Fish Assemblage Structure in Black Hills, South Dakota Streams

Understanding factors structuring fish assemblages in a particular area is valuable to both sport fishery management and native species conservation. Fish assemblages in the Black Hills are unique to South Dakota because they contain economi- cally valuable introduced salmonids as well as native species of conservation need. Our objective was to examine the relation- ship between fish assemblages and geomorphic and reach-scale habitat features across multiple stream reaches in the Black Hills. Canonical correspondence analysis, a direct gradient ordination analysis, indicated that factors operating at multiple spatial scales interacted to structure fish assemblages. There also was indication of segregation between native species and introduced salmo - nids. Fish assemblages were primarily structured by variables related to longitudinal stream gradients, followed by reach-scale habitat factors and biotic interactions. Habitat associations of fishes from this study provide insight into their ecology and can aid effective fisheries management in the Black Hills.