Comparative analyses of surplus production dynamics of functional feeding groups across 12 northern hemisphere marine ecosystems

Abstract

Progress on ecosystem approaches to fisheries management requires comparative studies with standardized methods that incorporate readily available data. This precludes complex ecosystem models in favor of simpler models such as surplus production models. Surplus production models for individual species can provide estimates of common biological reference points such as maximum sustainable yield (MSY) and the corresponding stock biomass level (BMSY). For ecosystem approaches, summing multiple single-species surplus production models to estimate the ecosystem MSY ignores potential biological and fishery interactions among species. Improved estimates of ecosystem-level MSY can be obtained by aggregating species, thereby accounting for known interactions among species. Here, we fit surplus production models to 3 different types of aggregations for 12 northern hemisphere marine ecosystems. Aggregations were based on habitat (benthic/pelagic), foraging guild (planktivore/zoopivore/benthivore/piscivore) and size class (small/medium/large). The objectives of this work were to explore, compare and contrast model outputs across the various types of aggregations and among ecosystems. We found that regardless of the type of aggregation, aggregate production never exceeded 6 t km−2 and was generally less than 3 t km−2. Patterns of production varied among ecosystems with no particular pattern with respect to ocean basin, latitude or component species. Aggregated surplus production models can provide biological reference points that are familiar to fishery managers and can be used to set overall removals with respect to aggregate group as long as less productive stocks are protected.