Regional fisheries management organisations (RFMOs) have adopted a range of measures aimed at promoting compliance with the conservation and management measures they adopt and at deterring IUU fishing. However, enforcement of those measures continues to be problematic. This article reviews current compliance and enforcement measures, and discusses their shortcomings. It then examines the legal basis for the adoption by RFMOs of an expanded range of measures aimed at strengthening their enforcement capability and provides practical suggestions as to the possible content of those new measures. Particular attention is paid to the modus operandi of international co-operation and the emerging practice of non-flag state enforcement.