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Registros recuperados: 3
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Multigear fishery of Nile perch (Lates niloticus) in the Winam Gulf of Lake Victoria: with special reference to mortality, selection and catch/effort data OceanDocs
Manyala, J.O.; Rabuor, C.O..
A survey of multigear fishery of Nile perch (Lates niloticus) in the Winam Gulf of Lake Victoria indicates that total mortality coefficient (Z) determined from longline fishery using hook number 6 was double that of hook number 7. Total mortality coefficient determined from gillnets and beachseines were lower than those of hooks. The catch per unit effort (C/f) measured using different criteria indicated an increase for all gears in 1990 as compared to 1989 except for gillnets. A two-fold increase in unit effort (f) increased the C/f for mosquito seines by only 30%. The typical exponential decay of C/f with increasing f of exploited stock in equilibrium was lacking in the case of Nile perch in the Winam Gulf.
Tipo: Proceedings Paper Palavras-chave: Lates niloticus; Catch/effort; Exploitation; Gillnets; Lake fisheries; Gillnets; Lake fisheries; Http://aims.fao.org/aos/agrovoc/c_32431; Http://aims.fao.org/aos/agrovoc/c_4159.
Ano: 1994 URL: http://hdl.handle.net/1834/1174
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Floodplain fishery of the lower Sondu-Miriu River with emphasis on the Nile perch (Lates niloticus) (Linnaeus) OceanDocs
Manyala, J.O..
Experimental beach seine surveys in 1990 in the lower Sondu-Miriu River in Kenya indicate a potential catch rate of up to 59.8 kg ha super(-1) hr super(-1). Lates niloticus dominated the catches in the lower reaches (37.5%), while catches in the upper reaches were dominated by Labeo victorianus, Schilbe mystus and Barbus altianalis. L. victorianus contributed up to 84.8% of the catch in the upper reaches by weight. Catches in the floodplain were dominated by Oreochromis niloticus, O. variabilis and Clarias gariepinus, which contributed more than 50% by weight. The size frequency distribution of L. niloticus suggests that larger specimens occur in the river as compared to the floodplain.
Tipo: Proceedings Paper Palavras-chave: Catch composition; River fisheries; River fisheries; Catch composition; Http://aims.fao.org/aos/agrovoc/c_6615; Http://aims.fao.org/aos/agrovoc/c_1384.
Ano: 1994 URL: http://hdl.handle.net/1834/1173
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The life history and survival of Neochetina in Lake Victoria basin: Basis for biological weed control OceanDocs
Ochiel, G.R.S.; Njoka, S.W.; Manyala, J.O.; Okeyo Owuor, J.B..
Using our own experimental data and published data, we review information on the control process of water hyacinth and its status in Lake Victoria basin, Kenya. Experimental results show that the mean fecundity of the two weevils is 290 and 237 eggs per female laid over a period of 16 weeks, with an adult longevity of 98 and 112 days for Neochetina bruchi and N. eichhorniae respectively. There was significant difference between the egg laying capacities of the two weevil species (p=0.002). The survival rate of the two species was significantly different (p<0.05) for all life stages except for larvae to pupa. There was no significant interaction between the species and the method of experimental egg setting (p<0.05). The fecundity of both N. bruchi...
Tipo: Proceedings Paper Palavras-chave: Biological development; Life cycle; Plant control; Biological control; Aquatic insects; Insect eggs; Entomology; Environment management; Survival; Biological control; Biological development; Life cycle; Http://aims.fao.org/aos/agrovoc/c_918; Http://aims.fao.org/aos/agrovoc/c_921; Http://aims.fao.org/aos/agrovoc/c_4317.
Ano: 2006 URL: http://hdl.handle.net/1834/1498
Registros recuperados: 3
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