Since the water is warm, Alaska experiences salmon booms and busts

This story originally appeared in News from the Highlands and is part of climate desk Cooperation.

Every June, Serena Fitka drives home to her Yup’ik community in St. Mary’s, Alaska, near the confluence of the Yukon and Andreafsky Rivers in the state’s southwest. She usually helps her family fish for salmon and preserves it in the smokehouse for the lean winter months. But that didn’t happen this year: there were no salmon to catch this year.

“I could feel the loss,” she said. “I didn’t know what to fill my days with, and I could tell that was the case for everyone along the Yukon River.”

There are five types of salmon in Alaska: chinook, sockeye, chum, coho, and pink. Chum is the most commonly caught fish in the Yukon, but both chum and chinook are critical to the life and culture of the approximately 50 Alaskan communities that depend on the river and its tributaries for their livelihoods.

Statewide, Chinook numbers have been in decline for a decade, but this year’s run is the lowest on record. The chum count has plummeted in 2021, and this year’s tally is the second-lowest on record; As a result, state and federal fisheries managers have shut down chum fishing in the Yukon. This will affect more than 2,500 households in the region who depend on mates to support their families. “That annual harvest is gone,” said Holly Carroll, Yukon River subsistence fisheries manager for the US Fish and Wildlife Service. Scientists have yet to figure out why parts of western Alaska are faring so badly with chum and chinook runs, but many suspect warming oceans are affecting salmon early in their life cycle — and some local fishermen believe commercial ones are Fisheries have stalled. Other parts of the state could also contribute.

Warmer waters have led to a decline in Chinook and chum numbers in the Pacific, and these changes are also hurting salmon in the Yukon. In a study of chum, researchers found that the fish ate things outside of their usual diet, like jellyfish, and therefore probably didn’t have enough energy stored in their bodies to survive the winter. “It’s related to these marine heatwaves that we’ve seen in both the Bering Sea and the Gulf of Alaska,” said Katie Howard, a fisheries scientist with the Alaska Department of Fish and Game Salmon Ocean Ecology Program. During marine heatwaves, chums eat prey that is easier to catch but often lower in calories. Drought in the Interior Alaska and Canada spawning grounds could also contribute to lower numbers of Chinooks as it results in lower water levels and makes the water warmer.

Meanwhile, a warming climate nearly 400 miles south in Bristol Bay could actually help salmon migrations, said Jordan Head, a state biologist working in the area. Bristol Bay fishermen caught over 57 million redfish this year, beating the 1995 record of 44 million fish. The region has returned over 74 million redfish so far this season, the largest number in the history of the fishery. With warmer temperatures, lakes have frozen for less time, and the juvenile sockeye could grow larger and be more competitive when entering the ocean, increasing its chances of survival. But as the Bering Sea continues to warm, it could experience the same salmon declines seen in the Yukon.

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