Scientists track seal migration into Chukchi Sea

Posted: Tuesday, October 30, 2001

ANCHORAGE (AP) -- Scientists working from Little Diomede Island in the Bering Strait have used satellites to track a ringed seal during its spring migration, logging a trip of more than 400 miles with dives as deep as 150 feet.

It's the first time anyone has tracked a ringed seal in open sea ice, which is where the animals live, scientists say.

''The main thing it does is tell us about the migratory movements of this animal during this time period,'' said Bob Small, marine mammals coordinator for the Alaska Department of Fish and Game. ''Due to their association with ice, it's hard to monitor these guys.''

The satellite tracking device has been used extensively by scientists tracking marine mammals, but this was the first time a ringed seal had worn one.

The seal was captured by local residents of Little Diomede Island using what Fish and Game biologist Gay Sheffield described as a ''clever and effective'' method. A homemade plywood slide was pushed out from a blind to block the animal's escape down a breathing hole, she said. Scientists then cornered the animal and glued the tracking device to its fur.

The tracking lasted about seven weeks, with the animal probably losing it when it molted, Small said.

The new information provides a key link in the lives of the ringed seals, whose worldwide population is estimated at somewhere between two to seven million animals, ranging all around the northern polar region.

The Alaska population of ringed seals is estimated at a million to a million and a half.

''In Alaska, the large-scale movements of ringed, bearded and ribbon seals are unknown except in a general sense,'' Sheffield said. ''At this point, the only northern seals in Alaska for which we have had even an inkling of their movements are spotted seals.''

It's important to learn about migration patterns for these species so scientists have baseline information to evaluate changes in behavior over the years, particularly if global warming alters the northern environment, Small said.

He cited, as an example, the difficulty biologists have had in evaluating the impact of the Exxon Valdez oil spill because they didn't have information about populations and movements there prior to the spill.

Sheffield has been working at Little Diomede for several months each year for the last three years. Between that and her experience in other remote villages, she has gained valuable information from the people of the northwest Alaska region, Small said.

''I was working with men who work with these animals on a daily basis,'' Sheffield related. ''They are the experts on the animal's local behavior and movements. It was a privilege to be able to unite scientific and traditional knowledge to gain a better understanding of ringed seal life history.''

Sheffield's work is part of a National Science Foundation project that has focused on gathering data about the movement of nutrient-rich water from the North Pacific into the Arctic Ocean, Small said.

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