the MFCMA are designed to ensure that catch is limited to the optimum yield. The optimum-yield concept has been criticized, however, for its failure to establish adequate usable guidelines for decision-making. To the extent that there has been explicit acceptance of the concept of optimum yield, it has frequently been used as an excuse for exceeding the maximum sustainable yield.⁴ Optimum yield is defined in MFCMA Section 3 (21) as “the amount of fish a) which will provide the greatest overall benefit to the Nation, with particular reference to food production and recreational opportunities; and b) which is prescribed as such on the basis of the maximum sustainable yield from such fishery, as modified by any relevant economic, social, or ecological factor.” Unfortunately, this definition is so broad that it can be used to justify almost any quantity of catch. Consequently, an “optimum yield” might easily conflict with conservation goals. The implementing regulations, known as the “ 602 guidelines,” do not provide the specification and guidance needed. It is clear that there are two often mutually exclusive issues involved in trying to achieve “optimum yield.” One issue is a concern for biological overexploitation of fishery resources; the second is a concern for attaining economic efficiency as moderated by social concerns.

Each council is required by law to assess and specify the maximum sustainable yield and the optimum yield in any fishery management plan under its jurisdiction. The optimum yield figure sets the upper limit of allowed harvest in each fishery, including both domestic and foreign fishing allowed in the EEZ. Typically, political and social pressures are exerted on councils; scientific uncertainty due to inadequate information and to a lack of consensus about what the data indicate weaken scientific input and lessen the weight given to the biological component; complexity of ecological systems makes achievement of optimal levels a trial-and-error process; and large natural variability often masks overexploitation until it is too late. Some councils are therefore taking the more conservative approach of setting “effective total harvest” levels (including directed catch and discards) and “overfishing” levels (developed from species-specific exploitation rates), which ensures that the spawning biomass will be adequate to produce populations near maximum sustainable yield, rather than managing directly for maximum sustainable yield. While a move in the right direction, this approach still fails to account for ecosystem requirements adequately.