Working Group on Integrated Assessments of the Norwegian Sea (WGINOR; outputs from 2021 meeting)

Corrigendum (23/06/2023):  An error in the data used to support primary production estimates was detected and corrected in 2022. Increasing trends in net primary production reported in the highlights, in the graphical summary and in the phytoplankton section are erroneous. Readers should refer to the WGINOR 2023 report (ICES, 2023; https://doi.org/10.17895/ices.pub.22110260) where the error has been corrected.

The Working Group on Integrated Ecosystem Assessments for the Norwegian Sea (WGINOR) executes and develops an integrated ecosystem assessment (IEA) for the Norwegian Sea ecoregion. This report summarizes the working group’s progress on annual updates to the IEA and time series, development of an ocean climate forecast, a food-web based assessment of the pelagic ecosystem, evaluation of single and multispecies harvest control rules for pelagic fish, revisions of the Ecosystem Overview completed in 2021, and establishment of dialogue with pelagic fisheries stakeholders and managers in Norway, Faroe Islands, and Iceland. The Norwegian Sea Ecosystem Overview revision included updates to the pressures and their importance, and a re-evaluation of the sector-pressure-component pathways. Other outputs included: (1) a 10-page ecosystem state summary for a non-scientific audience was produced (Annex 3), (2) a framework for identifying extreme values in the time series for in-depth analysis was developed, and (3) a study on multispecies harvest control rules scenarios and another on impact of value- and ecosystem-based management scenarios on Norwegian Spring-spawning herring showed impact of management decisions on the ecosystem. Dialogue was also successfully initiated with pelagic fisheries stakeholders and managers in Iceland.

Research on ocean climate impacts on ecosystem productivity indicated Arctic water masses facilitate greater abundance of nutrients and zooplankton compared to Atlantic waters. Preliminary results suggest oceanographic conditions are influenced by many processes operating at different time-scales complicating the development of ocean climate forecast products. Model reconstruction of trophic interactions in the pelagic ecosystem suggests limited competitions between dominant pelagic fish stocks. Comparison of diet estimation methods reveals occurrence-based methods give similar results to weight-based methods but are more robust and cost efficient. Furthermore, sampling fewer specimens at more stations reduces diet variance.

WGINOR priorities for the next term is to continue development of robust IEAs to support development of ecosystem-based management and ecosystem-based fisheries management in the Norwegian Sea.