Evaluating impacts of environmental stress and bioactive chemicals on the North Carolina blue crab population: An individual-based model

ObjectiveRecent estimates of the North Carolina blue crab Callinectes sapidus stock found that the stock is overfished and overfishing is occurring. Threats outlined in the 2018 stock assessment include climate change and estrogenic endocrine-disrupting chemicals (EEDCs). The objective of this study was to use an individual-based modeling approach to simulate the long-term effects of climate change and EEDCs on the North Carolina blue crab stock.MethodsTo do this, we built an individual-based model that simulated the life history of individual blue crabs, including but not limited to growth, reproduction, and mortality. We then tested our population of blue crabs against 30 different combinations of temperature and EEDC scenarios over 50 years to determine the long-term effects on the population.ResultOur simulations suggested that the North Carolina blue crab population may be relatively resilient to climate change-related temperature shifts but that there may be significant impacts at the population level as summer temperatures become more extreme. Endocrine-disrupting chemical effects resulted in an alternative stable state of lower catch or the total extinction of the population.ConclusionThese results suggest that management strategy changes may be necessary as temperatures become more extreme in the region. In addition, more research is necessary to fully understand the effects of EEDCs on blue crabs and other crustaceans at the individual and population level. This study used a novel approach to connect fine-scale blue crab ecology to broadscale population ecology. This model can be a useful predictive tool that allows for assessment of the effects of future threats or regulation changes and can be modified to simulate other important crustacean species.Impact statement