دراسة مجتمع أسماك نهر كرمة علي، شمال البصرة، العراق

Abstract EN

The fish assemblage of Garmat Ali River, north of Basrah, Iraq was described from November 2007 to October 2008.

A total 4913 fishes belonging to 26 species and 13 families, all belonging to Osteichthyes, were caught using gill net, cast net, electro-fisher, hook and lines.

Cyprinidae, the dominant family, was represented by eight species.

The number of species increased in summer and spring and sharply decreased in winter.

The species composition and abundance seem to be affected by the water temperature more than the salinity, pH and light penetration.

The fish assemblage in the river had a ten resident species, seven seasonal species and nine occasional species.

The fish fauna consisted of eleven native, nine marine and six alien species.

Liza abu was the most abundant species numerically and in weight comprising 39.3% and 28.1% respectively, followed by Carassius auratus (21.2%, 23.7%).

The third position in number was occupied with Poecillius sphenops (7.0%), but Silurus triostegus .in weight (22.1%).

The dominance value (D3) for the more three abundant species in number ( L.

abu, C.

auratus, P.

sphenops) was 67.5%, while in weight was 73.9% for L.

abu, C.

auratus and S.

triostegus.

L.

abu also occupied the first position in index of relative importance IRI% (37.8%), followed by C.

auratus (25.2%) and S.

triostegus (10.9%).

The numerical diversity index ranged form 1.26 in September to 2.2 in June, but the weight diversity index ranged between 1.18 in December and 1.72 in October.

Richness index ranged from 1.05 in December to 2.44 in July.

The numerical evenness index between 0.52 in August and 0.84 in June, but the weight evenness lay between 0.47 in August and 0.77 in October.

The highest similarity level of fish species was found between November and January depending on Jaccard similarity index.