Mysterious otter decline in Alaska – 04/06/2004

  • September 30, 2013 at 7:55 pm #441
    By Jeffrey Hope
    Updated: 2:36 a.m. ET April 06, 2004
    April 5 – Alaska’s dramatic sea otter population decline has
    researchers around the globe concerned. This week, the Alaska SeaLife
    Center in Seward is hosting a workshop on the issue. The sea otter
    population in Southwest Alaska has been declining for years, and
    researchers hope this special conference will help find out why.

    It’s a rare gathering of both Russian and U.S. sea otter experts.
    Researchers from both countries have been extensively studying sea
    otters for years. The last 20 years, there’s been a dramatic decrease
    in the sea otter population, from 56 percent to 68 percent down on
    the Alaska Peninsula and Aleutian Chain. The cause remains unclear.

    Doug Burn is a biologist with the U.S. Fish and Wildlife
    Service. “I’d like to see more of these comprehensive studies that
    look at things like survival, look at things like starvation, and
    what’s out there for them to eat, look at things like contaminants
    and disease,” he says. “Basically, this holistic approach to try to
    rule out some of these other possibilities and hopefully narrow in on
    some sort of cause.”

    Burn may get his wish. The conference is designed to help researchers
    determine which project should be done next, while the U.S. Fish and
    Wildlife Service goes through the long process of proposing the sea
    otter be listed as a threatened species.

    So what’s to blame? Jim Estes has the most controversial idea so far.
    He believes killer whales are eating more sea otters because other
    prey populations have also declined.

    “It seems to me that the most obvious explanation is that, when they
    ran out of these other things, they expanded their diet to include
    other species, and sea otters were one of those other species. And
    that’s what happened,” Estes said.

    Another mystery is that populations in Russia, just a few hundred
    miles from Alaska, are stable. The Russians are proposing more
    studies in the Commander Islands, an ecosystem the SeaLife Center is
    also targeting as an important research area.

    “I think we have to give all of the ideas equal weighting until
    there’s enough evidence to be able to dismiss them,” said Shannon
    Atkinson of the Alaska SeaLife Center.

    Over a century ago, some populations were hunted to near extinction.
    Now, this population could see a similar fate, but nobody knows why.
    The U.S. Fish and Wildlife Service is accepting public comments on
    the proposal until June 10. They expect to make a decision by
    February 2005.

    Researchers say they see almost no sea otter carcasses on beaches
    anymore, where they used to be common. That leads them to suspect
    that many more otters are dying at sea.

    Also, during about 4,000 hours of observation time, biologists saw
    killer whales make six successful strikes on sea otters. Researchers
    say that, plugging those numbers into a computer model would yield
    approximately the decline in numbers that they’re seeing, so it’s
    possible that orcas actually are taking thousands of otters each year.

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