Warming waters are causing salmon born in Juneau’s Auke Creek to shift when they return home — a trend that’s been going on for 46 years. That’s according to an annual report published by the National Oceanic and Atmospheric Administration in August.
The report details findings from the Auke Creek Research Station. It houses the Auke Creek weir and is operated by NOAA Fisheries Auke Bay Laboratories. Weirs are shallow barriers built across rivers and used by scientists to catch and track fish.
All Pacific salmon species are running earlier up the Auke Creek weir, the report says. The findings are in line with research published in 2013 that found climate change is influencing the shift in migration timing.
David Tallmon is a professor of biology at the University of Alaska Southeast. He’s worked at the weir for 16 years and says he’s worried about what climate change could mean for salmon.
“We all have the same interests and concerns for the future of fish, given how fast we’re seeing the environment change,” he said.
His concerns include maintaining healthy fish populations, for both people and other animals that depend on them.
According to the NOAA report, the average temperature of Auke Creek has risen significantly since 1980. The average temperature from 1980 to 2024 was 7.5 degrees Celsius. In 2025, it rose to 8.3 C.
Tallmon says salmon use environmental cues, including water temperature, to decide when to return to the streams where they were born and when to head out to sea.
Curry Cunningham is a fisheries scientist for the University of Alaska Fairbanks at the Lena Point Fisheries Facility. He says fish run timing changes can have large impacts on conservation and economics for salmon fisheries.
He’s not involved with the Auke Creek weir, but studies the commercial salmon fishery in Bristol Bay, which is also experiencing run time shifts due to environmental changes. There, adult sockeye are migrating upriver earlier than usual as well.
“If you’ve had high escapements up through a given point in season, that can point to a large run size. When in reality, the run is just early,” he said.
Despite the change in run timings, warming waters haven’t impacted abundance at Auke Creek. The NOAA report says the number of salmon counted at the weir has stayed roughly the same.
