NOAA 99-R127
Contact: Stephanie Dorezas


NOAA's Fisheries Service is seeking comment on an application and proposed authorization for Western Geophysical of Houston, Texas, to potentially disturb small numbers of marine mammals while conducting seismic surveys in the Western Beaufort Sea in state and federal waters of Alaska.

Under the Marine Mammal Protection Act, Western Geophysical has applied for a permit to incidentally disturb small numbers of bowhead whales and other marine mammals during oil and gas surveys in the Western Beaufort Sea.

NOAA's Fisheries Service may grant permission to incidentally harass these mammals if it finds the surveys will have a negligible impact on marine mammals and will not significantly affect the availability of marine species for subsistence uses. Also, the company must meet proposed mitigation, monitoring and reporting guidelines.

If a marine mammal authorization is approved, the survey is expected to take place between about July 1 and Oct. 20, 1999, during the open water or ice-free season.

The Beaufort/Chukchi Seas support a diverse assembly of marine mammals, including bowhead whales, gray whales, beluga whales, ringed seals, spotted seals and bearded seals.

It is possible the harvest of some marine mammals (mainly bowhead whales, ringed seals and bearded seals) by native hunters from coastal North Slope communities may be affected. Migrating marine mammals (principally bowhead whales) may move farther offshore due to possible behavioral changes from elevated noise levels, and this could potentially make the subsistence harvest of this species more difficult.

Seismic surveys collect data about oil-bearing rock formations several thousands of meters deep. Sound waves are transmitted into the earth, which are reflected off subsurface formations and recorded. A typical marine seismic source is an airgun array that releases compressed air into the water, creating an acoustical energy pulse that is directed into the earth. Hydrophones (oceanic microphones) spaced along the ocean bottom receive the reflected energy from the subsurface formations and transmit the data to the surface vessels. On board, the signals are amplified, digitized, and recorded on magnetic tape.

The airguns emit pulsed energy primarily at frequencies in the 10 to 300 Hz range. Small whale and seal hearing is believed to be poor at frequencies less than 1,000 Hz, and should be relatively unaffected by the survey, although the beluga whale and the seals may detect some sounds at these frequencies. However, bowhead and gray whales have been known to move away from a seismic search area.

As part of the proposed authorization, NOAA's Fisheries Service proposes that Western Geophysical observe several operating procedures designed to avoid potential injury to marine mammals. NOAA's Fisheries Service proposes 1) biological observers onboard the seismic vessels monitor marine mammal presence in the vicinity of the seismic array (the array would be powered down if seals or whales are sighted within a designated safety zone, depending on the species); 2) the airguns be brought to operating levels over a several-minute period at the commencement of operations or after any period where the array is powered down; and 3) if marine mammals are observed within a safety zone designated to prevent injury to the animals, start-up operations will be delayed until all marine mammals are outside that distance.

In addition, Western Geophysical is developing an agreement with Native American subsistence whalers to reduce any potential interference with their hunt as well as provide information to help resolve uncertainties about the effects of seismic exploration on the accessibility of bowheads to hunters.

Comments will be received through June 28,1999, for the application from Western Geophysical. Comments should be addressed to Chief, Marine Mammal Division, Office of Protected Resources, National Marine Fisheries Service, 1315 East-West Highway, Silver Spring, MD 20910-3225. Copies of the application and an environmental assessment may be obtained by contacting the above office.

NOAA's Fisheries Service is an agency of the Commerce Department's National Oceanic and Atmospheric Administration. The Fisheries Service is dedicated to protecting and preserving our nation's living marine resources through scientific research, management, enforcement, and the conservation of marine mammals and other protected marine species and their habitats.