Twelve miles east, the waters of the Gibbon and Firehole Rivers join to form the Madison River. Flowing through the heart of this valley, its rich waters nourish an abundance of wildlife. Trout feed on bountiful insect hatches, while osprey and other raptors use keen eyesight to swoop down for prey and river otters glide underwater hunting fish. Upstream, elk and bison forage on lush valley grasses. Wild trout remain abundant here, but the fish community has been greatly altered by historic stocking of non-native species. Westslope cutthroat and grayling once thrived in the Madison River, but they are now gone, displaced by non-native rainbow and brown trout. Today, Yellowstone’s native fish are protected by a catch-and-release program and the use of barbless hooks.