A risk-based approach to evaluating northeast US fish community vulnerability to climate change

Risk assessment methods are used worldwide to evaluate threats posed by fisheries and other impacts on living marine resources, and to prioritize management of these threats. We derive a simplified risk analysis for aggregate fish communities as a preliminary tool to identify priorities for further detailed assessment. Because some of the largest observed rates of sea surface temperature increase are on the northeast US continental shelf, we focused on climate change-driven risks to marine communities in this region. We evaluated climate vulnerability for six communities across two ecosystems: both commercial and non-commercial demersal fish, pelagic fish, and benthic invertebrates in the Gulf of Maine (GOM) and Mid-Atlantic bight (MAB). We first evaluated the probability that anticipated climate changes (e.g. warming water, decreased salinity, increased acidity, altered boundary currents) would occur in these regions, and rated the potential severity of change over the next 10 years. Then, we evaluated the sensitivity of each biological community in each region using 12 attributes (e.g. habitat and prey specificity, temperature and acidity sensitivity, larval dispersal, adult mobility, population productivity, etc.). Exposure to the key climate risks was related to community sensitivity in each region for an overall assessment of climate vulnerability. Climate risks from increased surface water temperature, sea level rise, and earlier spring were rated moderate to high in both regions, with additional moderate to high risks in the GOM from increased bottom temperature, stratification, and river inputs. Benthic invertebrates were rated most sensitive, with demersals intermediate and pelagics lowest. Two MAB communities were rated more sensitive than corresponding GOM communities, but greater short-term climate risks in the GOM indicated increased exposure for GOM communities. Overall, this simple analysis may help prioritize short-term regional climate risk management action, thus addressing key conditions related to fishery fluctuations beyond fishing itself.