The Dungeness crab is one of the most iconic and intensively harvested marine species on the west coast of North America. In Washington state, the Puget Sound Dungeness crab fishery is managed independently from the open coast fishery and accounts for ~45% of the statewide fishery. Vulnerabilities in the current management framework have been exposed by recent fishery closures, yet despite the considerable value of the fishery, the development of adaptive management strategies has been inhibited by a lack of fundamental biological knowledge. Several lines of evidence suggest that Puget Sound may represent a mixed-stock fishery, in which fishery yields vary according to the relative supply, survival, and growth of genetically distinct populations. If this is the case, management under the current system risks overexploitation of vulnerable stocks, as well as underutilization of more robust stocks.
We are working to determine if current spatial management areas align with the true population structure of Puget Sound Dungeness crab. High-throughput genomic techniques are being used to characterize crab population structure, assessing both population connectivity and potential local adaptation among populations. Estimates of effective population size will be used in lieu of census population size to compare stock robustness. The project leverages established regional collaborative efforts of the Pacific Northwest Crab Research Group (PCRG), composed of federal, state and tribal biologists, NGOs, industry members, community scientists and students. Sampling of adult crabs throughout the region was coordinated with commercial fishers and biologists during pre-season test fisheries in 2023. Crab larvae were also sampled by the PCRG larval crab monitoring network to provide the clearest possible picture of sources and sinks of crab cohorts, and their relative strengths in each region. A low coverage whole genome sequencing approach was used to genotype all specimens at a depth of approximately 2x. Results will be discussed in the context of prior genetic research on Dungeness crab and the potential implications for fishery management.