Differences in the food of the young and the adult Indian mackerel, Rastrelliger kanagurta (Cuv.)

Abstract

The problem of the food of fishes with its varied bearings on their shoaling habits and migrations has engaged the attention of fishery biologists since the beginning of the present century. The mackerel is an important food fish in both hemispheres. Several contributions have been made to our knowledge of the food of the Indian mackerel, Rastrelliger kanagurta, which contributes to one of the largest fisheries of India. All these observations, except those of Chacko, which are from the Gulf of Manaar, are confined to the west coast of India. According to these workers, mackerel is a noted plankton feeder, securing its food by filtration. Chidambaram, while observing the adult mackerel as plankton feeder, suggested the carnivorous habits of the young mackerel. Later, in a detailed account on the food of this fish, Bhimachar and George observe that "the food of the young mackerel does not radically differ from that of the adult". Pradhan has arrived at a similar conclusion regarding the food of mackerel; but one will not fail to note from his observations that young mackerel less than 89 mm. in total length are not represented in his material.