The development of a conceptual model for a Sustainable management of the Belgian part of the North Sea, based on scientic flow charts, is a first step within the BALANS-project. The conceptual model contains the information on social, economical and ecological indicators concerning fisheries and sand and gravel extraction as well as the various correlation between these aspects. Firstly, this conceptual model gives an indication of the various 'black boxes', uncertainties of information and the various correlations between these indicators. The finetuning and operationability of the conceptual model is a next step that could only start at the end of the BALANS-project. On the long term, when the BALANS-model is operational, it should give the policy makers and users of the North Sea the tools to make priorities, based on scientific advice that is constructed through an intensive cooperation between the relevant disciplines.