Diet composition and feeding behavior of largehead hairtail Trichiurus lepturus Linnaeus 1758 along the Eastern Arabian Sea and Western Bay of Bengal

Information on diet composition and feeding habits of species is very much essential for the scientific planning to develop sustainable management plans. The feeding biology of Trichiurus lepturus was studied during 2014 to 2018 from 6167 and 3346 specimens collected on a weekly basis along Eastern Arabian Sea (EAS) and Western Bay of Bengal (WBB), respectively. Crustaceans mainly represented Acetes spp. (98.6 %) and were categorized as dominant and preferred (%QI = 51.35; %IRI = 53.31) food item; teleosts were categorized as dominant and secondary (%QI = 47.46; %IRI = 45.71) food items and molluscs as accidental and accessory food items of T. lepturrus based on the values of dietary coefficient and Index of Relative Importance along the Eastern Arabian Sea (EAS) while, teleosts were completely dominant (%QI = 99.61; %IRI = 99.27) with both molluscs (%QI = 0.34; %IRI = 0.56) and crustaceans (%QI = 0.01; %IRI = 0.17) forming accessory and accidental food items along the Western Bay of Bengal (WBB). The teleostean prey items belonging to 23 genera were encountered in the guts of T. lepturus from EAS with Stolephorus spp. (17.09 %), Sardinella longiceps (6.65 %), Decapterus spp. (5.75 %), Rastrelliger kanagurta (1.36 %), and Megalaspis cordyla (0.89 %) as major component; whereas, in WBB, 16 genera of teleosts representing Sardinella longiceps (50 %), Stolephorus spp. (31.52 %), Decapterus spp. (4.57 %), and Rastrelliger kanagurta (2.26 %) formed the major portion of diet by %IRI. Crustaceans were dominated by Acetes spp. (52.61% IRI) in EAS, while other crustaceans' contribution as prey item was negligible. However, along WBB, the crustaceans' contribution as food components was very minimal. Molluscs did not contribute much as dietary constituents of T. lepturus in both EAS and WBB. About 50.15 % and 56.83 % of the stomachs had food content in various proportions in EAS and WBB, respectively and rest of the stomachs were empty.