Spatiotemporal Variability of Fish Assemblage in the Shatt Al-Arab River, Iraq

Abstract

Spatial and temporal variability of fish assemblage in the Shatt Al-Arab River was studied from December 2011 to November 2012. Water temperature, salinity, dissolved oxygen and transparency were measured from three sites in the river. Several fishing methods were adopted to collect fish including gill nets, cast net, electro-fishing and hook and lines. The results showed that the fish assemblage consisted of 58 species representing 46 genera and 27 families belong to Osteichthyes except one (Carcharhinus leucas) relate to Chondrichthyes. Number of species increased in summer and autumn months and sharply decreased in winter. Tenualosa ilisha was the most abundant species comprising 27.4% of the catch, followed by Carassius auratus (23.7%) and Liza klunzingeri (10.6%). The dominance (D3) value for the main three abundant species was 61.7%. Nine species were caught for the first times from the river include eight marine. The overall values of diversity index ranged from ranged from 0.67 in March to 2.57 in October, richness index from 2.64 in January to 3.71 in September and evenness index from 0.22 in March to 0.73 in August. Associations between the distribution of fish species and the environmental variables were quantified by using canonical correspondence analysis (CCA).