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Genetic Characterization of Intermixed Walleye Stocks in Claytor Lake and the Upper New River, Virginia
Palmer, George Caleb
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Historically, the New River may have contained a genetically unique, river-spawning population of walleye (Stizostedion vitreum). Additionally, a number of genetically different walleye stocks have been stocked in Claytor Lake, Virginia. The increasing importance of the walleye fishery led to interest in clarifying key unknowns regarding the biology of the New River walleye stock. A radio telemetry study and genetic evaluation of present-day stocks led to identification of three spawning areas and the characterization of the genetic stock structure of walleye in Claytor Lake and the upper New River. Using radio telemetry to track movements of walleye, I determined that two resident walleye populations co-exist: one within Claytor Lake and the other in the New River above the lake. These populations establish spatially disjunct home ranges, remaining spatially separated throughout most of the year. Although there is no blockage to movement or migration, walleye within Claytor Lake generally spawn at Allisonia, while walleye within the upper New River spawn at Buck Dam. Some walleye from both populations spawn in other areas, such as Fosters Falls. Using allozymes, microsatellite DNA, and mitochondrial DNA marker techniques to examine population structure of walleye, I determined that the walleye within Claytor Lake are a panmictic population. This is the result of years of stocking walleye from different genetic stocks and interbreeding among individuals. The genetic structure of walleye from the New River also shows the presence of more than one genetic stock. Within the New River population, there exists a genetic stock of walleye that is characterized by three mitochondrial DNA haplotypes (43, 44, and 45) that previously have not been seen. This may be indicative of a unique walleye stock that is native to the New River and which has remained spatially or temporally segregated by spawning habits. The co-existence of two different walleye populations in the Claytor Lake / upper New River system justifies different management strategies. I recommend that management of the walleye population in Claytor Lake focus on increasing the exploitation of this non-indigenous stock. Management of the upper New River walleye population should focus on conservation of the unique native stock through supportive breeding and/or strict harvest regulations.