The Trophic Structure and Diversity of Haplochromines among the Kyoga Minor Lakes

Before the introduction and establishment of the Nile perch, Lates nilolicus (L). Lakes Victoria and Kyoga had a diverse fish fauna, dominated by haplochromine cichlids. The haplochromines had evolved into many trophic groups which occupied virtually all trophic levels and contributed to the ecological efficiency of the lakes. Establishment of Nile perch in the main lakes was followed by a decline and in some cases complete disappearance of many haplochromine trophic groups. This is thought to have affected the efficiency of the ecosystem. This study examined the species composition and trophic diversity among haplochromines in Kyoga Minor lakes where Nile perch was not introduced and compared this with historical data from Lake Victoria. Six Kyoga Minor lakes and the main Lake Kyoga (Iyingo) were sampled. Forty one haplochromine species were recorded in the Kyoga lake basin and only fourteen species were recorded from the main Lake Kyoga. Species and trophic diversity of haplochromines were highest in the Kyoga Minor lakes as compared to Lake Kyoga

Final report of the fisheries catch assessment survey in the Ugandan waters of Lake Victoria for the March 2010 survey

This report presents findings of the CAS conducted in the Ugandan waters of Lake Victoria in March 2010. The results of the previous ten CASs conducted under the same programme in July, August, September and November 2005; in March, August and December 2006; in March, and August 2007; in February and December 2008 are included to show the emerging trends. The report also presents total annual catch estimates for the Ugandan part of the lake from 2005 to 2010

The fishery potential of the minor lake (Nabisojjo) - Luwero District

Luwero district before the creation of Nakasongola District had a share of south-western portion of Lake Kyoga. After loosing the portion of the lake, they want to resort the minor lake (Nabisojjo) for supply of fish at least to the population around this lake. The plans were to start commercial fishing. The lake is 45 km from Luwero town adjacent 10 the road going to Ngoma town. River Nabisojjo, a tribulary of river Mayanja flows through the lake on its way to river Kafu. The main objective of the scientific field study on Lake Nabisojjo was therefore to generate information on the status of the lake fishery and recommend to the local authorities the next line of action

The fish stocks of Kabaka's Lake

Kabaka's Lake as the name implies, is a lake that belongs to the Buganda Kingdom which is under the Kabaka of Buganda (King of Buganda) and is located in the central portion of Kampala city. At the launching of "Food for all in Buganda" campaign during November 1999 at Nfuufu in Mukono District -Uganda, National Agricultural Research Organisation (NARO) was requested to find means of reactivating the fishery potential of the lake. The lake had been stocked with the Nile perch (Lates niloticus & T. zilli) during 1950s and the fishery was not being efficiently exploited. After restocking, no monitoring was done and therefore it was not known whether the introduced species established themselves. Restocking was mainly aimed at enabling this lake provide a source of food and recreation. The major objective of the study therefore was to establish the present status of the fishery by determining the fish species composition, distribution, relative abundance, population structure of the major fish species, catch rates in the gill net fishery and the biology and ecology of the dominant fish species. The study was conducted during 200

Implications of changes in trophic diversity and food webs on fisheries and the environment

Most of the earth's ecosystems are experiencing slight to catastrophic losses of biodiversity, caused by habitat destruction, alien species introduction, climate change and pollution (Wilcove et al., 1998). These human effects have led to the extinction of native fish species, the collapse of their populations and the loss of ecological integrity and ecosystem functioning (Ogutu-Ohwayo & Hecky, 1991; Witte et al. , 1992a; Mills et al., 1994; Vitousek et al., 1996). Food webs are macro-descriptors of community feeding interactions that can be used to map the flow of materials and nutrients in ecosystems (Jepsen & Winemiller, 2002). Comparative food web studies have been used to address theoretical questions such as 'does greater trophic connectivity increase stability?' (Cohen et al., 1990), and 'does the number of trophic levels increase with productivity?' (Briand & Cohen, 1987). Answers to such questions have obvious applications for natural resources management. From a multi-species fisheries standpoint, there is a need to understand consumer-resource dynamics within complex trophic networks

Trophic interrelationships and food-webs among the fishes in ecosystems of the Victoria and Kyoga lake basin

The Victoria and Kyoga lake basins had a high fish species diversity with many fish species that were found only in these lakes. Two Tilapiines species Oreochromis esculentus and Oreochromis variabilis were the most important commercial species in these lakes and were found nowhere else on earth except in the Victoria and Kyoga lake basins (Graham 1929, Worthington 1929). Lakes Kyoga and Nabugabo also had endemic haplochromine species (Worthington 1929, Trewavas 1933, Greenwood 1965, 1966). As stocks of introduced species increased, stocks of most of the native species declined rapidly or disappeared altogether. The study was carried out on Lakes Victoria and Kyoga, River Nile, some selected satellite lakes from the two basins namely Lakes Mburo, Kachera, Wamala, Kayanja, Kayugi, Nabugabo, Victoria, Victoria nile and River Sio(Victoria lake basin). Lakes Kyoga (Iyingo), Nawampasa, Nakuwa, Gigati, Nyaguo, Agu, Kawi and Lemwa (Kyoga lake basin). Species composillon and relative abundance of fishes were estimated by detennining the overall average total number of each species encountered. A trophic consists of species using the same food category. Shannon-Weaver Index of diversity H (Pielou, 1969) and number of trophic groups, were used to estimate the Trophic diversity of various fish species in the lakes. Food analysis has been done on some fishes in some of the sampled lakes and is still going on, on remaining fishes and in some lakes. Generally fish ingested detritus, Spirulina, Melosira, filamentous algae, Planktolyngbya, Microcysists, Anabaena, Merismopedia, Spirogyra, higher plant material, rotifers, Ostracodes, Chironomid larvae and pupae, Choaborus larvae, Odonata, Povilla, Insect remains, Caridina, fish eggs and fish. Eight trophic groups were identified from thes food items ingestes. These included detritivores, algae eaters, higher plant eaters, zooplanktivores, insectivores, molluscivores, prawn eaters, paedophages and piscivores. Trophic diversity by number of trophic groups was highest in Lake Kyoga (6) followed by lakes Kayugi, Nabugabo, River Nile and Mburo (3) and the lowest number was recorded in kachera (2)

The fisheries diversity of Lake Mburo with reference to Lake Kachera and some other Ankole minor lakes

Lakes Mburo and Kachera are part of the complex system of lakes known as the the Koki lakes. These lakes form part of the Victoria satellite lakes. The Koki lakes are separated by extended swamps. The fisheries of these lakes are important as they contribute to government efforts of increasing food security, poverty reduction and conservation of natural resource base. These lakes are important biodiversity areas because some of these lakes have been found to contain the native tilapiine Oreochromis esculentus (Ngege), absent or threatened with extinction in the main lakes Victoria and Kyoga. It's also important to note that this species is only unique to the Victoria and Kyoga lake basins (Graham, 1929, Worthington, 1929). The values of some of these lake fisheries are however, threatened by human. activities such as over exploitation, introduction of exotics especially water hyacinth which is already present in River Ruizi, habitat degra-dation among others

The decline of Alestes baremose Boulenger, 1901 and Hydrocynus forskahlii (Cuvier, 1819) stocks in Lake Albert: implications for sustainable management of their fisheries

The fish stocks of Lake Albert face immense exploitation pressure which has led to “fishingdown” of their fisheries, with some larger species having been driven to near-extinction, while others such as Citharinus citharus have almost disappeared. Both A. baremose (Angara) and H. forskahlii (Ngassia) historically formed the most important commercial species in Lake Albert until the early 2000s but recent Catch Assessment Surveys (2007-2013) revealed a sweeping decline in their contribution to the commercial catch from 72.7% in 1971 to less than 6% in 2013. The catch per unit effort also registered a two-fold decline from 45.6 and 36.1 kg/boat/day to 22.6 and 18.1 kg/boat/day for A. baremose and H. forskahlii respective between 1971 and 2007. Over 50% of illegal gillnets, below the legal minimum limit of four inches (101.6 mm) used on Lake Albert target the two species. Gillnet experiments found the three inch (76.2 mm) gill net mesh size suitable for sustained harvest of the two species. The study concludes that optimal utilization of the two species and probably other non target fish species is achievable through species specific management strategies, coupling species specific licensing, and controlling harvest of juvenile individuals, overall fishing effort and fish catch on Lake Albert and protecting the vulnerable fish habitats

Population morphological variation of the Nile perch (Lates niloticus, L. 1758), of East African Lakes and their associated waters

In this study an attempt was made to determine whether there are morphological variations associated with the different geographical populations of the Nile perch of East Africa. Analyses of the levels of morphological differentiation based on morphological characterisation and variation were carried out. The study was based on 864 Nile perch sampled from 25 different locations from different Lakes in the region and 10 morphological characters. Also determined were the length – weight relationships and condition factor of sampled Nile perch. The log transformed data of all sampled Nile perch were subjected to multivariate analysis, using ‘PAST’ statistical software. Findings showed that peduncle form and size, of all the variables used in this study, contributed most to the variance. The analysis clustered the Nile perch into two groups, which were found to be as characterised by earlier morphological description of this species and most probably are representatives of two distinct taxa of Nile perch in the East African waters. The LWRs and condition factor conformed to the fish isometric growth formula W = aLb with the value for the pooled data being W = 0.6664L0.3264. The existence of 2 morphs agrees with earlier taxonomists (Harrison, 1991; Ribbink, 1987; Bwathondi, 1985; Holden, 1967) who proposed that Nile perch exists in two populations – a bigger shallow water dwelling morph and a smaller deep open water dwelling morph. This calls for identification and mapping of the 2 populations in the different waters of East Africa that may require application of different management regimes.Keywords: Nile perch, taxa, morphological variation, East Africa

Associations between highly active antiretroviral therapy and the presence of HPV, premalignant and malignant cervical lesions in sub-Saharan Africa, a systematic review : current evidence and directions for future research

Objectives: In sub-Saharan Africa, substantial international funding along with evidence-based clinical practice have resulted in an unparalleled scale-up of access to antiretroviral treatment at a higher CD4 count. The role and timing of highly active antiretroviral therapy (HAART) in mediating cervical disease remains unclear. The aim of this article is to systematically review all evidence pertaining to Africa and identify research gaps regarding the epidemiological association between HAART use and the presence of premalignant/malignant cervical lesions. Method: Five databases were searched until January 2017 to retrieve relevant literature from sub-Saharan Africa. Publications were included if they addressed prevalence, incidence or clearance of human papillomavirus (HPV) infection in women undergoing HAART as well as cytological or histological neoplastic abnormalities. Results: 22 studies were included, of which seven were prospective studies. Women receiving HAART are less likely to develop squamous intraepithelial lesions (SILs). There is evidence that duration of HAART along with the CD4 count may reduce the prevalence of high-risk HPV (HR-HPV), suggesting that without HAART, severe immunosuppression increases the risk of becoming or remaining infected with HR-HPV. Furthermore, according to existent literature, the CD4 count, rather than HAART coverage or its duration, plays a central role in the prevalence of cervical intraepithelial neoplasia (CIN) 2 and CIN 3. Conclusion: Our findings suggest a positive impact of HAART duration, in conjunction and interaction with CD4 count, on reducing the prevalence of HR-HPV. The greatest treatment effect might be seen among women starting at the lowest CD4 count, which may have a more instrumental role in cervical oncogenesis than either HAART use or the treatment duration on the prevalence of CIN 2 and CIN 3. There is still insufficient evidence to show a clear association between HAART coverage and the incidence of invasive cervical cancer. Enhanced surveillance on the impact of HAART treatment is crucial