The Rio Grande cutthroat trout (Oncorhynchus clarkii virginalis) is the southern-most subspecies of cutthroat trout in the Western United States. Historically, the subspecies occupied over 10,000 km of streams in the Rio Grande, Pecos, and Canadian River basins of Colorado and New Mexico. Introductions of non-native fishes and habitat loss have reduced this subspecies to 120 conservation populations occupying less than 12 percent of its historical range (1,500 km). In 2008, the subspecies was added to the Endangered Species Act Candidate List.