Modeling Climate Impacts on Northeast Fisheries and Ecosystems

An important element of stock assessment is to forecast the abundance of fish in the future and then recommend catch limits that either maintain or rebuild stocks to defined levels. Most stock assessment forecasts assume stationary environmental and ecological forcing (i.e., no trend with random variability). However, climate is changing and there is greater recognition of decadal variability in climate, both of which violate the stationarity assumption made by many stock assessments. In the northeast U.S., there is clear evidence that the climate is changing and that there is pronounced decadal variability in climate. Further, there is clear evidence that climate is affecting fish abundance and distribution. Over the past several years, the Northeast Fisheries Science Center has been developing methods to forecast stock abundance and distribution under climate change scenarios and to incorporate this information into stock assessments. These studies link General Circulation Models to population dynamic models and make forecasts of abundance and distribution in the future. Work with Atlantic cod suggests extirpation from Southern New England and reduced stock productivity. Work with Atlantic croaker indicates the opposite: poleward range expansion and increased stock productivity. Recent work with gray snapper, forecast modest range expansion along the southeast coast, but no shift into the northeast region. Efforts with cusk and winter flounder are currently underway in an endangered species status review and stock assessment context, respectively. Taken together, these studies suggest regional and species–specific responses to climate change and some of these responses are significant, both biologically and economically. These studies also demonstrate the weakness of current approaches and point to what is needed in the future: decadal and regional skill in climate forecasts, more holistic and better parameterized population models, and incorporation of species interactions, and increased integration with ecosystem models. Incorporating climate change into fisheries management is going to be a major challenge facing NOAA in coming decades; we have tools and approaches that can be used now, but we need to further develop these and expand their application to meet this growing challenge.