Reproductive biology and feeding dynamics of the shrimp scad Alepes djedaba (Forsskal, 1775) from Ratnagiri, central west coast of India

The shrimp scad Alepes djedaba (Forsskal, 1775) belonging to family Carangidae is one of the important components of trawl bycatch landed at Ratnagiri, Maharashtra. Length-weight relationship, condition factor, morphometrics, feeding and reproductive biology of the species was investigated in the present study. Length-weight relationship indicated isometric growth in males, females and pooled individuals. All morphometric characters showed a moderate to high degree of correlation with total length. The qualitative and quantitative analysis of food revealed that A. djedaba is a carnivorous fish feeding mainly on Acetes spp., small fishes, copepods and shrimp larvae. The male:female sex ratio was found to be 1:0.85. Higher gonadosomatic index (GSI) values for females were observed during post-monsoon season. The ova diameter study indicated that A. djedaba follows a protracted spawning season with the individual spawning twice in a season. The absolute fecundity ranged from 15004 to 640800 eggs with an average of 309916 eggs. Length at sexual maturity for female fish was estimated to be 149 mm.