Colorado River Cutthroat Historically, Colorado River Cutthroat Trout were found throughout portions of the Colorado River drainage in Colorado, southern Wyoming, eastern Utah, northeastern Arizona, and northwestern New Mexico. Due to completion with other species and habitat degradation it is estimated that this cutthroat occupies less than 5% of its historical range, primarily in high mountain streams. Currently, approximately 100 pure-strain populations exist, mostly in small, isolated streams. Like most trout species, Colorado River cutthroat require clear, cold water of streams, rivers, and small to medium sized lakes.
Cutthroat trout are named for the reddish/orangish slash under its jaw. Giving the appearance that fish’s throat was cut. Colorado River cutthroats are among the most colored of the cutthroats. While their color varies from location, they generally have greenish hued backs transitioning to golden-yellowish side, sometimes with orange hues. Some fish may sport bright reddish colored bellies, especially males during spawn. They all have large spot uniformly distributed over the body and tail. Unlike rainbow trout it lacks white tips on the fins. As most Colorado River cutthroat trout are found in small, headwater streams, typically they are under 10 inches, but in lakes and rivers they can reach 20 inches or so.
Sexually mature at two to three years of age, cutthroats spawn in the spring. A red is built in a gravelly area, where the female lays her eggs. The male simultaneously deposits his milt over the eggs. The fertilized eggs are then covered with gravel. Fry emerge in late July through early September, about six weeks after spawn.
In lakes cutthroat feed on plankton and aquatic insects. In streams a variety of aquatic and terrestrial insects make up the bulk of their diet. Larger fish, over 12 inches will feed on small fish and crayfish.
Colorado River Cutthroat in Colorado
Courtesy of NDIS Colorado Division of Wildlife
Found in the Colorado River drainage, the Colorado River cutthroat is the ancestor of the other two native Colorado varieties. Current distribution is limited to a few, small headwater streams and lakes in northwest Colorado. Like all native cutthroat, the Colorado River variety spawns from April to June in running water. Fertilized eggs are buried in a gravel nest by females and hatch in the summer. The cutthroat, like all trout, feeds on terrestrial insects and aquatic invertebrates, but includes small fish, frogs, and mice in its diet after reaching maturity.