[Federal Register Volume 63, Number 87 (Wednesday, May 6, 1998)]
[Notices]
[Pages 25015-25020]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-12001]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[I.D. 041598A]
Small Takes of Marine Mammals Incidental to Specified Activities;
Offshore Seismic Activities in the Beaufort Sea
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice of receipt of application and proposed authorization for
a small take exemption; request for comments.
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SUMMARY: NMFS has received a request from the BP Exploration (Alaska),
900 East Benson Boulevard, Anchorage, AK 99519 (BPXA) for a renewal of
an authorization to take small numbers of marine mammals by harassment
incidental to conducting seismic surveys in the Beaufort Sea in state
and Federal waters. Under the Marine Mammal Protection Act (MMPA), NMFS
is requesting comments on its proposal to authorize BPXA to
incidentally take, by harassment, small numbers of bowhead whales and
other marine mammals in the above mentioned areas during the open water
period of 1998.
DATES: Comments and information must be received no later than June 5,
1998.
ADDRESSES: Comments on the application should be addressed to
[[Page 25016]]
Michael Payne, Chief, Marine Mammal Division, Office of Protected
Resources, NMFS, 1315 East-West Highway, Silver Spring, MD 20910-3225.
A copy of the application, a 1996 environmental assessment (EA), the
1997 informal section 7 consultation, BPXA's 1997 90-day Report, and a
list of references used in this document may be obtained by writing to
this address or by telephoning one of the contacts listed here.
FOR FURTHER INFORMATION CONTACT: Kenneth R. Hollingshead, (301) 713-
2055, Brad Smith, (907) 271-5006.
SUPPLEMENTARY INFORMATION:
Background
Section 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.)
directs the Secretary of Commerce to allow, upon request, the
incidental, but not intentional taking 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.
Permission may be granted if NMFS finds that the taking will have a
negligible impact on the species or stock(s) and will not have an
unmitigable adverse impact on the availability of the species or
stock(s) for subsistence uses and that the permissible methods of
taking and requirements pertaining to the monitoring and reporting of
such taking are set forth.
On April 10, 1996 (61 FR 15884), NMFS published an interim rule
establishing, among other things, procedures for issuing incidental
harassment authorizations under section 101(a)(5)(D) of the MMPA for
activities in Arctic waters. For additional information on the
procedures to be followed for this authorization, please refer to that
document.
Summary of Request
On March 26, 1998, NMFS received an application from BPXA
requesting a 1-year renewal of its authorization for the harassment of
small numbers of several species of marine mammals incidental to
conducting seismic surveys during the open water season in the Beaufort
Sea between Harrison Bay and Camden Bay/Flaxman Island, AK. Weather
permitting, the survey is expected to take place between approximately
July 1 and October 20, 1998. A detailed description of the work
proposed for 1998 is contained in the application (BPXA, 1998) and is
available upon request (see ADDRESSES).
Description of Habitat and Marine Mammal Affected by the Activity
A detailed description of the Beaufort Sea ecosystem and its
associated marine mammals can be found in the EA prepared for this
authorization (BPXA, 1996b) or in other documents (Minerals Management
Service (MMS), 1992, 1996). This information is incorporated by
reference and need not be repeated here. A copy of the EA is available
upon request (see ADDRESSES).
Marine Mammals
The Beaufort/Chukchi Seas support a diverse assemblage of marine
mammals, including bowhead whales (Balaena mysticetus), gray whales
(Eschrichtius robustus), belukha (Delphinapterus leucas), ringed seals
(Phoca hispida), spotted seals (Phoca largha) and bearded seals
(Erignathus barbatus). Descriptions of the biology and distribution of
these species and of others can be found in several other documents
(BPXA, 1996b, 1998; Lentfer, 1988; MMS, 1992, 1996; Small and DeMaster,
1995; Hill et al., 1997). Please refer to those documents for
information on these species.
Potential Effects of Seismic Surveys on Marine Mammals
Disturbance by seismic noise is the principal means of taking by
this activity. Support vessels and aircraft will provide a secondary
source of noise. The physical presence of vessels and aircraft could
also lead to non-acoustic effects involving visual or other cues.
Seismic surveys are used to obtain data about formations several
thousands of feet deep. The proposed seismic operation is an ocean
bottom cable (OBC) survey. OBC surveys involve dropping cables from a
ship to the ocean bottom, forming a patch consisting of 6 cables 5.9
kilometers (km) (3.7 mi) long, separated 660 m (2,165 ft) from each
other. Sensors (hydrophones) are attached to the cables. These
hydrophones are used to detect seismic energy reflected back from
underground rock strata. The original source of this energy is a
submerged acoustic source, called a seismic airgun array, that releases
compressed air into the water, creating an acoustical energy pulse that
is directed downward toward the seabed. Normally, 27 seismic lines are
run for each patch, covering an area 7.3 km by 8.6 km (4.5 mi by 5.3
mi), centered over the patch.
After sufficient data have been recorded to allow accurate mapping
of the rock strata, the cable is lifted onto the deck of a cable-
retrieval vessel, moved to a new location (ranging from several hundred
to a few thousand feet away), and placed onto the seabed again. For a
more detailed description of the seismic operation, including the sizes
of the various airguns, and for numbers of vessels planned for this
survey, please refer to the application (BPXA, 1998).
Depending upon ambient conditions and the sensitivity of the
receptor, underwater sounds produced by open water seismic operations
may be detectable a substantial distance away from the activity. Any
sound that is detectable is (at least in theory) capable of eliciting a
disturbance reaction by a marine mammal or of masking a signal of
comparable frequency (BPXA, 1998). An incidental harassment take is
presumed to occur when marine mammals in the vicinity of the seismic
source, the seismic vessel, other vessels, or aircraft react to the
generated sounds or to visual cues.
Seismic pulses are known to cause bowhead whales to behaviorally
respond within a distance of several kilometers (Richardson et al.,
1995). Although some limited masking of low-frequency sounds (e.g.,
whale calls) is a possibility, the intermittent nature of seismic
source pulses (1 second in duration every 6 to 12 seconds) will limit
the extent of masking. Bowhead whales are known to continue calling in
the presence of seismic survey sounds, and their calls can be heard
between seismic pulses (Richardson et al., 1986). Masking effects are
expected to be absent in the case of belukhas, given that sounds
important to them are predominantly at much higher frequencies than are
airgun sounds (BPXA, 1998).
Hearing damage is not expected to occur during the project. It is
not known whether a marine mammal very close to an airgun array would
be at risk of temporary or permanent hearing impairment, but temporary
threshold shift is a theoretical possibility for animals within a few
hundred meters (Richardson et al., 1995) of the source. However,
planned monitoring and mitigation measures (described later in this
document) are designed to detect marine mammals occurring near the
array and to avoid exposing them to sound pulses that have any
possibility of causing hearing damage.
When the received levels of noise exceed some behavioral reaction
threshold, cetaceans will show disturbance reactions (BPXA, 1998). The
levels, frequencies, and types of noise that will elicit a response
vary between
[[Page 25017]]
and within species, individuals, locations, and seasons. Behavioral
changes may be subtle alterations in surface, respiration, and dive
cycles. More conspicuous responses include changes in activity or
aerial displays, movement away from the sound source, or complete
avoidance of the area. The reaction threshold and degree of response
are related to the activity of the animal at the time of the
disturbance. Whales engaged in active behaviors, such as feeding,
socializing, or mating, are less likely than resting animals to show
overt behavioral reactions, unless the disturbance is directly
threatening (BPXA, 1998).
Bowhead Whales
Various studies (Reeves et al., 1984, Fraker et al., 1985,
Richardson et al., 1986, Ljungblad et al., 1988) have reported that,
when an operating seismic vessel approaches within a few kilometers,
most bowhead whales exhibit strong avoidance behavior and changes in
surfacing, respiration, and dive cycles. Bowheads exposed to seismic
pulses from vessels more than 7.5 km (4.5 mi) away rarely showed
observable avoidance of the vessel, but their surface, respiration, and
dive cycles appeared altered in a manner similar to that observed in
whales exposed at a closer distance (BPXA, 1996a, 1996b, 1998).
Within a 6-99 km (3.7-60 mi) range, it has not been possible to
determine a specific distance at which subtle behavioral changes no
longer occur (Richardson and Malme, 1993), given the high variability
observed in bowhead whale behavior (BPXA, 1996a, 1996b). Analysis of
the results from BPXA's 1996 seismic monitoring program does not
provide conclusive evidence about the radius of avoidance of bowheads
to the seismic program. The peak number of bowhead sightings was 10-20
km (6.2-12.3 mi) from shore during no-seismic periods and 20-30 km
(12.3-18.6 mi) from shore during periods that may have been influenced
by seismic noise. This difference was not statistically significant,
but the low numbers of sightings preclude meaningful interpretation
(BPXA, 1998).
Inupiat whalers believe that migrating bowheads are sometimes
displaced at distances considerably greater than 6 to 8 km (3.7 to 5.0
mi)(Rexford, 1996). Scientific studies done to date have limitations as
discussed in part by Moore and Clark (1992) and MMS (1996). It is
possible that, when additional data are available, it will be
demonstrated that bowheads sometimes do avoid seismic vessels at
distances beyond 6 to 8 km (3.7 to 5.0 mi). Also, whalers have
mentioned that bowheads sometimes seem more ``skittish'' and more
difficult to approach when seismic exploration is underway in the area.
This ``skittish'' behavior may be related to the observed subtle
changes in the behavior of bowheads exposed to seismic pulses from
distant seismic vessels (Richardson et al., 1986).
Gray Whales
The reactions of gray whales to seismic pulses are similar to those
of bowheads. Migrating gray whales along the California coast were
noted to slow their speed of swimming, turn away from seismic noise
sources, and increase their respiration rates. Malme et al. (1983,
1984, 1988) concluded that approximately 50 percent showed avoidance
when the average received pulse level was 170 dB (re 1 Pa @ 1
m). By some behavioral measures, clear effects were evident at average
pulse levels of 160+dB; less consistent results were suspected at
levels of 140-160 dB.
Belukha
The belukha is the only species of toothed whale (Odontoceti)
expected to be encountered in the Beaufort Sea. Because their hearing
threshold at frequencies below 100 Hz (where most of the energy from
airgun arrays is concentrated) is poor (125 dB re 1 Pa @ 1 m)
or more depending upon frequency (Johnson et al., 1989; Richardson et
al., 1991, 1995), belukha are not predicted to be strongly influenced
by seismic noise. However, because of the high source levels of seismic
pulses, airgun sounds may be audible to belukha at distances of 100 km
(Richardson and Wursig, 1997). The reaction distance for belukha,
although presently unknown, is expected to be less than that for
bowheads, given the presumed poorer sensitivity of belukhas than that
of bowheads for low-frequency sounds (BPXA, 1998).
Ringed, Largha and Bearded Seals
No detailed studies of reactions by seals to noise from open water
seismic exploration have been published (Richardson et al., 1995).
However, there are some data on the reactions of seals to various types
of impulsive sounds (J. Parsons as quoted in Greene, et al. 1985;
Anon., 1975; Mate and Harvey, 1985). These studies indicate that ice
seals typically either tolerate or habituate to seismic noise produced
from open water sources.
Underwater audiograms have been obtained using behavioral methods
for three species of phocinid seals, ringed, harbor, and harp seals
(Pagophilus groenlandicus). These audiograms were reviewed in
Richardson et al. (1995). Below 30-50 kHz, the hearing threshold of
phocinids is essentially flat down to at least 1 kHz and ranges between
60 and 85 dB (re 1 Pa @ 1 m). There are few data on hearing
sensitivity of phocinid seals below 1 kHz. NMFS considers harbor seals
to have a hearing threshold of 70-85 dB at 1 kHz (60 FR 53753, October
17, 1995), and recent measurements for a harbor seal indicate that,
below 1 kHz, its thresholds deteriorate gradually to 97 dB (re 1
Pa @ 1 m) at 100 Hz (Kastak and Schusterman, 1995a, b).
Because no studies to date have focused on pinniped reaction to
underwater noise from pulsed, seismic arrays in open water (Richardson
et al., 1991, 1995), as opposed to in-air exposure to continuous noise,
substantive conclusions are not possible at this time. However,
assuming a sound pressure level of 80-100 dB over its threshold is
needed in order to cause annoyance and 130 dB for injury (pain), as is
the current thought based upon human studies (Advanced Research
Projects Agency and NMFS, 1995), it appears unlikely that pinnipeds
would be harassed or injured by low frequency sounds from a seismic
source unless they were within close proximity of the array. For
permanent injury, pinnipeds would likely need to remain in the high-
noise field for extended periods of time. Existing evidence also
suggests that, while they may be capable of hearing sounds from seismic
arrays, seals appear to tolerate intense pulsatile sounds without known
effect once they learn that there is no danger associated with the
noise (see, for example, NMFS/Washington Department of Wildlife, 1995).
In addition, they will apparently not abandon feeding or breeding areas
due to exposure to these noise sources (Richardson et al., 1991) and
may habituate to certain noises over time. Since seismic work is fairly
common in Beaufort Sea waters, pinnipeds have been previously exposed
to seismic noise and may not react to it after initial exposure.
Other Effects
For a discussion on the anticipated effects of ships, boats,
aircraft, and smaller acoustic devices, such as single airguns,
sparkers, sub-bottom profilers, side-scan sonar, and bathymetric
sounders, on marine mammals and their food sources, please refer to the
application (BPXA, 1998). Information on these effects is incorporated
in this document by reference (see BPXA, 1998). Numbers of Marine
Mammals Expected to be Taken
[[Page 25018]]
BPXA estimates that the following numbers of marine mammals may be
subject to Level B harassment, as defined in 50 CFR 216.3:
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Harassment takes in
1998
Species Population size -----------------------
Possible Probable
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Bowhead...................................... 8,000.................................... 800 <400 gray="" whale...................................="" 23,000...................................=""><10 0="" belukha......................................="" 41,610...................................="" 250=""><150 ringed="" seal..................................="" 1-1.5="" million............................="" 400=""><400 spotted="" seal.................................="">200,000................................. 10 <5 bearded="" seal.................................="">300,000................................. 50 <30 ----------------------------------------------------------------------------------------------------------------="" effects="" of="" seismic="" noise="" and="" other="" activities="" on="" subsistence="" needs="" the="" disturbance="" and="" potential="" displacement="" of="" marine="" mammals="" by="" sounds="" from="" seismic="" activities="" are="" the="" principle="" concerns="" related="" to="" subsistence="" use="" of="" the="" area.="" the="" harvest="" of="" marine="" mammals="" (mainly="" bowhead="" whales,="" ringed="" seals,="" and="" bearded="" seals)="" is="" central="" to="" the="" culture="" and="" subsistence="" economies="" of="" the="" coastal="" north="" slope="" communities="" (bpxa,="" 1998).="" in="" particular,="" if="" migrating="" bowhead="" whales="" are="" displaced="" farther="" offshore="" by="" elevated="" noise="" levels,="" the="" harvest="" of="" these="" whales="" could="" be="" more="" difficult="" and="" dangerous="" for="" hunters.="" the="" harvest="" could="" also="" be="" affected="" if="" bowheads="" become="" more="" skittish="" when="" exposed="" to="" seismic="" noise="" (bpxa,="" 1998).="" nuiqsut="" is="" the="" community="" closest="" to="" the="" area="" of="" the="" proposed="" activity,="" and="" it="" harvests="" bowhead="" whales="" only="" during="" the="" fall="" whaling="" season.="" in="" recent="" years,="" nuiqsut="" whalers="" typically="" take="" zero="" to="" four="" whales="" each="" season="" (bpxa,="" 1998).="" nuiqsut="" whalers="" concentrate="" their="" efforts="" on="" areas="" north="" and="" east="" of="" cross="" island,="" generally="" in="" water="" depths="" greater="" than="" 20="" m="" (65="" ft).="" cross="" island,="" the="" principle="" field="" camp="" location="" for="" nuiqsut="" whalers,="" is="" located="" within="" the="" general="" area="" of="" the="" proposed="" seismic="" area.="" thus,="" the="" possibility="" and="" timing="" of="" potential="" seismic="" operations="" in="" the="" cross="" island="" area="" requires="" bpxa="" to="" provide="" nmfs="" with="" a="" plan="" of="" cooperation="" (also="" called="" the="" communications="" and="" avoidance="" agreement)="" with="" north="" slope="" borough="" residents="" to="" avoid="" any="" unmitigable="" adverse="" impact="" on="" subsistence="" needs.="" whalers="" from="" the="" village="" of="" kaktovik="" search="" for="" whales="" east,="" north,="" and="" west="" of="" the="" village.="" kaktovik="" is="" located="" 60="" mi="" (38="" km)="" east="" of="" the="" easternmost="" end="" of="" the="" planned="" seismic="" exploration="" area.="" the="" westernmost="" reported="" harvest="" location="" was="" about="" 21="" km="" (13="" mi)="" west="" of="" kaktovik,="" near="" 70="" deg.10'n,="" 144="" deg.w="" (kaleak,="" 1996).="" that="" site="" is="" approximately="" 40="" km="" (25="" mi)="" east="" of="" the="" closest="" part="" of="" the="" planned="" seismic="" exploration="" area="" for="" 1998="" (bpxa,="" 1998).="" whalers="" from="" the="" village="" of="" barrow="" search="" for="" bowhead="" whales="" much="" further="" from="" the="" planned="" seismic="" area,="">200 km (>125 mi) west (BPXA,
1998).
The location of the proposed seismic activity is south of the
center of the westward migration route of bowhead whales, but there is
some overlap. BPXA (1998) believes that, although whales may be able to
hear the sounds emitted by the seismic array out to a distance of 50 km
(30 mi) or more, it is unlikely that changes in migration route will
occur at distances of >25 km (>15 mi). Alternatively, whalers believe
that bowheads begin to divert from their normal migration path more
than 48 km (35 mi) away (MMS, 1996).
It is recognized that it is difficult to determine the maximum
distance at which reactions occur (Moore and Clark, 1992). As a result,
BPXA is developing a Communications and Avoidance Agreement with the
whalers to reduce potential interference with the hunt. Also, it is
believed that the monitoring plan proposed by BPXA (LGL Ltd. and
Greeneridge Sciences Inc, 1998) will provide information that will help
resolve uncertainties about the effects of seismic exploration on the
accessibility of bowheads to hunters.
While seismic exploration has some potential to influence
subsistence seal hunting activities, the peak season for seal hunting
is during the winter months when the harvest consists almost
exclusively of ringed seals (BPXA, 1998). In summer, boat crews hunt
ringed, spotted and bearded seals (BPXA, 1998). The most important
sealing area for Nuiqsut hunters is off the Colville delta, extending
as far west as Fish Creek and as far east as Pingok Island (BPXA,
1998). This area overlaps with the westernmost portion of the planned
seismic area. In this area, during summer, sealing occurs by boat when
hunters apparently concentrate on bearded seals (BPXA, 1998).
Mitigation
BPXA proposes to continue the mitigation program carried out in
1996 and 1997. BPXA plans to use biological observers to monitor marine
mammal presence in the vicinity of the seismic array. To avoid the
potential for serious injury to marine mammals, BPXA will power down
the seismic source if pinnipeds are sighted within the area delineated
by the 190 dB isopleth or:
(1) within 60 m (197 ft) of a single airgun or an array of
60 in3.
(2) within 110 m (361 ft) of an array >60 in3 and
720 in3 at <2.5 m="" (8.3="" ft)="" depth;="" (3)="" within="" 190="" m="" (623="" ft)="" of="" an="" array="">60 in3 and
720 in3 operating at 2.5 m (8.3 ft)
depth;
(4) within 150 m (492 ft) of an array >720 in3 and
840 in3 operating at <2.5 m="" (8.3="" ft)="" depth;="" (5)="" within="" 250="" m="" (820="" ft)="" of="" an="" array="">720 in3 and
840 in operating at 2.5 m (8.3 ft)
depth;
(6) within 260 m (853 ft) of an array >840 in\3\ operating at
2.5 m (8.3 ft) depth; and
(7) within 130 m (426 ft) of an array >840 in\3\ operating at >2.5
m (8.3 ft) depth.
BPXA will power down the seismic source if bowhead, gray, or
belukha whales are sighted within the area delineated by the 180 dB
isopleth or:
(1) within 160 m (525 ft) of a single airgun or an array of
60 in\3\;
(2) within 600 m (1,928 ft) of an array >60 in\3\ and
720 in\3\ at >2.5 m (8.3 ft) depth;
(3) within 800 m (2,625 ft) of an array >60 in\3\ and
720 in\3\ operating at 2.5 m (8.3 ft) depth;
(4) within 700 m (2,298 ft) of an array >720 in\3\ and
840 in\3\ operating at <2.5 m="" (8.3="" ft)="" depth;="" (5)="" within="" 900="" m="" (2,953="" ft)="" of="" an="" array="">720 in\3\ and
840 in\3\ operating at 2.5 m (8.3 ft) depth;
(6) within 1020 m (3,346 ft) of an array >840 in\3\ operating at
2.5 m (8.3 ft) depth; and
[[Page 25019]]
(7) within 640 m (2,100 ft) of an array >840 in\3\ operating at
>2.5 m (8.3 ft) depth.
In addition, BPXA proposes to ramp-up the seismic source to
operating levels at a rate no greater than 6 dB/min. If the array
includes airguns of different sizes, the smallest gun will be fired
first. Additional guns will be added at intervals appropriate to limit
the rate of increase in source level to a maximum of 6 dB/min.
Monitoring
As part of its application, BPXA provided a monitoring plan for
assessing impacts to marine mammals from seismic surveys in the
Beaufort Sea. This monitoring plan is described in detail in BPXA
(1998) and LGL Ltd. and Greeneridge Sciences Inc. (1998). As required
by the MMPA, this monitoring plan will be subject to a peer-review
panel of technical experts prior to formal acceptance by NMFS.
Preliminarily, BPXA plans to conduct the following
Vessel-Based Visual Monitoring
A minimum of two biologist-observers aboard each seismic vessel
will search for and observe marine mammals whenever seismic operations
are in progress, and for at least 30 minutes prior to planned start of
shooting. These observers will scan the area immediately around the
vessels with reticulated binoculars during the daytime and with night-
vision equipment during the night (prior to mid-August, there are no
hours of darkness). Individual watches will normally be limited to no
more than 4 consecutive hours. 1
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\1\ Because individual watches will normally be limited to no
more than 4 consecutive hours, NMFS believes that no seismic vessel
(including those conducting shallow-hazards surveys) will be able to
operate with fewer than two observers, unless surveys are shorter
than 4 consecutive hours.
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When mammals are detected within a safety zone designated to
prevent injury to the animals (see Mitigation), the geophysical crew
leader will be notified so that shutdown procedures can be implemented
immediately.
Aerial Surveys
From September 1, 1998, until 3 days after the seismic program
ends, aerial surveys will be conducted daily, weather permitting. The
primary objective will be to document the occurrence, distribution, and
movements of bowhead and belukha whales in and near the area where they
might be affected by the seismic pulses. These observations will be
used to estimate the level of harassment takes and to assess the
possibility that seismic operations affect the accessibility of bowhead
whales for subsistence hunting. Pinnipeds will be recorded when seen.
Aerial surveys will be at an altitude of 300 m (1,000 ft) above sea
level. BPXA proposes to avoid overflights of the Cross Island area
where whalers from Nuiqsut are based during their fall whale hunt.
Consistent with the 1996 and 1997 aerial surveys, the daily aerial
surveys are proposed to cover two grids: (1) A grid of 12 north-south
lines spaced 8 km (5 mi) apart and extending from about 20 km (12.5 mi)
west of the western side of the then-current seismic exploration area
to 50 km (30 mi) east of its eastern edge, and from the barrier islands
north to approximately the 100 m (328 ft) depth contour; and (2) a grid
of 4 survey lines within the above region, also spaced 8 km (5 mi)
apart and mid-way between the longer lines, to provide more intensive
coverage of the area of the seismic operations and immediate
surrounding waters.
When the seismic program is relocated east or west along the coast
during the 1998 season, both survey grids will be relocated a
corresponding distance along the coast. Information on the survey
program can be found in BPXA (1998) and in LGL Ltd. and Greeneridge
Sciences Inc. (1998), which are incorporated herein by reference.
Acoustical Measurements
The acoustic measurement program proposed for 1998 is designed to
be a sequel to the program conducted in 1996 and 1997 (see BPXA, 1996a,
1997, and 1998; LGL Ltd. and Greeneridge Sciences Inc., 1996, 1997, and
1998). The acoustic measurement program is planned to include (1)
retrieval of autonomous seafloor acoustic recorders (ASARs) deployed
and not recovered in 1997 and analysis of usable data contained in
those recorders, (2) deployment of ASARs during the 1998 seismic
program to provide continuous acoustic data for extended periods, (3)
boat-based acoustic measurements, (4) OBC-based acoustic measurements,
and (5) use of air-dropped sonobuoys.
The boat-based acoustical measurement program is proposed for a 7-
day period in August 1998. The objectives of this survey will be as
follows: (1) To measure the levels and other characteristics of the
horizontally propagating seismic survey sounds from the type(s) of
airgun array(s) to be used in 1998 as a function of distance and aspect
relative to the seismic source vessel(s) and to water depth.
(2) To measure the levels and frequency composition of the vessel
sounds emitted by vessels used regularly during the 1998 program,
excluding vessels whose sounds were characterized adequately in
previous years.
(3) To obtain additional site-specific ambient noise data, which
determine signal-to-noise ratios for seismic and other acoustic signals
at various ranges from their sources. This aspect of the monitoring is
described in more detail in BPXA (1998) and LGL Ltd. and Greeneridge
Sciences Inc. (1998).
Estimates of Marine Mammal Take
Estimates of takes by harassment will be made through vessel and
aerial surveys. Preliminarily, BPXA will estimate the number of (a)
marine mammals observed within the area ensonified strongly by the
seismic vessel; (b) marine mammals observed showing apparent reactions
to seismic pulses (e.g., heading away from the seismic vessel in an
atypical direction); (c) marine mammals subject to take by type (a) or
(b) above when no monitoring observations were possible; and (d)
bowheads displaced seaward from the main migration corridor.
Reporting
BPXA will provide an initial report on 1998 activities to NMFS
within 90 days of the completion of the seismic program. This report
will provide dates and locations of seismic operations, details of
marine mammal sightings, estimates of the amount and nature of all
takes by harassment, and any apparent effects on accessibility of
marine mammals to subsistence users.
A final technical report will be provided by BPXA within 20 working
days of receipt of the document from the contractor, but no later than
April 30, 1999. The final technical report will contain a description
of the methods, results, and interpretation of all monitoring tasks.
Consultation
Under section 7 of the Endangered Species Act (ESA), NMFS completed
an informal consultation on the issuance of an incidental harassment
authorization for this activity on June 26, 1997. A copy of that
document is available upon request (see ADDRESSES). If an authorization
to incidentally harass listed marine mammals is issued under the MMPA,
NMFS will issue an Incidental Take Statement under section 7 of the
ESA.
National Environmental Policy Act (NEPA)
In conjunction with the 1996 notice of proposed authorization (61
FR 26501,
[[Page 25020]]
May 28, 1996), NMFS released an EA that addressed the impacts on the
human environment from issuance of the authorization and the
alternatives to the proposed action. No comments were received on that
document and, on July 18, 1996, NMFS concluded that neither
implementation of the proposed authorization to BPXA for the harassment
of small numbers of several species of marine mammals incidental to
conducting seismic surveys during the open water season in the U.S.
Beaufort Sea nor the alternatives to that action would significantly
affect the quality of the human environment. As a result, the
preparation of an environmental impact statement on this action is not
required by section 102(2) of NEPA or its implementing regulations. A
copy of the EA is available upon request (see ADDRESSES).
This year's activity is a continuation of the seismic work
conducted in 1996 and 1997. For BPXA's 1998 application, NMFS has
conducted a review of the impacts expected from the issuance of an
Incidental Harassment Authorization in comparison to those impacts
evaluated in 1996. As assessed in detail in this document, NMFS has
preliminarily determined that there will be no more than a negligible
impact on marine mammals from the issuance of the harassment
authorization and that there will not be any unmitigable impacts to
subsistence communities, provided the mitigation measures required
under the authorization are implemented. Because the activity is
substantially the same as the one conducted in 1996 and no new impacts
on the environment have been identified, a new EA is not warranted.
Conclusions
NMFS has preliminarily determined that the short-term impact of
conducting seismic surveys in the U.S. Beaufort Sea will result, at
worst, in a temporary modification in behavior by certain species of
cetaceans and possibly pinnipeds. While behavioral modifications may be
made by these species to avoid the resultant noise, this behavioral
change is expected to have a negligible impact on the animals.
As the number of potential incidental harassment takes will depend
on the distribution and abundance of marine mammals (which vary
annually due to variable ice conditions and other factors) in the area
of seismic operations, due to the distribution and abundance of marine
mammals during the projected period of activity and the location of the
proposed seismic activity in waters generally too shallow and distant
from the edge of the pack ice for most marine mammals of concern, the
number of potential harassment takings is estimated to be small. In
addition, no take by injury and/or death is anticipated, and the
potential for temporary or permanent hearing impairment will be avoided
through the incorporation of the mitigation measures mentioned in this
document. No rookeries, mating grounds, areas of concentrated feeding,
or other areas of special significance for marine mammals occur within
or near the planned area of operations during the season of operations.
Because bowhead whales are east of the seismic area in the Canadian
Beaufort Sea until late August/early September, seismic activities are
not expected to impact subsistence hunting of bowhead whales prior to
that date. After August 31, 1998, BPXA will initiate aerial survey
flights for bowhead whale assessments. Appropriate mitigation measures
to avoid an unmitigable adverse impact on the availability of bowhead
whales for subsistence needs will be the subject of consultation
between BPXA and subsistence users.
Also, while open-water seismic exploration in the U.S. Beaufort Sea
has some potential to influence seal hunting activities by residents of
Nuiqsut, because (1) the peak sealing season is during the winter
months, (2) the main summer sealing is off the Colville Delta), and (3)
the zone of influence by seismic sources on belukha and seals is fairly
small, NMFS believes that BPXA's seismic survey will not have an
unmitigable adverse impact on the availability of these stocks for
subsistence uses.
Proposed Authorization
NMFS proposes to issue an incidental harassment authorization for
the 1998 Beaufort Sea open water season for a seismic survey provided
the above mentioned mitigation, monitoring, and reporting requirements
are incorporated. NMFS has preliminarily determined that the proposed
seismic activity would result in the harassment of only small numbers
of bowhead whales, gray whales, and possibly belukha whales, bearded
seals, and largha seals; would have a negligible impact on these marine
mammal stocks; and would not have an unmitigable adverse impact on the
availability of marine mammal stocks for subsistence uses.
Information Solicited
NMFS requests interested persons to submit comments, and
information, concerning this request (see ADDRESSES).
Dated: May 1, 1998.
Patricia A. Montanio,
Deputy Director, Office of Protected Resources, National Marine
Fisheries Service.
[FR Doc. 98-12001 Filed 5-5-98; 8:45 am]
BILLING CODE 3510-22-P
