Monitoring the incidence of escaped farmed Atlantic salmon, Salmo salar L., in rivers and fisheries of the United Kingdom and Ireland: current progress and recommendations for future programmes

An inevitable consequence of the development of the Atlantic salmon, Salmo salar L., farming industry in coastal waters of the British Isles has been the loss of farmed salmon to the wild, their occurrence in inshore waters and rivers, and their appearance in coastal and freshwater fisheries. Monitoring programmes have been developed throughout the British Isles, variously using scientific sampling, catch records from coastal or freshwater fisheries or both, and scientific sampling of catches from in-river traps. We compare the results of these monitoring programmes with regional production and the numbers of escapees reported from marine fish farms. We also consider the effectiveness of the programmes for assessing the prevalence of farmed salmon that escape from marine cages. Finally, we make recommendations for improvements to these programmes and for the development of best practice, including the scientific sampling of in-river spawning stocks through fishery-independent sources, identification of fish origin based on at least two methods, assessment of the degree of incorrect classification, and the timely and accurate reporting of all escapes.