2019 Alaska Seabird Die-off
Photo credit adn.com
Unusually warm temperatures across Alaska this summer led to die-offs of massive amounts of unspawned chum, sockeye, and pink salmon.
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. Stephanie Quinn Davidson, the Director of the Yukon Inter-Tribal Fish Commission, took a team of scientists along 200 miles of the Koyukuk River to investigate a die-off of chum salmon at the end of July. The team counted 850 dead, unspawned chum - and that, she said, was a minimum count. "We were boating, going about 35 or 40 miles per hour, and we know we missed a lot," she said. "On a boat going by relatively fast, we were probably getting at most half the fish and at the least about ten per cent of the fish." Locals to the area said this same thing happened four or five years, ago, she said, but not to the scale it did this year. She attributes the deaths to heat stress. "We cut open the fish, looked for any size of disease, infections, parasites... By all indications, these fish looked healthy," she said. "They didn't have any marks on them, or any sign of disease or stress otherwise. And the die-off event coincides with the week of heat we had."
The total run was more than 1.4 million chum, she said, with some arriving before the warm weather event. "We definitely had chum salmon spawn," she said. "And have chum salmon continue to make it to spawning grounds. There are salmon that made it through. Hopefully, they'll pass those genes on that allowed them to persist." In the Kuskokwim, according to KYUK, there was a die-off of salmon having "heart attacks" due to the warmer than usual water along the ocean. In Norton Sound, large numbers of pink salmon were observed dead before spawning, according to KNOM. Full story