Small Takes of Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey Across the Arctic Ocean

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

[Federal Register: August 15, 2005 (Volume 70, Number 156)]
[Notices]
[Page 47792-47809]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr15au05-30]

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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[I.D. 040505A]

Small Takes of Marine Mammals Incidental to Specified Activities;
Marine Geophysical Survey Across the Arctic Ocean

AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
[[Page 47793]]
ACTION: Notice; issuance of incidental harassment authorization.

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SUMMARY: In accordance with the provisions of the Marine Mammal
Protection Act (MMPA) as amended, notification is hereby given that
NMFS has issued an Incidental Harassment Authorization (IHA) to the
University of Alaska, Fairbanks (UAF) to take marine mammals by Level B
harassment incidental to conducting a marine seismic survey across the
Arctic Ocean from northern Alaska to Svalbard.

DATES: Effective from August 5, 2005, through August 4, 2006

ADDRESSES: A copy of the IHA and the application are available by
writing to Steve Leathery, Chief, Permits, Conservation, and Education
Division, Office of Protected Resources, National Marine Fisheries
Service, 1315 East-West Highway, Silver Spring, MD 20910-3225, or by
telephoning the contact listed here. A copy of the application
containing a list of references used in this document may be obtained
by writing to this address, by telephoning the contact listed here (see
FOR FURTHER INFORMATION CONTACT) or online at: http://www.nmfs.noaa.gov/
prot_res/PR2/Small_Take/smalltake_info.htmapplications.
Documents cited in this notice may be viewed, by appointment, during
regular business hours, at the aforementioned address.

FOR FURTHER INFORMATION CONTACT: Jolie Harrison, Office of Protected
Resources, NMFS, (301) 713-2289, ext 166.

SUPPLEMENTARY INFORMATION:

Background

Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.)
direct the Secretary of Commerce to allow, upon request, the
incidental, but not intentional taking of small numbers of marine
mammals by U.S. citizens who engage in a specified activity (other than
commercial fishing) within a specified geographical region if certain
findings are made and either regulations are issued or, if the taking
is limited to harassment, notice of a proposed authorization is
provided to the public for review.
Authorization for incidental takings may be granted if NMFS finds
that the taking will have no more than a negligible impact on the
species or stock(s), will not have an unmitigable adverse impact on the
availability of the species or stock(s) for subsistence uses, and that
the permissible methods of taking and requirements pertaining to the
monitoring and reporting of such taking are set forth.
NMFS has defined ``negligible impact'' in 50 CFR 216.103 as:
an impact resulting from the specified activity that cannot be
reasonably expected to, and is not reasonably likely to, adversely
affect the species or stock through effects on annual rates of
recruitment or survival.
Subsection 101(a)(5)(D) of the MMPA established an expedited
process by which citizens of the United States can apply for an
authorization to incidentally take small numbers of marine mammals by
harassment. Except for certain categories of activities not pertinent
here, the MMPA defines ``harassment'' as:
any act of pursuit, torment, or annoyance which (i) has the
potential to injure a marine mammal or marine mammal stock in the
wild [``Level A harassment'']; or (ii) has the potential to disturb
a marine mammal or marine mammal stock in the wild by causing
disruption of behavioral patterns, including, but not limited to,
migration, breathing, nursing, breeding, feeding, or sheltering
[``Level B harassment''].
Section 101(a)(5)(D) establishes a 45-day time limit for NMFS
review of an application followed by a 30-day public notice and comment
period on any proposed authorization for the incidental harassment of
small numbers of marine mammals. Within 45 days of the close of the
comment period, NMFS must either issue or deny issuance of the
authorization.

Summary of Request

On March 30, 2005, NMFS received an application from UAF for the
taking, by harassment, of several species of marine mammals incidental
to conducting, with research funding from the National Science
Foundation (NSF) and the Norwegian Petroleum Directorate (NPD), a
marine seismic survey across the Arctic Ocean from northern Alaska to
Svalbard during the period 5 August to 30 September 2005. The purpose
of the proposed seismic study is to collect seismic reflection and
refraction data that reveal the structure and stratigraphy of the upper
crust of the Arctic Ocean. These data will assist in the determination
of the history of ridges and plateaus that subdivide the Amerasian
basin in the Arctic Ocean. Past studies have mapped the bottom of the
Arctic Ocean, but data are needed to describe the boundaries and
connections between the ridges and plateaus in the Amerasian basin and
to study the stratigraphy of the smaller basins. This information will
assist in preparing for future scientific drilling that is crucial to
reconstructing the tectonic, magmatic, and paleoclimatic history of the
Amerasian basin.
Subsequent to the Federal Register notice announcing NMFS' receipt
of UAF's application (70 FR 24539, May 10, 2005), minor changes were
made to the proposed action. These changes are documented in detail in
the NMFS administrative record, are included in the Specified
Activities below, and are summarized here: (1) the seismic survey will
commence more than 125 mi (201 km) northwest of the coast of Barrow,
instead of approximately 25 mi (40 km) off the coast of Barrow, AK,
which means that none of the survey will be conducted in waters less
than 100-meters deep, and (2) UAF has added a passive acoustic
monitoring component to the project (to gather additional information,
not as part of mitigation implementation), wherein marine mammal
observers (MMOs) will be able to listen to, and visually analyze,
marine mammal signals received by sonobuoys deployed every four hours.
As a result of the seismic survey track amendments, adverse impacts to
all species addressed in the EA will be equal to or less than those
predicted in the original EA, with the possible exception of walruses.
In summer, potential walrus numbers along the new track are very
difficult to predict because they are distributed patchily, depending
on the ice pack distribution, which is very unpredictable. Regardless
of numbers, though, if the ship encounters walruses, it will implement
the same mitigation measures to avoid take as for other marine mammals
and suspend seismic operations until the vessel has traveled well past
the animals.

Description of the Activity

The geophysical survey will involve the United States Coast Guard
(USCG) cutter Healy. The Healy will rendezvous with the Swedish
icebreaker Oden near Alpha Ridge. The Oden will be working on a
separate project, conducting an oceanographic section across the Arctic
Ocean basin and will coordinate its timing to meet the Healy. The Oden
will cut a path through the ice as necessary, leading the Healy for the
remainder of the trans-ocean track past the North Pole and then on
towards Svalbard. The two icebreakers working in tandem will optimize
seismic data collection and safety through the heaviest multi-year ice.
The source vessel, the USCG icebreaker Healy, will use a portable
Multi-Channel Seismic (MCS) system from the University of Bergen to
conduct the seismic survey. The Healy will tow two different airgun
configurations. The primary energy source will be two Generator guns
(G. guns), each with a discharge volume of 250 in\3\ for a total volume
of 500 in\3\. The secondary energy source will be a

[[Page 47794]]

single Bolt airgun of 1200 in\3\ that will be used for deeper
penetration over three ridges (the Alpha, Mendeleev, and Gakkel ridges).
The Healy will also tow a hydrophone streamer 100-150 m (328-492
ft) behind the ship, depending on ice conditions. The hydrophone
streamer will be up to 300 m (984 ft) long. As the airguns are towed
along the survey lines, the receiving system will receive the returning
acoustic signals. In addition to the airguns, a multi-beam sonar and
sub-bottom profiler will be used during the seismic profiling and
continuously when underway.
The program will consist of a total of approximately 4131 km (2230
nautical miles (nm)) of surveys, not including transits when the
airguns are not operating, plus scientific coring at nine locations.
The seismic survey will commence < 200 km (108 nm) off the northwest
coast of Barrow, AK, and the seismic activities will be completed
northwest of Svalbard, in Norwegian territorial waters. Water depths
within the study area are 170 4000 m (66-13123 ft). Approximately 9
percent of the survey will be conducted in water 100 1000-m (328-3280-
ft) deep, and most (91 percent) of the survey (approximately 3759 km
(1976 nm)) will occur in water < 1000-m (3280-ft) deep. Additional
seismic operations will be associated with airgun testing, start up,
and repeat coverage of any areas where initial data quality is sub-
standard.
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 multi-beam 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 12-kHz pinger will be used during
the sea-bottom coring operations to monitor the depth of the corer
relative to the ocean floor. A detailed description of the acoustic
sources proposed for use during this survey can be found in the UAF
application, which is available at: http://www.nmfs.noaa.gov/
prot_res/PR1/Small_Take/smalltake_info.htm#applications.
The coring operations constitute a separate project, which will be
conducted in conjunction with the seismic study from the Healy. Seismic
operations will be suspended while the USCG Healy is on site for coring
at each of nine locations. Depending on water depth and the number of
cores to be collected, the Healy may be at each site for between 8 and
36 hours.

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 (29.2 ft). The Healy is a USCG
icebreaker, capable of traveling at 5.6 km/h (3 knots) through 1.4 m
(4.6 ft) of ice. A ``Central Power Plant'', four Sultzer 12Z AU40S
diesel generators, provides electric power for propulsion and ship's
services through a 60 Hz, 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/h
(3.5 knots). When not towing seismic survey gear or breaking ice, the
Healy cruises at 22 km/h (12 knots) and has a maximum speed of 31.5 km/
h (17 knots). She has a normal operating range of about 29,650 km
(16,000 nm) at 23.2 km/hr (12.5 knots).
The Healy will also serve as the platform from which vessel-based
marine mammal observers will watch for marine mammals before and during
airgun operations. The characteristics of the Healy that make it
suitable for visual monitoring are described in the monitoring section.

Airgun Description and Safety Radii

The University of Bergen's portable MCS system will be installed on
the Healy for this cruise. The Healy will tow either two Sodera 250-
in\3\ G. guns (for a total discharge volume of 500 in\3\) or a single
1200-in3 Bolt airgun, along with a streamer containing hydrophones,
along predetermined lines. Seismic pulses will be emitted at intervals
of 20 seconds (s) and recorded at a 2 millisecond (ms) sampling rate.
The 20 s spacing corresponds to a shot interval of approximately 36 m
(118 ft) at the typical cruise speed.
The two-G. gun-cluster configuration will be towed below a
depressor bird at a depth between 7 and 20 m (23 and 66 ft), as close
to the Healy's stern as possible to minimize ice interference
(preferred depth is 8 to 10 m (26 to 29 ft)). The two airguns will be
towed 1 m (3.3 ft) apart, separated by a spreader bar. The G. guns have
a zero to peak (peak) source output of 236 dB re 1 microPascal-m (6.5
bar-m) and a peak-to-peak (pk-pk) level of 241 dB (11.7 bar-m). The
dominant frequency components of these airguns are in the range of 0-
150 Hz. For a one-gun source, the nominal source level represents the
actual level that would be found about 1 m (3.3 ft) from the airgun.
Actual levels experienced by any marine organism more than 1 m (3.3 ft)
from the airguns will be significantly lower.
The single Bolt airgun will be towed below a depressor bird at a
depth of 10 m (29 ft). This airgun has peak source output of 234 dB re
1 microPascal-m (5 bar-m) and a pk-pk level of 241 dB (11.7 bar-m). The
dominant frequency components of these airguns are in the range of 8-40
Hz. Indicated source outputs are for sources at 5 m (16 ft) and for a
filter bandwidth of approximately 0-250 Hz.
Received sound levels were modeled by Lamont Doherty Earth
Observatory (L-DEO) for single 1200-in\3\ Bolt airguns and for the one
and two 250-in\3\ G. guns in relation to distance and direction from
the gun. This publically available model does not allow for bottom
interactions, and, thus, is most directly applicable to deep water. 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, etc., dB re 1 microPa rms (Tolstoy et
al., 2004a,b). Based on the models, table 1 shows the distances from
the planned sources where sound levels of 190, 180, and 160 dB re 1
microPa root-mean squared (rms) are predicted to be received. 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,
and in NMFS guidelines concerning levels above which ``taking'' might
occur. The rms level of a seismic pulse is typically about 10 dB less
than its peak level (Greene 1997; McCauley et al., 1998, 2000a).

[[Page 47795]]

Table 1. Estimated distances to which sound levels [gteqt]190, 180, and 160 dB re 1 microPa (rms) might be received from the 250-in\3\ G. gun(s) and
1200-in\3\ Bolt airgun that will be used during the seismic survey across the Arctic Ocean during 2005. The sound radii used during the survey will
depend on water depth (see text). Due to revision in survey start point, no surveys will be conducted in < 100 m. Distances are based on model results
provided by the Lamont-Doherty Earth Observatory of Columbia University.
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Estimated Distances at Received Levels (m)
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Seismic Source Volume Water depth 190 dB (safety criterion for 180 dB (safety criterion for 160 dB (assumed onset of
pinnipeds) cetaceans) behavioral harassment)
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250 in\3\ >1000 m 17 52 500
G. gun 100-1000 m 26 78 750
< :100 m 213 385 1364
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500 in\3\ >1000 m 100 325 3300
2 G. guns 100-1000 m 150 500 5000
< 100 m 1500 2400 9700
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1200 in\3\ >1000 m 25 50 560
Bolt 100-1000 m 38 75 840
airgun < 100 m 313 370 1527
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For the two-G. gun source, the highest sound level measurable at
any location in the water would be slightly less than the nominal
source level because the actual source is a distributed source rather
than a point source. However, the two guns would be only 1 m (3.3 ft)
apart, so the non-point-source effect would be slight. For the single
Bolt airgun, the source level represents the actual level that would be
found about 1 m from the energy source. Actual levels experienced by
any organism more than 1 m (3.3 ft) from either of the sources will be
significantly lower.
The rms received levels that are used by NMFS 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, i.e., peak or pk-pk
decibels, are always higher than the rms decibels referred to in much
of the biological literature. A measured received level of 160 decibels
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, 2000a). The precise
difference between rms and peak or pk-pk 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 pk-pk
level for an airgun-type source.
The depth at which the sound 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
relatively deep depths of 7 to 20 m (23 to 66 ft).
Empirical data concerning the 190-, 180-, and 160-dB (rms)
isopleths in deep and shallow water have been acquired for various
airgun configurations based on measurements during the acoustic
verification study conducted by L-DEO in the northern Gulf of Mexico
from 27 May to 3 June 2003 (Tolstoy et al., 2004a, b). Those data
demonstrated that L-DEO's model tends to overestimate the isopleth
distances applied in deep water. During that study, empirical data were
not obtained for either the 1200-in\3\ Bolt airgun or the G. guns that
will be used during this survey. Although the results were limited, the
calibration-study results showed that radii around the airguns where
the received level would be 180 dB re 1 microPa (rms), the safety zone
radius NMFS uses for cetaceans, (NMFS 2000), vary with water depth.
Similar depth-related variation is likely in the 190 dB distances used
for pinnipeds. Although sea turtle sightings are highly unlikely, the
180-dB distance will also be used as the safety radius for sea turtles,
as required by NMFS in another recent seismic project (Smultea et al.,
2005). The safety zones are used to trigger mitigation measures, which
are described below.
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 factor will be applied
to the values predicted by L-DEO's model. Due to UAF's revision of the
survey start In shallow water, larger precautionary factors derived
from the empirical shallow-water measurements would be applied,
however, no seismic will be conducted in shallow water. The proposed
study area will occur mainly in water 1000 to 4000 m (3280 to 13123 ft)
deep, with approximately 9 percent of the survey lines in intermediate
water depths < 100 1000 m (328-3280 ft)), and with no seismic survey
lines in shallow (< 100 m (328 ft)) water, since the application was
revised to start the survey >200 km (108 nm) off the coast of Barrow, AK.
The empirical data indicate that, for deep water (>1000 m (3280
ft)), 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, UAF has
proposed using safety radii during airgun operations in deep water that
correspond to the values predicted by L-DEO's model for deep water
(Table 1). In deep water, the estimated 190 and 180 dB radii for two
250-in\3\G. guns are 100 and 325 m (328 and 1067 ft), respectively.
Those for one 1200-in\3\ Bolt airgun are 25 and 50 m (82 and 164 ft),
respectively.

[[Page 47796]]

Empirical measurements were not conducted for intermediate depths
(100 1000 m (328-3280 ft)). On the expectation that results would be
somewhere between those from shallow and deep water, UAF has applied a
1.5x correction factor 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 estimated 190- and 180-dB radii in
intermediate-depth water are 150 m (490 ft) and 500 m (1640 ft),
respectively, for the two G. gun system and 38 and 75 m (125 and 246
ft), respectively, for the single Bolt airgun (Table 1).
Though no seismic exercises will be conducted in shallow water, the
explanation for the safety ranges in shallow water is included below
because it is cross-referenced elsewhere. Empirical measurements were
not made for the sources that will be employed during the proposed
survey operating in shallow water (< 100 m (328 ft)). The empirical data
on operations of two 105 in\3\ GI guns in shallow water showed that
modeled values underestimated actual levels in shallow water at
corresponding distances of 0.5 to 1.5 km (0.3 to 0.5 nm) by a factor of
approximately 3x (Tolstoy et al., 2004b). Sound level measurements for
the 2 GI guns were not available for distances < 0.5 km (0.3 nm) from
the source. The radii estimated here for two G. guns operating in
shallow water are derived from L-DEO's deep water estimates, with the
same adjustments for depth-related differences in sound propagation
used for 2 GI guns in earlier applications (and approximately the same
factors as used for L-DEO's 10-airgun array). Similarly, the factors
for the single airguns are the same as those for a single GI gun in
earlier applications. Thus, the estimated 190- and 180-dB radii in
shallow water are 1500 and 2400 m (4921 and 7874 ft), respectively, for
the two G. guns (Table 1). The corresponding radii for the single G.
gun in shallow water are estimated to be 213 and 385 m (699 and 1263
ft), respectively. The sound radii for the single Bolt airgun in
shallow water are estimated to be 313 m (1027 ft) for 190 dB and 370 m
(1214 ft) for 180 dB.

Characteristics of Airgun Pulses

Discussion of the characteristics of airgun pulses has been
provided in the application and in previous Federal Register notices
(see 69 FR 31792 (June 7, 2004) or 69 FR 34996 (June 23, 2004)).
Reviewers are referred to those documents for additional information.

Comments and Responses

A notice of receipt of the UAF application and proposed IHA was
published in the Federal Register on May 10, 2005 (70 FR 24539). The
Federal Register notice also invited comments on UAF's associated draft
Environmental Assessment (EA), which was posted on the NMFS website.
During the comment period, NMFS received comments only from the Marine
Mammal Commission (Commission) and one individual.
Comment 1: The Commission notes that the May, 2005 Federal Register
notice states that monitoring would be conducted by at least one
observer and, when practical, two observers, but does not indicate what
factors will be used to determine when monitoring by two observers will
be considered ``practical.'' The Commisssion recommends that NMFS seek
clarification of this point.
Response: There will always be two observers watching for at least
30 minutes before seismic operations begin. Observation coverage during
this time period is especially important in order to avoid surprising a
marine mammal. Once seismic operations have begun, it is more likely a
marine mammal will move to avoid the area within the safety radii. Once
operations have begun, the time that two observers are on watch will be
maximized within the constraints of four observers, working watches no
longer than 4 hours, with 8-hr breaks in each 24-hr period, and needing
time to work the data.
Comment 2: In light of the fact that marine mammal detection is
especially difficult in the dark, the Commission recommends that NMFS
more explicitly define what constitutes daytime and nighttime for
purposes of the proposed mitigation measures.
Response: NMFS appreciates the Commissions concerns regarding the
detection of marine mammals in the dark. However, whether it is night-
time or a foggy day, the Healy's start-up procedures require that
seismic operation ramp-up may not begin unless the entire safety radius
has been completely visible for at least 30 minutes prior to start-up.
Comment 3: The Commission notes that the use of passive acoustic
detection techniques to locate whales and ice seals by their
vocalizations prior to start-up of the airguns might increase the
efficacy of the monitoring effort and may be a useful additional
mitigation measure that should be implemented. They further suggest
that NMFS consult with the applicant about the possibility of
establishing a one-half hour listening period prior to start-up of the
airguns for this purpose.
Response: In response to a request and subsequent discussion at the
Anchorage MMPA Peer-review meeting in May, 2005, UAF has added a
passive acoustic monitoring component (described in the Monitoring
section below), which will utilize data collected by the sonobuoys that
are deployed from the Healy every 4 hours. The plan is for one MMO to
listen to the sound being received by the closest sonobuoy for 10
minutes out of every 30 they are monitoring, which will include time
prior to ramp up of seismic operations. The added passive acoustic
monitoring with sonobuoys, though it will allow marine mammal observers
(MMOs) to identify the presence of marine mammals in a region in which
visual observations are restricted by ice and poor visibility, will not
be used directly to implement mitigation measures (i.e. to necessitate
a shut-down) because the direction and exact distance from which the
signals are coming cannot be determined. However, any information
gathered could help to fill a data gap about the habitats marine
mammals occupy in the very high Arctic latitudes.
Comment 4: The Commission states concerns about whether the
proposed monitoring effort will be sufficient to determine that no
marine mammal, especially species that may be difficult to detect, are
within the safety zones (190 dB for pinnipeds, 180 dB for cetaceans) at
start up or will be an effective means of detecting when marine mammals
enter the safety zones during operations.
Response: For this activity, the safety radii range from 17 to 78 m
(56 to 256 ft) in deep water (91 percent of survey), to 100 to 500 m
(328 to1640 ft) in intermediate depth water (9 percent of survey).
Considering the small size of the conservative shutdown zones, the
speed of the vessel when towing the airgun (6.5 km/h (3.5 knots)), and
the marine mammal avoidance measures that are implemented on the vessel
for animals on the vessel's track, it is very unlikely that any marine
mammals would enter the safety zone undetected. If a marine mammal
enters the small safety zone, operational shutdown will be implemented
until the animal leaves the safety zone.

Description of Habitat and Marine Mammals Affected by the Activity

A detailed description of the Healy's revised track from northwest
of Barrow, through the Arctic ocean to northwest of

[[Page 47797]]

Svalbard and the associated marine mammals can be found in the UAF
application (including revisions) and a number of documents referenced
in the UAF application. A total of 17 cetacean species and 10 pinniped
species may occur in the proposed study area. The marine mammals that
occur in the proposed survey area belong to four taxonomic groups:
odontocetes (toothed cetaceans, such as dolphins and sperm whales),
mysticetes (baleen whales), pinnipeds (seals, sea lions, and walrus),
and fissipeds (polar bear).
Odontocete whales include the sperm whale, northern bottlenose
whale, beluga whale, narwhal, Atlantic white-beaked dolphin, Atlantic
white-sided dolphin, killer whale, long-finned pilot whale, and harbor
porpoise.
Mysticete whales include the North Atlantic right whale, bowhead
whale, gray whale, humpback whale, minke whale, sei whale, fin whale,
and blue whale.
Pinnipeds include the walrus, bearded seal, harbor seal, spotted
seal, ringed seal, hooded seal, and harp seal.
The marine mammal species most likely to be encountered include
four cetacean species (beluga whale, narwhal, gray whale, bowhead
whale), five pinniped species (walrus, bearded seal, ringed seal,
hooded seal, harp seal), and the polar bear. However, most of these
will occur in low numbers and are most likely to be encountered within
100 km (54 nm) of shore. The most abundant marine mammal likely to be
encountered throughout the cruise is the ringed seal. The most widely
distributed marine mammals are expected to be the beluga, ringed seal,
and polar bear.
About 13 additional cetacean species could occur in the project
area, but are unlikely to be encountered along the proposed trackline.
If encountered at all, those species would be found only near one end
of the track, either near Svalbard or near Alaska. The following 12
species, if encountered at all, would be found close to Svalbard: sperm
whale, northern bottlenose whale, long-finned pilot whale, Atlantic
white-sided dolphin, Atlantic white-beaked dolphin, harbor porpoise,
killer whale, North Atlantic right whale, humpback whale, minke whale,
sei whale, fin whale, and blue whale. Two additional pinniped species,
the harbor seal and spotted seal, are also unlikely to be encountered.
Although information on the walrus and polar bear are included
here, they are managed by the U.S. Fish & Wildlife Service (USFWS) and
are not the subject of this authorization. UAF will coordinate with the
USFWS regarding the effects of project operations on walruses and polar
bears.
More detailed information on these species is contained in the UAF
application (see ADDRESSES).

Potential Effects of Activities on Marine Mammals

The effects of noise on marine mammals are highly variable, and can
be categorized as follows (based on Richardson et al., 1995):
(1) The noise may be too weak to be heard at the location of the
animal (i.e., lower than the prevailing ambient noise level, the
hearing threshold of the animal at relevant frequencies, or both);
(2) The noise may be audible but not strong enough to elicit any
overt behavioral response;
(3) The noise may elicit reactions of variable conspicuousness and
variable relevance to the well being of the marine mammal; these can
range from temporary alert responses to active avoidance reactions such
as vacating an area at least until the noise event ceases;
(4) Upon repeated exposure, a marine mammal may exhibit diminishing
responsiveness (habituation), or disturbance effects may persist; the
latter is most likely with sounds that are highly variable in
characteristics, infrequent and unpredictable in occurrence, and
associated with situations that a marine mammal perceives as a threat;
(5) Any anthropogenic noise that is strong enough to be heard has
the potential to reduce (mask) the ability of a marine mammal to hear
natural sounds at similar frequencies, including calls from
conspecifics, and underwater environmental sounds such as surf noise;
(6) If mammals remain in an area because it is important for
feeding, breeding or some other biologically important purpose even
though there is chronic exposure to noise, it is possible that there
could be noise-induced physiological stress; this might in turn have
negative effects on the well-being or reproduction of the animals
involved; and
(7) Very strong sounds have the potential to cause temporary or
permanent reduction in hearing sensitivity. In terrestrial mammals, and
presumably marine mammals, received sound levels must far exceed the
animal's hearing threshold for there to be any temporary threshold
shift (TTS) in its hearing ability. For transient sounds, the sound
level necessary to cause TTS is inversely related to the duration of
the sound. Received sound levels must be even higher for there to be
risk of permanent hearing impairment. In addition, intense acoustic or
explosive events may cause trauma to tissues associated with organs
vital for hearing, sound production, respiration and other functions.
This trauma may include minor to severe hemorrhage.

Effects of Seismic Surveys on Marine Mammals

The UAF application provides the following information on what is
known about the effects on marine mammals of the types of seismic
operations planned by UAF. The types of effects considered in here are
(1) tolerance, (2) masking of natural sounds, (3) behavioral
disturbance, and (4) potential hearing impairment and other non-
auditory physical effects (Richardson et al., 1995). Because the airgun
sources planned for use during the present project involve only one or
two airguns, the effects are anticipated to be considerably less than
would be the case with a large array. UAF and NMFS believe it is very
unlikely that there would be any cases of temporary or permanent
hearing impairment, or non-auditory physical effects. Also, behavioral
disturbance is expected to be limited to animals that are near the
vessel at distances less than 3300 m (10827 ft) in deep water (91
percent of survey) and less than 5000 m (16404 ft) in intermediate
water depths, where the received sound levels greater than160 dB are
expected to be. This corresponds to the value NMFS uses for onset of
Level B harassment due to impulse sounds. Additional discussion on
effects on marine mammal species can be found in the UAF application.
Tolerance
Numerous studies (referenced in L-DEO, 2004) have shown that pulsed
sounds from airguns are often readily detectable in the water at
distances of many kilometers, but 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 hearing sensitivity of that mammal group.
However, most measurements of airgun sounds that have been reported
concerned sounds from larger arrays of airguns, whose sounds would be
detectable farther away than the ones that are planned to be used in
the proposed survey. Although various baleen whales, toothed whales,
and pinnipeds have been shown to react behaviorally to airgun pulses
under some conditions, at other times all three types of mammals have
shown no overt reactions. In general, pinnipeds and

[[Page 47798]]

small odontocetes seem to be more tolerant of exposure to airgun pulses
than are baleen whales. Given the low-energy airgun sources planned for
use in this proposed project, marine mammals would be expected to
tolerate being closer to these sources than would be the case for a
larger airgun source typical of most seismic surveys.
Masking
Masking effects of pulsed sounds (even from large arrays of
airguns) on marine mammal vocalizations and other natural sounds are
expected to be limited, although there are very few specific data of
relevance. Some whales are known to continue calling in the presence of
seismic pulses. Their calls can be heard between the seismic pulses
(e.g., Richardson et al., 1986; McDonald et al., 1995; Greene et al.,
1999; Nieukirk et al., 2004). Although there has been one report that
sperm whales cease calling when exposed to pulses from a very distant
seismic ship (Bowles et al., 1994), a more recent study reports that
sperm whales off northern Norway continued calling in the presence of
seismic pulses (Madsen et al., 2002). That behavior has also been shown
during recent work in the Gulf of Mexico (Tyack et al., 2003). Given
that the airgun sources planned for use here involve only 1 or 2
airguns, there is even less potential for masking of baleen or sperm
whale calls during the present study than in most seismic surveys.
Masking effects of seismic pulses are expected to be negligible in the
case of the odontocete cetaceans, given the intermittent nature of
seismic pulses and the relatively low source level of the airgun
configurations to be used here. Also, the sounds important to
odontocetes are predominantly at much higher frequencies than are
airgun sounds and would not be masked by the airguns.
Most of the energy in the sound pulses emitted by airguns is at low
frequencies, with strongest spectrum levels below 200 Hz and
considerably lower spectrum levels above 1000 Hz. These low frequencies
are mainly used by mysticetes, but generally not by odontocetes or
pinnipeds. An industrial sound source will reduce the effective
communication or echolocation distance only if its frequency is close
to that of the marine mammal's signal. If little or no overlap occurs
between the frequencies of the industrial noise and the marine mammals,
as in the case of many marine mammals relative to airgun sounds,
communication and echolocation are not expected to be disrupted.
Furthermore, the discontinuous nature of seismic pulses makes
significant masking effects unlikely even for mysticetes.
A few cetaceans are known to increase the source levels of their
calls in the presence of elevated sound levels, or possibly to shift
their peak frequencies in response to strong sound signals (Dahlheim,
1987; Au, 1993; Lesage et al., 1999; Terhune, 1999; as reviewed in
Richardson et al., 1995). These studies involved exposure to other
types of anthropogenic sounds, not seismic pulses, and it is not known
whether these types of responses ever occur upon exposure to seismic
sounds. If so, these adaptations, along with directional hearing, pre-
adaptation to tolerate some masking by natural sounds (Richardson et
al., 1995) and the relatively low-power acoustic sources being used in
this survey, would all reduce the possible adverse impacts of masking
marine mammal vocalizations.
Behavioral Disturbance by Seismic Surveys
Disturbance includes a variety of effects, including subtle changes
in behavior, more conspicuous changes in activities, and displacement.
Not all behavioral disturbances rise to the level of Level B
Harassment, which requires a disruption of behavioral patterns of
biological importance. Exposure to sound alone may not constitute
harassment or ``taking'' (NMFS 2001, p. 9293). Behavioral reactions of
marine mammals to sound are difficult to predict. Reactions to sound,
if any, depend on species, individual variation, state of maturity,
experience, current activity, reproductive state, time of day, season,
and many other factors. If a marine mammal does react to an underwater
sound by changing its behavior or moving a small distance, the impacts
of the change may not rise to the level of a disruption of a behavioral
pattern. However, if a sound source would displace a marine mammal from
an important feeding or breeding area, such a disturbance may
constitute Level B harassment under the MMPA. In addition, effects that
might not constitute Level B harassment may still result in spatial
displacement of sensitive species, such as bowhead whales, thereby
affecting subsistence needs. Given the many uncertainties in predicting
the quantity and types of impacts of noise on marine mammals, NMFS
estimates the number of marine mammals that may be present within a
particular distance of industrial activities or exposed to a particular
level of industrial sound and uses these numbers as a proxy. With the
possible exception of beaked whales, NMFS believes that this is a
conservative approach and likely overestimates the numbers of marine
mammals that may experience a disruption of a behavioral pattern.
The sound exposure criteria used to estimate how many marine
mammals might be harassed behaviorally by the seismic survey are based
on behavioral observations during studies of several species. However,
information is lacking for many other species. Detailed studies have
been conducted on humpback, gray, and bowhead whales, and on ringed
seals. Less detailed data are available for some other species of
baleen whales, sperm whales, small toothed whales, and sea otters. Most
of those studies have been on behavioral reactions to much larger
airgun sources than the airgun configurations planned for use in the
present project. Thus, effects are expected to be limited to
considerably smaller distances and shorter periods of exposure in the
present project than in most of the previous work concerning marine
mammal reactions to airguns. Detailed information on potential
disturbance effects on baleen whales, toothed whales, and pinnipeds can
be found in the UAF application.
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 airgun
pulses. Based on current information, NMFS precautionarily sets
impulsive sounds equal to or greater than 180 and 190 dB re 1 microPa
(rms) as the exposure thresholds for onset of Level A harassment
(injury) for cetaceans and pinnipeds, respectively (NMFS, 2000). Those
criteria have been used for several years in setting the safety (shut-
down) radii for seismic surveys. As discussed in the UAF application
and summarized here,
1. The 180-dB criterion for cetaceans is probably quite
precautionary, i.e., lower than necessary to avoid TTS let alone
permanent auditory injury, at least for delphinids.
2. The minimum sound level necessary to cause permanent hearing
impairment is higher, by a variable and generally unknown amount, than
the level that induces barely-detectable TTS.
3. The level associated with the onset of TTS is often considered
to be lower than levels that may cause permanent hearing damage.
Because the airgun sources planned for use during this project
involve only

[[Page 47799]]

1 or 2 guns, and with the planned monitoring and mitigation measures,
there is little likelihood that any marine mammals will be exposed to
sounds sufficiently strong to cause even the mildest (and reversible)
form of hearing impairment. Several aspects of the planned monitoring
and mitigation measures for this project are designed to detect marine
mammals occurring near the airgun(s), and multi-beam sonar, and to
avoid exposing them to sound pulses that might (at least in theory)
cause hearing impairment. In addition, many cetaceans are likely to
show some avoidance of the small area with high received levels of
airgun sound (see above). In those cases, the avoidance responses of
the animals themselves will likely reduce or prevent any possibility of
hearing impairment.
Non-auditory physical effects might also occur in marine mammals
exposed to strong underwater pulsed sound. Possible types of non-
auditory physiological effects or injuries that theoretically might
occur in mammals close to a strong sound source include stress,
neurological effects, bubble formation, resonance effects, and other
types of organ or tissue damage. It is possible that some marine mammal
species (i.e., beaked whales) may be especially susceptible to injury
and/or stranding when exposed to strong pulsed sounds. However, as
discussed below, there is no definitive evidence that any of these
effects occur even in marine mammals that are in close proximity to
large arrays of airguns. UAF and NMFS believe that it is highly
unlikely that any of these non-auditory effects would occur during the
proposed survey given the small size of the source, the brief duration
of exposure of any given mammal, and the planned mitigation and
monitoring measures. The following paragraphs discuss the possibility
of TTS, permanent threshold shift (PTS), and non-auditory physical
effects.
TTS
TTS is the mildest form of hearing impairment that can occur during
exposure to a strong sound (Kryter, 1985). When an animal experiences
TTS, its 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. Richardson et al. (1995) note that the magnitude of TTS
depends on the level and duration of noise exposure, among other
considerations. For sound exposures at or somewhat above the TTS
threshold, hearing sensitivity recovers rapidly after exposure to the
noise ends. Little data on pulsed sound levels and durations necessary
to elicit mild TTS have been obtained for marine mammals, and none of
the published data concern TTS elicited by exposure to multiple pulses
of sound.
For toothed whales exposed to single short pulses, the TTS
threshold appears to be, at a first approximation, a function of the
energy content of the pulse (Finneran et al., 2002). Given the
available data, the received level of a single seismic pulse might need
to be approximately 210 dB re 1 microPa rms (approx. 221 226 dB pk pk)
in order to produce brief, mild TTS. Exposure to several seismic pulses
at received levels near 200 205 dB (rms) might result in slight TTS in
a small odontocete, assuming the TTS threshold is at a function of the
total received pulse energy (Finneran et al., 2002). Seismic pulses
with received levels of 200 205 dB or more are usually restricted to a
zone of no more than 100 m (328 ft) around a seismic vessel operating a
large array of airguns. Such sound levels would be limited to distances
within a few meters of the single airgun planned for use during this
project.
There are no data, direct or indirect, on levels or properties of
sound that are required to induce TTS in any baleen whale. However, TTS
is not expected to occur during this survey given that the airgun
sources involve only 1 or 2 airguns, and the strong likelihood that
baleen whales would avoid the approaching airgun(s), or vessel, before
being exposed to levels high enough for there to be any possibility of TTS.
TTS thresholds for pinnipeds exposed to brief pulses (single or
multiple) have not been measured, although exposures up to 183 dB re 1
microPa (rms) have been shown to be insufficient to induce TTS in
captive California sea lions (Finneran et al., 2003). However, studies
for prolonged exposures show that some pinnipeds may incur TTS at
somewhat lower received levels for prolonged exposures than do small
odontocetes exposed for similar durations (Kastak et al., 1999; Ketten
et al., 2001; Au et al., 2000). More recent indications are that TTS
onset in the most sensitive pinniped species studied (harbor seal) may
occur at a similar sound exposure level as in odontocetes (Kastak et
al., 2004).
A marine mammal within 100 m ( < =328 ft) of a typical large array
of operating airguns might be exposed to a few seismic pulses with
levels of [gteqt]
205 dB, and possibly more pulses if the mammal moved
with the seismic vessel. (As noted above, most cetacean species tend to
avoid operating airguns, although not all individuals do so.) However,
several of the considerations that are relevant in assessing the impact
of typical seismic surveys with arrays of airguns are not directly
applicable here:(1) The planned airgun sources involve only 1 or 2
airguns, with correspondingly smaller radii within which received sound
levels could exceed any particular level of concern.
(2) ``Ramping up'' (soft start) 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
will be employed when the 2 G. guns are operated.
(3) Even with a large airgun array, it is unlikely that cetaceans
would be exposed to airgun pulses at a sufficiently high level for a
sufficiently long period to cause more than mild TTS, given the
relative movement of the vessel and the marine mammal. In this project,
the airgun sources are much less strong, so the area of influence and
duration of exposure to strong pulses is much smaller, especially in
deep and intermediate-depth water.
(4) With a large array of airguns, TTS would be most likely to
occur in any odontocetes that bow-ride or otherwise linger near the
airguns. In the present project, the anticipated 180 dB distances in
deep and intermediate-depth water are 325 and 500 m (1066 and 1640 ft),
respectively, for the 2 G. gun system, and 50 and 75 m (164 and 246
ft), respectively, for the single Bolt airgun (Table 2). The waterline
at the bow of the Healy will be approximately 123 m (403 ft) ahead of
the airgun.
NMFS believes that, to avoid Level A harassment, cetaceans should
not be exposed to pulsed underwater noise at received levels exceeding
180 dB re 1 microPa (rms). The corresponding limit for pinnipeds is 190
dB. The predicted 180- and 190-dB distances for the airgun arrays operated
by UAF during this activity are summarized in Table 1 in this document.
It has also been shown that most whales tend to avoid ships and
associated seismic operations. Thus, whales will likely not be exposed
to such high levels of airgun sounds. Because of the slow ship speed,
any whales close to the trackline could move away before the sounds
become sufficiently strong for there to be any potential for hearing
impairment. Therefore, there is little potential for whales being close
enough to an array to experience TTS. In addition, ramping up multiple
airguns in arrays has become standard operational protocol for many
seismic operators and will occur when the 2 G. guns are operated.

[[Page 47800]]

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, while in
other cases the animal has an impaired ability to hear sounds in
specific frequency ranges. Although there is no specific evidence that
exposure to pulses of airgun sounds can cause PTS in any marine
mammals, even with the largest airgun arrays, physical damage to a
mammal's hearing apparatus can potentially occur if it is exposed to
sound impulses that have very high peak pressures, especially if they
have very short rise times (time required for sound pulse to reach peak
pressure from the baseline pressure). Such damage can result in a
permanent decrease in functional sensitivity of the hearing system at
some or all frequencies.
Single or occasional occurrences of mild TTS are not indicative of
permanent auditory damage in terrestrial mammals. However, very
prolonged exposure to sound strong enough to elicit TTS, or shorter-
term exposure to sound levels well above the TTS threshold, can cause
PTS, at least in terrestrial mammals (Kryter, 1985). 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, based on their similar anatomy and inner ear structures. The
low-to-moderate levels of TTS that have been induced in captive
odontocetes and pinnipeds during recent controlled studies of TTS have
been confirmed to be temporary, with no measurable residual PTS (Kastak
et al., 1999; Schlundt et al., 2000; Finneran et al., 2002; Nachtigall
et al., 2003). In terrestrial mammals, the received sound level from a
single non-impulsive sound exposure must be far above the TTS threshold
for any risk of permanent hearing damage (Kryter, 1994; Richardson et
al., 1995). For impulse sounds with very rapid rise times (e.g., those
associated with explosions or gunfire), a received level not greatly in
excess of the TTS threshold may start to elicit PTS. The rise times for
airgun pulses are rapid, but less rapid than for explosions.
Some factors that contribute to onset of PTS are as follows: (1)
exposure to single very intense noises, (2) repetitive exposure to
intense sounds that individually cause TTS but not PTS, and (3) recurrent
ear infections or (in captive animals) exposure to certain drugs.
Cavanagh (2000) has reviewed the thresholds used to define TTS and
PTS. Based on his review and SACLANT (1998), it is reasonable to assume
that PTS might occur at a received sound level 20 dB or more above that
which induces mild TTS. However, for PTS to occur at a received level
only 20 dB above the TTS threshold, it is probable that the animal
would have to be exposed to the strong sound for an extended period.
Sound impulse duration, peak amplitude, rise time, and number of
pulses are the main factors thought to determine the onset and extent
of PTS. Based on existing data, Ketten (1994) has noted that the
criteria for differentiating the sound pressure levels that result in
PTS (or TTS) are location and species-specific. PTS effects may also be
influenced strongly by the health of the receiver's ear.
Given that marine mammals are unlikely to be exposed to received
levels of seismic pulses that could cause TTS, it is highly unlikely
that they would sustain permanent hearing impairment. If we assume that
the TTS threshold for odontocetes for exposure to a series of seismic
pulses may be on the order of 220 dB re 1 microPa (pk-pk)
(approximately 204 dB re 1 microPa rms), then the PTS threshold might
be about 240 dB re 1 microPa (pk-pk). In the units used by
geophysicists, this is 10 bar-m. Such levels are found only in the
immediate vicinity of the largest airguns (Richardson et al., 1995;
Caldwell and Dragoset, 2000). However, as noted previously in this
document, it is very unlikely that an odontocete would remain within a
few meters of a large airgun for sufficiently long to incur PTS. The
TTS (and thus PTS) thresholds of baleen whales and pinnipeds may be
lower, and thus may extend to a somewhat greater distance from the
source. However, baleen whales generally avoid the immediate area
around operating seismic vessels, so it is unlikely that a baleen whale
could incur PTS from exposure to airgun pulses. Some pinnipeds do not
show strong avoidance of operating airguns.
In summary, during this project, it is highly unlikely that marine
mammals could receive sounds strong enough and over a sufficient period
of time to cause permanent hearing impairment. In the proposed project
marine mammals are unlikely to be exposed to received levels of seismic
pulses strong enough to cause TTS, and because of the higher level of
sound necessary to cause PTS, it is even less likely that PTS could
occur. This is due to the fact that even levels immediately adjacent to
the single G. gun may not be sufficient to induce PTS because the
mammal would not be exposed to more than one strong pulse unless it
swam alongside an airgun for a period of time.
Strandings and Mortality
Marine mammals close to underwater detonations of high explosives
can be killed or severely injured, and the auditory organs are
especially susceptible to injury (Ketten et al., 1993; Ketten, 1995).
Airgun pulses are less energetic and have slower rise times than
underwater detonations. While there is no documented evidence that
airgun arrays can cause serious injury, death, or stranding, the
association of mass strandings of beaked whales with naval exercises
and, in one case, an L-DEO seismic survey have raised the possibility
that beaked whales may be especially susceptible to injury and/or
behavioral reactions that can lead to stranding when exposed to strong
pulsed sounds.
It is important to note that seismic pulses and mid-frequency
military sonar pulses are quite different. Sounds produced by the types
of airgun arrays used to profile sub-sea geological structures are
broadband with most of the energy below 1 kHz. Typical military mid-
frequency sonars operate at frequencies of 2 to 10 kHz, generally with
a relatively narrow bandwidth at any one time (though the center
frequency may change over time). Because seismic and sonar sounds have
considerably different characteristics and duty cycles, it is not
appropriate to assume that there is a direct connection between the
effects of military sonar and seismic surveys on marine mammals.
However, evidence that sonar pulses can, in special circumstances, lead
to hearing damage and, indirectly, mortality suggests that caution is
warranted when dealing with exposure of marine mammals to any high-
intensity pulsed sound.
In addition to mid-frequency sonar-related strandings (see 69 FR
74906 (December 14, 2004) for additional discussion), there was a
September, 2002 stranding of two Cuvier's beaked whales in the Gulf of
California (Mexico) when a seismic survey by the R/V Maurice Ewing was
underway in the general area (Malakoff, 2002). The airgun array in use
during that project was the Ewing's 20-gun 8490-in\3\ array. This might
be a first indication that seismic surveys can have effects, at least
on beaked whales, similar to the suspected effects of naval sonars.
However, the evidence linking the Gulf of California strandings to the
seismic surveys is inconclusive, and is not based on any physical
evidence (Hogarth, 2002; Yoder, 2002). The ship was also operating its
multi-beam

[[Page 47801]]

bathymetric sonar at the same time but this sonar had much less
potential to affect beaked whales than either the airguns in use or
these naval sonars. Although the link between the Gulf of California
strandings and the seismic (plus multi-beam sonar) survey is
inconclusive, this event, in addition to the various incidents
involving beaked whale strandings associated with naval exercises,
suggests a need for caution in conducting seismic surveys in areas
occupied by beaked whales.
The present project will involve lower-energy sound sources than
used in typical seismic surveys. That, along with the monitoring and
mitigation measures that are planned, and the infrequent occurrence of
beaked whales in the project area, will minimize any possibility for
strandings and mortality.
Non-auditory Physiological Effects
Possible types of non-auditory physiological effects or injuries
that might theoretically occur in marine mammals exposed to strong
underwater sound include stress, neurological effects, bubble
formation, resonance effects, and other types of organ or tissue
damage. There is no evidence that any of these effects occur in marine
mammals exposed to sound from airgun arrays. However, there have been
no direct studies of the potential for airgun pulses to elicit any of
these effects. If any such effects do occur, they would probably be
limited to unusual situations when animals might be exposed at close
range for unusually long periods.
Long-term exposure to anthropogenic noise may have the potential to
cause physiological stress that could affect the health of individual
animals or their reproductive potential, which could theoretically
cause effects at the population level (Gisner (ed.), 1999). However,
there is essentially no information about the occurrence of noise-
induced stress in marine mammals. Also, it is doubtful that any single
marine mammal would be exposed to strong seismic sounds for
sufficiently long that significant physiological stress would develop.
That is especially so in the case of the present project which will
deploy only 1 or 2 airguns, the ship is moving 3 4 knots, and for the
most part the tracklines will not ``double back'' through the same area.
Gas-filled structures in marine animals have an inherent
fundamental resonance frequency. If stimulated at this frequency, the
ensuing resonance could cause damage to the animal. There may also be a
possibility that high sound levels could cause bubble formation in the
blood of diving mammals that in turn could cause an air embolism,
tissue separation, and high, localized pressure in nervous tissue
(Gisner (ed), 1999; Houser et al., 2001). In 2002, NMFS held a workshop
(Gentry (ed.), 2002) to discuss whether the stranding of beaked whales
in the Bahamas in 2000 might have been related to air cavity resonance
or bubble formation in tissues caused by exposure to noise from naval
sonar. A panel of experts concluded that resonance in air-filled
structures was not likely to have caused this stranding. Among other
reasons, the air spaces in marine mammals are too large to be
susceptible to resonant frequencies emitted by mid- or low-frequency
sonar; lung tissue damage has not been observed in any mass, multi-
species stranding of beaked whales; and the duration of sonar pings is
likely too short to induce vibrations that could damage tissues (Gentry
(ed.), 2002).
Opinions were less conclusive about the possible role of gas
(nitrogen) bubble formation/growth in the Bahamas stranding of beaked
whales. Workshop participants did not rule out the possibility that
bubble formation/growth played a role in the stranding and participants
acknowledged that more research is needed in this area. The only
available information on acoustically-mediated bubble growth in marine
mammals is modeling that assumes prolonged exposure to sound.
A short paper concerning beaked whales stranded in the Canary
Islands in 2002 suggests that cetaceans might be subject to
decompression injury in some situations (Jepson et al., 2003). If so,
that might occur if they ascend unusually quickly when exposed to
aversive sounds. However, the interpretation that the effect was
related to decompression injury is unproven (Piantadosi and Thalmann,
2004; Fernandez et al., 2004). Even if that effect can occur during
exposure to mid-frequency sonar, there is no evidence that this type of
effect occurs in response to low-frequency airgun sounds. It is
especially unlikely in the case of the proposed survey, involving only
1 or 2 airguns that will operate in any one location only briefly.
In summary, little is known about the potential for seismic survey
sounds to cause either auditory impairment or other non-auditory
physical effects in marine mammals. Available data suggest that such
effects, if they occur at all, would be limited to short distances from
the sound source. However, the available data do not allow for
meaningful quantitative predictions of the numbers (if any) of marine
mammals that might be affected in these ways. Marine mammals that show
behavioral avoidance of seismic vessels, including most baleen whales,
some odontocetes, and some pinnipeds, are unlikely to incur auditory
impairment or other physical effects. Also, the planned mitigation and
monitoring measures are expected to minimize any possibility of serious
injury, mortality or strandings.
Possible Effects of Mid-frequency Sonar Signals
A SeaBeam 2112 multi-beam 12-kHz bathymetric sonar system and a
sub-bottom profiler will be operated from the source vessel nearly
continuously during the planned study. A pinger will be operated during
all coring.
Sounds from the SeaBeam 2112 multi-beam sonar system are very short
pulses, depending on water depth. Most of the energy in the sound
pulses emitted by the multi-beam 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.
Any given mammal at depth near the trackline would be in the main beam
for only a fraction of a second. Navy sonars that have been linked to
avoidance reactions and stranding of cetaceans generally: (1) are more
powerful than the SeaBeam 2112 sonar, (2) have a longer pulse duration,
and (3) are directed close to horizontally (vs. downward for the
SeaBeam sonars). The area of possible influence of the bathymetric
sonar is much smaller-a narrow band oriented in the cross-track
direction below the source vessel. Marine mammals that encounter the
bathymetric 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 and ship speed. In assessing the possible impacts of the 15.5-
kHz Atlas Hydrosweep (similar to the SeaBeam sonar), Boebel et al.
(2004) noted that the critical sound pressure level at which TTS may
occur is 203.2 dB re 1 microPa (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 would be incurred.
Therefore, as harassment or injury from pulsed sound is a function of
total energy received, the actual harassment or injury threshold for
the bathymetric sonar signals (approximately 10 ms) would be at a much
higher dB level than that for

[[Page 47802]]

longer duration pulses such as seismic signals. As a result, NMFS
believes that marine mammals are unlikely to be harassed or injured
from the SeaBeam multibeam sonars.
Sounds from the sub-bottom profiler are very short pulses; pulse
duration ranges from 0.5 to 25 milliseconds, and the interval between
pulses can range between 0.25 s and 10 s, depending upon water depth. A
3.5-kHz transducer emits a conical beam with a width of 26[deg]
and the
12 kHz transducer emits a conical beam with a width of 30[deg]. The
swept (chirp) frequency ranges from 2.75 kHz to 6 kHz. Most of the
energy from the sub-bottom profiler is directed downward from the
transducer array. Sound levels have not been measured directly for the
sub-bottom profiler used by the Healy, but Burgess and Lawson (2000)
measured sounds propagating more or less horizontally from a similar
unit with similar source output (205 dB re 1 microPa m). The 160- and
180- dB re 1 microPa rms radii, in the horizontal direction, were
estimated to be, respectively, near 20 m (66 ft) and 8 m (26 ft) from
the source, as measured in 13 m or 43 ft water depth. The corresponding
distances for an animal in the beam below the transducer would be
greater, on the order of 180 m (591 ft) and 18 m (59 ft), assuming
spherical spreading.
Sounds from the 12-kHz pinger are very short pulses, occurring for
0.5, 2, or 10 ms once every second, with source level approximately 192
dB re 1 microPa at a one pulse per second rate. The 12-kHz signal is
omnidirectional. The pinger produces sounds that are within the range
of frequencies used by small odontocetes and pinnipeds that occur or
may occur in the area of the planned survey.
Masking by Mid-frequency Sonar Signals
Marine mammal communications will not be masked appreciably by the
multibeam sonar signals or the sub-bottom profiler given the low duty
cycle and directionality of the sonars and the brief period when an
individual mammal is likely to be within its beam. Furthermore, the 12-
kHz multi-beam will not overlap with the predominant frequencies in
baleen whale calls, further reducing any potential for masking in that
group.
While the 12-kHz pinger produces sounds within the frequency range
used by odontocetes that may be present in the survey area and within
the frequency range heard by pinnipeds, marine mammal communications
will not be masked appreciably by the pinger signals. This is a
consequence of the relatively low power output, low duty cycle, and
brief period when an individual mammal is likely to be within the area
of potential effects. In the case of mysticetes, the pulses do not
overlap with the predominant frequencies in the calls, which would
avoid significant masking.
Behavioral Responses Resulting from Mid-frequency Sonar Signals
Behavioral reactions of free-ranging marine mammals to military and
other sonars appear to vary by species and circumstance. Observed
reactions have included silencing and dispersal by sperm whales
(Watkins et al., 1985), increased vocalizations and no dispersal by
pilot whales (Rendell and Gordon, 1999), and the previously-mentioned
strandings by beaked whales. Also, Navy personnel have described
observations of dolphins bow-riding adjacent to bow-mounted mid-
frequency sonars during sonar transmissions. However, all of these
observations are of limited relevance to the present situation. Pulse
durations from these sonars were much longer than those of the
bathymetric sonars to be used during the proposed survey, and a given
mammal would have received many pulses from the naval sonars. During
UAF's operations, the individual pulses will be very short, and a given
mammal would not receive many of the downward-directed pulses as the
vessel passes by.
Captive bottlenose dolphins and a white whale exhibited changes in
behavior when exposed to 1-s pulsed sounds at frequencies similar to
those that will be emitted by the bathymetric sonar to be used by UAF
and to shorter broadband pulsed signals. Behavioral changes typically
involved what appeared to be deliberate attempts to avoid the sound
exposure (Schlundt et al., 2000; Finneran et al., 2002). The relevance
of these data to free-ranging odontocetes is uncertain and in any case
the test sounds were quite different in either duration or bandwidth as
compared to those from a bathymetric sonar.
UAF and NMFS are not aware of any data on the reactions of
pinnipeds to sonar sounds at frequencies similar to those of the 12-kHz
multibeam sonar. Based on observed pinniped responses to other types of
pulsed sounds, and the likely brevity of exposure to the bathymetric
sonar sounds, pinniped reactions are expected to be limited to startle
or otherwise brief responses of no lasting consequences to the
individual animals.
The pulsed signals from the pinger are much weaker than those from
the bathymetric sonars and sub-bottom profiler. In summary, NMFS does
not anticipate behavioral disturbance from the mid-frequency sources
discussed unless marine mammals get very close to the source.
Hearing Impairment and Other Physical Effects
Given recent stranding events that have been associated with the
operation of naval sonar, there is concern that sonar noise can cause
serious impacts to marine mammals. However, the multi-beam sonars
proposed for use by UAF are quite different than sonars used for navy
operations. Pulse duration of the bathymetric sonars is very short
relative to the naval sonars. Also, at any given location, an
individual marine mammal would be in the beam of the multi-beam sonar
for much less time given the generally downward orientation of the beam
and its narrow fore-aft beam-width. (Navy sonars often use near-
horizontally-directed sound.) These factors would all reduce the sound
energy received from the multi-beam sonar relative to that from the
sonars used by the Navy. Therefore, hearing impairment by multi-beam
bathymetric sonar is unlikely.
Source levels of the sub-bottom profiler are much lower than those
of the airguns and the multi-beam sonar, which are discussed above.
Sound levels from a sub-bottom profiler similar to the one on the Healy
were estimated to decrease to 180 dB re 1 microPa (rms) at 8 m (26 ft)
horizontally from the source (Burgess and Lawson, 2000), and at
approximately 18 m (59 ft) downward from the source. Furthermore,
received levels of pulsed sounds that are necessary to cause temporary
or especially permanent hearing impairment in marine mammals appear to
be higher than 180 dB (see earlier). Thus, it is unlikely that the sub-
bottom profiler produces pulse levels strong enough to cause hearing
impairment or other physical injuries even in an animal that is
(briefly) in a position near the source. The 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
mammals would be close enough for there to be any possibility of
effects from the less intense sounds from the sub-bottom profiler. In
the case of mammals 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

[[Page 47803]]

the sub-bottom profiler. Given the brevity of the pulses from each
source [sub-bottom profiler, multi-beam sonar, airgun(s)], and the
directionality of the first two sources, it would be rare for an animal
to receive pulses from 2 or 3 of the sources simultaneously. In the
unlikely event that simultaneous reception did occur, the combined
received level would be little different from that attributable to the
strongest single source (see equation 2.9 in Richardson et al. 1995, p.
30).
Source levels of the pinger are much lower than those of the G.
airgun and bathymetric sonars. It is unlikely that the pinger produces
pulse levels strong enough to cause temporary hearing impairment or
(especially) physical injuries even in an animal that is (briefly) in a
position near the source.

Mitigation

For the proposed seismic survey in the Arctic Ocean in August -
September 2005, UAF will use airgun sources involving one or two
airguns and a downward direction of energy. The downward directional
nature of the airgun(s) to be used in this project is an important
mitigating factor as it will result in reduced sound levels at any
given horizontal distance as compared with the levels expected at that
distance if the source were omnidirectional with the stated nominal
source level. The relatively small size of these sources is also an
important mitigation measure that will reduce the potential for effects
relative to those that might occur with large airgun arrays. This
measure is in conformance with NMFS policy of encouraging seismic
operators to use the lowest intensity airguns practical to accomplish
research objectives.
The following mitigation measures, as well as marine mammal visual
monitoring (discussed later in this document), will be implemented for
the subject seismic survey: (1) speed and course alteration (provided
that they do not compromise operational safety requirements); (2) power
or shut-down procedures; (3) special mitigation measures (shut-downs)
for the North Atlantic right whale and Northeast Atlantic bowhead
whale, because of special concern associated with their very low
population sizes, and (4) ramp-up procedures.

Speed and Course Alteration

If a marine mammal is detected outside its respective safety zone
(180 dB for cetaceans, 190 dB for pinnipeds) and, based on its position
and the relative motion, is likely to enter the safety zone, the
vessel's speed and/or direct course may, when practical and safe, be
changed in a manner that also minimizes the effect to the planned
science objectives. The marine mammal activities and movements relative
to the seismic vessel will be closely monitored to ensure that the
marine mammal does not approach within the safety zone. If the mammal
appears likely to enter the safety zone, further mitigative actions
will be taken (i.e., either further course alterations or shut down of
the airguns).

Power-down Procedures

A power-down involves decreasing the number of airguns in use such
that the radius of the 180-dB (or 190-dB) zone is decreased to the
extent that marine mammals are not in the safety zone. A power down may
also occur when the vessel is moving from one seismic line to another.
During a power-down, one airgun is operated. In this project, a power-
down is possible when the two G. gun array is in use, but not when
single Bolt airgun is in use. The continued operation of one airgun is
intended to alert marine mammals to the presence of the seismic vessel
in the area. In contrast, a shut-down occurs when all airgun activity
is suspended.
If a marine mammal 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 may (as an alternative to a complete shut-down) be
powered down before the mammal is within the safety radius. Likewise,
if a mammal is already within the safety zone when first detected, the
airguns will be powered down immediately if this is a reasonable
alternative to a complete shut-down. During a power-down of the 2-G.
gun system, one airgun (e.g., 250 in\3\) will be operated. If a marine
mammal is detected within or near the smaller safety radius around that
single airgun (Table 2), the other airgun will be shut down (see next
subsection).
Following a power-down, airgun activity will not resume until the
marine mammal has cleared the safety zone. The safety zones for both
one and two Sodera 250-in\3\ G. guns, as well as the single 1200-in\3\
Bolt airgun at both 180 and 190 dB, are described in Table 1. The
animal will be considered to have cleared the safety zone if it is
visually observed to have left the safety zone, if it has not been seen
within the zone for 15 minutes in the case of small odontocetes and
pinnipeds, or if it has not been seen within the zone for 30 minutes in
the case of mysticetes and large odontocetes, including sperm and
beaked whales.

Shut-down Procedures

The operating airgun(s) will be shut down completely if a marine
mammal approaches or enters the then-applicable safety radius and a
power down is not practical. The operating airgun(s) will also be shut
down completely if a marine mammal approaches or enters the estimated
safety radius of the source that would be used during a power down.
Airgun activity will not resume until the marine mammal has cleared
the safety radius. The animal will be considered to have cleared the
safety radius if it is visually observed to have left the safety
radius, or if it has not been seen within the radius for 15 min (small
odontocetes, pinnipeds, and sea turtles) or 30 min (mysticetes and
large odontocetes, including sperm and beaked whales).
In the unlikely event a right whale is sighted by the vessel-based
observers, or if a bowhead is sighted in the Svalbard area, the
airgun(s) will be shut down regardless of the distance of the whale
from the airgun(s).

Start-Up Procedures

A ``ramp-up'' procedure will be followed when the 2-G. gun cluster
begins operating after a specified-duration period without airgun
operations. NMFS normally recommends that the rate of ramp up be no
more than 6 dB per 5-min period. The specified period depends on the
speed of the source vessel and the size of the airgun array being used.
Ramp-up will begin with one of the two G. guns (250 in\3\). The other
G. gun will be added after a period of 5 min. This will result in an
increase of no more than 6 dB per 5-min period when going from one G.
gun to the full two G. gun system, which is the normal rate of ramp up
for larger airgun arrays. During the ramp-up (i.e. when only one G. gun
is operating), the safety zone for the full two G. gun system will be
maintained.
If the complete safety radius has not been visible for at least 30
min prior to the start of operations in either daylight or nighttime,
ramp-up will not commence unless one G. gun has been operating during
the interruption of the seismic survey operations. This means that it
will not be permissible to ramp up the two-G. gun source from a
complete shut down in thick fog or at other times when the outer part
of the safety zone is not visible. If the entire safety radius is
visible using vessel lights and/or night vision devices (NVDs) (as may
be possible under moonlit and calm conditions), then start-up of the
airguns from a shut-down

[[Page 47804]]

may occur at night. If one airgun has operated during a power-down
period, ramp up to full power will be permissible at night or in poor
visibility, on the assumption that marine mammals will be alerted to
the approaching seismic vessel by the sounds from the single airgun and
could move away if they chose. Ramp-up of the airguns will not be
initiated if a marine mammal is sighted within or near the applicable
safety radii during the day or a night.

Marine Mammal Monitoring

Vessel-based marine mammal observers (MMOs) will monitor marine
mammals near the seismic source vessel during all daytime hours and
during any start ups of the airgun(s) at night. Airgun operations will
be powered down or shut down when marine mammals are observed within,
or about to enter, designated safety radii where there is a possibility
of significant effects on hearing or other physical effects. Vessel-
based MMOs will also watch for marine mammals near the seismic vessel
for at least 30 min prior to the planned start of airgun operations
after an extended shut down of the airgun. When feasible, observations
will also be made during daytime periods without seismic operations
(e.g., during transits and during coring operations).
During seismic operations across the Arctic Ocean, four observers
will be based aboard the vessel. MMOs will be appointed by UAF with
NMFS concurrence. A Barrow resident knowledgeable about the mammals and
fish of the area is expected to be included in the MMO team aboard the
Healy. At least one observer, and when practical two observers, will
monitor marine mammals near the seismic vessel during ongoing daytime
operations and nighttime start ups of the airgun. Use of two
simultaneous observers will increase the proportion of the animals
present near the source vessel that are detected. MMOs 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 marine mammals and
implementing mitigation requirements (if practical). Before the start
of the seismic survey the crew will be given additional instruction on
how to do so.
The Healy is a suitable platform for marine mammal observations.
When stationed on the flying bridge, the eye level will be 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. During daytime, the MMOs will scan the area around the
vessel systematically with reticle binoculars (e.g., 7 . 50 Fujinon)
and with the naked eye. During darkness, NVDs will be available (ITT
F500 Series Generation 3 binocular-image intensifier or equivalent), if
and when required. Laser rangefinding binoculars (Leica LRF 1200 laser
rangefinder or equivalent) will be available to assist with distance
estimation. Those are useful in training observers to estimate
distances visually, but are generally not useful in measuring distances
to animals directly.Taking into consideration the additional costs of
prohibiting nighttime operations and the likely impact of the activity
(including all mitigation and monitoring), NMFS has determined that the
required mitigation and monitoring ensures that the activity will have
the least practicable impact on the affected species or stocks. Two
marine mammal observers will be required to monitor the safety radii
(using shipboard lighting or NVDs at night) for at least 30 minutes
before ramp-up begins and verify that no marine mammals are in or
approaching the safety radii; start-up may not begin unless the entire
safety radii are visible; and marine mammals will have sufficient
notice of a vessel approaching with an operating seismic airgun,
thereby giving them an opportunity to avoid the approaching noise
source. Additionally, a power-down or shut-down will occur if a marine
mammal is detected within the safety radius.

Passive Acoustic Monitoring Using Sonobuoys

At the request of interested parties in the scientific field, UAF
developed a method and procured additional equipment to implement a
passive acoustic marine mammal monitoring program utilizing sonobuoys
already in use for other purposes on the Healy's Arctic cruise. Details
and the proposed protocols are outlined below.
The University of Alaska has obtained approximately 300 sonobuoys
for use during the marine seismic survey by the Healy across the Arctic
Ocean. Two hundred of the sonobuoys are of the type AN/SSQ-57SPC; an
additional 100 sonobuoys will also be available. The sonobuoys will
primarily be used to obtain seismic information during the survey.
However, as a secondary function, they will also be used to passively
monitor for marine mammal vocalizations during the survey. The use of
sonobuoys for passive acoustic monitoring of marine mammals is in lieu
of using a towed hydrophone array, as ice conditions, deployment
logistics, and personnel limitations would complicate the use of this
type of equipment in the survey area.
The sonobuoys will be launched from the fantail approximately every
4 hours while underway, and they will be set to transmit signals for up
to 8 hours. The MMOs will be able to listen to the signals from the
sonobuoys in real time, concurrently while observing. The signals will
be fed to the MMO station through the ship's network and/or via FM
radio. MMOs will listen to the signals by use of weatherproof speakers
or noise-canceling headphones. The strong airgun pulses will be blanked
out, as necessary to allow the MMOs to listen effectively for marine
mammal vocalizations. Laptop computers with acoustic software to
display, analyze, and save acoustic samples will be available for use
for the MMOs, when appropriate.
It is tentatively planned that at least one MMO will listen to the
sonobuoy signals for a minimum of 10 minutes during each 30-minute
period of visual watch when a useable sonobuoy signal is available. The
specific acoustic survey protocol may need to be amended early in the
cruise, as simultaneous visual and acoustic monitoring by the same MMO
is a new approach for a seismic survey. Some details may require
refinement when the planned procedures are first implemented. The times
when sonobuoy signals are monitored will be noted, along with the other
information routinely recorded by MMOs during their visual watches.
When there is an acoustic encounter with marine mammal(s), the details
will be documented in a manner consistent with that used during passive
acoustic monitoring in previous L-DEO cruises. Samples of the marine
mammal sounds will be recorded via the laptop computer.
The sonobuoys are broadband receivers, and their sensitivity ranges
from 10 Hz to 20 kHz. Thus, any vocalizing marine mammal (e.g., bowhead
whale, beluga, narwhal, bearded seal) in the survey area near the Healy
could be detected with the sonobuoys, providing that there is not too
much background noise (e.g., seismic sounds, ship noise, ice noise)
that could mask marine mammal signals.
Even though marine mammal vocalizations may be detected during the
survey, acoustic detections will not be used directly to implement
mitigation measures. The sonobuoys will be located at varying distances

[[Page 47805]]

behind the vessel (depending on time since deployment and vessel
speed), and the marine mammal sounds received may be from several
kilometers away. Also, the sonobuoys are omnidirectional, with no
ability to determine the locations of the calling mammals. However, the
information about marine mammal presence gained from the sonobuoy
signals will supplement visual observations, which will often be
restricted by ice and/or poor visibility. The sonobuoys will provide a
means of detecting (calling) marine mammals over a larger and to some
degree different area than is monitored visually. Thus, the sonobuoys
will be useful in identifying the presence of marine mammals of various
species in different regions along the survey track, but not in
determining their specific locations relative to the airguns.

Reporting

UAF will submit a report to NMFS within 90 days after the end of
the cruise. The report will describe the operations that were conducted
and the marine mammals that were detected near the operations. The
report will provide 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 marine
mammal sightings (dates, times, locations, activities, associated
seismic survey activities). The report will also include estimates of
the amount and nature of potential ``take'' of marine mammals by
harassment or in other ways.

Estimates of Take by Harassment for the Arctic Ocean Seismic Survey

Given the requested mitigation (above), all anticipated takes
involve a temporary change in behavior that may constitute Level B
harassment. The mitigation measures will minimize or eliminate the
possibility of Level A harassment or mortality. UAF has calculated both
``best estimates'' and ``maximum estimates'' for the numbers of animals
that could be taken by Level B harassment during the proposed Arctic
Ocean seismic survey using data obtained during marine mammal surveys
in and near the Arctic Ocean (Stirling et al., 1982, Kingsley, 1986,
Christensen et al., 1992, Koski and Davis, 1994, Moore et al., 2000a,
Whitehead, 2002, and Moulton and Williams, 2003) and on estimates of
the sizes of the areas where effects could potentially occur (Table 2).
This section provides estimates of the number of potential
``exposures'' of marine mammals to sound levels [gteqt]160, the
criteria for the onset of Level B Harassment, by operations with the
two-G. gun array (500 in\3\) or the single Bolt airgun (1200 in\3\). No
animals are expected to exhibit responses to the sonars, sub-bottom
profiler, or pinger given their characteristics described previously
(e.g., narrow, downward-directed beam). Therefore, no additional
incidental takings are included for animals that might be affected by
the multi-beam sonars or 12-kHz pinger.
Table 2 incorporates corrected density estimates and provides the
best estimate of the numbers of each species that would be exposed to
seismic sounds greater than 160 dB. Estimates are based on
consideration of numbers of marine mammals that might be disturbed by
5164 km of seismic surveys across the Arctic Ocean, which includes a
25-percent allowance over the planned 4131-km track to allow for turns,
lines that might have to be repeated due to poor data quality, or for
minor changes to the survey design. A detailed description on the
methodology used by UAF to arrive at the estimates of Level B
harassment takes that are provided in Table 2 can be found in UAF's IHA
application for the Arctic Ocean survey.

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Effects on Cetaceans

Strong avoidance reactions by several species of mysticetes to
seismic vessels have been observed at ranges up to 6-8 km (3-4 nm) and
occasionally as far as 20-30 km (11-16 nm) from the source vessel,
although, the sources in these observations were more powerful than
those used in this project. However, reactions at the longer distances
appear to be atypical of most species and situations, particularly when
feeding whales are involved (Miller et al. 2005). Fewer than 66
mysticetes are expected to be encountered during the proposed survey in
the Arctic Ocean (Table 2) and disturbance effects would be confined to
shorter distances given the relatively low-energy acoustic source to be
used during this project. Also, based on calibration of 160-dB radii
data obtained in deep water (Tolstoy et al., 2004), the estimated
numbers presented in Table 2 are considered overestimates of actual
numbers that may be harassed.
Odontocete reactions to seismic pulses, or at least the reactions
of dolphins, are expected to extend to lesser distances than are those
of mysticetes. Odontocete low-frequency hearing is less sensitive than
that of mysticetes, and dolphins are often seen from seismic vessels.
In fact, there are documented instances of delphinids and Dall's
porpoise approaching active seismic vessels. However, dolphins, as well
as some other types of odontocetes, sometimes show avoidance responses
and/or other changes in behavior when near operating seismic vessels.
Taking into account the small total volume and relatively low sound
output of the sources proposed in this project, and the mitigation
measures that are planned, effects on cetaceans are generally expected
to be limited to avoidance of a small area around the seismic operation
and short-term changes in behavior, falling within the MMPA definition
of Level B harassment. Furthermore, the estimated

[[Page 47807]]

numbers of animals potentially exposed to sound levels sufficient to
cause appreciable disturbance are very low percentages of the affected
populations, as described below.
Based on the 160-dB criterion, the best estimates of the numbers of
individual cetaceans that may be exposed to sounds [gteqt]160 dB re 1
microPa (rms) represent < 1 percent of the populations of each species
in the Arctic Ocean and adjacent waters. For species listed as
endangered under the Endangered Species Act (ESA), estimates include no
exposure for North Atlantic right whales, humpback, sei whales, fin,
sperm, or blue whales; and [gteqt]0.6 percent of the Bering-Chukchi-
Beaufort bowhead whale population of >10,470+. In the cases of belugas,
narwhals and gray whales, the potential reactions are expected to
involve no more than very small numbers (29 to 35) of exposures.
Low numbers of monodontids may be exposed to sounds produced by the
1 or 2 airguns during the proposed seismic study, and the numbers
potentially affected are small relative to the population sizes. The
best estimates of the numbers of belugas and narwhals that might be
exposed to [gteqt]160 dB represent < 1 percent of their populations.
This assumes that narwhals encountered in the polar pack ice in the
central Arctic Ocean belong to the Baffin Bay Davis Strait population.
If they are actually members of the East Greenland population, then the
estimated size of that population is too low because it did not include
surveys of the central Arctic Ocean.Two estimates of the numbers of
marine mammals that might be exposed to sounds from the 2-G. gun array
or the single Bolt airgun during the 2005 trans-Arctic seismic survey
were presented in Table 2, depending on the density criteria used (best
vs. maximum). UAF requested ``take authorizations'' for each species
based on the estimated maximum number of exposures to [gteqt]160 dB re
1 microPa (rms), i.e., the highest of the various estimates. That
figure likely overestimates the actual number of animals that will be
exposed to the sound (see above). Their request included take of very
small numbers (5 or less each) of sperm whales, North Atlantic right
whales, humpback whales, sei whales, fin whales, and blue whales.
However, the NMFS Division of Endangered Species determined that the
Arctic seismic cruise was not likely to adversely affect those six
species, the NMFS Division of Permits, Conservation, and Education
concurred with their findings, and is, therefore, not authorizing take
under the MMPA. NMFS is authorizing the numbers of take of each of the
9 cetacean species listed in Table 2.
Mitigation measures such as controlled speed, course alteration,
observers, ramp ups, and shut downs when marine mammals are seen within
defined ranges should further reduce short-term reactions, and minimize
any effects on hearing. In all cases, the effects are expected to be
short-term, with no lasting biological consequence. In light of the
type of take expected and the small percentages of affected stocks of
cetaceans, the action is expected to have no more than a negligible
impact on the affected species or stocks of cetaceans.

Effects on Pinnipeds

Two pinniped species (ringed seal and bearded seal) are likely to
be encountered in the study area. Also, it is possible that a small
number (0-12) of harp seals, hooded seals, spotted seals, harbor seals,
or walruses may be encountered. An estimated 2373 individual ringed
seals and 111 bearded seals (< 0.5 percent their Arctic Ocean and
adjacent waters population) may be exposed to airgun sounds at received
levels greater than or equal to 160 dB re 1 microPa (rms) during the
seismic survey. It is probable that only a small percentage of those
individuals would actually be disturbed. NMFS is authorizing the
requested take for the pinniped species (Table 2). Effects are expected
to be limited to short-term and localized behavioral changes falling
within the MMPA definition of Level B harassment. As is the case for
cetaceans, the short-term exposures to sounds from the sources in this
project are not expected to result in any long-term consequences for
the individuals or their populations and the activity is expected to
have no more than a negligible impact on the affected species or stocks
of pinnipeds.

Effects on Polar Bears

Effects on polar bears are anticipated to be minor at most.
Although the best estimate of polar bears that will be encountered
during the survey is 16, almost all of these would be on the ice, and
therefore they would be unaffected by underwater sound from the
airgun(s). 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 far below the surface or for a long duration. Received levels
of airgun sound are reduced substantially just below the surface,
relative to those at deeper depths, because of the pressure release
effect at the surface.
Possible Effects of Activities on Marine Mammal Habitat
The proposed seismic survey will not result in any permanent impact
on habitats used by marine mammals, or to the food sources they
utilize. The main impact of the proposed activity will be temporarily
elevated noise levels and the associated direct effects on marine mammals.
One of the reasons for the adoption of airguns as the standard
energy source for marine seismic surveys was that they (unlike the
explosives used in the distant past) do not result in any appreciable
fish kill. Various experimental studies showed that airgun discharges
cause little or no fish kill, and that any injurious effects were
generally limited to the water within a meter or so of an airgun.
However, it has recently been found that injurious effects on captive
fish, especially on fish hearing, may occur at somewhat greater
distances than previously thought (McCauley et al., 2000a,b, 2002;
2003). Even so, any injurious effects on fish would be limited to short
distances from the source. Also, many of the fish that might otherwise
be within the injury-zone are likely to be displaced from this region
prior to the approach of the airguns through avoidance reactions to the
passing seismic vessel or to the airgun sounds as received at distances
beyond the injury radius.
Fish often react to sounds, especially strong and/or intermittent
sounds of low frequency. Sound pulses at received levels of 160 dB re 1
microPa (peak) may cause subtle changes in behavior. Pulses at levels
of 180 dB (peak) may cause noticeable changes in behavior (Chapman and
Hawkins, 1969; Pearson et al., 1992; Skalski et al., 1992). It also
appears that fish often habituate to repeated strong sounds rather
rapidly, on time scales of minutes to an hour. However, the habituation
does not endure, and resumption of the disturbing activity may again
elicit disturbance responses from the same fish.
Fish near the airguns are likely to dive or exhibit some other kind
of behavioral response. This might have short-term impacts on the
ability of cetaceans to feed near the survey area. However, only a
small fraction of the available habitat would be ensonified at any
given time, and fish species would return to their pre-disturbance
behavior once the seismic activity ceased. Thus, the proposed surveys
would have little impact on the abilities of marine mammals to feed in
the area where seismic work is planned. Some of the fish that do not
avoid the approaching

[[Page 47808]]

airguns (probably a small number) may be subject to auditory or other
injuries.
Zooplankton that are very close to the source may react to the
airgun's shock wave. These animals have an exoskeleton and no air sacs;
therefore, little or no mortality is expected. Many crustaceans can
make sounds and some crustacea and other invertebrates have some type
of sound receptor. However, the reactions of zooplankton to sound are
not known. Some mysticetes feed on concentrations of zooplankton. A
reaction by zooplankton to a seismic impulse would only be relevant to
whales if it caused a concentration of zooplankton to scatter. Pressure
changes of sufficient magnitude to cause this type of reaction would
probably occur only very close to the source, so few zooplankton
concentrations would be affected. Impacts on zooplankton behavior are
predicted to be negligible, and this would translate into negligible
impacts on feeding mysticetes.
Possible Effects of Activities on Subsistence Needs
Subsistence remains the basis for Alaska Native culture and
community. Subsistence hunting and fishing continue to be prominent in
the household economies and social welfare of some Alaskan residents,
particularly among those living in small, rural villages (Wolfe and
Walker, 1987). In rural Alaska, subsistence activities are often
central to many aspects of human existence, including patterns of
family life, artistic expression, and community religious and
celebratory activities.
Marine mammals are legally hunted in Alaskan waters near Barrow by
coastal Alaska Natives. Nearby communities with subsistence economies
include Barrow, Nuisqsut, and Kaktovik. Species hunted include bowhead
whales, beluga whales, ringed, spotted, and bearded seals, walrus, and
polar bears. In the Barrow area, bowhead whales provided approximately
69 percent of the total weight of marine mammals harvested from April
1987 to March 1990. During that time, on a numerical basis, ringed
seals were harvested the most frequently (394 animals). More detailed
information regarding the level of subsistence by species is provided
in the application (UAF, 2005).
In the event that both marine mammals and hunters would be near the
Healy when it begins operating north of Barrow, the proposed project
could potentially impact the availability of marine mammals for harvest
in a very small area immediately around the Healy. However, the
majority of marine mammals are taken by hunters are within
approximately 33 km (18 nm) off shore, and the Healy is expected to
commence the seismic survey more than 200 km (108 nm) offshore.
Operations in that area are scheduled to occur in August, and hunting
in offshore waters generally does not occur at that time of year (the
bowhead hunt near Barrow normally does not begin until more than a
month later). Considering that, and the limited times and location
where the planned seismic survey overlaps with hunting areas, the
proposed project is not expected to have an unmitigable adverse effect
on the availability of marine mammals for subsistence harvest.
In Norwegian waters, a limited amount of hunting takes place on or
near Svalbard. The human population of Svalbard is approximately 1700.
Of the marine mammals found near Svalbard only the minke whale, bearded
seal, and ringed seal may be taken by local hunters (the commercial
sealing grounds for harp and hooded seals are distant from Svalbard).
The seismic survey will terminate northwest of Svalbard territorial
waters. Any ship operations closer to Svalbard will be similar to those
of other vessels operating in the area, will not involve airgun
operations, and will not adversely impact subsistence harvests.

Endangered Species Act

Under section 7 of the ESA, NSF and the NMFS Division of Permits,
Conservation, and Education consulted with the NMFS Endangered Species
Division regarding take of ESA-listed species during this activity and
as a result of the issuance of an IHA under section 101(a)(5)(D) of the
MMPA for this activity. In a Biological Opinion (BO) issued on August
4, 2005, NMFS concluded that the UAF's 2005 seismic survey across the
Arctic and the issuance of the associated IHA are not likely to
jeopardize the continued existence of threatened or endangered species
(specifically the bowhead whale) under the jurisdiction of NMFS or
destroy or adversely modify any designated critical habitat. NMFS has
issued an incidental take statement (ITS) for the take of up to 238
bowhead whales, which contains reasonable and prudent measures with
implementing terms and conditions to minimize the effects of this take.
This IHA action is within the scope of the previously analyzed action
and does not change the action in a manner that was not considered
previously. The terms and conditions of the BO have been incorporated
into the IHA.

National Environmental Policy Act (NEPA)

NSF prepared an EA of a Marine Geophysical Survey by the Coast
Guard Cutter Healy Across the Arctic Ocean, August - September 2005 and
issued a Finding of No Significant Impact (FONSI) on June 7, 2005. NMFS
posted NSF's EA on the NMFS website concurrently with the Federal
Register receipt of application notice and received public comment on
both the proposed IHA and the EA. NMFS then adopted NSF's EA and issued
a FONSI on August 2, 2005. Therefore, preparation of an EIS on this
action is not required by section 102(2) of the NEPA or its
implementing regulations. A copy of the EA and FONSI are available upon
request (see ADDRESSES).

Conclusions

NMFS has determined that the impact of conducting the seismic
survey in the Arctic Ocean may result, at worst, in a temporary
modification in behavior (Level B Harassment) by certain species small
numbers of marine mammals. This activity is expected to result in no
more than a negligible impact on the affected species or stocks.
For reasons stated previously in this document, this determination
is supported by: (1) the likelihood that, given sufficient notice
through slow ship speed and ramp-up, marine mammals are expected to
move away from a noise source that is annoying prior to its becoming
potentially injurious; (2) recent research that indicates that TTS is
unlikely (at least in delphinids) until levels closer to 200-205 dB re
1 microPa are reached rather than 180 dB re 1 microPa; (3) the fact
that 200-205 dB isopleths would be well within 100 m (328 ft) of the
vessel; and (4) the likelihood that marine mammal detection ability by
trained observers is close to 100 percent during daytime and remains
high at night to that distance from the seismic vessel. As a result, no
take by injury or death is anticipated, and the potential for temporary
or permanent hearing impairment is very low and will be avoided through
the incorporation of the proposed mitigation measures mentioned in this
document.
While the number of potential incidental harassment takes will
depend on the distribution and abundance of marine mammals in the
vicinity of the survey activity, the number of potential harassment
takings is estimated to be small, and has been mitigated to the lowest
level practicable through incorporation of the measures mentioned
previously in this document.

[[Page 47809]]

The proposed seismic program will not interfere with any legal
subsistence hunts, since seismic operations will not be conducted in
the same space and time as the hunts in subsistence whaling and sealing
areas. Therefore, the issuance of an IHA for this activity will not
have an unmitigable adverse effect on any marine mammal species or
stocks used for subsistence purposes.

Authorization

NMFS has issued a 1-year IHA to UAF for the take, by harassment, of
small numbers of marine mammals incidental to conducting a low-
intensity oceanographic seismic survey in the Arctic Ocean, provided
the previously mentioned mitigation, monitoring, and reporting
requirements are incorporated. NMFS has determined that the proposed
activity would result in the harassment of small numbers of marine
mammals; would have no more than a negligible impact on the affected
marine mammal stocks; and would not have an unmitigable adverse impact
on the availability of species or stocks for subsistence uses.

Dated: August 4, 2005.
James H. Lecky,
Director, Office of Protected Resources, Mational Marine Fisheries Service.
[FR Doc. 05-16116 Filed 8-12-05; 8:45 am]
BILLING CODE 3510-22-C

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Small Takes of Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey Across the Arctic Ocean

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