Journal Article

Exploration of short-term predictions and long-term projections of Barents Sea cod biomass using statistical methods on data from dynamical models

Ottersen, Geir, Stiansen, Jan Erik, Sandø, Anne Britt, Koseki, Mariko, Årthun, Marius

2025

Overview

This study aims to explore how well simple statistical modeling can generate short-term predictions and long-term projections of the total biomass of the Northeast Arctic stock of Atlantic cod ( Gadus Morhua ) inhabiting the Barents Sea. We examine the predictability of statistical models only based on hydrographic and lower trophic level biological variables from dynamical modeling. Simple and multiple linear regression models are developed based on gridded variables from the regional ocean model NEMO-NAA10km and the ecosystem model NORWECOM.E2E. This includes the essential environmental variables temperature, salinity, sea ice concentration, primary production and secondary production. The regression models are statistically evaluated to find variables that can capture variability in Barents Sea cod biomass. Finally, future total cod stock biomass is projected by applying the best found regression models to the range of downscaled IPCC climate scenarios from the coupled Intercomparison Project Phase 6 (CMIP6 Shared Socioeconomic Pathways; SSP1–2.6, SSP2–4.5, SSP5–8.5). Our prediction models are based on variables that affect cod both directly and indirectly. We find that several regression models have high prediction skill and capture the variations in total stock biomass of the Northeast Arctic cod well. Our results suggest that increased ocean temperature and abundant zooplankton may lead to a large cod stock. However, even if total stock biomass has a positive trend with an increase in copepods in the highest warming scenario SSP5–8.5, we found that it has a negative trend in the low emission scenario SSP1–2.6 when the regional ocean and ecosystem models show weak cooling and reduced zooplankton. We show that variability in essential environmental variables can provide a remarkably good first approximation to cod dynamics. However, to resolve the full picture other factors like fishing and natural mortality also need to be addressed explicitly.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Animals / Arctic Regions / Biology and Life Sciences / Biomass / Cod / Commercial fishing / Copepods / Dynamic models / Earth Sciences / Ecology and Environmental Sciences / Ecosystem / Ecosystem models / Ecosystems / Fish / Fisheries / Fishing / Gadus morhua - growth & development / Gadus morhua - physiology / Intergovernmental Panel on Climate Change / Marine ecosystems / Models, Statistical / Ocean models / Ocean temperature / Oceans / Oceans and Seas / Physical Sciences / Prediction models / Primary production / Regional development / Regression analysis / Regression models / Research and Analysis Methods / Salinity / Salvage / Sea ice / Sea ice concentrations / Sea ice temperatures / Secondary production / Statistical analysis / Statistical methods / Statistical models / Temperature / Time series / Trophic levels / Variability / Variables / Winter / Zooplankton