207 



Presently, the cause or causes for these declines are not 

 known; however, a list of potential causes includes 

 entanglement in lost or discarded fishing gear, incidental 

 take in driftnet, trawl, and other fisheries; decreased food 

 availability due to overharvesting of pollock or other 

 finfish; decreased food availability due to climate or other 

 natural changes affecting the distribution, abundance, or 

 productivity of important prey species; natural diseases; 

 intentional shooting; and environmental pollution. 62 

 Regardless of the precise reason these changes are occurring, 

 the fact remains that a major unexplained reduction in numbers 

 of animals in the Bering Sea has taken place. Such 

 reductions, left unchecked, may result in irreversible change 

 in the structure and productivity of the entire ecosystem. 



Traditionally, the Bering Sea has maintained a high level 

 of biological productivity, supporting a substantial food web 

 which includes up to 25 species of marine mammals, 32 species 

 of seabirds, 30 species of waterfowl, and sizable populations 

 of fish. In turn, this productivity has allowed the Bering 

 Sea to play host to a number of commercial industries. Prior 

 to 1900, economic attention centered around the acquisition of 

 Northern fur seal and sea otter furs. Overhunting soon 



62 Gordon L. Swartzman and Robert J. Hofman, Uncertainties and 

 Research Needs Regarding the Bering Sea and Antarctic Marine Ecosystems 1 

 (Final Report for Marine Mammal Workshop Held December 12-13 1990). 



[19653-0001/DA940590.060] -37- 



