| Summary: | We examined the distribution and abundance of marine birds and mammals in the northern Gulf of Alaska over five seasons during the winters of 1997-2001. We recorded 58 species of seabirds, which were dominated numerically by five species; species-richness was greatest in October and May and lowest in December and March. Abundance was greatest in May and October, in the winters of 1997-1998 and 1999-2000, and, depending on the species, at the shelf-break front or in the mid-shelf. The shelf-break front is highly important to the overwinter survival of a variety of bird and mammal species; the mid-shelf zone appears to be important to a suite of diving seabirds that concentrate on nekton, especially fishes. We recorded 10 species of marine mammals, which were dominated numerically by Dall's Porpoises; the seasonal pattern of species-richness was identical to that seen for seabirds. Abundance of Dall's Porpoises was greatest in the Alaska Coastal Current, whereas several other species were concentrated at the shelf-break or widespread. We conclude that an at-sea monitoring program can provide valuable information on wintering seabirds and recommend that a seabird monitoring component be added to the proposed Gulf Ecosystem Monitoring Program. Publications: Day, R. H., and A. K. Prichard. 2004. Biology of wintering marine birds and mammals in the northern Gulf of Alaska. Exxon Valdez Oil Spill Restoration Project Final Report (Restoration Project 00287), ABR Inc., Environmental Research and Services, Fairbanks, Alaska.
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