From the Koyukuk River, to the Kuskokwim, to Norton Sound, to Bristol Bay’s Igushik River, unusually warm temperatures across Alaska this summer led to die-offs of unspawned chum, sockeye and pink salmon. Warm waters also sometimes this summer acted as a “thermal block” — essentially a wall of heat salmon don’t swim past, delaying upriver migration.

Dead chum salmon have been spotted floating down the Yukon river. Water temperatures are measuring at 70 degrees, the warmest in recollection.

In early July, dead fish were observed floating along Kouwegoki Slough and along Powers Creek, among other locations.

"Our temperatures reached 83 degrees, and seem to be getting hotter! We think that maybe the warm water has something to do with the humpy die-off?"