A comparison of management strategies for the rehabilitation of a fishery: Applied to the fishery for blacklip abalone Haliotis rubra in the Western Zone of Victoria (Australia)

Abstract

Three broad strategies for achieving rehabilitation were compared through simulation. The first was to control the yield at a reduced level. The second was direct reduction in the fishing effort. The third was to increase the size at first capture. Use was made of a mathematical model of the abalone fishery in the Western Zone of Victoria; incorporating variable recruitment and a stock-recruitment relationship. The strategies were compared on the basis of the probability of rehabilitation being achieved. The extent to which yield might be forgone, and the time required for rehabilitation were also examined. It was found that the use of a total allowable catch (TAC) can be an uncertain means of achieving rehabilitation. In the simulations, it required up to 30 years to achieve probabilities of rehabilitation of 95%, 75%, and 50% (when the TACs were set either at 280, 320, or 360 t, respectively). Probabilities approaching 100% were attained within five years from the equivalent (in the sense of the expected long-term outcome) reductions in fishing effort. Increasing the size at first capture gave similarly high probabilities of rehabilitation, other than from very low catch rates.