Effect of Dams and Flows on Fish

Principal Investigator(s): 

John Sabo

There are over 75,000 large dams on rivers in the United States alone. These dams have had measureable effects on the size and distribution of fish populations, as well as on the number and types of species in rivers across the United States. Dams block migration routes for fish like salmon and sturgeon and alter the flow and temperature of water downstream from dams. As a result, dams also tend to promote the replacement of native species by non-native species.

This Working Group is interested in quantifying the effect of dams on river flows and the composition of fish faunas. More specifically, they are interested in understanding how the number and placement of dams within watersheds changes the relative number of native and non-native species. In this way they will measure the footprint of dams on fish for entire river basins, rather than just single dams. Results from this work will contribute to a more strategic perspective on the management of large dams by identifying dams and basins where dam removal, experimental high flows, or other dam release strategies would have maximum positive impacts on native fish populations by mimicking native flow and temperature regimes.

Photo Credit: U.S. Army Corps of Engineers

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