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.

SUMMARY:

NMFS has received a request from Western Geophysical/Western Atlas International of Houston, Texas (Western Geophysical) for 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 Western Geophysical 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 2000.

DATES:

Comments and information must be received no later than May 24, 2000.

ADDRESSES:

Comments on the application should be addressed to Donna Wieting, Chief, Marine Mammal Conservation Division, Office of Protected Resources, NMFS, 1315 East-West Highway, Silver Spring, MD 20910-3225. A copy of the application, the Technical Monitoring Plan, 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, ext 128, Brad Smith, (907) 271-5006.

SUPPLEMENTARY INFORMATION:

Background

Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) direct the Secretary of Commerce to allow, upon request, the incidental, but not intentional taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are issued or, if the taking is limited to harassment, notice of a proposed authorization is provided to the public for review.

Permission may be granted if NMFS finds that the taking will have no more than 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 (IHAs) 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 February 14, 2000, NMFS received an application from Western Geophysical 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 in the south central Beaufort Sea between western Camden Bay and Harrison Bay off Alaska. Weather permitting, the survey is expected to take place between approximately July 1 and mid- to late-October, 2000. However, only a small portion of this area will be surveyed this year. A detailed description of the work proposed for 2000 is contained in the application (Western Geophysical, 2000) which is available upon request (see ADDRESSES).

Description of Habitat and Marine Mammals Affected by the Activity

A detailed description of the Beaufort Sea ecosystem and its associated marine mammals can be found in several documents (Corps of Engineers, 1999; NMFS, 1999; Minerals Management Service (MMS), 1992, 1996) and does not need to be repeated here.

Marine Mammals

The Beaufort/Chukchi Seas support a diverse assemblage of marine mammals, including bowhead whales (Balaena mysticetus), gray whales (Eschrichtius robustus), beluga (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 NMFS (1999), Western Geophysical (2000), the annual monitoring reports for seismic surveys in the Beaufort Sea (LGL Ltd. and Greeneridge Sciences Inc, 1997, 1998, and 1999) and several other documents (Corps of Engineers, 1999; Lentfer, 1988; MMS, 1992, 1996; Hill et al., 1999). 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 may provide a potential secondary source of noise. The physical presence of vessels and aircraft could also lead to non-acoustic effects on marine mammals 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. For this activity, OBC surveys involve dropping cables from a ship to the ocean bottom, forming a patch consisting of 4 parallel cables 8.9 kilometers (km) (5.5 miles (mi)) long, separated by approximately 600 meters (m) (1,968 feet (ft)) from each other. Hydrophones and geophones, attached to the cables, are used to detect seismic energy reflected back from underground rock strata. The 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. The source level planned for this project—a maximum of 247 dB re 1 μPa-m or 22.3 bar-meters (zero to peak), or a maximum of 252 dB (re 1 μPa-m or 39 bar-meters (peak-to-peak)—will be from an airgun array with a air discharge volume of 1,210 in³. In addition to this seismic source, Western Geophysical also plans to use a 40-in³ airgun with a source level of 210 dB (re 1 μPa-m), a Sub-bottom Profiler, a Geo-pulse unit, and two side-scan sonar units, one of 100 kHz and a one of 500 kHz unit.

It is anticipated that the seismic vessel will sail along pre-plotted source lines arranged orthogonally to the OBCs. Each source line will be 5 km (3.1 mi) long and adjacent source lines will be approximately 500 m (1,640 ft) apart. There will be 34 source lines for each seismic patch. The overall grid of source lines for a given patch will be 4.7 km by 16.5 km (2.9 mi by 10.2 mi) and the source line for one patch will overlap with those for adjacent patches. Western Geophysical anticipates completing 18 patches during the 2000 open-water season.

After sufficient data have been recorded to allow accurate mapping of the rock strata, the cables are 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, please refer to Western Geophysical (2000).

Depending upon ambient noise 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 (Western Geophysical, 2000). 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 strong avoidance reactions by many of the bowhead whales occurring within a distance of a few kilometers, including changes in surfacing, respiration and dive cycles, and may sometimes cause avoidance or other changes in bowhead behavior at considerably greater distances (Richardson et al., 1995; Rexford, 1996; MMS, 1997). Results from the 1996-1998 BP and Western Geophysical seismic program monitoring indicate that most migrating bowheads deflected seaward to avoid an area within about 20 km (12.4 mi) of an active nearshore seismic operation, with the exception of a few closer sightings when there was an island or very shallow water between the seismic operations and the whales (Miller et al., 1998, 1999). The available data do not provide an unequivocal estimate of the distance at which approaching bowheads begin to deflect, but this may be on the order of 35 km (21.7 mi). It is also uncertain how far beyond (west of) the seismic operation the seaward deflection persists (Miller et al., 1999). Although very few bowheads approached within 20 km (12.4 mi) of the operating seismic vessel, the number of bowheads sighted within that area returned to normal within 12-24 hours after the airgun operations ended (Miller et al., 1999). Because recent seismic work have been conducted in shallow water, have been limited to a confined area at any one time, and have employed smaller arrays of airguns than those that were often used in the past, Western Geophysical believes that avoidance distances around nearshore seismic operations conducted this year will likely be less than those around some of the seismic operations conducted before 1996.

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 16 to 24 seconds, less than 7 percent)) 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 (Greene et al., 1999, Richardson et al., 1986). Masking effects are expected to be absent in the case of belugas, given that sounds important to them are predominantly at much higher frequencies than are airgun sounds (Western Geophysical, 2000).

Hearing damage is not expected to occur during the project. It is not positively known whether the hearing systems of marine mammals very close to an airgun 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 of the source (Richardson et al., 1995). However, planned monitoring and mitigation measures (described later in this document) are designed to avoid sudden onsets of seismic pulses at full power, to detect marine mammals occurring near the array, and to avoid exposing them to sound pulses that have any possibility of causing hearing impairment. Moreover, bowhead whales avoid an area many kilometers in radius around ongoing seismic operations, precluding any possibility of hearing damage.

When the received levels of noise exceed some behavioral reaction threshold, cetaceans will show disturbance reactions. The levels, frequencies, and types of noise that will elicit a response vary between 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.

Bowhead Whales

Studies conducted prior to 1996 (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. In these studies, bowheads exposed to seismic pulses from vessels more than 7.5 km (4.7 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 (Western Geophysical, 2000). In three studies of bowhead whales and one of gray whales during this period, surfacing-dive cycles were unusually rapid in the presence of seismic noise, with fewer breaths per surfacing and longer intervals between breaths (Richardson et al., 1986; Koski and Johnson, 1987; Ljungblad et al., 1988; Malme et al., 1988). This pattern of subtle effects was evident among bowheads 6 km to at least 73 km (3.7 to 45.3 mi) from seismic vessels. However, in the pre-1996 studies, active avoidance usually was not apparent unless the seismic vessel was closer than about 6 to 8 km (3.7 to 5.0 mi)(Western Geophysical, 2000).

Inupiat whalers believe that migrating bowheads are sometimes displaced at distances considerably greater than suggested by pre-1996 scientific studies (Rexford, 1996) previously mentioned in this document. Also, whalers believe that avoidance effects can extend out to distances on the order of 30 miles, and that bowheads exposed to seismic also are “skittish” and more difficult to approach. The “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 documented for bowheads during the 1980s. 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 of the migrating gray whales showed avoidance when the average received pulse level was 170 dB (re 1 μPa). 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. Recent research on migrating gray whales showed responses similar to those observed in the earlier research when the source was moored in the migration corridor 2 km (1.2 mi) from shore. However, when the source was placed offshore (4 km (2.5 mi) from shore) of the migration corridor, the avoidance response was not evident on track plots (Tyack and Clark. 1998).

Beluga

The beluga is the only species of toothed whale (Odontoceti) expected to be encountered in the Beaufort Sea. Belugas have poor hearing thresholds at frequencies below 200 Hz, where most of the energy from airgun arrays is concentrated. Their thresholds at these frequencies (as measured in a captive situation), are 125 dB re 1 μPa or more depending upon frequency (Johnson et al., 1989). Although not expected to be significantly affected by the noise, given the high source levels of seismic pulses, airgun sounds sometimes may be audible to beluga at distances of 100 km (62.1 mi)(Richardson and Wursig, 1997), and perhaps further if actual low-frequency hearing thresholds in the open sea are better than those measured in captivity (Western Geophysical, 2000). The reaction distance for beluga, although presently unknown, is expected to be less than that for bowheads, given the presumed poorer sensitivity of belugas than that of bowheads for low-frequency sounds (Western Geophysical, 2000).

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 (LGL and Greeneridge, 1997, 1998, 1999a; 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) and Kastak and Schusterman (1998). 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 μPa @ 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 μPa @ 1 m) at 100 Hz (Kastak and Schusterman, 1998).

While no detailed studies of reactions of seals from open-water seismic exploration have been published (Richardson et al., 1991, 1995), some data are available on the reactions of seals to various types of impulsive sounds (see LGL and Greeneridge, 1997, 1998, 1999a; Thompson et al. 1998). These references indicate that it is unlikely that pinnipeds would be harassed or injured by low frequency sounds from a seismic source unless they were within relatively close proximity of the seismic 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 seals may be capable of hearing sounds from seismic arrays, they 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.

For a discussion on the anticipated effects of ships, boats, and aircraft on marine mammals and their food sources, please refer to the application (Western Geophysical, 2000). Information on these effects is preliminarily adopted by NMFS as the best information available on this subject.

Numbers of Marine Mammals Expected to Be Taken

Western Geophysical estimates that the following numbers of marine mammals may be subject to Level B harassment, as defined in 50 CFR 216.3:

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, but also ringed and bearded seals) is central to the culture and subsistence economies of the coastal North Slope communities. 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.

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 two to four whales each season (Western Geophysical, 2000). 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 2000 seismic area. Thus, the possibility and timing of potential seismic operations in the Cross Island area requires Western Geophysical to provide NMFS with either a Plan of Cooperation with North Slope Borough residents or measures that have been or will be taken to avoid any unmitigable adverse impact on subsistence needs. Western Geophysical's application has identified those measures that will be taken to minimize any adverse effect on subsistence. In addition, the timing of seismic operations in and east of the Cross Island area will be addressed in a Conflict and Avoidance Agreement (C&AA) with the Nuiqsut whalers and the AEWC (Western Geophysical, 2000).

Whalers from the village of Kaktovik search for whales east, north, and west of the village. Kaktovik is located 60 km (37.3 mi) east of the easternmost end of Western Geophysical's planned 2000 seismic exploration area. The westernmost reported harvest location was about 21 km (13 mi) west of Kaktovik, near 70°10 N′, 144° W (Kaleak, 1996). That site is approximately 40 km (24.7 mi) east of the closest part of Western Geophysical's planned seismic exploration area for 2000 (Western Geophysical, 2000).

Whalers from the village of Barrow search for bowhead whales much further from the planned seismic area, >200 km (>125 mi) west (Western Geophysical, 2000).

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. Seismic monitoring results from 1996-1998 indicate that most bowheads avoid the area within about 20 km (12.4 mi) around the array when it is operating, and some avoid the area within 30 km (18.6 mi). In addition, bowheads may be able to hear the sounds emitted by the seismic array out to a distance of 50 km (31.1 mi) or more, depending on the ambient noise level and the efficiency of sound propagation along the path between the seismic vessel and the whale (Miller et al., 1997.

Western Geophysical (2000) believes it is unlikely that changes in migration route will occur at distances greater than 25 km (15.5 mi) from an array of maximum volume of 1,210 in³ operating in water less than 30 m (100 ft) deep. However, subtle changes in behavior might occur out to longer distances. Inupiat whalers believe that bowheads begin to divert from their normal migration path more than 35 miles away (MMS, 1997).

It is recognized that it is difficult to determine the maximum distance at which reactions occur (Moore and Clark, 1992). As a result, Western Geophysical will participate in a C&AA with the whalers to reduce any potential interference with the hunt. Also, it is believed that the monitoring plan proposed by Western Geophysical (2000) will provide information that will help resolve uncertainties about the effects of seismic exploration on the accessibility of bowheads to hunters.

Many Nuiqsut hunters hunt seals intermittently year round. However, during recent years, most seal hunting has been during the early summer in open water. In summer, boat crews hunt ringed, spotted, and bearded seals. 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. 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. However, these subsistence hunters have not perceived any interference between recent open-water seismic activities in the Alaskan Beaufort Sea. Therefore, because Western Geophysical is proposing similar mitigation and consultation procedures this year, it is unlikely that seismic activities would have more than a negligible impact on Nuiqsut seal hunting.

Mitigation

For the second year, Western Geophysical will reduce its airgun array from the 1,500 in³ used in 1998 to 1,210 in³. This reduction in source level will result in lower received levels and, therefore, smaller safety ranges and fewer takes by harassment than those in 1998. However, because the 1,210 in³ array is a subset (with some minor variations) of the 1,500 in³ array (with four guns not firing), NMFS again this year proposes to limit Western Geophysical's active airguns so that they do not exceed a capacity of 1,210 in³ during the 2000 open water seismic survey.

Vessel-based observers will monitor marine mammal presence in the vicinity of the seismic array throughout the seismic program. To avoid the potential for injury to seals, Western Geophysical proposes to immediately power down the seismic source if seals are sighted within the area delineated by the 190 dB isopleth. In water depth less than 10 m (33 ft), Western Geophysical will establish safety zones 240 m (787.4 ft) from the array when the array is operating at 5 m (16.4 ft) depth and 90 m (295.3 ft) from the array when it is operating at 2.3 m (7.5 ft) depth. In water depth greater than 10 m (33 ft), Western Geophysical will establish safety zones 260 m (853 ft) from the array when the array is operating at 5 m (16.4 ft) depth and 150 m (492 ft) from the array when it is operating at 2.3 m (7.5 ft) depth.

To avoid the potential for injury to whales, Western Geophysical will immediately power down the seismic source if bowhead, gray, or beluga whales are sighted within the area delineated by the 180 dB isopleth. In water depth less than 10 m (33 ft), Western Geophysical will establish safety zones 750 m (2,460.6 ft) from the array when the array is operating at 5 m (16.4 ft) depth and 360 m (1,181.1 ft) from the array when it is operating at 2.3 m (7.5 ft) depth. In water depth greater than 10 m (33 ft), Western Geophysical will establish safety zones 1000 m (3281 ft) from the array when the array is operating at 5 m (16.4 ft) depth and 600 m (1968.5 ft) from the array when it is operating at 2.3 m (7.5 ft) depth.

Different safety radii will be established for shallow-hazard survey operations. Received levels of sounds from a single 40 in³ airgun operating at a depth of 1 m (3 ft) are expected to diminish below 190 and 180 dB (re 1 μPa RMS) at distances of 22 m (72.2 ft), and 100 m (328.1 ft), respectively. These estimates are based on extensive measurements of sounds from operations with a single airgun and a small array of airguns in the same area during 1996-97 (Western Geophysical, 2000). Because the GeoPulse and the sub-bottom profiler will normally be operated simultaneously with the airgun, and, because these units are less powerful than the airgun, separate safety zones do not need to be established for them. As previously done, operations using these sources will be terminated whenever a seal or whale enters its respective safety zone.

Within the first 10 days of Beaufort Sea operations in 2000, Western Geophysical will measure and analyze the sounds from Western's 2000 array operating at both 5 m (16.4 ft) and 2 m (6.6 ft) depths. This information will be provided to NMFS, along with the contractor's recommendation as to whether any adjustments in the safety radii are needed to meet the 190 and 180 dB_rms shutdown criteria.

In addition, Western Geophysical proposes to ramp-up the 1,210 in³ seismic source to operating levels at a rate no greater than 6 dB/min anytime the array has not been firing for 1 minute at a vessel speed of 4 to 8 knots and 2 minutes at a vessel speed of 3 knots or slower. Ramp-up will begin with an air volume discharge not exceeding 80 in³ with additional guns added at intervals appropriate to limit the rate of increase to 6 dB/min. No ramp-up is proposed for the smaller acoustic sources.

Monitoring

As part of its application, Western Geophysical provided a monitoring plan for assessing impacts to marine mammals from seismic surveys in the Beaufort Sea. This monitoring plan is described in Western Geophysical (2000) and in LGL Ltd. (2000). 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.

Western Geophysical plans to conduct the following monitoring:

Vessel-based Visual Monitoring

It is proposed that one or two marine mammal observers aboard the seismic vessel will search for and observe marine mammals whenever seismic operations are in progress and for at least 30 minutes before the planned start of seismic transmissions. These observers will scan the area immediately around the vessels with reticle binoculars during the daytime. Laser rangefinding binoculars will be available to assist with distance estimation. After mid-August, when the duration of darkness increases, image intensifiers will be used by observers and additional light sources will be used to illuminate the safety zone (see application for more detail).

A total of four observers (three trained biologists and one Inupiat observer/communicator) will be based aboard the seismic vessel. As in 1999, the use of four observers is an increase over the three observers used in 1998 and will allow two observers to be on duty simultaneously for up to 50 percent of the active airgun hours. The use of two observers will increase the probability of detecting marine mammals, and two observers will be required to be on duty whenever the seismic array is ramped up. Individual watches will normally be limited to no more than 4 consecutive hours.

When mammals are detected within or about to enter the 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

Between September 1, 2000, until 1 day after the OBC seismic operations end or until September 15 (whichever comes first), aerial survey flights for bowhead whale assessments are proposed to be undertaken by Western Geophysical. If OBC seismic work is suspended during the bowhead subsistence hunting season, but resumes later in the autumn, aerial surveys will commence (or resume) when OBC seismic work resumes. Western Geophysical proposes to continue aerial surveys either until 1 day after OBC seismic work ends, or until a total of 15 days of aerial surveys have been conducted during September-October 2000, whichever comes first. It should be noted that the proposed duration for aerial surveys would be a reduction from previous years. Western Geophysical believes this reduction is appropriate because some of the main questions about disturbance to bowhead whales from a nearshore seismic operation have been answered through the 1996-1998 monitoring projects. In addition, MMS expects to conduct its broad-scale aerial survey work from approximately 31 August until the end of the bowhead migration in October. Western Geophysical believes that this combined aerial survey data will provide sufficient information to estimate the numbers of bowheads taken by harassment.

The primary objective of the aerial surveys will be to document the occurrence, distribution, and movements of bowhead, as well as beluga and gray, 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, although survey altitude will be too high for systematic surveys of seals.

Western Geophysical proposes to fly at 300 m (1,000 ft) in areas where no whaling is underway, but it may reduce that altitude to no less than 274 m (900 ft) under low cloud conditions. In addition, surveys will be flown at 457 m (1500 ft) altitude over areas where whaling is occurring on that date and will avoid direct overflights of whaleboats and Cross Island, where whalers from Nuiqsut are based during their fall whale hunt.

The daily aerial surveys are proposed to cover a grid of 18 north-south lines spaced 8 km (5 mi) apart and will extend seaward to about the 100 m (328 ft) depth contour (typically about 65 km (40.4 mi) offshore. This grid will extend from about 40 km (24.8 mi) east to 40 km (24.8 mi) west of the area in which seismic operations are underway on that date. This design will provide extended coverage to the west to determine the westward extent of the offshore displacement of whales by seismic. In 2000, no “intensive” grid surveys are planned to be conducted by Western Geophysical because very few whales occur within 20 km (12.4 mi) of the seismic operation.

Detailed information on the survey program can be found in Western Geophysical (2000) and in LGL Ltd. (2000), which are incorporated in this document by citation.

Acoustical Measurements

The acoustic measurement program proposed for 2000 is designed to be continue work conducted in 1996 through 1999 (see LGL and Greeneridge Sciences Inc., 1997, 1998, 1999). The acoustic measurement program is planned to include (1) vessel-based hydrophone measurements, (2) use of air-dropped sonobuoys during OBC operations in September and October, and (3) bottom-mounted acoustical recorders.

(1) If shallow-water hazards surveys are conducted, a vessel-based acoustical measurement program is proposed for a few days early in that program. The objectives of this survey will be as follows: (a) To measure the levels and other characteristics of the horizontally propagating sounds from the single airgun, GeoPulse, and sub-bottom profiler to be used in 2000 as a function of distance relative to the source and (b) to measure the levels and frequency composition of the vessel sounds emitted by vessels used regularly during Western's 2000 program in those cases where these vessels have not previously been measured adequately.

(2) Sonobuoys will be dropped and monitored from survey aircraft during September/October (if the seismic operations are continuing at that time). Sonobuoys will provide data on characteristics of seismic pulses (and signal-to-ambient ratios) at offshore locations, including some of the specific places where bowhead whales are observed.

(3) Autonomous seafloor acoustic recorders will be placed on the sea bottom at three locations to record low-frequency sounds continuously over an extended period of time (if seismic operations extend into September/October). The objective is to obtain continuous records of seismic sound pulses, ambient noise, and bowhead calls.

For a more detailed description of planned monitoring activities, please refer to the application and the Technical Monitoring Plan (Western Geophysical, 2000; LGL Ltd., 2000).

Estimates of Marine Mammal Take

Estimates of takes by harassment will be made through vessel and aerial surveys. Preliminarily, Western Geophysical 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) when no monitoring observations were possible; and (d) bowheads displaced seaward from the main migration corridor.

Reporting

Western Geophysical will provide an initial report on 2000 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 Western Geophysical within 20 working days of receipt of the document from the contractor, but no later than April 30, 2001. 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 IHA for similar activities on July 26, 1999. If an authorization to incidentally harass listed marine mammals is issued under the MMPA for this activity, 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, May 28, 1996) for open water seismic operations in the Beaufort Sea, 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 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.

In 1999, NMFS determined that a new EA was warranted based on the proposed construction of the Northstar project, the collection of data from 1996 through 1998 on Beaufort Sea marine mammals and the impacts of seismic activities on these mammals, and the analysis of scientific data indicating that bowheads avoid nearshore seismic operations by up to about 20 km (12.4 mi). Accordingly, a review of the impacts expected from the issuance of an IHA has been assessed in both the EA and in this document, and NMFS has 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. As a result, NMFS determined that neither implementation of the 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 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 additional NEPA documentation on this action is not required by section 102(2) of NEPA or by its implementing regulations.

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 by 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.

While 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. Between September 1, 2000, until 1 day after the OBC seismic operations end or until September 15 (whichever comes first), aerial survey flights for bowhead whale assessments are proposed to be undertaken by Western Geophysical. If OBC seismic work is suspended during the bowhead subsistence hunting season, but resumes later in the autumn, aerial surveys will commence (or resume) when OBC seismic work resumes. Western Geophysical proposes to continue aerial surveys either until 1 day after OBC seismic work ends, or until a total of 15 days of aerial surveys have been conducted during September-October 2000, whichever comes first. It should be noted that the proposed duration for aerial surveys would be a reduction from previous years. Western Geophysical believes this reduction is appropriate because some of the main questions about disturbance to bowhead whales from a nearshore seismic operation have been answered through the 1996-1998 monitoring projects. In addition, MMS expects to conduct its broad-scale aerial survey work from approximately August 31 until the end of the bowhead migration in October. Western Geophysical believes that this combined aerial survey data will provide sufficient information to estimate the numbers of bowheads taken by harassment.

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 Western Geophysical 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 beluga and seals is fairly small, NMFS believes that Western Geophysical'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 IHA for the 2000 Beaufort Sea open water season for a seismic survey, provided the previously 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, beluga whales, ringed seals, bearded seals, and possibly spotted seals and gray whales; would have no more than 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).