Walleyes from several geographic areas have been stocked in Claytor Lake since 1940. Fish presently in the reservoir may have originated from the stocking of Kansas, Nebraska, or Pennsylvania walleyes, or may possibly be descended from a native New River walleye strain. Recent stockings (1974, 1975, 1977, 1979) utilized walleye fingerlings of primarily Kansas origin. A biochemical genetic approach was used to evaluate the present stock structure of Claytor Lake walleyes. Electrophoretic phenotypes for skeletal muscle malate dehydrogenase (MDH) and parvalbumin were identified (using starch and polyacrylamide gel electrophoresis techniques, respectively) for 217 walleyes from three Claytor Lake sites. MDH-B² allelic frequency was significantly higher in stocked than in unstacked cohorts. Muscle parvalbumin frequencies were independent of cohort, but were dependent upon collection site and sex. Parvalbumin-a allelic frequency was higher in male than female walleyes from Claytor Lake. Sex of Claytor Lake walleyes was dependent upon both collection site and cohort, with unstocked cohorts containing more female fish than the stocked cohorts (independence. G-tests). At least two genetically distinct stocks of walleyes presently survive in Claytor Lake. Allelic frequencies of Claytor Lake walleyes were compared (heterogeneity G-test and STP) to those of 428 walleyes collected from Kansas, Nebraska, and Pennsylvania in an effort to identify existing Claytor Lake stocks and to evaluate the effectiveness of recent stockings. Phenotypic frequencies for both MDH and muscle parvalbumin conformed to expected Hardy-Weinberg proportions in samples from all geographic areas, confirming assumptions of genetic control by two co-dominant alleles. Kansas, Nebraska, and Pennsylvania walleyes were different from one another, as were stocked and unstocked Claytor Lake cohorts. Unstocked Claytor Lake cohorts were similar to Nebraska walleyes. Stocked Claytor Lake cohorts were different from all three brood fish sources, probably because stocked cohorts contain both stocked Kansas fish and fish originating from natural reproduction by some other stock in Claytor Lake (probably Nebraska fish). Based on allelic frequency differences between stocked and unstocked cohorts, the stocking of Kansas fingerlings in Claytor Lake during 1975 - 1978 contributed approximately 53 percent of the recruitment to those cohorts in years during which stocking occurred, and approximately 36 percent of the total recruitment to the 1975 - 1978 cohorts. The effectiveness of the present Claytor Lake stocking program is similar to that reported for other walleye stocking programs. Based on 1975 replacement costs for walleye fingerlings, each stocked walleye caught by a Claytor Lake angler during 1976 - 1978 cost approximately $14.78. Low levels of angler harvest may make the continuation of a fingerling walleye stocking program on the reservoir economically unjustifiable. Multiple genetic stocks of walleyes can exist in a relatively small reservoir ecosystem, particularly in mainstream impoundments where very diverse habitats are often spatially isolated due to the large size of these reservoirs. The existence of these multiple stocks is an important consideration for effective management. Particular management strategies may not impact all genetic stocks in the reservoir equally (particularly if they are spatially isolated), and therefore may not produce the desired or expected results if the population is treated as being homogeneous. / Ph. D.

Thesis (M.S.)--Montana State University--Bozeman, 2006. / Title from PDF t.p. (viewed on Mar. 30, 2008). Chairperson, Graduate Committee: Christopher S. Guy. Includes bibliographical references (p. 65-72).

Recently, viral hemorrhagic septicemia virus (VHSV IVb) was associated with several walleye (Sander vitreus) mortality events in the Great Lakes. To examine the effects of route, strain-variation and temperature, walleye were experimentally infected with VHSV IVb using intraperitoneal (i.p.)-injection (102-108 pfu/fish) and immersion (w.; 1.4 x 107 virions mL-1). Walleye were relatively resistant to experimental infection with VHSV IVb, regardless of route or water temperature. High cumulative mortality (64-100%) and severe gross lesions associated with VHSV-IVb infection were only evident in fish i.p.-injected with 108 pfu at 12°C, which had mild to moderate, multifocal necrosis of several tissues including the gill and heart. There were significant differences in mortality between four walleye strains following i.p.-infection. Viral antigen was found in both i.p. and w.-exposed walleye using immunohistochemistry, mostly within the gill and skin epithelium of w.-exposed fish. VHSV IVb was detected in walleye tissues from 6-21 d post-infection using RT-qPCR. / Great Lakes Fisheries Commission and NSERC

Walleye (Sander vitreus M.) are valuable in commercial and recreational fisheries and are affected by bacterial, fungal and viral disease. Pattern recognition receptors (PRRs) are germline-encoded and constitutively expressed and bind non-self or altered-self for immune recognition. Walleye were hypothesised to have circulating PRRs that were capable of binding diverse pathogens. These PRRs were hypothesised to increase with infection, be distributed in immunologically relevant tissues and to be strain and age specific. PRR binding was measured by affinity chromatography, plasma binding assays,SDS-PAGE, Western blots, ELISA, PCR, and immunohistochemistry. ELISA and affinity chromatography assays were developed in rainbow trout (Oncorhynchus mykiss) with known PRRs. Trout ladderlectin was confirmed as a PRR binding viral hemorrhagic septicemia virus (VHSV). These techniques were adapted to walleye using Flavobacterium columnare, chitin, VHSV and Sepharose resin. A 22 kDa protein bound to F. columnare, a 17 kDa protein bound to chitin and a 34 kDa protein bound to VHSV were identified as similar to bass apolipoprotein, carp C3 and rainbow trout intelectin, respectively. PCR and 3'-RACE-PCR were used to generate nucleotide sequence to confirm identity of walleye apolipoprotein and mannose-binding lectin (MBL)-like protein from the intelectin-like sequence. Two rabbit polyclonal antibodies were raised to 34 and 67 kDa MBL amino acid sequences and used to verify MBL-like protein as a PRR for VHSV. Healthy walleye MBL-like protein plasma concentration was 7.5 ng/ml. Significant differences were found between geographically distant strains of walleye. An ELISA demonstrated that MBL-like protein had significant differences in binding affinity between multiple strains of VHSV and different viruses found in Ontario. MBL-like protein plasma levels increased with initial infection of naïve fish with waterborne and IP VHSV (107 pfu) but did not change with IP reinfection. Previous infection with VHSV significantly decreased walleye mortality. IHC of walleye shows MBL-like protein is distributed in epithelial surfaces, primarily skin, oropharynx, gill, gastrointestinal system, renal nephrons, connective tissue of gonads and plasma. There was no qualitative difference in MBL-like protein tissue distribution in healthy and VHSV-infected walleye. This is the first evidence for fish lectins binding viruses.

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Walleye (Sander vitreus) is an economically valuable freshwater fish throughout North America. In Alberta, pressure from sport fishing and commercial fishing make effective management and protection of this species crucial to its sustainability. Walleye from 12 Alberta lakes were genetically characterized using 15 microsatellite markers. Each lake contained a genetically distinct walleye subpopulation within a larger population of the river basin in which the lake was situated. Differentiation between subpopulations varied (ST=0.05 to 0.29). Patterns of genetic divergence aligned closely with the current hydro-geographical landscape, except where stocking events have occurred. Vicariance and natal philopatry are likely mechanisms maintaining the current genetic structure. The markers detected sufficient genetic variation between most subpopulations to assign an individual fish to a subpopulation of origin. The utility of genetic assignment was illustrated for stocking assessment and forensic enforcement. These genetic data will help to inform management decisions, monitor population status and enforce harvest restrictions for Alberta walleye. / Systematics and Evolution

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 70-82). Also available on the World Wide Web.

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