Browsing by Author "Palmer, George Caleb"
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- Genetic Characterization of Intermixed Walleye Stocks in Claytor Lake and the Upper New River, VirginiaPalmer, George Caleb (Virginia Tech, 1999-12-02)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.
- Marker-assisted restoration of native New River walleyeHarris, Sheila; Copeland, John R.; Palmer, George Caleb; Hallerman, Eric M. (New River Symposium, 2017-05-16)Walleye (Sander vitreus) is an important game fish in the Upper New River, with March and April walleye fishing effort from Buck Dam to Claytor Lake increasing from 49 to 66% of total fishing effort between 2007 and 2016. Population genetics research has shown the persistence of the presumptive native stock in the New River. Although the river had been stocked from sources in the Great Lakes region, unique genetic markers (microsatellite alleles at the Svi17 and Svi33 loci and mitochondrial restriction fragment haplotype 43) were observed, indicating that the native stock had persisted. Native walleye is of conservation interest due to their adaptation to a southern river system and their large ultimate size. Genetic marker-assisted selection of presumptive native walleye has been carried out since 2000, and has led to an increase in native allele frequencies from 16% and 14% in the 1997 and 1999 genetic surveys to 46% and 58% in the 2004 and 2006 surveys. Walleye abundance and angler catch increased over this time period in relation to annual stocking success. Ongoing work is aimed at deepening our understanding of population genetics and natural history of walleye in the southeast.