April 13, 2006
Scientists Use Labs to Find Arctic Seals
ANCHORAGE, Alaska -- America's most popular dog is a big hit with scientists who are using Labrador retrievers to hunt up seals for study in the Arctic.
The dogs are proving nifty at finding the breathing holes and snow lairs of ringed seals, which after centuries of being hunted by human and beast alike, are strictly covert."Ringed seals are pretty well adapted to not being found because they live in a world with polar bears and human seal hunters," said Peter Boveng, program leader for the National Marine Mammal Laboratory in Seattle. "You can walk along on top of the snow on top of the ice and see no sign of them whatsoever."
Seals begin maintaining breathing holes in the ice at freeze-up in the fall. Once there is enough snow, they excavate snow caves.
"They come up, they clear holes through long cracks in the ice and excavate little caves in the snow," Boveng said.
Boveng and Brendan Kelly, an associate professor of marine biology at the University of Alaska Southeast, as well as other scientists, are entering into a second season of tagging ringed seals to get basic information about numbers and breeding sites. The study hinges on being able to find the seals - no small issue it turns out.
"Fortunately, for us the problem had been solved a long time ago by Inuit hunters," said Kelly, who has been tagging seals since 1982. "They figured out their dogs could smell the seal holes under the snow."
Kelly learned to use Labs to find seals from a Canadian biologist and an Inuit hunter in the Northwest Territories of Canada. He trained his first Lab to find seals by burying sealskin slippers in the snow.
During the hunt, the dogs run ahead of researchers traveling on snowmobiles. Hand and voice commands are used to tell the dogs to find 'natchiq' - the Inupiaq word for ringed seal.
When the dogs get a whiff of seal, they run in a zigzag pattern, which gets shorter as the dogs zero in on the source, and presto - a breathing hole or lair. The dogs start digging at the spot, but are quickly called off so that researchers can set up a capture net at the hole.
Kelly said the net fits in the bottom of the hole.
"What happens is that the seal swims up through an open net into the breathing hole. We hear the seal breathing through a microphone and transmitter that we've placed in the snow and that transmits back to our hut," Kelly said.
When the scientists hear the seal breathing, they close the net using a radio trigger.
"Then we get on our snowmobiles and take a quick ride back to the seal hole," Kelly said.
Once there, the snow cover is swept off and the seal is grabbed and pulled onto the ice for tagging.
Kelly tried finding seals without the help of dogs, using an infrared camera that detects body heat. It didn't work.
"Under ideal conditions, we could detect the seal holes under infrared sensors only if the dogs first showed us where it was," he said.
The dogs have an 80 to 85 percent success rate within several miles of the campsites and can find between 100 and 200 holes a month.
The satellite tagging study in Peard Bay and Point Barrow in northernmost Alaska, more than 300 miles above the Arctic Circle, is entering its second season. Kelly expects to return to the Arctic on May 8. Last year, 13 seals were tagged. This year the goal is 20.
Last year, they learned that ringed seals use the same breeding sites each year. What they hope to find out this year is whether the seals breed with each other throughout the Arctic, in effect creating one big gene pool, or if breeding takes place locally.
Preliminary findings suggest the seals are breeding locally, but more study needs to be done, Kelly said, and with a lot more DNA samples. To get more samples, scientists are extracting DNA from skin samples left by the seals at the breathing holes.
"These are like little pepper flakes on the ice," Boveng said.
Global warming is raising concerns for the future of the seals, especially if they're breeding only locally, Kelly said.
"One of the things we are seeing is increasingly early snow melts," he said. "The pups' very survival depends on inhabiting the snow cave for the first couple months of their lives while they are still nursing."
Early snow melts expose the pups to the harsh Arctic and leaves them vulnerable to predators. They can freeze to death, Kelly said.
"If you have lots of small isolated populations, each one of them is more vulnerable to local extinction," Kelly said.
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