Center for Biological Diversity

The Bering Sea

Walrus. Photo by USFWS

Bering Sea vertebrate biodiversity assessment

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Last Updated July 31, 2006

During the height of the last Ice Age, the Bering Sea was a vast grassland that served as the gateway for people migrating from Asia to North America. Today, it is one of the most productive and diverse marine bodies in the world. Nineteen species of whales and dolphins, 10 other marine mammal species, more than 400 species of fish, and millions of seabirds representing more than 50 species all make their home in the Bering Sea. From Polar Bears hunting on the sea ice to volcanic islands covered with seabirds, the Bering Sea is one of the world’s last, best places for wildlife.


Despite cold winters and the remoteness of the Bering Sea, the productivity and richness of Bering Sea wildlife have drawn humans to the area for thousands of years. Following European exploration by the 1741 Bering Expedition, exploitation of wildlife in the Bering Sea began in earnest – driving two species, Steller’s Sea Cow and Pallas’s Cormorant, to extinction in a mere 30 years. Over the next 150 years, whaling and sealing for pelts, meat and oil drove one species after another to the brink of extinction. During the first half of the 20th century, whaling and sealing were largely phased out by international treaty and other laws, and a number of species subsequently recovered or are in the process of recovering.

Beginning in the 1950s, large-scale commercial fishing replaced whaling and sealing as a primary stressor on Bering Sea wildlife. Through the early 1970s, commercial fishing remained largely unregulated, and many stocks were overfished. In the eastern Bering Sea, overfishing has been largely controlled, despite the fact that nearly 50 percent of fish consumed in the United States come from the Bering Sea. Although sustainable for individual targeted stocks, commercial fishing still has many impacts on Bering Sea ecosystems through bycatch, habitat destruction, disposal of offal, and possible impacts on the prey-base of marine mammals.

The impacts of commercial fishing are compounded by natural fluctuations in the Bering Sea environment, which can be quite dramatic, and increasingly by the effects of global climate change caused by anthropogenic releases of greenhouse gases. Climate change is likely a primary factor in unprecedented changes observed in the Bering Sea in recent decades. These include earlier breakup of summer sea ice, persistent warm waters, large blooms of marine algae called coccolithophorids, a large increase in the abundance of jellyfish (lasting from the early 1980s through 2000), and shifts in the abundance and distribution of fish and marine mammals.


Northern Fur Seal
Photo by Pete Spruance

Biological data show a disturbing downward trend in a number of Bering Sea wildlife species. The North Pacific Right Whale population numbers as few or fewer than 100 animals, and only one calf has been sighted this century. The Common Eider declined by 53 percent from 1976 to 1996, breeding Spectacled Eiders declined by 96 percent on the Yukon-Kuskokwim (YK) Delta, and Aleutian Sea Otters suffered a 70 percent loss in their population from 1992 to 2000. Steller’s Sea Lions declined 90 percent since the 1960s and continue to decline in the western Aleutians. Northern Fur Seals on the Pribilof Islands have been declining since the 1970s, with numbers dropping by as much as 4-8 percent in recent years. Numerous commercial fish species also have declined, including Yellowfin Sole, Alaska Plaice, Pacific Ocean Perch and Greenland Turbot.


In recent years, the Center for Biological Diversity has taken a leading role in conserving Bering Sea wildlife. In 2006, the Center completed an assessment of the status of and threats to all Bering Sea vertebrate species. This assessment identified at least 549 vertebrate species living in the Bering Sea for all or part of the year, including 418 fish, 102 birds and 29 marine mammals. Of these species, we determined that 335 (61%) have an unknown status, 148 (27%) appear to be non-imperiled, and 66 (12%) are of conservation concern. Of the species of concern, 52 (79%) are vulnerable, nine (13.6%) are imperiled, and five (7.6%) are critically imperiled.

The fact that most species of concern in the Bering Sea are listed as vulnerable, and thus may not be at immediate risk of extinction, is cause for hope. For many of these species, positive reforms in management could forestall further decline. Toward this end, the Center has been actively engaged in obtaining greater protection of Bering Sea wildlife under the Endangered Species Act.

Following a petition and two lawsuits, the Center successfully obtained protection for the southwest Alaska population of the northern Sea Otter, which was listed as a threatened species under the Endangered Species Act in August 2005. The Sea Otter is one of very few species that the Bush administration has protected under the Act.

In 2001, the Center filed a petition to have the Kittlitz’s Murrelet protected as an endangered species. A seabird that has the unique habit of frequenting the edges of tidewater glaciers, the Murrelet is threatened by global warming and oil spills. In response to the Center’s petition, the U.S. Fish and Wildlife Service designated the Murrelet a candidate for listing, meaning that they agree it deserves protection, but that such protection is delayed. As a candidate, the Murrelet joins more than 250 other species that have been waiting for protection an average of 14 years. The Center is currently involved in litigation to force the agency to protect all of these species, including the Kittlitz’s Murrelet.

Polar Bear with cubs
Photo by Pete Spruance

Most recently, the Center petitioned to have the Polar Bear listed as a threatened or endangered species, and the U.S. Fish and Wildlife Service issued a positive initial finding on this petition. The Polar Bear is threatened by the loss of its sea-ice habitat to global warming. The Center is considering petitioning for a number of other Bering Sea species that are dependent on sea ice, such as the Pacific Walrus.

The Center has obtained critical habitat protection for a number of Bering Sea threatened and endangered species, including the Northern Right Whale, Spectacled Eider and Steller’s Eider, and is pushing for protection of the Bowhead Whale’s habitat. Critical habitat protection for these species covers literally millions of acres of the Bering Sea and could prove pivotal in protecting the Sea from overfishing, oil and gas development and other threats.

Spectacled Eider male
Photo by USFWS

Responding to a Center petition and lawsuit, for example, the National Marine Fisheries Service designated critical habitat for the North Pacific Right Whale in February 2006, including portions of Bristol Bay in the Bering Sea and north of Kodiak Island in the Gulf of Alaska. This designation will hopefully stop or seriously curtail plans to lease portions of Bristol Bay for oil and gas leasing and lead to greater safeguards on shipping traffic in the Bering Sea and Gulf of Alaska to avoid oil spills and collisions with whales.

The Center plans to continue to work to protect Bering Sea wildlife using the Endangered Species Act and other means to reduce threats from commercial fishing, oil and gas development, pollution, shipping and other problems.