Thomas A. McDonough

Threadfin shad (Dorosoma petenense) impingement at the Tennessee Valley Authority's Cumberland Steam-Electric Plant followed a seasonal pattern related to the abundance and length distribution of young-of-year fish. Electrofishing samples taken near the plant showed a similar pattern. The number ofimpinged fish (larger than 50 mm) decreased rapidly with increasing length due to reduction in abundance by natural mortality. Impingement mortality was found to be length dependent. Most individuals. less than 50 mm in length passed through the screens, while increasingly larger individuals were...

Distribution of fish in the heavily impounded Tennessee and Cumberland River systems shows definite longitudinal zonation similar to that in nonimpounded river systems. Ten of 11 physical variables examined were highly correlated with one another, reflecting the complex of conditions accompanying changes from storage reservoirs in upper elevations to mainstream reservoirs in the lowlands. Elevation was the variable most highly correlated with the number of species. Cluster analysis indicated 4 associations of reservoirs: lower mainstream, upper mainstream and large storage, upper Holston,...