Colorado Fish Species: Greenback Cutthroat

These cutthroat, like their cousins the Colorado River cutthroat are extremely colorful and many consider them to be one of the most beautiful trout.  Their appearance is similar Colorado River cutthroat trout, so much so that it appears that Colorado River cutthroat were mistakenly stocked for the Greenback cutthroat trout in restoration efforts.  Greenbacks are intensely colored with large and pronounced spots heavily concentrated towards tail region. However, despite their name, the back is not pronouncedly "green."  Like all cutthroat they have distinctive orange to reddish slashes under the lower jaw.  The olive backs shade to a shades of yellow along the side and the underside often takes on a brilliant reddish color during spawn.  Most are 12 inches or smaller.  Eighteen inches is considered the maximum size, although historically it reportedly grew close to ten pounds.

These fish have adapted to spawning high elevations, as such their eggs hatch quicker than other cutthroat species.  While spring spawners, due to the higher elevations spawn may occur in late July or even early August. 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 survival is influenced by stream temperature and high altitude streams tend to have lower fry survival.

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.

Greenback cutthroat trout’s native distribution was along the Front Range of the Rocky Mountains from Wyoming to New Mexico. Today it exists east of the Continental Divide in the Arkansas and South Platte Rivers, primarily in small, isolated headwaters.  Like most trout species, Colorado River cutthroat require clear, cold water of streams, rivers, and small to medium sized lakes. Rocky Mountain National Park is this endangered species strongest toehold.  This easternmost subspecies of cutthroat trout currently occupies less than 1% of its original range. Greenback’s linage is thought to be from the Colorado River cutthroat. Both are subspecies of the Yellowstone cutthroat.