JACKSON, Wyo. — The Wyoming Game and Fish Department is planning to restore native Snake River cutthroat trout to Game Creek where the iconic fish has been absent for years after once thriving.
Game Creek is a small tributary to Flat Creek and used to be a thriving spawning stream for Snake River cutthroat trout. Historical sampling records from 1953-61 indicate Game Creek was 100% cutthroat trout. By 2016, no cutthroat trout were found during any sampling upstream of the highway.
The disappearance of cutthroat trout can be traced back to two events. The first was the periodic stocking of brook trout between 1941 and 1983. This introduction of brook trout was an important factor in the decline of cutthroat trout. The second event was the rerouting of Highway 89 to the west side of the Snake River in the 1960’s. This road construction included a new culvert for Game Creek, which no longer allowed for fish passage from Flat Creek.
Removing a fish population from a stream is not an easy task and can be done only under the right conditions. Fortunately, Game Creek provides the conditions and the opportunity for brook trout removal. The application of the chemical rotenone is the only approved method for fish removal. Rotenone works by disrupting oxygen uptake within the cells of gill breathing organisms. This means that rotenone does not affect organisms without gills.
In order to remove brook trout from Game Creek, biologists plan to apply rotenone to the stream during one day in the summers of 2020 and 2021. Treatments are conducted on subsequent years in order to make certain all brook trout are removed. The application will take place in late August when water levels are low. This allows biologists to apply the least amount of rotenone possible during the year. This timeline also allows for the treatment of the stream to take place prior to the brook trout spawn in the fall. Game Creek will be detoxified prior to entering Flat Creek to contain the chemical to that stream.
Once both treatments are complete, Snake River Cutthroat Trout will be stocked back into Game Creek to provide angling opportunities soon after the treatment. Cutthroat eggs will also be stocked to help establish a self-sustaining population. The removal of brook trout and restoration of cutthroat trout will not only return a native species to a spawning stream, but will protect Flat Creek and the Snake River from another invasion by brook trout.