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Contrasting Western Steller Sea Lion and Northern Fur Seal
Population Trends in Alaska

AFSC Quarterly
Research Reports
Jan-Mar 2006
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photo of steller sea lions

Adult bull, fremale, and juvenile Steller sea lions.

The western stock of Steller sea lion (Eumetopias jubatus) and the northern fur seal (Callorhinus ursinus) are sympatric over large portions of their ranges in Alaskan waters, and both have declined substantially over the past 30 years. These population declines have resulted in a listing of ‘endangered’ for the western Steller sea lion under the Endangered Species Act, and of ‘depleted’ for the northern fur seal under the Marine Mammal Protection Act. 

Though both share some common traits, significant differences exist in body size (northern fur seals are much smaller than similarly aged Steller sea lions), life history traits, and in how each utilizes the marine environment. Exploring the interrelationship among these traits and environmental variables may help elucidate underlying environmental or anthropogenic factors affecting survival and reproductive rates, and hence population trends, of these two species.

This article presents results of the most recently completed Steller sea lion and northern fur seal abundance surveys and examine their population trends from 1976 through 2005.

Read the complete article>>>
pdf; 586KB

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