occurred only within 30-40 mi (48-64 km) 
of the coastline. Shell's planned drill sites are located more than 64 
statute mi (103 km) offshore, so activities within the Burger Prospect, 
such as drilling, would have no impact on subsistence hunting for 
seals. Helicopter traffic between land and the offshore exploration 
drilling operations could potentially disturb seals and, therefore, 
subsistence hunts for seals, but any such effects would be minor and 
temporary lasting only minutes after the flight has passed due to the 
small number of flights and the altitude at which they typically fly, 
and the fact that most seal hunting is done during the winter and 
spring when the exploration drilling program is not operational. 
Mitigation measures to be implemented by Shell include minimum flight 
altitudes, employment of subsistence advisors in the villages, and 
operation of Com Centers.

Potential Impacts to Subsistence Uses

    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.
    Noise and general activity during Shell's proposed drilling program 
have the potential to impact marine mammals hunted by Native Alaskans. 
In the case of cetaceans, the most common reaction to anthropogenic 
sounds (as noted previously in this document) is avoidance of the 
ensonified area. In the case of bowhead whales, this often means that 
the animals divert from their normal migratory path by several 
kilometers. Helicopter activity also has the potential to disturb 
cetaceans and pinnipeds by causing them to vacate the area. 
Additionally, general vessel presence in the vicinity of traditional 
hunting areas could negatively impact a hunt. Native knowledge 
indicates that bowhead whales become increasingly ``skittish'' in the 
presence of seismic noise. Whales are more wary around the hunters and 
tend to expose a much smaller portion of their back when surfacing 
(which makes harvesting more difficult). Additionally, natives report 
that bowheads exhibit angry behaviors in the presence of seismic 
activity, such as tail-slapping, which translate to danger for nearby 
subsistence harvesters. Only limited seismic activity is planned in the 
vicinity of the drill units in 2015.

Plan of Cooperation or Measures To Minimize Impacts to Subsistence 
Hunts

    Regulations at 50 CFR 216.104(a)(12) require IHA applicants for 
activities that take place in Arctic waters to provide a Plan of 
Cooperation (POC) or information that identifies what measures have 
been taken and/or will be taken to minimize adverse effects on the 
availability of marine mammals for subsistence purposes.
    Shell has prepared and will implement a POC pursuant to BOEM Lease 
Sale Stipulation No. 5, which requires that all exploration operations 
be conducted in a manner that prevents unreasonable conflicts between 
oil and gas activities and the subsistence activities and resources of 
residents of the North Slope. This stipulation also requires adherence 
to USFWS and NMFS regulations, which require an operator to implement a 
POC to mitigate the potential for conflicts between the proposed 
activity and traditional subsistence activities (50 CFR 18.124(c)(4) 
and 50 CFR 216.104(a)(12)). A POC was prepared and submitted with the 
initial Chukchi Sea EP that was submitted to BOEM in May 2009, and 
approved on 7 December 2009. Subsequent POC Addendums were submitted in 
May 2011 with a revised Chukchi Sea EP and the IHA application for the 
2012 exploration drilling program. For this IHA application, Shell has 
again updated the POC Addendum. The POC Addendum has been updated to 
include documentation of meetings undertaken to specifically gather 
feedback from stakeholder communities on Shell's implementation of the 
Chukchi Sea exploration drilling program during 2012, plus inform and 
obtain their input regarding the continuation of the program with the 
addition of a second drilling unit, additional vessels and aircraft.
    The POC Addendum identifies the measures that Shell has developed 
in consultation with North Slope subsistence communities to minimize 
any adverse effects on the availability of marine mammals for 
subsistence uses and will implement during its planned Chukchi Sea 
exploration drilling program for the summer of 2015. In addition, the 
POC Addendum details Shell's communications and consultations with 
local subsistence communities concerning its planned exploration 
drilling program, potential conflicts with subsistence activities, and 
means of resolving any such conflicts (50 CFR 18.128(d) and 50 CFR 
216.104(a) (12) (i), (ii), (iv)). Shell has documented its contacts 
with the North Slope subsistence communities, as well as the substance 
of its communications with subsistence stakeholder groups.
    The POC Addendum report (Attachment C of the IHA application) 
provides a list of public meetings attended by Shell since 2012 to 
develop the POC and the POC Addendum. The POC Addendum is updated 
through July 2015, and includes sign-in sheets and presentation 
materials used at the POC meetings held in 2014 to present the 2015 
Chukchi Sea exploration drilling information. Comment analysis tables 
for numerous meetings held during 2014 summarize feedback from the 
communities on Shell's 2015 exploration drilling and planned activities 
beginning in the summer of 2015.
    The following mitigation measures, plans and programs, are integral 
to this POC and were developed during Shell's consultation with 
potentially affected subsistence groups and communities. These 
measures, plans, and programs to monitor and mitigate potential impacts 
to subsistence users and resources will be implemented by Shell during 
its exploration drilling operations in the Chukchi Sea. The mitigation 
measures Shell has adopted and will implement during its Chukchi Sea 
exploration drilling operations are listed and discussed below. These 
mitigation measures reflect Shell's experience conducting exploration 
activities in the Alaska Arctic OCS since the 1980s and its ongoing 
efforts to engage with local subsistence communities to better 
understand their concerns and develop appropriate and effective 
mitigation measures to address those concerns. This most recent version 
of Shell's planned mitigation measures was presented to community 
leaders and subsistence user groups starting in January 2009 and has 
evolved since in response to information learned during the 
consultation process.
    To minimize any cultural or resource impacts from its exploration 
operations, Shell will continue to implement the following additional 
measures to ensure coordination of its activities with local 
subsistence users to minimize further the risk of impacting marine 
mammals

[[Page 11771]]

and interfering with the subsistence hunt:
(1) Communications
    <bullet> Shell has developed a Communication Plan and will 
implement this plan before initiating exploration drilling operations 
to coordinate activities with local subsistence users, as well as 
Village Whaling Captains' Associations, to minimize the risk of 
interfering with subsistence hunting activities, and keep current as to 
the timing and status of the bowhead whale hunt and other subsistence 
hunts. The Communication Plan includes procedures for coordination with 
Com Centers to be located in coastal villages along the Chukchi Sea 
during Shell's proposed exploration drilling activities.
    <bullet> Shell will employ local SAs from the Chukchi Sea villages 
that are potentially impacted by Shell's exploration drilling 
activities. The SAs will provide consultation and guidance regarding 
the whale migration and subsistence activities. There will be one per 
village, working approximately 8-hr per day and 40-hr per week during 
each drilling season. The subsistence advisor will use local knowledge 
(Traditional Knowledge) to gather data on subsistence lifestyle within 
the community and provide advice on ways to minimize and mitigate 
potential negative impacts to subsistence resources during each 
drilling season. Responsibilities include reporting any subsistence 
concerns or conflicts; coordinating with subsistence users; reporting 
subsistence-related comments, concerns, and information; coordinating 
with the Com and Call Center personnel; and advising how to avoid 
subsistence conflicts.
(2) Aircraft Travel
    <bullet> Aircraft over land or sea shall not operate below 1,500 
ft. (457 m) altitude unless engaged in marine mammal monitoring, 
approaching, landing or taking off, in poor weather (fog or low 
ceilings), or in an emergency situation.
    <bullet> Aircraft engaged in marine mammal monitoring shall not 
operate below 1,500 ft. (457 m) in areas of active whaling; such areas 
to be identified through communications with the Com Centers.
(3) Vessel Travel
    <bullet> The drilling unit(s) and support vessels will enter the 
Chukchi Sea through the Bering Strait on or after 1 July, minimizing 
effects on marine mammals and birds that frequent open leads and 
minimizing effects on spring and early summer bowhead whale hunting.
    <bullet> The transit route for the drilling unit(s) and drilling 
support fleets will avoid known fragile ecosystems and the Ledyard Bay 
Critical Habitat Unit (LBCHU), and will include coordination through 
Com Centers.
    <bullet> PSOs will be aboard the drilling unit(s) and transiting 
support vessels.
    <bullet> When within 900 ft (274 m) of whales, vessels will reduce 
speed, avoid separating members from a group and avoid multiple changes 
of direction.
    <bullet> Vessel speed will be reduced during inclement weather 
conditions in order to avoid collisions with marine mammals.
    <bullet> Shell will communicate and coordinate with the Com Centers 
regarding all vessel transit.
(4) ZVSP
    <bullet> Airgun arrays will be ramped up slowly during ZVSPs to 
warn cetaceans and pinnipeds in the vicinity of the airguns and provide 
time for them to leave the area and avoid potential injury or 
impairment of their hearing abilities. Ramp ups from a cold start when 
no airguns have been firing will begin by firing a single airgun in the 
array. A ramp up to the required airgun array volume will not begin 
until there has been a minimum of 30 min of observation of the safety 
zone by PSOs to assure that no marine mammals are present. The safety 
zone is the extent of the 180 dB radius for cetaceans and 190 dB re 1 
[mu]Pa rms for pinnipeds. The entire safety zone must be visible during 
the 30-min lead-into an array ramp up. If a marine mammal(s) is sighted 
within the safety zone during the 30-min watch prior to ramp up, ramp 
up will be delayed until the marine mammal(s) is sighted outside of the 
safety zone or the animal(s) is not sighted for at least 15-30 min: 15 
min for small odontocetes and pinnipeds, or 30 min for baleen whales 
and large odontocetes.
(5) Ice Management
    <bullet> Real time ice and weather forecasting will be from SIWAC.
(6) Oil Spill Response
    <bullet> Pre-booming is required for all fuel transfers between 
vessels.
    The potentially affected subsistence communities, identified in 
BOEM Lease Sale, that were consulted regarding Shell's exploration 
drilling activities include: Barrow, Wainwright, Point Lay, Point Hope, 
Kotzebue, and Deering. Additionally, Shell has met with subsistence 
groups including the Alaska Eskimo Whaling Commission (AEWC), Inupiat 
Community of the Arctic Slope (ICAS), and the Native Village of Barrow, 
and presented information regarding the proposed activities to the 
North Slope Borough (NSB) and Northwest Arctic Borough (NWAB) 
Assemblies, and NSB and NWAB Planning Commissions during 2014. In July 
2014, Shell conducted POC meetings in Chukchi villages to present 
information on the proposed 2015 drilling season. Shell has 
supplemented the IHA application with a POC addendum to incorporate 
these POC visits. Throughout 2014 and 2015 Shell anticipates continued 
engagement with the marine mammal commissions and committees active in 
the subsistence harvests and marine mammal research.
    Shell continues to meet each year with the commissioners and 
committee heads of AEWC, Alaska Beluga Whale Committee, the Nanuuq 
Commission, Eskimo Walrus Commission, and Ice Seal Committee jointly in 
co-management meetings. Shell held individual consultation meetings 
with representatives from the various marine mammal commissions to 
discuss the planned Chukchi exploration drilling program. Following the 
drilling season, Shell will have a post-season co-management meeting 
with the commissioners and committee heads to discuss results of 
mitigation measures and outcomes of the preceding season. The goal of 
the post-season meeting is to build upon the knowledge base, discuss 
successful or unsuccessful outcomes of mitigation measures, and 
possibly refine plans or mitigation measures if necessary.
    Shell attended the 2012-2014 Conflict Avoidance Agreement (CAA) 
negotiation meetings in support of exploration drilling, offshore 
surveys, and future drilling plans. Shell will do the same for the 
upcoming 2015 exploration drilling program. Shell states that it is 
committed to a CAA process and will make a good-faith effort to 
negotiate an agreement every year it has planned activities.

Unmitigable Adverse Impact Analysis and Preliminary Determination

    NMFS considers that these mitigation measures including measures to 
reduce overall impacts to marine mammals in the vicinity of the 
proposed exploration drilling area and measures to mitigate any 
potential adverse effects on subsistence use of marine mammals are 
adequate to ensure subsistence use of marine mammals in the vicinity of 
Shell's proposed exploration drilling program in the Chukchi Sea.
    Based on the description of the specified activity, the measures 
described to minimize adverse effects

[[Page 11772]]

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 Shell's proposed activities.

Endangered Species Act (ESA)

    There are four marine mammal species listed as endangered under the 
ESA with confirmed or possible occurrence in the proposed project area: 
The bowhead, humpback, and fin whales, and ringed seals. NMFS' Permits 
and Conservation Division will initiate consultation with NMFS' 
Endangered Species Division under section 7 of the ESA on the issuance 
of an IHA to Shell under section 101(a)(5)(D) of the MMPA for this 
activity. Consultation will be concluded prior to a determination on 
the issuance of an IHA.

National Environmental Policy Act (NEPA)

    NMFS is preparing an Environmental Assessment (EA), pursuant to 
NEPA, to determine whether the issuance of an IHA to Shell for its 2015 
drilling activities may have a significant impact on the human 
environment. NMFS has released a draft of the EA for public comment 
along with this proposed IHA.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to Shell for conducting an exploration drilling program in 
the Chukchi Sea during the 2015 Arctic open-water season, provided the 
previously mentioned mitigation, monitoring, and reporting requirements 
are incorporated. The proposed IHA language is provided next.
    This section contains a draft of the IHA itself. The wording 
contained in this section is proposed for inclusion in the IHA (if 
issued).
    (1) This Authorization is valid from July 1, 2015, through October 
31, 2015.
    (2) This Authorization is valid only for activities associated with 
Shell's 2015 Chukchi Sea exploration drilling program. The specific 
areas where Shell's exploration drilling program will be conducted are 
within Shell lease holdings in the Outer Continental Shelf Lease Sale 
193 area in the Chukchi Sea.
    (3)(a) The incidental taking of marine mammals, by Level B 
harassment only, is limited to the following species: bowhead whale; 
gray whale; beluga whale; minke whale; fin whale; humpback whale; 
killer whale; harbor porpoise; ringed seal; bearded seal; spotted seal; 
and ribbon seal.
    (3)(b) The taking by injury (Level A harassment), serious injury, 
or death of any of the species listed in Condition 3(a) or the taking 
of any kind of any other species of marine mammal is prohibited and may 
result in the modification, suspension or revocation of this 
Authorization.
    (4) The authorization for taking by harassment is limited to the 
following acoustic sources (or sources with comparable frequency and 
intensity) and from the following activities:
    (a) a three-airgun array consisting of three 150 in\3\ airguns, or 
a two-airgun array consisting of two 250 in\3\ airguns;
    (b) continuous drilling unit and associated dynamic positioning 
sounds during active drilling operations;
    (c) vessel sounds generated during active ice management or 
icebreaking;
    (d) mudline cellar construction during the exploration drilling 
program;
    (e) anchor handling during the exploration drilling program, and
    (f) aircraft associated with marine mammal monitoring and support 
operations,
    (5) The taking of any marine mammal in a manner prohibited under 
this Authorization must be reported immediately to the Chief, Permits 
and Conservation Division, Office of Protected Resources, NMFS or her 
designee.
    (6) The holder of this Authorization must notify the Chief of the 
Permits and Conservation Division, Office of Protected Resources, at 
least 48 hours prior to the start of exploration drilling activities 
(unless constrained by the date of issuance of this Authorization in 
which case notification shall be made as soon as possible).
    (7) General Mitigation and Monitoring Requirements: The Holder of 
this Authorization is required to implement the following mitigation 
and monitoring requirements when conducting the specified activities to 
achieve the least practicable impact on affected marine mammal species 
or stocks:
    (a) All vessels shall reduce speed to a maximum of 5 knots when 
within 900 ft (300 yards/274 m) of whales. Those vessels capable of 
steering around such groups should do so. Vessels may not be operated 
in such a way as to separate members of a group of whales from other 
members of the group;
    (b) Avoid multiple changes in direction and speed when within 900 
ft (300 yards/274 m) of whales;
    (c) When weather conditions require, such as when visibility drops, 
support vessels must reduce speed and change direction, as necessary 
(and as operationally practicable), to avoid the likelihood of injury 
to whales;
    (d) Aircraft shall not fly within 1,000 ft (305 m) of marine 
mammals or below 1,500 ft (457 m) altitude (except during takeoffs, 
landings, or in emergency situations) while over land or sea;
    (e) Utilize two, NMFS-approved, vessel-based Protected Species 
Observers (PSOs) (except during meal times and restroom breaks, when at 
least one PSO shall be on watch) to visually watch for and monitor 
marine mammals near the drilling units or support vessel during active 
drilling or airgun operations (from nautical twilight-dawn to nautical 
twilight-dusk) and before and during start-ups of airguns day or night. 
The vessels' crew shall also assist in detecting marine mammals, when 
practicable. PSOs shall have access to reticle binoculars (7x50 
Fujinon), big-eye binoculars (25x150), and night vision devices. PSO 
shifts shall last no longer than 4 consecutive hours and shall not be 
on watch more than 12 hours in a 24-hour period. PSOs shall also make 
observations during daytime periods when active operations are not 
being conducted for comparison of animal abundance and behavior, when 
feasible;
    (f) When a mammal sighting is made, the following information about 
the sighting will be recorded by the PSOs:
    (i) 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, etc.), 
closest point of approach, and behavioral pace;
    (ii) Time, location, speed, activity of the vessel, sea state, ice 
cover, visibility, and sun glare; and
    (iii) The positions of other vessel(s) in the vicinity of the PSO 
location.
    (iv) The ship's position, speed of support vessels, and water 
temperature, 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.
    (g) PSO teams shall consist of Alaska Native observers and 
experienced field biologists. An experienced field crew leader will 
supervise the PSO team onboard the survey vessel. New observers shall 
be paired with experienced observers to avoid situations where lack of 
experience impairs the quality of observations;
    (h) PSOs will complete a two or three-day training session on 
marine mammal monitoring, to be conducted shortly

[[Page 11773]]

before the anticipated start of the 2015 open-water season. The 
training session(s) will be conducted by qualified marine mammalogists 
with extensive crew-leader experience during previous vessel-based 
monitoring programs. A marine mammal observers' handbook, adapted for 
the specifics of the planned program, will be reviewed as part of the 
training;
    (i) PSO training that is conducted prior to the start of the survey 
activities shall be conducted with both Alaska Native PSOs and 
biologist PSOs being trained at the same time in the same room. There 
shall not be separate training courses for the different PSOs; and
    (j) PSOs shall be trained using visual aids (e.g., videos, photos), 
to help them identify the species that they are likely to encounter in 
the conditions under which the animals will likely be seen.
    (8) ZVSP Mitigation and Monitoring Measures: The Holder of this 
Authorization is required to implement the following mitigation and 
monitoring requirements when conducting the specified activities to 
achieve the least practicable impact on affected marine mammal species 
or stocks:
    (a) PSOs shall conduct monitoring while the airgun array is being 
deployed or recovered from the water;
    (b) PSOs shall visually observe the entire extent of the exclusion 
zone (EZ) (180 dB re 1 [mu]Pa [rms] for cetaceans and 190 dB re 1 
[mu]Pa [rms] for pinnipeds) using NMFS-qualified PSOs, for at least 30 
minutes (min) prior to starting the airgun array (day or night). If the 
PSO finds a marine mammal within the EZ, Shell must delay the seismic 
survey until the marine mammal(s) has left the area. If the PSO sees a 
marine mammal that surfaces then dives below the surface, the PSO shall 
continue the watch for 30 min. If the PSO sees no marine mammals during 
that time, they may assume that the animal has moved beyond the EZ. If 
for any reason the entire radius cannot be seen for the entire 30 min 
period (i.e., rough seas, fog, darkness), or if marine mammals are 
near, approaching, or in the EZ, the airguns may not be ramped-up. If 
one airgun is already running at a source level of at least 180 dB re 1 
[mu]Pa (rms), the Holder of this Authorization may start the second 
airgun without observing the entire EZ for 30 min prior, provided no 
marine mammals are known to be near the EZ;
    (c) Establish and monitor a 180 dB re 1 [mu]Pa (rms) and a 190 dB 
re 1 [mu]Pa (rms) EZ for marine mammals before the airgun array is in 
operation. Before the field verification tests, described in condition 
10(c)(i) below, the 180 dB radius is temporarily designated to be 1.28 
km and the 190 dB radius is temporarily designated to be 255 m;
    (d) Implement a ``ramp-up'' procedure when starting up at the 
beginning of seismic operations. During ramp-up, the PSOs shall monitor 
the EZ, and if marine mammals are sighted, a power-down, or shut-down 
shall be implemented as though the full array were operational. 
Therefore, initiation of ramp-up procedures from shut-down requires 
that the PSOs be able to view the full EZ;
    (e) Power-down or shutdown the airgun(s) if a marine mammal is 
detected within, approaches, or enters the relevant EZ. A shutdown 
means all operating airguns are shutdown (i.e., turned off). A power-
down means reducing the number of operating airguns to a single 
operating airgun, which reduces the EZ to the degree that the animal(s) 
is no longer in or about to enter it;
    (f) Following a power-down, if the marine mammal approaches the 
smaller designated EZ, the airguns must then be completely shutdown. 
Airgun activity shall not resume until the PSO has visually observed 
the marine mammal(s) exiting the EZ and is not likely to return, or has 
not been seen within the EZ for 15 min for species with shorter dive 
durations (small odontocetes and pinnipeds) or 30 min for species with 
longer dive durations (mysticetes);
    (g) Following a power-down or shut-down and subsequent animal 
departure, airgun operations may resume following ramp-up procedures 
described in Condition 8(d) above;
    (h) ZVSP surveys may continue into night and low-light hours if 
such segment(s) of the survey is initiated when the entire relevant EZs 
are visible and can be effectively monitored; and
    (i) No initiation of airgun array operations is permitted from a 
shutdown position at night or during low-light hours (such as in dense 
fog or heavy rain) when the entire relevant EZ cannot be effectively 
monitored by the PSO(s) on duty.
    (9) Subsistence Mitigation Measures: To ensure no unmitigable 
adverse impact on subsistence uses of marine mammals, the Holder of 
this Authorization shall:
    (b) Not enter the Bering Strait prior to July 1 to minimize effects 
on spring and early summer whaling;
    (c) Implement the Communication Plan before initiating exploration 
drilling operations to coordinate activities with local subsistence 
users and Village Whaling Associations in order to minimize the risk of 
interfering with subsistence hunting activities;
    (d) Participate in the Com Center Program. The Com Centers shall 
operate 24 hours/day during the 2015 bowhead whale hunt;
    (e) Employ local Subsistence Advisors (SAs) from the Chukchi Sea 
villages to provide consultation and guidance regarding the whale 
migration and subsistence hunt;
    (f) Not operate aircraft below 1,500 ft (457 m) unless engaged in 
marine mammal monitoring, approaching, landing or taking off, or unless 
engaged in providing assistance to a whaler or in poor weather (low 
ceilings) or any other emergency situations;
    (10) Monitoring Measures:
    (a) Vessel-based Monitoring: The Holder of this Authorization shall 
designate biologically-trained PSOs to be aboard the drilling units and 
all transiting support vessels. The PSOs are required to monitor for 
marine mammals in order to implement the mitigation measures described 
in conditions 7 and 8 above;
    (b) Aerial Survey Monitoring: The Holder of this Authorization must 
implement the aerial survey monitoring program detailed in its Marine 
Mammal Mitigation and Monitoring Plan (4MP); and
    (c) Acoustic Monitoring:
    (i) Field Source Verification: the Holder of this Authorization is 
required to conduct sound source verification tests for the drilling 
units, support vessels, and the airgun array not measured in previous 
seasons. Sound source verification shall consist of distances where 
broadside and endfire directions at which broadband received levels 
reach 190, 180, 170, 160, and 120 dB re 1 [mu]Pa (rms) for all active 
acoustic sources that may be used during the activities. For the airgun 
array, the configurations shall include at least the full array and the 
operation of a single source that will be used during power downs. The 
test results for the airgun array shall be reported to NMFS within 5 
days of completing the test.
    A report of the acoustic verification measurements of the ZVSP 
airgun array will be submitted within 120 hr after collection and 
analysis of those measurements once that part of the program is 
implemented. The ZVSP acoustic array report will specify the distances 
of the exclusion zones that were adopted for the ZVSP program. Prior to 
completion of these measurements, Shell will use the radii in condition 
8(c).
    (ii) Acoustic ``Net'' Array: Deploy acoustic recorders widely 
across the U.S. Chukchi Sea and on the prospect in order to gain 
information on the distribution of marine mammals in the

[[Page 11774]]

region. This program must be implemented as detailed in the 4MP.
    (11) Reporting Requirements: The Holder of this Authorization is 
required to:
    (a) Within 5 days of completing the sound source verification tests 
for the airguns, the Holder shall submit a preliminary report of the 
results to NMFS. A report on the results of the acoustic verification 
measurements of the drilling units and support vessels, not recorded in 
previous seasons, will be reported in the 90-day report. The report 
should report down to the 120-dB radius in 10-dB increments;
    (b) Submit a draft report on all activities and monitoring results 
to the Office of Protected Resources, NMFS, within 90 days of the 
completion of the exploration drilling program. This report must 
contain and summarize the following information:
    (i) 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);
    (ii) Sound source verification results for drilling units and 
vessels recorded in 2015;
    (iii) Analyses of the effects of various factors influencing 
detectability of marine mammals (e.g., sea state, number of observers, 
and fog/glare);
    (iv) Species composition, occurrence, and distribution of marine 
mammal sightings, including date, water depth, numbers, age/size/gender 
categories (if determinable), group sizes, and ice cover;
    (v) Sighting rates of marine mammals during periods with and 
without exploration drilling activities (and other variables that could 
affect detectability), such as: (A) Initial sighting distances versus 
drilling state; (B) closest point of approach versus drilling state; 
(C) observed behaviors and types of movements versus drilling state; 
(D) numbers of sightings/individuals seen versus drilling state; (E) 
distribution around the survey vessel versus drilling state; and (F) 
estimates of take by harassment;
    (v) Reported results from all hypothesis tests should include 
estimates of the associated statistical power when practicable;
    (vi) Estimate and report uncertainty in all take estimates. 
Uncertainty could be expressed by the presentation of confidence 
limits, a minimum-maximum, posterior probability distribution, etc.; 
the exact approach will be selected based on the sampling method and 
data available;
    (vii) The report should clearly compare authorized takes to the 
level of actual estimated takes;
    (viii) If, changes are made to the monitoring program after the 
independent monitoring plan peer review, those changes must be detailed 
in the report.
    (c) The draft report will be subject to review and comment by NMFS. 
Any recommendations made by NMFS must be addressed in the final report 
prior to acceptance by NMFS. The draft report will be considered the 
final report for this activity under this Authorization if NMFS has not 
provided comments and recommendations within 90 days of receipt of the 
draft report.
    (d) A draft comprehensive report describing the aerial, acoustic, 
and vessel-based monitoring programs will be prepared and submitted 
within 240 days of the date of this Authorization. The comprehensive 
report will describe the methods, results, conclusions and limitations 
of each of the individual data sets in detail. The report will also 
integrate (to the extent possible) the studies into a broad based 
assessment of all industry activities and their impacts on marine 
mammals in the Arctic Ocean during 2015.
    (e) The draft comprehensive report will be subject to review and 
comment by NMFS, the Alaska Eskimo Whaling Commission, and the North 
Slope Borough Department of Wildlife Management. The draft 
comprehensive report will be accepted by NMFS as the final 
comprehensive report upon incorporation of comments and 
recommendations.
    (12)(a) In the unanticipated event that the drilling program 
operation clearly causes the take of a marine mammal in a manner 
prohibited by this Authorization, such as an injury (Level A 
harassment), serious injury or mortality (e.g., ship-strike, gear 
interaction, and/or entanglement), Shell shall immediately cease 
operations and immediately report the incident to the Chief of the 
Permits and Conservation Division, Office of Protected Resources, NMFS, 
by phone or email and the Alaska Regional Stranding Coordinators. The 
report must include the following information: (i) Time, date, and 
location (latitude/longitude) of the incident; (ii) the name and type 
of vessel involved; (iii) the vessel's speed during and leading up to 
the incident; (iv) description of the incident; (v) status of all sound 
source use in the 24 hours preceding the incident; (vi) water depth; 
(vii) environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, and visibility); (viii) description of 
marine mammal observations in the 24 hours preceding the incident; (ix) 
species identification or description of the animal(s) involved; (x) 
the fate of the animal(s); (xi) and photographs or video footage of the 
animal (if equipment is available).
    Activities shall not resume until NMFS is able to review the 
circumstances of the prohibited take. NMFS shall work with Shell to 
determine what is necessary to minimize the likelihood of further 
prohibited take and ensure MMPA compliance. Shell may not resume their 
activities until notified by NMFS via letter, email, or telephone.
    (b) In the event that Shell discovers an injured or dead marine 
mammal, and the lead PSO determines that the cause of the injury or 
death is unknown and the death is relatively recent (i.e., in less than 
a moderate state of decomposition as described in the next paragraph), 
Shell will immediately report the incident to the Chief of the Permits 
and Conservation Division, Office of Protected Resources, NMFS, by 
phone or email and the NMFS Alaska Stranding Hotline and/or by email to 
the Alaska Regional Stranding Coordinators. The report must include the 
same information identified in Condition 12(a) above. Activities may 
continue while NMFS reviews the circumstances of the incident. NMFS 
will work with Shell to determine whether modifications in the 
activities are appropriate.
    (c) In the event that Shell discovers an injured or dead marine 
mammal, and the lead PSO determines that the injury or death is not 
associated with or related to the activities authorized in Condition 2 
of this Authorization (e.g., previously wounded animal, carcass with 
moderate to advanced decomposition, or scavenger damage), Shell shall 
report the incident to the Chief of the Permits and Conservation 
Division, Office of Protected Resources, NMFS, by phone or email and 
the NMFS Alaska Stranding Hotline and/or by email to the Alaska 
Regional Stranding Coordinators, within 24 hours of the discovery. 
Shell shall provide photographs or video footage (if available) or 
other documentation of the stranded animal sighting to NMFS and the 
Marine Mammal Stranding Network. Activities may continue while NMFS 
reviews the circumstances of the incident.
    (13) Activities related to the monitoring described in this 
Authorization do not require a separate scientific research permit 
issued under section 104 of the Marine Mammal Protection Act.
    (14) The Plan of Cooperation outlining the steps that will be taken 
to

[[Page 11775]]

cooperate and communicate with the native communities to ensure the 
availability of marine mammals for subsistence uses must be 
implemented.
    (15) Shell is required to comply with the Terms and Conditions of 
the Incidental Take Statement (ITS) corresponding to NMFS's Biological 
Opinion issued to NMFS's Office of Protected Resources.
    (16) A copy of this Authorization and the ITS must be in the 
possession of all contractors and PSOs operating under the authority of 
this Incidental Harassment Authorization.
    (17) Penalties and Permit Sanctions: Any person who violates any 
provision of this Incidental Harassment Authorization is subject to 
civil and criminal penalties, permit sanctions, and forfeiture as 
authorized under the MMPA.
    (18) This Authorization may be modified, suspended or withdrawn if 
the Holder fails to abide by the conditions prescribed herein or if the 
authorized taking is having more than a negligible impact on the 
species or stock of affected marine mammals, or if there is an 
unmitigable adverse impact on the availability of such species or 
stocks for subsistence uses.

Request for Public Comment

    As noted above, NMFS requests comment on our analysis, the draft 
authorization, and any other aspect of the Notice of Proposed IHA for 
Shell's 2015 Chukchi Sea exploratory drilling program. Please include, 
with your comments, any supporting data or literature citations to help 
inform our final decision on Shell's request for an MMPA authorization.

    Dated: February 26, 2015.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2015-04427 Filed 3-3-15; 8:45 am]
BILLING CODE 3510-22-P


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