Naive Cutthroat Trout Released in Woods Lake

photo of cutthroat trout up close in hand

This summer approximately 250 native cutthroat trout were released in Woods Lake as part of an ongoing project to restore the species to its native habitat.

Cutthroat trout were once an abundant species in Colorado, but for the past 50 years haven’t been very common. Currently, the species only occupies around 14 percent of its original habitat.

Different species and lineages of cutthroat trout are found across the western states. In Colorado, there are three species of cutthroat trout in different regions of the state. Colorado River cutthroat trout live in drainages west of the continental divide, greenback cutthroat trout are in the South Platte and Arkansas River drainages, and the Rio Grande cutthroat trout are found in streams draining into the San Luis Valley, according to Parks and Wildlife. Efforts to restore the species have been ongoing since the early 1970s, when greenback cutthroat trout were listed as endangered. This species currently has a lesser-threatened classification.   

The plan is to have Woods Lake become a brood stock for the species for future relocation efforts, which could boost their population numbers. The 24-acre lake is located off of Forest Service Road 618 west of Telluride and was chosen for a number of reasons — mainly its pristine condition and remote location. Barriers also prevent non-native species from gaining access. Introductions such as this one at Woods Lake could help the species make a comeback.

The reintroduction plan ultimately calls for more than 2,000 fish to be stocked into the lake and its surrounding tributaries — the next stocking is planned for the spring of 2013. "The spring relocation will give multiple age classes of fish which will provide good genetic diversity," said Dan Kowalski, an aquatic researcher with Parks and Wildlife in Montrose.

Before this summer, the lake was home mostly to brook and brown trout, both non-native species. Over the last two years, to make room for the native species, the lake has been treated with a chemical called Rotenone. Rotenone is derived from the root of a tropical plant and is fast-acting, and leaves no residue. Rotenone quickly degrades in the environment or can be manually neutralized by the application of an oxidizing agent commonly used to treat drinking water.

The last treatment was applied in mid-August to remove non-native fish that eluded earlier treatments. Biologists have been electro fishing and netting the lake and its tributaries to assess its suitability for the reintroduction.

Fishing at Woods Lake might be sparse over the next two years, but if everything goes as planned, it will eventually be full of native cutthroat trout. While anglers can expect to start catching fish by next summer, the waters will remain catch and release until the species’ population is larger.

According to Parks and Wildlife, another cutthroat trout restoration project is ongoing in the upper Hermosa Creek drainage near the Durango Mountain Resort in San Juan County. When that project is completed in about five years, more than 20 miles of Hermosa Creek and feeder streams will also be home to native cutthroat trout.

For more information on Colorado’s aquatic and other wildlife, visit wildlife.state.co.us

photo of boat on lae with biologist spraying rotenone
 

Biologists spray rotenone in Woods Lake to remove non-native fish species that compete with native cutthroat trout.

photo of biologist mixing rotenone

Rotenone is diluted and mixed for application to the lake and its tributaries. Rotenone is derived from the root of a tropical plant and is fast-acting, and leaves no residue. Rotenone quickly degrades in the environment or can be manually neutralized by the application of an oxidizing agent commonly used to treat drinking water.
 

photo of biologist setting up poison dispenser

A Forest Service Fisheries Biologist sets up a device to slowly release the chemical into the upper reaches of the lake's watershed.

photo of biologist pouring color dye in creek  

A green dye is placed in the water as the rotenone is released to track the distribution of the chemical in the tributaries.

photo of green dye spread through creek

The neon green dye quickly flows with the rotenone down stream. The upper reaches are perfect habitat for brook trout, a non-native species that out compete the native cutthroat trout. Effective and timely treatments of rotenone will remove adult and fry stages of these fish and "set the stage" for successful reintroductions of native cutthroat trout.     

photo of biologist spraying creek

Several of the small, upper reaches of tributaries are more effectively treated by spraying rotenone.

photo of lake in fall

After the fish populations have a chance to grow in a few years, the very scenic Woods Lake will be full of native cutthroat trout  - an anglers delight!