Many marine species are currently undergoing severe population declines. Of the 26 species of marine mammals that inhabit the Bering Sea :
- Seven great whales are listed as endangered under the Endangered Species Act (ESA);
- The Steller sea lion is listed as endangered in the western portion of its range, and has declined by over 80 percent in the past 25 years;
- The northern fur seal is listed as depleted under the Marine Mammal Protection Act, and now numbers approximately 20% of its historical high;
- Sea otters have declined by over 90% in the western Aleutian Islands and have recently been listed under the ESA .
Some seabird populations are declining rapidly; others have experienced nesting failures for the past several years. Of the seabirds in the Bering Sea :
- The Short-tailed Albatross is listed as endangered under the ESA ;
- Spectacled Eiders are listed as endangered under the ESA , Steller’s Eiders are listed as threatened, and King Eiders are proposed for listing as threatened;
- Red-faced Cormorants have declined on St. Paul Island by 70% since the mid 1970s;
- Red-legged Kittiwakes have declined by 40-60% in the Pribilof Islands during the same period.
Some commercially important fish and shellfish populations have crashed, resulting in fishery closures, most notably the once lucrative king crab fisheries around the Pribilof Islands . Herring, a previously abundant fish, has declined in the eastern Bering Sea . Declines of some fish species may be contributing to declines in the populations of top level predators, such as sea lions, fur seals, and seabirds. Residents of coastal villages report seeing marine mammal species that have never before been seen in their traditional waters, and warm surface waters in some years have resulted in widescale plankton blooms.
Agents of change
The Bering Sea ecosystem continues to undergo natural environmental changes, many of which we do not yet understand. The sea has also been influenced by human activities for more than 200 years and the effects of human activities are little understood. Even less understood are the synergistic effects of natural and anthropogenic changes in the Bering Sea , and whether those changes are permanent or reversible on a human timescale. Major agents of change in the Bering Sea include:
- Climate Change
- Introduced species, such as Norway rats and foxes, that prey upon nesting seabirds
- Commercial fishing, including overfishing of some important species, bycatch of non-target fish, incidental take of seabirds (e.g. Short-tailed Albatross), and damage to sensitive bottom habitats from contact with fishing gear
- Oil spills and other accidental or illegal spills
- Persistent Organic Pollutants (POPs) and other pollutants
- Marine debris
- Salmon ranching/farming (Russia only)
- Invasive marine species
- Overhunting (e.g. of polar bears and, potentially, some seal species)
- Increased shipping and changes to shipping routes (e.g. noise disturbance and increased risk of collision).