Trophic breadth and dietary overlap for ten fish species caught from Shatt Al-Arab River, Fao, southern Iraq


A total of 274 fishes of 10 species were caught since July 2010 to March 2011, using coastal seine net from Shatt Al-Arab River at Fao. The importance of food items in the diet of ten species were assessed by index of relative importance. Most fishes depend upon one or two main food items where the all fishes eat 15 food items of which seven were animal items, five of plant origin and three organic and non-organic detritus. Six species were considered as carnivores where animal ratios in their diets are 97.1, 89.1, 86.9, 81.5, 76.8 and 72.6 for Johnius belangerii, J. dussumieri, Thryssa whitheadi, Ilisha compressa, Sparidentex hasta and T. hamiltoni respectively. The Morisita indexes of feeding overlap showed only five significant overlap, three of them between J. dussumieri with I. compressa (0.869), T. whitheadi (0.866) and T. hamiltoni (0.675), while only two significant overlap were recorded between T. whitheadi with I. compressa (0.862) and T. hamiltoni (0.657). Five species were considered as high specialized feeders (P. klunzegeri, J. dussumieri, J. belangeri, T. whithead and I. compressa), four species were considered as low specialized feeders (P. subviridis, A. arabicus, T. hamiltoni and T. Ilisha), and S. hasta considered as generalized feeder.