Microhabitat Selection by Brook and Rainbow Trout in a Southern Appalachian Stream

The decreased range of native brook trout Salvelinus fontinalis in the Great Smoky Mountains National Park has been attributed to competition with introduced rainbow trout Oncorhynchus mykiss . To determine whether brook trout were displaced from preferred sites in the presence of rainbow trout, we made underwater observations of microhabitat use to characterize positions of individual fishes in a section of Palmer Creek, North Carolina, where both species occur. We then reduced rainbow trout numbers by about 80% by electrofishing and repeated our underwater observations on the remaining brook trout to determine whether the species underwent changes in microhabitat use. We found differences in characteristics of focal points selected by the two species. Focal points of age‐0 brook trout were similar to those of rainbow trout for distance to overhead cover. After rainbow trout were reduced, age‐0 brook trout shifted to positions significantly farther from overhead cover. Brook trout age 1 or older responded to rainbow trout reduction by shifting to positions farther from overhead cover, but to a lesser degree than age‐0 fish. No differences in focal‐point water velocity were observed between age‐0 and older fish of either species before and after rainbow trout were reduced. Shortcomings in our approach to determining the potential role ofcompetition between brook and rainbow trout for preferred stream sites underscore the need for additional research on interactions between these two species.