Marine Mammals; Incidental Take During Specified Activities

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

[Federal Register: June 22, 2006 (Volume 71, Number 120)]
[Notices]
[Page 35928-35944]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr22jn06-101]

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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service

AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of receipt of application and proposed incidental
harassment authorization; request for comments.

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SUMMARY: The Fish and Wildlife Service (Service) has received an
application from the University of Texas at Austin Institute for
Geophysics (UTIG) for authorization to take small numbers of marine
mammals by harassment incidental to conducting a marine seismic survey
in the Arctic Ocean, including the Chukchi Sea, from approximately July
15 through August 25, 2006. In accordance with provisions of the Marine
Mammal Protection Act (MMPA), as amended, the Service requests comments
on its proposed authorization for the applicant to incidentally take,
by harassment, small numbers of Pacific walrus and polar bears in the
Chukchi Sea during the seismic survey.

DATES: Comments and information must be received by July 24, 2006.

ADDRESSES: You may submit comments by any of the following methods:
1. By mail to: Craig Perham, Office of Marine Mammals Management,
U.S. Fish and Wildlife Service, 1011 East Tudor Road, Anchorage, Alaska
99503.
2. By fax to: 907-786-3816.
3. By electronic mail (e-mail) to: FW7MMM@FWS.gov. Please submit
comments as an ASCII file avoiding the use of special characters and
any form of encryption. Please also include your name and return
address in your message. If you do not receive a confirmation from the
system that we have received your message, contact us directly at U.S.
Fish and Wildlife Service, Office of Marine Mammals Management, 907-
786-3810 or 1-800-362-5148.
4. By hand-delivery to: Office of Marine Mammals Management, U.S.
Fish and Wildlife Service, 1011 East Tudor Road, Anchorage, Alaska 99503.

FOR FURTHER INFORMATION CONTACT: Craig Perham, Office of Marine Mammals
Management, U.S. Fish and Wildlife Service, 1011 East Tudor Road,
Anchorage, Alaska 99503; telephone 907-786-3810 or 1-800-362-5148; or
e-mail craig_perham@FWS.gov.

SUPPLEMENTARY INFORMATION:

Background

Sections 101(a)(5)(A) and (D) of the MMPA, as amended, (16 U.S.C.
1371(a)(5)(A) and (D)) authorize the Secretary of the Interior to
allow, upon request, the incidental, but not intentional, taking of
small numbers of marine mammals by U.S. citizens who engage in a
specified activity (other than commercial fishing) within a specified
geographical region provided that 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
and comment.
Authorization to incidentally take marine mammals may be granted if
the Service finds that the taking will have a negligible impact on the
species or stock(s), and will not have an unmitigable adverse impact on
the availability of the species or stock(s) for subsistence uses.
Permissible methods of taking and other means of affecting the least
practicable impact on the species or stock and its habitat, and
requirements pertaining to the monitoring and reporting of such
takings, are prescribed as part of the authorization process.
The term ``take,'' as defined by the MMPA, means to harass, hunt,
capture, or kill, or attempt to harass, hunt, capture, or kill any
marine mammal. Harassment, as defined by the MMPA, means ``any act of
pursuit, torment, or annoyance which--(i) has the potential to injure a
marine mammal or marine mammal stock in the wild [the MMPA calls this
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 [the MMPA calls
this Level B harassment].''
The terms ``small numbers,'' ``negligible impact,'' and
``unmitigable adverse impact'' are defined in 50 CFR 18.27, the
Service's regulations governing take of small numbers of marine mammals
incidental to specified activities. ``Small numbers'' is defined as ``a
portion of a marine mammal species or stock whose taking would have a
negligible impact on that species or stock.'' ``Negligible impact'' is
defined 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.'' ``Unmitigable adverse impact'' is defined
as ``an impact resulting from the specified activity (1) that is likely
to reduce the availability of the species to a level insufficient for a
harvest to meet subsistence needs by (i) causing the marine mammals to
abandon or avoid hunting areas, (ii) directly displacing subsistence
users, or (iii) placing physical barriers between the marine mammals
and the subsistence hunters; and (2) that cannot be sufficiently
mitigated by other measures to increase the availability of marine
mammals to allow subsistence needs to be met.''
Section 101(a)(5)(D) of the MMPA established an expedited process
by which citizens of the United States can apply for an authorization
to incidentally take small numbers of marine mammals where the take
will be limited to harassment. Section 101(a)(5)(D)(iii) establishes a
45-day time limit for Service review of an application followed by a
30-day public notice and comment period on any proposed authorizations
for the incidental harassment of marine mammals. Within 45 days of the
close of the comment period, the Service must

[[Page 35929]]

either issue or deny issuance of the authorization. The Service refers
to these authorizations as Incidental Harassment Authorizations (IHAs).

Summary of Request

On March 17, 2006, the Service received an application from UTIG
for the taking by harassment of Pacific walrus and polar bears
incidental to conducting, with research funding from the National
Science Foundation (NSF), a marine seismic survey in the Western Canada
Basin, Chukchi Borderland, and Mendeleev Ridge of the Arctic Ocean
during July through August, 2006. The seismic survey will be operated
in conjunction with a sediment coring project, which will obtain data
regarding crustal structure, and will take place far north of the
Chukchi Sea. A description of the coring activities is provided in the
National Oceanic and Atmospheric Administration's (NOAA) proposed IHA
for this same research cruise in the Federal Register of May 15, 2006
(71 FR 27997). Walrus do not occur in the area of the coring activities
and there is no potential for harassment of walrus. There is a
potential that coring activities may encounter a very few isolated
members of the Chukchi Sea polar bear stock; however, the effects to
those individuals would be no more than minimal. This authorization,
therefore, assesses the incidental harassment of walrus and polar bear
resulting from the seismic survey activity in the Chukchi Sea.
The purpose of the proposed study is to collect seismic reflection
and refraction data and sediment cores that reveal the crustal
structure and composition of submarine plateaus in the western Amerasia
Basin in the Arctic Ocean. Past studies have led many researchers to
support the idea that the Amerasia Basin opened about a pivot point
near the Mackenzie Delta. However, the crustal character of the Chukchi
Borderlands could determine whether that scenario is correct, or
whether more complicated tectonic scenarios must be devised to explain
the presence of the Amerasia Basin. These data will assist in the
determination of the tectonic evolution of the Amerasia Basin and
Canada Basin, which is fundamental to such basic concerns as sea level
fluctuations and paleoclimate in the Mesozoic era.

Description of the Activity

The Healy, a U.S. Coast Guard (USCG) Cutter ice-breaker, will
rendezvous with the science party off Barrow, Alaska, on or around July
15, 2006. Trained marine mammal observers will also be onboard during
the cruise. The Healy will sail north and arrive at the beginning of
the seismic survey, which will start more than 150 kilometers (km) (93
miles [mi]) north of Barrow. The cruise will last for approximately 40
days, and it is estimated that the total seismic survey time will be
approximately 30 days depending on ice conditions. Seismic survey work
is scheduled to terminate west of Barrow about August 25, 2006. The
vessel will then sail south to Nome, Alaska, where the science party
will disembark. In conjunction with the seismic survey, a sediment
coring project will be conducted in the Arctic Ocean, north of the
Chukchi Sea. The NOAA's proposed IHA for this same research cruise,
published in the Federal Register of May 15, 2006, describes the coring
project activities.
The majority of seismic survey activities will take place in the
Arctic Ocean. The Chukchi Sea segment of the survey is approximately
478 km, located between 75[deg] N and 70.9[deg] N and will occur in
mid- to late August. The bulk of the seismic survey will not be
conducted in any country's territorial waters. However, the survey will
occur within the Exclusive Economic Zone (EEZ) of the United States for
approximately 563 km.
The Healy will use a portable Multi-Channel Seismic (MCS) system to
conduct the seismic survey. A cluster of eight airguns will be used as
the energy source during most of the cruise, especially in deep water
areas. The airgun array will have four 500-cubic inches
(in3) Bolt airguns and four 210-in3 G. guns for a
total discharge volume of 2,840-in3. In shallow water,
occurring during the first and last portions of the cruise, a four 105-
in3 GI gun array with a total discharge volume of 420
in3 will be used. Other sound sources (see below) will also
be employed during the cruise. The seismic operations during the survey
will be used to obtain information on the history of the ridges and
basins that make up the Arctic Ocean.
The airgun arrays will discharge about once every 60 seconds. The
compressed air will be supplied by compressors onboard the source
vessel. The Healy will also tow a hydrophone streamer 100 to 150 meters
(328 to 492 feet [ft]) behind the ship, depending on ice conditions.
The hydrophone streamer will be up to 200 m (656 ft) long. As the
source operates along the survey lines, the hydrophone receiving system
will receive and record the returning acoustic signals. In addition to
the hydrophone streamer, sea ice seismometers (SIS) will be deployed on
ice floes ahead of the ship using a vessel-based helicopter, and then
retrieved from behind the ship once it has passed the SIS locations.
The SISs will be deployed as much as 120 km (74 mi) ahead of the
ship, and recovered when as much as 120 km (74 mi) behind the ship. The
seismometers will be placed on top of ice floes with a hydrophone
lowered into the water through a small hole drilled in the ice. These
instruments will allow seismic refraction data to be collected in the
heavily ice-covered waters of the region.
The program will consist of a total of approximately 3,625 km
(2,252 mi) of surveys, not including transits when the airguns are not
operating. The area included in this proposal is the southwest leg,
which extends 478 km into the Chukchi Sea (south of 75[deg] N). Water
depths within the study area are 40 to 3,858 m (131 to 12,657 ft).
Little more than 15 percent (approximately 73 km [45 mi]) of the
Chukchi Sea survey segment will occur in water deeper than 1,000 m
(3,280 ft); 21 percent (approximately 102 km [63 mi]) will be conducted
in water 100 to 1,000 m (328 to 3,280 ft) deep. Most of the Chukchi
survey track, 64 percent (approximately 303 km [188 mi]), will occur in
water less than 100 m (328 ft). The Principal Investigators (PIs) plan
to use the larger, 8-airgun array for only 24 km (15 mi) along the
northernmost reach of the Chukchi survey line in deep water (greater
than 1,000 m). There will be additional seismic operations associated
with airgun testing, start up, and repeat coverage of any areas where
initial data quality is sub-standard. In addition to the airgun array,
a multibeam sonar and sub-bottom profiler will be used during the
seismic profiling and continuously when underway.

Vessel Specifications

The Healy has a length of 128 m (420 ft), a beam of 25 m (82 ft),
and a full load draft of 8.9 m (29 ft). The Healy is capable of
traveling at 5.6 km/h (3 knots) through 1.4 m (4.6 ft) of ice. A
Central Power Plant, consisting of four Sultzer 12Z AU40S diesel
generators, provides electric power for propulsion and ship's services
through a 60 Hz, 3-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 operation speed during seismic
acquisition is expected to be approximately 6.5 km/hr (hour) (3.5
knots). When not towing seismic survey gear or breaking ice, the Healy
cruises at 22 km/hr (12 knots) and has a maximum speed of 31.5 km/hr
(17 knots). It has a normal operating range

[[Page 35930]]

of about 29,650 km (18,423 mi) at 23.2 km/hr (12.5 knots).

Seismic Source Description

A portable MCS system will be installed on the Healy for this
cruise. The source vessel will tow along predetermined lines one of two
different airgun arrays (an 8-airgun array with a total discharge
volume of 2,840 in\3\ or a four GI gun array with a total discharge
volume of 420 in\3\), as well as a hydrophone streamer. Seismic pulses
will be emitted at intervals of approximately 60 seconds and recorded
at a 2 millisecond (ms) sampling rate. The 60-second spacing
corresponds to a shot interval of approximately 120 m (394 ft) at the
anticipated typical cruise speed.
As the airgun array is towed along the survey line, the towed
hydrophone array receives the reflected signals and transfers the data
to the onboard processing system. The SISs will store returning signals
on an internal datalogger and also relay them in real-time to the Healy
via a radio transmitter, where they will be recorded and processed.
The 8-airgun array will be configured as a four-G. gun cluster with
a total discharge volume of 840 in\3\ and a four Bolt airgun cluster
with a total discharge volume of 2,000 in\3\. The source output is from
246 to 253 dB re 1 [mu]Pa m. The two clusters are four meter apart,
which will result in less downward directivity than is often present
during seismic surveys and more horizontal propagation of sound. The
clusters will be operated simultaneously for a total discharge volume
of 2,840 in\3\. The 4-GI gun array will be configured the same as the
four G. gun portion of the 8-airgun array. The energy source (source
level 239-245 dB re 1 [mu]Pa m) will be towed as close to the stern as
possible to minimize ice interference. The 8-airgun array will be towed
below a depressor bird at a depth of 7-20 m (23-66 ft) depending on ice
conditions; the preferred depth is 8-10 m (26-33 ft).
The highest sound level measurable at any location in the water
from the airgun arrays would be slightly less than the nominal source
level because the actual source is a distributed source rather than a
point source. The depth at which the source is towed has a major impact
on the maximum near-field output, and on the shape of its frequency
spectrum. In this case, the source is expected to be towed at a
relatively deep depth of up to 9 m (30 ft).
The rms (root mean square) received sound 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 to describe airgun sources, 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, and to a peak-to-peak measurement of about 176
to 178 decibels, as measured for the same pulse received at the same
location (Greene 1997; 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. Additional discussion of
the characteristics of airgun pulses is included in Appendix A of
UTIG's application.

Safety Radii Proposed by UTIG

Received sound fields have been modeled by Lamont-Doherty Earth
Observatory (L-DEO) for the 8-airgun and 4-GI gun arrays that will be
used during this survey. For deep water, where most of the present
project is to occur, the L-DEO model has been shown to be
precautionary, i.e., it tends to overestimate radii for 190, 180, 170,
160 dB re 1 [mu]Pa rms (Tolstoy et al. 2004a, b).
Predicted sound fields were modeled using sound exposure level
(SEL) units (dB re 1 [mu]Pa\2\-s), because a model based on those units
tends to produce more stable output when dealing with mixed-gun arrays
like the one to be used during this survey. The predicted SEL values
can be converted to rms received pressure levels, in dB re 1 [mu]Pa by
adding approximately 15 dB to the SEL value (Greene 1997; McCauley et
al. 1998, 2000). The rms pressure is an average over the pulse
duration. This is the measure commonly used in studies of marine mammal
reactions to airgun sounds. The rms level of a seismic pulse is
typically about 10 dB less than its peak level.
Empirical data concerning 190, 180, 170, and 160 dB (rms) distances
in deep and shallow water were acquired for various airgun array
configurations during the acoustic verification study conducted by L-
DEO in the northern Gulf of Mexico (Tolstoy et al. 2004a, b). The
proposed Chukchi Sea survey track will occur mainly in shallow water
with approximately 64 percent of trackline in water depths greater than
100 m, 21 percent in intermediate water depths (100-1,000 m), and 15
percent in water deeper than 1,000 meter.
The L-DEO model does not allow for bottom interactions, and thus,
is most directly applicable to deep water and to relatively short
ranges. In intermediate-depth water a precautionary 1.5x correction
factor will be applied to the values predicted by L-DEO's model, as has
been done in other recent NSF-sponsored seismic studies. In shallow
water, larger precautionary factors derived from the empirical shallow-
water measurements will be applied (see Table 1).

Table 1.--Estimated Distances to Which Sound Levels (dB re 1[mu]
Pa) Might Be Received From Various Gun-Types Used During the Healy Arctic Cruise
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Estimated distances for received levels (m)
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170 dB
(alternate
Seismic source volume Water depth 190 dB (shut- 180 dB (shut- behavioral 160 dB (assumed
down criterion down criterion harassment onset of
for pinnipeds) for cetaceans) criterion for behavioral
delphinids & harassment)
pinnipeds)
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105 in\3\ GI gun.............................. >1,000 m........................ 10 27 90 275
100-1,000 m..................... 15 41 135 413
< 100 m.......................... 125 200 375 750
210 in\3\ G. gun.............................. >1,000 m........................ 20 78 222 698
100-1,000 m..................... 30 117 333 1,047
< 100 m.......................... 250 578 925 1,904
420 in\3\ (4-GI gun array).................... >1,000 m........................ 75 246 771 2,441

[[Page 35931]]

100-1,000 m..................... 113 369 1,157 3,662
< 100 m.......................... 938 1,822 3,213 6,657
2,840 in\3\ (8-airgun array).................. >1,000 m........................ 230 716 2,268 7,097
100-1,000 m..................... *NA *NA *NA *NA
< 100 m.......................... *NA *NA *NA *NA
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* The 8-airgun array will only be operated in deep (greater than 1,000 m) water for approximately 24 km at the northern extent of the Chukchi Sea portion
of the survey.

The empirical data indicate that, for deep water (greater than
1,000 m), the L-DEO model tends to overestimate the received sound
levels at a given distance (Tolstoy et al. 2004a, b). However, to be
precautionary pending acquisition of additional empirical data, it is
proposed that safety radii during airgun operations in deep water will
be the values predicted by L-DEO's modeling, after conversion from SEL
to rms (Table 1). The estimated 190 dB (rms) radii for 8-airgun and 4-
GI gun arrays are 230 (745 ft) and 75 m (246 ft), respectively.
Empirical measurements were not taken for intermediate depths (100-
1,000 m). On the expectation that results would be intermediate between
those from shallow and deep water, a 1.5x correction factor is applied
to the estimates provided by the model for deep water situations. This
is the same factor that has been applied to the model estimates during
L-DEO operations in intermediate-depth water from 2003 through early
2005. The assumed 190 dB (rms) radius in intermediate-depth water is
113 m for the 4-GI gun array (Table 1). The 8-airgun array will only be
used in deep water, i.e., greater than 1,000 m.
Empirical measurements were not made for the 4 GI guns that will be
employed during the proposed survey in shallow water (less than 100 m).
(The 8-airgun array will not be used in shallow water.) The empirical
data on operations of two 105 in\3\ GI guns in shallow water showed
that modeled values underestimated the distance to the actual 160 dB
sound level radii in shallow water by a factor of approximately 3
(Tolstoy et al. 2004b). Sound level measurements for the 2 GI guns were
not available for distances less than 0.5 km (.31 mi) from the source.
The radii estimated here for the 4-GI guns operating in shallow water
are derived from the L-DEO model, with the same adjustments for depth-
related differences between modeled and measured sound levels as were
used for 2-GI guns in earlier applications. Correction factors for the
different sound level radii are approximately 12x the model estimate
for the 190 dB radius in shallow water, approximately 7x for the 180 dB
radius, and approximately 4x for the 170 dB radius (Tolstoy 2004a, b).
Thus, the 190 dB radius in shallow water is assumed to be 938 m (3,077
ft) for the 4-GI gun array (Table 1).
Pursuant to the mitigation measures of this proposed authorization,
the airguns will be powered down (or shut-down if necessary)
immediately when walrus or polar bears are detected within or about to
enter the appropriate radii. The 190 dB safety criteria are consistent
with guidelines listed for pinnipeds, by the National Marine Fisheries
Service (NMFS) (2000) and other guidance by NMFS. The UTIG will
conservatively apply the same 190 dB criterion to polar bears in water
in this IHA request. Although sound effects on the walrus and polar
bears have not been studied, the 190 dB criterion was selected because
walrus, which are pinnipeds, are expected to react similarly to other
pinnipeds. Polar bears normally swim with their heads above the surface
and are likely to be less sensitive than pinnipeds to human-caused
underwater sounds.

Other Acoustic Devices

Along with the airgun operations, additional acoustical systems
will be operated during much of or the entire cruise. The ocean floor
will be mapped with a multibeam sonar, and a sub-bottom profiler will
be used. These two systems are commonly operated simultaneously with an
airgun system. An acoustic Doppler current profiler will also be used
through the course of the project.
A SeaBeam 2112 multibeam 12 kHz bathymetric sonar system will be
used on the Healy, with a maximum source output of 237 dB re 1 [mu]Pa
at one meter. The transmit frequency is a very narrow band, less than
200 Hz, and centered at 12 kHz. Pulse lengths range from less than one
ms to 12 ms. The transmit interval ranges from 1.5 to 20 seconds,
depending on the water depth, and is longer in deeper water. The
SeaBeam system consists of a set of underhull projectors and
hydrophones. The transmitted beam is narrow (approximately 2[deg]) in
the fore-aft direction but broad (approximately 132[deg]) in the cross-
track direction. The system combines this transmitted beam with the
input from an array of receiving hydrophones oriented perpendicular to
the array of source transducers, and calculates bathymetric data (sea
floor depth and some indications about the character of the seafloor)
with an effective 2[deg] by 2[deg] footprint on the seafloor. The
SeaBeam 2112 system on the Healy produces a useable swath width of
slightly more than 2 times the water depth. This is narrower than
normal because of the ice-protection features incorporated into the
system on the Healy.
The Knudsen 320BR will provide information on sedimentary layering,
down to between 20 and 70 m, depending on bottom type and slope. It
will be operated with the multibeam bathymetric sonar system that will
simultaneously map the bottom topography.
The Knudsen 320BR sub-bottom profiler is a dual-frequency system
with operating frequencies of 3.5 and 12 kHz:
Low frequency--Maximum output power into the transducer array, as
wired on the Healy (125 ohms), at 3.5 kHz is approximately 6,000 watts
(electrical), which results in a maximum source level of 221 dB re 1
[mu]Pa at 1 m downward. Pulse lengths range from 1.5

[[Page 35932]]

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 1-percent duty
cycle. Typical repetition rate is between one-half second (in shallow
water) to 8 s in deep water.
High frequency--The Knudsen 320BR is capable of operating at 12
kHz, but the higher frequency is rarely used because it interferes with
the SeaBeam 2112 multibeam sonar, which also operates at 12 kHz. The
calculated maximum source level (downward) is 215 dB re 1 [mu]Pa at 1 m
(3.28 ft). The pulse duration is typically 1.5 to 5 ms with the same
limitations and typical characteristics as the low-frequency channel.
A single 12 kHz transducer and one 3.5 kHz, low-frequency (sub-
bottom) transducer array, consisting of 16 elements in a 4-by-4 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], and the 3.5 kHz
transducer (TR109) emits a conical beam with a width of 26[deg].
The 150 kHz acoustic Doppler current profiler (ADCPTM)
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 ADCPTM's maximum
depth range is 300 m.
The Ocean Surveyor 75 is an ADCPTM 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 (2,297 ft).

Plan of Cooperation

The UTIG will consult with representatives of the communities along
the Chukchi Sea coast to identify any areas or issues of potential
conflict. These communities are Point Hope, Point Lay, Wainwright, and
Barrow. A Plan of Cooperation (POC) for the 2006 seismic survey in the
Chukchi Sea will be developed if identified as warranted during these
consultations and determined to be necessary by the Service. The POC
would cover the phases of UTIG's seismic surveys planned in the Chukchi
Sea when appropriate for the 2006 project. The purpose of the POC will
be to identify measures that will be taken to minimize any adverse
effects on the availability of marine mammals for subsistence uses, and
to ensure good communication between the project scientists and the
native communities along the coast.
Subsequent meetings with community representatives and any other
parties to the POC will be held as necessary to negotiate the terms of
the plan and to coordinate the planned seismic survey operation with
subsistence hunting. The POC may address: Operational agreement and
communications procedures; where and when the agreement becomes
effective; the general communications scheme; onboard observers;
conflict avoidance; seasonally sensitive areas; vessel navigation; air
navigation; marine mammal monitoring activities; measures to avoid
impacts to marine mammals; measures to avoid conflicts in areas of
active hunting; emergency assistance; and the dispute resolution process.
In addition, one (or more) Alaska Native knowledgeable about the
mammals and fish of the area is expected to be included as a member of
the observer team aboard the Healy. Although the primary
responsibilities encompass implementing the monitoring and mitigation
requirements, duties will also include acting as a liaison with hunters
and fishers if they are encountered at sea. In the unlikely event
subsistence hunting or fishing is occurring within 5 km (3 mi) of the
Healy's trackline, the airgun operations will be suspended until the
Healy is approximately 5 km (3 mi) away.

Description of Habitat and Marine Mammals Affected by the Activity

A detailed description of the Chukchi Sea ecosystem and the
associated marine mammals can be found in several documents (Corps of
Engineers 1999; NMFS 1999; Minerals Management Service (MMS) 2006,
1996, and 1992). MMS' Programmatic Environmental Assessment (PEA)-
Arctic Ocean Outer Continental Shelf Seismic Surveys 2006--may be
viewed at: http://www.mms.gov/alaska .
The marine mammals that occur in the proposed survey area belong to
three taxonomic groups: odontocetes (toothed cetaceans, such as beluga
whale and narwhal whale), mysticetes (baleen whales), and carnivora
(pinnipeds and polar bears). Cetaceans and pinnipeds, with the
exception of walrus, are managed by the NMFS and are being addressed by
that agency (71 FR 27997; May 15, 2006). Pacific walrus and polar bear,
which are managed by the Service, are the subject of this proposed IHA.

Pacific Walrus

Concentrations of walrus might be encountered in certain areas,
depending on the location of the edge of the pack ice relative to their
favored shallow-water foraging habitat. There are two recognized
subspecies of walrus: the Pacific walrus (Odobenus rosmarus divergens)
and Atlantic walrus (O. r. rosmarus). Only the Pacific subspecies is
potentially within the planned seismic survey study area.
The Pacific walrus is represented by a single stock of animals that
inhabits the shallow continental shelf waters of the Bering and Chukchi
Seas, occasionally moving into the East Siberian and Beaufort Seas. The
population ranges across the international boundaries of the United
States and Russia, and both nations share common interests with respect
to the conservation and management of this species.
Walrus are migratory, moving south with the advancing ice in autumn
and north as the ice recedes in spring (Fay 1981). In the summer, most
of the population of Pacific walrus moves to the Chukchi Sea, but
several thousands aggregate in the Gulf of Anadyr and in Bristol Bay
(Angliss and Lodge 2004). Limited numbers of walrus inhabit the
Beaufort Sea during the open water season, and they are considered
extralimital east of Point Barrow (Sease and Chapman 1988).
The northeast Chukchi Sea west of Barrow is the northeastern extent
of the main summer range of the walrus, and only a few are seen farther
east in the Beaufort Sea (e.g., Harwood et al. 2005). Walrus observed
in the Beaufort Sea have typically been lone individuals. The reported
subsistence harvest of walrus by Barrow hunters for the 5-year period
of 1994-1998 was 99 walrus (USDI 2000a). Most of these were harvested
west of Point Barrow. In addition, between 1988 and 1998, Kaktovik
hunters harvested one walrus (USDI 2000b).
Walrus are most commonly found near the southern margins of the
pack ice as opposed to deep in the pack where few open leads (polynyas)
exist to afford access to the sea for foraging (Estes and Gilbert 1978;
Gilbert 1989; Fay 1982). Walrus are not typically found in areas of
greater than 80 percent ice cover (Fay 1982). Ice serves as an
important mobile platform, floating the walrus on to new foraging
habitat and providing a place to rest and nurse their young.
This close relationship to the ice largely determines walrus
distribution and the timing of their migrations. As the pack ice breaks
up in the Bering Sea and recedes northward in May and June, a majority
of subadults, females, and calves migrate with it, either by

[[Page 35933]]

swimming or resting on drifting ice sheets. Many males will choose to
stay in the Bering Sea for the entire year, with concentrations near
Saint Lawrence Island and further south in Bristol Bay. Two northward
migration pathways are apparent, either toward the eastern Chukchi Sea
near Barrow or northwestward toward Wrangel Island. By late June to
early July, concentrations of walrus migrating northeastward spread
along the Alaska coast congregating within 200 km of the shore from
Saint Lawrence Island to southwest of Barrow. In August, largely
dependent on the retreat of the pack ice, walrus are found further
offshore with principal concentrations to the northwest of Barrow. By
October, a reverse migration occurs out of the Chukchi Sea, with
animals swimming ahead of the developing pack ice, as it is too weak to
support them (Fay 1982).
Estimates of the pre-exploitation population of the Pacific walrus
range from 200,000 to 400,000 animals (USFWS 2000a). Over the past 150
years, the population has been depleted by overharvesting and then
periodically allowed to recover (Fay et al. 1989). An aerial survey
flown in 1990 produced a population estimate of 201,039 animals;
however, large confidence intervals associated with that estimate
precluded any conclusions concerning population trend (Gilbert et al.
1992). The most current minimum population estimate is 188,316 walrus
(USFWS 2000a). This estimate is conservative, because a portion of the
Chukchi Sea was not surveyed due to lack of ice. The Service and U.S.
Geological Survey, in partnership with Russian scientists, will conduct
a rangewide survey to estimate population size. The results of these
survey efforts should be available in 2007 (USFWS 2006).
Pacific walrus feed primarily on benthic invertebrates,
occasionally fish and cephalopods, and more rarely, some adult males
may prey on other pinnipeds (reviewed in Riedman 1990). Walrus
typically feed in depths of 10 to 50 m (Vibe 1950; Fay 1982). Though
the deepest dive recorded for a walrus was 133 m, they are more likely
to be found in depths of 80 m or less in coastal or continental shelf
habitats, where the clams and other mollusks that walrus prefer are
found (Fay 1982; Fay and Burns 1988; Reeves et al. 2002). In a recent
study in Bristol Bay, 98 percent of satellite locations of tagged
walrus were foraging in water depths of 60 m or less (Chadwick and
Hills 2005).
Polar bears (Ursus maritimus) are known to prey on walrus calves,
and killer whales (Orcinus orca) have been known to take all age
classes of animals. Predation levels are thought to be highest near
terrestrial haulout sites where large aggregations of walrus can be
found; however, few observations exist for off-shore environs.
Pacific walrus have been hunted by coastal Natives in Alaska and
Chukotka for thousands of years. Exploitation of walrus by Europeans
has also occurred in varying degrees since first contact. Presently,
walrus hunting in Alaska and Chukotka is restricted to meet the
subsistence needs of aboriginal peoples. The Service, in partnership
with the Eskimo Walrus Commission (EWC) and the Association of
Traditional Marine Mammal Hunters of Chukotka, administers subsistence
harvest monitoring programs in Alaska and Chukotka.
Intraspecific trauma is also a known source of walrus injury and
mortality. Disturbance events can cause walrus to stampede into the
water and have been known to result in injuries and mortalities. The
risk of stampede-related injuries increases with the number of animals
hauled out. Calves and young animals at the perimeter of these herds
are particularly vulnerable to trampling injuries.
Most (64 percent or 303 km) of the proposed Chukchi Sea seismic
work will take place in water less than 100 m deep. Of those 303 km,
220 km will be surveyed in water greater then 60 m, where walrus prefer
to forage (Chadwick and Hills 2005). During a survey through open water
in the northern Chukchi Sea in early August of 2005, only three walrus
were sighted south of 72.8[deg] N in water 47 to 69 m deep (Haley and
Ireland 2006).
The probability of encountering Pacific walrus along the proposed
survey line in the Chukchi Sea will depend on the location of the
southern margin of the pack ice and the timing of spring break-up. If
the Healy crosses the margin when the ice margin is close to depths
where walrus prefer to feed, it is likely that walrus will be encountered.

Polar Bear

Polar bears have a circumpolar distribution throughout the northern
hemisphere (Amstrup et al. 1986) and occur in relatively low densities
throughout most ice-covered areas (DeMaster and Stirling 1981). Polar
bears are divided into six major populations and many sub-populations
based on mark-and-recapture studies (Lentfer 1983), radio telemetry
studies (Amstrup and Gardner 1994), and morpho-metrics (Manning 1971;
Wilson 1976). Polar bears are common in the Chukchi and Beaufort Seas
north of Alaska throughout the year, including the late summer period
(Harwood et al. 2005). They also occur throughout the East Siberian,
Laptev, and Kara Seas of Russia and the Barent's Sea of northern
Europe. They are found in the northern part of the Greenland Sea, and
are common in Baffin Bay, which separates Canada and Greenland, as well
as through most of the Canadian Arctic Archipelago.
In Alaska, they have been observed as far south in the eastern
Bering Sea as St. Matthew Island and the Pribilof Islands, but they are
most commonly found within 180 miles of the Alaskan coast of the
Chukchi and Beaufort Seas, from the Bering Strait to the Canadian
border. Two stocks occur in Alaska: (1) The Chukchi/Bering Seas stock;
and (2) the Southern Beaufort Sea stock. The Chukchi/Bering Seas stock
is defined as polar bears inhabiting the area as far west as the
eastern portion of the Eastern Siberian Sea, as far east as Point
Barrow, and extending into the Bering Sea, with its southern boundary
determined by the extent of annual ice.
The world population estimate of polar bears ranges from 20,000-
25,000 individuals (ICUN, in prep). Amstrup (1995) estimated the
minimum population of polar bears for the Beaufort Sea to be
approximately 1,500 to 1,800 individuals, with an average density of
about one bear per 38.6 to 77.2 square miles (100 to 200 km\2\).
Previous population estimates have put the Chukchi/Bering Seas
population at 2,000 to 5,000; however, there are no reliable data on
the population status of polar bears in the Bering/Chukchi Seas. An
estimate was derived by subtracting the total estimated Alaska polar
bear population from the Beaufort Sea population, thus yielding an
estimate of 1,200-3,200 animals (Amstrup 1995).
The Alaskan polar bear population is considered to be stable or
increasing slightly (USFWS 2000b, c). Polar bear populations located in
the Southern Beaufort Sea have been estimated to have an annual growth
rate of 2.2 to 2.4 percent with an annual harvest of only 1.9 percent
(Amstrup 1995). The Southern Beaufort Sea population ranges from the
Baillie Islands, Canada, in the east to Point Hope, Alaska, in the
west. The Chukchi/Bering Seas population ranges from Point Barrow,
Alaska, in the east to the Eastern Siberian Sea in the west. These two
populations overlap between Point Hope and Point Barrow, Alaska,
centered near Point Lay (Amstrup 1995). Both of these populations have
been extensively studied by tracking the movement of tagged females
(Garner et al. 1990). Radio-tracking studies indicate significant
movement within

[[Page 35934]]

populations and occasional movement between populations (Garner et al.
1990; Amstrup 1995).
Although insufficient data exist to accurately quantify polar bear
denning along the Alaskan Chukchi Sea coast, dens in the area are less
concentrated than for other areas in the Arctic. The majority of
denning of Chukchi Sea polar bears occurs on Wrangel Island, Herald
Island, and certain locations on the northern Chukotka coast. Females
without dependent cubs breed in the spring, and pregnant females enter
maternity dens by late November; the young are usually born in late
December or early January. Female bears can be quite sensitive to
disturbances during this denning period.
Greater than 90 percent of a polar bear's diet is ringed (Phoca
hispida) and bearded (Erignathus barbatus) seals; walrus calves are
hunted occasionally. Polar bears hunt in areas where there are high
concentrations of ringed and bearded seals (Larsen 1985; Stirling and
McEwan 1975). This includes areas of land-fast ice, as well as moving
pack ice. They hunt along leads and other areas of open water, or by
waiting at a breathing hole, or by breaking through the roof of a
seal's lair. Lairs are excavated in snow drifts on top of the ice.
Bears also stalk seals in the spring when they haul out on the ice in
warm weather. The relationship between ice type and bear distribution
is as yet unknown, but it is suspected to be related to seal
availability. Polar bears are opportunistic feeders and feed on a
variety of foods and carcasses, including other marine mammals,
reindeer, arctic cod, and geese and their eggs (Smith 1985; Jefferson
et al. 1993; Smith and Hill 1996; Derocher et al. 2000). Polar bears
are also known to eat nonfood items including styrofoam, plastic,
antifreeze, and hydraulic and lubricating fluids.
The most significant source of mortality is man. Before the MMPA
was passed, polar bears were taken by sport hunters and residents.
Between 1925 and 1972, the mean reported kill was 186 bears per year.
Since 1972, only Alaska Natives have been allowed to hunt polar bears
for their subsistence uses or for handicraft and clothing items for
sale. From 1980 to 2005, the total annual harvest for Alaska averaged
101 bears: 64 percent from the Chukchi Sea and 36 percent from the
Beaufort Sea.
MMS bowhead whale aerial surveys since 1979 have documented an
increase, starting in 1992, in the proportion of polar bears associated
with land vs. sea-ice in the fall season (Monnett et al. 2005). In
2004, a large number of bears were observed swimming more than 2 km
offshore, and a number of polar bear carcasses were subsequently
observed offshore. Monnett et al. (2005) suggest that, as the pack ice
edge moves northward, drowning deaths of polar bears may increase. The
number of polar bears encountered in open water may, therefore, be
slightly higher than previously reported.
Polar bears typically range as far north as 88[deg] N (Ray 1971;
Durner and Amstrup 1995); at about 88[deg] N their population thins
dramatically. However, polar bears have been observed across the
Arctic, including close to the North Pole (van Meurs and Splettstoesser
2003). Stirling (1990) reported that, of 181 sightings of bears, only 3
were above 82[deg] N. Three polar bears were observed from the Healy in
the northern Chukchi Sea during a survey through this area in August of
2005 (Haley and Ireland 2006). These three sightings occurred along
2,401 km of observed trackline over 14 days between 70[deg] N and
81[deg] N.
Historically, polar bears have preferred the pack ice over coastal
areas during the summer (Stirling 1988; Amstrup 1995). However, since
the late 1980s, polar bears have been observed in greater numbers near
coastal areas during late summer and fall in the central Beaufort Sea
(Schliebe et al. 2004). This recent observation of bear behavior may be
related to the 30-year moratorium on polar bear hunting and the recent
success of subsistence whale harvests, the scraps of which appear to
have become a reliable, annual food source for polar bears (Schliebe et
al. 2004). The Healy is likely to encounter polar bears when it enters
the pack ice, and small numbers of bears could be encountered anywhere
along the entire trackline, as well as in the course of coring activities.

Potential Impacts of Activities on Pacific Walrus and Polar Bear

Potential Effects of Airguns

The effects of sounds from airguns might include one or more of the
following: noise, behavioral disturbance, and, at least in theory,
temporary or permanent hearing impairment, or non-auditory physical
effects (Richardson et al. 1995). Because the airgun sources planned
for use during the present project involve only 4 or 8 airguns, the
effects are anticipated to be less than would be the case with a large
array of airguns. It is very unlikely that there would be any cases of
temporary or especially permanent hearing impairment, or non-auditory
physical effects. Also, behavioral disturbance is expected to be
limited to relatively short distances.

Species Perception of Sound and Masking Effects

The underwater hearing of a walrus has been measured at frequencies
from 13 Hz to 1,200 Hz. The range of best hearing was from 1 to 12 kHz,
with maximum sensitivity (67 dB re 1 [mu]Pa) occurring at 12 kHz
(Kastelein et al. 2002). Most of the energy in the sound pulses emitted
by airgun arrays is at low frequencies, with the strongest spectrum
levels below 200 Hz and considerably lower spectrum levels above 1,000
Hz. These low frequencies are not generally used by Pacific walrus.
Masking effects of pulsed sound (even from large arrays of airguns) on
Pacific walrus calls and other natural sounds are expected to be
limited, and given the intermittent nature of these seismic pulses,
masking effects are expected to be negligible. Any sound levels
received by polar bears in the water would be attenuated because polar
bears generally swim with their heads out of the water or at the
surface and polar bears do not dive much below 4.5 m. Received levels
of airgun sounds are reduced near the surface because of the pressure
release effect at the water's surface (Greene and Richardson 1988;
Richardson et al. 1995). Walrus and polar bears on the ice would be
unaffected by underwater sound.

Disturbance Reactions

Disturbance includes a variety of effects, including subtle changes
in behavior, more conspicuous changes in activities, and displacement.
Reactions to sound depend on species, state of maturity, experience,
current activity, reproductive state, time of day, and many other
factors. If a marine mammal does react briefly to a disturbance by
changing its behavior or moving a small distance, the impacts of the
change are unlikely to be significant to the individual, let alone the
stock or the species as a whole. Alternatively, if a sound source
displaces marine mammals from an important area for a prolonged period,
impacts on the animals are most likely significant.
Numerous studies have shown that pulsed sounds from airguns are
often readily detectable in the water at distances of many kilometers;
however, numerous studies have shown that marine mammals at distances
more than a few kilometers from operating seismic vessels often show no
apparent response. That is often true even in cases when the pulsed
sounds must be readily audible to the animals based on measured
received levels and the

[[Page 35935]]

hearing sensitivity of that mammal group.
Seismic operations are expected to create significantly more noise
than general vessel and icebreaker traffic; however, data specific to
the potential response of walrus to seismic operations is limited.
Therefore, we rely on observations of walrus and other pinniped
reactions to similar activities and apply these conservatively to
determine expected reactions. Potential effects of prolonged or
repeated disturbances to Pacific walrus include displacement from
preferred feeding areas, increased stress levels, increased energy
expenditure, masking of communication, and impairment of
thermoregulation of neonates that spend too much time in the water.
There are some uncertainties in predicting the quantity and types of
impacts of noise on marine mammals; however, appropriate mitigation
measures minimize the potential for displacement.
The response of walrus to sound sources may be either avoidance or
tolerance. It is possible that noises produced by the icebreaking or
seismic activities may cause avoidance behavior in walrus. Walrus on
ice have been observed to become alert and dive into the water when
icebreakers passed over 2 km (1.2 mi) away (Fay et al. 1984; Brueggeman
et al. 1990, 1991, 1992). In addition, Brueggeman et al. (1990) suggest
that walrus on ice floes may avoid icebreakers by 10 to 15 km (6.2 to
9.3 mi). Anecdotal observations by walrus hunters and researchers
suggest that males tend to be more tolerant of disturbances than
females and individuals tend to be more tolerant than groups. Females
with dependent calves are considered least tolerant of disturbances.
Pacific walrus are not likely to show a strong avoidance reaction
to the medium-sized airgun sources that will be used. Studies in the
Beaufort Sea based on visual monitoring from seismic vessels has shown
only slight (if any) avoidance of airguns by pinnipeds in general, and
only slight (if any) changes in behavior. These studies have shown that
pinnipeds frequently do not avoid the area within a few hundred meters
of operating airgun arrays (e.g., Miller et al. 2005, Harris et al.
2001). However, visual studies have their limitations, and initial
telemetry work suggests that avoidance and other behavioral reactions
to small airgun sources may at times be stronger than evident to date
from visual studies of pinniped 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.
Quantitative research on the sensitivity of walrus to noise has
been limited because no audiograms (a test to determine the range of
frequencies and minimum hearing threshold) have been done on walrus.
Hearing range is assumed to be within the 13 Hz and 1,200 Hz range of
their own vocalizations, with maximum hearing sensitivity in the 1 to
12 kHz range (Kastelein et al. 2002). Walrus hunters and researchers
have also noted that walrus tend to react to the presence of humans and
machines at greater distances from upwind approaches than from downwind
approaches, suggesting that odor may also be a stimulus for a flight
response. The visual acuity of walrus is thought to be less than for
other species of pinnipeds. The reaction of walrus to vessels is highly
dependent on distance, vessel speed, and possibly vessel smell
(Richardson et al. 1995; Fay et al. 1984), as well as previous exposure
to hunting (D.G. Roseneau In Malme et al. 1989). Walrus in the water
appear to be less readily disturbed by vessels than walrus hauled out
on land or ice (Fay et al. 1984).
Seismic activities may affect polar bears in a number of ways.
Seismic ships and icebreakers may be physical obstructions to polar
bear movements, although these impacts are of short-term and localized
effect. Noise, sights, and smells produced by exploration activities
may repel or attract bears, either disrupting their natural behavior or
endangering them by threatening the safety of seismic personnel.
In the Chukchi Sea, during the open-water season, polar bears spend
the majority of their time on pack ice, which limits the chance of
impacts from seismic activities. Occasionally, polar bears can be found
in open water, miles from the ice edge or ice floes.
Vessel traffic could result in short-term behavioral disturbance to
polar bears. During the open-water season, most polar bears remain
offshore in the pack ice and are not typically present in the area of
vessel traffic. If a ship is surrounded by ice, it is more likely that
curious bears will approach. Any on-ice activities create the
opportunity for bear-human interactions. In relatively ice-free waters,
polar bears are less likely to approach ships, although bears may be
encountered on ice floes.
Ships and icebreakers may act as physical obstructions in the
spring if they transit through a restricted lead system, such as the
Chukchi Polynya. Polynyas are important habitat for marine mammals,
which makes them important hunting areas for polar bears. Ship traffic
in these ice conditions may intercept or alter movements of bears. A
similar situation could occur in the fall when the pack ice begins to
expand.
Little research has been conducted on the effects of noise on polar
bears. Polar bears are curious and tend to investigate novel sights,
smells, and possibly noises. Noise produced by seismic activities could
elicit several different responses in polar bears. It may act as a
deterrent to bears entering an area of operation, or potentially
attract curious bears. Underwater noises are probably not a relevant
form of disturbance because bears spend most of their time on the ice
or at the surface of the water.

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. Currently, the Service does not have specific
guidelines regarding ``allowable'' received sound levels for either
walrus or polar bears; however, we have adopted the NMFS criterion for
Pacific walrus that pinnipeds should not be exposed to impulsive sounds
greater or equal to 190 dB re 1 [mu]Pa (rms) (NMFS 2000). As a
conservative measure, this criterion is also applied to polar bear.
This criterion defines the safety (shut-down) radii planned for the
proposed seismic survey.
Several aspects of the planned monitoring and mitigation measures
for this project are designed to detect animals occurring near the
airguns (and multi-beam bathymetric sonar), and to avoid exposing them
to sound pulses that might cause hearing impairment. Marine mammal
observers will be on watch during seismic operations. In addition,
walrus and polar bears are likely to show some avoidance of the area
with high received levels of airgun sound. In those cases, the
avoidance responses of the animals themselves will reduce or (most
likely) avoid any possibility of hearing impairment.
Temporary Threshold Shift (TTS): TTS is the mildest form of hearing
impairment that can occur during exposure to a strong sound (Kryter
1985). While experiencing TTS, the hearing threshold rises and a sound
must be stronger in order to be heard. TTS can last from minutes or
hours to (in cases of strong TTS) days. For sound

[[Page 35936]]

exposures at or somewhat above the TTS threshold, hearing sensitivity
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. In Pacific walrus, TTS
thresholds associated with exposure to brief pulses (single or
multiple) of underwater sound have not been measured.
A marine mammal within a radius of 100 m around a typical large
array of operating airguns might be exposed to a few seismic pulses
with levels of 205 dB, and possibly more pulses if the mammal moved
with the seismic vessel. However, based on the implementation of the
mitigation measures required by this proposed authorization, several of
the considerations that are relevant in assessing the impact of typical
seismic surveys with arrays of airguns are not directly applicable
here. These considerations include the effects on polar bear and walrus of:
Ramping up (soft start), which is standard operational protocol
during startup of large airgun arrays in many jurisdictions. Ramping up
involves starting the airguns in sequence, usually commencing with a
single airgun and gradually adding additional airguns. This practice,
which will be employed when the airgun array is operated, requires that
the safety radius be visible for 30 minutes prior to the start of
operations and that no walrus or polar bear has been sighted within or
near the safety radius during the final 15 minutes, thereby avoiding
exposure of walrus and polar bears to potential effects of ramping up.
Longer term exposure to airgun pulses at a sufficiently high level
for a sufficiently long period to cause more than mild TTS. Because the
mitigation measures require that the operation of airguns either shut-
down or power-down (which procedure is followed depends on the
circumstances as described in the section on Mitigation) if a walrus or
polar bear approaches or nears the safety radius, long term exposure to
airgun pulses at high levels will be avoided.
The predicted 190 dB distances for the airguns operated by UTIG
vary with water depth. They are estimated to be 230 m in deep water for
the 8-airgun system, and 75 m in deep water for the 4-GI gun system. In
intermediate depths, this distance is predicted to increase to 113 m
for the 4-GI gun system. The 8-airgun array will only be used in deep
water (greater than 1,000 m). The predicted 190 dB distance for the 4-
GI gun system in shallow water is 938 m (Table 1). Shallow water (less
than 100 m) will occur along 303 km (64 percent) of the planned
trackline in the Chukchi Sea. Those sound levels are not considered to
be the levels above which TTS might occur.
Permanent Threshold Shift (PTS): When PTS occurs, there is physical
damage to the sound receptors in the ear. In some cases, there can be
total or partial deafness; in other cases, the animal has an impaired
ability to hear sounds in specific frequency ranges.
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 TTS, there has been further speculation about the
possibility that some individuals occurring very close to airguns might
incur PTS. Single or occasional occurrences of mild TTS are not
indicative of permanent auditory damage in terrestrial mammals.
Relationships between TTS and PTS thresholds have not been studied in
marine mammals, but are assumed to be similar to those in humans and
other terrestrial mammals. PTS might occur at a received sound level at
least several decibels above that inducing mild TTS if the animal were
exposed to the strong sound pulses with very rapid rise time.
It is unlikely that walrus or polar bears could receive sounds
strong enough (and over a sufficient duration) to cause permanent
hearing impairment during a project employing the medium-sized airgun
sources planned here. In the proposed project, walrus or bears are
unlikely to be exposed to received levels of seismic pulses strong
enough to cause TTS, as they would probably need to be within 100 to
200 m of the airguns for that to occur. Given the higher level of sound
necessary to cause PTS, it is even less likely that PTS could occur. In
fact, even the levels immediately adjacent to the airgun may not be
sufficient to induce PTS, especially because an animal would not be
exposed to more than one strong pulse unless it swam immediately
alongside the airgun for a period longer than the inter-pulse interval.
The planned monitoring and mitigation measures, including visual
monitoring, power-downs, and shut-downs of the airguns when walrus and
bears are seen within the safety radii, will minimize the already
minimal probability of exposure of animals to sounds strong enough to
induce PTS.
Non-auditory Physiological Effects: Non-auditory physiological
effects or injuries that theoretically might occur in Pacific walrus or
polar bears exposed to strong underwater sound include stress,
neurological effects, and other types of organ or tissue damage.
However, studies examining such effects are very 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 walrus or bear would be exposed
to strong seismic sounds long enough for significant physiological
stress to develop. That is especially so in the case of the proposed
project where the airgun configuration is moderately sized, the ship is
moving at 3 to 4 knots (5.5 to 7.4 km/hr), and for the most part, the
tracklines will not double back through the same area.
In general, little is known about the potential for seismic survey
sounds to cause auditory impairment or other physical effects in
Pacific walrus or polar bears. Available data suggest that such
effects, if they occur at all, would be limited to short distances and
probably to projects involving large arrays of airguns. Marine mammals
that show behavioral avoidance of seismic vessels, including some
pinnipeds, are especially unlikely to incur auditory impairment or
other physical effects. Also, the planned monitoring and mitigation
measures include shut-downs of the airguns, which will reduce any such
effects that might otherwise occur.
Pacific walrus or polar bears close to underwater detonations of
high explosives can be killed or severely injured, and auditory organs
would be especially susceptible to injury (Ketten et al. 1993; Ketten
1995). However, airgun pulses are less energetic and have slower rise
times, and there is no evidence that they can cause serious injury, or
death, even in the case of large airgun arrays.

Potential Effects of Bathymetric Sonar Signals

A SeaBeam 2112 multibeam 12 kHz bathymetric sonar system will be
operated from the source vessel essentially continuously during the
planned study. Sounds from the multibeam are very short pulses,
depending on water depth. Most of the energy in the sound pulses
emitted by the multibeam is at moderately high 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.
The area of possible influence of the bathymetric sonar is a narrow
band oriented in the cross-track direction below the source vessel.
Walrus or polar bears that encounter the bathymetric

[[Page 35937]]

sonar 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 pulses. In assessing
the possible impacts of a similar multibeam system (the 15.5 kHz Atlas
Hydrosweep multibeam bathymetric sonar), Boebel et al. (2004) noted
that the critical sound pressure level at which TTS may occur is 203.2
dB re 1 [mu]Pa (rms). The critical region included an area of 43 m (141
ft) in depth, 46 m (151 ft) wide athwartship, and 1 m (3.3 ft) fore-
and-aft (Boebel et al. 2004). In the more distant parts of that (small)
critical region, only slight TTS could potentially be incurred.
Walrus communications will not be masked appreciably by the
bathymetric sonar signals given the low duty cycle of the sonar and the
brief period when an individual mammal is likely to be within the sonar
beam. Furthermore, the 12 kHz multibeam will not overlap with the
predominant frequencies in walrus calls, further reducing any potential
for masking in that group.
We are not aware of any data on the reactions of Pacific walrus to
sonar sounds at frequencies similar to those of the multibeam sonar (12
kHz). Based on observations of other pinniped responses to other types
of pulsed sounds, and the likely brevity of exposure to the bathymetric
sonar sounds, Pacific walrus reactions to the sonar sounds are expected
to be limited to startle or otherwise brief responses of no lasting
consequence to the animals.
Polar bears would not occur below the Healy or elsewhere at
sufficient depth to be in the main beam of the bathymetric sonar, so
would not be affected by the sonar sounds.

Potential Effects of Sub-bottom Profiler Signals

A Knudsen 320BR sub-bottom profiler will be operated from the
source vessel at nearly all times during the planned study. The Knudsen
320BR produces sound pulses with lengths of up to 24 ms every 0.5
seconds to approximately 8 seconds, depending on water depth. The
energy in the sound pulses emitted by this sub-bottom profiler is at
mid-to moderately high frequency, depending on whether the 3.5 or 12
kHz transducer is operating. The conical beam-width is either 26[deg],
for the 3.5 kHz transducer, or 30[deg], for the 12 kHz transducer, and
is directed downward. Source levels for the Knudsen 320 operating at
3.5 and 12 kHz have been measured as a maximum of 221 and 215 dB re 1
[mu]Pa m, respectively. Received levels would diminish rapidly with
increasing depth.
Walrus communications will not be masked appreciably by the sub-
bottom profiler signals given its relatively low duty cycle,
directionality, and the brief period when an individual animal is
likely to be within its beam. The 12 kHz transducer for the Knudsen
320BR will rarely be used because its frequency interferes with the
multibeam sonar; however, neither the 3.5 kHz nor the 12 kHz sonar
signals overlap with the predominant frequencies in walrus calls, which
would avoid significant masking.
The pulsed signals from the Knudsen 320BR while the 3.5 kHz
transducer is operating are weaker than those from the bathymetric
sonar and those from the proposed 4-or 8-airgun arrays. Therefore,
behavioral responses are not expected unless an animal is close to the
source. Exposure would be brief and any response would likely be
limited and have no lasting consequence to the animals.
Source frequencies of the Knudsen 320BR are much lower than those
of the bathymetric sonar when the 3.5 kHz transducer is engaged. When
the 12.5 kHz transducer is operating (which will be seldom because it
interferes with the SeaBeam), the source frequency is similar to that
of the bathymetric sonar. As with the SeaBeam, the pulses are brief and
concentrated in a downward beam. An animal would be in the beam of the
sub-bottom profiler only briefly, reducing its received sound energy.
Thus, it is unlikely that the sub-bottom profiler produces pulse levels
strong enough to cause hearing impairment or other physical injuries
even in a walrus that is (briefly) in a position near the source.
Polar bears would not occur below the Healy or elsewhere at
sufficient depth to be in the main beam of the sub-bottom profiler, so
would not be affected by the sonar sounds.
The sub-bottom profiler is usually operated simultaneously with
other higher-power acoustic sources. Many marine mammals will move away
in response to the approaching higher-power sources or the vessel
itself before the animal would be close enough for there to be any
possibility of effects from the sub-bottom profiler. In the case of
Pacific walrus and polar bears that do not avoid the approaching vessel
and its various sound sources, mitigation measures that would be
applied to minimize effects of the higher-power sources would further
reduce or eliminate any minor effects of the sub-bottom profiler.

Effects of Helicopter Activities

Collection of seismic refraction data requires the deployment of
hydrophones at great distances from the source vessel. In order to
accomplish this in the ice-covered waters, the science party plans to
deploy SISs along seismic lines in front of the Healy and then retrieve
them off the ice once the vessel has passed. Vessel-based helicopters
will be used to shuttle SISs along seismic track lines. Deployment and
recovery of SISs every 10 to 15 km (6.2 to 9.3 mi) along the track line
and as far as 120 km (75 mi) ahead or behind the vessel will require as
many as 24 on-ice landings per 24-hr period during seismic shooting.
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
civilian helicopter service will be providing air support for this
project; however, the type of helicopter has not been determined.
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.
Few systematic studies of Pacific walrus reactions to aircraft
overflights have been completed. Documented reactions of pinnipeds
range from simply becoming alert and raising the head to escape
behavior such as hauled out animals rushing to the water. Disturbances
caused by low-flying air traffic may cause walrus groups to abandon
land or ice haulouts or to stampede. Reactions of walrus to aircraft
vary with range, aircraft type, and flight pattern, as well as walrus
age, sex, and group size. Fixed-winged aircraft are less likely to
elicit a response than helicopter overflights. Adult females, calves,
and immature walrus tend to be more sensitive to aircraft disturbance
(Loughrey 1959; Salter 1979). Walrus are particularly sensitive to
changes in engine noise and are more likely to stampede when planes
turn or fly low overhead. Severe disturbance events could result in
trampling injuries or cow-calf separations, both of which are
potentially fatal.
Although specific details of altitude and horizontal distances are
lacking from many largely anecdotal reports, escape reactions to a low
flying helicopter (lower than 150 m altitude) can be expected from walrus

[[Page 35938]]

encountered during the proposed operations. These responses would
likely be relatively minor and brief in nature. Researchers conducting
aerial surveys for walrus in sea ice habitats have observed little
reaction to aircrafts above 1,000 ft (304 m).
In order to limit behavioral reactions of Pacific walrus during
deployment of SISs, helicopters will maintain a minimum altitude of
1,000 ft (304 m) above the sea ice except when taking off or landing.
Sea-ice landings within 1,000 ft (304 m) of any observed walrus will
not occur, and the helicopter flight path will remain along the seismic
track line. Three or four SIS units will be deployed/retrieved before
the helicopter returns to the vessel. This should minimize the number
of disturbances caused by repeated over-flights.
While researching the effects of human disturbances on denning
polar bears, Amstrup (1993) noted that repeated overflights and the
capture and handling of study animals was likely to seriously disturb
the bears. In addition, the effects of fleeing from aircraft on a warm
spring or summer day may be enough to overheat a well-insulated polar
bear. Nonetheless, the studied female's cubs were not smaller and did
not suffer decreased recruitment (Amstrup 1993). Aerial surveyors
observed 24 polar bears while monitoring marine mammals during BP's
Northstar oil development project. One polar bear was sitting on the
ice, 6 were looking at the aircraft, 3 were walking, and 14 were
running. The surveyors concluded that the running or walking bears had
been displaced from a small area and that the bears were not impacted
over the long term (Moulton and Williams 2003). Recurring aircraft
overflights could result in short-term behavioral disturbances to polar
bears. However, reactions will vary among individuals and are not
likely to be significant to the individual.
Repeated overflights of any individual polar bear during the
helicopter operations are unlikely with the monitoring provisions that
are in place. Any reaction to the helicopter work is expected to be
limited and of no consequence to the fitness or health of individual
animals. However, in order to further limit any potential behavioral
reactions of polar bears, the same requirements applied for helicopter
operations around observed walrus will be applied to those operations
when polar bears are sighted.

Effects of Coring Activities

The sediment coring project to be conducted in the Arctic Ocean
north of the Chukchi Sea will have no effect on walrus, because it will
not encounter walrus. Walrus do not occur in the areas of the coring
project, which are far north of the southern edge of the pack ice. The
coring project may encounter a few individual polar bears. The effects
of the coring activities on any bears that are encountered would be
minimal, consisting of temporary disturbance. The presence of humans
and the nature of the activity would likely prevent any encounters
because individual bears are expected to alter their course to avoid
the coring activity due to unfamiliar scents and noises.

Mitigation

Several important mitigation measures have been built into the
design of the project. The UTIG has stated that these mitigation
measures will be implemented to avoid or minimize effects on Pacific
walrus and polar bear encountered along the tracklines.
(1) No seismic surveys will take place in the Chukchi Sea before
July 15, 2006.
(2) Airgun operations will be limited to offshore waters, i.e.,
greater than 120 km (93 miles) from shore;
(3) When operating in shallower parts (less than 100 m) of the
study area, airgun operations will be limited to the smaller source (4
GI guns);
(4) Seismic vessels must observe a 0.5-mile (800-m) exclusion zone
around walrus and polar bears observed on land or ice when not
conducting seismic operations.
(5) Trained vessel-based observers will be required onboard to
monitor marine mammals near the seismic source vessel during all airgun
operations. When marine mammals are observed within, or about to enter,
designated safety radius (i.e., the distance from the sound source at
which the received level of sound would correspond to the acoustic
threshold of 190 dB at any given depth), airgun operations will be
powered down (or shut-down, if necessary) immediately. Vessel-based
observers will watch for walrus and polar bears near the seismic vessel
during all periods of shooting and for a minimum of 30 minutes prior to
the planned start of airgun operations after an extended shut-down.
(6) If a Pacific walrus or polar bear is detected outside the
safety radius and, based on its position and the relative motion, is
likely to enter the safety radius, 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 animal's
activities and movements relative to the seismic vessel will be closely
monitored to ensure that it does not approach within the safety radius.
If the animal appears likely to enter the safety radius, further
mitigative actions will be taken, i.e., either further course
alterations, or power-down or shut-down of the airgun(s).
(7) A power-down involves decreasing the number of airguns in use
such that the radius of the 190-dB zone is decreased to the extent that
marine mammals are no longer within the safety radius. A power-down may
also occur when the vessel is moving from one seismic line to another.
During a power-down, one airgun (or some other number of airguns less
than the full airgun array) is operated. The continued operation of one
airgun will alert marine mammals to the presence of the seismic vessel
in the area.
If a Pacific walrus or polar bear is detected outside the safety
radius but is likely to enter the safety radius, and if the vessel's
speed and/or course cannot be changed to avoid having the mammal enter
the safety radius, the airguns will be powered down before the animal
is within the safety radius. Likewise, if a walrus or polar bear is
already within the safety zone when first detected, the airguns will
immediately be powered down. During a power-down of the 4-or 8-airgun
array, one airgun (either a single 105 in\3\ GI gun or one 210 in\3\ G.
gun, respectively) will be operated. If a Pacific walrus or polar bear
is detected within or near the smaller safety radius around that single
airgun (see Table 1), it will be shut-down. Power-downs will only be
used in deep water. In shallow and intermediate depth water, an
immediate shutdown will occur when Pacific walrus or polar bears are
sighted within the designated safety radii.
(8) The operating airgun(s) will be shut-down completely if a
Pacific walrus or polar bear approaches or enters the safety radius and
a power-down is not practical (or shut-down is specifically prescribed,
see Table 1). The operating airgun(s) will also be shut-down completely
if a walrus or polar bear approaches or enters the estimated safety
radius around the source that would be used during a power-down.
(9) Following a power-down or shut-down, airgun activity will not
resume until the walrus or polar bear has cleared the safety zone. The
animal will be considered to have cleared the safety zone if it is
visually observed to have left the safety zone or has not been seen
within the zone for 15 minutes.
(10) A ramp-up procedure will be followed when the airgun array
begins operating after a specified-duration period without airgun
operations. The

[[Page 35939]]

specified period depends on the speed of the source vessel and the size
of the airgun array that is being used. Ramp-up will begin with one of
the G. guns (210 in\3\) or one of the Bolt airguns (500 in\3\) for the
8-airgun array, or one of the 105 in\3\ GI guns for the 4-GI gun array.
One additional airgun will be added after a period of 5 minutes. Two
more airguns will be added after another 5 minutes, and the last four
airguns (for the 8-airgun array) will all be added after the final 5
minute period. During the ramp-up, the safety zone for the full airgun
array in use at the time will be maintained.
If the complete 190-dB safety radius has not been visible for at
least 30 minutes prior to the start of operations, ramp up will not
commence unless at least one airgun has been operating during the
interruption of seismic survey operations. This means that it will not
be permissible to ramp up the 4-GI gun or 8-airgun source from a
complete shut-down in thick fog or darkness (which may be encountered
briefly in late August), when the outer part of the 190 dB safety zone
is not visible. If the entire safety radius is visible, then start up
of the airguns from a shut-down may occur at night (if any periods of
darkness are encountered during seismic operations). If one airgun has
operated during a power-down period, ramp up to full power will be
permissible in poor visibility, on the assumption that walrus and polar
bears will be alerted to the approaching seismic vessel by the sounds
from the single airgun and could move away. Ramp up of the airguns will
not be initiated during the day or at night if a walrus or polar bear
has been sighted within or near the applicable safety radii during the
previous 15 minutes.
(11) To limit disturbance, helicopters will follow the survey track
line. The UTIG would avoid landing within 1,000 ft (304 m) of an
observed walrus or bear, and maintain a minimum altitude of 1,000 ft
(304 m), unless weather or other circumstances require a closer landing
for human safety. For efficiency, each helicopter excursion will be
scheduled to deploy/retrieve three or four SIS units. This will
minimize the number of flights and the number of potential disturbances
to walrus and polar bears in the area.
(12) The applicant will be required to develop a Service-approved
site-specific polar bear and walrus interaction plan prior to
initiation of activities. These plans outline the contingency steps
that the applicant will take, such as the chain of command for
reporting and responding to polar bear or walrus sightings.
(13) No seismic activities will occur within a 40-mile radius of
affected communities. This condition will limit potential interactions
with walrus hunters in near-shore environments.
(14) Prior to seismic activities, UTIG will contact and consult
with the communities of Point Hope, Point Lay, Wainwright, and Barrow
to identify any necessary measures to be taken to minimize adverse
impacts to subsistence hunters in these communities. A POC will be
developed if there is concern from the community that the activities
will impact subsistence uses of Pacific walrus and polar bears.
The POC must outline how applicants will work with the affected
Native communities and what actions will be taken to avoid interference
with subsistence hunting of walrus and polar bear. The POC will
address: Operational agreement and communications procedures; where and
when the agreement becomes effective; the general communications
scheme; onboard observers; conflict avoidance; seasonally sensitive
areas; vessel navigation; air navigation; marine mammal monitoring
activities; measures to avoid impacts to marine mammals; measures to
avoid conflicts in areas of active hunting; emergency assistance; and
the dispute resolution process. The Service will review the POC prior
to issuance of the final IHA to ensure any potential adverse effects on
the availability of the animals are minimized.
(15) At least one Alaska Native knowledgeable about the mammals and
fish of the area will be a member of the observer team and will serve
as a liaison with subsistence users encountered at sea. Air gun
operations will be suspended if the Healy's trackline is less than 5 km
(3 miles) from ongoing subsistence hunting or fishing activities.

Estimated Take by Incidental Harassment Due to Chukchi Sea Seismic Survey

All anticipated takes would be non-lethal harassment involving
temporary changes in behavior. In the sections below, we estimate take
by harassment of the numbers of walrus and polar bears that are likely
to be affected during the proposed seismic study in the Chukchi Sea
with the implementation of the mitigation measures described above. The
estimates are based on data obtained during marine mammal surveys in
and near the Chukchi Sea by Brueggeman et al. (1990) and Evans et al.
(2003).
This section provides estimates of the number of potential
exposures to sound levels greater than or equal to 160 dB and 170 dB re
1 [mu]pa (rms). The 160 dB criterion is applied as a maximum estimate
for both species, and the 170 dB criterion is applied as a more
accurate criterion based on studies that have determined pinnipeds tend
to be less responsive than many other marine mammal species. As a
conservative measure, this sound level criteria is also applied to
polar bears.
The following estimates are based on a consideration of the number
of walrus and polar bears that might be disturbed appreciably by
approximately 478 line kilometers of seismic surveys in the Chukchi
Sea. An assumed total of 598 km of trackline includes a 25 percent
allowance over and above the planned 478 km to allow for turns, lines
that might have to be repeated because of poor data quality, or minor
changes to the survey design.
The anticipated radii of influence of the bathymetric sonar and
sub-bottom profiler are less than those for the airgun configurations.
It is assumed that, during simultaneous operations of the airgun array,
sonar, and profiler, any walrus or polar bear close enough to be
affected by the sonars would already be affected by the airguns.
However, whether or not the airguns are operating simultaneously with
the sonar or with the profiler, walrus and polar bears are expected to
exhibit no more than short-term and inconsequential responses to the
sonar or profiler given their characteristics (e.g., narrow downward-
directed beam) and other considerations described above. Such reactions
are not considered to constitute taking and, therefore, no additional
allowance is included for animals that might be affected by the sound
sources other than the airguns.
Few surveys of walrus and polar bears have been conducted in the
Chukchi Sea area of the proposed project. The best polar bear density
data are from one pilot study in the eastern Chukchi Sea testing the
viability of aerial surveys from an icebreaker as a tool for monitoring
polar bear stock (Evans et al. 2003). Most of the survey (90.7 percent)
was flown over areas of ice cover greater than 10 percent. The density
of bears was calculated to be 0.0068/km\2\. It is expected that the
density estimate is greater than that which may be encountered in the
Chukchi Sea in open water. In recent years, many polar bears have
concentrated near bowhead harvesting sites on land during late summer
and would, therefore, not be affected by the proposed seismic survey.
Polar bears are not expected to be encountered in areas of open water
(Haley and Ireland 2006, Harwood et al.

[[Page 35940]]

2005, Evans et al. 2003), but an estimated density of 0.0001 has been
used to allow for the chance encounter of a few individuals traversing
open water areas (Monnett et al. 2005).
The estimates of walrus densities most relevant to the proposed
project are reported by Brueggeman et al. (1990) from seven aerial
surveys of ice pack areas occurring in late June through early July.
These surveys took place in the Chukchi Sea area of the proposed Healy
trackline in optimal ice habitat for walrus, and near the center of the
northern migration concentration of the summer population of Chukchi
walrus. Brueggeman et al. (1990) reported an average density in open
water near the ice margin of 0.0731 walrus/km\2\. This value was used
as the average density for walrus in open water during the proposed
survey. Brueggeman et al. (1990) reported a walrus density along the
pack ice edge of 0.62 walrus/km\2\. This value was considered to be the
maximum density of walrus that will be encountered as the Healy crosses
the ice margin in the Chukchi Sea. Pacific walrus most frequently feed
in shallow waters (less than 60 to 80 m) (Chadwick and Hills 2005;
Reeves et al. 2002), and the deepest recorded walrus dive was to 133 m
(Reeves et al. 2002). Because of these reasons, walrus densities have
only been applied to areas along the seisimic survey line that are less
than 200 m deep.
The potential number of occasions when walrus and polar bears
species might be exposed to received levels 160 dB re 1 [mu]Pa (rms)
was calculated for each of three water depth categories (less than 100
m, 100 to 1,000 m, and greater than 1,000 m) within the Chukchi Sea
(south of 75[deg] N) by multiplying:

the expected species density, either average (i.e., best estimate) or
maximum; the anticipated line-kilometers of operations with both the 4-
GI and 8-airgun array in each water-depth category after applying a 25
percent allowance for possible additional line kilometers;
the cross-track distances within which received sound levels are
predicted to be greater than or equal to 160 dB for each water-depth
category.

During the Chukchi Sea portion of the survey, 1,931 km\2\ would be
ensonified within the 170 dB isopleths and 6,455 km\2\ would be
ensonified within the 160 dB isopleths. After adding the 25 percent
contingency to the expected number of line kilometers, the number of
exposures is calculated based on 2,414 km\2\ for the 170 dB sound level
and 8,069 for the 160 dB sound level. The numbers of exposures in the
three depth categories were then summed for each species (Table 2).

Table 2.--Estimates of the Possible Numbers of Walrus and Polar Bear Exposures to 160 dB and 170 dB during
UTIG's Proposed Seismic Program in the Chukchi Sea, Alaska
----------------------------------------------------------------------------------------------------------------
Number of exposures to sound levels
-----------------------------------------------
Species Best estimate Maximum estimate
-----------------------------------------------
>160 dB >170 dB >160 dB >170 dB
----------------------------------------------------------------------------------------------------------------
Walrus.......................................................... 470 143 3,960 1,203
Polar bear...................................................... 8 2 55 16
----------------------------------------------------------------------------------------------------------------

Unlike polar bears, whose best and maximum density estimates were
multiplied by the entire trackline within the Chukchi Sea survey area
to estimate exposures, walrus densities were only multiplied by the
proposed seismic trackline in water depths less than 200 m in the
Chukchi Sea survey area. Walrus are known to occur offshore but
generally remain in waters less than 200 m deep and mostly along the
pack ice margin where ice concentrations are less than 80 percent (Fay
1982; Fay and Burns 1988). The location of the ice edge has shown a
high degree of interannual variation, but is rarely found north of
75[deg] N. Calculating exposures of walrus along the entire
southwestern seismic trackline south of 75[deg] N should somewhat
overestimate the number of exposures since concentrations of walrus are
only likely to be at the proposed densities for a short distance at the
margin of the ice pack.
Based on this method, the best and maximum estimates of the numbers
of Pacific walrus and polar bears exposures to airgun sounds with
received levels greater than or equal to 160 dB re 1 [mu]Pa (rms) were
obtained using the average and maximum densities described above and
are presented in Table 2.
Based upon information supplied by the applicant, the impact of
conducting the seismic survey in the Chukchi Sea it is likely to result
in the temporary modification in behavior (Level B Harassment) of up to
143 Pacific walrus and 2 polar bears. The walrus may be exposed to
airgun sounds at received levels greater than or equal to 160 dB re 1
[mu]Pa (rms) during the seismic survey. It is probable that only a
small percentage of those would actually be disturbed.
For polar bears that may be encountered during the survey, almost
all of these are expected to be on the ice, and therefore unaffected by
underwater sound from the airguns. For the few bears that are in the
water, levels of airgun and sonar sound would be attenuated because
polar bears generally do not dive much below the surface. Bears on the
ice may be impacted by short-term displacements as the vessel traverses
the area near the bear.
In addition, we note that the coring project activities to be
conducted to the north of the Chukchi Sea in the Arctic Ocean will
cause no take of Pacific walrus because no walrus will be encountered
that far north. There is a possibility that a few individual polar
bears will be encountered; however, any potential disturbance would be
limited to temporary behavior changes and does not affect the take
estimate for polar bear.
Although current population estimates for the Pacific walrus
population and Chukchi Sea polar bear stocks are not available, the
best available information indicates that the number of potentially
affected animals is small. Furthermore, any impacts to individuals are
expected to be relatively short term in duration, are anticipated to be
minor behavioral reactions, and are not expected to impact animal
health or reproduction.
In 2005, the Healy conducted similar research that began in the
same region, but continued across the Arctic Basin to Norway (Haley and
Ireland 2006). During the 2005 cruise, seven live walrus were
encountered in the Bering Sea. No walrus were encountered in the
northern Chukchi Sea (B. Haley, LGL Alaska Research Associates, Inc.,
pers. comm.). In addition, a total of 24 polar

[[Page 35941]]

bears were visually recorded and the Service considers all observations
to be takes. Three separate groups consisting of 5 bears were observed
north of the Alaska coast between 74[deg] and 79[deg] N latitude. These
bears were most likely from the southern Beaufort Sea or Chukchi/Bering
Seas polar bear stocks. The remainder of the bears were observed near
Svalbard and Franz Joseph Land. These bears most likely belonged to the
Svalbard and Franz Joseph-Novaya Zemlya polar bear stocks. The takes
for both species during the 2005 cruise through the Chukchi Sea
appeared to be limited to Level B harassment of a relatively small
number of animals and of relatively a short-term duration.

Potential Effects on Habitat

The proposed airgun operations will not result in any permanent
impact on habitats used by Pacific walrus or polar bears, or to the
food sources they utilize. The main impact associated with the proposed
activities will be temporarily elevated noise levels and the associated
direct effects.
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 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 in Wardle et al. 2001).
Generally, the higher the received pressure and the less time it takes
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.
During the seismic study only a small fraction of the available
habitat would be ensonified at any given time. Disturbance to benthic
invertebrates, fish, and marine mammals would be short term, and they
would return to their pre-disturbance behavior once the seismic
activity passes or otherwise ceases. Thus, the proposed survey would
have little effect on these prey items and, therefore, little, if any,
impact on the abilities of walrus and polar bears to feed in the area
where seismic work is planned. In addition, the proposed activity is
not expected to have any habitat-related effects that could cause
significant or long-term consequences for prey species or for
individual walrus or polar bears or their populations, since operations
at any one location will be limited in duration.

Potential Impacts on Subsistence Needs

Subsistence hunting and fishing continue to be prominent in the
household economies and social welfare of some Alaskan residents,
particularly among those living in small, rural villages (Wolfe and
Walker 1987). 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.
Pacific walrus and polar bear are legally hunted in the Chukchi Sea
by coastal Alaska Natives. For thousands of years, hunting has been an
important source of food and raw materials for equipment and
handicrafts. Today, hunting remains an important part of the culture
and economy of many coastal villages in Alaska. Rural communities in
the vicinity of the proposed Chukchi Sea seismic survey area include
Point Hope, Point Lay, Wainwright, and Barrow.
Any activity that displaces Pacific walrus beyond the range of
coastal hunters has the potential to adversely impact subsistence
harvests in these communities. Walrus hunting may occur anywhere along
the Chukchi Sea coastline from Cape Lisburne to Point Barrow. Walrus
hunting by these communities is generally limited to conditions when
sea ice occurs within the range of small hunting boats, typically less
than 48 km (30 mi) from shore.
Point Hope hunters typically begin their hunt in late May and June
as walrus migrate north. The sea ice is usually well off shore of Point
Hope by July and does not bring animals back into the range of hunters
until late August and September. Between 2000 and 2004, the average
annual reported harvest at Point Hope was 11 animals per year.
Walrus hunting in Point Lay occurs primarily in July. Point Lay
hunters reported an average of six walrus per year between 2000 and 2004.
Wainwright residents hunt walrus from June through August as the
ice retreats northward. Walrus are plentiful in the pack ice near the
village this time of year. Wainwright hunters have consistently
harvested more walrus than other subsistence communities; the village
averaged 62 animals per year for 2000 through 2004.
In Barrow, most walrus hunting occurs from June through September,
peaking in August, when the land-fast ice breaks up and hunters can
access the walrus by boat as they migrate north on the retreating pack
ice. The average annual walrus harvest for Barrow from 2000 to 2004 was
32 animals.
Although it is possible that accessibility to walrus for
subsistence harvest could be impacted during the seismic surveys, it is
unlikely. The majority of Pacific walrus are taken less than 48 km (30
mi) from shore, and the Healy will conduct its survey operations
significantly farther offshore, i.e., approximately 150 km (93 mi) to
200 km (124 mi) offshore. In addition, the applicant will implement
necessary mitigation measures as described above to further minimize or
avoid any potential impact.
Depending upon ice conditions, the subsistence harvest of polar
bears can occur year-round in the northern Chukchi Sea villages, with
peaks in the spring and winter. The period with the lowest harvest of
bears occurs in June and July. Hunting success varies considerably from
year to year because of variable ice and weather conditions.
For Point Hope, the average annual reported harvest between 2000
and 2004 was eight polar bears. The average for Point Lay during this
same time period was less than one bear per year. In Wainwright, the
average was four bears per year from 2000 through 2004. And, in Barrow,
the average annual polar bear harvest from 2000 to 2004 was 16 animals.
Disruption of polar bear subsistence hunting is not expected
because the timing of polar bear hunting occurs primarily during the
winter and spring when pack ice is present nearshore and the seismic
surveys will take place during the summer and fall open-water seasons.
Furthermore, the applicant will implement necessary mitigation measures
as described above to insure any potential impact is minimized or avoided.
The harvest information provided for Pacific walrus and polar bears
is based on reports provided through the Service's Marking, Tagging,
and Reporting Program. Harvest data for 2005 is not presently
available. Harvest totals are not corrected for struck and lost animals.

[[Page 35942]]

Basis for Findings

Negligible Impact on Species

The Service has determined that the seismic survey in the Chukchi
Sea will cause a temporary modification in behavior of small numbers of
Pacific walrus and polar bears. Based upon information supplied by the
applicant, the seismic survey in the Chukchi Sea could potentially
result in the temporary modification in behavior of up to 143 Pacific
walrus and 2 polar bears. Any impacts to individuals are expected to be
limited to Level B harassment and short term in duration. The potential
for temporary or permanent hearing impairment is very low and any
potential for hearing impairment will be avoided through the
incorporation of the proposed mitigation measures mentioned in this
document. We also considered the sediment coring projects potential
effect on walrus and polar bears in making the negligible impact
finding. Because the coring project will not affect the estimated take
of the overall survey, it does not affect the negligible impact
finding. No take by injury or death is anticipated. The Service finds
that the anticipated harassment caused by the proposed activities are
not expected to adversely affect the species or stock through effects
on annual rate of recruitment or survival and, therefore, will have a
negligible impact on Pacific walrus and polar bears.
Our finding of negligible impact is based on the total level of
activity proposed by UTIG and the Service's analysis of the effects of
all activities. In making this finding, we considered the following:
(1) The distribution of the species; (2) the biological characteristics
of the species; (3) the nature of seismic survey program; (4) the
potential effects of seismic activities on the species; (5) the
documented impacts of seismic activities on the species; and (6) the
mitigation measures that will be conditions of the authorization.
Although Pacific walrus are expected to occur in the area of the
proposed seismic surveys, the surveys would not be concentrated in any
location for extended periods. Most of the proposed activities would
occur in areas of open water where walrus densities are expected to be
relatively low. In addition, mitigation measures will be followed when
walrus are observed within the safety radius.
The number of polar bears present in the open water of the Chukchi
Sea during the time of the seismic surveys will also be minimal.
Individual polar bears may be observed in the open water during seismic
activities, but the majority of the population will be found on the
pack ice during this time of year. If polar bears are observed in the
area prior to, or even during, seismic surveys, appropriate mitigation
measures will be followed.
Based on our review of these factors, we conclude that, while
incidental harassment of polar bears and walrus is reasonably likely to
or reasonably expected to occur as a result of proposed seismic
surveys, the overall impact would be negligible on polar bear and
Pacific walrus populations. In addition, we find that any takes are
likely to be limited to Level B harassment of a relatively small number
of animals and of relatively a short-term duration. Furthermore, we do
not expect the anticipated level of harassment from these proposed
activities to affect the rates of recruitment or survival of Pacific
walrus and polar bear populations.
While the actual number of incidental harassment takes will depend
on the distribution and abundance of Pacific walrus and polar bears in
the vicinity of the survey activity, the number of harassment takings
will be small. Furthermore, the previously mentioned mitigation
measures that will be implemented by the applicant insures these
measures will provide additional means of effecting the least level
practicable impact on Pacific walrus and polar bears.

Impact on Subsistence

Based on the results of harvest data, including affected villages,
the number of animals harvested, the season of the harvests, and the
location of hunting areas, we find that the anticipated harassment
caused by the proposed seismic surveys will not have an unmitigable
adverse impact on the availability of Pacific walrus and polar bears
for taking for subsistence uses during the period of the activities. In
making this finding, we considered the following: (1) Records on
subsistence harvest from the Service's Marking, Tagging, and Reporting
Program (historical data regarding the timing and location of
harvests); (2) anticipated effects of UTIG's proposed activities on
subsistence hunting; (3) development of Plans of Cooperation between
the applicants and affected Native communities, as appropriate; (4)
reliance on an Alaska Native to serve as a liaison with subsistence
users encountered at sea; and (5) and suspending air gun operations
when the Healy's trackline is less than 5 km (3 miles) from ongoing
subsistence hunting or fishing activities.
Most subsistence walrus hunting occurs less than 48 km (30 mi) from
shore. Although walrus hunters may encounter vessels and aircraft in
open-water areas, these interactions are expected to be limited in area
and duration and are not expected to affect overall hunting success.
Only a small fraction of the polar bear harvest occurs during the
open-water season. In addition, most polar bears are harvested outside
of the area that would be covered by this authorization. Because the
polar bear is hunted almost entirely during the ice-covered season, it
is unlikely that open-water seismic activities would have any effect on
the harvest of that species.
In addition, helicopter operations will occur far offshore where
the seismic operations take place in the ice-pack. Thus any reaction of
walrus or polar bears to the helicopter operations will have no effect
on their availability for subsistence. These helicopter operations will
be conducted in a manner that will minimize effects on walrus and polar
bears.
Finally, UTIG will develop a POC for the proposed 2006 seismic
survey in the Chukchi Sea, as appropriate, in consultation with
representatives of communities along the Chukchi Sea coast including
Point Hope, Point Lay, Wainwright, and Barrow.

Monitoring

The UTIG will conduct marine mammal monitoring during the seismic
surveys, in order to implement the mitigation measures that require
real-time monitoring, and to satisfy monitoring called for under the MMPA.
Vessel-based observers will monitor Pacific walrus and polar bears
near the seismic source vessel during all seismic operations. There
will be little or no darkness during this cruise. Airgun operations
will be shut-down when Pacific walrus or polar bears are observed
within, or about to enter, designated safety radii. Vessel-based
observers will also watch for Pacific walrus and polar bears near the
seismic vessel for at least 30 minutes 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 and during coring operations).
During seismic operations in the Chukchi Sea, four observers will
be based aboard the vessel. These observers will be appointed by UTIG
with Service concurrence. An Alaska native resident knowledgeable about
the mammals and fish of the area is expected to be included as one of
the team of observers

[[Page 35943]]

aboard the Healy. At least one observer, and when practical, two
observers, will monitor Pacific walrus and polar bears near the seismic
vessel during ongoing operations and nighttime startups (if darkness is
encountered in late August). Observers will normally be on duty in
shifts of duration no longer than 4 hours. The USCG crew will also be
instructed to assist in detecting Pacific walrus and polar bears and
implementing mitigation requirements (if practical). The necessary
instructions will be provided to the crew prior to the start of the
seismic survey.
The Healy is a suitable platform for marine mammal observations.
When stationed on the flying bridge, the eye level will be
approximately 27.7 m (91 ft) above sea level, and the observer will
have an unobstructed view around the entire vessel. If surveying from
the bridge, the observer's eye level will be 19.5 m (64 ft) above sea
level and approximately 25[deg] of the view will be partially
obstructed directly to the stern by the stack (Haley and Ireland 2006).
The observers will scan the area around the vessel systematically with
reticle binoculars (e.g., 7 x 50 Fujinon), Big-eye binoculars (25 x
150), and with the naked eye. During any periods of darkness (minimal,
if at all, in this cruise), NVDs will be available (ITT F500 Series
Generation 3 binocular-image intensifier or equivalent), if and when
required. The survey will take place at high latitude in the summer
when there will be continuous daylight, but night (darkness) is likely
to be encountered briefly at the southernmost extent of the survey in
late August. Laser rangefinding binoculars (Leica LRF 1200 laser
rangefinder or equivalent) will be available to assist with distance
estimation; these are useful in training observers to estimate
distances visually, but are generally not useful in measuring distances
to animals directly.
When walrus or polar bears are detected within, or are about to
enter, the designated safety radius, the airgun(s) will be powered down
or shut-down immediately. To assure prompt implementation of shut-
downs, additional channels of communication between the observers and
the airgun technicians will be established. During power-downs and
shut-downs, the observers will continue to maintain watch to determine
when the animal(s) are outside the safety radius. Airgun operations
will not resume until the animal is outside the safety radius. The
animal will be considered to have cleared the safety radius if it is
visually observed to have left the safety radius, or if it has not been
seen within the radius for 15 minutes.
All observations and airgun power or shut-downs will be recorded in
a standardized format. Data will be entered into a custom database
using a notebook computer. The accuracy of the data entry will be
verified by computerized validity data 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, or other programs for further processing and
archiving. Results from the vessel-based observations will provide:
(1) The basis for real-time mitigation (airgun power or shut-down).
(2) Information needed to estimate the number of Pacific walrus and
polar bears potentially taken by harassment, which must be reported to FWS.
(3) Data on the occurrence, distribution, and activities of Pacific
walrus and polar bears in the area where the seismic study is conducted.
(4) Information to compare the distance and distribution of Pacific
walrus and polar bears relative to the source vessel at times with and
without seismic activity.
(5) Data on the behavior and movement patterns of Pacific walrus
and polar bears seen at times with and without seismic activity.
Development and participation in a cooperative research program is
not a requirement for obtaining an IHA. However, the Service encourages
research of walrus and polar bear, such as projects funded and
supported by the National Fish and Wildlife Foundation. The UTIG stated
it will coordinate the planned marine mammal monitoring program
associated with the seismic survey in the Chukchi Sea with other
parties that may have interest in this area and/or be conducting marine
mammal studies in the same region during operations. This type of
coordination could provide additional insight into the relationship
between seismic activities and the basic biological requirements of the
two species of concern. The UTIG will also coordinate with other
applicable Federal, State, and Borough agencies, and will comply with
their requirements.

Reporting

Polar bear and walrus observation forms will be provided by the
Service to the applicant. Any walrus or polar bear sighting that occurs
during the seismic surveys must be submitted to the Service within 24
hours of the animal sighting or as soon as practicable. A report must
be submitted to the Service within 90 days after the end of the cruise.
The report will describe the operations that were conducted and the
walrus and polar bears that were detected near the operations. The
report will be submitted to the Service, providing full documentation
of methods, results, and interpretation pertaining to all monitoring.
The 90-day report will summarize the dates and locations of seismic
operations, and all walrus and polar bear sightings (dates, times,
locations, activities, associated seismic survey activities). The
report will also include estimates of the level and type of take,
numbers of walrus and polar bears observed, direction of movement of
observed individuals, and any observed changes or modifications in
behavior or travel direction resulting from the seismic surveys.

Proposed Authorization

The Service proposes to issue an IHA for small numbers of Pacific
walrus and polar bears harassed incidentally by UTIG while conducting
marine seismic surveys in the Arctic Ocean from July 15 through August
25, 2006. The purpose of the surveys is to collect seismic reflection
and refraction data in the western Amerasia Basin in the Arctic Ocean.
The final IHA would incorporate the mitigation, monitoring, and
reporting requirements discussed in this proposal. The UTIG will be
responsible for following those requirements. All activities would be
conducted during the 2006 open-water season. Authorization for the
seismic surveys would be for approximately 40 days. These
authorizations do not allow the intentional taking of polar bear or
Pacific walrus.
If the level of activity exceeds that described by the UTIG, or the
level or nature of take exceeds those projected here, the Service would
reevaluate its findings. The Secretary may modify, suspend, or revoke
an authorization if the findings are not accurate or the conditions
described herein are not being met.

Endangered Species Act

The Service has determined that no species under its jurisdiction
listed as threatened or endangered under the Endangered Species Act of
1973, as amended, would be affected by issuing an IHA under section
101(a)(5)(D) of the MMPA to the applicants for the proposed open-water
seismic surveys.

[[Page 35944]]

National Environmental Policy Act (NEPA)

The applicant provided a Draft Environmental Assessment (EA) of a
Marine Geophysical Survey by the USCG Healy of the Western Canada
Basin, Chukchi Borderland and Mendeleev Ridge, Arctic Ocean, July-
August 2006, prepared by LGL Alaska Research Associates, Inc. of
Anchorage, Alaska and LGL Ltd., environmental research associates of
King City, Ontario dated March 1, 2006. The Service has adopted this
draft EA as the foundation of the Service's EA and finds that it meets
NEPA standards for analyzing the effects of the issuance of this IHA.
For a copy of the EA, contact the individual identified under FOR
FURTHER INFORMATION CONTACT.

Government-to-Government Relations With Native American Tribal Governments

In accordance with the President's memorandum of April 29, 1994,
``Government-to-Government Relations with Native American Tribal
Governments'' (59 FR 22951), Executive Order 13175, Secretarial Order
3225, and the Department of the Interior's manual at 512 DM 2, we
readily acknowledge our responsibility to communicate meaningfully with
federally recognized Tribes on a Government-to-Government basis. We
have evaluated possible effects on federally recognized Alaska Native
tribes. Through the POC identified above, applicants will work with the
Native Communities most likely to be affected and will take actions to
avoid interference with subsistence hunting.

Public Comments Solicited

The Service requests interested persons to submit comments and
information concerning this proposed IHA. Consistent with section
101(a)(5)(D)(iii) of the MMPA, we are opening the comment period on
this proposed authorization for 30 days (see DATES).
Our practice is to make comments, including names and home
addresses of respondents, available for public review during regular
business hours. Individual respondents may request that we withhold
their home address from the record, which we will honor to the extent
allowable by law. If you wish us to withhold your name and/or address,
you must state that prominently at the beginning of your comment.
However, we will not consider anonymous comments. We will make all
submissions from organizations or businesses, and from individuals
identifying themselves as representatives or officials of organizations
or businesses, available for public inspection in their entirety.

Dated: June 15, 2006.
Tom Melius,
Regional Director.
[FR Doc. 06-5589 Filed 6-21-06; 8:45 am]
BILLING CODE 4310-55-P

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