Date of Award
Doctor of Philosophy (PhD)
Professor B.N. White
Increases in the use of hatchery fish have raised interest in the genetics of hatchery-reared fish. Four types of genetic concerns have been identified for hatchery stock management: loss of stocks, domestication, loss of within and among-stock genetic variability. Each has an impact on the quality of fish available. To address these concerns, mitochondrial DNA, randomly amplified polymorphic DNA, and microsatellite DNA loci were considered for their suitability for stock discrimination, hatchery monitoring, and mixed-stock analysis of rehabilitated populations of lake trout (Salvelinus namaycush) Mitochondrial DNA variation was analyzed to determine if it could be used in a mixed-stock analysis. The accuracy of the estimates was low because one clone is found at high frequencies in all lake trout stocks studied. Mitochondrial DNA variation may have limited application in mixed stock analysis, but is well suited for further studies of variation in the wild. Randomly amplified polymorphic DNA (RAPD) loci were tested for Mendelian inheritance in lake trout and the 13 variable loci amplified in the Killala Lake hatchery stock were inherited in a Mendelian fashion. Individual variation of RAPD markers in lake trout hatchery stocks was large which made genetic stock identification and mixed-stock analysis difficult. Genetic relationships among hatchery stocks in Ontario were examined using microsatellite DNA loci. Heterologous primer sets designed for other salmonid species could be used to amplify microsatellite loci in lake trout. The genetic relationships observed among the hatchery stocks were similar to those observed in previous genetic analyses using allozyme and mitochondrial DNA markers. The results of a simulation study based on microsatellite DNA and allozyme loci indicate that microsatellite DNA loci provide more accurate estimates than allozyme loci in mixed stock analyses. Further comparisons of microsatellite DNA loci to mitochondrial DNA and RAPD loci indicate that microsatellite loci are the most useful for mixed-stock analysis. Nuclear markers in general are more useful than mitochondrial markers because they provide data on the contributions of both sexes, whereas mitochondrial DNA data only describes the contribution of females. Comparisons of genetic variation in Ontario hatchery stocks of lake trout using mitochondrial DNA, RAPD loci, and microsatellite DNA loci indicate that within stock varaiation is being maintained in moost stocks. Small numbers of founders and unequal sex ratios may be responsible for any losses that have occurred. Among-stock variation is similar to that observed in wild populations. The few changes observed may be due to sampling errors of gametes used to found broodstocks or to provide yearling lake trouut for hatchery supplemented lakes such as Lake Simcoe.
Stott, Wendylee, "Genetic Variation within and among Ontario Hatchery Stocks of Lake Trout (Salvelinus namayacush) as Measured by Three Molecular Market Systems: Applicants to Rehabilitation and Hatchery Management" (1998). Open Access Dissertations and Theses. Paper 2075.