An assessment of hatchery contribution and fine-scale genetic structure of brook trout (Salvelinus fontinalis) in southern Ontario streams

Brook trout in southern Ontario streams have been increasingly impacted by habitat degradation, exploitation and hatchery introductions over the past century. Effective conservation and management of fish species requires the identification and protection of locally-adapted populations. In this study, classical and contemporary population genetic analyses were used to identify native gene pools and geographic genetic structure of brook trout (Salvelinus fontinalis) in southern Ontario streams. The results provide strong evidence that extensive stocking of provincial hatchery broodstock has resulted in introgression in stream-resident brook trout populations in southern Ontario. Furthermore, use of individual-level analyses provided insights into contemporary levels of admixture and migration patterns. Brook trout movement was found to be limited largely at the sub-watershed level where genetically distinct subpopulations operate within these boundaries. These general patterns are strongly influenced by geographic proximity and correspond with expectations from a two-dimensional stepping stone model for movement and gene flow.