Photographs of frolicking sea otters projected onto a screen greeted students, staff and members of the public coming into Egan Library Thursday night for the “Sea Otter Symposium” hosted by the University of Alaska Southeast.
Meanwhile, posters at the back of the room described studies done and conclusions reached by University of Alaska Fairbanks and United States Fish and Wildlife Service researchers, many of them on the impact of surging northern sea otter populations in Southeast Alaska.
Six sea otter experts gave presentations on the marine animals, which were eradicated from Southeast Alaska by overhunting during the height of the commercial fur trade, but have thrived since their reintroduction to the region in the 1960s.
“Protection from harvest and translocations have been successful in restoring the species to much of its range,” said James Bodkin, a retired U.S. Geological Survey research biologist, describing one of the main conclusions of his study of sea otter populations.
Wildlife biologist Verena Gill, of the USFWS, said an aerial survey of Southeast Alaska that she conducted over the past three years suggests a population of about 25,000 sea otters.
“We went from 400 animals to about 25,000 animals,” Gill said. “I mean, that’s … just a wonderful story.”
Several of the speakers explored the effects that resurgent sea otters have had on Alaskan ecosystems.
UAF associate professor Ginny Eckert showed data indicating a portentious decline in red sea urchin, sea cucumber and Dungeness crab populations since sea otters have returned to Southeast Alaska.
“It doesn’t take a lot of pressure over a long period of time to wipe something out,” Eckert said.
The red sea urchin fishery, Eckert said, is no longer commercially viable.
“Sea otters really like sea urchins, so when they first show up to an area, almost half their diet is sea urchins,” Eckert said. “They really like them.”
The relationship between sea otters, sea urchins and a third species, sea kelp, was central to keynote speaker James Estes’ presentation.
“Otters are pretty darn important predators on the things that they eat,” Estes, a professor at the University of California at Santa Cruz, said. “They have a strong depleting effect.”
He added, “When otters are present in the ecosystem, they have a depleting effect on the urchins. That has an enhancing effect on the kelp.”
Estes said that relationship is important because kelp, like most plants, store carbon dioxide while releasing oxygen.
“Otters make a lot of difference to the carbon dynamics and carbon cycle,” Estes said.
Without sea otters, he said, sea kelp populations fall as sea urchins, which feed extensively on kelp, prosper in the absence of one of their main predators.
“Sea otter management should weigh the costs and benefits of all these effects,” Estes said.
Sea otters are voracious animals, according to Bodkin’s data. They must eat 15 to 25 pounds of food every day — more than a quarter of their body weight.
USGS zoologist George Esslinger studied the effects of sea otters’ rising population on shellfish in Glacier Bay, where the mammals have exhibited a 42 percent annual rate of increase. He said researchers believe many of those otters are entering the bay from Icy Strait.
“You tend to see declines in the sites with higher sea otter densities,” Esslinger said.
While subtidal clams have not been hit as hard as intertidal clams, horse mussel populations in the bay have been sharply reduced, according to Esslinger’s data.
USGS research wildlife biologist Tim Tinker offered some good news about sea otters’ place in Southeast Alaska ecosystems: In some areas, they may be reaching “carrying capacity,” the point at which their population theoretically stabilizes.
“If there’s more and more otters sharing the same amount of resources, the amount of resources available to any one otter in that population is going to get less and less,” Tinker said, explaining the notion of carrying capacity.
Marine ecologist Michelle Ridgway moderated the event, which also included a panel discussion on the future of sea otter research.
The symposium came a day after state Sen. Bert Stedman, R-Sitka, offered his own proposal for sea otter management: put a price on the animals’ furry heads.
Stedman’s Senate Bill 60 would amend Alaska state law to place a $100 bounty on sea otters legally killed in compliance with the Marine Mammal Protection Act of 1972, which generally prohibits the “take” of marine mammals but includes an exemption for Alaska Natives’ subsistence hunting, under a 1994 amendment.
“Now they’re a population size that is devastating the fisheries and migrating north, off of west Prince of Wales (Island), up on Kuiu Island, there around Baranof (Island),” Stedman said. “And they’re devastating the shellfish beds and impacting the Dungeness fishermen, geoducks, all that. So we need to have some population control somehow. I’m not looking for eradication of them or anything, but we’ve got to control the population and the spread.”
Stedman said it was a coincidence that the bill introduction and symposium were so close together.
“The timing couldn’t have been better,” Stedman said. “I think it hopefully is noticed by some of the other groups that are interested in expanding the habitat of the sea otters, that it’s impacting the people that live here.”
According to Gill, close to 3,000 sea otters have been harvested for subsistence purposes since 2008. Some 842 were taken last year, an increase of more than 200 over the previous two years.
Subsistence hunting is not allowed in Glacier Bay, Gill said.
• Contact reporter Mark D. Miller at 586-1821 or at firstname.lastname@example.org.