The abundant waters of the Bering Sea and Gulf of Alaska once teemed with one of the world's largest concentrations of sea lions, fur and harbor seals, and seabirds. Today, intensive industrial trawling in the North Pacific seas is depleting fish populations, harming habitat and unnecessarily disrupting the ocean web of life. This industrial-scale fishing also takes food away from the ocean's top-of-the-food-chain predators, including the now endangered Steller sea lion.
Prior to the 1960s, when foreign factory trawlers first arrived in large numbers off the coast of Alaska, huge populations of wildlife thrived in the glacier-fed waters of the Bering Sea and Gulf of Alaska. Some of the world's largest populations of Steller sea lions, fur and harbor seals, and seabirds depend on pollock, mackerel, cod, some of the 300 fish species in the area.
In 1965 the estimated total population of western Steller sea lions was about 230,000 animals. Today, that number has dropped by about 85%. Within the sea lion's western population's core area, from the Kenai Peninsula to Kiska Island, the number of observed sea lions fell 140,000 adults and juveniles to less than 18,000 in 1995, a drop of 87%.
Harbor seal populations in the central Gulf of Alaska have declined by more than 90% in key locations since the 1970's. Between 1974 and 1995, harbor seal counts declined by more than 80% on Otter Island, also critical habitat for the Steller sea lion.
Significant declines in populations of marine birds, particularly murres and kittiwakes, have occurred in the Bering Sea and Gulf of Alaska since the 1960s.
The dramatic drops in populations of these marine mammals and birds are red flags that the North Pacific ecosystem is in trouble. The three species that have declined most significantly in western Alaska -- Steller sea lions, harbor seals, and fur seals -- are the three that compete most directly for the fish targeted by the trawl fisheries. The broad declines in marine mammals and birds indicate dramatic changes in the Bering Sea and Gulf of Alaska in the last 30 years.
The precipitous decline of the Steller sea lion, as well as harbor and fur seals and seabirds, coincides closely with the development of intensive, high-volume trawl fisheries. Beginning in 1964 with the development of a process for reducing pollock to a protein paste called surimi, the pollock catch from the Bering Sea soared from less than 175,000 metric tons to almost 1.8 million metric tons. About 40 million metric tons of pollock alone have been mined from the eastern Bering Sea in the last 3 decades.Rather than limit the expansion of commercial fisheries to areas outside critical habitat, in the years after Steller sea lions were listed under the Endangered Species Act, NMFS allowed the groundfish trawl fisheries to increase rather than decrease their catch inside sea lion critical habitat areas. The fisheries became compressed into short periods and focused in small areas that overlap significantly with designated critical foraging areas for sea lions.
In the Bering Sea, for example, the pollock catch in critical habitat areas alone rose from about 200,000 metric tons in the late 1970's to about 800,000 metric tons in 1995. Atka mackerel catches in critical habitat areas alone rose from less than 10,000 metric tons in the late 1970's to about 80,000 metric tons in 1996. Much of this concentrated fishing occurs in the winter, when pups are learning to forage on their own and many mothers are pregnant and nursing.
Fact Sheets
Steller Sea Lions - ENDANGERED!
Creating a Fishery that Sea Lions Can Live With
Decades of Decline
Additional Information
National Marine Mammal Laboratory Steller Sea Lion Research website
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