The Working Group on Integrative Physical-Biological and Ecosystem Modelling held their fourth meeting at Plymouth Marine Laboratory, Plymouth, UK. Scientists from Belgium, Denmark, France, Germany, Italy, UK, Netherlands, and USA joined the meeting either directly or by correspondence. The focus of the group is to advance state-of-the-art ecosystem-, individual-based and population modelling of marine sys-tems within the ICES areas. It further addresses effective ways of model coupling and knowledge transfer on implementations, parameterizations and tools as well as sensi-tivity testing, model benchmarking, increasing of model confidence and quantifying model uncertainty. The group’s activities help improve model-based advice on press-ing questions related to fisheries and ecosystem management. Seven non-exclusive groups of interest have been created for the year to come, and will focus on: end-to-end modelling including bioeconomical dimension, fish and fisherman movement be-havior, trophic controls including zooplankton as the key component between lower and higher trophic levels, analysis of model performance and uncertainty, connectivity models, frontiers or novel approaches in modelling, and bioenergetics modelling. A focus of this year’s meeting was on zooplankton modelling and included a joint, 1-day meeting with the WGZE. The workshop identified good examples of studies that included both models and observations to integrate knowledge, to better understand processes and to advance the science in the field, however, these are rather exceptions than the rule and more cooperation and interdisciplinary work is needed. This requires i) a standardization of measurements; ii) a stronger interaction between disciplines; iii) databases or catalogues that show where and which data are available; iv) iterative steps following data sampling, building models, integrating processes, identifying knowledge gaps, informing sampling programs on which parameters to measure etc. v) efficient and statistically sound ways to compare (or integrate) models and observa-tions. It also became obvious that, for any type of model used now to interpret field data including those capable of providing advice on Calanus harvesting, better esti-mates of the different zooplankton mortality rates are required. Trait-based models might provide a more adaptive way for modelling zooplankton distributions or diver-sity but the parameterization is very complex and requires a wealth of data, which cannot always be provided for all taxonomic groups. A first step might be size-based models, to be modified with complementary traits once a traits database is initiated from the joint effort between modelers and zooplankton ecologists. Another future re-search focus should be to investigate genetic adaptation and plasticity of single (key) species and to also focus on the whole ecosystem by integrating knowledge of all trophic levels and environmental drivers for examples through end-to-end models, coupled models and closer cooperation of field and theoretical planktologists. A joint Skype meeting with the WGIMM Chairs was also held to identify possibilities regarding coupling of models with economical and ecological focus, how to make a better use of models concerning stakeholder involvement and regarding how (and which) models can be used to provide spatial or indicator based advice.