A critical look at the current gillnet regulations meant to protect the Nile Perch stocks in Lake Victoria
Keywords:
slot size, long lines, growth over-fishing, catch assessment, mesh sizeAbstract
Nile Perch fishing in Lake Victoria is done using gillnets and long lines. These gears have been deployed in the lake indiscriminately to the extent that in early 2000s the species showed signs of over-fishing. To address this situation, a slot size of 50–85 cm total length (TL) was instituted by the partner states to protect immature fish, and large adults to replenish the stocks while at the same time harvesting mature individuals. Catch Assessment Surveys, have been conducted regularly by the partner states between July 2005 and December 2008 to generate data for setting policies, development planning, and management intervention. A study involving two-stage stratified sampling on the Tanzanian side of the lake showed that Nile Perch caught in the minimum legal 5” gillnets were immature by more than 80%. In contrast Nile Perch of ≥85 cm total length, targeted by long-lines, were seldom encountered to validate the upper limit of the slot size. We advise to abolish the upper slot size limit and introduce a lower legal limit of 7” for gillnets.
References
Asila, A. A. 1999. “Selectivity of gillnets for Nile Perch, Lates niloticus (L.) in Lake Victoria, Kenya”. In LVFRP Technical Document No. 7, Edited by: Cowx, I. G. and Tweddle, D. 92–98. Uganda: LVFRP.
Balirwa, J. S., Chapman, C. A., Chapman, L. J., Cowx, I. G., Geheb, K., Kaufman, L., Lowe-McConnell, R. H., Seehausen, O., Wanink, J. H., Welcomme, R. L. and Witte, F. 2003. Biodiversity and fishery sustainability in the Lake Victoria basin: An unexpected marriage?. BioScience, 53(8): 703–715.
Cowx, I. G, Muhoozi, I., Mkumbo, O., Getabu, A. and Okaronon, J. 2002. Summary evidence for the overexploitation of fisheries resources in Lake Victoria with special reference to Ugandan waters, Strategic exports for Uganda: Fisheries, Kampala: EU Delegation.
Frame Survey Report. 2008. Report on Lake Victoria Fisheries Frame Survey results, Fisheries Division Tanzania.
Fryer, G. 1960. Concerning the proposed introduction of Nile Perch into Lake Victoria. East African Agricultural Journal, 25: 267–270.
Graham, M. 1929. “The Victoria Nyanza and its fisheries. A Report on the fishing survey of Lake Victoria 1927–1928, and appendices”. London Crown Agents for Colonies
Harrison, K. 1991. The Taxonomy of East African Nile Perch Lates spp (Perciformes, Centropomidae). J. Fish. Biol, 38: 175–186.
Kayanda, R., Taabu, A. M., Tumwebaze, R., Muhoozi, L., Jembe, J., Mlaponi, E. and Nzungi, P. 2009. Status of the Major Commercial Fish Stocks and Proposed Species-specific Management Plans for Lake Victoria. African Journal of Tropical Hydrobiology and Fisheries, 12: 60–66.
King, M. 1995. Fisheries Biology, Assessment and Management, Oxford: Fishing News Books.
LVFO (Lake Victoria Fisheries Organization). 2007. “Standard Operating Procedures (SOPs) for Catch Assessment Surveys on Lake Victoria”. In LVFO Standard Operating Procedures No. 3, LVFO Jinja, , Uganda
LVFO (Lake Victoria Fisheries Organization). 2008a. Hydro- acoustic Survey Report, Uganda: LVFO. 2008
LVFO (Lake Victoria Fisheries Organization). 2008b. “Lake Victoria Frame Survey Report (2008)”. Secretariat, , Jinja: Frame Survey Technical Committee.
LVFO (Lake Victoria Fisheries Organization). 2008c. “Draft Catch Assessment Survey Report Tanzania”. December 2008
LVFRP (Lake Victoria Fisheries Research Project). 2001. “Lake Victoria Fisheries Research Project Phase II”. In 1997–2001: Final Report of UNECIA Ltd, Edited by: Cowx, I. G., Crean, K. and MacLennan, D. UK: Universities of the North of England Consortium for International Activities. . Compiled by
Marshall, B. 2008. Is the Nile Perch fishery sustainable?, Jinja, , Uganda: (LVFO) Lake Victoria Fisheries Organization.
Matsuishi, T., Muhoozi, L., Mumbo, O., Budeba, Y., Njiru, M., Asila, A., Othina, A. and Cowx, I. G. 2006. Are the exploitation pressures on Nile Perch fisheries resources of Lake Victoria a cause of concern?. Fisheries Management and ecology, 13: 53–51.
Mkumbo, O. C. 2002. Assessment and management of Nile Perch (Lates niloticus L.) stocks in the Tanzanian waters of Lake Victoria. Thesis submitted for the Degree of Doctor of Philosophy, UK: University of Hull.
Mkumbo, O. C. and Mlaponi, E. 2007. Impact of the baited hook fishery on the recovering endemic fish species in Lake Victoria. Aquatic Ecosystem Health and Management, 10(4): 458–466.
Njiru, M, Getabu, A, Taabu, A., Mlaponi, E., Muhoozi, L. and Mkumbo, O. C. 2009. Managing Nile Perch using slot size: is it possible?. African Journal of Tropical Hydrobiology and Fisheries, 12: 9–14.
Ogutu-Ohwayo, R. 1990. The decline in the native fishes of lakes Victoria and Kyoga (East Africa) and the impact of the introduced species, especially the Nile Perch. Lates niloticus and Nile Tilapia Oreochromis niloticus. Environmental Biology of Fishes, 27: 81–96.
Pitcher, T. J. and Hart, P. J.B. 1982. Fisheries Ecology, London: Croom Helm.
TAFIRI (Tanzania Fisheries Research Institute). 2005. Report on assessment of the size selectivity of the five-inch gillnets in the Nile Perch fishery in Lake Victoria, Tanzania: TAFIRI, Dar es Salaam.
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