Size distribution and growth of Metapenaeus dobsoni(Miers) and their effect on the trawler catches off Kerala

Metapenaeus dobsoni (Miers) spawns almost throughout the year. The traditional method of tracing the progression of modes in monthly length frequency distribution to determine growth and age was not very successful. The application of a modified Von Bertalanffy equation furnished expected sizes at different ages. The total instantaneous mortality rate was found out from the approximate formulae of Holt-Beverton. The size distribution of the catches landed by trawlers were obtained and the role played by the size distribution in influencing the catch and abundance has been discussed