Feeding behaviour of greater amberjackSeriola dumerili(Risso, 1810) from Central Mediterranean (Gulf of Gabes, Tunisia)

Abstract

The diet of greater amberjackSeriola dumerili(Carangidae) in the Gulf of Gabes (Tunisia, Mediterranean) was described from analysis of stomach contents of 290 specimens fished between June 2004 and May 2006. The index of vacuity (%VI) was relatively low (37.9%) and differed significantly across size classes.Seriola dumeriliis an opportunistic predator that consumes mostly pelagic organisms; benthic prey were also examined in small proportion. The diet was quantified using the frequency of occurrence (%O), numerical abundance (%N), weight (%W) and the index of relative importance (IRI and %IRI) for each prey taxa. The most important prey were teleosts (%IRI = 99.61); molluscs and crustaceans were found occasionally (%IRI, 0.38 and 0.01%, respectively). Among teleosts, Clupeidae were also the dominant food items in number (%N = 36.06%) and then in frequency of occurrence (%O = 36.7%). In term of weight, Sparidae were the most abundant prey (%W = 36.5%). There is no significant difference between male and female diets. Seasonal differences in the diet components were observed.