The physiological challenge for anadromous fish to migrate upriver to spawn and complete their life cycle is influenced by river temperature.
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The impacts of river temperatures can be difficult to predict due to an incomplete understanding of how temperature influences migration costs, especially in high latitude ecosystems. To assess temperature influences on migrating Pacific salmon in a Subarctic watershed, we measured an indicator of heat stress (heat shock protein 70), energy density of Sockeye Salmon (Oncorhynchus nerka) throughout their upriver migration, and pre-spawning mortality. We suspected Sockeye Salmon energy levels would be reduced by warmer river temperatures; however, we found no evidence of heat stress, similar rates of energetic decline from river entry to the spawning grounds amongst years, and minimal evidence of pre-spawn mortality. In fact, higher accumulated thermal units (ATU) resulted in higher energy densities in migrating salmon. This is likely due to how the bell-shaped curve of thermal optimal conditions for Sockeye Salmon interacts with the thermal regime of the river. The Pilgrim River is at the northern edge of the Sockeye Salmon distribution and often ranges below the optimal temperature for Sockeye migration resulting in a positive effect of warmer temperature pulses on somatic energy. Hindcasting back to 1907, the predicted river temperatures during the spawning migration historically were not substantially different from the measured river temperatures (2013-2016). Air temperature predictions for 2040, 2060, and 2090 indicate an increase in ATU, but not to the level that would suggest negative impacts. ATU levels resulting in negative effects would require a combination of increased air temperature with a dramatically prolonged migration. Understanding interactions between environmental drivers and biological responses will help anticipate future changes and will provide insights to make informed management decisions within the watersheds.
Below are other science projects associated with this project.
Fish and Aquatic Ecology
Condition of Forage Fish in Prince William Sound During the Marine Heatwave
Winter Habitat of Juvenile Dolly Varden in the Canning River
Arctic Lake Food Webs
Ecosystem Shifts in Arctic Seas
Lake Trout Biochronologies as Long-term Climate and Productivity Indicators in Alaska Lake Ecosystems
Primary Production Sources and Bottom-up Limitations in Nearshore Ecosystems
Hydro-Ecology of Arctic Thawing (HEAT): Ecology
Effect of Elodea spp. on Fish Performance Mediated Through Food Web Interactions
Nearshore Fish Surveys in the Beaufort Sea
Assessing heat stress in migrating Yukon River Chinook Salmon
- Overview
The physiological challenge for anadromous fish to migrate upriver to spawn and complete their life cycle is influenced by river temperature.
Return to Wildlife, Fish, and Habitats >> Fish and Aquatic Ecology
The impacts of river temperatures can be difficult to predict due to an incomplete understanding of how temperature influences migration costs, especially in high latitude ecosystems. To assess temperature influences on migrating Pacific salmon in a Subarctic watershed, we measured an indicator of heat stress (heat shock protein 70), energy density of Sockeye Salmon (Oncorhynchus nerka) throughout their upriver migration, and pre-spawning mortality. We suspected Sockeye Salmon energy levels would be reduced by warmer river temperatures; however, we found no evidence of heat stress, similar rates of energetic decline from river entry to the spawning grounds amongst years, and minimal evidence of pre-spawn mortality. In fact, higher accumulated thermal units (ATU) resulted in higher energy densities in migrating salmon. This is likely due to how the bell-shaped curve of thermal optimal conditions for Sockeye Salmon interacts with the thermal regime of the river. The Pilgrim River is at the northern edge of the Sockeye Salmon distribution and often ranges below the optimal temperature for Sockeye migration resulting in a positive effect of warmer temperature pulses on somatic energy. Hindcasting back to 1907, the predicted river temperatures during the spawning migration historically were not substantially different from the measured river temperatures (2013-2016). Air temperature predictions for 2040, 2060, and 2090 indicate an increase in ATU, but not to the level that would suggest negative impacts. ATU levels resulting in negative effects would require a combination of increased air temperature with a dramatically prolonged migration. Understanding interactions between environmental drivers and biological responses will help anticipate future changes and will provide insights to make informed management decisions within the watersheds.
Sources/Usage: Public Domain.Sockeye salmon being collected with gill nets with cooperation of subsistence harvesters in Grantely Harbor, where the Pilgrim River enters the Bering Sea.(Credit: Mike Carey, USGS. Public domain.)
Sources/Usage: Public Domain.Collecting water quality data on the Pilgrim River. Types of measurements taken were on water temperature, dissolved oxygen, pH, and conductivity.(Credit: Chris Zimmerman, USGS. Public domain.)
Sources/Usage: Public Domain.The fish weir is operated on the Pilgrim River by the Norton Sound Economic Development Corporation with assistance from the Alaska Department of Fish and Game.(Credit: Mike Carey, USGS. Public domain.)
Sources/Usage: Public Domain. Visit Media to see details.Beach seining on the spawing grounds of sockeye salmon in Salmon Lake. This is the headwater of the Pilgrim River which is the northern edge of the sockeye salmon distribution.(Credit: Mike Carey, USGS. Public domain.)
Sources/Usage: Public Domain.Chris Zimmerman removing otoliths from sockeye salmon carcasses on the shoreline of Salmon Lake. Otoliths are used to read age of a fish and other chemical signatures over time.(Credit: Mike Carey, USGS. Public domain.) - Science
Below are other science projects associated with this project.
Fish and Aquatic Ecology
Fish and aquatic habitats in Alaska support important commercial, sport, and subsistence fisheries and provide forage fish that support wildlife populations. The USGS Alaska Science Center conducts interdisciplinary research to inform local, state, federal, and international policy makers regarding conservation of fish, aquatic species, and their habitats. We work collaboratively with hydrologists...Condition of Forage Fish in Prince William Sound During the Marine Heatwave
Changes in the body condition of a key forage fish species, Pacific sand lance (Ammodytes personatus), are examined to understand how energy transfer to predators may have been disrupted during the recent marine heatwave in the North Pacific (late 2013 to mid 2016).Winter Habitat of Juvenile Dolly Varden in the Canning River
In the Arctic, rivers often freeze all the way to the bottom each winter leaving fish with limited habitat where they can survive.Arctic Lake Food Webs
From 2011 to 2013 we investigated freshwater food webs of Arctic Coastal Plain lakes in Alaska to improve our understanding how Arctic freshwater food webs may respond to landscape change the warmer, drier future.Ecosystem Shifts in Arctic Seas
In addition to the direct effects of sea ice loss on walrus (Odobenus rosmarus divergens) and polar bears (Ursus maritimus) that use ice as a platform, the decline of Arctic sea ice is predicted to promote a fundamental ecosystem shift from benthic animals that forage on the sea floor to pelagic animals that forage near the sea surface.Lake Trout Biochronologies as Long-term Climate and Productivity Indicators in Alaska Lake Ecosystems
High latitude ecosystems are among the most vulnerable to long-term climate change, yet continuous, multidecadal indicators by which to gauge effects on biology are scarce, especially in freshwater environments.Primary Production Sources and Bottom-up Limitations in Nearshore Ecosystems
Kelp forests are among the world’s most productive habitats, but recent evidence suggests that production is highly variable.Hydro-Ecology of Arctic Thawing (HEAT): Ecology
Permafrost thaw is leading to a myriad of changes in physical and chemical conditions throughout the Arctic.Effect of Elodea spp. on Fish Performance Mediated Through Food Web Interactions
The potential for invasive species introductions in Arctic and Subarctic ecosystems is growing as climate change manifests and human activity increases in high latitudes.Nearshore Fish Surveys in the Beaufort Sea
Nearshore systems provide habitat to a unique community of marine and diadromous (lives in both fresh and saltwater) fish and support high fish abundance.Assessing heat stress in migrating Yukon River Chinook Salmon
We will examine evidence of heat stress in Yukon River Chinook salmon (Oncorhynchus tshawytscha) using heat shock proteins and gene expression. - Multimedia
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