Warming waters are fundamentally altering the timing of salmon runs in Southeast Alaska, according to a new report from the National Oceanic and Atmospheric Administration (NOAA). Data collected at the Auke Creek Research Station suggests that local salmon populations are shifting their migration patterns, a trend that researchers have tracked for 46 years.
The Auke Creek facility, operated by NOAA Fisheries Auke Bay Laboratories, utilizes a weir—a shallow barrier spanning the creek—to monitor and track fish movement. Findings from the August NOAA annual report indicate that all Pacific salmon species are arriving at the weir earlier in the season than in previous decades. This shift aligns with research published in 2013, which first identified climate change as a primary driver behind these changing migration schedules.
Rising Creek Temperatures Influence Migration
The environmental data reveals a marked increase in the average temperature of Auke Creek. Records show that the average temperature from 1980 to 2024 was 7.5 degrees Celsius; however, that figure rose to 8.3 C in 2025. David Tallmon, a professor of biology at the University of Alaska Southeast who has worked at the weir for 16 years, notes that salmon rely on specific environmental cues, such as water temperature, to trigger their movement toward spawning grounds or out to sea.
“We all have the same interests and concerns for the future of fish, given how fast we’re seeing the environment change,” Tallmon said. His research focus remains on the long-term health of fish populations and the broader ecosystem that relies on these salmon runs.
Shifted Migration Timing Complicates Regional Fisheries Management
While the Auke Creek data focuses on local runs, the implications of shifting migration timing extend to major commercial fisheries in the region. Curry Cunningham, a fisheries scientist for the University of Alaska Fairbanks at the Lena Point Fisheries Facility, observes that run-timing changes can complicate conservation efforts and economic planning.
Cunningham, who studies the Bristol Bay commercial salmon fishery, notes that early migrations can lead to miscalculations regarding the total size of a run. “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,” Cunningham explained. In Bristol Bay, sockeye salmon are also exhibiting earlier migration patterns, mirroring the trends observed in the Juneau area.
Despite these adjustments in timing, the NOAA report highlights one point of stability: the total abundance of salmon at Auke Creek. The number of fish counted at the weir has remained relatively consistent, suggesting that while the “when” of the salmon run is changing, the overall population numbers have not yet seen a significant decline due to the warming water temperatures.
Scientists continue to monitor these environmental shifts to determine how future temperature fluctuations might impact the long-term sustainability of Alaska’s salmon runs. The current data serves as a baseline for ongoing research into how aquatic species adapt to a rapidly changing climate.
