Alaska's salmon collapse and the trawler fight

NOAA is the federal ocean and fisheries agency. One of its researchers, Lukas DeFilippo, led a study in Ecological Applications that reconstructed Yukon chinook mortality across the life cycle. It found that natural deaths at sea began climbing substantially in 2016, connected to acute and prolonged Bering Sea marine heatwaves. It tested harvest and bycatch as well, and for neither did it find evidence of a significant effect on the population. The mechanism runs through food. A marine heatwave is an extended stretch of abnormally warm ocean water, and it squeezes salmon twice. Warm water raises a young salmon's metabolic rate so it needs more food, while crashing the food itself. Prey fish such as capelin declined steeply. NOAA's earlier chum research found juveniles in warm years eating jellyfish with roughly half the calories of their normal prey. It found they then died in their first winter at sea with too little fat to survive. Even with fewer severe heatwaves since 2020, mortality had not returned to pre-heatwave levels by 2023. By September 2026 each side of the bycatch argument was citing its own figure for the chinook in the nets. Both figures draw on the same counted bycatch.