The Working Group on Integrative Physical-Biological and Ecosystem Modelling (WGIPEM) met in Oristano, Italy, on 13–15 June 2017. Presentations of the latest mod-elling work done within WGIPEM ToRs were given in plenary. End-to-end models (Atlantis, Osmose) have been used to explore trade-offs between fishing strategies, in the context of MSY targets. While validation of integrated model output is required to be used for advice, a comparison of different performance indices illustrated that the perception of the goodness-of-fit of complex models (e.g. ISIS-Fish) depends on the metrics and visualization tools used. Several tools have also been presented and dis-cussed within the group, among which a R-package to handle outputs of Atlantis model and create various plots and another R-package to display model results in a friendly-form, easier for communicating them to stakeholders.
Regarding advance of modelling approaches, the fish movement of the norwecom.e2e ecosystem model has been refined, and the resulting seasonal migration patterns of pelagic fish will be used to validate stock monitoring and assessment. Another model of fish movement, individual-based and following the DEB theory, produced realistic interannual distributions of sardinella and diagnostics of population connectivity, that could fuel the development of international fishing agreements.
Initiated 2 years ago, the comparison study addressing top–down trophic control in the plankton community will be revised to focus only on 3 study areas (North Sea, Baltic Sea, Nordic Seas) modelled by 7 models, to better investigate the effects of model structure and ecosystem dynamics. Another study showed that the inclusion of upper trophic level (fish) and benthic-pelagic coupling (by integrating macro-benthos) led to significant changes of nutrient dynamics simulated by ECOSMO E2E, illustrating the importance of considering these trophic links in integrated models. Finally, in the North Sea, it has been corroborated that considering a variable predation, both spa-tially and seasonally, from the fish community upon early life stages of fish leads to changes in survival of different ontogenic stages, which might affect stock estimated dynamics.
Bioenergetics studies presented show that DEB models applied to anchovy and sardine and adjusted on energy density measurements allow the identification of distinct en-ergy allocation strategy for these species. Another DEB application to cold-water corals explored the effects of starvation and climate change scenarios (acidification and tem-perature increase) and concluded that the combined impact reduces survival and leads to smaller coral. Finally, measurements of aerobic metabolic scope of fish can be used to explore potential competition between species under climate change, i.e. when their spatial distribution changes due to temperature increase (linked to their thermal pref-erences) and leads to the apparition of new competition.
During this meeting, two main gaps of knowledge were identified. The first one relates to data availability and more specifically to the need for collecting field and laboratory data on key parameters of bioenergetics processes. The second gap of knowledge dis-cussed this year concerns the limited consideration of benthic fauna within physical-biological models, and the need for further modelling effort to suitably represent this group and integrate it in end-to-end models. Intersession exchanges with other work-ing groups are expected to fill partly these gaps.