Maximum Sustainable Yield

Abstract

The concept of Maximum sustainable yield (MSY) has been used in fisheries science for about a century and is defined as the highest average catch that can be continuously taken from an exploited population (= a stock) under average environmental conditions. MSY is based on the ecological concept of sigmoid population growth toward the carrying capacity of the ecosystem for the respective species. The surplus in numbers and biomass produced for population growth can be caught sustainably and reaches a maximum (MSY) at intermediate population size. MSY can be determined from surplus production models, which require catch and effort or abundance (numbers or biomass) data, or from age-structured models, which in addition need information about somatic growth, maturation, selectivity, mortality rates, and recruitment. The MSY concept has been criticized for its simplified assumptions and considerable range of uncertainty, but more sophisticated data-demanding models, which take into account species interactions and environmental conditions, come with their own problems and uncertainties. As a result, the MSY framework remains the main management tool in most fisheries of the world, with fishing mortality and biomass reference points that correspond to MSYs.