In March 1998, the U.S. Geological Survey, in collaboration with a number of other government and academic institutions, conducted seismic surveys in the greater Puget Sound area to investigate earthquake hazards. The project was named SHIPS (Seismic Hazards Investigations in Puget Sound) and was conducted from 10 to 24 March 1998. The surveys consisted of measuring responses to a towed array of 12-16 air guns with a total volume of 5,500-6,500 cubic inches. Maximum theoretical source levels for such an array were calculated to be on the order of 260 dB (re 1 µP at 1m).
Although seismic tests and other applications of loud low-frequency sound in waters have been used for many years, there has been a heightened concern in recent years about the impacts of these sounds on marine mammals. In the last year for example, the HESS (High Energy Seismic Surveys) team has been organized to evaluate the impacts of seismic exploration primarily off California. This team includes the Minerals Management Service, National Marine Fisheries Service, other regulating state and federal agencies, representatives of the oil industry and fishing groups and environmentalists.
We report here the results of a marine mammal mitigation and monitoring program conducted in conjunction with the SHIPS surveys. This effort was originally designed by the authors in conjunction with USGS and NMFS. The mitigation requirements and safety zones employed in these surveys and reported on here were the result of negotiations between USGS and NMFS and were incorporated into the permit issued by NMFS to USGS for the incidental taking of marine mammals.
Calambokidis, J. and S.D. Osmek. 1998. Marine mammal research and mitigation in conjunction with air gun operation for the USGS “SHIPS” seismic surveys in 1998. Report to the U.S. Geological Survey, National Marine Fisheries Service and Minerals Management Service. 29pp.Download PDF
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