DSpace Collection:

Lakes water quality monitoring and management programme in developing countries

2011-07-23T15:19:06Z

Title: Lakes water quality monitoring and management programme in developing countries Authors: Mutia, Silas M Abstract: Developing Countries face an array of traditional and modern lakes water quality problems ranging from faecal contamination to toxic chemicals. Moreover, they do so in an economic environment that is severely restricted, an institutional environment which is often poorly structured, and for which the modern scientific knowledge base is frequently poorly understood and applied. Agencies in many developing countries recognize this as major impediment to sustainable development, especially as water quality has become one of the leading economic issues for the purposes of development and investment. Generally water quality programmes tend to suffer from traditional approaches, both of methodology and legal/administrative. The Consequence is that many programmes on lakes water quality are grossly inefficient; produce often unreliable data and which are not generally useful for making management or investment decisions, and face decreasing economic and political support. Programme modernization is essential to achieve the twin goals of greater efficiency and greater relevance in meeting data needs for contemporary lakes water quality management purposes. Modernization reduces costs, may reduce the amount of equipment and infrastructure required, and more closely matches the abilities of developing countries where, for example, knowledge of advanced environmental chemistry may be limited but where knowledge of biological systems is strong.

The life history and survival of Neochetina in Lake Victoria basin: Basis for biological weed control

2012-05-13T21:15:51Z

Title: The life history and survival of Neochetina in Lake Victoria basin: Basis for biological weed control Authors: Ochiel, G.R.S.; Njoka, S.W.; Manyala, J.O.; Okeyo Owuor, J.B. Abstract: 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 and N. eichhorniae significantly decreases with time in weeks (t = 4.09; p<0.01 and (t = 3.40.09; p=0.004 respectively). N. bruchi method had a significantly (p<0.05) high larvae to pupa survival percentage (33.8 ± 6.00 for Incision Egg Setting (IES) method as compared to the Free Egg Setting (FES) method (18.7 ± c 2.6). In the case of N. eichhorniae, the percentage survival for IES (25.4 ± 4.6) was also significantly higher (p>0.05) than the FES method (19.7 ± 4.1).On the basis of these results, we review and discuss data on the damage caused by the two weevil species as a basis for large-scale biological control of water hyacinth in Lake Victoria basin.

Dominance of introduced Nile tilapia, Oreochromis niloticus (L.) in Lake Victoria: A case of changing biology and ecosystem

2011-09-16T00:00:39Z

Title: Dominance of introduced Nile tilapia, Oreochromis niloticus (L.) in Lake Victoria: A case of changing biology and ecosystem Authors: Njiru, M.; Ojuok, J.E; Getabu, A.; Muchiri, M.S.; Cowx, I.G; Okeyo Owuor, J.B. Abstract: Nile tilapia, Oreochromis niloticus together with other tilapiines of Oreochromis leucosticus, Tilapia zillii and Sarotherodon melanopleudra (=T. rendalii) were introduced into Lake Victoria (Kenya) between 1951 and 1962 to boost the then declining fishery. Only O. niloticus was able to establish leading further to reduction in endemic tilapiines of Oreochromis variabilis and Oreochromis esculentus. O. niloticus currently forms the third commercially important species after introduced Nile perch, Lates niloticus and a native cyprinid Rastrineobola argentea, whereas other tilapias are extinct or are occasionally caught in the lake. Information was collected from by bottom trawling and from published literature to ascertain possible factors leading to dominance of O. niloticus. Compared to other tilapiines, Nile tilapia is widely distributed, feeds on a variety of food items, grows to larger sizes, is highly fecund and can survive in a wide range of physical chemical parameters in the lake. These attributes could probably be the reason for its dominance over the tilapiine groups in the lake. Studies further show that ecology and biology of the O. niloticus has changed probably in response to changes occurring in the ecosystem. Management measures to sustain the fishery which include reduced fishing pressure, use of legal fishing methods, and control of environmental degradation have been discussed.

Community involvement in fish harvesting around Lake Victoria (Kenya)

2011-09-16T00:00:39Z

Title: Community involvement in fish harvesting around Lake Victoria (Kenya) Authors: Omwega, R.N. Abstract: Benefits accruing to fishing communities have not marched increases in fish yields. This has affected the disadvantaged groups especially women who rely on processing and marketing fish for their livelihood. The aim of this study was to asses the extent of community involvement in fish harvesting activities, the benefits accruing, perceptions towards fisheries regulations and their constraints in regard to threats and risks they face in Lake Victoria. Sampling was conducted on 25 landing beaches between August and November 2000 and a total of 229 fishers interviewed. Data was obtained using a structured survey questionnaire on fish production and personal interviews. Seventy two percent felt that their occupation was not sustainable due to low prices of fish, 70% of fishers joined the fishery for period between 1 to 10 years, 81% operated on full-time basis, while 19% operated on parttime. During the Government of Kenya retrenchment exercise, there was a short-term influx into the fishery. In a good week, a fisher could earn an average of Kshs.7, 750. In a bad week one could earn approximately Kshs.1, 822. Fishers sampled were familiar with fisheries laws and regulations applied in the management of Lake Victoria fisheries 90%. The results show most fishers have no alternative occupation apart from fishing with men dominating in the harvesting sector while women only owned fishing gears and equipments. Although majority of fishers worked on full-time basis, they have limited or no influence on the levels of benefits they receive from the activity and this can be supported by the unemployment caused by the fish processing factories that fish directly by providing efficient gears and boats to fishermen.