The escape of fish from sea-cage aquaculture is perceived as a serious threat to natural biodiversity in Europe's marine waters. Escaped fish may cause undesirable genetic effects in native populations through interbreeding, and ecological effects through predation, competition and the transfer of diseases to wild fish. Technical and operational failures of fish farming technology cause escapes. Cages break down in storms, wear and tear of the netting causes holes, and operational accidents lead to spills of fish. Sea-cage equipment is marketed and used across Europe, thus knowledge relevant to the culture of numerous species in diverse environments is required to produce robust equipment and implement risk adverse operations. The Prevent Escape project will conduct and integrate biological and technological research on a pan-European scale to improve recommendations and guidelines for aquaculture technologies and operational strategies that reduce escape events. Through research focused on sea-cages and their immediate surrounds, we will assess technical and operational causes of escape incidents, assess the extent of escapes of reproductive gametes and fish, determine the inherent behaviours that pre-dispose certain species of fish towards a higher probability of escaping, and document the dispersal of escapees to develop and test recapture strategies. Information from these components of the project will feed into research specifically aimed at benchmarking the performance of equipment under farming conditions and thereby improving operations and equipment production, and advancing national and international standards for the design, construction and use of aquaculture equipment. These key pieces of information, when added to existing knowledge, will allow determination of practical, implementable measures to prevent escapes and mitigate the effects of escapees. If prevention and mitigation are more successful, genetic and ecological impacts should diminish.