Sunday, August 14, 2005

Alaskan sea otters

Alaska Sea Otters to Get U.S. Protection:
Southwest Alaska's sea otters, which came back from the brink of extinction in the 1800s, are facing another dramatic decline and could be named a "threatened" species as early as Tuesday [August 9].

There are no clear answers why the population across a wide swath of Alaska has plummeted or how to reverse the decline, said Douglas Burn, leader of the U.S. Fish and Wildlife Service's sea otter program.

"It is a complex task, partly because we don't know with 100 percent certainty how we got here," Burn said.

Southwest Alaska's sea otters have recovered before. They were nearly wiped out by more than 150 years of commercial hunting before receiving international protection in 1911. By the mid-1980s, the population had burgeoned to as many as 129,000.

Today, however, only about 40,000 inhabit the area extending from the west side of Cook Inlet to the Alaska Peninsula and Kodiak Island, west to the Aleutian Islands and beyond to the Russia-U.S. maritime border.

The move to list the sea otters as threatened follows a 2003 lawsuit accusing the Interior Department of failing to protect them. The Arizona-based Center for Biological Diversity argued that without action, sea otters in the Aleutians and Alaska Peninsula would become extinct.
There's a lot of neat biology around sea otters. They were hunted for their fur for many years. When they were protected, they recovered. When sea otters were in decline, sea urchins expanded their range and overpopulated. The urchins eat kelp, so the kelp was eradicated in some areas, eliminating habitat for various other species.

As otters recovered, orcas started preying on them. It's unclear whether otters were orca prey previously, but the orca predation in some areas is considered to be a source of the threat to the otter. It's possible that an unexplained decline in the population of Steller's sea lions caused the prey shift. Some people think global climate change may have caused the changes in sea lion populations, but that's still very speculative.

Ain't ecology grand?