[Federal Register: May 3, 2006 (Volume 71, Number 85)]
[Notices]
[Page 26055-26069]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr03my06-52]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[I.D. 020306A]
Small Takes of Marine Mammals Incidental to Specified Activities;
Seismic Surveys in the Beaufort and Chukchi Seas off Alaska
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice of receipt of application and proposed incidental take
authorization; request for comments.
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SUMMARY: NMFS has received two applications from Shell Offshore, Inc.
and WesternGeco, Inc. (Shell) for Incidental Harassment Authorizations
(IHAs) to take small numbers of marine mammals, by harassment,
incidental to conducting a marine geophysical program, including deep
seismic surveys, on oil and gas lease blocks located on Outer
Continental Shelf (OCS) waters in the mid- and eastern-Beaufort Sea and
on pre-lease areas in the Northern Chukchi Sea. Under the Marine Mammal
Protection Act (MMPA), NMFS is requesting comments on its proposal to
issue a single IHA to Shell to take, by Level B harassment, small
numbers of several species of marine mammals between July and November,
2006 incidental to conducting seismic surveys.
DATES: Comments and information must be received no later than June 2,
2006.
ADDRESSES: Comments on the application should be addressed to the
Chief of the Permits, Conservation and Education Division, Office of
Protected Resources, National Marine Fisheries Service, 1315 East-West
Highway, Silver Spring, MD 20910-3225, or by telephoning one of the
contacts listed here. The mailbox address for providing email comments
is PR1.020306A@noaa.gov. Comments sent via e-mail, including all
attachments, must not exceed a 10-megabyte file size. A copy of the
application (containing a list of the references used in this document)
may be obtained by writing to this address or by telephoning the
contact listed here and are also available at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm#iha
.
A copy of the Minerals Management Service's (MMS) Programmatic
Environmental Assessment (PEA) is available on-line at: http://www.mms.gov/alaska/ref/pea_be.htm
.
Documents cited in this document, that are not available through
standard public library access, may be viewed, by appointment, during
regular business hours at this address.
FOR FURTHER INFORMATION CONTACT: Kenneth Hollingshead or Jolie
Harrison, Office of Protected Resources, NMFS, (301) 713-2289.
SUPPLEMENTARY INFORMATION:
Background
Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.)
direct the Secretary of Commerce to allow, upon request, the
incidental, but not intentional, taking of small numbers of marine
mammals by U.S. citizens who engage in a specified activity (other than
commercial fishing) within a specified geographical region if certain
findings are made and either regulations are issued or, if the taking
is limited to harassment, a notice of a proposed authorization is
provided to the public for review.
An authorization shall be granted if NMFS finds that the taking
will have a negligible impact on the species or stock(s) and will not
have an unmitigable adverse impact on the availability of the species
or stock(s) for subsistence uses and that 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 United States can apply for an authorization
to incidentally take small numbers of marine mammals by 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].
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
[[Page 26056]]
mammals. Within 45 days of the close of the comment period, NMFS must
either issue or deny issuance of the authorization.
Summary of Request
On November 16, 2005, NMFS received two applications from Shell for
the taking, by Level B harassment, of several species of marine mammals
incidental to conducting a marine seismic survey program during 2006 in
the mid- and eastern-Beaufort and northern Chukchi seas. The deep
seismic survey component of the program will be conducted from
WesternGeco's vessel the M/V Gilavar. Detailed specifications on this
seismic survey vessel are provided in Shell's application (Attachment A
- Seismic Survey, Overview/Description). These specifications include:
(1) complete descriptions of the number and lengths of the streamers
which form the airgun and hydrophone arrays; (2) airgun size and sound
propagation properties; and (3) additional detailed data on the M/V
Gilavar's characteristics. In summary, the M/V Gilavar will tow two
source arrays, comprising three identical subarrays each, which will be
fired alternately as the ship sails downline in the survey area. The M/
V Gilavar will tow up to 6 hydrophone streamer cables up to 5.4
kilometers (km) (3.4 mi) long. With this configuration each pass of the
Gilavar can record 12 subsurface lines spanning a swath of up to 360
meters (m; 1181 ft). The seismic data acquisition vessel will be
supported by the M/V Alex Gordon, which will serve to resupply and re-
fuel the M/V Gilavar. The M/V Alex Gordon is also capable of ice
management should that be required. The M/V Alex Gordon will not deploy
seismic acquisition gear.
Plan for Seismic Operations
It is planned that the M/V Gilavar will be in the Chukchi Sea in
early July to begin deploying the acquisition equipment. Seismic
acquisition is planned to begin on or about July 10, 2006. The
approximate areas of operations are shown in Appendix 4 in Shell's IHA
application. Acquisition will continue in the Chukchi Sea until ice
conditions permit a transit into the Beaufort Sea around early August.
Seismic acquisition is planned to continue in the Beaufort at one of
three 3-D areas until early October depending on ice conditions. These
3-D areas are shown in Appendix 5 in Shell's application. For each of
the 3-D areas, the M/V Gilavar will traverse the area multiple times
until data on the area of interest has been recorded. At the conclusion
of seismic acquisition in the Beaufort Sea, the M/V Gilavar will return
to the Chukchi Sea and resume recording data there until all seismic
lines are completed or weather prevents data collection.
The proposed Beaufort Sea deep seismic, site clearance, shallow
hazard surveys and geotechnical activities are proposed to commence in
August and continue until weather precludes further seismic work. The
timing is scheduled to avoid any conflict with the Beaufort Sea
subsistence hunting conducted by the Alaska Eskimo Whaling Commission's
(AEWC) villages.
In summary, the proposed Chukchi deep seismic survey will occur in
two phases. Phase 1 will commence sometime after June 15, 2006, as sea
ice coverage conditions allow and will continue through July to early
August, 2006. Phase 2 of the Chukchi deep seismic survey will occur
upon completion of the Beaufort Sea survey sometime after mid-October
and continue until such time as sea ice and weather conditions preclude
further work, probably sometime in mid- to late-November, 2006. Shell
plans to run approximately 5556 km (3452 mi) of surveys in the Chukchi
Sea and a similar survey length in the Beaufort Sea.
Alternatively, if ice conditions preclude seismic operations in the
Beaufort Sea, Shell proposes to continue its seismic program in the
Chukchi Sea through mid- to late-November, 2006, or approximately 5.5
months. This scenario takes into account that approximately twice as
many seismic line miles would be completed during this time in the
Chukchi Sea. Under this scenario approximately 6000 nm (6905 stat mi;
11,112 km) of seismic line miles could be completed in the Chukchi Sea.
A detailed description of the work proposed by Shell for 2006 is
contained in the two applications which are available for review (see
ADDRESSES).
Description of Marine 3-D Seismic Data Acquisition
In the seismic method, reflected sound energy produces graphic
images of seafloor and sub-seafloor features. The seismic system
consists of sources and detectors, the positions of which must be
accurately measured at all times. The sound signal comes from arrays of
towed energy sources. These energy sources store compressed air which
is released on command from the towing vessel. The released air forms a
bubble which expands and contracts in a predictable fashion, emitting
sound waves as it does so. Individual sources are configured into
arrays. These arrays have an output signal, which is more desirable
than that of a single bubble, and also serve to focus the sound output
primarily in the downward direction, which is useful for the seismic
method. This array effect also minimizes the sound emitted in the
horizontal direction.
The downward propagating sound travels to the seafloor and into the
geologic strata below the seafloor. Changes in the acoustic properties
between the various rock layers result in a portion of the sound being
reflected back toward the surface at each layer. This reflected energy
is received by detectors called hydrophones, which are housed within
submerged streamer cables which are towed behind the seismic vessel.
Data from these hydrophones are recorded to produce seismic records or
profiles. Seismic profiles often resemble geologic cross-sections along
the course traveled by the survey vessel.
Description of WesternGeco's Air-Gun Array
Shell proposes to use WesternGeco's 3147 in\3\ Bolt-Gun Array for
its 3-D seismic survey operations in the Chukchi and Beaufort Seas.
WesternGeco's source arrays are composed of 3 identically tuned Bolt-
gun sub-arrays operating at an air pressure of 2,000 psi. In general,
the signature produced by an array composed of multiple sub-arrays has
the same shape as that produced by a single sub-array while the overall
acoustic output of the array is determined by the number of sub-arrays
employed.
The gun arrangement for each of the three 1049-in\3\ sub-array is
detailed in Shell's application. As indicated in the application's
diagram, each sub-array is composed of six tuning elements; two 2-gun
clusters and four single guns. The standard configuration of a source
array for 3D surveys consists of one or more 1049-in\3\ sub-arrays.
When more than one sub-array is used, as here, the strings are lined up
parallel to each other with either 8 m or 10 m (26 or 33 ft) cross-line
separation between them. This separation was chosen so as to minimize
the areal dimensions of the array in order to approximate point source
radiation characteristics for frequencies in the nominal seismic
processing band. For the 3147 in\3\ array the overall dimensions of the
array are 15 m (49 ft) long by 16 m (52.5 ft) wide.
Shell's application provides illustrations of the time series and
amplitude spectrum for the far-field signature and the computed
acoustic emission pattern for the vertical inline and crossline planes
for the 3147 in3 array with guns at a depth of 6 m (20
[[Page 26057]]
ft). The signature for this array was first computed using GSAP,
WesternGeco's in house signature modelling software. Based on this
model, Shell estimates the sound level output radii (root-mean-squared
(rms)) for a 3147 in3 source array at a depth of 6 m (20 ft):
160 dB (rms) :: < 650 m/2133 ft
170 dB (rms) :: < 425 m/1394 ft
180 dB (rms) :: < 225 m/738 ft
190 dB (rms) :: < 120 m/394 ft.
Subsequent to submitting its application, Shell contracted with
JASCO to model sound source characteristics using a different model.
The JASCO parabolic equation model is believed by Shell and NMFS to be
superior in these waters because it accounts for bathymetry effects,
water properties, and the geoacoustic properties of seabed layers. The
JASCO-modeled radii are based on the worst case model predictions. For
this model, the proposed 180-dB and 190-dB radii are 1.5 km (0.9 mi)
and 0.5 km (0.3mi), respectively. This model will be used by Shell and
NMFS to estimate sound level isopleths and radii for rms sound level
thresholds between 120 and 190 dB at six proposed survey locations for
the proposed airgun arrays. In addition, these modeled radii estimates
will be multiplied by a safety margin of 1.5 to obtain conservative
exclusion radii for marine mammal safety until empirical sound field
verification measurements are completed within the first few days of
seismic shooting.
An explanation for the indicated sound pressure levels (SPLs) is
provided later in this document (see Impacts to Marine Mammals).
Characteristics of Airgun Pulses
Discussion of the characteristics of airgun pulses was provided in
several previous Federal Register documents (see 69 FR 31792 (June 7,
2004) or 69 FR 34996 (June 23, 2004)) and is not repeated here.
Additional information can be found in the MMS PEA. Reviewers are
encouraged to read these earlier documents for additional information.
Site Clearance Surveys
In addition to deep seismic surveys in the Beaufort Sea, Shell also
plans to conduct site clearance and shallow hazards surveys of
potential exploratory drilling locations within Shell's lease areas as
required by MMS regulations. The site clearance surveys are confined to
very small specific areas within defined OCS blocks. Shell is currently
in the process of selecting site clearance/shallow hazards and
geotechnical contractors and vessels for the site clearance/shallow
hazards surveys, and geotechnical borings. As yet unidentified vessels
will conduct these surveys contemporaneously with the deep seismic
survey program. Very small and limited geophysical survey energy
sources will be employed to measure bathymetry, topography, geo-hazards
and other seabed characteristics. The actual locations of site
clearance and shallow hazard surveys have not been definitively set as
of the date of Shell's application. That information will be supplied
to NMFS and MMS as it becomes available, but well before the
commencement of operations. The vessels conducting the site clearance
and shallow hazard surveys, and geotechnical borings will also operate
in accordance with the provisions of a Conflict Avoidance Agreement
(CAA), between the seismic industry and the AEWC and the Whaling
Captains Associations regarding times and areas in order to avoid any
possible conflict with the bowhead subsistence whale hunts by the
Kaktovik and Nuiqsut.
Offshore site clearance surveys use various geophysical methods and
tools to acquire graphic records of seafloor and sub-seafloor geologic
conditions. The data acquired and the type of investigations outlined
in this document are performed routinely for most exploratory drilling
and production platforms, submarine pipelines, port facilities, and
other offshore projects. High-resolution geophysical data such as two-
dimensional, high-resolution multi-channel seismic, medium penetration
seismic, subbottom profiler, side scan sonar, multibeam bathymetry,
magnetometer and possibly piston core soil sampling are typical types
of data acquired. These data are interpreted to define geologic and
geotechnical conditions at the site and to assess the potential
engineering significance of these conditions. The following section
provides a brief description of those instruments used for site
clearance that may impact marine mammals. Information on the data
acquisition methodology planned by Shell can be found in the Shell
application.
Geophysical Tools for Site Clearance
High-Resolution seismic profiling
Reflected sound energy, often called acoustic or seismic energy,
produces graphic images of seafloor and sub-seafloor features. These
systems transmit the acoustic energy from various sources called
transducers that are attached to the hull of the vessel or towed
astern. Part of this energy is reflected from the seafloor and from
geologic strata below the seafloor. This reflected energy is received
by the hydrophone or streamer and is recorded to produce seismic
records or profiles. Seismic profiles often resemble geologic cross-
sections along the course traveled by the survey vessel.
In most Beaufort Sea site surveys, Shell will operate several high-
resolution profiling systems simultaneously to obtain detailed records
of seafloor and near seafloor conditions. A typical survey would
include data acquisition using a shallow penetration profiler or
subbottom profiler (1 - 12.0 kHz, typically 3.5 kHz), medium
penetration system or boomer/sparker/ airgun (400-800 Hz) and a deep
penetrating hi-res multi-channel seismic system (20-300 Hz) not to be
confused with the deep seismic used for hydrocarbon exploration. These
profiling systems complement each other since each system achieves
different degrees of resolution and depths of sub-seafloor
penetrations.
Side Scan Sonar
Unlike seismic profiling systems, which produce a vertical profile
along the vessel's path, side scan sonar systems provide graphic
records that show two-dimensional (map) views of seafloor topography
and of objects on the seafloor. The sonar images provide a swath
display/record covering an area on the seafloor up to several hundred
feet on both sides of the survey trackline. The side scan sonar
transmits very high-frequency acoustic signals (100 - 410 kHz) and
records the reflected energy from the seafloor. Signals reflected from
the seafloor are displayed on a continuous record produce by a two-
channel recorder. Reflected signals normally appear as dark areas on
the record whereas shadows behind objects appear as light or white
areas. The intensity and distribution of reflections displayed on the
sonar image depend on the composition and surface texture of the
reflecting features, on their size, and on their orientation with
respect to the transducers in the towfish. Line spacing and display
range are designed to ensure 100 percent coverage of the proposed
survey area in the prime survey line direction, with additional tie-
lines acquired in an orthogonal direction.
Side scan sonar data are useful for mapping areas of boulders, rock
outcrops, and other areas of rough seafloor, and for determining the
location and trends of seafloor scarps and ice gouges. These data are
also used to locate shipwrecks, pipelines, and other objects on the
seafloor.
[[Page 26058]]
Multi-beam Bathymetry
Multi-beam bathymetric systems are either hull mounted or towed
astern of the survey vessel. The system transmits acoustic signals
(200-500 kHz) from multiple projectors propagating to either side of
the vessel at angles that vary from vertical to near horizontal. The
locations of the soundings cover a swath whose width may be equal to
many times the waterdepth. By adjusting the spacing of the survey
tracklines such that adjacent swaths are overlapping, Shell obtains
depth information for 100 percent of the bottom in the survey area. The
time it takes to receive the signals as well as signal intensity,
position, and other characteristics for echoes received across the
swath are used to calculate depth of each individual beam transmitted
across the swath.
Acoustic systems similar to the ones proposed for use by Shell have
been described in detail by NMFS previously (see 66 FR 40996, August 6,
2001; 70 FR 13466, March 21, 2005). NMFS encourages readers to refer to
these documents for additional information on these systems.
Description of Habitat and Marine Mammals Affected by the Activity
A detailed description of the Beaufort and Chukchi sea ecosystems
and their associated marine mammals can be found in several documents
(Corps of Engineers, 1999; NMFS, 1999; Minerals Management Service
(MMS), 2006, 1996 and 1992) and does not need to be repeated here.
Marine Mammals
The Beaufort/Chukchi Seas support a diverse assemblage of marine
mammals, including bowhead whales (Balaena mysticetus), gray whales
(Eschrichtius robustus), beluga whales (Delphinapterus leucas), killer
whales (Orcinus orca), harbor porpoise (Phocoena phocoena), ringed
seals (Phoca hispida), spotted seals (Phoca largha), bearded seals
(Erignathus barbatus), walrus (Odobenus rosmarus) and polar bears
(Ursus maritimus). These latter two species are under the jurisdiction
of the U.S. Fish and Wildlife Service (USFWS) and are not discussed
further in this document. Descriptions of the biology and distribution
of the marine mammal species under NMFS' jurisdiction can be found in
Shell's application, MMS' PEA, and several other documents (Corps of
Engineers, 1999; Lentfer, 1988; MMS, 1992, 1996; Hill et al., 1999).
Information on these species can be found in the NMFS Stock Assessment
Reports. The Alaska Stock Assessment Report is available at: http://www.nmfs.noaa.gov/pr/readingrm/MMSARS/sar2003akfinal.pdf.
Updated
species reports are available at: http://www.nmfs.noaa.gov/pr/readingrm/MMSARS/2005alaskasummarySARs.pdf.
Please refer to those
documents for information on these species.
Potential Effects of Seismic Surveys on Marine Mammals
Disturbance by seismic noise is the principal means of taking by
this activity. Support vessels and aircraft may provide a potential
secondary source of noise. The physical presence of vessels and
aircraft could also lead to non-acoustic effects on marine mammals
involving visual or other cues.
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., 1995):
(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;
(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 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.
Effects of Seismic Surveys on Marine Mammals
Shell (2005) states that the only anticipated impacts to marine
mammals associated with noise propagation from vessel movement, seismic
airgun operations, and seabed profiling and coring work would be the
temporary and short term displacement of seals and whales from within
ensonified zones produced by such noise sources. In the case of bowhead
whales, that displacement might well take the form of a deflection of
the swim paths of migrating bowheads away from (seaward of) received
noise levels greater than 160 db (Richardson et al., 1999). The cited
and other studies conducted to test the hypothesis of the deflection
response of bowheads have determined that bowheads return to the swim
paths they were following at relatively short distances after their
exposure to the received sounds. Shell believes that there is no
evidence that bowheads so exposed have incurred injury to their
auditory mechanisms. Additionally, Shell cites Richardson and Thomson
[eds]. (2002) that there is no conclusive evidence that exposure to
sounds exceeding 160 db have displaced bowheads from feeding activity.
NMFS notes that results from the 1996-1998 BP and Western
Geophysical seismic monitoring programs in the Beaufort Sea indicate
that most fall migrating bowheads deflected seaward to avoid an area
within about 20 km (12.4 mi) of an active nearshore seismic operation,
with the exception of a few closer sightings when there was an island
or very shallow water between the seismic operations and the whales
(Miller et al., 1998, 1999). The available data do not provide an
unequivocal estimate of the distance (and received
[[Page 26059]]
sound levels) at which approaching bowheads begin to deflect, but this
may be on the order of 35 km (21.7 mi). It is also uncertain how far
beyond (west of) the seismic operation the seaward deflection persists
(Miller et al., 1999). Although very few bowheads approached within 20
km (12.4 mi) of the operating seismic vessel, the number of bowheads
sighted within that area returned to normal within 12-24 hours after
the airgun operations ended (Miller et al., 1999).
Although NMFS believes that some limited masking of low-frequency
sounds (e.g., whale calls) is a possibility during seismic surveys, the
intermittent nature of seismic source pulses (1 second in duration
every 16 to 24 seconds (i.e., less than 7 percent duty cycle)) will
limit the extent of masking. Bowhead whales are known to continue
calling in the presence of seismic survey sounds, and their calls can
be heard between seismic pulses (Greene et al., 1999, Richardson et
al., 1986). Masking effects are expected to be absent in the case of
belugas, given that sounds important to them are predominantly at much
higher frequencies than are airgun sounds (Western Geophysical, 2000).
Hearing damage is not expected to occur during the Shell seismic
survey project. It is not positively known whether the hearing systems
of marine mammals very close to an airgun would be at risk of temporary
or permanent hearing impairment, but TTS is a theoretical possibility
for animals within a few hundred meters of the source (Richardson et
al., 1995). However, planned monitoring and mitigation measures
(described later in this document) are designed to avoid sudden onsets
of seismic pulses at full power, to detect marine mammals occurring
near the array, and to avoid exposing them to sound pulses that have
any possibility of causing hearing impairment. Moreover, as mentioned
previously, bowhead whales avoid an area many kilometers in radius
around ongoing seismic operations, precluding any possibility of
hearing damage.
When the received levels of noise exceed some behavioral reaction
threshold, cetaceans will show disturbance reactions. The levels,
frequencies, and types of noise that will elicit a response vary
between and within species, individuals, locations, and seasons.
Behavioral changes may be subtle alterations in surface, respiration,
and dive cycles. More conspicuous responses include changes in activity
or aerial displays, movement away from the sound source, or complete
avoidance of the area. The reaction threshold and degree of response
are related to the activity of the animal at the time of the
disturbance. Whales engaged in active behaviors, such as feeding,
socializing, or mating, are less likely than resting animals to show
overt behavioral reactions, unless the disturbance is directly
threatening.
The following summaries are provided by NMFS to facilitate
understanding of our knowledge of impulsive noise impacts on the
principal marine mammal species that are expected to be affected.
Bowhead Whales
Seismic pulses are known to cause strong avoidance reactions by
many of the bowhead whales occurring within a distance of a few
kilometers, including changes in surfacing, respiration and dive
cycles, and may sometimes cause avoidance or other changes in bowhead
behavior at considerably greater distances (Richardson et al., 1995;
Rexford, 1996; MMS, 1997). Studies conducted prior to 1996 (Reeves et
al., 1984, Fraker et al., 1985, Richardson et al., 1986, Ljungblad et
al., 1988) have reported that, when an operating seismic vessel
approaches within a few kilometers, most bowhead whales exhibit strong
avoidance behavior and changes in surfacing, respiration, and dive
cycles. In these studies, bowheads exposed to seismic pulses from
vessels more than 7.5 km (4.7 mi) away rarely showed observable
avoidance of the vessel, but their surface, respiration, and dive
cycles appeared altered in a manner similar to that observed in whales
exposed at a closer distance (Western Geophysical, 2000). In three
studies of bowhead whales and one of gray whales during this period,
surfacing-dive cycles were unusually rapid in the presence of seismic
noise, with fewer breaths per surfacing and longer intervals between
breaths (Richardson et al., 1986; Koski and Johnson, 1987; Ljungblad et
al., 1988; Malme et al., 1988). This pattern of subtle effects was
evident among bowheads 6 km to at least 73 km (3.7 to 45.3 mi) from
seismic vessels. However, in the pre-1996 studies, active avoidance
usually was not apparent unless the seismic vessel was closer than
about 6 to 8 km (3.7 to 5.0 mi)(Western Geophysical, 2000).
Results from the 1996-1998 BP and Western Geophysical seismic
program monitoring in the Beaufort Sea indicate that most migrating
bowheads deflected seaward to avoid an area within about 20 km (12.4
mi) of an active nearshore seismic operation, with the exception of a
few closer sightings when there was an island or very shallow water
between the seismic operations and the whales (Miller et al., 1998,
1999). The available data do not provide an unequivocal estimate of the
distance at which approaching bowheads begin to deflect, but this may
be on the order of 35 km (21.7 mi). It is also uncertain how far beyond
(west of) the seismic operation the seaward deflection persists (Miller
et al., 1999). Although very few bowheads approached within 20 km (12.4
mi) of the operating seismic vessel, the number of bowheads sighted
within that area returned to normal within 12-24 hours after the airgun
operations ended (Miller et al., 1999).
Inupiat whalers believe that migrating bowheads are sometimes
displaced at distances considerably greater than suggested by pre-1996
scientific studies (Rexford, 1996) previously mentioned in this
document. Also, whalers believe that avoidance effects can extend out
to distances on the order of 30 miles (48.3 km), and that bowheads
exposed to seismic also are ``skittish'' and more difficult to
approach. The ``skittish'' behavior may be related to the observed
subtle changes in the behavior of bowheads exposed to seismic pulses
from distant seismic vessels (Richardson et al., 1986).
Gray Whales
The reactions of gray whales to seismic pulses are similar to those
documented for bowheads during the 1980s. Migrating gray whales along
the California coast were noted to slow their speed of swimming, turn
away from seismic noise sources, and increase their respiration rates.
Malme et al. (1983, 1984, 1988) concluded that approximately 50 percent
of the migrating gray whales showed avoidance when the average received
pulse level was 170 dB (re 1 microPa). By some behavioral measures,
clear effects were evident at average pulse levels of 160+dB; less
consistent results were suspected at levels of 140-160 dB. Recent
research on migrating gray whales showed responses similar to those
observed in the earlier research when the source was moored in the
migration corridor 2 km (1.2 mi) from shore. However, when the source
was placed offshore (4 km (2.5 mi) from shore) of the migration
corridor, the avoidance response was not evident on track plots (Tyack
and Clark, 1998).
Beluga
The beluga is the only species of toothed whale (Odontoceti)
expected to be encountered in the Beaufort Sea. Belugas have poor
hearing thresholds at frequencies below 200 Hz, where most of the
energy from airgun arrays is concentrated. Their thresholds at these
[[Page 26060]]
frequencies (as measured in a captive situation), are 125 dB re 1
microPa or more depending upon frequency (Johnson et al., 1989).
Although not expected to be significantly affected by the noise, given
the high source levels of seismic pulses, airgun sounds sometimes may
be audible to beluga at distances of 100 km (62.1 mi)(Richardson and
Wursig, 1997), and perhaps further if actual low-frequency hearing
thresholds in the open sea are better than those measured in captivity
(Western Geophysical, 2000). The reaction distance for beluga, although
presently unknown, is expected to be less than that for bowheads, given
the presumed poorer sensitivity of belugas than that of bowheads for
low-frequency sounds (Western Geophysical, 2000).
Ringed, Largha and Bearded Seals
No detailed studies of reactions by seals to noise from open water
seismic exploration have been published (Richardson et al., 1995).
However, there are some data on the reactions of seals to various types
of impulsive sounds (LGL and Greeneridge, 1997, 1998, 1999a; J. Parsons
as quoted in Greene, et al. 1985; Anon., 1975; Mate and Harvey, 1985).
These studies indicate that ice seals typically either tolerate or
habituate to seismic noise produced from open water sources.
Underwater audiograms have been obtained using behavioral methods
for three species of phocinid seals, ringed, harbor, and harp seals
(Pagophilus groenlandicus). These audiograms were reviewed in
Richardson et al. (1995) and Kastak and Schusterman (1998). Below 30-50
kHz, the hearing threshold of phocinids is essentially flat, down to at
There are few data on hearing sensitivity of phocinid seals below 1
kHz. NMFS considers harbor seals to have a hearing threshold of 70-85
dB at 1 kHz (60 FR 53753, October 17, 1995), and recent measurements
for a harbor seal indicate that, below 1 kHz, its thresholds
and Schusterman, 1998).
While no detailed studies of reactions of seals from open-water
seismic exploration have been published (Richardson et al., 1991,
1995), some data are available on the reactions of seals to various
types of impulsive sounds (see LGL and Greeneridge, 1997, 1998, 1999a;
Thompson et al. 1998). These references indicate that it is unlikely
that pinnipeds would be harassed or injured by low frequency sounds
from a seismic source unless they were within relatively close
proximity of the seismic array. For permanent injury, pinnipeds would
likely need to remain in the high-noise field for extended periods of
time. Existing evidence also suggests that, while seals may be capable
of hearing sounds from seismic arrays, they appear to tolerate intense
pulsatile sounds without known effect once they learn that there is no
danger associated with the noise (see, for example, NMFS/Washington
Department of Wildlife, 1995). In addition, they will apparently not
abandon feeding or breeding areas due to exposure to these noise
sources (Richardson et al., 1991) and may habituate to certain noises
over time.
Numbers of Marine Mammals Expected to Be Exposed to Seismic Noise
The methodology used by Shell to estimate incidental take by Level
B harassment, at sound pressure levels at 160 dB or above, by seismic
and the numbers of marine mammals that might be affected during the
proposed seismic acquisition area in the Chukchi and Beaufort seas are
presented in the application. Subsequent to submission of that
application, Shell decided to provide more conservative estimates of
potential marine mammal exposures by using the JASCO model. Therefore,
Tables 1 and 2 provide exposure calculations for both sets of
calculations. NMFS proposes to use the more conservative estimates of
noise exposure to determine impacts to marine mammals.
[[Page 26061]]
[GRAPHIC] [TIFF OMITTED] TN03MY06.000
[[Page 26062]]
[GRAPHIC] [TIFF OMITTED] TN03MY06.001
The density estimates for the species covered under this IHA are
based on the estimates developed by LGL (2005). The LGL density
estimates are based on the original data from Moore et al. (2000) on
summering bowhead, gray, and beluga
[[Page 26063]]
whales in the Beaufort and Chukchi Seas, and relevant studies on ringed
seal estimates, including Stirling et al. (1982) and Kingsley (1986).
In its application, Shell provides estimates of the number of
potential ``exposures'' to sound levels greater than 160 dB re 1
microPa (rms) and greater than 170 dB. Shell states that while the 160-
dB criterion is applied for estimating Level B harassment of all
species of cetaceans and pinnipeds, Shell believes that a 170-dB
criterion should be considered appropriate for estimating Level B
harassment of delphinid cetaceans and pinnipeds, which tend to be less
responsive, whereas the 160-dB criterion is considered appropriate for
other cetaceans (LGL, 2005). However, NMFS has noted in the past that
there is no empirical evidence to indicate that some delphinid species
do not respond at the lower level (i.e., 160 dB). As a result, NMFS
proposes to use the 160-dB isopleth to estimate the numbers of marine
mammals that may be taken by Level B harassment.
The estimates in Tables 1 and 2 are based on marine mammal
exposures to 160 dB (and greater) from either approximately 5,556 km
(3452 mi) of seismic surveys in three distinct areas of the eastern-
and mid-Beaufort Sea and a similar level of effort in the Chukchi Sea
or approximately 11,112 km (6905 mi) only in the Chukchi Sea if seismic
work in the Beaufort Sea is not undertaken. These latter calculations
are provided in the last column of Table 2.
There will be no site clearance work performed for the seismic
activities in the Chukchi Sea, therefore, potential taking estimates
only include noise disturbance from the use of airguns. It is assumed
that, during simultaneous operations of those additional sound sources
and the airgun(s), any marine mammals close enough to be affected by
the sonars or pinger would already be affected by the airgun(s).
Exposure Calculations for Cetaceans and Pinnipeds
The number of exposures of a particular species to sound levels
between 160 dB and 180 dB re 1 microPa (rms) was calculated by
multiplying: (1) the expected species density (i.e., average and
maximum), as shown in Tables 1 and 2; (2) the anticipated total line-
kilometers of operations with the three 1,049-in\3\ subarrays (i.e.,
5556 km (3452 mi)); and (3) the cross-track distances within which
received sound levels are predicted to be between 160 and 180 dB
(Figure 6-1 and Table 6-3 in the Shell application).
Chukchi Sea
Shell estimates that the average and maximum numbers of bowhead
whales that may be exposed to noise levels of 160 dB or greater are 808
and 3226, respectively. However, according to Shell, the proposed
seismic activities would occur when bowheads are widely distributed and
would be expected to occur in very low numbers within the seismic
activity area. Therefore, based on the 160-dB threshold criterion, the
number of bowhead whales that may be exposed to sounds at or greater
than 160 dB re 1 microPa (rms) represent a small percent of the
estimated population within the Beaufort and Chukchi Seas.
Gray and beluga whales also have the potential for exposure,
particularly near Area 3. The average and maximum estimates of the
number of exposures at or greater than 160 dB are revised as 284 and
1128 for gray whales, 214 and 851 for beluga whales, 10 for killer
whales, and 10 and 13 for harbor porpoises.
While no reliable abundance numbers currently exist for ringed,
spotted, and bearded seals for the Chukchi Sea, however, the potential
number of exposures would be a very small fraction of earlier abundance
estimates as shown in Table 2.
For both cetaceans and pinnipeds likely to be encountered within
the Chukchi and Beaufort Sea activity areas, the short-term exposures
to airgun sounds are not expected to result in any long-term negative
consequences for the individuals or their populations. Furthermore, the
estimated number of animals potentially exposed and requested under an
IHA, will be likely be much less for some species (e.g., bowhead whale)
because of the period of seismic acquisition, and the survey and
mitigation plan which contains efforts to further avoid take.
Beaufort Sea
As indicated in Table 1 in this document, the estimated average and
maximum numbers for bowhead whales at 160 dB or greater are 395 and
1579, respectively. However, as stated earlier, proposed activities
would occur mainly when bowheads are not present in the area or in very
low numbers.
Gray and beluga whales also have the potential for exposure,
particularly near seismic survey area 3. The average and maximum
estimates of the number of exposures for gray whales are 278 and 1104,
and 210 and 833 for beluga whales.
Ringed seals would be the most prevalent marine mammal species
encountered at each of the three proposed seismic acquisition areas,
and would account for most of the marine mammals that might be exposed
to seismic sounds equal to or greater than 160 dB. Potential exposure
estimates for pinnipeds in the Beaufort Sea are shown in Table 1.
However, as Moulton and Lawson (2002) indicated that most pinnipeds
exposed to seismic sounds lower than 170 dB do not visibly react,
pinnipeds are not likely to react to seismic sounds unless they are
greater than 170 dB re 1 microPa (rms). As a result, NMFS believes that
these exposure estimates are very conservative. Spotted and bearded
seals may be encountered in much small numbers than ringed seals, but
also have the potential for some minor exposure.
Finally, if Shell does not conduct seismic survey work in the
Beaufort Sea in 2006, and implements scenario 2 as mentioned
previously, Shell estimates that additional sound exposures would occur
in the Chukchi Sea. These estimates are provided in the last column of
Table 2.
Potential Impact of the Activity on the Affected Species or Stocks
According to Shell, the only anticipated impacts to marine mammals
associated with noise propagation from vessel movement, seismic airgun
operations and seabed profiling and coring work (in the Beaufort Sea)
would be the temporary and short term displacement of seals and whales
from within ensonified zones produced by such noise sources. Any
impacts on the whale and seal populations of the Chukchi Sea seismic
acquisition activity area are believed to be short term and transitory
arising from the temporary displacement of individuals or small groups
from locations they may occupy at the times they are exposed to seismic
sounds at the 160-190 db received levels. In the case of bowhead whales
that displacement might well take the form of a deflection of the swim
paths of migrating bowheads away from (seaward of) received noise
levels less than 160 db (Richardson et al., 1999). The cited and other
studies conducted to test the hypothesis of the deflection response of
bowheads have determined that bowheads return to the swim paths they
were following at relatively short distances after their exposure to
the received sounds. There is no evidence that bowheads so exposed have
incurred injury to their auditory mechanisms. Additionally, there is no
conclusive evidence that exposure to sounds exceeding 160 db have
displaced bowheads from feeding activity (Richardson and Thomson [eds],
2002). As noted previously, it is highly unlikely that animals will be
exposed to
[[Page 26064]]
sounds of such intensity and duration as to physically damage their
auditory mechanisms.
There is no evidence that seals are more than temporarily displaced
from ensonified zones and no evidence that seals have experienced
physical damage to their auditory mechanisms even within ensonified
zones.
Potential Impact On Habitat
Shell states that the proposed seismic activities will not result
in any permanent impact on habitats used by marine mammals, or to their
prey sources. Seismic activities will occur during the time of year
when bowhead whales are widely distributed and would be expected to
occur in very low numbers within the seismic activity area (mid- to
late-June through July and again from mid-October through November).
The northeastern-most of the recurring feeding areas is in the
northeastern Chukchi Sea southwest of Barrow. Any effects would be
temporary and of short duration at any one place. The primary potential
impacts to marine mammals associated with elevated sound levels from
the proposed airguns were discussed previously in this document.
A broad discussion on the various types of potential effects of
exposure to seismic on fish and invertebrates can be found in LGL
(2005; University of Alaska-Fairbanks Seismic Survey across Arctic
Ocean at http://www.nmfs.noaa.gov/pr/permits/incidental.htm#iha), and
includes a summary of direct mortality (pathological/ physiological)
and indirect (behavioral) effects.
Mortality to fish, fish eggs and larvae from seismic energy sources
would be expected within a few meters (0.5 to 3 m (1.6 to 9.8 ft)) from
the seismic source. Direct mortality within 48 hours has been observed
in cod and plaice that were subjected to seismic pulses two meters from
the source (Matishov, 1992), however other studies did not report any
fish kills from seismic source exposure (La Bella et al., 1996; IMG,
2002; Hassel et al., 2003). To date, fish mortalities associated with
normal seismic operations are thought to be slight. Saetre and Ona
(1996) modeled a worst-case mathematical approach on the effects of
seismic energy on fish eggs and larvae, and concluded that mortality
rates caused by exposure to seismic are so low compared to natural
mortality that issues relating to stock recruitment should be regarded
as insignificant.
Limited studies on physiological effects on marine fish and
invertebrates to acoustic stress have been conducted. No significant
increases in physiological stress from seismic energy were detected for
various fish, squid, and cuttlefish (McCauley et al., 2000) or in male
snow crabs (Christian et al., 2003). Behavioral changes in fish
associated with seismic exposures are expected to be minor at best.
Because only a small portion of the available foraging habitat would be
subjected to seismic pulses at a given time, fish would be expected to
return to the area of disturbance anywhere from 15-30 minutes (McCauley
et al., 2000) to several days (Engas et al., 1996).
Available data indicate that mortality and behavioral changes do
occur within very close range to the seismic source, however, the
proposed seismic acquisition activities in the Chukchi and Beaufort
seas are predicted by Shell to have a negligible effect to the prey
resource of the various life stages of fish and invertebrates available
to marine mammals occurring during the project's duration.
The total footprint of the proposed seismic survey area covers
approximately 378,000 acres in the Chukchi Sea and 717,000 acres in the
Beaufort Sea. The effects of the planned seismic activity at each of
the seismic locations on marine mammal habitats and food resources are
expected to be negligible, as described. It is estimated that only a
small portion of the animals utilizing the areas of the proposed
activities would be temporarily displaced.
During the period of seismic acquisition in the Chukchi Sea (mid-
June through July, and again in early- to mid-October through November,
2006), most marine mammals would be dispersed throughout the area. The
peak of the west- and south-bound bowhead whale migration through the
Chukchi Sea typically occurs in October, and efforts to reduce
potential impacts to subsistence hunting during this time will be
addressed with the actual start of the migration and with the whaling
communities. The timing of seismic activities in the Chukchi Sea will
take place when the whales are widely distributed and would be expected
to occur in very low numbers within the seismic activity area. Starting
in late August bowheads may travel in proximity to the aforementioned
activity area and hear sounds from vessel traffic and seismic
activities, of which some might be displaced seaward by the planned
activities. The numbers of cetaceans and pinnipeds subject to
displacement are small in relation to abundance estimates for the
mammals covered under this proposed IHA.
In addition, feeding does not appear to be an important activity by
bowheads migrating through the Chukchi Sea or the eastern and central
part of the Alaskan Beaufort Sea in most years (Shell, 2005). Sightings
of bowhead whales occur in the summer near Barrow (Moore and DeMaster,
2000) and there are suggestions that certain areas near Barrow are
important feeding grounds. In addition, a few bowheads can be found in
the Chukchi and Bering Seas during the summer and Rugh et al. (2003)
suggest that this may be an expansion of the western Arctic stock,
although more research is needed. In the absence of important feeding
areas, the potential diversion of a small number of bowheads away from
seismic activities is not expected to have any significant or long-term
consequences for individual bowheads or their population. As a result,
Shell believes the proposed activities are not expected to have any
habitat-related effects that would produce long-term effects to marine
mammals or their habitat due to the limited extent of the acquisition
areas and timing of the activities.
Effects of Seismic Noise and Other Activities on the Availability of
Marine Mammals for Subsistence Uses
The disturbance and potential displacement of marine mammals by
sounds from seismic activities are the principal concerns related to
subsistence use of the area. The harvest of marine mammals (mainly
bowhead whales, but also ringed and bearded seals) is central to the
culture and subsistence economies of the coastal North Slope and
Western Alaskan communities. In particular, if migrating bowhead whales
are displaced farther offshore by elevated noise levels, the harvest of
these whales could be more difficult and dangerous for hunters. The
harvest could also be affected if bowheads become more skittish when
exposed to seismic noise. Hunters related how whales also appear
``angry'' due to seismic noise, making whaling more dangerous.
In the Chukchi Sea, Shell seismic work should not have significant
adverse impacts on the availability of the whale species for
subsistence uses. The whale species normally taken by Inupiat hunters
are the bowhead and belugas. Shell's Chukchi seismic operations will
not begin until after July 1, 2006 at which time the majority of
bowheads will have migrated to their summer feeding areas in Canada. In
the event any bowheads remain in the northeastern Chukchi Sea after
July 1, they are not normally hunted after this date until the return
migration occurs
[[Page 26065]]
around late September when a fall hunt by Barrow whalers takes place.
In the past few years, a small number of bowheads have also been taken
by coastal villages along the Chukchi coast. Seismic operations for
phase two of the Chukchi program will be timed and located so as to
avoid any possible conflict with the Barrow fall whaling, and specific
provisions governing the timing and location matters addressed here
will be incorporated in the CAA established between Shell and
WesternGeco, the AEWC, and the Barrow Whaling Captains Association.
Beluga whales may also be taken sporadically for subsistence needs
by coastal villages, but traditionally are taken in small numbers very
near the coast. As the seismic surveys will be conducted at least 12
miles (25 km) offshore, impacts to subsistence uses of bowheads are not
anticipated. However, Shell plans to establish ``communication
stations'' in the villages to monitoring impacts. Gray whales, which
will be abundant in the northern Chukchi Sea from spring through
autumn, are not taken by subsistence hunters.
The various pinniped species, including walrus, are all taken by
subsistence hunters of the Chukchi villages (Barrow, Wainwright, Pt
Lay, Pt Hope). The planned seismic operations will not adversely affect
the usual open-water locations of these species and no haul-out areas
will be encountered (with the possible exception of the polar ice front
used by walrus, which is under the jurisdiction of the USFWS). However,
most seismic operations will take place sufficiently distant from
nearshore traditional beluga, seal, and walrus hunting areas such that
no unmitigable adverse impacts are anticipated.
In the Beaufort Sea, there could be an adverse impact on the
Inupiat bowhead subsistence hunt if the whales were deflected seaward
(further from shore) in traditional hunting areas. The impact would be
that whaling crews would necessarily be forced 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. This potential impact will be mitigated
by application of the procedures established in the CAA between the
seismic operators and the AEWC and the whaling captains' associations
of Kaktovik, Nuiqsut and Barrow. The times and locations of seismic and
other noise producing sources will be curtailed during times of active
scouting and whaling within the traditional subsistence hunting areas
of the three potentially affected communities. (Shell, 2005).
Plan of Cooperation
Regulations at 50 CFR 216.104(a)(12) require IHA applicants for
activities that take place in Arctic waters to provide a plan of
cooperation (POC) or information that identifies what measures have
been taken and/or will be taken to minimize any adverse effects on the
availability of marine mammals for subsistence uses. Shell's POC notes
that negotiations were initiated beginning in summer of 2005 with the
AEWC to create a CAA between Shell and WesternGeco for 2006, and the
subsistence hunting communities of Barrow, Nuiqsut, and Kaktovik. The
CAA will cover both the proposed Beaufort Sea seismic program
(including deep seismic, site clearance, shallow hazard surveys and a
geotechnical seabed coring program) and the Chukchi Sea deep seismic
survey. Meetings between Shell and the AEWC began in October, 2005 with
representatives of the North Slope Borough also present in Fairbanks
during the annual meeting of the Alaska Federation of Natives.
Additional meetings were held this spring.
Shell anticipates signing the CAA sometime this spring. The CAA
will incorporate all appropriate measures and procedures regarding the
timing and areas of Shell's planned activities (i.e., times and places
where seismic operations will be curtailed or moved in order to avoid
potential conflicts with active subsistence whaling and sealing);
communications system between operator's vessels and whaling and
hunting crews (i.e., the communications center will be located in
Deadhorse with links to Kaktovik, Nuiqsut, Cross Island, and Barrow);
provision for marine mammal observers/Inupiat communicators aboard all
project vessels; conflict resolution procedures; and provisions for
rendering emergency assistance to subsistence hunting crews.
If requested, post-season meetings will also be held to assess the
effectiveness of the 2006 CAA, to address how well conflicts (if any)
were resolved; and to receive recommendations on any changes (if any)
might be needed in the implementation of future CAAs. It is anticipated
that a final draft of the 2006 CAA for the Beaufort and Chukchi Seas
will be available for consideration and review by NMFS and the MMS by
late spring.
Proposed Mitigation Measures
Shell has proposed five main mitigation measures: (1) The timing
and locations for active seismic acquisition work will be scheduled to
curtail operations when whaling captains inform the operator that they
are scouting or hunting within traditional hunting areas; (2) the
configuration of airguns in a manner that directs energy primarily down
to the seabed thus decreasing the range of horizontal spreading of
seismic noise; (3) the use of a seismic energy source which is as small
as possible while still accomplishing the geophysical objectives; (4)
the use of ramp-up and soft start methods of initiating seismic
operations which is intended to alert any marine mammals either within
or approaching an operating airgun array so that they may swim away
from the source; and (5) the curtailment of active seismic work when
the marine mammal observers (MMOs) visually sight (from shipboard or
aerially) the presence of marine mammals within identified ensonified
zones. Details of the proposed mitigation measures follow:
Seasonal Restrictions: Shell has proposed to take all practicable
measures to complete seismic operations as early as possible and to
vacate areas within close proximity of subsistence bowhead hunting
areas during periods of hunting activity. During periods of hunting
activity, seismic operations will be moved to areas remote from hunting
operations or ceased for a period. From August 15 until the end of the
bowhead hunting season (or until the end of seismic operations in the
Beaufort Sea) special monitoring and mitigation/mitigation measures
will be adopted (i.e., aerial surveys). Given the potential for
diversion offshore, re-initiation of seismic operations within
identified hunting areas will proceed only after the affected
village(s) has acquired at least two whales or ceased hunting
activities and only with close coordination with representatives of the
whaling captains. All reasonable efforts will be made to avoid
disruption of the hunt or deflection of migrating bowheads in hunting
areas.
Aerial Surveys: Shell proposes to conduct aerial surveys of the
Beaufort Sea regional distribution and abundance of marine mammals with
special attention to bowhead whales in 2006 prior to the initiation of
the seismic survey starts and periodically during and after the survey.
The objectives of the Beaufort Sea aerial surveys are to:
(a) Provide real-time or near real-time information that can be
used (if appropriate) to alter the survey's starting point and survey
line sequence based on the actual distribution of whales in the
[[Page 26066]]
area immediately prior to and during surveys (see below),
(b) Document the numbers of whales in the general area and, at
least theoretically, exposed to noise from seismic survey and their
responses to the surveys (if detectable), and
(c) Conduct aerial surveys only when they can be carried out in a
safe manner and during periods of good visibility where there is
sufficient probability of detecting bowhead whales and other marine
mammals.
Beginning at least 3 days prior to the beginning of seismic surveys
in the Beaufort Sea, aerial surveys will be conducted on a daily basis,
when practicable given weather and visibility conditions.
Aerial surveys conducted during the bowhead whaling season will be
coordinated with whaling efforts, such that airplanes operating in
close proximity to whalers can take action, e.g. flying at higher
altitudes, to reduce the potential to impact the hunt.
Generally, the flight plan and coverage of the aerial survey will
be conducted following established standards and methodologies, as
described above, with particular reference to MMS Bowhead Whale Aerial
Survey Program (BWASP) procedures. Specific details of the flight
pattern and coverage will be fully developed in an aerial flight
operations plan but will be subject to operation changes as needed to
provide effective coverage during field operations.
Airgun Arrays: For the proposed seismic survey, Shell proposes to:
(a) Configure the airgun array to maximize the proportion of the
energy that is directed downward and to minimize horizontal sound
propagation. In particular, closely spaced airguns whose overall
radiation pattern is nearly omni-directional will be avoided. The size
of the airgun arrays, as measured by the source level, will not be any
larger than required to meet the technical objectives for the seismic
survey.
(b) Utilize pre-initiation modeling, based upon anticipated sound
propagation characteristics of the array, to establish anticipated
impact zones of 180 dB and 190 dB.
(c) Conduct field sound propagation assessments at the initiation
of the field season and 180 dB and 190 dB zones adjusted accordingly.
Ramp-up (soft-start): For the proposed seismic survey, Shell
proposes to implement the following 'soft start' procedures:
(a) The seismic operator will ramp-up airguns slowly over a period
of 20 minutes each time shooting begins or whenever the, shut-down
period has been greater than 10 minutes. 'Soft starts' will follow
every interruption of the airgun array firing that is greater than 10
minutes, most importantly if the survey is discontinued until marine
mammals leave the safety zone. The seismic operator and MMOs will
maintain records of the times when ramp-ups start, and when the airgun
array reaches full power.
(b) During periods of turn around and transit between seismic
transects, one airgun will remain operational. Through use of this
approach, seismic operations can resume upon entry to a new transect
without full ramp up. While it is routine to ramp up from a single gun
firing to full array operation, operation of a single gun allows
starting during poor visibility and ramp up without a period of static
visual observation.
(c) If shut down occurs, ramp-up will begin only following a
minimum of a 30-min period of observation of the prescribed safety zone
to assure that no marine mammals are present. However, if the MMOs were
on-duty prior to the shut-down, and continued their observations during
the shut-down, then an additional 30-min period of observation prior to
ramp-up is not necessary. Ramp-up procedures will be followed until
full operating intensity is achieved.
Safety Zones: For the proposed seismic survey, Shell proposes to
implement the following measures:
(a) Initial safety zones will be established prior to the survey
based on available data and modelling concerning sound output and on
the assumption that seismic pulses at broadband received levels above
190 dB re 1 microPa (rms over duration of pulse) for pinnipeds, or
above 180 dB re 1 microPa rms for cetaceans, should be avoided whenever
possible because those levels might affect hearing abilities at least
temporarily. The sound levels are based on frequencies between 10 Hz
and 120 Hz, the typical peak spectrum of sound emitted for seismic
surveys.
(b) The safety distances will be verified (and if necessary
adjusted) during the first week of the seismic survey, based on direct
measurements via calibrated hydrophones of the received levels of
underwater sound versus distance and direction from the airgun array.
The acoustic data will be analyzed as quickly as reasonably practicable
in the field and used to adjust safety distance. The same acoustic data
will be useful in interpreting observations of marine mammals during
analysis of sighting data after the programs completion (see below).
Biological Observers: For the proposed seismic survey, Shell
proposes to implement the following measures:
(a) Trained marine mammal observers on the seismic ship will be on
watch for marine mammals during all daylight hours when seismic
operations are in progress. This will require at least three and
preferably four observers on the vessel, given that observer efficiency
deteriorates after approximately 4 hours, and that having two observers
on watch simultaneously increases the probability of sighting the
marine mammals present near the vessel. In selecting seismic vessels
for the program, Shell has accounted for the requirement to accommodate
3 to 4 marine mammal observers on each vessel.
(b) The purpose of the observers on the seismic vessel will
primarily be to document the occurrence and responses of marine mammals
visible from the vessel, and to initiate airgun shutdown requirements
whenever a marine mammal is observed within the safety zone.
Furthermore, the observers will attempt to confirm the absence of
marine mammals in the safety zones prior to 'soft start'.
(c) When a marine mammal is sighted within, or approaching, the
safety zone around the airgun array, the observers will notify the
seismic contractor who will shut down the airguns. After completion of
the survey, a technical report and a scientific research paper will be
prepared to summarize the observations, results, and conclusions of the
marine mammal monitoring program.
Operations at Night and in Poor Visibility: For the proposed
seismic programs in the Beaufort and Chukchi seas, Shell proposes the
following measures:
(a) When operating under conditions of reduced visibility
attributable to darkness or to adverse weather conditions, infra-red or
night-vision binoculars will be available for use. It is recognized,
however, that their effectiveness for this application is very limited
even in clear night time conditions.
(b) Seismic activities will not be initiated during darkness or
during conditions when visibility is reduced to less than the radius of
the safety zone. Shell proposes that if a single small airgun remains
firing during a shut-down, the rest of the array can be ramped up
during darkness or in periods of low visibility. Seismic operations may
continue under conditions of darkness or reduced visibility unless, in
the judgement of the senior MMO, densities of endangered cetaceans in
the general area are high
[[Page 26067]]
enough to warrant concern that an endangered cetacean is likely to
enter the safety zone undetected. In that case, observers will advise
the ship's captain or his designee to halt airgun operations or to move
to a part of the survey area where visibility is adequate or where the
likelihood of encountering an endangered cetacean is low based on
aerial and vessel based surveys that would be part of the real-time
monitoring program.
Mitigation for Subsistence Needs
Although not discussed in detail by Shell, NMFS must make a
determination that an activity would not have an unmitigable adverse
impact on the availability of marine mammals for taking for subsistence
uses. While this includes both cetaceans and pinnipeds, the primary
impact by seismic activities on subsistence hunting is expected to be
impacts from noise on bowhead whales during its westward fall feeding
and migration period in the Beaufort Sea. NMFS has defined unmitigable
adverse impact 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 (50
CFR 216.103). Discussions between the AEWC, the whaling captains and
Shell continue at this time and results of those discussions will be
reported in the final IHA notice.
A signed CAA allows NMFS to make a determination that the activity
will not have an unmitigable adverse impact on the subsistence use of
marine mammals. If one or both parties fail to sign the CAA, then NMFS
will make the necessary determinations that the activity will or will
not have an unmitigable adverse impact on subsistence use of marine
mammals and NMFS may require that the IHA contain additional mitigation
measures in order for this decision to be made.
Proposed Monitoring
As part of its application, Shell provided a monitoring plan for
assessing impacts to marine mammals from seismic surveys in the
Beaufort and Chukchi seas. Shell proposes to conduct the following
monitoring:
Vessel-based Visual Monitoring
Shell proposes that one or two marine mammal observers aboard the
operating seismic vessel will search for and observe marine mammals
whenever seismic operations are in progress and for at least 30 minutes
before the planned start of seismic transmissions or whenever the
seismic array's operations have been suspended for more than 10
minutes. These observers will scan the area immediately around the
vessels with reticle binoculars during the daytime. Laser rangefinding
equipment will be available to assist with distance estimation. After
mid-August, when the duration of darkness increases, image intensifiers
will be used by observers and additional light sources may be used to
illuminate the safety zone.
A total of four observers (three trained biologists and one Inupiat
observer/communicator) will be based aboard the seismic vessel. The use
of four observers allows two observers to be on duty simultaneously for
up to 50 percent of the active airgun hours. The use of two observers
increases the probability of detecting marine mammals, and two
observers will be required to be on duty whenever the seismic array is
ramped up. Individual watches will be limited to no more than 4
consecutive hours to avoid observer fatigue (and no more than 12 hours
on watch per 24 hour day). When mammals are detected within or about to
enter the safety zone designated to prevent injury to the animals (see
Proposed Mitigation), the geophysical crew leader will be notified so
that shutdown procedures can be implemented immediately.
Aerial Surveys
Shell proposes to conduct aerial surveys bi-weekly from the middle
to the end of August, and daily (when possible due to weather) after
September 1\st\ in the Beaufort Sea. At this time Shell does not
propose to conduct aerial surveys in the Chukchi Sea. Aerial surveys in
the Beaufort Sea are proposed to continue for three days after the
cessation of seismic operations.
Aerial surveys are typically conducted by teams of four observers
(a pilot, two dedicated observers, and an observer/data recorder) in
twin-engine airplanes. Observations are made at an altitude of 900 to
1,500 ft (274 to 457 m)and a ground speed of 120 knots (120 nm/hr; 138
statute mi (mi)/hr; 222 km/hr). Similar to previous Beaufort Sea aerial
surveys, the survey plane will traverse a survey grid, centered on the
seismic operations, which extends 50 to 75 km (31 to 46.6 mi) both east
and west of the seismic operations and to 75 km (46.6 mi) offshore.
Shell suggests that periodic flights that range further to the east may
be utilized prior to the onset of migration to provide an early warning
of the approach of migrating bowhead whales.
However, NMFS proposes that if seismic work is suspended during the
bowhead subsistence hunting season, but resumes later in the autumn,
aerial surveys will commence (or resume) when the seismic work resumes.
In addition, MMS expects to conduct its broad-scale BWASP aerial survey
work from approximately August 31st until the end of the bowhead
migration in October. NMFS believes that this combined aerial survey
data will provide good information to estimate the number of bowheads
taken by Level B harassment.
The primary objective of the aerial surveys will be to document the
occurrence, distribution, and movements of bowhead, as well as beluga
and gray, whales in and near the area where they might be affected by
the seismic pulses. These observations will be used to estimate the
level of harassment takes and to assess the possibility that seismic
operations affect the accessibility of bowhead whales for subsistence
hunting. Pinnipeds will be recorded when seen, although survey altitude
will be too high for systematic surveys of seals.
Passive Acoustic Monitoring
Shell is considering the possibility of using a towed hydrophone
array or other passive acoustic technique to detect and perhaps locate
marine mammals during this seismic project. Towed hydrophones that are
part of the seismic array have the ability to detect marine mammals
within close proximity of the array but generally do not provide
accurate location information. Hydrophone technology utilizing fixed
position hydrophones has been useful in locating bowhead whales through
their vocalizations around the fixed BP NorthStar facility (Richardson,
2005), however, the proposed seismic operation will be far ranging and
would require either an extensive array of fixed sonobuoys, or multiple
``listening'' vessels. The presence of ``listening'' vessels within the
seismic project area would add significantly to the number of noise
sources present and broaden the potential impact area.
The use of aerial monitoring has demonstrated that bowheads avoid
areas where active seismic operations are being conducted and is
effective at documenting the extent of this impact.
[[Page 26068]]
Aerial surveys can also provide early, near-real time, reconnaissance
information as to presence or approach of marine mammals to areas of
seismic operation. According to Shell, the use of real-time acoustic
monitoring would, therefore, not add significantly to the information
available to seismic operators but would add significantly to the
complexity and potential area of impact of the project. As a result,
while Shell's original application did not propose to use passive
acoustical monitoring during either the Beaufort or Chukchi Sea seismic
operations, the value of implementing a passive acoustic program was
discussed at the recent Anchorage meeting. Accordingly, Shell is
presently reviewing its earlier determination. NMFS scientists believe
that incorporating either a towed passive array from the seismic vessel
or one of the support vessels or installing a passive net array along
the Chukchi Sea coast would add valuable information on the marine
mammals in the area.
Additional Proposed Mitigation and Monitoring Measures
As part of NMFS' week-long open-water peer review meeting in
Anchorage, on April 19-20, 2006, participants had a discussion on
appropriate mitigation and monitoring measures for Arctic Ocean seismic
activities in 2006. In addition to previously mentioned mitigation and
monitoring measures proposed by Shell, the workshop participants
recommended several monitoring measures to increase our knowledge of
marine mammal distribution and abundance in the Chukchi Sea. These
included use of passive acoustics, either towed from a vessel or set
out in a series of arrays along the Chukchi Sea coast. As of the
publication date of this notice, Shell is studying these
recommendations and will inform NMFS prior to the close of the comment
period on this document on any additional monitoring that would be
conducted.
In addition, NMFS proposes to impose additional mitigation and
monitoring measures, such as expanded safety zones for bowhead and gray
whales, and having those zones monitored effectively, in order to
remain within the scope of the PEA and to increase the likelihood for
NMFS and MMS to make a Finding of No Significant Impact (FONSI) under
the National Environmental Policy Act (NEPA).
Research
Shell proposes to develop and implement a research component to its
marine mammal monitoring program that would further improve the
understanding of bowhead whale deflection related to industrial sound
sources, most specifically the operation of seismic operations. A
detailed study plan is being developed that will utilize data from
aerial surveys, possibly combined with acoustic monitoring. That
research plan will include:
Vessel-based Surveys: Three MMOs will conduct observations onboard
a dedicated vessel conducting three individual 2-3 day surveys early in
the seismic season, in the middle of the season and late in the season,
as well as opportunistic surveys while the vessel is being used for
crew changes/supply runs. The survey will systematically cover broad
areas of the Chukchi planning area in order to obtain adequate coverage
across multiple habitat types (subject to vessel operational
limitations near ice pack). The surveys will provide: (1) quantitative
data on distribution and densities for each marine mammal species by
habitat (depth and ice); (2) sighting data to compute densities during
seismic and non seismic periods; (3) density information during non-
seismic periods to be used to estimate numbers of marine mammals that
would have been exposed to various sound levels (160, 180, 190 dB re 1
microPa), if they had not moved away from the seismic vessel; and (4)
sighting and density information from operating seismic vessel will
provide data on numbers that did not avoid the vessel and were exposed
to the same sound levels.
Reporting
Shell proposes to submit a report to NMFS approximately 90 days
after completion of the 2006 season and a final technical report
approximately 240 days after completion of the 2006 season. The 90-day
report will: (1) present the results of the 2006 shipboard marine
mammal monitoring; (2) estimate exposure of marine mammals to industry
sounds; (3) provide data on marine mammal sightings (e.g., species,
numbers, locations, age/size/gender, environmental correlates); (4)
analyze the effects of seismic operations (e.g., on sighting rates,
sighting distances, behaviors, movement patterns); (5) provide
summaries of power downs, shut downs, and ramp up delays; (6) provide
an analysis of factors influencing detectability of marine mammals; and
(7) provide summaries on communications with hunters and potential
effects on subsistence activities.
NMFS proposes that the Final Technical Report will contain a
cumulative analysis of the data and information of the 90-day report
with similar data and information from other seismic activities in the
Beaufort and Chukchi seas in 2006.
Endangered Species Act (ESA)
Under section 7 of the ESA, the MMS has begun consultation on the
proposed seismic survey activities in the Beaufort and Chukchi seas
during 2006. NMFS will also consult on the issuance of the IHA under
section 101(a)(5)(D) of the MMPA to Shell for this activity.
Consultation will be concluded prior to a determination on the issuance
of an IHA.
NEPA
The MMS has prepared a Draft PEA for the 2006 Arctic Outer
Continental Shelf (OCS) Seismic Surveys. NMFS is a cooperating agency
in the preparation of the Draft PEA. NMFS is reviewing this PEA and
will either adopt it or prepare its own NEPA document before making a
determination on the issuance of Arctic Ocean OCS seismic surveys in
2006. A copy of the MMS Draft PEA for this activity is available upon
request and is available online (see ADDRESSES).
Preliminary Conclusions
Summary
Based on the information provided in Shell's application and the
MMS PEA, NMFS has preliminarily determined that the impact of Shell
conducting seismic surveys in the northern Chukchi Sea and eastern and
central Beaufort Sea in 2006 will have no more than a negligible impact
on marine mammals and that there will not be any unmitigable adverse
impacts to subsistence communities, provided the mitigation measures
required under the authorization are implemented and a CAA is
implemented.
Potential Impacts on Marine Mammals
NMFS has preliminarily determined that the relatively short-term
impact of conducting seismic surveys in the U.S. Chukchi and Beaufort
seas may result, at worst, in a temporary modification in behavior by
certain species of marine mammals. While behavioral and avoidance
reactions may be made by these species in response to the resultant
noise, this behavioral change is expected to have a negligible impact
on the affected species and stocks of marine mammals.
[[Page 26069]]
While the number of potential incidental harassment takes will
depend on the distribution and abundance of marine mammals in the area
of seismic operations (as shown in Table 4-1 in the applications),
which will vary annually due to variable ice conditions and other
factors, the number of potential harassment takings is estimated to be
small (see Tables 1 and 2 in this document).
In addition, no take by death or serious injury is anticipated, and
the potential for temporary or permanent hearing impairment will be
avoided through the incorporation of the mitigation measures proposed
for Shell's IHA. This preliminary determination is supported by: (1)
the likelihood that, given sufficient notice through slow ship speed
and ramp-up of the seismic array, marine mammals are expected to move
away from a noise source that is annoying prior to its becoming
potentially injurious; (2) recent research that indicates that TTS is
unlikely at SPLs as low as 180 dB re 1 microPa;(at least in
delphinids); (3) the fact that injurious levels would be very close to
the vessel; and (4) the likelihood that marine mammal detection ability
by trained observers is close to 100 percent during daytime and remains
high at night close to the seismic vessel. Finally, no known rookeries,
mating grounds, areas of concentrated feeding, or other areas of
special significance for marine mammals are known to occur within or
near the planned areas of operations during the season of operations.
Potential Impacts on Subsistence Uses of Marine Mammals
Preliminarily, NMFS believes that the proposed seismic activity by
Shell in the northern Chukchi Sea and central and eastern Beaufort Sea
in 2006, in combination with other seismic and oil and gas programs in
these areas, will not have an unmitigable adverse impact on the
subsistence uses of bowhead whales and other marine mammals. This
preliminary determination is supported by the following: (1) Seismic
activities in the Chukchi Sea will not begin until after July 10 by
which time the spring bowhead hunt is expected to have ended; (2) NMFS'
understanding that the fall bowhead whale hunt in the Beaufort Sea will
be governed by a CAA between Shell and the AEWC and village whaling
captains; (3) although unknown at this time to NMFS, the CAA conditions
will significantly reduce impacts on subsistence hunters; (4) while it
is possible that accessibility to belugas during the spring subsistence
beluga hunt could be impaired by the survey, it is unlikely because
very little of the proposed survey is within 25 km (15.5 mi) of the
Chukchi coast, meaning the vessel will usually be well offshore and
away from areas where seismic surveys would influence beluga hunting by
communities; and (5) because seals (ringed, spotted, bearded) are
hunted in nearshore waters and the seismic survey will remain offshore
of the coastal and nearshore areas of these seals where natives would
harvest these seals, it should not conflict with harvest activities.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
issue an IHA to Shell for conducting a seismic survey in the northern
Chukchi Sea and central and eastern Beaufort Sea in 2006, provided the
previously proposed mitigation, monitoring, and reporting requirements
are incorporated.
Information Solicited
NMFS requests interested persons to submit comments and information
concerning this request (see ADDRESSES).
Dated: April 28, 2006.
James H. Lecky,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 06-4172 Filed 5-2-06; 8:45 am]
BILLING CODE 3510-22-S