Killer whales preying on otters

2010-10-16 14:16

Anchorage - A report by government scientists identifies killer whales as the No 1 reason there are so few sea otters in southwest Alaska.

The US Fish and Wildlife Service's proposed a five-year, $15m recovery plan for sea otters in the Aleutian Islands considered a slew of possible reasons for the perilously low numbers found in some areas.

The draft recovery plan released this week said there is only one threat considered to have high importance: predation by killer whales, with sharks perhaps being a factor.

Nearly all other factors, including climate change and impacts from humans, were considered to have low importance.

The report said there may be "few actions that can be taken" to mitigate predation by killer whales ". But the sea otter recovery program should search for solutions and be open to novel ideas," the report said.

The southwest Alaska sea otter population, which has declined by more than 90% in some areas, has been listed as threatened since 2005. In 1976, there were an estimated 94 050 to 128 650 sea otters. Now, there are an estimated 53 674 animals, and perhaps fewer.

The recovery plan does identify some other potential threats to sea otters, most importantly the role of disease and whether there is adequate oil-spill response in southwest Alaska.

One hundred years ago, fur harvesting nearly wiped out the world's population of northern sea otters. By the time international treaty protection was granted in 1911, there were fewer than 1 000 sea otters in 13 remnant colonies. They eventually repopulated much of their original habitat.

The southwest Alaska population began its steep decline in the mid-1980s.

If fully implemented, the recovery plan would cost $15m over the next five years. There is a 120-day public comment period.

The plan calls for dozens of actions in five units stretching along more than 1,500 miles of shoreline, from the western Aleutian Islands to Kodiak and the Alaska Peninsula.

Actions include monitoring the population, protecting habitat, managing the impact of human uses and protecting sea otters from human as well as natural threats.

The plan also considers potential threats from biotoxins, contaminants, food limitations, commercial fishing, the subsistence harvest, loss of habitat and illegal take.