Population Aspects of Fishes in Geba and Sor Rivers, White Nile System in Ethiopia, East Africa

Abstract

This study was carried out to assess the diversity, condition factor, length-weight relationship, and sex ratio of fishes in Geba and Sor Rivers located in Baro-Akobo Basin, White Nile system within Ethiopia. Fish samples were collected in one wet and one dry season. The length-weight relationships were fitted using power equation for the most abundant species. A total of 348 fish specimens were collected using gillnets and hooks. These were identified into eight species and oneGarrasp. representing seven genera and four families. Family Cyprinidae was the most dominant with six species (66.7%).Labeobarbus intermedius, Labeobarbus nedgia,and Labeo cylindricuswere the most abundant fish species, respectively, with 60.72%, 16.83%, and 14.66% index of relative importance (IRI). The diversity index was higher for Geba River (𝐻 𸀠 = 1.50) than for Sor River (𝐻 𸀠 = 1.10). All the three most abundant species had negative allometric growth. Seasonal variations in the mean Fulton condition factor (FCF) were statistically significant forL. cylindricus(𝑝 < 0.05). There was variation in the sex ratio with the females dominating in all the three most abundant species. Further investigation into the fish diversity, food, feeding, and reproductive behaviors of fish species especially in the tributaries of these rivers and their socioeconomic aspects is recommended.