MARINE MAMMAL COMMISSION — Annual Report for 1991 



• revise the definitions of Class A, B, and C stocks 

 to make it clear that the burden of proof will 

 remain, as presently is the case under the Marine 

 Mammal Protection Act, on potential users to 

 demonstrate that levels of taking do not disadvan- 

 tage the affected marine mammal species and 

 stocks; 



• describe the program or programs the Service is 

 planning or proposing to move toward the zero 

 mortality rate goal; 



• provide an estimate of the funding and special 

 logistic requirements that would be required to 

 implement the proposed assessment, monitoring, 

 and mortality reduction programs; and 



• if it has not already done so, revise the assessments 

 of possible economic impacts in the Legislative 

 Environmental Impact Statement to use the Marine 

 Mammal Protection Act prior to 1988, to which 

 the interim exemption will revert absent enactment 

 of new legislation, as the baseline against which 

 the various alternatives are compared. 



The Commission also noted that, in the recom- 

 mended guidelines forwarded to the Service in July 

 1990, it had recommended that the National Marine 

 Fisheries Service and the Fish and Wildlife Service, 

 in consultation with the Commission, the Fishery 

 Management Councils, and other relevant organiza- 

 tions, hold a workshop or series of workshops in 1991 

 or 1992 to consider and provide advice on: (1) 

 thresholds below which exploitation of fish stocks 

 should be prohibited to ensure maintenance of target, 

 dependent, and associated species at optimum sustain- 

 able levels (i.e., to ensure the fullest possible range of 

 management options for future generations); (2) 

 guidelines and procedures for dealing with uncertainty 

 concerning the status of and numerical and functional 

 relationships among fish stocks and other components 

 of the ecosystems of which they are a part; and (3) 

 research and monitoring programs needed to fill 

 critical gaps in our knowledge of the structure and 

 dynamics of marine ecosystems and to verify the 

 predicted effects and detect the possible unforeseen 

 effects of fishery management programs. The Com- 

 mission noted fiirther that the Service had not re- 

 sponded to this or a number of the other reconmienda- 

 tions made in the Commission's recommended guide- 



lines and in its 23 September 1991 comments on the 

 Service's initial proposed regime. The Commission 

 reiterated its belief that failure to carry out the recom- 

 mended actions could result in fisheries having 

 significant adverse effects on marine mammals and the 

 ecosystems of which they are a part. Thus, the 

 Commission requested that, if the Service decides not 

 to adopt one or more of these recommendations, the 

 Service provide it widi a detailed explanation as to the 

 reasons why the recommendations were not followed 

 or adopted, as required by section 202(7)(d) of the 

 Marine Mammal Protection Act. 



At the end of 1991, the Service was reviewing the 

 comments received on its revised proposal. It is 

 expected that the Service will complete and transmit 

 to Congress its suggested regime to govern the taking 

 of marine mammals incidental to commercial fishing 

 operations, and issue a Final Legislative Environmen- 

 tal Impact Statement on the proposal, early in 1992. 



The Tuna-Porpoise Issue 



For reasons not fully understood, schools of large 

 yellowfin tuna (>25 kg) tend to associate with 

 dolphin schools in the eastern tropical Pacific Ocean, 

 an area of more than five million square miles stretch- 

 ing from southern California to Chile and westward to 

 Hawaii. In the late 1950s, U.S. fishermen began to 

 exploit this association by deploying large purse seine 

 nets around the more readily observed dolphin schools 

 to catch the tuna swinmiing below. Despite efforts by 

 the fishermen to release the encircled dolphins, some 

 become trapped in the nets and drown. As discussed 

 below, efforts to reduce the incidental mortality of 

 dolphins in this fishery have been a central focus of 

 the Marine Mammal Protection Act since its enact- 

 ment in 1972. Early efforts under the Act focused 

 almost exclusively on the operations of the U.S. purse 

 seine fleet. Beginning in the mid-1980s, however, the 

 focus shifted to reducing dolphin mortality from 

 foreign tuna fishing activities in the eastern tropical 

 Pacific. 



Background 



The eastern tropical Pacific tuna purse seine fishery 

 was dominated by the United States fleet during the 

 first two decades of its existence. At its peak in the 



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