Food and feeding habits of Indian mackerel (Rastrelliger kanagurta) in the southern part of Qeshm Island, Persian Gulf

Abstract

The study investigated the stomach content of Indian Mackerel (Rastrelliger kanagurta) from the southern part of the Qeshm Island in the Persian Gulf from April 2016 to March 2017. The food and feeding behavior of R. kanagurta with a fork length of 17.8 to 22.5 was studied from the gut contents. The frequency of occurrence and numeric methods was used for stomach content analysis. R. kanagurta fed on Diatom, Dinoflagellate, Crustacean, Molluscs, Forams and Ciliate. Plant origin organisms including Diatom (Bacillariophyceae) and Dinoflagellate (Dinophyceae) forming the main food items constituting about 72% of food items by number and 66.67% by the occurrence. Amongst the plant origin organisms, Coscinodiscus sp. was the most diverse food item, constituting 46.92% by number and 12.88% by occurrence, followed by Guinardia sp. which constituted 9.74% and 7.58% by number and occurrence, respectively. Among zooplankton, Crustacean was the dominant food item contributing to 19.58% of the food items by number and 24.61% by the occurrence. Amongst the Crustacean, Copepoda was the major food item constituting 7.57% by occurrence and 5.72% by number. Gastro-Somatic Index (GaSI) indicated the highest level in the autumn and lowest in winter that is before and after spawning season. The stomach emptiness index was 36.15% indicates the comparatively gluttonous of the fish. Overall R. kanagurta in the southern part of the Qeshm Island in the Persian Gulf is planktonivorous and feed on a wide range of planktonic organisms.