Will Fishing Closures Stop the Decline of Endangered Steller Sea Lions?

C. J. Gudmundson/NMML/NOAA

To stop the continuing decline of endangered Steller sea lions (Eumetopias jubatus) in Alaska's Aleutian Islands, federal scientists are calling for closures of some Alaskan fisheries beginning January 2011. While conservationists say the measures don't go far enough, industrial fishers are already objecting. Scientists with the National Marine Fisheries Service (NMFS) insist that curtailing fishing is necessary to assure the sea lions' federally mandated recovery. "Their numbers have dropped to startling levels; that's why this is urgent," says Doug Mecum, a fishery biologist with NMFS in Juneau.

The scientists issued their recommendations this week in a draft Groundfish Biological Opinion—a report which was delayed for 2 years because of political infighting and to include data from a 2009 population survey of Steller sea lion pups. More than 4 billion pounds of groundfish—Pacific cod, pollock, and Atka mackerel—are harvested each year in the Bering Sea, Gulf of Alaska, and Bering Islands. Steller sea lions feed in these same waters and on these same species, as well as other fish and cephalopods. "We can't say that competition with fisheries is the absolute direct cause" of the sea lions' continuing decline, "but it may be playing a role," says Mecum, who helped prepare the report. If nothing is done, the report concludes that the western population of Steller sea lions faces extinction.

In the Opinion, the scientists report that the adult population of Steller sea lions in the western-most Aleutian Islands dropped 45% from 2000 to 2009, whereas the birth rate of new pups fell 43%—even though the animals have been protected under the Endangered Species Act since 1990. In the past 5 to 6 years, fishing has also intensified in this area, says Mecum, particularly around the rookeries and island haul-outs considered critical habitat for the sea lions.

Until the late 1960s, Steller sea lions numbered close to 250,000 in the North Pacific. Their numbers dropped by a staggering 80% over the next 2 decades as they drowned in fishing nets and were killed in legal harvests and predator-control programs. Once protected, the sea lions began to recover—at least in the central and eastern portion of their range. But the western population, once the largest in the world, has continued to struggle. Based on a survey this spring, only 1000 adult Stellers remain in the western Aleutians. "Their population [there] is declining at about 7% a year," says Douglas DeMaster, science director of NMFS's Alaska Fisheries Science Center, and another adviser on the draft opinion. "That's horrible."

Scientists have examined everything from climate change to contaminants to disease to the dietary preferences of killer whales. The NMFS researchers suspect that nutritional stress is the main culprit. "Given the very low birth rates, it's the best explanation," says DeMaster. At one island rookery, scientists counted only one pup this year; in 1979, there were 1142.

NMFS proposes shutting down the cod and mackerel fishery year-round across more than 131,000 square miles in the western Aleutians to give the sea lions a shot at recovery. It also recommends more limited fishing seasons and restricted fishing near rookeries in the area east of these islands. And while these changes are expected to cost the fishing industry some $32 million a year, they leave untouched the billion-dollar-a-year pollock fishery—a major failing of the Opinion, according to Greenpeace and other conservation groups. DeMaster imagines that the fishing restrictions will have to remain in place for a decade or more simply to stabilize the Stellers' population in this region.

The fishing industry is reeling from the proposed closures. "It's outrageous," says Gerald Thomas of the Fishing Company of Alaska in Seattle, Washington. "I've been fishing for 45 years and have never heard anything like this, and with nothing to really back up their claims."

Fishers and conservationists will be able to comment on the draft opinion later this month at a meeting in Anchorage of the North Pacific Fishery Management Council, an advisory group.