Chrisphine Nyamweya

Kenya Marine and Fisheries Research Institute (KMFRI) · Department of Fishery

The seven African Great Lakes are some of the most critical freshwater, large-lake systems in the world, providing essential services, food, drinking water, and other livelihood support to over 62 million people. Like most freshwater systems around the world, these lakes are strained by anthropogenic stressors, leading to degradation of these biolo...

There is a common agreement that establishment of co-management could be of benefit to fisher community and other stakeholders across the African Great Lakes. This could aid in promoting community livelihoods and sustainability of the fishery and lakes ecosystem. However, the effectiveness of established co-management regimes remains unknown. This...

Sport fishing for Nile Perch and Tilapia are key attractions to recreational anglers on Lake Victoria. Existing hospitality establishments promote sport fishing with angling as the main form of recreational fishing. Development of this industry is expected to generate accrued benefits of eco-tourism and community empowerment by providing alternativ...

The extent of flooding in vulnerable inland and lacustrine systems can demonstrate the coverage and the magnitude of such phenomenon for policy enhancement. This study examined the extent of flooding due to rising water levels in selected Afrotropical lakes to guide interventions that would sustain the livelihoods of communities affected. The years...

Restocking of fish in Small Water Bodies (SWBs) is one of the technologies that can be used to enhance fish-food production for post Covid recovery and growth in food security, and national development. The current study aimed at assessing the socioeconomic impact and stock performance of restocked Nile tilapia fingerlings in SWBs in 15 counties in...

HRBS-GLWNB 2020 presents the first open-source and high-resolution bathymetry, shoreline, and water level data for Lakes Victoria, Albert, Edward, and George in East Africa. For each Lake, these data have three primary products collected for this project. The bathymetric datasets were created from approximately 18 million acoustic soundings. Over 8...

Sport fishing for Nile Perch and Tilapia are key attractions to recreational anglers on Lake Victoria. Existing hospitality establishments promote sport fishing with angling as the main form of recreational fishing. Development of this industry is expected to generate accrued benefits of eco-tourism and community empowerment by providing alternativ...

There is a common agreement that establishment of co-management could be of benefit to fisher community and other stakeholders across the African Great Lakes. This could aid in promoting community livelihoods and sustainability of the fishery and lakes ecosystem. However, the effectiveness of established co-management regimes remains unknown. This...

People residing in Lake Victoria’s basin and riparian countries benefit from ecosystem services provided by the lake. However, the lake’s resources, particularly fish, are under threat from pressures caused by humans such as overfishing, alien species invasion, rising eutrophication, and climate change. In this assessment, we look at how to maximiz...

Fisheries resources face a confluence of socio‐ecological challenges, the resolution of which requires interdisciplinary scientific information for sustainable utilization and management. The present study assessed gaps and challenges in Lake Victoria fisheries resources management for better research focus, policy formulation and improved governan...

Socio‐ecological characteristics of small water bodies (SWBs) are useful in determining the required level of rehabilitation and rebranding for possible blue economic investments. The current study assessed the socio‐ecological aspects of 74 SWBs in central and western counties in Kenya to determine their contamination status. The SWBs were selecte...

Kenya's inland and marine waters harbor exceptional high biodiversity and provide critical ecosystem goods and services to the riparian communities, ranging from drinking water, flood protection, water filtration, carbon storage, food supplies, tourism, and healthy well-being. However, these vital ecosystems and livelihood support systems are threa...

Assessing fisheries resource composition and exploitation trends is vital for the sustainable management of fish stocks. Accordingly, the present study analysed datasets of fish catches and market values from 1991 to 2019, and from 2004 to 2019, respectively, to determine shifts and trends in fish species composition, fishing effort, fish yield and...

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 o...

Understanding the potential of small water bodies (SWBs) will open greater opportunities in investment towards increased food and energy production. This study established the carrying capacity for fisheries development in SWBs in eight counties in Central and seven counties in Western Kenya. The carrying capacity of SWBs was calculated using socio...

We present the Multi-metric Index of Biotic Integrity methodological approach that allows for the ranking of major river catchments based on pollution status in the Kenyan portion of Lake Victoria, Africa. The study has a broader applicability to all of Lake Victoria, other African Great Lakes, and all lakes that have riverine discharge. The method...

We present a GIS‐based approach to the delineation of areas that have different levels of suitability for use as tilapia cage culture sites the Kenyan part of Lake Victoria, Africa. The study area was 4,100 km2. The method uses high‐resolution bathymetric data, newly collected water quality data from all major fishing grounds and cage culture sites...

We present the Multi-metric Index of Biotic Integrity methodological approach that allows for the ranking of major river catchments based on pollution status in the Kenyan portion of Lake Victoria, Africa. The study has a broader applicability to all of Lake Victoria, other African Great Lakes, and all lakes that have riverine discharge. The method...

Over-exploitation of tropical lakes and reservoirs ('lakes') causes water quality problems that occur as a result of competing socioeconomic demands and the presence of feedback loops within the system that exacerbate the situation. We review well documented case studies from Brazil, India, Indonesia, Kenya, Malaysia and Mexico to examine the effec...

Lake Baringo is a Ramsar‐designated water body facing a myriad of environmental challenges attributable to anthropogenic activities. At the same time, however, it is an important aquatic resource not only to the local community but also to the international arena because of its rich biodiversity. It supports an artisanal fishery with four major fis...

Lake Victoria biophysical and geochemical status has changed dramatically within an unprecedentedly short time scale driven by human actions. These actions can be broadly classified as escalated fisheries exploitation, biomanipulation (characterized by species introduction) and catchment processes. A chronology of these activities since 1901 to pre...

During the period February to June 2020, heavy rainfall caused increases in levels and flooding in many lakes in East Africa. This coincided with the COVID-19 pandemic. These calamities affected ecosystems and livelihoods, especially of fishers who depend on fisheries as their only source of livelihood. This study examined the effects of COVID-19 a...

Most small scale inland fisheries worldwide are open access, and fishing provides the only source of employment and livelihood for the riparian communities. Management of these fisheries requires information on trade-offs between fish production, profits from fishing, employment, and conservation objectives. We use the non-linear optimization proce...

The Lake Victoria Basin (LVB) is a global hotspot of aquatic biodiversity, but aquatic ecosystems are under threat from multiple stressors. Most studies on fish have focused on Lake Victoria, while patterns of fish diversity, distribution, and assemblage structure in influent rivers remain poorly understood. To assess threats and conservation statu...

Biomass of the schooling fish Rastrineobola argentea (dagaa) is presently estimated in Lake Victoria by acoustic survey following the simple “rule” that dagaa is the source of most echo energy returned from the top third of the water column. Dagaa have, however, been caught in the bottom two-thirds, and other species occur towards the surface: a mo...

Biomass of the schooling fish Rastrineobola argentea (dagaa) is presently estimated in Lake Victoria by acoustic survey following the simple “rule” that dagaa is the source of most echo energy returned from the top third of the water column. Dagaa have, however, been caught in the bottom two-thirds, and other species occur towards the surface: a mo...

Long-term time series data are not available for many of the African Great Lakes. This precludes fitting ecosystem model parameters to time series data, and we do not know how reliable non-fitted models are compared to fitted ones in terms of predicting consequences of alternative management strategies. To investigate this, we generate a historical...

The present study demonstrates the application of a multi‐metric Phytoplankton Index of Biotic Integrity (PIBI) approach for ranking of major river catchments in the Kenyan part of Lake Victoria on the basis of their pollution status. The index utilizes water quality and zooplankton data, phytoplankton diversity, abundance and attributes, as well a...

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...

Lake Victoria just like many other lakes is affected by water hyacinth which resides in several bays for the better part of the year. This weed affects several economic activities of the locals and denies the government revenue every year from blue economic activities related to the lake. This paper explores the interaction of water hyacinth with b...

Global fish oil production is between 1 to 1.25 million tones and primarily exploiting fatty fish such as menhaden, herring, pilchards, anchovy, and sardine among others. The main producing countries include Japan, USA, Chile and Peru. Yet, fish oil from developing countries end up as bio waste since only the flesh is utilized. This paper discusses...

Global fish oil production is between 1 to 1.25 million tonnes and primarily exploiting fatty fish such as menhaden, herring, pilchards, anchovy, and sardine among others. The main producing countries include Japan, USA, Chile and Peru. Yet, fish oil from developing countries end up as bio waste since only the flesh is utilized. This paper discusse...

Ecosystem simulation models are valuable quantitative decision tools for supporting ecosystem-based fisheries management. However, the application of ecosystem models in fisheries management is still undermined by the lack of simple procedures to test the effect of model uncertainty on policy outcomes. The use of multiple ecosystem models is viewed...

Lake Victoria, the largest lake in the tropics, has a storied history that includes major shifts in ecology in recent years due to a variety of point and non-point source anthropogenic impacts. Among the expanding industries contributing to environmental impacts if not properly managed, is the recent and rapid expansion of cage aquaculture of Nile...

Small-scale fisheries in Kenya contribute about 4.7% of the Gross Domestic Product (GDP) in spite of high post-harvest losses. Post-harvest interventions in fisheries enable fishers and fish processors to reduce waste, maintain nutritional aspects and meet stringent demands in food quality and safety. This review highlights the benefits and pitfall...

Fisheries management uses important fish market information and information from Communication Technology (ICT) to improve fish trade by identifying inefficiencies, inequity and post‐harvest losses. The current study reports fisheries output using ICT at major landing sites and markets in Kenya and Uganda from the Kenya Marine and Fisheries Researc...

Ecosystem simulation models are valuable tools for strengthening and promoting ecosystem-based fisheries management (EBFM). However, utility of these models in practical fisheries management is often undermined by lack of simple means to test the effect of uncertainty on model outputs. Recently, the use of multiple ecosystem models has been recomme...

Invasive aquatic macrophytes in Lake Victoria including water hyacinth (Eichhornia crassipes) exhibit periodic cyclical patterns of decline and proliferation with attendant ecological and economic impacts. This study aimed to monitor the extent of macrophytes and other invasive weeds on Lake Victoria to establish their impact on fisheries. The stud...

Lake Turkana is the largest lake in Kenya and it can greatly contribute to economic development of the arid region and the country in general. There is need for urgent measures to develop, improve and transfer innovative technologies to reduce fish post-harvest losses which will greatly contribute to ensuring food security as envisaged in the Big 4...

The small pelagic cyprinid, Rastrineobola argentea (Pellegrin), commonly known as dagaa, accounted for 60% of the total fish biomass and 40% of the commercial catches in Lake Victoria in 2015. However, some aspects of the biology of species (from which management interventions are based) have changed since 1970s; and yet harvest regulations have re...

The past subsistence of the Lake Victoria fishery was dominated by rich, diverse haplochromine cichlids. This multispecies fishery has undergone a decline over the past four decades, evolving into a commercial fishery consisting mainly of Nile perch (Lates niloticus), Nile tilapia (Oreochromis niloticus) and cyprinid (Rastrineobola argentea species...

To fully appreciate the ecological, social and economic benefits of wetland ecosystems, actions are needed to advocate for sustainable use. A study of Lake Kanyaboli, located the Yala swamp and are of great ecological significance to conservation and biodiversity. The challenges facing the wetland includes; pollution, water diversion, wetland encro...

Nile perch were secretly introduced into Lake Victoria in the 1950s, and officially in the 1960s, amid unresolved controversy. Proponents were of the view that the introduction would improve fisheries production and sport fishing. Although the former objective was achieved, the side effects were dire, including extinction of many native species, es...

Fisheries management of Lake Victoria has evolved from traditional belief systems of local fishing communities to one with formal national and regional institutions. The impact of management interventions utilized so far is difficult to assess. With the advent of whole ecosystem models, management strategy evaluation has taken root elsewhere. The f...

This study investigated sunflower seed meal (SSM) as dietary protein replacement of fish meal (FM) for Nile tilapia (Oreochromis niloticus) juveniles (initial mean weight of 19.8 ± 6.3 g) reared in earthen ponds for 210 days. SSM replaced 25%, 50%, 75%, and 100% (i.e., D25, D50, D75, and D100, respectively) of FM in an isonitrogenous and isocaloric...

Lake Victoria has experienced human induced pressures such as overfishing, introduction of alien species, increased eutrophication and climate change impacts. However, there is limited understanding of the system dynamics, major processes, drivers and responses to the changes. To address this challenge, we developed the first end-to-end whole ecosy...

Aquaculture in Kenya provides important livelihood opportunities for the rural poor by improving the local economy as well as supplementing protein sources. Despite being one of the areas with highest aquaculture potential in the country, Western Kenya records some of the highest rates of poverty and malnutrition. This study undertook an assessment...

Lake Victoria provides important ecosystem services including transport, water for domestic and industrial uses and fisheries to about 33 million inhabitants in three East African countries. The lake plays an important role in modulating regional climate. Its thermodynamics and hydrodynamics are also influenced by prevailing climatic and weather co...

Shape files for a map of Lake Victoria in East Africa, its major rivers and bathymetry. (ZIP)

Water samples for physico-chemical analysis for this study were collected monthly for five years between April 2008 and March 2013. Conductivity, temperature, dissolved oxygen and pH was measured in situ using a Surveyor II model hydrolab. Chlorophyll-a concentration was determined using a Genesys 10S Vis spectrophotomer. Nutrients were determined...

Lake Victoria, East Africa, supports a fishery that yields about one million tonnes per annum consisting predominantly of three species, Nile Perch (Lates niloticus), Nile Tilapia (Oreochromis niloticus) and a native sardine-like cyprinid called Dagaa (Rastrineobola argentea). The non-native Nile Perch is the most valuable of these species and supp...

The Lake Victoria ecosystem once hosted a diverse fish community dominated by a large species flock of haplochromine cichlids. Today this fish assemblage is highly altered by anthropogenic activities, with at least half of the indigenous species either extinct or very rare. The fishery has been reduced to three fishes of economic importance: introd...

The distribution and densities of three pelagic fish taxa (Nile Perch, Lates niloticus, Rastrineobola argentea [Dagaa], and the haplochromine cichlids) in Lake Victoria were estimated through 17 lake-wide acoustic surveys conducted in two series (August 1999–August 2002 and August 2005–September 2011). Nile Perch densities were estimated through ec...

A survey on Lake Naivasha identified and delineated critical breeding and nursery areas for fish which were to be protected in order to assist in the recovery of its fish stocks. Crescent Island, Oserian Bay, the river Malewa mouth and Kamere and its wetlands were identified as critical areas. A questionnaire revealed that most fishermen come from...

Aspects of the biology of Labeo cylindricus from Lake Baringo were investigated, based on experimental beach seining and gillnetting between August and October 2007. The length–weight relationship indicated the species exhibited positive allometric growth (b = 3.7083), with a condition factor (K) of 0.84 ± 0.0298 S.D. Males dominated fish catches,...

Abstract The African catfish (Clarias gariepinus) is widely distributed in Africa, where it is a major food fish. The species comprises a significant component of commercial fishery landings in Kenya, and elsewhere in Africa. Nevertheless, little information or data exist on its age and growth characteristics, which is necessary for its sustainable...

Otolith microstructure analysis was used to validate microincrement deposition rate and to determine daily growth rates of young-of-the-year (YOY) Baringo tilapia, Oreochromis niloticus baringoensis. Micro-increment formation was validated as daily by correlating the number of circuli on otoliths with the known age of cultured fish. For wild young-...

Otolith microstructure analysis was used to validate microincrement deposition rate and to determine daily growth rates of young-of-the-year (YOY) Baringo tilapia, Oreochromis niloticus baringoensis. Microincrement formation was validated as daily by correlating the number of circuli on otoliths with the known age of cultured fish. For wild young-o...