Heat stress in migrating Yukon River Chinook salmon

Salmonid Research, Monitoring, and Evaluation (RM&E)

Project ID1811
Recovery Domains -
Start Date05/01/2021
End Date03/31/2022
Last Edited07/30/2021
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We will examine evidence of heat stress in Yukon River Chinook salmon (Oncorhynchus tshawytscha) using heat shock proteins and gene expression. Yukon River Chinook salmon have been in decline since the 1990s for unknown causes and the pace of decline has recently accelerated. Heat stress during spawning migration has the potential to cause significant prespawn mortality of adult fish. Two biomarkers will be used to assess the presence of heat stress in Yukon River Chinook salmon, the concentration of a specific heat shock protein (HSP70) associated with stress and the expression (i.e., transcription) of genes involved with thermal stress and physiological pathways affected by thermal stress. Fish will be collected during the spawning migration at established monitoring sites throughout the Yukon River watershed including test fisheries at Emmonak and Eagle, weirs on tributaries (East Fork Andreafsky River and Gisasa River), and a subsistence fish wheel near Tanana. A short (<48 h) manipulative temperature experiment will distinguish baseline protein and gene expression levels in fish held at a cooler control temperature from fish held at temperatures associated with low (18 °C) and high (21 °C) heat stress. The potential influence of migration timing, age, and size on the presence of stress indicators will also be evaluated. The results of this study will be used to assess the likelihood of increases in freshwater adult mortality and reduced reproductive success from heat stress. If heat stress indicators are present, managers may adjust escapement goals to compensate for the likelihood of higher prespawn mortality rates.

Project Benefit    

This research may contribute to preventing a Chinook salmon failure in the future. If evidence of heat stress is present in Yukon River Chinook salmon and heat stress can be linked to increased prespawn mortality during future studies, management plans can be adjusted to account for the additional increase in adult mortality. If freshwater mortality is underestimated in warm years, there is potential for overharvest and ultimately fishery failure. By sampling throughout the Yukon River watershed, we will identify areas of the watershed where heat stress is more common. Sampling at the Eagle test fishery on the Canadian boarded will provide an indication of whether fish escaped to Canada are heat stressed or not.


Metric Completed Originally

Funding Details

Report Total:$105,020

Project Map



  • Worksite Identifier: 49468465
  • Start Date: 05/01/2021
  • End Date: 03/31/2022
Area Description
Yukon River Watershed

Location Information

  • Basin: Lower Yukon
  • Subbasin:
  • Watershed:
  • Subwatershed:
  • State: Alaska
  • Recovery Domain:
  • Latitude: 62.6747528918
  • Longitude: -164.6534312794


    No ESU data was found for this worksite.




  • E.0 Salmonid Research, Monitoring, and Evaluation (RM&E)Y (Y/N)
    •      . . E.0.a RM&E Funding .00
    •      . . E.0.b
      Complement habitat restoration project
    •      . . E.0.c
      Project identified in a plan or watershed assessment.
    •      . . E.0.d.1 Number of Cooperating Organizations
    •      . . E.0.d.2
      Name Of Cooperating Organizations.
    •      . . E.2 ResearchY (Y/N)
      •      . . . . E.2.a Research Funding
      •      . . . . E.2.b.8 Climate change studiesY (Y/N)
        •      . . . . . . E.2.b.8.a
          Key issues addressed by climate change study