Genetic Tracking Through Space and Time: Single- and Multi-Generational Assessment of Source Contributions and Comparative Fitness for Introduction and Rehabilitation Efforts In Ontario

As novel experimental systems, species introductions and rehabilitation efforts are inherently uncertain.  Genetic marker systems provide unique opportunities for tracking outcomes of introduction and rehabilitation efforts across life stages, source populations, and generations.  As well as providing information on the genetic ancestry or origin of individual fish or populations, analysis of genetic diversity is also informative for reconstructing their demographic history.  Genetic tracking has been broadly integrated into fisheries rehabilitation and restoration efforts management in Ontario, with applications ranging from evaluation of recent and historical stocking contributions to wild populations, to contributions and comparative fitness among source populations used in matched-plant introductions. Examples from inland lakes and Great Lakes Areas of Concern highlight the value of implementing genetic tracking to inform management efforts for lake trout, brook trout, muskellunge and walleye.  An ambitious current project aims to re-establish self-sustaining populations of Atlantic salmon in Lake Ontario, which once held the largest freshwater population of this species in the world.  Genetic tracking is a core element of this large-scale stocking effort: using strain identification and parentage analysis, a suite of microsatellite loci are being used to quantify the survival, growth, and recruitment success of three stocked juvenile life stages from three source populations with contrasting ecologies.  As well as enabling quantification of differences in survival, growth, and timing of migration, these combined analyses are allowing for the identification of recruitment success among stocked life stages and strains, as well as the detection of natural (wild) recruits.  These examples highlight the potency of genetic marker systems as integral assessment tools for tracking the effectiveness of introduction and rehabilitation efforts for exploited and endangered fish species.