Eel populations have declined dramatically across Europe. Since 2000 eel stocks have been reported as outside safe biological limits and current fisheries as not sustainable. The European Commission has responded by introducing an Eel Recovery Plan. The Environment Agency is responsible for managing eel stocks in England, and for keeping track of whether measures to boost eel stocks are working. This report supports this role by providing a new, more realistic approach for modelling the life cycle and population dynamics of eels in our rivers.