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As the climate warms, cold-water refuges could be particularly important for migratory species that encounter a wide range of environmental conditions throughout their lives.

Researchers from the EPA, USGS, and University of Idaho used simulations to investigate the potential for cold-water refuges to provide relief for salmon and trout migrating upstream through a warm river corridor. Fish characteristics that impact the thermal exposure of fish during migration, such as migratory and spawn timing, swim speed, and use of cold-water refuges, were included in the simulations. The researchers found that use of cold-water refuges decreased the exposure of summer steelhead trout and fall Chinook salmon to physiologically stressful temperatures. There was more diversity in migration timing and speed, as cold-water refuge use allowed fish to migrate more slowly during warmer periods while minimizing energy expenditure. These simulations suggest that management actions designed to preserve cold-water refuges may improve the likelihood of Pacific salmon species to persist in a warming climate.  

Snyder, M.N., Schumaker, N.H., Ebersole, J.L., Dunham, J.B., Keefer, M.L., Halama, J., Comeleo, R.L., Leinenbach, P., Brookes, A., Cope, B., Wu, J., and Palmer, J., 2020, Tough places and safe spaces- can refuges save salmon from a warming climate: Ecosphere, v. 13, no. 11, e4265.