An index of fisheries closures due to harmful algal blooms and a framework for identifying vulnerable fishing communities on the US West Coast

Harmful algal blooms (HABs) arc a significant threat to coastal communities and their economies. They cause economic losses associated with lost fisheries landings and tourism revenue, food insecurity from loss of subsistence harvest activities, disruption of cultural practices, and loss of community identity and social interactions tied to coastal resource use. In 2015, an unprecedented bloom of Pseudo-nitzschia occurred along the U.S. West Coast, producing record high concentrations of the toxin domoic acid (DA). Widespread and prolonged fisheries closures resulted, including closures of the lucrative Dungeness crab fishery, generating an economic shock for fishery-dependent communities. To estimate the socioeconomic impacts of the closures and to compare the 2015 DA event with other events, an index was constructed that quantifies lost fishing opportunities due to toxic HABs for 17 fishing communities on the West Coast from 2005 through 2016. An examination of the HAB index shows that the 2015 DA event caused the longest duration and most geographically widespread fisheries closures on record. Communities most vulnerable to the closures of the Dungeness crab fishery were identified using indices of community social vulnerability and fishery dependence. Of the 17 fishing communities examined here, the communities of Crescent City, Fort Bragg and Moss Landing in California had the highest social vulnerability, were the most dependent on the Dungeness crab fishery, and were the most deprived of their Dungeness crab fishing opportunities; as such, these communities may have been the least resilient to the economic shock generated by the 2015 DA event.