Clearing Snake Creek of Nonnative Trout to Bring Back Bonneville Cutthroat

By Jonathan Reynolds, Fisheries Biologist, Great Basin National Park. Written in winter 2018.

Collecting an eDNA sample to check for any brook trout DNA left in Snake Creek after the second treatment.

The goal

Snake Creek is the largest stream in the South Snake Range named as a conservation population for Bonneville cutthroat trout (Oncorhynchus clarkii utah) in the 2006 Conservation Agreement and Conservation Strategy for the species in Nevada. Bringing the native trout back first meant removing all nonnative fish from the stretch of the creek inside Great Basin National Park.

First treatment, 2016

In August 2016, the park, the Nevada Department of Wildlife (NDOW) and staff from other National Park Service units treated the creek with rotenone.

Then came a year and a half of checking:

• Electrofishing surveys through the 2016 and 2017 seasons caught and killed eight brook trout — meaning less than 1% had survived.
• eDNA sampling in 2017 found brook trout at 1 of 75 sites — a site with no captured brook trout.

So a second treatment was needed, and the cutthroat's return was postponed.

Second treatment, 2018

In July 2018, park and NDOW staff treated the creek again. All the brook trout and eDNA finds had been above the pipeline inlet, so the stretch from the pipeline outlet to the park boundary didn't need retreating — saving rotenone and staff.

Checking again

• Electrofishing resumed after the treatment and was to continue until the stream began to freeze. As of this writing, no fish had been found.
• A second round of eDNA sampling was done in October 2018, with results due by spring.

If the surveys confirmed the creek was clear, Bonneville cutthroat trout were to be released into Snake Creek in summer 2019.

Sources

Based on "Treatment of Snake Creek to Restore Bonneville Cutthroat," by Jonathan Reynolds, The Midden — Great Basin National Park, Vol. 18, No. 2, Winter 2018, National Park Service; a work of the United States government in the public domain.