Optimal Annual Changes in Harvests from Multicohort Fish Stocks: The Case of Western Mackerel

An optimising model is developed to determine the .sequence of total allowable catches of western mackerel which would result in the maximum present value of the stream of annual rents. It is found that the optimal steady state fishing mortality would be one half to one third of recent levels. For the base formulation of the model the optimal plan calls for periodic fishing, witha moratorium on fishing for the first two years, and for a very substantial catchin the third year. The sensitivity of pulse fishing as an optimal strategy is testedwith respect to number of solution iterations, asymmetric charges for increasingfleet capacity, quadratic adjustment costs, harvesting stock effects, the rate of discount, and the price elasticity of demand for mackerel.