SUSTAINABLE-YIELD INDICATORS FROM BIOMASS - ARE THERE APPROPRIATE REFERENCE POINTS FOR USE IN TROPICAL FISHERIES

Various methods have been proposed to calculate maximum sustainable yi eld, MSY, from biomass estimates, but the classical approach of Gullan d, MSY = 0.5 M B-0 is still widely used, despite overwhelming theoreti cal and practical evidence pointing to its limited value, probably due to confusion as to the alternative methods available. A review of alt ernative 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 sy stem based on precautionary reference points. We also focus on problem s of estimating MSY and other reference points, review alternative est imators and discuss some of the ecological and life history criteria t hat affect how these estimators should be used: as targets or limits f or exploitation, as indicators of conformity under sustainable harvest ing conditions, or even for ecocertification of responsible or sustain able fisheries. (C) 1997 Elsevier Science B.V.