Arctic Climate Report Shares Data on Salmon Troubles in Western Alaska

Chinook salmon, Coho salmon and steelhead returning to the Elwha River. Photo by John McMillan via NOAA.
Chinook salmon, Coho salmon and steelhead returning to the Elwha River. Photo by John McMillan via NOAA.

Wild salmon populations in Western Alaska are engaged in constant battle with land and ocean heat waves, as well as other factors, resulting in fewer fish returning to the Yukon River, according to the annual Arctic Report Card, a collaborative effort of NOAA Fisheries and other stakeholders that was released Dec. 15.

The NOAA Fisheries 2023 Ecosystem Status Reports for Alaska, released by the National Oceanic and Atmospheric Administration (NOAA), contains special sections on salmon, which note, for example, that in 2022, 81% fewer king salmon returned than average to the Yukon River, a new record low and part of a long-term decline seen across Alaska.

The report notes that the cause of this decline is complex and that researchers have found possible links to water temperature, disease and declining body size of the fish.

“There is still a lot we don’t know,” Rick Thoman, the lead editor and a climate specialist at the University of Alaska Fairbanks’ Alaska Center for Climate Assessment and Policy, said.

“But it seems clear from the essay that climate induced changes look like bigger factors than the bycatch,” he continued. “Warmer on land conditions and in the ocean are changing the food supply and predators (for fish). It appears that these environmental issues are playing a larger role.”

Thoman said he’s optimistic that Alaskans will adapt to the changes because they have no choice.

“It seems perfectly clear at this point that we are going to do things differently than in the past, but it is going to be a different Alaska than what we are used to,” he said.

“We’ve seen heat waves in the ocean and heat waves on land, and salmon populations have been responding with extreme ups and downs,” said Erik Schoen, a fisheries scientist at the UAF International Arctic Research Center who’s the lead author of the salmon chapter. Peter Westley, a scientist at the UAF College of Fisheries and Ocean Sciences, was also among the salmon chapter co-authors.

“We know that king populations on the Yukon do worse when the adult salmon swimming upriver to spawn experience high river temperatures and low flow, which tend to be correlated with hot, dry years,” Schoen explained. “There’s also a disease called Ichthyophonus that can interfere with a salmon’s ability to swim.”

In 2022, observers in the research network found that more frequent and intense coastal storms contributed to flooding in communities and coastline erosion. Shifting wind patterns altered the sea ice, improving access to marine mammal hunting areas.

Chum salmon were also facing challenges. In 2021, 92% fewer adults returned to the Yukon River than average, and until then chum populations had been stable.

The report notes that the decline has been linked to unprecedented heat waves and loss of sea ice in the Bering Sea. Juvenile chum salmon ate lower quality food and put on less fat under those conditions potentially reducing their survival rates, the report said.