Sea otters that live from southwestern Cook Inlet to the tip of the Aleutian Chain will now get more federal protection and a biological investigation into why their population has crashed by more than two-thirds since 1980.
Alaska's southwest stock of northern sea otters will be listed as threatened under the Endangered Species Act, officials with the local office of the U.S. Fish and Wildlife Service said Monday.
If published today in the Federal Register as scheduled, the decision will take effect Sept. 8.
Within a few months, officials hope to appoint a team that will find out what, if anything, people can do to help the animals recover, said biologist Doug Burn, sea otter team leader for the agency in Anchorage.
"There's been reduced abundance in places, but to our knowledge, they have not been completely wiped out from any areas," he said. "That leads me to be hopeful."
Listing otters as threatened will likely have little impact on subsistence hunting by Alaska Natives or commercial fishing, but it will trigger more studies and surveys of the near-shore waters where the furry marine mammals forage for sea urchins and other shellfish, Burn said. Identifying specific areas critical to the animals will be one major chore.
The sea otter decline comes amid other mysterious shifts in the marine ecosystem near Alaska, with some species rising and some dropping fast. Driven largely by studies of the endangered Steller sea lion, more than $120 million has been spent over the past five years to investigate marine climate change, food problems, disease, contaminants and increased predation by killer whales. New sea otter studies by federal agencies, the Alaska SeaLife Center and independent scientists are under way.
So far, no one has found a simple answer.
"The loss of sea otters is an indication that there are some things going on out there in the ecosystem that we don't really understand, and we need to find out more," Burn said.
Sea otters in the North Pacific were almost driven extinct in the 19th century by fur hunters. Fewer than 2,000 animals remained in 13 isolated colonies when they were given international protection in 1911.
After rebounding for almost eight decades, biologists estimated that 94,000 to 128,000 otters lived from Kodiak Island out the Alaska Peninsula and Aleutian Chain, perhaps 80 percent of all the northern sea otters in the world.
Then, for reasons that remain unclear, the southwest Alaska stock began to decline, dropping to about 42,000 by the early 2000s, Burn said. Some areas along the Alaska Peninsula and far western Aleutians saw the steepest declines.
One of the most stunning examples occurred in the Rat Islands, home to an estimated 3,000 otters in the early 1960s.
Five years ago, a team of biologists found 192 animals in the same area -- a plunge of 94 percent over four decades.
The conservation group Center for Biological Diversity petitioned the agency in 2000 to list the otters as threatened or endangered, then filed suit in 2003 to force the agency to move faster.
In a statement e-mailed to journalists on Monday, center attorney Brent Plater urged the agency to quickly identify critical habitat.
"Saving the sea otters will be a complex task, because they may be an indicator of ecosystem decay in the Bering Sea," Plater said. "Scientists have shown that species with critical habitats protected are twice as likely to be recovering as those without."
Scientists say otters declined so fast that something had to be killing individual animals. Disease, starvation, and contaminants don't appear to be major factors. They've got plenty of sea urchins and shellfish to eat. In fact, urchins have become so abundant off some Aleutian Islands that they're eating up the kelp forests, altering the marine habitat and causing a crisis of their own.
"I don't think that subsistence hunting is playing a major role," Burn said. "And there's not a lot of overlap (with commercial fishing.) ... We don't think competition for prey is an issue for sea otters."
Some scientists argue that certain kinds of killer whales may have caused the decline or made it worse after switching prey from whales to sea otters over the past few decades. But many whale biologists disagree.
Adding to the mystery, sea otters that live further east in the Kenai Fjords area or in Prince William Sound appear to be stable or increasing in number.
Daily News reporter Doug O'Harra can be reached at do'harra@adn.com.
