Steepness, lakes, and forest cover are the main factors influencing salmon-stream temperatures

Salmon returning to streams and lakes in Southeast Alaska are affected greatly by water temperatures both in winter and summer, and these temperatures are projected to increase given climate warming. Changes in water temperature affects the time it takes for salmon eggs to hatch and emerge, and the timing of salmon returning to each stream, as they seek to avoid dangerous peak stream temperatures. Thus predictions of the effect of climate warming on salmon populations relies critically on predictions of water temperatures. Now, a new study identifies the most important factors that can be used to predict changes in water temperature in the future in these salmon-producing streams and lakes. In summer, streams in areas with shallow gradients and more lakes had both higher and more variable temperatures; in winter, temperatures were higher in areas with steep gradients that had greater forest cover and more lakes. Thus both landscape features and forest cover influence stream temperature, and hence the productivity of salmon produced by each watershed. The research was led by Michael Winfree; coauthors include SAFS professor Daniel Schindler; and it appears in the journal Environmental Research Letters.

Back to Top