Dungeness crab (Cancer magister) is one of the most economically valuable fisheries on the U.S. West Coast. As climate change alters ocean temperature and currents, there may be ecological and environmental consequences that impact the distribution of Dungeness crab in the California Current. The potential impacts of a Dungeness crab distribution shift would not only propagate geographically, but through the social systems of coastal communities. To understand the risks and consequences of a Dungeness crab distribution shift, we used a transdisciplinary research approach to integrate research and analysis techniques from multiple disciplines in order to address three objectives. First, we used historical landings from West Coast ports and records of climate and ocean conditions to quantify factors most important in determining the Dungeness crab distribution along the California Current. Second, using the results of our first objective and regional projections for future ocean conditions, we developed several possible future scenarios for the distribution of Dungeness crab. Third, we used the NOAA framework for Vulnerability and Resilience of Fishing Communities to examine the socio-economic importance of the Dungeness crab industry in specific coastal communities, considering current and possible future distributions of Dungeness crab.
Results/Conclusions
We observed large spatial and temporal fluctuations in historical commercial landings of Dungeness crab over the past four decades. These fluctuations reflect the interconnected influences of biological, environmental, and social variability. Our analysis highlights the importance of ocean temperature, California Current strength, and upwelling, driven by climate factors (PDO and ENSO), in determining the spatial distribution of harvestable crabs. Based on the relative importance of these climate factors, we present several possible future Dungeness crab distributions. Distribution scenarios capture the proposed weakening of the California Current (resulting in reduced southward larval transport), increased sea surface temperatures (reduced survival during early larval stages), and greater mis-match between timing of larval delivery and the spring upwelling transition (reduced larval transport to coastal habitats). Given possible future changes in distribution and historical reliance on the Dungeness crab industry, socio-economic analyses identified communities with the greatest relative potential to experience impacts of a distribution shift. Our transdisciplinary research highlights the need for collaborative studies that identify consequences of increasingly uncertain future ocean changes on important coupled human-natural systems.