Survival and reproductive success of salmon and other diadromous fish depends on a return from the sea and upstream migration tens to thousands of miles through complex riverscapes to their birthplace.
Such a feat is not without risk under the best of circumstances, but many features of streams and rivers in human-dominated landscapes can further impede successful migration, such as passage barriers and increased water temperature. USGS, EPA, and University of Idaho researchers developed and tested a migration corridor simulation model that links stream conditions and fish fitness. Unlike prior models, the new model allows for greater complexity, accounting for stream network and small-scale factors such as cold water refuges that vary over time and throughout the stream network. Results from model testing of a Columbia River migration passage suggest multiple factors affect fitness including initial fish energy reserves, river temperature, and thermoregulation behavior. This model is an effective new way for biologists and managers to determine the value of cold water refuges to specific species in a given stream network and consider interventions that may increase successful migration.
Snyder, M.N., Schumaker, N.H., Ebersole, J.E., Dunham, J.B., Comeleo, R.L., Keefer, M.L., Leinenbach, P., Brookes, A., Cope, B., Wu, J., Palmer, J., Keenan, D.M., 2019, Individual based modelling of fish migration in a 2-D river system- model description and case study: Landscape Ecology, p. online, https://doi.org/10.1007/s10980-019-00804-z