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. 050196A]

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 (BPX) for authorization

to take small numbers of marine mammals by harassment incidental to

conducting seismic surveys in the Northstar Unit, 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 BPX to

incidentally take, by harassment, small numbers of bowhead whales and

other marine mammals in the above mentioned area during the open water

period of 1996.

DATES: Comments and information must be received no later than June 27,

1996.

ADDRESSES: Comments on the application should be addressed to Chief,

Marine Mammal Division, Office of Protected Resources, National Marine

Fisheries Service, 1315 East-West Highway, Silver Spring, MD 20910-

3225. A copy of the application, an environmental assessment (EA), and

a list of references used in this document may be obtained by writing

to this address, by telephoning one of the contacts listed below or by

leaving a voice mail request at (301) 713-4070.

FOR FURTHER INFORMATION CONTACT: Kenneth R. Hollingshead, Office of

Protected Resources, NMFS, (301) 713-2055, Ron Morris, Western Alaska

Field Office, NMFS, (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), will not have an

unmitigable adverse impact on the availability of the species or

stock(s) for subsistence uses, and 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 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 18, 1996, NMFS received an application from BPX requesting

an authorization for the harassment of small numbers of several species

of marine mammals incidental to conducting seismic surveys during the

open water season within the Northstar Unit, located in the Beaufort

Sea in U.S. waters. The survey is expected to take place between

approximately July 20 and October 20, 1996. A detailed description of

the work planned is contained in the application (BPX 1996) 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 (SAIC 1996) or in other documents (Minerals Management

Service (MMS) 1992, 1996) 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 glacialis), gray whales

(Eschrichtius robustus), belukha (Delphinapterus leucas), ringed seals

(Phoca hispida), spotted seals (Phoca largha) and bearded seals

(Erignathus barbatus). Descriptions on the biology and distribution of

these species, and others, can be found in several other documents (BPX

1996, Lentfer 1988, MMS 1992, NMFS 1990 and 1996, Small and DeMaster

1995). 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. Vessel and aircraft will provide a secondary source of

noise.

Deep seismic surveys are used to obtain data about formations

several thousands of feet deep. The physical presence of vessels could

also lead to non-acoustic effects involving visual or other cues. These

surveys are accomplished by transmitting sound waves into the earth,

which are reflected

[[Page 26502]]

off subsurface formations and recorded with detectors in the water

column. A typical marine seismic source is an airgun array, which

releases compressed air into the water creating an acoustical energy

pulse that is directed downwards toward the seabed. Hydrophones spaced

along a streamer cable just below the surface of the water receive the

reflected energy from the subsurface formations and transmit data to

the seismic vessel. Onboard the vessel, the signals are amplified,

digitized, and recorded on magnetic tape.

Depending upon ambient conditions and the sensitivity of the

receptor, underwater sounds produced by open water seismic operations

may be detectable some 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 masking a signal of

comparable frequency (BPX 1996). An incidental harassment take is

presumed to occur when marine mammals in the vicinity of the seismic

source (or other vessels) react to the generated sounds or 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 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).

Hearing damage is not expected to occur during the project. It is

not known whether a marine mammal very close to an air gun 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). Planned monitoring and

mitigation measures (described below) 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 (BPX 1996). The

levels, frequencies, and types of noise that will elicit a response

vary between and within species, individuals, locations and season.

Behavioral changes may be subtle alterations in surface-dive-

respiration 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 (BPX 1996).

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 4.5 miles (7.5 km) 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 (BPX 1996).

Within a 3.7-60 mile (6-99 km) 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 (BPX 1996).

Gray Whales

The reactions of gray whales to seismic pulses is 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 about 50 percent showed avoidance when the

average received pulse level was 170 dB (re 1 Pa @ 1 m). Less

consistent results were indicated 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 its hearing

threshold at frequencies below 100 Hz (where most of the energy from

air gun arrays is concentrated) is poor (125 dB re 1 Pa @ 1 m)

or more depending upon frequency (Johnson et al. 1989 (as referenced in

BPX 1996), Richardson 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 large distances (Richardson 1991, 1995).

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 3 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 an sound pressure level needed to be 80-100 dB over its

threshold in order to cause annoyance and 130 dB for injury (pain), as

is the current thought based upon human studies (ARPA, 1995), then 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, marine mammals would 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/WDFW,

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 Western Beaufort Sea waters, pinnipeds have

previously been

[[Page 26503]]

exposed to seismic noise, and may not react to it, after initial

exposure.

Effects of Seismic Noise and other Activities on Subsistence Needs.

The disturbance and potential displacement of marine mammals by

sounds from seismic activities is the principle concern 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 (BPX 1996). Displacement of migrating marine mammals

farther offshore due to behavioral changes resulting from elevated

noise levels could potentially make harvest of these species more

difficult.

Nuiqsut is the community closest to the area of the proposed

activity, and only harvests bowhead whales during the fall whaling

season. Nuiqsut whalers typically take zero to three whales each

season, with a trend toward larger harvests in the most recent years

(BPX 1996). Nuiqsut whalers concentrate their efforts on areas north

and east of the Northstar Unit, generally in water depths greater than

65 ft (20 m). Cross Island, located 13 miles (20 km) east of the

eastern edge of the primary area of proposed activity, is the principle

field camp location for Nuiqsut whalers. Thus, most bowhead whales will

not enter the ensonified area until they have passed through the area

used by Nuiqsut whalers (BPX 1996).

The location of the proposed seismic activity is to the south of

the main westward migration route of bowhead whales. BPX believes that

although whales may be able to hear the sounds emitted by the seismic

array out to a distance of 30 miles (50 km) or more, it is unlikely

that changes in migration route will occur at distances of >15 miles

(>25 km). As discussed above, scientific studies have shown obvious

avoidance reactions at distances up to 3.7-5 miles (6-8 km), with one

probable case of avoidance at 15 miles (24 km)(Richardson et al. 1986,

Koski and Johnson 1987, Ljungblad et al. 1988). However, other bowheads

>3.7 miles (>6 km) from shallow-water seismic operations showed no

obvious avoidance (BPX 1996).

It is difficult to determine the maximum distance at which

reactions occur (Moore and Clark 1992), although whalers believe that

some migrating bowheads are deflected by seismic operations at

distances greater than those documented by scientific studies done to

date. As a result, BPX is developing a Communications and Avoidance

Agreement with the whalers (see BPX 1996) to reduce any potential

interference with the hunt. Also, it is believed that the monitoring

plan proposed by BPX (LGL 1996) will provide information that will help

resolve uncertainties about the effects of seismic exploration on the

accessibility of bowheads to hunters.

In addition, while seismic exploration in the Northstar Unit 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 (BPX 1996). In

summer, boat crews hunt ringed, spotted and bearded seals (BPX 1996).

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 (BPX 1996). In this area, during summer, sealing occurs by boat

when hunters apparently concentrate on bearded seals (BPX 1996).

Mitigation

BPX proposes 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, BPX will power down the seismic

source if pinnipeds are sighted within 500 ft (150 m) of the source or

if cetaceans are sighted within 2,130 ft (650 m) of the source. At 500

ft (150 m), the average pulse levels will be less than 190 dB (re 1

Pa @ 1 m). At 2,130 ft (650 m), the average pulse level is

expected to be about 180 dB (re 1 Pa @ 1 m), based on the

expected characteristics of the air gun array to be used in this

program, and on site-specific propagation loss data (from Miles et al.

1987).

In addition, NMFS proposes to require BPX to ramp-up the seismic

source from a level less than, or equal to, 160 dB to its operating

level immediately preceding transmissions at a rate not exceeding 6 dB/

min and to power-down the array to a level no greater than 160 dB

whenever marine mammals enter their respective safety zone. NMFS will

recommend ramp-up be accomplished through software designed to fire a

specified sequence of guns operating at a designated pressure until the

full array of guns are firing at peak operating pressure.

Monitoring

As part of their application, BPX provided a preliminary monitoring

plan for assessing impacts to marine mammals from seismic surveys in

the Beaufort Sea (LGL 1996). 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, BPX plans to conduct the following:

(1) Vessel-based Visual Monitoring

Two biologist-observers aboard the seismic vessel will search for

and observe marine mammals whenever seismic operations are in progress,

and immediately preceding the start of shooting. These observers will

scan the area immediately around the vessels with binoculars during the

daytime and with night vision equipment during the night. When mammals

are detected within a safety zone designated to prevent injury to the

animals, the geophysical crew leader will be notified so that shutdown

procedures can be implemented.

(2) Aerial Surveys

From September 1, 1996 until 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 for assessing the

possibility that seismic operations affect the accessibility of bowhead

whales for subsistence hunting. Pinnipeds will be recorded when seen,

and sonobuoys will be dropped to document ambient noise and

characteristics of seismic noise near whale sightings. Aerial surveys

will be at an altitude of 1,000 ft (300 m) above sea level. It is

tentatively proposed to avoid direct overflights of the Cross Island

area where whalers from Nuiqsut are based during their fall whale hunt.

The daily aerial surveys are proposed to cover two grids:

(a) A grid of 12 north-south lines spaced 8 km (5 miles) apart and

extending to about 30 mi (50 km) offshore, 30 mi (50 km) east, and 12.5

mi (20 km) west of the Northstar area;

(b) A grid of 8 north-south lines within the above region, also

spaced 5 mi (8 km) apart and mid-way between the longer lines, to

provide more intensive coverage of the area of the seismic operations

and immediate surrounding waters.

(3) Acoustical Measurements

A boat-based acoustical measurement program is proposed for a 10-

day period in mid- to late-August 1996. The objectives of this survey

will be as follows:

[[Page 26504]]

(a) To measure the levels and other characteristics of the

horizontally-propagating seismic survey sounds as a function of

distance and aspect relative to BPX's seismic source vessel.

(b) To measure acoustic transmission loss vs. frequency, distance,

and propagation direction in and near the Northstar Unit, based on

transmission and reception of standardized acoustic signals having a

source level of about 165 dB re 1 Pa @ 1 m. Transmissions will

not be done if bowheads are seen within 2,130 ft (650 m) of the seismic

array.

(c) 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.

In addition, data on ambient noise and on characteristics of

seismic pulses will be obtained from sonobuoys dropped and monitored

from the survey aircraft after September 1, 1996.

For a more detailed description of planned monitoring activities,

please refer to the application and supporting document (LGL 1996).

Reporting

BPX will provide an initial report 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 BPX within 20 working

days of receipt of the document from the contractor, but no later than

April 30, 1996. 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, NMFS has begun

consultation on the proposed issuance of this authorization.

Consultation will be concluded upon completion of the comment period

and consideration of those comments in the final determination on

issuance of an authorization.

National Environmental Policy Act

In conjunction with this notice, NMFS has released an EA that

addresses the impacts on the human environment from issuance of the

authorization and the alternatives to the proposed action. A copy of

the EA is available upon request (see ADDRESSES).

Conclusions

NMFS has preliminarily determined that the short-term impact of

conducting seismic surveys in the Northstar Unit of the Beaufort Sea

will result, at worst, in a temporary modification in behavior by

certain species of cetaceans. While behavioral modifications may be

made by these species of cetaceans 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 incorporation of the mitigation measures mentioned above.

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 September 1, 1996, BPX 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 BPX and subsistence users.

Also, while summer seismic exploration in the Northstar Unit 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 (west and

inshore of Northstar), and (3) the zone of influence by seismic sources

on belukha and seals is fairly small, NMFS believes the Northstar

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 1996 Beaufort Sea open water season for a seismic survey within the

Northstar Unit 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; will have a

negligible impact on these marine mammal stocks; and will not have an

unmitigable adverse impact on the availability of these stocks for

subsistence uses.

Information Solicited

NMFS requests interested persons to submit comments, information,

and suggestions concerning this request (see ADDRESSES).

Dated: May 17, 1996.

Patricia A. Montanio,

Acting Director, Office of Protected Resources, National Marine

Fisheries Service.

[FR Doc. 96-13287 Filed 5-23-96; 10:02 am]

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