Walrus Numbers Decline
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INTRO: Throughout the North Pacific Ocean, scientists say some marine mammals, fish and seabirds are in dramatic decline. As Doug Schneider reports in this week's Arctic Science Journeys Radio, that list may soon also include the Pacific walrus.
STORY: When Brendan Kelly went to the Bering Sea ice edge each of the last two years, he saw very few walrus calves. So few that he began to worry about the long-term health of these huge marine mammals.
KELLY: "You know these cruises have suggested to us that, boy, these are very low proportion of calves and one-year-olds and two-year-olds in that population. It does have the effect of telling us, boy, we might have to worry."
Kelly is a marine mammal scientist at the University of Alaska. He says that in a growing walrus population, at least 35 percent of the females should have calves with them. But the rates he saw were far less, in some places in the single digits.
KELLY: " Survival certainly seems to be low. Productivity and juvenile survival combined seem to be quite low in recent years."
One possible explanation for the decline may be that walrus populations are merely down from levels estimated at 250,000 in the early 1980s. Annual harvests of 10,000 walrus by Alaska and Russian Natives aren't considered a threat. Another possibility is that the population crash may be linked to dramatic declines also being experienced by other mammals, seabirds and fish in the Bering Sea.
KELLY: "Are we looking at a population that's stable around a new carrying capacity? Or in fact is the population declining more rapidly than that? There are other pinniped populations and seabird populations in the Bering Sea and the Gulf of Alaska that have declined quite dramatically in the last couple of decades. The important question for us is, is something similar happening to walruses? Unfortunately we don't have a good way of counting walruses."
Confounding the issue is a lack of good data on the overall number of walrus living from Alaska westward into Russia, an area of sea and ice roughly the size of California. During the Cold War, the U.S. and the Soviet Union counted walrus every five years. The irony today is that even though relations have improved, Russia's economic crisis means there's no money to continue the surveys.
KELLY: "The question now is what's happened in the last 15 years since we stopped collecting aerial survey data and really have no good index or pulse of the population."
The answer may lie in a new population model Kelly is creating that predicts the long-term future of the population based on trends in calf production and survival.
KELLY: "What we're trying to do here is try to look at these other population parameters--productivity and juvenile survival--and ask the question: Are those parameters consistent with a population that's stable with carrying capacity or declining?"
The models are being created with funds appropriated by Congress last year as part of a $6-million-a-year research effort being run by the University of Alaska.
OUTRO: This is Arctic Science Journeys Radio, a production of the Alaska Sea Grant Program and the University of Alaska Fairbanks. I'm Doug Schneider.
Our thanks to the following individual for help in the preparation of this script:
Dr. Brendan Kelly
If you'd like more information about walrus, check out these web sites:
North Pacific Marine Research Program (NPMR): Walrus study
Smithsonian Institution's Museum of Natural History
Arctic Science Journeys is a radio service highlighting science, culture, and the environment of the circumpolar north. Produced by the Alaska Sea Grant College Program and the University of Alaska Fairbanks.
Alaska Sea Grant Homepage
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