Sustainable yield indicators from biomass: are there appropriate reference points for use in tropical fisheries?

Abstract

Various methods have been proposed to calculate maximum sustainable yield, MSY, from biomass estimates, but the classical approach of Gulland, MSY = 0.5 M B 0 is still widely used, despite overwhelming theoretical and practical evidence pointing to its limited value, probably due to confusion as to the alternative methods available. A review of alternative methods is presented and their applicability to species with high values of M discussed. An extreme-value strategy is proposed for introducing considerations of risk and precaution into a management system based on precautionary reference points. We also focus on problems of estimating MSY and other reference points, review alternative estimators and discuss some of the ecological and life history criteria that affect how these estimators should be used: as targets or limits for exploitation, as indicators of conformity under sustainable harvesting conditions, or even for ecocertification of responsible or sustainable fisheries.