Amphibians, Reptiles, & Fish
The introduction of fish has had many unintended effects - the most dramatic being the resulting decline in the mountain yellow-legged frog populations (under consideration for listing as federally endangered) due to predation. Scientists have investigated the role of other causative factors in their decline, such as acid deposition, UV-B radiation, and disease, but predation is clearly the main problem. When fish are present, they eat frogs, force frogs into marginal habitat, and fragment the population, the latter of which hinders recolonization. Wildlife management staff hope to remove exotic fish from some naturally fishless lakes to help restore the native frog population.
In order to monitor the density, distribution, and species composition of native and exotic fish, counts are regularly conducted along set transects. Transects of western pond turtles in low elevation rivers and streams are another important monitoring project. These turtles are impacted negatively by non-native bullfrogs that eat the young.