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Management issues in the Lake Victoria watershed
Abstract
Lake Victoria is the largest lake in Africa (68 800 km2) and is the eighth largest lake in the world by volume. The three East African countries of Tanzania, Uganda and Kenya share Lake Victoria and its resources. The total annual catch of fish from the lake ranges between 400 × 106 kg and 500 × 106 kg, bringing these riparian countries a combined annual income of approximately US$250 000–500 000 from exports alone. Approximately 30 million people live in the riparian region and the catchment, with about 2 million of these depending directly or indirectly on fishing activities. Tragically, Lake Victoria’s extremely diverse fauna was decimated in only 30 years following the introduction of non-native Nile perch in the early 1960s. An estimated 200 endemic cichlid species became extinct. Dramatic increases in overfishing, pollution from various sources, effects of noxious water weeds and other associated problems threaten the sustainability of the lake’s resources and the economies of the riparian governments and peoples. Regulations governing Lake Victoria’s resources are different in each country. The laws concerning treatment of effluents from point sources in the three countries are not harmonized, neither are implementation or enforcement provisions. The governments of Kenya, Uganda and Tanzania have begun to put in place regional mechanisms to address the lake’s many problems including the creation of a permanent regional international institution through the establishment of the Lake Victoria Fisheries Organization (LVFO). A strategic vision document and action plans have been developed. Efforts are being made at local, national and regional levels to control the water hyacinth, including manual pulling, mechanical harvesting and introduction of weevils that weaken hyacinth root systems. To address the problem of overfishing, fishermen committees at landing beaches have been put in place. Each country has committed to take all necessary measures including legislation to implement the decisions of the LVFO governing bodies. All three countries have agreed to adopt and enforce legislation and regulations prohibiting the introduction of non-indigenous species to the lake and to enforce existing regulations regarding fisheries. A Global Environment Facility project which provides funding to the Lake Victoria Fisheries Organization addresses land use management, catchment forestation, fisheries research and management, water hyacinth control, industrial effluent treatment and municipal waste treatment.
... Pollution from industrial sources (such as sugar refineries, oil and soap mills, and dairies) and agriculture (such as fertiliser from coffee, tea, cotton, maize, and cotton farms) has increased tremendously, with total nitrogen and phosphorus application increasing on average by 85 % across the basin in the last 50 years (FAO, 2023). This has accelerated eutrophication within the basin's waters (Magunda and Majaliwa, 1999;Ntiba et al., 2001), which was a main concern for 38 % of the stakeholders. In addition, many stakeholders expressed concerns regarding the impacts of reduced water quality and eutrophication on the aquatic ecosystems, which have been historically threatened by anoxia and invasive species in addition to the reduced water quality (Mugidde et al., 2005;Njiru et al., 2008;Ntiba et al., 2001;Raburu et al., 2009). ...
... This has accelerated eutrophication within the basin's waters (Magunda and Majaliwa, 1999;Ntiba et al., 2001), which was a main concern for 38 % of the stakeholders. In addition, many stakeholders expressed concerns regarding the impacts of reduced water quality and eutrophication on the aquatic ecosystems, which have been historically threatened by anoxia and invasive species in addition to the reduced water quality (Mugidde et al., 2005;Njiru et al., 2008;Ntiba et al., 2001;Raburu et al., 2009). In accordance with this, Mugidde et al. (2005) found the average chlorophyll-a concentrations in 2000 within Lake Victoria to be 45.7 mg L − 1 (ranging from 3.0 to 656.0 mg L − 1 ), which Table 1 Information extracted from documentation concerning WEFE nexus tools. ...
... Of these, deforestation and degradation of wetlands were emphasised to be the most significant challenges in the basin (Fig. 2), particularly due to the impacts this has on ecosystems, water quality, and food security (both agriculture and fisheries). This corresponds to the environmental challenges identified in the scientific literature, many of which cite land use change as one of the greatest pressures within the basin, which is underpinned by a whole suite of drivers such as population growth, agricultural expansion, forest exploitation, and infrastructural development (Chapman et al., 2008;Muyodi et al., 2010;Ntiba et al., 2001;Odada et al., 2009;Waiswa et al., 2015). In accordance with this, a study by Mugo et al. (2020) found that within the Lake Victoria basin, large scale farmlands and urban areas have increased by 55 % and 890 % respectively between 1985 and 2014, whilst wetlands and closed woodland have decreased by 33 % and 75 % respectively. ...
... Pollution from industrial sources (such as sugar refineries, oil and soap mills, and dairies) and agriculture (such as fertiliser from coffee, tea, cotton, maize, and cotton farms) has increased tremendously, with total nitrogen and phosphorus application increasing on average by 85 % across the basin in the last 50 years (FAO, 2023). This has accelerated eutrophication within the basin's waters (Magunda and Majaliwa, 1999;Ntiba et al., 2001), which was a main concern for 38 % of the stakeholders. In addition, many stakeholders expressed concerns regarding the impacts of reduced water quality and eutrophication on the aquatic ecosystems, which have been historically threatened by anoxia and invasive species in addition to the reduced water quality (Mugidde et al., 2005;Njiru et al., 2008;Ntiba et al., 2001;Raburu et al., 2009). ...
... This has accelerated eutrophication within the basin's waters (Magunda and Majaliwa, 1999;Ntiba et al., 2001), which was a main concern for 38 % of the stakeholders. In addition, many stakeholders expressed concerns regarding the impacts of reduced water quality and eutrophication on the aquatic ecosystems, which have been historically threatened by anoxia and invasive species in addition to the reduced water quality (Mugidde et al., 2005;Njiru et al., 2008;Ntiba et al., 2001;Raburu et al., 2009). In accordance with this, Mugidde et al. (2005) found the average chlorophyll-a concentrations in 2000 within Lake Victoria to be 45.7 mg L − 1 (ranging from 3.0 to 656.0 mg L − 1 ), which Table 1 Information extracted from documentation concerning WEFE nexus tools. ...
... Of these, deforestation and degradation of wetlands were emphasised to be the most significant challenges in the basin (Fig. 2), particularly due to the impacts this has on ecosystems, water quality, and food security (both agriculture and fisheries). This corresponds to the environmental challenges identified in the scientific literature, many of which cite land use change as one of the greatest pressures within the basin, which is underpinned by a whole suite of drivers such as population growth, agricultural expansion, forest exploitation, and infrastructural development (Chapman et al., 2008;Muyodi et al., 2010;Ntiba et al., 2001;Odada et al., 2009;Waiswa et al., 2015). In accordance with this, a study by Mugo et al. (2020) found that within the Lake Victoria basin, large scale farmlands and urban areas have increased by 55 % and 890 % respectively between 1985 and 2014, whilst wetlands and closed woodland have decreased by 33 % and 75 % respectively. ...
... The three governments began discussions about transboundary water management following the Rio Earth Summit (Muyodi et al., 2010). They submitted a biodiversity grant to the Global Environment Facility (Ntiba, Kudoja, & Mukasa, 2001). 19 ...
... A long drought began that lasted until 1984 (Mwiturubani & van Wyk, 2010). 14 The water hyacinth was introduced into the lake (Ntiba et al., 2001). 15 ...
... The countries are also obligated to legislatively implement decisions of the LVFO Steering Committee (Zilov, 2013). There have been criticisms that there is little financial investment by states in the LVFO and that there has not been harmonization of regulations signaling lack of commitment to constraints and costs affiliated with the organization (Ntiba et al., 2001). The Lake Victoria Environmental Management Project (LVEMP) was also agreed upon by the three riparian countries in 1994 to conduct research and address environmental management of the lake (Wirkus & Böge, 2006;Kolding et al., 2014). ...
... The East African Great Lakes are well-known biodiversity hotspots and constitute an important fisheries resource for the rapidly growing human population through the provision of food protein and employment (Scullion, 2007;Tibihika et al., 2022). In Uganda, the fisheries subsector is predominantly supported by the six major freshwater bodies, including lakes Victoria, Kyoga, Edward, George, Albert and the Nile River (Ntiba et al., 2001;Ogutu-Ohwayo et al., 1997). The capture fisheries from L. Victoria alone contribute between $250,000 and $500,000 annually to the three greater East African States of Uganda, Kenya and Tanzania from exports and support a population of over 42 million people (Ntiba et al., 2001;Nyamweya et al., 2023). ...
... In Uganda, the fisheries subsector is predominantly supported by the six major freshwater bodies, including lakes Victoria, Kyoga, Edward, George, Albert and the Nile River (Ntiba et al., 2001;Ogutu-Ohwayo et al., 1997). The capture fisheries from L. Victoria alone contribute between $250,000 and $500,000 annually to the three greater East African States of Uganda, Kenya and Tanzania from exports and support a population of over 42 million people (Ntiba et al., 2001;Nyamweya et al., 2023). In Uganda, the available aquatic resources not only demonstrate enormous potential for aquaculture and capture fisheries but also support the livelihood of more than 3.5 million people (Cai et al., 2017). ...
Nile tilapia (Oreochromis niloticus), native to Africa and the Levant, is an important species for both aquaculture and capture fisheries. Despite these attributes, Nile tilapia has been negatively impacted by anthropogenic activities ranging from overfishing and habitat destruction to translocations. These human‐mediated activities have threatened the genetic evolutionary integrity of native populations of Nile tilapia and congeneric species through admixture, demographic bottlenecks and introgressive hybridization. In this context, the genetic contrast between farmed/bred strains and wild Nile tilapia populations in the major lakes of Uganda remains understudied. Understanding the genetic structure of Nile tilapia populations in the major water bodies of Uganda (lakes Victoria, Kyoga, Edward, George, Albert and Nile River) is a key resource to guide selective breeding programmes, thus minimizing the effects of maladaptation under both aquaculture and natural stocks. Although the population genetics of Nile tilapia in Uganda's major lakes have been studied, this was based on limited sampling scope, especially in the wild, and the key information on the species could have been overlooked. We fill this knowledge gap by genotyping 756 Nile tilapia individuals from multiple populations for each major water body of Uganda using a panel of 34 microsatellite loci based on the microsatellite genotyping‐by‐sequencing (SSR‐GBS) technique. The results indicate two discrete gene pools/stocks: the Edward‐George system and the Albert‐Kyoga system‐Victoria. Evidence of loss of genetic diversity and admixture of some Nile tilapia stocks was found, most likely resulting from anthropogenic perturbations. This study contributes useful information key for understanding the potential Nile tilapia broodstock sources for selective breeding programmes, aimed at improving aquaculture production in Uganda.
... They found that water hyacinth covered 8.2% of the lake area in 2019, and that water hyacinth density was positively correlated with chlorophyll-a concentration and turbidity. [40] . Wind and water also influence the spread of the weed during wet season. ...
... However, according to Dersseh Melesse et al. (2020)[39] the top coverage changed slightly from October 2016 and 2017 to December 2018 and 2019. Under favorable conditions, water hyacinths can double their area coverage in just 5 days, as stated byNtiba et al. (2001) ...
... Their feeding habits and high reproductive rates have resulted in increased competition for resources with native fish species. This has led to changes in the relative abundance and distribution of different fish populations, potentially displacing or reducing the numbers of native species [19,20]. Moreover, the introduction of Tilapiines has led to changes in the lake's nutrient dynamics. ...
... The absence of natural predators and competitors in the lake has further facilitated its uncontrolled growth. Water hyacinth thrives in eutrophic conditions, taking advantage of high nutrient levels resulting from agricultural runoff and untreated sewage discharge [20]. The proliferation of water hyacinth has had severe ecological consequences in Lake Victoria. ...
Fish have been deliberately introduced into new ecosystems as a management tool, to argument overfished native stocks, to occupy vacant niches, and to create lucrative commercial fisheries. Lake Victoria has witnessed successful introductions of predatory Nile perch, Lates niloticus and four Tilapiine species (including Nile tilapia, Oreochromis niloticus, Tilapia zilii, and Oreochromis leucostictus). These introductions have negatively and positively impacted the fishery potential and ecology of native fisheries in the lake. The predation of native species by the voracious Nile perch has contributed to decimation and virtual disappearance of over 300 species of Haplochromines. In addition, competition for feeding and breeding areas and interspecific hybridization between exotic O. niloticus and the native Tilapiines have also yielded undesirable results such as disappearance of native Oreochromis esculentus. The most successful invasive plant introductions have been water hyacinth, Eichhornia crassipes, Nile cabbage, Pistia stratiotes, and dense waterweed, Egeria densa. Proliferation of water hyacinth has led to increased shading and turbidity. The introduced species have manifested more pronounced deleterious effects on the native fisheries and their ecology in Lake Victoria. Therefore, future introductions of new species should be based on sound scientific research in order to minimize their unprecedented impacts in the new ecosystems.
... Consequently, loss of water quality and biological diversity threaten the well-being of millions of lake side riparian communities. This is because studies have shown that portable water supply by relevant authorities is less than 60% hence, most people use the water directly without prior treatment (Ntiba et al., 2001;Njiru et al., 2008;Kobingi et al., 2009;Masese et al., 2009b). The major cause of degradation is increased intensity of agriculture and deforestation coupled with the rapid growth of urban centers and industrial activities that have been linked to increasing magnitude and frequency of run-off events (Mutie, 2006;Mati et al., 2008), pesticide contamination (Osano et al., 2003), reduced base flow (GEF, 2004), erosion and sedimentation of streams and rivers (Mutie, 2006). ...
... Overall, the hydrological characteristics of flow and water retention have been altered resulting in massive and destructive flooding in the lowlands during spates (UNEP, 2003;Kadomura, 2005). As a result, these activities have led to sedimentation and eutrophication that have not only affected domestic and industrial water supply (Ntiba et al., 2001), but also led to massive fish kills and proliferation of the water hyacinth (Eichhornia crassipes) (Gichuki, 2000;Lung'aiya et al., 2000;Mugidde et al., 2005;Wawire and Ochiel, 2005;Njiru et al., 2008). ...
... The lake is at an altitude of 1135 m above sea level and lies on the between latitude 0.7 • 'N-3 • 'S and longitude 31.8 • 'E-34.8 • 'E 6,7 . Annual rainfall in the lake area varies between 950 and 2450 mm and on the terrestrial part of the basin, it ranges from 450 to 950 mm. ...
... The contribution of haplochromines fish biomass in the lake decreased from 80% to less than 1% within a decade from 1970 and1980 47 11,49 . There are about 35 fish fillet processing factories operating within the lakeshore cities which have created high demands for fish landing 7,50 . Artisanal fishermen cannot compete with commercial fishers because of the poor fishing gear they use 51 . ...
For the countries within the Lake Victoria basin, sustainably managing it is critical to the harmonious survival of a vast array of biodiversity. The abundance of resources in and around the lake provides various vital ecosystem services (like food, transport, nutrient cycling, tourism, climate regulation as well as disease and flood control) for humans and countless other species. However, decades of unsustainable development practices combined with unchecked population growth are diminishing the lakes' productivity and threatening its very existence. Eutrophication, proliferation of alien species, water pollution, inappropriate fishing techniques, and climate change are among some of the anthropogenic and natural threats that are besieging Lake Victoria. In light of recent exploration and exploitation of minerals, oil, and gas further degradation of the watershed is not only eminent but a surety. However, to date the institutions mandated with the regional management of the basin have fallen short of their expectations and literature pertaining to the basin's management is quite outdated. There is urgent need to draw attention to the cause-effect relationship between the driving forces-pressures-state-impacts-responses, that diminish sustainable utilization and development of Lake Victoria. Using this indicator-based approach clearly highlights the nexus between the environmental metrics and anthropogenic interactions making decisions for practice and policy-making more sustainable. Overall, the need for robust integrated water management policies within the riparian countries is critical to simultaneously address conservation and development which are paramount in ensuring sustainable development and enhancing the lake's productivity. Sensitization and capacity building within the communities utilizing the lake as a primary source of income will mitigate detrimental impacts from unsustainable usage. More so, appropriate incentives and fines to deter pollution and illegal reclamation of wetlands and forests will promote regeneration of the ecosystem and recovery in the long term.
... The lake is shared by three of the East African countries: Uganda (45%), Kenya (6%) and Tanzania (49%). With approximately 30 million people living within its catchment area (Ntiba et al. 2001), people carry out a number of economic activities (fishing, agriculture, forestry, transport and tourism). The lake's natural resources in terms of its waters and immense biodiversity base, serve not only the people of East Africa, but also the world in general. ...
... They comprise beaches, resorts, hotels, camping sites, botanical gardens and conservation areas with activities ranging from water jet skiing and canoeing to sun bathing and nature walks. Tourism, like the other economic activities, (fishing and agriculture) is threatened by unsustainable use of natural resources which has led to overfishing, water pollution (from industries, urban waste and agriculture sources), wetland reclamation, invasion of noxious waterweeds and other associated problems (Ntiba et al. 2001, LVEMP 2005. To address these challenges, trans-national bodies have been set up to coordinate resource use and management among the three countries. ...
Tourism in Uganda has over the years witnessed an increase in tourist arrivals which has resulted in the development of a number of tourist facilities and destinations. Although studies have been conducted to examine the development of tourism in Uganda, limited attention has been given to Lake Tourism, especially with respect to tourism planning from a spatial and temporal perspective. This paper focuses on the Lake Victoria shore region where it identifies the tourism establishments, analyses their spatial and temporal trend and examines the implication on tourism planning of the lakeshore region. Using qualitative, quantitative and geo-spatial techniques data was collected and analysed using nearest-neighbour tool, Chi Square and ANOVA tests. The results indicate that: the
lakeshore region has a variety of tourism sites, majority of whom are beach resorts (without accommodation facilities); they have been increasing in number and size over the years; and attract an increasing number of visitors. Spatial analysis revealed that there is a tendency of the sites clustering near the urban than in the peri urban areas. This implies that tourism planning of the lakeshore should ensure that resources are sustainable utilised as tourism ‘hot spots’ begin to develop around the clustering areas, which are already experiencing an increasing number of sites and visitors. The study
recommends a pro-active planning approach, which incorporates spatial and temporal aspects to ensure sustainable tourism development along the lakeshore region.
... Consequently, loss of water quality and biological diversity threaten the well-being of millions of lake side riparian communities. This is because studies have shown that portable water supply by relevant authorities is less than 60% hence, most people use the water directly without prior treatment (Ntiba et al., 2001;Njiru et al., 2008;Kobingi et al., 2009;Masese et al., 2009b). The major cause of degradation is increased intensity of agriculture and deforestation coupled with the rapid growth of urban centers and industrial activities that have been linked to increasing magnitude and frequency of run-off events (Mutie, 2006;Mati et al., 2008), pesticide contamination (Osano et al., 2003), reduced base flow (GEF, 2004), erosion and sedimentation of streams and rivers (Mutie, 2006). ...
... Overall, the hydrological characteristics of flow and water retention have been altered resulting in massive and destructive flooding in the lowlands during spates (UNEP, 2003;Kadomura, 2005). As a result, these activities have led to sedimentation and eutrophication that have not only affected domestic and industrial water supply (Ntiba et al., 2001), but also led to massive fish kills and proliferation of the water hyacinth (Eichhornia crassipes) (Gichuki, 2000;Lung'aiya et al., 2000;Mugidde et al., 2005;Wawire and Ochiel, 2005;Njiru et al., 2008). ...
The degradation of freshwater systems is on the increase due to anthropogenic activities. In the recent past, there has been a rapid shift of assessment and monitoring from the conventional methods to biomonitoring of these ecosystems globally. Although, an organism's response to degradation varies, little is known as far as their sensitivities are concerned. The aim of this study, therefore, was to assess the life cycle responses of the midge of Chironomus species (Diptera: Chironomidae) to sugarcane and paper pulp effluents exposure. This is in order to ascertain their use in the monitoring of freshwater ecosystems. Fourth instar of Chironomid midges were sampled at two locations on the Rivers Nzoia and Mbogo. River Mbogo is a tributary joining River Nyando within the Lake Victoria Basin. All midges were taken to the laboratory on the same day of collection and acclimatized in a controlled climate room for 24 hours. They were then exposed to the effluent dilutions (i.e. 100%, 50%, 25%, 12.5% and lastly 6.25%) collected from Webuye Paper Mill Factory and Chemelil Sugar Factory treatment ponds/lagoons. A completely randomized experimental design was employed in which ten midges were placed in each of the treatments replicated four times and the experiment ran for 28 days. It was found that emergence of the Chironomus species decreased with an increase in the effluent concentration. An increase in effluent concentration, led to a delay in emergence of chironomids over time. However, there was no significant difference (p<0.05) between the emergence of Chironomus species exposed to the two effluents. Emergence is one of the most sensitive endpoints in toxicological studies. This is because effects on emergence involve three moultings and the very complex pupation process. Therefore, not all surviving larvae would have managed to undergo all the four stages of their life cycle due to adverse effects of the effluents. The study concluded that pulp paper and sugar cane effluents delayed the development of life cycle stages of Chironomus species and it was recommended that life cycle stages of the midges, Chironomus species can be a good indicator of environmental degradation.
... This region is distinguished by notable physiographic features, including Lake Victoria, which is shared among Kenya (6%), Uganda (45%), and Tanzania (49%). As the largest Lake in Africa, Lake Victoria, along with other sizable inland water bodies, plays a role in regulating moisture distribution in the region [43] and serves as a vital livelihood for the population of the region [44]. Additionally, this region boasts prominent geographical landmarks such as the Rif Valley and Africa's highest elevations, including Mt. Kilimanjaro (>5885 m), Mt. ...
This study evaluated the effectiveness of the NASA Earth Exchange Global Daily Downscaled models from CMIP6 experiments (hereafter; NEX-GDDP-CMIP6) in reproducing observed precipitation and temperature across East Africa (EA) from 1981 to 2014. Additionally, climate changes were estimated under various emission scenarios, namely low (SSP1-2.6), medium (SSP2-4.5), and high (SSP5-8.5) scenarios. Multiple robust statistics metrics, the Taylor diagram, and interannual variability skill (IVS) were employed to identify the best-performing models. Significant trends in future precipitation and temperature are evaluated using the Mann-Kendall and Sen’s slope estimator tests. The results highlighted IPSL-CM6A-LR, EC-Earth3, CanESM5, and INM-CM4-8 as the best-performing models for annual and March to May (MAM) precipitation and temperature respectively. By the end of this century, MAM precipitation and temperature are projected to increase by 40% and 4.5 °C, respectively, under SSP5-8.5. Conversely, a decrease in MAM precipitation and temperature of 5% and 0.8 °C was projected under SSP2-4.5 and SSP1-2.6, respectively. Long-term mean precipitation increased in all climate scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5), with near-term MAM precipitation showing a 5% decrease in Rwanda, Burundi, Uganda, and some parts of Tanzania. Under the SSP5-8.5 scenario, temperature rise exceeded 2–6 °C in most regions across the area, with the fastest warming trend of over 6 °C observed in diverse areas. Thus, high greenhouse gas (GHG) emission scenarios can be very harmful to EA and further GHG control is needed.
... A considerable proportion of the respondents (63.3%) perceived the water quality in Lake Victoria to be "very low," while a majority (53.3%) expressed moderate concern about water pollution. These perceptions are consistent with previous studies highlighting increasing concerns about Lake Victoria's water quality degradation due to anthropogenic activities (Barakagira and de Wit, 2019; Barakagira and de Wit, 2017;Ntiba et al., 2001;Sitoki, et al., 2010;Twesigye et al., 2011;Kavuma and Barakagira, 2024). The high level of agreement (48.0%) about changes in water color and strong concern (39.3%) regarding the presence of suspended solid waste further emphasize the community's awareness of environmental changes, particularly those linked to pollution and eutrophication. ...
Lakes serve as vital ecosystems, providing freshwater resources and habitats for diverse species. However, human activities, particularly around lakeshores, have led to significant environmental degradation, including heavy metal contamination. Lake Victoria, the second-largest freshwater lake globally, has been severely impacted by pollution from industrial, agricultural, and urban sources. This research aims at examining the influence of the anthropogenic activities on the water quality of Lake Victoria. Specifically, the study tried to determine the activities undertaken at the Lake shores of Lake Victoria; determined the physico-chemical parameters of the water from the shores and the heavy metal concentration in the water samples obtained from the shores of Lake Victoria. This study utilized a cross-sectional and experimental research designs to assess water quality and anthropogenic influences around Lake Victoria. A total of 150 residents from selected communities were surveyed using a semi-structured questionnaire to gather demographic information, perceptions of water quality and the activities carried out within the shores of Lake Victoria. Water samples were collected from multiple sites along the lake shores for analysis of heavy metals using the Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Water quality parameters were determined In-situ using a multi-parameter water testing kit and Hanna instrument. Results showed that the anthropogenic activities that could have contributed to water degradation include: fishing, transport, agriculture and construction among others. Apart from pH which was outside the permissible limits, all the other water parameters were within the WHO permissible limits. Considering the heavy metal concentration, all the sampled sites apart from one inlet, had the concentrations above the WHO permissible levels an indication of significant heavy metal contamination in the Lake Victoria shores. These findings highlight the urgent need for targeted pollution control measures and regular monitoring to mitigate further environmental degradation. Effective interventions, including stricter regulations and sustainable land use practices within the Victoria shores are essential for safeguarding the lake's ecosystem and the health of surrounding communities.
... In tropical and subtropical areas, the uncontrolled presence of water hyacinth in waters has a negative impact on fisheries, navigation, hydropower, irrigation, and recreation activities in reservoirs. The conditions under water hyacinth cover become anoxic due to dead plant remains (15) . The presence of water hyacinth has an economic impact, reducing fishermen's income and increasing transportation costs (16) . ...
Water vegetation in lakes or reservoirs can change the water's ecology. Water vegetation in Jatiluhur Reservoirs is dominated by water hyacinth (Eichhornia crassipes). Water hyacinth in lakes or reservoirs becomes an invasive weed that can cause ecological degradation. Jatiluhur Reservoir is one of the water bodies affected by the uncontrolled growth of water vegetation. The study was conducted to determine the spatial and temporal distribution patterns of water vegetation and its effect on Jatiluhur Reservoir. Water vegetation's spatial and temporal distribution was analyzed using Sentinel-2A satellite image data. The Normalized Difference Vegetation Index (NDVI) algorithm was used to see the distribution of water vegetation in the reservoir waters. The observations show that the movement of water vegetation starts from the inlet area and then moves along with the flow of water to the center of the reservoir. Finally, it accumulates in the outlet area. The correlation between vegetation cover area and month of observation obtained the equation y=662.5x + 128.1. Based on the equation, the increasing vegetation cover area in the Jatiluhur Reservoir is predicted to reach 128.1 ha per month. The physical method used for controlling the growth and distribution of vegetation (water hyacinth) in Jatiluhur Reservoir by taking in the waters. Efforts to control vegetation physically must notice the increasing rate of water hyacinth distribution.
... Additionally, leaf meal from Eichhornia crassipes (water hyacinth) may be a perfect alternative feed ingredient due to their good nutritive value (Sarker and Aziz, 2020) and plenty of availability (Saha and Ray, 2011) as the proliferation rate is speedy, and within five days, it can be double (Ntiba et al., 2001;Ojeifo et al., 2002). The dry matter, crude protein, ether extract, crude fibre, nitrogen-free extract, and total ash contents in the Indian water hyacinth leaf meal is reported to be 90. ...
... T A B L E 6 Pearson correlation matrix generated using 11 measured parameters and WQI as parameter (a: p The remarkable variation in turbidity between stations highlighted the effect of human disturbance in the lake's watershed and along the shores of Lake Kivu. These variations in turbidity, the only parameter that showed a highly significant negative correlation with the WQI, are related to the observations made along the shores of other lakes of the Albertine Rift, such as Lake Victoria (Ntiba et al., 2001;Odada et al., 2004;Odada et al., 2006) and Lake Tanganyika (Hecky, 1993). In fact, high population growth and associated activities not only increase domestic water uses, but also contribute to an increase in discharges of waste and pollutants of all kinds that affect water quality in lake littoral areas (Bootsma & Hecky, 1993;Busch et al., 2018;Cohen et al., 1993;Palacios-Fest et al., 2005). ...
... This increases competition for food among native fish species, some of which have specialized diets or depend on specific food sources. The depletion of these resources can lead to reduced populations and even local extinctions of native species, disrupting the natural balance of the ecosystem [12]. ...
Lake Victoria, one of Africa's largest freshwater lakes, has been severely impacted by invasive species, leading to significant ecological changes and threatening the region's biodiversity and socioeconomic well-being. Two prominent invasive species in Lake Victoria are the Nile Tilapia (Oreochromis niloticus) and water hyacinth (Eichhornia crassipes). The introduction of the Nile Tilapia has disrupted the native fish community through competition, predation, and habitat alteration, resulting in declines in native species and altering the trophic dynamics of the ecosystem. Water hyacinth, on the other hand, forms dense mats that impede sunlight penetration, reduce water quality, and hinder the movement of native species. These invasive species have cascading effects on the lake's food web, water clarity, oxygen levels, and overall ecosystem health. Addressing the impacts of invasive species in Lake Victoria requires integrated management approaches that combine prevention, early detection, and control measures. Strategies such as mechanical removal, biological control, and targeted herbicide use have been employed to mitigate the spread and impact of invasive species. Additionally, habitat restoration and public awareness initiatives are crucial for long-term conservation and sustainable management of the lake. Continuous scientific research and monitoring efforts are necessary to understand the dynamics of invasive species and their impacts, as well as to evaluate the effectiveness of management strategies. Efforts to combat invasive species in Lake Victoria should be undertaken in a collaborative manner, involving government agencies, researchers, local communities, and other stakeholders. By implementing comprehensive management plans and promoting responsible practices, it is possible to restore the ecological balance of Lake Victoria, protect its rich biodiversity, and safeguard the livelihoods of communities that depend on its resources.
... As a result of the high human population and its continued growth in the basin, waste disposal has been a major challenge for many municipalities. Many small towns along streams, rivers, and shores of Lake Victoria lack proper solid waste management and sewage systems (Calamari et al., 1995;Nyenje et al., 2010), while those with sewage services are operating above capacity (Juma et al., 2014;Ntiba et al., 2001). Scheren et al. (2000) showed that BOD load is highest on the Kenyan side, and that domestic BOD loads exceed industrial loads in all regions (although it is noted that industrial loads will contribute to a higher chemical oxygen demand). ...
Over 42 million people rely on Lake Victoria as their primary source of food, employment, and clean drinking water. The lake's fisheries have produced around one million tonnes in recent years, but the lake's growing population has resulted in a lower catch rate per capita. And the lake and its catchment have been negatively impacted by a wide variety of human activities, such as overfishing, oil spills, discharge of untreated waste, spread of invasive species, over-abstraction of water from the lake basin, and climate change, among other drivers of change. This paper presents existing research gaps, existing capacity, and presents a way forward for priority research on issues ranging from fish and fisheries, biodiversity , pollution, invasive species, aquaculture, human population growth and socio-economics, land use changes, habitat degradation, climate change and skills and knowledge. The purpose of this paper is to document: information that is currently available from previous research; the existing scientific capacity ; and the resources required to guarantee that Lake Victoria becomes a heathy and biologically diverse resource for the millions of people who are dependent on it. It is clear from this synthesis that the biological , social, and economic benefits that can be derived from Lake Victoria can only be accomplished through the utilization of multidisciplinary approaches in the research and monitoring of both basin-wide and lake-wide biophysical processes, as well as the modeling of all potential interactions between the ecology of the basin and the lake. Ó
... It was linked to increased farming activities and soil erosion in the catchments of major influent rivers in the 1950s and 1960s that led to increased nutrient loading into the lake (Verschuren et al., 2002;Gichuki et al., 2006). Untreated municipal waste from the riparian cities/towns is also responsible for eutrophication in the lake as the construction of sewerage facilities for the treatment of municipal waste has not kept pace with the growing human population (Gichuki et al., 2006;Scheren et al., 2001;Ntiba et al., 2001). ...
Lake Victoria is the second largest freshwater lake in the world that was once a biodiversity hotspot hosting over 500 endemic haplochromine cichlids that were later decimated by exotic introductions and anthropogenically driven environmental and ecological changes. The environmental and ecological changes in the lake over the years have been attributed to overfishing, eutrophication, introduction of exotic species, pollution and possibly climate change. The lake's capture fishery, which is the main economic activity directly and indirectly supporting over 40 million people, has continued to decline after experiencing a boom between the 1970s and 1990s following the introduction of Nile Perch (Lates niloticus) and Nile Tilapia (Oreochromis niloticus). In order to augment capture fisheries from the lake, cage culture was introduced in the year 2005, but its sustainability and influence on the ecology of the lake are not well understood. In this review, we examine the genesis of degradation of Lake Victoria and assess the role of cage culture as both a solution to the current situation and a cause for concern for the ecology of the lake. To compile this review, we utilized data in the grey and published literature. Studies show that the degradation of the lake can be traced back to the 1930s when the trophic status and ecology of the lake started showing signs of anthropogenic influence. The Nile Perch was introduced in early 1960s to replenish the fishery but its ecological impacts were felt in 1970s and 1980s when the native haplochromine species started to disappear from catches. Progressively, the ecological changes and management concerns in the lake have become a complex mix of exotic species introductions, eutrophication, and overfishing. In this mix of persistent ecological changes, the once thriving capture fisheries revolving around the two exotic species (L. niloticus and O. niloticus) have significantly declined threatening the livelihoods of millions of people directly and indirectly involved in the fisheries. These declines necessitated the introduction of cage culture in 2005 to fill the increasing demand for fish from the lake. Ever since, cage numbers have increased tremendously (>6 000 by 2020) and is now operated by over 60 different firms which are owned either individually or by groups. Over 70% of the cages have been installed in shallow areas within the Winam Gulf which goes against the guidelines on cage installation 1
... East African inland fisheries predominantly rely on major freshwater bodies, notably Lake Victoria, the world's secondlargest freshwater body (Getabu et al. 2003). The capture fisheries from Lake Victoria alone contribute US$250 000-US$500 000 annually to three greater East African states (Uganda, Kenya and Tanzania) from exports alone (Ntiba et al. 2001;Scullion 2007). ...
The Nile tilapia (Oreochromis niloticus) is the second-most economically important fish species in East African countries (EAC), surpassed only by the Nile perch (Lates niloticus). It is the most-farmed freshwater fish species in EAC and the second-most-farmed worldwide. Currently, in EAC, through direct stocking activities and likely indirectly via aquaculture escapees, Nile tilapia are present in waterbodies where it is not native and where it is thought to have contributed to the fish biodiversity loss observed in recent decades. Introduced Nile tilapia may hybridise with native, congeneric species, promoting genetic introgression that can be detrimental to the sustainability of biodiversity. Moreover, the translocation dynamics and escapes from aquaculture can contribute to artificial geneflow between Nile tilapia stocks, compromising their gene pool and the sustainability of the species as a fishery resource. In the current work, we review some examples of these phenomena in EAC. Additionally, we explore the importance of collecting genetic data to define baseline knowledge for native and non-native Nile tilapia populations that can be used in monitoring programmes for development, management and conservation of tilapia genetic resources.
... It is part of depression within the East African Great Rift Valley, between two mountain ranges, generally running north-south, on both sides and one of Africa's great lakes. The lake is bounded by latitudes 0.5o N and 2.5o S and longitudes 32o E and 34o E covering an area of 69,000 km2 (Semazzi, 2011), but it is also one of the shallowest; the bathymetry within the lake Many people in the region rely on the lake for food, water, income, and energy (World Bank, 2015), and it has long served as a convenient method to travel between the three nations via boat transport (Ntiba, Kudoja, and Mukasa, 2001). ...
The objective of this study was to explore lake and land breezes over the Lake Victoria basin based on 2 years (2019 to 2020). Hourly and daily data of wind speed and direction, precipitation, 2-meter air temperature over land, and Lake mix-layer depth obtained from Era 5 re-analysis were utilized. The method employed was based on the characteristics of the lake breeze with the elimination of the days with strong synoptic winds. According to the results, the main drivers for the breeze development at the meteorological stations were the thermal gradient between the lake and the surroundings and the low-level winds. The breezes mainly occur between 9:00 h and 15:00 h characterized by divergence over the lake and reduction in temperature and they move over land. The study calls for a look at the factors that may contribute to the formation of the breezes.
... Freshwater tropical lakes in Africa are among the most biologically productive lakes globally [9]. Equatorial Lake Victoria is the second-largest freshwater lake globally by surface area and the largest freshwater lake in Africa, with a surface area of 69,000 km 2 [10] and a catchment area of 284,000 km 2 [11]. Lake Victoria is large enough to create its weather system and influence regional climate [10; 12]. ...
Lake Victoria is the second-largest freshwater lake in the world, with an eco-system critical to 25-30 million inhabitants of Kenya, Uganda, Tanzania, Rwanda, and Burundi who live in the lake basin. The lake provides several ecosystem services from inland waterway transport, fisheries to hydropower and supports many different industries such as tourism, trade, and wildlife. However, Lake Victorias ecosystem management has been highly extractive; hence its water resources are either inefficiently or overused. This is because the value of this resource is either unknown or underestimated. The main purpose of the research was to contribute to Lake Victorias conservation efforts by providing the best techniques that can be used to assess the value of this resource and develop appropriate policies for the sustainable management of the lake. The study reviewed relevant literature on the economic assessment methods of environmental resources in the context of water management. Search engines such as Google Scholar, Web of Science, and ScienceDirect were used for it. The study suggests methods for economic valuation of Lake Victoria water ecosystem for each service. The proposed techniques can be used for assessing the value and benefits of conservation and restoration of Lake Victoria ecosystem.
... The lake fisheries are important livelihood sources that provide food and employment (Ntiba et al., 2001). Lake Victoria is the principal inland fishery, with a five-year cycle average production of about 90,000 tonnes landed and valued at about US$ 90 million in Kenya alone Njiru et al., 2018). ...
Fisheries governance uses policy and statutory documents to improve governance on fish ecology, harvesting, trade and consumption by identifying and addressing gaps regarding inefficiencies, inequity and post‐harvest losses. The current study examines existing policies and institutional documents on fisheries, health and trade to assess the level of inclusion of small indigenous fish species (SIS), especially Omena, as a means of guiding governance interventions for sustained livelihoods of fishing communities in Lake Victoria. A content‐analysis review was conducted on all the fisheries and nutritional policy documents related to Lake Victoria fishery to ascertain the need for their integration into fisheries governance. From the scoring scale, where zero (0) implies no integration and three (3) implies high integration, the study results indicated very low levels of integration across health, fisheries and trade relating to small fish species. Further, the management plans and regulations/guidelines exhibited a relatively higher level of integration than did policies and laws. There is need for a more targeted approach for streamlining the existing policy documents to realize the untapped potential contribution of SIS towards food and nutritional security.
... Although the Lake Victoria Fisheries Organization (LVFO) has tried to harmonize regulations for fisheries management in Lake Victoria, differences do occur across the three riparian countries. For instance, closed season for Rastrineobola argentea (dagaa) is only observed in Kenya from 1st April to 31st July (Ntiba et al., 2001), and monofilament gill nets are banned in Kenya and Tanzania, but allowed in Uganda (Njiru et al., 2008). ...
... As represented in Figure 3, the total capacity of Africa's river basins, freshwater bodies, riparian areas, wetlands and groundwater reservoirs is approximately twice that of North America [21][22][23][24]. With a total land area of roughly 68,800 km 2 , Lake Victoria, Africa's widest lake, the second-largest globally freshwater lake, ranked after Lake Superior, is vast in size (with a water volume of approximately 2500 km 3 even though it is a little shallow. ...
Human activities mostly impact the trend and direction of rainwater, groundwater, and other river basin resources in the watershed in Africa. These activities alter river flows and the quality of usable water supplies at both highlands and lowlands. A watershed is indeed a conserved area of land that collects rain, sleet and snow, and empties or penetrates groundwater sources. The act of managing the activities around the watershed is integrated watershed management, which considers the social, economic, and environmental issues in tandem with the human, institutional, natural, and sustainability systems, which are the key drivers as identified in this study, as well as community interests and participation, to manage groundwater resources sustainably. These watersheds, river basins, and groundwater resources provide important services for communities and biodiversity. This paper reveals that the best way to protect groundwater resources is on a watershed basis using sustainable management measures. This technique enables us to handle a variety of concerns and objectives while also allowing us to plan in a complicated and uncertain environment. Sustaining a regional and sub-regional watershed involves cooperation and participation from a wide range of community interests and water users, including municipalities, companies, people, agencies, and landowners, for stakeholders’ input to be successful. All of the strategies and plans are produced with regard to one another, as well as the overall conditions of the watershed, local land uses, and specific regional transboundary issues.
... Fishers' income is determined by the quantity of fish they catch and the price obtained for it; thus, if the fishery is managed well, it will contribute to driving income poverty down (Nyeko 2004;Bavinck 2009;McGregor 2009;Coulthard et al. 2011;Weeratunge et al. 2014). Building on these facts, Lake Victoria provides open access to anyone to fish in it, subject to existing fishery regulations (Ntiba et al. 2001;Eggert & Ellegård 2003;Ogello et al. 2013). This study therefore conceptualises that the existing income poverty among communities in Lake Victoria will lead to Nile perch overfishing because of the open-access nature of the lake and the lack of income diversification activities. ...
Despite the crucial role played by Nile perch in the income of fishers around Lake Victoria, Tanzania, fishing pressure has increased in recent years and has led to overfishing and, consequently, a risk to the lake’s future sustainability and the fishers’ livelihoods. This study used data collected in 2018 from 268 randomly selected sample fishers at 10 landing sites across Lake Victoria. In conjunction with the endogenous switching regression model, the potential impact of Nile perch overfishing on the fishers’ income per fishing trip in Lake Victoria was evaluated. The results show that there is a significant difference in the socio-economic, institutional and fishing effort characteristics of Nile perch fishers who overfish and those who do not. In particular, Nile perch fishers who overfish earn significantly higher incomes per fishing trip than fishers who do not overfish. The study recommends the need for policy makers to develop policies that acknowledge the dynamics of socio-economic, institutional and fishing effort factors. In addition, more flexible fish quota restrictions and consistent fishing patrols need to be enforced to ensure compliance with fishery regulations. These measures should promote a balance between the sustainability of fishery resources and an improved income for Nile perch fishers in Lake Victoria.
... T A B L E 6 Pearson correlation matrix generated using 11 measured parameters and WQI as parameter (a: p The remarkable variation in turbidity between stations highlighted the effect of human disturbance in the lake's watershed and along the shores of Lake Kivu. These variations in turbidity, the only parameter that showed a highly significant negative correlation with the WQI, are related to the observations made along the shores of other lakes of the Albertine Rift, such as Lake Victoria (Ntiba et al., 2001;Odada et al., 2004;Odada et al., 2006) and Lake Tanganyika (Hecky, 1993). In fact, high population growth and associated activities not only increase domestic water uses, but also contribute to an increase in discharges of waste and pollutants of all kinds that affect water quality in lake littoral areas (Bootsma & Hecky, 1993;Busch et al., 2018;Cohen et al., 1993;Palacios-Fest et al., 2005). ...
Freshwater ecosystems provide many services such as moderation of the local microclimate and a source of water and food for riparian communities. It is also a preferred habitat for many organisms such as plankton, benthic macroinvertebrates and fish. However, these ecosystems are among the most affected by various anthropogenic threats that modify water quality and ecological processes, thus affecting biodiversity. The objective of this study was the spatio‐temporal characterization of physico‐chemical littoral water parameters and the assessment of anthropogenic disturbance on the littoral zone by a water quality index (WQI). Physico‐chemical water quality data including temperature, dissolved oxygen, conductivity, pH, TDS, turbidity, SiO 2 , PO 4 ³⁻ , NO 2 ⁻ , and NH 4 ⁺ were collected from January to December 2018. They were used to calculate the WQI to assess water quality according to aquatic life, using limits values of Canadian Council of Ministers of the Environment (CCME), United States Environmental Protection Agency (USEPA) and Australian and New Zeland Environment and Conservation Council (ANZECC). PO 4 ³⁻ is out of range in all the stations while NO 2 ⁻ and Turbidity are out of range in some of the anthropized stations according to ANZECC, CCME, and USEPA recommended values for aquatic life. The WQI values range from medium to good and the high WQI values obtained in the non‐anthropized stations that reflect the negative influence of human disturbance on water quality in the Lake littoral zone. The results suggest the need for an integrated lake watershed management system in order to maintain the ecological functions of the lake and support livelihoods from the lake.
... According to [5], in most developing countries including Nigeria, anthropogenic activi-ties of different kind such as bathing and washing, indiscriminate dumping and direct discharge of untreated waste including human feaces around the shoreline and into nearby rivers, streams and into creek, contaminate surface water directly and in turn contrib-ute to increase in microbial pollution. Other negative effects in-clude nutrient enrichment, deterioration of the water quality, and destruction of spawning grounds for aquatic and marine life [6]. ...
... The introduction of seven exotic fish species and the surge of clupeids that are originally marine fish, have become one of the biggest challenges to the lake management authorities and fisheries biologists in Bangladesh. This is somewhat similar to the case in Lake Victoria in East Africa, where despite an increased fish yield, over 200 fish species were lost after introducing Nile perch, Lates niloticus (Linnaeus, 1758) (Ntiba et al., 2001). Kohinoor et al. (1998) observed adverse effects on the overall growth and yield of carp in polyculture with mola carplet (A. ...
Kaptai Lake (KL), the largest artificial lake in Bangladesh, supports an important inland open water fishery. Nevertheless, detailed studies on its fish diversity and environmental threats are still limited. Hence, a study was conducted to evaluate the current fish management scenarios, fish production, relative abundance to improve the production and biodiversity of KL. Data were collected from stakeholders through personal observation, focus group discussions, and cross-check interviews from September 2018 to July 2019. The fish production of KL increased from 1,200 metric tons (MT) in 1965-1966 to 10,577 MT in 2018-2019. The output of the lake was dominated by small fish remarkably, Gudusia chapra (Hamilton, 1822), Gonialosa manmina (Hamilton, 1822), and Corica soborna Hamilton, 1822, accounting for 64 % of the total production in 2018-2019. A total of seventy-six fish species were observed under ten orders, including seven exotic fish species. According to the IUCN Bangladesh, 14 % of total species were identified as vulnerable, 11 % as endangered, 3 % as critically endangered, 11 % as near threatened and 51 % as least concern. The study also identified that climate change and various human-driven causes threaten the fish production and biodiversity of this lake. These findings suggest that community-based fisheries management, protection of natural breeding grounds of carps, control of pollution, amendment of existing fishing laws, and collaborative research would be a necessary approach for mitigating the negative environmental impact of this lake. The overall practical knowledge of this investigation could assist in policymaking and further research.
... The study was conducted along Lake Victoria shoreline in Magu district, Tanzania which is among the seven districts in Mwanza region involved in fishery activities along Lake Victoria (DADPs, 2009(DADPs, /2010 (Ntiba et al., 2001), is not mentioned in the refernces list occupying an area of about 15,000 ha. The data for this study was collected from Ihale, Nyamikoma and Nyakaboja landing sites ( Figure 1). ...
This study was conducted to assess body size distribution and Catch Per Unit Effort (CPUE) of Nile perch (Lates cf. niloticus) captured using three common fishing gears at Magu district in Tanzania. Three landing sites along Lake Victoria were selected for this assessment. Each site was visited twice per week for two months. At each site 10 boats were identified based on the gear used and randomly selected for fish count. Ten fish per boat were taken for weight and length measurements. The results show that the main fishing gears used to catch fish at all sites were gillnet (GN), long line (LL) and beach seine (BS). Mean length of captured fish recorded from each gear were 33.7, 41.5 and 43.8 for beach seine, gillnets and long lines respectively, which was below the minimal required length of 50 cm. Large proportion of small landed fish were observed in vessels fishing with beach seine, this was due to illegal nature of the beach seine, where by fishermen used small mesh sizes of 10 mm to 12 mm. However, beach seine had higher CPUE (kg/gear/day) (44.9) and gillnet had the lowest (22.6). This study revealed that the mean length from all sites were below the legal minimum size required by the Tanzanian government, suggesting that all beaches are involves in over exploration of fish.
... Although authorities in Kenya acknowledge the need to reduce sediment pollution, the linkages between land use change and changes in sediment dynamics in the headwater catchments are not well quantified (Nyssen et al., 2004;Vanmaercke et al., 2010Vanmaercke et al., , 2014. There are limited data on sediment export for montane catchments in Sub-Saharan Africa in general and in East Africa in particular (Ntiba et al., 2001;Walling & Webb, 1996). Clearly, this is a significant gap in our knowledge of these environments that requires empirical measurements to address it. ...
Land use change is known to affect suspended sediment fluxes in headwater catchments. There is however limited empirical evidence of the magnitude of these effects for montane catchments in East Africa. We collected a unique 4-year high-frequency data set and assessed seasonal sediment variation, water pathways, and sediment response to hydrology in three catchments under contrasting land use in the Mau Forest Complex, Kenya's largest tropical montane forest. Annual suspended sediment yield was significantly higher in a smallholder agriculture-dominated catchment (131.5 ± 90.6 t km −2 yr −1) than in a tea-tree plantation catchment (42.0 ± 21.0 t km −2 yr −1) and a natural forest catchment (21.5 ± 11.1 t km −2 yr −1) (p < 0.05). Transfer function models showed that in the natural forest and the tea-tree plantations subsurface flow pathways delivered water to the stream, while in the smallholder agriculture shallow subsurface and surface runoff were dominant. There was a delayed sediment response to rainfall for the smallholder agriculture and the tea-tree plantations. A slow depletion in sediment supply suggests that the wider catchment area supplies sediment, especially in the catchment dominated by smallholder farming. In contrast, a fast sediment response and depletion in sediment supply in the natural forest suggests a dominance of temporarily stored and nearby sediment sources. This study shows that the vegetation cover of a forest ecosystem is very effective in conserving soil, whereas catchments with more bare soil and poor soil conservation practices generated six times more suspended sediment yield. Catchment connectivity through unpaved tracks is thought to be the main explanation for the difference in sediment yield.
... Governance, too, is also a key factor around these issues. The Lake Victoria Basin is one of the regions in East Africa with the highest population density [29], averaging approximately 500 persons per km 2 , and, in some parts of Kenya, densities of up to 1200 persons per km 2 have been reported [1]. The basin is home to over 30 million people [30] whose livelihoods depend mainly on agriculture and livestock production, beekeeping, mining, trade, and fishing [9]. ...
The Lake Victoria Basin (LVB) is a significant resource for five states within East Africa, which faces major land use land cover changes that threaten ecosystem integrity and ecosystem services derived from the basin's resources. To assess land use land cover changes between 1985 and 2014, and subsequently determine the trends and drivers of these changes, we used a series of Landsat images and field data obtained from the LVB. Landsat image pre-processing and band combinations were done in ENVI 5.1. A supervised classification was applied on 118 Landsat scenes using the maximum likelihood classifier in ENVI 5.1. The overall accuracy of classified images was computed for the 2014 images using 124 reference data points collected through stratified random sampling. Computations of area under various land cover classes were calculated between the 1985 and 2014 images. We also correlated the area from natural vegetation classes to farmlands and settlements (urban areas) to explore relationships between land use land cover conversions among these classes. Based on our land cover classifications, we obtained overall accuracy of 71% and a moderate Kappa statistic of 0.56. Our results indicate that the LVB has undergone drastic changes in land use land cover, mainly driven by human activities that led to the conversion of forests, woodlands, grasslands, and wetlands to either farmlands or settlements. We conclude that information from this work is useful not only for basin-scale assessments and monitoring of land cover changes but also for targeting, prioritizing, and monitoring of small scale, community led efforts to restore degraded and fragmented areas in the basin. Such efforts could mitigate the loss of ecosystem services previously derived from large contiguous land covers which are no longer tenable to restore. We recommend adoption of a basin scale, operational, Earth observation-based, land use change monitoring framework. Such a framework can facilitate rapid and frequent assessments of gains and losses in specific land cover classes and thus focus strategic interventions in areas experiencing major losses, through mitigation and compensatory approaches.
... Fisheries are a vital industry in the Lake Victoria Basin, being a major source of income for the population and a driver for many regional economies (Njiru et al. 2008). However, the lake is under severe pressure due to overfishing and pollution (Ntiba et al. 2008). Promoting a shift from wild catch fisheries to sustainable aquaculture is vital (Bostock et al. 2010) for safeguarding the lake ecosystem and the provision of a reliable protein supply for the region's ever-expanding population. ...
Lake Victoria, regionally important both as a food and income source, is under pressure due to overfishing and severe pollution. Currently, the vast majority of east African aquaculture is open pond based. The adoption of modern, sustainable, aquaculture technologies and practices – in this case study recirculating aquaculture systems (RAS) – will aid the region to increase food security and decrease the current reliance on imported fish and stressed wild stocks. To this end, VicInAqua, a project under the EU Horizon 2020 programme, has developed a pilot Nile Tilapia (Oreochromis niloticus) hatchery in Kisumu, Kenya using RAS adapted to local conditions. The hatchery is designed as a flexible, scalable and modular system. An online monitoring system enables the farmers to access farm data both from fish tanks and the supporting renewable energy systems allowing around the clock monitoring and control. The hatchery is linked to a 14.3 kWp Photovoltaic system including 30 kWh lithium‐battery storage to supply sustainable electricity. Treated by a membrane bioreactor (MBR), water for the RAS, certified for use in aquaculture and agriculture, comes chiefly from Kisumu's municipal sewage reducing the farms reliance on an expensive and occasionally intermittent potable water supply. The coupling of these technologies represents a first for the industry and offers a working example for larger scale future developments. The purpose of the project is to demonstrate the possible technologies and practices in situ as well as providing a template for future development and investment. The hatchery is used by the Department of Livestock, Agriculture and Fisheries, Kisumu County, Kenya, as a training and demonstration facility to promote the aquaculture sector and increase awareness, knowledge and skills for fish farmers as well as providing high quality fingerlings to cage farmers within the lake. This article is protected by copyright. All rights reserved.
... Eutrophication tends to affect shallow lake systems more than deeper tropical lakes (Kemka et al., 2006). Population growth, intensified agriculture (including the use of agrochemicals) and deforestation are the main drivers of nutrient-rich inflows into shallow tropical reservoirs (Ndebele-Murisa et al., 2010;Ntiba et al., 2001). ...
Man-made reservoirs are important inland ecosystems that provide food and livelihoods in many countries. Due to the dispersed nature of inland fisheries, most individual systems are rarely adequately assessed or monitored, therefore reliable data on the target stocks are largely unavailable to implement management strategies. This thesis focuses on Tono, Bontanga and Golinga reservoirs in northern Ghana which contribute significantly to food nutrition and community livelihoods. The thesis presents studies that demonstrate how differences in reservoir use patterns, reservoir morphometry and physicochemical characteristics influence ecosystem structures and fisheries resource productivity. The thesis includes (i) an assessment of empirical models for reservoir harvest estimations, (ii) a study relating morphometric characteristics of the reservoirs to fish production, (iii) assessments of the exploitation levels and stock status of the reservoirs’ target species and (iv) a holistic description of the reservoirs’ biological interactions through a food web modelling approach (Ecopath with Ecosim). To improve the estimation of current harvest potential of West African reservoirs, the relationship between total annual fish catch and reservoir surface area was modelled, which compared to a previous model, indicated that catches from reservoirs in the region have more than doubled over the last two decades. While the analysis indicated that fisheries productivity is inversely correlated with both mean depth and surface area, no significant correlation was found with reservoir age. The exploited resources in the small-scale fisheries of the Tono, Bontanga, and Golinga reservoirs were assessed based on length frequency samples. Growth, mortality, exploitation status, stock size, and relative yield per recruit reference points were determined using bootstrapping fish stock assessment (BFSA), a novel framework that allows for the estimation of uncertainties around the life-history parameters and reference levels (e.g., L∞, K, and F0.1). A complementary assessment approach based on length-based indicators was used to calculate the species’ spawning potential ratios under the current exploitation regime. Tono, Bontanga and Golinga reservoirs provide a total fish catch of 10.1, 15.5 and 17.1 t km−2 yr−1, respectively. The reservoir fisheries are dominated by two cichlid species (Sarotherodon galilaeus and Oreochromis niloticus). The cichlid species Oreochromis niloticus, Sarotherondon galilaeus, and Coptodon zillii were found to be heavily exploited in all three reservoirs. The giraffe catfish, Auchenoglanis occidentalis was found only in Tono and Bontanga reservoirs. In Bontanga, the catfish stock is fully exploited. While in Tono, the giraffe catfish is underexploited, the current fishing mortality could be doubled to increase yield. The length-based indicators suggested all the species at Bontanga and O. niloticus and S. galilaeus populations at Golinga have spawning stock biomasses below 40% of the unfished biomass. This points to a situation of a possible ongoing recruitment overfishing of those species in the two reservoirs and suggests that a further increase in fishing effort is not advisable. To support the construction of reservoirs’ food web models, a study was conducted on the feeding characteristics of the giraffe catfish with the expectation that the population in Reservoir Tono, which has an extensive macrophyte coverage, feeds more on plant material and associated insects than their counterparts in the Reservoir Bontanga. The study showed that fish food items did not differ significantly between the two reservoirs. Insect larvae and algae dominated the stomach contents. Comparative analysis of the reservoirs showed interesting differences: the mean trophic level of the catch was lowest in the largest and deepest reservoir (Tono), likely due to higher trophic level species occupying less accessible deep ‘refuge’ habitats. In the medium-sized (Bontanga) and small shallow (Golinga) reservoirs, in contrast, a larger catch portion resembles high trophic level species. Lake Bontanga differs from the other reservoirs by having a lower human population impact, a significantly lower Total Primary Production to Total Respiration ratio, a higher Total Biomass to Total System Throughput ratio, a higher Finn Cycling Index, a higher Detritivory to Herbivory ratio as well as the highest gross efficiency of the catch, all indicative for a more developed ecosystem. The smallest shallow (Golinga) reservoir is more impacted by anthropogenic activities than the other two reservoirs as indicated by the high levels of dissolved organic carbon, total dissolved nitrogen bonded, nitrite-nitrogen and turbidity in the reservoir. While the smallest lake had the highest fish production (per unit area) under optimal conditions of water supply, it is most vulnerable when used for both irrigated agriculture and fisheries production. The findings of this thesis suggest that the use of man-made lakes and respective catchment areas should be assessed and managed carefully to prevent the loss of nutrition and livelihoods contributions. Finally, this thesis serves as a broad template for the development of sustainable ecosystem-based management measures not only for the three studied ecosystems but for other reservoirs exposed to human activities around the world.
... Eutrophication tends to affect shallow lake systems more than deeper tropical lakes ( Kemka et al., 2006 ). Population growth, intensified agriculture (including the use of agrochemicals) and deforestation are the main drivers of nutrient-rich inflows into shallow tropical reservoirs ( Ndebele-Murisa et al., 2010 ;Ntiba et al., 2001 ). ...
A major constraint to science-based fish stock management in West Africa is the lack of reliable data on target stocks. This especially holds true for inland fisheries, such as those that operate in reservoirs. Due to the low availability of resources and population data, and the limited number of fisheries experts in the region, state institutions and investigators rely heavily on simple catch statistics and empirical models for their estimations of fish production and potential yields. This paper reviews data from the FAO, and published articles and reports on West African reservoirs, with special reference to their morphometric and environmental features in relation to fish catch. In addition, we analyse primary data on three focus reservoirs. First, to improve and update available models of potential harvests from reservoirs, we regress fish catch data against reservoir surface area data for 30 reservoirs in West Africa, yielding the following equation: Catch (tonnes/year) = 17.3 × Area (km2)0.8626. The equation accounts for 95.7% of the variation observed in the fish catches. Analysis of covariance of small (<2 km2) and large (>2 km2) reservoirs shows no significant difference (F = 0.5895, p = 0.45) in the slopes of the two groups. Second, we apply multiple regressions to a sub dataset of 15 reservoirs with surface area and mean depth as predictors; and we also explore reservoir age as a further variable. We find that fisheries productivity is inversely correlated with both mean depth (r = -0.49) and surface area (r = -0.32), but there is no significant correlation found with reservoir age (r = 0.03).
... Other threats to freshwater that are exacerbated by climate change include increased river siltation resulting from high soil erosion in the basin, recurrent destructive floods in the low-lying areas, riparian land encroachment, degradation of river banks, eutrophication, and proliferation of the invasive water hyacinth [23,24]. Increasing intensity and frequency of extreme climatic events pose additional threats to the future ecological and community well-being in the Lake Victoria Basin (LVB) [25]. ...
Rivers in the Lake Victoria Basin support a multitude of ecosystem services, and the economies of the riparian countries (Kenya, Tanzania, Uganda, Rwanda, and Burundi) rely on their discharge, but projections of their future discharges under various climate change scenarios are not available. Here, we apply Vector Autoregressive Moving Average models with eXogenous variables (VARMAX) statistical models to project hydrological discharge for 23 river catchments for the 2015–2100 period, under three representative concentration pathways (RCPs), namely RCPs 2.6, 4.5, and 8.5. We show an intensification of future annual rainfall by 25% in the eastern and 5–10% in the western part of the basin. At higher emission scenarios, the October to December season receives more rainfall than the March to May season. Temperature projections show a substantial increase in the mean annual minimum temperature by 1.3–4.5 °C and warming in the colder season (June to September) by 1.7–2.9 °C under RCP 4.5 and 4.9 °C under RCP 8.5 by 2085. Variability in future river discharge ranges from 5–267%, increases with emission intensity, and is the highest in rivers in the southern and south eastern parts of the basin. The flow trajectories reveal no systematic trends but suggest marked inter-annual variation, primarily in the timing and magnitude of discharge peaks and lows. The projections imply the need for coordinated transboundary river management in the future.
... Located on the banks of Lake Victoria in Kenya, Kisumu has encountered many food-system shifts, from the depletion of a key protein resource in the Lake, as a result of the introduction of the Nile Perch [49], to more recent ecological challenges driven by increased effluent and agricultural run-off into the lake and the increase in water hyacinth [50]. The land-based resource has also seen significant change where traditional and more localised crops have been replaced with cash crops such as sugar. ...
Global food insecurity levels remain stubbornly high. One of the surest ways to grasp the scale and consequence of global inequality is through a food systems lens. In a predominantly urban world, urban food systems present a useful lens to engage a wide variety of urban (and global) challenges—so called ‘wicked problems.’ This paper describes a collaborative research project between four urban food system research units, two European and two African. The project purpose was to seek out solutions to what lay between, across and within the different approaches applied in the understanding of each city’s food system challenges. Contextual differences and immediate (perceived) needs resulted in very different views on the nature of the challenge and the solutions required. Value positions of individuals and their disciplinary “enclaves” presented further boundaries. The paper argues that finding consensus provides false solutions. Rather the identification of novel approaches to such wicked problems is contingent of these differences being brought to the fore, being part of the conversation, as devices through which common positions can be discovered, where spaces are created for the realisation of new perspectives, but also, where difference is celebrated as opposed to censored.
... The water prevents the wood from cracking. Boats not-in-use are normally stationed ashore [6,12] during months when fishing is illegal [4,56,57], when fish catches are significantly low, when actors are off duty and during tumultuous party times when fishermen revel after receiving cash bonuses from their cooperative societies. That aside, it is unlikely that the larvae found in boats were introduced through the maintenance process. ...
Background
Everyday hundreds of people, mainly men, set out to take part in a vibrant artisanal capture fishing (ACF) industry on Lake Victoria. It is not known whether actions of artisanal fishers, in their unrelenting quest for existence, surpass ecosystems’ sustainability thresholds with potentially negative repercussions on human health with respect to malaria transmission potential. This article sought to fill this information gap.
Methods
This study used an ecosystem approach to find out how ACF processes facilitate the breeding of mosquitoes. The observational study adopted a cross-sectional design and was carried out on Mageta Island situated inside Lake Victoria in western Kenya.
Results
Of the 87 mosquito larval habitats identified 27 (31%) were created through ACF activities. The ACF-related habitats, hereafter collectively referred to as ‘fishing habitats’, included fishing boats (24), trenches (1) and fish bait mines (2). About half (48%) of Anopheles larvae were recovered from fishing habitats. The mean larval density in the fishing habitats (35.7 ± 1.15) was double that in non-fishing habitats (17.4 ± 0.539). Despite being the most common ‘non-fishing habitat’ type (N = 32), the mean number of Anopheles larvae present in rock pools (30.81 ± 10.54) was significantly less than those found inside fishing boats (N = 24; 40.08 ± 10.16). Overall, man-made habitats and those used to support livelihoods contained significantly more Anopheles larvae.
Conclusions
These data show that artisanal capture fishing is a key driver of malaria epidemiology on Mageta Island. This suggests that larval source management strategies in the global south should pay attention to the heterogeneity in Anopheles breeding habitats created through livelihood activities.
The entities responsible for the management of the endangered Gulf of Maine Distinct Population Segment of Atlantic salmon (Salmo salar) have partnered with a commercial aquaculture company to apply a novel conservation aquaculture program. This effort marks a major shift in management and has garnered mixed public reactions. Recent expansion of aquaculture in Maine has been a point of controversy as people and systems grapple with the social, environmental, and legal aspects of this burgeoning industry. Still, the use of aquaculture for conservation has shown some promise. In 2021, a questionnaire was administered to 850 households (response rate 27 %) in Maine via the Drop-off and Pick-up method. We examined differences and similarities in attitudes, beliefs, and knowledge about Atlantic salmon, hatcheries, and aquaculture between property owners in the town where the proposed net pens would be located (Cutler; n=73), and those in neighboring towns (n=152). The Potential for Conflict Index (PCI2) was used to examine differences between the groups. Both groups held similar positive attitudes toward Atlantic salmon, endangered species conservation, freshwater hatcheries, and both commercial and conservation aquaculture. Both groups believe that “Atlantic salmon should be protected,” and that freshwater hatcheries and marine conservation aquaculture “should be used for conservation.” However, Cutler residents had less consensus and supported the use of freshwater hatcheries and marine conservation aquaculture less than other respondents. Community concerns have stalled efforts to move the project forward. Our research indicates there are several social concepts which may help to explain localized opposition to the project.
chapter in report for UNDP
The presence of the non-native Nile perch (Lates niloticus) in Lake Victoria and the resulting ecological transformations have garnered significant attention from the scientific community. However, details regarding the timing, origin, and purpose of the fish introduction have remained elusive. This paper reviews fish fauna changes in Lake Victoria, investigates causes, and advocates for biodiversity conservation through diversity and sanctuary sites. It examines different historical periods to understand changes and guide effective conservation strategies. The introduction of Nile perch has led to a substantial decline and even extinction of many native fish species, particularly cichlids, resulting in ecological imbalances and economic challenges for local fishing communities. To address these pressing issues, ongoing conservation efforts are being implemented. These initiatives focus on promoting sustainable fishing practices, safeguarding critical habitats, and reintroducing native fish species. Furthermore, cage fish farming is being explored as a potential solution to alleviate pressure on wild populations, as suggested by various authors. Recommendations stemming from this study include conducting virtual population analysis for stock assessments of indigenous species, intensify conservation efforts, diversify fishing practices, expand cage fish farming, increase public awareness and education, and enhance policy and governance frameworks. By implementing these recommendations, there is optimism for the recovery and resilience of indigenous fish species in Lake Victoria, leading to the conservation of biodiversity and the promotion of sustainable livelihoods for local communities.
This datasheet on Lates niloticus covers Identity, Overview, Distribution, Dispersal, Diagnosis, Biology & Ecology, Environmental Requirements, Natural Enemies, Impacts, Uses, Further Information.
Understanding the factors that contribute to transboundary water conflict and cooperation is critical to improve governance and protect water resources. State interactions are shaped by multiple pressures and multi-scalar actors. This research assesses how local stakeholders influence the state through an analysis of power, water quality-related vulnerability and risk. Based on the findings, local stakeholders directly and indirectly support high-intensity cooperation over transboundary lakes and can foster low-intensity conflict to enable a greater representation of needs. Local actors also mutually influence state and international processes causing a multi-scalar impact and response to the states’ transboundary water quality interactions.
The ongoing global warming has caused unprecedented changes in the climate system, leading to an increase in the intensity and frequency of weather and climate extremes. This study uses the sixth phase of Coupled Model Intercomparison Project (CMIP6) data to investigate projected changes in drought events over East Africa (EA) under four Shared Socioeconomic Pathway (SSP) emission scenarios (SSP1-2.6, SSP2-4.5, SSP3-4.0, and SSP5-8.5). The CMIP6 data are bias-corrected using a quantile mapping method, with the Climatic Research Unit's precipitation dataset as reference. Drought is quantified using the standardized precipitation index and different measures of drought are estimated: drought duration, drought frequency, drought severity, and drought intensity. Evaluating the accuracy and reliability of historical data before and after bias correction demonstrates the importance of the approach. The overall distribution after bias correction depicts a close agreement with observation. Moreover, the multi-model ensemble mean demonstrate superiority over individual Global Circulation Models. Projected future changes show enhancement in precipitation over most parts of EA in the far future under different SSP scenarios. However, the arid and semi-arid regions are expected to receive less amount of precipitation, whereas the highlands and lake regions are expected to receive a larger amount of precipitation increase. Furthermore, the dry areas of EA are likely to experience more frequent drought events with longer duration, stronger intensity, and severity in the far future. Overall, this study identifies possible drought hotspots over EA, enabling early preparation for such events.
The changing climatic patterns and increasing human population within the Lake Victoria Basin (LVB), together with overexploitation of water for economic activities call for assessment of water management for the entire basin. Based on the work of [8], this chapter focuses on the analysis of a combination of available in-situ climate data, Gravity Recovery And Climate Experiment (GRACE), Tropical Rainfall Measuring Mission (TRMM) observations, and high resolution Regional Climate simulations during recent decade(s) to assess the water storage changes within LVB that may be linked to recent climatic variability/changes and anomalies.
Background and Objective: Human-induced physical and environmental barriers especially hydropower dams and dense anoxic
vegetation along riverine-lacustrine connectivity are known to isolate and fragment fish populations, leading to variation. This study
explored possible morphological variations among populations of Barbus altianalis from Uganda with the intent to provide a more costeffective and reliable platform for elucidating the stocks under combined environmental and anthropogenic influence as a tool for
improved fisheries management and conservation. Materials and Methods: Multivariate analysis of morphometric variables was
performed to determine the morphological variation and discreteness among three populations of B. altianalis (N = 251) from the
lacustrine (Lake Edward) and riverine (River Nile and Kazinga channel) systems in Uganda. Morphological variation was determined using
a multivariate analysis of advanced truss and non-truss network systems on all individuals collected from commercial catches.
Results: There was a significantly (p<0.001) higher level of heterogeneity among populations. Group means on the DFA1 showed that
River Nile (-0.89) separated furthest from Lake Edward (0.79) and the Kazinga channel (0.68). River Nile had the highest number (80.5%)
of individuals correctly classified while Lake Edward (67.2%) and Kazinga channel (60.5%) had more misclassifications between them, an
indication that they could be much harder to separate. Conclusion: The observed patterns of variation were consistent with the
geographical locations of the different water bodies, that the isolating mechanisms are subjecting the different populations to different
selection pressure hence different phenotypic responses by the populations.
Key words: Discriminant function analysis, Lake Victoria, Edward basins, phenotypic variation, stock identification
The present study demonstrates the declining state of the major commercial fisheries of Lake Victoria, Kenya, a situation threatening sustainability of the lake's fishery. Data in the present study were derived from resource monitoring programmes that included hydro‐acoustics (2009–2018), trawl net fishing (2011–2018), frame surveys (2000–2016) and catch assessment surveys (2000–2015). The activities provided information on fish stocks and supported advice for fisheries management. The average fish stock densities for Tanzania, Uganda and Kenya of 8.92, 8.25 and 8.19 t/km2, respectively, were relatively similar. Diplomatic and sustainable efforts for harmony in fish harvesting among the fishers of the riparian countries are encouraged given the interdependence of the lake. The Kenyan and River Kagera regions had a higher proportion (≈ 4% each) of big‐sized Nile perch (≥50 cm total length) in 2018, signifying the critical breeding areas for Nile perch. To sustain the fishery, there is need to enforce a 36%–44% effort reduction for all the major fisheries, and enforcement of gear limits to avoid harvesting of immature fish and destruction of the lake ecosystem.
The Lake Victoria fish fauna included an endemic cichlid flock of more than 300 species. To boost fisheries, Nile perch (Lates sp.) was introduced into the lake in the 1950s. In the early 1980s an explosive increase of this predator was observed. Simultaneously, catches of haplochromines decreased. This paper describes the species composition of haplochromines in a research area in the Mwanza Gulf of Lake Victoria prior to the Nile perch upsurge. The decline of the haplochromines as a group and the decline of the number of species in various habitats in the Mwanza Gulf was monitored between 1979 and 1990. Of the 123+ species originally caught at a series of sampling stations ca. 80 had disappeared from the catches after 1986. In deepwater regions and in sub-littoral regions haplochromine catches decreased to virtually zero after the Nile perch boom. Haplochromines were still caught in the littoral regions where Nile perch densities were lower. However, a considerable decrease of species occurred in these regions too. It is expected that a remnant of the original haplochromine fauna will survive in the littoral region of the lake. Extrapolation of the data of the Mwanza Gulf to the entire lake would imply that approximately 200 of the 300+ endemic haplochromine species have already disappeared, or are threatened with extinction. Although fishing had an impact on the haplochromine stocks, the main cause of their decline was predation by Nile perch. The speed of decline differed between species and appeared to depend on their abundance and size, and on the degree of habitat overlap with Nile perch. Since the Nile perch upsurge, the food web of Lake Victoria has changed considerably and the total yield of the fishery has increased three to four times. Dramatic declines of native species have also been observed in other lakes as a result of the introduction of alien predators. However, such data concern less speciose communities and, in most cases, the actual process of extinction has not been monitored.
The equatorial Lake Victoria is unique in its loss of an estimated two-thirds of its more than 300 endemic cichlid species within the last two or three decades. Great international and local concern has spawned a bibliography of over 2000 references. Based on studies in which PH. Greenwood and the author participated, this contribution selects the key events affecting changes to the fish communities and limnological conditions in the lake since the establishment of the East African Fisheries Research Organization in 1947.
After the disappearance of the haplochromine species in the Nyanza Gulf of Lake Victoria as a result of predation by Lates niloticus, the latter has turned its attention to aquatic invertebrates and other fish. Changes in the diet of the Nile perch with increase in its size have been observed: young L. niloticus preyed mostly on invertebrates, including crustaceans and various small aquatic insects; large, immature L. niloticus supplemented the invertebrate diet with both young and small fish; adults above 80 cm total length were mainly piscivorous. L. niloticus feeds on fish prey of about one third its own length.
The tendency of L. niloticus to switch from one prey item to another, depending on availability, is reported; e.g., in the Nyanza Gulf, the prey diet has shifted from the haplochromine to Caridina nilotica and L. niloticus juveniles.
The haplochromine cichlids in Lake Victoria: An assessment of biological and fisheries interests
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