MARINE MAMMAL COMMISSION - Annual Report for 1995 



Table 5. Subsistence harvest levels for northern fur seals in the Pribilof Islands, 1985-1995 1 



1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 



St. Paul 

 St. George 

 Total 



3,384 1,299 1,710 1,145 1,340 1,077 1,645 



329 124 92 113 181 164 281 



3,713 1,423 1,802 1,258 1,521 1,241 1,926 



1,482 1,518 1,616 1,265 



194 319 161 260 



1,676 1,837 1,777 1,525 



Data provided by the National Marine Fisheries Service, Alaska Region. 



Northern Fur Seal Stock Assessments 



In 1994 the Marine Mammal Protection Act was 

 amended to provide a new approach for managing 

 interactions between marine mammals and fisheries. 

 In part, it required that the National Marine Fisheries 

 Service prepare stock assessments for all marine 

 mammal stocks in U.S. waters. The assessments are 

 to include estimates of key population parameters, 

 such as size and maximum productivity, in order to 

 calculate a potential biological removal level (not 

 including natural mortality) that, if taken, would allow 

 a stock to increase towards its optimum sustainable 

 population level. To assure that commercial fisheries 

 do not cause mortality in excess of this level, the 

 assessments also must include a determination as to 

 whether the stock is a "strategic stock" possibly 

 requiring the establishment of an incidental-take 

 reduction team and preparation of an incidental-take 

 reduction plan. 



The Service circulated draft stock assessments for 

 review in August 1994 and final stock assessments in 

 August 1995. It concluded that northern fur seals in 

 U.S. waters consisted of two distinct stocks — an 

 eastern Pacific stock composed of animals breeding on 

 the Pribilof Islands and Bogoslof Island and a San 

 Miguel Island stock in southern California. 



Eastern Pacific Stock — Based on fur seal census 

 data collected in 1994, the final stock assessment for 

 the eastern Pacific fur seal stock estimated its size to 

 be 1,019,192 animals, including an estimated 5,173 

 animals on Bogoslof Island. Using population growth 

 trends from 1912 to 1940 — a period of steadily in- 

 creasing numbers — the Service concluded that the 



maximum net annual productivity rate for the popula- 

 tion is 8.6 percent. Based on this and other data, the 

 stock's potential biological removal level was calculat- 

 ed to be 20,846 animals per year. Because the 

 Pribilof Island fur seal population is listed as depleted 

 under the Marine Mammal Protection Act, the stock 

 was automatically considered a strategic stock (see 

 Chapter IV for discussion of strategic stocks). 



In commenting on the draft assessment in 1994 the 

 Commission noted that, unless it could be inferred 

 why the stock presently is not growing, it would seem 

 that a potential biological removal level could not be 

 calculated for this stock. The Service's determination 

 of a potential biological removal level, however, did 

 not address this point, and given the lack of popula- 

 tion recovery since the early 1980s, it is questionable 

 whether the estimated potential biological removal 

 level would allow the population to increase if that 

 number was actually removed. 



Based on fishery observer and logbook data, the 

 Service noted that incidental take in commercial 

 fisheries appears to be insignificant, approaching a 

 zero mortality and serious injury rate. Six fisheries in 

 the Bering Sea and Gulf of Alaska are thought to be 

 potential sources of incidental take for northern fur 

 seals. The Service estimated that these fisheries 

 resulted in a total annual mortality rate of less than 10 

 animals now that high-seas driftnet fishing, a previous 

 source of incidental take, was no longer authorized. 

 Considering the low incidental-take rate, no action 

 was taken in 1995 to constitute a take reduction team 

 for this stock even though it is considered a strategic 

 stock. 



40 



