Insights into the Food and Feeding Habits of the Indian Mackerel (Rastrelliger kanagurta) from the Coast of Goa

Abstract

The Indian Mackerel is a commercially important fish species and India contributes to world’s 90% of mackerel production. The present study deals with gut content analysis of the Indian Mackerel Rastrelliger kanagurta to determine the type of feed and the feeding habitat. The gonado-somatic index and gastro-somatic indices were determined to find out the spawning period and maturity of the fishes. The stomach emptiness was also calculated to estimate the fish appetite from the stomach content. The present study indicated that Diatoms formed the predominant planktonic feed followed by Dinoflagellates. A total of 25 different types of planktons were found to be preferred by Rastrelliger kanagurta. The gut content also revealed sand particles, fish scales and cnidarian spicules. Highest mean GSI and lowest GaSI were observed in the month of April. The stomach emptiness index revealed gluttonous feeding from November to March and comparatively gluttonous feeding in the month of April. From the present study it can be concluded that Rastrelliger kanagurta, though shows preference for diatoms (40.74%) and dinoflagellates (22.22%), the dietary preference is not limited to it, but they also exhibited preference for Crustaceans (except copepods) (14.81%), Cyanobacteria (7.40%), Copepods (7.40%), molluscs (3.70%) and Protists (3.70%). The present study analysed the food constituents and feeding habitat of the Indian mackerel through gut content analysis. The intensity of feeding was also compared to the size of the fishes, reproductive maturity and the spawning time.