Large, disconnected waterbodies such as drinking water reservoirs hold significant stocks of European eel, but rarely can these populations escape these water bodies to undertake their seaward spawning migration. As part of this project HR2 technology is being used to determine the distribution, 3D movement patterns and residency characteristics of adult eels within a large reservoir. Eel data will be analysed in relation to concurrent environmental and physiological data to quantify the relative influence of these factors on eel movement, and used to develop predictive models to enable forecasting of eel movement and behaviour under a range of management scenarios.