Spatial and temporal changes in the distribution of Rastrineobola argentea in Lake Victoria
Keywords:
Acoustic survey, biomass estimates, stock dynamics, yield, fisheries managementAbstract
Following recent changes in the ecosystem of Lake Victoria resulting from the introduction of Nile perch, Lates niloticus, in the 1960s, there is urgent need for information on which to formulate rational exploitation and management of the fisheries resources. This paper presents information on the biomass and distribution of dagaa, Rastrineobola argentea, the second most important commercial species in Lake Victoria. Data were collected during five acoustic surveys conducted between 1999 and 2001, using a Simrad EY500 echo–integrator with a 120 kHz split–beam transducer. Fish samples were collected using a frame trawl, bottom trawl and pelagic trawl, all lined with 5 mm mesh size netting. The mean total biomass of R. argentea in the lake was 476,902 ± 339,308 t at an average fish density of 7.3 ± 5.4 t km−2 in the sampled area. Potential yield was estimated at 581,584 ± 305,377 t (8.5 ± 4.4 t km−2). The majority of the biomass of R. argentea (an average of 68%) was distributed in waters of more than 40 m depth. The biomass of R. argentea increased progressively over the survey period, probably as a result of decreased predation pressure by Nile perch.
References
Appenzeller, A. R. and Leggett, W. C. 1992. Bias in hydroacoustic estimates of fish abundance due to acoustic shadowing: from day-night surveys of vertically migrating fish. Canadian Journal of Fisheries and Aquatic Science, 49: 2179–2189.
Bundy, A. and Pitcher, T. J. 1995. “An analysis of species changes in Lake Victoria: did the Nile perch act alone?”. In The Impact of Species Changes in African Lakes, Edited by: Pitcher, T. J. and Hart, P. J.B. 111–135. London: Chapman and Hall.
Bwathondi, P. O. J., Ogutu-Ohwayo, R. and Ogari, J. 2001. Lake Victoria Fisheries Management Plan Edited by: Cowx, I. G. and Crean, K. LVFRP Technical Document No. 16, Jinja, Uganda
Crean, K., Abila, R., Lwenya, C., Omwega, R., Omwenga, F., Atai, A., Gonga, J., Nyapendi, A., Odongkara, K., Medard, M., Onyango, P. and Geheb, K. 2002. “Unsustainable tendencies and the fisheries of Lake Victoria”. In Management and Ecology of Lake and Reservoir Fisheries, Edited by: Cowx, I. G. 367–375. Oxford: Fishing News books, Blackwell Science.
Degnbol, P. 1982. Food habits of larval Engraulicypris sardella in Lake Malawi: diurnal feeding pattern and comparison of size groups Technical Report 1, Rome, FAO. FI: DP/MLW/75/019
Foote, K. G. 1987. Fish target strengthens for use in echo integrator surveys. Journal of the Acoustic Society of America, 82: 981–987.
Hecky, R. E. and Bugenyi, F. W. B. 1992. Hydrology and chemistry of the African Great Lakes and water quality issues: problems and solutions. Mitteilungen. Verhandlungen Internationale vereiniging fur theoretische und angewandte Limnologie, 23: 45–54.
Jansen, E. G., Abila, R. O. and Owino, J. P. 1999. Constraints and opportunities for community participation in the management of the Lake Victoria Fisheries IUCN Eastern African Programme. Socio-economics of the Lake Victoria Fisheries. Report 6, IUCN, Nairobi
LVFO, 2005. Regional Status Report on Lake Victoria Frame Surveys for 2000, 2002 and 2004 Kenya, Tanzania and Uganda. LVFO, Jinja, Uganda. http://www.lfvo.org/downloads/Regional%/20frame%20survey%202000–2004.pdf
Marshall, J. R. 2001. Some aspects of the ecology and reproduction of the small pelagic cyprinid, Rastrineobola argentea in Lake Victoria, Masters Thesis England: University of Hull.
Mkumbo, O. C. 2002. Assessment and management of Nile perch(Lates niloticus L.) stocks in the Tanzania waters of Lake Victoria, PhD Thesis England: University of Hull.
Mkumbo, O. C., Ezekiel, C., Budeba, Y. L. and Cowx, I. G. 2002. “Analysis of exploitation patterns for Nile perch, Lates niloticus, in Lake Victoria”. In Management and Ecology of Lake and Reservoir Fisheries, Edited by: Cowx, I. G. 84–95. Oxford: Fishing News books, Blackwell Science.
Moreau, J. 1995. “Analysis of species change in Lake Victoria using ECOPATH, a multispecies trophic model”. In The Impact of Species Changes in African Lakes, Edited by: Pitcher, T. J. and Hart, P. J. B. 137–162. London: Chapman and Hall.
Moreau, J., Ligtvoet, W. and Palomares, M. L. 1993. “Trophic relationship in fish community of Lake Victoria, with emphasis on the impact of Nile perch (Lates niloticus)”. In Trophic models of Aquatic ecosystems, Edited by: Christensen, V. and Pauly, D. 144–152. Manila, Phillippines: ICLAM.
Muhoozi, L. I. 2002. Exploitation and management of the artisanal fisheries in the Ugandan waters of Lake Victoria, PhD Thesis England: University of Hull.
Njiru, M., Othina, A. and Cowx, I. G. 2002. “Lake Victoria invasion by water hyacinth a blessing for Lake Victoria fisheries”. In Management and Ecology of Lake and Reservoir Fisheries, Edited by: Cowx, I. G. 255–263. Fishing News books, Blackwell Science.
Odongkara, C. 2001. Poverty in the fisheries. A framework for analysis and intervention for Lake Victoria. Uganda, PhD Thesis England: University of Hull.
Ogutu–Ohwayo, R. 1990. The decline in 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.
Ogutu-Ohwayo, R., Wandera, S. B. and Kamanyi, J. R. 1998. Fishing gear selectivity for Lates niloticus L. Oreochromis niloticus L. and Rastrineobola argentea P. in Lake Victoria, Kyoga and Nabugabo. Uganda Journal of Agricultural Sciences, 3: 33–38.
Othina, A. and Tweddle, D. 1999. The status of the artisanal fishery of Lake Victoria, Kenya, with notes on improvements to the catch data collection system Edited by: Cowx, I. G. and Tweddle, D. 78–91. Report on fourth FIDAWOG workshop held at Kisumu, 1999 August 16–20.: LVFRP, Kisumu. LVFRP/TECH/99/07
Pitcher, T. J., Bundy, A. and Neill, W. E. 1996. The fishery for Rastrineobola argentea in Lake Victoria: estimation of potential yields using a new approximate model based on primary production. Fisheries Research, 28: 133–149.
Reynolds, J. E., Gréboval, D. F. and Mannini, P. 1995. “Thirty years on: the development of the Nile perch fishery in Lake Victoria”. In The Impact of species changes in African lakes, Edited by: Pitcher, T. J. and Hart, P. J. 181–214. London: Chapman and Hall.
Scholz, C. A., Rosendahl, B. R., Versfelt, J. W. and Rach, N. 1990. Results of high-resolution echo-sounding of Lake Victoria. Journal of African Earth Sciences, 11(1): 25–32.
Sparre, P., Ursin, E. and Venema, S. C. 1989. Introduction to tropical assessment, Part 1. Manual FAO Fisheries Technical Paper 306, Rome
Talling, J. F. 1966. The annual cycle of stratification and phytoplankton growth in L. Victoria (East Africa). Internationale Revue der gesamten Hydrobiologie, 51: 545–621.
Tumwebaze, R. 2003. Hydroacoustic abundance assessment and population characteristics of Rastrineobola argentea in Lake Victoria, PhD Thesis England: University of Hull.
Tweddle, D. and Lewis, D. S. C. 1990. The biology of Usipa (Engraulicypris sardella) in relation to fluctuations in productivity of Lake Malawi and species introductions, London: Overseas Development Administration. Coll. Report on Fishereies Research Malawi, Occassional Paper No. 1
Villanueva, M. C. and Moreau, J. 2002. “Recent trends in the Lake Victoria fisheries assessed by ECOPATH”. In Management and Ecology of Lake and Reservoir Fisheries, Edited by: Cowx, I. G. 96–111. Fishing News books, Blackwell Science.
Wanink, J. H. 1998. “Lake Victoria sardine Rastrineobola argentea: a zooplanktivorous specialist or an opportunistic generalist?”. In The pelagic cyprinid Rastrineobola argentea as a crucial link in the disrupted ecosystem of Lake Victoria: Dwarfs and Giants-African Adventures, PhD Thesis Edited by: Wanink, J. 96–111. Netherlands: University of Leiden.
Wanink, J. H. 1991. “Survival in a perturbed environment: the effects of Nile perch introduction on the zooplanktivorous fish community of Lake Victoria”. In Terrestrial and aquatic ecosystems: perturbation and recovery, Edited by: Rivera, O. 269–275. Chichester: Ellis Horwood Ltd..
Wanink, J. H. 1999. Prospects for the fishery on the small pelagic Rastrineobola argentea in Lake Victoria. Hydrobiologia, 407(1): 183–189.
Wanink, J. H. and Witte, F. 2000. The use of perturbation as a natural experiment: effects of predator introduction on the community structure of zooplanktivorous fish in Lake Victoria. Advance Ecology Research, 31: 553–568.
Witte, F., Msuku, B. S., Wanink, J. H., Seehausen, O., Katunzi, E. F. B., Goudswaard, P. C. and Goldschmidt, T. 2000. Recovery of cichlid species in Lake Victoria: an examination of factors leading to differential extinction. Reviews in Fish Biology and Fisheries, 10: 233–241.
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