Further Information on Sustained Yields from Fluctuating Environments

Abstract

The conclusions of Ricker (1958) are confirmed in series of 200 generations in which environment effects are simulated. The best constant rate of exploitation is very close to the maximum equilibrium rate when there is no environmental variation. A higher catch is obtained when an optimum portion of the stock is reserved for escapement and the remainder is harvested up to the level of the maximum equilibrium rate. Still higher catches are associated with reserving an optimum portion of the catch for escapement and harvesting all of the remainder. In general, these kinds of benefits are greatest at higher levels of environmental variability.