Migration water temperature and heat stress assessments in western Alaska Chinook salmon overlapping the 2019 heatwave

Canadian Journal of Fisheries and Aquatic Sciences
By: , and 

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Abstract

Chinook salmon population declines span their geographic range with climate hypothesized as a major driver. Concerns of warming freshwater temperatures in their northern range gained urgency during 2019 when a heatwave coincided with premature mortality. This study examined heat stress during the 2019 heatwave compared to subsequent years and described water temperatures in western Alaska to understand the degree to which freshwater temperatures may be a stressor. Heat stress was prevalent among Chinook salmon captured in the 2019 heatwave (Kuskokwim tributaries: 90% in Kwethluk and 63% Takotna river), and variable in subsequent years (∼8% to 60% across Kuskokwim tributaries and Norton Sound rivers). A review of water temperature data indicated that potentially stressful temperatures (≥18 °C) were most common and prolonged in the Yukon River, moderately common and prolonged in the Kuskokwim River, and relatively rare in the Norton Sound region. Water temperatures in 2019 broke several records for overall maximum and frequency of temperatures ≥ 18 °C. Migration water temperatures and heat stress in northern Pacific salmon habitats vary more widely than previously recognized (up to 25 °C).

Suggested Citation

von Biela, V.R., Regish, A.M., McCormick, S.D., Spaeder, J., Whitworth, K., Leon, J., Gillikin, D., Liller, Z., Ivanoff, R., Bell, J., Larson, S.D., Carey, M.P., Zimmerman, C.E., 2026, Migration water temperature and heat stress assessments in western Alaska Chinook salmon overlapping the 2019 heatwave: Canadian Journal of Fisheries and Aquatic Sciences, https://doi.org/10.1139/cjfas-2025-0109.

Publication type Article
Publication Subtype Journal Article
Title Migration water temperature and heat stress assessments in western Alaska Chinook salmon overlapping the 2019 heatwave
Series title Canadian Journal of Fisheries and Aquatic Sciences
DOI 10.1139/cjfas-2025-0109
Edition Online First
Publication Date February 04, 2026
Year Published 2026
Language English
Publisher Canadian Science Publishing
Contributing office(s) Eastern Ecological Science Center, Alaska Science Center Ecosystems
Country United States
State Alaska
Other Geospatial western Alaska
Additional publication details