| Summary: | Fur seals on the Pribilof Islands have been declining for 40 years, and losses since the early 1970s remain unexplained. A number of possible causes have been investigated. Some factors have been considered and rejected, and others are still being debated. Current leading hypotheses include effects of commercial fisheries and climate change on prey availability in the Bering Sea, and predation by killer whales. Steller sea lions, harbor seals and sea otters have also experience large population declines in areas that are important to northern fur seals (i.e., the western GOA, Aleutian Islands and the Bering Sea). Therefore, we propose to review the life history strategies and influential factors affecting northern fur seals in the Bering Sea, where they reproduce and raise pups, and in the N. Pacific, where female and juvenile fur seals migrate and over winter for about eight months each year. We will compare fur seal ecology to that of Steller sea lions, harbor seals and sea otters in the North Pacific to help evaluate which factors may be important in the fur seal decline on the Pribilof Islands. Such a review will enable us to make recommendations about hypotheses and questions that need further research. This literature review and critical evaluation will ultimately be of benefit to the conservation of fur seals, the rational management of commercial fisheries, and an understanding of the effects of climate change and predation on individual species and on marine ecosystems. Background and relevance to research priorities
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