Small Takes of Marine Mammals Incidental to Specified Activities; Offshore Seismic Activities in the Beaufort Sea

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.................................... 800 200,000................................. 10 300,000................................. 50 200 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 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 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 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]

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