Christian Smith


To evaluate the effects of human impacts on the composition and abundances of fishes on the Little Bear River, the 2012 Aquatic Ecology Practicum class conducted backpack electrofishing surveys in four sites of the river on 29 September and 4 October 2012. At these sites, species composition, biomass, and abundances were documented utilizing 2-pass electrofishing. In total, ten species were captured, with native species being represented by Bonneville cutthroat trout (Oncoryhnchus clarki Utah) and mottled sculpin (Cottus bairdii). Mottled sculpin comprised the majority of native fish captured (n= 241), while brown trout accounted for the majority of nonnatives (n= 129). Brown trout abundance was highest at the most upstream site (Station 2) and decreased going down the longitudinal gradient. Regression analysis revealed that larger average pebble size at Station 2 could be a factor in determining the observed higher brown trout abundance at this site, although the small sample size warrants further investigation. At the lowest site (Station 11) with poor water quality, only introduced species were present: green sunfish (Lepomis cyanellus), common carp (Cyprinus carpio), largemouth bass (Micropterus salmoides) and sand shiner (Notropis stramineus). Recommendations for future fisheries investigations on the Little Bear River include the sampling of additional sites, inclusion of more passes per site, and additional invertebrate and pebble sampling. Management recommendations include assessment of the potential value of a fisheries management program on the Little Bear River.