Littérature scientifique sur le sujet « Silverbellies »

AbstractMarine capture of Sphyraena putnamae along western Bay of Bengal has been increasing. Owing to scarcity of information available on feeding dynamics globally, the present study was conducted using 763 individuals captured during 2017–19, to decipher trophic ecology and relationships. Of the individuals analysed, 54.8% had their stomachs either empty or with trace amounts of food, 27.3% had part-full stomachs and 18.0% had full stomachs. Stomach vacuity and fullness as well as predator–prey weight ratio varied with increase in body size, implying higher feeding intensity in large-sized fishes. Feeding activity was highest during July–November and lowest during March–April. The species is an opportunistic piscivorous pelagic predator that feeds on teleosts (>85%) and cephalopods. Sardines were the major prey, followed by whitebait, squid, bigeye scad, Indian scad, silverbellies and Indian mackerel. Diet contents were similar between sexes (82.17%); however, it varied among seasons (56.86–69.85%). Shifts in prey preferences from sardines, squid and bigeye scad to ribbonfish, shad, grunter, Indian mackerel, horse mackerel and Acetes were observed with increase in fish size, and diet varied between individuals sized <60.0 and >60.0 cm. Trophic level value was 3.51 ± 0.13 and Levin's Standardized Niche Breadth Index was 0.21. Dietary niche breadth varied across seasons and sizes, with higher values during summer and winter (0.36–0.41) and in fish measuring >45.0 cm (0.50–0.68), which implies generalized feeding behaviour. The present study represents the first detailed report on the diet of S. putnamae and will provide a substantial contribution to stock management through understanding of trophic interactions.

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.