The influence of habitat characteristics on the longitudinal distribution of brook, brown, and rainbow trout in a small midwestern stream

Previous research describing the distribution of sympatric native and non-native trout have centered on mountain stream habitats where gradient and elevation are more pronounced. To determine if this pattern is similar in other stream habitats, we described the distribution of sympatric brook (Salvelinus fontinalis), brown (Salmo trutta), and rainbow trout (Oncorhynchus mykiss) in a low gradient, low elevation, spring-fed Minnesota stream, and used canonical correspondence analysis to evaluate the relationship between trout distribution and physical habitat variables. Brook, brown, and rainbow trout exhibited a longitudinal gradient in Valley Creek, Minnesota, similar to other trout distribution studies in mountain streams. Temperature and gradient were not strongly correlated with trout abundance in Valley Creek, however elevation explained a substantial amount of variation. Our analysis suggests that brook and rainbow trout were utilizing habitat with similar physical characteristics, but were separated by elevation. Brown trout were correlated with different habitat characteristics than brook and rainbow trout. Although habitat variables explain a substantial amount of variation in the densities of sympatric species of trout, they do not provide an explanation into the causal relationships for the redistribution of native trout.