This volume includes 29 peer-reviewed papers presented at the Fifth Conference on Fish Telemetry held in Europe (Ustica, Italy, 9-13 June 2003). The papers cover a wide range of topics on the application of aquatic telemetry in the field of human impact, fishery management and aquaculture. Evaluations of the barriers’ effects on the migrations of both juvenile and adult fish are presented and discussed. New results on migratory patterns and habitat utilization are reported, elucidating behavioural ecology of several freshwater and marine species. Advances in methodology and new technology are also described and examined.