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

Abstract

The present work is to assess the fish structure and diversity status in the Tigris River, northeast of Basrah province from October 2015 to September 2016 in relation to some ecological factors. Three stations were selected; first station was located at the north of the east Qurna city in Al-Jewber village, the second station was located at a distance of 7 km after the first station in the Abu Aran village and the third station was in Qurna city. Water temperature, dissolved oxygen, salinity and total alkalinity were measured from the study areas. Several fishing methods were adopted to collect fishes, electric fishing and gill nets. Twenty- seven fish species were collected belonging to 25 genera and 12 families. A total of 9400 individual fishes were collected. Fishes were classified into three categories, common, seasonal and occasional species which 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 Margalef richness (D) were calculated according to months and stations. The mean value and standard 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 deviations of Evenness (E) in these stations were 0.695 ± 0.087, 0.741± 0.101 and 0.725± 0.101 in the same order. Mean values and standard deviations of Margalef richness (D) in these stations were 2.010 ± 0.898, 2.299 ± 0.851 and 2.893 ± 0.667, respectively. The dominance (D3) value of the main three abundant species was 59.24%.