[Federal Register Volume 76, Number 100 (Tuesday, May 24, 2011)]
[Notices]
[Pages 30110-30130]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-12666]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XA396
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to Shallow Hazards Survey in the
Chukchi Sea, Alaska
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorization; request
for comments.
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SUMMARY: NMFS received an application from Statoil USA E&P Inc.
(Statoil) for an Incidental Harassment Authorization (IHA) to take
marine mammals, by harassment, incidental to a proposed open water
shallow hazards survey in the Chukchi Sea, Alaska, between July through
November 2011. Pursuant to the Marine Mammal Protection Act (MMPA),
NMFS is requesting comments on its proposal to issue an IHA to Statoil
to take, by Level B harassment only, thirteen species of marine mammals
during the specified activity.
DATES: Comments and information must be received no later than June 23,
2011.
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 e-
mail 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
[[Page 30111]]
FURTHER INFORMATION CONTACT), or visiting the Internet at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm. Documents cited in this
notice may also be viewed, by appointment, during regular business
hours, at the aforementioned address.
FOR FURTHER INFORMATION CONTACT: Shane Guan, Office of Protected
Resources, NMFS, (301) 713-2289, ext 137.
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 March 1, 2011, from Statoil for the
taking, by harassment, of marine mammals incidental to shallow hazards
site surveys and soil investigations (geotechnical boreholes) in the
Chukchi Sea, Alaska, during the 2011 open-water season. After
addressing comments from NMFS, Statoil modified its application and
submitted a revised application on April 19, 2011. The April 19, 2011,
application is the one available for public comment (see ADDRESSES) and
considered by NMFS for this proposed IHA.
The proposed shallow hazards and site clearance surveys would use a
towed airgun cluster consisting of four, 10-in\3\ airguns with a ~600 m
towed hydrophone streamer, as well as additional lower-powered and
higher frequency survey equipment for collecting bathymetric and
shallow sub-bottom data. The proposed survey will take place on and
near Statoil's leases in the Chukchi Sea, covering a total area of ~665
km\2\ located ~240 km (150 mi) west of Barrow and ~165 km (103 mi)
northwest of Wainwright, in water depths of ~30-50 m (100-165 ft).
The proposed geotechnical soil investigations will take place at
prospective drilling locations on Statoil's leases and leases jointly
owned with ConocoPhillips Alaska Inc. (CPAI). All cores will be either
2.1 in. or 2.8 in. in diameter (depending on soil type) and those
collected at prospective drilling locations will be up to 100 m in
depth. The maximum total number of samples collected as part of the
drilling location and site survey program will be ~29.
Statoil intends to conduct these marine surveys during the 2011
Arctic open-water season (July through November). Impacts to marine
mammals may occur from noise produced from active acoustic sources
(including airguns) used in the surveys.
Description of the Specified Activity
Statoil acquired 16 leases in the Chukchi Sea during Lease Sale 193
held in February 2008. The leased areas are located ~240 km (150 mi)
west of Barrow and ~160 km (~100 mi) northwest of Wainwright. During
the open-water season of 2010, Statoil conducted a 3D seismic survey
over its lease holdings and the surrounding area. The data gathered
during that survey are currently being analyzed in order to determine
potential well locations on the leases. These analyses will be
completed prior to commencement of the site survey program. During the
open-water season of 2011, Statoil proposes to conduct shallow hazards
and site clearance surveys (site surveys) and soil investigations
(geotechnical boreholes).
The proposed operations will be performed from two different
vessels. Shallow hazards surveys will be conducted from the M/V Duke,
while geotechnical soil investigations will be conducted from the M/V
Fugro Synergy (see Statoil's application for vessel specifications).
Both vessels will mobilize from Dutch Harbor in late July and arrive in
the Chukchi Sea to begin work on or after 1 August. Allowing for poor
weather days, operations are expected to continue into late September
or early October. However, if weather permits and all planned
activities have not been completed, operations may continue as late as
15 November.
The site survey work on Statoil's leases will require approximately
23 days to complete. Geotechnical soil investigations on Statoil leases
and on leases jointly held with CPAI will require ~14 days of
operations.
Shallow Hazards and Site Clearance Surveys
Shallow hazards site surveys are designed to collect bathymetric
and shallow sub-seafloor data that allow the evaluation of potential
shallow faults, gas zones, and archeological features at prospective
exploration drilling locations, as required by the Bureau of Ocean
Energy Management, Regulation, and Enforcement (BOEMRE). Data are
typically collected using multiple types of acoustic equipment. During
the site surveys, Statoil proposes to use the following acoustic
sources: 4x10 in\3\ airgun cluster, single 10 in\3\ airgun, Kongsberg
SBP3000 sub-bottom profiler, GeoAcoustics 160D side-scan sonar, and a
Kongsberg EM2040 multi-beam echosounder. The operating frequencies and
estimated source levels of this equipment are provided below.
1. Airguns
A 4x10 in\3\ airgun cluster will be used to obtain geological data
during the shallow hazards survey. A similar airgun cluster was
measured by Shell in 2009 during shallow hazards surveys on their
nearby Burger prospect (Reiser et al. 2010). The measurements resulted
in 90th percentile propagation loss equations of RL =
[[Page 30112]]
218.0-17.5LogR-0.00061R for a 4x10 in\3\ airgun cluster and RL = 204.4-
16.0LogR-0.00082R for a single 10 in\3\ airgun (where RL = received
level and R = range). The estimated 190, 180, and 160 dBrms
re 1 [mu]Pa isopleths are estimated at 39 m, 150 m, and 1,800 m from
the source. More accurate isopleths at these received levels will be
established prior to Statoil's shallow hazards survey (see below).
2. Kongsberg SBP300 Sub-Bottom Profiler
This instrument will be operated from the M/V Duke during site
survey operations. This sub-bottom profiler operates at frequencies
between 2 and 7 kHz with a manufacturer specified source level of ~225
dB re 1 [mu]Pa-m. The sound energy is projected downwards from the hull
in a maximum 15[deg] cone. However, field measurements of similar
instruments in previous years have resulted in much lower actual source
levels (range 161-186 dB) than specified by the manufacturers (i.e. the
manufacturer source level of one instrument was reported as 214 dB, and
field measurements resulted in a source level estimate of 186.2 dB)
(Reiser et al. 2010). Although it is not known whether these field
measurements captured the narrow primary beam produced by the
instruments, Statoil will measure the sounds produced by this
instrument (and all other survey equipment) at the start of operations
and if sounds from the instrument are found to be above mitigation
threshold levels (180 dB for cetaceans, 190 dB for seals) at a distance
beyond the footprint of the vessel, then the same power-down and shut-
down mitigation measures used during airgun operations will be employed
during use of the sub-bottom profiler.
3. GeoAcoustics 160D Side-Scan Sonar
The side-scan sonar will be operated from the M/V Duke during site
survey operations. This unit operates at 114 kHz and 410 kHz with a
source level of ~233 dB re 1 [mu]Pa-m. The sound energy is emitted in a
fan shaped pattern that is narrow (0.3-1.0[deg]) in the fore/aft
direction of the vessel and broad (40-50[deg]) in the port/starboard
direction.
4. Kongsberg EM2040 Multi-Beam Echosounder
Multi-beam echosounders also emit energy in a fan-shaped pattern,
similar to the side-scan sonar described above. This unit operates at
200 to 400 kHz with a source level of ~210 dB re 1 [mu]Pa-m. The beam
width is 1.5[deg] in the fore/aft direction. The multi-beam echosounder
will be operated from the M/V Duke during site surveys operations.
Geotechnical Soil Investigations
Geotechnical soil investigations are performed to collect detailed
data on seafloor sediments and geological structure to a maximum depth
of 100 m. These data are then evaluated to help determine the
suitability of the site as a drilling location. Statoil has contracted
with Fugro who will use the vessel M/V Fugro Synergy to complete the
planned soil investigations. Three to four bore holes will be collected
at each of up to 5 prospective drilling locations on Statoil's leases
and up to 3 boreholes may be completed at each of up to 3 potential
drilling locations on leases jointly owned with CPAI. This would result
in a maximum total of 29 bore holes to be completed as part of the
geotechnical soil investigation program. The Fugro Synergy operates a
Kongsberg EA600 Echosounder and uses a Kongsberg 500 high precision
acoustic positioning (HiPAP) system for precise vessel positioning
while completing the boreholes. The operating frequencies and estimated
source levels of the acoustic equipment, as well as the sounds produced
during soil investigation sampling, are provided in the sub-section
below.
1. Kongsberg EA600 Echosounder
This echosounder will be operated from the M/V Fugro Synergy
routinely as a fathometer to provide depth information to the bridge
crew. This model is capable of simultaneously using 4 transducers, each
with a separate frequency. However, only 2 transducers will be mounted
and used during this project. These transducers will operate at 18 kHz
and 200 kHz and have similar or slightly lower source levels than the
multi-beam echosounder described above. The energy from these
transducers is emitted in a conical beam from the hull of the vessel
downward to the seafloor.
2. Kongsberg HiPAP 500
The Kongsberg high precision acoustic positioning system (HiPAP)
500 is used to aid the positioning of the M/V Fugro Synergy during soil
investigation operations. An acoustic signal is sent and received by a
transponder on the hull of the vessel and a transponder lowered to the
seafloor near the borehole location. The two transponders communicated
via signals with a frequency of between 21-30.5 kHz with source levels
expected to be in the 200-210 dB range.
3. Geotechnical Soil Investigation Sounds
In-water sounds produced during soil investigation operations by
the M/V Fugro Synergy have not previously been measured and estimates
of such activities vary. Measurements of another Fugro vessel that
often conducts soil investigations were made in the Gulf of Mexico in
2009. However, because measurements were taken using a towed hydrophone
system, recordings of soil investigation related sounds could not be
made while the vessel was stationary. Therefore, sounds recorded while
the vessel was in transit were compared to sounds recorded while the
vessel also operated generators and mechanical equipment associated
with soil investigation operations while in transit. The difference in
sound levels during transit alone and during transit with soil
investigation equipment operating was negligible and this was
attributed to the fact that transit noise was dominant up to at least 7
kHz and likely masked the lower frequency sounds produced by the
simulated soil investigation activities.
4. Dynamic Positioning Sound
During soil investigation operations, the M/V Fugro Synergy will
remain stationary relative to the seafloor by means of a dynamic
positioning (DP) system that automatically controls and coordinates
vessel movements using bow and/or stern thrusters as well as the
primary propeller(s). The sounds produced by soil investigation
equipment are not likely to substantially increase overall source
levels beyond those produced by the various thrusters while in DP mode.
Measurements of a vessel in DP mode with an active bow thruster were
made in the Chukchi Sea in 2010 (Chorney et al. 2011). The resulting
source level estimate was 175.9 dBrms re 1 [mu]Pa-m. Using
the transmission loss equation from measurements of a single 60 in\3\
airgun on Statoil's lease in 2010 (RL = 205.6-13.9LogR-0.00093R;
O'Neill et al. 2011) and replacing the constant term with the 175.9
results in an estimated range of 4.97 km to the 120 dB level. To allow
for uncertainties and some additional sound energy being contributed by
the operating soil investigation equipment, an inflation factor of 1.5
was applied to arrive at an estimated >= 120 dB radius of 7.5 km for
soil investigation activities.
Description of Marine Mammals in the Area of the Specified Activity
Nine cetacean and four seal species could occur in the general area
of the
[[Page 30113]]
site clearance and shallow hazards survey. The marine mammal species
under NMFS's jurisdiction most likely to occur near operations in the
Chukchi and Beaufort seas include four cetacean species: Beluga whale
(Delphinapterus leucas), bowhead whale (Balaena mysticetus), gray whale
(Eschrichtius robustus), and harbor porpoise (Phocoena phocoena), and
three seal species: ringed (Phoca hispida), spotted (P. largha), and
bearded seals (Erignathus barbatus). The marine mammal species that is
likely to be encountered most widely (in space and time) throughout the
period of the planned site clearance and shallow hazards surveys is the
ringed seal.
Other marine mammal species that have been observed in the Chukchi
Sea but are less frequent or uncommon in the project area include
narwhal (Monodon monoceros), killer whale (Orcinus orca), fin whale
(Balaenoptera physalus), minke whale (B. acutorostrata), humpback whale
(Megaptera novaeangliae), and ribbon seal (Histriophoca fasciata).
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 proposed shallow hazards
survey. 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).
The bowhead, fin, 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 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.
Statoil's application contains information on the status,
distribution, seasonal distribution, and abundance of each of the
species under NMFS jurisdiction mentioned in this document. Please
refer to the application for that information (see ADDRESSES).
Additional information can also be found in the NMFS Stock Assessment
Reports (SAR). The Alaska 2010 SAR is available at: http://www.nmfs.noaa.gov/pr/pdfs/sars/ak2010.pdf.
Potential Effects of the Specified Activity on Marine Mammals
Operating active acoustic sources such as an airgun array has the
potential for adverse effects on marine mammals.
Potential Effects of Airgun Sounds on Marine Mammals
The effects of sounds from airgun pulses might include one or more
of the following: tolerance, masking of natural sounds, behavioral
disturbance, and temporary or permanent hearing impairment or non-
auditory effects (Richardson et al. 1995). 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) Tolerance
Numerous studies have shown that pulsed sounds from airguns are
often readily detectable in the water at distances of many kilometers.
Numerous studies have also shown that marine mammals at distances more
than a few kilometers from operating survey vessels often show no
apparent response. That is often true even in cases when the pulsed
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 airgun pulses under
some conditions, at other times, mammals of all three types have shown
no overt reactions. In general, pinnipeds and small odontocetes seem to
be more tolerant of exposure to airgun pulses than baleen whales.
(2) Behavioral Disturbance
Marine mammals may behaviorally react to sound when exposed to
anthropogenic noise. These behavioral reactions are often shown as:
changing durations of surfacing and dives, number of blows per
surfacing, or moving direction and/or speed; reduced/increased vocal
activities; changing/cessation of certain behavioral activities (such
as socializing or feeding); visible startle response or aggressive
behavior (such as tail/fluke slapping or jaw clapping); avoidance of
areas where noise sources are located; and/or flight responses (e.g.,
pinnipeds flushing into water from haulouts or rookeries).
The biological significance of many of these behavioral
disturbances is difficult to predict, especially if the detected
disturbances appear minor. However, the consequences of behavioral
modification could be expected to be biologically significant if the
change affects growth, survival, and reproduction. Some of these
significant behavioral modifications include:
Drastic change in diving/surfacing patterns (such as those
thought to be causing beaked whale stranding due to exposure to
military mid-frequency tactical sonar);
Habitat abandonment due to loss of desirable acoustic
environment; and
Cease feeding or social interaction.
For example, at the Guerreo Negro Lagoon in Baja California,
Mexico, which is one of the important breeding grounds for Pacific gray
whales, shipping and dredging associated with a salt works may have
induced gray whales to abandon the area through most of the 1960s
(Bryant et al. 1984). After these activities stopped, the lagoon was
reoccupied, first by single whales and later by cow-calf pairs.
The onset of behavioral disturbance from anthropogenic noise
depends on both external factors (characteristics of noise sources and
their paths) and the receiving animals (hearing, motivation,
experience, demography) and is also difficult to predict (Southall et
al. 2007).
Currently NMFS uses 160 dB re 1 [mu]Pa at received level for
impulse noises (such as airgun pulses) as the onset of marine mammal
behavioral harassment.
(3) Masking
Chronic exposure to excessive, though not high-intensity, noise
could cause masking at particular frequencies for marine mammals that
utilize sound for vital biological functions. Masking can interfere
with detection of acoustic signals such as communication calls,
echolocation sounds, and environmental sounds important to marine
mammals. Since marine mammals depend on acoustic cues for vital
biological functions, such as orientation, communication, finding prey,
and avoiding predators, marine mammals that experience severe acoustic
masking will have reduced fitness in survival and reproduction.
Masking occurs when noise and signals (that the animal utilizes)
overlap at both spectral and temporal scales. For the airgun noise
generated from the proposed site clearance and shallow hazards surveys,
noise will consist of low frequency (under 1 kHz) pulses with extremely
short durations (in the scale of milliseconds). Lower frequency man-
made noises are more likely to affect detection of communication calls
and other potentially important natural
[[Page 30114]]
sounds such as surf and prey noise. There is little concern regarding
masking near the noise source due to the brief duration of these pulses
and relatively longer silence between airgun shots (9-12 seconds).
However, at long distances (over tens of kilometers away), due to
multipath propagation and reverberation, the durations of airgun pulses
can be ``stretched'' to seconds with long decays (Madsen et al. 2006).
Therefore it could affect communication signals used by low frequency
mysticetes when they occur near the noise band and thus reduce the
communication space of animals (e.g., Clark et al. 2009) and cause
increased stress levels (e.g., Foote et al. 2004; Holt et al. 2009).
Nevertheless, the intensity of the noise is also greatly reduced at
such long distances (for example, the modeled received level drops
below 120 dB re 1 [mu]Pa rms at 14,900 m from the source).
Marine mammals are thought to be able to compensate for masking by
adjusting their acoustic behavior such as shifting call frequencies,
increasing call volume and vocalization rates. For example, blue whales
are found to increase call rates when exposed to seismic survey noise
in the St. Lawrence Estuary (Di Iorio and Clark 2010). The North
Atlantic right whales (Eubalaena glacialis) exposed to high shipping
noise increase call frequency (Parks et al. 2007), while some humpback
whales respond to low-frequency active sonar playbacks by increasing
song length (Miller el al. 2000).
(4) Hearing Impairment
Marine mammals exposed to high intensity sound repeatedly or for
prolonged periods can experience hearing threshold shift (TS), which is
the loss of hearing sensitivity at certain frequency ranges (Kastak et
al. 1999; Schlundt et al. 2000; Finneran et al. 2002; 2005). TS can be
permanent (PTS), in which case the loss of hearing sensitivity is
unrecoverable, or temporary (TTS), in which case the animal's hearing
threshold will recover over time (Southall et al. 2007). Just like
masking, marine mammals that suffer from PTS or TTS will have reduced
fitness in survival and reproduction, either permanently or
temporarily. Repeated noise exposure that leads to TTS could cause PTS.
For transient sounds, the sound level necessary to cause TTS is
inversely related to the duration of the sound.
Experiments on a bottlenose dolphin (Tursiops truncates) and beluga
whale showed that exposure to a single watergun impulse at a received
level of 207 kPa (or 30 psi) peak-to-peak (p-p), which is equivalent to
228 dB re 1 [mu]Pa (p-p), resulted in a 7 and 6 dB TTS in the beluga
whale at 0.4 and 30 kHz, respectively. Thresholds returned to within 2
dB of the pre-exposure level within 4 minutes of the exposure (Finneran
et al. 2002). No TTS was observed in the bottlenose dolphin. Although
the source level of pile driving from one hammer strike is expected to
be much lower than the single watergun impulse cited here, animals
being exposed for a prolonged period to repeated hammer strikes could
receive more noise exposure in terms of SEL than from the single
watergun impulse (estimated at 188 dB re 1 [mu]Pa\2\-s) in the
aforementioned experiment (Finneran et al. 2002).
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 ambient noise levels at
those low frequencies tend to be higher (Urick 1983). 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).
From this, it is suspected that received levels causing TTS onset may
also be higher in baleen whales. However, no cases of TTS are expected
given the small size of the airguns proposed to be used and the strong
likelihood that baleen whales (especially migrating bowheads) would
avoid the approaching airguns (or vessel) before being exposed to
levels high enough for there to be any possibility of TTS.
In pinnipeds, TTS thresholds associated with exposure to brief
pulses (single or multiple) of underwater sound have not been measured.
Initial evidence from prolonged exposures suggested that some pinnipeds
may incur TTS at somewhat lower received levels than do small
odontocetes exposed for similar durations (Kastak et al. 1999, 2005;
Ketten et al. 2001). However, more recent indications are that TTS
onset in the most sensitive pinniped species studied (harbor seal,
which is closely related to the ringed seal) may occur at a similar SEL
as in odontocetes (Kastak et al., 2004).
NMFS (1995, 2000) concluded that cetaceans and pinnipeds should not
be exposed to pulsed underwater noise at 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. As summarized above,
data that are now available imply that TTS is unlikely to occur unless
bow-riding odontocetes are exposed to airgun pulses much stronger than
180 dB re 1 [mu]Pa rms (Southall et al. 2007).
No cases of TTS are expected as a result of Statoil's proposed
activities given the small size of the source, the strong likelihood
that baleen whales (especially migrating bowheads) would avoid the
approaching airguns (or vessel) before being exposed to levels high
enough for there to be any possibility of TTS, and the mitigation
measures proposed to be implemented during the survey described later
in this document.
There is no empirical evidence that exposure to pulses of airgun
sound can cause PTS in any marine mammal, even with large arrays of
airguns (see Southall et al., 2007). However, given the possibility
that mammals close to an airgun array might incur TTS, there has been
further speculation about the possibility that some individuals
occurring very close to airguns 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. That is, PTS might
occur at a received sound level magnitudes higher than the level of
onset TTS, or by repeated exposure to the levels that cause TTS.
Therefore, by means of preventing the onset of TTS, it is highly
unlikely that marine mammals could receive sounds strong enough (and
over a sufficient duration) to cause permanent hearing impairment
during the proposed marine surveys in the Chukchi Sea.
(5) Non-Auditory Physical Effects
Non-auditory physical effects might occur in marine mammals exposed
to strong underwater pulsed 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.
Some marine mammal species (i.e., beaked whales) may be
[[Page 30115]]
especially susceptible to injury and/or stranding when exposed to
strong pulsed sounds. However, there is no definitive evidence that any
of these effects occur even for marine mammals in close proximity to
large arrays of airguns, and beaked whales do not occur in the proposed
project area. In addition, marine mammals that show behavioral
avoidance of seismic vessels, including most baleen whales, some
odontocetes (including belugas), and some pinnipeds, are especially
unlikely to incur non-auditory impairment or other physical effects.
The small airgun array proposed to be used by Statoil would only have
190 and 180 dB distances of 35 and 125 m (115 and 410 ft),
respectively.
Therefore, it is unlikely that such effects would occur during
Statoil's proposed surveys given the brief duration of exposure and the
planned monitoring and mitigation measures described later in this
document.
(6) Stranding and Mortality
Marine mammals close to underwater detonations of high explosive
can be killed or severely injured, and the auditory organs are
especially susceptible to injury (Ketten et al. 1993; Ketten 1995).
Airgun pulses are less energetic and their peak amplitudes have slower
rise times. To date, there is no evidence that serious injury, death,
or stranding by marine mammals can occur from exposure to airgun
pulses, even in the case of large airgun arrays.
However, in numerous past IHA notices for seismic surveys,
commenters have referenced two stranding events allegedly associated
with seismic activities, one off Baja California and a second off
Brazil. NMFS has addressed this concern several times, and, without new
information, does not believe that this issue warrants further
discussion. For information relevant to strandings of marine mammals,
readers are encouraged to review NMFS' response to comments on this
matter found in 69 FR 74905 (December 14, 2004), 71 FR 43112 (July 31,
2006), 71 FR 50027 (August 24, 2006), and 71 FR 49418 (August 23,
2006). In addition, a May-June 2008, stranding of 100-200 melon-headed
whales (Peponocephala electra) off Madagascar that appears to be
associated with seismic surveys is currently under investigation (IWC
2009).
It should be noted that strandings related to sound exposure have
not been recorded for marine mammal species in the Beaufort and Chukchi
seas. NMFS notes that in the Beaufort Sea, aerial surveys have been
conducted by BOEMRE (formerly the Minerals Management Service or MMS)
and industry during periods of industrial activity (and by MMS during
times with no activity). No strandings or marine mammals in distress
have been observed during these surveys and none have been reported by
North Slope Borough inhabitants. As a result, NMFS does not expect any
marine mammals will incur serious injury or mortality in the Arctic
Ocean or strand as a result of the proposed shallow hazards survey.
Potential Effects From Active Sonar Equipment on Marine Mammals
Several active acoustic sources other than the four 10 in\3\ airgun
have been proposed for Statoil's 2011 open water shallow hazards survey
in the Chukchi Sea. The specifications of this sonar equipment (source
levels and frequency ranges) are provided above. In general, the
potential effects of this equipment on marine mammals are similar to
those from the airgun, except the magnitude of the impacts is expected
to be much less due to the lower intensity and higher frequencies.
Estimated source levels from sonar equipment are discussed above. In
some cases, due to the fact that the operating frequencies of some of
this equipment (e.g., Multi-beam echosounder: Frequency at 200-400 kHz)
are above the hearing ranges of marine mammals, they are not expected
to have any impacts to marine mammals.
Vessel Sounds
In addition to the noise generated from seismic airguns and active
sonar systems, various types of vessels will be used in the operations,
including source vessel and vessel used for geotechnical soil
investigations. 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; O'Neill and
McCrodan 2011; Chorney et al. 2011). 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. Compared to airgun pulses, underwater sound from
vessels is generally at relatively low frequencies. However, noise from
the vessel during geophysical soil investigation while operating the DP
system using thrusters as well as the primary propeller(s) could
produce noise levels higher than during normal operation of the vessel.
Measurements of a vessel in DP mode with an active bow thruster were
made in the Chukchi Sea in 2010 (Chorney et al. 2011). The resulting
source level estimate was 175.9 dBrms re 1 [mu]Pa-m. Noise
at this high level is not expected to be emitted continuously. It is
emitted intermittently as the pitch is engaged to position the vessel.
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. Source levels from various vessels would
be empirically measured before the start of marine surveys, and during
geotechnical soil investigation while operating the DP system.
Anticipated Effects on Habitat
The primary potential impacts to marine mammals and other marine
species are associated with elevated sound levels produced by airguns
and other active acoustic sources. However, other potential impacts to
the surrounding habitat from physical disturbance are also possible.
Potential Impacts on Prey Species
With regard to fish as a prey source for cetaceans and pinnipeds,
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
[[Page 30116]]
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), 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. 1995).
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). However, by the time most
bowhead whales reach the Chukchi Sea (October), they will likely no
longer be feeding, or if it occurs it will be very limited. A reaction
by zooplankton to a seismic impulse 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 source. Impacts on zooplankton behavior
are predicted to be negligible, and that would translate into
negligible impacts on feeding mysticetes. Thus, the proposed activity
is not expected to have any habitat-related effects that could cause
significant or long-term consequences for individual marine mammals or
their populations.
Proposed Mitigation
In order to issue an incidental take authorization under Section
101(a)(5)(D) of the MMPA, NMFS must set forth the permissible methods
of taking pursuant to such activity, and other means of effecting the
least practicable adverse 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.
For the proposed Statoil open water shallow hazards survey in the
Chukchi Sea, Statoil worked with NMFS and proposed the following
mitigation measures to minimize the potential impacts to marine mammals
in the project vicinity as a result of the shallow hazards survey
activities.
As part of the application, Statoil submitted to NMFS a Marine
Mammal Monitoring and Mitigation Program (4MP) for its open water
shallow hazards survey in the Chukchi Sea during the 2011 open-water
season. The objectives of the 4MP are:
To ensure that disturbance to marine mammals and
subsistence hunts is minimized and all permit stipulations are
followed,
To document the effects of the proposed survey activities
on marine mammals, and
To collect baseline data on the occurrence and
distribution of marine mammals in the study area.
The 4MP 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).
Mitigation Measures Proposed in Statoil's IHA Application
For the proposed mitigation measures, Statoil listed the following
protocols to be implemented during its shallow hazards survey in the
Chukchi Sea.
(1) Sound Source Measurements
As described above, previous measurements of similar airgun arrays
in the Chukchi Sea were used to model the distances at which received
levels are likely to fall below 120, 160, 180, and 190 dB re 1 [mu]Pa
(rms) from the planned airgun sources. These modeled distances will be
used as temporary safety radii until measurements of the airgun sound
source are conducted. The measurements will be made at the beginning of
the field season and the measured radii used for the remainder of the
survey period.
The objectives of the sound source verification measurements
planned for 2011 in the Chukchi Sea will be to measure the distances at
which broadband received levels reach 190, 180, 170, 160, and 120
dBrms re 1 [mu]Pa for the airgun configurations that may be
used during the survey activities. The configurations will include at
least the full array (4 x 10 in\3\) and the operation of a single 10
in\3\ airgun that will be used during power downs or very shallow
penetration surveys. The measurements of airgun sounds will be made by
an acoustics contractor at the beginning of the survey. The distances
to the various radii will be reported as soon as possible after
recovery of the equipment. The primary radii of concern will be the 190
and 180 dB safety radii for pinnipeds and cetaceans, respectively, and
the 160 dB disturbance radii. In addition to reporting the radii of
specific regulatory concern, nominal distances to other sound isopleths
down to 120 dBrms will be reported in increments of 10 dB.
Sound levels during soil investigation operations will also be
measured. However, source levels are not expected to be strong enough
to require mitigation actions at the 190 dB or 180 dB levels.
Data will be previewed in the field immediately after download from
the hydrophone instruments. An initial sound source analysis will be
supplied to NMFS and the vessel within 120 hours of completion of the
measurements, if possible. The report will indicate the distances to
sound levels based on fits of empirical transmission loss formulae to
data in the endfire and broadside directions. A more detailed report
will be issued to NMFS as part of the 90-day report following
completion of the acoustic program.
(2) Safety and Disturbance Zones
Under current NMFS guidelines, ``safety radii'' for marine mammal
exposure to impulse sources are customarily defined as the distances
within which received sound levels are >= 180 dBrms re 1
[mu]Pa for cetaceans and >= 190 dBrms re 1 [mu]Pa for
pinnipeds. These safety criteria are based on an assumption that SPL
received at levels lower than these will not injure these animals or
impair their hearing abilities, but that at higher levels might have
some such effects. Disturbance or behavioral effects to marine mammals
from underwater sound may occur after exposure to sound at distances
greater than the safety radii (Richardson et al. 1995).
Initial safety and disturbance radii for the sound levels produced
by the planned airgun configurations have been estimated (Table 1).
These radii will be used for mitigation purposes until results of
direct measurements are available early during the exploration
activities. The proposed surveys will use an airgun source composed of
four
[[Page 30117]]
10-in\3\ airguns (total discharge volume of 40 in\3\) and a single 10
in\3\ airgun. Underwater sound propagation from a similar 4 x 10-in\3\
airgun cluster and single 10 in\3\ was measured in 2009 (Reiser et al.
2010). Those measurements resulted in 90th percentile propagation loss
equations of RL = 218.0-17.5LogR-0.00061R for the 4 x 10 in\3\ airgun
cluster and RL = 204.4-16.0LogR-0.00082R for the single 10 in\3\ airgun
(where RL = received level and R = range). The estimated distances for
the proposed 2011 activities are based on a 25% increase over 2009
results (Table 1).
In addition to the site surveys, Statoil plans to use a dedicated
vessel to conduct geotechnical soil investigations. Sounds produced by
the vessel and soil investigation equipment are not expected to be
above 180 dB (rms). Therefore, mitigation related to acoustic impacts
from these activities is not expected to be necessary.
An acoustics contractor will perform direct measurements of the
received levels of underwater sound versus distance and direction from
the airguns and soil investigation vessel using calibrated hydrophones.
The acoustic data will be analyzed as quickly as reasonably practicable
in the field and used to verify and adjust the safety distances. The
field report will be made available to NMFS and the MMOs within 120 hrs
of completing the measurements. The mitigation measures to be
implemented at the 190 and 180 dB sound levels will include power downs
and shut downs as described below.
Table 1--Distances to Specified Received Levels Measured From a 4 x 10 in\3\ Airgun Cluster and a Single 10-
in\3\ Airgun on the Burger Prospect in 2009 as Reported by Reiser et al. (2010). The 2011 ``Pre-SSV'' Distances
Are a Precautionary 25% Increase Above the Reported 2009 Results and Will Be Used by MMOs for Mitigation
Purposes Until an SSV Is Completed in 2011
----------------------------------------------------------------------------------------------------------------
Distance (m)
-----------------------------------------------------------------------
Received Levels (dB re 1 [mu]Pa rms) Airgun cluster (4 x 10 in\3\) Single airgun (1 x 10 in\3\)
-----------------------------------------------------------------------
2009 Results 2011 pre-SSV 2009 Results 2011 pre-SSV
----------------------------------------------------------------------------------------------------------------
190..................................... 39 50 8 10
180..................................... 150 190 34 45
160..................................... 1,800 2,250 570 715
120..................................... 31,000 39,000 19,000 24,000
----------------------------------------------------------------------------------------------------------------
(3) Speed and Course Alterations
If a marine mammal is detected outside the applicable safety radius
and, based on its position and the relative motion, is likely to enter
the safety radius, changes of the vessel's speed and/or direct course
will be considered if this does not compromise operational safety. For
marine seismic surveys using large streamer arrays, course alterations
are not typically possible. However, for the smaller airgun array and
streamer planned during the proposed site surveys, such changes may be
possible. After any such speed and/or course alteration is begun, the
marine mammal activities and movements relative to the survey vessel
will be closely monitored to ensure that the marine mammal does not
approach within the safety radius. If the mammal appears likely to
enter the safety radius, further mitigative actions will be taken,
including a power down or shut down of the airgun(s).
(4) Power Downs
A power down for immediate mitigation purposes is the immediate
reduction in the number of operating airguns such that the radii of the
190 dBrms and 180 dBrms zones are decreased to
the extent that an observed marine mammal(s) are not in the applicable
safety zone of the full array. Power downs are also used while the
vessel turns from the end of one survey line to the start of the next.
During a power down, one airgun (or some other number of airguns less
than the full airgun array) continues firing. The continued operation
of one airgun is intended to (a) alert marine mammals to the presence
of the survey vessel in the area, and (b) retain the option of
initiating a ramp up to full operations under poor visibility
conditions.
The array will be immediately powered down whenever a marine mammal
is sighted approaching close to or within the applicable safety zone of
the full array, but is outside the applicable safety zone of the single
mitigation airgun. Likewise, if a mammal is already within the safety
zone when first detected, the airguns will be powered down immediately.
If a marine mammal is sighted within or about to enter the applicable
safety zone of the single mitigation airgun, it too will be shut down
(see following section).
Following a power down, operation of the full airgun array will not
resume until the marine mammal has cleared the safety zone. The animal
will be considered to have cleared the safety zone if it:
Is visually observed to have left the safety zone of the
full array, or
Has not been seen within the zone for 15 min in the case
of pinnipeds or small odontocetes, or
Has not been seen within the zone for 30 min in the case
of mysticetes or large odontocetes.
(5) Shut Downs
The operating airgun(s) will be shut down completely if a marine
mammal approaches or enters the then-applicable safety radius and a
power down is not practical or adequate to reduce exposure to less than
190 or 180 dBrms, as appropriate. In most cases, this means
the mitigation airgun will be shut down completely if a marine mammal
approaches or enters the estimated safety radius around the single 10
in\3\ airgun while it is operating during a power down. Airgun activity
will not resume until the marine mammal has cleared the safety radius.
The animal will be considered to have cleared the safety radius as
described above under power down procedures.
A shut down of the borehole drilling equipment may be requested by
MMOs if an animal is sighted approaching the vessel close enough to
potentially interact with and be harmed by the soil investigation
operation.
(6) Ramp Ups
A ramp up of an airgun array provides a gradual increase in sound
levels, and involves a step-wise increase in the number and total
volume of airguns firing until the full volume is achieved. The purpose
of a ramp up (or ``soft start'') is to ``warn'' cetaceans and pinnipeds
in the vicinity of the airguns and to provide the time for them to
leave the area and thus avoid any
[[Page 30118]]
potential injury or impairment of their hearing abilities.
During the proposed site survey program, the seismic operator will
ramp up the airgun cluster slowly. Full ramp ups (i.e., from a cold
start after a shut down, when no airguns have been firing) will begin
by firing a single airgun in the array. The minimum duration of a shut-
down period, i.e., without air guns firing, which must be followed by a
ramp up is typically the amount of time it would take the source vessel
to cover the 180-dB safety radius. Given the small size of the planned
airgun array, it is estimated that period to be about 1-2 minutes based
on the modeling results described above and a survey speed of 4 kts.
A full ramp up, after a shut down, will not begin until there has
been a minimum of 30 minutes of observation of the safety zone by MMOs
to assure that no marine mammals are present. The entire safety zone
must be visible during the 30-minute lead-in to a full ramp up. If the
entire safety zone is not visible, then ramp up from a cold start
cannot begin. If a marine mammal(s) is sighted within the safety zone
during the 30-minute watch prior to ramp up, ramp up will be delayed
until the marine mammal(s) is sighted outside of the safety zone or the
animal(s) is not sighted for at least 15-30 minutes: 15 minutes for
small odontocetes and pinnipeds, or 30 minutes for baleen whales and
large odontocetes.
During turns or brief transits between survey transects, one airgun
will continue operating. The ramp-up procedure will still be followed
when increasing the source levels from one airgun to the full 4-airgun
cluster. However, keeping one airgun firing will avoid the prohibition
of a cold start during darkness or other periods of poor visibility.
Through use of this approach, survey operations can resume upon entry
to a new transect without the 30-minute watch period of the full safety
radius required for a cold start. MMOs will be on duty whenever the
airguns are firing during daylight, and during the 30-min periods prior
to ramp-ups as well as during ramp-ups. Daylight will occur for 24 h/
day until mid-August, so until that date MMOs will automatically be
observing during the 30-minute period preceding a ramp up. Later in the
season, MMOs will be called to duty at night to observe prior to and
during any ramp ups. The survey operator and MMOs will maintain records
of the times when ramp-ups start, and when the airgun arrays reach full
power.
Additional Mitigation Measures Proposed by NMFS
Besides Statoil's proposed mitigation measures discussed above,
NMFS proposes the following additional protective measures to address
some uncertainties regarding the impacts of bowhead cow-calf pairs and
aggregations of whales from shallow hazards surveys. Specifically, NMFS
proposes that
A 160-dB vessel monitoring zone for large whales will be
established and monitored in the Chukchi Sea during all shallow hazards
surveys. Whenever an aggregation of bowhead whales or gray whales (12
or more whales of any age/sex class that appear to be engaged in a non-
migratory, significant biological behavior (e.g., feeding,
socializing)) are observed during a vessel monitoring program within
the 160-dB safety zone around the survey operations, the survey
activity will not commence or will shut down, until they are no longer
present within the 160-dB safety zone of shallow hazards surveying
operations.
Furthermore, 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, and 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 adjust speed (increase or decrease) and direction
accordingly 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 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 Statoil's IHA Application
The monitoring plan proposed by Statoil can be found in the 4MP.
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 marine survey activities. MMOs will
monitor the occurrence and behavior of marine mammals near the survey
vessel during all daylight periods during operation and during most
daylight periods when airgun operations are not occurring. MMO duties
will include watching for and identifying marine mammals, recording
their numbers, distances, and reactions to the survey operations, and
documenting ``take by harassment'' as defined by NMFS.
A sufficient number of MMOs will be required onboard the survey
vessel to meet the following criteria: (1) 100% monitoring coverage
during all periods of survey operations in daylight; (2) maximum of 4
consecutive hours on watch per MMO; and (3) maximum of
[[Page 30119]]
12 hours of watch time per day per MMO.
MMO teams will consist of Inupiat observers and experienced field
biologists. An experienced field crew leader will supervise the MMO
team onboard the survey vessel. The total number of MMOs may decrease
later in the season as the duration of daylight decreases. Statoil
currently plans to have 5 MMOs aboard the site survey vessel and 3 MMOs
aboard the soil investigation vessel, with the potential of reducing
the number of MMOs later in the season as daylight periods decrease in
length.
Crew leaders and most other biologists serving as observers in 2011
will be individuals with experience as observers during recent seismic
or shallow hazards monitoring projects in Alaska, the Canadian
Beaufort, or other offshore areas in recent years.
Observers will complete a two or three-day training session on
marine mammal monitoring, to be conducted shortly before the
anticipated start of the 2011 open-water season. The training
session(s) will be conducted by qualified marine mammalogists with
extensive crew-leader experience during previous vessel-based
monitoring programs. A marine mammal observers' handbook, adapted for
the specifics of the planned survey program will be reviewed as part of
the training.
Primary objectives of the training include:
Review of the marine mammal monitoring plan for this
project, including any amendments specified by NMFS in the IHA (if
issued), by USFWS or Bureau of Ocean Energy Management, Regulation and
Enforcement (BOEMRE), or by other agreements in which Statoil may elect
to participate;
Review of marine mammal sighting, identification, and
distance estimation methods;
Review of operation of specialized equipment (reticle
binoculars, night vision devices, and GPS system);
Review of, and classroom practice with, data recording and
data entry systems, including procedures for recording data on marine
mammal sightings, monitoring operations, environmental conditions, and
entry error control. These procedures will be implemented through use
of a customized computer database and laptop computers;
Review of the specific tasks of the Inupiat Communicator.
The observer(s) will watch for marine mammals from the best
available vantage point on the survey vessels, typically the bridge.
The observer(s) will scan systematically with the unaided eye and 7x50
reticle binoculars, supplemented with 20x60 image-stabilized Zeiss
Binoculars or Fujinon 25x150 ``Big-eye'' binoculars, and night-vision
equipment when needed (see below). Personnel on the bridge will assist
the marine mammal observer(s) 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.
Monitoring At Night and In Poor Visibility
Night-vision equipment (Generation 3 binocular image intensifiers,
or equivalent units) will be available for use when/if needed. Past
experience with night-vision devices (NVDs) in the Beaufort and Chukchi
seas and elsewhere has indicated that NVDs are not nearly as effective
as visual observation during daylight hours (e.g., Harris et al. 1997,
1998; Moulton and Lawson 2002).
(2) Acoustic Monitoring
Sound Source Measurements
As described above, previous measurements of airguns in the Chukchi
Sea were used to estimate the distances at which received levels are
likely to fall below 120, 160, 180, and 190 dBrms from the
planned airgun sources. These modeled distances will be used as
temporary safety radii until measurements of the airgun sound source
are conducted. The measurements will be made at the beginning of the
field season and the measured radii used for the remainder of the
survey period. An acoustics contractor will use their equipment to
record and analyze the underwater sounds and write the summary reports
as described below.
The objectives of the sound source verification measurements
planned for 2011 in the Chukchi Sea will be (1) to measure the
distances at which broadband received levels reach 190, 180, 170, 160,
and 120 dBrms re 1 [micro]Pa for the airgun configurations
that may be used during the survey activities. The configurations will
include at least the full array (4x10 in\3\) and the operation of a
single 10 in\3\ airgun that will be used during power downs or very
shallow penetration surveys.
2011 Joint Environmental Studies Program
Statoil, Shell Offshore, Inc. (Shell), and ConocoPhillips Alaska
Inc. (CPAI) are working on plans to once again jointly fund an
extensive environmental studies program in the Chukchi Sea. This
program is expected to be coordinated by Olgoonik-Fairweather LLC
(OFJV) during the 2011 open water season. The environmental studies
program is not part of the Statoil site survey and soil investigations
program, but acoustic monitoring equipment is planned to be deployed on
and near Statoil leases and will therefore collect additional data on
the sounds produced by the 2011 activities. The program components
include:
Acoustics Monitoring
Fisheries Ecology
Benthic Ecology
Plankton Ecology
Marine Mammal Surveys
Seabird Surveys, and
Physical Oceanography.
The planned 2011 program will continue the acoustic monitoring
programs carried out in 2006-2010. A similar number of acoustic
recorders as deployed in past years will be distributed broadly across
the Chukchi lease area and nearshore environment. In past years,
clusters of recorders designed to localize marine mammal calls
originating within or nearby the clusters have been deployed on each of
the companies' prospects: Amundsen (Statoil), Burger (Shell), and
Klondike (CPAI). This year, recorders from the clusters are planned to
be relocated in a broader deployment on and around Hanna Shoal.
The recorders will be deployed in late July or mid-August and will
be retrieved in early to mid-October, depending on ice conditions. The
recorders will be AMAR and AURAL model acoustic
[[Page 30120]]
buoys set to record at 16 kHz sample rate. These are the same recorder
models and same sample rates that have been used for this program from
2006-2010. The broad area arrays are designed to capture both general
background soundscape data, industrial sounds and marine mammal call
data across the lease area. From previous deployments of these
recordings we have been able to gain insight into large-scale
distributions of marine mammals, identification of marine mammal
species present, movement and migration patterns, and general abundance
data.
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 convened an independent peer review panel to review Statoil's
mitigation and monitoring plan in its IHA application for taking marine
mammals incidental to the proposed shallow hazards survey in the
Chukchi Sea, during 2011. The panel met and reviewed the plan in early
March 2011, and provided comments to NMFS in April 2011. NMFS is
currently reviewing the panel report and 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-dBrms re 1 [mu]Pa radii of the source vessel(s) 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 marine survey activities.
(2) Field Reports
Statoil states that throughout the survey program, the observers
will prepare a report each day or at such other interval as the IHA (if
issued), or Statoil may require, summarizing the recent results of the
monitoring program. The field reports will summarize the species and
numbers of marine mammals sighted. These reports will be provided to
NMFS and to the survey operators.
(3) Technical Reports
The results of Statoil's 2011 vessel-based monitoring, including
estimates of ``take'' by harassment, will be presented in the ``90-
day'' and Final Technical reports. Statoil proposes that the Technical
Reports will include:
(a) Summaries of monitoring effort (e.g., total hours, total
distances, and marine mammal distribution through the study period,
accounting for sea state and other factors affecting visibility and
detectability of marine mammals);
(b) Analyses of the effects of various factors influencing
detectability of marine mammals (e.g., sea state, number of observers,
and fog/glare);
(c) 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;
(d) Analyses of the effects of survey operations;
Sighting rates of marine mammals during periods with and
without airgun activities (and other variables that could affect
detectability), such as:
Initial sighting distances versus airgun activity state;
Closest point of approach versus airgun activity state;
Observed behaviors and types of movements versus airgun
activity state;
Numbers of sightings/individuals seen versus airgun
activity state;
Distribution around the survey vessel versus airgun
activity state; and
Estimates of take by harassment.
(4) Comprehensive Report
Following the 2011 open-water season a comprehensive report
describing the vessel-based 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 2011. 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.
(5) Notification of Injured or Dead Marine Mammals
In addition to the reporting measures proposed by Statoil, NMFS
will require that Statoil 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 marine survey operations. Statoil
shall 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
Statoil that is not in the vicinity of the proposed open water marine
survey program, Statoil will report the same information as listed
above as soon as operationally feasible to NMFS.
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 open water marine
survey program. Anticipated impacts to marine mammals are associated
with noise propagation from the survey airgun(s) used in the shallow
hazards survey.
The full suite of potential impacts to marine mammals 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 open water marine survey programs
might include one or more of the following: Tolerance; masking of
[[Page 30121]]
natural sounds; behavioral disturbance; non-auditory physical effects;
and, at least in theory, temporary or permanent hearing impairment
(Richardson et al. 1995). 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 proposed mitigation and
monitoring measures that would preclude marine mammals being exposed to
noise levels high enough to cause hearing impairment.
For impulse sounds, such as those produced by airgun(s) used in the
seismic survey, NMFS uses the 160 dBrms re 1 [mu]Pa isopleth
to indicate the onset of Level B harassment. For non-impulse sounds,
such as noise generated during the geotechnical soil investigation that
involves drilling bore holes and running DP thruster of the vessel,
NMFS uses the 120 dBrms re 1 [mu]Pa isopleth to indicate the
onset of Level B harassment. Statoil provided calculations for the 160-
and 120-dB isopleths produced by these activities and then used those
isopleths to estimate takes by harassment. NMFS used the calculations
to make the necessary MMPA preliminary findings. Statoil provided 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.
Statoil has requested an authorization to take 13 marine mammal
species by Level B harassment. These 13 marine mammal species are:
Beluga whale (Delphinapterus leucas), narwhal (Monodon monoceros),
killer whale (Orcinus orca), harbor porpoise (Phocoena phocoena),
bowhead whale (Balaena mysticetus), gray whale (Eschrichtius robustus),
humpback whale (Megaptera novaeangliae), minke whale (Balaenoptera
acutorostrata), fin whale (B. physalus), bearded seal (Erignathus
barbatus), ringed seal (Phoca hispida), spotted seal (P. largha), and
ribbon seal (Histriophoca fasciata).
Basis for Estimating ``Take by Harassment''
As stated previously, it is current NMFS policy to estimate take by
Level B harassment for impulse sounds at a received level of 160
dBrms re 1[mu]Pa. 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 7, 9, and 11 in Southall et al. (2007) outline the
numbers of low-frequency cetaceans, mid-frequency cetaceans, and
pinnipeds in water, respectively, reported as having behavioral
responses to multi-pulses in 10-dB received level increments. These
tables illustrate that for the studies summarized the more severe
reactions did not occur until sounds were much higher than 160
dBrms re 1[mu]Pa.
As described earlier in the document, a 4x10 in\3\ airgun cluster
will be used to obtain geological data during the site surveys. A
similar airgun cluster was measured by Shell in 2009 during shallow
hazards surveys on their nearby Burger prospect (Reiser et al. 2010).
The measurements resulted in 90th percentile propagation loss equations
of RL = 218.-17.5LogR-0.00061R for a 4x10 in\3\ airgun cluster and RL =
204.4-16.0LogR-0.00082R for a single 10 in\3\ airgun (where RL =
received level and R = range). For use in estimating potential
harassment takes in this application, as well as for mitigation radii
to be implemented by MMOs prior to SSV measurements, ranges to
threshold levels from the 2009 measurements were increased by 25% as a
precautionary approach (Table 1). The >=160 dB distance is therefore
estimated to be 2.25 km from the source. Adding a 2.25 km perimeter to
the two site survey areas results in an estimated area of 1,037 km\2\
being exposed to >=160 dB.
Geotechnical soil investigations on the Statoil leases and leases
jointly owned with CPAI will involve completing 3-4 boreholes at up to
8 total prospective drilling locations for an expected maximum of 29
boreholes. The 3-4 boreholes completed at each drilling location will
be positioned in a square or triangle formation, roughly 100 m on each
side. As described earlier, the sounds produced by soil investigation
equipment are estimated to fall below 120 dB at a distance of 7.5 km.
Buffering 4 core sites spaced 100 m apart with the 7.5 km 120 dB
distance results in a total area of 180 km\2\. The total area exposed
to sounds >=120 dB by soil investigations at the 8 prospective drilling
locations will therefore be 1,440 km\2\.
The following subsections describe the estimated densities of
marine mammals that may occur in the areas where activities are
planned, and areas of water that may be ensonified by pulsed sounds to
>= 160 dB or non-pulsed sounds to >= 120 dB.
Marine mammal densities near the planned activities in the Chukchi
Sea are likely to vary by season, and habitat. Therefore, densities
have been derived for two time periods, the summer period, including
July and August, and the fall period, including September and October.
Animal densities encountered in the Chukchi Sea during both of these
time periods will further depend on whether they are occurring in open
water or near the ice margin. Vessel and equipment limitations will
result in very little activity occurring in or near sea ice, however,
if ice is present near the areas of activity some sounds produced by
the activities may remain above disturbance threshold levels in ice
margin habitats. Therefore, open water densities have been used to
estimate potential ``take by harassment'' in 90% of the area expected
to be ensonified above disturbance thresholds while ice margin
densities have been used in the remaining 10% of the ensonified area.
Detectability bias [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%
probability of sighting an animal that is present on 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 analyses (e.g. Moore et al.
2000).
(1) Cetaceans
Eight species of cetaceans are known to occur in the Chukchi Sea
area of the proposed Statoil project. Only four of these (bowhead,
beluga, and gray whales, and harbor porpoise) are likely to be
encountered during the proposed survey activities. Three of the eight
species (bowhead, fin, and humpback whales) are listed as endangered
under the ESA. Of these, only the bowhead is likely to be found within
the survey area.
Beluga Whales--Summer densities of belugas in offshore waters of
the Chukchi Sea are expected to be low, with higher densities in ice-
margin and nearshore areas. Aerial surveys have recorded few belugas in
the offshore Chukchi Sea during the summer months (Moore et al. 2000).
Aerial surveys of the Chukchi Sea in 2008-2009 flown by the NMML as
part of the Chukchi Offshore Monitoring in Drilling Area project
(COMIDA) have only reported 5 beluga
[[Page 30122]]
sightings during > 14,000 km of on-transect effort, only 2 of which
were offshore (COMIDA 2009). One of the three nearshore sightings was
of a large group (~275 individuals on July 12, 2009) of migrating
belugas along the coastline just north of Peard Bay. Additionally, only
one beluga sighting was recorded during > 61,000 km of visual effort
during good visibility conditions from industry vessels operating
largely in offshore areas of the Chukchi Sea in September-October of
2006-2008 (Haley et al. 2010). If belugas are present during the
summer, they are more likely to occur in or near the ice edge or close
to shore during their northward migration. Expected densities have
previously been calculated from data in Moore et al. (2000). However,
more recent data from COMIDA aerial surveys during 2008-2010 are now
available. Effort and sightings reported by Clarke and Ferguson (in
prep.) were used to calculate the average open-water density estimate.
Clarke and Ferguson (in prep.) reported two on-transect beluga
sightings (5 individuals) during 11,985 km of on-transect effort in
waters 36-50 m deep in the Chukchi Sea during July and August. The mean
group size of these two sightings is 2.5 animals. A f(0) value of 2.841
and g(0) value of 0.58 from Harwood et al. (1996) were also used in the
density calculation. Specific data on the relative abundance of beluga
whales in open-water versus ice-margin habitats during the summer in
the Chukchi Sea are not available. However, belugas are commonly
associated with ice, so an inflation factor of 4 was used to estimate
the average ice-margin density from the open-water density. Very low
densities observed from vessels operating in the Chukchi Sea during
non-seismic periods and locations in July-August of 2006-2008 (0.0-
0.0001/km\2\; Haley et al. 2010) also suggest the number of beluga
whales likely to be present near the planned activities will not be
large (Table 2).
In the fall, beluga whale densities in the Chukchi Sea are expected
to be somewhat higher than in the summer because individuals of the
eastern Chukchi Sea stock and the Beaufort Sea stock will be migrating
south to their wintering grounds in the Bering Sea (Allen and Angliss
2010). However, there were no beluga sightings reported during > 18,000
km of vessel based effort in good visibility conditions during 2006-
2008 industry operations in the Chukchi Sea (Haley et al. 2010).
Densities derived from survey results in the northern Chukchi Sea in
Clarke and Ferguson (in prep.) were used as the average density for
open-water fall season estimates (see Table 3). Clarke and Ferguson (in
prep.) reported 3 beluga sightings (6 individuals) during 10,036 km of
on-transect effort in water depths 36-50 m. The mean group size of
those three sightings is 2 animals. A f(0) value of 2.841 and g(0)
value of 0.58 from Harwood et al. (1996) were used in the calculation.
Moore et al. (2000) reported lower than expected beluga sighting rates
in open-water during fall surveys in the Beaufort and Chukchi seas, so
an inflation value of 4 was used to estimate the average ice-margin
density from the open-water density. Based on the lack of any beluga
sightings from vessels operating in the Chukchi Sea during non-seismic
periods and locations in September-October of 2006-2008 (Haley et al.
2010), the relative low densities shown in Table 3 are consistent with
what is likely to be observed from vessels during the planned
operations.
Table 2--Expected Densities of Cetaceans and Seals in Areas of the
Chukchi Sea, Alaska, During the Planned Summer (July-August) Period of
the Shallow Hazards Survey Program
------------------------------------------------------------------------
Open water Ice margin
-----------------------------------
Species Average density Average density
(/ (/
km\2\) km\2\)
------------------------------------------------------------------------
Beluga whale........................ 0.0010 0.0040
Narwhal............................. 0.0000 0.0000
Killer whale........................ 0.0001 0.0001
Harbor porpoise..................... 0.0011 0.0011
Bowhead whale....................... 0.0013 0.0013
Fin whale........................... 0.0001 0.0001
Gray whale.......................... 0.0258 0.0258
Humpback whale...................... 0.0001 0.0001
Minke whale......................... 0.0001 0.0001
Bearded seal........................ 0.0107 0.0142
Ribbon seal......................... 0.0005 0.0005
Ringed seal......................... 0.3668 0.4891
Spotted seal........................ 0.0073 0.0098
------------------------------------------------------------------------
Table 3--Expected Densities of Cetaceans and Seals in Areas of the
Chukchi Sea, Alaska, During the Planned Fall (September-October) Period
of the Shallow Hazards Survey Program
------------------------------------------------------------------------
Open water Ice margin
-----------------------------------
Species Average density Average density
(/ (/
km\2\) km\2\)
------------------------------------------------------------------------
Beluga whale........................ 0.0015 0.0060
Narwhal............................. 0.0000 0.0000
Killer whale........................ 0.0001 0.0001
Harbor porpoise..................... 0.0001 0.0001
Bowhead whale....................... 0.0219 0.0438
Fin whale........................... 0.0001 0.0001
Gray whale.......................... 0.0080 0.0080
Humpback whale...................... 0.0001 0.0001
Minke whale......................... 0.0001 0.0001
Bearded seal........................ 0.0107 0.0142
[[Page 30123]]
Ribbon seal......................... 0.0005 0.0005
Ringed seal......................... 0.2458 0.3277
Spotted seal........................ 0.0049 0.0065
------------------------------------------------------------------------
Bowhead Whales--By July, most bowhead whales are northeast of the
Chukchi Sea, within or migrating toward their summer feeding grounds in
the eastern Beaufort Sea. No bowheads were reported during 10,684 km of
on-transect effort in the Chukchi Sea by Moore et al. (2000). Aerial
surveys in 2008-2010 by the NMML as part of the COMIDA project reported
six sightings during 25,781 km of on-transect effort (Clarke and
Ferguson 2011). Two of the six sightings were in waters <= 35 m deep
and the remaining four sightings were in waters 51-200 m deep. Bowhead
whales were also rarely sighted in July-August of 2006-2008 during
aerial surveys of the Chukchi Sea coast (Thomas et al. 2010). This is
consistent with movements of tagged whales (ADFG 2010) all of which
moved through the Chukchi Sea by early May 2009, and tended to travel
relatively close to shore, especially in the northern Chukchi Sea. The
estimate of summer bowhead whale density in the Chukchi Sea was
calculated by assuming there was one bowhead sighting during the 11,985
km of survey effort in waters 36-50 m deep in the Chukchi Sea during
July-August reported in Clarke and Ferguson (in prep.), although no
bowheads were actually observed during those surveys. The mean group
size from September-October sightings reported in Clarke and Ferguson
(in prep.) is 1.1, and this was also used in the calculation of summer
densities. The group size value, along with a f(0) value of 2 and a
g(0) value of 0.07, both from Thomas et al. (2002) were used to
estimate a summer density of bowhead whales (Table 2). Bowheads are not
expected to be encountered in higher densities near ice in the summer
(Moore et al. 2000), so the same density estimates are used for open-
water and ice-margin habitats. Densities from vessel based surveys in
the Chukchi Sea during non-seismic periods and locations in July-August
of 2006-2008 (Haley et al. 2010) ranged from 0.0001-0.0007/km\2\ with a
maximum 95 percent confidence interval (CI) of 0.0029/km\2\. This
suggests the densities used in the calculations and shown in Table 3
are somewhat higher than are likely to be observed from vessels near
the area of planned operations.
During the fall, bowhead whales that summered in the Beaufort Sea
and Amundsen Gulf migrate west and south to their wintering grounds in
the Bering Sea, making it more likely that bowheads will be encountered
in the Chukchi Sea at this time of year. Moore et al. (2000; Table 8)
reported 34 bowhead sightings during 44,354 km of on-transect survey
effort in the Chukchi Sea during September-October. Thomas et al.
(2010) also reported increased sightings on coastal surveys of the
Chukchi Sea during September and October of 2006-2008. GPS tagging of
bowheads appear to show that migration routes through the Chukchi Sea
are more variable than through the Beaufort Sea (Quakenbush et al.
2010). Some of the routes taken by bowheads remain well north of the
planned activities while others have passed near to or through the
area. Kernel densities estimated from GPS locations of whales suggest
that bowheads do not spend much time (e.g., feeding or resting) in the
north-central Chukchi Sea near the area of planned activities
(Quakenbush et al. 2010). Clarke and Ferguson (in prep.) reported 14
sightings (15 individuals) during 10,036 km of on transect aerial
survey effort in 2008-2010. The mean group size from those sightings is
1.1. The same f(0) and g(0) values that were used for the summer
estimates above were used for the fall estimates (Table 3). Moore et
al. (2000) found that Bowheads were detected more often than expected
in association with ice in the Chukchi Sea in September-October, so a
density of twice the average open-water density was used as the average
ice-margin density (Table 3). Densities from vessel based surveys in
the Chukchi Sea during non-seismic periods and locations in September-
October of 2006-2008 (Haley et al. 2010) ranged from 0.0003/km\2\ to
0.0044/km\2\ with a maximum 95 percent CI of 0.0419 km\2\. This
suggests the densities used in the calculations and shown in Table 3
are somewhat higher than are likely to be observed from vessels near
the area of planned operations.
Gray Whales--Gray whale densities are expected to be much higher in
the summer months than during the fall. Moore et al. (2000) found the
distribution of gray whales in the planned operational area was
scattered and generally limited to nearshore areas where most whales
were observed in water less than 35 m deep. Thomas et al. (2010) also
reported substantial declines in the sighting rates of gray whales in
the fall. The average open-water summer density (Table 2) was
calculated from effort and sightings reported by Clarke and Ferguson
(in prep.) for water depths 36-50 m including 54 sightings (73
individuals) during 11,985 km of on-transect effort. The average group
size of those sightings is 1.35 animals. Correction factors f(0) = 2.49
(Forney and Barlow 1998) and g(0) = 0.30 (Forney and Barlow 1998;
Mallonee 1991) were also used in the density calculation. Gray whales
are not commonly associated with sea ice, but may be present near it,
so the same densities were used for ice-margin habitat as were derived
for open-water habitat during both seasons. Densities from vessel based
surveys in the Chukchi Sea during non-seismic periods and locations in
July-August of 2006-2008 (Haley et al. 2010) ranged from 0.0021/km\2\
to 0.0080/km\2\ with a maximum 95 percent CI of 0.0336 km\2\.
In the fall, gray whales may be dispersed more widely through the
northern Chukchi Sea (Moore et al. 2000), but overall densities are
likely to be decreasing as the whales begin migrating south. A density
calculated from effort and sightings (15 sightings [19 individuals]
during 10,036 km of on-transect effort) in water 36-50 m deep during
September-October reported by Clarke and Ferguson (in prep.) was used
as the average estimate for the Chukchi Sea during the fall period
(Table 3). The corresponding group size value of 1.26, along with the
same f(0) and g(0) values described above were also used in the
calculation. Densities from vessel based surveys in the Chukchi Sea
during non-seismic periods and locations in July-
[[Page 30124]]
August of 2006-2008 (Haley et al. 2010) ranged from 0.0026/km\2\ to
0.0042/km\2\ with a maximum 95 percent CI of 0.0277 km\2\.
Harbor Porpoise--Harbor Porpoise densities were estimated from
industry data collected during 2006-2008 activities in the Chukchi Sea.
Prior to 2006, no reliable estimates were available for the Chukchi Sea
and harbor porpoise presence was expected to be very low and limited to
nearshore regions. Observers on industry vessels in 2006-2008, however,
recorded sightings throughout the Chukchi Sea during the summer and
early fall months. Density estimates from 2006-2008 observations during
non-seismic periods and locations in July-August ranged from 0.0008/
km\2\ to 0.0015/km\2\ with a maximum 95 percent CI of 0.0079/km\2\
(Haley et al. 2010). The average of those three years (0.0011/km\2\)
was used as the average open-water density estimate while the high
value (0.0015/km\2\) was used as the maximum estimate (Table 2). Harbor
porpoise are not expected to be present in higher numbers near ice, so
the open-water densities were used for ice-margin habitat in both
seasons. Harbor porpoise densities recorded during industry operations
in the fall months of 2006-2008 were slightly lower than the summer
months and ranged from 0.0002/km\2\ to 0.0010/km\2\ with a maximum 95
percent CI of 0.0093/km\2\. The average of those three years (0.0001/
km\2\) was again used as the average density estimate and the high
value 0.0011/km\2\ was used as the maximum estimate (Table 3).
Other Cetaceans--The remaining five cetacean species that could be
encountered in the Chukchi Sea during Statoil's planned activities
include the humpback whale, killer whale, minke whale, fin whale, and
narwhal. Although there is evidence of the occasional occurrence of
these animals in the Chukchi Sea, it is unlikely that more than a few
individuals will be encountered during the planned activities. George
and Suydam (1998) reported killer whales, Brueggeman et al. (1990) and
Haley et al. (2010) reported minke whale, and COMIDA (2009) and Haley
et al. (2010) reported fin whales. Narwhal sightings in the Chukchi Sea
have not been reported in recent literature, but subsistence hunters
occasionally report observations near Barrow, and Reeves et al. (2002)
indicated a small number of extralimital sightings in the Chukchi Sea.
(2) Pinnipeds
Four species of pinnipeds may be encountered in the Chukchi Sea:
Ringed seal, bearded seal, spotted seal, and ribbon seal. Each of these
species, except the spotted seal, is associated with both the ice
margin and the nearshore area. The ice margin is considered preferred
habitat (as compared to the nearshore areas) during most seasons.
Ringed and Bearded Seals--Ringed seal and bearded seal summer ice-
margin densities (Table 2) were taken from Bengtson et al. (2005) who
conducted spring surveys in the offshore pack ice zone (zone 12P) of
the northern Chukchi Sea. However, a correction for bearded seal
availability bias, g(0), based on haulout and diving patterns was not
available and used in the reported densities. Densities of ringed and
bearded seals in open water are expected to be somewhat lower in the
summer when preferred pack ice habitat may still be present in the
Chukchi Sea. Average and maximum open-water densities have been
estimated as \3/4\ of the ice margin densities during both seasons for
both species. The fall density of ringed seals in the offshore Chukchi
Sea has been estimated as \2/3\ the summer densities because ringed
seals begin to reoccupy nearshore fast ice areas as it forms in the
fall. Bearded seals may also begin to leave the Chukchi Sea in the
fall, but less is known about their movement patterns so fall densities
were left unchanged from summer densities. For comparison, the ringed
seal density estimates calculated from data collected during summer
2006-2008 industry operations ranged from 0.0158/km\2\ to 0.0687/km\2\
with a maximum 95 percent CI of 0.1514/km\2\ (Haley et al. 2010). These
estimates are lower than those made by Bengtson et al. (2005) which is
not surprising given the different survey methods and timing.
Spotted Seal--Little information on spotted seal densities in
offshore areas of the Chukchi Sea is available. Spotted seal densities
in the summer were estimated by multiplying the ringed seal densities
by 0.02. This was based on the ratio of the estimated Chukchi
populations of the two species. Chukchi Sea spotted seal abundance was
estimated by assuming that 8 percent of the Alaskan population of
spotted seals is present in the Chukchi Sea during the summer and fall
(Rugh et al. 1997), the Alaskan population of spotted seals is 59,214
(Allen and Angliss 2010), and that the population of ringed seals in
the Alaskan Chukchi Sea is ~208,000 animals (Bengtson et al. 2005). In
the fall, spotted seals show increased use of coastal haulouts so
densities in offshore areas were estimated to be \2/3\ of the summer
densities.
Ribbon Seal--Two ribbon seal sightings were reported during
industry vessel operations in the Chukchi Sea in 2006-2008 (Haley et
al. 2010). The resulting density estimate of 0.0005/km\2\ was used as
the average density.
Potential Number of Takes by Harassment
This subsection provides estimates of the number of individuals
potentially exposed to sound levels >= 160 dBrms re 1 [mu]Pa
by pulsed airgun sounds and to >= 120 dBrms re 1 [mu]Pa by
non-impulse sounds during geotechnical soil investigations. The
estimates are based on a consideration of the number of marine mammals
that might be disturbed appreciably by operations in the Chukchi Sea
and the anticipated area exposed to those sound levels.
The number of individuals of each species potentially exposed to
received levels of pulsed sounds >= 160 dBrms re 1 [mu]Pa or
to >= 120 dBrms re 1 [mu]Pa by continuous sounds within each
season and habitat zone was estimated by multiplying
The anticipated area to be ensonified to the specified
level in each season and habitat zone to which that density applies, by
The expected species density.
The numbers of individuals potentially exposed were then summed for
each species across the two seasons and habitat zones. Some of the
animals estimated to be exposed, particularly migrating bowhead whales,
might show avoidance reactions before being exposed to pulsed airgun
sounds >= 160 dBrms re 1 [micro]Pa. Thus, these calculations
actually estimate the number of individuals potentially exposed to the
specified sound levels that would occur if there were no avoidance of
the area ensonified to that level.
Site survey and geotechnical soil investigations are planned to
occur primarily in August and September, with the potential to continue
into mid-November, if necessary and weather permitting. For the
purposes of assigning activities to the summer (August) and fall
(September-October) periods for which densities have been estimated
above, we have assumed that half of the operations will occur during
the summer period and half will occur in the fall period. Additionally,
the planned activities cannot be completed in or near significant
amounts of sea ice, so 90% of the activity each season (and associated
ensonified areas) has been multiplied by the open-water densities
described above, while the remaining 10% of activity has been
multiplied by the ice-margin densities.
[[Page 30125]]
Species with an estimated average number of individuals exposed
equal to zero are included below for completeness, but are not likely
to be encountered.
(1) Shallow Hazards and Site Clearance Surveys
The estimated numbers of marine mammals potentially exposed to
airgun sounds with received levels >= 160 dBrms from site
surveys on Statoil's leases are shown in Table 4. The average estimate
of the number of individual bowhead whales exposed to received sound
levels >= 160 dB is 11. The average estimate for gray whales is
slightly greater at 18, while few belugas are expected to be exposed
(Table 4). Few other cetaceans (such as narwhal, harbor porpoise,
killer, humpback, fin, and minke whales) are likely to be exposed to
airgun sounds >= 160 dB, but estimates have been included to account
for chance encounters.
Ringed seals are expected to be the most abundant animal in the
Chukchi Sea during this period and the average estimate of the number
exposed to >= 160 dB by site survey activities is 337 (Table 4).
Estimated exposures of other seal species are substantially below those
for ringed seals (Table 4).
Table 4--Summary of the Number of Marine Mammals in Areas Where Maximum Received Sound Levels in the Water Would
Be >= 160 dB in Summer (Aug) and Fall (Sep-Oct) Periods During Statoil's Planned Site Surveys in the Chukchi
Sea, Alaska. Not All Marine Mammals Are Expected To Change Their Behavior When Exposed to These Sound Levels
----------------------------------------------------------------------------------------------------------------
Number of individuals exposed to sound levels >= 160 dB
-------------------------------------------------------------------------------
Species Summer Fall
---------------------------------------------------------------- Total
Open water Ice margin Open water Ice margin
----------------------------------------------------------------------------------------------------------------
Beluga whale.................... 0 0 1 0 2
Narwhal......................... 0 0 0 0 2
Killer whale.................... 0 0 0 0 2
Harbor porpoise................. 1 0 0 0 1
Bowhead whale................... 1 0 10 0 11
Gray whale...................... 12 1 4 1 18
Humpback whale.................. 0 0 0 0 2
Fin whale....................... 0 0 0 0 2
Minke whale..................... 0 0 0 0 2
Bearded seal.................... 5 1 5 1 12
Ribbon seal..................... 0 0 0 0 1
Ringed seal..................... 171 25 115 25 337
Spotted seal.................... 3 1 2 1 7
----------------------------------------------------------------------------------------------------------------
(2) Geotechnical Soil Investigations
The estimated numbers of marine mammals potentially exposed to
continuous sounds with received levels >= 120 dBrms from
geotechnical soil investigations on Statoil's leases and jointly owned
leases are shown in Table 5. The average estimate of the number of
individual bowhead whales exposed to received sound levels >= 120 dB is
15. The average estimate for gray whales is slightly larger at 26
individuals (Table 5). Few other cetaceans (such as narwhal, harbor
porpoise, killer, humpback, fin, and minke whales) are likely to be
exposed to soil investigation sounds >= 120 dB, but estimates have been
included to account for chance encounters.
The average estimate of the number of ringed seals potentially
exposed to >=120 dB by soil investigation activities is 467 (Table 5).
Estimated exposures of other seal species are substantially below those
for ringed seals (Table 5).
Table 5--Summary of the Number of Marine Mammals in Areas Where Maximum Received Sound Levels in the Water Would
Be >= 120 dB in Summer (Aug) and Fall (Sep-Oct) Periods During Statoil's Planned Geotechnical Soil
Investigations in the Chukchi Sea, Alaska. Not All Marine Mammals Are Expected To Change Their Behavior When
Exposed to These Sound Levels
----------------------------------------------------------------------------------------------------------------
Number of individuals exposed to sound levels >= 120 dB
-------------------------------------------------------------------------------
Species Summer Fall
---------------------------------------------------------------- Total
Open water Ice margin Open water Ice margin
----------------------------------------------------------------------------------------------------------------
Beluga whale.................... 1 0 1 0 2
Narwhal......................... 0 0 0 0 3
Killer whale.................... 0 0 0 0 3
Harbor porpoise................. 1 0 0 0 1
Bowhead whale................... 1 0 14 0 15
Gray whale...................... 17 2 5 2 26
Humpback whale.................. 0 0 0 0 3
Fin whale....................... 0 0 0 0 3
Minke whale..................... 0 0 0 0 3
Bearded seal.................... 7 1 7 1 16
Ribbon seal..................... 0 0 0 0 1
Ringed seal..................... 238 35 159 35 467
Spotted seal.................... 5 1 3 1 10
----------------------------------------------------------------------------------------------------------------
[[Page 30126]]
Estimated Take Conclusions
Cetaceans--Effects on cetaceans are generally expected to be
restricted to avoidance of an area around the seismic survey and short-
term changes in behavior, falling within the MMPA definition of ``Level
B harassment''.
Using the 160 dB criterion, the average estimates of the numbers of
individual cetaceans exposed to sounds < 160 dBrms re 1
[mu]Pa represent varying proportions of the populations of each species
in the Beaufort Sea and adjacent waters. For species listed as
``Endangered'' under the ESA, the estimates include approximately 26
bowheads. This number is approximately 0.18% of the Bering-Chukchi-
Beaufort population of > 14,247 assuming 3.4% annual population growth
from the 2001 estimate of > 10,545 animals (Zeh and Punt 2005). For
other cetaceans that might occur in the vicinity of the shallow hazards
survey in the Chukchi Sea, they also represent a very small proportion
of their respective populations. The average estimates of the number of
belugas, killer whales, harbor porpoises, gray whales, humpback whales,
fin whales, and minke whales that might be exposed to <160 dB and 120
dB re 1 [mu]Pa are 4, 5, 2, 44, 5, 5, and 5. These numbers represent
0.11%, 1.59%, 0.004%, 0.25%, 0.53%, 0.09%, and 0.50% of these species
of their respective populations in the proposed action area. No
population estimates of narwhal are available in U.S. waters due to its
extralimital distribution here. The world population of narwhal is
estimated at 75,000 (Laidre et al. 2008), and most of them are
concentrated in the fjords and inlets of Northern Canada and western
Greenland. The estimated take of 5 narwhals represents approximately
0.01% of its population.
Seals--A few seal species are likely to be encountered in the study
area, but ringed seal is by far the most abundant in this area. The
average estimates of the numbers of individuals exposed to sounds at
received levels <160 dBrms re 1 [mu]Pa during the proposed
shallow hazards survey are as follows: ringed seals (803), bearded
seals (28), spotted seals (17), and ribbon seals (2). These numbers
represent 0.35%, 0.01%, 0.03%, and 0.002% of Alaska stocks of ringed,
bearded, spotted, and ribbon seals, respectively.
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
Statoil's proposed 2011 open water marine shallow hazards surveys in
the Chukchi Seas, and none are proposed to be authorized. In addition,
these surveys would use a small 40 in\3\ airgun array and several mid-
to high-frequency active acoustic sources. The acoustic power output is
much lower than full scale airgun arrays used in a 2D or 3D seismic
survey, and thus generates much lower source levels. The modeled
isopleths at 160 dB is expected to be less than 2.25 km from the source
(see discussion earlier). 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 of marine
mammals may be exposed to sounds from shallow hazards survey activities
more than once, the expanse of these multi-exposures are expected to be
less extensive since both the animals and the survey vessels will be
moving constantly in and out of the survey areas.
Most of the bowhead whales encountered during the summer will
likely show overt disturbance (avoidance) only if they receive airgun
sounds with levels >= 160 dB re 1 [mu]Pa. Odontocete reactions to
seismic energy pulses are usually assumed to be limited to shorter
distances from the airgun(s) than are those of mysticetes, probably in
part because odontocete low-frequency hearing is assumed to be less
sensitive than that of mysticetes. However, at least when in the
Canadian Beaufort Sea in summer, belugas appear to be fairly responsive
to seismic energy, with few being sighted within 6-12 mi (10-20 km) of
seismic vessels during aerial surveys (Miller et al. 2005). Belugas
will likely occur in small numbers in the Chukchi Sea during the survey
period and few will likely be affected by the survey activity. In
addition, due to the constant moving of the survey vessel, the duration
of the noise exposure by cetaceans to seismic impulse would be brief.
For the same reason, it is unlikely that any individual animal would be
exposed to high received levels multiple times.
For animals exposed to machinery noise from geotechnical oil
investigations, NMFS considers that at received levels >= 120 dB re 1
[mu]Pa, the animals could respond behaviorally in a manner that NMFS
considers Level B harassment due to the non-pulse nature of the noise
involved in this activity. During soil investigation operations, the
most intensive noise source is from the dynamic positioning (DP) system
that automatically controls and coordinates vessel movements using bow
and/or stern thrusters. Measurements of a similar vessel in DP mode in
the Chukchi Sea in 2010 provided an estimated source level at about 176
dB re 1 [mu]Pa, which is below what NMFS uses to assess Level A
harassment of received levels at 180 dB for cetaceans and 190 dB for
pinnipeds. In addition, the duration of the entire geotechnical oil
investigation is approximately 14 days, and DP will only be running
sporadically when needed to position the vessel. In addition, the oil
investigation operations are expected to be stationary, with limited
area to be ensonified. Therefore, the impacts to marine mammals in the
vicinity of the oil investigation operations are expected to be in
short duration and localized.
Taking into account the mitigation measures that are planned,
effects on cetaceans are generally expected to be restricted to
avoidance of a limited area around the survey operation and short-term
changes in behavior, falling within the MMPA definition of ``Level B
harassment''.
Furthermore, the estimated numbers of animals potentially exposed
to sound levels sufficient to cause appreciable disturbance are very
low percentages of the population sizes in the Bering-Chukchi-Beaufort
seas, as described above.
The many reported cases of apparent tolerance by cetaceans of
seismic exploration, vessel traffic, and some other human activities
show that co-existence is possible. Mitigation measures such as
controlled vessel speed, dedicated marine mammal observers, non-
pursuit, and shut downs or power downs when marine mammals are seen
within defined ranges will further reduce short-term reactions and
minimize any effects on hearing sensitivity. In all cases, the effects
are expected to be short-term, with no lasting biological consequence.
Some individual pinnipeds may be exposed to sound from the proposed
marine surveys more than once during
[[Page 30127]]
the time frame of the project. However, as discussed previously, due to
the constant moving of the survey vessel, the probability of an
individual pinniped being exposed to sound multiple times is much lower
than if the source is stationary. Therefore, NMFS has preliminarily
determined that the exposure of pinnipeds to sounds produced by the
proposed shallow hazards surveys and soil investigation in the Chukchi
Sea 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 thirteen marine mammal species likely to occur in the
proposed marine survey area, only the bowhead, fin, and humpback whales
are listed as endangered under the ESA. These species are also
designated as ``depleted'' under the MMPA. Despite these designations,
the Bering-Chukchi-Beaufort stock of bowheads has been increasing at a
rate of 3.4 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). The occurrence of fin and humpback whales in the
proposed marine survey areas is considered very rare. There is no
critical habitat designated in the U.S. Arctic for the bowhead, fin,
and humpback 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 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 marine survey
activities, any missed feeding opportunities in the direct project area
would be minor based on the fact that other feeding areas exist
elsewhere.
The estimated takes proposed to be authorized represent 0.11% of
the Eastern Chukchi Sea population of approximately 3,710 beluga whales
(Allen and Angliss 2010), 1.59% of Aleutian Island and Bering Sea stock
of approximately 314 killer whales, 0.004% of Bering Sea stock of
approximately 48,215 harbor porpoises, 0.25% of the Eastern North
Pacific stock of approximately 17,752 gray whales, 0.18% of the Bering-
Chukchi-Beaufort population of 14,247 bowhead whales assuming 3.4
percent annual population growth from the 2001 estimate of 10,545
animals (Zeh and Punt, 2005), 0.53% of the Western North Pacific stock
of approximately 938 humpback whales, 0.09% of the North Pacific stock
of approximately 5,700 fin whales, and 0.50% of the Alaska stock of
approximately 1,003 minke whales. The take estimates presented for
bearded, ringed, spotted, and ribbon seals represent 0.01, 0.35, 0.03,
and 0.002 percent of U.S. Arctic stocks of 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. In addition, 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 Statoil's proposed 2011 open
water shallow hazards survey in the Chukchi Sea may result in the
incidental take of small numbers of marine mammals, by Level B
harassment only, and that the total taking from the marine surveys 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 the proposed marine surveys are the principal concerns
related to subsistence use of the area. Subsistence remains the basis
for Alaska Native culture and community. Subsistence hunting and
fishing continue to be prominent in the household economies and social
welfare of some Alaskan residents, particularly among those living in
small, rural villages (Wolfe and Walker 1987). 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. (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.
Marine mammals are legally hunted in Alaskan waters by coastal
Alaska Natives; species hunted include bowhead and beluga whales;
ringed, spotted, and bearded seals; walruses, and polar bears. The
importance of each of the various species varies among the communities
based largely on availability. Bowhead whales, belugas, and walruses
are the marine mammal species primarily harvested during the time of
the proposed shallow hazard survey. There is little or no bowhead
hunting by the community of Point Lay, so beluga and walrus hunting are
of more importance there. Members of the Wainwright community hunt
bowhead whales in the spring, although bowhead whale hunting conditions
there are often more difficult than elsewhere, and they do not hunt
bowheads during seasons when Statoil's survey operation would occur.
Depending on the level of success during the spring bowhead hunt,
Wainwright residents may be very dependent on the presence of belugas
in a nearby lagoon system during July and August. Barrow residents
focus hunting efforts on bowhead whales during the spring and generally
do not hunt beluga then. However, Barrow residents also hunt in the
fall, when Statoil expects to be conducting shallow hazards surveys
(though not near Barrow).
(1) Bowhead Whales
Bowhead whale hunting is a key activity in the subsistence
economies of northwest Arctic communities. The whale harvests have a
great influence on social relations by strengthening the sense of
Inupiat culture and heritage in addition to reinforcing family and
community ties.
An overall quota system for the hunting of bowhead whales was
established by the International Whaling Commission (IWC) in 1977. The
quota is now regulated through an agreement between NMFS and the Alaska
Eskimo Whaling Commission (AEWC). The AEWC allots the number of bowhead
whales that each whaling community may harvest annually (USDI/BLM
2005). The annual take of bowhead whales has varied due to (a) changes
in the allowable quota level and (b) year-to-
[[Page 30128]]
year variability in ice and weather conditions, which strongly
influence the success of the hunt.
Bowhead whales migrate around northern Alaska twice each year,
during the spring and autumn, and are hunted in both seasons. Bowhead
whales are hunted from Barrow during the spring and the fall migration
and animals are not successfully harvested every year. The spring hunt
along Chukchi villages and at Barrow occurs after leads open due to the
deterioration of pack ice; the spring hunt typically occurs from early
April until the first week of June. The fall migration of bowhead
whales that summer in the eastern Beaufort Sea typically begins in late
August or September. Fall migration into Alaskan waters is primarily
during September and October.
In the fall, subsistence hunters use aluminum or fiberglass boats
with outboards. Hunters prefer to take bowheads close to shore to avoid
a long tow during which the meat can spoil, but Braund and Moorehead
(1995) report that crews may (rarely) pursue whales as far as 50 mi (80
km). The autumn bowhead hunt usually begins in Barrow in mid-September,
and mainly occurs in the waters east and northeast of Point Barrow.
The scheduling of this shallow hazard survey has been discussed
with representatives of those concerned with the subsistence bowhead
hunt, most notably the AEWC, the Barrow Whaling Captains' Association,
and the North Slope Borough (NSB) Department of Wildlife Management.
The planned mobilization and start date for shallow hazards surveys
in the Chukchi Sea (~25 July and ~1 August, respectively) is well after
the end of the spring bowhead migration and hunt at Wainwright and
Barrow. Shallow hazards survey and soil investigation operations will
be conducted far offshore from Barrow and Wainwright are not expected
to conflict with subsistence hunting activities. Specific concerns of
the Barrow whaling captains are addressed as part of the Plan of
Cooperation/Conflict Avoidance Agreement that is being negotiated with
the AEWC (see below).
(2) Beluga Whales
Beluga whales are available to subsistence hunters along the coast
of Alaska in the spring when pack-ice conditions deteriorate and leads
open up. Belugas may remain in coastal areas or lagoons through June
and sometimes into July and August. The community of Point Lay is
heavily dependent on the hunting of belugas in Kasegaluk Lagoon for
subsistence meat. From 1983-1992 the average annual harvest was ~40
whales (Fuller and George 1997). In Wainwright and Barrow, hunters
usually wait until after the spring bowhead whale hunt is finished
before turning their attention to hunting belugas. The average annual
harvest of beluga whales taken by Barrow for 1962-1982 was five (MMS
1996). The Alaska Beluga Whale Committee recorded that 23 beluga whales
had been harvested by Barrow hunters from 1987 to 2002, ranging from 0
in 1987, 1988 and 1995 to the high of 8 in 1997 (Fuller and George
1997; Alaska Beluga Whale Committee 2002 in USDI/BLM 2005). The seismic
survey activities take place well offshore, far away from areas that
are used for beluga hunting by the Chukchi Sea communities.
(3) Ringed Seals
Ringed seals are hunted mainly from October through June. Hunting
for these smaller mammals is concentrated during winter because bowhead
whales, bearded seals and caribou are available through other seasons.
In winter, leads and cracks in the ice off points of land and along the
barrier islands are used for hunting ringed seals. The average annual
ringed seal harvest was 49 seals in Point Lay, 86 in Wainwright, and
394 in Barrow (Braund et al. 1993; USDI/BLM 2003; 2005). Although
ringed seals are available year-round, the planned activities will not
occur during the primary period when these seals are typically
harvested. Also, the activities will be largely in offshore waters
where the activities will not influence ringed seals in the nearshore
areas where they are hunted.
(4) Spotted Seals
The spotted seal subsistence hunt peaks in July and August along
the shore where the seals haul out, but usually involves relatively few
animals. Spotted seals typically migrate south by October to overwinter
in the Bering Sea. During the fall migration spotted seals are hunted
by the Wainright and Point Lay communities as the seals move south
along the coast (USDI/BLM 2003). Spotted seals are also occasionally
hunted in the area off Point Barrow and along the barrier islands of
Elson Lagoon to the east (USDI/BLM 2005). The planned activities will
remain offshore of the coastal harvest area of these seals and should
not conflict with harvest activities.
(5) Bearded Seals
Bearded seals, although generally not favored for their meat, are
important to subsistence activities in Barrow and Wainright, because of
their skins. Six to nine bearded seal hides are used by whalers to
cover each of the skin-covered boats traditionally used for spring
whaling. Because of their valuable hides and large size, bearded seals
are specifically sought. Bearded seals are harvested during the spring
and summer months in the Chukchi Sea (USDI/BLM 2003; 2005). The animals
inhabit the environment around the ice floes in the drifting nearshore
ice pack, so hunting usually occurs from boats in the drift ice. Most
bearded seals are harvested in coastal areas inshore of the proposed
survey so no conflicts with the harvest of bearded seals are expected.
In the event that both marine mammals and hunters are near the
areas of planned operations, the proposed project potentially could
impact the availability of marine mammals for harvest in a small area
immediately around the vessel, in the case of pinnipeds, and possibly
in a large area in the case of migrating bowheads. However, the
majority of marine mammals are taken by hunters within ~21 mi (~33 km)
from shore, and the survey activities will occur far offshore, well
outside the hunting areas. Considering the timing and location of the
proposed shallow hazards survey activities, as described earlier in the
document, the proposed project is not expected to have any significant
impacts to the availability of marine mammals for subsistence harvest.
Specific concerns of the respective communities are addressed as part
of the Plan of Cooperation between Statoil and the AEWC.
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 Statoil's proposed open water
shallow hazards survey 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
[[Page 30129]]
normal migratory path by several kilometers. 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 Chukchi
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.
In addition, Native knowledge indicates that bowhead whales become
increasingly ``skittish'' in the presence of seismic noise. Whales are
more wary around the hunters and tend to expose a much smaller portion
of their back when surfacing (which makes harvesting more difficult).
Additionally, natives report that bowheads exhibit angry behaviors in
the presence of seismic, such as tail-slapping, which translate to
danger for nearby subsistence harvesters.
Plan of Cooperation (POC or Plan)
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.
Statoil states that it intends to maintain an open and transparent
process with all stakeholders throughout the life-cycle of activities
in the Chukchi Sea. Statoil began the stakeholder engagement process in
2009 with meeting Chukchi Sea community leaders at the tribal, city,
and corporate level. Statoil will continue to engage with leaders,
community members, and subsistence groups, as well as local, state, and
federal regulatory agencies throughout the exploration and development
process.
As part of stakeholder engagement, Statoil is developing a Plan of
Cooperation (POC) for the proposed 2011 activities. The POC summarizes
the actions Statoil will take to identify important subsistence
activities, inform subsistence users of the proposed survey activities,
and obtain feedback from subsistence users regarding how to promote
cooperation between subsistence activities and the Statoil program.
During the early phase of the POC process for the proposed project,
Statoil met with the North Slope Borough Department of Wildlife
Management (Dec 2010) and the AEWC (mini-convention in Barrow, Feb
2011). Statoil also arranged to visit and hold public meetings in the
affected Chukchi Sea villages, including Pt. Hope, Pt. Lay, Wainwright,
and Barrow during the week of 21 March, 2011.
Based upon these meetings, a draft POC document is being developed.
Upon completion, the draft POC will be submitted to each of the
community leaders Statoil visited during the March meetings as well as
other interested community members. Statoil will also submit the draft
POC to NMFS, USFWS, and BOEMRE.
A final POC that documents all consultations with community
leaders, subsistence user groups, individual subsistence users, and
community members will be submitted to NMFS, USFWS, and BOEMRE upon
completion of consultations.
Subsistence Mitigation Measures
Statoil plans to introduce the following mitigation measures, plans
and programs to potentially affected subsistence groups and
communities. These measures, plans, and programs have been effective in
past seasons of work in the Arctic and were developed in past
consultations with these communities.
Statoil will not be entering the Chukchi Sea until early August, so
there will be no potential conflict with spring bowhead whale or beluga
subsistence whaling in the polynya zone. Statoil's planned activities
area is ~100 mi (~ 161 km) northwest of Wainwright which reduces the
potential impact to subsistence hunting activities occurring along the
Chukchi Sea coast.
The communication center in Wainwright will be jointly funded by
Statoil and other operators, and Statoil will routinely call the
communication center according to the established protocol while in the
Chukchi Sea. Depending on survey progress, Statoil may perform a crew
change in the Nome area in Alaska. The crew change will not involve the
use of helicopters. Statoil does have a contingency plan for a
potential transfer of a small number of crew via ship-to-shore vessel
at Wainwright. If this should become necessary, the Wainwright
communications center will be contacted to determine the appropriate
vessel route and timing to avoid potential conflict with subsistence
users.
Prior to survey activities, Statoil will identify transit routes
and timing to avoid other subsistence use areas and communicate with
coastal communities before operating in or passing through these areas.
Unmitigable Adverse Impact Analysis and Preliminary Determination
NMFS has preliminarily determined that Statoil's proposed 2011 open
water shallow hazards survey in the Chukchi Sea 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 Statoil's draft
POC. Statoil has adopted a spatial and temporal strategy for its
Chukchi Sea operations that should minimize impacts to subsistence
hunters. Statoil will enter the Chukchi Sea far offshore, so as to not
interfere with July hunts in the Chukchi Sea villages. After the close
of the July beluga whale hunts in the Chukchi Sea villages, very little
whaling occurs in Wainwright, Point Hope, and Point Lay. Although the
fall bowhead whale hunt in Barrow will occur while Statoil is still
operating (mid- to late September to October), Barrow is approximately
150 mi (241 km) east of the eastern boundary of the proposed shallow
hazards survey site. Based on these factors, Statoil's Chukchi Sea
shallow hazards survey is not expected to interfere with the fall
bowhead harvest in Barrow. In recent years, bowhead whales have
occasionally been taken in the fall by coastal villages along the
Chukchi coast, but the total number of these animals has been small.
Adverse impacts are not anticipated on sealing activities since the
majority of hunts for seals occur in the winter and spring, when
Statoil will not be operating. Additionally, most sealing activities
occur much closer to shore than Statoil's proposed shallow hazards
survey area.
Based on the measures described in Statoil'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 Statoil's open water shallow hazards survey in
the Chukchi Sea.
Endangered Species Act (ESA)
There are three marine mammal species listed as endangered under
the ESA with confirmed or possible occurrence in the proposed project
area: The bowhead, humpback, and fin whales. NMFS' Permits,
Conservation and Education Division has initiated consultation with
NMFS' Protected
[[Page 30130]]
Resources Division under section 7 of the ESA on the issuance of an IHA
to Statoil 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)
In 2010, NMFS prepared an Environmental Assessment (EA) and issued
findings of no significant impact (FONSIs) for open-water seismic and
marine surveys in the Beaufort and Chukchi seas by Shell and Statoil. A
review of Statoil's proposed 2011 open-water shallow hazards surveys
indicates that the planned action is essentially the same as the marine
survey conducted by Shell in 2010, but on a smaller scale. In addition,
the review indicated that there is no significant change in the
environmental baselines from what were analyzed in 2010. Therefore,
NMFS is preparing a Supplemental EA which incorporates by reference the
2010 EA and other related documents, and updates the activity to
reflect the lower impacts compared to the previous season.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
authorize the take of marine mammals incidental to Statoil's 2011 open
water shallow hazards survey in the Chukchi Sea, Alaska, provided the
previously mentioned mitigation, monitoring, and reporting requirements
are incorporated.
Dated: May 17, 2011.
James H. Lecky,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2011-12666 Filed 5-23-11; 8:45 am]
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