Some aspects of the biology and population dynamics of Amblygaster sirm (Walbaum) from the west coast of Sri Lanka

Abstract

The spawning of Amblygaster s i m was found to occur twice a year in April / May and August / September. The growth rate and the asymptotic length were fohnd t o be 2.1 (annually) and 24.4 cm respectively. Growth pattern determined from length frequency distribution, corresponded with the spawning season. Natural mortality coefficient was estimated as 2.54. The sex ratio indicated that more females than males were abundant in the catches. A t present &out 75-85% of the maximum yield is being obtained. The yield per recruit can be increased by increasing the fishing intensity. However, an increase in fishing intensity could lead t o a reduction in the spawning stock below the level where the recruitment could be affected.