During the breeding season, the Colorado River cutthroat trout (O.c. pleuriticus) is a striking crimson color along the lateral line, ventral surface, and gill covers, often with equally striking shades of orange and golden yellow laid over a yellowish or brassy background color. These colors become darker with age.

Juveniles and non-breeding adults typically have white bellies which gradually take on color as fish increase in size. A variety of forms of Colorado River cutthroat have been observed, with specimens from isolated populations showing widely varying patterns of coloration and spotting, reflecting long-standing geographic isolation.

The spotting pattern of fish from the uppermost Green River system, for example, is more typical of interior cutthroat trout in general --pronounced, rounded spots no larger than the pupil of the eye, concentrated on the caudal peduncle and above the lateral line anterior to the dorsal fin. Alternately, fish from the Yampa River Basin, farther to the east and originally abutting the Continental Divide, more closely resemble the greenback cutthroat trout, with spots larger than the pupil of the eye.

Historical accounts indicate individual Colorado River cutthroat were commonly as large as 20 lbs., whereas most adult fish today are under 5 lbs. because of reduced habitat quality.

graphic Andrew Rodman ©2002
May 22, 2003
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