Chapter III — Species of Special Concern 



decision marked the end of the plaintiffs administra- 

 tive review process. 



Sea Otter Stock Assessments 



As discussed in Chapter IV, amendments to the 

 Marine Mammal Protection Act in 1994 established a 

 new regime to govern the incidental taking of marine 

 mammals in commercial fisheries. Among other 

 things, they required the National Marine Fisheries 

 Service and the Fish and Wildlife Service to prepare 

 stock assessments for all marine mammal stocks in 

 U.S. waters. Each assessment is to estimate the size 

 and maximum productivity rate of the stock, calculate 

 a potential biological removal level (not including 

 natural mortality) that would allow the stock to remain 

 or increase towards its optimum sustainable population 

 level, assess incidental-take levels in commercial 

 fisheries, and determine if a stock is a strategic stock 

 requiring special management attention. 



On 15 August 1994 the Fish and Wildlife Service 

 distributed to the Marine Mammal Commission and 

 others draft stock assessments for marine mammal 

 populations under its jurisdiction, including sea otter 

 stocks in California, Washington, and Alaska. As 

 discussed in the previous annual report, the Commis- 

 sion, in consultation with its Committee of Scientific 

 Advisors, reviewed the drafts and by letter of 1 

 December 1994 provided comments to the Service. 



Final stock assessments for sea otters and other 

 marine mammals under its jurisdiction were circulated 

 by the Fish and Wildlife Service on 4 October 1995. 

 Based on its 1994 spring survey, the minimum size of 

 the California sea otter population was estimated at 

 2,359 animals. The population is continuing to 

 increase, and its maximum net productivity rate is 

 estimated at six percent a year. Based on available 

 data, the estimated potential biological removal level 

 for the California sea otter stock is 7 animals. The 

 assessment noted, however, that this estimate serves 

 no practical purpose since incidental take of the 

 California sea otter is not governed under section 1 18 

 of the Marine Mammal Protection Act. 



The assessment further noted that, since 1985, 

 when fishing restrictions were enacted to protect sea 

 otters from incidental take in gill and trammel nets, 



known fishing-related mortality was zero in 1991 and 

 1992, one in 1993, and zero in 1994. However, the 

 level of take of sea otters in lobster and crab fisheries 

 in California is unknown. The assessment concluded 

 that, if the restrictions on gill and trammel nets were 

 lifted, the California sea otter stock would be classi- 

 fied as a strategic stock. 



The Service's final stock assessment of the Wash- 

 ington sea otter stock estimates a minimum population 

 of 360 animals and a maximum annual growth rate of 

 about 20 percent. The potential biological removal 

 level is set at 11 animals. The assessment noted that 

 known instances of incidental take of sea otters in 

 fisheries are rare and other sources of human-caused 

 mortality are not well documented. 



The Washington sea otter stock has no federal 

 designation as either threatened or endangered al- 

 though it is legally designated as endangered by the 

 State of Washington. The Service's stock assessment 

 concluded that the population is below its optimum 

 sustainable population level. 



The Service's final assessment for the Alaska sea 

 otter population established a minimum population 

 estimate of 100,000 animals. The assessment noted 

 that information on population growth rates is not 

 available for all areas in Alaska; therefore, it adopted 

 a maximum net productivity rate of 20 percent. 

 Using these data, the Service calculated the potential 

 biological removal level at 10,000 sea otters per year. 

 It noted, however, the impact of such a removal could 

 realistically be considered not adverse only if the 

 removal is allocated throughout the state and takes 

 into account the sex and age of the harvested animals. 



With respect to human-caused mortality, the assess- 

 ment noted that activities associated with oil and gas 

 development have the potential for adversely impact- 

 ing sea otters and their habitat in Alaska, and that 

 approximately 2,650 sea otters died as a result of the 

 1989 Exxon Valdez spill. Subsistence harvest of sea 

 otters is estimated at approximately 1.2 percent of the 

 total population and is not believed to have affected 

 the Alaska sea otter population as a whole. The 

 assessment noted, however, that the harvest must be 

 spread throughout the population's range to ensure 

 that overharvesting does not occur in local areas. 



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