[Federal Register Volume 76, Number 217 (Wednesday, November 9, 2011)]
[Notices]
[Pages 69958-70008]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-28914]



[[Page 69957]]

Vol. 76

Wednesday,

No. 217

November 9, 2011

Part VI





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. 76 , No. 217 / Wednesday, November 9, 2011 / 
Notices  

[[Page 69958]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XA811


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 Offshore 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 December 
9, 2011.

ADDRESSES: Comments on the application should be addressed to Michael 
Payne, 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 [email protected]. 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 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: Candace Nachman, 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.
    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.''
    Section 101(a)(5)(D) of the MMPA established an expedited process 
by which citizens of the U.S. can apply for an authorization to 
incidentally take small numbers of marine mammals by harassment. 
Section 101(a)(5)(D) establishes a 45-day time limit for NMFS review of 
an application followed by a 30-day public notice and comment period on 
any proposed authorizations for the incidental harassment of marine 
mammals. Within 45 days of the close of the comment period, NMFS must 
either issue or deny the authorization.
    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

    NMFS received an application on June 30, 2011, from Shell for the 
taking, by harassment, of marine mammals incidental to offshore 
exploration drilling on OCS leases in the Chukchi Sea, Alaska. NMFS 
reviewed Shell's application and identified a number of issues 
requiring further clarification. After addressing comments from NMFS, 
Shell modified its application and submitted a revised application on 
September 12, 2011. NMFS carefully evaluated Shell's application, 
including their analyses, and determined that the application is 
complete. The September 12, 2011, application is the one available for 
public comment (see ADDRESSES) and considered by NMFS for this proposed 
IHA.
    Shell plans to drill up to three exploration wells at three 
possible drill sites and potentially a partial well at a fourth drill 
site on OCS leases offshore in the Chukchi Sea, Alaska, during the 2012 
Arctic open-water season (July through October). Impacts to marine 
mammals may occur from noise produced by the drillship, zero-offset 
vertical seismic profile (ZVSP) surveys, and supporting vessels 
(including icebreakers) and aircraft. 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 
include: 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).

Description of the Specified Activity and Specified Geographic Region

    Shell plans to conduct an offshore exploration drilling program on 
U.S. Department of the Interior, Bureau of Ocean Energy Management 
(BOEM, formerly the Minerals Management

[[Page 69959]]

Service) Alaska OCS leases located greater than 64 mi (103 km) from the 
Chukchi Sea coast during the 2012 open-water season. The leases were 
acquired during the Chukchi Sea Oil and Gas Lease Sale 193 held in 
February 2008. During the 2012 drilling program, Shell plans to drill 
up to three exploration wells at three drill sites and potentially a 
partial well at a fourth drill site at the prospect known as Burger. 
See Figure 1-1 in Shell's application for the lease block and drill 
site locations (see ADDRESSES). All drilling is planned to be vertical.

Exploration Drilling

    All of the possible Chukchi Sea offshore drill sites are located 
between 65 and 78 mi (105 and 125.5 km) from the Chukchi coast in water 
depths between 143 and 150 ft (43.7 and 45.8 m). Table 2-1 in Shell's 
application provides the coordinates for the drill sites (see 
ADDRESSES). All of the proposed wells would be at Shell's Burger 
prospect. Shell has identified a total of six lease blocks on this 
prospect where drilling could occur.
(1) Drilling Vessel
    Shell proposes to use the ice strengthened drillship Discoverer to 
drill the wells. The Discoverer is a true drillship and is a largely 
self-contained drillship that offers full accommodations for a crew of 
up to 140 persons. The Discoverer is 514 ft (156.7 m) long with a 
maximum height (above keel) of 274 ft (83.7 m). It is an anchored 
drillship with an 8-point anchored mooring system and would likely have 
a maximum anchor radius of 2,969-2,986 ft (905-910 m) at either the 
Sivulliq or Torpedo drill sites. While on location at the drill sites, 
the Discoverer will be affixed to the seafloor using eight 7,000 kg 
(7.7 ton) Stevpris anchors arranged in a radial array. The underwater 
fairleads prevent ice fouling of the anchor lines. Turret mooring 
allows orientation of the vessel's bow into the prevailing ice drift 
direction to present minimum hull exposure to drifting ice. The vessel 
is rotated around the turret by hydraulic jacks. Rotation can be 
augmented by the use of the fitted bow and stern thrusters. The hull 
has been reinforced for ice resistance. Ice-strengthened sponsons have 
been retrofitted to the ship's hull. Additional details about the 
drillship can be found in Attachment A of Shell's IHA application (see 
ADDRESSES).
(2) Support Vessels
    During the 2012 drilling season, the Discoverer will be attended by 
eight vessels that will be used for ice management, anchor handling, 
oil spill response (OSR), refueling, resupply, and servicing of the 
exploration drilling operations. The ice-management vessels will 
consist of an icebreaker and an anchor handler. The OSR vessels 
supporting the exploration drilling program include a dedicated OSR 
barge and an OSR vessel, both of which have associated smaller 
workboats, an oil spill tanker, and a containment barge. Tables 1-2a 
and 1-2b in Shell's application provide a list of the support and OSR 
vessels that will be used during the drilling program.
    Shell's base plan is for the ice management vessel and the anchor 
handler, or similar vessels, the oil spill vessels (OSVs), and 
potentially some of the OSR vessels to accompany the Discoverer 
traveling north from Dutch Harbor through the Bering Strait, on or 
about July 1, 2012, then into the Chukchi Sea, before arriving on 
location approximately July 4. Exploration drilling is expected to be 
complete by October 31, 2012. At the completion of the drilling season, 
one or two ice-management vessels, along with various support vessels, 
such as the OSR fleet, will accompany the Discoverer as it travels 
south out of the Chukchi Sea and through the Bering Strait to Dutch 
Harbor. Subject to ice conditions, alternate exit routes may be 
considered.
    The M/V Fennica (Fennica), or a similar vessel, will serve as the 
primary ice management vessel, and the M/V Tor Viking (Tor Viking), or 
a similar vessel, will serve as the primary anchor handling vessel in 
support of the Discoverer. The Fennica and Tor Viking will remain at a 
location approximately 25 mi (40 km) upwind and upcurrent of the 
drillship when not in use. Any ice management would be expected to 
occur within 0.6-6 mi (1-9.6 km) upwind from the Discoverer. When 
managing ice, the vessels will generally be confined to a 40[deg] arc 
up to 3.1 mi (4.9 km) upwind originating at the drilling vessel (see 
Figure 1-3 in Shell's application). It is anticipated that the ice 
management vessels will be managing ice for up to 38% of the time when 
within 25 mi (40 km) of the Discoverer. Active ice management involves 
using the ice management vessel to steer larger floes so that their 
path does not intersect with the drill site. Around-the-clock ice 
forecasting using real-time satellite coverage (available through Shell 
Ice and Weather Advisory Center [SIWAC]) will support the ice 
management duties. The proposed exploration drilling operations will 
require two OSVs to resupply the Discoverer with exploration drilling 
materials and supplies from facilities in Dutch Harbor and fuel.
(3) Aircraft
    Offshore operations will be serviced by helicopters operated out of 
onshore support base locations. A Sikorsky S-92 or Eurocopter EC225 
capable of transporting 10 to 12 persons will be used to transport 
crews between the onshore support base and the drillship. The 
helicopters will also be used to haul small amounts of food, materials, 
equipment, and waste between vessels and the shorebase. The helicopter 
will be housed at facilities at the Barrow airport. Shell will have a 
second helicopter for Search and Rescue (SAR). The SAR helicopter is 
expected to be a Sikorsky S-61, S-92, Eurocopter EC225, or similar 
model. This aircraft will stay grounded at the Barrow shorebase 
location except during training drills, emergencies, and other non-
routine events.
    A fixed wing propeller or turboprop aircraft, such as a Saab 340-B 
30-seat, Beechcraft 1900, or deHavilland Dash8 will be used to 
routinely transport crews, materials, and equipment between the 
shorebase and hub airports such as Barrow or Fairbanks. A fixed wing 
aircraft, deHavilland Twin Otter (DHC-6) will be used for marine mammal 
monitoring flights. Table 1-2c in Shell's application presents the 
aircraft planned to support the exploration drilling program.

Zero-Offset Vertical Seismic Profile

    At the end of each drill hole, Shell may conduct a geophysical 
survey referred to as ZVSP at each drill site where a well is drilled 
in 2012. During ZVSP surveys, an airgun array is deployed at a location 
near or adjacent to the drilling vessel, 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 
in a string, 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 is to gather geophysical information 
at various depths, which can then be used to tie-in or ground-truth 
geophysical information from the previous seismic surveys with 
geological data collected within the wellbore.
    Shell intends to conduct a particular form of vertical seismic 
profile known as a ZVSP, in which the sound source is maintained at a 
constant location near the wellbore (see Figure 1-2 in Shell's

[[Page 69960]]

application). A typical sound source that would be used by Shell in 
2012 is the ITAGA eight-airgun array, which consists of four 150 in\3\ 
airguns and four 40 in\3\ airguns. These airguns can be activated in 
any combination, and Shell intends to utilize the minimum airgun volume 
required to obtain an acceptable signal. Current specifications of the 
array are provided in Table 1-3 of Shell's application. The airgun 
array is depicted within its frame or sled, which is approximately 6 ft 
x 5 ft x 10 ft (1.8 m x 1.5 m x 3 m) (see photograph in Shell's 
application). Typical receivers would consist of a Schlumberger 
wireline four level Vertical Seismic Imager (VSI) tool, which has four 
receivers 50-ft (15-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 plans to deploy the airgun array over the side of the Discoverer 
with a crane (sound source will be 50-200 ft [15-61 m] from the 
wellhead depending on crane location) to a depth of approximately 10-23 
ft (3-7 m) below the water surface. The VSI, with its four receivers, 
will be temporarily anchored in the wellbore at depth. The sound source 
will be pressured up to 2,000 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 reanchored, 
after which the airgun array will again be activated 5-7 times. This 
process will be repeated until the entire well bore is surveyed in this 
manner. The interval between anchor points for the VSI usually is 
between 200 and 300 ft (61 and 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. Therefore, considering a few 
different scenarios, the airgun array could be fired between 117 and 
245 times during the 10-14 hour period. For example, a 7,000-ft 
(2,133.6-m) well with 200-ft (61-m) spacing and seven activations per 
station would result in the airgun array being fired 245 times to 
survey the entire well. That same 7,000-ft (2,133.6-m) well with 300-ft 
(91-m) spacing and five activations would result in the airgun array 
being fired 117 times to survey the entire well. The remainder of the 
time during those 10-14 hours when the airgun is not firing is used to 
move and anchor the geophone array.

Ice Management and Forecasting

    Shell recognizes that the 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 has developed and will implement an Ice Management 
Plan (IMP; see Attachment B in Shell's IHA application) to ensure real-
time ice and weather forecasting is conducted in order to identify 
conditions that might put operations at risk and will modify its 
activities accordingly. The IMP also contains ice threat classification 
levels depending on the time available to suspend drilling operations, 
secure the well, and escape from advancing hazardous ice. Real-time ice 
and weather forecasting will be available to operations personnel for 
planning purposes and to alert the fleet of impending hazardous ice and 
weather conditions. Ice and weather forecasting is provided by SIWAC. 
The center is continuously manned by experienced personnel, who rely on 
a number of data sources for ice forecasting and tracking, including:
     Radarsat and Envisat data--satellites with Synthetic 
Aperture Radar, providing all-weather imagery of ice conditions with 
very high resolution;
     Moderate Resolution Imaging Spectroradiometer--a satellite 
providing lower resolution visual and near infrared imagery;
     Aerial reconnaissance--provided by specially deployed 
fixed wing or rotary wing aircraft for confirmation of ice conditions 
and position;
     Reports from ice specialists on the ice management and 
anchor handling vessels and from the ice observer on the drillship;
     Incidental ice data provided by commercial ships 
transiting the area; and
     Information from NOAA ice centers and the University of 
Colorado.
    Drift ice will be actively managed by ice management vessels, 
consisting of an ice management vessel and an anchor handling vessel. 
Ice management for safe operation of 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 
causing no threat to public safety or services that occur near to 
shore. Shell vessels will also communicate movements and activities 
through the 2012 North Slope Communications Centers. Management of ice 
by ice management vessels will occur during a drilling season 
predominated by open water and thus is not expected to contribute to 
ice hazards, such as ridging, override, or pileup in an offshore or 
nearshore environment.
    The ice-management/anchor handling vessels would manage the ice by 
deflecting any ice floes that could affect the Discoverer when it is 
drilling and would also handle the Discoverer's anchors during 
connection to and separation from the seafloor. When managing ice, the 
ice management and anchor handling vessels will generally be operating 
at a 40[deg] arc up to 3.1 mi (4.9 km) upwind originating at the 
Discoverer (see Figure 1-3 in Shell's application).
    The ice-management/anchor handling vessels would manage any ice 
floes upwind of the Discoverer by deflecting those that could affect 
the Discoverer when it is on location conducting exploration drilling 
operations. The ice-management/anchor handling vessels would also 
manage the Discoverer's anchors during connection to and separation 
from the seafloor. The ice floe frequency and intensity are 
unpredictable and could range from no ice to ice sufficiently dense 
that the fleet has insufficient capacity to continue operating, and the 
Discoverer would need to disconnect from its anchors and move off site. 
If ice is present, ice management activities may be necessary in early 
July and towards the end of operations in late October, but it is not 
expected to be needed throughout the proposed drilling season. Shell 
has indicated that when ice is present at the drill site, ice 
disturbance will be limited to the minimum needed to allow drilling to 
continue. First-year ice (i.e., ice that formed in the most recent 
autumn-winter period) will be the type most likely to be encountered. 
The ice management vessels will be tasked with managing the ice so that 
it will flow easily around and past the Discoverer without building up 
in front of or around it. 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 Discoverer and making turns at both 
ends. During ice management, the vessel's propeller is rotating at 
approximately 15-20 percent 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, thereby 
reducing cavitation effects in the water. Occasionally, there may be 
multi-year ice (i.e., ice that has survived at least one summer melt 
season) ridges that would be managed at a much slower speed than that 
used to manage first-year ice.
    During Chukchi Sea exploration drilling operations, Shell has 
indicated

[[Page 69961]]

that they do not intend to conduct any icebreaking activities; rather, 
Shell would deploy its support vessels to manage ice as described here. 
As detailed in Shell's IMP (see Attachment B of Shell's IHA 
application), actual breaking of ice would occur only in the unlikely 
event that ice conditions in the immediate vicinity of operations 
create a safety hazard for the drilling vessel. In such a circumstance, 
operations personnel will follow the guidelines established in the IMP 
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. Historical data relative to 
ice conditions in the Chukchi Sea in the vicinity of Shell's planned 
operations, and during the timeframe for those operations, establish 
that there is a very low probability (e.g., minimal) for the type of 
hazardous ice conditions that might necessitate icebreaking (e.g., 
records of the National Naval Ice Center archives). This probability 
could be greater at the shoulders of the drilling season (early July or 
late October); therefore, for purposes of evaluating possible impacts 
of the planned activities, Shell has assumed limited icebreaking 
activities for a very limited period of time, and estimated incidental 
takes of marine mammals from such activities.

Timeframe of Activities

    Shell proposes to mobilize the drillship and its fleet of vessels 
from Dutch Harbor and to travel through the Bering Strait on or about 
July 1, 2012. The vessels would then travel into the Chukchi Sea, 
arriving on location at the Burger prospect in the Chukchi Sea on 
approximately July 4, 2012. Shell proposes to conduct the exploration 
drilling program through October 31, 2012. At the end of the 
exploration drilling season, the Discoverer and its support vessels 
would travel south out of the Chukchi Sea through the Bering Strait to 
Dutch Harbor. Subject to ice conditions, alternate exit routes may be 
considered.
    Shell anticipates that the exploration drilling program will 
require approximately 32 days per well, including mudline cellar 
construction. Therefore, if Shell is able to drill three exploration 
wells during the 2012 open-water season, it would require a total of 96 
days. If Shell is able to drill part of a fourth well, it would add an 
additional 1-32 days to the season but would not extend beyond October 
31, 2012. These estimates do not include any downtime for weather or 
other operational delays. Time to conduct the ZVSP surveys for each 
well is included in the 32 drilling days for each well. Shell also 
assumes approximately 10 additional days will be needed for transit, 
drillship mobilization and mooring, drillship moves between locations, 
and drillship demobilization.
    Activities associated with the 2012 Chukchi Sea exploration 
drilling program include operation of the Discoverer, associated 
support vessels, crew change support, and resupply, ZVSP surveys, and 
icebreaking. The Discoverer 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 in accordance with Shell's IMP. The anchor handler and 
OSR vessels will remain in close proximity to the drillship during 
drilling operations.

Exploratory Drilling Program Sound Characteristics

    Potential impacts to marine mammals could occur from the noise 
produced by the drillship and its support vessels (including the 
icebreakers), aircraft, and the airgun array during ZVSP surveys. The 
drillship produces continuous noise into the marine environment. NMFS 
currently uses a threshold of 120 dB re 1 [mu]Pa (rms) for the onset of 
Level B harassment from continuous sound sources. This 120 dB threshold 
is also applicable for the icebreakers when actively managing or 
breaking ice. The drilling vessel to be used will be the Discoverer. 
The airgun array proposed to be used by Shell for the ZVSP surveys 
produces pulsed noise into the marine environment. NMFS currently uses 
a threshold of 160 dB re 1 [mu]Pa (rms) for the onset of Level B 
harassment from pulsed sound sources.
(1) Drilling Sounds
    Exploratory drilling will be conducted from the Discoverer, a 
vessel specifically designed for such operations in the Arctic. 
Underwater sound propagation results from the use of generators, 
drilling machinery, and the rig itself. Received 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 levels 
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 558 ft (170 m) the 20-1000 Hz band level 
was 122-125 dB for the drillship Explorer I. Underwater sound levels 
were slightly higher (134 dB) during drilling activity from the 
Northern Explorer II at a range of 656 ft (200 m), although tones were 
only recorded below 600 Hz. Underwater sound measurements from the 
Kulluk at 0.62 mi (1 km) were higher (143 dB) than from the other two 
vessels.
    Sound measurements from the Discoverer have not previously been 
conducted in the Arctic. However, measurements of sounds produced by 
the Discoverer were made in the South China Sea in 2009 (Austin and 
Warner, 2010). The results of those measurements were used to model the 
sound propagation from the Discoverer (including a nearby support 
vessel) at planned exploration drilling locations in the Chukchi Sea 
(Warner and Hannay, 2011). Broadband source levels of sounds produced 
by the Discoverer varied by activity and direction from the ship but 
were generally between 177 and 185 dB re 1 [micro]Pa at 1 m (rms) 
(Austin and Warner, 2010). Once on location at the drill sites in 
Chukchi Sea, Shell plans to take measurements of the drillship to 
quantify the absolute sound levels produced by drilling and to monitor 
their variations with time, distance, and direction from the drilling 
vessel.
(2) Vessel Sounds
    In addition to the drillship, various types of vessels will be used 
in support of the operations, including ice management vessels, anchor 
handlers, offshore supply vessels, barges and tugs, 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 (e.g., Aerts et al., 2008; Hauser et al., 2008; 
Brueggeman, 2009; Ireland et al., 2009). For example, Garner and Hannay 
(2009) estimated sound pressure levels of 100 dB at distances ranging 
from approximately 1.5 to 2.3 mi (2.4 to 3.7 km) from various types of 
barges. MacDonald et

[[Page 69962]]

al. (2008) estimated higher underwater sound pressure levels (SPLs) 
from the seismic vessel Gilavar of 120 dB at approximately 13 mi (21 
km) from the source, although the sound level was only 150 dB at 85 ft 
(26 m) from the vessel. Like other industry-generated sound, underwater 
sound from vessels is generally at relatively low frequencies.
    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 icebreaking 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.
    Measurements of the icebreaking supply ship Robert Lemeur pushing 
and breaking ice during exploration drilling operations in the Beaufort 
Sea in 1986 resulted in an estimated broadband source level of 193 dB 
re 1 [micro]Pa at 1 m (Greene, 1987a; Richardson et al., 1995a).
    Sound levels during ice management activities would not be as 
intense as during icebreaking, and the resulting effects to marine 
species would be less significant in comparison. During ice management, 
the vessel's propeller is rotating at approximately 15-20 percent of 
the vessel's propeller rotation capacity. Instead of actually breaking 
ice, during ice management, the vessel redirects and repositions the 
ice by pushing it away from the direction of the drillship at slow 
speeds so that the ice floe does not slip past the vessel bow. 
Basically, ice management occurs at slower speed, lower power, and 
slower propeller rotation speed (i.e., lower cavitation), allowing for 
fewer repositions of the vessel, thereby reducing cavitation effects in 
the water than would occur during icebreaking. Once on location at the 
drill sites in the Chukchi Sea, Shell plans to measure the sound levels 
produced by vessels operating in support of drilling operations. These 
vessels will include crew change vessels, tugs, ice management vessels, 
and OSR vessels.
(3) Aircraft Sound
    Helicopters may be used for personnel and equipment transport to 
and from the drillship. 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 
drillship will generally maintain straight-line routes at altitudes of 
at least 1,500 ft (457 m) above sea level, thereby limiting the 
received levels at and below the surface. Aircraft travel would be 
controlled by Federal Aviation Administration approved flight paths.
(4) Vertical Seismic Profile Sound
    A typical eight airgun array (4 x 40 in\3\ airguns and 4 x 150 
in\3\ airguns, for a total discharge volume of 760 in\3\) would be used 
to perform ZVSP surveys, if conducted after the completion of each 
exploratory well. Typically, a single ZVSP survey will be performed 
when the well has reached proposed total depth or final depth; 
although, in some instances, a prior ZVSP will have been performed at a 
shallower depth. A typical survey will last 10-14 hours, depending on 
the depth of the well and the number of anchoring points, and include 
firings of the full array, plus additional firing of a single 40-in\3\ 
airgun to be used as a ``mitigation airgun'' while the geophones are 
relocated within the wellbore. The source level for the airgun array 
proposed for use by Shell will differ based on source depth. At a depth 
of 9.8 ft (3 m), the SPL is 238 dB re 1 [mu]Pa at 1 m, and at a depth 
of 16.4 ft (5 m), the SPL is 241 dB re 1 [mu]Pa at 1 m, with most 
energy between 20 and 140 Hz.
    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. Typical high-energy airgun 
arrays emit most energy at 10-120 Hz. However, the pulses contain 
significant energy up to 500-1,000 Hz and some energy at higher 
frequencies (Goold and Fish, 1998; Potter et al., 2007).
    Although there will be several support vessels in the drilling 
operations area, NMFS considers the possibility of collisions with 
marine mammals highly unlikely. Once on location, the majority of the 
support vessels will remain in the area of the drillship throughout the 
2012 drilling season and will not be making trips between the shorebase 
and the offshore vessels. When not needed for ice management/
icebreaking operations, the icebreaker and anchor handler will remain 
approximately 25 mi (40 km) upwind and upcurrent of the drillship. Any 
ice management/icebreaking activity would be expected to occur at a 
distance of 0.6-12 mi (1-19 km) upwind and upcurrent of the drillship. 
As the crew change/resupply activities are considered part of normal 
vessel traffic and are not anticipated to impact marine mammals in a 
manner that would rise to the level of taking, those activities are not 
considered further in this document.

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. 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. On December 10, 2010, NMFS published a notice of

[[Page 69963]]

proposed threatened status for subspecies of the ringed seal (75 FR 
77476) and a notice of proposed threatened and not warranted status for 
subspecies and distinct population segments of the bearded seal (75 FR 
77496) in the Federal Register. Neither of these two ice seal species 
is considered depleted under the MMPA. Additionally, the ribbon seal is 
considered a ``species of concern'' under the ESA. 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 include: 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 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 2010 SAR is available at: http://www.nmfs.noaa.gov/pr/pdfs/sars/ak2010.pdf.

Brief Background on Marine Mammal Hearing

    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):
     Low frequency cetaceans (13 species of mysticetes): 
functional hearing is estimated to occur between approximately 7 Hz and 
22 kHz (however, a study by Au et al. (2006) of humpback whale songs 
indicate that the range may extend to at least 24 kHz);
     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;
     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; and
     Pinnipeds in Water: functional hearing is estimated to 
occur between approximately 75 Hz and 75 kHz, with the greatest 
sensitivity between approximately 700 Hz and 20 kHz.
    As mentioned previously in this document, 12 marine mammal species 
(four pinniped and eight cetacean species) are likely to occur in the 
proposed drilling area. Of the eight cetacean species likely to occur 
in Shell's project area, five are classified as low frequency cetaceans 
(i.e., bowhead, gray, humpback, minke, and fin whales), two are 
classified as mid-frequency cetaceans (i.e., beluga and killer whales), 
and one is classified as a high-frequency cetacean (i.e., harbor 
porpoise) (Southall et al., 2007).
    Underwater audiograms have been obtained using behavioral methods 
for four species of phocinid seals: the ringed, harbor, harp, and 
northern elephant seals (reviewed in Richardson et al., 1995a; Kastak 
and Schusterman, 1998). Below 30-50 kHz, the hearing threshold of 
phocinids is essentially flat down to at least 1 kHz and ranges between 
60 and 85 dB re 1 [mu]Pa. There are few published data on in-water 
hearing sensitivity of phocid seals below 1 kHz. However, measurements 
for one harbor seal indicated that, below 1 kHz, its thresholds 
deteriorated gradually to 96 dB re 1 [mu]Pa at 100 Hz from 80 dB re 1 
[mu]Pa at 800 Hz and from 67 dB re 1 [mu]Pa at 1,600 Hz (Kastak and 
Schusterman, 1998). More recent data suggest that harbor seal hearing 
at low frequencies may be more sensitive than that and that earlier 
data were confounded by excessive background noise (Kastelein et al., 
2009a,b). If so, harbor seals have considerably better underwater 
hearing sensitivity at low frequencies than do small odontocetes like 
belugas (for which the threshold at 100 Hz is about 125 dB).
    Pinniped call characteristics are relevant when assessing potential 
masking effects of man-made sounds. In addition, for those species 
whose hearing has not been tested, call characteristics are useful in 
assessing the frequency range within which hearing is likely to be most 
sensitive. The four species of seals present in the study area, all of 
which are in the phocid seal group, are all most vocal during the 
spring mating season and much less so during late summer. In each 
species, the calls are at frequencies from several hundred to several 
thousand hertz--above the frequency range of the dominant noise 
components from most of the proposed oil exploration activities.
    Cetacean hearing has been studied in relatively few species and 
individuals. The auditory sensitivity of bowhead, gray, and other 
baleen whales has not been measured, but relevant anatomical

[[Page 69964]]

and behavioral evidence is available. These whales appear to be 
specialized for low frequency hearing, with some directional hearing 
ability (reviewed in Richardson et al., 1995a; Ketten, 2000). Their 
optimum hearing overlaps broadly with the low frequency range where 
exploration drilling activities, airguns, and associated vessel traffic 
emit most of their energy.
    The beluga whale is one of the better-studied species in terms of 
its hearing ability. As mentioned earlier, the auditory bandwidth in 
mid-frequency odontocetes is believed to range from 150 Hz to 160 kHz 
(Southall et al., 2007); however, belugas are most sensitive above 10 
kHz. They have relatively poor sensitivity at the low frequencies 
(reviewed in Richardson et al., 1995a) that dominate the sound from 
industrial activities and associated vessels. Nonetheless, the noise 
from strong low frequency sources is detectable by belugas many 
kilometers away (Richardson and Wursig, 1997). Also, beluga hearing at 
low frequencies in open-water conditions is apparently somewhat better 
than in the captive situations where most hearing studies were 
conducted (Ridgway and Carder, 1995; Au, 1997). If so, low frequency 
sounds emanating from drilling activities may be detectable somewhat 
farther away than previously estimated.
    Call characteristics of cetaceans provide some limited information 
on their hearing abilities, although the auditory range often extends 
beyond the range of frequencies contained in the calls. Also, 
understanding the frequencies at which different marine mammal species 
communicate is relevant for the assessment of potential impacts from 
manmade sounds. A summary of the call characteristics for bowhead, 
gray, and beluga whales is provided next.
    Most bowhead calls are tonal, frequency-modulated sounds at 
frequencies of 50-400 Hz. These calls overlap broadly in frequency with 
the underwater sounds emitted by many of the activities to be performed 
during Shell's proposed exploration drilling program (Richardson et 
al., 1995a). Source levels are quite variable, with the stronger calls 
having source levels up to about 180 dB re 1 [mu]Pa at 1 m. Gray whales 
make a wide variety of calls at frequencies from < 100-2,000 Hz (Moore 
and Ljungblad, 1984; Dalheim, 1987).
    Beluga calls include trills, whistles, clicks, bangs, chirps and 
other sounds (Schevill and Lawrence, 1949; Ouellet, 1979; Sjare and 
Smith, 1986a). Beluga whistles have dominant frequencies in the 2-6 kHz 
range (Sjare and Smith, 1986a). This is above the frequency range of 
most of the sound energy produced by the proposed exploratory drilling 
activities and associated vessels. Other beluga call types reported by 
Sjare and Smith (1986a,b) included sounds at mean frequencies ranging 
upward from 1 kHz.
    The beluga also has a very well developed high frequency 
echolocation system, as reviewed by Au (1993). Echolocation signals 
have peak frequencies from 40-120 kHz and broadband source levels of up 
to 219 dB re 1 [mu]Pa-m (zero-peak). Echolocation calls are far above 
the frequency range of the sounds produced by the devices proposed for 
use during Shell's Chukchi Sea exploratory drilling program. Therefore, 
those industrial sounds are not expected to interfere with 
echolocation.

Potential Effects of the Specified Activity on Marine Mammals

    The likely or possible impacts of the proposed exploratory drilling 
program in the Chukchi Sea on marine mammals could involve both non-
acoustic and acoustic effects. Potential non-acoustic effects could 
result from the physical presence of the equipment and personnel. 
Petroleum development and associated activities introduce sound into 
the marine environment. Impacts to marine mammals are expected to 
primarily be acoustic in nature. Potential acoustic effects on marine 
mammals relate to sound produced by drilling activity, vessels, and 
aircraft, as well as the ZVSP airgun array. The potential effects of 
sound from the proposed exploratory drilling program 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). However, for reasons discussed later in this document, it is 
unlikely that there would be any cases of temporary, or especially 
permanent, hearing impairment resulting from these activities. As 
outlined in previous NMFS documents, the effects of noise on marine 
mammals are highly variable, and can be categorized as follows (based 
on Richardson et al., 1995a):
    (1) The noise may be too weak to be heard at the location of the 
animal (i.e., lower than the prevailing ambient noise level, the 
hearing threshold of the animal at relevant frequencies, or both);
    (2) The noise may be audible but not strong enough to elicit any 
overt behavioral response;
    (3) The noise may elicit reactions of variable conspicuousness and 
variable relevance to the well being of the marine mammal; these can 
range from temporary alert responses to active avoidance reactions such 
as vacating an area at least until the noise event ceases but 
potentially for longer periods of time;
    (4) Upon repeated exposure, a marine mammal may exhibit diminishing 
responsiveness (habituation), or disturbance effects may persist; the 
latter is most likely with sounds that are highly variable in 
characteristics, infrequent, and unpredictable in occurrence, and 
associated with situations that a marine mammal perceives as a threat;
    (5) Any anthropogenic noise that is strong enough to be heard has 
the potential to reduce (mask) the ability of a marine mammal to hear 
natural sounds at similar frequencies, including calls from 
conspecifics, and underwater environmental sounds such as surf noise;
    (6) If mammals remain in an area because it is important for 
feeding, breeding, or some other biologically important purpose even 
though there is chronic exposure to noise, it is possible that there 
could be noise-induced physiological stress; this might in turn have 
negative effects on the well-being or reproduction of the animals 
involved; and
    (7) Very strong sounds have the potential to cause a temporary or 
permanent reduction in hearing sensitivity. In terrestrial mammals, and 
presumably marine mammals, received sound levels must far exceed the 
animal's hearing threshold for there to be any temporary threshold 
shift (TTS) in its hearing ability. For transient sounds, the sound 
level necessary to cause TTS is inversely related to the duration of 
the sound. Received sound levels must be even higher for there to be 
risk of permanent hearing impairment. In addition, intense acoustic or 
explosive events may cause trauma to tissues associated with organs 
vital for hearing, sound production, respiration and other functions. 
This trauma may include minor to severe hemorrhage.

Potential Acoustic Effects From Exploratory Drilling Activities

(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

[[Page 69965]]

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 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

[[Page 69966]]

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 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 
provide an idea of 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

[[Page 69967]]

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 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

[[Page 69968]]

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 
(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 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. 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.

[[Page 69969]]

    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 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

[[Page 69970]]

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 [ 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 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 ZVSP Activities'').

Potential Effects from ZVSP 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

[[Page 69971]]

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 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 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

[[Page 69972]]

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 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,

[[Page 69973]]

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 drillship 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 re 1 [mu]Pa (rms) criteria are the received 
levels above which, in the view of a panel of bioacoustics specialists 
convened by NMFS before additional TTS measurements for marine mammals 
became available, one could not be certain that 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 shutdown criteria 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 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 drillship 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 drillship, the levels 
immediately adjacent to the drillship 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 drillship 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. Table 1 in this document summarizes the SPL and 
SEL levels thought to cause auditory injury to cetaceans and pinnipeds 
in-water. For more information, please refer to Southall et al. (2007).

[[Page 69974]]



   Table 1--Proposed Injury Criteria for Cetaceans and Pinnipeds Exposed to ``Discrete'' Noise Events (Either
           Single Pulses, Multiple Pulses, or Non-Pulses Within a 24-Hr Period; Southall et al., 2007)
----------------------------------------------------------------------------------------------------------------
                                            Single pulses           Multiple pulses             Non pulses
----------------------------------------------------------------------------------------------------------------
                                             Low-frequency cetaceans
----------------------------------------------------------------------------------------------------------------
Sound pressure level.................  230 dB re 1 [mu]Pa       230 dB re 1 [mu]Pa       230 dB re 1 [mu]Pa
                                        (peak) (flat).           (peak) (flat).           (peak) (flat).
Sound exposure level.................  198 dB re 1 [mu]Pa\2\-s  198 dB re 1 [mu]Pa\2\-s  215 dB re 1 [mu]Pa\2\-s
                                        (Mlf).                   (Mlf).                   (Mlf).
----------------------------------------------------------------------------------------------------------------
                                             Mid-frequency cetaceans
----------------------------------------------------------------------------------------------------------------
Sound pressure level.................  230 dB re 1 [mu]Pa       230 dB re 1 [mu]Pa       230 dB re 1 [mu]Pa
                                        (peak) (flat).           (peak) (flat).           (peak) (flat).
Sound exposure level.................  198 dB re 1 [mu]Pa\2\-s  198 dB re 1 [mu]Pa\2\-s  215 dB re 1 [mu]Pa\2\-s
                                        (Mlf).                   (Mlf).                   (Mlf).
----------------------------------------------------------------------------------------------------------------
                                            High-frequency cetaceans
----------------------------------------------------------------------------------------------------------------
Sound pressure level.................  230 dB re 1 [mu]Pa       230 dB re 1 [mu]Pa       230 dB re 1 [mu]Pa
                                        (peak) (flat).           (peak) (flat).           (peak) (flat).
Sound exposure level.................  198 dB re 1 [mu]Pa\2\-s  198 dB re 1 [mu]Pa\2\-s  215 dB re 1 [mu]Pa\2\-s
                                        (Mlf).                   (Mlf).                   (Mlf).
----------------------------------------------------------------------------------------------------------------
                                              Pinnipeds (in water)
----------------------------------------------------------------------------------------------------------------
Sound pressure level.................  218 dB re 1 [mu]Pa       218 dB re 1 [mu]Pa       218 dB re 1 [mu]Pa
                                        (peak) (flat).           (peak) (flat).           (peak) (flat).
Sound exposure level.................  186 dB re 1 [mu]Pa\2\-s  186 dB re 1 [mu]Pa\2\-s  203 dB re 1 [mu]Pa\2\-s
                                        (Mpw).                   (Mpw).                   (Mpw).
----------------------------------------------------------------------------------------------------------------

    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 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.,

[[Page 69975]]

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 drillships 
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 drillship 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.

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, 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 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 drillship 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

[[Page 69976]]

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.

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 2012 open-water season. The impacts to marine mammals that are 
reasonably expected to occur will be acoustic in nature. In response to 
previous IHA applications submitted by Shell, various entities have 
asserted that NMFS cannot authorize the take of marine mammals 
incidental to exploratory drilling under an IHA. Instead, they contend 
that incidental take can be allowed only with a letter of authorization 
(LOA) issued under five-year regulations because of the potential that 
an oil spill will cause serious injury or mortality.
    There are two avenues for authorizing incidental take of marine 
mammals under the MMPA. NMFS may, depending on the nature of the 
anticipated take, authorize the take of marine mammals incidental to a 
specified activity through regulations and LOAs or annual IHAs. See 16 
U.S.C. 1371(a)(5)(A) and (D). In general, regulations (accompanied by 
LOAs) may be issued for any type of take (e.g., Level B harassment 
(behavioral disturbance), Level A harassment (injury), serious injury, 
or mortality), whereas IHAs are limited to activities that result only 
in harassment (e.g., behavioral disturbance or injury). Following the 
1994 MMPA Amendments, NMFS promulgated implementing regulations 
governing the issuance of IHAs in Arctic waters. See 60 FR 28379 (May 
31, 1995) and 61 FR 15884 (April 10, 1996). NMFS stated in the preamble 
of the proposed rulemaking that the scope of IHAs would be limited to 
``* * * those authorizations for harassment involving incidental 
harassment that may involve non-serious injury.'' See 60 FR 28380 (May 
31, 1995; emphasis added); 50 CFR 216.107(a). (``[e]xcept for 
activities that have the potential to result in serious injury or 
mortality, which must be authorized under 216.105, incidental 
harassment authorizations may be issued, * * * to allowed activities 
that may result in only the incidental harassment of a small number of 
marine mammals.'') NMFS explained further that applications would be 
reviewed to determine whether the activity would result in more than 
harassment, and, if so, the agency would either (1) attempt to negate 
the potential for serious injury through mitigation requirements, or 
(2) deny the incidental harassment authorization and require the 
applicant to apply for incidental take regulations. See id. at 28380-
81.
    NMFS' determination of whether the type of incidental take 
authorization requested is appropriate occurs shortly after the 
applicant submits an application for an incidental take authorization. 
The agency evaluates the proposed action and all information contained 
in the application to determine whether it is adequate and complete and 
whether the type of taking requested is appropriate. See 50 CFR 
216.104; see also 60 FR 28380 (May 31, 1995). Among other things, NMFS 
considers the specific activity or class of activities that can 
reasonably be expected to result in incidental take; the type of 
incidental take authorization that is being requested; and the 
anticipated impact of the activity upon the species or stock and its 
habitat. See id. at 216.104(a) (emphasis added). Any application that 
is determined to be incomplete or inappropriate for the type of taking 
requested will be returned to the applicant with an explanation of why 
the application is being returned. See id. Finally, NMFS evaluates the 
best available science to determine whether a proposed activity is 
reasonably expected or likely to result in serious injury or mortality.
    NMFS evaluated Shell's incidental take application for its proposed 
2012 drilling activities in light of the foregoing criteria and has 
concluded that Shell's request for an IHA is warranted. Shell submitted 
information with its IHA Application indicating that an oil spill is a 
highly unlikely event that is not reasonably expected to occur during 
the course of exploration drilling or ZVSP surveys. See Chukchi Sea IHA 
Application, p. 3 and Attachment E--Analysis of the Probability of an 
``Unspecified Activity'' and Its Impacts: Oil Spill. In addition, 
Shell's 2012 Exploration Plan indicates there is a ``very low 
likelihood of a large oil spill event.'' See Shell Offshore, Inc.'s 
Revised Outer Continental Shelf Lease Exploration Plan, Chukchi Sea, 
Alaska (May 2011), at p. 8-1; see also, Appendix F to Shell's Revised 
Outer Continental Shelf Lease Exploration Plan, at p. 4-174.
    The likelihood of a large or very large (i.e., >=1,000 barrels or 
>=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). 
Attachment E in Shell's IHA Application contains information regarding 
the probability of an oil spill occurring during the proposed program 
and the potential impacts should one occur. 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. Please refer to Shell's application for additional information on 
the model and predicted frequencies (see ADDRESSES).

[[Page 69977]]

    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; IMP; 
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:
     Shell's Blow Out Preventer (BOP) was inspected and tested 
by an independent third party specialist;
     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;
     Subsea BOP hydrostatic tests will be increased from once 
every 14 days to once every 7 days;
     A second set of blind/shear rams will be installed in the 
BOP stack;
     Full string casings will typically not be installed 
through high pressure zones;
     Liners will be installed and cemented, which allows for 
installation of a liner top packer;
     Testing of liners prior to installing a tieback string of 
casing back to the wellhead;
     Utilizing a two-barrier policy; and
     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 from 
the 2012 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, 2009).
    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 further 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. In fact, 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 (EVOS). 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 EVOS (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 
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).

[[Page 69978]]

(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). 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 EVOS, 
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

[[Page 69979]]

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 EVOS (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 EVOS, 
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 EVOS 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 EVOS (Frost et al., 1994a). However, in a reanalysis of those 
data and additional years of surveys, along with an examination of 
assumptions and biases associated with the original data, Hoover-Miller 
et al. (2001) concluded that the EVOS effect had been overestimated. 
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 EVOS. The results from Hoover-Miller et al. (2001) indicate 
that the effects of EVOS 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 EVOS (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.

[[Page 69980]]

    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 drillship 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.

Common Marine Mammal Prey in the Area

    All of the marine mammal species that may occur in the proposed 
project area prey on either marine fish or invertebrates. The ringed 
seal feeds on fish and a variety of benthic species, including crabs 
and shrimp. Bearded seals feed mainly on benthic organisms, primarily 
crabs, shrimp, and clams. Spotted seals feed on pelagic and demersal 
fish, as well as shrimp and cephalopods. They are known to feed on a 
variety of fish including herring, capelin, sand lance, Arctic cod, 
saffron cod, and sculpins. Ribbon seals feed primarily on pelagic fish 
and invertebrates, such as shrimp, crabs, squid, octopus, cod, sculpin, 
pollack, and capelin. Juveniles feed mostly on krill and shrimp.
    Bowhead whales feed in the eastern Beaufort Sea during summer and 
early autumn but continue feeding to varying degrees while on their 
migration through the central and western Beaufort Sea in the late 
summer and fall (Richardson and Thomson [eds.], 2002). Aerial surveys 
in recent years have sighted bowhead whales feeding in Camden Bay on 
their westward migration through the Beaufort Sea. When feeding in 
relatively shallow areas, bowheads feed throughout the water column. 
However, feeding is concentrated at depths where zooplankton is 
concentrated (Wursig et al., 1984, 1989; Richardson [ed.], 1987; 
Griffiths et al., 2002). Lowry and Sheffield (2002) found that copepods 
and euphausiids were the most common prey found in stomach samples from 
bowhead whales harvested in the Kaktovik area from 1979 to 2000. Areas 
to the east of Barter Island in the Beaufort Sea appear to be used 
regularly for feeding as bowhead whales migrate slowly westward across 
the Beaufort Sea (Thomson and Richardson, 1987; Richardson and Thomson 
[eds.], 2002). However, in some years, sizable groups of bowhead whales 
have been seen feeding as far west as the waters just east of Point 
Barrow (which is more than 150 mi [241 km] east of Shell's proposed 
drill sites in the Chukchi Sea) near the Plover Islands (Braham et al., 
1984; Ljungblad et al., 1985; Landino et al., 1994). The situation in 
September-October 1997 was unusual in that bowheads fed widely across 
the Alaskan Beaufort Sea, including higher numbers in the area east of 
Barrow than reported in any previous year (S. Treacy and D. Hansen, 
MMS, pers. comm.). However, by the time most bowhead whales reach the 
Chukchi Sea (October), they will likely no longer be feeding, or if it 
occurs it will be very limited. The location near Point Barrow is 
currently under intensive study as part of the BOWFEST program 
(BOWFEST, 2011).
    Beluga whales feed on a variety of fish, shrimp, squid, and octopus 
(Burns and Seaman, 1985). Like several of the other species in the 
area, harbor porpoise feed on demersal and benthic species, mainly 
schooling fish and cephalopods. Killer whales from resident stocks 
primarily feed on salmon while killer whales from transient stocks feed 
on other marine mammals, such as harbor seals, harbor porpoises, gray 
whale calves and other pinniped and cetacean species.
    Gray whales are primarily bottom feeders, and benthic amphipods and 
isopods form the majority of their summer diet, at least in the main 
summering areas west of Alaska (Oliver et al., 1983; Oliver and 
Slattery, 1985). Farther south, gray whales have also been observed 
feeding around kelp beds, presumably on mysid crustaceans, and on 
pelagic prey such as small schooling fish and crab larvae (Hatler and 
Darling, 1974). The northeastern-most of the recurring feeding areas 
for gray whales is in the northeastern Chukchi Sea southwest of Barrow 
(Clarke et al., 1989).
    Three other baleen whale species may occur in the proposed project 
area, although likely in very small numbers: Minke, humpback, and fin 
whales. Minke whales opportunistically feed on crustaceans (e.g., 
krill), plankton (e.g., copepods), and small schooling fish (e.g., 
anchovies, dogfish, capelin, coal fish, cod, eels, herring, mackerel, 
salmon, sand lance, saury, and wolfish) (Reeves et al., 2002). Fin 
whales tend to feed in northern latitudes in the summer months on 
plankton and shoaling pelagic fish (Jonsgard, 1966a,b). Like many of 
the other species in the area, humpback whales primarily feed on 
euphausiids, copepods, and small schooling fish (e.g., herring, 
capelin, and sand lance) (Reeves et al., 2002). However, the primary 
feeding grounds for these species do not occur in the northern Chukchi 
Sea.
    Two kinds of fish inhabit marine waters in the study area: (1) True 
marine fish that spend all of their lives in salt water, and (2) 
anadromous species that reproduce in fresh water and spend parts of 
their life cycles in salt water.
    Most arctic marine fish species are small, benthic forms that do 
not feed high in the water column. The majority of these species are 
circumpolar and are found in habitats ranging from deep offshore water 
to water as shallow as 16.4-33 ft (5-10 m; Fechhelm et al., 1995). The 
most important pelagic species, and the only abundant pelagic species, 
is the Arctic cod. The Arctic cod is a major vector for the transfer of 
energy from lower to higher trophic levels (Bradstreet et al., 1986). 
In summer, Arctic cod can form very large schools in both nearshore and 
offshore waters (Craig et al., 1982; Bradstreet et al., 1986). 
Locations and areas frequented by large schools of Arctic cod cannot be 
predicted but can be almost anywhere. The Arctic cod is a major food 
source for beluga whales, ringed seals, and numerous species of 
seabirds (Frost and Lowry, 1984; Bradstreet et al., 1986).
    Anadromous Dolly Varden char and some species of whitefish winter 
in rivers and lakes, migrate to the sea in spring and summer, and 
return to fresh water in autumn. Anadromous fish form the basis of 
subsistence, commercial, and small regional sport fisheries. Dolly 
Varden char migrate to the sea from May through mid-June (Johnson, 
1980) and spend about 1.5-2.5 months there (Craig, 1989). They return 
to rivers beginning in late July or early August with the peak return 
migration occurring between mid-August and early September (Johnson, 
1980). At sea, most anadromous corregonids (whitefish) remain in 
nearshore waters within several kilometers of shore (Craig, 1984, 
1989). They are often termed ``amphidromous'' fish in that they make 
repeated annual migrations into marine waters to feed, returning each 
fall to overwinter in fresh water.
    Benthic organisms are defined as bottom dwelling creatures. 
Infaunal

[[Page 69981]]

organisms are benthic organisms that live within the substrate and are 
often sedentary or sessile (bivalves, polychaetes). Epibenthic 
organisms live on or near the bottom surface sediments and are mobile 
(amphipods, isopods, mysids, and some polychaetes). The northeastern 
Chukchi Sea supports a higher biomass of benthic organisms than do 
surrounding areas (Grebmeier and Dunton, 2000). Some benthic-feeding 
marine mammals, such as walruses and gray whales, take advantage of the 
abundant food resources and congregate in these highly productive 
areas. Harold and Hanna Shoals are two known highly productive areas in 
the Chukchi Sea rich with benthic animals.
    Many of the nearshore benthic marine invertebrates of the Arctic 
are circumpolar and are found over a wide range of water depths (Carey 
et al., 1975). Species identified include polychaetes (Spio filicornis, 
Chaetozone setosa, Eteone longa), bivalves (Cryrtodaria kurriana, 
Nucula tenuis, Liocyma fluctuosa), an isopod (Saduria entomon), and 
amphipods (Pontoporeia femorata, P. affinis). Additionally, kelp beds 
occur in at least two areas in the nearshore areas of the Chukchi Sea 
(Mohr et al., 1957; Phillips et al., 1982; Phillips and Reiss, 1985), 
but they are located within about 15.5 mi (25 km) of the coast, which 
is much closer nearshore than Shell's proposed activities.

Potential Impacts From Seafloor Disturbance on Marine Mammal Habitat

    There is a possibility of some seafloor disturbance or temporary 
increased turbidity in the seabed sediments during anchoring and 
excavation of the mudline cellars (MLCs). The amount and duration of 
disturbed or turbid conditions will depend on sediment material and 
consolidation of specific activity.
    The Discoverer would be stabilized and held in place with a system 
of eight 15,400 lb (7,000 kg) Stevpris anchors during operations. The 
anchors from the Discoverer are designed to embed into the seafloor. 
Prior to setting, the anchors will penetrate the seafloor and drag two 
or three times their length. Both the anchor and anchor chain will 
disturb sediments and create an ``anchor scar,'' which is a depression 
in the seafloor caused by the anchor embedding. The anchor scar is a 
depression with ridges of displaced sediment, and the area of 
disturbance will often be greater than the size of the anchor itself 
because the anchor is dragged along the seafloor until it takes hold 
and sets.
    Each Stevpris anchor may impact an area of 2,027 ft\2\ (188 m\2\) 
of the seafloor, including the scar made when the anchor chain is 
dragged across the seafloor. Minimum impact estimates from each well or 
mooring the Discoverer by its eight anchors is 16,216 ft\2\ (1,507 
m\2\) of seafloor. This estimate assumes that the anchors are set only 
once. Shell plans to pre-set anchors at each drill site. Unless moved 
by an outside force such as sea current, anchors should only need to be 
set once per drill site. (Shell proposes to drill at three sites and 
potentially a fourth site in the Chukchi Sea during the 2012 open-water 
season.) Additionally, based on the vast size of the Chukchi Sea, the 
area of disturbance is not anticipated to adversely affect marine 
mammal use of the area.
    Once the drillship ends operation, the anchors will be retrieved. 
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 5-10 years 
after retrieval. Centaur Associates, Inc. (1984) reported that 
anchoring in sand or muddy sand sediments may not result in anchor 
scars or may result in scars that do not persist. 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 Discoverer will displace about 17,128 
ft\3\ (485 m\3\) of seafloor sediments and directly disturb 
approximately 314 ft\2\ (29 m\2\) of seafloor. Material will be 
excavated from the MLCs using a large diameter drillbit. 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 removed via the air lift system and 
discharged on the seafloor away from the MLC. These excavated materials 
will also have some indirect effects as they are deposited on the 
seafloor in the vicinity of the MLCs. Direct and indirect effects would 
include slight changes in seafloor relief and sediment consistency.
    Vessel mooring and MLC construction would result in increased 
suspended sediment in the water column that could result in lethal 
effects on some zooplankton (food source for baleen whales). However, 
compared to the overall population of zooplankton and the localized 
nature of effects, any mortality that may occur would not be considered 
significant. Due to fast regeneration periods of zooplankton, 
populations are expected to recover quickly.
    Impacts on fish resulting from suspended sediments would be 
dependent upon the life stage of the fish (e.g., eggs, larvae, 
juveniles, or adults), the concentration of the suspended sediments, 
the type of sediment, and the duration of exposure (IMG Golder, 2004). 
Eggs and larvae have been found to exhibit greater sensitivity to 
suspended sediments (Wilber and Clarke, 2001) and other stresses, which 
is thought to be related to their relative lack of motility (Auld and 
Schubel, 1978). Sedimentation could affect fish by causing egg 
morbidity of demersal fish feeding near or on the ocean floor (Wilber 
and Clarke, 2001). Surficial membranes are especially susceptible to 
abrasion (Cairns and Scheier, 1968). Adhesive demersal eggs could be 
exposed to the sediments as long as the excavation activity continues, 
while exposure of pelagic eggs would be much shorter as they move with 
ocean currents (Wilber and Clarke, 2001). Most of the offshore demersal 
marine fish species in the northeastern Chukchi Sea (Shell's proposed 
project area) spawn under the ice during the winter and therefore would 
not be affected by redeposition of sediments on the seafloor due to MLC 
construction since Shell has not scheduled any exploration drilling 
activities during the winter months.
    Most diadromous fish species expected to be present in the area of 
Shell's drilling operations lay their eggs in freshwater or coastal 
estuaries. Therefore, only those eggs carried into the marine 
environment by winds and current would be affected by these operations. 
Because Shell's proposed drill sites occur 65 and 78 mi (105 and 125.5 
km) from the Chukchi coast, the statistical probability of diadromous 
fish eggs being present in the vicinity of Shell's proposed operations 
is infinitesimally small. Thus, impacts on diadromous fish eggs due to 
abrasion, puncture, burial, or other effects associated with anchoring 
or MLC construction would be slight. Further, since most diadromous 
fish species produce eggs prolifically, even if a small number of eggs 
were impacted by these activities, the total species population would 
not be expected to be impacted.
    Suspended sediments, resulting from vessel mooring and MLC 
excavation, are

[[Page 69982]]

not expected to result in permanent damage to habitats used by the 
marine mammal species in the proposed project area or on the food 
sources that they utilize. Rather, NMFS considers that such impacts 
will be temporary in nature and concentrated in the areas directly 
surrounding vessel mooring and MLC excavation activities--areas which 
are very small relative to the overall Chukchi Sea region. Less than 
0.0000001 percent of the fish habitat in the LS 193 area would be 
directly affected by the mooring and excavation activity.

Potential Impacts From Sound Generation

    With regard to fish as a prey source for odontocetes and seals, 
fish are known to hear and react to sounds and to use sound to 
communicate (Tavolga et al., 1981) and possibly avoid predators (Wilson 
and Dill, 2002). Experiments have shown that fish can sense both the 
strength and direction of sound (Hawkins, 1981). Primary factors 
determining whether a fish can sense a sound signal, and potentially 
react to it, are the frequency of the signal and the strength of the 
signal in relation to the natural background noise level.
    Fishes produce sounds that are associated with behaviors that 
include territoriality, mate search, courtship, and aggression. It has 
also been speculated that sound production may provide the means for 
long distance communication and communication under poor underwater 
visibility conditions (Zelick et al., 1999), although the fact that 
fish communicate at low-frequency sound levels where the masking 
effects of ambient noise are naturally highest suggests that very long 
distance communication would rarely be possible. Fishes have evolved a 
diversity of sound generating organs and acoustic signals of various 
temporal and spectral contents. Fish sounds vary in structure, 
depending on the mechanism used to produce them (Hawkins, 1993). 
Generally, fish sounds are predominantly composed of low frequencies 
(less than 3 kHz).
    Since objects in the water scatter sound, fish are able to detect 
these objects through monitoring the ambient noise. Therefore, fish are 
probably able to detect prey, predators, conspecifics, and physical 
features by listening to environmental sounds (Hawkins, 1981). There 
are two sensory systems that enable fish to monitor the vibration-based 
information of their surroundings. The two sensory systems, the inner 
ear and the lateral line, constitute the acoustico-lateralis system.
    Although the hearing sensitivities of very few fish species have 
been studied to date, it is becoming obvious that the intra- and inter-
specific variability is considerable (Coombs, 1981). Nedwell et al. 
(2004) compiled and published available fish audiogram information. A 
noninvasive electrophysiological recording method known as auditory 
brainstem response is now commonly used in the production of fish 
audiograms (Yan, 2004). Generally, most fish have their best hearing in 
the low-frequency range (i.e., less than 1 kHz). Even though some fish 
are able to detect sounds in the ultrasonic frequency range, the 
thresholds at these higher frequencies tend to be considerably higher 
than those at the lower end of the auditory frequency range.
    Literature relating to the impacts of sound on marine fish species 
can be divided into the following categories: (1) Pathological effects; 
(2) physiological effects; and (3) behavioral effects. Pathological 
effects include lethal and sub-lethal physical damage to fish; 
physiological effects include primary and secondary stress responses; 
and behavioral effects include changes in exhibited behaviors of fish. 
Behavioral changes might be a direct reaction to a detected sound or a 
result of the anthropogenic sound masking natural sounds that the fish 
normally detect and to which they respond. The three types of effects 
are often interrelated in complex ways. For example, some physiological 
and behavioral effects could potentially lead to the ultimate 
pathological effect of mortality. Hastings and Popper (2005) reviewed 
what is known about the effects of sound on fishes and identified 
studies needed to address areas of uncertainty relative to measurement 
of sound and the responses of fishes. Popper et al. (2003/2004) also 
published a paper that reviews the effects of anthropogenic sound on 
the behavior and physiology of fishes.
    Potential effects of exposure to continuous sound on marine fish 
include TTS, physical damage to the ear region, physiological stress 
responses, and behavioral responses such as startle response, alarm 
response, avoidance, and perhaps lack of response due to masking of 
acoustic cues. Most of these effects appear to be either temporary or 
intermittent and therefore probably do not significantly impact the 
fish at a population level. The studies that resulted in physical 
damage to the fish ears used noise exposure levels and durations that 
were far more extreme than would be encountered under conditions 
similar to those expected during Shell's proposed exploratory drilling 
activities.
    The level of sound at which a fish will react or alter its behavior 
is usually well above the detection level. Fish have been found to 
react to sounds when the sound level increased to about 20 dB above the 
detection level of 120 dB (Ona, 1988); however, the response threshold 
can depend on the time of year and the fish's physiological condition 
(Engas et al., 1993). In general, fish react more strongly to pulses of 
sound rather than a continuous signal (Blaxter et al., 1981), such as 
the type of sound that will be produced by the drillship, and a quicker 
alarm response is elicited when the sound signal intensity rises 
rapidly compared to sound rising more slowly to the same level.
    Investigations of fish behavior in relation to vessel noise (Olsen 
et al., 1983; Ona, 1988; Ona and Godo, 1990) have shown that fish react 
when the sound from the engines and propeller exceeds a certain level. 
Avoidance reactions have been observed in fish such as cod and herring 
when vessels approached close enough that received sound levels are 110 
dB to 130 dB (Nakken, 1992; Olsen, 1979; Ona and Godo, 1990; Ona and 
Toresen, 1988). However, other researchers have found that fish such as 
polar cod, herring, and capeline are often attracted to vessels 
(apparently by the noise) and swim toward the vessel (Rostad et al., 
2006). Typical sound source levels of vessel noise in the audible range 
for fish are 150 dB to 170 dB (Richardson et al., 1995a). (Based on 
models, the 160 dB radius for the Discoverer would extend approximately 
33 ft [10 m]; therefore, fish would need to be in close proximity to 
the drillship for the noise to be audible). In calm weather, ambient 
noise levels in audible parts of the spectrum lie between 60 dB to 100 
dB.
    Sound will also occur in the marine environment from the various 
support vessels. Reported source levels for vessels during ice-
management have ranged from 175 dB to 185 dB (Brewer et al., 1993, Hall 
et al., 1994). However, ice management or icebreaking activities are 
not expected to be necessary throughout the entire drilling season, so 
impacts from that activity would occur less frequently than sound from 
the drillship. Sound pressures generated by drilling vessels during 
active drilling operations have been measured during past exploration 
in the Beaufort and Chukchi seas. Sounds generated by drilling and ice-
management are generally low frequency and within the frequency range 
detectable by most fish.

[[Page 69983]]

    Shell also proposes to conduct seismic surveys with an airgun array 
for a short period of time during the drilling season (a total of 
approximately 30-56 hours over the course of the entire proposed 
drilling program). Airguns produce impulsive sounds as opposed to 
continuous sounds at the source. Short, sharp sounds can cause overt or 
subtle changes in fish behavior. Chapman and Hawkins (1969) tested the 
reactions of whiting (hake) in the field to an airgun. When the airgun 
was fired, the fish dove from 82 to 180 ft (25 to 55 m) depth and 
formed a compact layer. The whiting dove when received sound levels 
were higher than 178 dB re 1 [micro]Pa (Pearson et al., 1992).
    Pearson et al. (1992) conducted a controlled experiment to 
determine effects of strong noise pulses on several species of rockfish 
off the California coast. They used an airgun with a source level of 
223 dB re 1 [micro]Pa. They noted:
     Startle responses at received levels of 200-205 dB re 1 
[micro]Pa and above for two sensitive species, but not for two other 
species exposed to levels up to 207 dB;
     Alarm responses at 177-180 dB for the two sensitive 
species, and at 186 to 199 dB for other species;
     An overall threshold for the above behavioral response at 
about 180 dB;
     An extrapolated threshold of about 161 dB for subtle 
changes in the behavior of rockfish; and
     A return to pre-exposure behaviors within the 20-60 minute 
exposure period.
    In summary, fish often react to sounds, especially strong and/or 
intermittent sounds of low frequency. Sound pulses at received levels 
of 160 dB re 1 [micro]Pa may cause subtle changes in behavior. Pulses 
at levels of 180 dB may cause noticeable changes in behavior (Chapman 
and Hawkins, 1969; Pearson et al., 1992; Skalski et al., 1992). It also 
appears that fish often habituate to repeated strong sounds rather 
rapidly, on time scales of minutes to an hour. However, the habituation 
does not endure, and resumption of the strong sound source may again 
elicit disturbance responses from the same fish. Underwater sound 
levels from the drillship and other vessels produce sounds lower than 
the response threshold reported by Pearson et al. (1992), and are not 
likely to result in major effects to fish near the proposed drill 
sites.
    Based on a sound level of approximately 140 dB, there may be some 
avoidance by fish of the area near the drillship while drilling, around 
ice management vessels in transit and during ice management, and around 
other support and supply vessels when underway. Any reactions by fish 
to these sounds will last only minutes (Mitson and Knudsen, 2003; Ona 
et al., 2007) longer than the vessel is operating at that location or 
the drillship is drilling. Any potential reactions by fish would be 
limited to a relatively small area within about 0.21 mi (0.34 km) of 
the drillship during drilling (JASCO, 2007). Avoidance by some fish or 
fish species could occur within portions of this area. No important 
spawning habitats are known to occur at or near the drilling locations.
    Some of the fish species found in the Arctic are prey sources for 
odontocetes and pinnipeds. A reaction by fish to sounds produced by 
Shell's proposed operations would only be relevant to marine mammals if 
it caused concentrations of fish to vacate the area. Pressure changes 
of sufficient magnitude to cause that type of reaction would probably 
occur only very close to the sound source, if any would occur at all 
due to the low energy sounds produced by the majority of equipment 
proposed for use. Impacts on fish behavior are predicted to be 
inconsequential. Thus, feeding odontocetes and pinnipeds would not be 
adversely affected by this minimal loss or scattering, if any, of 
reduced prey abundance.
    Some mysticetes, including bowhead whales, feed on concentrations 
of zooplankton. Bowhead whales primarily feed off Point Barrow in 
September and October. Reactions of zooplankton to sound are, for the 
most part, not known. Their ability to move significant distances is 
limited or nil, depending on the type of zooplankton. A reaction by 
zooplankton to sounds produced by the exploratory drilling program 
would only be relevant to whales if it caused concentrations of 
zooplankton to scatter. Pressure changes of sufficient magnitude to 
cause that type of reaction would probably occur only very close to the 
sound source, if any would occur at all due to the low energy sounds 
produced by the drillship. However, Barrow is located approximately 140 
mi (225 km) east of Shell's Burger prospect. Impacts on zooplankton 
behavior are predicted to be inconsequential. Thus, bowhead whales 
feeding off Point Barrow would not be adversely affected.
    Gray whales are bottom feeders and suck sediment and the benthic 
amphipods that are their prey from the seafloor. The species primary 
feeding habitats are in the northern Bering Sea and Chukchi Sea 
(Nerini, 1984; Moore et al., 1986; Weller et al., 1999). In the 
northeastern Chukchi Sea, gray whales can be found feeding in the 
shallow offshore water area known as Hanna Shoals, which is located 
approximately 25 mi (40 km) northeast from the proposed drill sites. 
This area lies outside of the 120-dB and 160-dB ensonified zones for 
Shell's proposed Chukchi Sea drill sites. Moore et al. (2000) reported 
that in the summer gray whales were clustered along the shore primarily 
between Cape Lisburne and Point Barrow. In 2006 and 2007, gray whales 
were noted to be most abundant along the coast south of Wainwright 
(2006) and nearshore from Wainwright to Barrow (2007) (Thomas et al., 
2007; Thomas et al., 2009). While some gray whales may migrate past or 
through Shell's proposed drill sites, no impacts to gray whales feeding 
at Hanna Shoal are anticipated based on the distance from the proposed 
activity and the area of the ensonified zone. Additionally, Yazvenko et 
al. (2007) studied the impacts of seismic surveys off Sakhalin Island, 
Russia, on feeding gray whales and found that the seismic activity had 
no measurable effect on bottom feeding gray whales in the area.

Potential Impacts From Drill Cuttings

    Discharging drill cuttings or other liquid waste streams generated 
by the drilling vessel could potentially affect marine mammal habitat. 
Toxins could persist in the water column, which could have an impact on 
marine mammal prey species. However, despite a considerable amount of 
investment in research on exposures of marine mammals to 
organochlorines or other toxins, there have been no marine mammal 
deaths in the wild that can be conclusively linked to the direct 
exposure to such substances (O'Shea, 1999).
    The National Pollutant Discharge Elimination System (NPDES) General 
Permit (GP) establishes discharge limits for drilling fluids (at the 
end of a discharge pipe) to a minimum 96-hr LC50 of 30,000 
parts per million. Both modeling and field studies have shown that 
discharged drilling fluids are diluted rapidly in receiving waters 
(Ayers et al., 1980a,b; Brandsma et al., 1980; NRC, 1983; O'Reilly et 
al., 1989; Nedwed et al., 2004; Smith et al., 2004; Neff, 2005). The 
dilution rate is strongly affected by the discharge rate; the NPDES GP 
limits the discharge of cuttings and fluids to 750 bbl/hr. For example, 
the EPA modeled hypothetical 750 bbl/hr discharges of drilling fluids 
in water depths of 66 ft (20 m) in the Beaufort and Chukchi Seas and 
predicted a minimum dilution of 1,326:1 at 330 ft (100 m).

[[Page 69984]]

    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 discharge of drilling 
fluids 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 fluids drop to levels that would have no effect 
within about two minutes of discharge and within 16 ft (5 m) of the 
discharge location.
    Studies by the EPA (2006) and Neff (2005) indicate that although 
planktonic organisms are extremely sensitive to environmental 
conditions (e.g., temperature, light, availability of nutrients, and 
water quality), there is little or no evidence of effects from drilling 
mud and cuttings discharges on plankton. More than 30 OCS well sites 
have been drilled in the Beaufort Sea. The Warthog well was drilled in 
Camden Bay in 35 ft (11 m) of water (Thurston et al., 1999). BOEMRE 
routinely monitored that well site for contaminants and found that it 
had no accumulated petroleum hydrocarbons or heavy metals (Brown et 
al., 2001). Effects on zooplankton present within a few meters of the 
discharge point would be expected, primarily due to sedimentation. 
However, zooplankton and benthic animals are not likely to have long-
term exposures to drilling mud and cuttings because of the episodic 
nature of discharges (typically only a few hours in duration). Results 
of a recent study on a historical drill site in Camden Bay (HH-2) 
showed that movement of drilling mud and cuttings were restricted to 
within 330 ft (100 m) of the discharge site (Trefry and Trocine, 2009).
    Fine-grained particulates and other solids in drilling mud and 
cuttings could cause sublethal effects to organisms in the water 
column. The responses observed following exposure to drilling mud 
include alteration of respiration and filtration rates and altered 
behavior. Zooplankton in the immediate area of discharge from 
exploration drilling operations could potentially be adversely impacted 
by sediments in the water column, which could clog respiratory and 
feeding structures, and they could suffer abrasions. However, because 
of the close proximity that is required to endure such effects, impacts 
are anticipated to be inconsequential.
    Studies in the 1980s, 1999, 2000, and 2002 (Brown et al., 2001 
cited in MMS, 2003) also found that benthic organisms near drilling 
sites in the Beaufort 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. Because discharges from 
drilling mud and cuttings are composed of seawater, impacts to benthic 
organisms are anticipated to be inconsequential and restricted to a 
very small area of the seafloor in the Chukchi Sea.
    Discharges and drill cuttings could impact fish by displacing them 
from the affected area. Additionally, sedimentation could impact fish, 
as demersal fish eggs could be smothered if discharges occur in a 
spawning area during the period of egg production. However, this is 
unlikely in deeper offshore locations, and no specific demersal fish 
spawning locations have been identified at the Burger well 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. Based on 
this information, drilling muds and cutting wastes are not anticipated 
to have long-term impacts to marine mammals or their prey.

Potential Impacts From Drillship Presence

    The Discoverer is 514 ft (156.7 m) long. If an animal's swim path 
is directly perpendicular to the drillship, the animal will need to 
swim around the ship in order to pass through the area. The length of 
the drillship (approximately one and a half football fields) is not 
significant enough to cause a large-scale diversion from the animals' 
normal swim and migratory paths. Additionally, the eastward spring 
bowhead whale migration will occur prior to the beginning of Shell's 
proposed exploratory drilling program. Moreover, any deflection of 
bowhead whales or other marine mammal species due to the physical 
presence of the drillship or its support vessels would be very minor. 
The drillship's physical footprint is small relative to the size of the 
geographic region it will occupy and will likely not cause marine 
mammals to deflect greatly from their typical migratory route. Also, 
even if animals may deflect because of the presence of the drillship, 
the Chukchi Sea is much larger in size than the length of the drillship 
(many dozens to hundreds of miles vs. less than two football fields), 
and animals would have other means of passage around the drillship. 
While there are other vessels that will be on location to support the 
drillship, most of those vessels will remain within a few kilometers of 
the drillship (with the exception of the ice management vessels which 
will remain approximately 25 mi [40 km] upwind of the drillship when 
not in use). In sum, the physical presence of the drillship is not 
likely to cause a significant deflection to migrating marine mammals.

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.

Potential Impacts From Ice Management/Icebreaking Activities

    Ice management activities include the physical pushing or moving of 
ice to create more open-water in the proposed drilling area and to 
prevent ice floes from striking the drillship. Icebreaking activities 
include the physical breaking of ice. Shell does not intend to conduct 
icebreaking activities. However, should

[[Page 69985]]

there be a need for icebreaking, it would only be performed in order to 
safely move the drillship and other vessels off location and to end 
operations for the season. Ringed, bearded, spotted, and ribbon seals 
(along with the walrus) 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. Should ice 
management/icebreaking activities be necessary during the proposed 
drilling program, Shell would only manage pack ice in either early to 
mid-July or mid- to late October. Landfast ice would not be present 
during Shell's proposed operations.
    The ringed seal is the most common pinniped species in the proposed 
project area. While ringed seals use ice year-round, they do not 
construct lairs for pupping until late winter/early spring on the 
landfast ice. Therefore, since Shell plans to conclude drilling by 
October 31, Shell's activities would not impact ringed seal lairs or 
habitat needed for breeding and pupping in the Chukchi Sea. Aerial 
surveys in the eastern Chukchi Sea conducted in late May-early June 
1999-2000 found that ringed seals were four to ten times more abundant 
in nearshore fast and pack ice environments than in offshore pack ice 
(Bengtson et al., 2005). Ringed seals can be found on the pack ice 
surface in the late spring and early summer in the northern Chukchi 
Sea, the latter part of which may overlap with the start of Shell's 
proposed drilling activities. If an ice floe is pushed into one that 
contains hauled out seals, the animals may become startled and enter 
the water when the two ice floes collide. Bearded seals breed in the 
Bering and Chukchi Seas from mid-March through early May (several 
months prior to the start of Shell's operations). Bearded seals require 
sea ice for molting during the late spring and summer period. Because 
this species feeds on benthic prey, bearded seals occur over the pack 
ice front over the Chukchi Sea shelf in summer (Burns and Frost, 1979) 
but were not associated with the ice front when it receded over deep 
water (Kingsley et al., 1985). The spotted seal does not breed in the 
Chukchi Sea. Spotted seals molt most intensely during May and June and 
then move to the coast after the sea ice has melted. Ribbon seals are 
not known to breed in the Chukchi Sea. From July-October, when sea ice 
is absent, the ribbon seal is entirely pelagic, and its distribution is 
not well known (Burns, 1981; Popov, 1982). Therefore, ice used by 
bearded, spotted, and ribbon seals needed for life functions such as 
breeding and molting would not be impacted as a result of Shell's 
drilling program since these life functions do not occur in the 
proposed project area or at the same time as Shell's operations. For 
ringed seals, ice management/icebreaking activities would occur during 
a time when life functions such as breeding, pupping, and molting do 
not occur in the proposed activity area. Additionally, these life 
functions normally occur on landfast ice, which will not be impacted by 
Shell's activity.

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).

Mitigation Measures Proposed by Shell

    Shell submitted a 4MP as part of its application (Attachment C; 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 design features 
and operational procedures have been described in the IHA and LOA 
applications submitted to NMFS and USFWS, respectively, and are 
summarized here. Survey design features include:
     Timing and locating drilling and support activities to 
avoid interference with the annual subsistence hunts by the peoples of 
the Chukchi villages;
     Identifying transit routes and timing to avoid other 
subsistence use areas and communicating with coastal communities before 
operating in or passing through these areas; and
     Conducting pre-season sound propagation modeling to 
establish the appropriate exclusion and behavioral radii.
    Shell indicates that the potential disturbance of marine mammals 
during operations will be minimized further through the implementation 
of several ship-based mitigation measures, which include establishing 
and monitoring safety and disturbance zones.
    Exclusion radii for marine mammals around sound sources are 
customarily defined as the distances within which received sound levels 
are greater than or equal to 180 dB re 1 [micro]Pa (rms) for cetaceans 
and greater than or equal to 190 dB re 1 [micro]Pa (rms) for pinnipeds. 
These exclusion criteria are based on an assumption that sounds at 
lower received levels will not injure these animals or impair their 
hearing abilities, but that higher received levels might have such 
effects. It should be understood that marine mammals inside these 
exclusion zones will not necessarily be injured, as the received sound 
thresholds which determine these zones were established prior to the 
current understanding that significantly higher levels of sound would 
be required before injury would likely occur (see Southall et al., 
2007). With respect to Level B harassment, NMFS' practice has been to 
apply the 120 dB re 1 [micro]Pa (rms) received level threshold for 
underwater continuous sound levels and the 160 dB re 1 [micro]Pa (rms) 
received level threshold for underwater impulsive sound levels.
    Shell proposes to monitor the various radii in order to implement 
any mitigation measures that may be necessary. Initial radii for the 
sound levels produced by the Discoverer, the icebreaker, and the 
airguns have been modeled. Measurements taken by Austin and Warner 
(2010) indicated broadband source levels between 177 and 185 dB re 1 
[micro]Pa rms for the Discoverer. Measurements of the icebreaking 
supply ship Robert Lemeur pushing and breaking ice during exploration 
drilling operations in the Beaufort Sea in 1986 resulted in an 
estimated broadband source level of 193 dB re 1 [micro]Pa rms (Greene, 
1987a; Richardson et al., 1995a). Based on a similar airgun array used 
in the shallow waters of the Beaufort Sea in 2008 by BP, the source 
level of the airgun is predicted to be 241.4 dB re 1 [micro]Pa rms. 
Once on location in the Chukchi Sea, Shell will conduct sound source 
verification (SSV) tests to establish safety zones for the previously 
mentioned sound level criteria. The objectives of the SSV tests are: 
(1) To quantify the absolute sound levels produced by drilling and to 
monitor their variations with time, distance, and direction from the 
drillship; and (2) to measure the sound levels produced by

[[Page 69986]]

vessels operating in support of drilling operations, which include crew 
change vessels, tugs, ice management vessels, and spill response 
vessels. The methodology for conducting the SSV tests is fully 
described in Shell's 4MP (see ADDRESSES). Please refer to that document 
for further details. Upon completion of the SSV tests, the new radii 
will be established and monitored, and mitigation measures will be 
implemented in accordance with Shell's 4MP.
    Based on the best available scientific literature, the source 
levels noted above for exploration drilling are not high enough to 
cause a temporary reduction in hearing sensitivity or permanent hearing 
damage to marine mammals. Consequently, Shell believes that mitigation 
as described for seismic activities including ramp ups, power downs, 
and shutdowns should not be necessary for drilling activities. NMFS has 
also determined that these types of mitigation measures, traditionally 
required for seismic survey operations, are not practical or necessary 
for this proposed drilling activity. Seismic airgun arrays can be 
turned on slowly (i.e., only turning on one or some guns at a time) and 
powered down quickly. The types of sound sources used for exploratory 
drilling have different properties and are unable to be ``powered 
down'' like airgun arrays or shutdown instantaneously without posing 
other risks to operational and human safety. However, Shell plans to 
use Protected Species Observers (PSOs, formerly referred to as marine 
mammal observers) onboard the drillship and the various support vessels 
to monitor marine mammals and their responses to industry activities 
and to initiate mitigation measures (for ZVSP activities) should in-
field measurements of the operations indicate that such measures are 
necessary. Additional details on the PSO program are described in the 
``Proposed Monitoring and Reporting'' section found later in this 
document. Also, for the ZVSP activities, Shell proposes to implement 
standard mitigation procedures, such as ramp ups, power downs, and 
shutdowns.
    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 the time for them to leave 
the area and thus avoid any potential injury or impairment of their 
hearing abilities.
    During the proposed ZVSP surveys, Shell 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 a minimum of 30 
minutes of observation of the 180-dB and 190-dB exclusion zones for 
cetaceans and pinnipeds, respectively, by PSOs to assure that no marine 
mammals are present. The entire exclusion zone must be visible during 
the 30-minute lead-in to a full ramp up. If the entire exclusion zone 
is not visible, then ramp up from a cold start cannot begin. If a 
marine mammal(s) is sighted within the exclusion zone during the 30-
minute watch prior to ramp up, ramp up will be delayed until the marine 
mammal(s) is sighted outside of the applicable exclusion zone or the 
animal(s) is not sighted for at least 15 minutes for small odontocetes 
and pinnipeds or 30 minutes for baleen whales.
    A power down is the immediate reduction in the number of operating 
energy sources from all firing to some smaller number. A shutdown 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 shutdown 
(i.e., no sources firing). The same 15 and 30 minute sighting times 
described for ramp up also apply to starting the airguns again after 
either a power down or shutdown.
    Additional mitigation measures proposed by Shell include: (1) 
Reducing speed and/or changing course if a marine mammal is sighted 
from a vessel in transit (NMFS has proposed a specific distance in the 
next subsection); (2) resuming full activity (e.g., full support vessel 
speed) only after marine mammals are confirmed to be outside the safety 
zone; (3) implementing flight restrictions prohibiting aircraft from 
flying below 1,500 ft (457 m) altitude (except during takeoffs and 
landings or in emergency situations); and (4) keeping vessels anchored 
when approached by marine mammals to avoid the potential for avoidance 
reactions by such animals.
    Shell has also proposed additional mitigation measures to ensure no 
unmitigable adverse impact on the availability of affected species or 
stocks for taking for subsistence uses. Those measures are described in 
the ``Impact on Availability of Affected Species or Stock for Taking 
for Subsistence Uses'' section found later in this document.

Additional Mitigation Measures Proposed by NMFS

    In addition to the mitigation measures proposed by Shell, NMFS 
proposes the following measures (which apply to vessel operations) be 
included in the IHA, if issued, in order to ensure the least 
practicable impact on the affected species or stocks. NMFS proposes to 
require Shell to avoid multiple changes in direction or speed when 
within 300 yards (274 m) of whales. Additionally, NMFS proposes to 
require Shell to reduce speed in inclement weather.

Oil Spill Contingency Plan

    In accordance with BOEM regulations, Shell has developed an Oil 
Discharge Prevention and Contingency Plan (ODPCP) for its Chukchi Sea 
exploration drilling program. A copy of this document can be found on 
the Internet at: http://www.alaska.boemre.gov/fo/ODPCPs/2010_Chukchi_rev1.pdf. Additionally, in its Plan of Cooperation (POC), Shell has 
agreed to several mitigation measures in order to reduce impacts during 
the response efforts in the unlikely event of an oil spill. Those 
measures are detailed in the ``Plan of Cooperation (POC)'' section 
found later in this document. The ODPCP is currently under review by 
the Department of the Interior and other agencies. A final decision on 
the adequacy of the ODPCP is expected prior to the start of Shell's 
2012 Chukchi Sea drilling program.
    NMFS has carefully evaluated Shell'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:
     The manner in which, and the degree to which, the 
successful implementation of the measure is expected to minimize 
adverse impacts to marine mammals;
     The proven or likely efficacy of the specific measure to 
minimize adverse impacts as planned; and
     The practicability of the measure for applicant 
implementation.
    Proposed measures to ensure availability of such species or stock 
for taking for certain subsistence uses is discussed later in this 
document (see

[[Page 69987]]

``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, where applicable, 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.

Monitoring Measures Proposed by Shell

    The monitoring plan proposed by Shell can be found in the 4MP 
(Attachment C of Shell's application; see ADDRESSES). 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). A summary of the primary components of the plan 
follows. Later in this document in the ``Proposed Incidental Harassment 
Authorization'' section, NMFS lays out the proposed monitoring and 
reporting conditions, as well as the mitigation conditions, for review, 
as they would appear in the final IHA (if issued).
(1) Vessel-Based PSOs
    Vessel-based monitoring for marine mammals will be done by trained 
PSOs throughout the period of drilling operations on all vessels. PSOs 
will monitor the occurrence and behavior of marine mammals near the 
drillship during all daylight periods during operation and during most 
daylight periods when drilling operations are not occurring. PSO duties 
will include watching for and identifying marine mammals, recording 
their numbers, distances, and reactions to the drilling operations. A 
sufficient number of PSOs will be required onboard each vessel to meet 
the following criteria: (1) 100% monitoring coverage during all periods 
of drilling operations in daylight; (2) maximum of 4 consecutive hours 
on watch per PSO; and (3) maximum of 12 hours of watch time per day per 
PSO. Shell anticipates that there will be provision for crew rotation 
at least every 3-6 weeks to avoid observer fatigue.
    Biologist-observers will have previous marine mammal observation 
experience, and field crew leaders will be highly experienced with 
previous vessel-based marine mammal monitoring projects. Resumes for 
those individuals will be provided to NMFS so that NMFS can review and 
accept their qualifications. Inupiat observers will be experienced in 
the region, familiar with the marine mammals of the area, and complete 
a NMFS approved observer training course designed to familiarize 
individuals with monitoring and data collection procedures. A handbook, 
adapted for the specifics of the planned Shell drilling program, will 
be prepared and distributed beforehand to all PSOs.
    PSOs will watch for marine mammals from the best available vantage 
point on the drillship and support vessels. PSOs will scan 
systematically with the unaided 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 PSOs in watching 
for marine mammals. 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 PSOs will include the same types of 
information that were recorded during recent monitoring programs 
associated with industry activity in the Arctic (e.g., Ireland et al., 
2009). The recording will include information about the animal sighted, 
environmental and operational information, and the position of other 
vessels in the vicinity of the sighting. 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.
    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. PSOs may use a laser rangefinder to test and improve their 
abilities for visually estimating distances to objects in the water. 
However, previous experience showed that a Class 1 eye-safe device was 
not able to measure distances to seals more than about 230 ft (70 m) 
away. The device was very useful in improving the distance estimation 
abilities of the observers at distances up to about 1968 ft (600 m)--
the maximum range at which the device could measure distances to highly 
reflective objects such as other vessels. Humans observing objects of 
more-or-less known size via a standard observation protocol, in this 
case from a standard height above water, quickly become able to 
estimate distances within about  20% when given immediate 
feedback about actual distances during training.
(2) Aerial Survey Program
    Recent aerial surveys of marine mammals in the Chukchi Sea were 
conducted over coastal areas to approximately 23 mi (37 km) offshore in 
2006-2008 and 2010 in support of Shell's summer seismic exploration 
activities. These surveys were designed to provide data on the 
distribution and abundance of marine mammals in nearshore waters of the 
Chukchi Sea. Shell proposes to conduct an aerial survey program in the 
Chukchi Sea in 2012 that would be similar to the previous programs.
    The current aerial survey program will be designed to collect data 
on cetaceans but will be limited in its ability to collect similar data 
on pinnipeds. Shell's objectives for this program include:
     To collect data on the distribution and abundance of 
marine mammals in coastal areas of the eastern Chukchi Sea; and
     To collect and report data on the distribution, numbers, 
orientation and behavior of marine mammals, particularly beluga whales, 
near traditional hunting areas in the eastern Chukchi Sea.
    With agreement from hunters in the coastal villages, aerial surveys 
of coastal areas to approximately 23 mi (37 km) offshore between Point 
Hope and Point Barrow will begin in early to mid-July and will continue 
until drilling operations in the Chukchi Sea are completed. Weather and 
equipment permitting, surveys will be conducted twice per week during 
this time period. In addition, during the 2012 drilling season, aerial 
surveys will be coordinated in cooperation with the aerial surveys 
funded by BOEMRE and conducted by NMFS and any other groups conducting 
surveys in the region. A full description of Shell's survey procedures 
can be found in the 4MP of Shell's application (see ADDRESSES). A 
summary follows next.
    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 (see Figure 6 of Shell's 4MP). This design will 
permit completion of the survey in one to two days and will provide 
representative coverage of the

[[Page 69988]]

nearshore region. The surveyed area will include waters where belugas 
are normally available to subsistence hunters. Survey altitude will be 
at least 1,000 ft (305 m) with an average survey speed of 110-120 
knots. 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.
    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) 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. If large 
concentrations of belugas are encountered during the survey, the survey 
may be interrupted to photograph the groups to obtain better counts of 
the number of animals present. If whales are photographed in lagoons or 
other shallow-water concentration areas, the aircraft will climb to 
approximately 10,000 ft (3,050 m) altitude to avoid disturbing the 
whales and causing them to leave the area. If whales are in offshore 
areas, the aircraft will climb high enough to include all whales within 
a single photograph; typically about 3,000 ft (914 m) altitude.
    Three PSOs will be aboard the aircraft during surveys. Two primary 
observers will be looking for marine mammals; one each at bubble 
windows on either side of the aircraft. The third person will record 
data. For each marine mammal sighting, the observer will dictate the 
species, number, size/age/sex class when determinable, activity, 
heading, swimming speed category (if traveling), sighting cue, ice 
conditions (type and percentage), and inclinometer reading to the 
marine mammal into a digital recorder. The inclinometer reading will be 
taken when the animal's location is 90[deg] to the side of the aircraft 
track, allowing calculation of lateral distance from the aircraft 
trackline.
    Transect information, sighting data and environmental data will be 
entered into a GPS-linked computer by the third observer and 
simultaneously recorded on digital voice recorders for backup and 
validation. At the start of each transect, the observer recording data 
will record the transect start time and position, ceiling height (ft), 
cloud cover (in 10ths), wind speed (knots), wind direction ([deg]T) and 
outside air temperature ([deg]C). In addition, each observer will 
record the time, visibility (subjectively classified as excellent, 
good, moderately impaired, seriously impaired or impossible), sea state 
(Beaufort wind force), ice cover (in 10ths) and sun glare (none, 
moderate, severe) at the start and end of each transect, and at 2 min 
intervals along the transect. The data logger will automatically record 
time and aircraft position (latitude and longitude) for sightings and 
transect waypoints, and at pre-selected intervals along the transects.
(3) Acoustic Monitoring
    As discussed earlier in this document, Shell will conduct SSV tests 
to establish the isopleths for the applicable exclusion radii, mostly 
to be employed during the ZVSP surveys. In addition, Shell proposes to 
use an acoustic ``net'' array.
    Drilling Sound Measurements--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 Discoverer. The objectives of these measurements are:
    (1) To quantify the absolute sound levels produced by drilling and 
to monitor their variations with time, distance, and direction from the 
drilling vessel;
    (2) To measure the sound levels produced by vessels operating in 
support of exploration drilling operations. These vessels will include 
crew change vessels, tugs, icebreakers, and OSRVs; and
    (3) To measure the sound levels produced by an end-of-hole ZVSP 
survey, using a stationary sound source.
    The Discoverer, support vessels, and ZVSP sound measurements will 
be performed using one of two methods, both of which involve real-time 
monitoring. The first method would involve use of bottom-founded 
hydrophones cabled back to the Discoverer (see Figure 1 in Shell's 
4MP). These hydrophones would be positioned between 1,640 ft (500 m) 
and 3,281 ft (1,000 m) from the Discoverer, depending on the final 
positions of the anchors used to hold the Discoverer in place. 
Hydrophone cables would be fed to real-time digitization systems 
onboard. In addition to the cabled system, a separate set of bottom-
founded hydrophones (see Figure 2 in Shell's 4MP) may be deployed at 
various distances from the exploration drilling operation for storage 
of acoustic data to be retrieved and processed at a later date.
    As an alternative to the cabled hydrophone system (and possible 
inclusion of separate bottom-founded hydrophones), the second (or 
alternative) monitoring method would involve a radio buoy approach 
deploying four sparbuoys 4-5 mi (6-8 km) from the Discoverer. 
Additional hydrophones may be deployed closer to the Discoverer, if 
necessary, to better determine sound source levels. Monitoring 
personnel and recording/receiving equipment would be onboard one of the 
support vessels with 24-hr monitoring capacity. The system would allow 
for collection and processing of real-time data similar to that 
provided by the cabled system but from a wider range of locations.
    Sound level monitoring with either method will occur on a 
continuous basis throughout all exploration drilling activities. Both 
types of systems will be set to record digital acoustic data at a 
sample rate of 32 kHz, providing useful acoustic bandwidth to at least 
15 kHz. These systems are capable of measuring absolute broadband sound 
levels between 90 and 180 dB re 1 [micro]Pa. The long duration 
recordings will capture many different operations performed from the 
drillship. Retrieval of these systems will occur following completion 
of the exploration drilling activities.
    These recorders will provide a capability to examine sound levels 
produced by different drilling activities and practices. This system 
will not have the capability to locate calling marine mammals and will 
indicate only relative proximity. The system will be evaluated during 
operations for its potential to improve PSO observations through 
notification of PSOs on vessel and aircraft of high levels of call 
detections and their general locations.
    The deployment of drilling sound monitoring equipment will occur as 
soon as possible once the drillship is on site. Activity logs of 
exploration drilling operations and nearby vessel activities will be 
maintained to correlate with these acoustic measurements. This 
equipment will also be used to take measurements of the support vessels 
and airguns. Additional details can be found in Shell's 4MP.
    Acoustic ``Net'' Array--The acoustic ``net'' array used by Shell 
during the 2006-2010 field seasons is proposed for 2011 and 2012. The 
array was designed to accomplish two main objectives:
     To collect information on the occurrence and distribution 
of marine

[[Page 69989]]

mammals that may be available to subsistence hunters near villages 
located on the Chukchi Sea coast and to document their relative 
abundance, habitat use, and migratory patterns; and
     To measure the ambient soundscape throughout the eastern 
Chukchi Sea and to record received levels of sound from industry and 
other activities further offshore in the Chukchi Sea.
    The net array configuration used in 2007-2010 is again proposed for 
2011 and 2012. The basic components of this effort consist of 30 
hydrophone systems placed widely across the U.S. Chukchi Sea and a 
prospect specific array of 12 hydrophones capable of localization of 
marine mammal calls. The net array configuration will include 
hydrophone systems distributed at each of the four primary transect 
locations: Cape Lisburne; Point Hope; Wainwright; and Barrow. The 
systems comprising the regional array will be placed at locations shown 
in Figure 7 of the 4MP in Shell's application (see ADDRESSES). These 
offshore systems will capture exploration drilling sounds, if present, 
over large distances to help characterize the sound transmission 
properties in the Chukchi Sea and will also provide a large amount of 
information related to marine mammals in the Chukchi Sea.
    The regional acoustic monitoring program will be augmented in 2012 
by an array of additional acoustic recorders to be deployed on a grid 
pattern over a 7.2 mi (12 km) by 10.8 mi (18 km) area extending over 
several of Shell's lease blocks near locations of highest interest for 
exploration drilling in 2012. The cluster array will operate at a 
sampling frequency of 16 kHz, which is sufficient to capture 
vocalizations from bowhead, beluga, gray, fin, humpback, and killer 
whales, and most other marine mammals known to be present in the 
Chukchi Sea. The cluster deployment configuration was defined to allow 
tracking of vocalizing animals that pass through the immediate area of 
these lease blocks. Maximum separation between adjacent recorders is 
3.6 mi (5.8 km). At this spacing, Shell expects that individual whale 
calls will be detected on at least three different recorders when the 
calling animals are within the boundary of the deployment pattern. 
Bowhead and other mysticete calls should be detectable simultaneously 
on more than three recorders due to their relatively higher sound 
source levels compared to other marine mammals. In calm weather 
conditions, when ambient underwater sound levels are low, Shell expects 
to detect most other marine mammal calls on more than three recorders. 
The goal of simultaneous detection on multiple recorders is to allow 
for triangulation of the call positions, which also requires accurate 
time synchronization of the recorders. When small numbers of whales are 
vocalizing, Shell hopes to be able to identify and track the movements 
of specific individuals within the deployment area. It will not be 
possible to track individual whales if many whales are calling due to 
abundant overlapping calls. In this case, analyses will show the 
general distribution of calls in the vicinity of the recorders.
    Additional details on data analysis for the types of monitoring 
described here (i.e., vessel-based, aerial, and acoustic) can be found 
in the 4MP in Shell's application (see ADDRESSES).

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 2012. The panel is scheduled to meet in early 
January 2012, 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 preliminary results of the acoustic verification 
measurements, including as a minimum the measured 190- , 180- , 160- , 
and 120-dB (rms) radii of the drillship, support vessels, and airgun 
array will be submitted within 120 hr after collection and analysis of 
those measurements at the start of the field season or in the case of 
the airgun once that part of the program is implemented. This report 
will specify the distances of the exclusion zones that were adopted for 
the exploratory drilling program. Prior to completion of these 
measurements, Shell will use the radii outlined in their application 
and elsewhere in this document.
(2) Technical Reports
    The results of Shell's 2012 Chukchi Sea exploratory drilling 
monitoring program (i.e., vessel-based, aerial, and acoustic) will be 
presented in the ``90-day'' and Final Technical reports, as required by 
NMFS 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 drillship 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 Directional 
Autonomous Seafloor Acoustic Recorder; (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 drillship activities. The bowhead 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).

[[Page 69990]]

    The initial technical report is due to NMFS within 90 days of the 
completion of Shell's Beaufort Sea exploratory 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.
(3) Comprehensive Report
    Following the 2012 drilling season, a comprehensive report 
describing the vessel-based, aerial, and acoustic monitoring programs 
will be prepared. 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 industry activities, and 
other activities that occur in the Beaufort and/or Chukchi seas, and 
their impacts on marine mammals during 2012. The report will help to 
establish long-term data sets that can assist with the evaluation of 
changes in the Chukchi and Beaufort Sea ecosystems. The report will 
attempt to provide a regional synthesis of available data on industry 
activity in offshore areas of northern Alaska that may influence marine 
mammal density, distribution and behavior.
(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 of 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 drillship, 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 
drillship 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 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. Finally, based on 
the proposed mitigation and monitoring measures described earlier in 
this document and the fact that the back-propagated source level for 
the drillship is estimated to be between 177 and 185 dB re 1 [mu]Pa 
(rms), no injury or mortality of marine mammals is anticipated as a 
result of Shell's proposed exploratory drilling program.
    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 the Discoverer and by the icebreaker 
during icebreaking activities 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 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 [mu]Pa (rms) during drillship operations 
or icebreaking activities and impulse sounds >=160 dB re 1 [mu]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 120 dB or 160 dB re 1 [mu]Pa 
rms'' subsection.
    Marine mammal densities near the operation are likely to vary by 
season and habitat, mostly related to the presence or absence of sea 
ice. Marine mammal density estimates in the Chukchi Sea have been 
derived for two

[[Page 69991]]

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 operations are occurring: Open 
water or ice margin. More ice is likely to be present in the area of 
operations during the summer period, so summer ice-margin densities 
have been applied to 50 percent of the area that may be exposed to 
sounds from exploration 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 fall 
season, so fall ice-margin densities have been applied to only 20 
percent of the area that may be exposed to sounds from exploration 
drilling and ZVSP activities in those months. Fall open-water densities 
were applied to the remaining 80 percent 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.
    Shell notes that 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, and in 
those cases the mean and maximum estimates were determined from the 
survey data. In other cases, no applicable estimate (or perhaps a 
single estimate) was available, so correction factors were used to 
arrive at ``average'' and ``maximum'' estimates. These are described in 
detail in the following subsections. Table 6-7 in Shell's application 
indicates that the ``average estimate'' for killer, fin, humpback, and 
minke whales, harbor porpoise, and ribbon seal is either zero or one. 
Therefore, to account for the fact that these species listed as being 
potentially taken by harassment in this document may occur in Shell's 
proposed drilling sites during active operations, NMFS either used the 
``maximum estimates'' or made an estimate based on typical group size 
for a particular species.
    Detectability bias, quantified in part by f(0), is associated with 
diminishing sightability with increasing lateral distance from the 
trackline. Availability bias [g(0)] refers to the fact that there is 
<100 percent probability of sighting an animal that is present along 
the survey trackline. Some sources of densities used below included 
these correction factors in their reported densities (e.g., ringed 
seals in Bengtson et al., 2005). In other cases the best available 
correction factors were applied to reported results when they had not 
been included in the reported data (e.g., Moore et al., 2000).
    Estimated densities of marine mammals in the Chukchi Sea project 
area during the summer period (July-August) are presented in Table 6-1 
in Shell's application and Table 2 here, and estimated fall densities 
(September-October) are presented in Table 6-2 in Shell's application 
and Table 3 here. Descriptions of the individual density estimates 
shown in the tables are presented next.
(1) Cetaceans
    Beluga Whales--Summer densities of belugas in offshore waters are 
expected to be low, with somewhat higher densities in ice-margin and 
nearshore areas. Aerial surveys have recorded few belugas in the 
offshore Chukchi Sea during the summer months (Moore et al., 2000). 
Aerial surveys of the Chukchi Sea in 2008-2009 flown by NMFS' National 
Marine Mammal Laboratory (NMML) as part of the Chukchi Offshore 
Monitoring in Drilling Area project (COMIDA) have only reported five 
beluga sightings during more than 8,700 mi (14,001 km) of on-transect 
effort, only two of which were offshore (COMIDA, 2009). One of the 
three nearshore sightings was of a large group (approximately 275 
individuals on July 12, 2009) of migrating belugas along the coastline 
just north of Peard Bay. Additionally, only one beluga sighting was 
recorded during more than 37,900 mi (60,994 km) of visual effort during 
good visibility conditions from industry vessels operating in the 
Chukchi Sea in September-October of 2006-2008 (Haley et al., 2010). 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. Expected densities have previously been calculated from data 
in Moore et al. (2000). However, more recent data from COMIDA aerial 
surveys during 2008-2010 are now available (Clarke and Ferguson, in 
prep.). Effort and sightings reported by Clarke and Ferguson (in prep.) 
were used to calculate the average open-water density estimate. Clarke 
and Ferguson (in prep.) reported two on-transect beluga sightings (5 
individuals) during 11,985 km of on-transect effort in waters 118-164 
ft (36-50 m) deep in the Chukchi Sea during July and August. The mean 
group size of these two sightings is 2.5. 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. The CV associated with group size was used to 
select an inflation factor of 2 to estimate the maximum density that 
may occur in both open-water and ice-margin habitats. 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 4 
was used to estimate the average ice-margin density from the open-water 
density. Very low densities observed from vessels operating in the 
Chukchi Sea during non-seismic periods and locations in July-August of 
2006-2008 (0.0-0.0003/mi\2\, 0.0-0.0001/km\2\; Haley et al., 2010), 
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 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, 
2010). However, there were no beluga sightings reported during more 
than 11,200 mi (18,025 km) of vessel based effort in good visibility 
conditions during 2006-2008 industry operations in the Chukchi Sea 
(Haley et al., 2010). Densities derived from survey results in the 
northern Chukchi Sea in Clarke and Ferguson (in prep) were used as the 
average density for open-water fall season estimates (see Table 6-2 in 
Shell's application and Table 3 here). Clarke and Ferguson (in prep) 
reported 3 beluga sightings (6 individuals) during 6,236 mi (10,036 km) 
of on-transect effort in water depths 118-164 ft (36-50 m). The mean 
group size of those three sightings is 2. A f(0) value of 2.841 and 
g(0) value of 0.58 from Harwood et al. (1996) were used in the 
calculation. The same inflation factor of 2 used for summer densities 
was used to estimate the maximum density that may occur in both open-
water and ice-margin habitats in the fall. 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 4 
was used to estimate the average ice-margin density from the open-water 
density. Based on the lack of any beluga sightings from vessels 
operating in the Chukchi Sea during non-seismic periods and locations 
in September-October of 2006-2008 (Haley et al., 2010), the relatively 
low

[[Page 69992]]

densities shown in Table 6-2 in Shell's application and Table 3 here 
are consistent with what is likely to be observed from vessels during 
the planned operations.
[GRAPHIC] [TIFF OMITTED] TN09NO11.002


[[Page 69993]]


    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 6,640 mi 
(10,686 km) of on-transect effort in the Chukchi Sea by Moore et al. 
(2000). Aerial surveys in 2008-2010 by NMML as part of the COMIDA 
project reported only six sightings during more than 16,020 mi (25,781 
km) of on-transect effort (Clarke and Ferguson, in prep.). Two of the 
six sightings were in waters less than 115 ft (35 m) deep, and the 
remaining four sightings were in waters 167-656 ft (51-200 m) deep. 
Bowhead whales were also rarely sighted in July-August of 2006-2008 
during aerial surveys of the Chukchi Sea coast (Thomas et al., 2010). 
This is consistent with movements of tagged whales (see 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 bowhead whale density in the Chukchi Sea 
was calculated by assuming there was one bowhead sighting during the 
7,447 mi (11,985 km) of survey effort in waters 118-164 ft (36-50 m) 
deep in the Chukchi Sea during July-August reported in Clarke and 
Ferguson (in prep.) although no bowheads were actually observed during 
those surveys. The mean group size from September-October sightings 
reported in Clarke and Ferguson (in prep.) is 1.1, and this was also 
used in the calculation of summer densities. 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 bowhead whales 
(see Table 6-1 in Shell's application and Table 2 here). The CV of 
group size and standard errors reported in Thomas et al. (2002) for 
f(0) and g(0) correction factors suggest that an inflation factor of 2 
is appropriate for estimating the maximum density from the average 
density. Bowheads are not expected to be encountered in higher 
densities near ice in the summer (Moore et al., 2000), so the same 
density estimates are 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 2006-2008 (Haley et 
al., 2010) ranged from 0.0003-0.0018/mi\2\ (0.0001-0.0007/km\2\) with a 
maximum 95% confidence interval (CI) of 0.0075/mi\2\ (0.0029 km\2\).
    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 that bowheads will be encountered 
in the Chukchi Sea at this time of year. Moore et al. (2002; Table 8) 
reported 34 bowhead sightings during 27,560 mi (44,354 km) of on-
transect survey effort in the Chukchi Sea during September-October. 
Thomas et al. (2010) also reported increased sightings on coastal 
surveys of the Chukchi Sea during September and October of 2006-2008. 
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 exploration 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). Clarke and 
Ferguson (in prep) reported 14 sightings (15 individuals) during 6,236 
mi (10,036) km of on transect aerial survey effort in 2008-2010. The 
mean group size of those sightings is 1.1. The same f(0) and g(0) 
values that were used for the summer estimates above were used for the 
fall estimates. As with the summer estimates, an inflation factor of 2 
was used to estimate the maximum density from the average density in 
both habitat types. 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 a density of twice the average 
open-water density was used as the average ice-margin density. 
Densities from vessel based surveys in the Chukchi Sea during non-
seismic periods and locations in July-August of 2006-2008 (Haley et 
al., 2010) ranged from 0.0008 to 0.0114/mi\2\ (0.0003-0.0044/km\2\) 
with a maximum 95% CI of 0.1089/mi\2\ (0.0419 km\2\).
    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 115 ft (35 m) deep. Thomas et al. (2010) 
also reported substantial declines in the sighting rates of gray whales 
in the fall. The average open-water summer density (see Table 6-1 in 
Shell's application and Table 2 here) was calculated from 2008-2010 
aerial survey effort and sightings in Clarke and Ferguson (in prep.) 
for water depths 118-164 ft (36-50 m) including 54 sightings (73 
individuals) during 7,447 mi (11,985 km) of on-transect effort. The 
average group size of those sightings is 1.35. Correction factors f(0) 
= 2.49 (Forney and Barlow, 1998) and g(0) = 0.3 (Forney and Barlow, 
1998; Mallonee, 1991) were also used in the density calculation. 
Similar to beluga and bowhead whales, an inflation factor of 2 was used 
to estimate the maximum densities from average densities in both 
habitat types and seasons. 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 2006-2008 (Haley et 
al., 2010) ranged from 0.0055mi\2\ to 0.0208/mi\2\ (0.0021/km\2\ to 
0.008/km\2\) with a maximum 95% CI of 0.0874 mi\2\ (0.0336 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 (15 sightings [19 individuals] 
during 6,236 mi [10,036 km] of on-transect effort) in water 118-164 ft 
(36-50 m) deep during September-October reported by Clarke and Ferguson 
(in prep.) was used as the average estimate for the Chukchi Sea during 
the fall period. The corresponding group size value of 1.26, along with 
the same f(0) and g(0) values described above were used in the 
calculation. Densities from vessel based surveys in the Chukchi Sea 
during non-seismic periods and locations in July-August of 2006-2008 
(Haley et al., 2010) ranged from 0.0068/mi\2\ to 0.0109/mi\2\ (0.0026/
km\2\ to 0.0042/km\2\) with a maximum 95% CI of 0.072 mi\2\ (0.0277 
km\2\).
    Harbor Porpoise--Harbor porpoise densities were estimated from 
industry data collected during 2006-2008 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-
2008, however, recorded sightings throughout the Chukchi Sea during the 
summer and early fall months. Density estimates from 2006-2008 
observations during non-seismic periods and locations in July-August 
ranged from 0.0021/mi\2\ to 0.0039/mi\2\ (0.0008/km\2\ to 0.0015/km\2\) 
with a maximum 95% CI of 0.0205/mi\2\ (0.0079/km\2\) (Haley et al., 
2010). The

[[Page 69994]]

average density from the summer season of those three years (0.0029/
mi\2\ [0.0011/km\2\]) was used as the average open-water density 
estimate while the high value (0.0039/mi\2\ [0.0015/km\2\]) was used as 
the maximum estimate (see Table 6-1 in Shell's application and Table 2 
here). 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 2006-2008 ranged from 0.0005 mi\2\ to 
0.0029/mi\2\ (0.0002/km\2\ to 0.0011/km\2\) with a maximum 95% CI of 
0.0242/mi\2\ (0.0093/km\2\). The average of those years of 0.0018/mi\2\ 
(0.0007/km\2\) was again used as the average density estimate, and the 
high value of 0.0029/mi\2\ (0.0011/km\2\) was used as the maximum 
estimate (see Table 6-2 in Shell's application and Table 3 here).
    Other Cetaceans--The remaining four cetacean species that could be 
encountered in the Chukchi Sea during Shell's planned exploration 
drilling program include the humpback, killer, minke, and fin whales. 
Although there is evidence of the occasional occurrence of these 
animals in the Chukchi Sea, it is unlikely that more than a few 
individuals will be encountered during the planned drilling program. 
Clarke et al. (2011) and Haley et al. (2010) reported humpback whale 
sightings; George and Suydam (1998) reported killer whales; Brueggeman 
et al. (1990), Haley et al. (2010), and COMIDA (2011) reported minke 
whales; and Clarke et al. (2011) and Haley et al. (2010) reported fin 
whales.
(2) Pinnipeds
    Four species of pinnipeds may be encountered in the Chukchi Sea 
area of Shell's proposed drilling program: ringed, bearded, spotted, 
and ribbon seals. Each of these species, except the spotted seal, is 
associated with both the ice margin and the nearshore area. The ice 
margin is considered preferred habitat (as compared to the nearshore 
areas) 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, as far as 74.6 mi (120 km) off the 
Alaskan coast in the eastern Chukchi Sea, 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; Haley et al., 2010).
    Ringed and Bearded Seals--Ringed and bearded seals ``average'' and 
``maximum'' summer ice-margin densities (see Table 6-1 in Shell's 
application and Table 2 here) 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 haul-out 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 the ice 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 2006-2008 industry 
operations ranged from 0.0411/mi\2\ to 0.1786/mi\2\ (0.0158/km\2\ to 
0.0687/km\2\) with a maximum 95% CI of 0.3936/mi\2\ (0.1514/km\2\) 
(Haley et al., 2010). These estimates are lower than those made by 
Bengtson et al. (2005), which is not surprising given the different 
survey methods and timing.
    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, 2010), and that the population of ringed seals in the 
Alaskan Chukchi Sea is approximately 208,000 animals (Bengtson et al., 
2005). In the fall, spotted seals show increased use of coastal haul-
outs so densities were estimated to be \2/3\ of the summer densities.
    Ribbon Seals--Two ribbon seal sightings were reported during 
industry vessel operations in the Chukchi Sea in 2006-2008 (Haley et 
al. 2010). The resulting density estimate of 0.0013/mi\2\ (0.0005/
km\2\) was used as the average density and 4 times that was used as the 
maximum for both seasons and habitat zones.

Estimated Area Exposed to Sounds >=120 dB or >=160 dB re 1 [mu]Pa rms

(1) Estimated Area Exposed to Continuous Sounds >= 120 dB rms From the 
Drillship
    Sounds from the Discoverer have not previously been measured in the 
Arctic. However, measurements of sounds produced by the Discoverer were 
made in the South China Sea in 2009 (Austin and Warner, 2010). The 
results of those measurements were used to model the sound propagation 
from the Discoverer (including a nearby support vessel) at planned 
exploration drilling locations in the Chukchi and Beaufort seas (Warner 
and Hannay, 2011). Broadband source levels of sounds produced by the 
Discoverer varied by activity and direction from the ship but were 
generally between 177 and 185 dB re 1 [mu]Pa [middot] m rms (Austin and 
Warner, 2010). Propagation modeling at the Burger Prospect resulted in 
an estimated distance of 0.81 mi (1.31 km) to the point at which 
exploration drilling sounds would likely fall below 120 dB. The 
estimated 0.81 mi (1.31 km) distance was multiplied by 1.5 (= 1.22 mi 
[1.97 km]) as a further precautionary measure before calculating the 
total area that may be exposed to continuous sounds >=120 dB re 1 
[mu]Pa rms by the Discoverer at each drill site on the Burger Prospect 
(Table 6-3 in Shell's application and Table 4 here). Given this 
distance or radius, the total area of water ensonified to >=120 dB rms 
during exploration drilling at each drill site was estimated to be 4.6 
mi\2\ (12 km\2\). The 160-dB radius for the Discoverer was estimated to 
be approximately 33 ft (10 m). Again, because the source level for the 
drillship was measured to be between 177 and 185 dB, the 180 and 190-dB 
radii were not needed.
    The acoustic propagation model used to estimate the sound 
propagation from the Discoverer in the Chukchi Sea is JASCO Research's 
Marine Operations Noise Model (MONM). MONM computes received sound 
levels in rms units when source levels are specified also in those 
units. MONM treats sound propagation in range-varying acoustic 
environments through a wide-angled parabolic equation solution to the 
acoustic wave equation. The specific parabolic equation code in MONM is 
based on the Naval Research Laboratory's Range-dependent Acoustic 
Model. This code has been extensively benchmarked for accuracy and is 
widely

[[Page 69995]]

employed in the underwater acoustics community (Collins, 1993).
    Changes in the water column of the Chukchi Sea through the course 
of the exploration drilling season will likely affect the propagation 
of sounds produced by exploration drilling activities, so the modeling 
of exploration drilling sounds was run using expected oceanographic 
conditions in October which are expected to support greater sound 
propagation (Warner and Hannay, 2011). Results of sound propagation 
modeling that were used in the calculations of areas exposed to various 
levels of received sounds are summarized in Table 6-3 in Shell's 
application and Table 4 here.
    Distances shown in Table 6-3 in Shell's application and Table 4 
here were used to estimate the area ensonified to >=120 dB rms around 
the drillship. As noted above, all exploration drilling activities will 
occur at the Burger Prospect. The exploration drill sites assumed for 
the summer of 2012 at the Burger Prospect (Burger A, F, J, and V) are 
3.4 to 13 mi (5.5 km to 21 km) from each other, and wells will not be 
drilled simultaneously. Therefore, the area exposed to continuous 
sounds >=120 dB at each drill site is not expected to overlap with any 
other drill site. The total area of water potentially exposed to 
received sound levels >=120 dB rms by exploration drilling operations 
during July-August at two locations is therefore estimated to be 9.42 
mi\2\ (24.4 km\2\). Activities at two additional locations in 
September-October may expose an additional 9.42 mi\2\ (24.4 km\2\) to 
continuous sounds >=120 dB rms.
[GRAPHIC] [TIFF OMITTED] TN09NO11.003

(2) Estimated Area Exposed to Continuous Sounds >=120 dB rms from Ice 
Management/Icebreaking Activities
    Measurements of the icebreaking supply ship Robert Lemeur pushing 
and breaking ice during exploration drilling operations in the Beaufort 
Sea in 1986 resulted in an estimated broadband source level of 193 dB 
re 1 [mu]Pa [middot] m (Greene, 1987a; Richardson et al., 1995a). 
Measurements of the icebreaking sounds were made at five different 
distances and those were used to generate a propagation loss equation 
[RL = 141.4 - 1.65R - 10Log(R) where R is range in kilometers (Greene, 
1987a); converting R to meters results in the following equation: R = 
171.4 - 10log(R) - 0.00165R]. Using that equation, the estimated 
distance to the 120 dB threshold for continuous sounds from icebreaking 
is 4.74 mi (7.63 km). Since the measurements of the Robert Lemeur were 
taken in the Beaufort Sea under presumably similar conditions as would 
be encountered in the Chukchi Sea in 2012, an inflation factor of 1.25 
was selected to arrive at a precautionary 120 dB distance of 5.9 mi 
(9.5 km) for icebreaking sounds (see Table 6-3 in Shell's application 
and Table 4 here). Additionally, measurements of identical sound 
sources at the Burger and Camden Bay prospects in 2008 yielded similar 
results, suggesting that sound propagation at the two locations is 
likely to be similar (Hannay and Warner, 2009).
    If ice is present, ice management/icebreaking activities may be 
necessary in early July and towards the end of operations in late 
October, but it is not expected to be needed throughout the proposed 
exploration drilling season. Icebreaking activities would likely occur 
in a 40[deg] arc up to 3.1 mi (5 km) upwind of the Discoverer (see 
Figure 1-3 and Attachment B in Shell's application for additional 
details). This activity area plus a 5.9 mi (9.5 km) buffer around it 
results in an estimated total area of 162 mi\2\ (420 km2) 
that may be exposed to sounds >=120 dB from ice management/icebreaking 
activities in each season.
(3) Estimated Area Exposed to Impulsive Sounds >= 160 dB rms From 
Airguns
    Shell proposes to use the ITAGA eight-airgun array for the ZVSP 
surveys in 2012, which consists of four 150-in\3\ airguns and four 40-
in\3\ airguns for a total discharge volume of 760 in\3\. The >=160 dB 
re 1 [mu]Pa rms radius for this source was estimated from measurements 
of a similar seismic source used during the 2008 BP Liberty seismic 
survey (Aerts et al., 2008). The BP liberty source was also an eight-
airgun array but had a slightly larger total volume of 880 in\3\. 
Because the number of airguns is the same, and the difference in total 
volume only results in an estimated 0.4 dB decrease in the source level 
of the ZVSP source, the 100th percentile propagation model from the 
measurements of the BP Liberty source is almost directly applicable. 
However, the BP Liberty source was towed at a depth of 5.9 ft (1.8 m), 
while Shell's ZVSP source would be lowered to a target depth of 13 ft 
(4 m) (from 10-23 ft [3-7 m]). The deeper depth of the ZVSP source has 
the potential to increase the source strength by as much as 6 dB. Thus, 
the constant term in the propagation equation from the BP Liberty 
source was increased from 235.4 to 241.4 while the remainder of the 
equation (-18*LogR--0.0047*R) was left unchanged. NMFS reviewed the use 
of this equation and the similarities between the 2008 BP Liberty 
project and Shell's proposed drilling sites and determined that it is 
appropriate to base the sound isopleths on those results. This equation 
results in the following estimated distances to maximum received 
levels: 190 dB = 0.33 mi (524 m); 180 dB = 0.77 mi (1,240 m); 160 dB = 
2.28 mi (3,670 m); 120 dB = 6.52 mi (10,500 m). The >=160 dB distance 
was multiplied by 1.5 (see Table 6-3 in Shell's application and Table 4 
here) for use in estimating the area ensonified to >=160 dB rms around 
the drilling vessel during ZVSP activities. Therefore, the total area 
of water potentially exposed to received sound levels >=160 dB rms by 
ZVSP operations at two exploration well sites during each season is 
estimated to be 73.7 mi\2\ (190.8 km\2\).
    Shell intends to conduct sound propagation measurements on the

[[Page 69996]]

Discoverer and the airgun source in 2012 once they are on location in 
the Chukchi Sea. The results of those measurements would then be used 
during the season to implement mitigation measures.

Potential Number of Takes by Harassment

    Although a marine mammal may be exposed to drilling or icebreaking 
sounds >= 120 dB (rms) or airgun sounds >= 160 dB (rms), this does not 
mean that it will actually exhibit a disruption of behavioral patterns 
in response to the sound source. Rather, the estimates provided here 
are simply the best estimates of the number of animals that potentially 
could have a behavioral modification due to the noise. However, not all 
animals react to sounds at this low level, and many will not show 
strong reactions (and in some cases any reaction) until sounds are much 
stronger. There are several variables that determine whether or not an 
individual animal will exhibit a response to the sound, such as the age 
of the animal, previous exposure to this type of anthropogenic sound, 
habituation, etc.
    Numbers of marine mammals that might be present and potentially 
disturbed (i.e., Level B harassment) are estimated below based on 
available data about mammal distribution and densities at different 
locations and times of the year as described previously. Exposure 
estimates are based on a single drillship (Discoverer) drilling up to 
four wells in the Chukchi Sea from July 4-October 31, 2012. Shell 
assumes an average of 32 days at each drill site (including the partial 
well drill site, including 7.5 days of MLC excavation at all four drill 
sites). Shell also assumes that ZVSP activities may occur at each well 
drilled. Additionally, Shell assumed that more ice is likely to be 
present in the area of operations during the July-August period, so 
summer ice-margin densities have been applied to 50 percent of the area 
that may be exposed to sounds from exploration 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 percent of the area that may be 
exposed to sounds from exploration drilling and ZVSP activities in 
those months. Fall open-water densities were applied to the remaining 
80 percent of the area. Since ice management/icebreaking activities 
would only occur within ice-margin habitat, the entire area potentially 
ensonified by ice management/icebreaking activities has been multiplied 
by the ice-margin densities in both seasons.
    The number of different individuals of each species potentially 
exposed to received levels of continuous drilling-related sounds >= 120 
dB re 1 [mu]Pa or to pulsed airgun sounds >= 120 dB re 1 [mu]Pa within 
each season and habitat zone was estimated by multiplying:
     The anticipated area to be ensonified to the specified 
level in the time period and habitat zone to which a density applies, 
by
     The expected species density.
    The numbers of exposures were then summed for each species across 
the seasons and habitat zones.
(1) Drillship Activities
    Estimates of the average and maximum number of individual marine 
mammals that may be exposed to continuous sound levels >=120 dB by 
exploration drilling activities are shown by season and habitat in 
Table 6-4 in Shell's application and Table 5 here. Due to the 
relatively small estimated >=120 dB radius around the exploration 
drilling activities, only a few individuals of any species are 
estimated to be exposed based on average densities. However, chance 
encounters with individuals of any species are possible as all of the 
species are known to occur in the Chukchi Sea (except for the narwhal 
for reasons stated previously in this document). Minimal estimates have 
therefore been included in the Total (Max) column to account for chance 
encounters or where greater numbers may be encountered than 
calculations suggested.
(2) Ice Management/Icebreaking Activities
    Estimates of the average and maximum number of individual marine 
mammals that may be exposed to continuous sound levels >=120 dB by ice 
management/icebreaking activities are shown by season and habitat in 
Table 6-5 in Shell's application and Table 6 here. Should ice 
management/icebreaking be necessary, it would ensonify a larger area of 
water to >=120 dB than the exploration drilling activities or to >=160 
dB by ZVSP surveys, and, therefore, results in the highest number of 
potential estimated individual exposed to such sounds.
    The average and maximum estimates of the number of individual 
bowhead whales exposed to received sound levels >=120 dB are 19 and 38, 
respectively. The average estimates for beluga and gray whales are 4 
and 14, respectively. Few other cetaceans are likely to be exposed to 
icebreaking sounds >=120 dB, but maximum estimates have been included 
to account for chance encounters.
    Ringed seals are expected to be the most abundant animal in the 
Chukchi Sea, and the average and maximum estimates of the number 
exposed to >=120 dB by potential ice management/icebreaking activities 
are 343 and 568, respectively. Estimated exposures of other seal 
species are substantially less than those for ringed seals (see Table 
6-5 in Shell's application and Table 6 here).
(3) ZVSP Activities
    Estimates of the average and maximum number of individual marine 
mammals that may be exposed to pulsed airgun sounds at received levels 
>=160 dB during ZVSP activities are shown by season and habitat in 
Table 6-6 in Shell's application and Table 7 here. The estimates are 
somewhat greater than for exploration drilling activities because of 
the larger >=160 dB radius around the airguns compared to the estimated 
>=120 dB radius around exploration drilling activities (see Table 6-3 
in Shell's application and Table 4 here).
    The average and maximum estimates of the number of individual 
bowhead whales potentially exposed to received sound levels >=160 dB 
are 5 and 11, respectively. The average estimates for beluga and gray 
whales are 1 and 6, respectively (see Table 6-6 in Shell's application 
and Table 7 here). Few other cetaceans are likely to be exposed to 
airgun sounds >=160 dB, but maximum estimates have been included to 
account for chance encounters.
    The average and maximum estimated number of ringed seals 
potentially exposed to >=160 dB by ZVSP activities are 132 and 218, 
respectively. Estimated exposures of other seal species are 
substantially below those for ringed seals (Table 6-6 in Shell's 
application and Table 7 here).

Estimated Take Conclusions

    As stated previously, NMFS' practice has been to apply the 120 dB 
re 1 [mu]Pa (rms) received level threshold for underwater continuous 
sound levels and the 160 dB re 1 [mu]Pa (rms) received level threshold 
for underwater impulsive sound levels to determine whether take by 
Level B harassment occurs. However, not all animals react to sounds at 
these low levels, and many will not show strong reactions (and in some 
cases any reaction) until sounds are much stronger. Southall et al. 
(2007) provide a severity scale for ranking observed behavioral 
responses of both free-ranging marine mammals and laboratory subjects 
to various types of

[[Page 69997]]

anthropogenic sound (see Table 4 in Southall et al. (2007)). Tables 15, 
17, and 21 in Southall et al. (2007) outline the numbers of low-
frequency and mid-frequency cetaceans and pinnipeds in water, 
respectively, reported as having behavioral responses to non-pulsed 
sounds in 10-dB received level increments. These tables illustrate, 
especially for low- and mid-frequency cetaceans, that more intense 
observed behavioral responses did not occur until sounds were higher 
than 120 dB (rms). Many of the animals had no observable response at 
all when exposed to anthropogenic continuous sound at levels of 120 dB 
(rms) or even higher.
BILLING CODE 3510-22-P

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[[Page 69999]]


[GRAPHIC] [TIFF OMITTED] TN09NO11.005

BILLING CODE 3510-22-C

    Although the 120-dB isopleth for the drillship may seem slightly 
expansive (i.e., 1.22 mi [1.97 km], which includes the 50% inflation 
factor), the zone of ensonification begins to shrink dramatically with 
each 10-dB increase in received sound level to where the 160-dB 
isopleth is only about 33 ft (10 m) from the drillship. As stated 
previously, source levels are expected to be between 177 and 185 dB 
(rms). For an animal to be exposed to received levels between 177 and 
185 dB, it would have to be within several meters of the vessel, which 
is unlikely, especially given the fact that certain species are likely 
to avoid the area (as described earlier in this document).
    For impulsive sounds, such as those produced by the airguns, 
studies reveal that baleen whales show avoidance responses, which would 
reduce the likelihood of them being exposed to higher received sound 
levels. The 180-dB zone (0.77 mi [1.24 km]) is one-third the size of 
the 160-dB zone (2.28 mi [3.67 km], which is the modeled distance 
before the 1.5 inflation factor is included). In the limited studies 
that have been conducted on pinniped responses to pulsed sound sources, 
they seem to be more tolerant and do not exhibit strong behavioral 
reactions (see Southall et al., 2007).
    NMFS is proposing to authorize the maximum take estimates provided 
in Table 6-7 of Shell's application. Table 8 in this document outlines 
the abundance, proposed take, and percentage of each stock or 
population for the 12 species that may be exposed to sounds >= 120 dB 
from the drillship and ice management/ice breaking activities and to 
sounds >= 160 dB from ZVSP activities in Shell's proposed Chukchi Sea 
drilling area. With the exception of killer and minke whales (which are 
still less than 2.5%), less than 1% of each species or stock would 
potentially be exposed to sounds above the Level B harassment 
thresholds. The take estimates presented here do not take any of the 
mitigation measures presented earlier in this document into 
consideration. These take numbers also do not consider how many of the 
exposed animals may actually respond or react to the proposed 
exploration drilling program. Instead, the take estimates are based on 
the presence of animals, regardless of whether or not they react or 
respond to the activities.

[[Page 70000]]

[GRAPHIC] [TIFF OMITTED] TN09NO11.006

Negligible Impact Analysis

    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.'' In making a negligible impact determination, 
NMFS considers a variety of factors, including but not limited to: (1) 
The number of anticipated mortalities; (2) the number and nature of 
anticipated injuries; (3) the number, nature, intensity, and duration 
of Level B harassment; and (4) the context in which the takes occur.
    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 drillship or icebreaker above 120 dB or to impulsive sounds from 
the airguns above 160 dB, as those sound levels only propagate 1.22 mi 
(1.97 km), 5.9 mi (9.5 km), and 3.42 mi (5.51 km), respectively, which 
includes the inflation factor. Additionally, the 120-dB radius for the 
airgun array has been modeled to propagate 6.5 mi (10.5 km) from the 
source (and would still be less than 10 mi [16.1 km] if an inflation 
factor of 1.5 were applied). 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., 
drillship, 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

[[Page 70001]]

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 likely to occur in the proposed 
drilling area, three are listed as endangered under the ESA: The 
bowhead, humpback, and fin whales. All three 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 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. On December 10, 2010, NMFS published a notice of 
proposed threatened status for subspecies of the ringed seal (75 FR 
77476) and a notice of proposed threatened and not warranted status for 
subspecies and distinct population segments of the bearded seal (75 FR 
77496) in the Federal Register. Neither of these two ice seal species 
is currently considered depleted under the MMPA. The ribbon seal is a 
``species of concern.'' None of the other species that may occur in the 
project area are 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.
    The estimated takes proposed to be authorized represent less than 
1% of the affected population or stock for 10 of the species and less 
than 2.5% for two of the species. 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, these take numbers were calculated using a 
50% inflation factor of the 120-dB radius from the drillship and of the 
160-dB radius for the airguns and using a 25% inflation factor of the 
120-dB radius from the icebreaker during active ice management/
icebreaking activities, which is a conservative approach recommended by 
some acousticians when modeling a new sound source in a new location. 
This is fairly conservative given the fact that the radii were based on 
results from measurements of the Discoverer in another location and of 
the icebreaker and airguns in the Arctic Ocean. SSV tests may reveal 
that the Level B harassment zone is either smaller or larger than that 
used to estimate take. If the SSV tests reveal that the Level B 
harassment zone is slightly larger than those modeled or measured 
elsewhere, the inflation factors should cover the discrepancy, however, 
based on recent SSV tests of seismic airguns (which showed that the 
measured 160-dB isopleths was in the area of the modeled value), the 
50% correction factor likely results in an overestimate of takes. 
Moreover, the mitigation and monitoring measures (described previously 
in this document) proposed for inclusion in the IHA (if issued) are 
expected to reduce even further any potential disturbance to marine 
mammals. Last, some marine mammal individuals, including mysticetes, 
have been shown to avoid the ensonified area around airguns at certain 
distances (Richardson et al., 1999), and, therefore, some individuals 
would not likely enter into the Level B harassment zones for the 
various types of activities.

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, walruses, and polar bears. (As mentioned previously in this 
document, both the walrus and the polar bear are under the USFWS' 
jurisdiction.) 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). Wainwright is the coastal village 
closest to the proposed drill site and is located approximately 78 mi 
(125.5 km) from Shell's Burger prospect. Point Lay, Barrow, and Point 
Hope are all approximately 92, 140, and 180 mi (148, 225.3, and 290 
km), respectively, from Shell's Burger prospect.
(1) Bowhead Whales
    Bowhead whale hunting is a key activity in the subsistence 
economies of northwest Arctic communities. The whale harvests have a 
great influence on social relations by strengthening the sense of 
Inupiat culture and heritage in addition to reinforcing family and 
community ties.
    An overall quota system for the hunting of bowhead whales was 
established by the International Whaling Commission (IWC) in 1977. The 
quota is now regulated through an agreement between NMFS and the Alaska 
Eskimo Whaling Commission (AEWC). The AEWC allots the number of bowhead 
whales that each whaling community may harvest annually (USDOI/BLM,

[[Page 70002]]

2005). The annual take of bowhead whales has varied due to (a) changes 
in the allowable quota level and (b) year-to-year variability in ice 
and weather conditions, which strongly influence the success of the 
hunt.
    Bowhead whales migrate around northern Alaska twice each year, 
during the spring and autumn, and are hunted in both seasons. Bowhead 
whales are hunted from Barrow during the spring and the fall migration. 
The spring hunt along Chukchi villages and at Barrow occurs after leads 
open due to the deterioration of pack ice; the spring hunt typically 
occurs from early April until the first week of June. From 1984-2009, 
bowhead harvests by the villages of Wainwright, Point Hope, and Point 
Lay occurred only between April 14 and June 24 and only between April 
23 and June 15 in Barrow (George and Tarpley, 1986; George et al., 
1987, 1988, 1990, 1992, 1995, 1998, 1999, 2000; Philo et al., 1994; 
Suydam et al., 1995b, 1996, 1997, 2001b, 2002, 2003, 2004, 2005b, 2006, 
2007, 2008, 2009, 2010). Shell will not mobilize and move into the 
Chukchi Sea prior to July 1.
    The fall migration of bowhead whales that summer in the eastern 
Beaufort Sea typically begins in late August or September. Fall 
migration into Alaskan waters is primarily during September and 
October. In the fall, subsistence hunters use aluminum or fiberglass 
boats with outboards. Hunters prefer to take bowheads close to shore to 
avoid a long tow during which the meat can spoil, but Braund and 
Moorehead (1995) report that crews may (rarely) pursue whales as far as 
50 mi (80 km). The autumn bowhead hunt usually begins in Barrow in mid-
September and mainly occurs in the waters east and northeast of Point 
Barrow. Fall bowhead whaling has not typically occurred in the villages 
of Wainwright, Point Hope, and Point Lay in recent years. However, a 
Wainwright whaling crew harvested the first fall bowhead whale in 90 
years or more on October 8, 2010. Because of changing ice conditions, 
there is the potential for these villages to resume a fall bowhead 
harvest.
    Barrow participates in a fall hunt each year. From 1984-2009, 
Barrow whalers harvested bowhead whales between August 31 and October 
29. While this time period overlaps with that of Shell's proposed 
operations, the drill sites are located more than 140 mi (225 km) west 
of Barrow, so the whales would reach the Barrow hunting grounds before 
entering the sound field of Shell's operations. Shell will be flying 
helicopters out to the drillship for resupply missions. In the past 35 
years, however, Barrow whaling crews have harvested almost all whales 
in the Beaufort Sea to the east of Point Barrow (Suydam et al., 2008), 
indicating that relatively little fall hunting occurs to the west where 
the flight corridor is located.
(2) Beluga Whales
    Beluga whales are available to subsistence hunters along the coast 
of Alaska in the spring when pack-ice conditions deteriorate and leads 
open up. Belugas may remain in coastal areas or lagoons through June 
and sometimes into July and August. The community of Point Lay is 
heavily dependent on the hunting of belugas in Kasegaluk Lagoon for 
subsistence meat. From 1983-1992 the average annual harvest was 
approximately 40 whales (Fuller and George, 1997). 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.
    In Wainwright and Barrow, hunters usually wait until after the 
spring bowhead whale hunt is finished before turning their attention to 
hunting belugas. The average annual harvest of beluga whales taken by 
Barrow for 1962-1982 was five (MMS, 1996). The Alaska Beluga Whale 
Committee (ABWC) recorded that 23 beluga whales had been harvested by 
Barrow hunters from 1987 to 2002, ranging from 0 in 1987, 1988 and 1995 
to the high of 8 in 1997 (Fuller and George, 1997; ABWC, 2002 cited in 
USDOI/BLM, 2005). Barrow residents typically hunt for belugas between 
Point Barrow and Skull Cliffs in the Chukchi Sea (primarily April-June) 
and later in the summer (July-August) on both sides of the barrier 
island in Elson Lagoon/Beaufort Sea (MMS, 2008). Harvest rates indicate 
that 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.
    Shell's proposed exploration drilling activities take place well 
offshore, far away from areas that are used for beluga hunting by the 
Chukchi Sea communities.
(3) Ringed Seals
    Ringed seals are hunted mainly from October through June. Hunting 
for these smaller mammals is concentrated during winter (November 
through March) because bowhead whales, bearded seals, and caribou are 
available through other seasons. In winter, leads and cracks in the ice 
off points of land and along the barrier islands are used for hunting 
ringed seals. The average annual ringed seal harvest was 49 seals in 
Point Lay, 86 in Wainwright, and 394 in Barrow (Braund et al., 1993; 
USDOI/BLM, 2003, 2005). Although ringed seals are available year-round, 
the planned activities will not occur during the primary period when 
these seals are typically harvested (November-March). Also, the 
activities will be largely in offshore waters where they will not 
influence ringed seals in the nearshore areas where they are hunted.
(4) Spotted Seals
    The spotted seal subsistence hunt peaks in July and August along 
the shore where the seals haul out, but usually involves relatively few 
animals. Available maps of recent and past subsistence use areas for 
spotted seals indicate harvest of this species within 30-40 mi (48-64 
km) of the coastline. Spotted seals typically migrate south by October 
to overwinter in the Bering Sea. During the fall migration, spotted 
seals are hunted by the Wainwright and Point Lay communities as the 
seals move south along the coast (USDOI/BLM, 2003). Spotted seals are 
also occasionally hunted in the area off Point Barrow and along the 
barrier islands of Elson Lagoon to the east (USDOI/BLM, 2005). The 
planned activities will remain offshore of the coastal harvest area of 
these seals and should not conflict with harvest activities.
(5) Bearded Seals
    Bearded seals, although generally not favored for their meat, are 
important to subsistence activities in Barrow and Wainwright because of 
their skins. Six to nine bearded seal hides are used by whalers to 
cover each of the skin-covered boats traditionally used for spring 
whaling. Because of their valuable hides and large size, bearded seals 
are specifically sought. Bearded seals are harvested during the spring 
and summer months in the Chukchi Sea (USDOI/BLM, 2003, 2005). The 
animals inhabit the environment around the ice floes in the drifting 
nearshore ice pack, so hunting usually occurs from boats in the drift 
ice. Most bearded seals are harvested in coastal areas inshore of the 
proposed exploration drilling area, so no conflicts with the harvest of 
bearded seals are expected.

Potential Impacts to Subsistence Uses

    NMFS has defined ``unmitigable adverse impact'' in 50 CFR 216.103 
as an impact resulting from the specified activity that is likely to 
reduce the

[[Page 70003]]

availability of the species to a level insufficient for a harvest to 
meet subsistence needs by causing the marine mammals to abandon or 
avoid hunting areas; directly displacing subsistence users; or placing 
physical barriers between the marine mammals and the subsistence 
hunters; and 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.

Plan of Cooperation (POC)

    Regulations at 50 CFR 216.104(a)(12) require IHA applicants for 
activities that take place in Arctic waters to provide a 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 developed a Draft POC for 
its 2012 Chukchi Sea, Alaska, exploration drilling program to minimize 
any adverse impacts on the availability of marine mammals for 
subsistence uses. A copy of the Draft POC was provided to NMFS with the 
IHA Application as Attachment D (see ADDRESSES for availability). 
Meetings with potentially affected subsistence users began in 2009 and 
continued into 2010 and 2011 (see Table 4.2-1 in Shell's POC for a list 
of all meetings conducted through April 2011). During these meetings, 
Shell focused on lessons learned from prior years' activities and 
presented mitigation measures for avoiding potential conflicts, which 
are outlined in the 2012 POC and this document. Shell's POC addresses 
vessel transit, drilling, and associated activities. Communities that 
were consulted regarding Shell's 2012 Arctic Ocean operations include: 
Barrow, Kaktovik, Wainwright, Kotzebue, Kivalina, Point Lay, Point 
Hope, Kiana, Gambell, Savoonga, and Shishmaref.
    Beginning in early January 2009 and continuing into 2011, Shell 
held one-on-one meetings with representatives from the North Slope 
Borough (NSB) and Northwest Arctic Borough (NWAB), subsistence-user 
group leadership, and Village Whaling Captain Association 
representatives. Shell's primary purpose in holding individual meetings 
was to inform and prepare key leaders, prior to the public meetings, so 
that they would be prepared to give appropriate feedback on planned 
activities.
    Shell presented the proposed project to the NWAB Assembly on 
January 27, 2009, to the NSB Assembly on February 2, 2009, and to the 
NSB and NWAB Planning Commissions in a joint meeting on March 25, 2009. 
Meetings were also scheduled with representatives from the AEWC, and 
presentations on proposed activities were given to the Inupiat 
Community of the Arctic Slope, and the Native Village of Barrow. On 
December 8, 2009, Shell held consultation meetings with representatives 
from the various marine mammal commissions. Prior to drilling in 2012, 
Shell will also hold additional consultation meetings with the affected 
communities and subsistence user groups, NSB, and NWAB to discuss the 
mitigation measures included in the POC. Shell also attended the 2011 
Conflict Avoidance Agreement (CAA) negotiation meetings in support of a 
limited program of marine environmental baseline activities in 2011 
taking place in the Beaufort and Chukchi seas. Shell has stated that it 
is committed to a CAA process and will demonstrate this by making a 
good-faith effort to negotiate a CAA every year it has planned 
activities.
    The following mitigation measures, plans and programs, are integral 
to the POC and were developed during consultation with potentially 
affected subsistence groups and communities. These measures, plans, and 
programs will be implemented by Shell during its 2012 exploration 
drilling operations in both the Beaufort and Chukchi Seas to monitor 
and mitigate potential impacts to subsistence users and resources. The 
mitigation measures Shell has adopted and will implement during its 
2012 Chukchi Sea offshore exploration drilling operations are listed 
and discussed below. This most recent version of Shell's planned 
mitigation measures was presented to community leaders and subsistence 
user groups starting in January of 2009 and has evolved since in 
response to information learned during the consultation process.
    To minimize any cultural or resource impacts to subsistence 
activities from its exploration operations, Shell will implement the 
following additional measures to ensure coordination of its activities 
with local subsistence users to minimize further the risk of impacting 
marine mammals and interfering with the subsistence hunts for marine 
mammals:
    (1) The drillship and support vessels will not enter the Chukchi 
Sea before July 1;
    (2) To minimize impacts on marine mammals and subsistence hunting 
activities, vessels that can safely travel outside of the polynya zone 
will do so. In the event the transit outside of the polynya zone 
results in Shell having to break ice (as opposed to managing ice by 
pushing it out of the way), the drillship and support vessels will 
enter into the polynya zone far enough so that ice breaking is not 
necessary. If it is necessary to move into the polynya zone, Shell will 
notify the local communities of the change in the transit route through 
the Communication Centers (Com Centers);
    (3) Shell has developed a Communication Plan and will implement the 
plan before initiating exploration drilling operations to coordinate 
activities with local subsistence users as well as Village Whaling 
Associations in order to minimize the risk of interfering with 
subsistence hunting activities and keep current as to the timing and 
status of the bowhead whale migration, as well as the timing and status 
of other subsistence hunts. The Communication Plan includes procedures 
for coordination with Com and Call Centers to be located in coastal 
villages along the Chukchi and Beaufort Seas during Shell's proposed 
activities in 2012;
    (4) Shell will employ local Subsistence Advisors from the Beaufort 
and Chukchi Sea villages to provide consultation and guidance regarding 
the whale migration and subsistence hunt. There will be a total of nine 
subsistence advisor-liaison positions (one per village), to work 
approximately 8 hours per day and 40-hour weeks through Shell's 2012 
exploration project. The subsistence advisor will use local knowledge 
(Traditional Knowledge) to gather data on subsistence lifestyle within 
the community and advise on

[[Page 70004]]

ways to minimize and mitigate potential impacts to subsistence 
resources during the drilling season. Responsibilities include 
reporting any subsistence concerns or conflicts; coordinating with 
subsistence users; reporting subsistence-related comments, concerns, 
and information; and advising how to avoid subsistence conflicts. A 
subsistence advisor handbook will be developed prior to the operational 
season to specify position work tasks in more detail;
    (5) Shell will recycle drilling muds (e.g., use those muds on 
multiple wells), to the extent practicable based on operational 
considerations (e.g., whether mud properties have deteriorated to the 
point where they cannot be used further), to reduce discharges from its 
operations. At the end of the season excess water base fluid will be 
pre-diluted to a 30:1 ratio with seawater and then discharged;
    (6) Shell will implement flight restrictions prohibiting aircraft 
from flying within 1,000 ft (305 m) of marine mammals or below 1,500 ft 
(457 m) altitude (except during takeoffs and landings or in emergency 
situations) while over land or sea;
    (7) Vessels within 900 ft (274 m) of marine mammals will reduce 
speed, avoid separating members from a group, and avoid multiple 
changes in direction;
    (8) Vessels underway will alter course to avoid impacts to marine 
mammals, including collisions;
    (9) The drilling support fleet will avoid known fragile ecosystems, 
including the Ledyard Bay Critical Habitat Unit and will include 
coordination through the Com Centers; and
    (10) Vessel speeds will be reduced during inclement weather 
conditions in order to reduce the potential for collisions with marine 
mammals.
    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. Vessel and aircraft traffic associated with 
Shell's proposed 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 traffic corridors 
do not traverse areas indicated in recent mapping as utilized by 
Barrow, Point Lay, or Point Hope for beluga hunts. The corridor avoids 
important beluga hunting areas in Kasegaluk Lagoon.
    The POC also contains measures regarding ice management procedures, 
critical operations procedures, the blowout prevention program, and oil 
spill response. Some of the oil spill response measures to reduce 
impacts to subsistence hunts include: having the primary OSRV on 
standby at all times so that it is available within 1 hour if needed; 
the remainder of the OSR fleet will be available within 72 hours if 
needed and will be capable of collecting oil on the water up to the 
calculated Worst Case Discharge; oil spill containment equipment will 
be available in the unlikely event of a blowout; capping stack 
equipment will be stored aboard one of the ice management vessels and 
will be available for immediate deployment in the unlikely event of a 
blowout; and pre-booming will be required for all fuel transfers 
between vessels.

Unmitigable Adverse Impact Analysis

    Shell has adopted a spatial and temporal strategy for its Chukchi 
Sea operations that should minimize impacts to subsistence hunters. 
Shell will enter the Chukchi Sea far offshore, so as to not interfere 
with July hunts in the Chukchi Sea villages and will communicate with 
the Com Centers to notify local communities of any changes in the 
transit route. After the close of the July beluga whale hunts in the 
Chukchi Sea villages, very little whaling occurs in Wainwright, Point 
Hope, and Point Lay. Although the fall bowhead whale hunt in Barrow 
will occur while Shell is still operating (mid- to late September to 
October), Barrow is located 140 mi (225 km) east of the proposed drill 
sites. Based on these factors, Shell's Chukchi Sea survey is not 
expected to interfere with the fall bowhead harvest in Barrow. In 
recent years, bowhead whales have occasionally been taken in the fall 
by coastal villages along the Chukchi coast, but the total number of 
these animals has been small. Wainwright landed its first fall whale in 
more than 90 years in October 2010. Hunters from the northwest Arctic 
villages prefer to harvest whales within 50 mi (80 km) so as to avoid 
long tows back to shore.
    Adverse impacts are not anticipated on sealing activities since the 
majority of hunts for seals occur in the winter and spring, when Shell 
will not be operating. Additionally, most sealing activities occur much 
closer to shore than Shell's proposed drill sites.
    Shell will also support the village Com Centers in the Arctic 
communities and employ local Subsistence Advisors from the Beaufort and 
Chukchi Sea villages to provide consultation and guidance regarding the 
whale migration and subsistence hunt. The Subsistence Advisors will 
provide advice to Shell on ways to minimize and mitigate potential 
impacts to subsistence resources during the drilling season. Support 
activities, such as helicopter flights, could impact nearshore 
subsistence hunts. However, Shell will use flight paths and agreed upon 
flight altitudes to avoid adverse impacts to hunts and will communicate 
regularly with the Com Centers.
    In the unlikely event of a major oil spill in the Chukchi Sea, 
there could be major impacts on the availability of marine mammals for 
subsistence uses. As discussed earlier in this document, the 
probability of a major oil spill occurring over the life of the project 
is low (Bercha, 2008). Additionally, Shell developed an ODPCP, which is 
currently under review by the Department of the Interior and several 
Federal agencies and the public. Shell has also incorporated several 
mitigation measures into its operational design to reduce further the 
risk of an oil spill. Copies of Shell's 2012 Chukchi Sea Exploration 
Plan and ODPCP can be found on the Internet at: http://alaska.boemre.gov/ref/ProjectHistory/2012_Shell_CK/revisedEP/EP.pdf 
and http://www.alaska.boemre.gov/fo/ODPCPs/2010_Chukchi_rev1.pdf, 
respectively.

Proposed Incidental Harassment Authorization

    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 4, 2012, through October 
31, 2012.
    (2) This Authorization is valid only for activities associated with 
Shell's 2012 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

[[Page 70005]]

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) 8-Airgun array with a total discharge volume of 760 in\3\;
    (b) Continuous drillship sounds during active drilling operations; 
and
    (c) Vessel sounds generated during active ice management or 
icebreaking.
    (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 his 
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 at least 9 knots when within 
300 yards (274 m) of whales. The reduction in speed will vary based on 
the situation but must be sufficient to avoid interfering with the 
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 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-qualified, 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 drillship 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 (7 x 50 
Fujinon), big-eye binoculars (25 x 150), and night vision devices. PSO 
shifts shall last no longer than 4 hours at a time 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 MMO, 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 MMO 
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 Inupiat 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 before the 
anticipated start of the 2012 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) If there are Alaska Native PSOs, the 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 should 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 8-airgun array (760 
in\3\) is in operation; and a 180 dB re 1 [mu]Pa (rms) and a 190 dB re 
1 [mu]Pa (rms) EZ before a single airgun (40 in\3\) is in operation, 
respectively. For purposes of the field verification tests, described 
in condition 10(c)(i) below, the 180 dB radius is predicted to be 0.77 
mi (1.24 km) and the 190 dB radius is predicted to be 0.33 mi (524 m);
    (d) Implement a ``ramp-up'' procedure when starting up at the 
beginning of seismic operations, which means start the smallest gun 
first and add airguns in a sequence such that the source level of the 
array shall increase in steps not exceeding approximately 6 dB per 5-
min period. During ramp-up, the PSOs

[[Page 70006]]

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 40 in\3\ 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:
    (a) Traverse north through the Bering Strait through the Chukchi 
Sea along a route that lies offshore of the polynya zone. In the event 
the transit outside of the polynya zone results in Shell having to 
break ice, the drilling vessel and support vessels will enter into the 
polynya zone far enough so that icebreaking is not necessary. If it is 
necessary to move into the polynya zone, Shell shall notify the local 
communities of the change in transit route through the Communication 
and Call Centers (Com Centers). As soon as the fleet transits past the 
ice, it will exit the polynya zone and continue a path in the open sea 
toward the Camden Bay drill sites;
    (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 2012 bowhead whale hunt;
    (e) Employ local Subsistence Advisors (SAs) from the Beaufort and 
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;
    (g) Cool all drilling mud to mitigate any potential permafrost 
thawing or thermal dissociation of any methane hydrates encountered 
during exploration drilling if such materials are present at the drill 
site; and
    (h) Recycle all drilling mud to the extent practicable based on 
operational considerations (e.g., whether mud properties have 
deteriorated to the point where they cannot be used further) so that 
the volume of the mud disposed of at the end of the drilling season is 
reduced.
    (10) Monitoring Measures:
    (a) Vessel-based Monitoring: The Holder of this Authorization shall 
designate biologically-trained PSOs to be aboard the drillship and all 
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 
vessel, support vessels, and the airgun array. 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 shall be 
reported to NMFS within 5 days of completing the test.
    (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 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 drillship, support vessels, and the airguns, the Holder shall 
submit a preliminary report of the results to NMFS. 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) analyses of the effects of various factors influencing 
detectability of marine mammals (e.g., sea state, number of observers, 
and fog/glare);
    (iii) 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;
    (iv) 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

[[Page 70007]]

expressed by the presentation of confidence limits, a minimum-maximum, 
posterior probability distribution, etc.; the exact approach would 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, after the independent monitoring plan peer review 
changes are made to the monitoring program, 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 2012.
    (e) The draft comprehensive report will be subject to review and 
comment by NMFS, the AEWC, and the NSB 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 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.

Endangered Species Act (ESA)

    There are three 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. 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 currently preparing an Environmental Assessment (EA), 
pursuant to NEPA, to determine whether the issuance of an IHA to Shell 
for its 2012 drilling activities may have a significant impact on the 
human environment. NMFS expects to release a draft of the EA for public 
comment and will inform the public through the Federal Register and 
posting on our Web site once a draft is available (see ADDRESSES).

[[Page 70008]]

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 2012 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: November 2, 2011.
James H. Lecky,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2011-28914 Filed 11-8-11; 8:45 am]
BILLING CODE 3510-22-P