Results from RV Utafiti research cruises

Monthly fish surveys were made from 1997-1999 in the Kenyan waters of Lake Victoria in order to estimate the magnitude of fisheries resources. Sample sites were defined using GPS while thirty minute hauls in alternate grid squares were made. Demersal fish biomass was estimated using the swept area method, while for trawling two different trawl nets were used. Collected fish was sorted into species, measured (TL) and weighed. Smaller fish were mixed on deck and sub-samples taken. Sexual maturity stages of fish were also observed. Areas with consistency high catches were located outside major urban and riverine influence where most artisanal fishermen were concentrated. Very low catches were obtained from areas that had recently been covered by water hyacinth Eichhornia crassipe

Results of the first hydroacoustic survey of the Ugandan waters of Lake Victoria

A lakewide hydroacoustic research programme was designed in the Ugandan waters of Lake Victoria in order to ascertain the status of fish stocks. Data obtained from the hydroacoustic surveys were complemented with by catch data from multi mesh gillnets and frame trawls to validate acoustic estimates. Fish were distributed over the whole survey area, though the densities and species composition varied from place to place. Echo traces showed the fish formed schools during daytime and became more dispersed towards evening. Approximately equivalent indices of abundance were estimated for Rastrineobola argentea and Haplocromines. The distribution of the freshwater prawn, Caridina nilotica and the lakefly Chaoborus sp. was patchy. Dense swarms of Chaoborus larvae were observed to disperse from the lake bottom as the night approached thus assuring echo-traces formed by fish on the echogram and making their interpretation difficult. Caridina nilotica were observed to form dense echo-traces at the thermoclin

Relative abundance and distribution of fish in Kenyan waters of Lake Victoria

Bottom trawl surveys were conducted in Kenyan waters of Lake Victoria during the period September 1997 and March 1999. The means of fish biomass for the two most important species: Lates niloticus (L.) and Oreochromis niloticus (L.) were estimated at 61.5 kg ha and 4.5 kg ha respectively. There were few L. niloticus greater than 80 cm TL and O. niloticus greater than 50 cm TL, though these species attain maximum sizes of 205 cm and 65 cm respectively. Oreochromis niloticus was mostly found shallower than 5 m though some specimens were encountered deeper than 10 m, suggesting that the species has extended its ecological range. Very low catches were obtained from areas under water hyacinth cover. Water in such areas was turbid with oxygen levels below the critical 3.0 mg L

Managing Nile perch using slot size: is it possible?

The fishery of Lake Victoria became a major commercial fishery with the introduction of Nile perch in 1950s and 1960s. Biological and population characteristics point to a fishery under intense fishing pressure attributed to increased capacity and use of illegal fishing gears. Studies conducted between 1998 to 2000 suggested capture of fish between slot size of 50 to 85 cm TL to sustain the fishery. Samples from Kenya and Uganda factories in 2008 showed that 50% and 71% of individuals processed were below the slot size respectively. This study revealed that fish below and above the slot has continued being caught and processed. This confirms that the slot size is hardly adhered to by both the fishers and the processors. The paper explores why the slot size has not been a successful tool in management of Nile perch and suggests strategies to sustain the fisher

Growth Performance, Yields and Economic Benefits of Nile Tilapia Oreochromis niloticus and Kales Brassica oleracea Cultured under Vegetable-Fish Culture Integration

An experiment was conducted for 210 days to demonstrate the role of vegetable-fish culture integration in the growth, yields and economic benefits of fish and vegetables. Two 200 m2 earthen fishponds were stocked with Nile tilapia Oreochromis niloticus at 20,000 fish fingerlings per hectare. Pond A was fertilized with chicken manure and stocked fish fed on 35% crude protein supplementary diet referred to here as treated fish pond (TFP). Another fish pond was not fertilized and the fish stocked in it did not receive any supplementary diet referred to here as non treated fish pond (NTFP). Twelve vegetable plots of 7.2 x 3 m were planted with kale seedlings at a spacing of 0.45 x 0.6 m. The first, second and third sets of three vegetable plots were irrigated by water from stream (SW), treated fish pond (TFP) and non treated fish pond (NTFP) respectively. The last three vegetable plots were not irrigated (NI). Sampling of kale leaves was done by removal of the lowest three leaves per plant every four days. Results showed that fish reared under integrated systems attained significantly higher growth than those reared under non integrated systems (t-test, t=14.38, d.f. = 118, P<0.001). One way Analysis of Variance showed a significant difference in kale leaf yields and income (ANOVA: F=63.17; P<0.05; d.f.=3) among plots receiving different sources of water with plots receiving water from treated fish pond (TFP) attaining highest yield and income. Gross and net yields of 2,806.969±198 and 2706.569±194 kgha-1 (for fish) and 51,970.49 and 51,968.63 kgha-1 (for vegetables) respectively attained were highest from integrated than non-integrated systems. Partial enterprise budget analysis showed that net returns were higher from integrated than non integrated systems. Results from this study demonstrate that fish farmers could improve yields and profits by integrating fish farming with other on-farm activities.Tanz. J. Sci. Vol. 37 2011, 37-4

Influence of Participation of School Youth in Decision Making During Showcasing Success Stories by Young Agripreneurs on Implementation of Agricultural Programmes

School agriculture programme was introduced in secondary education curriculum in Kenya in 1965 and has academic objective to transfer scientific knowledge, and a vocational one to impart skills that would enable youth become self reliant. However, the vocational objective is scantly attained and school youth are inadequate in skills necessary for creation of livelihoods. It is expected that school youth would acquire more and specialized skills for independence through implementation of agricultural programmes such as in showcasing success stories by young agripreneurs. Participation in decision making on the showcasing events would act as motivation for youth to increase implementation of agricultural programmes. However, there is problem of low participation of school youth in decision making on implementation during showcasing success stories by young agripreneurs. This research was conducted to establish the influence of participation of school youth in decision-making during showcasing by young agripreneurs on implementation of agricultural programmes. The study was carried out in extra-county, county and sub-county category of secondary schools offering agriculture subject and, spread in five agro-ecological zones typical of Kenyan farm types, and found in Kisii and Nyamira counties region. Cross-sectional survey design was used. School youth are secondary school form fours taking the subject and implementing KCSE agriculture project. Stratified, purposive, and simple random sampling procedures were used to select a sample of 361 school youth. Data was collected using questionnaires, analyzed by descriptive and inferential statistics at probability level of 0.05 using SPSS version 21. Results show that school youth are well exposed to showcasing success stories by young agripreneurs for acquiring more and specialized implementation skills. It also confirms that gender of youth in school does not make a significant difference in the level of participation in decision making during showcasing events by young agripreneurs. School youth rated five of the six strategies evaluated as very important, and identified some amongst them as more significantly very important than the rest in increasing their participation during showcasing by young agripreneurs. There is a positive significant and linear correlation between level of participation in decision making during showcasing of success stories by young agripreneurs and level of implementation of agricultural programmes by school youth (R= 0.30, p = 0.00), p = 0.00). These findings will be useful in addressing issues of school youth participation in decision making during showcasing by young agripreneurs to motivate others implement agricultural programmes for self reliance

An assessement of the ecosystem health of Lake Victoria (East Africa): Current status, trends and impacts to fishery

The paper presents results on the current environmental conditions in Lake Victoria in order to improve understanding on the limnological changes that have taken place over the last four decades and their impacts on fish stocks. Results show that in last four decades, Secchi disc visibility decreased by about 75% (range: 0.5m in the shallow bays around Nyanza Gulf to 5.7m in deep waters). Oxycline depth decreased by 50% indicating that a large body of the lake water in the deeper waters cannot support life. Chlorophyll a has increased three times compared to historical values. Results also show that the redfield ratio has decreased to 8.2:1 (N: P)  indicating more P and less N in the lake water. Low oxygen conditions in the deep water causes rapid denitrification with subsequent loss of nitrogen. In addition, primary productivity has doubled over the period and algal biomass increased by 8-10 folds. The algal biomass is currently dominated by Cyanophyta. Zooplankton communities have also changed to smaller sized species and a dominance of rotifers while the micro-invertebrate Caridina nilotica has a higher abundance in inshore waterscompared to offshore waters. Changes in phytoplankton and zooplankton biomass and species composition following eutrophication has influenced changes in herbivorous fish species as well as zooplanktivorous resulting in increase of zooplankton fish species such as “Dagaa” Rastrineobola argentea, and decline of other species. Changes in other ecological interactions due to species introduction and predation accelerated by the environmental changes and increased fishing pressure have furthercomplicated the ecosystem dynamics of Lake Victoria and pose serious uncertainties about its future stability and sustainability of the fisheriesresources. Lake Victoria’s future sustainability requires effective management of fishing effort and phosphorous loading. Future research should endeavour to determine an acceptable nutrient loading rate that will sustain/ improve the fishery.Key words: Deoxygenation, Phosphorous, NP ratios, Eutrophication, Fisher

Engagement of Out of School Youth in Decision Making During Showcasing of Success Stories by Young Agripreneurs and Its Effect on Implementation of Agricultural Programmes

Participation of out of school youth in decision making on showcasing success stories by young agripreneurs would act as motivation for them to increase implementation of agricultural programmes for self reliance. However, there is problem of low participation of out of school youth in decision making on showcasing success by young agripreneurs. Out of school youths who have completed secondary school agriculture are scantly exposed in agripreneurship. It is expected that the gap in knowledge and skills would be filled by the youth participating in showcasing success events by young agripreneurs. This research was conducted to establish the influence of participation of out of school youth in decision-making on showcasing success stories by young agripreneurs on implementation of agricultural programmes. The investigation was conducted in three categories of secondary schools offering agriculture subject, spread in five agro-ecological zones typical of Kenyan farm types, and found in Kisii and Nyamira counties region. Cross-sectional survey design was used. Out of school youth are those who studied agriculture subject and are registered with youth groups within their localities engaged in agricultural activities for creation of livelihoods. Stratified, purposive, and simple random sampling procedures were used to select a sample size of 160 out of school youth. Data was collected using questionnaires, analyzed by descriptive and inferential statistics at probability level of 0.05 using SPSS version 21. Results show that gender of out of school youth does not make a significant difference in the level of participation in decision making on showcasing events by young agripreneurs. Youth out of school are in concurrence that strategies 5, 4, 3 and 6 are more significantly very important than the rest in increasing their participation in decision making during showcasing success stories by young agripreneurs. Strategy 5 is identified as outstanding out of the four and advocates for the formation of agribusiness clubs at community level where successful agripreneurs can mentor the out of school youth, share ideas, experiences and  showcase their successes. There is a positive significant linear correlation between level of participation in decision making during showcasing of success stories by young agripreneurs and the level of implementation of agricultural programmes by youth out of school (R= 0.438762, p = 0.00). These findings will be useful in addressing issues of out of school youth on participation in decision making during showcasing success stories by young agripreneurs to prompt them implement agricultural programmes for independence