Tracking coaster brook trout to their sources: Combining telemetry and genetic profiles to determine source populations

Radiotelemetry and genetic analysis are potent tools for informing fisheries management. Although they are usually applied independently, combining them can provide insights on fish origins, movement, and reproduction that could not otherwise be achieved. We applied these two techniques in two separate studies to resolve the origins and habitat use of coaster brook trout Salvelinus fontinalis in Nipigon Bay, Lake Superior. Telemetry of adult fish was used to determine the habitat use of coaster brook trout and microsatellite DNA genotyping to determine the relatedness of coasters to river-resident brook trout. Both studies indicated that coaster brook trout utilize multiple tributaries within Nipigon Bay for spawning. In terms of philopatric homing, however, the tracking data suggested that coasters show site fidelity between years, whereas the genetic data indicated substantial gene flow among tributaries. For individual tracked fish, the genetic data supported the homing hypothesis for 10 of 11 fish but also conclusively showed straying for 1 individual. The complementary insights from these combined data sets significantly clarify the behavior and habitat use of coaster brook trout and provide an example of the power of these combined methodologies for fisheries management.