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Individual Highlight

Modeling Potential River Management Conflicts Between Frogs and Salmonids

Photo of Hells Canyon Dam. Forest Service researchers and their colleagues have developed spatially explicit, individual-based models of salmonid fishes to address how dams affect them. NOAA.Hells Canyon Dam. Forest Service researchers and their colleagues have developed spatially explicit, individual-based models of salmonid fishes to address how dams affect them. NOAA.Snapshot : The Forest Service participates in the management of many regulated rivers that, while providing clean water to people, also support populations of threatened frogs and fish that can respond differently to alternative flow regimes. A novel modeling effort provides an objective, process-based approach for finding optimal streamflow regimes to sustain people, frogs and fish.

Principal Investigators(s) :
Harvey, Bret C. 
Research Location : South Fork Trinity River, Six Rivers National Forest
Research Station : Pacific Southwest Research Station (PSW)
Year : 2016
Highlight ID : 944

Summary

Flow regimes below dams affect people, fish and frogs. The optimal flow regimes for each group are unlikely to overlap extensively. Tools are needed to evaluate the effects of alternative flow regimes on highly valued species. Forest Service researchers and their colleagues have developed spatially explicit, individual-based models of salmonid fishes to address this need. This project extended the approach to yellow-legged frogs, a species of special concern in much of California. Yellow-legged frogs oviposit in rivers in spring and depend on declining flows and warming temperatures for survival and growth, whereas salmonid management can include high spring flows and low-temperature reservoir releases. Forest Service scientists built a model of how flow and temperature affect frog breeding success. Its mechanisms include adults selecting oviposition sites to balance risks to egg masses, temperature effects on development, habitat selection by tadpoles, and mortality via dewatering and scouring. In simulations of a regulated river managed primarily for salmonids, below-natural temperatures delayed tadpole metamorphosis into froglets, which can reduce overwinter survival; however, mitigating this impact via higher temperatures was predicted to cause adults to oviposit before spring flow releases for salmonids, which then scoured the egg masses. The relative timing of frog oviposition and high-flow releases critical in determining conflicts between salmonid and frog management.

Forest Service Partners

External Partners

 
  • Lang, Railsback & Associates
  • McBain Associates
  • University of California, Berkeley