Assessment of motorized commercial gillnet fishery of the three commercially important fishes in Lake Tana, Ethiopia
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This study was conducted from July 2010 to June 2011 to assess the status of motorized commercial gillnet fishery of the three commercially most important fishes in Lake TanaLabeobarbusspp., Oreochromisniloticus(Nile tilapia) and Clariasgariepinus (African catfish). Catches were monitored daily and additional information on number of gillnets used, mesh size of gill nets and location of fishing grounds were collected. Data on the Labeobarbus species composition were collected 3 days per month. The total fish yield from the main fishing grounds of the commercial fishery was 238 metric tons/year. The catch of tilapia was 71%, that of catfish 18% and that of Labeobarbus 11% of the total catch. Peak production was from March - May 2011. Most effort (80%) was allocated to the North Eastern Floodplain (NEFP). The total number of gillnets set and boat trips made were 85,943 and 3104, respectively, which is much higher than reported previously. Consequently, the Catch per Unit effort (CpUE; kg/trip) of the 2010/2011 production year was with 64.7 ± 3 (95% CL) kg much lower than reported previously. The CpUE of all three fish taxa was lower than previously reported, but especially the LabeobarbusCpUE was much lower than before (6.1 kg). An integrated management plan and research program for the Lake Tana basin is urgently required to prevent the collapse of an important fishery and the extinction of the only known cyprinid species flock in the world.
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Dit werk wordt verdeeld onder een Naamsvermelding-NietCommercieel-GelijkDelen 4.0 Internationaal licentie.
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Referenties
AbebeGetahun, EsheteDejen and WassieAnteneh.2008. Fishery studies of RibRiver, Lake Tana Basin, Ethiopia. A report submitted to World Bank. Vol. 2:1573.
Berihun Tefera, Assefa Tessema and Eshete Dejen. 2009. Dry fish market assessment from Lake Tana to Metema. Amhara Regional Agricultural Research Institute (ARARI), Bahir Dar Fishery and Other Aquatic Life Research Center.
De Graaf, M., Machiels, M.A.M., Tesfaye Wudneh and Sibbing, F.A., 2004.Declining stocks of Lake Tana’s endemic Barbus species flock (Pisces; Cyprinidae): natural variation or human impact? Biological Conservation 116: 277-287.
De Graaf, M., Nentwich, E.D., Osse, J.W.M. and Sibbing, F.A., 2005. Lacustrine spawning: is this a new reproductive strategy among ‘large’ African cyprinid fishes? Journal of Fish Biology 66: 1214-1236.
De Graaf, M., van Zwieten, P.A.M., Machiels, M.A.M., Lemma, E., TesfayeWudneh, EsheteDejen, and Sibbing, F.A., 2006. Vulnerability to a small-scale commercial fishery of Lake Tana’s (Ethiopia) endemic Labeobarbus compared with African catfish and Nile tilapia: An example of recruitment overfishing? Fisheries Research 82: 304-318.
Dereje TewabeandGoraw Goshu, 2010. Statusof Lake Tana commercial fishery, Ethiopia, EFASA (Ethiopian Fisheries and Aquatic Science Association), 2nd annual meeting proceeding.
Eshete Dejen, Vijverberg, J., Nagekerke, L.A.J. andSibbing, F.A. 2004. Temporal and spatial distribution of microcrustacean zooplankton in relation to turbidity and other environmental factors in large tropical lake (Lake Tana, Ethiopia).Hydrobiologia513:39–49.
Gordon, D.M., 2003. Technological change and economies of scale in the history of Mweru-Luapula’s fishery (Zambia and Democratic Republic of the Congo). In: Jul-Larsen, E., J. Kolding, R. Overå, J. Raakjær Nielsen and P.A.M. van Zwieten (eds), Management, co-management or no-management? Major dilemmas in southern African freshwater fisheries, FAO Fisheries Technical Paper 426/2. Rome, FAO, pp.164-178.
Kolding, J. 1993. Population dynamics and life history styles of Nile tilapia, Oreochromis niloticus, in Ferguson’s Gulf, Lake Turkana, Kenya. Env. Biol. Fish. 37, 25–46.
Kornfield, I., Carpenter, K.E., 1984. Cyprinids of Lake Lanao, Philippines: taxonomic validity, evolutionary rates and speciation scenarios. In: Echelle, A.A., Kornfield, I. (Eds.) Evolution of fish species flocks. Orono Press, Maine, 69-83pp.
McCartney, M.; Alemayehu, T.; Shiferaw, A.; Awulachew, S. B., 2010. Evaluation of currentand future water resources development in the Lake Tana Basin, Ethiopia. Colombo, SriLanka: International Water Management Institute. 39 pp. (I.W.M.L Research Report 134). Doi: 10.3910/2010. 204.
Nagelkerke, L.A.J. and Sibbing, F.A., 1996. Reproductive segregation among the large barbs (Barbus intermedius complex) of Lake Tana, Ethiopia. An example of intralacustrine speciation? Journal of Fish Biology 49: 1244-1266.
Nagelkerke, L.A.J., Sibbing, F.A., 2000. The large barbs (Barbus spp., Cyprinidae, Teleostei) of Lake Tana (Ethiopia), with a description ofa new species, Barbus osseensis. Nether. J. Zool. 50, 179–214.
Ochumba, P.B.O. and Manyala, J.O., 1992. Distribution of fishes along the Sondu-Miriu River of Lake Victoria, Kenya with special reference to upstream migration, biology and yield. Aquaculture and Fisheries Management 23: 701-719.
Ogutu-Ohayo, R., 1990. The decline of the native fishes of Lakes Victoria and Kyoga (East Africa) and the impact of introduced species, especially the Nile perch, Lates niloticus and the Nile tilapia, Oreochromis niloticus. Environmental Biology of Fishes 27: 81-96.
Shewit Gebremedhin. 2011. Spawning Migration of Labeobarbus species of Lake Tana to Arno-GarnoRiver, Lake Tana sub-basin, Ethiopia. MSc. Thesis, Bahir Dar University.
Skelton, P.H., Tweddle, D., Jackson, P., 1991. Cyprinids of Africa. In: Cyprinid Fishes, Systematics, Biology and Exploitation. Winfield, I.J. and J.S. Nelson (eds.), Chapman and Hall, London, 211-233.
Tesfaye Wudneh, 1998. Biology and management of fish stocks in BahirDarGulf. Lake Tana, Ethiopia. PhD Thesis, Wageningen Agricultural University, Wageningen, The Netherlands.