Most fish and whale stocks are scarce common properties: access to exploitation is open to many users, which generates individual incentives that can prove collectively disruptive. Institutions for managing fisheries and whaling aim at avoiding such ‘tragedy of the commons’ by building scientific knowledge, placing regulatory constraints on harvesting operations, and altering incentives to better align behaviour to regulatory commitments. Important practices and principles of environmental governance, including treaty-based cooperation, inclusive decision making, and knowledge-based management emerged in the fisheries and whaling sectors. International attempts to regulate fisheries and whaling hinge on national management systems that vary considerably in structure and effectiveness, typically mixing four types of policy instruments: technical measures like minimum mesh-size rules; input controls such as permit requirements; output controls like vessel- or group quotas; and economic measures like tax exemption rules and subsidies. Advances are notable on the behavioural aspect of management in that regional resource regimes have developed innovative means for combating illegal, unreported or unregulated fisheries, typically centred on trade restrictions as part a broader menu of port-state controls.