By admin 
The intense marine heatwave conditions that began roiling the Bering Sea in about 2016 resulted in the lowest winter sea ice extent measured in 150 years, widespread bird and marine mammal die-offs, a drastic shift in fish populations and a crash of snow crab stocks.
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Now new research is tying the marine heatwave to the recent collapse of Yukon River Chinook salmon.
A study published in April, written by scientists at the National Oceanic and Atmospheric Administration’s Alaska Fisheries Science Center and University of Alaska Fairbanks, showed the correlation between the extreme heatwave conditions and the nosedive in Yukon River Chinook stocks. The heatwave was accompanied by a dramatic increase in deaths of older juvenile and adult Chinook that, had they survived, would have returned from the ocean to freshwater spawning grounds, the study found.
The study was published in the journal Ecological Applications.
The Yukon River’s runs of Chinook, also called king salmon, have been in a long-term decline since their past heyday, when they numbered in the hundreds of thousands and the river was one of the biggest sources of that salmon species.
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The sharp downturn in recent years resulted in a 2022 return that was the lowest on . Widespread fishery closures have been in effect for years along the Yukon River system in both Alaska and Canada.
The study evaluated four general reasons for the sharp decline: poor juvenile “recruitment” into the ocean, which refers to the successful migration of surviving juvenile fish from freshwater; deaths of fish in the marine environment at the start of their migration back to freshwater; harvests that target the salmon; and bycatch, the unintentional harvest of salmon by commercial fishing vessels targeting other species, such as pollock.
Poor juvenile recruitment emerged as an important factor, which was to be expected, the study said.
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