ANCHORAGE - Scientists asked by Congress to find out why the Steller sea lion population has plummeted in Alaska have concluded commercial fishing probably is not the main culprit.
The conclusion presented Wednesday to the North Pacific Fishery Management Council differs from that reached in November 2000 by the National Marine Fisheries Service, which said Alaska's $1 billion groundfish fishery was a threat to the survival of Steller sea lions competing for food.
That conclusion resulted in fishing restrictions and closures around sea lion rookeries in the Bering Sea and Gulf of Alaska, and a request by Sen. Ted Stevens, an Alaska Republican, for an independent scientific review.
Congress over a two-year period has allocated more than $80 million for research on Steller sea lions, money secured mostly through Stevens' efforts. Sea lions since 1997 have been protected under the federal Endangered Species Act. Alaska has about 64,000 Steller sea lions.
The National Research Council scientists, part of the National Academy of Sciences, found that the impact of commercial fishing on sea lion numbers has been overemphasized.
While not the main culprit, it cannot be ruled out as a "contributing factor" for why Steller sea lions in Alaska have declined by more than 80 percent in the past 30 years, said Gordon H. Kruse, fisheries professor at the University of Alaska Fairbanks, while presenting the report's executive summary at the council meeting in Anchorage. The full report will be ready later this month.
At the same time, more emphasis should be placed on what the 12 scientists call "top-down" factors - those factors that would kill sea lions regardless of the environment. They include predation by killer sharks, entanglement in fishing gear, illegal shootings, fatal disease, and underestimates of subsistence harvesting.
The scientists compared the "top-down" factors to "bottom-up" factors. Those are environmental factors that likely would limit the amount, quality or variety of foods, causing a physical deterioration in the animals. Those factors include commercial fishing, climate change, non-lethal disease and pollutants in fish.
Kruse said commercial fishing may have been a bigger factor from 1985 to 1990, when sea lion numbers declined precipitously by more than 15 percent a year.
But a look at the animals now, when the decline has slowed, finds that sea lions are getting enough food. That would indicate that it is the "top-down" factors that are at work, Kruse said.
The scientists recommend adjusting the fishing restrictions now in place to set up management units in Western Alaska to collect more data. Each region would include rookeries open and closed to fishing.
"This is the only approach that directly tests fishing," Kruse said.
Terry Leitzell, lawyer for Seattle-based Icicle Seafoods, a company that has operations from Petersburg to Dutch Harbor, said the important thing about the report is that it points to other possible causes for the decline in sea lions besides fishing.
Larry Cotter, CEO for the Aleutian Pribilof Island Community Development Association, who chaired the committee that came up with the fishing restrictions, said the panel should be reconvened in light of the new report.
"The results validate what a lot of people have felt for quite some time that fishing does not seem to be part of the problem," Cotter said.