Evaluation composition of fish assemblage in the southern part of the Tigris River, Iraq

Abstract

The habitats of the southern part of the Tigris River in the north of Basrah province are going through impairment due to habitat modification and foundation of barriers, dams, and other human modifications in the last decades. The composition of assemblage of fishes in the southern river part was assessed from January to December 2018. A total of 8995 fish are affiliated to bony fishes included 13 families, 23 genera, and 26 fish species. The exotic fish species were nine; native species were twelve with five marine species. The small size Abu mullet Planiliza abu native species the highest abundant species in the study area formed 26.96% of the overall species number, and the Blue tilapia Oreochromis aureus formed 20.08% of overall collected fishes. Prussian carp Carassius gibelio included 19.86% of the total caught. The rate of diversity index in the study area assessed as poor fluctuated from 1.83 to 1.94. Values of richness index pointed as disturbed, varied from 1.83 to 2.84, rates of evenness index differ from 0.77 to 0.78 and expressed it as balanced. The occurrence of species in present study recoded twelve native fish species formed 94.89% of the total caught, and five seasonal fish species formed 3.76% of the total number of species and eight occasional fish species represented 1.35% of the total catch. The current study affirms the non-attendance or scarceness of some important native species that constituted the core building structure of the historical fish community as a result of anthropogenic activates caused habitat degradations and increased beta diversity.