Bull trout - Mid-Columbia Recovery Unit (Salvelinus confluentus pop. 3)

Photo not available for this species
Category: Fish
State status: Candidate
Federal ESA status: Threatened
Vulnerability to climate change (More details)


Bull trout - Mid-Columbia Recovery Unit is a distinct population of Bull trout. Visit the Bull trout page for more information.

Climate vulnerability

Sensitivity to climate change


Sensitivity of bull trout is primarily driven by water temperature. Bull trout are the southern-most species of Western North American char and have lower thermal tolerance than other salmonids they co-occur with. The upper incipient lethal temperature for bull trout was found to be 21˚C, whereas the optimal temperatures for growth were in the range of 10-15˚C. Thus bull trout have a similar thermal optima to the salmonids they co-occur with, yet a lower thermal tolerance, indicating they have a narrower thermal niche and higher sensitivity to temperature. Indeed the geographic distribution of bull trout, and the persistence of populations during contemporary warming has been most strongly related to maximum water temperature. The ability of bull trout to persist in sub-optimally warm temperatures likely depends on food abundance. As temperature increases metabolic costs, the extent to which bull trout can maintain positive energy balance depends on its ability to find food. Bull trout historically relied heavily on salmon as a food resource and may be less resilient to temperatures in areas where foraging opportunities of salmon eggs and juveniles have declined. Invasive chars (brook and lake trout) now reside in many headwater streams and lakes, and may exclude bull trout from these potential coldwater refuges, increasing their sensitivity to warming. Bull trout sensitivity to flows is likely to occur during two critical periods: (1) direct effects of altered runoff timing and magnitude on emerging fry in late winter/spring, and (2) indirect effects of low summer flows on all life phases of bull trout by mediating the duration and magnitude of thermal stress events.

Confidence: High

Exposure to climate change

  • Increased water temperatures
  • Altered runoff timing
  • Increased winter/spring flood events
  • 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.