65 FR 60 pgs. 16374-16379 - Small Takes of Marine Mammals Incidental to Specified Activities; Marine Seismic-Reflection Data Collection in Southern California

Type: NOTICEVolume: 65Number: 60Pages: 16374 - 16379
Docket number: [I.D.022800B]
FR document: [FR Doc. 00-7611 Filed 3-27-00; 8:45 am]
Agency: Commerce Department
Sub Agency: National Oceanic and Atmospheric Administration
Official PDF Version:  PDF Version


National Oceanic and Atmospheric Administration


Small Takes of Marine Mammals Incidental to Specified Activities; Marine Seismic-Reflection Data Collection in Southern California


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


Notice of receipt of application and proposed authorization for a small take exemption; request for comments.


NMFS has received a request from the U.S. Geological Survey (USGS) for an authorization to take small numbers of marine mammals by harassment incidental to collecting marine seismic-reflection data in southern California waters. Under the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to authorize the USGS to incidentally take, by harassment, small numbers of marine mammals in the afore- mentioned area for a 3-week period between May and July 2000.


Comments and information must be received no later than April 27, 2000.


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 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.


Kenneth R. Hollingshead, NMFS, (301) 713-2055, or Christina Fahy, NMFS, 562-960-4023.



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

Permission may be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s), will not have an unmitigable adverse impact on the availability of the species or stock(s) for subsistence uses, and permissible methods of taking and requirements pertaining to the monitoring and reporting of such takings are set forth. NMFS has defined "negligible impact" in 50 CFR 216.103 as " * * *an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival."

Subsection 101(a)(5)(D) of the MMPA established an expedited process by which citizens of the United States can apply for an authorization to incidentally take small numbers of marine mammals by harassment. The MMPA now defines "harassment" as:

...any act of pursuit, torment, or annoyance which (a) has the potential to injure a marine mammal or marine mammal stock in the wild; or (b) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering.

Subsection 101(a)(5)(D) establishes a 45-day time limit for NMFS review of an application followed by a 30-day public notice and comment period on any proposed authorizations for the incidental harassment of small numbers of marine mammals. Within 45 days of the close of the comment period, NMFS must either issue or deny issuance of the authorization.

Summary of Request

On January 24, 2000, NMFS received a request from the USGS for authorization to take small numbers of several species of marine mammals by harassment incidental to collecting marine seismic-reflection data from waters off southern California. Seismic data will be collected during a 3-week period between May and July 2000, preferably June, to determine the source of the invasion of seawater into freshwater aquifers that are critical to the Los Angeles-San Pedro area water supply and to support studies of the regional landslide and earthquake hazards for people within the coastal cities between Santa Barbara and San Diego.


The USGS proposes to conduct a high-resolution seismic survey offshore from Southern California. For a 3-week period between May and July 1999, preferably in June, the USGS would like to collect seismic-reflection data to investigate: (1) the intrusion of seawater into freshwater coastal aquifers that are critical to the water supply for people within the Los Angeles- San Pedro area and (2) the hazards posed by landslides, tsunamis, and potential earthquake faults in the nearshore region from Santa Barbara to San Diego. Both of these tasks are multi-year efforts that require high-resolution, seismic-reflection data using a minisparker acoustic source.

Coastal Southern California is the most highly populated urban area along the U.S. Pacific coast with 30 percent of the California population (approximately 10 million people) living in Los Angeles County alone. The primary objectives of the USGS research are to provide information (1) to understand and help mitigate the intrusion of salt water into coastal aquifer systems resulting from ground-water overdraft and (2) to help mitigate the earthquake threat to this area. Data collected to address the salt water intrusion objective will be used to develop a hydrogeologic model for the region. This model will assist water managers (Water Replenishment District of Southern California and the Los Angeles County Department of Public Works) provide a safe and uncontaminated ground-water supply to the local population.

Important geologic information that the USGS will derive from this project's seismic-reflection data concerns how earthquake deformation is distributed offshore; that is, where the active faults are and what the history of movement along them has been. This should improve understanding of the shifting pattern of deformation that occurred over both the long term (approximately the last 100,000 years) and short term (the last few thousand years). The USGS seeks to identify actively deforming structures that may constitute significant earthquake threats. The USGS also proposes to locate offshore landslides that might affect coastal areas. Not only major subsea landslides might affect the footings of coastal buildings, but also very large slides can generate local tsunamis. These large sea waves can be generated by seafloor movement that is produced either by landslides or by earthquakes. Knowing where large slides have occurred offshore will help locate areas susceptible to wave inundation.

Some faults that have produced earthquakes lie entirely offshore or extend into offshore areas where they can be studied using high-resolution seismic-reflection techniques. An example is the Rose Canyon fault, which extends through the San Diego area, and is considered to be the primary earthquake threat. This fault extends northward from La Jolla, beneath the inner continental shelf, and appears again onshore in the Los Angeles area. This fault and others like it near shore could generate moderate (M5-6) to large (M6-7) earthquakes.

Knowing the location and geometry of fault systems is critical to estimating the location and severity of ground shaking. Therefore, the results of this project will contribute to decisions involving land use, hazard zonation, insurance premiums, and building codes.

The USGS emphasizes that the goal is not to predict earthquakes but rather to help determine what steps might be taken to minimize the devastation should a large earthquake occur. The regional earthquake threat is known to be high, and a major earthquake could adversely affect the well-being of a large number of people. In one example, earthquakes in the coastal ocean off southern California commonly result in large-scale submarine landslides, many of which could be capable of producing destructive tsunamis.

The proposed work is in collaboration with scientists at the Southern California Earthquake Center, which analyzes faults and earthquakes in onshore regions, and with scientists at the Scripps Institute of Oceanography, who measure strain (incremental movement) on offshore faults.

The USGS also wants to collect high-resolution seismic-reflection data to locate the sources and pathways of seawater that intrudes into freshwater aquifers below San Pedro. Ground water usage in the Los Angeles basin began in the mid-1800s. Today, more than 44,000 acre-feet of freshwater each year are extracted from the aquifers that underlie the West Coast Basin. Aggressive extraction of freshwater from coastal aquifers causes offshore salt water to flow toward areas of active pumping. To limit this salt-water intrusion, the Water Replenishment District and water purveyors in San Pedro are investing $2.7 million per year at the Dominguez Gap Barrier Project to inject freshwater underground to establish a zone of high water pressure in the aquifers near San Pedro and Long Beach. The resulting zone of high pressure forms a barrier between the invasive saltwater and the productive coastal aquifers.

USGS scientists in San Diego are working with the Los Angeles County Department of Public Works and the Water Replenishment District to develop a ground-water simulation model to predict fluid flow below San Pedro and nearby parts of the Los Angeles Basin. This model will eventually be used in managing water resources. The accuracy of the present model, however, is

compromised by a paucity of information about aquifer geometry and about other geologic factors that might affect fluid flow. Data collected by the USGS will be used to improve three-dimensional, fluid-flow models to aid management of water resources.

Proposed Field Work

Fieldwork described here will be the fourth geophysical survey on the west coast that the USGS has conducted under close supervision by marine-mammal biologists. In March 1998, the USGS used a large (6,500 in 3. , 106 liters) airgun array in and around Puget Sound to study the regional earthquake hazard (see 63 FR 2213, January 14, 1998). The USGS employed 12 biologists, who worked on two ships continuously to oversee the seismic- reflection operations. On several occasions the USGS shut off the acoustic sources when marine mammals entered safety zones that had been stipulated by NMFS, and when mammals left these zones, the USGS gradually ramped-up the array as required in its permit to avoid harming wildlife. Marine-mammal biologists reported that during the survey, no overt distress was evident among the dense marine-mammal population, and afterward no unexplained marine-mammal strandings occurred.

In August 1998, the USGS surveyed offshore from southern California, using a small airgun (40 in 3 , 0.65 liters). Two marine-mammal biologists oversaw this activity. In June 1999, the USGS conducted the third survey to support study of aquifer contamination and earthquake hazards in southern California (see 64 FR 31548, June 11, 1999). Three marine-mammal biologists provided oversight for this operation. The survey described in this document is proposed to be conducted with similar oversight.

Experimental Design

Marine studies conducted by the USGS focus where saltwater intrusion into coastal aquifers is an active concern and where other kinds of natural hazards have their greatest potential impact on society. In southern California, USGS studies will focus on five chief geographic areas. First is the San Pedro shelf, offshore of the Dominguez Gap barrier project. Collecting data as close to shore as feasible is critically important in order to merge onshore and offshore geology in a manner that allows modeling the hydrologic flow through the system. With respect to the seismic-hazard issues in the offshore, the USGS' main priority (and second geographic area) is the coastal zone and continental shelf between Long Beach and San Diego, where much of the hazard appears to be associated with strike-slip faults such as the Newport-Inglewood and Palos Verdes faults. A critical component of the survey concerns the third geographic area, which lies farther offshore in the Santa Monica, San Pedro, and San Diego Trough deeps, where rapid sedimentation has left a more complete record, relative to shallow-water areas, that can be used to decipher earthquake history. The fourth area is the extension into the Santa Barbara Channel of major elements of onshore geology that cross the northern part of Santa Monica Bay and include several major known earthquake faults. The fifth area is the geologic boundary, marked generally by the Channel Islands, between the inner California Borderland (dominated by strike-slip faults) and the Santa Barbara Channel (dominated by compressional faults). This change in fault types is important to study because the degree of earthquake threat varies with fault type. The study proposed herein focuses on the three highest priority areas, which lie near shore between Los Angeles and San Diego.

The seismic-reflection survey is planned to last 21 days. Based on experience collecting seismic-reflection data in this general area during 1998 and 1999, the USGS would prefer to conduct the 2000 survey in June. Because it will have to contract for a vessel from which to conduct the geophysical survey, the targeted study time frame is sometime within the May through July window. The basis for this decision is the USGS' desire to avoid the gray whale migrations and the peak arrival of other mysticetes during the later summer. An important part of the effort this summer will be to fill in gaps caused by shutdowns and daylight-only operations during earlier surveys.

The USGS has not yet determined the exact tracklines for the survey, but it does know the areas where minisparker use will be concentrated (see Fig. 3 in the application). Within the overall work area, the objective is to collect seismic-reflection data along a grid of lines that are about 2 km (1.07 nmi) apart. Data collected during the 1998 and 1999 surveys will be used to guide the planning for the proposed survey in order to minimize the number of survey lines that are required to adequately define the aquifer geometries and location of potential earthquake faults.

The USGS proposes to use two seismic-reflection systems for data collection: (1) A 1.5 kilo-Joule (kJ) minisparker using a 200-m (656.2-ft) long multichannel streamer, and (2) a low-power, high resolution deep-tow system. The potential effect on marine mammals is from the minisparker; mammals cannot become entangled in the streamer. The low-powered, high-resolution seismic- reflection system, manufactured by Huntec, Ltd., will obtain detailed information about the very shallow geology. The seismic-reflection systems will be aboard a vessel owned by a private contractor or academic cooperator. Ship navigation will be accomplished using satellites of the Global Positioning System. The survey ship will be able to report accurate positions, which is important to mitigating the minisparker's effect on marine mammals and to analyzing what impact, if any, minisparker operation has on the environment.

The Seismic Sound Sources

The primary sound source to be used during this survey will be a 1.5 kJ sparker "SQUID 2000" minisparker system manufactured by Applied Acoustic Engineering, Inc. This minisparker includes eight electrodes that are mounted on a small pontoon sled. The electrodes simultaneously discharge electric current through the seawater to an electrical ground. This discharge creates an acoustic signal. The pontoon sled that supports the minisparker is towed on the sea surface, approximately 20 meters (65.6 ft) behind the ship.

Source characteristics of the SQUID 2000 TM provided by the manufacturer show a sound-pressure level (SPL) of 209 dB re 1 µPa-m root-mean-square (RMS). The amplitude spectrum of this pulse indicates that most of the sound energy lies between 150 Hz and 1700 Hz (1.7 kHz), and the peak amplitude is at 900 Hz. The output sound pulse of the minisparker has a duration of about 0.8 milli-seconds (ms). When operated at sea for the multichannel seismic-reflection survey proposed herein, the minisparker will be discharged every 4 to 6 seconds.

The second seismic source that will be used during this survey is a Huntec TM system, which generates underwater sound at higher frequencies than does the minisparker. The Huntec system uses electromagnetically driven plates to produce an acoustic pulse every 0.5 seconds. This sound source is towed approximately 100 meters (328.1 ft) behind the ship in water depths greater than 200 m (656.2 ft). In shallow water, such as the inner shelf, the sound source is towed within 5 m (16.4 ft) of the sea surface. The SPL for this source is 205 dB re 1 µPa RMS. The frequencies of the main output sound are between 500 Hz and 8 kHz, with a peak amplitude at 4.5 kHz.

Description of Habitat and Marine Mammals Affected by the Activity

The Southern California Bight supports a diverse assemblage of 29 species of cetaceans (whales, dolphins and porpoises) and 6 species of pinnipeds (seals and sea lions). The species of marine mammals that are likely to be present in the seismic research area include the bottlenose dolphin ( Tursiops truncatus ), common dolphin ( Delphinus delphis ), killer whale ( Orcinus orca ), Pacific white-sided dolphin ( Lagenorhynchus obliquidens ), northern right whale dolphin ( Lissodelphis borealis ), Risso's dolphin ( Grampus griseus ), pilot whales ( Globicephala macrorhynchus ), Dall's porpoise ( Phocoenoides dalli ), sperm whale ( Physeter macrocephalus ), humpback whale ( Megaptera novaengliae ), gray whale ( Eschrichtius robustus ), blue whale ( Balaenoptera musculus ), minke whale ( Balaenoptera acutorostrata ), fin whales ( Balaenoptera physalus ), harbor seal ( Phoca vitulina ), elephant seal ( Mirounga angustirostris ), northern sea lion ( Eumetopias jubatus ), and California sea lion ( Zalophus californianus ), northern fur seal ( Callorhinus ursinus ) and sea otters ( Enhydra lutris ). General information on these latter species can be found in the USGS application and in Forney et al . (1999) and Barlow et al . (1998, 1997). Please refer to these documents for information on the biology, distribution, and abundance of these species in southern California waters.

Potential Effects of Seismic Surveys on Marine Mammals


Seismic surveys are used to obtain data about stratigraphic sequences and rock formations up to several thousands of feet deep. These surveys are accomplished by transmitting sound waves into the earth, which are reflected off subsurface formations and recorded with detectors in the water column.

Disturbance by seismic noise is the principal means of taking by this activity. Vessel noise may provide a secondary source. Also, the physical presence of vessel(s) could lead to some non-acoustic effects involving visual or other cues.

Depending upon ambient conditions and the sensitivity of the receptor, underwater sounds produced by open-water seismic operations may be detectable some 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. An incidental harassment take is presumed to occur when marine mammals in the vicinity of the seismic source (or vessel) react to the generated sounds or to visual cues.

Seismic pulses are known to cause some species of whales, including gray whales, to behaviorally respond within a distance of several kilometers (Richardson et al ., 1995). Although some limited masking of low-frequency sounds is a possibility for those species of whales using low frequencies for communication, the intermittent nature of seismic source pulses limits the extent of masking. Bowhead whales in Arctic waters, for example, are known to continue calling in the presence of seismic survey sounds, and their calls can be heard between seismic pulses (Richardson et al ., 1986).

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-dive-respiration cycles. More conspicuous responses include changes in activity or aerial displays, movement away from the sound source, or complete avoidance of the area. The reaction threshold and degree of response are related to the activity of the animal at the time of the disturbance. Whales engaged in active behaviors, such as feeding, socializing, or mating are less likely than resting animals to show overt behavioral reactions, unless the disturbance is directly threatening.

Hearing damage is not expected to occur during the project. While it is not known whether a marine mammal co-located or very close to the seismic source would be at risk of permanent hearing impairment, temporary threshold shift (TTS) is a theoretical possibility for animals close to the minisparker. However, planned monitoring and mitigation measures (described later in this document) are designed to detect marine mammals occurring near the seismic source(s) and to avoid, to the greatest extent practicable, exposing them to sound pulses that have any possibility of causing TTS in hearing.

Maximum Sound-Exposure Levels for Marine Mammals

The adverse effects of underwater sound on mammals have been documented for exposure times that last for tens of seconds or minutes, but adverse effects have not been documented for the brief pulses typical of the minisparker (0.8 ms) and the Huntec system (typically 0.3 ms). While NMFS in the past considered that the maximum SPLs, from impulse sounds, to which marine mammals should be exposed are 180 dB re 1 µPa-m RMS for mysticetes (baleen whales) and sperm whales, and 190 dB re 1 µPa-m RMS for odontocetes (toothed whales, dolphins and porpoises) and pinnipeds (seals and sea lions), recent workshops have recommended a more precautionary approach be taken and, accordingly, NMFS now recommends that odontocetes also be limited to an SPL no greater than 180 dB re 1 µPa-m RMS. However, based on statements and recommendations made at NMFS' Acoustic Criteria Workshop in 1998, NMFS has not increased its recommended safety zone for pinnipeds to this same level. In 1999, the California Coastal Commission (CCC) limited the maximum sound-exposure level to 180 dB re 1 µPa-m RMS for all species of marine mammals.

In its application, the USGS has provided two estimates of how close marine mammals can approach the minisparker source before it needs to be powered down. The first estimate follows the procedure required by the CCC in 1999, where underwater sound is assumed to attenuate with distance according to the equation 20log(Radius(R)), and the maximum SPL to which marine mammals can be exposed is 180 dB re 1 µPa-m RMS. The alternative estimate of safe distance is proposed for operations limited to shallow water. In shallow water, sound from the minisparker will decay (attenuate) with distance more sharply than 20log(R) because some of the sound energy will exit the water and penetrate the sea floor when the minisparker source is physically close to the sea floor.

In the deeper water (greater than 50 m (164 ft)) areas of the proposed survey, the safety zone for the minisparker is a circle whose radius is the distance from the source to where the SPL is reduced to 180 dB re 1 µPa-m RMS. For a 20log(R) sound attenuation, the safety zone for a 209 dB RMS source has a radius of about 30 m (98 ft).

Much of that part of the proposed 2000 survey that focuses on saltwater intrusion of coastal aquifers will be conducted close to shore, where water is shallow. In such areas, underwater sound commonly attenuates more sharply than 20log(R) because sound exits the water layer and penetrates into the substrate. In 1999, the USGS measured a sound attenuation of 27log(R) in shallow water off southern California. Therefore, the USGS proposes that for inshore areas, underwater sound will attenuate approximately like 25log(R), which for inshore areas would yield a safety zone with a radius of 15 m (49.2 ft). Because of this short radius of the safety zone in shallow water, the USGS proposes that the minisparker can be used at night, using spotlights to illuminate the safety zone around the tow sled.

Estimated Number of Potential Harassments of Marine Mammals

Based on estimated marine mammal populations within the survey area (Calambokidis and Francis, 1994) and on the number of individuals that were observed during the 1998 and 1999 seismic surveys, the USGS estimates that up to 50 blue whales, 5 killer whales, 10 minke whales, 10 sea otters, 50 humpback whales, 50 northern sea lions, 100 northern fur seals, 100 northern elephant seals, 100 Dall's porpoise, 100 Risso's dolphins, 100 northern right-whale dolphins, 100-200 Pacific white-sided dolphins, 100 bottlenosed dolphins, 200 California sea lions, 200 Pacific harbor seals, and 10,000-12,000 common dolphins may be harassed incidental to the USGS survey. No marine mammals will be seriously injured or killed as a result of the survey.

Proposed Mitigation of Potential Environmental Impact

To avoid potential Level A harassment (i.e., injury) of marine mammals, safety zones will be established and monitored continuously by biologists, and the USGS will shut off the seismic source whenever the ship and a marine mammal converge closer than the previously mentioned safety distance.

For gray, fin, blue and humpback whales, the marine mammal species near the survey area that are considered to be most sensitive to the frequency and intensity of the sound source, and for odontocetes, even with their lower sensitivity to the low frequency sound that will be emitted by the minisparker, minisparker operations will cease when members of these species approach within 30 m (98 ft) of the sound source when operating in deep water and 15 m (49.2 ft) when in shallow water as mentioned previously.

For pinnipeds (seals and sea lions), if the research vessel approaches a pinniped, a safety radius of 30 m (98 ft) around the seismic source when operating in deep water and 15 m (49.2 ft) when in shallow water will be maintained. However, if a pinniped approaches the towed minisparker source, NMFS proposes that it will not require the USGS to shutdown the minisparker, but will require the USGS to monitor the interaction to ensure the animal does not show signs of distress. Experience indicates that pinnipeds will come from great distances to inspect seismic operations. Seals have been observed swimming within airgun bubbles, 10 m (33 ft) away from active arrays, apparently unaffected. Although minisparker oprations will be terminated if the pinnipeds show obvious distress, the USGS will conduct observations on effects the minisparker may have on the animals.

The USGS plans to have marine biologists aboard the ship who will have the authority to stop the minisparker operations when a marine mammal enters the safety zone. If observations are made that one or more marine mammals of any species are attempting to beach themselves when the source is operating in the vicinity of the beaching, the minisparker will be immediately shut off and NMFS contacted.

During seismic-reflection surveying, the ship's speed will only be 4 to 5 knots, so that when the minisparker is being discharged, nearby marine mammals, if they hear the low frequency noise, will have gradual warning of the vessel's approach and can move away if disturbed. Finally, NMFS will coordinate with the local stranding network to determine whether strandings can be related to the seismic operation. If NMFS determines, based upon a necropsy of the animal(s), that the death was likely due to exposure to the minisparker, the survey shall cease until procedures are altered to eliminate the potential for future deaths.

Operating less than 24 hours each day incurs substantially increased cost for the leased ship, which the USGS states that it cannot afford. The ship schedule provides a narrow time window for this project; other experiments are already scheduled to precede and follow this one and for that reason, the USGS cannot arbitrarily extend the survey time. Thus, the USGS does not propose as a mitigation measure shutting down in dark or during periods of poor visibility. The 2000 survey will require only three weeks, and it will be spread out geographically from Los Angeles to San Diego, so no single area will experience long-term activity. In the view of the USGS, the best course is to complete the experiment as expeditiously as possible. For these reasons, the USGS has requested that the Incidental Harassment Authorization (IHA) allow 24-hour operations, specifically at night and limiting surveys during this time to shallow water.

Monitoring and Reporting

Monitoring marine mammals while the minisparker is active will be conducted 24 hours each day. Trained marine mammal observers will be aboard the seismic vessel to mitigate the potential environmental impact from minisparker use and to gather data on the species, number, and reaction of marine mammals to the minisparker. During daylight, observers will use 7x50 binoculars with internal compasses and reticules to record the horizontal and vertical angle to sighted mammals. Night-time operations will be conducted with a spotlight to illuminate the safety zone around the minisparker tow sled. Monitoring data to be recorded during minisparker operations include the name of the observer on duty, and weather conditions (such as Beaufort sea state, wind speed, cloud cover, swell height, precipitation, and visibility). For each mammal sighting, the observer will record the time, bearing and reticule readings, species, group size, and the animal's surface behavior and orientation. Observers will instruct geologists to shut off the minisparker whenever a marine mammal enters the safety zone.

Possible Modifications or Alternatives to the Proposed Survey

The instructions for this permit request stipulate that the USGS consider alternatives to the proposed experiment. Options to change the activity are limited, but for the proposed survey, the USGS has changed from using an airgun source as used in prior surveys to a minisparker in order to reduce the probability for the harassment of marine mammals and to be able to operate within nearshore areas.

To abandon this study altogether is a poor option. The USGS has described the societal relevance of this project as it would improve understanding of fluid movement in coastal aquifers and how to stem the intrusion of salt water into them. Another facet of this study is to help scientists understand the regional earthquake hazard that, in turn, will aid city planners in establishing building codes. If the project was canceled, such information would be unavailable.

The seismic-source strength cannot be reduced further in an attempt to limit the potential environmental impact. The proposed minisparker is already smaller than any source the USGS has previously used for these kinds of geophysical surveys, and the problem with this option is that the USGS cannot significantly reduce the source strength without jeopardizing the success of this survey. This judgment is based on USGS' decades-long experience with seismic-reflection surveys, but especially on the 1998 survey that was conducted in the same general area as outlined here. If the USGS were to reduce the sound-source size and then fail to obtain the required information, another survey would need to be conducted, and this would have the potential to increase impact on marine mammals.

This project could be carried out at some other time of year, and the USGS is open to suggestions. The USGS talked with biologists to find out the best time for the project to be conducted. The USGS wants to avoid the gray whale migrations and the mid-summer arrival of other mysticete species because, while these species remain mostly in the area of the Channel Islands, some individuals venture closer to the mainland. An important consideration in deciding the most appropriate time of the year is that biologists can best prevent harm to mammals when daylight is long, that is, near the solstice.


The USGS will contract with qualified marine-mammal observers to provide an initial report to NMFS within 160 days of the completion of the 2000 phase of the marine seismic project. This report will provide dates and locations of seismic operations, details of marine mammal sightings, and estimates of the amount and nature of all takes by harassment. A final technical report will be provided by USGS within 1 year of completion of the 2000 phase of the marine seismic project. 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, NMFS has begun consultation on the proposed issuance of an IHA. Consultation will be concluded upon completion of the comment period and consideration of those comments in the final determination on issuance of an authorization.


NMFS has preliminarily determined that the short-term impact of conducting marine seismic-reflection data in offshore southern California will result, at worst, in a temporary modification in behavior by certain species of pinnipeds and cetaceans. While behavioral modifications may be made by certain species of marine mammals to avoid the resultant noise from the minisparker, this behavioral change is expected to have a negligible impact on the animals.

In addition, no take by injury and/or death is anticipated, and takes will be at the lowest level practicable due to the incorporation of the mitigation measures previously mentioned. No known 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.

Proposed Authorization

NMFS proposes to issue an IHA to the USGS for the possible harassment of small numbers of several species of marine mammals incidental to collecting marine seismic-reflection data off southern California, provided the previously mentioned mitigation, monitoring, and reporting requirements are incorporated. NMFS has preliminarily determined that the proposed activities would result in the harassment of only small numbers of each of several species of marine mammals and will have no more than a negligible impact on these marine mammal stocks.

Information Solicited

NMFS requests interested persons to submit comments, information, and suggestions concerning this request (see ADDRESSES ).

Dated: March 22, 2000.

Donald R. Knowles,

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

[FR Doc. 00-7611 Filed 3-27-00; 8:45 am]