[Federal Register Volume 75, Number 130 (Thursday, July 8, 2010)]
[Notices]
[Pages 39336-39364]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-16374]
[[Page 39335]]
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Part II
Department of Commerce
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National Oceanic and Atmospheric Administration
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Incidental Takes of Marine Mammals During Specified Activities; Marine
Seismic Survey in the Arctic Ocean, August to September, 2010; Notice
Federal Register / Vol. 75 , No. 130 / Thursday, July 8, 2010 /
Notices
[[Page 39336]]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XW05
Incidental Takes of Marine Mammals During Specified Activities;
Marine Seismic Survey in the Arctic Ocean, August to September, 2010
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental take authorization; request for
comments.
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SUMMARY: NMFS has received an application from the U.S. Geological
Survey (USGS) for an Incidental Harassment Authorization (IHA) to take
small numbers of marine mammals, by harassment, incidental to
conducting a marine seismic survey in the Arctic Ocean during August to
September, 2010. Pursuant to the Marine Mammal Protection Act (MMPA),
NMFS requests comments on its proposal to authorize USGS to
incidentally take, by Level B harassment only, small numbers of marine
mammals during the aforementioned activity.
DATES: Comments and information must be received no later than August
9, 2010.
ADDRESSES: Comments on the application should be addressed to P.
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.
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 containing a list of the references used
in this document may be obtained by writing to the address specified
above, telephoning the contact listed below (see FOR FURTHER
INFORMATION CONTACT), or visiting the Internet at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm. Documents cited in this
notice may be viewed, by appointment, during regular business hours, at
the aforementioned address.
FOR FURTHER INFORMATION CONTACT: Howard Goldstein or Jolie Harrison,
Office of Protected Resources, NMFS, 301-713-2289.
SUPPLEMENTARY INFORMATION:
Background
Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.)
direct the Secretary of Commerce (Secretary) to allow, upon request,
the incidental, but not intentional, taking of marine mammals by United
States citizens who engage in a specified activity (other than
commercial fishing) within a specified geographical region if certain
findings are made and either regulations are issued or, if the taking
is limited to harassment, a notice of a proposed authorization is
provided to the public for review.
An authorization for incidental taking of small numbers of marine
mammals 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, 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 United States can apply for an authorization
not to exceed one year to incidentally take small numbers of marine
mammals by harassment. Except with respect to certain activities not
pertinent here, the MMPA defines ``harassment'' as:
Any act of pursuit, torment, or annoyance which (i) has the
potential to injure a marine mammal or marine mammal stock in the
wild [``Level A harassment'']; or (ii) has the potential to disturb
a marine mammal or marine mammal stock in the wild by causing
disruption of behavioral patterns, including, but not limited to,
migration, breathing, nursing, breeding, feeding, or sheltering
[``Level B harassment''].
16 U.S.C. 1362(18)
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 for any proposed authorizations for the incidental harassment of
marine mammals. Within 45 days of the close of the comment period,
NMFS, MMPA must either issue or deny the authorization.
Summary of Request
On March 9, 2010, NMFS received an IHA application and an
Environmental Assessment (EA) from USGS for the taking, by Level B
harassment only, of small numbers of several species of marine mammals
incidental to conducting a marine seismic survey in the Arctic Ocean
during August to September, 2010. NMFS received a revised IHA
application and a revised EA on June 1, 2010.
Description of the Specified Activity
USGS plans to conduct a marine geophysical (seismic reflection/
refraction) and bathymetric survey in the Arctic Ocean in August and
September, 2010 (see Tables 1 and 2, and Figure 3 of the IHA
application). The survey will be conducted from the Canadian Coast
Guard (CCG) vessel CCGS Louis S. St. Laurent (St. Laurent) which will
be accompanied by the U.S. Coast Guard Cutter (USCGC) Healy, both of
which are polar-class icebreakers. Descriptions of the vessels and
their specifications are presented in Appendix A of the IHA
application. The two vessels will operate in tandem in the presence of
ice but may diverge and operate independently in open water. Some minor
deviation of the dates is possible, depending on logistics and weather
(i.e., the cruise may depart earlier or be extended due to poor
weather; there could be extra days of seismic operations if collected
data are of sub-standard quality).
One CCG helicopter will be available for deployment from the St.
Laurent for ice reconnaissance and crew transfers between the vessels
during survey operations. Helicopters transfer of crew from the Healy
is also planned for approximately one day during a ship-to-shore crew
change at Barrow, Alaska at the end of the survey. The helicopter
operations in Barrow will be conducted under Department of Interior
(DOI) contract. Daily helicopter operations are anticipated pending
weather conditions. Spot bathymetry will also be conducted from the
helicopter outside U.S. waters.
Acoustic sources onboard the St. Laurent will include an airgun
array comprised of three Sercel G-airguns and a Knudsen 320BR ``Chirp''
pulse echosounder operating at 12 kHz. The St. Laurent will also tow a
3 to 5 kHz sub-bottom profiler while in open water
[[Page 39337]]
and when not working with the Healy. The airgun array consists of two
500 in \3\ and one 150 in \3\ airguns for an overall discharge of 1,150
in \3\. Table 2 of the IHA application presents different sound
pressure level (SPL) radii of the airgun array. Acoustic sources that
will be operated on the St. Laurent are described in detail in Section
VII and Appendix B in the IHA application. The seismic array and a
hydrophone streamer towed from the St. Laurent will operate under the
provisions of a Canadian authorization based on Canada's environmental
assessment of the proposed survey while in Canadian or international
waters, and under the provisions of an IHA issued to the USGS by NMFS
in U.S. waters. NMFS cannot issue an IHA directly to a non-U.S.
citizen, however, the Geological Survey of Canada (GSC) has written a
Categorical Declaration stating that ``while in U.S. waters (i.e., the
U.S. 200 mile Exclusive Economic Zone), the GSC will comply with any
and all environmental mitigation measures required by the U.S. NMFS
and/or the U.S. Fish and Wildlife Service.'' The St. Laurent will
follow the lead of the Healy. The Healy will break and clear ice
approximately 1.6 to 3.2 km (1 to 2 miles [mi]) in advance of the St.
Laurent. In situations where the array (and hydrophone streamer) cannot
be towed safely due to ice cover, the St. Laurent may escort the Healy.
The Healy will use a multi-beam echosounder (Kongsberg EM122), a sub-
bottom profiler (Knudsen 3.5 kHz Chirp), and a ``piloting'' echosounder
(ODEC 1500) continuously when underway and during the seismic
profiling. Acoustic Doppler current profilers (75 kHz and 150 kHz) may
also be used on the Healy. The Healy's acoustic systems are described
in further detail in Section VII and Appendix B of the IHA application.
In addition to the hydrophone streamer, marine sonobuoys will be
deployed to acquire wide angle reflection and refraction data for
velocity determination to convert seismic reflection travel time to
depth. Sonobuoys will be deployed off the stern of the St. Laurent
approximately every eight hours during seismic operations with as many
as three deployments per day. The sonobuoy's hydrophone will activate
at a water depth of approximately 60 m (196.9 ft) and seismic signals
will be communicated via radio to the St. Laurent. The sonobuoys are
pre-set to scuttle (i.e., deliberately sink) eight hours after
activation.
The program within U.S. waters will consist of approximately 806 km
(500.8 mi) of survey transect line, not including transits when the
airguns are not operating (see Figure 1 and Table 1 of the IHA
application). U.S. priorities include another 997 km (619.5 mi) of
survey lines north of the U.S. Exclusive Economic Zone (EEZ), for a
total of 1,803 km (1,120.3 mi) of tracklines of interest to the U.S.
Table 1 of the IHA application lists all U.S. priority tracklines;
Figure 1 of the IHA application includes all U.S. priority tracks and
the area of interest to Canada near the proposed U.S. tracklines. Water
depths within the U.S. study area will range from approximately 1,900
to 4,000 m (6,233.5 to 13,123.4 ft) (see Figure 1 of the IHA
application). There may be additional seismic operations associated
with airgun testing, start-up, and repeat coverage of any areas where
initial data quality is sub-standard. The tracklines that will be
surveyed in U.S. waters include the southern 263.8 km (164 mi) of the
line that runs North-South in the western EEZ, the southern 264.5 km
(164.4 mi) of the line that runs North-South in the central EEZ, and
277.7 km (172.6 mi) trackline of the line that connects the two (see
Figure 1 and Table 1 of the IHA application). The IHA application
requests the authorization of incidental takes of marine mammals for
activities within U.S. waters.
Table 1--Proposed U.S. Priority Tracklines for USGS and Geological Survey of Canada (GSC) 2010 Extended
Continental Shelf Survey in the Northern Beaufort Sea and Arctic Ocean
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Time (hour
Location End point 1 End point 2 Kilometer (km) Nautical Mile [hr]) @ 4 nmi/
(nmi) hr
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NS in central EEZ (south).... 71.22[deg] 72.27[deg] 118 64 16
North; North;
145.17[deg] 145.41[deg]
West. West.
NS in central EEZ (north).... 72.27[deg] 73.92[deg] 183 100 25
North; North;
145.41[deg] 145.30[deg]
West. West.
Central-western EEZ connector 73.92[deg] 71.84[deg] 317 171 43
North; North;
145.30[deg] 151.82[deg]
West. West.
NS in western EEZ............ 71.84[deg] 74.32[deg] 281 152 39
North; North;
151.82[deg] 150.30[deg]
West. West.
South Northwind Ridge........ 74.32[deg] 74.96[deg] 239 129 32
North; North;
150.30[deg] 158.01[deg]
West. West.
Northwind Ridge connector.... 74.96[deg] 76.30[deg] 161 87 22
North; North;
158.01[deg] 155.88[deg]
West. West.
Mid-Northwind Ridge.......... 76.30[deg] 75.41[deg] 274 148 37
North; North;
155.88[deg] 146.50[deg]
West. West.
Northwind Ridge connector.... 75.41[deg] 76.57[deg] 129 70 17
North; North;
146.50[deg] 146.82[deg]
West. West.
Mid-Northwind Ridge.......... 76.57[deg] 76.49[deg] 102 55 14
North; North;
146.82[deg] 150.73[deg]
West. West.
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Totals................... ................ ............... 1,804 976 245
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Two vessels will operate cooperatively during the proposed seismic
survey. The St. Laurent will conduct seismic operations using an airgun
array and also operate a 12 kHz Chirp echosounder. The St. Laurent will
also operate a 3 to 5 kHz sub-bottom profiler in open water when not
working with the Healy. The Healy will normally escort the St. Laurent
in ice cover, and will continuously operate a bathymetric multi-beam
echosounder, a 3.5 kHz Chirp sub-bottom profiler, a piloting
echosounder, and two acoustic Doppler current profilers.
The St. Laurent will access the survey area from Canada and
rendezvous with the Healy on approximately August 7, 2010; the Healy
will approach the survey area from the Bering Straits. The St. Laurent
will deploy a relatively small airgun array comprised of three G-
airguns and a single hydrophone streamer approximately 300 m (984 ft)
in length. The airgun array consists of two 500 in\3\ and one 150 in\3\
airguns for an overall discharge of 1,150 in\3\. The St. Laurent will
follow the lead of the Healy which will operate approximately 1.9 to
3.8 km (1 to 2 nmi) ahead of the St. Laurent. In ice conditions where
seismic gear cannot be safely towed, the St. Laurent will escort the
Healy to optimize multi-beam bathymetry data collection. If extended
open-water conditions are encountered, Healy and St. Laurent may
operate independently.
The U.S. priority survey lines will consist of eight transect lines
ranging in
[[Page 39338]]
length from approximately 102 to 317 km (63.4 to 197 mi) of trackline
(see Table 1 and Figure 1 of the IHA application). These tracklines are
planned in water depths of 1,900 to 4,000 m (6,234 to 13,123 ft).
Approximately 806 km (500.8 mi) of trackline will be surveyed within
U.S. waters. The survey line nearest to shore in U.S. waters is
approximately 116 km (63 nmi) offshore at its closest point. After
completion of the survey the St. Laurent will return to port in Canada,
and the Healy will change crew at Barrow via helicopter or surface
conveyance before continuing on another project.
Vessel Specifications
The CCGS St. Laurent was built in 1969 by Canadian Vickers Ltd. in
Montreal, Quebec, and underwent an extensive modernization in Halifax,
Nova Scotia between 1988 to 1993. The St. Laurent is based at CCG Base
Dartmouth in Dartmouth, Nova Scotia. Current vessel activities involve
summer voyages to the Canadian Arctic for sealifts to various coastal
communities and scientific expeditions. A description of the St.
Laurent with vessel specifications is presented in Appendix A of the
IHA application and is available online at: http://www.ccg-gcc.gc.ca/eng/Fleet/Vessels?id=1111&info=5&subinfo.
The Healy is designed to conduct a wide range of research
activities, providing more than 390.2 m\2\ (4,200 ft\2\) of scientific
laboratory space, numerous electronic sensor systems, oceanographic
winches, and accommodations for up to 50 scientists. The Healy is
designed to break 1.4 m (4.5 ft) of ice continuously at 5.6 km/hour
(three knots) and can operate in temperatures as low as -45.6 C (-50
degrees F). The science community provided invaluable input on lab lay-
outs and science capabilities during design and construction of the
ship. The Healy is also a capable platform for supporting other
potential missions in the polar regions, including logistics, search
and rescue, ship escort, environmental protection, and enforcement of
laws and treaties.
The Healy is a USCG icebreaker, capable of traveling at 5.6 km/hour
(three knots) through 1.4 m (4.5 ft) of ice. A ``Central Power Plant,''
four Sultzer 12Z AU40S diesel generators, provides electric power for
propulsion and ship's services through a 60 Hz, three-phase common bus
distribution system. Propulsion power is provided by two electric AC
Synchronous, 11.2 MW drive motors, fed from the common bus through a
Cycloconverter system, that turn two fixed-pitch, four-bladed
propellers. The Healy will also serve as the platform from which
vessel-based Protected Species Observers (PSOs) will watch for marine
mammals before and during airgun operations. Other details of the Healy
can be found in Appendix A of the IHA application.
NMFS believes that the realistic possibility of a ship-strike of a
marine mammal by the vessel during research operations and in-transit
during the proposed survey is discountable. The probability of a ship
strike resulting in an injury or mortality of an animal has been
associated with ship speed; however, it is highly unlikely that the
proposed seismic survey would increase the rate of serious injury or
mortality given the St. Laurent and Healy's slow survey speed.
Acoustic Source Specifications--Seismic Airguns and Radii
The seismic source for the proposed seismic survey will be
comprised of three Sercel G-airguns with a total volume of 1,150 in\3\.
The three-airgun array will be comprised of two 500 in\3\ and one 150
in\3\ G-airguns in a triangular configuration (see Figure B-1 in the
IHA application). The single 150 in\3\ G-airgun will be used if a
power-down is necessary for mitigation. The G-airgun array will be
towed behind the St. Laurent at a depth of approximately 11 m (36.1 ft)
(see Figure B-2 in the IHA application) along predetermined lines in
water depths ranging from 1,900 to 4,000 m (6,233.6 to 13,123.4 ft).
One streamer approximately 232 m (761.2 ft) in length with a single
hydrophone will be towed behind the airgun array at a depth of
approximately 9 to 30 m (29.5 to 98.4 ft).
A square wave trigger signal will be supplied to the firing system
hardware by a FEI-Zyfer GPStarplus Clock model 565, based on GPS time
(typically at approximately 14 to 20 sec intervals). Vessel speed will
be approximately 10.2 km/hour (5.5 knots) resulting in a shot interval
ranging from approximately 39 to 56 m (128 to 183.7 ft). G-airgun
firing and synchronization will be controlled by a RealTime Systems
LongShot fire controller, which will send a voltage to the airgun
solenoid to trigger firing with approximately 54.8 ms delay between
trigger and fire point.
Pressurized air for the pneumatic G-airguns will be supplied by two
Hurricane compressors, model 6T-276-44SB/2500. These are air cooled,
containerized compressor systems. Each compressor will be powered by a
C13 Caterpillar engine which turns a rotary screw first stage
compressor and a three stage piston compressor capable of developing a
total air volume of 600 SCFM @ 2,500 pounds per square inch (PSI). The
seismic system will be operated at 1,950 PSI and one compressor could
easily supply sufficient volume of air under appropriate pressure.
Seismic acquisition will require a watchkeeper in the seismic lab
and another in the compressor container. The seismic lab watchkeeper is
responsible for data acquisition/recording, watching over-the-side
equipment, airgun firing and log keeping. A remote screen will permit
monitoring of compressor pressures and alerts, as well as communication
with the compressor watchkeeper. The compressor watchkeeper will be
required to monitor the compressor for any emergency shut-down and
provide general maintenance that might be required during operations.
Sound level radii for the proposed three airgun array were measured
in 2009 during a seismic calibration (Mosher et al., 2009; Roth and
Schmidt, 2010). A transmission loss model was then constructed assuming
spherical (20LogR) spreading and using the source level estimate 235 dB
re 1 [micro]Pa (rms) 0-peak; 225 dB re 1 [micro]Pa (rms) from the
measurements. The use of 20LogR spreading fit the data well out to
approximately 1 km (0.6 mi) where variability in measured values
increased (see Appendix B in the IHA application for more details and a
figure of the transmission loss model compared to the measurement
data). Additionally, the Gundalf modeling package was used to model the
airgun array and estimated a source level output of 236.7 dB 0-peak
(226.7 dB [rms]). Using this slightly stronger source level estimate
and a 20LogR spreading the 180 and 190 dB (rms) radii are estimated to
be 216 m (708.7 ft) and 68 m (223.1 ft), respectively. As a
conservation measure for the proposed safety radii, the sound level
radii indicated by the empirical data and source models have been
increased to 500 m (1,640.4 ft) for the 180 dB isopleths and to 100 m
(328 ft) of the 190 dB isopleths.
The rms received levels that are used as impact criteria for marine
mammals are not directly comparable to the peak or peak-to-peak values
normally used to characterize source levels of airguns. The measurement
units used above to describe the airgun source, peak or peak-to-peak
dB, are always higher than the rms dB referred to in much of the
biological literature. A measured received level of 160 dB (rms) in the
far field would typically correspond to a peak measurement of about 170
to 172 dB, at the same location (Greene, 1997;
[[Page 39339]]
McCauley et al., 1998, 2000). The precise difference between rms and
peak or peak-to-peak values for a given pulse depends on the frequency
content and duration of the pulse, among other factors. However, the
rms level is always lower than the peak or peak-to-peak level for an
airgun-type source.
Table 2--Distances To Which Sound Levels Greater Than or Equal to 190, 180, and 160 dB re 1 [mu]Pa (rms) Could
Be Received in Deep (Greater Than 1,000 m) Water During the Proposed Survey in the Arctic Ocean, August 7 to
September 3, 2010
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Tow depth Predicted received RMS distances (m)
Source and volume (m) Ice/ Water depth --------------------------------------
open water 190 dB 180 dB 160 dB
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Single Mitigation Airgun (150 in\3\) 11/6-7 Deep (>1,000 m)....... 30 75 750
3 G-airguns (1,190 in\3\)........... 11/6-7 Deep (>1,000 m)....... 100 500 2,500
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Acoustic Source Specifications--Multibeam Echosounders (MBES), Sub-
Bottom Profiler (SBP) and Acoustic Doppler Current Profilers (ADCP)
Along with the airgun operations, additional acoustic systems that
will be operated during the cruise include a 12 kHz Chirp echosounder
and a 3-5 kHz SBP from the St. Laurent. The Healy will operate a 12 kHz
Kongsberg MBES, a Knudsen 320BR profiler, a piloting echosounder, and
two ADCPs. These sources will be operated throughout most of the cruise
to map bathymetry, as necessary, to meet the geophysical science
objectives. During seismic operations, these sources will be deployed
from the St. Laurent and the Healy and will generally operate
simultaneously with the airgun array deployed from the St. Laurent.
The Knudsen 320BR echosounder will provide information on depth and
bottom profile. The Knudsen 320BR is a dual-frequency system with
operating frequencies of 3.5 and 12 kHz, however, the unit will be
functioning at the higher frequency, 12 kHz, because the 3.5 kHz
transducer is not installed.
While the Knudsen 320BR operates at 12 kHz, its calculated maximum
source level (downward) is 215 dB re [micro]Pa at 1 m. The pulse
duration is typically 1.5 to 5 ms with a bandwidth of 3 kHz (FM sweep
from 3 kHz to 6 kHz). The repetition rate is range dependent, but the
maximum is a one percent duty cycle. Typical repetition rate is between
\1/2\ s (in shallow water) to 8 s in deep water. A single 12 kHz
transducer (sub-bottom) array, consisting of 16 elements in a 4x4 array
will be used for the Knudsen 320BR. The 12 kHz transducer (TC-12/34)
emits a conical beam with a width of 30[deg].
The 3-5 kHz chirp SBP will be towed by and operated from the St.
Laurent in open water when the St. Laurent is not working in tandem
with the Healy. The SBP provides information about sedimentary features
and bottom topography. The chirp system has a maximum 7.2 kW transmit
capacity into the towed array. The energy from the towed unit is
directed downward by an array of eight transducers in a conical
beamwidth of 80 degrees. The interval between pulses will be no less
than one pulse per second. SBPs of that frequency can produce sound
levels 200 to 230 dB re 1 [micro]Pa at 1 m (Richardson et al., 1995).
The Kongsberg EM 122 MBES operates at 10.5 to 13 (usually 12) kHz
and is hull-mounted on the Healy. The transmitting beamwidth is 1[deg]
or 2[deg] fore-aft and 150[deg] athwartship. The maximum source level
is 242 dB re 1 [mu]Pam (rms). Each ``ping'' consists of eight (in water
greater than 1,000 m deep) or four (less than 1,000 m) successive fan-
shaped transmissions, each ensonifying a sector that extends 1[deg]
fore-aft. Continuous-wave (CW) pulses increase from two to 15 ms long
in water depths up to 2,600 m (8,530 ft), and FM chirp pulses up to 100
ms long are used in water greater than 2,600 m (8,530 ft). The
successive transmissions span an overall cross-track angular extent of
about 150[deg], with 2 ms gaps between pulses for successive sectors.
The Knudsen 320BR hydrographic SBP will provide information on
sedimentary layering, down to between 20 and 70 m (65.6 to 229.7 ft),
depending on bottom type and slope. The Knudsen 320 BR is a dual-
frequency system with operating frequencies of 3.5 and 12 kHz; only the
low frequency will be used during this survey. At 3.5 kHz, the maximum
output power into the transducer array, as wired on the Healy (where
the array impedance is approximately 125 ohms), is approximately 6,000
watts (electrical), which results in a maximum source level of 221 dB
re 1 [micro]Pa at 1 m downward. Pulse lengths range from 1.5 to 24 ms
with a bandwidth of 3 kHz (FM sweep from 3 kHz to 6 kHz). The
repetition rate is range dependent, but the maximum is a one percent
duty cycle. Typical repetition rate is between \1/2\ s (in shallow
water) to 8 s in deep water. The 3.5 kHz transducer array on the Healy,
consisting of 16 (TR109) elements in a 4x4 array, will be used for the
Knudsen 320BR. At 3.5 kHz the SBP emits a downward conical beam with a
width of approximately 26[deg].
The piloting echosounder on the Healy is an Ocean Data Equipment
Corporation (ODEC) Bathy-1500 that will provide information on water
depth below the vessel. The ODEC system has a maximum 2 kW transmit
capacity into the transducer and has two operating modes, single or
interleaved dual frequency, with available frequencies of 12, 24, 33,
40, 100, and 200 kHz.
The 150 kHz ADCP has a minimum ping rate of 0.65 ms. There are four
beam sectors and each beamwidth is 3[deg]. The pointing angle for each
beam is 30[deg] off from vertical with one each to port, starboard,
forward, and aft. The four beams do not overlap. The 150 kHz ADCP's
maximum depth range is 300 m (984.3 ft).
The Ocean Surveyor 75 is an ADCP operating at a frequency of 75
kHz, producing a ping every 1.4 s. The system is a four-beam phased
array with a beam angle of 30[deg]. Each beam has a width of 4[deg] and
there is no overlap. Maximum output power is 1 kW with a maximum depth
range of 700 m (2,296.6 ft).
Acoustic Source Specifications--Icebreaking
Icebreaking is considered by NMFS to be a continuous sound and NMFS
estimates that harassment occurs when marine mammals are exposed to
continuous sounds at a received sound level of 120 dB SPL or above.
Potential takes of marine mammals may ensue from icebreaking activity
in which the Healy is expected to engage outside of U.S. waters, i.e.,
north of approximately 74.1[deg] North. While breaking ice, the noise
from the ship, including impact with ice, engine noise, and propeller
cavitation, will exceed 120 dB
[[Page 39340]]
continuously. If icebreaking does occur in U.S. waters, USGS expects it
will occur during seismic operations. The exclusion zone (EZ) for the
marine mammal Level B harassment threshold during the proposed seismic
activities is greater than the calculated radius during icebreaking.
Therefore, if the Healy breaks ice during seismic operations within the
U.S. waters, the greater radius, i.e, that for seismic operations,
supersedes that for icebreaking, so no additional takes have been
estimated within U.S. waters.
Proposed Dates, Duration, and Specific Geographic Area
The proposed seismic survey will be conducted for approximately 30
days from approximately August 7 to September 3, 2010. The
approximately 806 km (501 mi) of tracklines within U.S. waters will be
surveyed first. These survey lines are expected to be completed by
approximately August 12, 2010. The seismic vessel St. Laurent will
depart from Kugluktuk, Nunavut, Canada on August 2, 2010 and return to
the same port on approximately September 16, 2010. The Healy will
depart from Dutch Harbor, Alaska on August 3, 2010 to meet the St.
Laurent by August 7, 2010. After completion of this survey, the Healy
will change crew through Barrow via helicopter or surface vessel on
September 4, 2010 (see Table 3 of the IHA application). The entire
survey area will be bounded approximately by 145[deg] to 158[deg] West
longitude and 71[deg] to 84[deg] North latitude in water depths ranging
from approximately 1,900 to 4,000 m (6,234 to 13,123 ft) (see Figure 1
and Table 1 of the IHA application). Ice conditions are expected to
range from open water to 10/10 ice cover. See Table 3 of the IHA
application for a synopsis of the 2010 St. Laurent and Healy Extended
Continental Shelf expeditions in the Arctic Ocean, August 3 to
September 16, 2010.
Icebreaking outside U.S. waters will occur between the latitudes of
approximately 74[deg] to 84[deg] North. Vessel operations and ice
conditions from similar survey activities and timing in 2008 and 2009
were used to estimate the amount of icebreaking (in trackline km) that
is likely to occur in 2010. USGS expects that the St. Laurent and the
Healy will be working in tandem through the ice for a maximum of 23 to
25 days while outside of U.S. waters. The average distance travelled in
2008 and 2009 when the Healy broke ice for the St. Laurent was 135 km/
day (83.9 mi/day). Based on the 23 to 25 day period of icebreaking,
USGS calculated that, at most approximately 3,102 to 3,372 km (1,927.5
to 2,095.3 mi) of vessel trackline may involve icebreaking. This
calculation is likely an overestimation because icebreakers often
follow leads when they are available and thus do not break ice at all
times.
Table 3--Projected 2010 Icebreaking Effort for USGS/GSC 2010 Extended Continental Shelf Survey in the Northern
Beaufort Sea and Arctic Ocean
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
2008.................................... 19........................ 2,469..................... 130
2009.................................... 27........................ 37,744.................... 140
Average 2008 to 2009.................... 23........................ 3,122..................... 135
Projected 2010.......................... 23 to 25.................. 3,102 to 3,372............ --
----------------------------------------------------------------------------------------------------------------
Description of Marine Mammals in the Proposed Activity Area
Regarding marine mammals, a total of nine cetacean species,
including four odontocete (dolphins, porpoises, and small- and large-
toothed whales) species, five mysticete species (baleen whales), and
five pinniped species (seals, sea lions, and walrus) and the polar bear
are known to occur in the area affected by the specified activities
associated with the proposed Arctic Ocean marine seismic survey (see
Table 3 of USGS's application). Cetaceans and pinnipeds, which are the
subject of this IHA application, are protected by the MMPA and managed
by NMFS in accordance with its requirements. In the U.S., the walrus
and polar bear are managed under the jurisdiction of the U.S. Fish and
Wildlife Service (USFWS) and are not considered further in this
analysis. Information on the occurrence, distribution, population size,
and conservation status for each of the 14 marine mammal species that
may occur in the proposed project area is presented in Table 4 of
USGS's application as well as here in the table below (Table 4).
Several marine mammal species that may be affected by the proposed IHA
are listed as Endangered or Threatened under Section 4 of the ESA,
including the bowhead, fin and humpback whale, and polar bear. The
bowhead whale is common in the Arctic, but unlikely in the survey area.
Based on a small number of sightings in the Chukchi Sea, the fin whale
is unlikely to be encountered along the planned trackline in the Arctic
Ocean. Humpback whales are uncommon in the Chukchi Sea and normally do
not occur in the Beaufort Sea. Several humpback sightings were recorded
during vessel-based surveys in the Chukchi Sea in 2007 (three
sightings) and 2008 (one sighting; Haley et al., 2009). The only known
occurrence of humpback whale in the Beaufort Sea was a single sighting
of a cow and calf reported and photographed in 2007 (Green et al.,
2007). Based on the low number of sightings in the Chukchi and Beaufort
seas, humpback whales would be unlikely to occur in the vicinity of the
proposed geophysical activities.
The marine mammal species under NMFS jurisdiction most likely to
occur in the seismic survey area include two cetacean species (beluga
and bowhead whales), and two pinniped species (ringed and bearded
seals). These species however, will likely occur in low numbers and
most sightings will likely occur in locations within 100 km (62 mi) of
shore where no seismic work is planned. The marine mammal most likely
to be encountered throughout the cruise is the ringed seal.
Seven additional cetacean species--narwhal, killer whale, harbor
porpoise, gray whale, minke whale, fin whale, and humpback whale--could
occur in the project area. Gray whales occur regularly in continental
shelf waters along the Chukchi Sea coast in summer and to a lesser
extent along the Beaufort Sea coast. Recent evidence from monitoring
activities in the Chukchi and Beaufort seas during industry seismic
surveys suggests that harbor porpoise and minke whales, which have been
considered uncommon or rare in the Chukchi and Beaufort seas, may be
increasing in numbers in these areas (Funk et al., 2009). Small numbers
of killer whales have also been recorded during these industry surveys,
along with a few sightings of fin and humpback whales. The narwhal
occurs in Canadian waters and occasionally in the Beaufort Sea, but is
rare there and not expected to be encountered. Each of these species is
uncommon or rare in the Chukchi and Beaufort seas, and relatively few
if any encounters with
[[Page 39341]]
these species are expected during the seismic program.
Additional pinniped species that could be encountered during the
proposed seismic survey include spotted and ribbon seals, and Pacific
walrus. Spotted seals are more abundant in the Chukchi Sea and occur in
small numbers in the Beaufort Sea. The ribbon seal is uncommon in the
Chukchi Sea and there are few sightings in the Beaufort Sea. The
Pacific walrus is common in the Chukchi Sea, but uncommon in the
Beaufort Sea and not likely to occur in the deep waters of the proposed
survey area. None of these species would likely be encountered during
the proposed cruise other than perhaps transit periods to and from the
survey area.
Table 4 below outlines the marine mammal species, their habitat and
abundance in the proposed project area, their conservation status, and
density. Additional information regarding the distribution of these
species expected to be found in the proposed project area and how the
estimated densities were calculated may be found in USGS's application.
Table 4--The Habitat, Regional Abundance, Conservation Status, and Best and Maximum Density Estimates of Marine
Mammals That Could Occur in or Near the Proposed Seismic Survey Area in the Arctic Ocean. See Table 4 in USGS's
Application for Further Detail
----------------------------------------------------------------------------------------------------------------
Best \b\ Max \c\
Density Density
Abundance/ (/ (/
Species Habitat regional ESA\a\ km\2\) open km\2\) open
population water, ice water, ice
size\a\ margin, polar margin, polar
pack pack
----------------------------------------------------------------------------------------------------------------
Odontocetes:
Beluga whale Offshore, 3,710\d\, NL 0.0354 0.0709
(Delphinapterus leucas). coastal, ice 39,257\e\. 0.0354 0.0709
edges. 0.0035 0.0071
Narwhal (Monodon Offshore, ice Rare\f\......... NL 0.0000 0.0001
monocerus). edge. 0.0000 0.0002
0.0000 0.0001
Killer whale (Orcinus orca).. Widely Rare............ NL 0.0000 0.0001
distributed. 0.0000 0.0001
0.0000 0.0001
Harbor porpoise (Phocoena Coastal, inland Common NL 0.0000 0.0001
phocoena). waters, shallow (Chukchi), 0.0000 0.0001
offshore waters. Uncommon 0.0001 0.0001
(Beaufort).
Mysticetes:
Bowhead whale (Balaena Pack ice and 10,545\g\....... EN 0.0061 0.0122
mysticetus). coastal. 0.0061 0.0122
0.0006 0.0012
Eastern Pacific gray Coastal, lagoons 488\h\, NL 0.0000 0.0001
whale (Eschrichtius 17,500\i\. 0.0000 0.0001
robustus). 0.0000 0.0001
Minke whale (Balaenoptera Shelf, coastal.. Small numbers... NL 0.0000 0.0001
acutorostrata). 0.0000 0.0001
0.0000 0.0001
Fin whale (Balaenoptera Slope, mostly Rare (Chukchi).. E 0.0000 0.0001
physalus). pelagic. 0.0000 0.0001
0.0000 0.0001
Humpback whale (Megaptera Shelf, coastal.. Rare............ EN 0.0000 0.0001
novaeangliae). 0.0000 0.0001
0.0000 0.0001
Pinnipeds:
Bearded seal (Erignathus Pack ice, open 300,000-450,000\ C 0.0096 0.0384
barbatus). water. j\. 0.0128 0.0512
0.0013 0.0051
Spotted seal (Phoca Pack ice, open 59,214\k\....... P-T 0.0001 0.0004
largha). water, coastal 0.0001 0.0004
haul-outs. 0.0000 0.0000
Ringed seal (Pusa Landfast and 18,000\l\, C 0.1883 0.7530
hispida). pack ice, open 208,000-252,000 0.2510 1.0040
water. \m\. 0.0251 0.1004
Ribbon seal (Histriophoca Pack ice, open 90,000-100,000\n NL N.A. N.A.
fasciata). water. \.
Pacific walrus (Odobenus Ice, coastal.... N.A............. NL N.A. N.A.
rosmarus divergens).
Carnivores:
Polar bear (Ursus Ice, coastal.... N.A............. T N.A. N.A.
maritimus marinus).
----------------------------------------------------------------------------------------------------------------
N.A.--Data not available or species status was not assessed,
\a\ U.S. Endangered Species Act: EN = Endangered, T = Threatened, C = Candidate, P = Proposed, NL = Not listed.
\b\ Best estimate as listed in Table 5 and Add-3 of the application.
\c\ Maximum estimate as listed in Table 5 and Add-3 of the application.
\d\ Eastern Chukchi Sea stock based on 1989 to 1991 surveys with a correction factor (Angliss and Allen, 2009).
\e\ Beaufort Sea stock based on surveys in 1992 (Angliss and Allen, 2009).
\f\ DFO (2004) states the population in Baffin Bay and the Canadian Arctic archipelago is approximately 60,000;
very few of these enter the Beaufort Sea.
[[Page 39342]]
\g\ Abundance of bowhead whales surveyed near Barrow, as of 2001 (George et al., 2004). Revised to 10,545 by Zeh
and Punt (2005).
\h\ Southern Chukchi Sea and northern Bering Sea (Clarks and Moore, 2002).
\i\ Eastern North Pacific gray whale population (Rugh et al., 2008).
\j\ Based on earlier estimates, no current population estimate available (Angliss and Allen, 2009).
\k\ Alaska stock based on aerial surveys in 1992 (Angliss and Allen, 2009).
\l\ Beaufort Sea minimum estimate with no correction factor based on aerial surveys in 1996 to 1999 (Frost et
al., 2002 in Angliss and Allen, 2009).
\m\ Eastern Chukchi Sea population (Bengston et al., 2005).
\n\ Bering Sea population (Burns, 1981a in Angliss and Allen, 2009).
Within the latitudes of the proposed survey when the Healy will be
breaking ice outside of U.S. waters, no cetaceans were observed by PSOs
along approximately 21,322 km (13,248.9 mi) of effort during projects
in 2005, 2006, 2008, and 2009 (Haley and Ireland, 2006; Haley, 2006;
Jackson and DesRoches, 2008; Mosher et al., 2009). The estimated
maximum amount of icebreaking outside of U.S. waters for this project,
i.e., 3,372 line km (2,095.3 mi), is considerably less than the
combined trackline for the aforementioned projects. At least one PSO
will stand watch at all times while the Healy is breaking ice for the
St. Laurent. USGS does not expect that PSOs will observe any cetaceans
during the proposed survey. Seals were reported by PSOs during the
2005, 2006, 2008, and 2009 effort within the latitudes of the proposed
survey.
Table 5--Number of Pinnipeds Reported During 2005, 2006, 2008, and 2009
Projects Within the Latitudes Where the Healy Will Be Breaking Ice
Outside of U.S. Waters for the Proposed Arctic Ocean Survey (Haley and
Ireland, 2006; Haley, 2006, GSC Unpublished Data, 2008; Mosher et al.,
2009)
------------------------------------------------------------------------
Number of Number of
Pinniped species sightings individuals
------------------------------------------------------------------------
Ringed seal............................. 116 125
Bearded seal............................ 24 26
Unidentified seal....................... 128 140
-------------------------------
Totals.............................. 268 291
------------------------------------------------------------------------
Potential Effects on Marine Mammals
Potential Effects of Airgun Sounds
The effects of sounds from airguns might result in one or more of
the following: Tolerance, masking of natural sounds, behavioral
disturbances, temporary or permanent hearing impairment, or non-
auditory physical or physiological effects (Richardson et al., 1995;
Gordon et al., 2004; Nowacek et al., 2007; Southall et al., 2007).
Permanent hearing impairment, in the unlikely event that it occurred,
would constitute injury, but temporary threshold shift (TTS) is not an
injury (Southall et al., 2007). Although the possibility cannot be
entirely excluded, it is unlikely that the project would result in any
cases of temporary or especially permanent hearing impairment, or any
significant non-auditory physical or physiological effects. Some
behavioral disturbance is expected, but this would be localized and
short-term. NMFS concurs with this determination.
The root mean square (rms) received levels that are used as impact
criteria for marine mammals are not directly comparable to the peak or
peak-to-peak values normally used to characterize source levels of
airgun arrays. The measurement units used to describe airgun sources,
peak or peak-to-peak decibels, are always higher than the rms decibels
referred to in biological literature. A measured received level of 160
dB (rms) in the far field would typically correspond to a peak
measurement of approximately 170 to 172 dB, and to a peak-to-peak
measurement of approximately 176 to 178 dB, as measured for the same
pulse received at the same location (Greene, 1997; McCauley et al.,
1998, 2000a). The precise difference between rms and peak or peak-to-
peak values depends on the frequency content and duration of the pulse,
among other factors. However, the rms level is always lower than the
peak or peak-to-peak level for an airgun-type source.
Tolerance
Numerous studies have shown that pulsed sounds from airguns are
often readily detectable in the water at distances of many kilometers.
For a summary of the characteristics of airgun pulses, see Appendix D
(3) of the IHA application. Numerous studies have shown that marine
mammals at distances more than a few kilometers from operating seismic
vessels often show no apparent response--see Appendix D (5) of the IHA
application. 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 the 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 usually seem to be more tolerant
of exposure to airgun pulses than are cetaceans, with relative
responsiveness of baleen and toothed whales being variable.
Masking
Obscuring of sounds of interest by interfering sounds, generally at
similar frequencies, is known as masking. Masking effects of pulsed
sounds (even from large arrays of airguns) on marine mammal calls and
other natural sounds are expected to be limited, although there are few
specific data of relevance. Because of the intermittent nature and low
duty cycle of seismic pulses, animals can emit and receive sounds in
the relatively quiet intervals between pulses. However in exceptional
situations, reverberation occurs for much or all of the interval
between pulses (Simard et al., 2005; Clark and Gagnon, 2006) which
could mask calls. Some baleen and toothed whales are known to continue
calling in the presence of seismic pulses. The airgun sounds are
pulsed, with quiet periods between the pulses, and whale calls often
can be heard between the seismic pulses (Richardson et al., 1986;
McDonald et al., 1995; Greene et al., 1999; Nieukirk et al., 2004;
Smultea et al., 2004; Holst et al., 2005a,b, 2006; Dunn et al., 2009).
In the northeast Pacific Ocean, blue whale calls have been recorded
during a seismic survey off Oregon (McDonald et al., 1995). Clark and
Gagnon (2006) reported that fin whales in the northeast Pacific Ocean
went silent for an extended period starting soon after the onset of a
seismic survey in the area. Similarly, there has been one report that
sperm whales ceased calling when exposed to pulses from a very distant
seismic ship (Bowles et al., 1994). However, more recent studies found
that they continued calling the presence of seismic pulses (Madsen et
al., 2002; Tyack et al., 2003; Smultea et al., 2004; Holst et al.,
2006; Jochens et al., 2008). Bowhead whale calls are frequently
detected in the presence of seismic pulses, although the
[[Page 39343]]
number of calls detected may sometimes be reduced in the presence of
airgun pulses (Richardson et al., 1986; Greene et al., 1999; Blackwell
et al., 2008). Dolphins and porpoises commonly are heard calling while
airguns are operating (Gordon et al., 2004; Smultea et al., 2004; Holst
et al., 2005a,b; Potter et al., 2007). The sounds important to small
odontocetes are predominantly at much higher frequencies than the
dominant components of airgun sounds, thus limiting the potential for
masking. In general, masking effects of seismic pulses are expected to
be minor (in the case of smaller odontocetes), given the normally
intermittent nature of seismic pulses. Masking effects on marine
mammals are discussed further in Appendix D (4) of the IHA application.
Disturbance Reactions
Disturbance includes a variety of effects, including subtle changes
in behavior, more conspicuous changes in activities, and displacement.
Reactions to sound, if any, depend on species, state of maturity,
experience, current activity, reproductive state, time of day, and many
other factors (Richardson et al., 1995; Wartzok et al., 2004; Southall
et al., 2007; Weilgart, 2007). If a marine mammal does react to an
underwater sound by changing its behavior or moving a small distance,
the response may or may not rise to the level of ``harassment'' to the
individual, or affect the stock or the species population as a whole.
However, if a sound source displaces marine mammals from an important
feeding or breeding area for a prolonged period, impacts on individuals
and populations could be significant (e.g., Lusseau and Bejder, 2007;
Weilgart, 2007). Given the many uncertainties in predicting the
quantity and types of impacts of noise on marine mammals, it is common
practice to estimate how many mammals are likely to be present within a
particular distance of industrial activities, and/or exposed to a
particular level of industrial sound. In most cases, this practice
potentially overestimates the numbers of marine mammals that would be
affected in some biologically-important manner.
The sound exposure criteria used to estimate how many marine
mammals might be disturbed to some biologically-important degree by a
seismic program are based primarily on behavioral observations during
studies of several species. However, information is lacking for many
species. Detailed studies have been done on humpback, gray, bowhead,
and on ringed seals. Less detailed data are available for some other
species of baleen whales, sperm whales, small toothed whales, and sea
otters, but for many species there are no data on responses to marine
seismic surveys.
Baleen Whales--Baleen whales generally tend to avoid operating
airguns, but avoidance radii are quite variable. Whales are often
reported to show no overt reactions to pulses from large arrays of
airguns at distances beyond a few kilometers, even though the airgun
pulses remain well above ambient noise levels out to much longer
distances. However, as reviewed in Appendix D (5) of the USGS IHA
application, baleen whales exposed to strong noise pulses from airguns
often react by deviating from their normal migration route and/or
interrupting their feeding activities and moving away from the sound
source. In the case of the migrating gray and bowhead whales, the
observed changes in behavior appeared to be of little or no biological
consequence to the animals. They simply avoided the sound source by
displacing their migration route to varying degrees, but within the
natural boundaries of the migration corridors.
Studies of gray, bowhead, and humpback whales have demonstrated
that seismic pulses with received levels of 160 to 170 dB re 1 [mu]Pa
(rms) seem to cause obvious avoidance behavior in a substantial
fraction of the animals exposed (Richardson et al., 1995). In many
areas, seismic pulses from large arrays of airguns diminish to those
levels at distances ranging from 4 to 15 km (2.8 to 9 mi) from the
source. A substantial proportion of the baleen whales within those
distances may show avoidance or other strong behavioral reactions to
the airgun array. Subtle behavioral changes sometimes become evident at
somewhat lower received levels, and studies summarized in Appendix D
(5) of the USGS IHA application have shown that some species of baleen
whales, notably bowhead and humpback whales, at times show strong
avoidance at received levels lower than 160 to 170 dB re 1 [mu]Pa
(rms).
Bowhead whales migrating west across the Alaskan Beaufort Sea in
autumn, in particular, are unusually responsive, with substantial
avoidance occurring out to distances of 20 to 30 km (12.4 to 18.6 mi)
from a medium-sized airgun source at received sound levels of around
120 to 130 dB re 1 [mu]Pa (rms) (Miller et al., 1999; Richardson et
al., 1999; see Appendix D (5) of the IHA application). However, more
recent research on bowhead whales (Miller et al., 2005a; Harris et al.,
2007; Lyons et al., 2009; Christi et al., 2009) corroborates earlier
evidence that, during the summer feeding season, bowheads are not as
sensitive to seismic sources. Nonetheless, subtle but statistically
significant changes in surfacing-respiration-dive cycles were evident
upon statistical analysis (Richardson et al., 1986). In summer,
bowheads typically begin to show avoidance reactions at a received
level of about 152 to 178 dB re 1 [mu]Pa (rms) (Richardson et al.,
1986, 1995; Ljungblad et al., 1988; Miller et al., 2005a). The USGS
project will be conducted during fall migration at locations greater
than 200 nmi offshore, well north of the known bowhead migration
corridor. Recent evidence suggests that some bowheads feed during
migration and feeding bowheads might be encountered in the central
Alaska Beaufort Sea during transit periods to and from Barrow (Lyons et
al., 2009; Christi et al., 2009). The primary bowhead summer feeding
grounds however, are far to the east in the Canadian Beaufort Sea.
Reactions of migrating and feeding (but not wintering) gray whales
to seismic surveys have been studied. Malme et al. (1986, 1988) studied
the responses of feeding Eastern Pacific gray whales to pulses from a
single 100 in\3\ airgun off St. Lawrence Island in the northern Bering
Sea. Malme et al. (1986, 1988) estimated, based on small sample sizes,
that 50 percent of feeding gray whales ceased feeding at an average
received pressure level of 173 dB re 1 [mu]Pa on an (approximate) rms
basis, and that 10 percent of feeding whales interrupted feeding at
received levels of 163 dB re 1 [mu]Pa (rms). Those findings were
generally consistent with the results of experiments conducted on
larger numbers of gray whales that were migrating along the California
coast (Malme et al., 1984; Malme and Miles, 1985), and with
observations of Western Pacific gray whales feeding off Sakhalin
Island, Russia, when a seismic survey was underway just offshore of
their feeding area (Wursig et al., 1999; Gailey et al., 2007; Johnson
et al., 2007; Yazvenko et al. 2007a,b), along with data on gray whales
off British Columbia (Bain and Williams, 2006).
Various species of Balaenoptera (blue, sei, fin, Bryde's, and minke
whales) have occasionally been reported in areas ensonified by airgun
pulses (Stone, 2003; MacLean and Haley, 2004; Stone and Tasker, 2006),
and calls from blue and fin whales have been localized in areas with
airgun operations (e.g. McDonald et al., 1995; Dunn et al., 2009).
Sightings by observers on seismic vessels off the United Kingdom from
1997 to 2000 suggest that, during times of good sightability, sighting
rates for
[[Page 39344]]
mysticetes (mainly fin and sei whales) were similar when large arrays
of airguns were shooting and not shooting (silent) (Stone, 2003; Stone
and Tasker, 2006). However, these whales tended to exhibit localized
avoidance, remaining significantly further (on average) from the airgun
array during seismic operations compared with non-seismic periods
(Stone and Tasker, 2006). In a study off of Nova Scotia, Moulton and
Miller (2005) found little difference in sighting rates (after
accounting for water depth) and initial sighting distances of
balaenopterid whales when airguns were operating vs. silent. However,
there were indications that these whales were more likely to be moving
away when seen during airgun operations. Similarly, ship-based
monitoring studies of blue, fin, sei, and minke whales offshore of
Newfoundland (Orphan Basin and Laurentian Sub-basin) found no more than
small differences in sighting rates and swim direction during seismic
vs. non-seismic periods (Moulton et al., 2005, 2006a,b).
Data on short-term reactions (or lack of reactions) of cetaceans to
impulsive noises are not necessarily indicative of long-term or
biologically significant effects. It is not known whether impulsive
sounds affect reproductive rate or distribution and habitat use in
subsequent days or years. However, gray whales continued to migrate
annually along the west coast of North America with substantial
increases in the population over recent years, despite intermittent
seismic exploration (and much ship traffic) in that area for decades
(see Appendix A in Malme et al., 1984; Richardson et al., 1995; Angliss
and Outlaw, 2008). The Western Pacific gray whale population did not
seem affected by a seismic survey in its feeding ground during a prior
year (Johnson et al., 2007). Similarly, bowhead whales have continued
to travel to the eastern Beaufort Sea each summer, and their numbers
have increased notably, despite seismic exploration in their summer and
autumn range for many years (Richardson et al., 1987; Angliss and
Outlaw, 2008). Populations of both gray whales and bowhead whales grew
substantially during this time. In any event, the brief exposures to
sound pulses from the proposed airgun source are highly unlikely to
result in prolonged effects.
Toothed Whales--Little systematic information is available about
reactions of toothed whales to noise pulses. Few studies similar to the
more extensive baleen whale/seismic pulse work summarized above and (in
more detail) in Appendix D of the IHA application have been reported
for toothed whales. However, recent systematic studies on sperm whales
have been done (Gordon et al., 2006; Madsen et al., 2006; Winsor and
Mate, 2006; Jochens et al., 2008; Miller et al., 2009). There is an
increasing amount of information about responses of various odontocetes
to seismic surveys based on monitoring studies (e.g., Stone, 2003;
Smultea et al., 2004; Moulton and Miller, 2005; Bain and Williams,
2006; Holst et al., 2006; Stone and Tasker, 2006; Potter et al., 2007;
Hauser et al., 2008; Holst and Smultea, 2008; Weir, 2008; Barkaszi et
al., 2009; Richardson et al., 2009).
Seismic operators and observers on seismic vessels regularly see
dolphins and other small toothed whales near operating airgun arrays,
but in general there seems to be a tendency for most delphinids to show
some limited avoidance of operating seismic vessels with large airgun
arrays (Goold, 1996a,b,c; Calambokidis and Osmek, 1998; Stone, 2003;
Moulton and Miller, 2005; Holst et al., 2006; Stone and Tasker, 2006;
Weir, 2008; Richardson et al., 2009; Barkaszi et al., 2009). However,
some dolphins seem to be attracted to the seismic vessel and floats,
and some ride the bow wave of the seismic vessel even when large airgun
arrays are firing (Moulton and Miller, 2005). Nonetheless, there have
been indications that small toothed whales more often tend to head
away, or to maintain a somewhat greater distance from the vessel, when
a large array of airguns is operating than when it is silent (Goold,
1996a,b,c; Calambokidis and Osmek, 1998; Stone, 2003; Stone and Tasker,
2006; Weir, 2008). In most cases, the avoidance radii for delphinids
appear to be small, on the order of 1 km (0.62 mi) or less, and some
individuals show no apparent avoidance. The beluga is a species that
(at least at times) shows long-distance avoidance of seismic vessels.
Aerial surveys during seismic operations in the southeastern Beaufort
Sea during summer found that sighting rates of beluga whales were
significantly lower at distances 10 to 20 km (6.2 to 12.4 mi) compared
with 20 to 30 km (12.4 to 18.6 mi) from an operating airgun array, and
observers on seismic boats in that area rarely see belugas (Miller et
al., 2005; Harris et al., 2007).
Captive bottlenose dolphins and beluga whales exhibited changes in
behavior when exposed to strong pulsed sounds similar in duration to
those typically used in seismic surveys (Finneran et al., 2000, 2002,
2005; Finneran and Schlundt, 2004). However, the animals tolerated high
received levels of sound (pk-pk level greater than 200 dB re 1
[micro]Pa) before exhibiting aversive behaviors. With the presently-
planned source, such levels would be limited to distances less than 200
m (656.2 ft) of the three airgun array. The reactions of belugas to the
USGS survey are likely to be more similar to those of free-ranging
belugas exposed to airgun sound (Miller et al., 2005) than to those of
captive belugas exposed to a different type of strong transient sound
(Finneran et al., 2000, 2002).
Results for porpoises depend on species. The limited available data
suggest that harbor porpoises show stronger avoidance of seismic
operations than do Dall's porpoises (Stone, 2003; Bain and Williams,
2006; Stone and Tasker, 2006). Dall's porpoises seem relatively
tolerant of airgun operations (MacLean and Koski, 2005; Bain and
Williams, 2006), although they too have been observed to avoid large
arrays of operations airguns (Calambokidis and Osmek, 1998; Bain and
Williams, 2006). This apparent difference in responsiveness of these
two porpoise species is consistent with their relative responsiveness
to boat traffic and some other acoustic sources in general (Richardson
et al., 1995; Southall et al., 2007).
Odontocete reactions to large arrays of airguns are variable and,
at least for delphinids and Dall's porpoises, seem to be confined to a
smaller radius than has been observed for the more responsive of the
mysticetes, belugas, and harbor porpoises (Appendix C of the IHA
application).
Pinnipeds--Pinnipeds are not likely to show a strong avoidance
reaction to the airgun sources that will be used. Visual monitoring
from seismic vessels has shown only slight (if any) avoidance of
airguns by pinnipeds, and only slight (if any) changes in behavior--see
Appendix D (5) of the IHA application. Ringed seals frequently do not
avoid the area within a few hundred meters of operating airgun arrays
(Harris et al., 2001; Moulton and Lawson, 2002; Miller et al., 2005).
However, initial telemetry work suggests that avoidance and other
behavioral reactions by two other species of seals to small airgun
sources may at times be stronger than evident to date from visual
studies of pinnipeds reactions to airguns (Thompson et al., 1998). Even
if reactions of the species occurring in the present study area are as
strong as those evident in the telemetry study, reactions are expected
to be confined to relatively small distances and durations, with no
long-term effects on pinniped individuals or populations.
[[Page 39345]]
Hearing Impairment and Other Physical Effects
Temporary or permanent hearing impairment is a possibility when
marine mammals are exposed to very strong sounds, but there has been no
specific documentation of this for marine mammals exposed to sequences
of airgun pulses.
NMFS is presently developing new noise exposure criteria for marine
mammals that take account of the now-available scientific data on
temporary threshold shift (TTS), the expected offset between the TTS
and permanent threshold shift (PTS) thresholds, differences in the
acoustic frequencies to which different marine mammal groups are
sensitive, and other relevant factors. Detailed recommendations for new
science-based noise exposure criteria were published in late 2007
(Southall et al., 2007).
Several aspects of the planned monitoring and mitigation measures
for this project (see below) are designed to detect marine mammals
occurring near the airguns to avoid exposing them to sound pulses that
might, at least in theory, cause hearing impairment. In addition, many
cetaceans are likely to show some avoidance of the area where received
levels of airgun sound are high enough such that hearing impairment
could potentially occur. In those cases, the avoidance responses of the
animals themselves will reduce or (most likely) avoid any possibility
of hearing impairment.
Non-auditory physical effects may also occur in marine mammals
exposed to strong underwater pulsed sound. Possible types of non-
auditory physiological effects or injuries that might (in theory) occur
in mammals close to a strong sound source include stress, neurological
effects, bubble formation, and other types of organ or tissue damage.
It is possible that some marine mammal species (i.e., beaked whales)
may be especially susceptible to injury and/or stranding when exposed
to strong pulsed sounds. However, as discussed below, 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 study area. It is especially unlikely that
any effects of these types would occur during the present project given
the brief duration of exposure of any given mammal, the deep water in
the study area, and the proposed monitoring and mitigation measures
(see below). The following subsections discuss in somewhat more detail
the possibilities of TTS, PTS, and non-auditory physical effects.
Temporary Threshold Shift--TTS is the mildest form of hearing
impairment that can occur during exposure to a strong sound (Kryter,
1985). While experiencing TTS, the hearing threshold rises and a sound
must be stronger in order to be heard. At least in terrestrial mammals,
TTS can last from minutes or hours to (in cases of strong TTS) days.
For sound exposures at or somewhat above the TTS threshold, hearing
sensitivity in both terrestrial and marine mammals recovers rapidly
after exposure to the noise ends. Few data on sound levels and
durations necessary to elicit mild TTS have been obtained for marine
mammals, and none of the published data concern TTS elicited by
exposure to multiple pulses of sound. Available data on TTS in marine
mammals are summarized in Southall et al. (2007).
For toothed whales exposed to single short pulses, the TTS
threshold appears to be, to a first approximation, a function of the
energy content of the pulse (Finneran et al., 2002, 2005). Given the
available data, the received level of a single seismic pulse might need
to be approximately 210 dB re 1 [mu]Pa (rms) (approximately 221 to 226
dB pk-pk) in order to produce brief, mild TTS. Exposure to several
seismic pulses at received levels near 200 to 205 dB (rms) might result
in slight TTS in a small odontocete, assuming the TTS threshold is (to
a first approximation) a function of the total received pulse energy.
Seismic pulses with received levels of 200 to 205 dB or more are
usually restricted to a radius of no more than 200 m (656.2 ft) around
a seismic vessel operating a large array of airguns.
For baleen whales, there are no data, direct or indirect, on levels
or properties of sound required to induce TTS. The frequencies to which
baleen whales are most sensitive are lower than those to which
odontocetes are more sensitive, and natural background noise levels at
those low frequencies tend to be higher. As a result, auditory
thresholds of baleen whales within their frequency band of best hearing
are believed to be higher (less sensitive) than are those of
odontocetes at their best frequencies (Clark and Ellison, 2004). From
this, it is suspected that received levels causing TTS onset may also
be higher in baleen whales (Southall et al., 2007). However, no cases
of TTS are expected given the moderate size of the source 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; Au et al., 2000). For harbor seal, which is
closely related to the ringed seal, TTS onset apparently occurs at
somewhat lower received energy levels than for odontocetes (see
Appendix D of the IHA application).
A marine mammal within a radius of less than or equal to 100 m (328
ft) around a typical large array of operating airguns might be exposed
to a few seismic pulses with levels of greater than 205 dB (rms), and
possibly more pulses if the mammal moved with the seismic vessel. The
received sound levels will be reduced for the proposed three airgun
array to be used during the current survey compared to the larger
arrays thus reducing the potential for TTS for the proposed survey. (As
noted above, most cetacean species trend to avoid operating airguns,
although not all individuals do so.) However, several of the
considerations that are relevant in assessing the impact of typical
seismic surveys with arrays of airguns are not directly applicable
here:
``Ramping-up'' (soft-start) is standard operational
protocol during start-up of large airgun arrays. Ramping-up involves
starting the airguns in sequence, usually commencing with a single
airgun and gradually adding additional airguns.
It is unlikely that cetaceans would be exposed to airgun
pulses at a sufficiently high level for a sufficiently long period to
cause more than mild TTS, given the relative movement of the vessel and
the marine mammal. For the proposed project, the seismic survey will be
in deep water where the radius of influence and duration of exposure to
strong pulses is smaller compared to shallow locations.
With a large array of airguns, TTS would be most likely in
any odontocetes that bow-ride or in any odontocetes or pinnipeds that
linger near the airguns. For the proposed survey, the anticipated 180
dB and 190 dB (re 1 [mu]Pa 1m rms) exclusion zone in deep water are
expected to extend 483 m (1,584.7 ft) and 153m (502 ft), respectively,
from the airgun array which could result in effects to bow-riding
species. However, no species that occur within the project area are
expected to bow-ride.
[[Page 39346]]
There is a possibility that a small number of seals (which
often show little or no avoidance of approaching seismic vessels) could
occur close to the airguns and that they might incur slight TTS if no
mitigation action (shut-down) were taken.
To avoid the potential for injury, NMFS (1995, 2000) concluded that
cetaceans and pinnipeds should not be exposed to pulsed underwater
noise at received levels exceeding 180 and 190 dB re 1 [mu]Pa (rms),
respectively. All airgun activity will occur in water depths ranging
from approximately 2,000 to 4,000 m (6,561.7 to 13,123.4 ft). Sound
level radii of the proposed three airgun array were measured in 2009
during a seismic calibration experiment (Mosher et al., 2009; Roth and
Schmidt, 2010). A transmission loss model was then constructed assuming
spherical (20LogR) spreading and using the source level estimate (235
dB re 1 [mu]Pa 0-peak; 225 dB re 1 [mu]Pa rms) from the measurements.
The use of 20LogR spreading fit the data well out to approximately one
km (0.6 mi) where variability in measures values increased (see
Appendix B of the IHA application for more details and a figure of the
transmission loss model compared to the measurement data).
Additionally, the Gundalf modeling package was used to model the airgun
array and estimated a source level output of 236.7 dB 0-peak (226.7 dB
rms). Using this slightly stronger source level estimate and 20LogR
spreading the 180 and 190 dB rms radii are estimated to be 216 m (708.7
ft) and 68 m (223.1 ft), respectively. As a conservative measure for
the proposed EZ, the sound-level radii indicated by the empirical data
and source models have been increased to 500 m (1,640.4 ft) for the 180
dB (rms) isopleths and to 100 m (328 ft) for the 190 dB isopleth (see
Table 2 of the IHA application). These distances will be used as power-
down/shut-down criteria described in the Proposed Mitigation and
Proposed Monitoring and Reporting sections below. Furthermore,
established 180 and 190 dB (rms) criteria are not considered to be the
level 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 cetaceans. As summarized
above and in Southall et al. (2007), data that are now available imply
that TTS is unlikely to occur in most odontocetes (and probably
mysticetes as well) unless they are exposed to a sequence of several
airgun pulses stronger than 180 or 190 dB re 1 [mu]Pa (rms). Since no
bow-riding species occur in the study area, it is unlikely such
exposures will occur.
Permanent Threshold Shift--When PTS occurs, there is physical
damage to the sound receptors in the ear. In severe cases, there can be
total or partial deafness, whereas in other cases, the animal has an
impaired ability to hear sounds in specific frequency ranges (Kryter,
1985).
There is no specific evidence that exposure to pulses of airgun
sound can cause PTS in any marine mammal, even with large arrays of
airguns. However, given the possibility that mammals close to an airgun
array might incur at least mild TTS, there has been further speculation
about the possibility that some individuals occurring very close to
airguns might incur PTS (Richardson et al., 1995; Gedamke et al.,
2008). Single or occasional occurrences of mild TTS are not indicative
of permanent auditory damage, but repeated or (in some cases) single
exposures to a level well above that causing TTS onset might elicit
PTS.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals, but are assumed to be similar to those in humans and
other terrestrial mammals. PTS might occur at a received sound level at
least several decibels above that inducing mild TTS if the animal were
exposed to strong sound pulses with rapid rise time (see Appendix D (6)
of the IHA application). Based on data from terrestrial mammals, a
precautionary assumption is that the PTS threshold for impulse sounds
(such as airgun pulses as received close to the source) is at least 6
dB higher than the TTS threshold on a peak-pressure basis, and probably
greater than 6 dB (Southall et al., 2007). On an SEL basis, Southall et
al. (2007) estimated that received levels would need to exceed the TTS
threshold by at least 15 dB for there to be risk of PTS. Thus, for
cetaceans they estimate that the PTS threshold might be an M-weighted
SEL (for the sequence of received pulses) of approximately 198 dB re 1
[mu]Pa\2\[middot]s (15 dB higher than the Mmf-weighted TTS
threshold, in a beluga, for a watergun impulse), where the SEL value is
cumulated over the sequence of pulses.
Southall et al. (2007) also note that, regardless of the SEL, there
is concern about the possibility of PTS if a cetacean or pinniped
receives one or more pulses with peak pressure exceeding 230 or 218 dB
re 1 [mu]Pa (peak), respectively. Thus PTS might be expected upon
exposure of cetaceans to either SEL greater than or equal to 198 dB re
1 [mu]Pa\2\[middot]s or peak pressure greater than or equal to 230 dB
re 1 [mu]Pa. Corresponding proposed dual criteria for pinnipeds (at
least harbor seals) are greater than or equal to 186 dB SEL and greater
than or equal to 218 dB peak pressure (Southall et al., 2007). These
estimates are all first approximations, given the limited underlying
data, assumptions, species differences, and evidence that the ``equal
energy'' model may not be entirely correct. A peak pressure of 230 dB
re 1 [mu]Pa (3.2 bar [middot]m, 0-pk), which would only be found within
a few meters of the largest (360 in \3\) airguns in the planned airgun
array (Caldwell and Dragoset, 2000). A peak pressure of 218 dB re 1
[mu]Pa could be received somewhat farther away; to estimate that
specific distance, one would need to apply a model that accurately
calculates peak pressures in the near-field around an array of airguns.
Given the higher level of sound necessary to cause PTS as compared
with TTS, it is considerably less likely that PTS could occur. Baleen
whales generally avoid the immediate area around operating seismic
vessels, as do some other marine mammals. The planned monitoring and
mitigation measures, including visual monitoring, power-downs, and
shut-downs of the airguns when mammals are seen within or approaching
the EZs will further reduce the probability of exposure of marine
mammals to sounds strong enough to induce PTS.
Non-auditory Physiological Effects--Non-auditory physiological
effects or injuries that theoretically might occur in marine mammals
exposed to strong underwater sound include stress, neurological
effects, bubble formation, resonance, and other types of organ or
tissue damage (Cox et al., 2006; Southall et al., 2007). Studies
examining such effects are limited. If any such effects do occur, they
probably would be limited to unusual situations when animals might be
exposed at close range for unusually long periods. It is doubtful that
any single marine mammal would be exposed to strong seismic sounds for
sufficiently long that significant physiological stress would develop.
That is especially so in the case of the proposed project where the
airgun configuration focuses most energy downward, the ship will
typically be moving at four to five knots, and for the most part, the
tracklines will not ``double back'' through the same area. However,
resonance effects (Gentry, 2002) and direct noise-induced bubble
formation (Crum et al., 2005) are implausible in the case of exposure
to an impulsive broadband source like an airgun array. If seismic
surveys disrupt
[[Page 39347]]
diving patterns of deep-diving species, this might perhaps result in
bubble formation and a form of ``the bends,'' as speculated to occur in
beaked whales exposed to sonar. However, there is no specific evidence
of this upon exposure to airgun pulses. Beaked whales do not occur in
the proposed survey area.
In general, little is known about the potential for seismic survey
sounds (or other types of strong underwater sounds) to cause non-
auditory physical effects in marine mammals. Such effects, if they
occur at all, would presumably be limited to short distances and to
activities that extend over a prolonged period. The available data do
not allow identification of a specific exposure level above which non-
auditory effects can be expected (Southall et al., 2007), or any
meaningful quantitative predictions of the numbers (if any) of marine
mammals that might be affected in those ways. Marine mammals that show
behavioral avoidance of seismic vessels, including most baleen whales
and some odontocetes (including belugas), and some pinnipeds, are
especially unlikely to incur non-auditory physical effects. Also, the
planned monitoring and mitigation measures, including shut-down of the
airguns, will reduce any such effects that might otherwise occur.
Strandings and Mortality--Marine mammals close to underwater
detonations of high explosives can be killed or severely injured, and
their auditory organs are especially susceptible to injury (Ketten et
al., 1993; Ketten, 1995). However, explosives are no longer used for
marine waters for commercial seismic surveys or (with rare exceptions)
for seismic research; they have been replaced entirely by airguns or
related non-explosive pulse generators. Airgun pulses are less
energetic and have slower rise times, and there is no proof that they
can cause serious injury, death, or stranding even in the case of large
airgun arrays. However, the association of mass strandings of beaked
whales with naval exercises and, in one case, an L-DEO seismic survey
(Malakoff, 2002; Cox et al., 2006), has raised the possibility that
beaked whales exposed to strong pulsed sounds may be especially
susceptible to injury and/or behavioral reactions that can lead to
stranding (Hildebrand, 2005; Southall et al., 2007). Appendix D(6) of
the USGS IHA application provides additional details.
Specific sound-related processes that lead to strandings and
mortality are not well documented, but may include:
(1) Swimming in avoidance of a sound into shallow water;
(2) A change in behavior (such as a change in diving behavior) that
might contribute to tissue damage, gas bubble formation, hypoxia,
cardiac arrhythmia, hypertensive hemorrhage or other forms of trauma;
(3) A physiological change such as a vetibular response leading to
a behavioral change or stress-induced hemorrhagic diathesis, leading in
turn to tissue damage; and
(4) Tissue damage directly from sound exposure, such as through
acoustically mediated bubble formation and growth or acoustic resonance
of tissues.
Some of these mechanisms are unlikely to apply in the case of
impulse sounds. However, there are increasing indications that gas-
bubble disease (analogous to ``the bends''), induced in supersaturated
tissue by a behavioral response to acoustic exposure, could be a
pathologic mechanism for the strandings and mortality of some deep-
diving cetaceans exposed to sonar. The evidence for this remains
circumstantial and associated with exposure to naval mid-frequency
sonar, not seismic surveys (Cox et al., 2006; Southall et al., 2007).
Seismic pulses and mid-frequency sonar signals are quite different.
Sounds produced by airgun arrays are broadband impulses with most of
the energy below 1 kHz. Typical military mid-frequency sonars operate
at frequencies of 2 to 10 kHz, generally with a relatively narrow
bandwidth at any one time. Thus, it is not appropriate to assume that
there is a direct connection between the effects of military sonar and
seismic surveys on marine mammals. However, evidence that sonar pulses
can, in special circumstances, lead (at least indirectly) to physical
damage and mortality (Balcomb and Claridge, 2001; NOAA and USN, 2001;
Jepson et al., 2003; Fern[aacute]ndez et al., 2004, 2005a; Cox et al.,
2006) suggests that caution is warranted when dealing with exposure of
marine mammals to any high-intensity pulsed sound.
There is no conclusive evidence of cetacean strandings or deaths at
sea as a result of exposure to seismic surveys, but a few cases of
strandings in the general area where a seismic survey was ongoing have
led to speculation concerning a possible link between seismic surveys
and strandings. Suggestions that there was a link between seismic
surveys and strandings of humpback whales in Brazil (Engel et al.,
2004) was not well founded based on available data (IAGC, 2004; IWC,
2007b). In September 2002, there was a stranding of two Cuvier's beaked
whales in the Gulf of California, Mexico, when the L-DEO vessel R/V
Maurice Ewing (Ewing) was operating a 20 airgun, 8,490 in\3\ array in
the general area. The link between the stranding and the seismic survey
was inconclusive and not based on any physical evidence (Hogarth, 2002;
Yoder, 2002). Nonetheless, the Gulf of California incident plus the
beaked whale strandings near naval exercises involving use of mid-
frequency sonar suggests a need for caution when conducting seismic
surveys in areas occupied by beaked whales until more is known about
effects of seismic surveys on those species (Hildebrand, 2005).
However, no beaked whales are found within this project area and the
planned monitoring and mitigation measures are expected to minimize any
possibility for mortality of other species.
Potential Effects of Chirp Echosounder Signals
A Knudsen 320BR Plus echosounder will be operated from the source
vessel at nearly all times during the planned study. Details about the
equipment are provided in Appendix B of the IHA application. The
Knudsen 320BR produces sound pulses with lengths up to 24 ms every 0.5
to approximately 8 s, depending on water depth. The energy in the sound
pulses emitted by the Chirp echosounder is of moderately high
frequency. The Knudsen can be operated with either a 3.5 kHz
transducer, for sub-bottom profiling, or a 12 kHz transducer for
sounding. The lower frequency (3.5 kHz) transducer is not installed and
will not be used. The conical beamwidth for the 12 kHz transducer is
30[deg], and is directed downward.
Source levels for the Knudsen 320 operating at 12 kHz has been
measured as a maximum of 215 dB re 1 [mu]Pam. Received levels would
diminish rapidly with increasing depth. Assuming spherical spreading,
received level directly below the transducer(s) would diminish to 180
dB re 1 [mu]Pa at distances of about 56 m (183.7 ft) when operating at
12 kHz. The 180 dB distance in the horizontal direction (outside the
downward-directed beam) would be substantially less. Kremser et al.
(2005) noted that the probability of a cetacean swimming through the
area of exposure when a bottom profiler emits a pulse is small, and if
the animal was in the area, it would have to pass the transducer at
close range in order to be subjected to sound levels that could cause
TTS.
Navy sonars that have been linked to avoidance reactions and
stranding of cetaceans (1) generally are more powerful than the Knudsen
320BR operating with the 12 kHz transducer,
[[Page 39348]]
(2) have longer pulse duration, and (3) are directed close to
horizontally vs. downward for the Knudsen 320. The area of possible
influence of the Chirp echosounder is much smaller--a narrow conical
beam spreading downward from the vessel. Marine mammals that encounter
the sounder at close range are unlikely to be subjected to repeated
pulses because of the narrow width of the beam, and will receive only
small amounts of pulse energy because of the short pulses.
Marine mammal communications will not be masked appreciably by the
Chirp echosounder signals given its relatively low duty cycle,
directionality, and the brief period when an individual mammal is
likely to be within its beam. Belugas can, however, hear sounds ranging
from 1.2 to 120 kHz; their peak sensitivity is approximately 10 to 15
kHz, overlapping with the 12 kHz signals (Fay, 1988). Some level of
masking could result for beluga whales in close proximity to the survey
vessel during brief periods of exposure to the sound. However, masking
is unlikely to be an issue for beluga whales because belugas are likely
to avoid survey vessels. The 12 kHz frequency signals will not overlap
with the predominant low frequencies in baleen whale calls, thus
reducing potential for masking in this group.
Marine mammal behavioral reactions to pulsed sound sources from an
active airgun array are discussed above, and responses to the
echosounder are likely to be similar to those for other pulsed sources
if received at the same levels. When the 12 kHz transducer is in
operation, the behavioral responses to the Knudsen 320BR are expected
to be similar to those reactions to the active airgun array (as
discussed above). Because of the lower source level and high
directionality, NMFS expects animals to be only infrequently exposed to
higher levels of sound and in short durations, and therefore NMFS does
not anticipate that exposure to the echosounder will result in a
``take'' by harassment.
When the 12 kHz transducer is operating, the pulses are brief and
concentrated in a downward beam. A marine mammal would be in the beam
of the echosounder only briefly, reducing its received sound energy.
Thus, it is unlikely that the chirp echosounder produces pulse levels
strong enough to cause hearing impairment or other physical injuries
even in an animal that is (briefly) in a position near the source.
The Knudsen 320 BR will be operated simultaneously with the airgun
array. Many marine mammals will move away in response to the
approaching higher-power sources of the vessel itself before the
mammals would be close enough for there to be any possibility of
effects from the Chirp echosounder (see Appendix D of the IHA
application).
Potential Effects of Other Acoustic Devices--Chirp SBP Signals
A Knudsen 3260 SBP will be operated from the St. Laurent in open
water when the St. Laurent is not working in tandem with the Healy
during the planned study. The Knudsen's transducer will be towed behind
the St. Laurent. Details about the equipment are provided in Appendix B
of the IHA application. The chirp system has a maximum 7.2 kW transmit
capacity into the towed array and generally operated at 3 to 5 kHz. The
energy from the towed unit is directed downward by an array of eight
transducers in a conical beamwidth of 80[deg]. The interval between
pulses will be no less than one pulse per second. SBPs of that
frequency can produce sound levels of 200 to 230 dB re 1 [mu]Pa at 1 m
(Richardson et al., 1995).
Marine mammal communications will not be masked appreciably by the
SBP signals given their relatively low duty cycle, directionality of
the signal and the brief period when an individual mammal is likely to
be within its beam. In the case of the most odontocetes, the 3 to 5 kHz
chirp signals do not overlap with the predominant frequencies in their
calls, which would avoid significant masking. Beluga whale is the only
odontocete anticipated in the area of the proposed survey. Though
belugas can hear sounds ranging from 1.2 to 120 kHz, their peak
sensitivity is approximately 10 to 15 kHz, not overlapping with the 3
to 5 kHz signals (Fay, 1988). Furthermore, in the case of most baleen
whales, the low-energy SBP signals do not overlap with the predominant
low frequencies in the calls, which would reduce potential for masking.
Marine mammal behavioral reactions to other pulsed sound sources
are discussed above, and responses to the SBP are likely to be similar
to those for other pulsed sources if received at the same levels. The
pulsed signals from the SBP are somewhat weaker than those from the
airgun array. Therefore, behavioral responses are not expected unless
marine mammals are very close to the source.
The pulses from the chirp profiler are brief and directed downward.
A marine mammal would be in the beam of the SBP only briefly, reducing
its received sound energy. Thus, it is unlikely that the SBP produces
pulse levels strong enough to cause hearing impairment or other
physical injuries even if an animal is (briefly) in a position near the
surface. It is unlikely that the SBP produces pulse levels strong
enough to cause hearing impairment or other physical injuries even in
an animal that is (briefly) in a position near the source. The SBP is
operated simultaneously with other higher-power acoustic sources,
including the airguns. Many marine mammals will move away in response
to the approaching higher-power sources or the vessel itself before the
mammals would be close enough for there to be any possibility of
effects from the less intense sounds from the SBP. In the case of
mammals that do not avoid the approaching vessel and its various sound
sources, monitoring and mitigation measures that would be applied to
minimize effects of other sources would further reduce or eliminate any
minor effects of the SBP.
Potential Effects of Other Acoustic Devices--MBES Signals
The Kongsberg EM 122 MBES will be operated from the Healy
continuously during the planned study. Sounds from the MBES are very
short pulses, depending on water depth. Most of the energy in the sound
pulses emitted by the MBES is at frequencies centered at 12 kHz. The
beam is narrow (approximately 2[deg]) in fore-aft extent and wide
(approximately 130[deg]) in the cross-track extent. Any given mammal at
depth near the trackline would be in the main beam for only a fraction
of a second. Therefore, marine mammals that encounter sound from the
MBES at close range are unlikely to be subjected to repeated pulses
because of the narrow fore-aft width of the beam and will receive only
limited amounts of pulse energy because of the short pulses. Similarly,
Kremser et al. (2005) noted that the probability of a cetacean swimming
through the area of exposure when an MBES emits a pulse is small. The
animal would have to pass the transducer at close range and be swimming
at speeds similar to the vessel in order to be subjected to sound
levels that could cause TTS. In 2008 and 2009 the St. Laurent and the
Healy surveyed together with a cooperative strategy similar to that
proposed for 2010. The director of NOAA's Office of Ocean Exploration
and Research deemed that the use of the Healy's MBES would not have
significant impacts on marine mammals of a direct or cumulative nature.
The U.S. portions of the projects were granted a Categorical Exclusion
from the need to prepare an EA.
Navy echosounders that have been linked to avoidance reactions and
[[Page 39349]]
stranding of cetaceans (1) generally are more powerful than the
Kongsberg EM122 echosounder, (2) generally have a longer pulse duration
than the Kongsberg EM 122, and (3) are often directed close to
horizontally vs. more downward for the MBES. The area of possible
influence of the MBES is much smaller--a narrow band oriented in the
cross-track direction below the source vessel. Marine mammals that
encounter the MBES at close range are unlikely to be subjected to
repeated pulses because of the narrow fore-aft width of the beam, and
will receive only small amounts of pulse energy because of the short
pulse. In assessing the possible impacts of a similar MBES system (the
15.5 kHz Atlas Hydrosweep MBES), Boebel et al. (2004) noted that the
critical sound pressure level at which TTS may occur is 203.2 dB re 1
[micro]Pa (rms). The critical region included an area of 43 m (141.1
ft) in depth, 46 m (151 ft) wide athwartship, and 1 m fore-and-aft
(Boebel et al., 2004). In the more distant parts of that (small)
critical region, only slight TTS would be incurred.
Marine mammal communications will not be masked appreciably by the
MBES signals given its low duty cycle of the MBES and the brief period
when an individual mammal is likely to be within its beam. Furthermore,
the MBES signals (12 kHz) do not overlap with the predominant
frequencies in the baleen whale calls, further reducing any potential
for masking in that group.
Behavioral reactions of free-ranging marine mammals to sonars,
echosounders, and other sound sources appear to vary by species and
circumstance. Observed reactions have included silencing and dispersal
by sperm whales (Watkins et al., 1985), increased vocalizations and no
dispersal by pilot whales (Rendell and Gordon, 1999), and the
previously-mentioned beachings by beaked whales. Also, Navy personnel
have described observations of dolphins bow-riding adjacent to bow-
mounted mid-frequency sonars during sonar transmissions. During
exposure to a 21 to 25 kHz ``whale-finding'' sonar with a source level
of 215 dB re 1 [mu]Pam, gray whales reacted by orienting slightly away
from the source and being deflected from their course by approximately
200 m (656 ft) (Frankel, 2005). However, all of those observations are
of limited relevance to the present situation. Pulse durations from the
Navy sonars were much longer than those of the MBESs to be used during
the proposed study, and a given mammal would have received many pulses
from the naval sonars. During the USGS operations, the individual
pulses will be very short, and a given marine mammal would not receive
many of the downward-directed pulses as the vessel passes by.
Captive bottlenose dolphins and a beluga whale exhibited changes in
behavior when exposed to 1 s pulsed signals at frequencies similar to
those that will be emitted by the MBES used by USGS, and to shorter
broadband pulsed signals. Behavioral changes typically involved what
appeared to be deliberate attempts to avoid the sound exposure
(Schlundt et al., 2000; Finneran et al., 2002; Finneran and Schlundt,
2004). The relevance of those data to free-ranging odontocetes is
uncertain, and in any case, the test sounds were quite different in
either duration or bandwidth as compared with those from a MBES.
USGS is not aware of any data on the reactions of pinnipeds to
echosounder sounds at frequencies similar to those of the MBES (12
kHz). Based on observed pinniped responses to other types of pulsed
sounds, and the likely brevity of exposure to the MBES, pinniped
reactions to the echosounder sounds are expected to be limited to
startle or otherwise brief responses of no lasting consequence to the
animals.
Given recent stranding events that have been associated with the
operation of naval sonar, there is concern that mid-frequency sonar
sounds can cause serious impacts to marine mammals (see above).
However, the MBES proposed for use by USGS is quite different from
sonars used for Navy operations. Pulse duration of the bathymetric
echosounder is very short relative to the naval sonars. Also, at any
given location, an individual cetacean or pinniped would be in the beam
of the MBES for much less time given the generally downward orientation
of the beam and its narrow fore-aft beamwidth. (Navy sonars often use
near-horizontally-directed sound.) Those factors would all reduce the
sound energy received from the bathymetric echosounder relative to that
from the sonars used by the Navy.
NMFS believes that the brief exposure of marine mammals to one
pulse, or small numbers of signals, from the MBES are not likely to
result in the harassment of marine mammals.
Possible Effects of Helicopter Activities
It is anticipated that a helicopter will be deployed daily, weather
permitting to conduct ice reconnaissance as well as to periodically
transfer personnel between the two vessels. The helicopter will also be
used to collect spot bathymetry data during operations in Canadian and
international waters, outside of U.S. waters. The spot soundings will
be recorded to maximize the area surveyed and the data will be
collected off the ship's survey lines. A 12 kHz transducer will be
slung by the helicopter and placed in the water down to a mark affixed
to the tether. Data will then be logged to a laptop computer in the
helicopter.
Levels and duration of sounds received underwater from a passing
helicopter are a function of the type of helicopter used, orientation
of the helicopter, the depth of the marine mammal, and water depth. A
CCG helicopter, a Messerschmitt MBB BO105, will be providing air
support for this project. Helicopter sounds are detectable underwater
at greater distances when the receiver is at shallow depths. Generally,
sound levels received underwater decrease as the altitude of the
helicopter increases (Richardson et al., 1995). Helicopter sounds are
audible for much greater distances in air than in water.
Cetaceans--The nature of sounds produced by helicopter activities
above the surface of the water do not pose a direct threat to the
hearing of marine mammals that are in the water; however minor and
short-term behavioral responses of cetaceans to helicopters have been
documented in several locations, including the Beaufort Sea (Richardson
et al., 1985a,b; Patenaude et al., 2002). Cetacean reactions to
helicopters depend on several variables including the animal's
behavioral state, activity, group size, habitat, and the flight
patterns used, among other variables (Richardson et al., 1995). During
spring migration in the Beaufort Sea, beluga whales reacted to
helicopter noise more frequently and at greater distances than did
bowhead whales (38 percent vs. 14 percent of observations,
respectively). Most reaction occurred when the helicopter passed within
250 m (820.2 ft) lateral distance at altitudes less than or equal to
150 m (492.1 ft). Neither species exhibited noticeable reactions to
single passes at altitudes greater than 150 m (492.1 ft). Belugas
within 250 m (820.2 ft) of stationary helicopters on the ice with the
engine showed the most overt reactions (Patenaude et al., 2002). Whales
were observed to make only minor changes in direction in response to
sounds produced by helicopters, so all reactions to helicopters were
considered brief and minor. Cetacean reactions to helicopter
disturbance are difficult to predict and may range from no reaction at
all to minor changes in course or (infrequently) leaving the immediate
area of the activity.
Pinnipeds--Few systematic studies of pinniped reactions to aircraft
overflights
[[Page 39350]]
have been completed. Documented reactions range from simply becoming
alert and raising the head to escape behavior such as hauled-out
animals rushing to the water. Ringed seals hauled out on the surface of
the ice have shown behavioral responses to aircraft overflights with
escape responses most probable at lateral distances greater than 200 m
(656.2 ft) and overhead distances less than or equal to 150 m (492.1
ft) (Born et al., 1999). Although specific details of altitude and
horizontal distances are lacking from many largely anecdotal reports,
escape reactions to a low flying helicopter (less than 150 m [492.1 ft]
altitude) can be expected from all four species of pinnipeds
potentially encountered during the proposed operations. These responses
would likely be relatively minor and brief in nature. Whether any
response would occur when a helicopter is at the higher suggested
operational altitudes (below) is difficult to predict and probably a
function of several other variables including wind chill, relative wind
chill, and time of day (Born et al., 1999).
As mentioned in the previous section, momentary behavioral
reactions ``do not rise to the level of taking'' (NMFS, 2001). In order
to limit behavioral reactions of marine mammals during ice
reconnaissance and spot bathymetry work outside of U.S. waters, the
helicopter will maintain a minimum altitude of 200 m (656 ft) above the
sea ice except when taking off, landing, or conducting spot bathymetry.
Sea-ice landings are not planned at this time.
Possible Effects of Icebreaking Activities
Icebreakers produce more noise while breaking ice than ships of
comparable size due, primarily, to the sounds of the propeller
cavitating (Richardson et al., 1995). Multi-year ice, which is expected
to be encountered in the northern and eastern areas of the proposed
survey, is thicker than younger ice. Icebreakers commonly back and ram
into heavy ice until losing momentum to make way. The highest noise
levels usually occur while backing full astern in preparation to ram
forward through the ice. Overall, the noise generated by an icebreaker
pushing ice was 10 to 15 dB greater than the noise produced by the ship
underway in open water (Richardson et al., 1995). In general, the
Arctic Ocean is a noisy environment. Greening and Zakarauskas (1993)
reported ambient sound levels of up to 180 dB/[mu]Pa\2\/Hz under multi-
year pack ice in the central Arctic pack ice. Little information is
available about the effect to marine mammals of the increased sound
levels due to icebreaking.
Cetaceans--Few studies have been conducted to evaluate the
potential interference of icebreaking noise with marine mammal
vocalizations. Erbe and Farmer (1998) measured masked hearing
thresholds of a captive beluga whale. They reported that the recording
of a CCG ship, Henry Larsen, ramming ice in the Beaufort Sea, masked
recordings of beluga vocalizations at a noise to signal pressure ratio
of 18 dB, when the noise pressure level was eight times as high as the
call pressure. Erbe and Farmer (2000) also predicted when icebreaker
noise would affect beluga whales through software that combined a sound
propagation model and beluga whale impact threshold models. They again
used the data from the recording of the Henry Larsen in the Beaufort
Sea and predicted that masking of beluga vocalizations could extend
between 40 and 71 km (24.9 and 44.1 mi) near the surface. Lesage et al.
(1999) report that beluga whales changed their call type and call
frequency when exposed to boat noise. It is possible that the whales
adapt to the ambient noise levels and are able to communicate despite
the sound. Given the documented reaction of belugas to ships and
icebreakers it is highly unlikely that beluga whales would remain in
the proximity of vessels where vocalizations would be masked.
Beluga whales have been documented swimming rapidly away from ships
and icebreakers in the Canadian high Arctic when a ship approaches to
within 35 to 50 km (21.4 to 31.1 mi), and they may travel up to 80 km
(49.7 mi) from the vessel's track (Richardson et al., 1995). It is
expected that belugas avoid icebreakers as soon as they detect the
ships (Cosens and Dueck, 1993). However, the reactions of beluga whales
to ships vary greatly and some animals may become habituated to higher
levels of ambient noise (Erbe and Darmber, 2000).
There is little information about the effects of icebreaking ships
on baleen whales. Migrating bowhead whales appeared to avoid an area
around a drill site by greater than 25 km (15.5 mi) where an icebreaker
was working in the Beaufort Sea. There was intensive icebreaking daily
in support of the drilling activities (Brewer et al., 1993). Migrating
bowheads also avoided a nearby drill site at the same time of year
where little icebreaking was being conducted (LGL and Greeneridge,
1987). It is unclear as to whether the drilling activities, icebreaking
operations, or the ice itself might have been the cause for the whales'
diversion. Bowhead whales are not expected to occur in the proximity of
the proposed action area.
Pinnipeds--Brueggeman et al. (1992) reported on the reactions of
seals to an icebreaker during activities at two prospects in the
Chukchi Sea. Reactions of seals to the icebreakers varied between the
two prospects. Most (67 percent) seals did not react to the icebreaker
at either prospect. Reaction at one prospect was greatest during
icebreaking activity followed by general vessel activity (running/
maneuvering/jogging) and was 0.23 km (0.14 mi) of the vessel and lowest
for animals beyond 0.93 km (0.58 mi). At the second prospect however,
seal reaction was lowest during icebreaking activity with higher and
similar levels of response during general (non-icebreaking) vessel
operations and when the vessel was at anchor or drifting. The frequency
of seal reaction generally declined with increasing distance from the
vessel except during general vessel activity where it remained
consistently high to about 0.46 km (0.29 mi) from the vessel before
declining.
Similarly, Kanik et al. (1980) found that ringed and harp seals
often dove into the water when an icebreaker was breaking ice within 1
km (0.6 mi) of the animals. Most seals remained on the ice when the
ship was breaking ice 1 to 2 km (0.6 to 1.2 mi) away.
Estimated Take of Marine Mammals by Incidental Harassment
All anticipated takes would be ``takes by Level B harassment,''
involving temporary changes in behavior. The proposed monitoring and
mitigation measures are expected to minimize the possibility of
injurious takes or mortality. However, as noted earlier, there is no
specific information demonstrating that injurious ``takes'' or
mortality would occur even in the absence of the planned monitoring and
mitigation measures. NMFS believes, therefore, that injurious take or
mortality to the affected species marine mammals is extremely unlikely
to occur as a result of the specified activities within the specified
geographic area for which USGS seeks the IHA. The sections below
describe methods to estimate ``take by harassment,'' and present
estimates of the numbers of marine mammals that could be affected
during the proposed seismic study in the Arctic Ocean. The estimates of
``take by harassment,'' are based on data obtained during marine mammal
surveys in and near the Arctic Ocean by Stirling et al. (1982),
Kingsley (1986), Moore et al. (2000b), Haley and Ireland (2006), Haley
(2006), GSC unpublished data (2008), and Mosher et al. (2009), Bowhead
Whale Aerial Survey Program (BWASP), and on estimates of the sizes
[[Page 39351]]
of the areas where effects could potentially occur. In some cases these
estimates were made from data collected from regions and habitats that
differed from the proposed project area.
Detectability bias, quantified in part by [fnof](0), is associated
with diminishing sightability with increasing lateral distance from the
trackline. Availability bias (g[0]) refers to the fact that there is
less than 100 percent probability of sighting an animal that is present
along the survey trackline. Some sources of densities used below
included these correction factors in their reported densities. In other
cases the best densities used below included these correction factors
in their reported densities. In other cases the best available
correction factors were applied to reported results when they had not
been included in the reported data (Moore et al., 2000b). Adjustments
to reported population or density estimates were made on a case by case
basis to take into account differences between the source data and the
general information on the distribution and abundance of the species in
the proposed project area.
Although several systematic surveys of marine mammals have been
conducted in the southern Beaufort Sea, few data (systematic or
otherwise) are available on the distribution and numbers of marine
mammals in the northern Beaufort Sea or offshore water of the Arctic
Ocean. The main sources of distributional and numerical data used in
deriving the estimates are described in the next subsection. Both
``maximum estimates'' as well as ``best estimates'' of marine mammal
densities (see Table 5 of the IHA application) and the numbers of
marine mammals potentially exposed to underwater sound (see Table 6 of
the IHA application) were calculated as described below. The best (or
average) estimate is based on available distribution and abundance data
and represents the most likely number of animals that may be
encountered during the survey, assuming no avoidance of the airguns or
vessel. The maximum estimate is either the highest estimate from
applicable distribution and abundance data or the average estimate
increased by a multiplier intended to produce a very conservative
(over) estimate of the number of animals that may be present in the
survey area. There is some uncertainty about how representative the
available data are and the assumptions used below to estimate the
potential ``take by harassment.'' However, the approach used here is
accepted by NMFS as the best available at this time.
USGS has calculated exposures to marine mammals within U.S. waters
only. After the St. Laurent (a Canadian icebreaker) exits U.S. waters,
their activities no longer fall under the jurisdiction of the U.S. or
the MMPA.
The following estimates are based on a consideration of the number
of marine mammals that might be disturbed appreciably over the
approximately 806 line km (501 mi) of seismic surveys within U.S.
waters across the Arctic Ocean. An assumed total of 1,007.5 km (626 mi)
of trackline includes a 25 percent allowance over and above the planned
approximately 806 km to allow for turns, lines that might have to be
repeated because of poor data quality, or for minor changes to the
survey design.
The anticipated radii of influence of the lower energy sound
sources including Chirp echosounder (on the St. Laurent) and
bathymetric echosounder (on the Healy) are less than that for the
airgun configuration. It is assumed that during simultaneous operations
of the airgun array and echosounder, any marine mammals close enough to
be affected by the sounder would already be affected by the airguns.
However, whether or not the airguns are operating simultaneously with
the echosounder, marine mammals are expected to exhibit no more than
short-term and inconsequential responses to the sounder given its
characteristics (e.g., narrow downward-directed beam) and other
considerations described in the IHA application. Similar responses are
expected from marine mammals exposed to the Healy's bathymetric
profiler. Such reactions are not considered to constitute ``taking'' as
defined by NMFS (NMFS, 2001). Therefore, no additional allowance is
included for animals that might be exposed to sound sources other than
the airguns.
Marine Mammal Density Estimates
Numbers of marine mammals that might be present and potentially
disturbed are estimated based on available data about marine mammal
distribution and densities in the Arctic Ocean study area during the
summer. ``Take by harassment'' is calculated by multiplying expected
densities of marine mammals likely to occur in the survey area by the
area of water potentially ensonified to sound levels >=160 dB re 1
[mu]Pa (rms) for the airgun operations and >=120 dB re 1 [mu]Pa (rms)
for icebreaking activities. Estimates for icebreaking are based on a
consideration of the number of marine mammals that might be disturbed
appreciably over the approximately 3,102 to 3,372 line km (1,927.5 to
2,095.3 mi) of icebreaking that may occur during the proposed project.
This section provides descriptions of the estimated densities of marine
mammals that may occur in the proposed survey area. The area of water
that may be ensonified to the indicated sound level is described
further below. There is no evidence that avoidance at received sound
levels >=160 dB would have significant effects on individual animals or
that the subtle changes in behavior or movements would rise to the
level of taking according to guidance by NMFS (NMFS, 2001).
Some surveys of marine mammals have been conducted near the
southern end of the proposed project area, but few data are available
on the species and abundance of marine mammals in the northern Beaufort
Sea and the Arctic Ocean. No published densities of marine mammals are
available for the region of the proposed survey (including between
74[deg] and 84[deg] North where the Healy will be breaking ice outside
U.S. waters), although vessel-based surveys through the general area in
2005, 2006, 2008, and 2009 encountered few marine mammals. A total of
two polar bears, 36 seals, and a single beluga whale sighting(s) were
recorded along approximately 2,299 km (1,429 mi) of monitored trackline
between 71[deg] North and 74[deg] North (Haley and Ireland, 2006;
Haley, 2006; GSC unpublished data, 2008; Mosher et al., 2009). PSOs
recorded 268 sightings of 291 individual seals along approximately
21,322 km (13,248.9 mi) of monitored trackline between 74[deg] and
84[deg] North (Haley and Ireland, 2006; Haley, 2006; GSC unpublished
data, 2008; Mosher et al., 2009). No cetaceans were observed during the
surveys between 74[deg] and 84[deg] North. Given the few sightings of
marine mammals along the 21,322 km (13,248.9 mi) vessel trackline in
previous years, USGS estimate that the densities of marine mammals
encountered while breaking ice will be 1/10 of the estimated densities
of marine mammals encountered within the ice margin habitat described
in the original application.
Given that the survey lines within U.S. waters extend from
latitudes 71[deg] to 74[deg] North, it is likely that seismic
operations will be conducted in both open-water and sea-ice conditions.
Because densities of marine mammals often differ between open-water and
pack-ice areas, the likely extent of the pack-ice at the time of the
survey was estimated. Images of average monthly sea ice concentration
for August from 2005 through 2009, available from the National Snow and
Ice Data Center
[[Page 39352]]
(NISDC), were used to identify 74[deg] North latitude as a reasonable
ice-edge boundary applicable to the proposed study period and location.
Based on these satellite data, the majority of the survey in U.S.
waters will be conducted in open water and unconsolidated pack ice, in
the southern latitudes of the survey area. This region will include the
ice margin where the highest densities of cetaceans and pinnipeds are
likely to be encountered. The proposed survey lines within U.S. waters
reach approximately 74.10[deg] North, extending within the estimated
ice-edge boundary for August, 2010 by approximately 19 km (10 mi). This
comprises less than 3 percent of the total trackline within U.S.
waters. USGS has divided the survey effort between the two habitat
zones of open water and ice margin based on the 2005 to 2009 NSIDC
satellite data described above and the planed location of the
tracklines. NSIDC data from 2005 to 2009 suggests little ice will be
present south of 74[deg] North, although data from the 2009 cruise
(Moser et al., 2009) shows that inter-annual variability could result
in a greater amount of ice being encountered than expected. As a
conservative measure, USGS estimated that, within U.S. waters, 80
percent of the survey tracklines will occur in open water and 20
percent of the tracklines will occur within the ice margin.
The NSIDC (2009) reported that more Arctic sea ice cover in 2009
remained after the summer than in the record-setting low years of 2007
and 2008. USGS expects that sea ice density and extent in 2010 will be
closer to the density and extent of sea ice in 2009 rather than the
record-setting low years of 2007 and 2008. All animals observed during
the 2009 survey (Mosher et al., 2009) were north of the proposed
seismic survey area, i.e., north of 74[deg] North.
Cetaceans--Average and maximum densities for each cetacean species
or species group reported to occur in U.S. waters of the Arctic Ocean,
within the study area, are presented in Table 5 of the IHA application.
Densities were calculated based on the sightings and effort data from
available survey reports. No cetaceans were observed during surveys
near the proposed study area in August/September, 2005 (Haley and
Ireland, 2006), August, 2006 (Haley, 2006), August/September, 2008 (GSC
unpublished data, 2008) or August/September, 2009 (Mosher et al.,
2009).
Seasonal (summer and fall) differences in cetacean densities along
the north coast of Alaska have been documented by Moore et al. (2000b).
The proposed survey will be conducted in U.S. waters from approximately
August 6 to 12, 2010 and is considered to occur during the summer
season.
The summer beluga density (see Table 5 of the IHA application) was
based on 41 sightings along 9,022 km (5,606 mi) of on-transect effort
that occurred over water greater than 2,000 m (6,561.7 ft) during the
summer in the Beaufort Sea (Moore et al., 2000b; see Table 2 of the IHA
application). A mean group size of 2.8 derived from BWASP data of
August beluga sightings in the Beaufort Sea in water depths greater
than 2,000 m was used in the density calculation. A [fnof](0) value of
2.326 from Innes et al. (1996) and a g(0) value of 0.419 from Innes et
al. (1996) and Harwood et al. (1996) were also used in the density
computation. The CV associated with group size was used to select an
inflation factor of 2 to estimate the maximum density that may occur in
the proposed study area within U.S. waters. Most Moore et al. (2000b)
sightings were south of the proposed seismic survey. However, Moore et
al. (2000b) found that beluga whales were associated with both light (1
to 10 percent) and heavy (70 to 100 percent) ice cover. Five of 23
beluga whales that Suydam et al. (2005) tagged in Kaseglauk Lagoon
(northeast Chukchi Sea) traveled to 79 to 80[deg] North into the pack
ice and within the region of the proposed survey. These and other
tagged whales moved into areas as far as 1,100 km (594 nmi) offshore
between Barrow and the Mackenzie River delta, spending time in water
with 90 percent ice coverage. Therefore, we applied the observed
density calculated from the Moore et al. (2000b) sightings as the
average density for both ``open water'' and ``ice margin'' habitats.
Because no beluga whales were sighted during surveys in the proposed
survey area (Harwood et al., 2005; Haley and Ireland, 2006; Haley,
2006; GSC unpublished data, 2008; and Mosher et al., 2009) the
densities in Table 5 of the IHA application are probably higher than
densities likely to be encountered.
By the time the survey begins in early August, most bowhead whales
have typically traveled east of the proposed project area to summer in
the eastern Beaufort Sea and Amundsen Gulf. Industry aerial surveys of
the continental shelf near Camden Bay in 2008 recorded eastward
migrating bowhead whales until July 12 (Lyons and Christie, 2009). No
bowhead sightings were recorded again despite continued flights until
August 19, 2010. A summer bowhead whale density was derived from 9,022
km (5,606 mi) of summer (July/August) aerial survey effort reported by
Moore et al. (2000b) in the Alaska Beaufort Sea during which six
sightings of bowhead whales were documented in water greater than 2,000
m (6,561.7 ft). A mean group size of bowhead whale sightings in
September, in waters greater than 2,000 m deep, was calculated to be
1.14 (CV= 0.4) from BWASP data. A [fnof](0) value of 2.33 and g(0)
value of 0.073, both from Thomas et al. (2002) were used to estimate a
summer density for bowhead whales of 0.0122 whales/km\2\. This density
falls within the range of densities, i.e., 0.0099 to 0.0717 whales/
km\2\, reported by Lyons and Christie (2009) based on data from three
July, 2008 surveys.
Treacy et al. (2006) reported that in years of heavy ice
conditions, bowhead whales occur farther offshore than in years of
light to moderate ice. NSIDC (2009) reported that September, 2009 had
the third lowest sea ice extent since the start of their satellite
records in 1979. The extent of sea ice at the end of the 2009 Arctic
summer, however, was greater than in 2007 or 2008. USGS does not expect
2010 to be a heavy ice year during which bowhead whales might occur
farther offshore in the area of the proposed survey. During the lowest
ice-cover year on record (2007), BWASP reported no bowhead whale
sightings in the greater than 2,000 m depth waters far offshore.
Because few bowhead whales have been documented in the deep offshore
waters of the proposed survey area, half of the bowhead whale density
estimate from size and standard error reported in Thomas et al. (2002)
for [fnof](0) and g(0) correction factors suggest that an inflation
factor of two is appropriate for estimating the maximum density from
the average density. NSIDC did not forecast that 2010 would be a heavy
ice year and USGS anticipates that bowheads will remain relatively
close to shore, and in areas of light ice coverage. Therefore, USGS has
applied the same density for bowheads to the open-water and ice-margin
categories. Bowhead whales were not sighted during recent surveys in
the Arctic Ocean (Haley and Ireland, 2006; Haley, 2006; GSC unpublished
data, 2008; Mosher et al., 2009), suggesting that the bowhead whale
densities shown in Table 5 are likely higher than actual densities in
the survey area.
For other cetacean species that may be encountered in the Beaufort
Sea, densities are likely to be very low in the summer when the survey
is scheduled. Fin and humpback whales are unlikely to occur in the
Beaufort Sea. No gray whales were observed in the Beaufort Sea by Moore
et al. (2000b) during summer aerial surveys in water greater than 2,000
m. Gray whales were not recorded in water greater than 2,000 m by the
BWASP during August in 29
[[Page 39353]]
years of survey operation. Harbor porpoises are not expected to be
present in large numbers in the Beaufort Sea during the fall although
small numbers may be encountered during the summer. Neither gray whales
nor harbor porpoises are likely to occur in the far-offshore waters of
the proposed survey area (Table 5 of the IHA application). Narwhals are
not expected to be encountered within the survey area although a few
individuals could be present if ice is nearby. Because these species
occur so infrequently in the Beaufort Sea, little to no data are
available for the calculation of densities. Minimal cetacean densities
have therefore been assigned to these three species for calculation
purposes and to allow for chance encounters (see Table 5 of the IHA
application). Those densities include ``0'' for the average and 0.0001
individuals/km\2\ for the maximum.
Pinnipeds--Extensive surveys of ringed and bearded seals have been
conducted in the Beaufort Sea, but most surveys were conducted over the
landfast ice during aerial surveys, and few seal surveys have occurred
in open water or in the pack ice. Kingsley (1986) conducted ringed seal
surveys of the offshore pack ice in the central and eastern Beaufort
Sea during the late spring (late June). These surveys provide the most
relevant information on densities of ringed seals in the ice margin
zone of the Beaufort Sea. The density estimate in Kingsley (1986) was
used as the average density of ringed seals that may be encountered in
the ice-margin area of the proposed survey (see Table 5 of the IHA
application). The average density was multiplied by four to estimate
maximum density, as was done for all seal species likely to occur
within the survey area. Ringed seals are closely associated with sea
ice therefore the ice-margin densities were multiplied by a factor of
0.75 to estimate a summer open-water ringed-seal density for locations
with water depth greater than 2,000 m (6,561.7 ft).
Densities of bearded seals were estimated by multiplying the ringed
seal densities by 0.051 based on the proportion of bearded seals to
ringed seals reported in Stirling et al., (1982; see Table 6-3 of IHA
application). Because bearded seals are associated with the pack ice
edge and shallow water, their estimated summer ice-margin density was
also multiplied by a factor of 0.75 for the open-water density
estimate. Minimal values were used to estimate spotted seal densities
because they are uncommon offshore in the Beaufort Sea and are not
likely to be encountered.
Numbers of marine mammals that might be present and potentially
disturbed are estimated below based on available data about marine
mammal distribution and densities in the three different habitats
during the summer as described in Table 5 of the IHA application.
The number of individuals of each species potentially exposed to
received levels greater than or equal to 160 dB re 1 [micro]Pa (rms)
(for seismic airgun operations) or 120 dB re 1 [mu]Pa (rms) (for
icebreaking) was estimated by multiplying
The anticipated area to be ensonified to the specified
sound level in both open water, the ice margin, and polar pack by
The expected species density.
Some of the animals estimated to be exposed to sound levels greater
than or equal to 160 dB re 1 [mu]Pa (rms) or 120 dB re 1 [mu]Pa (rms),
particularly migrating bowhead whales, might show avoidance reactions
before actual exposure to this sound level (see Appendix D of the IHA
application). Thus, these calculations actually estimate the number of
individuals potentially exposed to greater than or equal to 160 dB
(rms) or 120 dB re 1 [micro]Pa (rms) that would occur if there were no
avoidance of the area ensonified to that level.
Estimated Area Exposed to >= 160 dB (rms)
The area of water potentially exposed to received levels greater
than or equal to 160 dB by the proposed operations was calculated by
multiplying the planned trackline distance within U.S. waters by the
cross-track distance of the sound propagation. The airgun array of two
500 in\3\ and one 150 in\3\ G-airguns that will be used for the
proposed 2010 survey within U.S. waters was measured during a 2009
project in the Arctic Ocean. The propagation experiment took place at
74[deg] 50.4' North; 156[deg] 34.31' West, in 3,863 m (12,674 ft) of
water. The location was near the northern end of the two proposed
survey lines in U.S. waters. USGS expects the sound propagation by the
airgun array in the planned 2010 survey will be the same as that
measured in 2009, because of the similar water depths and relative
locations of the test site and proposed survey area. The greater than
or equal to 160 dB (rms) sound level radius was estimated to be
approximately 2,500 m (8,202.1 ft) based on modeling of the 0 to peak
energy of the airgun array (Roth and Schmidt, 2010). The 0 to peak
values were corrected to rms by subtracting 10 dB.
Closely spaced survey lines and large cross-track distances of the
greater than or equal to 160 dB radii can result in repeated exposure
of the same area of water. Excessive amounts of repeated exposure can
lead to overestimation of the number of animals potentially exposed
through double counting. The trackline for the proposed USGS survey in
U.S. waters, however, covers a large geographic area without adjacent
tracklines and the potential for multiple or repeated exposure is
unlikely to be a concern.
The USGS 2010 geophysical survey is planned to occur approximately
108 km (67.1 mi) offshore, along approximately 806 km (501 mi) of
survey lines in U.S. waters, during the first half of August exposing a
total of approximately 4,109 km\2\ (1,586.5 mi\2\) of water to sound
levels of greater than or equal to 160 dB (rms).USGS included an
additional 25 percent allowance over and above the planned tracklines
within U.S. waters to allow for turns, lines that might have to be
repeated because of poor data quality, or for minor changes to the
survey design. The resulting estimate of 5,136.5 km\2\ (1,983.2 mi\2\)
was used to estimate the numbers of marine mammals exposed to
underwater sound levels greater than or equal to 160 dB (rms).
Based on the operational plans and marine mammal densities
described in Table 5 of the IHA application, the estimates of marine
mammals potentially exposed to sounds greater than or equal to 160 dB
(rms) in the proposed survey area within U.S. waters are presented in
Table 6 of the IHA application. For the common species, the requested
numbers are calculated as described above and based on the average
densities from the data reported in the different studies mentioned
above. For less common species, estimates were set to minimal values to
allow for chance encounters. Discussion of the number of potential
exposures is summarized by species in the following subsections.
Cetaceans--Based on density estimates and area ensonified, one
endangered cetacean species (bowhead whale) is expected to be exposed
to received levels greater than or equal to 160 dB unless bowheads
avoid the survey vessel before the received levels reach 160 dB.
Migrating bowheads are likely to do so, though many of the bowheads
engaged in other activities, particularly feeding and socializing may
not. The USGS estimate of the number of bowhead whales potentially
exposed to sound levels greater than or equal to 160 dB in the portion
of the survey area in U.S. waters in between 31 and 63 (see Table 6 of
the IHA application). Although take was calculated based on
[[Page 39354]]
density estimates in the proposed action area, the proposed seismic
survey will be conducted during the fall migration for bowhead whales,
but at locations starting at greater than 185.2 km (100 nmi) offshore,
well north of the known bowhead migration corridor and well beyond
distances (20 to 30 km [12.4 to 18.6], Miller et al., 1999; Richardson
et al., 1999) known to potentially effect this species. Other
endangered cetacean species that may be encountered in the area are fin
and humpback whales; both are unlikely to be exposed given their
minimal density in the area.
The only other cetacean species likely to occur in the proposed
survey area is the beluga whale. Average (best) and maximum estimates
of the number of exposures of belugas to sound levels greater than or
equal to 160 dB (rms) are 182 and 364, respectively. Estimates for
other cetacean species are minimal (see Table 6 of the IHA
application).
Pinnipeds--The ringed seal is the most widespread and abundant
pinniped in ice-covered arctic waters, and there is a great deal of
annual variation in abundance and distribution of these marine mammals.
Ringed seals account for the vast majority of marine mammals expected
to be encountered, and hence exposed to airgun sounds with received
levels greater than or equal to 160 dB (rms) during the proposed marine
seismic survey. The average (best) and maximum number of exposures of
ringed seals to sound levels greater than or equal to 160 dB (rms) were
estimated to be 1,031 and 4,126, respectively.
Two additional pinniped species (other than the Pacific walrus) are
likely to occur in the proposed project area. The average and maximum
numbers of exposures of bearded seals to sound levels greater than or
equal to 160 dB (rms) were estimated to be 53 and 210, respectively.
The ribbon seal is unlikely to be encountered in the survey area, but a
chance encounter could occur.
Estimated Area Exposed to >= 120 dB (rms)
The area potentially exposed to received levels greater than or
equal to 120 dB (rms) due to icebreaking operations was estimated by
multiplying the anticipated trackline distance breaking ice by the
estimated cross-track distance to received levels of 120 dB caused by
icebreaking.
In 2008, acousticians from Scripps Institution of Oceanography
Marine Physical Laboratory and University of New Hampshire Center for
Coastal and Ocean Mapping conducted measurements of SPLs of Healy
icebreaking under various conditions (Roth and Schmidt, 2010). The
results indicated that the highest mean SPL (185 dB [rms]) was measured
at survey speeds of 4 to 4.5 knots in conditions of 5/10 ice and
greater. Mean SPL under conditions where the ship was breaking heavy
ice by backing and ramming was actually lower (180 dB). In addition,
when backing and ramming, the vessel is essentially stationary, so the
ensonified area is limited for a short period (on the order of minutes
to tens of minutes) to the immediate vicinity of the boat until the
ship breaks free and once again makes headway.
Although the report by Roth and Schmidt has not yet been reviewed
externally nor peer-reviewed for publication, the SPL results reported
are consistent with previous studies (Thiele, 1981, 1988; LGL and
Greenridge, 1986; Richardson et al., 1995).
The existing threshold for Level B harassment for continuous sounds
is a received sound level of 120 dB SPL. Using a spherical spreading
model, a source level of 185 dB decays to 120 dB in about 1,750 m
(5,741.5 ft). This model is corroborated by Roth and Schmidt (2010).
Therefore, as the ship travels through the ice, a swath 3,500 m (11,483
ft) wide would be subjected to sound levels greater than or equal to
120 dB (rms). This results in the potential exposure of 11,802 km\2\
(4,557.8 mi\2\) to sounds greater than or equal to 120 dB (rms) from
icebreaking.
Based on the operational plans and marine mammal densities
described above, the estimates of marine mammals exposed to sounds
greater than or equal to 120 dB (rms) during the maximum estimation of
icebreaking outside of U.S. waters (3,372 km [2,095.3 mi]) are
presented in Table Add-4 of the IHA application. For the common marine
mammal species, the requested numbers are calculated as described above
and based on the average densities from the data reported in the
different studies mentioned above. For less common species, estimates
were set to minimal values to allow for chance encounters.
Based on models, bowhead whales likely would respond to the sound
of the icebreakers at distances of 2 to 25 km (1.2 to 15.5 mi) from the
icebreakers (Miles et al., 1987). This study predicts that roughly half
of the bowhead whales show avoidance responses to an icebreaker
underway in open water at a range of 2 to 12 km (1.3 to 7.5 mi) when
the sound-to-noise ratio is 30 dB (rms). The study also predicts that
roughly half of the bowhead whales would show avoidance response to an
icebreaker pushing ice at a range of 4.6 to 6.2 km (2.9 to 12.4 mi)
when the sound-to-noise ratio is 30 dB.
Richardson et al. (1995b) found that bowheads migrating in the
nearshore lead during the spring migration often tolerated exposure to
playbacks of recorded icebreaker sounds at received levels up to 20 dB
or more above the natural ambient noise levels at corresponding
frequencies. The source level of an actual icebreaker is much higher
than that of the projectors (projecting the recorded sound) used in
this study (median difference 34 dB over the frequency range 40 Hz to
6.3 kHz). Over the two season period (1991 and 1994) when icebreaker
playbacks were attempted, an estimated 93 bowheads (80 groups) were
seen near the ice camp when the projectors were transmitting icebreaker
sounds into the water, and approximately 158 bowheads (116 groups) were
seen near there during quiet periods. Some bowheads diverted from their
course when exposed to levels of projected icebreaker sound greater
than 20 dB above the natural ambient noise level in the \1/3\ octave
band of the strongest icebreaker noise. However, not all bowheads
diverted at that sound-to-noise ratio, and a minority of whales
apparently diverted at a lower sound-to-noise ratio. The study
concluded that exposure to a single playback of variable icebreaker
sounds can cause statistically, but probably not biologically
significant effects on movements and behavior of migrating whales in
the lead system during the spring migration east of Point Barrow,
Alaska. The study indicated the predicted response distances for
bowheads around an actual icebreaker would be highly variable; however,
for typical traveling bowheads, detectable effects on movements and
behavior are predicted to extend commonly out to radii of 10 to 30 km
(6.2 to 18.6 mi). Predicting the distance a whale would respond to an
icebreaker like the Healy is difficult because of propagation
conditions and ambient noise varies with time and with location.
However, because the closest survey activities and icebreaking are
approximately 116 km (72.1 mi) away and are of limited duration (5
days), and the next closest survey activities are 397 km (246.7 mi)
away to the north and west in the Arctic ocean, NMFS does not
anticipate that icebreaking activities would have biologically
significant effects on the movements and behavior of bowhead whales.
[[Page 39355]]
Table 6--The Estimates of the Possible Numbers of Marine Mammals Exposed to Sound Levels Greater Than or Equal
to 120 dB (rms) (for Icebreaking) or 160 dB (rms) (for Seismic Airgun Operations) During USGS's Proposed Seismic
Survey in U.S. Waters in the Northern Beaufort Sea and Arctic Ocean, in August, 2010. Received Levels are
Expressed in dB re 1 [mu]Pa (rms) (Averaged Over Pulse Duration), Consistent With NMFS' Practice. Not All Marine
Mammals Will Change Their Behavior When Exposed to These Sound Levels, but Some May Alter Their Behavior When
Levels Are Lower (See Text). See Tables 4 to 5 and Add-3 and Add-4 in USGS's Application for Further Detail.
----------------------------------------------------------------------------------------------------------------
Number of Number of
individuals individuals Approximate
exposed (best) 1 exposed (max) 2 percent of
Species open water, ice open water, ice Total (best) regional
margin, polar margin, polar population best)
pack pack 2
----------------------------------------------------------------------------------------------------------------
Odontocetes............................. 146 291
Beluga whale............................ 36 73 224 0.57
(Delphinapterus leucas)................. 42 84
Narwhal................................. 0 1
(Monodon monocerus)..................... 0 1 0 0
0 1
Killer whale............................ 0 0
(Orcinus orca).......................... 0 0 0 0
0 1
Harbor porpoise......................... 0 0
(Phocoena phocoena)..................... 0 0 0 0
0 1
Mysticetes.............................. 25 50
Bowhead whale........................... 6 13 38 0.36
(Balaena mysticetus).................... 7 1
Eastern Pacific gray whale.............. 0 0
(Eschrichtius robustus)................. 0 0 0 0
0 1
Minke whale............................. 0 0
(Balaenoptera acutorostrata)............ 0 0 0 0
0 1
Fin whale............................... 0 0
(Balaenoptera physalus)................. 0 0 0 0
0 1
Humpback whale.......................... 0 0
(Megaptera novaeangliae)................ 0 0 0 0
0 0
Pinnipeds............................... 39 158
Bearded seal............................ 13 53 67 0.02
(Erignathus barbatus)................... 15 60
Spotted seal............................ 0 2
(Phoca largha).......................... 0 0 0 0
0 0
Ringed seal............................. 774 3,094
(Pusa hispida).......................... 258 1,031 1,328 7.38
296 1,185
Ribbon seal (Histriophoca fasciata)..... N.A. N.A. N.A. N.A.
Pacific walrus (Odobenus rosmarus N.A. N.A. N.A. N.A.
divergens).............................
Carnivores
Polar bear (Ursus maritimus marinus) N.A. N.A. N.A. N.A.
----------------------------------------------------------------------------------------------------------------
N.A.--Data not available or species status was not assessed.
1 Best estimate and maximum density estimates are from Table 5 and Table Add-3 of USGS's application.
2 Regional population size estimates are from Table 4.
Conclusions--Bowhead whales are considered by NMFS to be disturbed
after exposure to underwater sound levels greater than or equal to 160
dB (rms) for impulse sources and 120 dB (rms) for continuous sources.
The relatively small airgun array proposed for use in this survey
limits the size of the 160 dB (rms) EZ around the vessel and is not
expected to result in any bowhead whale exposures to underwater sound
levels sufficient to reach the disturbance criterion as defined by
NMFS.
Odontocete reactions to seismic energy pulses are usually assumed
to be limited to lesser 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 10
to 20 km (6.2 to 12.4 mi) of seismic vessels during aerial surveys
(Miller et al., 2005). Belugas will likely occur in small numbers in
the project area within U.S. waters during the survey period. Most
belugas will likely avoid the vicinity of the survey activities and few
will likely be affected.
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-
[[Page 39356]]
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.
Based on the >= 160 dB disturbance criterion, the best estimates of
the numbers of cetacean exposures to sounds >= 160 dB re 1 [mu]Pa (rms)
represent less than one percent of the populations of each species in
the Chukchi Sea and adjacent waters. For species listed as Endangered
under the ESA, USGS estimates suggest it is unlikely that fin whales or
humpback whales will be exposed to received levels >= 160 dB and/or >=
120 dB, but that approximately 38 bowheads (0.36 percent of the
regional population) may be exposed at this level. The latter is less
than one percent of the Bering-Chukchi-Beaufort population of greater
than 14,247 assuming 3.4 percent population growth from the 2001
estimate of greater than 10,545 animals (Zeh and Punt, 2005). NMFS does
not anticipate bowhead whales to be potentially affected by the
proposed survey activities due to its location far offshore of the
bowhead fall migration pathway.
Some monodontids may be exposed to sounds produced by the airgun
arrays during the proposed survey, and the numbers potentially affected
are small relative to the population sizes (see Table 6 of the IHA
application). The best estimate of the number of belugas (224 animals)
that might be exposed to >= 160 dB and/or >= 120 dB represents less
than one percent (0.57 percent) of their regional population.
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. Monitoring and mitigation measures
such as controlled vessel speed, dedicated PSOs, non-pursuit, 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.
Several pinniped species may be encountered in the study area, but
the ringed seal is by far the most abundant marine mammal species in
the survey area. The best (average) estimates of the numbers of
individual seals exposed to airgun sounds at received levels >= 160 dB
re 1 [mu]Pa (rms) and/or >= 120 dB re 1 [mu]Pa (rms) for icebreaking
during the marine survey are as follows: Ringed seals (1,328 animals;
7.4 percent of the regional population), bearded seals (67 animals;
0.02 percent of the regional population), and spotted seals (0 animals,
0 percent of the regional population), representing less than a few
percent of the Bering-Chukchi-Beaufort populations for each species. It
is probable that only a small percentage of the pinnipeds exposed to
sound level >= 160 dB (rms) or 120 dB (rms) would actually be
disturbed. The short-term exposures of pinnipeds to airgun sounds are
not expected to result in any long-term negative consequences for the
individuals or their populations.
Potential Effects on Habitat
The proposed USGS seismic survey will not result in any permanent
impact on habitats used by marine mammals, including the food sources
they use. The proposed activities will be of short duration in any
particular area at any given time; thus any effects would be localized
and short-term. However, the main impact issue associated with the
proposed activity will be temporarily elevated noise levels and the
associated direct effects on marine mammals, as described above.
Icebreaking could alter ice conditions in the immediate area around
the vessels. However, ice conditions at this time of year are typically
highly variable and relatively unstable in most locations the survey
will take place. Although there is the potential for the destruction of
ringed seal lairs or polar bear dens due to icebreaking, these animals
will not be using lairs or dens at the time of the planned survey.
One of the reasons for the adoption of airguns as the standard
energy source for marine seismic surveys was that, unlike explosives,
they do not result in any appreciable fish kill. However, the existing
body of information relating to the impacts of seismic on marine fish
and invertebrate species, the primary food sources of pinnipeds and
belugas, is very limited.
In water, acute injury and death of organisms exposed to seismic
energy depends primarily on two features of the sound source: (1) The
received peak pressure, and (2) the time required for the pressure to
rise and decay (Hubbs and Rechnitzer, 1952; Wardle et al., 2001).
Generally, the higher the received pressure and less time required for
the pressure to rise and decay, the greater the chance of acute
pathological effects. Considering the peak pressure and rise/decay time
characteristics of seismic airgun arrays used today, the pathological
zone for fish and invertebrates would be expected to be within a few
meters of the seismic source (Buchanan et al., 2004). For the proposed
survey, any injurious effects on fish would be limited to very short
distances from the sound source and well away from the nearshore waters
where most subsistence fishing activities occur.
The only designated Essential Fish Habitat (EFH) species that may
occur in the area of the project during the seismic survey are salmon
(adult), and their occurrence in waters north of the Alaska coast is
limited. Adult fish near seismic operations are likely to avoid the
immediate vicinity of the source, thereby avoiding injury (see Appendix
E of the IHA application). No EFH species will be present as very early
life stages when they would be unable to avoid seismic exposure that
could otherwise result in minimal mortality.
Studies have been conducted on the effects of seismic activities on
fish larvae and a few other invertebrate animals. Generally, seismic
was found to only have potential harmful effects to larvae and
invertebrates that are in direct proximity (a few meters) of an active
airgun array (see Appendix E and F of the IHA application). The
proposed Arctic Sea seismic program for 2010 is predicted to have
negligible to low physical effects on the various life stages of life
and invertebrates. Therefore, physical effects of the proposed program
on fish and invertebrates would not be significant.
The Healy is designed for continuous passage at 5.6 km (3 knots)
through ice 1.4 m (4.6 ft) thick. During this project the Healy will
typically encounter first- or second-year ice while avoiding thick ice
floes, particularly large intact multi-year ice, whenever possible. In
addition, the icebreaker will follow leads when possible while
following the survey route. As the icebreaker passes through the ice,
the ship causes the ice to part and travel alongside the hull. This ice
typically returns to fill the wake as the ship passes. The effects are
transitory, i.e., hours at most, and localized, i.e., constrained to a
relatively narrow swath perhaps 10 m (32.8 ft) to each side of the
vessel.
The Healy's maximum beam is 25 m (82 ft). Applying the maximum
estimated amount of icebreaking, i.e., 3,372 km (2,095.3 mi), to the
corridor opened by the ship, USGS anticipates that a maximum of
approximately 152 km\2\ (58.7 mi\2\) of ice may be disturbed. This
encompasses an insignificant amount (less than 0.005 percent) of the
total Arctic ice extent in August and September of 2008 and 2009 which
ranged from 3.24 million to 4.1 million km\2\ (1,235,527 to 1,583,019
mi\2\).
[[Page 39357]]
Potential Effects on Marine Mammal Habitat
The proposed airgun operations will not result in any permanent
impact on habitats used by marine mammals, or to the food sources they
use. The main impact issue associated with the proposed activities will
be temporarily elevated noise levels and the associated direct effects
on marine mammals, as well as the potential effects of icebreaking. The
potential effects of icebreaking include locally altered ice conditions
which may temporarily alter the haul-out pattern of seals in the
immediate vicinity of the vessel. The destruction of ringed seal lairs
or polar bear dens is not expected to be a concern at this time of
year.
During the seismic survey only a small fraction of the available
habitat would be ensonified at any given time. Disturbance to fish
species would be short-term and fish would return to their pre-
disturbance behavior once the seismic activity ceases. Thus, the
proposed survey would have little, if any, impact on the abilities of
marine mammals to feed in the area where seismic work is planned.
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 other feed intermittently during
their westward migration in September and October (Richardson and
Thomson, 2002; Lowry et al., 2004; Lyons et al., 2009; Christi et al.,
2009). 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, since operations at
any specific location will be limited in duration.
Icebreaking will create temporary leads in the ice and could
possibly destroy unoccupied seal lairs. Seal pups are born in the
spring, therefore, pupping and nursing will have concluded and the
lairs will be vacated at the time of the proposed survey. Breaking ice
may damage seal breathing holes and will also reduce the haul-out area
in the immediate vicinity of the ship's track.
Icebreaking along a maximum of 3,372 km (2,095.3 mi) of trackline
will alter local ice conditions in the immediate vicinity of the
vessel. This has the potential to temporarily lead to a reduction of
suitable seal haul-out habitat. However the dynamic sea-ice environment
requires that seals be able to adapt to changes in sea, ice, and snow
conditions, and they therefore create new breathing holes and lairs
throughout winter and spring (Hammill and Smith, 1989). In addition,
seals often use open leads and cracks in the ice to surface and breathe
(Smith and Stirling, 1975). Disturbance to the ice will occur in a very
small area (less than 0.005 percent) relative to the Arctic icepack and
no significant impact on marine mammals is anticipated by icebreaking
during the proposed project.
Proposed Mitigation
In order to issue an Incidental Take Authorization (ITA) for small
numbers of marine mammals 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 seismic survey in
the Arctic Ocean, USGS will deploy an airgun array of three G-airguns.
The source will be relatively small in size and source level, relative
to airgun arrays typically used for industry seismic surveys. Important
mitigation factors built into the design of the survey include the
following:
In deep offshore waters (where the survey will occur),
sound from the airguns is expected to attenuate relatively rapidly as
compared with attenuation in shallower waters;
The airguns comprising the array will be clustered with
only limited horizontal separation (see Appendix B of the IHA
application), so the arrays will be less directional than is typically
the case with larger airgun arrays. This will result in less downward
directivity than is often present during seismic surveys, and more
horizontal propagation of sound; and
Airgun operations will be limited to offshore waters, far
from areas where there is subsistence hunting or fishing, and in waters
where marine mammal densities are generally low.
In addition to the mitigation measure that are built into the
general project design, several specific mitigation measures will be
implemented to avoid or minimize effects on marine mammals encountered
along the tracklines. These include ramping-up the airguns at the
beginning of operations, and power-downs or shut-downs when marine
mammals are detected within specified distances from the source. The
GSC has written a Categorical Declaration (see Appendix C of the IHA
application) stating that: ``While in U.S. waters (i.e., the U.S. 200
mile EEZ), the GSC operators will comply with any and all environmental
mitigation measures required by the U.S. National Marine Fisheries
Service (NMFS) and/or the U.S. Fish and Wildlife Service (USFWS).''
Received sound fields were measured for the airgun configuration,
in relation to distance and direction from the airgun(s). The proposed
radii around the airgun(s) where received levels would be 180 and 190
dB (rms) are shown in Table 2 of the IHA application. The 180 and 190
dB (rms) levels are used to initiate a power-down or, if necessary,
shut-down criteria applicable to cetaceans and pinnipeds, respectively,
as specified by NMFS (2000).
Vessel-based PSOs will watch for marine mammals near the airgun(s)
when they are in use. Mitigation and monitoring measures proposed to be
implemented for the seismic survey have been developed and refined in
cooperation with NMFS during previous seismic studies in the Arctic and
described in associated EAs, IHA applications, and IHAs. The mitigation
and monitoring measures described herein represent a combination of the
procedures required by past IHAs for Arctic projects.
Some cetacean species (such as bowhead whales) may be feeding or
migrating in the Beaufort Sea during August and September. However,
most of the proposed geophysical activities will occur north of the
main migration corridor and the number of individual animals expected
to closely approach the vicinity of the proposed activity will be small
in relation to regional population sizes. With the proposed monitoring,
ramp-up, power-down, and shut-down provisions (see below), any effects
on individuals are expected to be limited to behavioral disturbance.
The following subsections provide more detailed information about the
mitigation measures that are integral part of the planned activity.
Proposed Exclusion Zones (EZ)
Mosher et al. (2009) collected received sound level data for the
airgun configuration that will be used in the proposed survey in
similar water
[[Page 39358]]
depths, i.e., greater than 2,000 m (6,561.7 ft). The empirical data
were plotted in relation to distance and direction from the three
airguns by Roth and Schmidt (2010; see Figure B-3). Based on model fit
to the measured received levels and source modeling estimates from
Gundalf, the 180 and 190 dB (rms) EZ are estimated to be 216 m (708.7
ft) and 68 m (223.1 ft), respectively. As a conservation measure for
the proposed EZ, the sound-level EZ indicated by the empirical data
have been increased to 500 m (1,640.4 ft) for the 180 dB isopleths and
to 100 m (328 ft) for the 190 dB isopleths (see Table 2 of the IHA
application). The 180 and 190 dB levels are shut-down criteria
applicable to cetaceans and pinnipeds, respectively, as specified by
NMFS (2000); these levels were used to establish the EZs. If the PSO
detects marine mammal(s) within or about to enter the appropriate EZ,
the airguns will be powered-down (or shut-down if necessary)
immediately (see below).
Detailed recommendations for new science-based noise exposure
criteria were published in early 2008 (Southall et al., 2007). USGS
will be prepared to revise its procedures for estimating numbers of
mammals ``taken,'' EZs, etc., as may be required by any new guidelines
that result. As yet, NMFS has not specified a new procedure for
determining EZs. Such procedures, if applicable would be implemented
through a modification to the IHA if issued.
In addition to monitoring, mitigation measures that will be adopted
during the proposed Arctic Ocean survey include:
(1) Speed or course alteration, provided that doing so will not
comprise operational safety requirements;
(2) Power-down procedures;
(3) Shut-down procedures; and
(4) Ramp-up procedures.
No start-up of airgun operations would be permitted unless the full
180 dB (rms) EZ is visible for at least 30 min during day or night.
Other proposed provisions associated with operations at night or in
periods of poor visibility include the following:
During foggy conditions or darkness (which may be
encountered starting in late August), the full 180 dB (rms) EZ may not
be visible. In that case, the airguns could not start-up after a full
shut-down until the entire 180 dB (rms) radius was visible.
During any nighttime operations, if the entire 180 dB
(rms) EZ is visible using vessel lights, then start-up of the airgun
array may occur following a 30 min period of observation without
sighting marine mammals in the EZ.
If one or more airguns have been operational before
nightfall, they can remain operational throughout the night, even
though the entire EZ may not be visible.
Speed or Course Alteration--If a marine mammal (in water) is
detected outside the EZ and, based on its position and relative motion,
is likely to enter the EZ, the vessel's speed and/or direct course may,
when practical and safe, be changed in a manner that also minimizes the
effect on the planned science objectives. The marine mammal activities
and movements relative to the seismic vessel will be closely monitored
to ensure that the marine mammal does not approach within the EZ. If
the mammal appears likely to enter the EZ, further mitigative actions
will be taken, i.e., either further course alterations or power-down or
shut-down of the airgun(s).
Power-down Procedures--A power-down involves reducing the number of
airguns in use such that the radius of the 180 dB or 190 dB (rms) EZ
are decreased to the extent that marine mammals are no longer in or
about to enter the EZ. A power-down of the airgun array can also occur
when the vessel is moving from one seismic line to another. During a
power-down for mitigation, one airgun (or some other number of airguns
less than the full airgun array) will be operated. The continued
operation of one airgun is intended to alert (1) marine mammals to the
presence of the seismic vessel in the area, and (2) retain the option
of initiating a ramp-up to full operations under poor visibility
conditions. In contrast, a shut-down occurs when all airgun activity is
suspended.
If a marine mammal is detected outside the EZ but is likely to
enter the EZ, and if the vessel's speed and/or course cannot be changed
to avoid having the marine mammal enter the EZ, the airguns (as an
alternative to a complete shut-down) will be powered-down to a single
airgun before the animal is within the EZ. Likewise, if a mammal is
already within the EZ when first detected, the airguns will be powered-
down immediately if this is a reasonable alternative to a complete
shut-down. During a power-down of the airgun array, the number of
airguns will be reduced to a single 150 in\3\ G-airgun will be
operated. The 180 dB (rms) EZ for the power-down sound source has been
estimated to be 62 m (203 ft), the proposed distance for use by PSOs is
75 m (246 ft). If a marine mammal is detected within or near the
smaller EZ around that single 150 in\3\ airgun (see Table 2 of USGS's
application and Table 2 above), all airguns will be shut-down (see next
subsection).
Following a power-down, operation of the full airgun array will not
resume until the marine mammal is outside the EZ for the full array.
The animal will be considered to have cleared the EZ if it:
(1) Is visually observed to have left the EZ, or
(2) Has not been seen within the EZ for 15 minutes in the case for
species with shorter dive durations (e.g., small odontocetes and
pinnipeds); or
(3) Has not been seen within the EZ for 30 minutes in the case for
species with longer dive durations (e.g., mysticetes and large
odontocetes, including killer whales).
During airgun operations following a power-down (or shut-down)
whose duration has exceeded the limits specified above and subsequent
animal departures, the airgun array will be ramped-up gradually. Ramp-
up procedures are described below.
Shut-down Procedures--The operating airgun(s) will be shut-down if
a marine mammal is detected within or approaching the EZ for a single
airgun source (i.e., a power-down is not practical or adequate to
reduce exposure to less than 190 or 180 dB (rms), as appropriate).
Shut-downs will be implemented (1) if an animal approaches or enters
the EZ of the single airgun after a power-down has been initiated, or
(2) if an animal is initially seen within the EZ of a single airgun
when more than one airgun (typically the full array) is operating.
Airgun activity will not resume until the marine mammal has cleared the
EZ, or until the PSVO is confident that the animal has left the
vicinity of the vessel (or the PSVO not observing the animal(s) within
the EZ for 15 or 30 min depending upon the species). Criteria for
judging that the animal has cleared the EZ will be as described in the
preceding subsection. Ramp-up procedures will be followed during
resumption of full seismic operations after a shut-down of the airgun
array.
Ramp-up Procedures--A ramp-up procedure will be followed when the
airgun array begins operating after a specified period without airgun
operations or when a power-down (or reduced airgun operations) has
exceeded that specified duration period. The specified period depends
on the speed of the source vessel, the size of the airgun array that is
being used, and the size of the EZ, but is often about 10 min. NMFS
normally requires that, once ramp-up commences, the rate of ramp-up be
no more than 6 dB per 5 min period. Ramp-up will begin with a
[[Page 39359]]
single airgun (the smallest airgun in the array). Airguns will be added
in a sequence such that the source level of the array will increase in
steps not exceeding 6 dB per 5 min period over a total duration of
approximately 10 minutes. During ramp-up, the PSVOs will monitor the
EZ, and if marine mammals are sighted, a power-down or shut-down will
be implemented as though the full array were operational.
If the complete 180 dB (rms) EZ has not been visible for at least
30 min prior to the start of operations in either daylight or
nighttime, ramp-up will not commence unless at least one airgun (150
in\3\ or similar) has been operating during the interruption of seismic
survey operations. Given these provisions, it is likely that the three
G-airgun array will not be ramped-up from a complete shut-down at night
or in thick fog, because the outer part of the EZ for that array will
not be visible during those conditions. If the entire EZ is visible
using vessel lights, then start-up of the airguns from a complete shut-
down may occur at night. If one airgun has operated during a power-down
period, ramp-up to full power will be permissible at night or in poor
visibility, on the assumption that marine mammals will be alerted to
the approaching seismic vessel by the sounds from the single airgun and
could move away if they choose. Given the responsiveness of bowhead and
beluga whales to airgun sounds, it can be assumed that those species in
particular will move away during a ramp-up. Ramp-up of the airguns will
not be initiated during the day or at night if a marine mammal is
sighted within or near the applicable EZ during the previous 15 or 30
min, as applicable.
Helicopter Flights--The use of a helicopter to conduct ice
reconnaissance flights and vessel-to-vessel personnel transfers is
likely to occur during survey activities in U.S. waters. However,
collection of spot bathymetry data or on-ice landings, both of which
required low altitude flight patterns, will not occur in U.S. waters.
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) require that requests for IHAs
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.
USGS proposes to sponsor marine mammal monitoring during the
proposed project, in order to implement the proposed mitigation
measures that require real-time monitoring, to satisfy the anticipated
monitoring requirements of the IHA proposed by NMFS, and to meet any
monitoring requirements agreed to as part of the Plan of Cooperation.
USGS's proposed Monitoring Plan is described below as well as in their
IHA application. USGS understands that this Monitoring Plan will be
subject to review by NMFS and others, and that refinements may be
required as part of the MMPA consultation process.
The monitoring work described here has been planned as a self-
contained project independent of any other related monitoring projects
that may be occurring simultaneously in the same regions. USGS is
prepared to discuss coordination of its monitoring program with any
related work that might be done by other groups insofar as this is
practical and desirable.
Vessel-Based Visual Monitoring
Vessel-based Protected Species Observers (PSOs) will monitor for
marine mammals near the seismic source vessel during all daytime airgun
operations and during any nighttime start-ups of the airguns. The
survey area within U.S. waters is located within high latitudes
(approximately 72[deg] to 74[deg] North) and the project will take
place during the summer when little darkness will be encountered (see
Table 9 of the IHA application). Some periods of darkness will be
encountered towards the end of the survey when there will be several
hours between sunset and sunrise.
The PSO's observations will provide the real-time data needed to
implement the key mitigation measures. Airgun operations will be
powered-down or (if necessary) shut-down when marine mammals are
observed within, or about to enter, designated EZ where there is a
possibility of effects on hearing or other physical effects. Vessel-
based PSOs will also watch for marine mammals near the seismic vessel
for at least 30 min prior to the planned start of airgun operations
after an extended shut-down of the airgun. When feasible, observations
will also be made during daytime periods without seismic operations
(e.g., during transits).
Table 7--The Daylight Times and Periods Within the Proposed Project Area From Beginning (August 7, 2010) To End
(September 3, 2010) of the Planned Survey Activities Within Latitudes of the Planned Survey Within U.S. Waters.
Time is in Alaska Daylight Time (AKDT).
----------------------------------------------------------------------------------------------------------------
72[deg] North 74[deg] North
----------------------------------------------------------------------------------------------------------------
August 7 September 3 August 7 September 3
----------------------------------------------------------------------------------------------------------------
Sunrise......................................... 09:29 12:14 .............. 12:00
Sunset.......................................... 06:42 03:45 .............. 03:59
Period of daylight (hours)...................... 21:13 15:31 24:00 15:59
----------------------------------------------------------------------------------------------------------------
During daylight, vessel-based PSOs will watch for marine
mammals near the seismic vessel during all periods of airgun activity
and for a minimum of 30 min prior to the planned start of airgun
operations after an extended shut-down.
Although there will be only a brief period during the
survey when darkness will be encountered in U.S. waters, USGS proposes
to conduct nighttime as well as daytime operations. PSOs dedicated to
protected species observations are proposed not to be on duty during
ongoing seismic operations at night, given the very limited
effectiveness of visual observation at night. At night, bridge
personnel will watch for marine mammals (insofar as practical at night)
and will call for the airguns to be shut-down if marine mammals are
observed in or about to enter the EZ.
PSOs will be stationed aboard both the seismic source vessel (St.
Laurent) and Healy during the proposed survey. The vessels will
typically work together in tandem while making way through heavy ice
with the Healy in the lead breaking ice and collecting multi-beam data.
The St. Laurent will follow
[[Page 39360]]
collecting seismic reflection and refraction data. In light ice
conditions, the vessels will separate to maximize data collection.
``Real-time'' communication between the two vessels regarding marine
mammal detections will be available through VHF radio.
During operations in U.S. EEZ waters, a complement of five PSOs
will work on the source vessel, the St. Laurent, and two will be
stationed on the Healy. Three trained PSOs will board the St. Laurent
in Kagluktuk, Nunavut, Canada. Three experienced PSOs and one Alaska
Native community observer will be aboard the Healy at the outset of the
project. Before survey operations begin in U.S. waters, two of the PSOs
on the Healy will transfer to the St. Laurent to provide additional
observers during airgun operations. When not surveying in U.S. waters,
the distribution of PSOs will return to three on the St. Laurent and
four on the Healy.
PSOs on the St. Laurent will monitor for marine mammals during all
daylight airgun operations. Airgun operations will be shut-down when
marine mammals are observed within, or about to enter, designated EZ
(see below) where there may be a possibility of significant effects on
hearing or other physical effects. PSOs on both the source vessel and
the Healy will also watch for marine mammals within or near the EZ for
at least 30 min prior to the planned start of airgun operations after
an extended shut-down of the airgun array. When feasible, observations
will also be made during periods without seismic operations (e.g.,
during transits). Environmental conditions will be recorded every half
hour during PSO watch.
The PSOs aboard the Healy will also watch for marine mammals during
daylight seismic activities conducted in both U.S. and international
waters. They will maximize their time on watch but will not watch
continuously, as will those on the St. Laurent, because they will not
have mitigation duties and there will be only two PSOs aboard the
Healy. The Healy PSOs will report sightings to the PSOs on the St.
Laurent to alert them of possible needs for mitigation.
In U.S. waters, at least one observer, and when practical two
observers, will monitor for marine mammals from the St. Laurent during
ongoing daytime operations and nighttime start-ups (when darkness is
encountered). Use of two simultaneous observers will increase the
proportion of the animals present near the source vessel that are
detected. PSOs will normally be on duty in shifts of no longer than
four hours duration although more than one hour shift may be worked per
day with a maximum of 12 hour of daily watch time. During seismic
operations in international waters, PSOs aboard the St. Laurent will
conduct eight hour watches. This schedule accommodates 24 hour/day
monitoring by three PSOs which will be necessary during most of the
survey when daylight will be continuous. Healy PSOs will limit watches
to four hours in U.S. waters.
The St. Laurent crew will be instructed to assist in detecting
marine mammals and implementing required mitigation (if practical). The
crew will be given instruction on mitigation requirements and
procedures for implementation of mitigation prior to the start of the
seismic survey. Members of the Healy crew will be trained to monitor
for marine mammals and asked to contact the Healy observers for
sightings that occur while the PSOs are off-watch.
The St. Laurent and Healy are suitable platforms for observations
for marine mammals. When stationed on the flying bridge, eye level will
be approximately 15.4 m (51 ft) above sea level on the St. Laurent and
approximately 24 m (78.7 ft) above sea level on the Healy. On both
vessels the PSO will have an unobstructed view around the entire vessel
from the flying bridge. If surveying from the bridge of the St. Laurent
or the Healy the PSO's eye level will be approximately 12.1 m (40 ft)
above sea level or 21.2 m (69 ft) above sea level, respectively. The
PSO(s) will scan the area around the vessel systematically with laser
range finding binoculars and with the unaided eye.
The survey will be conducted at high latitudes and continuous
daylight will persist through much of the proposed survey area through
the month of August. Day length will decrease to approximately 18 hours
in the northern portion of the survey area by about early September.
Laser range-finding binoculars (Leica LRF 1200 laser rangefinder or
equivalent) will be available to assist with distance estimation; this
equipment is useful in training observers to estimate distances
visually, but is generally not useful in measuring distances to animals
directly.
When marine mammals are detected within or about to enter the
designated EZ, the airgun(s) will be powered-down or shut-down
immediately. The distinction between power-downs and shut-downs is
described in the IHA application. Channels of communication between the
PSOs and the airgun technicians will be established to assure prompt
implementation of shut-downs when necessary as has been done in other
recent seismic survey operations in the Arctic (e.g., Haley, 2006).
During power-downs and shut-downs, PSOs will continue to maintain watch
to determine when the animal(s) are outside the EZ. Airgun operations
will not resume until the animal is outside the EZ. The animal will be
considered to have cleared the EZ if it is visually observed to have
left the EZ. Alternatively, in U.S. waters the EZ will be considered
clear if the animal has not been seen within the EZ for 15 min for
small odontocetes and pinnipeds or 30 min for mysticetes. Within
international waters the PSOs will apply a 30 min period for all
species.
PSO Data and Documentation
PSOs will record data to estimate the numbers of marine mammals
exposed to various received sound levels and to document apparent
disturbance reactions or lack thereof. Data will be used to estimate
numbers of animals potentially `taken' by harassment (as defined in the
MMPA). They will also provide information needed to order a power-down
or shut-down of the seismic source when a marine mammal is within or
near the EZ.
When a sighting is made, the following information about the
sighting will be recorded:
(1) Species, group size, and age/size/sex categories (if
determinable); behavior when first sighted and after initial sighting;
heading (if consistent), bearing, and distance from seismic vessel;
sighting cue; apparent reaction to the seismic source or vessel (e.g.,
none, avoidance, approach, paralleling, etc.); and behavioral pace.
(2) Time, location, heading, speed, activity of the vessel, sea
state, visibility, and sun glare.
The data listed under (2) above will also be recorded at the start
and end of each observation watch, and during a watch whenever there is
a change in one or more of the variables.
All observations, as well as information regarding seismic source
power-downs and shut-downs, will be recorded in a standardized format.
Data will be entered into a custom database using a notebook computer.
The accuracy of data entry will be verified by computerized data
validity checks as the data are entered and by subsequent manual
checking of the database. These procedures will allow initial summaries
of data to be prepared during and shortly after the field program, and
will facilitate transfer of the data to statistical, graphical, and
other programs for further processing and archiving.
[[Page 39361]]
Results for the vessel-based observations will provide:
(1) The basis for real-time mitigation (airgun power-down or shut-
down).
(2) Information needed to estimate the number of marine mammals
potentially taken by harassment, which must be reported to NMFS per
terms of MMPA authorizations or regulations.
(3) Data on the occurrence, distribution, and activities of marine
mammals in the area where the seismic study is conducted.
(4) Information to compare the distance and distribution of marine
mammals relative to the source vessel at times with and without seismic
activity.
(5) Data on the behavior and movement patterns of marine mammals
seen at times with and without seismic activity.
A report on USGS activities and on the relevant monitoring and
mitigation results will be submitted to NMFS within 90 days after the
end of the cruise. The report will describe the operations that were
conducted and sightings of marine mammals near the operations. The
report will be submitted to NMFS, providing full documentation of
methods, results, and interpretation pertaining to all acoustic
characterization work and vessel-based monitoring. The 90-day report
will summarize the dates and locations of seismic operations, and all
marine mammal sightings (dates, times, locations, activities,
associated seismic survey activities). The number and circumstances of
ramp-ups, power-downs, shut-downs, and other mitigation measures will
be reported. Sample size permitting, the report will also include
estimates of the amount and nature of potential ``take'' of marine
mammals by harassment or in other ways.
All injured or dead marine mammals (regardless of cause) will be
reported to NMFS as soon as practicable. Report should include species
or description of animal, condition of animal, location, time first
found, observed behaviors (if alive) and photo or video, if available.
Encouraging and Coordinating Research
USGS will coordinate the planned marine mammal monitoring program
associated with the seismic survey in the Arctic Ocean with other
parties that may have interest in this area and/or be conducting marine
mammal studies in the same region during operations. No other marine
mammal studies are expected to occur in the main (northern) parts of
the study area at the proposed time. However, other industry-funded
seismic surveys may be occurring in the northeast Chukchi and/or
western Beaufort Sea closer to shore, and those projects are likely to
involve marine mammal monitoring. USGS has coordinated, and will
continue to coordinate, with other applicable Federal, State and
Borough agencies, and will comply with their requirements.
Negligible Impact and Small Numbers of Marine Mammals Analysis and
Determination
The Secretary, in accordance with paragraph 101(a)(5)(D) of the
MMPA, shall authorize the take of small numbers of marine mammals
incidental to specified activities other than commercial fishing within
a specific geographic region if, among other things, he determines that
the authorized incidental take will have a ``negligible impact'' on
species or stocks affected by the authorization. NMFS implementing
regulations codified at 50 CFR 216.103 states that a ``negligible
impact is 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.''
Based on the analysis contained herein, of the likely effects of
the specified activity on marine mammals and their habitat within the
specific area of study for the Arctic Ocean marine geophysical survey,
and taking into consideration the implementation of the mitigation and
monitoring measures NMFS, on behalf of the Secretary, preliminary finds
that USGS's proposed activities would result in the incidental take of
small numbers of marine mammals, by Level B harassment only, and that
the total taking from the proposed seismic survey would have a
negligible impact on the affected species or stocks of marine mammals.
As a basis for its small numbers determination, NMFS evaluated the
number of individuals taken by Level B harassment relative to the size
of the stock or population.
While the number of marine mammals potentially incidentally
harassed will depend on the distribution and abundance of marine
mammals in the vicinity of the survey activity, the number of potential
Level B incidental harassment takings (see Table 6 above) is estimated
to be small, less than a few percent of any of the estimated population
sizes based on the data disclosed in Table 4 and 6 of this notice, and
has been mitigated to the lowest level practicable through the
incorporation of the monitoring and mitigation measures mentioned
previously in this document. Tables 4 and 6 in this notice disclose the
habitat regional abundance, conservation status, density, and the
number of individuals exposed to sound levels greater than or equal to
120 dB (rms) (for icebreaking) or 160 dB (rms) (for seismic airgun
operations). Also, there are no known important reproduction or feeding
areas in the proposed action area.
For reasons stated previously in this document, the specified
activities associated with the proposed survey are not likely to cause
TTS, PTS or other non-auditory injury, serious injury, or death to
affected marine mammals because:
(1) The likelihood that, given sufficient notice through relatively
slow ship speed, marine mammals are expected to move away from a noise
source that is annoying prior to its becoming potentially injurious;
(2) The fact that cetaceans and pinnipeds would have to be closer
than 500 m (1,640.4 ft) and 30 m (98.4 ft), in deep water when the full
array is in use at tow depth from the vessel to be exposed to levels of
sound (180 dB and 190 dB, respectively) believed to have even a minimal
chance of causing PTS;
(3) The fact that marine mammals would have to be closer than 2,500
m (8,202.1 ft) in deep water when the full array is in use at tow depth
from the vessel to be exposed to levels of sound (160 dB) believed to
have even a minimal chance at causing TTS; and
(4) The likelihood that marine mammal detection ability by trained
observers is high at that short distance from the vessel.
As a result, no take by injury, serious injury, or death is
anticipated or authorized, and the potential for temporary or permanent
hearing impairment is very low and will be avoided through the
incorporation of the proposed monitoring and mitigation measures.
In making a negligible impact determination NMFS evaluated factors
such as: no anticipated injury, serious injury or mortality; the
number, nature, intensity and duration of harassment (all relatively
limited); the low probability that take will likely result in effects
to annual rates of recruitment of survival; the context in which it
occurs (i.e., impacts to areas of significance, impacts to local
populations, and cumulative impacts when taking into account
successive/contemporaneous actions when added to baseline data); the
status of stock or species of marine mammal (i.e., depleted, not
depleted, decreasing, increasing, stable, impact relative to the size
of the population); impacts on habitat affecting rates of
[[Page 39362]]
recruitment/survival; and the effectiveness of monitoring and
mitigation measures
Impact on Availability of Affected Species for Taking for Subsistence
Uses
There is subsistence hunting for marine mammals in the waters off
of the coast of Alaska, in the Arctic Ocean, that implicates MMPA
Section 101(a)(5)(D). Subsistence hunting and fishing continue to be
prominent in the household economies and social welfare of some Alaska
residents, particularly among those living in small, rural villages
(Wolfe and Walker, 1987; Braund and Kruse, 2009). Subsistence remains
the basis for Alaska Native culture and community. 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.
Subsistence Hunting
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 seismic survey. Subsistence remains the basis for Alaska
Native culture and community, and subsistence activities are often
central to many aspects of human existence, including patterns of
family life, artistic expression, and community religious and
celebratory activities.
Bowhead whale hunting is a key activity in the subsistence
economies of Barrow and other Native communities along the Beaufort Sea
coast. 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 in 1977. The quota
is now regulated through an agreement between NMFS and the Alaska
Eskimo Whaling Commission (AEWC) which extends to 2012 (NMFS, 2008b).
The AEWC allows the number of bowhead whales that each whaling
community may harvest annually during five-year periods (USDI/BLM,
2005; NMFS, 2008).
The community of Barrow hunts bowhead whales in both the spring and
fall during the whales' seasonal migration along the coast (see Figure
2 of the IHA application). Often the bulk of the Barrow bowhead harvest
is taken during the spring hunt. However, with larger quotas in recent
years, it is common for a substantial fraction of the annual Barrow
quota to remain available for the fall hunt (see Table 7 of the IHA
application). The communities of Nuiqsut and Kaktovik participate only
in the fall bowhead harvest. 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. However, in recent years a small number of
bowheads have been seen or heard offshore from the Prudhoe Bay region
during the last week of August (Treacy, 1993; LGL and Greenridge, 1996;
Greene, 1997; Greene et al., 1999; Blackwell et al., 2004).
Table 8--Number of Bowhead Whale Landing by Year at Barrow, Cross Island (Nuiqsut), and Kaktovik, 1993 to 2008.
Barrow Numbers Include the Total Number of Whales Landed for the Year Followed by the Numbers Landed During the
Fall Hunt in Parentheses. Cross Island (Nuiqsut) and Kaktovik Landings Are in Autumn.
----------------------------------------------------------------------------------------------------------------
Year Point hope Wainwright Barrow Cross island Kaktovik
----------------------------------------------------------------------------------------------------------------
1993............................ 2 5 23 (7) 3 3
1994............................ 5 4 16 (1) 0 3
1995............................ 1 5 19 (11) 4 4
1996............................ 3 3 24 (19) 2 1
1997............................ 4 3 30 (21) 3 4
1998............................ 3 3 25 (16) 4 3
1999............................ 2 5 24 (6) 3 3
2000............................ 3 5 18 (13) 4 3
2001............................ 4 6 27 (7) 3 4
2002............................ 0 1 22 (17) 4 3
2003............................ 4 5 16 (6) 4 3
2004............................ 3 4 21 (14) 3 3
2005............................ 7 4 29 (13) 1 3
2006............................ 0 2 22 (19) 4 3
2007............................ 3 4 20 (7) 3 3
2008............................ 2 2 21 (12) 4 3
----------------------------------------------------------------------------------------------------------------
Sources: USDI/BLM and references therein; Burns et al., 1993; Koski et al., 2005; Suydam et al., 2004, 2005,
2006, 2007, 2008, and 2009.
The spring hunt 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 location of the fall
subsistence hunt depends on ice conditions and (in some years)
industrial activities that influence the bowheads as they move west
(Brower, 1996). 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 80 km (49.7 mi). The fall hunts begin in late August
or early September in Kaktovik and at Cross Island. At Barrow the fall
hunt usually begins in mid-September, and mainly occurs in the waters
east and northeast of Point Barrow in the Chukchi Sea (Suydam et al.,
2008). The whales have usually left the Beaufort Sea by late October
(Treacey, 2002a,b).
The scheduling of this seismic 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
timing of the proposed seismic survey in early to mid-August will
affect neither the
[[Page 39363]]
spring nor the fall bowhead hunt. The Healy is planning to change crew
after the completion of the seismic survey through Barrow via
helicopter or boat. That crew change is scheduled for approximately
September 4 to 5, 2010, well before the fall bowhead whaling which
typically begins late September or early October. All of the proposed
geophysical activities will occur offshore between 71[deg] and 84[deg]
North latitude well north of Beaufort Sea whaling activities.
Beluga whales are available to subsistence hunters at Barrow in the
spring when pack-ice conditions deteriorate and leads open up. Belugas
may remain in the area through June and sometimes into July and August
in ice-free waters. 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 to 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 zero in 1987, 1988 and 1995 to
the high of eight in 1997 (Fuller and George, 1997; Alaska Beluga Whale
Committee, 2002 in USDI/BLM, 2005). The proposed seismic survey is
unlikely to overlap with the beluga harvest, and the survey initiates
well outside the area where impacts to beluga hunting by Barrow
villagers could occur.
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
barrier islands are used for hunting ringed seals. The average annual
ringed seal harvest by the community of Barrow from the 1960s through
much of the 1980s has been estimated as 394 (see Table 8 of the IHA
application). More recently Bacon et al. (2009) estimated that 586,
287, and 413 ringed seals were harvest by villagers at Barrow in 2000,
2001, and 2003, respectively. Although ringed seals are available year-
round, the seismic survey will not occur during the primary period when
these seals are typically harvested. Also, the seismic survey will be
largely in offshore waters where the activities will not influence
ringed seals in the nearshore areas where they are hunted.
The spotted seal subsistence hunt peaks in July and August at least
in 1987 to 1990, but involves few animals. Spotted seals typically
migrate south by October to overwinter in the Bering Sea, Admiralty
Bay, less than 60 km (37.3 mi) to the east of Barrow, is a location
where spotted seals are harvested. 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 average annual spotted
seal harvest by the community of Barrow from 1987 to 1990 was one
(Braund et al., 1993; see Table 7 of the IHA application). More
recently however, Bacon et al. (2009) estimated that 32, 7, and 12
spotted seals were harvested by villagers at Barrow in 2000, 2001, and
2003, respectively. Spotted seals become less abundant at Nuiqsut and
Kaktovik and few if any spotted seal are harvested at these villages.
The seismic survey will commence at least 115 km (71.5 mi) offshore
from the preferred nearshore harvest area of these seals.
Bearded seals, although not favored for their meat, are important
to subsistence activities in Barrow 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 summer months in the Beaufort
Sea (USDI/BLM, 2005). The animals inhabit the environment around the
ice floes in the drifting ice pack, so hunting usually occurs from
boats in the drift ice. Braund et al. (1993) estimated that 174 bearded
seals were harvested annually at Barrow from 1987 to 1990 (see Table 8
of the IHA application). More recently Bacon et al. (2009) estimated
that 728, 327, and 776 bearded seals were harvested by villagers at
Barrow in 2000, 2001, and 2003, respectively. Braund et al. (1003)
mapped the majority of bearded seal harvest sites from 1987 to 1990 as
being within approximately 24 km (14.9 mi) of Point Barrow, well
inshore of the proposed survey which is to start approximately 115 km
(71.5 mi) offshore and terminate greater than 200 km (124.3 mi)
offshore. The average annual take of bearded seals by the Barrow
community from 1987 to 1990 was 174 (see Table 8 of the IHA
application).
Table 9--Average Annual Take of Marine Mammals Other Than Bowhead Whales Harvest by the Community of Barrow
(Compiled by LGL Alaska Research Associates, 2004)
----------------------------------------------------------------------------------------------------------------
Beluga whales Ringed seals Bearded seals Spotted seals
----------------------------------------------------------------------------------------------------------------
5**.......................................................... 394* 174* 1*
----------------------------------------------------------------------------------------------------------------
* Average annual harvest for years 1987 to 1990 (Braund et al., 1993).
** Average annual harvest for years 1962 to 1982 (MMS, 1996).
Plan of Cooperation
The USGS has communicated with community authorities and residents
of Barrow to foster understanding of the proposed survey. There are
elements of the proposed survey, intrinsic to the project, that
significantly limit the potential conflict with subsistence users.
Operations will be conducted during early August before bowhead whale
hunting typically occurs off Barrow and approximately 108 km (67.1 mi)
offshore, farther offshore than traditional subsistence hunting
grounds. USGS continues to work with the people of Barrow to identify
and avoid areas of potential conflict.
The USGS initiated contact with NSB scientists and the
chair of the AEWC in mid-December, 2010 via an e-mailed description of
the proposed survey that included components intended to minimize
potential subsistence conflict.
Invitations were extended December 31, 2009 to members of
the NSB, AEWC, and North Slope Communities to attend a teleconference
arranged for January 11, 2010. The teleconference served as a venue to
promote understanding of the project and discuss shareholder concerns.
Participants in the teleconference included Harry Brower, chair of the
AEWC, and NSB wildlife biologist Dr. Robert Suydam.
To further promote cooperation between the project
researchers and the community, Dr. Deborah Hutchinson with USGS
presented the proposed survey at a meeting of the AEWC in Barrow on
February 11, 2010. Survey plans were explained to local hunters and
whaling captains, including NSB Department of Wildlife Management
[[Page 39364]]
biologists, Craig George and Dr. Robert Suydam. Dr. Hutchinson
consulted with stakeholders about their concerns and discussed the
aspects of the survey designed to mitigate impacts.
Dr. Deborah Hutchinson of the USGS e-mailed a summary of
the topics discussed during the teleconference and the AEWC meeting in
Barrow to representatives of the NSB, AEWC, and North Slope
communities. These included:
[cir] Surveying within U.S. waters is scheduled early
(approximately August 7 to 12) to avoid conflict with hunters.
[cir] The EA and IHA application will be distributed as early as
possible to NSB and AEWC.
[cir] A community observer will be present aboard the Healy during
the project.
[cir] Mitigation of the one crew transfer near Barrow in early
September will be arranged--probably through Barrow Volunteer Search
and Rescue.
Representatives of the USGS attended the Arctic Open-water
Meeting in Anchorage, March 22 to 24, 2010.
[cir] Dr. Deborah Hutchinson presented information regarding the
proposed survey to the general assembly.
[cir] Dr. Jonathan Childs and Dr. Deborah Hutchinson met with
stakeholders and agency representatives while at the meeting.
Subsequent meetings with whaling captains, other community
representatives, the AEWC, NSB, and any other parties to the plan will
be held if necessary to coordinate the planned seismic survey operation
with subsistence hunting activity. The USGS has informed the chairman
of the Alaska Eskimo Whaling Committee (AEWC), Harry Brower, Jr., of
its survey plan.
As noted above and in the IHA application, in the unlikely event
that subsistence hunting or fishing is occurring within 5 km (3 mi) of
the project vessel tracklines, or where potential impacts could occur,
the airgun operations will be suspended until the vessel is greater
than 5 km away and otherwise not interfering with subsistence
activities.
Endangered Species Act (ESA)
On May 21, 2010, USGS initiated informal consultation, under
Section 7 of the ESA, with the NMFS, Office of Protected Resources,
Endangered Species Division, on this proposed seismic survey. Based on
the information provided by USGS, NMFS concurred with their
determination that the activities conducted during the proposed seismic
survey are not likely to adversely affect endangered whales in the
study area. No designated critical habitat occurs within the action
area for this experiment, therefore, no critical habitat will be
affected by the proposed bathymetric and seismic surveys and other
associated activities.
National Environmental Policy Act (NEPA)
With its complete application, USGS provided NMFS an Environmental
Assessment (EA) analyzing the direct, indirect and cumulative
environmental impacts of the proposed specified activities on marine
mammals including those listed as threatened or endangered under the
ESA. The EA, prepared by LGL Environmental Research Associated (LGL) on
behalf of USGS, USCG, and NOAA is titled Draft Environmental Assessment
of a Marine Geophysical Survey of Portions of the Arctic Ocean, August-
September, 2010 (EA). Prior to making a final decision on the IHA
application, NMFS will either prepare an independent EA, or, after
review and evaluation of the USGS EA for consistency with the
regulations published by the Council of Environmental Quality (CEQ) and
NOAA Administrative Order 216-6, Environmental Review Procedures for
Implementing the National Environmental Policy Act, adopt the USGS EA
and make a decision of whether or not to issue a Finding of No
Significant Impact (FONSI).
Preliminary Determinations
NMFS has preliminarily determined that the impact of conducting the
specific marine seismic survey activities described in this notice and
the IHA request in the specific geographic region within the U.S. EEZ
within the Arctic Ocean may result, at worst, in a temporary
modification in behavior (Level B harassment) of small numbers of
marine mammals. No take by injury (Level A harassment), serious injury,
or mortality is anticipated, and take by harassment will be at the
lowest level practicable due to incorporation of the mitigation and
monitoring measures mentioned previously in this document. Further,
this activity is expected to result in a negligible impact on the
affected species or stocks of marine mammals. NMFS has preliminarily
determined that this proposed activity will not have an unmitigable
impact on the availability of the affected species or stock of marine
mammals for subsistence uses. USGS will coordinate with local
communities on a Plan of Cooperation.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
issue an IHA to USGS for conducting a marine seismic survey in the
Arctic Ocean from August to September, 2010, provided the previously
mentioned mitigation, monitoring, and reporting requirements are
incorporated. The duration of the IHA would not exceed one year from
the date of its issuance.
Information Solicited
NMFS asks interested persons to submit comments and information
concerning this proposed project and NMFS' preliminary determination of
issuing an IHA (see ADDRESSES). Concurrent with the publication of this
notice in the Federal Register, NMFS is forwarding copies of this
application to the Marine Mammal Commission and its Committee of
Scientific Advisors.
Dated: June 29, 2010.
Helen M. Golde,
Deputy Director, Office of Protected Resources, National Marine
Fisheries Service.
[FR Doc. 2010-16374 Filed 7-7-10; 8:45 am]
BILLING CODE 3510-22-P