August 22, 2002
The sea otter population has dropped 12.2
percent since 1997, and dropped in 2001 to 2161 from 2317 in
2000 - a 6.7 percent decline in one year.
Today the sea otter is an endangered species
and a "fully protected mammal" under California law. They
are also protected under Canadian and Russian
laws.
Much of the research on the sea otter has
been done since the 1989 Exxon Valdez oil spill in Alaska's
Prince William Sound.
There are estimated to be a few thousand,
sea otters in Alaska and the Aleutians, a few dozen in
California.
This is down from 300,000 worldwide before
the eighteenth century. In the eighteenth and nineteenth
centuries they were hunted for their fur. The sea otter
lacks the blubber that keeps whales, seals, and other marine
animals warm, but possesses the thickest fur of any mammal,
up to a million hairs per square inch.
The sea otter survey encompasses San
Francisco to Santa Barbara. The cause of the decline is
being argued among the scientists; it could be caused by
over-fishing or a slight rise in water
temperature.
A group of scientists believe that the
whale's usual prey, the Stellar sea lions and harbor seals,
is so diminished that they're resorting to feeding on otters
and that this is the main reason for the otters' decline in
numbers, but this is debatable.
James Estes of the US Geological Survey
believes that the otters are too fat and healthy to be
suffering from food shortages and no signs of an epidemic or
widespread contaminant have been found.
Researchers have observed that otter
populations dropped in a whale-accessible area but did not
in a bay that the whales couldn't reach.
It wouldn't take many whales to devastate
the otter population because it is possible that a single
whale could consume 1,825 otters per year.
Greg Saunders, U.S. Fish & Wildlike
Service coordinator for the sea otter says "The three year
average of survey results indicates that the sea otter
population is more or less stable. However, the numbers fall
short of our recovery goals for the species."
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Resources:
BioScience Online
Chang, Maria L.,
Scholastic Science World, Feb 22 99
Cohn, Jeffrey P.,
March 1998
Estes, James, US Geological Survey,
2001
Hay, Mark E., Ecologist, University of North
Carolina, 1998
