Consequences of ignoring climate impacts on New England groundfish stock assessment and management

The impact of warming on fisheries resources on the Northeast U.S. Shelf is increasingly apparent through shifts in species distribution and productivity changes of economically and culturally important stocks, such as groundfish. Ignoring such impacts can potentially lead to problems with stock assessment performance and effectiveness of fisheries management decisions. Retrospective patterns (i.e., inconsistency of recent estimates after adding another year of data) currently present a large source of uncertainty in the classification of stock status and determination of catch advice for New England groundfish. We evaluated the impact of ignoring historical climate impacts on assessment performance and the resulting management for New England groundfish. We utilized a management strategy evaluation framework to simulate the impacts of climate change on recruitment, natural mortality, and growth for New England groundfish, emulate stock assessment misspecifications, and evaluate the performance of harvest control rules. Three harvest control rules were evaluated: ramped, step in advised fishing mortality (i.e., fishing mortality reduces from 75% FMSY to 70% FMSY when biomass decreases below the biomass threshold) and a constrained ramped harvest control rule (i.e., the target advised catch cannot vary more than 20% from the previous year’s catch). Results suggest tradeoffs among control rules, but addressing stock assessment bias resulting from misspecifications may be more important than identifying an optimal harvest control rule for meeting management objectives. Failure to account for changes in stock dynamics from climate change resulted in adverse effects on the performance of New England groundfish assessment and management, but the magnitude of impact varied by harvest control rule. Retrospective patterns caused unintended overfishing because of management actions derived from misperceptions of stock status. Our research shows how management strategy evaluation can be used to test the robustness of harvest control rules to climate change impacts on stock dynamics.