Limits to sustainable fish catch: the case of marine fishery in Kerala

ABSTRACT This study aims to examine the interannual variation in fish biomass and to estimate the maximum sustainable yield (MSY) for the marine fisheries of Kerala, India. Although the productivity of a fishery is known to be dependent on species diversity, this relationship is not widely documented. This paper uses an extended Gordon–Schaefer model that is modified to incorporate species diversity to estimate the MSY levels of catch and the corresponding fishing effort. Species diversity is expressed as both biological and bioeconomic diversity using the Simpson index. The model reports that the actual fishing effort has exceeded the maximum level necessary to support sustainable yield, while the maximum level of catch for maintaining sustainable yield is not known. A comparison of fish landings and effort data across different fishing techniques indicates that there is a potential to decrease the current level of fishing effort without experiencing a significant decline in fish catch.