Mitigating fisheries-induced evolution in lacustrine brook charr in southern Quebec
Size-selective mortality due to fishing can impose strong selection on harvested fish populations, causing evolutionary changes in key life-history traits such as size at maturation. Understanding and predicting harvest-induced evolutionary change is crucial for the long-term maintenance of sustainable fisheries. I will investigate optimal management strategies for an evolutionarily sustainable fishery of the lacustrine brook charr (Salvelinus fontinalis) in southern Canada. Brook charr inhabit a series of lakes, some of which are harvested and some are not. This provides an ideal model system for investigating harvest-induced evolutionary changes and management strategies that mitigate such changes. I have previously developed an individual-based model of the effects of harvesting on life-history variation in brook charr populations, which I plan to parameterize with data provided by my collaborators, the Research Group on Aquatic Ecosystems at l’Université du Québec à Trois-Rivières. The important next step will be to elucidate optimal management strategies for the brook charr populations. In particular, I will investigate two types of management strategies, with the first aiming to minimize future evolutionary change by managing fishing effort and the second aiming to curtail ongoing evolutionary change by translocating individuals with late-maturing genes from unharvested to harvested lakes. To optimize these two strategies, I will employ genetic algorithms for evolving management strategies in the individualbased model. I will examine whether, especially when implemented together, the two optimal management strategies can slow down or reverse ongoing evolutionary changes resulting from past fishing practices and minimize future changes by improving these fishing practices.