by Doug Molyneaux
“The summers of 2020 and 2021 saw the lowest numbers on record for chum salmon returning to the Kuskokwim and Yukon rivers. There are many possible reasons for these low returns. I used the scientific method to investigate one of those possible reasons.” Those were the opening lines of Sleetmute 8th grader Kiley Hayden when explaining her science project at the recent Alaska Science and Engineering Fair held in Anchorage.
The question Kiley was asking is whether the exceptionally warm summer of 2019 that resulted in pre-spawning death of salmon in the Yukon and Kuskokwim rivers had anything to do with the low chum salmon returns in 2020 and 2021. Kiley rejected her hypothesis because her research showed that juvenile chums that would ultimately return in 2020 and 2021 where not in the warm rivers during 2019. Instead, those immature chum salmon were swimming in the Bering Sea and Gulf of Alaska when the rivers were overheating.
But in her poster, Kiley pointed out that being at sea did not make the immature salmon safe from the heatwave. Both the Bering Sea and Gulf of Alaska experienced the 2019 heatwave too. The result was record warm sea surface temperatures and extensive die offs of sea birds and other marine animals. These creatures starved to death because the warm water disrupted the entire ecosystem.
The immature chum salmon were caught up in this same disruption and many likely starved to death, which resulted in the low return of spawning adult chum in 2020 and 2021. This was the conclusion Kiley discussed in her accompanying report.
Her research earned Kiley first place in her category at the science fair, plus she received many other acknowledgements, prizes, and accolades for her efforts.
Asked about the upcoming salmon season, Kiley was not hopeful. She speculated that 2022 would likely see continued low chum salmon abundance because the immature fish that will make up the 2022 return were also impacted by the warm ocean waters in 2019.
