The threatened greenback cutthroat trout once stared extinction in the face. It is native only to the waters of the Arkansas and upper South Platte rivers in Colorado, and a tiny part of Wyoming. By the 1880’s, their numbers had diminished greatly from over-fishing by miners and homesteaders on Colorado’s Front Range. Competition from non-native trouts stocked in greenback waters nearly rang a death knell.

The Colorado Museum of Natural History in 1937 reported that this colorful cutthroat was gone forever. Fortunately, greenback cutthroat trout still swam in five streams inside Rocky Mountain National Park near Boulder. Their discovery in the 1960’s set conservation in motion; the trout was placed on the endangered species list in 1973.
The U.S. Fish & Wildlife Service’s Colorado Fish and Wildlife Management Assistance Office (FWMAO) has restored greenback cutthroat trout to nearly 100 miles of streams and 450 acres of lakes working alongside biologists and concerned conservationists from Rocky Mountain National Park, Trout Unlimited, and the Colorado Division of Wildlife. Leadville National Fish Hatchery in Colorado < http://leadville.fws.gov/ > plays a pivotal role in restoring greenback cutthroat trout to the Arkansas River in southern Colorado. A brood stock is there, and when certified free of whirling disease by the Bozeman Fish Health Center http://bozemanfishhealth.fws.gov/, restoration efforts will begin in earnest, in 2006.

The Colorado FWMAO http://www.r6.fws.gov/fisheries/co/colorado_fwmao.htm is currently working to expand the range of the fish from 19 to 22 streams, all the while ensuring the fish are genetically pure. Once 22 self-sustaining populations are achieved, the fish may be taken entirely off the endangered species list.

That would be truly a remarkable event given this trout was once thought extinct, and no fish species to date has been delisted. The tremendous recreational fishing opportunity this trout provides is another measure of success. The fish doesn’t have a green back, and the origin of its name is a little mysterious. But it is no mystery what the fish means in greenbacks – dollar bills, that is. Ardent anglers spend a great deal in pursuit of this fish, generating jobs and income for others. Fishing license sales are up in Colorado, and the fish has a following. It is official state of Colorado.

Life history
The name ‘cutthroat’ comes from the crimson slash below the gills. When this trout spawns in spring, the red spreads spectacularly over the head and the complete underside.

Greenback Head

A population in the headwaters of the South Platte River had adapted to spawning at 10,000 feet above sea level; their eggs hatch quickly and the young store energy over a shortest of summers to survive the most rigorous and harshest of conditions. Its scientific name, Oncorhynchus clarki stomias, refers to the fish being related to salmon; clarki is a tribute to Lewis and Clark, given Lewis was the first scientist to write about cutthroat trout; stomias implies this trout has a large mouth.
The greenback is one of 13 subspecies of cutthroat trout, a group of trout found only in western North America, ranging from New Mexico to Alaska. This fish prefers headwaters streams in the high mountains of Colorado. It typically grows to 12 inches and 12 ounces, but has been known to reach 5 pounds in larger streams. Its diet consists primarily of aquatic insects and terrestrial beetles, flies, and moths.
For more information, contact Bruce Rosenlund bruce_rosenlund@fws.gov