Piscicide Effects on Invertebrates in High Elevation Lakes and Streams: Establishing Baseline

Native cutthroat trout populations of the southern Rocky Mountains have declined significantly since the 1800s. Restoration of native cutthroat trout populations often requires the use of piscicides such as rotenone to remove non-native fishes before reintroduction. Rotenone interferes with fish and aquatic insect respiration and has been used in over 15 projects in Rocky Mountain National Park. Managers and scientists have presumed that effects of rotenone on non-target organisms are short-term, but few studies have actually investigated such assumptions. Measuring the effects of rotenone on non-target organisms is key to understanding the long-term ecological consequences (e.g. on the food web) of piscicide use for fish reclamation projects. Our objective is to characterize invertebrate community structure in control and treatment lake-stream networks before and after rotenone treatment. Both lake/stream networks will be sampled biannually for two years before treatment and up to 10 years post treatment. Invertebrate community metrics will be compared over time to assess site-specific changes in community structure and how long recovery to pre-treatment condition takes. In addition, we are re-analyzing the unique long-term dataset associated with Strawberry Reservoir (UT) to quantify an expected time to recovery of macroinvertebrates to piscicide treatment.