A genetic risk assessment of native shellfish aquaculture

Abstract

Global aquaculture production is expanding, as the demand for marine protein cannot be met by capture fisheries alone. Within shellfish aquaculture, growers have begun to cultivate native shellfish to limit introduction of non-native species. However, cultivation of native species poses genetic risks to wild populations if farmed and wild animals interbreed, such as loss of genetic diversity within and among populations and loss of fitness due to domestication selection. These risks threaten long-term viability of wild populations, and are thus a concern for sustainable resource management. Genetic risks of native shellfish aquaculture have received little science and policy attention, limiting effective management of aquaculture impacts to wild populations. In my first two chapters, I quantified and characterized population structure in wild populations of two native shellfish species considered for aquaculture: the Purple-hinged Rock Scallop, Crassadoma gigantea (Chapter 1), and the California Sea Cucumber, Apostichopus californicus (Chapter 2). These results can be used by decision-makers to inform spatial management of wild shellfish species, including mitigating impacts from aquaculture. To support potential policy development regarding the genetic risks of native shellfish aquaculture, I interviewed co-managers of shellfish resources along the Pacific Coast of the United States to characterize the regulatory context for this emerging policy issue (Chapter 3). Lastly, I developed a simulation model for quantifying genetic risks of native shellfish aquaculture and used the model in a management strategy evaluation for Olympia oyster (Chapter 4), a species grown for commercial and conservation purposes.