Population dynamics of big-eye croaker Pennahia macrophthalmus and blotched croaker Nibea maculata (Pisces Perciformes Sciaenidae) in the trawling grounds off Rameswaram island, east coast of India

153-157Growth parameters of P. macrophthalmus and N. maculata were estimated. Estimated lengths on completion of I, II and III years were 173, 216 and 228 mm for P. macrophthalmus and 193, 253 and 273 mm for N. maculata. Total mortality rates (Z) ranged from 2.7 to 5.8 and from 3.35 to 5.91, while natural mortality (M) ranged from 1.84 to 2.38 and from 1.66 to 2.70, respectively for P. macrophthalmus and N. maculata. Length and age at first capture were 97 mm, 0.35 y and 124 mm, 0.48 y for the two species, which were less than the corresponding parameters at first maturity in both of them. Highest yield could be obtained when age at first capture was 0.45 in P. macrophthalmus and 0.60 in N. maculata