Gray wolves along Alaska’s coast are turning to the sea for prey

On Alaska’s Prince of Wales Island, gray wolves have added an unexpected prey item to the menu: sea otters.

The shift could ripple through both land and sea, with consequences for food webs and wolf health. A new project is digging into how these predators pull off marine hunts and what that reveals about their behavior.

The work is led by Patrick Bailey, a Ph.D. candidate at the University of Rhode Island (URI).

The team combined wolf teeth, trail cameras, and long-term observations to decode how coastal wolves use marine resources and how their tactics differ from other wolf populations.

Wolves reshape coastal ecosystems

On land, wolves are famed for reshaping ecosystems by moving prey and plants into new patterns. Along the coast, their influence may extend into tide lines and kelp beds.

“We don’t have a clear understanding of the connections between water and land food webs, but we suspect that they are much more prevalent than previously understood,” said Bailey, a member of Sarah Kienle’s CEAL Lab in the Department of Natural Resources Science.

“Since wolves can alter land ecosystems so dramatically, it is possible that we will see similar patterns in aquatic habitats.”

The return of sea otters adds a historical twist. Once abundant along the Pacific Coast, otters were nearly wiped out by the fur trade. Their recovery has revived old interactions – and possibly this wolf-otter predator-prey dynamic.

Researchers now want to know whether renewed access to otters is changing wolf behavior and what this could mean for otter populations.

Wolf teeth reveal their prey

To map diet through time, Bailey turned to stable isotope analysis of gray wolf teeth from museum collections and recently deceased animals. Like growth rings in a tree, teeth record seasonal chapters of a life.

“If large enough, we can individually sample each of these growth rings to track an individual’s feeding patterns over time,” he said. “When we gather enough samples across individuals, we can then analyze how prevalent these dietary trends are throughout a population.”

Those chemical fingerprints can show whether marine-derived food is a minor supplement or a sustained habit. They also help researchers understand whether individual wolves switch diets with the seasons or as opportunities arise.

Coastal wolves and aquatic prey

Shellfish, fish carcasses, and beached marine mammals are one thing; catching a living sea otter in the water is another.

“Capturing and eating prey in the marine environment is very different from doing it on land,” Kienle said. “We are super curious to see if these coastal wolves have behavioral adaptations that are different from terrestrial wolves.”

Despite more than two decades of official reports that wolves consume aquatic prey, the mechanics of a sea otter hunt remain unclear.

“What hasn’t been explored, and what I am really interested in documenting, is how exactly wolves are able to capture sea otters,” Bailey said.

Capturing new details on camera

Early video from the island offered hints but lacked the clarity to analyze pursuit and capture.

New trail-camera arrays that Bailey installed this summer aim to change that – watching haul-outs, crossing points, and shorelines where wolves and otters intersect.

“So far, we know that these wolves are consuming sea otters and we’re now staged to capture the details that have previously eluded us,” Bailey said.

A team of seven URI students is already combing through more than 250,000 images logged since December to flag behaviors, times, tides, and interactions.

Tracking elusive coastal wolves

Coastal wolves are clever, wary, and mobile, and the terrain is dense, wet, and remote. “When you pair these traits with a landscape that is very rural and difficult to traverse, researching them becomes quite the undertaking,” Bailey explained.

Progress depends on local knowledge and long partnerships. Prince of Wales Island became the project’s hub thanks to a collaboration with Alaska Department of Fish and Game biologist Gretchen Roffler and local research technician Michael Kampnich.

“I cannot emphasize enough how much these two have helped me,” Bailey said. “This project would not be possible without their input and guidance.”

“Kampnich has been an unbelievable resource for getting us acquainted with the island and its unique ecology. Working with locals is so important because they have decades of experience and perspective that we as outside researchers simply do not have.”

Toxic toll of a new diet

Diet isn’t just about calories. Roffler’s recent findings point to high levels of methylmercury – a toxic form of mercury – in sea otters from the region.

If wolves are feeding on otters, that contamination could move up the food chain. Liver samples from aquatic-foraging wolves show mercury burdens far above inland wolves – sometimes up to 278 times higher – raising red flags about reproduction, behavior, and long-term health.

“Methylmercury accumulation can cause a suite of problems related to reproduction, body condition, and behavioral abnormalities,” Bailey noted.

Tracking mercury alongside diet history could reveal whether particular coastlines, seasons, or prey types elevate risk, and whether certain packs are more exposed than others.

Land and sea entwined

If wolves are routinely eating otters, the effects could be profound. Otters shape nearshore communities by controlling sea urchins. Fewer otters can mean more urchins and less kelp.

Wolves, meanwhile, can redirect energy from the sea onto land – scattering nutrients through scat, urine, and carcass remains, with knock-on effects for plants, insects, and scavengers.

Documenting the “how” of sea otter predation is the keystone for understanding the “so what” across the shoreline.

Coastal wolves hunting their prey

The next phase blends the isotope “diaries” from teeth with time-stamped camera evidence to connect diet shifts to specific behaviors and places.

If the cameras capture hunts, they could reveal whether wolves ambush otters on land, intercept them at haul-outs, or exploit tides and terrain.

With each image and tooth section, the picture sharpens: a coastal predator adapting to a richer shoreline, carrying benefits and risks between two worlds.

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