Biology of the cleftbelly trevally Atropus atropos (Bloch and Schneider, 1801) from Ratnagiri coast of India

The cleftbelly trevally Atropus atropos (Bloch and Schneider, 1801) is one of the important carangid species landed mostly as trawl bycatch along Ratnagiri coast. Investigations were carried out on A. atropos with respect to length-weight relationship, condition factor, morphometrics, feeding and reproductive biology. The length-weight relationship indicated negative allometric growth in A. atropos. Morphometric measurements showed significant correlation with total length. The gut content analysis revealed A. atropos to be a carnivore fish feeding mainly on Acetes spp., small teleostean fishes, cephalopods, and squilla. Sex ratio showed dominance of males. Gonadosomatic index and maturity studies indicated that A. atropos has a protracted spawning season extending from May to December. Length at sexual maturity for females was estimated to be 171 mm. Fecundity ranged from 16458 to 138688 eggs with an average of 70097 eggs. Ova diameter studies showed that A. atropos spawns twice in a protracted spawning season.