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The National Marine Fisheries Service has defined the term 

 "optimum sustainable population" as — 



"...a population size which falls within a range from the 

 population level of a given species or stock which is the 

 largest supportable within the ecosystem to the population 

 level that results in maximum net productivity. Maximum net 

 productivity is the greatest net annual increment in 

 population numbers or biomass resulting from additions to 

 the population due to reproduction and/or growth less losses 

 due to natural mortality" (50 C.F.R. 216.3), 



Before they were extirpated by commercial hunting, sea 

 otters presumably inhabited most of the nearshore coastal waters 

 of California. Although habitat in some places, like san Diego 

 and San Francisco Bays, may no longer be suitable for sea otters, 

 there can be little doubt that (a) much of the presently 

 unoccupied historic sea otter range in California remains 

 suitable sea otter habitat; (b) less than one-half and possibly 

 less than one-third, of the available sea otter habitat in 

 California presently is occupied; and (c) the sea otter 

 population in California presently is below the lower limit of 

 its optimum sustainable population range as defined above. Thus, 

 nothing can be done to prevent or limit range expansion northward 

 until the population is determined to be within its optimum 

 sustainable range or Congress provides authority to do so, either 

 in the Marine Mammal Protection Act, the Endangered Species Act, 

 or free-standing legislation such as P.L. 99-625. 



Available information suggests that, historically, a large 

 part of the California sea otter population occurred in San 

 Francisco Bay. Because of pollution, sedimentation, increased 

 boat traffic, etc . , much of the historic sea otter habitat in the 

 Bay probably has been damaged or destroyed. In some areas, it 

 may be possible to restore and maintain suitable sea otter 

 habitat in the Bay. If sufficient habitat is available, or can 

 be made available through habitat restoration, it may be that the 

 nearshore coastal area from Point Conception north to, and 

 including, San Francisco Bay would support a population at or 

 above the maximum net productivity level, calculated with respect 

 to the largest population supportable by presently available 

 habitat in the State. Thus, before doing anything else, it might 

 be desirable to ask [direct] the Fish and Wildlife Service to 

 undertake a study, in consultation with the California Department 

 of Fish ard Game, to determine the amount of suitable and 

 potentially suitable sea otter habitat present in San Francisco 

 Bay and whether reoccupation of this habitat, at equilibrium 

 levels, would bring the California sea otter population within 

 its optimum sustainable population range. 



