[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]]
-----------------------------------------------------------------------
Part III
Department of Commerce
-----------------------------------------------------------------------
National Oceanic and Atmospheric Administration
-----------------------------------------------------------------------
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
[[Page 20482]]
-----------------------------------------------------------------------
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.
-----------------------------------------------------------------------
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