Influence of a Kentucky Flood-Control Reservoir on the Tailwater and Headwater Fish Populations

Abstract

An impoundment on the Green River, Kentucky, altered the fish community below the dam and in the unregulated river above the reservoir. Reservoir species apparently migrated both down-stream and upstream out of the reservoir and were abundant in both areas. Abundance in the tailwaters of two species common in the reservoir—white crappies (Pomoxis annularis) and gizzard shad (Dorosoma cepedianum)—was positively correlated with the volume of discharge. Redhorse (Moxostoma sp.) and catfish (Ictaluridae) were less abundant in the tailwaters than above the reservoir. Post-impoundment reductions in abundance of minnows (Cyprinidae), redhorse, and catfish in the tailwaters appeared to be related to lower water temperatures caused by discharge of water from the hypolimnion. Use of a stream station above a reservoir to represent the pre-impoundment fish community will lead to erroneous conclusions for species that migrate extensively upstream after becoming established in the reservoir. However, comparisons may be valid for species that seldom move upstream.