Spatial and temporal distribution of commercially important fish species of Lake Tana, Ethiopia

• Autorzy: Goshu G. , Tewabe D. , Adugna B. T.
• Języki publikacji: EN

Abstrakty

EN

The distribution of Lake Tana fish species was studied from January 2000 to December 2003. Samples were collected monthly using gill-nets of 60, 80, 100, 120 and 140 mm stretched mesh size. Labeobarbus spp., Oreochromis niloticus, Claris gariepinus and Varicorhinus beso are commercially important fish species and form 77%, 13%, 9% and 1% of the pooled experimental fish catch. There was significant variability among years and sampling sites encompassing both temporal and spatial aspects. Population densities of Labeobarbus spp. and V. beso were significantly declining, in contrast, the abundance of O. niloticus and C. gariepinus did not change. The most likely explanations for the decline in Labeobarbus spp. are the increase of the commercial gill-net fishery targeting their spawning aggregations in the river mouths, use of poisonous plant materials and the increasing trend of the disconnectivity and channelisation of rivers. The results stress the need for urgent development of a management plan focusing on ensuring river connectivity, fishing effort and gear restrictions, and control in the river mouths and major tributaries during the breeding seasons.

Słowa kluczowe

EN

tropical lake; lake; species composition; Labeobarbus; Oreochromis niloticus; Clarias gariepinus; Varicorhinus beso; spatial distribution; temporal distribution; fish; Ethiopia; breeding season; fish collection; abundance; annual change

• Wydawca: -
• Czasopismo: International Journal of Ecohydrology and Hydrobiology
• Rocznik: 2010
• Tom: 10
• Numer: 2-4
• Opis fizyczny: p.231-240,fig.,ref.

Twórcy

autor

Goshu G.

• Bahir Dar University, College of Agriculture and Environmental Sciences, P.O.BOX 1701, Bahir Dar, Ethiopia

autor

Tewabe D.

autor

Adugna B. T.