Evidence for Trophic Amplification and Attenuation of Climate Change Impacts on Groundfish Species Productivity in the Bering Sea, AK

Climate change is expected to impact marine ecosystems globally, with largest changes anticipated for arctic and sub-arctic ecosystems. We used multi-species stock-assessment models to link climate-driven changes in physical and trophodynamic conditions to recruitment and mortality of three Eastern Bering Sea groundfish species (Gadus chalcogrammus, G. macrocephalus, and Atheresthes stomias, herafter pollock, P. cod, and arrowtooth, respectively) in order to distinguish harvest impacts on fish populations from large-scale climate pressures. When we compared model projections under climate scenarios to those under mean historical conditions, we generally found declines in estimated acceptable biological catch (ABC) for pollock and declines in recruitment for both pollock and P. cod. However, projected declines in ABC were sensitive to model specifications of trophic interactions, specifically the strength of bottom-up or top-down controls. Stock assessment models with predation had the largest projected declines in ABC, whereas single-species models without bottom-up controls on recruitment had the lowest projected changes in ABC. Inclusion of trophic interactions amplified climate-driven declines or increases in fish abundances, emphasizing the need to evaluate multiple future scenarios and model structures when projecting climate effects on fishery species.