Arctic Grayling

Illustration by Michelle LaGory. Courtesy of Wyoming Game & Fish.

One of 11 fish species native to Yellowstone National Park, fluvial (entirely stream-dwelling) Arctic grayling (Thymallus arcticus) were historically common within the Madison, Gibbon, Firehole, and Gallatin rivers. However, with the introduction of competing non-native fishes such as brown trout (Salmo trutta) and brook trout (Salvelinus fontinalis), and the fragmentation of migratory pathways caused by the construction of the Hebgen dam, fluvial grayling have likely been eliminated from their native range within the park. Although anglers occasionally catch grayling in the Gibbon River, research has shown they are from the headwater lakes. The only known grayling populations that remain in the park are adfluvial (lake-dwelling).