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

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Information about this document as published in the Federal Register.

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National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.


Notice of issuance of an incidental harassment authorization.


In accordance with provisions of the Marine Mammal Protection Act (MMPA) as amended, notification is hereby given that an Incidental Harassment Authorization (IHA) to take small numbers of bowhead whales and other marine mammals by harassment incidental to conducting ocean bottom cable (OBC) seismic surveys in the Alaskan Beaufort Sea, has been issued to WesternGeco, LLC (formerly Western Geophysical) for the open water period of 2001.


Effective from July 31, 2001, until November 1, 2001.


The application, authorization, monitoring plan, Biological Opinion, and a list of references used in this document are available by writing to Donna Wieting, Chief, Marine Mammal Conservation Start Printed Page 42516Division, Office of Protected Resources, NMFS, 1315 East-West Highway, Silver Spring, MD 20910-3225, or by telephoning one of the contacts listed here.

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Simona Perry Roberts, Office of Protected Resources (301) 713-2322, ext. 106, or Brad Smith, Alaska Region (907) 271-5006.

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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 50 CFR 216.107.

Summary of Request

On April 16, 2001, NMFS received an application from WesternGeco requesting an authorization for the harassment of small numbers of several species of marine mammals incidental to conducting OBC seismic surveys during the open water season in the south central Beaufort Sea off Alaska between western Camden Bay and Harrison Bay. The primary area of seismic activity is expected to be an area approximately 16 by 7 kilometers (km) (10 miles (mi) by 4 mi) in and near Simpson Lagoon, west of Prudhoe Bay and offshore of Oliktok Point. Weather permitting, the survey is expected to take place between approximately July 27 and mid- to late-October, 2001.

WesternGeco's OBC survey involves dropping cables from a ship to the ocean bottom, forming a patch consisting of 4 parallel cables 8.9 km (5.5 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 rock strata below the ocean bottom. 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. WesternGeco will use two source vessels for the open-water 2001 seismic surveys, one for deep water and one for shallow water, primarily shoreward of the barrier islands. The deep water vessel, the R/V Arctic Star, will utilize an airgun array with an air discharge volume of 1,210 cubic inches (in3) (19.8 liters, L). The maximum source levels for the Arctic Star will be at 249 dB re 1 micro Pascal at 1 meter (Pa-m) when the acoustic pressure is 29.4 bar-meters (zero to peak), which is equivalent to 253 dB re 1 micro Pa-m when the acoustic pressure is 45.9 bar-meters (peak-to-peak). Most operations utilizing the 1,210 in3 array are expected to operate at a gun depth of 2.3 m (7.5 ft) and water depth of <10 m (<32.8 ft). The shallow water source vessel, the R/V Peregrine, will utilize an airgun array with an air discharge volume of 640 in3 (10.48 L). The source level maximums for the Peregrine will be at 237 dB re 1 micro Pa-m when the acoustic pressure is 6.7 bar-meters (zero to peak), which is equivalent to 242 dB re 1 micro Pa-m when the acoustic pressure is 12.2 bar-meters (peak to peak). These airgun arrays are smaller and less powerful than the arrays used in some other seismic programs in the Beaufort Sea prior to 1999 and are expected to operate at a gun depth of 1 m (3.3 ft) in very shallow water.

It is anticipated that the seismic vessels 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 from adjacent patches.

After sufficient data have been recorded to allow accurate mapping of the rock strata, the cables are lifted onto the deck of one of the two self-powered cable vessels (R/V Western Endeavor and R/V Western Frontier), moved to a new location (ranging from several hundred to a few thousand feet away), and placed onto the seabed again. A small utility vessel (Ski Barge) may also be used to transfer seismic crew and/or marine mammal observers, as well as supplies and refuse, between the seismic vessels and Prudhoe Bay. Air support will be limited to infrequent (if any) helicopter flights and, starting after August 31, 2001, aerial surveys at altitudes from 900 to 1500 ft (274 to 457 m). For a more detailed description of the seismic operation, please refer to WesternGeco (2001).

Comments and Responses

On June 14, 2001 (66 FR 32321), NMFS published a notice of receipt and a 30-day public comment period was provided on the application and proposed authorization. Comments were received from the Marine Mammal Commission (MMC) and LGL Ltd., environmental research associates (monitoring contractor for the seismic surveys) on behalf of Western Geco LLC.

Activity Concerns

Comment 1: The June 14, 2001, Federal Register notice implies that the 1210 in3 airgun array might be operated at two different pressures: “249 dB re 1 micro Pa-m equals 29.4 bar-m zero-to-peak, or 253 dB re 1 micro Pa-m equals 45.9 bar-m peak-to-peak.” LGL Ltd. commented that these four measurements are all equivalent to one another, and all would apply simultaneously. The same applies for the pressures quoted for the 640 in3 airgun array. In addition, LGL Ltd. noted that the “-m” in the unit “dB re 1 micro Pa-m” should be read as “at 1 meter”, not “per minute” as stated in the notice.

Response: Thank you for providing this information. NMFS did not intend to imply that the airgun array(s) would operate at two different pressures. To clarify, NMFS has added equivalent language to the sentences referred to within this document. Also, NMFS has corrected the micro Pascal “per minute” reference to read micro Pascal “at 1 meter”.

Comment 2: LGL Ltd. noted that the statement: “the highest frequency in the airgun sounds will be 188 Hz” is in error. Western's application states that the dominant frequency components will extend up to 188 Hz. The energy content decreases with increasing frequency, but there is some energy at frequencies above 188 Hz. The overall source level of the 1210 in3 array, as quoted in Western's application, included energy up to 375 Hz.

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Response: NMFS has made the appropriate changes in this document and has taken this information into account when making its determinations under the MMPA.

Subsistence Concerns

Comment 3: LGL Ltd. noted that a Conflict Avoidance Agreement for 2001 has been signed by WesternGeco, AEWC, and representatives of the Kaktovik and Nuiqsuit whaling captains.

Response: Thank you for this information.

Mitigation, Monitoring and Reporting Concerns

Comment 4: LGL Ltd. notes that at the peer/stakeholder workshop in Seattle on June 5-6, 2001, it was agreed that the number of marine mammal observers for the 2001 work aboard the Arctic Star would be three (two biologists and one Inupiat), not four as the June 14, 2001, Federal Register notice stated. As in previous years, one marine mammal observer would be on watch at most times, though 30 minutes prior to and during airgun startups, and occasionally at other times, two marine mammal observers would be on watch.

Response: Thank you for this information. NMFS has made the appropriate changes in this document and has taken this information into account when making its determinations under the MMPA.

Comment 5: LGL Ltd. notes that at the peer/stakeholder workshop in Seattle on June 5-6, 2001, it was agreed that the number of marine mammal observers for the 2001 work aboard the Peregrine would be two (one biologist and one Inupiat, with no additional observers required as the June 14, 2001, Federal Register notice stated), provided that wheelhouse personnel watch for marine mammals at times when no marine mammal observer is on duty, and that shut down of airguns would be conducted in the same manner when a marine mammal is seen inside the safety radius and a marine mammal observer is not on duty. It was also agreed that when a shutdown is initiated by wheelhouse personnel in the absence of a marine mammal observer, the shutdown would be recorded but additional details concerning the marine mammal sighting probably would not be recorded. It was noted at the peer/stakeholder workshop that the Peregrine has space for only two marine mammal observers, that frequent boat-to-boat transfers of personnel are undesirable from a safety perspective, and that the Peregrine will operate in shallow waters (mainly a lagoon) where bowhead whales are highly unlikely to occur and where seal densities may be relatively low.

Response: Thank you for this information. NMFS concurs with this change in the monitoring requirements aboard the Peregrine, with one exception. When a shut down occurs and a marine mammal observer is not on duty, the wheelhouse personnel must notify one of the marine mammal observers so that they can record the information required by NMFS. This was agreed upon by NMFS and WesternGeco at the peer/stakeholder meeting on June 6, 2001 as part of WesternGeco's standard operating procedures. NMFS has made the appropriate changes in this document and has taken this information into account when making its determinations under the MMPA.

Comment 6: The MMC concurs with NMFS that the proposed activities in the Alaskan Beaufort Sea will result, at most, in a temporary modification of the behavior of certain species of cetaceans and pinnipeds. The MMC also concurs that the monitoring and mitigation measures proposed by WesternGeco appear to be adequate to ensure that the planned surveys will not result in the mortality or serious injury of any marine mammals or have unmitigable adverse effects on the availability of marine mammals for taking by Alaska Natives for subsistence uses. Therefore, the MMC recommends that the requested IHA be issued, provided that NMFS is satisfied that the monitoring and mitigation programs will be carried out as described in the application.

Response: Thank you for the comment. On June 5, 2001, NMFS convened a peer-review/stakeholders meeting in Seattle, WA to discuss the proposed monitoring and mitigation measures for this seismic survey program. A description of the monitoring and mitigation that will be required for this activity is described later in this document.

Although NMFS has no reason to believe that the monitoring and mitigation programs will not be carried out, a report on all activities under the IHA will be required to be submitted to NMFS within 90 days of completion of the planned survey. This report will be reviewed by NMFS to determine whether WesternGeco fully complied with the terms and conditions of the IHA, including the monitoring and mitigation requirements.

Comment 7: The MMC questions whether there is a sufficient basis for concluding that this activity, combined with past and possible future activities in this region, is unlikely to have non-negligible cumulative effects on any of the potentially affected marine mammal species or their availability to Alaska Natives for subsistence uses. Therefore, the MMC recommends (as in previous letters) that NMFS, in consultation with the applicant, the Alaska Department of Fish and Game, and the Native communities, determine the long-term monitoring that would be required to confirm that the proposed seismic surveys and possible future exploration and development activities do not cause changes in the seasonal distribution patterns, abundance, or productivity of marine mammal populations in the area. MMC recommends that such consultations address: (1) the possibility that the sum of exploration and development activities could have significant cumulative adverse effects on marine mammal behavior and distribution; (2) whether previous and proposed monitoring programs have provided and will continue to provide adequate baseline data for detecting possible future changes in the distribution, abundance, or productivity of the potentially affected marine mammal populations; (3) changes in the planned marine mammal and acoustic monitoring program that would be required to provide adequate baseline data; and, (4) whether the purposes of the MMPA and the Endangered Species Act might be met more cost-effectively by designing and implementing long-term monitoring programs to replace or augment the site-specific monitoring currently required.

Response: Thank you for the recommendation. Based on the best available scientific information, WesternGeco's proposed OBC seismic survey is unlikely to have more than minimal behavioral effects on marine mammal species in the area. If the survey period extends into the fall bowhead migration season, there may be some effect on bowhead whales migrating inshore. However, some of WesternGeco's seismic work will be conducted shoreward of the barrier islands, where noise from the survey would be unlikely to reach the main migration path for bowheads. In addition, the seismic arrays being used will never be fired simultaneously.

NMFS recognizes the need to address potential adverse cumulative impacts from oil and gas exploratory and development activities on both marine mammal stocks and subsistence needs. The 2001 scientific peer review workshop participants concluded that the current research and monitoring proposed by WesternGeco for seismic surveys, by BPX for oil development at Northstar, and by BP/EM/PAI for Start Printed Page 42518shallow hazard surveys (see 66 FR 32321, June 14, 2001, 65 FR 34014, May 25, 2000, and 66 FR 29287, May 30, 2001), coupled with existing projects to monitor bowhead population abundance (trends in abundance) should provide the information necessary to provide baseline data and determine overall cumulative impacts from noise on bowhead whales. Existing long-term monitoring projects that augment current site-specific monitoring required under MMPA authorizations, include: (1) the North Slope Borough spring bowhead census; (2) the Minerals Management Service's (MMS) autumn aerial survey; and, (3) an MMS-funded bowhead whale photo-identification project conducted in conjunction with bowhead whale feeding studies. Similar work is underway for ringed seals. Provided trends in bowhead (and other species') abundance continue to be positive and until new scientific information is made available, NMFS presumes industrial development on the North Slope is not adversely affecting the bowhead population.

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 whales(Delphinapterus leucas), ringed seals (Phoca hispida), spotted seals (Pusa 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), WesternGeco (2001), the annual monitoring reports for seismic surveys in the Beaufort Sea (LGL Ltd. and Greeneridge Sciences Inc, 1997, 1998, 1999, 2000) and several other documents (Corps of Engineers, 1999; Lentfer, 1988; MMS, 1992, 1996; Ferrero et al., 2000). 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.

Underwater pulsed sounds generated by open water seismic operations may be detectable a substantial distance away from the activity. The effect of these pulsed sounds on living marine resources, particularly marine mammals in the area, will be dependent on the hearing sensitivity of the species, the behavior of the animal at the time the sound is detected, as well as the distance and level of the sound relative to ambient conditions. Any sound that is detectable is (at least in theory) capable of eliciting a disturbance or avoidance reaction by some marine mammals or of masking signals of comparable frequency that are generated by marine mammals (e.g., whale calls) (WesternGeco, 2001). 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 show a disturbance or avoidance reaction to the generated sounds or to visual cues.

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 the 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. Seismic pulses have been observed to cause strong avoidance reactions by many of the bowhead whales occurring within a distance of several kilometers, including changes in surfacing, respiration and dive cycles, and to sometimes cause avoidance or other changes in bowhead behavior at considerably greater distances (Richardson et al., 1995; Rexford, 1996; MMS, 1997; Miller et al., 1999). Airgun pulses may also disturb some other marine mammal species occurring in the area. Ringed seals within a few hundred meters of an airgun array showed variable reaction to the noise, with some moving somewhat farther away and other seals not moving far at all (Harris et al., 1997, 1998, in press; Lawson and Moulton, 1999; Moulton and Lawson, 2000). It is likely that avoidance distances around nearshore seismic operations of the type planned for 2001 may be less than those around some of the seismic operations that were done in the Beaufort Sea before 1996 for the following reasons: (1) The recent seismic operations have been in shallow water, (2) the recent seismic operations have been limited to a confined area at any one time, and (3) the recent seismic operations have employed smaller airgun arrays than those that were used in the past.

Although some limited masking of low-frequency sounds (e.g., bowhead and gray whale calls) is a possibility, the intermittent nature of seismic survey pulses used by WesternGeco (1 second in duration every 16 to 24 seconds), as well as the fact that airgun operations are expected to occur no more than 50 percent of the time, 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., 1997, 1999; Richardson et al., 1986). Masking effects are expected to be absent in the case of beluga whales, given that sounds utilized by them are at much higher frequencies (in the 2 to 6 kilohertz (kHz) range) (Sjare and Smith, 1986) than airgun sounds from WesternGeco's seismic surveys (dominant frequency components will extend up to 188 hertz(Hz)) (WesternGeco, 2001).

Permanent hearing damage is not expected to occur during the project. There is no direct evidence that the hearing systems of marine mammals close to an airgun array would be at risk of temporary or permanent hearing impairment; however, depending on the species, the equipment being used, and the number of pulses to which the animal is exposed, temporary threshold shift (TTS) is a theoretical possibility for animals within a few hundred meters of the source (Richardson et al., 1995; Finneran et al., 2000).

Planned monitoring and mitigation measures, proposed by WesternGeco and 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.

For a discussion on the anticipated effects of ships, boats, and aircraft on marine mammals and their food sources, and for a more complete review of the best available information Start Printed Page 42519available on the potential effects of seismic surveys to marine mammals in the Arctic, please refer to the application (WesternGeco, 2001) and the Federal Register notice of June 14, 2001 (66 FR 32321).

Numbers of Marine Mammals Expected to Be Taken

Based on an analysis provided in their application, WesternGeco estimates that the following numbers of marine mammals may be subject to Level B harassment, as defined in 50 CFR 216.3:

SpeciesPopulation SizeHarassment Takes in 2001
160 dB criterion1,000<500
2 0km criterion2,630<1,300
Gray whale26,000<100
Beluga whale39,258250<150
Ringed seal31-1.5 million400<200
Spotted seal3>200,000<10<2
Bearded seal3>300,00050<15
1 The maximum number that might be taken if seismic surveys are operable during the September/October period and the bowhead migration passes unusually close to shore as in 1997.
2 The number that could be taken under the most likely operating conditions.
3 Some individual seals may be harassed more than once

At the 2001 open water peer-review workshop held in Seattle on June 5th and 6th, the attendees agreed on support of the following statement based on methods and results reported in Miller et al. (1999): “Monitoring studies of 3-D seismic exploration (6-18 airguns totaling 560-1500 in3) in the nearshore Beaufort Sea during 1996-1998 have demonstrated that nearly all bowhead whales will avoid an area within 20 km of an active seismic source, while deflection may begin at distances up to 35 km. Sound levels received by bowhead whales at 20 km ranged from 117-135 dB re 1 micro Pa rms and 107-126 dB re 1 micro Pa rms at 30 km. The received sound levels at 20-30 km are considerably lower levels than have previously been shown to elicit avoidance in bowhead or other baleen whales exposed to seismic pulses.” NMFS adopts the Miller et al. research and the peer review workshop's statement as the best scientific information available on bowhead whale reactions to seismic sources. Given this information, NMFS utilized the 20 km criterion estimates of take for bowhead whales provided by WesternGeco in determining the number of harassment takes to be authorized under the IHA for the 2001 open water season.

Estimates of Marine Mammal Takes

Estimates of takes by harassment will be made through vessel and/or aerial surveys. Preliminarily, WesternGeco will estimate the number of (1) marine mammals observed within the area ensonified strongly by the OBC seismic vessel (see Mitigation section of this document for description of safety radii); (2) marine mammals observed showing apparent avoidance or disturbance reactions to seismic pulses (e.g., heading away from the seismic vessel in an atypical direction); (3) marine mammals estimated to be subject to take by type (1) or (2) when no monitoring observations were possible; and (4) bowhead whales whose migration routes come within 20 km (actual distance dependent on a combination of 1996-1998 and 2001 data) of the operating OBC seismic vessel, or would have if they had not been displaced farther offshore.

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 bowhead whales become more “skittish” when exposed to seismic noise.

The location of the proposed seismic activity is south of the center of the westward migration route of bowhead whales, but there is some limited overlap with the southern limit of the migration. Seismic monitoring results from 1996-1998 indicate that most bowhead whales avoid the area within about 20 km (12.4 mi) around the airgun array when it is operating, and some avoid the area within 30 km (18.6 mi). In addition, bowhead whales 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).

Nuiqsut is the community closest to the area of the proposed activity. The communities of Barrow and Kaktovik also harvest resources that pass through the general area, but do not regularly hunt in the planned seismic exploration area. Subsistence hunters from all three communities conduct an annual hunt for migrating bowhead whales during the autumn months. In recent years, Nuiqsut whalers have typically taken two to four whales each year (WesternGeco, 2001). 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 2001 seismic area.

Whalers from the village of Kaktovik search for whales east, north, and west of the village. Kaktovik is located 72 km (45 mi) east of the easternmost end of WesternGeco’s planned 2001 seismic exploration area.

Whalers from the village of Barrow search for bowhead whales >200 km (>125 mi) to the west of the planned seismic area (WesternGeco, 2001).

Nuiqsut hunters also hunt seals for subsistence purposes. Most seal hunting has been during the early summer in open water. Boat crews hunt ringed, spotted, and bearded seals. The most important sealing area for Nuiqsut Start Printed Page 42520hunters is off the Colville Delta, extending as far west as Fish Creek and as far east as Pingok Island. The planned seismic exploration during the summer has some potential to influence seal hunting activities by residents of Nuiqsut. During BP and Western Geophysical's 1996-2000 seismic programs, an operating airgun array apparently did not displace seals by more than a few hundred meters.

The possibility and timing of potential seismic operations in the Cross Island area and in Nuiqsut sealing areas required WesternGeco to provide NMFS with either (1) a Plan of Cooperation with the Alaska Eskimo Whaling Commission (AEWC) and the North Slope whaling communities, or (2) measures that have been or will be taken to avoid any unmitigable adverse impact on the availability of these animals for subsistence needs. The timing of seismic operations has been addressed in a Conflict Avoidance Agreement (CAA) between WesternGeco, the Nuiqsut and Kaktovik whalers, and the AEWC (WesternGeco, 2001). In addition, WesternGeco’s application identifies, and the IHA has incorporated, mitigation and monitoring measures that will be taken to minimize any adverse effect on subsistence uses and improve the state of knowledge on the effects of seismic exploration on the accessibility of bowhead whales to hunters.

Anticipated Impact on Habitat

The proposed seismic activity is not expected to cause significant and permanent impacts on habitats used by marine mammals, or to the food sources they utilize. The main impact issue associated with the proposed activity will be temporarily elevated noise levels. For a more detailed analysis of anticipated impact on habitat refer to the application (WesternGeco, 2001) and the Federal Register notice of June 14, 2001 (66 FR 32321).

The 2001 OBC survey area may overlap with areas identified as “Boulder Patch” habitat. WesternGeco is required by the State of Alaska to consult with NMFS as to the location and resources of the Stephansson Sound Boulder Patches so that they may be avoided.


For the 2001 seismic operations, WesternGeco will reduce its primary airgun array from the 1,500 in3 used in 1998 to 1,210 in3. This reduction in volume will lower the source levels and result in lower received levels at each distance compared to Western Geophysical's 1998 project. The smaller volume 640 in3 airgun array consists of sixteen 40 in3 airguns in four 4-gun clusters. The airguns comprising this small volume array will be spread out horizontally, such that the energy from the array, like that from the 1,210 in3 array, will be directed downward insofar as possible. The distances within which received levels (see the proposed safety radii below) can exceed 190 dB and 180 dB re 1 micro-Pa have been measured at two airgun depths (2.3 and 5 m or 7.5 and 16.4 ft) and in two water depths (8 and 23 m or 26.2 and 75.5 ft) (Greene and McLennan, 2000), and are reduced relative to those around the 1998 array. The shallower depth at which the 640 in3 array will operate will tend to reduce the source level (and hence the 190 and 180 dB safety radii) even farther; however, as a precautionary approach, the 190 and 180 dB radii for the 1,210 in3 airgun operating at 2.3 m (7.5 ft) depth will be assumed to apply to the 640 in3 array operating at 1 m (3.3 ft) gun depth.

The safety radii for OBC seismic operations in 2001 are based on comprehensive measurements of the sounds recorded in the water near the OBC array in 1999 and analyzed by Greene and McLennan (2000).

Vessel-based observers will monitor marine mammal presence in the vicinity of the seismic arrays throughout the seismic program. To avoid the potential for injury, WesternGeco will immediately shut down the seismic source if seals and/or whales are sighted within the safety radii. The safety radii are as follows:

190 dB (Seals)180 dB (Whales)

In addition, WesternGeco will ramp-up the 1,210 in3 and 640 in3 seismic sources to operating levels at a rate no greater than 6 dB per minute. Under normal operational conditions (source vessel speed at least 4 knots), a ramp-up will be required after the array has been inactive for a period lasting 1 minute or longer. If the towing speed is reduced to 3 knots or less, a ramp-up will be required after the array has been inactive for a period lasting 2 minutes or longer. Ramp-up will begin with an air volume discharge not exceeding 80 in3 for the 1,210 in3, and 40 in3 for the 640 in3 array. Additional guns will be added at appropriate intervals so as to limit the rate of increase in source level to 6 dB per minute.


As part of its application, WesternGeco provided a monitoring plan for assessing impacts to marine mammals from seismic surveys in the Beaufort Sea. This monitoring plan is described in WesternGeco (2001) and in LGL, Ltd. and Greeneridge Sciences Inc. (2001).

The monitoring plan submitted to NMFS on April 16, 2001, was reviewed at a peer-review workshop held in Seattle, WA, on June 5-6, 2001. The monitoring plan, with minor modifications, was accepted by NMFS at this meeting. A copy of the monitoring plan is available upon request (see ADDRESSES).

WesternGeco plans to conduct the following monitoring:

Vessel-based Visual Monitoring

One or two marine mammal observers aboard the seismic source vessels 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. If operations continue after mid-August, when the duration of Start Printed Page 42521darkness increases, image intensifiers and additional light sources will be used to illuminate the safety zone (see application for more detail).

A total of three observers (two trained biologists and one Inupiat observer/communicator) will be based aboard the seismic source vessel Arctic Star. Two observers must be on active watch 30 minutes prior to and during the start of seismic transmissions and a minimum of one observer needs to be on active watch aboard the Arctic Star whenever the seismic sources are operating during daylight hours.

A total of two observers will be based aboard the seismic source vessel Peregrine. A minimum of one observer must be on active watch 30 minutes prior to and during the start of seismic transmissions and a minimum of one observer must be on active watch aboard the Peregrine for a total of 16 hours during any given 24 hour period when seismic operations are taking place. In addition, wheelhouse staff aboard the Peregrine will assist in maintaining a watch for marine mammals. During the hours when a marine mammal observer is not on duty, wheelhouse personnel must actively watch for marine mammals, follow all shut-down procedures if a marine mammal is sighted within the designated safety zones, and notify the marine mammal observer(s) any time a shut-down occurs.

Vessel-based monitoring will include recording information on seismic operations, vessel activities, marine mammals sighted, and other relevant activity in a standardized format.

Aerial Surveys

If OBC seismic work continues after August 31, 2001, aerial surveys by WesternGeco's marine mammal contractor, LGL Ltd., will occur from the date on which OBC seismic operations commence until 1 day after the OBC seismic operations end. 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. WesternGeco will continue aerial surveys until 1 day after OBC seismic work ends. It should be noted that the proposed duration for aerial surveys would be a reduction from previous years. WesternGeco 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, the MMS expects to conduct its broad-scale aerial survey work from approximately August 31 until the end of the bowhead migration in October. WesternGeco believes that this combined aerial survey data will provide sufficient information to estimate the numbers of bowhead whales taken by harassment.

The primary objective of WesternGeco's aerial surveys will be to document the occurrence, distribution, and movements of bowhead whales, and (secondarily) 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 these species. Sonobuoys will be dropped to document seismic and ambient noise at offshore locations, including locations near whales.

WesternGeco will fly at 300 m (1,000 ft) in areas where no whaling is underway, with a minimum altitude of no less than 275 m (900 ft) under low cloud conditions. In addition, and subject to the terms of the 2001 CAA with subsistence communities, surveys will be flown at 457 m (1500 ft) altitude over areas where whaling is occurring and will avoid direct overflights of whaleboats and Cross Island.

The daily aerial surveys are designed to cover a grid of 18 north-south lines spaced 8 km (5 mi) apart and extending seaward to about the 100 m (328 ft) depth contour (typically about 65 km (40.4 mi) offshore). This grid will extend from about 65 km (40.3 mi) east to 65 km (40.3 mi) west of the area in which seismic operations are underway on that date. This survey design will provide extended coverage to determine the eastward and westward extent of the offshore displacement of whales by seismic operations. Because of the inshore nature of the 2001 seismic surveys, few whales are expected to occur within 20 km (12.4 mi) of the operations; therefore, no “intensive” grid surveys are planned.

Detailed information on the aerial survey program can be found in WesternGeco (2001) and in LGL Ltd. and Greeneridge Sciences Inc. (2001), which are incorporated in this document by citation.

Acoustical Measurements

The acoustic measurement program for 2001 is designed to provide, in conjunction with existing results from previous years (see LGL and Greeneridge Sciences Inc., 1997, 1998, 1999), the specific acoustic data needed to document the seismic sounds to which marine mammals will be exposed in 2001. This measurement program will only be operable if seismic operations continue after August 31, 2001. Proposed emphasis is on situations and locations not studied in detail during previous operations.

WesternGeco has two basic objectives for collecting acoustic measurements, one physical and one biological. The physical acoustics objective is to determine the characteristics of airgun array pulses as received in the bowhead migration corridor at varying distances offshore and to the east of the area of seismic exploration in 2001 and in 1996- 98 plus 2001 combined. Pulse characteristics to be determined are received levels and pulse durations versus range offshore and to the east, spectral properties, and signal-to-ambient ratios. The biological objective is to determine whether there are differences in the pattern of bowhead call detection rates near, offshore of, and east of the seismic exploration area at times with and without active seismic operations based on 2001 data and combined 1996-98 and 2001 data. If there are differences, then WesternGeco will use the combined acoustic and aerial survey data to evaluate whether the noise-related differences in call detection rate are attributable to differences in calling behavior, whale distribution, or a combination of the two.

In 2001, the acoustic measurement program is planned to include (1) deployment in late August/September of autonomous seafloor acoustic recorders (ASARs) to provide continuous acoustic data for extended periods, and (2) use of air-dropped sonobuoys in September/October. WesternGeco will use these methods only if OBC surveys occur in September/October.

For a more detailed description of planned monitoring activities, please refer to the application and the Technical Monitoring Plan (WesternGeco, 2001; LGL Ltd. and Greeneridge Sciences Inc., 2001) and the Federal Register notice of June 14, 2001 (66 FR 32321).


WesternGeco will provide an initial report on 2001 activities to NMFS within 90 days after the end of the seismic program. This report will summarize dates and locations of seismic operations, marine mammal sightings (dates, times, locations, behaviors, associated seismic survey activities), estimates of the amount and nature of all takes by harassment or in other ways, and any apparent effects on Start Printed Page 42522accessibility of marine mammals to subsistence users.

A final technical report will be provided by WesternGeco within 20 working days of receipt of the document from the contractor, but no later than April 30, 2002. The final technical report will contain a description of the methods, results, and interpretation of all monitoring tasks.


Under section 7 of the Endangered Species Act (ESA), NMFS completed consultation with MMS on oil and gas exploration and associated activities in the Alaskan Beaufort Sea on May 25, 2001. This consultation includes a review of seismic and related noise sources used by the oil and gas industry. The finding of that consultation was that oil and gas activities in the Alaskan Beaufort Sea, and the issuance by NMFS of a small take authorization for oil and gas activities, are not likely to jeopardize the continued existence of the bowhead whale. In formulating this opinion, NMFS used the best available information, including information provided by MMS, recent research on the effects of oil and gas activities on the bowhead whale, and the traditional knowledge of Native hunters and the Inupiat along Alaska's North Slope. A copy of the Biological Opinion issued as a result of this consultation is available upon request (see ADDRESSES).

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 Environmental Assessment (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. This determination was based on (1) the proposed construction of the Northstar project by BP, Alaska, (2) the collection of data from 1996 through 1998 on Beaufort Sea marine mammals and the impacts of seismic activities on these mammals, and (3) the analysis of scientific data indicating that bowhead whales avoid nearshore seismic operations by a distance of approximately 20 km (12.4 mi). Accordingly, a review of the impacts expected from the issuance of an IHA have been assessed in the EA, in the Federal Register notice of June 14, 2001 (66 FR 32321), and in this document. NMFS has determined that there will be no more than a negligible impact on marine mammals from the issuance of the IHA 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, as in 1999, 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. Since this proposed action falls into a category of actions that do not individually or cumulatively have a significant impact on the human environment, as determined through the 1999 EA, this action is categorically excluded from further NEPA analysis (NOAA NAO 216-6). A copy of the 1999 EA is available upon request (see ADDRESSES).

Coastal Zone Management Act Consistency

The State of Alaska, Department of Natural Resources, Division of Oil and Gas issued a proposed Alaska Coastal Management Program consistency determination on June 21, 2001, for WesternGeco's planned 3-D seismic surveys on state tide and submerged lands in the Beaufort Sea during the open water season of 2001. Based on the State's review, performed under 6 AAC 50, the State concurred that the project is consistent with the ACMP as long as: (1) Operations beyond September 1 will be considered on a case-by-case basis if the Director, Division of Oil and Gas, in consultation with NMFS, determines that: (a) a suitable whale monitoring program will be conducted and appropriate measures to minimize conflict with the Nuiqsuit subsistence whale harvests will be taken; or (b) the Village of Nuiqsuit has completed its whale hunt for 2001; or (c) NMFS has issued an IHA; (2) all operations must be conducted in a manner that will assure minimum conflict with other users of the area, including coordination with local whaling crews as needed to avoid conflicts with the subsistence whale hunt; (3) seismic activities shall avoid or minimize interference with traditional food gathering and access to subsistence resources; and (4) permittee will consult with NMFS' Alaskan Offices as to the location and resources of the Stephansson Sound Boulder Patches and any operational changes made in response to this consultation will be disclosed in the completion report.


Based on the evidence provided in the application, the EA, the Federal Register notice (66 FR 32321), and this document, and taking into consideration the comments submitted on the application and proposed authorization notice, NMFS has determined that there will be no more than a negligible impact on marine mammals from the issuance of the harassment authorization to WesternGeco, LLC and that there will not be any unmitigable adverse impacts to subsistence communities. NMFS has determined that the short-term impact of conducting OBC seismic operations in the Alaskan Beaufort Sea will result, at worst, in a temporary modification in behavior by certain species of pinnipeds and cetaceans. Behavioral modifications may be made by these species to avoid noise from seismic operations; however, this behavioral change is expected to have a negligible impact on marine mammal species and stocks mentioned here. Due to the distribution and abundance of marine mammals during the projected period of activity and the location of the seismic operations 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.

Since (1) the number of potential harassment takings of bowhead whales, gray whales, beluga whales, ringed seals, spotted seals, and bearded seals is estimated to be small; (2) no take by injury and/or death is anticipated; (3) the potential for temporary or permanent hearing impairment is low and will be avoided through the incorporation of the mitigation measures mentioned in this document and required under the IHA; and (4) no rookeries, mating grounds, year-round 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, NMFS has determined that the requirements of section 101 (a)(5)(D) of the MMPA have Start Printed Page 42523been met and the authorization can be issued.

Appropriate mitigation measures to avoid an unmitigable adverse impact on the availability of bowhead whales for subsistence needs have been the subject of a CAA between WesternGeco, the AEWC, and Nuiqsut and Kaktovik whalers. This agreement consists of three main components: (1) Communications, (2) conflict avoidance, and (3) dispute resolution, and has been concluded for the 2001 open-water seismic season.

WesternGeco estimates that 2,630 bowheads could potentially be exposed to its OBC seismic survey activities and, more probably, a total of less than 1,300 bowheads may be harassed based on the number of bowheads that might potentially be within 20 km of the airgun arrays. NMFS concurs and is therefore authorizing a take for bowhead whales by Level B harassment of 1,965 animals (based on the average of 2,630 and 1,300 animals). NMFS believes that no bowheads will be killed or seriously injured by WesternGeco's activity and accordingly has not authorized takings for injury or mortality.

Open-water seismic exploration in the Alaskan Beaufort Sea does have some potential to influence seal hunting activities by residents of Nuiqsut. However, because the main summer sealing by the village of Nuiqsut is conducted off the Colville Delta, west of the proposed survey area, and the zone of influence by seismic sources on seals is expected to be fairly small (less than a few hundred meters), NMFS believes that WesternGeco’s OBC seismic survey will not have an unmitigable adverse impact on the availability of seals for subsistence uses.


Accordingly, NMFS has issued an IHA to WesternGeco, LLC for the ocean bottom cable seismic survey operations described in this notice during the 2001 open water season in the Alaskan Beaufort Sea provided the mitigation, monitoring, and reporting requirements described in this document and in the IHA are undertaken.

Start Signature

Dated: August 1, 2001.

Donald Knowles,

Director, Office of Protected Resources, National Marine Fisheries Service.

End Signature End Supplemental Information

[FR Doc. 01-20281 Filed 8-10-01; 8:45 am]