Food and feeding habits of the Indian scad, Decapterus russelli (Ruppell, 1830) from Mumbai waters, north-west coast of India

摘要

The principal diet of the Indian scad Decapterus russelli comprises crustaceans and fishes with Acetes indicus being the most dominant food item with a preponderence value of 64.66. The second most dominant food item was fishes (12.8) which comprised of Lactarius lactarius, silverbellies, myctophids, Nemipterus spp, Saurida tumbil, Boleophthalamus sp., Polynemus Bregmaceros mcclellandi, Polynemus heptadactylus, Cynoglossus spp., Trichiurus lepturus, Stolephorus spp. and eels. Penaeid prawns, cephalopods, crabs and plankton were encountered in few occasions. Variety in food composition signifies adaptive behavior of the species. The juveniles feed on A. indicus and sometimes on plankton, whereas the adult feeds on large quantities of A. indicus and teleosts. Fish component entered the diet when the species was 100 - 109 mm in size. The fish component was found to increase with the increase in size of fish, with A. indict's still being the preferred food item as it was found in large quantities even in the higher length groups. The percentage of males and females showing low feeding intensity was higher during all the months except in January for females. It was seen that feeding intensity gradually increases as the fish increases in size indicating that as the fish continues to grow it eventually becomes a more active predator. No seasonal variation was observed in feeding intensity of D. russelli.