Exploitation of perch fishery resource off Tuticorin by small mechanised trawlers with an account on the biology of Scolopsis bimaculatus Ruppell

Abstract

Annual average perch production was 2541.2 tonnes at the catch rate of 88.8 kg/unit by average effort of 28612 units of small mechanised trawlers measuring 14 m and below. Peak periods of perch fishery were during June-September and a minor peak during December-February. Inspite of the comparative decline in the catch rate of perch, there is a scope for further increase in perch production provided the effort is increased. The age and growth of Scolopsis bimaculatus is described by the von Bertalanffy growth equation i.e. \ = 322 (1-e ''"''* (tto.oois)) This species attains a size of 163.6, 243.9, 283.5 and 303.0 mm in 0.5, 1.0, 1.5 and 2.0 years. Length - weight relationship of this species is defined by the equation Log W = -5.6848 + 3.3699 Log L and the Woo is 584 g. The natural mortality coefBcient (M) is estimated to be 2.2, the total mortality coefficient (Z) is 3.2 and the fishing mortality rate (F) is 1.0. Yield per recruit of this species indicates that for the prevailing M/K ratio 1.56 and age at first capture 0.4353 the F^^^ which can produce the Y^^^ of 52.3 g is 4.5 and suggests that the fishing effort may be increased further from the present level to enhance the yield of this species as in the case of L. nebulosus and N. delagoae. The fish is a carnivore feeding on fishes, amphipods, Squilla spp., brittle stars, prawns, cuttlefish, polychaetes and molluscs.