CHAPTER VI 



MARINE MAMMAL/FISHERIES INTERACTIONS 



Interactions among marine mammals, finfish, shellfish, 

 and other components of marine ecosystems present complex and 

 often difficult problems for those responsible for making 

 conservation and management decisions. One of the most 

 widely known examples of such interaction problems — the 

 incidental take of porpoises in the yellowfin tuna purse 

 seine fishery in the eastern tropical Pacific Ocean (dis- 

 cussed in Chapter VII) — was one of the issues that prompted 

 Congress to pass the Marine Mammal Protection Act. 



The Commission, in consultation with its Committee of 

 Scientific Advisors on Marine Mammals, has devoted consi- 

 derable attention and funding to efforts to identify, assess, 

 and resolve problems caused by marine mammal/fisheries 

 interactions. Activities prior to 1986 have been reported in 

 previous Annual Reports. A brief summary of these earlier 

 efforts and a description of activities in 1986 are provided 

 below. 



Background 



Interactions between marine mammals and fisheries can 

 take various forms and have significant adverse effects on 

 the involved marine mammal populations, the involved fish- 

 eries, or both. Marine mammals can be caught and killed or 

 injured, either accidentally or deliberately, during routine 

 fishing operations. They can also be caught in lost and 

 discarded fishing gear. Fishermen, on the other hand, can be 

 affected when marine mammals take or damage fish caught on 

 hooks, in traps, and in nets, or when their fishing gear is 

 damaged or destroyed. Further, marine mammals and fishermen 

 may compete in some areas for the same fish and shellfish 

 resources. This can cause or contribute to depletion of the 

 fish and shellfish resources and result in fundamental 

 changes in the marine food web as well as have significant 

 adverse effects on the competing marine mammals and fish- 

 eries. 



Prior to enactment of the Marine Mammal Protection Act 

 in 1972, regulated and unregulated hunting, bounty programs, 



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