Coral reef fisheries stock assessment

Abstract

Although all fisheries are multispecies and spatially heterogeneous, coral reef fisheries are an extreme in both respects. The two main approaches to stock assessment have been either to consider individual species separately or to lump all species together. Both are limited in their predictive power. The lack of ecological knowledge and the large number of parameters required make methods based on single species often impractical or expensive. However, where the appropriate information is available, ecological studies do not provide significant improvements on yield-per-recruit or surplus yield models currently used. Alternative community models based on aggregates of species lack predictive power, empirical support and relative data. Models are further limited because they do not address various economic aspects, fish movement and recruitment, all of which must be spatially resolved. However, the ECOPATH model, based on trophic compartments, represents a new approach useful to multispecies assessment, and the only way at present to include predation in stock models. In practice the data available will be the most important factor in the choice of stock assessment model. The major concern for management of many coral reefs is conservation of the habitat and stocks. In some cases this has been achieved with little reference to stock assessment, by using community management and closed areas, which are receiving increasing support. However, once the objective of conservation is achieved, stock assessment should have an important role in improving the economic performance of the fisheries. The wider problems of management have no simple solutions, but managers should look to adaptive management, designing their own experiments to choose between management models.