Temporal and Spatial Characteristics of the Fish Assemblage in a Large Regulated River

Jeff M. Howard* and James B. Layzer
Tennessee Cooperative Fishery Research Unit Tennessee Technological University Box 5114 Cookeville, Tennessee 38505 Voice 931-372-3094 FAX 931-372-6257 E-Mail jmh2436@tntech.edu, jim_layzer@tntech.edu

We sampled the French Broad River below Douglas Dam, Tennessee every other month at 14 sites distributed along the length of the 52 km tailwater. Eight sites were located in pool habitat, while the remainder were in run habitat. Fish were collected by boat electrofishing in both habitats. Trammel nets were also drifted in the pools to collect fish inhabiting the midstream. Significant differences in species richness occurred temporally and spatially in runs (P < 0.05). Sites near the dam had low diversity and were dominated by large cyprinids and catastomids. Downstream sites were more diverse and supported a higher seasonal abundance of percids and ictalurids. Fish assemblages in pools also showed significant temporal variation (P < 0.05), but species richness was spatially similar. However, distributions of some species (e.g., Micropterus spp.) seemed limited to certain areas of the river. Throughout the study period, catch-per-unit-effort (CPUE) for largemouth bass M. salmoides was greatest at sites near the dam, while CPUE for spotted bass M. punctulatus and for smallmouth bass M. dolomieui was higher in downstream reaches.