Curious Nature: The History of Cutthroat Trout in Colorado

This June 17, 2018, photo provided by Colorado Parks and Wildlife shows a Colorado River cutthroat trout that authorities have identified as a unique type or “genetic lineage” that was thought to be extinct. The fish are found in southwestern Colorado.
Colorado Parks and Wildlife via AP

In the state of Colorado, outdoor recreation is a $62 billion industry that supports 511,000 jobs (figures from the Colorado Office of Economic Development and International Trade). This includes money spent on travel and equipment for Colorado residents and nonresidents, as well as wages and salaries for employees in the outdoor industry. Especially in our corner of Colorado, the economy is driven by visitors hoping to explore the trails, rivers, ski slopes, and wilderness.

The fishing industry represents 29% of this economic output. Anglers from all over the world flock (or should I say “school”) to the Colorado Trout Rivers Gold Medal. They come in search of our native gem, the cutthroat trout.

Don’t let the name intimidate you: cutthroat trout must be tough to survive in an aquatic world and maintain their status as Colorado’s only native trout species. However, their name comes from the distinctive red colored “bar” on their “throat”, not their tough reputation.

They feed mainly on aquatic insects and average 8-10 inches long and live in high mountain lakes and streams that have a mixture of cool, deep pools and rapids and rapids. Cutthroat trout spawn in the spring and the newly hatched fish (aka fry) emerge from the bottom of the gravel stream one to two months later.

The cutthroat trout’s name comes from the distinctive red “slash” of its “throat,” not its badass reputation.
Artwork by Christy Belardo

Four cutthroat trout subspecies are native to Colorado: the yellowfin cutthroat trout (currently considered extinct); the Cutthroat Rio Grande in the San Luis Valley and New Mexico; the green-backed cutthroat (Colorado’s official state fish) in the South Platte River basin; and the Cutthroat Colorado River on the western slope, including Eagle County. The Colorado River Cutthroat subspecies is genetically divided into three distinct lineages: the San Juan, Green, and Blue lineages. These genetically distinct populations were historically separated by geographic barriers such as mountain ranges. Research is currently underway to learn more about the genetic purity of the different lineage populations and the extent of each lineage’s historical range.

This map from Trout Unlimited shows the native regions of Colorado’s cutthroat trout species.
Courtesy of Trout Unlimited

This small fish with a great reputation is currently threatened by a variety of past and present human actions and natural stressors. Human activities such as logging, mining, the spread of invasive species, and the diversion of water are causing habitat loss for cutthroat trout.

Climate change and resulting wildfires, debris flows, and droughts could further limit available habitat. The stocking of rivers and lakes with non-native fish species, such as rainbow trout, and the poor genetic lineage of cutthroats in the 1880s-1980s led to a series of distinct problems. Now rainbow trout and cutthroat trout can hybridize to make rainbows. Mixing green and blue genetic populations can permanently alter the genetics of Colorado River cutthroat trout. As a result, this cutthroat subspecies currently occupies only 5% of its historic range.

So what can we do to help support the conservation of this species? Work is being done by state and federal agencies in partnership with local landowners and research biologists to help protect, restore, and connect suitable habitat for cutthroat trout. Additional efforts are made to help isolate genetically pure populations and prevent future hybridization and competition. By cleaning and disinfecting your fishing gear as you move between waterholes, we can prevent the spread of aquatic invasive species.

Through stewardship of our rivers and streams and responsible recreation, we can help keep Colorado River cutthroat trout, the outdoor industry, and Colorado’s economy happy and healthy.


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