Feeding habits and trophic level of round sardinella (Sardinella aurita) in the northeastern Mediterranean (Aegean Sea, Greece) ATHANASSIOS C. TSIKLIRAS1*, MICHELE TORRE2 and KONSTANTINOS I. STERGIOU1 1 Department of Zoology, School of Biology, Aristotle University of Thessaloniki, 541 24, Thessaloniki, Greece 2 Fisheries Research Institute, Nea Peramos, 640 07, Kavala, Greece Abstract Four seasonal samples of round sardinella, Sardinella aurita Valenciennes, 1847, were collected onboard the purse-seine fleet (October 2001-August 2002, 30 individuals per season) in the northern Aegean Sea. Samples were immediately fixed with 10% formaldehyde solution. The total length (TL, cm) was measured and prey items in the stomach contents were identified to large taxonomic groups. The vacuity index, the percentage gravimetric composition and the trophic level were estimated. The percentage of empty stomachs varied seasonally and among size classes. Crustaceans (copepods, amphipods, decapod larvae and other) were the main prey, followed by siphonophores, phytoplankton and fish larvae. The percentage gravimetric composition of the diet varied seasonally. Copepods were the most abundant prey item in the winter and spring, while decapod larvae and amphipods were most abundant in the summer and autumn, respectively. The trophic level ranged between 3.04 (winter) and 3.28 (spring), and increased asymptotically with size (Troph∞=3.31, K=0.018). Based on the composition of its diet, round sardinella may be characterized as an omnivorous fish with preference for animal prey. In addition, information on the diet composition of round sardinella in other areas of its distribution, was collected and trophic levels were calculated. They ranged between 2.05 in Senegalese waters and 3.33 in the waters surrounding the Canary islands. The between-area variations in trophic levels are discussed.   < back .