Comparison of Surplus Production Estimates with and without Environmental and Ecological Co-Variates: Patterns for Functionally Aggregated Groups Across 11 Large Marine Northern Hemisphere Ecosystems

We fit simple production models with and without covariates for several functionally aggregated groups using data for 11 large marine ecosystems.  Species were aggregated based on habitat (demersal/pelagic), size (small/medium/large using standard length to max body size ratios) and trophic guild (detritivore/benthivore/planktivore/zooplanktivore/piscivore). Covariates included common, broad-scale physical forcing functions such as AMO and PDO (depending upon ocean basin), plus water temperature and other local features. For all aggregated groups, we fit models with and without covariates.  Models were compared using typical MSY-based outputs.  The specific impacts of aggregation and covariates differed among systems, but major patterns among the different ecosystems were similar.  The evaluation of species groupings showed that various levels were 1) notably conditioned by environmental conditions, 2) varied with ecological considerations, and 3) although variable in output due to level of aggregation, were all more robust and conservative when compared to the sums of the component single species estimates.  We note how these aggregate groupings could be used in future fisheries management contexts.