Diet composition and variation in four commonly landed and threatened shark species in Maharashtra, India

The diets of Carcharhinus limbatus, Scoliodon laticaudus, Chiloscyllium arabicum and Ch. Griesum from the west coast of India were investigated. We compared trophic resource use and overlap across and within benthic and pelagic habitat guilds, between the two sympatric species belonging to family Hemiscyliidae, and between the life stages of S. laticaudus. It was observed that there was a significant difference in the diet composition of benthic and pelagic shark species. There was no difference in the diet of the two sympatric Chiloscyllium species. S. laticaudus showed an ontogenetic dietary niche shift from an invertebrate-rich to an ichthyophagous diet. Specifically, C. limbatus showed an ichthyophagous diet while S. laticaudus showed a diet consisting of both benthic and pelagic prey. C. arabicum, C. griesum, and S. laticaudus were less dependent on teleosts and displayed similar diet composition. The study also found that several of the prey species were commercially important fish species caught in the fisheries of Malvan. Thus a change in the relative abundance of either prey or predators due to fishing pressure could influence coastal food webs, leading to impacts both on ecosystems and fisheries.