RELATIONSHIPS BETWEEN COMMON BIOLOGICAL REFERENCE POINTS USED AS THRESHOLDS AND TARGETS OF FISHERIES MANAGEMENT STRATEGIES

Relationships between various biological reference points (BRPs) used to define thresholds and targets of fisheries management strategies we re examined for a range of combinations of life history characteristic s. Rank orderings of the selected BRPs were strongly influenced by the degree of density dependence in the underlying spawning-recruitment ( S-R) relationship. The validity of F0.1, F(max), F20% (the fishing mor tality at which spawning per recruit is 20% of the maximum), and other reference fishing mortality rates as approximations to F(msy) or as t hresholds of overfishing is highly dependent on life history character istics, particulary the degree of density dependence in the S-R relati onship. It is recommended that F40% be adopted as a target fishing mor tality rate when the S-R relationship is unknown and that threshold le vels of biomass be related to the estimated or assumed degree of densi ty dependence in the S-R relationship. Two new methods of calculating threshold biomass levels are suggested as alternatives to the familiar 20% B0 rule.