بيئة و تركيبة الأسماك في الجزء الجنوبي من نهر الفرات

A bio-ecological study was accomplished, from November 2013 to April 2014, at Al-Mudayna district north-west of Basrah following construction the barrier at the Euphrates River. The study aimed to investigate the environment and the diversity of fish in the southern part of the Euphrates River. To collect samples two fishing methods were used, namely electro-fishing and benthic cast net. A total of 6013 fish specimens were collected during the study period, belong to 24 species and representing nine families, dominated by cyprinids and accounting for 12 species. Each of the mullet (Mugilidae), tilapia (cichlidae) and the mosquito (Poecillidae) families were represented by two species, while the other families, Siluridae, Sparidae, Mastacembelidae, Hemiramphidae and Engraulidae were represented by one species only. Four marine fish species (Liza subviridis, Acanthopagrus latus, Hyporhaunpus limpatus and Thryssa whiteheadi) were recorded from the location. Khishni (Liza abu) was prevailed fish community numerically contributing for 34.19% and Tilapia zilli occupied the second position (22.72%), followed by Alburnus mossulensis (14.22%). However, contribution of tilapia Oreochromis aureus (9.88%), Himri Barbus luteus (4.92%) and the common carp Cyprinus carpio (0.15%) was somewhat low. The lowest numerical diversity rate (H) was encountered in December 2013 (1.508) and the highest (1,694) in January 2014. The minimum rate for the evenness index (J) 0.667 encountered in November 2013 and the highest (0.849) in January 2014 .The lowest richness (D) value was (1.257) in January and the highest (1.695) in March. The study also investigated some abiotic environmental characteristics and their relation to the composition of fish community.