Federally-funded Oregon research finds some wolves may primarily eat sea otters



(The Center Square) Observations of wolves hunting and killing a harbor seal and a group of wolves hunting and eating a sea otter on Alaska’s Katmai coast have scientists reconsidering assumptions about wolf hunting behavior.

Researchers had previously seen wolves eating sea otter carcasses. However, the frequency of that happening and whether they were scavenging or hunting was unknown. Scientists at Oregon State University, the National Park Service, and the Alaska Department of Fish and Game are changing that with a paper recently published in Ecology, according to Oregon State University.

The paper described several they saw involving wolves and marine mammals in Katmai National Park that had not been observed previously.

The researchers saw a male wolf hunt and kill a harbor seal in 2016. Near the mouth of a creek, the wolf charged into the water and grabbed the seal’s tail.

“The wolf continued to tear into the flesh of the seal’s tail and after an approximate 30-minute struggle, the seal appeared to tire, straining to lift its head above water,” the release said. “The wolf dragged the seal onto the exposed sandbar and began to tear into the existing wound and consume the tail.”

On three separate occasions in 2016, 2018, and 2019, the scientists noticed wolves carrying sea otter carcasses.

Researchers also observed three wolves hunting and eating an adult sea otter on an island at low tide in 2021.

They saw the wolves travel to the island, could not locate the wolves for about a minute, and later saw them reappear carrying a limp sea otter. The wolves ate the animal for about 60 minutes. Once the wolves left, the researchers looked at the kill site and found an area of concentrated blood where the wolves most likely killed the sea otter. The blood indicates the wolves likely killed the sea otters rather than scavenging one that was already dead.

“This is really exciting documentation of behaviors we believe have never been directly observed by scientists,” Ellen Dymit, a doctoral student at Oregon State, said. “It kind of forces us to reconsider the assumptions that underlie a lot of our management decisions and modeling around wolf populations and populations of their prey, which often assume that wolves depend on ungulates, like moose and elk.”

The research project started in 2016 when Kelsey Griffin, a National Park Service biologist, and her colleagues had lunch on the beach during a day of doing marine debris and bird mortality surveys at Katmai National Park.

“Seemingly out of nowhere, we are sitting there, we just see this white wolf carrying an otter just trotting by,” Griffin said in the release. “What? I was just blown away. I have never seen anything like that before.

“Then I was asking my co-workers: ‘Has anyone seen this before? Do wolves often eat sea otters?’ Griffin added. “I was just asking a bunch of questions about the wolves, and it just seemed like there was not a whole lot of information about them. That was the initial observation. I just got lucky. Wolves on the Katmai coast have never been studied, and our research highlights the unique role wolves play in nearshore ecosystems in Alaska”

Griffin reached out to Gretchen Roffler, a biologist with the Alaska Department of Fish and Game. Roffler introduced Griffin to Taal Levi, a professor at Oregon State and Dymit’s advisor.

The project expands upon work by Roffler, Levi, and others on wolves and sea otters on Pleasant Island. It is an island landscape adjacent to Glacier Bay about 40 miles west of Juneau and several hundred miles east of Katmai across the Gulf of Alaska.

A paper they published earlier this year found that wolves on Pleasant Island caused a deer population to plummet; the wolves mostly switched to eating sea otters in just a few years. The researchers believe this is the first instance of sea otters becoming the primary food source for a land-based predator.

The National Park Service funded the research through a grant but did not know how much it cost, a spokesperson for NPS told The Center Square.

Future papers will analyze wolves and sea otters from Lake Clark National Park, Glacier Bay National Park, and Kenai Fjords National Park, in addition to Katmai. The research team will examine how sea otter density impacts wolves’ diets on a pack level versus an individual level.

Dymit, Griffin, and Roffler authored the paper. Dymit and Levi work for the Department of Fisheries, Wildlife, and Conservation Sciences in Oregon State’s College of Agricultural Sciences. Additionally, Griffin is the director of the Ocean Alaska Science and Learning Center in Seward, Alaska.



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