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Alaska's freshwater spans a wide range of summer water temperatures, from ice-cold glacier water to warm rivers that routinely reach stressful levels for salmon, exceeding 18°C/64°F and even surpassing 21°C/70°F. Pacific salmon population trends are also varied and include declines in many Chinook salmon populations. Salmon declines are kitchen table issues because salmon fishing is key to the wellbeing of many Alaskans. Our heat stress research began with a focus on Yukon River Chinook salmon because the river was warm, the salmon population declined, and stakeholders were concerned. Heat stress research has since expanded to other rivers and Pacific salmon species in Alaska. Our research is collaborative and responsive to the science information needs of federal, state, tribal, and local partners. The U.S. Department of the Interior has management and science responsibilities for Pacific salmon established by the Alaska National Interest Lands Conservation Act (ANILCA).
Return to Ecosystems >> Fish and Aquatic Ecology
Pacific salmon heat stress research at USGS is a sustained, multiphase, and collaborative effort with partners that began in 2015 and continues today.
This effort includes the following research activities and key findings:
Bar plot showing the percentage of Chinook salmon with evidence of heat stress in each group based on the heat shock protein 70 (HSP70) protein concentration data. Map indicates sample collection locations. Sample groups are arranged by region from north to south: Norton Sound (purple), Yukon (orange), and Kuskokwim (green). Figure from the article "Migration water temperature and heat stress assessments in western Alaska Chinook salmon overlapping the 2019 heatwave".
Map showing the premature mortality observations of Pacific salmon carcasses in Alaska during summer and fall of 2019. Symbol color and shape denote Pacific Salmon species or alternative taxonomic groupings specified in the legend. Figure from the article "Premature Mortality Observations among Alaska’s Pacific Salmon During Record Heat and Drought in 2019".
Click on each news article below to learn more:
As salmon in Alaska plummet, scientists home in on a killer
‘Too hot’ for salmon: How climate change is contributing to the Yukon salmon collapse
Fat Bear Week celebrates Bristol Bay salmon
Alaska worries for its salmon run as climate change warms Arctic waters
Yukon River, beset by salmon woes and mercury threats, signals broader Arctic climate change
Warmer waters, animal die-offs and toxic blooms are among the signs that a ‘new Arctic’ is here
Warming Yukon River adversely affecting salmon
Summer Chum Salmon Die-Off Likely Caused By Heat Stress, Say Scientists
The water is so hot in Alaska it’s killing large numbers of salmon
Why Are Salmon Being Found Dead In Rivers Across Western Alaska?
Below are other science projects associated with this project.
Below are multimedia items associated with this project.
Two juvenile coho salmon (Oncorhynchus kisutch) used in a heat stress experiment. Alaska Department of Fish and Game’s William Jack Hernandez Sport Fish Hatchery, Anchorage, Alaska, USA.
Two juvenile coho salmon (Oncorhynchus kisutch) used in a heat stress experiment. Alaska Department of Fish and Game’s William Jack Hernandez Sport Fish Hatchery, Anchorage, Alaska, USA.
Experimental tanks used in a juvenile Pacific salmon heat stress experiment for Chinook salmon (Oncorhynchus tshawytscha) and coho salmon (Oncorhynchus kisutch).
Experimental tanks used in a juvenile Pacific salmon heat stress experiment for Chinook salmon (Oncorhynchus tshawytscha) and coho salmon (Oncorhynchus kisutch).
A juvenile Chinook salmon (Oncorhynchus tshawytscha) used in a heat stress experiment. Alaska Department of Fish and Game’s William Jack Hernandez Sport Fish Hatchery, Anchorage, Alaska, USA.
A juvenile Chinook salmon (Oncorhynchus tshawytscha) used in a heat stress experiment. Alaska Department of Fish and Game’s William Jack Hernandez Sport Fish Hatchery, Anchorage, Alaska, USA.
Infographic showing water temperature and discharge (flow) data from rivers with heat-related salmon mortality, drought-related salmon mortality, and normal salmon survival in Alaska during 2019.
Infographic showing water temperature and discharge (flow) data from rivers with heat-related salmon mortality, drought-related salmon mortality, and normal salmon survival in Alaska during 2019.
A spawning Yukon River Chinook salmon (Oncorhynchus tshawytscha) captured near Pilot Station, Alaska, in June 2018 as part of an experimental temperature manipulation study to validate heat stress biomarkers.
A spawning Yukon River Chinook salmon (Oncorhynchus tshawytscha) captured near Pilot Station, Alaska, in June 2018 as part of an experimental temperature manipulation study to validate heat stress biomarkers.
An experimental tank used in a thermal challenge experiment for adult salmonids. The upper lobe of an adult Chinook salmon (Oncorhynchus tshawytscha) caudal fin is visible in the center of the water surface.
An experimental tank used in a thermal challenge experiment for adult salmonids. The upper lobe of an adult Chinook salmon (Oncorhynchus tshawytscha) caudal fin is visible in the center of the water surface.
Scientist preparing to release Chinook salmon into the Yukon River in Alaska, USA.
Scientist preparing to release Chinook salmon into the Yukon River in Alaska, USA.
Chinook salmon released into Yukon River in Alaska, USA.
Chinook salmon released into Yukon River in Alaska, USA.
Chinook salmon restrained in a cradle after non-lethal muscle biopsy sample collection for heat stress assessment at a subsistence fish wheel in the Yukon River during July 2017. The muscle biopsy location looks like one of the black spots on the back of the fish.
Chinook salmon restrained in a cradle after non-lethal muscle biopsy sample collection for heat stress assessment at a subsistence fish wheel in the Yukon River during July 2017. The muscle biopsy location looks like one of the black spots on the back of the fish.
USGS biological science technician Shannon Waters releases a Chinook Salmon into an Alaskan river.
USGS biological science technician Shannon Waters releases a Chinook Salmon into an Alaskan river.
Vanessa von Biela with a Chinook salmon on the Yukon River.
Vanessa von Biela with a Chinook salmon on the Yukon River.
Randy Brown adjusts a fish wheel trap on the Yukon River that will catch Chinook salmon.
Randy Brown adjusts a fish wheel trap on the Yukon River that will catch Chinook salmon.
Fish drying at a subsistence fish camp along the Yukon River.
Fish drying at a subsistence fish camp along the Yukon River.
Alaska's freshwater spans a wide range of summer water temperatures, from ice-cold glacier water to warm rivers that routinely reach stressful levels for salmon, exceeding 18°C/64°F and even surpassing 21°C/70°F. Pacific salmon population trends are also varied and include declines in many Chinook salmon populations. Salmon declines are kitchen table issues because salmon fishing is key to the wellbeing of many Alaskans. Our heat stress research began with a focus on Yukon River Chinook salmon because the river was warm, the salmon population declined, and stakeholders were concerned. Heat stress research has since expanded to other rivers and Pacific salmon species in Alaska. Our research is collaborative and responsive to the science information needs of federal, state, tribal, and local partners. The U.S. Department of the Interior has management and science responsibilities for Pacific salmon established by the Alaska National Interest Lands Conservation Act (ANILCA).
Return to Ecosystems >> Fish and Aquatic Ecology
Pacific salmon heat stress research at USGS is a sustained, multiphase, and collaborative effort with partners that began in 2015 and continues today.
This effort includes the following research activities and key findings:
Bar plot showing the percentage of Chinook salmon with evidence of heat stress in each group based on the heat shock protein 70 (HSP70) protein concentration data. Map indicates sample collection locations. Sample groups are arranged by region from north to south: Norton Sound (purple), Yukon (orange), and Kuskokwim (green). Figure from the article "Migration water temperature and heat stress assessments in western Alaska Chinook salmon overlapping the 2019 heatwave".
Map showing the premature mortality observations of Pacific salmon carcasses in Alaska during summer and fall of 2019. Symbol color and shape denote Pacific Salmon species or alternative taxonomic groupings specified in the legend. Figure from the article "Premature Mortality Observations among Alaska’s Pacific Salmon During Record Heat and Drought in 2019".
Click on each news article below to learn more:
As salmon in Alaska plummet, scientists home in on a killer
‘Too hot’ for salmon: How climate change is contributing to the Yukon salmon collapse
Fat Bear Week celebrates Bristol Bay salmon
Alaska worries for its salmon run as climate change warms Arctic waters
Yukon River, beset by salmon woes and mercury threats, signals broader Arctic climate change
Warmer waters, animal die-offs and toxic blooms are among the signs that a ‘new Arctic’ is here
Warming Yukon River adversely affecting salmon
Summer Chum Salmon Die-Off Likely Caused By Heat Stress, Say Scientists
The water is so hot in Alaska it’s killing large numbers of salmon
Why Are Salmon Being Found Dead In Rivers Across Western Alaska?
Below are other science projects associated with this project.
Below are multimedia items associated with this project.
Two juvenile coho salmon (Oncorhynchus kisutch) used in a heat stress experiment. Alaska Department of Fish and Game’s William Jack Hernandez Sport Fish Hatchery, Anchorage, Alaska, USA.
Two juvenile coho salmon (Oncorhynchus kisutch) used in a heat stress experiment. Alaska Department of Fish and Game’s William Jack Hernandez Sport Fish Hatchery, Anchorage, Alaska, USA.
Experimental tanks used in a juvenile Pacific salmon heat stress experiment for Chinook salmon (Oncorhynchus tshawytscha) and coho salmon (Oncorhynchus kisutch).
Experimental tanks used in a juvenile Pacific salmon heat stress experiment for Chinook salmon (Oncorhynchus tshawytscha) and coho salmon (Oncorhynchus kisutch).
A juvenile Chinook salmon (Oncorhynchus tshawytscha) used in a heat stress experiment. Alaska Department of Fish and Game’s William Jack Hernandez Sport Fish Hatchery, Anchorage, Alaska, USA.
A juvenile Chinook salmon (Oncorhynchus tshawytscha) used in a heat stress experiment. Alaska Department of Fish and Game’s William Jack Hernandez Sport Fish Hatchery, Anchorage, Alaska, USA.
Infographic showing water temperature and discharge (flow) data from rivers with heat-related salmon mortality, drought-related salmon mortality, and normal salmon survival in Alaska during 2019.
Infographic showing water temperature and discharge (flow) data from rivers with heat-related salmon mortality, drought-related salmon mortality, and normal salmon survival in Alaska during 2019.
A spawning Yukon River Chinook salmon (Oncorhynchus tshawytscha) captured near Pilot Station, Alaska, in June 2018 as part of an experimental temperature manipulation study to validate heat stress biomarkers.
A spawning Yukon River Chinook salmon (Oncorhynchus tshawytscha) captured near Pilot Station, Alaska, in June 2018 as part of an experimental temperature manipulation study to validate heat stress biomarkers.
An experimental tank used in a thermal challenge experiment for adult salmonids. The upper lobe of an adult Chinook salmon (Oncorhynchus tshawytscha) caudal fin is visible in the center of the water surface.
An experimental tank used in a thermal challenge experiment for adult salmonids. The upper lobe of an adult Chinook salmon (Oncorhynchus tshawytscha) caudal fin is visible in the center of the water surface.
Scientist preparing to release Chinook salmon into the Yukon River in Alaska, USA.
Scientist preparing to release Chinook salmon into the Yukon River in Alaska, USA.
Chinook salmon released into Yukon River in Alaska, USA.
Chinook salmon released into Yukon River in Alaska, USA.
Chinook salmon restrained in a cradle after non-lethal muscle biopsy sample collection for heat stress assessment at a subsistence fish wheel in the Yukon River during July 2017. The muscle biopsy location looks like one of the black spots on the back of the fish.
Chinook salmon restrained in a cradle after non-lethal muscle biopsy sample collection for heat stress assessment at a subsistence fish wheel in the Yukon River during July 2017. The muscle biopsy location looks like one of the black spots on the back of the fish.
USGS biological science technician Shannon Waters releases a Chinook Salmon into an Alaskan river.
USGS biological science technician Shannon Waters releases a Chinook Salmon into an Alaskan river.
Vanessa von Biela with a Chinook salmon on the Yukon River.
Vanessa von Biela with a Chinook salmon on the Yukon River.
Randy Brown adjusts a fish wheel trap on the Yukon River that will catch Chinook salmon.
Randy Brown adjusts a fish wheel trap on the Yukon River that will catch Chinook salmon.
Fish drying at a subsistence fish camp along the Yukon River.
Fish drying at a subsistence fish camp along the Yukon River.