Common Patterns, Common Drivers: Comparative Analysis of System-Level Aggregate Surplus Production Across Northern Hemisphere Ecosystems

Multiple drivers act at multiple temporal and spatial scales on marine ecosystems, affecting their overall productivity. Marine ecosystems are dynamic, often have open boundaries, and respond nonlinearly to a triad of influences: climatic, anthropogenic and ecological. These are complex systems that are changing in a world of global change. In order to further our understanding of how the structure and functioning of marine ecosystems influence and regulate patterns of fisheries production, and how they are affected by external drivers, a comparative approach is required. Here we use a simplified comparative framework to examine the influence of fishery exploitation, trophic interactions, and environmental drivers on fishery production using surplus production models. We apply an aggregate surplus production modelling framework to the total aggregated fish/invertebrate biomass among eleven exploited northern hemisphere ecosystems, with and without environmental and other biological co-variates.  We use both simple regression methods (i.e., assuming only process error) and dynamic models allowing for observation error. The aim is to (a) explore the effects of common drivers at the basin scale (b) compare the relative influence within the triad of drivers among systems, (c) compare the results of the two models and (d) evaluate the effects of species interactions on overall productivity.  Finally we examine whether any “global” patterns can be detected in these results, and discus implications for an ecosystem approach to management.