Survey on fish diversity, resource potential and current production level ofmajor rivers in the Benishangul Gumuz Region; Ethiopia

Abstract

With an estimated total population of 667,049 people, the region is situated at the lower fresh water reaches of the Abay basin. The rivers mainly grouped as Flood Rivers, where there are extremes of annual fluctuation in water level from severe flood to sometimes complete desiccation in dry season. There exists also considerable difference in numbers of species inhabiting various river systems attributed to the size of the river as represented by its basin area or correlated with the length of main channel or stream order. Five major rivers of the basin were chosen purposely. Sampling was made during 2011 and gillnets of different mesh sizes were used. For the estimation of the potential fish yield of each river, the simplest model relating catch and river length was used. Compared to the other rivers, the diversity of fish in Dabus River was lower. Totally 29 commercially important fish species,grouped in to 11 families, has been known to present. The dominant family in these river systems is Cyprinidae with a diversity of 9 species. Current fish production in the region is estimated only as 183 tons/yr. The estimated total fish production potentials of sampled rivers is found to be 2,400 tons/yr indicating that there is the possibility to increase the current level of production more than 13 times. Inaddition, the exploitation is limited to subsistence level. The most potential river in the region is Abay with an estimated potential of 1680 tons/year and Anger contributes the least potential.