CMC's Denver Fly Fishing Section
The Greenback Trout Success Story
Article by Jorge Dominguez
CMC Trip Leader
Colorado's official state fish is the greenback cutthroat trout. Greenbacks are native to the cold waters of the state's Arkansas and South Platte River basins. The most easterly of all cutthroats, they were once thought extinct. With the help of state and federal organizations, populations are growing.
Greenbacks evolved over a span of two million years from Pacific salmon, rainbows, and cutthroats which migrated up the Columbia and Snake River systems. During the most recent Ice Age these ancestral salmonids crossed the Continental Divide. This probably occurred by way of ice dams or mudslides. They then evolved in isolation to become a distinct subspecies.
Four cutthroat trout subspecies are known to have existed in Colorado: the greenback, the yellowfin cutthroat, the Rio Grande cutthroat and the Colorado River cutthroat. Unfortunately, the populations of all four subspecies drastically declined. Mining, agriculture, logging and unregulated fishing took a great toll.
The introduction of non-native salmonids had the biggest impact. The arrival of the railroads and the emergence of fish culture combined to make trout eggs and fry easily available. The greenback’s failure to respond to early fish rearing practices soon led to other species being stocked throughout Colorado.
These newcomers interbred and out-competed the native cutthroats. The yellowfin cutthroat disappeared. By the 1930s, greenbacks were thought extinct.
However, greenback remnants were found in isolated streams in Rocky Mountain National Park and west of Boulder. Federal and state wildlife officials worked to preserve the species. Greenbacks were placed on the endangered species list in 1973 and recovery efforts ensued. The trout was upgraded to 'threatened' status five years later.
As greenbacks reproduced in hatcheries, parts of their former range were cleared of non-native salmonids. Greenbacks were then re-introduced into these waters, primarily in Rocky Mountain National Park. Naturally reproducing populations emerged. Now, catch and release fishing is allowed.
Like other cutthroat species, greenbacks can be identified by the red or orange slash on both sides of the lower jaw. Round spots found on the sides and tail are the largest of cutthroat subspecies. The upper body may or may not be greenish. The photo above shows greenbacks in spawning colors near RMNP's Fern Lake.
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