INTRO: Few animals are as difficult to study as the Pacific walrus. They're big, for one thing. And they sometimes don't take well to anesthetizing drugs. As Sonya Senkowsky reports in this week's Arctic Science Journeys Radio, researchers in Alaska hope to make their jobs easier by combining modern technology with an ancient hunting tool.
STORY: The Pacific walrus is a massive animal, about the size and weight of a compact car. Before working up close with these two-tusked Titans, researchers need to dart them with drugs that temporarily put the animals to sleep.
But there's a problem. These mighty giants are wimps when it comes to drugs. They can be felled by just a few drops of anesthetic. And sometimes they can't be revived.
Dave Tessler is a wildlife biologist with the United States Geological Survey in Alaska.
DAVE TESSLER: "Drugging a walrus is an extremely difficult business. It's dangerous for the researchers. It's dangerous to the walrus."
One complication is that a drugged animal can dive underwater, then drown. Tessler says another problem involves a natural process unique to marine mammals.
TESSLER: "They have a physiological response to being under water, which involves shutting off blood supply to the skin and large portions of their outer body and maintaining circulation to their brain and their internal organs, while slowing down their heart rate, slowing down their breathing, slowing down their metabolism."
If a drugged walrus reacts this way, its body might be unable to circulate the reversal drug that's supposed to wake it up.
Compared to the thousands of walrus killed annually by hunters on both sides of the Pacific, the deaths due to darting by researchers are minimal. Maybe a half dozen have died under his watch, says Tessler. But getting up close to walrus for research is so difficult in the first place that every loss is a major setback.
TESSLER: "It's not why I got into wildlife biology was to kill animals. The reason we're studying walruses is to help preserve them."
Pacific walrus live throughout the Chukchi and Bering seas that separate Alaska from Russia's Siberia. The last big census, done more than ten years ago, indicated a population of about 200,000. But there has been no new population information in years. And, although there is evidence that many animals in the Bering Sea are under stress, it's difficult to know if walruses are among them, because researchers lack the most basic population information.
TESSLER: "We have no idea how many walruses there are. We haven't yet come up with even an index to population, something we can measure year after year and see if the populations are decreasing, because they are spread over such a wide area, they are so remote."
In the meantime, there is reason to be concerned. Climate change has been melting sea ice; walruses give birth on the ice. Tissue and organ samples collected by hunters on both sides of the North Pacific Ocean support the concern that females are becoming sexually active at a younger age—a possible sign of a population in trouble. But until they have better population information, researchers can't be sure.
Tessler says researchers could use a way of tagging walrus that wouldn't require scientists to actually touch the animals. One solution is a prototype tagging device that Alaska researchers hope to try this spring. Dave Tessler explains the device, which is a specially modified crossbow.
TESSLER: "Crossbows are lethal most of the time, but this is a veterinary crossbow. You can adjust the power on it so at really close range you can deliver an arrow soft, so you're not going to penetrate the animal any more than you want to or need to. The other thing that distinguishes it is that it has a fishing reel on it, so we can retrieve the arrows with either the biopsies or the applicators to the tags we put in."
The researchers want to try the crossbow delivery system with two kinds of arrows. One would collect tissue samples. The other, with a steel harpoon head similar in design to those used by walrus hunters for centuries, would attach a small radio tracking device. Similar instruments have been used on whales, but never on walrus.
Over the past year, researchers have been describing the idea to Alaska and Russian Native hunters. This spring, they hope to test the devices on carcasses, then move on to live animals. Before conducting their studies, the scientists must wait for federal approval. In a show of respect, they will also ask for permission from Alaska Native hunters.
Researchers are eager to see how well the tagging device will work. Chad Jay is the walrus research program leader:
JAY: "A large part of it depends on the amount of retention time we get out of it. I think we can tag animals with it and get these things in initially. The bigger question, I think, is going be how long they stay in. If they stay in for a few months, then I think they will be useful for looking at short-term movement patterns. If we can use these tags to deploy transmitters, then it broadens its use even more."
OUTRO: This is Arctic Science Journeys Radio, a production of the Alaska Sea Grant Program and the University of Alaska Fairbanks. I'm Sonya Senkowsky.
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Thanks to the following individuals for help preparing this script:
Chadwick V. Jay
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. The shortcut to our ASJ news home page is www.asjnews.org.
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Walrus Numbers Decline —Arctic Science Journeys Radio
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