Diversity of fishes in the lower reaches of Tigris River, north east of Basrah province, Southern Iraq

The present work is to assess the fish structure and diversity status in theTigris River, northeast of Basrah province from October 2015 to September 2016 inrelation to some ecological factors. Three stations were selected; first station waslocated at the north of the east Qurna city in Al-Jewber village, the second station waslocated at a distance of 7 km after the first station in the Abu Aran village and the thirdstation was in Qurna city. Water temperature, dissolved oxygen, salinity and totalalkalinity were measured from the study areas. Several fishing methods were adopted tocollect fishes, electric fishing and gill nets. Twenty- seven fish species were collectedbelonging to 25 genera and 12 families. A total of 9400 individual fishes were collected.Fishes were classified into three categories, common, seasonal and occasional specieswhich were formed 98.04, 1.08 and 0. 88%, respectively of the total number of species.The value of the Shannon and Weaver diversity index (H), Evenness (E) and Margalefrichness (D) were calculated according to months and stations. The mean value andstandard deviations of Shannon and Weaver in the three stations were 1.53 ± 0.499,1.841± 0.259 and 2.432± 0.767 respectively. The average value and standard deviationsof Evenness (E) in these stations were 0.695 ± 0.087, 0.741± 0.101 and 0.725± 0.101 inthe same order. Mean values and standard deviations of Margalef richness (D) in thesestations were 2.010 ± 0.898, 2.299 ± 0.851 and 2.893 ± 0.667, respectively. Thedominance (D3) value of the main three abundant species was 59.24%.