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.
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. 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.