Testing the feasibility and effectiveness of genetic restoration by facilitated introgression of aurora trout (Salvelinus fontinalis timagamiensis)

Genetic restoration through translocation has been used to reverse inbreeding depression across a range of taxa with some success. Although uncontrolled trials entail some risk, using experimental breeding crosses in controlled environments can test the feasibility of genetic restoration for enhancing fitness in populations of conservation concern without risking outbreeding depression and irreversible genetic loss. All contemporary aurora trout are descended from nine founding individuals collected in 1958, followed by multiple generations of hatchery rearing. With unavoidable inbreeding in the early captive generations, inbreeding depression is a significant risk to their long term survival. I investigated the effectiveness of genetic restoration of aurora trout by monitoring the ecological fitness in second generation crosses between aurora trout and brook trout. As well as tracking the comparative life history of second-generation crosses under controlled hatchery conditions, aurora trout and two backcross types were marked and stocked into two inland lakes to assess their ecological fitness and phenotypic expression. Results from both the hatchery and wild trials showed increased ecological performance of hybrids over pure aurora trout, with variable phenotypic expression. These results suggest that genetic restoration through introgression can restore the fitness of aurora trout without compromising their phenotypic and evolutionary distinctiveness.