Abstract
Supplemental stocking is a widely used management tool to support recreational fisheries but is not always successful and can have consequences for the genetic composition of recipient wild populations. Introgressive admixture between native populations and genetically divergent stocking sources may lead to outbreeding depression and/or homogenization of genetic diversity, which could potentially decrease the fitness of the native populations. We assessed the genetic ancestry of Lake Trout Salvelinus namaycush in Cold Lake, Alberta, which received supplemental stocking from several sources after the closure of a historical commercial fishery. Recent demographic studies of Lake Trout in Cold Lake estimated increased natural mortality in the contemporary population relative to the period before the commercial fishery. Population‐ and individual‐based analyses of microsatellite loci were used to compare samples from Cold Lake collected over multiple time periods against hatchery stocking sources and a native population connected to Cold Lake via the Cold River (Pierce Lake). Despite extensive stocking over several decades and evidence of historical introgression, evidence suggests that the contemporary Lake Trout population in Cold Lake has primarily native ancestry, with little admixture from hatchery source populations. The cause of the increased mortality remains unresolved, but ecological factors should perhaps be the focus of future studies.