Trout stocking pushed Sierra Nevada yellow-legged frogs from 92% of their range

For more than a century, California’s high mountain lakes were stocked with trout to make remote wilderness more attractive to anglers. Between 1870 and 1988, fish were carried or flown into lakes and streams that had historically been fishless, creating new opportunities for recreation but also changing the balance of life in the Sierra Nevada. The introduced trout ate mountain yellow-legged frogs, their tadpoles and the insects the amphibians depended on. Over time, the once abundant frogs disappeared from about 92 percent of their historic range. As explained by the National Park Service (NPS), the story is one of unintended consequences, where a decision made to support fishing transformed fragile alpine ecosystems. Today, park managers are removing nonnative fish from selected waters and restoring the habitats where the frogs evolved without major aquatic predators.Fish in naturally fishless lakesThe Sierra Nevada contains thousands of lakes, ponds and marshes scattered across high elevations. Before modern fish stocking, many of these waters were naturally fishless. Steep waterfalls, dry stretches and other landscape barriers prevented trout from reaching them from lower rive...