NOAA 95-R129
Contact: Gordon Helm FOR IMMEDIATE RELEASE
(301) 713-2370 6/9/95
The National Oceanic and Atmospheric Administration is seeking public comment on an application and proposed authorization for Exxon Company, U.S.A. of Thousand Oaks, Calif., to potentially disturb small numbers of cetaceans while conducting a three-dimensional seismic survey in federal waters of the Santa Barbara channel.
Under the Marine Mammal Protection Act, Exxon applied for a permit to incidentally disturb the cetaceans during an oil and gas subsurface survey. As described in Exxon's application, the survey will cover an area of approximately 303 square kilometers (about 117 square miles) of the outer continental shelf and will require approximately two months.
Deep seismic surveys obtain data about formations several thousands of meters deep. These surveys are accomplished by transmitting sound waves 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 spaced along a streamer cable just below the surface of the water receive the reflected energy from the subsurface formations and transmit the data to the seismic vessel. On board the vessel, the signals are amplified, digitized, and recorded on magnetic tape.
Sound disturbance from the proposed survey could potentially affect some cetaceans, including most species of whale, swimming or transiting the area. The airguns emit pulsed energy primarily at frequencies in the 10 to 300 Hz range. The hearing of dolphins, porpoises, seals and sea lions is believed to be poor at frequencies less than 1,000 Hz, and should be unaffected by the survey. Only mysticete and sperm whales could hear or possibly react to the seismic sounds.
As part of the authorization request, NOAAþs National Marine Fisheries Service proposes that Exxon observe several operating procedures designed to avoid potential injury to marine mammals. The fisheries service proposes that 1) the airguns be brought to operating levels over a five-minute period at the commencement of operations or after any period where the array is powered down; 2) the array not be turned off at times when restarting it would occur during nighttime hours; and 3) if marine mammals are observed within 300 feet of the source, that operations be delayed until all marine mammals are outside that distance. The fisheries service also is recommending approved observers be required to monitor the impact of the seismic activities on marine mammal populations during the survey.
The fisheries service has determined that the survey may result in some temporary modification in behavior by certain species of cetaceans to avoid seismic noise, but this behavioral change is expected to have only a negligible impact on the animals.
Comments will be received through July 7, 1995, and 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 may be obtained by writing to the same address.