WGIPEM supports ecosystem modelling development and use for management purposes by exchanging knowledge, identifying knowledge gaps and recommending activities to improve model performance and uptake within management. Our terms of reference are therefore aligned along the different parts of marine ecosystem modelling: a) improving model coupling, b) improving lower trophic level models, c) improving higher trophic level models and d) improving model skill assessments. Focus under these terms may vary per reporting period, and were aligned for this period with single and cumulative anthropogenic stressors, parametrization of function diversity, benthic-pelagic coupling, connectivity and movement and metric comparison, among others. Work presented during WGIPEM meetings showed that survey design can seriously affect survey results, based on model sampling, and that this type of modelling can therefore be used to optimize survey design. This is important as observations as well are models are needed: they should be seen as complementary and both are necessary for understanding, and responsible management of, the marine ecosystem (Skogen et al., 2021). In a similar way, a modelling framework was developed to support the MSFD while population distribution was simulated in a novel way, indicating 3 separate populations in an area where management is based on a single population. Microplastics were shown to affect the spatial distribution of secondary production in the North Sea while simulations of aquaculture practises showed that multispecies aquaculture can reduce the nutrient input compared to monoculture. WGIPEM initiated a special issue of Marine Ecosystem Progress Series (estimated for fall 2021 publication) which will focus exclusively on dynamic modelling and includes multiple studies included in this report. WGIPEM also attended the WKCONSERVE workshop and heard presentations from or had joint sessions with BEWG, WGSAM, WGBIOP, WGINOSE, WGSPF and WGMPCZM. One joint publication was published (Skogen et al., 2021) with another submitted (Van de Wolfshaar et al., 2021). Initiatives for more collaborative papers were started. WGIPEM will continue to promote ecosystem modelling in their new Terms of Reference including a focus on incorporating human dimensions and ensemble modelling for support of management