Sign In
Maintaining and Evaluating Wild Rainbow Trout Brood Stocks
Maintaining and Evaluating Wild Rainbow Trout Brood Stocks

​​​​​​​​​​​​Led By

Dr. Eric R. Fetherman​

Study Area

Gunnison River and Harrison Creek

Project Status


Research Objectives

  • To maintain wild brood stocks of whirling disease resistant rainbow trout to supplement hatchery stocks, as necessary.

  • To evaluate wild stocks for continued disease resistance.

Project Description

Fishery managers stock whirling disease resistant rainbow trout (known as the Hofer strain) in waters across the state to supplement and recover populations previously lost to whirling disease.

In addition to maintaining hatchery brood stocks (fish used for spawning) of whirling disease resistant rainbow trout, two wild brood stocks have been established to supplement and replace hatchery brood stocks, as necessary. Researchers periodically evaluate that these brood stocks retain resistance to whirling disease. These evaluations allow Colorado Parks and Wildlife biologists and researchers to determine if the resistance characteristics of these populations are changing or remaining static, and ensure that eggs collected from these populations and used to supplement hatchery brood stocks will continue to produce rainbow trout that are resistant to whirling disease.

One of these wild brood stocks is located in Harrison Creek, a tributary of Lake Catamount in Steamboat Springs, Colorado. This wild brood stock is being used to rear crosses of the Hofer and Harrison Lake rainbow trout strains (known as the HxH). Known to be partially resistant to whirling disease, the Harrison Lake strain of rainbow trout originates from Harrison Lake, Montana. Recent research has shown that fish stocked in Harrison Creek return to the creek to spawn, facilitating future wild egg collections. Additionally, resistance to whirling disease is increasing in this population as more HxHs become established.

The other wild brood stock is located in the East Portal of the Gunnison River in the Black Canyon of the Gunnison National Park. Once managed for crosses of the Hofer and Colorado River Rainbow trout strains (known as the HxC), recent research shows that the HxC constituted only a small proportion of the total adult spawning rainbow trout population. Despite this, exposure experiments conducted using eggs from the East Portal showed that these fish had started to develop a resistance to whirling disease, likely a result of low infection levels and continued natural reproduction. Eggs are taken from this brood stock on an annual basis to stock other locations within the Gunnis​​on River, and to maintain the Gunnison River Rainbow trout brood stock in Colorado hatcheries. ​

Associated Publications