Shannon Clarke

Student Speaker | Étudiant.e
In order to ensure the sustainable management of fisheries, it is critical to integrate both demographic and genetic considerations into fishery assessments, as they both play a role in determining harvest yields and population persistence. This is especially important in populations subjected to size-selective harvest, which has the potential to result in significant demographic, life-history, and genetic changes. One important parameter that can be used to assess such genetic changes and predict future population viability is the effective population size (Ne), which is often compared with the census size (Nc) to integrate genetic and demographic changes. Very few studies, however, have measured Ne as an outcome of harvest-induced changes in fish populations. In wild populations, measuring Ne is often difficult because of the need for multiple temporal samples, so an alternate measure from a single generation (also known as Nb, or the effective number of breeders), can instead be used to compare with Nc. My thesis will investigate harvest-induced changes in the effective number of breeders for brook trout (Salvelinus fontinalis) in nine alpine lakes across three national parks in western Canada. These lakes have been subject to either traditional size-selective harvesting, or no harvest (control). Changes in Nb and Nc will be compared between control and harvest populations to assess how genetic and demographic variables may or may not be linked during size-selective harvest. The results of this study may provide valuable information regarding the long-term viability of fish populations subject to intensive harvesting.