Coho salmon (Lower Columbia River ESU) (Oncorhynchus kisutch pop. 1)

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Category: Fish
Federal ESA status: Threatened
Vulnerability to climate change (More details)


Coho salmon (Lower Columbia River ESU) is a distinct population of Coho salmon. Visit the Coho salmon page for more information.

Climate vulnerability

Sensitivity to climate change


In general, coho salmon likely exhibit sensitivity to warmer water temperatures (freshwater and ocean) and lower summer flows. Freshwater temperature and flow regimes: Central California represents the southern extent of the range for coho salmon, suggesting that they may be less sensitive to increases in water temperature than other species of Pacific salmon (i.e. pink, chum, and sockeye). However, due to their reliance on streams for freshwater rearing, coho are likely sensitive to both altered flow and thermal regimes. Juveniles prefer low-velocity habitat often in off-channel areas; reduced summer flows may increase the likelihood that such off-channel habitats become inaccessible, thermally stressful, or hypoxic. Early run timing individuals might be more sensitive to fall flood events, which are projected to increase in Washington, and may also be more sensitive to warmer water temperatures and lower flows during peak migration timing (i.e., mid-August to September). Later run timing individuals should be less sensitive because they migrate as adults during cooler periods of the year and their embryos are not yet buried in the gravel during late fall flooding. However, late run individuals may be more likely to have embryos or recently emerged fry threatened by spring flooding that is predicted to increase in severity and frequency. In general, coho salmon populations may be less resilient to episodic mortality events caused by climate stressors, because they exhibit only moderate levels of life history diversity and do not have as much variation in age-at maturity as do sockeye salmon and Chinook salmon. Marine: Increases in ocean and estuarine temperature, increased stratification of the water column, and/or changes in the intensity and timing of coastal upwelling may alter primary and secondary productivity, with potential impacts on growth, productivity, survival, and migrations of salmonids. For example, cool Pacific-Decadal Oscillation (PDO) years have historically coincided with high returns of coho salmon, while warm PDO cycles coincided with declines in salmon numbers. Cooler SSTs during the winter prior to and after smolt migration have also been linked to higher coho survival. In general, changes in coastal ocean habitat quality and productivity could negatively impact coho salmon.

Confidence: High

Exposure to climate change


  • Increased water temperatures (freshwater and sea surface)
  • Lower summer flows
Confidence: Moderate


This species is identified as a Species of Greatest Conservation Need (SGCN) under the State Wildlife Action Plan (SWAP). SGCN-classified species include both those with and without legal protection status under the Federal or State Endangered Species programs, as well as game species with low populations. The WDFW SWAP is part of a nationwide effort by all 50 states and five U.S. territories to develop conservation action plans for fish, wildlife and their natural habitats—identifying opportunities for species' recovery before they are imperiled and more limited.
This species is identified as a Priority Species under WDFW's Priority Habitat and Species Program. Priority species require protective measures for their survival due to their population status, sensitivity to habitat alteration, and/or recreational, commercial, or tribal importance. The PHS program is the agency's main means of sharing fish and wildlife information with local governments, landowners, and others who use it to protect priority habitats for land use planning.