Impacts of maximum sustainable yield policy to prey–predator systems

Abstract

This article investigates the effects of reaching the maximum sustainable yield (MSY) in prey–predator systems where the prey population follows logistic law of growth. Two different models are proposed: (i) first model involves linear prey–predator interaction and intraspecific competition among predator populations, and (ii) the second one is a ratio-dependent prey–predator system. In the first model, our results suggest that the introduction of intraspecific competition among predator population has important consequences for the fishing to reach MSY from prey species and maximum sustainable total yield (MSTY) for combined harvesting of both prey and predator species. On the otherhand, in the second model, our results suggest that though the harvesting of prey species at MSY level shall be guaranteed the coexistence of both the species, but the combined harvesting of both the species at MSTY level may cause extinction of the predator species. However, for both the models, predator harvesting at MSY level may be a sustainable fishing policy. Therefore, based on our results we can conclude that MSY (or MSTY) policy in prey–predator systems in nature are not likely to fit requirements of Conservation of Biological Diversity (CBD, 1992) in all cases.