Alaska hunters, researchers say whales and fish are changing their migration patterns in the warming climate

Two humpback whales feed in Beaufort Sea, northeast of Point Barrow. (Kate Stafford)

Catching salmon in the North Slope village of Kaktovik was unheard of not too long ago. But resident Robert Thompson says some fishermen now see salmon more regularly. About five years ago, he caught a dozen salmon – a small but noticeable number.

“Before it was unusual, and people would talk about it, that somebody got a salmon,” Thompson said. “Now it’s fairly common.”

Fishermen, hunters and researchers gathered at the Alaska Marine Science Symposium in Anchorage in January to discuss how several fish species and marine animals are changing their migration patterns in the warming climate. That includes humpbacks gaining new ground up north, bowheads expanding their diet and salmon observed in the Arctic.

Salmon are spawning in the Arctic

Elizabeth Mik’aq Lindley is a graduate student from Bethel who grew up fishing for salmon. Now she studies Pacific salmon in the Arctic.

In 2023, she and other researchers installed temperature loggers at the depth of salmon nests in several rivers – including the Anaktuvuk River, which runs through Gates of the Arctic National Park and Preserve.

“If it gets too cold, the stream can freeze straight through to the bottom, into these nests, and embryos will freeze and die,” Lindley said.

Temperature also influences incubation and when embryos will hatch and start making their way to the ocean.

But in a year of tracking the water temperature, the researchers never saw it get below freezing. They also estimated that salmon emerged around August. That’s later than in other parts of the state, but it’s the optimal time for the Arctic. While more data is needed to see if salmon populations are growing in Arctic rivers, the conditions seem survivable.

“Salmon are spawning in the Arctic,” Lindley said, “and it does seem like it’s thermally survivable, thermally possible and plausible that they can incubate and emerge at the right time, given these temperatures.”

Bowheads are expanding their foraging grounds

The warming environment has also been affecting bowhead whales.

Traditionally, bowheads travel south to spend their winters feeding on krill in the Bering Sea. But with ice conditions reshaping the zooplankton community, the animals have been delaying that migration — or even staying in the Chukchi and Beaufort Seas all winter.

Marine ecologist Clarissa Ribeiro Teixeira looked at the whales’ baleen plates to better understand the change. Elements that make up baleen plates – stable isotopes of nitrogen and carbon – can offer a window into an animal’s diet and movements. Each plate grows continuously and has information from about 20 years of the whale’s life, she said.

Teixeira and her colleagues sampled baleen sections from 11 whales harvested on the North Slope over two decades. They also looked at the ice conditions during those years. What they discovered was that after 2016, when there was very little ice, bowheads shifted their behavior.

“The reduction in the sea ice cover may have influenced the prey availability distribution for these animals, motivating bowhead whales to explore new foraging habitats or include a wider composition of their prey sources into their diet,” she said. “That’s amazing, because it shows how resilient these individuals are, right?”

Humpbacks are frequenting the Arctic

Less ice might also mean new territory for humpback whales.

Kate Stafford, who is an oceanographer and a professor at the Marine Mammal Institute at Oregon State University, studies bowheads in the Arctic. But in 2021, she and her late colleague Craig George saw a whale that, to their surprise, turned out to be a humpback – a species that was once rare in the Utqiaġvik area.

“You just never know what you’re going to find,” she said. “We all need to take our eyes off of our phones and watch the water.”

Stafford says data from local whalers and aerial surveys points to more humpbacks visiting the area.

In Utqiagvik, humpbacks were sighted only twice before 2021 and two or three times in years after that. Then, last fall, researchers saw more than 25 whales feeding close together for two days in a row.

“We came across what I would call Humpback Palooza,” Stafford said. “Just dozens of humpback whales, which was crazy.”

Researchers took photos of whales and uploaded them to Happywhale, a citizen science project that helps identify whales using a technology similar to face recognition. Several of the whales seen near Utqiaġvik matched whales seen in Hawaii breeding grounds.

Young humpbacks usually follow the migration patterns they learn from their mothers, Stafford said. Because researchers observed multiple mother-calf pairs, the whales might return to the area.

“This does suggest, at least to me, that humpbacks are here to stay near Utqiaġvik, at least so long as there’s something to eat,” she said.

Utqiaġvik whaler Michael Donovan said he did not witness Humpback Palooza, but he has seen a few humpbacks during his fall hunts. He said that he and other whalers are worried the humpback whales might be competing with bowheads — a staple subsistence resource for his community — for krill and copepods.

“They’re an invasive species, you know. They come in and eat the same food that our bowheads eat,” Donovan said.

Donovan and other hunters say they support scientists studying species that are growing their presence in the Arctic’s warming waters. Meanwhile, Stafford said scientists rely on people like Donovan for their research.

“The hunters and whalers, they’re really good naturalists, they’re really good observers and biologists,” she said. “They need to understand the seasonality of animals, the behavior of animals, how the environment impacts animals.”

Stafford says that local hunters contribute so much to her research, she’s grateful when her work can help them, too.