Diversity, Relative Abundance and Biology of Fishes in Some Rivers, and Cestode Parasites of African Catfish (Clarias Gariepinus ) in Some Lakes of Ethiopia

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Addis Ababa University


Diversity, relative abundance and biology of fish species of Beshilo, Ardi and Dura Rivers were studied in November 2005, March and May 2006. Conductivity and dissolved oxygen showed significant variations among rivers (P < 0.05). The highest conductivity (415 μ.sm.cm-1) was observed in Beshilo River (BS1). The lowest conductivity (66.90 μ.sm.cm-1) was recorded in Ardi River (A 2). The lowest (4.04 mgl-1) and the highest (7.03 mgl-1) dissolved oxygen measurements were observed in Ardi River (A2). Fishes were sampled using gill nets of 6,8,10, 12 and 14 cm stretched mesh sizes, hooks and lines and monofilaments. Fish identification was done to species level by comparing the samples meristic and morphometric characters with taxonomic keys found in the literature and deposited specimens. Shannon diversity index and an index of relative importance (IRI) were computed to evaluate diversity and relative abundance of fish species, respectively. A total of 1060 fish specimens belonging to three orders, five families, ten genera and seventeen species were identified in Beshilo, Ardi and Dura Rivers. A higher number of species was recorded in Beshilo River (13 species) than Ardi (7 species) and Dura (5 species) Rivers. The diversity index was higher in Beshilo River (H’ = 1.65) than Ardi (H’ = 1.59) and Dura (H’ = 1.12) Rivers. Cyprinids were the most dominant fish species in all studied Rivers. The Cyprinids Labeobarbus intermedius, Varicorhinus beso, and Labeobarbus nedgia were the most important fish species in the total catch. Labeobarbus intermedius, Varicorhinus beso, and Labeobarbus nedgia of Beshilo River had isometric growth while Varicorhinus beso exhibited positive allometric growth in Ardi and Dura Rivers. Both sexes of Varicorhinus beso and Labeobarbus intermedius in Beshilo River were in better condition while females of Labeobarbus intermedius were relatively in better condition than males. Female to male sex ratio was 1:1 in combined catches with slight difference in Varicorhinus beso. But, females out number males in dry season while males show preponderance in wet season. Absolute fecundity increased as fish size increased. The L 50 calculated for some fish species would help setting minimum mesh size for management in the riverine fishery development. Key words / phrases/: Ardi, Beshilo, Dura, Relative abundance, Rivers, Relative



Ardi, Beshilo, Dura, Relative abundance, Rivers, Relative importance (IRI), Species