Bridging the gap between fisheries genetics and management
Spies, Ingrid Brigitte
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The work in this dissertation addresses a gap between fisheries management and population genetics. The first chapter uses landscape genetics to determine whether natural boundaries exist in the Pacific cod stock in the Bering Sea and Aleutian Islands (BSAI) region of Alaska. Results indicate that Aleutian Islands and Bering Sea Pacific cod constitute distinct populations, and that Samalga Pass appears to be a physical barrier between the two. Until 2012, Pacific cod in the BSAI was managed as a single stock, but since that time have been managed separately, partially owing to the results of this work. In the second chapter, a novel simulation framework is used to examine the range of migration possible between North Sea and Norwegian Skagerrak Atlantic cod, given the results of genetic studies. Chapter 3 is a management strategy evaluation to answer questions regarding the utility of genetics in management decisions, given the inherent error rate in genetic studies. This chapter is parameterized for Pacific cod in the BSAI to examine the costs and benefits of incorporating genetic results into the determination of management units when two distinct populations exist. In general, incorporating the results of genetic studies into management framework increases catches and decreases the risk of population depletion below management goals. The fourth chapter examines a range of management strategies for populations subject to isolation-by-distance stock structure, a common type of population structure in marine fisheries. When disproportionate fishing effort exists, splitting a single management area into two provides less risk of depletion in individual spatial areas. Further improvement can be achieved when areas of similar fishing pressure are managed together.