[Federal Register Volume 75, Number 74 (Monday, April 19, 2010)]
[Notices]
[Pages 20482-20509]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-8790]



[[Page 20481]]

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Part III





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 Near 
Camden Bay, Beaufort Sea, Alaska; Notice

  Federal Register / Vol. 75 , No. 74 / Monday, April 19, 2010 / 
Notices  

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XU80


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to an Exploration Drilling Program 
Near Camden Bay, Beaufort Sea, AK

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 Beaufort 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, six species of marine mammals during the specified 
activity.

DATES: Comments and information must be received no later than May 19, 
2010.

ADDRESSES: Comments on the application should be addressed to Michael 
Payne, Chief, Permits, Conservation and Education 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 
e-mail comments sent to addresses other than the one provided here. 
Comments sent via e-mail, 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 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. The following 
associated documents are also available at the same internet address: 
Shell's 2010 Exploration Drilling Communication Plan Beaufort Sea, 
Alaska, and Shell's 2010 Plan of Cooperation (POC) Camden Bay, Alaska. 
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) 713-2289, ext 156.

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 May 11, 2009, from Shell for the 
taking, by harassment, of marine mammals incidental to offshore 
exploration drilling on OCS leases in the Beaufort 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 
December 10, 2009. However, after some additional discussions regarding 
certain activities, NMFS determined that a second revision to the 
application was warranted. The latest revised application was submitted 
to NMFS on March 18, 2010. NMFS carefully evaluated Shell's 
application, including their analyses, and determined that the 
application is complete and that it is appropriate to make the 
necessary preliminary determinations pursuant to the MMPA. The March 
18, 2010, application is the one available for public comment (see 
ADDRESSES) and considered by NMFS for this proposed IHA.
    Shell intends to drill two exploration wells at the Torpedo and 
Sivulliq prospects in Camden Bay, Beaufort Sea, Alaska, during the 2010 
Arctic open-water season (July through October). Impacts to marine 
mammals may occur from noise produced by the drillship and supporting 
vessels and aircraft. Shell has requested an authorization to take 11 
marine mammal species by Level B harassment. However, some of these 
species are not expected to be found in the activity area. Therefore, 
NMFS is proposing to authorize take of six marine mammal species, by 
Level B harassment, incidental to Shell's offshore exploration drilling 
in Camden Bay. These species include: beluga whale (Delphinapterus 
leucas); bowhead whale (Balaena mysticetus); gray whale (Eschrichtius 
robustus); bearded seal (Erignathus barbatus); ringed seal (Phoca 
hispida); and spotted seal (P. largha).

[[Page 20483]]

Description of the Specified Activity

    Shell plans to conduct an offshore exploration drilling program on 
U.S. Department of the Interior, Minerals Management Service (MMS) 
Alaska OCS leases located north of Point Thomson near Camden Bay in the 
Beaufort Sea, Alaska, during the 2010 open-water season. During the 
2010 drilling program, Shell plans to complete two exploration wells at 
two drill sites, one well each on the Torpedo (NR06-04 Flaxman Island 
lease block 6610, OCS-Y-1941 [Flaxman Island 6610]) and Sivulliq 
prospects (NR06-04 Flaxman Island lease block 6658, OCS-Y 1805 [Flaxman 
Island 6658]). 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.
    Shell plans to drill the Torpedo prospect well first, followed by 
the Sivulliq well, unless adverse surface conditions or other factors 
dictate a reversal of drilling sequence. In that case, Shell will 
mobilize to the Sivulliq prospect and drill there first. The Torpedo H 
drill site is located 22 mi (35.4 km) from shore in water 120 ft (36.6 
m) deep. The Sivulliq N drill site is located 16 mi (25.7 km) from 
shore with a water depth of 107 ft (32.6 m).
    The ice reinforced drillship Discoverer will be used to drill the 
wells. The Discoverer is 514 ft (156.7 m) long with a maximum height 
(above keel) of 274 ft (83.7 m). Additional rig specifications for the 
Discoverer can be found in Attachment A of Shell's application (see 
ADDRESSES). While on location at the drill sites, the Discoverer will 
be affixed to the seafloor using eight 7-ton Stevpris anchors arranged 
in a radial array.
    During the 2010 drilling season, the Discoverer will be attended by 
a minimum of seven vessels that will be used for ice-management, anchor 
handling, oil spill response (OSR), refueling, resupply, and servicing 
of the drilling operations. The ice-management vessels will consist of 
an icebreaker and an anchor handler. Table 1-1 in Shell's application 
provides a list of the support vessels that will be used during the 
drilling program, as well as information about trip frequency and 
duration for each vessel.
    Re-supply between the drill sites and West Dock will use a 
coastwide qualified vessel. An ice-capable OSR barge (OSRB), with an 
associated tug, will be located nearby during the planned drilling 
program. The OSRB will be supported by a berthing vessel for the OSR 
crew. An OSR tanker also will be nearby for its storage capability of 
recovered liquids.
    Shell's base plan is for two ice-management/anchor handling 
vessels, the M/V Vladimir Ignatjuk and the ice-management/anchor 
handling vessel M/V Nordica or similar vessels, to accompany the 
Discoverer traveling north of Dutch Harbor through the Bering Strait, 
after July 1, 2010, then through the Chukchi Sea, around Pt. Barrow, 
and east through the Alaskan Beaufort Sea, before arriving on location 
at the Torpedo ``H'' location on or about July 10, or Sivulliq ``N'' if 
adverse surface conditions or other factors dictate a reversal of 
drilling sequence. At the completion of the drilling season on or 
before October 31, 2010, one or two ice-management vessels, along with 
various support vessels, such as the OSR fleet, will accompany the 
Discoverer as it travels west through the Beaufort Sea, then south 
through the Chukchi Sea and the Bering Strait. Subject to ice 
conditions, alternate exit routes may be considered. Shell has planned 
a suspension of all operations beginning on August 25 for the Nuiqsut 
(Cross Island) and Kaktovik subsistence bowhead whale hunts. The 
Discoverer and support vessels will leave the Camden Bay project area, 
will move to a location at or north of 71.25[deg]N. latitude and at or 
west of 146.4[deg]W. longitude and will return to resume activities 
after the Nuiqsut (Cross Island) and Kaktovik subsistence bowhead whale 
hunts conclude.
    Shell will cease drilling on or before October 31, after which the 
Discoverer will exit the Alaskan Beaufort Sea. In total, Shell 
anticipates that the exploration drilling program will require 
approximately 74 drilling days, excluding weather delays, the shutdown 
period to accommodate the fall bowhead whale harvests at Kaktovik and 
Cross Island (Nuiqsut), or other operational delays. Shell assumes 
approximately 11 additional days will be needed for drillship 
mobilization, drillship moves between locations, and drillship 
demobilization.
    Activities associated with the 2010 Beaufort Sea exploration 
drilling program include operation of the Discoverer, associated 
support vessels, crew change support and re-supply. The Discoverer will 
remain at the location of the designated exploration drill sites except 
when mobilizing and demobilizing to and from Camden Bay, 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 Ice-
management Plan (IMP). Ice-management vessels, anchor tenders, and OSR 
vessels will remain in close proximity to the drillship during drilling 
operations.
    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 IMP 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 Shell's 
Ice and Weather Advisory Center. 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.
    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. 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

[[Page 20484]]

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 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 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 ridges that would be managed at a much slower speed than 
that used to manage first-year ice. Shell has indicated that they do 
not have any intention of breaking ice with the ice-management vessels 
but, rather, intend to push it out of the area as described here. 
Should ice become so prevalent in the drilling area that it is 
difficult to continue operations without the breaking of ice, Shell has 
indicated that they would stop operations and move off site instead of 
breaking ice (S. Childs, Shell, 2010, pers. comm.). Shell has indicated 
that ice breaking would only be conducted if the ice poses an immediate 
safety hazard at the drill sites.
    Crew change/re-supply vessels will transit to and from the 
drillship at the estimated frequency shown in Table 1-1 in Shell's 
application. Helicopters are planned to provide support for crew 
change, provision re-supply, and search-and-rescue operations during 
the drilling season. The aircraft operations will principally be based 
in Deadhorse, Alaska.
    Potential impacts to marine mammals could occur from the noise 
produced by the drillship and its support vessels and aircraft. 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. Sound measurements 
from the Discoverer have not previously been conducted in the Arctic or 
elsewhere; however, sounds from a similar drillship, the Northern 
Explorer II, were measured at two different times and locations in the 
Beaufort Sea (Miles et al., 1987; Greene, 1987a). The underwater 
received sound pressure level (SPL) in the 20-1,000 Hz band for 
drilling activity by the Northern Explorer II, including a nearby 
support vessel, was 134 dB re 1 [mu]Pa (rms) at 0.1 mi (0.2 km; Greene, 
1987b). The back-propagated source levels (175 dB re 1 [mu]Pa at 1 m) 
from these measurements were used as a proxy for modeling the sounds 
likely to be produced by drilling activities from the Discoverer. NMFS 
has determined that the sound measurements for the Northern Explorer II 
constitute a good proxy for estimating sound radii for the Discoverer. 
Sound propagation measurements will be performed on the Discoverer in 
2010 once on location near the Camden Bay drill sites in the Beaufort 
Sea. The results of those measurements will be used during the drilling 
season to implement proposed mitigation measures described later in 
this document (see the ``Proposed Mitigation'' section).
    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 
2010 drilling season and will not be making trips between the shorebase 
and the offshore vessels. Aircraft travel would be controlled by 
Federal Aviation Administration approved flight paths. Shell has agreed 
to a flight altitude of 1,500 ft (457 m; except during takeoffs and 
landings or during emergencies) for all non-marine mammal monitoring 
flights to minimize impacts on marine mammals. 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. Additionally, ice-management activities are 
not anticipated to impact marine mammals in a manner that would rise to 
the level of taking. This is based on the fact that the propeller 
rotation (i.e., cavitation) will be similar to that of vessels under 
normal operations and will not be used at 100 percent power as is the 
case in other situations rising to the level of taking (e.g., thruster 
use for dynamic positioning at terminals).

Description of Marine Mammals in the Area of the Specified Activity

    The Beaufort Sea supports a diverse assemblage of marine mammals, 
including: bowhead, gray, beluga, killer (Orcinus orca), minke 
(Balaenoptera acutorostrata), and humpback (Megaptera novaeangliae) 
whales; harbor porpoises (Phocoena phocoena); ringed, ribbon 
(Histriophoca fasciata), spotted, and bearded seals; polar bears (Ursus 
maritimus); and walruses (Odobenus rosmarus divergens; see Table 4-1 in 
Shell's application). The bowhead and humpback 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. Additionally, the 
ribbon seal is considered a ``species of concern'' under the ESA, and 
the bearded and ringed seals are ``candidate species'' under the ESA, 
meaning they are currently being considered for listing. 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, six are expected to occur in the area of Shell's 
proposed operations. These species include: The bowhead, gray, and 
beluga whales and the ringed, spotted, and bearded seals. 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. Bowhead whales are also anticipated to occur in the 
proposed project area more frequently than the other cetacean species; 
however, their occurrence is not expected until later in the season. 
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).

[[Page 20485]]

    Other cetacean species that have been observed in the Beaufort Sea 
but are uncommon or rarely identified in the project area include 
harbor porpoise, narwhal, and killer, minke, humpback, and gray whales. 
These species could occur in the project area, but each of these 
species is uncommon or rare in the area and relatively few encounters 
with these species are expected during the exploration drilling 
program. The narwhal occurs in Canadian waters and occasionally in the 
Beaufort Sea, but it is rare there 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). Point Barrow, Alaska, is 
the approximate northeastern extent of the harbor porpoise's regular 
range (Suydam and George, 1992), though there are extralimital records 
east to the mouth of the Mackenzie River in the Northwest Territories, 
Canada, and recent sightings in the Beaufort Sea in the vicinity of 
Prudhoe Bay during surveys in 2007 and 2008 (Christie et al., 2009). 
Monnett and Treacy (2005) did not report any harbor porpoise sightings 
during aerial surveys in the Beaufort Sea from 2002 through 2004. 
Humpback and minke whales have recently been sighted in the Chukchi Sea 
but very rarely in the Beaufort Sea. Greene et al. (2007) reported and 
photographed a humpback whale cow/calf pair east of Barrow near Smith 
Bay in 2007, which is the first known occurrence of humpbacks in the 
Beaufort Sea. Savarese et al. (2009) reported one minke whale sighting 
in the Beaufort Sea in 2007 and 2008. Ribbon seals do not normally 
occur in the Beaufort Sea; however, two ribbon seal sightings were 
reported during vessel-based activities near Prudhoe Bay in 2008 
(Savarese et al., 2009). Due to the rarity of these species in the 
proposed project area and the remote chance they would be affected by 
Shell's proposed Beaufort Sea drilling activities, these species are 
not discussed further in this proposed IHA notice.
    Shell's application contains information on the status, 
distribution, seasonal distribution, and abundance 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 2009 SAR is available at: http://www.nmfs.noaa.gov/pr/pdfs/sars/ak2009.pdf.

Potential Effects of the Specified Activity on Marine Mammals

    Potential effects of Shell's proposed drilling program in Camden 
Bay on marine mammals would most likely be acoustic in nature. 
Petroleum development and associated activities introduce sound into 
the marine environment. Potential acoustic effects on marine mammals 
relate to sound produced by drilling activity, vessels, and aircraft. 
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.

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 derived using auditory evoked 
potential techniques, 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;
     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;

[[Page 20486]]

     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, six marine mammal species 
(three pinniped and three cetacean species) are likely to occur in the 
proposed drilling area. Of the three cetacean species likely to occur 
in Shell's project area, two are classified as low frequency cetaceans 
(i.e., bowhead and gray whales), and one is classified as a mid-
frequency cetacean (i.e., beluga whale) (Southall et al., 2007).

Drilling Sounds

    Exploratory drilling will be conducted from 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 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 20-1,000 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. Shell used the measurements from the Northern Explorer II to 
model the various sound radii (which are discussed later in this 
document) for the Discoverer. Once on location at the drill sites in 
Camden Bay, Shell plans to take measurements of the Discoverer to 
quantify the absolute sound levels produced by drilling and to monitor 
their variations with time, distance, and direction from the drillship. 
Based on the similarities of the two drillships, NMFS has preliminarily 
determined that the radii produced by the Discoverer would be similar 
to those recorded for the Northern Explorer II.

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, and oil-spill response 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 al. (2008) 
estimated higher underwater 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 ice-breaking activities than ships of similar size during 
normal operation in open water (Richardson et al., 1995a). This higher 
sound production results from the greater amount of power and propeller 
cavitation required when operating in thick ice.
    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 Camden Bay, 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 spill response vessels.

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 1,000 ft (305 m), thereby limiting the received levels at and 
below the surface.

Tolerance

    Numerous studies have shown that underwater sounds from industry 
activities are often readily detectable by marine mammals in the water 
at

[[Page 20487]]

distances of many kilometers. Numerous studies have also shown that 
marine mammals at distances more than a few kilometers away often show 
no apparent response to industry activities of various types (Miller et 
al., 2005; Bain and Williams, 2006). This is often true even in cases 
when the sounds must be readily audible to the animals based on 
measured received levels and the hearing sensitivity of that mammal 
group. Although various baleen whales, toothed whales, and (less 
frequently) pinnipeds have been shown to react behaviorally to 
underwater sound such as airgun pulses or vessels under some 
conditions, at other times mammals of all three types have shown no 
overt reactions (e.g., Malme et al., 1986; Richardson et al., 1995; 
Madsen and Mohl, 2000; Croll et al., 2001; Jacobs and Terhune, 2002; 
Madsen et al., 2002; Miller et al., 2005). In general, pinnipeds and 
small odontocetes seem to be more tolerant of exposure to some types of 
underwater sound than are baleen whales. Richardson et al. (1995a) 
found that vessel noise does not seem to strongly affect pinnipeds that 
are already in the water. Richardson et al. (1995a) went on to explain 
that seals on haul-outs sometimes respond strongly to the presence of 
vessels and at other times appear to show considerable tolerance of 
vessels, and (Brueggeman et al., 1992; cited in Richardson et al., 
1995a) observed ringed seals hauled out on ice pans displaying short-
term escape reactions when a ship approached within 0.25-0.5 mi (0.4-
0.8 km).

Masking

    The term ``masking'' refers to the obscuring of sounds of interest 
by interfering sounds, generally at similar frequencies. Masking 
effects of underwater sounds on marine mammal calls and other natural 
sounds are expected to be limited. For example, beluga whales primarily 
use high-frequency sounds to communicate and locate prey; therefore, 
masking by low-frequency sounds associated with drilling activities is 
not expected to occur (Gales, 1982, as cited in Shell, 2009). If the 
distance between communicating whales does not exceed their distance 
from the drilling activity, the likelihood of potential impacts from 
masking would be low (Gales, 1982, as cited in Shell, 2009). At 
distances greater than 660-1,300 ft (200-400 m), recorded sounds from 
drilling activities did not affect behavior of beluga whales, even 
though the sound energy level and frequency were such that it could be 
heard several kilometers away (Richardson et al., 1995b). This exposure 
resulted in whales being deflected from the sound energy and changing 
behavior. These minor changes are not expected to affect the beluga 
whale population (Richardson et al., 1991; Richard et al., 1998). 
Brewer et al. (1993) observed belugas within 2.3 mi (3.7 km) of the 
drilling unit Kulluk during drilling; however, the authors do not 
describe any behaviors that may have been exhibited by those animals. 
Please refer to the Arctic Multiple-Sale Draft Environmental Impact 
Statement (USDOI MMS, 2008), available on the Internet at: http://www.mms.gov/alaska/ref/EIS%20EA/ArcticMultiSale_209/_DEIS.htm, for 
more detailed information.
    There is evidence of other marine mammal species continuing to call 
in the presence of industrial activity. For example, bowhead whale 
calls are frequently detected in the presence of seismic pulses, 
although the number of calls detected may sometimes be reduced 
(Richardson et al., 1986; Greene et al., 1999; Blackwell et al., 2009). 
Additionally, 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 nearly 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 
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. If, as 
described later in this document, certain species avoid the proposed 
drilling locations, impacts from masking will be low.

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

[[Page 20488]]

(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 differential sensitivities of marine mammal 
species to sound and the wide range of potential acoustic sources to 
which a marine mammal may be exposed.
    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).
    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 other sightings were at much greater 
distances. Few bowheads were recorded near industrial activities by 
aerial observers, but observations by surface observers suggested that 
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). Restriction 
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 [mu]Pa (rms). Probability of avoidance and 
other behavioral effects increased when received levels were from 120-
160 dB re 1 [mu]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 percent, 50 
percent, and 90 percent 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 percent 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

[[Page 20489]]

for humpback whales exposed to a low-frequency sonar stimulus (160- to 
330-Hz frequency band; 42-s tonal signal repeated every 6 min; source 
levels 170 to 200 dB) during playback experiments. Exposure to measured 
received levels ranging from 120 to 150 dB resulted in variability in 
humpback singing behavior. Croll et al. (2001) investigated responses 
of foraging fin and blue whales to the same low frequency active sonar 
stimulus off southern California. Playbacks and control intervals with 
no transmission were used to investigate behavior and distribution on 
time scales of several weeks and spatial scales of tens of kilometers. 
The general conclusion was that whales remained feeding within a region 
for which 12 to 30 percent of exposures exceeded 140 dB.
    Frankel and Clark (1998) conducted playback experiments with 
wintering humpback whales using a single speaker producing a low-
frequency ``M-sequence'' (sine wave with multiple-phase reversals) 
signal in the 60 to 90 Hz band with output of 172 dB at 1 m. For 11 
playbacks, exposures were between 120 and 130 dB re 1 [micro]Pa (rms) 
and included sufficient information regarding individual responses. 
During eight of the trials, there were no measurable differences in 
tracks or bearings relative to control conditions, whereas on three 
occasions, whales either moved slightly away from (n = 1) or towards (n 
= 2) the playback speaker during exposure. The presence of the source 
vessel itself had a greater effect than did the M-sequence playback.
    Finally, Nowacek et al. (2004) used controlled exposures to 
demonstrate behavioral reactions of northern right whales to various 
non-pulse sounds. Playback stimuli included ship noise, social sounds 
of conspecifics, and a complex, 18-min ``alert'' sound consisting of 
repetitions of three different artificial signals. Ten whales were 
tagged with calibrated instruments that measured received sound 
characteristics and concurrent animal movements in three dimensions. 
Five out of six exposed whales reacted strongly to alert signals at 
measured received levels between 130 and 150 dB (i.e., ceased foraging 
and swam rapidly to the surface). Two of these individuals were not 
exposed to ship noise, and the other four were exposed to both stimuli. 
These whales reacted mildly to conspecific signals. Seven whales, 
including the four exposed to the alert stimulus, had no measurable 
response to either ship sounds or actual vessel noise.
    Toothed Whales--Most toothed whales have the greatest hearing 
sensitivity at frequencies much higher than that of baleen whales and 
may be less responsive to low-frequency sound commonly associated with 
oil and gas industry exploratory drilling activities. Richardson et al. 
(1995b) reported that beluga whales did not show any apparent reaction 
to playback of underwater drilling sounds at distances greater than 
656-1,312 ft (200-400 m). Reactions included slowing down, milling, or 
reversal of course after which the whales continued past the projector, 
sometimes within 164-328 ft (50- 100 m). The authors concluded (based 
on a small sample size) that the playback of drilling sounds had no 
biologically significant effects on migration routes of beluga whales 
migrating through pack ice and along the seaward side of the nearshore 
lead east of Pt. 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. However, while the Vladimir Ignatjuk (an icebreaker) is 
anticipated to be one of the vessels attending the Discoverer, it will 
only be conducting ice-management activities (which were described in 
the ``Description of the Specified Activity'' section earlier in this 
document) and not physical breaking of ice. Thus, NMFS does not 
anticipate that marine mammals would exhibit the types of behavioral 
reactions as those noted in the aforementioned studies.
    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 to 120 dB, 
while others failed to exhibit such responses for exposure to received 
levels from 120 to 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 ice-breaking 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).

[[Page 20490]]

    Observations during 1983 (LGL and Greeneridge, 1986) involved two 
ice-breaking 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 
ice-breaking ships. During operations, no belugas and few narwhals were 
observed in an area approximately 16.8 mi (27 km) ahead of the vessels, 
and all whales sighted over 12.4-50 mi (20-80 km) from the ships were 
swimming strongly away. Additional observations confirmed the spatial 
extent of avoidance reactions to this sound source in this context.
    Buckstaff (2004) reported elevated dolphin whistle rates with 
received levels from oncoming vessels in the 110 to 120 dB range in 
Sarasota Bay, Florida. These hearing thresholds were apparently lower 
than those reported by a researcher listening with towed hydrophones. 
Morisaka et al. (2005) compared whistles from three populations of 
Indo-Pacific bottlenose dolphins. One population was exposed to vessel 
noise with spectrum levels of approximately 85 dB/Hz in the 1- to 22-
kHz band (broadband received levels approximately 128 dB) as opposed to 
approximately 65 dB/Hz in the same band (broadband received levels 
approximately 108 dB) for the other two sites. Dolphin whistles in the 
noisier environment had lower fundamental frequencies and less 
frequency modulation, suggesting a shift in sound parameters as a 
result of increased ambient noise.
    Morton and Symonds (2002) used census data on killer whales in 
British Columbia to evaluate avoidance of non-pulse acoustic harassment 
devices (AHDs). Avoidance ranges were about 2.5 mi (4 km). Also, there 
was a dramatic reduction in the number of days ``resident'' killer 
whales were sighted during AHD-active periods compared to pre- and 
post-exposure periods and a nearby control site.
    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 
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

[[Page 20491]]

up from 165 dB over 20 min) on their return to a haul-out site. 
Received exposure levels of the ATOC source for experimental subjects 
averaged 128 dB (range 118 to 137) in the 60- to 90-Hz band. None of 
the instrumented animals terminated dives or radically altered behavior 
upon exposure, but some statistically significant changes in diving 
parameters were documented in nine individuals. Translocated northern 
elephant seals exposed to this particular non-pulse source began to 
demonstrate subtle behavioral changes at exposure to received levels of 
approximately 120 to 140 dB.
    Kastelein et al. (2006) exposed nine captive harbor seals in an 
approximately 82 x 98 ft (25 x 30 m) enclosure to non-pulse sounds used 
in underwater data communication systems (similar to acoustic modems). 
Test signals were frequency modulated tones, sweeps, and bands of noise 
with fundamental frequencies between 8 and 16 kHz; 128 to 130 [ 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.

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. The following 
subsections discuss in somewhat more detail the possibilities of TTS, 
permanent threshold shift (PTS), and non-auditory 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. 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.
    For toothed whales exposed to single, short pulses, the TTS 
threshold appears to be, to a first approximation, a function of the 
energy content of the pulse (Finneran et al., 2002, 2005). Given the 
available data, the received level of a single seismic pulse (with no 
frequency weighting) might need to be approximately 186 dB re 1 
[mu]Pa\2.\s (i.e., 186 dB sound exposure level [SEL]) in order to 
produce brief, mild TTS. Exposure to several strong seismic pulses that 
each have received levels near 175-180 dB SEL might result in slight 
TTS in a small odontocete, assuming the TTS threshold is (to a first 
approximation) a function of the total received pulse energy. Given 
that the SPL is approximately 10-15 dB higher than the SEL value for 
the same pulse, an odontocete would need to be exposed to a sound level 
of 190 dB re 1 [mu]Pa (rms) in order to incur TTS.
    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 lower than those to which 
odontocetes are most sensitive, and natural background noise levels at 
those low frequencies tend to be higher. Marine mammals can hear sounds 
at varying frequency levels. However, sounds that are produced in the 
frequency range at which an animal hears the best do not need to be as 
loud as sounds in less functional frequencies to be detected by the 
animal. 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. Since current NMFS practice assumes the same thresholds for the 
onset of hearing impairment in both odontocetes and mysticetes, the 
threshold is likely conservative for mysticetes.
    In free-ranging 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). Kastak et al. (1999) reported TTS of approximately 4-5 dB in 
three species of pinnipeds (harbor seal, Californian sea lion, and 
northern elephant seal) after underwater exposure for approximately 20 
minutes to noise with frequencies ranging from 100 Hz to 2,000 Hz at 
received levels 60-75 dB above hearing threshold. This approach allowed 
similar effective exposure conditions to each of the subjects, but 
resulted in variable absolute exposure values depending on subject and 
test frequency. Recovery to near baseline levels was reported within 24 
hours of noise exposure (Kastak et al., 1999). Kastak et al. (2005) 
followed up on their previous work using higher sensitive levels and 
longer exposure times (up to 50-min) and corroborated their previous 
findings. The sound exposures necessary to cause slight threshold 
shifts were also determined for two California sea lions and a juvenile 
elephant seal exposed to underwater sound for similar duration. 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 (1995, 2000) concluded that cetaceans and pinnipeds should not 
be exposed to pulsed underwater noise at

[[Page 20492]]

received levels exceeding, respectively, 180 and 190 dB re 1 [mu]Pa 
(rms). The established 180- and 190-dB re 1 [mu]Pa (rms) criteria are 
not considered to be the levels above which TTS might occur. Rather, 
they are the received levels above which, in the view of a panel of 
bioacoustics specialists convened by NMFS before TTS measurements for 
marine mammals started to become available, one could not be certain 
that there would be no injurious effects, auditory or otherwise, to 
marine mammals. Based on the summary provided here and the fact that 
modeling indicates the back-propagated source level for the drillship 
to be 175 dB re 1 [mu]Pa at 1 m, 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.
    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.
    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. 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. PTS might occur at a 
received sound level at least several decibels above that inducing mild 
TTS.
    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 a similar drillship (i.e., the 
Northern Explorer II) suggests that marine mammals located immediately 
adjacent to a drillship such as the Discoverer 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.
    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. 
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.
    Until recently, it was assumed that diving marine mammals are not 
subject to the bends or air embolism. This possibility was first 
explored at a workshop (Gentry [ed.], 2002) held to discuss whether the 
stranding of beaked whales in the Bahamas in 2000 (Balcomb and 
Claridge, 2001; NOAA and USN, 2001) might have been related to bubble 
formation in tissues caused by exposure to noise from naval sonar. 
However, the opinions were inconclusive. Jepson et al. (2003) first 
suggested a possible link between mid-frequency sonar activity and 
acute and chronic tissue damage that results from the formation in vivo 
of gas bubbles, based on the beaked whale stranding in the Canary 
Islands in 2002 during naval exercises. Fernandez et al. (2005a) showed 
those beaked whales did indeed have gas bubble-associated lesions as 
well as fat embolisms. Fernandez et al. (2005b) also found evidence of 
fat embolism in three beaked whales that stranded 62 mi (100 km) north 
of the Canaries in 2004 during naval exercises. Examinations of several 
other stranded species have also revealed evidence of gas and fat 
embolisms (Arbelo et al., 2005; Jepson et al., 2005a; Mendez et al., 
2005). Most of the afflicted species were deep divers. There is 
speculation that gas and fat embolisms may occur if cetaceans ascend 
unusually quickly when exposed to aversive sounds or if sound in the 
environment causes the destabilization of existing bubble nuclei 
(Potter, 2004; Arbelo et al., 2005; Fernandez et al., 2005a; Jepson et 
al., 2005b). Even if gas and fat embolisms can occur during exposure to 
mid-frequency sonar, there is no evidence that that type of effect 
occurs in response to the types of sound produced during the proposed 
exploratory activities. Also, most evidence for such effects has been 
in beaked whales, which do not occur in the proposed survey area.
    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). 
Underwater sound from drilling and support activities is less energetic 
and has slower rise times, and there is no proof that they can cause 
serious injury, death, or stranding. However, the association of mass 
strandings of beaked whales with naval exercises and, in one case, a 
Lamont-Doherty Earth Observatory seismic survey, 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. The potential for stranding to result from exposure 
to strong pulsed sound suggests that caution be used when exposing 
marine mammals to pulsed or other underwater sound. Most of the 
stranding events associated with exposure of marine mammals to pulsed 
sound however, have involved beaked whales which do not occur in the 
proposed area. Additionally, the sound produced from the proposed 
activities will be at much lower levels than those reported during 
stranding events, as the source levels of the drillship are much lower 
than those other sources. Pulsed sounds, such as those produced by 
seismic airgun arrays, are transient and have rapid rise times, whereas 
the non-impulsive, continuous sounds produced by the drillship to be 
used by Shell do not have rapid rise time. 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.
    The potential effects to marine mammals described in this section 
of the document do not take into consideration the proposed monitoring

[[Page 20493]]

and mitigation measures described later in this document (see the 
``Proposed Mitigation'' and ``Proposed Monitoring and Reporting'' 
sections).

Anticipated Effects on Habitat

    The primary potential impacts to marine mammals and other marine 
species are associated with elevated sound levels produced by the 
exploratory drilling program. However, other potential impacts to the 
surrounding habitat from physical disturbance are also possible.

Potential Impacts From Seafloor Disturbance

    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.
    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. The drilling units will be 
stabilized and held in place with a system of eight 7,000 kg anchors 
during operations, which are designed to embed into the seafloor. Each 
anchor may impact an area of 775 ft\2\ (72 m\2\) of the seafloor. 
Minimum impact estimates from each well or mooring by the Discoverer is 
9,300 ft\2\ (864 m\2\) of seafloor. This estimate assumes that the 
anchors are set only once and not moved by outside forces such as sea 
current. However, based on the vast size of the Beaufort 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. Scars typically do not form or persist in sandy mud or 
sand sediments (such as those found in the Beaufort Sea) but may last 
for 9 years in hard clays (Centaur Associates Inc., 1984). The energy 
regime plus possible effects of ice gouge in the Beaufort Sea suggest 
that anchor scars would be refilled faster than in the North Sea.
    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). However, most of the abundant 
Beaufort Sea fish species with demersal eggs spawn under the ice in the 
winter well before MLC excavation would occur. Exposure of pelagic eggs 
would be much shorter as they move with ocean currents (Wilber and 
Clarke, 2001).
    Suspended sediments, resulting from vessel mooring and MLC 
excavation, are 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 Beaufort Sea region.

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.
    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 
measurements from the Northern Explorer II, the 160 dB radius for the 
Discoverer was modeled by JASCO to be approximately 115 ft [35 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 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 while drilling have been measured 
during past exploration in the Beaufort and Chukchi seas. Sounds 
generated by drilling and ice-management are generally low

[[Page 20494]]

frequency and within the frequency range detectable by most fish.
    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. 
Additionally, impacts to fish as a prey species for odontocetes and 
seals are expected to be minor.
    Some mysticetes, including bowhead whales, feed on concentrations 
of zooplankton. Some feeding bowhead whales may occur in the Alaskan 
Beaufort Sea in July and August, and others feed intermittently during 
their westward migration in September and October (Richardson and 
Thomson [eds.], 2002; Lowry et al., 2004). 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. Impacts on 
zooplankton behavior are predicted to be inconsequential. Thus, feeding 
mysticetes would not be adversely affected by this minimal loss or 
scattering, if any, of reduced zooplankton abundance.
    Aerial surveys in recent years have sighted bowhead whales feeding 
in Camden Bay on their westward migration through the Beaufort Sea. 
Individuals feeding in the Camden Bay area at the beginning of the 
migration (i.e., approximately late August or early September) are not 
expected to be impacted by Shell's proposed drilling program, primarily 
because of Shell's proposal to suspend operations and depart the area 
on August 25 and not return until the close of the Kaktovik and Nuiqsut 
(Cross Island) hunts, which typically ends around mid- to late 
September (see the ``Plan of Cooperation (POC)'' subsection later in 
this document for more details). If other individual bowheads stop to 
feed in the Camden Bay area after Shell resumes drilling operations in 
mid- to late September, they may potentially be exposed to sounds from 
the drillship. However, injury to the bowhead whales is not 
anticipated, as the source level of the drillship is not loud enough to 
cause even mild TTS, as discussed earlier in this document. As 
mentioned earlier in this document, some bowhead whales have 
demonstrated avoidance behavior in areas of industrial sound (e.g., 
Richardson et al., 1999) and some have continued to feed even in the 
presence of industrial activities (Richardson, 2004). However, Camden 
Bay is one of a few feeding locations for bowhead whales in the 
Beaufort Sea. Also, as discussed previously, drilling operations are 
not expected to adversely affect bowhead whale prey species or preclude 
bowhead whales from obtaining sufficient food resources along their 
traditional migratory path.

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. The westward fall bowhead whale 
migration begins in late August/early September and lasts through 
October. As discussed throughout this document, Shell plans to suspend 
all operations on August 25, move the drillship and all support vessels 
out of the area to a location north and west of the well sites, and 
will not resume drilling activities until the close of the Kaktovik and 
Nuiqsut bowhead subsistence hunts. This will reduce the amount of time 
that the Discoverer may impede the bowheads' normal swim and migratory 
paths as they move through Camden Bay. 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 Beaufort Sea's migratory corridor is much larger in size than the 
length of the drillship (many dozens of miles vs. less than two 
football fields), and animals would have other means of passage around 
the drillship. In sum, the physical presence of the drillship is not 
likely to cause a significant deflection to migrating marine mammals.

Potential Impacts From Ice Management

    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. Ringed, bearded, and 
spotted seals (along with the ribbon seal and 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 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 on 
October 31, Shell's activities would not impact ringed seal lairs or 
habitat needed for breeding and pupping in the Camden Bay area. Ringed 
seals can be found on the pack ice surface in the late spring and early 
summer in the Beaufort 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, as the Beaufort Sea 
provides less suitable habitat for the species. Spotted seals are even 
less common in the Camden Bay area. This species does not breed in the 
Beaufort Sea. Therefore, ice used by bearded and spotted 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.

[[Page 20495]]

For ringed seals, ice-management 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.
    In conclusion, NMFS has preliminarily determined that Shell's 
proposed exploration drilling program in Camden Bay, Beaufort Sea, 
Alaska, is not expected to have any habitat-related effects that could 
cause significant or long-term consequences for individual marine 
mammals or on the food sources that they utilize.

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).

Mitigation Measures Proposed in Shell's IHA Application

    Shell submitted a Marine Mammal Monitoring and Mitigation Plan 
(4MP) as part of its application (Attachment B; 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 fall bowhead whale hunts from 
Kaktovik, Nuiqsut (Cross Island), and Barrow;
     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 safety 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 and shutting down 
activities for a portion of the open-water season.
    Safety 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 [mu]Pa (rms) for pinnipeds. 
These safety 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 safety zones will 
not necessarily be injured, seriously injured, or killed, 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, serious injury, or mortality 
could 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.
    Initial safety and behavioral radii for the sound levels produced 
by the drilling activities have been modeled. These radii will be used 
for mitigation purposes, should they be necessary, until direct 
measurements are available early during the exploration activities. 
However, it is not anticipated that source levels from the Discoverer 
will reach the 180- or 190-dB (rms) levels.
    Sounds from the Discoverer have not previously been measured in the 
Arctic or elsewhere, but sounds from a similar drillship, Explorer II, 
were measured in the Beaufort Sea (Greene, 1987; Miles et al., 1987). 
The underwater received SPL in the 20 to 1,000 Hz band for drilling 
activity by the Explorer II, including a nearby support vessel, was 134 
dB re 1 [mu]Pa (rms) at 0.1 mi (0.2 km; Greene 1987). The back-
propagated source levels (175 dB re 1 [mu]Pa at 1 m) from these 
measurements were used as a proxy for modeling the sounds likely to be 
produced by drilling activities from the Discoverer. Based on the 
models, source levels from drilling are not expected to reach the 180 
dB rms level and are expected to fall below 160 dB rms at 115 ft (35 m) 
from the drillship. The 120 dB rms radius is expected to be 3 mi (4.9 
km) from the drillship. These estimated source measurements were used 
to model the expected sounds produced at the exploratory well sites by 
the Discoverer.
    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 preliminarily 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. However, Shell plans to use marine mammal observers 
(MMOs) onboard the drillship and the various support vessels to monitor 
marine mammals and their responses to industry activities and to 
initiate mitigation measures should in-field measurements of the 
operations indicate that such measures are necessary. Additional 
details on the MMO program are described in the ``Proposed Monitoring 
and Reporting'' section found later in this document.
    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 drillship. Once on 
location in Camden Bay, 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 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.
    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

[[Page 20496]]

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 in Shell's IHA 
application, NMFS proposes the following measures be included in the 
IHA, if issued, in order to ensure the least practicable impact on the 
affected species or stocks:
    (1) All vessels should reduce speed 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;
    (2) Avoid multiple changes in direction and speed when within 300 
yards (274 m) of whales; and
    (3) 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.

Mitigation Conclusions

    NMFS has carefully evaluated the applicant's proposed mitigation 
measures and considered a range of other measures in the context of 
ensuring that NMFS prescribes the means of effecting the least 
practicable impact on the affected marine mammal species and stocks and 
their habitat. Our evaluation of potential measures included 
consideration of the following factors in relation to one another:
     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.
    Based on our evaluation of the applicant's proposed measures, as 
well as other measures considered by NMFS, NMFS has preliminarily 
determined that the proposed mitigation measures provide the means of 
effecting the least practicable impact on marine mammal species or 
stocks and their habitat, paying particular attention to rookeries, 
mating grounds, and areas of similar significance.

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 in Shell's IHA Application

    The monitoring plan proposed by Shell can be found in the 4MP 
(Attachment B 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.
(1) Vessel-Based MMOs
    Vessel-based monitoring for marine mammals will be done by trained 
MMOs throughout the period of drilling operations. MMOs 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. MMO duties will include 
watching for and identifying marine mammals, recording their numbers, 
distances, and reactions to the drilling operations. A sufficient 
number of MMOs will be required onboard each vessel to meeting the 
following criteria: (1) 100 percent monitoring coverage during all 
periods of drilling operations in daylight; (2) maximum of 4 
consecutive hours on watch per MMO; and (3) maximum of 12 hours of 
watch time per day per MMO. Shell anticipates that there will be 
provision for crew rotation at least every 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 MMO 
handbook, adapted for the specifics of the planned Shell drilling 
program, will be prepared and distributed beforehand to all MMOs.
    MMOs will watch for marine mammals from the best available vantage 
point on the drillship and support vessels. MMOs will scan 
systematically with the unaided eye and 7 x 50 reticle binoculars, 
supplemented with 20 x 60 image-stabilized Zeiss Binoculars or Fujinon 
25 x 150 ``Big-eye'' binoculars and night-vision equipment when needed. 
Personnel on the bridge will assist the MMOs in watching for marine 
mammals.
    Information to be recorded by marine mammal observers 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). When a mammal sighting is made, the 
following information about the sighting will be recorded:
    (A) 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;
    (B) Time, location, speed, activity of the vessel, sea state, ice 
cover, visibility, and sun glare; and
    (C) The positions of other vessel(s) in the vicinity of the MMO 
location.
    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.

[[Page 20497]]

    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. MMOs 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 percent when given 
immediate feedback about actual distances during training.
(2) Aerial Survey Program
    Shell proposes to conduct an aerial survey program in support of 
the drilling program in the Beaufort Sea during the summer and fall of 
2010. Shell's objectives for this program include:
    (A) To advise operating vessels as to the presence of marine 
mammals (primarily cetaceans) in the general area of operation;
    (B) To collect and report data on the distribution, numbers, 
movement and behavior of marine mammals near the drilling operations 
with special emphasis on migrating bowhead whales;
    (C) To support regulatory reporting related to the estimation of 
impacts of drilling operations on marine mammals;
    (D) To investigate potential deflection of bowhead whales during 
migration by documenting how far east of drilling operations a 
deflection may occur and where whales return to normal migration 
patterns west of the operations; and
    (E) To monitor the accessibility of bowhead whales to Inupiat 
hunters.
    Aerial survey flights will begin 5 to 7 days before operations at 
the exploration well sites get underway. Surveys will be flown daily 
throughout drilling operations, weather and flight conditions 
permitting, and continued for 5 to 7 days after all activities at the 
site have ended.
    The aerial survey procedures will be generally consistent with 
those used during earlier industry studies (Davis et al., 1985; Johnson 
et al., 1986; Evans et al., 1987; Miller et al., 1997, 1998, 1999, 
2002; Patterson, 2007). This will facilitate comparison and pooling of 
data where appropriate. However, the specific survey grids will be 
tailored to Shell's operations. During the 2010 drilling season Shell 
will coordinate and cooperate with the aerial surveys conducted by MMS/
NMFS and any other groups conducting surveys in the same region.
    For marine mammal monitoring flights, aircraft will be flown at 
approximately 120 knots (138 mph) ground speed and usually at an 
altitude of 1,000 ft (305 m). Surveys in the Beaufort Sea are directed 
at bowhead whales, and an altitude of 900-1,000 ft (274-305 m) is the 
lowest survey altitude that can normally be flown without concern about 
potential aircraft disturbance. Aerial surveys at an altitude of 1,000 
ft (305 m) do not provide much information about seals but are suitable 
for both bowhead and beluga whales. The need for a 900-1000+ (374-305 
m) ft cloud ceiling will limit the dates and times when surveys can be 
flown.
    Two primary observers will be seated at bubble windows on either 
side of the aircraft and a third observer will observe part time and 
record data the rest of the time. All observers need bubble windows to 
facilitate downward viewing. 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. 
Ice observations during aerial surveys will be recorded and satellite 
imagery may be used, where available, during post-season analysis to 
determine ice conditions adjacent to the survey area. These are 
standard practices for surveys of this type and are necessary in order 
to interpret factors responsible for variations in sighting rates.
    During the late summer and fall, the bowhead whale is the primary 
species of concern, but belugas and gray whales are also present. To 
address concerns regarding deflection of bowheads at greater distances, 
the survey pattern around drilling operations has been designed to 
document whale distribution from about 25 mi (40 km) east of the 
drilling operations to about 37 mi (60 km) west of operations (see 
Figure 1 of Shell's 4MP).
    Bowhead whale movements during the late summer/autumn are generally 
from east to west, and transects should be designed to intercept rather 
than parallel whale movements. The transect lines in the grid will be 
oriented north-south, equally spaced at 5 mi (8 km) and randomly 
shifted in the east-west direction for each survey by no more than the 
transect spacing. The survey grid will total about 808 mi (1,300 km) in 
length, requiring approximately 6 hours to survey at a speed of 120 
knots (138 mph), plus ferry time. Exact lengths and durations will vary 
somewhat depending on the position of the drilling operation and thus 
of the grid, the sequence in which lines are flown (often affected by 
weather), and the number of refueling/rest stops.
    Weather permitting, transects making up the grid in the Beaufort 
Sea will be flown in sequence from west to east. This decreases 
difficulties associated with double counting of whales that are 
(predominantly) migrating westward. The survey sequence around the 
drilling operation is designed to monitor the distribution of whales 
around the drilling operation.
(3) Acoustic Monitoring
    As discussed earlier in this document, Shell will conduct SSV tests 
to establish the isopleths for the applicable safety radii. In 
addition, Shell proposes to use acoustic recorders to study bowhead 
deflections.
    Shell plans to deploy arrays of acoustic recorders in the Beaufort 
Sea in 2010, similar to that which was done in 2007 and 2008 using 
Directional Autonomous Seafloor Acoustic Recorders (DASARs). These 
directional

[[Page 20498]]

acoustic systems permit localization of bowhead whale and other marine 
mammal vocalizations. The purpose of the array will be to further 
understand, define, and document sound characteristics and propagation 
resulting from vessel-based drilling operations that may have the 
potential to cause deflections of bowhead whales from their migratory 
pathway. Of particular interest will be the east-west extent of 
deflection, if any (i.e., how far east of a sound source do bowheads 
begin to deflect and how far to the west beyond the sound source does 
deflection persist). Of additional interest will be the extent of 
offshore (or towards shore) deflection that might occur.
    In previous work around seismic and drillship operations in the 
Alaskan Beaufort Sea, the primary method for studying this question has 
been aerial surveys. Acoustic localization methods will provide 
supplementary information for addressing the whale deflection question. 
Compared to aerial surveys, acoustic methods have the advantage of 
providing a vastly larger number of whale detections, and can operate 
day or night, independent of visibility, and to some degree independent 
of ice conditions and sea state--all of which prevent or impair aerial 
surveys. However, acoustic methods depend on the animals to call, and 
to some extent, assume that calling rate is unaffected by exposure to 
industrial noise. Bowheads call frequently in fall, but there is some 
evidence that their calling rate may be reduced upon exposure to 
industrial sounds, complicating interpretation. The combined use of 
acoustic and aerial survey methods will provide a suite of information 
that should be useful in assessing the potential effects of drilling 
operations on migrating bowhead whales.
    Using passive acoustics with directional autonomous recorders, the 
locations of calling whales will be observed for a 6- to 10-week 
continuous monitoring period at five coastal sites (subject to 
favorable ice and weather conditions). Essential to achieving this 
objective is the continuous measurement of sound levels near the 
drillship.
    Shell plans to conduct the whale migration monitoring using the 
passive acoustics techniques developed and used successfully since 2001 
for monitoring the migration past Northstar production island northwest 
of Prudhoe Bay and from Kaktovik to Harrison Bay during the 2007 and 
2008 migrations. Those techniques involve using DASARs to measure the 
arrival angles of bowhead calls at known locations, then triangulating 
to locate the calling whale.
    In attempting to assess the responses of bowhead whales to the 
planned industrial operations, it will be essential to monitor whale 
locations at sites both near and far from industry activities. Shell 
plans to monitor at five sites along the Alaskan Beaufort coast as 
shown in Figure 10 of Shell's 4MP. The eastern-most site (5 in 
Figure 10 of the 4MP) will be just east of Kaktovik (approximately 62 
mi [100 km] west of the Sivulliq drilling area) and the western-most 
site (1 in Figure 10 of the 4MP) will be in the vicinity of 
Harrison Bay (approximately 109 mi [175 km] west of Sivulliq) . Site 2 
will be located west of Prudhoe Bay (approximately 68 mi [110 km] west 
of Sivulliq). Site 4 will be approximately 6.2 mi (10 km) east of the 
Sivulliq drilling area, and site 3 will be approximately 15.5 mi (25 
km) west of Sivulliq. These five sites will provide information on 
possible migration deflection well in advance of whales encountering an 
industry operation and on ``recovery'' after passing such operations 
should a deflection occur.
    The proposed geometry of DASARs at each site is comprised of seven 
DASARs oriented in a north-south pattern so that five equilateral 
triangles with 4.3-mi (7-km) element spacing is achieved. DASARs will 
be installed at planned locations using a GPS. However, each DASAR's 
orientation once it settles on the bottom is unknown and must be 
determined to know how to reference the call angles measured to the 
whales. Also, the internal clocks used to sample the acoustic data 
typically drift slightly, but linearly, by an amount up to a few 
seconds after 6 weeks of autonomous operation. Knowing the time 
differences within a second or two between DASARs is essential for 
identifying identical whale calls received on two or more DASARs.
    Bowhead migration begins in late August with the whales moving 
westward from their feeding sites in the Canadian Beaufort Sea. It 
continues through September and well into October. However, because of 
the drilling schedule, Shell will attempt to install the 21 DASARs at 
three sites (3, 4 and 5) in early August. The remaining 14 DASARs will 
be installed at sites 1 and 2 in late August. Thus, Shell proposes to 
be monitoring for whale calls from before August 15 until sometime 
before October 15.
    At the end of the season, the fourth DASAR in each array will be 
refurbished, recalibrated, and redeployed to collect data through the 
winter. The other DASARs in the arrays will be recovered. The 
redeployed DASARs will be programmed to record 35 min every 3 hours 
with a disk capacity of 10 months at that recording rate. This should 
be ample space to allow over-wintering from approximately mid-October 
2010, through mid-July 2011.
    Additional details on methodology and data analysis for the three 
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 Beaufort Sea in 2010. The panel met in late March 2010, and 
will provide comments to NMFS in mid-April 2010. 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 and the support vessels, will be 
submitted within 120 hr after collection and analysis of those 
measurements at the start of the field season. This report will specify 
the distances of the safety zones that were adopted for the exploratory 
drilling program.
(2) Technical Reports
    The results of Shell's 2010 Camden Bay 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 IHAs. Shell proposes that the Technical Reports will 
include: (1) Summaries of monitoring

[[Page 20499]]

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 DASAR; (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).
    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
    In November, 2007, Shell (in coordination and cooperation with 
other Arctic seismic IHA holders) released a final, peer-reviewed 
edition of the 2006 Joint Monitoring Program in the Chukchi and 
Beaufort Seas, July-November 2006 (LGL, 2007). This report is available 
on the NMFS Protected Resources Web site (see ADDRESSES). In March, 
2009, Shell released a final, peer-reviewed edition of the Joint 
Monitoring Program in the Chukchi and Beaufort Seas, Open Water 
Seasons, 2006-2007 (Ireland et al., 2009). This report is also 
available on the NMFS Protected Resources Web site (see ADDRESSES). A 
draft comprehensive report for 2008 (Funk et al., 2009) was provided to 
NMFS and those attending the Arctic Stakeholder Open-water Workshop in 
Anchorage, Alaska, on April 6-8, 2009. The 2008 report provides data 
and analyses from a number of industry monitoring and research studies 
carried out in the Chukchi and Beaufort Seas during the 2008 open-water 
season with comparison to data collected in 2006 and 2007. Reviewers 
plan to provide comments on the 2008 report to Shell. Once Shell is 
able to incorporate reviewer comments, the final 2008 report will be 
made available to the public. The 2009 draft comprehensive report is 
due to NMFS by mid-April 2010. NMFS will make this report available to 
the public upon receipt.
    Following the 2010 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 2010. 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. The comprehensive report 
will be due to NMFS within 240 days of the date of issuance of the IHA 
(if issued).
(4) Notification of Injured or Dead Marine Mammals
    Shell will notify NMFS' Office of Protected Resources and NMFS' 
Stranding Network within 48 hours of sighting an injured or dead marine 
mammal in the vicinity of drilling operations. 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).
    In the event that an injured or dead marine mammal is found by 
Shell that is not in the vicinity of the proposed drilling program, 
Shell will report the same information listed above to NMFS as soon as 
operationally feasible.

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. 
Anticipated impacts to marine mammals are associated with noise 
propagation from the drillship and associated support vessels. 
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, the most common impact will 
likely be from behavioral disturbance, including avoidance of the 
ensonified area or changes in speed, direction, and/or diving profile 
of the animal. For reasons discussed previously in this document, 
hearing impairment (TTS and PTS) are 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. Additionally, non-auditory physiological effects are 
anticipated to be minor, if any would occur at all. Finally, based on 
the proposed

[[Page 20500]]

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 175 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, NMFS uses a received level of 120-dB (rms) to indicate the 
onset of Level B harassment. Shell provided calculations for the 120-dB 
isopleths produced by the Discoverer and then used those isopleths to 
estimate takes by harassment. Shell also included modeling results of 
the 160-dB isopleths for the Discoverer and associated estimated takes 
by harassment. However, NMFS has used the 120-dB calculations to make 
the necessary MMPA preliminary findings. 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. However, this document only discusses the take 
estimates at the 120 dB level. Please refer to Shell's application for 
the full explanation and estimates at the 160 dB level.
    Shell has requested authorization for bowhead, gray, and beluga 
whales and ringed, spotted, and bearded seals. Additionally, Shell 
provided exposure estimates and requested takes of ribbon seals, 
humpback whales, minke whales, harbor porpoise, and narwhal. However, 
as stated previously in this document, sightings of these species are 
rare, and the likelihood of occurrence of these species in the proposed 
drilling area is minimal.

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 
sound levels of [gteqt]120 dB. The single exception to this method is 
for the estimation of exposures of bowhead whales during the fall 
migration where more detailed data were available, allowing an 
alternate approach, described below, to be used. NMFS evaluated and 
critiqued the methods provided in Shell's application and determined 
that they were appropriate in order to make the necessary preliminary 
MMPA findings. 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 
``Potential Number of Takes by Harassment'' subsection.
    Marine mammal densities near the operation are likely to vary by 
season and habitat. However, sufficient published data allowing the 
estimation of separate densities during summer (July and August) and 
fall (September and October) are only available for beluga and bowhead 
whales. As noted above, exposures of bowhead whales during the fall are 
not calculated using densities (see below). Therefore, summer and fall 
densities have been estimated for beluga whales, and a summer density 
has been estimated for bowhead whales. Densities of all other species 
have been estimated to represent the duration of both seasons.
    Marine mammal densities are also likely to vary by habitat type. In 
the Alaskan Beaufort Sea, where the continental shelf break is 
relatively close to shore, marine mammal habitat is often defined by 
water depth. Bowhead and beluga occurrence within nearshore (0-131 ft, 
0-40 m), outer continental shelf (131-656 ft, 40-200 m), slope (656-
6,562 ft, 200-2000 m), basin (>6,562 ft, 2000 m), or similarly defined 
habitats have been described previously (Moore et al., 2000; Richardson 
and Thomson, 2002). The presence of most other species has generally 
only been described relative to the entire continental shelf zone (0-
656 ft, 0-200 m) or beyond. Sounds produced by the drilling vessel are 
expected to drop below 120 dB within the nearshore zone (0-131 ft, 0-40 
m, water depth) while sounds produced by ice-management activities, if 
they are necessary, are likely to also be present in the outer 
continental shelf (131-656 ft, 40-200 m). Sounds [gteqt]120 dB are not 
expected to occur in waters >656 ft (200 m). Since the only instance in 
which sounds at the indicated levels may be introduced to the outer 
continental shelf would be during ice-management activities, and 
therefore ice-margin densities are more applicable, separate beluga and 
bowhead densities for the outer continental shelf have not been used in 
the calculations.
    In addition to water depth, densities of marine mammals are likely 
to vary with the presence or absence of sea ice (see later for 
descriptions by species). At times during either summer or fall, pack-
ice may be present in some of the area around the drilling operation. 
However, the retreat of sea ice in the Alaskan Beaufort Sea has been 
substantial in recent years, so Shell has assumed that only 33 percent 
of the area exposed to sounds [gteqt]120 dB by the drilling vessel will 
be in ice margin habitat. Therefore, ice-margin densities of marine 
mammals in both seasons have been multiplied by 33 percent of the area 
exposed to sounds by the drilling vessel, while open-water (nearshore) 
densities have been multiplied by the remaining 67 percent of the area.
    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. NMFS has determined that the average density data of 
marine mammal populations will be used to calculate estimated take 
numbers because these numbers are based on surveys and monitoring of 
marine mammals in the vicinity of the proposed project area. NMFS only 
used the ``maximum'' estimate for marine mammal species that are less 
likely to occur in the project area and for which little to no density 
information exists (i.e., gray whales and spotted seals).
    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. 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).
(1) Cetaceans
    As noted above, the densities of beluga and bowhead whales present 
in the Beaufort Sea are expected to vary by season and location. During 
the early and mid-summer, most belugas and bowheads are found in the 
Canadian Beaufort Sea and Amundsen Gulf or adjacent areas. Low numbers 
are found in the eastern Alaskan Beaufort Sea. Belugas begin to move 
across the Alaskan Beaufort Sea in August, and bowheads do so toward 
the end of August.
    Beluga Whales--Beluga density estimates were derived from data in

[[Page 20501]]

Moore et al. (2000). During the summer, beluga whales are most likely 
to be encountered in offshore waters of the eastern Alaskan Beaufort 
Sea or areas with pack ice. The summer beluga whale nearshore density 
(Table 6-1 in Shell's application and Table 1 here) was based on 7,447 
mi (11,985 km) of on-transect effort and nine associated sightings that 
occurred in water <=164 ft (50 m) in Moore et al. (2000; Table 6-2 in 
Shell's application and Table 2 here). A mean group size of 1.63, a 
f(0) value of 2.841, and a g(0) value of 0.58 from Harwood et al. 
(1996) were also used in the calculation. Moore et al. (2000) found 
that belugas were equally likely to occur in heavy ice conditions as 
open-water or very light ice conditions in summer in the Beaufort Sea, 
so the same density was used for both nearshore and ice-margin 
estimates (Table 6-1 in Shell's application and Table 1 here). The fall 
beluga whale nearshore density was based on 45,180.5 mi (72,711 km) of 
on-transect effort and 28 associated sightings that occurred in water 
<=164 ft (50 m) reported in Moore et al. (2000). A mean group size of 
2.9 (CV=1.9), calculated from all Beaufort Sea fall beluga sightings in 
<=164 ft (50 m) of water present in the Bowhead Whale Aerial Survey 
Program database, along with the same f(0) and g(0) values from Harwood 
et al. (1996) were also used in the calculation. Moore et al. (2000) 
found that during the fall in the Beaufort Sea belugas occurred in 
moderate to heavy ice at higher rates than in light ice, so ice-margin 
densities were estimated to be twice the nearshore densities. Based on 
the CV of group size maximum estimates in both season and habitats were 
estimated as four times the average estimates. ``Takes by harassment'' 
of beluga whales during the fall in the Beaufort Sea were not 
calculated in the same manner as described for bowhead whales because 
of the relatively lower expected densities of beluga whales in 
nearshore habitat near the exploration drilling program and the lack of 
detailed data on the likely timing and rate of migration through the 
area.

 Table 1--Expected Summer (Jul-Aug) Densities of Beluga and Bowhead Whales in the Eastern Alaskan Beaufort Sea.
 Densities Are Corrected for f(0) and g(0) Biases. Species Listed Under the U.S. ESA as Endangered Are Shown in
                                                     Italic
----------------------------------------------------------------------------------------------------------------
                                                       Nearshore                          Ice margin
                                         -----------------------------------------------------------------------
                 Species                  Average  density  Maximum  density  Average  density  Maximum  density
                                             ( /      ( /      ( /      ( /
                                               km\2\)            km\2\)            km\2\)            km\2\)
----------------------------------------------------------------------------------------------------------------
Beluga..................................            0.0030            0.0120            0.0030            0.0120
Bowhead whale...........................            0.0186            0.0717            0.0186            0.0717
----------------------------------------------------------------------------------------------------------------


  Table 2--Expected Fall (Sep-Nov) Densities of Beluga and Bowhead Whales in the Eastern Alaskan Beaufort Sea.
 Densities Are Corrected for f(0) and g(0) Biases. Species Listed Under the U.S. ESA as Endangered Are Shown in
                                                     Italic
----------------------------------------------------------------------------------------------------------------
                                                       Nearshore                          Ice margin
                                         -----------------------------------------------------------------------
                 Species                  Average  density  Maximum  density  Average  density  Maximum  density
                                             ( /      ( /      ( /      ( /
                                               km\2\)            km\2\)            km\2\)            km\2\)
----------------------------------------------------------------------------------------------------------------
Beluga..................................            0.0027            0.0108            0.0054            0.0216
Bowhead whale\a\........................                NA                NA                NA                NA
----------------------------------------------------------------------------------------------------------------
\a\ See text for description of how bowhead whales estimates were made.

    Bowhead Whales--Industry aerial surveys of the continental shelf 
near Camden Bay in 2008 recorded eastward migrating bowhead whales 
until July 12 (Lyons and Christie, 2009). No bowhead sightings were 
recorded again, despite continued flights until August 19. Aerial 
surveys by industry operators did not begin until late August of 2006 
and 2007, but in both years bowheads were also recorded in the region 
before the end of August (Christie et al., 2009). The late August 
sightings were likely of bowheads beginning their fall migration, so 
the densities calculated from those surveys were not used to estimate 
summer densities in this region. The three surveys in July 2008, 
resulted in density estimates of 0.0099, 0.0717, and 0.0186 whales/
km\2\, respectively. The estimate of 0.0186 whales/km\2\ was used as 
the average summer nearshore density, and the estimate of 0.0717 
whales/km\2\ was used as the maximum. Sea ice was not present during 
these surveys. Moore et al. (2000) reported that bowhead whales in the 
Alaskan Beaufort Sea were distributed uniformly relative to sea ice, so 
the same nearshore densities were used for ice-margin habitat.
    During the fall, most bowhead whales will be migrating west past 
the exploration drilling program, so it is less accurate to assume that 
the number of individuals present in the area from one day to the next 
will be static. However, feeding, resting, and milling behaviors are 
not entirely uncommon at this time and location either. In order to 
incorporate the movement of whales past the planned operations, and 
because the necessary data are available, Shell developed an alternate 
method of calculating the number of individual bowheads exposed to 
sounds produced by the exploration drilling program from the method 
used to calculate the number of exposures for bowheads in summer and 
the other marine mammal species for the entire season. The method is 
founded on estimates of the proportion of the population that would 
pass within the >=120 dB zone on a given day in the fall during the 
exploration drilling program. Based on the fact that most bowhead 
whales will be engaged in the fall migration at this time, NMFS 
preliminarily determined that this method was appropriate for 
estimating the number of individual bowhead whales that may be exposed 
to drilling sounds after August 25.
    Exploration drilling will be suspended on August 25 prior to the 
start of the bowhead subsistence hunts

[[Page 20502]]

at Kaktovik and Nuiqsut (Cross Island) and will be resumed when the 
hunts are concluded. After the completion of the subsistence hunts 
(expected in mid-September), approximately 40 days of activity will be 
required to complete the planned drilling operations. The current 
population size would be approximately 14,247 individuals based on a 
2001 population of 10,545 (Zeh and Punt, 2005) and a continued annual 
growth rate of 3.4 percent (Allen and Angliss, 2010). Based on data in 
Richardson and Thomson (2002, Appendix 9.1), the number of whales 
expected to pass each day after conclusion of the bowhead subsistence 
hunts (assumed to be September 15) was estimated as a proportion of the 
population. Minimum and maximum estimates of the number of whales 
passing each day were not available, so a single estimate based on the 
10-day moving average presented by Richardson and Thomson (2002) was 
used. Richardson and Thomson (2002) also calculated the proportion of 
animals within water depth bins (<66 ft [20m], 66-131 ft [20-40m], 131-
656 ft [40-200m], and >656 ft [200m]). Using this information, Shell 
multiplied the total number of whales expected to pass the drilling 
program each day by the proportion of whales that would be in each 
depth category to estimate how many individuals would be within each 
depth bin on a given day. The proportion of each depth bin falling 
within the >=120 dB zone was then multiplied by the number of whales 
within the respective bins to estimate the total number of individuals 
that would be exposed on each day. This was repeated for a total of 40 
days (September 15 to October 24), and the results were summed to 
estimate the total number of bowhead whales that might be exposed to 
>=120 dB during the migration period in the Beaufort Sea. If the hunts 
at Kaktovik and Cross Island (Nuiqsut) end later than September 15, the 
number of exposures calculated by Shell would be an overestimate, as 
Shell will still need to end active operations by the end of October 
because of the increased chance of their being additional ice covering 
the drill sites later in the season.
    Gray Whales--For gray whales, densities are likely to vary somewhat 
by season, but differences are not expected to be great enough to 
require estimation of separate densities for the two seasons. Gray 
whales are not expected to be present in large numbers in the Beaufort 
Sea during the fall but small numbers may be encountered during the 
summer. They are most likely to be present in nearshore waters. Since 
this species occurs infrequently in the Beaufort Sea, little to no data 
are available for the calculation of densities. Minimal densities have 
therefore been assigned for calculation purpose and to allow for chance 
encounters (see Table 6-3 in Shell's application and Table 3 here).

 Table 3--Expected Densities of Cetaceans (Excluding Beluga and Bowhead Whale) and Seals in the Alaskan Beaufort
                                                       Sea
----------------------------------------------------------------------------------------------------------------
                                                       Nearshore                          Ice margin
                                         -----------------------------------------------------------------------
                 Species                  Average  density  Maximum  density  Average  density  Maximum  density
                                             ( /      ( /      ( /      ( /
                                               km\2\)            km\2\)            km\2\)            km\2\)
----------------------------------------------------------------------------------------------------------------
Odontocetes:
    Monodontidae:
        Narwhal.........................            0.0000            0.0000            0.0000            0.0001
    Phocoenidae:
        Harbor porpoise.................            0.0001            0.0004            0.0000            0.0000
Mysticetes:
    Gray whale..........................            0.0001            0.0004            0.0000            0.0000
Pinnipeds:
    Bearded seal........................            0.0181            0.0724            0.0128            0.0512
    Ribbon seal.........................            0.0001            0.0004            0.0001            0.0004
    Ringed seal.........................            0.3547            1.4188            0.2510            1.0040
    Spotted seal........................            0.0037            0.0149            0.0001            0.0004
----------------------------------------------------------------------------------------------------------------

(2) Pinnipeds
    Extensive surveys of ringed and bearded seals have been conducted 
in the Beaufort Sea, but most surveys have been conducted over the 
landfast ice, and few seal surveys have occurred in open-water or in 
the pack ice. Kingsley (1986) conducted ringed seal surveys of the 
offshore pack ice in the central and eastern Beaufort Sea during late 
spring (late June). These surveys provide the most relevant information 
on densities of ringed seals in the ice margin zone of the Beaufort 
Sea. The density estimate in Kingsley (1986) was used as the average 
density of ringed seals that may be encountered in the ice margin 
(Table 6-3 in Shell's application and Table 3 here). The average ringed 
seal density in the nearshore zone of the Alaskan Beaufort Sea was 
estimated from results of ship-based surveys at times without seismic 
operations reported by Moulton and Lawson (2002; Table 6-3 in Shell's 
application and Table 3 here).
    Densities of bearded seals were estimated by multiplying the ringed 
seal densities by 0.051 based on the proportion of bearded seals to 
ringed seals reported in Stirling et al. (1982; Table 6-3 in Shell's 
application and Table 3 here). Spotted seal densities in the nearshore 
zone were estimated by summing the ringed seal and bearded seal 
densities and multiplying the result by 0.015 based on the proportion 
of spotted seals to ringed plus bearded seals reported in Moulton and 
Lawson (2002; Table 6-3 in Shell's application and Table 3 here). 
Minimal values were assigned as densities in the ice-margin zones 
(Table 6-3 in Shell's application and Table 3 here).

Potential Number of Takes by Harassment

(1) Estimates of the Number of Individuals That May Be Exposed to 
Sounds =120 dB
    Just because a marine mammal is exposed to drilling sounds 
=120 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

[[Page 20503]]

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) operating in 
Camden Bay beginning in July. Shell will not operate the Discoverer and 
associated vessels in Camden Bay during the 2010 Kaktovik and Nuiqsut 
(Cross Island) fall bowhead whale subsistence harvests. Shell will 
suspend exploration activities on August 25, prior to the beginning of 
the hunts, will resume activities in Camden Bay after conclusion of the 
subsistence harvests, and complete exploration activities on or about 
October 31, 2010. Actual drilling may occur on approximately 74 days 
while the Discoverer is in Camden Bay, approximately half of which 
would occur before and after the fall bowhead subsistence hunts.
    The number of different individuals of each species potentially 
exposed to received levels >=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.
(2) Estimated Area Exposed to Sounds >=120 dB
    The total area of a 4.6 mi (7.4 km) radius circle (66.4 mi\2\ [172 
km\2\]; representing 1.5 x the >=120 dB radius of 3.06 mi [4.93 km] 
modeled by JASCO for the Discoverer) was used to calculate the area 
ensonified to >=120 dB around the Discoverer operating at either of the 
planned drill sites (Sivulliq N and Torpedo H). This area falls within 
water less than 131 ft (40 m) deep at both planned locations. The area 
exposed to sounds by drilling occurs in waters <=131 ft (40 m) deep, so 
67 percent was multiplied by the nearshore zone densities and the 
remaining 33 percent by the ice-margin densities.
    For analysis of potential effects on migrating bowhead whales, 
Shell calculated the total distance perpendicular to the migration path 
ensonified to >=120 dB (4.6 mi [7.4 km] radius x 2 = 9.2 mi [14.8 km]) 
by the Discoverer. This represents 41 percent of the 22 mi (36 km) 
between the barrier islands and the 131 ft (40 m) bathymetry line, so 
it was assumed that 41 percent of the bowheads migrating within the 
nearshore zone (water depth 0-131 ft [0-40 m]) may be exposed to sounds 
>=120 dB, if they showed no avoidance of the drilling operations.
    Cetaceans--Cetacean species potentially exposed to drilling program 
sounds with received levels >=120 dB would involve bowhead, gray, and 
beluga whales. Shell also included some maximum exposure estimates for 
narwhal, harbor porpoise, humpback whale, and minke whale. However, as 
stated previously in this document, NMFS has determined that 
authorizing take of these four cetacean species is not warranted 
because the probability of these species being present in the drilling 
area is remote. Average and maximum estimates of the number of 
individual cetaceans exposed, in descending order, are bowhead whale 
(1,968 and 1,977), beluga whale (1 and 4), and gray whale (0 and 5). 
Table 6-7 in Shell's application and Table 4 here summarize the number 
of marine mammal species or stocks that may experience Level B 
harassment.
    The estimates show that one endangered cetacean species (the 
bowhead whale) is expected to be exposed to sounds >=120 dB unless 
bowheads avoid the area around the drill sites (Tables 6-4 and 6-5 in 
Shell's application). Migrating bowheads are likely to do so to some 
extent, though many of the bowheads engaged in other activities, 
particularly feeding and socializing, probably will not (Richardson, 
2004).
    Pinnipeds--The ringed seal is the most widespread and abundant 
pinniped in ice-covered arctic waters, and there appears to be a great 
deal of year-to-year variation in abundance and distribution of these 
marine mammals. Ringed seals account for a large number of marine 
mammals expected to be encountered during the exploration drilling 
program, and hence exposed to sounds with received levels >=120 dB. The 
average (and maximum) estimate is that 109 (436) ringed seals might be 
exposed to sounds with received levels >=120 dB from the exploration 
drilling program.
    Two additional seal species are expected to be encountered. Average 
and maximum estimates for bearded seal exposures to sound levels >=120 
dB were 6 and 22, respectively. For spotted seal these exposure 
estimates were 1 and 3, respectively. Table 6-7 in Shell's application 
and Table 4 here summarize the number of marine mammal species or 
stocks that may experience Level B harassment.

 Table 4--Summary of the Number of Potential Exposures of Marine Mammals
 to Received Sound Levels in the Water of >=120 dB and (>=160 dB) During
   Shell's Planned Exploration Drilling Program Near Camden Bay in the
               Beaufort Sea, Alaska, July-October 31, 2010
------------------------------------------------------------------------
                                            Total number of exposure to
                                             sound levels >120 dB and
                 Species                            (>=160 dB)
                                         -------------------------------
                                               Avg.            Max.
------------------------------------------------------------------------
Odontocetes:
    Monodontidae:
        Beluga..........................           1 (0)           4 (0)
        Narwhal.........................           0 (0)           5 (5)
    Phocoenidae:
        Harbor porpoise.................           0 (0)           5 (5)
Mysticetes:
    Bowhead whale \a\...................       1968 (14)       1977 (14)
    Gray whale..........................           0 (0)           5 (5)
    Humpback whale......................           0 (0)           5 (5)

[[Page 20504]]

 
    Minke whale.........................           0 (0)           5 (5)
                                         -------------------------------
        Total Cetaceans.................       1968 (14)       1992 (29)
Pinnipeds:
    Bearded seal........................           6 (0)          22 (0)
    Ringed seal.........................         109 (0)         436 (0)
    Ribbon seal.........................           0 (0)           5 (5)
    Spotted seal........................           1 (0)           5 (5)
                                         -------------------------------
        Total Pinnipeds.................         115 (0)        467 (10)
------------------------------------------------------------------------

Estimated Take Conclusions

    As stated previously, NMFS' practice has been to apply the 120 dB 
re 1 [micro]Pa (rms) received level threshold for underwater continuous 
sound levels to determine whether take by Level B harassment occurs. 
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. 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 
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-pulses 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 sound at levels of 120 dB (rms) or even 
higher.
    Although the 120-dB isopleth for the drillship may seem fairly 
expansive (i.e., 4.6 mi [7.4 km], which includes the 50 percent 
inflation factor), the zone of ensonification begins to shrink 
dramatically with each 10-dB increase in received sound level. Table 5 
here depicts the radii for the 120, 130, 140, 150, and 160 dB received 
levels for the drillship. As stated previously, source levels are 
expected to be 175 dB (rms). For an animal to receive a sound at this 
level, it would have to be within several meters of the vessel, which 
is unlikely, especially give the fact that certain species are likely 
to avoid the area (as described earlier in this document).

   Table 5--Modeled Sound Levels at the 120, 130, 140, 150, and 160 dB
   Isopleths for the Drillship--These Distances Do Not Include the 50
            Percent Inflation Factor Used for Estimating Take
------------------------------------------------------------------------
                                                            Drillship
         Received levels  (dB re 1 [mu]Pa rms)           (distance in m)
------------------------------------------------------------------------
160...................................................                35
150...................................................                55
140...................................................               216
130...................................................             1,358
120...................................................             4,930
------------------------------------------------------------------------

    Table 6-7 in Shell's application and Table 4 here present the 
number of each species that may be exposed to sounds >=160 dB. This 
number is substantially less than the number of individuals from each 
species that may be exposed to sounds at the 120 dB level. For example, 
1,968 bowhead whales are estimated to be exposed to sounds >=120 dB; 
however, only 14 bowhead whales are estimated to be exposed to sounds 
>=160 dB. Additionally, using the same calculations, only 541, 86, and 
22 bowhead whales are estimated to be exposed to sounds >=130, 140, and 
150 dB, respectively. Therefore, while 1,968 bowhead whales may occur 
within 4.6 mi (7.4 km) of the drillship, which is an area 1.5 x greater 
than the 120 dB radius, only a small percentage of the animals would 
occur in areas with received sound levels that may elicit more intense 
observed behavioral responses.
    The ringed seal is the species with the second highest predicted 
encounter rate during Shell's proposed drilling program. Although there 
is the potential for 109 ringed seals to be exposed to sounds >=120 dB, 
this number drops to zero at the 160 dB level. Additionally, using the 
same calculations, only 8 ringed seals are estimated to be exposed to 
sounds >=130, and none are expected to be exposed to sounds at the 140-
, 150--, or 160--dB levels. Moreover, fewer studies have been conducted 
on the reactions of pinnipeds to continuous sound sources. However, it 
appears that most pinnipeds are more tolerant and less responsive to 
sounds at lower received levels than most cetaceans, especially 
mysticetes.
    NMFS is proposing to authorize the average take estimates provided 
in Table 6-7 of Shell's application and Table 4 here. The only 
exceptions to this are for the gray whale since the average estimate is 
zero and for the beluga whale to account for group size. Therefore, 
NMFS proposes to authorize

[[Page 20505]]

the take of 4 beluga whales, 1,968 bowhead whales, 5 gray whales, 6 
bearded seals, 109 ringed seals, and 1 spotted seal. For beluga and 
gray whales, this represents 0.01 percent of the Beaufort Sea 
population of approximately 39,258 beluga whales (Angliss and Allen, 
2009) and 0.03 percent of the Eastern North Pacific stock of 
approximately 17,752 gray whales. This also represents 13.8 percent of 
the Bering-Chukchi-Beaufort population of 14,247 individuals assuming 
3.4 percent annual population growth from the 2001 estimate of 10,545 
animals (Zeh and Punt, 2005). The take estimates presented for bearded, 
ringed, and spotted seals represent 0.1, 0.04, and 0.1 percent of the 
Bering-Chukchi-Beaufort populations for each species, respectively.
    With the exception of the subsistence mitigation measure of 
shutting down during the Nuiqsut and Kaktovik fall bowhead whale hunts, 
these take estimates do not take into account any of the mitigation 
measures described previously in this document. Additionally, if the 
fall bowhead hunts end after September 15, and Shell still concludes 
activities on October 31, then fewer animals will be exposed to 
drilling sounds, especially bowhead whales, as more of them will have 
migrated past the area in which they would be exposed to sound levels 
of 120 dB or greater prior to Shell resuming active operations.
    Lastly, even though Shell has indicated that the Camden Bay 
drilling program will occur for 74 days between July 10 and October 31, 
2010, Shell has requested that the IHA (if issued) be valid for a full 
year. NMFS is proposing to grant this request in the event that Shell 
is unable to conduct active operations for the full 74 days. Therefore, 
depending on the expiration date of the IHA (if issued), Shell could 
potentially work early in the 2011 open-water season. The take numbers 
presented here (and in Shell's application) are based on 74 days of 
active operations. Therefore, these numbers account for this situation. 
In fact, these numbers may then be an overestimate, as fewer animals, 
especially bowhead and beluga whales, would be expected at the drill 
sites in early July 2011.
Negligible Impact and Small Numbers Analysis and Preliminary 
Determination
    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 Camden Bay exploratory drilling program, and none are 
proposed to be authorized. Additionally, animals in the area are not 
expected to incur hearing impairment (i.e., TTS or PTS) or non-auditory 
physiological effects. Takes will be limited to Level B behavioral 
harassment. 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 westward across the Beaufort Sea. This is 
especially true for bowhead whales that will be migrating past the 
drilling operations beginning in mid- to late September (depending on 
the date Shell resumes activities after the shutdown period for the 
fall bowhead subsistence hunts by the villages of Kaktovik and 
Nuiqsut).
    Some studies have shown that bowhead whales will continue to feed 
in areas of seismic operations (e.g., Richardson, 2004). Therefore, it 
is possible that some bowheads may continue to feed in an area of 
active drilling operations. It is important to note that the sounds 
produced by drilling operations are of a much lower intensity than 
those produced by seismic airguns. Should bowheads chose to feed in the 
ensonified area instead of avoiding the sound, individuals may be 
exposed to sounds at or above 120 dB (rms) for several hours to days, 
depending on how long the individual animal chooses to remain in the 
area to feed. As noted previously, many animals perform vital 
functions, such as feeding, resting, traveling, and socializing on a 
diel cycle (24-hr cycle). As discussed here, some bowhead whales may 
decide to remain in Camden Bay for several days to feed; however, they 
are not expected to be feeding for 24 hours straight each day. While 
feeding in an area of increased anthropogenic sound may potentially 
result in increased stress, it is not anticipated that the level of 
sound produced by the exploratory drilling operations and the amount of 
time that an individual whale may remain in the area to feed would 
result in extreme physiological stress to the animal. Additionally, if 
an animal is excluded from Camden Bay for feeding because it decides to 
avoid the ensonified area, this may result in some extra energy 
expenditure for the animal to find an alternate feeding ground. 
However, Camden Bay is one of a few feeding areas for bowhead whales in 
the U.S. Arctic Ocean. The disruption to feeding is not anticipated to 
have more than a negligible impact on the affected species or stock.
    Some bowhead whales have been observed feeding in the Camden Bay 
area in recent years. There has also been recent evidence that some 
bowhead whales continued feeding in close proximity to seismic sources 
(e.g., Richardson, 2004). The sounds produced by the drillship are of 
lower intensity than those produced by seismic airguns. Therefore, if 
animals remain in ensonified areas to feed, they would be in areas 
where the sound levels are not high enough to cause injury (based on 
the fact that source levels are not expected to reach levels known to 
cause even slight, mild TTS, a non-injurious threshold shift).
    Beluga whales are more likely to occur in the project area after 
the recommencement of activities in September than in July or August. 
Should any belugas occur in the area of active drilling, it is not 
expected that they would remain in the area for a prolonged period of 
time, as their westward migration usually occurs further offshore (more 
than 37 mi [60 km]) and in deeper waters (more than 656 ft [200 m]) 
than that planned for the location of Shell's Camden Bay well sites. 
Gray whales do not frequently occur in the Camden Bay area of the 
Beaufort Sea, so exposures to industrial sound are not expected to last 
for prolonged periods (i.e., several days or weeks). The exposure of 
cetaceans to sounds produced by exploratory drilling operations is not 
expected to result in more than Level B harassment and is anticipated 
to have no more than a negligible impact on the affected species or 
stock.
    Some individual pinnipeds may be exposed to drilling sounds more 
than once during the time frame of the project. This may be especially 
true for ringed seals, which occur in the Beaufort Sea year-round and 
are the most frequently encountered pinniped species in the area. 
However, 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. NMFS has 
preliminarily determined that the exposure of pinnipeds to sounds

[[Page 20506]]

produced by exploratory drilling operations is not expected to result 
in more than Level B harassment and is anticipated to have no more than 
a negligible impact on the animals.
    Of the six marine mammal species likely to occur in the proposed 
drilling area, only the bowhead whale is listed as endangered under the 
ESA. The species is 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 percent annually for 
nearly a decade (Allen and Angliss, 2010). 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, 2010). There is no 
critical habitat designated in the U.S. Arctic for the bowhead whale. 
The bearded and ringed seals are ``candidate species'' under the ESA, 
meaning they are currently being considered for listing but are not 
designated as depleted under the MMPA. None of the other three species 
that may occur in the project area are listed as threatened or 
endangered under the ESA or designated as depleted under the MMPA.
    Potential impacts to marine mammal habitat were discussed 
previously in this document (see the ``Anticipated Effects on Habitat'' 
section). Although some disturbance is possible to food sources of 
marine mammals, the impacts are anticipated to be minor enough as to 
not affect rates of recruitment or survival of marine mammals in the 
area. 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 minor based on the fact that other feeding grounds exist 
elsewhere.
    The estimated takes proposed to be authorized represent 0.01 
percent of the Beaufort Sea population of approximately 39,258 beluga 
whales (Angliss and Allen, 2009), 0.03 percent of the Eastern North 
Pacific stock of approximately 17,752 gray whales, and 13.8 percent of 
the Bering-Chukchi-Beaufort population of 14,247 individuals assuming 
3.4 percent annual population growth from the 2001 estimate of 10,545 
animals (Zeh and Punt, 2005). The take estimates presented for bearded, 
ringed, and spotted seals represent 0.1, 0.04, and 0.1 percent of the 
Bering-Chukchi-Beaufort populations for each species, respectively. 
These estimates represent the percentage of each species or stock that 
could be taken by Level B behavioral harassment if each animal is taken 
only once. Additionally, these numbers are likely an overestimate, as 
these take numbers were calculated using a 50 percent inflation factor 
of the 120-dB radius, 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 a similar drillship (i.e., the Northern Explorer II). SSV 
tests may reveal that the Level B harassment zone may in fact be 
smaller than that used to estimate take. If the SSV tests reveal that 
the Level B harassment zone is slightly larger than that of the 
Northern Explorer II, the 50 percent inflation factor should cover the 
discrepancy. 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.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the mitigation and monitoring 
measures, NMFS preliminarily finds that Shell's proposed Camden Bay 
exploratory drilling program may result in the incidental take of small 
numbers of marine mammals, by Level B harassment only, and that the 
total taking from the exploratory drilling program will have a 
negligible impact on the affected species or stocks.
Impact on Availability of Affected Species or Stock for Taking for 
Subsistence Uses

Relevant Subsistence Uses

    The disturbance and potential displacement of marine mammals by 
sounds from drilling activities are the principal concerns related to 
subsistence use of the area. Subsistence remains the basis for Alaska 
Native culture and community. Marine mammals are legally hunted in 
Alaskan waters by coastal Alaska Natives. In rural Alaska, subsistence 
activities are often central to many aspects of human existence, 
including patterns of family life, artistic expression, and community 
religious and celebratory activities. Additionally, the animals taken 
for subsistence provide a significant portion of the food that will 
last the community throughout the year. The main species that are 
hunted include bowhead and beluga whales, ringed, spotted, and bearded 
seals, 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 Beaufort Sea that have the 
potential to be impacted by Shell's Camden Bay drilling program include 
Kaktovik, Nuiqsut, and Barrow. Kaktovik is a coastal community 60 mi 
(96.6 km) east of the project area. Nuiqsut is 118 mi (190 km) west of 
the project area and about 20 mi (32 km) inland from the coast along 
the Colville River. Cross Island, from which Nuiqsut hunters base their 
bowhead whaling activities, is 47 mi (75.6 km) southwest of the project 
area. Barrow, the community farthest from the project area, lies 298 mi 
(479.6 km) west of Shell's Camden Bay drill sites.
(1) Bowhead Whales
    Of the three communities, Barrow is the only one that currently 
participates in a spring bowhead whale hunt. However, this hunt is not 
anticipated to be affected by Shell's activities, as the spring hunt 
occurs in late April to early May, and Shell's Camden Bay drilling 
program will not begin until July 10, at the earliest.
    All three communities participate in a fall bowhead hunt. In 
autumn, westward-migrating bowhead whales typically reach the Kaktovik 
and Cross Island (Nuiqsut hunters) areas by early September, at which 
points the hunts begin (Kaleak, 1996; Long, 1996; Galginaitis and 
Koski, 2002; Galginaitis and Funk, 2004, 2005; Koski et al., 2005). 
Around late August, the hunters from Nuiqsut establish camps on Cross 
Island from where they undertake the fall bowhead whale hunt. The 
hunting period starts normally in early September and may last as late 
as mid-October, depending mainly on ice and weather conditions and the 
success of the hunt. Most of the hunt occurs offshore in waters east, 
north, and northwest of Cross Island where bowheads migrate and not 
inside the barrier islands (Galginaitis, 2007). Hunters prefer to take 
bowheads close to shore to avoid a long tow, but Braund and Moorehead 
(1995) report that crews may (rarely) pursue whales as far as 50 mi (80 
km) offshore. Whaling crews use Kaktovik as their home base, leaving 
the village and returning on a daily basis. The core whaling area is 
within 12 mi (19.3 km) of the village with a periphery ranging about 8 
mi (13 km) farther, if necessary. The extreme limits of the Kaktovik 
whaling limit would be the

[[Page 20507]]

middle of Camden Bay to the west. The timing of the Kaktovik bowhead 
whale hunt roughly parallels the Cross Island whale hunt (Impact 
Assessment Inc, 1990b; SRB&A, 2009: Map 64). In recent years, the hunts 
at Kaktovik and Cross Island have usually ended by mid- to late 
September.
    Westbound bowheads typically reach the Barrow area in mid-
September, and are in that area until late October (Brower, 1996). 
However, over the years, local residents report having seen a small 
number of bowhead whales feeding off Barrow or in the pack ice off 
Barrow during the summer. Recently, autumn bowhead whaling near Barrow 
has normally begun in mid-September to early October, but in earlier 
years it began as early as August if whales were observed and ice 
conditions were favorable (USDI/BLM, 2005). The recent decision to 
delay harvesting whales until mid-to-late September has been made to 
prevent spoilage, which might occur if whales were harvested earlier in 
the season when the temperatures tend to be warmer. Whaling near Barrow 
can continue into October, depending on the quota and conditions.
    Shell anticipates arriving on location in Camden Bay around July 10 
and continuing operations until August 25. Shell has stated that it 
will suspend all operations on August 25 for the Nuiqsut (Cross Island) 
and Kaktovik subsistence bowhead whale hunts. The Discoverer and 
support vessels will leave the Camden Bay project area, will move to a 
location at or north of 71.25[deg]N. latitude and at or west of 
146.4[deg]W. longitude, and will return to resume activities after the 
Nuiqsut (Cross Island) and Kaktovik bowhead hunts conclude. Depending 
on when Nuiqsut and Kaktovik declare their hunts closed, drilling 
operations may resume in the middle of the Barrow fall bowhead hunt.
(2) Beluga Whales
    Beluga whales are not a prevailing subsistence resource in the 
communities of Kaktovik and Nuiqsut. Kaktovik hunters may harvest one 
beluga whale in conjunction with the bowhead hunt; however, it appears 
that most households obtain beluga through exchanges with other 
communities. Although Nuiqsut hunters have not hunted belugas for many 
years while on Cross Island for the fall hunt, this does not mean that 
they may not return to this practice in the future. Data presented by 
Braund and Kruse (2009) indicate that only one percent of Barrow's 
total harvest between 1962 and 1982 was of beluga whales and that it 
did not account for any of the harvested animals between 1987 and 1989.
    There has been minimal harvest of beluga whales in Beaufort Sea 
villages in recent years. Additionally, if belugas are harvested, it is 
usually in conjunction with the fall bowhead harvest. Shell will not be 
operating during the Kaktovik and Nuiqsut fall bowhead harvests.
(3) Ice Seals
    Ringed seals are available to subsistence users in the Beaufort Sea 
year-round, but they are primarily hunted in the winter or spring due 
to the rich availability of other mammals in the summer. Bearded seals 
are primarily hunted during July in the Beaufort Sea; however, in 2007, 
bearded seals were harvested in the months of August and September at 
the mouth of the Colville River Delta. An annual bearded seal harvest 
occurs in the vicinity of Thetis Island (which is a considerable 
distance from Shell's proposed Camden Bay drill sites) in July through 
August. Approximately 20 bearded seals are harvested annually through 
this hunt. Spotted seals are harvested by some of the villages in the 
summer months. Nuiqsut hunters typically hunt spotted seals in the 
nearshore waters off the Colville River delta, which is more than 100 
mi (161 km) from Shell's proposed drill sites.
    Although there is the potential for some of the Beaufort villages 
to hunt ice seals during the summer and fall months while Shell is 
conducting exploratory drilling operations, the primary sealing months 
occur outside of Shell's operating time frame. Additionally, some of 
the more established seal hunts that do occur in the Beaufort Sea, such 
as the Colville delta area hunts, are located a significant distance 
(in some instances 100 mi [161 km] or more) from the proposed project 
area.

Potential Impacts to Subsistence Uses

    NMFS has defined ``unmitigable adverse impact'' in 50 CFR 216.103 
as:

    * * * an impact resulting from the specified activity: (1) That 
is likely to reduce the availability of the species to a level 
insufficient for a harvest to meet subsistence needs by: (i) Causing 
the marine mammals to abandon or avoid hunting areas; (ii) Directly 
displacing subsistence users; or (iii) Placing physical barriers 
between the marine mammals and the subsistence hunters; and (2) That 
cannot be sufficiently mitigated by other measures to increase the 
availability of marine mammals to allow subsistence needs to be met.

    Noise and general activity during Shell's proposed drilling program 
have the potential to impact marine mammals hunted by Native Alaskans. 
In the case of cetaceans, the most common reaction to anthropogenic 
sounds (as noted previously in this document) is avoidance of the 
ensonified area. In the case of bowhead whales, this often means that 
the animals divert from their normal migratory path by several 
kilometers. Helicopter activity also has the potential to disturb 
cetaceans and pinnipeds by causing them to vacate the area. 
Additionally, general vessel presence in the vicinity of traditional 
hunting areas could negatively impact a hunt.
    In the case of subsistence hunts for bowhead whales in the Beaufort 
Sea, there could be an adverse impact on the hunt if the whales were 
deflected seaward (further from shore) in traditional hunting areas. 
The impact would be that whaling crews would have to travel greater 
distances to intercept westward migrating whales, thereby creating a 
safety hazard for whaling crews and/or limiting chances of successfully 
striking and landing bowheads.

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 2010 Camden Bay, Beaufort 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 distributed to the 
communities, subsistence user groups, NMFS, and other Federal and State 
agencies in May 2009. An updated Communications Plan was then submitted 
to NMFS as an attachment to the POC in July 2009. Shell conducted POC 
meetings throughout 2009 regarding its planned 2010 activities in both 
the Beaufort and Chukchi Seas. 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 
2010 POC and this document. For this Camden Bay drilling program, 
Shell's POC with Chukchi Sea villages primarily addresses the issue of 
transit of vessels, whereas the POC with Beaufort Sea villages 
addresses vessel transit, drilling, and associated activities. 
Communities that were consulted regarding Shell's 2010 Arctic

[[Page 20508]]

Ocean operations include: Barrow, Kaktovik, Wainwright, Kotzebue, 
Kivalina, Point Lay, and Point Hope. Attempts were made to meet 
individually with whaling captains and to hold a community meeting in 
Nuiqsut; however, after receipt of a request by the Mayor, the 
scheduled meeting was cancelled. Shell subsequently sent correspondence 
to all post office box holders in Nuiqsut on February 26, 2009, 
indicating its willingness to visit and have dialogue on the proposed 
plans.
    Beginning in early January 2009, 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 Alaska 
Eskimo Whaling Commission (AEWC), and presentations on proposed 
activities were given to the Inupiat Community of the Arctic Slope, and 
the Native Village of Barrow. A full list of POC meetings conducted by 
Shell between January and April 2009 can be found in Table 4.2-1 of 
Shell's POC. Shell has successfully completed additional POC meetings 
with several communities since submitting the Draft POC, including:
     June 1, 2009: NSB Assembly meeting;
     June 2, 2009: Point Lay meeting with village leadership;
     June 3, 2009: Kaktovik meeting with village leadership;
     June 17, 2009: Point Hope meeting with village leadership;
     August 5, 2009: NWAB Assembly meeting; and
     August 27, 2009: NSB Planning Commission meeting.
    On December 8, 2009, Shell held consultation meetings with 
representatives from the various marine mammal commissions. Prior to 
drilling in 2010, 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.
    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 2010 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 
2010 Camden Bay 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 whaling 
activities from its exploration operations, Shell will suspend drilling 
activities on August 25, 2010, prior to the start of the Kaktovik and 
Cross Island bowhead whale hunting season. The drillship and associated 
vessels will remain outside of the Camden Bay area during the hunt. 
Shell will resume drilling operations after the conclusion of the hunt 
and, depending on ice and weather conditions, continue its exploration 
activities through October 31, 2010. In addition to the adoption of 
this project timing restriction, 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 transit 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 (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);
    (2) 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 2010;
    (3) 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 2010 
exploration project. The subsistence advisor will use local knowledge 
(Traditional Knowledge) to gather data on subsistence lifestyle within 
the community and advise as to 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;
    (4) 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;
    (5) 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; and
    (6) No routine vessel traffic will traverse the subsistence area. 
Vessels within 900 ft (274 m) of marine mammals will reduce speed, 
avoid separating members from a group, and avoid multiple changes in 
direction.
    For several years, a Conflict Avoidance Agreement (CAA) has been 
negotiated between the AEWC, affected whaling captains' associations, 
and the oil and gas industry to avoid conflicts between industry 
activity and bowhead whale subsistence hunts. While the signing of a 
CAA is not a requirement to obtain an IHA, often times, the CAA

[[Page 20509]]

contains measures that help NMFS make its no unmitigable adverse impact 
determination for bowhead whales. Shell is currently reviewing the 
draft 2010 CAA and is expected to make a decision on whether or not it 
will sign the 2010 CAA prior to commencing operations this year.

Unmitigable Adverse Impact Analysis and Preliminary Determination

    NMFS has preliminarily determined that Shell's proposed Camden Bay 
exploration drilling program will not have an unmitigable adverse 
impact on the availability of species or stocks for taking for 
subsistence uses. This preliminary determination is supported by 
information contained in this document and Shell's POC. Shell has 
adopted a spatial and temporal strategy for its Camden Bay operations 
that should minimize impacts to subsistence hunters. First, Shell's 
activities will not commence until after the spring hunts have 
occurred. Additionally, Shell will traverse the Chukchi Sea far 
offshore, so as to not interfere with July hunts in the Chukchi Sea and 
will communicate with the Com Centers to notify local communities of 
any changes in the transit route. Once Shell is on location in Camden 
Bay, Beaufort Sea, whaling will not commence until late August/early 
September. Shell has agreed to cease operations on August 25 to allow 
the villages of Kaktovik and Nuiqsut to prepare for the fall bowhead 
hunts, will move the drillship and all support vessels out of the 
hunting area so that there are no physical barriers between the marine 
mammals and the hunters, and will not recommence activities until the 
close of both villages' hunts.
    Kaktovik is located 60 mi (96.6 km) east of the project area. 
Therefore, westward migrating whales would reach Kaktovik before 
reaching the area of Shell's activities or any of the ensonified zones. 
Although Cross Island and Barrow are west of Shell's drill sites, sound 
generating activities from Shell's drilling program will have ceased 
prior to the whales passing through the area. Additionally, Barrow lies 
298 mi (479.6 km) west of Shell's Camden Bay drill sites, so whalers in 
that area would not be displaced by any of Shell's activities.
    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. Sealing activities in the Colville River delta 
area occur more than 100 mi (161 km) from Shell's Camden Bay 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.
    Based on the measures described in Shell's Draft POC, the proposed 
mitigation and monitoring measures (described earlier in this 
document), and the project design itself, NMFS has determined 
preliminarily that there will not be an unmitigable adverse impact on 
subsistence uses from Shell's Camden Bay exploration drilling 
activities.

Endangered Species Act (ESA)

    There is one marine mammal species listed as endangered under the 
ESA with confirmed or possible occurrence in the proposed project area: 
The bowhead whale. NMFS' Permits, Conservation and Education Division 
has initiated 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, pursuant 
to NEPA, to determine whether or not this proposed activity may have a 
significant effect on the human environment. This analysis will be 
completed prior to the issuance or denial of the IHA.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
authorize the take of marine mammals incidental to Shell's 2010 Camden 
Bay, Beaufort Sea, Alaska, exploration drilling program, provided the 
previously mentioned mitigation, monitoring, and reporting requirements 
are incorporated.

    Dated: April 12, 2010.
James H. Lecky,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2010-8790 Filed 4-15-10; 8:45 am]
BILLING CODE 3510-22-P