Trophodynamics of Nemipterus japonicus (Bloch, 1791) in the trawl landings along the north-east coast of India

Abstract

The trophodynamics of Nemipterus japonicus (Bloch, 1791) along the north-east coast of India was studied during 2012-2015 based on specimens collected from trawl landings at Digha, Paradeep (northern region), Visakhapatnam and Kakinada (southern region). Crustaceans were the preferred prey with index of relative importance (IRI) of 50% in the northern region and 42.4% in the southern region. Among crustaceans, Oratosquilla dominated in both the regions followed by crabs and several species of penaeids and nonpenaeids. Finfishes ranked next in importance (IRI% of 32.1 in northern region and 39.9 in southern region) and included Stolephorus spp., silverbellies, Coilia sp., other clupeids, Apogon spp., mackerel, sardines, eels, priacanthids, Bregmaceros sp. and sciaenids. Along northern region, in juveniles and preadults, the diet comprised chiefly of crustaceans (IRI% of 72.27 and 52.76), followed by finfishes (IRI% of 15.37 and 27.65). In the southern region, adult fishes exhibited higher preference for finfishes (IRI% of 47.5 to 62.8). Feeding intensity was low throughout the year with close to half (48.23% in northern region and 43.67% in southern region) of the fishes exhibiting empty or trace stomach conditions which increased with an increase in age and size of fish. High similarity of 75.54% in the northern and 84.19% in the southern region was recorded in the diet contents of smaller and moderate sized adults. Annual and seasonal mean similarity in the diet components between the regions was 69.9 and 53%. Prey contents in juveniles between both the regions exhibited a similarity of 59.5%, while preadults and adults recorded similarities of 62.7 and 68.2% respectively.