Sea Otters Tagged for Population Study

Photo by Alaska Sea Grant Program

Add sea otters to the list of critters transmitting radio signals in Southeast Alaska.

Researchers recently captured and tagged the marine mammals north of Petersburg. It’s part of a project studying the habits and rapid spread of otters, which were reintroduced to the region a little more than 40 years ago.

U.S. Fish and Wildlife Service biologist Verena Gill is part of a cooperative effort that captured and tagged 30 sea otters near Kake. They ranged from babies to a male weighing more than 100 pounds.

“I think a lot of times people think that they’re a cute, cuddly, small, little creature. They are cute, but they’re not cuddly and they are not small,” she says.

Scientists and others implanted VHF radios so they can track movement and monitor behavior.

They also sampled bodily fluids and whiskers to check for viruses and learn more about diet. She says otter studies can help track other environmental issues.

“Otters are a real good canary in a coal mine, so to speak. They’re a really good indicator of what’s happening in the near-shore ecosystem. They inhabit the same area that we do. They eat many of the same subsistence foods that we do. They’re impacted by runoff from terrestrial environments. And so they are really sort of like a first warning system as to what is going on,” she says.

The capture program is one of several coordinated sea otter research projects going on in the region. Another will determine their numbers in northern Southeast, following a similar count in the south.

A third effort is monitoring feeding behavior from shore.

Zach Hoyt, of the University of Alaska School of Fisheries and Ocean Sciences, is part of that project.

“They’re voracious predators. They have the ability to consume 25 percent of their body weight a day in invertebrates. They have a very, very high metabolism because they’re the only marine mammal that does not have blubber, so they have to fuel themselves and they do that through consuming energy,” he says.

That energy comes from eating large amounts of crab, sea urchins, shrimp, clams and sea cucumbers.

“It’s kind of like watching a Tasmanian devil eat,” says Sunny Rice, who works with the Petersburg office of the university’s Marine Advisory Program.

She says research on otter numbers and feeding habits will help crabbers and dive fishermen anticipate future impacts.

“As otters were moving into new areas they traditionally fished, they were not seeing any more of that resource,” she says.

The fur trade virtually wiped sea otters out in Southeast Alaska by the early 1900s. The state transplanted the mammals to the region in the 1960s.

Recent population growth in the southern part of the region has been 13 percent a year.

Hoyt, the university researcher, says that‘s not as surprising as it seems.

“Well, right now I would say the population is definitely growing exponentially, which is typical of a species that isn’t resource limited,” he says.

The sampling part of the capture project will also help define otter diet. Wildlife biologist Gill says whiskers can show what’s been consumed during the past year.

“And the real exciting thing about that is we had a series of whiskers spanning the last 20 years from animals that had been harvested by Native people in the area. We had those analyzed and we’ll be able to compare the diet from 20 years ago to the contemporary animals we captured here in May,” she says.

Federal protections limit otter harvests to Alaska Natives. Pelts can only be sold to the general public if they’re been significantly modified.

Researchers are asking hunters to avoid taking tagged otters. But they’re also interested in information about any carcasses, which could become part of the scientific database.

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