Study on biology of Thryssa dussumieri (Valenciennes, 1848) from the coast of Ratnagiri, Maharashtra, India

Abstract

The Dussumier’s thryssa, Thryssa dussumieri is one of the important component of by-catch of trawl and mini purse seine landings at Ratnagiri. The length-weight relationship indicated the isometric growth in T. dussumieri with generalized equation W = 0.0066 L ^3.1077. The month-wise relative condition factor showed two peaks coinciding with peak spawning season. All morphometric lengths showed varying degree of correlation with total length. The qualitative and quantitative analysis of food revealed Thryssa dussumieri to be a carnivore, feeding mainly on mysids, copepods, diatoms and juvenile shrimps.The highest GSI value, for females, was observed during March, October, December and January. The male:female ratio was found to be 1:1.4. T. dussumieri has got a prolonged spawning season extending from September to April. The absolute fecundity ranged from 3367 to 14130 eggs with an average of 7420 eggs. Length at sexual maturity has been estimated to be 12.8 cm.