Skilful prediction of cod stocks in the North and Barents Sea a decade in advance

Vimal Koul,Geir Ottersen,Corinna Schrum,Camilla Sguotti,Marius Årthun,André Düsterhus,Sebastian Brune,Johanna Baehr,Bjarte Bogstad

doi:10.1038/s43247-021-00207-6

Abstract

Reliable information about the future state of the ocean and fish stocks is necessary for informed decision-making by fisheries scientists, managers and the industry. However, decadal regional ocean climate and fish stock predictions have until now had low forecast skill. Here, we provide skilful forecasts of the biomass of cod stocks in the North and Barents Seas a decade in advance. We develop a unified dynamical-statistical prediction system wherein statistical models link future stock biomass to dynamical predictions of sea surface temperature, while also considering different fishing mortalities. Our retrospective forecasts provide estimates of past performance of our models and they suggest differences in the source of prediction skill between the two cod stocks. We forecast the continuation of unfavorable oceanic conditions for the North Sea cod in the coming decade, which would inhibit its recovery at present fishing levels, and a decrease in Northeast Arctic cod stock compared to the recent high levels.

Highlights

Reliable information about the future state of the ocean and fish stocks is necessary for informed decision-making by fisheries scientists, managers and the industry
The time series of sea surface temperature (SST) in the North Sea and Barents Sea Opening highlight key differences in the two regions: While SST has an increasing trend both in the North Sea and in the Barents Sea Opening, the absolute values are very different from each other, highlighting that the cod stocks reside at the two extreme ends of the thermal habitat available for cod[40] (Fig. 1a)
Sustainable management of fish stocks in the eastern North Atlantic shelf seas requires a reliable assessment of their future abundance

Summary

Introduction

Reliable information about the future state of the ocean and fish stocks is necessary for informed decision-making by fisheries scientists, managers and the industry. Other approaches have combined GCM output with highly resolved physical–biological shelf-sea models accounting for trophic interactions[6] These approaches focus on long-term (>30 years) changes and do not provide information on decadal (1–10 years) fisheries forecasts. This prospect emerges from the influence of Atlantic inflow on both hydrography[34,35] and marine ecosystem of the North Atlantic shelf seas, such as the North and Barents Sea[15,16] and from the impact of anthropogenic warming on marine ecosystems[13] In these climate-driven marine ecosystems, statistical climate–fisheries models[36] provide a promising approach for transforming GCM-based ensembles of decadal climate predictions into reliable fisheries forecasts

Methods

Results

Conclusion