We propose an ecosystem approach to the aquaculture sector. We will address this by 1) identifying plausible quantitative indicators of the effects of aquaculture on ecosystems through a process of expert working groups, workshops and meetings, 2) similarly, identifying indicators of the main drivers of ecosystem change affecting aquaculture, including natural and environmental pressures, 3) assessing both sets of indicators using existing datasets (the partners collectively have extensive data archives), considering each in the context of appropriate selection criteria, 4) developing a range of tools, particularly models, that encapsulate best process understanding at a wide range of scales, 5) testing these models and indicators in a wide variety of field locations across Europe (~10) encompassing major culture species and technologies, and covering a wide spectrum of environment types, selected according to criteria developed during the project, and 6) using this data to test and select the final "toolpack" of models and indicators, including appropriate decision support tools to guide users to effective implementation. National annual meetings with stakeholders will be held to allow 2-way interaction ensuring the practical relevance of the work and that the user community achieves ownership of the project's outputs. We will organise a final international conference and workshop where the "toolpack" of indicators and tools for effective environmental impact assessment and site selection will be demonstrated.