Traditional methods of allocating the catch among sectors in a fishery are often imprecise, based on vague criteria and insecure. Recent developments in fishing rights, notably individual quotas, have focused attention on these weaknesses and created new pressures for ways to adjust sectoral allocations without undermining the security of established fishers’ rights.The growing and largely favorable experience with individual quotas suggests that market-based mechanisms can be advantageously employed to allocate catch shares among sectors as well. Providing for such mechanisms is most challenging where individual quotas are not employed and sectoral shares are not well defined. Examples of trade in fishing rights across sectors are few but increasing, and can be expected to enhance the benefits of individual quotas. Most important, clearly defined and secure sectoral shares will strengthen the incentives of fishers in all sectors to cooperate in managing their fisheries. To take full responsibility, however, holders of fishing rights must have the means to bargain with fishers in interdependent fisheries, in order to realize maximum benefit from whole marine ecosystems.