California removed 44,000 trout from Sierra lakes, helping frog numbers soar from 190 to 18,800

High in California’s Sierra Nevada, a conservation project changed the future of a disappearing amphibian. In 2001, staff at Sequoia and Kings Canyon National Parks began removing non-native trout from selected lakes and streams, restoring water bodies that had historically been home to mountain yellow-legged frogs but were naturally fishless. By 2011, nearly 44,000 trout had been removed from 19 lakes, including complete removal from nine. The results were striking: surveys in three restoration lakes recorded an increase from nearly 190 frogs and tadpoles to more than 18,800. The National Park Service says the project helped restore ecological balance and placed the frog population in a stronger position to face other threats, including deadly fungal disease.A fish introduced into fishless lakesThe mountain yellow-legged frog is native to the high country of the Sierra Nevada. These frogs evolved in lakes, ponds and streams where fish were naturally absent.That detail is important. For thousands of years, the frogs’ life cycle developed without the pressure of predatory trout. Tadpoles could grow in shallow water, young frogs could move around the edges of lakes and adults could r...