| Abstract |
Analysis of diet composition and feeding intensity of the brown meager (Sciaena umbra, Linnaeus, 1758) was realised seasonally and according to the fish size in the Central Mediterranean sea (Gulf of Tunis). Specimens were collected, monthly from October 2008 to September 2011 from the landings of the small-scale fisheries. In all, 272 stomachs of brown meagre measuring between 15.3 and 49.2cm total length (TL) were examined. The prey items identified in stomachs belong to six groups: Crustacea (Decapoda, Amphipoda, Isopoda, Mysidacea, Stomatopoda…), Annelida, Mollusca, Teleostei, Angiosperma and Algae. 118 stomachs were empty (43.4%). This percentage varied throughout the year. The lowest feeding intensity was recorded in summer during spawning period (June – August), feeding activity increased in October and November. Coefficient of vacuity is lower for individuals smaller than 25 cm. The Index of Relative Importance (IRI) was calculated to measure the trophic preference. According to this index, crustaceans were the main preys (%IRI = 99%), in both the small and large size classes, whereas other prey groups had minor importance. Among the crustaceans, the most important taxon identified was decapods, which was present in 96% of stomachs and represented 92% of total prey weight. The others most categories of crustaceans were amphipods and isopods which occurred in 25% and in 23% respectively. Diet composition showed little seasonal variation, decapods were the most important prey in all season. Cannibalism has not been observed for this species. The brown meagre is an opportunistic predator, stomach contents were dominated by the benthic organisms. |
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