Diet composition and variations of the striped seabream Lithognathus mormyrus (Teleostei: Sparidae) in Eastern coast of Algeria

The diet of the striped seabream Lithognathus mormyrus (Linnaeus, 1758) was investigated in the Gulf of Annaba (Eastern coast of Algeria). A total of 522 individuals (8.1 < TL < 35.5 cm, 5.59 < TW < 499.44 g) was examined from January 2007 to December 2009. The relative importance index (% IRI) combining the three main descriptors of the presence of different ingested preys (%F, %N, %W) was used to characterize the relative importance of different food taxa. Feeding strategy and food habits are determinate. Qualitative and quantitative variations in diet were studied according to seasons, size and sex. The average annual digestive vacuity is 19.92%. Differences observed between seasons were not significant (χY = 6.882; p = 0.075). Lithognathus mormyrus is a benthopelagic and carnivorous fish. The main diet items are in order of importance: Mollusca, Chordata, Foraminifera, Annelida, Arthropoda, Echinodermata, Macrophyta and Cnidaria. A total of 7927 preys were identified to a total weight of 91 g, which represents an average number and weight per individual of 19 preys and 0.21 g respectively. Molluscs are the dominant prey whatever the season, size and sex. Despite the dominance of malacological ingested preys, statistical analysis revealed changes in diet between winter and autumn, and between small and large individuals.