MARINE MAMMAL COMMISSION - Annual Report for 1995 



On 4 January 1995 the Service responded to the 

 Commission's request for reclassification criteria for 

 Steller sea lions. It noted that it had been reviewing 

 the general guidelines for listing species under the 

 Endangered Species Act as well as related scientific 

 analyses but, because of the broad non-objective 

 nature of advice on the matter, it had been unable to 

 develop specific relisting criteria for Steller sea lions. 

 It added, however, that an important element in its 

 deliberations would be the results of population 

 viability analyses. In this regard, it noted that an 

 endangerment threshold generally accepted by the 

 scientific community was the probability of extinction 

 within the foreseeable future, which for many mam- 

 malian species is about 100 years depending on life 

 history information. The Service also assured the 

 Commission that it would use the best available 

 scientific information to make its decision. 



Final results of the 1994 population survey con- 

 firmed that the declining trend was continuing but at 

 a somewhat slower overall rate. Based on the new 

 data, the Service published a proposed rule in the 

 Federal Register on 4 October 1995 to change the 

 Endangered Species Act listing for Steller sea lions. 

 Its proposal recognized two stocks separated east and 

 west of Cape Suckling, Alaska, (east of Prince Wil- 

 liam Sound) and called for listing the western stock as 

 endangered and the eastern stock as threatened. 



Regarding the western stock, the Service noted that 

 from 1990, when the species was listed as threatened, 

 to 1994 counts of adult and juvenile sea lions at trend 

 monitoring sites had declined by 21 percent, and pup 

 numbers had declined by 28 percent. Applying 

 population trend data from 1985 to 1994 to two 

 population viability models — one based on composite 

 population trends and the other on individual rookery 

 trends — the Service found a 100 percent probability 

 of extinction within 100 years in both cases. Consid- 

 ering only data from 1989 to 1994, however, the 

 models predicted 100-year extinction probabilities of 

 65 and 10 percent, respectively. 



Unlike the decline of the western stock, counts for 

 the eastern stock have been relatively stable. Overall 

 counts of juvenile and adult animals at monitoring 

 sites in the eastern stock's range increased by 17 

 percent between 1990 and 1994 and, given its trend, 



the Service predicted that the eastern stock would 

 persist for the foreseeable future. The Service noted, 

 however, that prior to the decline, the proportion of 

 U.S. Steller sea lions in the area of the eastern stock 

 was less than 10 percent. It also noted that Steller sea 

 lion numbers in California, the stock's southern limit, 

 had declined 50 percent between 1950 and 1980 and 

 19 percent between 1990 and 1994, suggesting that 

 the species' range may be shifting northward. Also, 

 pup counts in central and southeast Alaska, which had 

 been stable to increasing before 1991, declined by 20 

 percent between 1991 and 1994. In view of these 

 latter points and other information, the Service 

 concluded that the eastern stock should be considered 

 vulnerable and remain listed as threatened. 



At the end of 1995 the Marine Mammal Commis- 

 sion, in consultation with its Committee of Scientific 

 Advisors, was completing a review of the Service's 

 listing proposal and expected to provide comments 

 early in 1996. The Commission found that the Notice 

 provided a thorough, well-reasoned analysis of the 

 proposed changes. With the 1994 counts of Steller 

 sea lions in the western stock's range now less than 20 

 percent of those in the 1960s, the Commission 

 planned to express support for its listing as endan- 

 gered. Given the recent declines in pup production at 

 the northern end of the eastern stock's range and the 

 disappearance of the southernmost colony in Califor- 

 nia, it also planned to support listing of the eastern 

 stock as threatened. 



Habitat Protection 



As noted above and in previous annual reports, 

 between 1990 and 1994 the Service took a number of 

 actions to protect Steller sea lion rookeries, haul-out 

 sites, and prey resources. In 1995 the measures 

 specifically relating to Steller sea lions were not 

 modified or expanded. However, in its 4 October 

 1995 Federal Register notice on the species' status 

 under the Endangered Species Act, the Service noted 

 that, given the western stock's high probability of 

 extinction within 100 years under current trends, 

 actions taken during the next 20 years would be 

 crucial for the survival of that stock. To help identify 

 additional measures that might be taken, the Federal 

 Register notice invited comments on needed changes 

 with respect to buffer area rules protecting important 



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