Aquaculture

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Anthropogenic Nutrients and Phytoplankton Diversity in Kenya's Coastal Waters: An ecological Quality Assessment of Sea Turtle Foraging sites
(Marine polluition Bulletin, 2017) Oduor N. A; Munga C.M; Imbayi L.K; Botwe P.K; Nyanjong E.O; Muthama C.M; Mise N.A; Moosdorf Nils
Abstract We assessed ecological quality status (EQS) of coastal waters following claims of increasing sea turtle fibro-papillomatosis (FP) infections in Kenya, a disease hypothesized to be associated with ‘poor’ ecological health. We established widespread phosphate (P) and silicate (Si) limitation, dissolved ammonium contamination and an increase in potential harmful algal blooming species. Variations in the EQS was established in the sites depending on the indicators used and seasons. Generally, more sites located near hotels, tidal creeks, and estuarine areas showed ‘poor’, and ‘bad’ EQS during rainy period compared to dry season. Additionally, 90.1 % of the sites in ‘poor’ and ‘bad’ EQS based on dissolved inorganic nitrogen. Low dissolved oxygen, elevated temperature, salinity and ammonium, ‘poor’ EQS based on DIN, and potential bio-toxin-producing phytoplankton species characterized the FP prevalent areas, specifically during the dry season suggesting environmental stress pointing to the hypothesized connection between ecological and sea turtle health.
Application of the DPSIR Framework to Coastal and Marine Fisheries Management in Kenya
(Ocean Science Journal, 2020-06-09) Dzoga, Mumini; Simatele, Danny Mulala; Munga, Cosmas; Yonge, Shadrack
Natural resource management frameworks are important in generating information that promotes the development of appropriate policies and regulation for effective management and utilization of different aspects of ecosystems. The Drivers-Pressure-State-Impact and Response (DPSIR) framework is one of such frameworks which has been widely applied globally in assessing, addressing and communicating with regard to environmental problems. This framework provides a nexus between the causes of environmental problems and the resultant pressures, associated impacts and responses needed to resolve and manage specific environmental issues and challenges. Based on improved management evidence for natural resources enabled by the application of the DPSIR framework globally, this paper is a review of the application of the framework in the management of coastal and marine fisheries resources in Kenya. Findings indicate that there exists a limited number of studies which have adopted the DPSIR framework approach in Kenya, and these are mainly focused on terrestrial ecosystems. However, coastal and marine resources have been well studied in Kenya using different methodological approaches that have given insights into the conditions of resources. This review, therefore, analyzed these studies to understand drivers, pressures, states, impacts and responses in relation to coastal and marine fisheries resources in Kenya. The main drivers observed were a high population growth rate of 3.7% as well as a high dependency rate on natural resources of 74% and 58% in Ngomeni and Kipini fishing areas of north coast Kenya, respectively. There is also a lack of understanding regarding the potential of the DPSIR framework to effectively manage coastal and marine fisheries resources, particularly in the context of sub-Saharan Africa, taking Kenya as a case study. This may result in the development of fisheries regulations that are not holistic in their approach, and therefore, ineffective from a management perspective. Within this context, this paper provides a discourse on how the DPSIR framework may enhance coastal and marine fisheries resources management in Kenya.
Comparison of Water Use Savings and Crop Yields for Clay Pot and Furrow Irrigation Methods in Lake Bogoria, Kenya
(The International Institute for Science, Technology and Education (IISTE), 2013-07) Kefa C. C.; Kipkorir E. C.; Kwonyike J.; Kubowon P. C.; Ndambiri H. K.
As population grows mainly in developing countries resulting in an increase in water scarcity particularly in arid areas, irrigated agriculture is required to produce more food while using less water, and to do so without degrading the environment. The extent of improvement of water management in arid lands involves very high costs and irrigation methods that can help meet this challenge by giving growers greater control over the application of water is desirable. Clay pot is an efficient and cheap irrigation method that does not require water of high quality. Despite the significant efforts at Kapkuikui informal irrigation scheme to increase food production using furrow irrigation method, production has been declining over time due to water scarcity and fields abandoned as a result of salinity raising the need for improvement of the water productivity using an environmentally sound irrigation method. The objective of the present study was to evaluate water use savings under clay pot compared to furrow irrigation methods using field trials of maize and tomato crops and also soil water balance techniques. In addition, analysis of the salinity of irrigation water and soil at the scheme was done. Results indicate that the irrigation water sourced from springs at the scheme is saline with a salinity of 0.85g/l. The clay pot system was found to be more efficient than the furrow irrigation method by saving 97.1% of applied water for the maize crop and 97.8% for the tomato crop respectively. In terms of yield increases, the clay system was more productive per unit of water than the furrow irrigation method. The maize grain yields was 32.2% higher than that under the furrow, while fresh fruit tomato yields was 43.7% higher in the clay pot system than the furrow.
Diversity of Mangrove Fungal Endophytes from Selected Mangrove Species of Coastal Kenya. Published in Western Indian Ocean Journal of Marine Science
(Western Indian Ocean Marine Science Association (WIOMSA), 2021-01) David K. Bett; Mwakio Tole; Chrisestom M. Mlewa
Abstract Ring nets are modified purse seines used for pelagic fishing along the Kenya coast. This method is however associated with potential negative environmental implications in inshore and shallow fishing grounds. Biological impacts on selected pelagic species caught in the marine waters of Kilifi were investigated during the Southeast Monsoon season (SEM) in April, May and September 2014, and the Northeast Monsoon season (NEM) in October and November 2014, and March 2015. Amblygaster sirm, Rastrelliger brachysoma, Sardinella gibbosa, Rastrelliger kanagurta, Hemiramphus far and Sphyraena obtusata were the most abundant species caught by the ring nets and comprised 68.9 % of fish catch composition. Analysis of ring net impacts on the fish sizes and maturity status were conducted for the NEM and SEM seasons. The catch composition for A. sirm in October comprised of 53.3 % juveniles and 53.4 % juveniles for S. obtusata in November. High percentages of H. far (78.3%) and S. obtusata (58.9 %) were captured in September. Incidences of undersize fish for A. sirm, S. gibbosa, R. kanagurta and R. brachysoma were observed across the seasons. Sex ratios for A. sirm, R. brachysoma, R. kanagurta and S. obtusata in the NEM season deviated from a normal ratio of 1:1 with more males observed. Females were dominant in the catch for H. far (1: 1.28) but the ratio was not different for S. gibbosa (χ² = 5.564, df = 1, p = 0.21). Males were dominant for A. sirm (1: 0.8) and S. gibbosa (1: 0.7) in the SEM season but the ratios were not different for H. far, S. obtusata, R. brachysoma and R. kanagurta. Differences in sex ratios were attributed to fish migrations and reproductive processes. Ring nets fished relatively offshore during the NEM season and targeted mainly spawning aggregations in stage IV. Immature fish in stage I and II which comprised of juveniles were harvested within sheltered inshore waters in the SEM season. Use of ring nets to target juveniles and spawning aggregations may disrupt recruitment processes. To enhance sustainable management of the ring net fishery, there is a need to develop harvesting strategies based on the information on stock status of the target fish. Keywords: ring nets, reproductive biology, impacts, Kilifi
Estuarize-WIO: A socio-ecological assessment of small-scale fisheries in estuaries of the Western Indian Ocean
(Western Indian Ocean Journal of Marine Science, 2021-12-23) Groeneveld, Johan C.; Hoguane, Antonio M.; Kuguru, Baraka; Mackay, Fiona; Munga, Cosmas; Santos, Jorge
Estuaries provide unique ecosystem goods and services and have been focal points for human settlement and resource use throughout recorded history. In the Western Indian Ocean (WIO) region, the effects of human population growth, rapid economic development and climate change on estuaries threaten their ecological functioning and the sustainability of estuary-dependent livelihoods. Governance systems are ill-equipped to deal with the mounting challenges. Longterm datasets that describe estuary-scale trends are scarce, and socio-ecological interactions that support sustainable use of resources are incompletely understood. To address these gaps, the Estuarize-WIO project (2016-2019) compiled datasets on biophysical, ecological, socioeconomic and fisheries aspects of selected estuaries in Mozambique (Bons Sinais), Tanzania (Ruvu) and Kenya (Tana), analysed trends per estuary, and used a socio-ecological systems (SES) framework to integrate information from multiple sources at local and regional levels. The introductory paper of this Special Issue of the Western Indian Ocean Journal of Marine Science provides regional context and reviews the relevant literature available for WIO estuaries. In succeeding papers, estuarine circulation is inferred from hydrological measurements, seasonal and decadal trends in land cover and land use are investigated using remote sensing images, household surveys are used to investigate socio-economic circumstances and resource use, and long-term catch survey data and field samples are used to describe small-scale fisheries. In the synthesis paper, a SES framework is constructed to investigate linkages and feedback loops in individual estuaries. A regionally comparative analysis accross the WIO region was conducted, and recommendations were made for future research and governance. The methodological approach developed for Estuarize-WIO is well-suited to research of data poor systems with limited accessibility and research infrastructure.
Food and Feeding Habits of Three Main Fish Species in Lake Baringo, Kenya
(Journal of Environmental Microbiology, 2013-08-17) Omondi, R.,; Yasindi A.W.; Magana A. M
The diets of three fish species of commercial importance in Lake Baringo, Protopterus aethiopicus, Clarias gariepinus and Oreochromis niloticus, were determined using frequency of occurrence and volumetric methods between April 2008 and March 2010. Seine and gill nets were used to catch a total of 430 fish specimens. The diet of P. aethiopicus was 94.3% molluscs with a frequency of occurrence of 98.6% of stomachs with food. Adult C. gariepinus fed mainly on fish with 75% of the stomachs with food containing fish remains and mean of 49.2% contribution by volume. C. gariepinus also fed on zooplankton, especially the cladoceran Daphnia barbata. The food items in the stomachs of O. niloticus consisted mainly of algae, detritus and zooplankton. Algae was consumed by O. niloticus of all length classes in proportions ranging from 26.5 to 88.1%. The importance of zooplankton as food for O. niloticus decreased with size of fish. The study reveals the importance of zooplankton as food for O. niloticus and C. gariepinus in Lake Baringo. There is need to rehabilitate the catchment of Lake Baringo so as to improve the water quality thus improve productivity
Genetic diversity and population structure of the African catfish, Clarias gariepinus (Burchell, 1822) in Kenya: implication for conservation and aquaculture
(Belgian Journal of Zoology, 2017-10) Barasa, James E.; Mdyogolo, Sinebongo; Abila, Romulus; Grobler, Johannes Paul; Skilton, Robert A.; Bindeman, Hesmari; Njahira, Moses Ndotono; Chemoiwa, Emily J.; Dangasuk, Otto G.; Kaunda-Arara, Boaz; Verheyen, Erik
African catfish, Clarias gariepinus, is an important species in aquaculture and fisheries in Kenya. Mitochondrial D-loop control region was used to determine genetic variation and population structure in samples of C. gariepinus from 10 sites including five natural populations (Lakes Victoria (LVG), Kanyaboli (LKG), Turkana (LTA), Baringo (LBA) and Jipe (LJP), and five farms (Sangoro Aquaculture Center (SAN), Sagana Aquaculture Centre (SAG), University of Eldoret Fish Farm (UoE), Kibos Fish Farm (KIB), and Wakhungu Fish Farm (WKU)) in Kenya. Similarly, samples from eight localities (four natural populations: LVG/LKG, LTA, LBA, and four farmed: SAN, SAG, KIB, UoE) were genotyped using six microsatellite DNA loci. For the D-loop control region, samples from natural sites exhibited higher numbers of haplotypes and haplotype diversities compared to farmed samples, and 88.2% of haplotypes were private. All except LJP and LTA shared haplotypes, and the highest number of shared haplotypes (8) was detected in KIB. The 68 haplotypes we found in 268 individuals grouped into five phylogenetic clades: LVG/LKG, LTA, LBA, LJP and SAG. Haplotypes of farmed C. gariepinus mostly have haplotypes typical of LVG/LKG, and some shared haplotypes of the LBA population. Microsatellite analysis showed farmed samples have higher numbers of alleles than natural samples, but higher observed and expected heterozygosity levels were found in samples of natural Belg. J. Zool. 147 (2): 105–127 (2017) 106 populations. Fifteen pair-wise comparisons had significantly different FST values. All samples were in Hardy-Weinberg equilibrium. Samples from the eight localities grouped into four genetic clusters (LVG/ LKG, LTA, LBA and SAG), indicating genetically distinct populations, which should be considered for aquaculture and conservation
Illegal Unregulated and Unreported Fishing: Methods and Increasing Trends in Lake Naivasha, Kenya
(WILEY ONLINE LIBRARY, 2021) Morara George N.; Njiru M. James; Getabu M. Albert; Omondi Reuben; Lewo Ruth; Obegi Beatrice; Mwangata Raymond
Illegal, unregulated and unreported (IUU) fishing is a negative social vice that adversely affects global capture fishery production. The inadequate disclosure of IUU methods and trends in fishery waters hampers management actions to curb illegal fishing activities. Seldom have empirical studies been conducted on IUU methods and their trends in Lake Naivasha. Therefore, this study analysed data on the fisheries monitoring, control and surveillance (MCS) during 2012 to 2018 to test for the significance of trends, and compare the enforcement plans to seizures of illegal fishing gear in the lake. The IUU fishing methods included both the types of equipment and the means used to perpetrate illicit capture or acquisition of fish from the lake. The results indicate a 37% reduction of MCS enforcement patrols during 2018 compared to 2012, and a 16% to 100% upsurge in the quantity of seized IUU fishing items. Illegal fishing boats potentially threaten the fishery of Lake Naivasha with an additional fishing effort of 22% above the 176 licensed boats. An average of 10,700 fishing nets seized per year has the potential fishing intensity of 74 gillnets/km2 against an ideal intensity of 12 gillnets/km2. The frequencies of MCS patrols in Lake Naivasha exhibit no particular trends and likely ineffective in deterring the upsurge of IUU activities, or the evolution of new illegal fishing methods. An increased seizure of illegal fishing boats, outboard engines and gillnets could imply their rampant use in IUU fishing activities. These findings merit a multi-stakeholder participatory approach to identifying the MCS weaknesses and opportunities for sharing resources to strengthen the fishery management efforts in Lake Naivasha.
Natural Resource-use in the Lower Tana River Delta Based on Household Surveys and Remote Sensing of Land Cover and Land Use Patterns
(Western Indian Ocean Marine Science Association (WIOMSA), 2021) Hamadi M. Mwamlavya; Cosmas N. Munga; Bernerd M. Fulanda; Johnstone O. Omukoto; , Pascal Z. Thoya; Fiona MacKay; Fatma H. Manyenze; Johan C. Groeneveld
Abstract Household survey data and spatially explicit Sentinel-2 satellite images of land cover and land use during the dry and wet seasons were used to investigate livelihood strategies in the Lower Tana River Delta in Kenya, where food security and economic activity rely almost exclusively on ecosystem goods and services. Land cover classification of satellite imagery successfully showed seasonal changes to estuary-related vegetation and habitats from which land use cycles could be inferred. Flood-recession agriculture and part-time fishing were the most common activities at Ozi village, some 10 km upstream from the estuary mouth, whereas full-time fishing dominated activities at Kipini town, where the Tana Estuary discharges into Ungwana Bay. Seasonality of fishing at Kipini depended on favourable sea conditions, arrival of migrant fishers and peaks in shrimp abundance. Seasonality of agriculture at Ozi depended on the freshwater flooding regime, visible in satellite images as an inverse relationship of areas covered by wetlands and cultivated lands. The predominance of fishing assets at Kipini indicated specialization, which underlies a socio-economic network of fish processing, marketing, distribution and logistical support services. In contrast, mixed farming assets and traditional fishing gear at Ozi reflected more diversified farmer-fisher livelihoods, as a risk avoidance strategy. Key outcomes of this study were that land cover and land use were strongly seasonal, that coastal and upstream communities in the Tana Estuary relied on different combinations of ecosystem goods and services, and that livelihood strategies at the two locations differed fundamentally. Combining social, spatial and ecological data to describe socio-ecological systems typical of the Tana Estuary provided a broad platform for shared resource management strategies.
Reprint of : Fishers who rely on mangroves: Modelling and mapping the global intensity of mangrove-associated fisheries
(Elsevier, 2021-01-05) zu Ermgassen, Philine S.E.; Mukherjee, Nibedita; Worthington, Thomas A.; Acosta, Alejandro; da Rocha Araujo, Ana Rosa; Beitl, Christine M.; Castellanos-Galindo, Gustavo A.; Cunha-Lignon, Marília; Dahdouh-Guebas, Farid; Diele, Karen; Parrett, Cara L.; Dwyer, Patrick G.; Gair,Jonathan R.; Johnson, Andrew Frederick; Kuguru, Baraka; Lobo, Aaron Savio; Loneragan, Neil R.; Longley-Wood, Kate; Mendonça, Jocemar Tomasino; Meynecke, Jan-Olaf; Mandal, Roland Nathan; Munga, Cosmas Nzaka; Reguero, Borja G.; Rönnbäck, Patrik; Thorley, Julia; Wolff, Matthias; Spalding, Mark
Mangroves are critical nursery habitats for fish and invertebrates, providing livelihoods for many coastal communities. Despite their importance, there is currently no estimate of the number of fishers engaged in mangrove associated fisheries, nor of the fishing intensity associated with mangroves at a global scale. We address these gaps by developing a global model of mangrove associated fisher numbers and mangrove fishing intensity. To develop the model, we undertook a three-round Delphi process with mangrove fisheries experts to identify the key drivers of mangrove fishing intensity. We then developed a conceptual model of intensity of mangrove fishing using those factors identified both as being important and for which appropriate global data could be found or developed. These factors were non-urban population, distance to market, distance to mangroves and other fishing grounds, and storm events. By projecting this conceptual model using geospatial datasets, we were able to estimate the number and distribution of mangrove associated fishers and the intensity of fishing in mangroves. We estimate there are 4.1 million mangrove associated fishers globally, with the highest number of mangrove fishers found in Indonesia, India, Bangladesh, Myanmar, and Brazil. Mangrove fishing intensity was greatest throughout Asia, and to a lesser extent West and Central Africa, and Central and South America.
Retained Fish Catches of Artisanal Fishers is dependent on Fishing area, Season and Fishing gear type: A case Study from the South Coast of Kenya. Published in Western Indian Ocean Journal of Marine Science
(WIO Journal of Marine Science, 2023-02-27) Athman Mwakaribu; Cosmas Munga; Mumini Dzoga; Paul Njihia; Danny Mulala
Abstract The artisanal fishery is one of the sources of livelihood along the Kenya coast. Catches of retained fish of artisanal fishers between two fishing areas on the south coast of Kenya were compared. Artisanal fishers usually retain a portion of their daily catch which is reserved for family consumption while the rest is traded for cash to meet other family needs. This study hypothesized that retained fish catches were influenced by fishing area, fishing gear type and season. Daily fish landings and retained fish catches among artisanal fishers were monitored between August 2020 to July 2021 covering the South East Monsoon (SEM) and North East Monsoon (NEM) in Msambweni and Vanga fishing areas. A total of 60 fishers (30 for each area) were randomly selected and their retained catch monitored on a daily basis. The overall total fish landings were 23.3 tons and 210 tons in Msambweni and Vanga, respectively. The mean catch rate at Msambweni was 3.3 ± 0.12 kg.fisher-1day-1 in the NEM season and 2.2 ± 0.09 kg.fisher-1day-1 in the SEM season. Fish catch rates in Vanga was 8.5 ± 0.28 kg.fisher-1day-1 in the NEM season and 7.9 ± 0.29 kg.fisher-1day-1 in the SEM season. A total of 0.98 tons (only 4.2 %) of fish was retained versus 22.32 tons (95.8 %) not retained by the artisanal fishers in Msambweni, while in Vanga a total of 1.64 tons (only 0.78 %) was retained versus 208.36 tons (99.22 %) not retained. Retained fish catch varied significantly with season and type of fishing gear used (p < 0.05). Among the retained species in Msambweni, Siganus sutor made the highest contribution (53 %), followed by Lethrinus mahsena, (5.08 %). The species Euthynnus affinis and Sphyraena obtusata were mostly retained in Vanga with a contribution of 10.4 % and 10.2 %, respectively. The same retained fish species represented the most abundant species in the overall fish landings, however sizes were significantly smaller than those not retained by fishers (p < 0.05). Results of non-Metric Multidimensional Scaling (nMDS) ordination showed differences in species composition between fishing areas, seasons and fishing gear types with implication on fishers’ retained catches.
Seasonal Changes of Length -Weight Relationship and Condition Factor of Five Fish Species in Lake Baringo, Kenya
(International Journal of Sciences: Basic and Applied Research (IJSBAR), 2014) Elijah Migiro Kembenya; Erick Ochieng Ogello; Cecilia Muthoni Githukia; Callen Nyaboke Aera; Reuben Omondi; Jonathan Mbonge Munguti
This study describes the length-weight relationships (LWR) and relative condition factor (K) of five fish species in Lake Baringo, Kenya. A total of 483 fishes consisting of Barbus intermedius, Clarias gariepinus, Labeo cylindricus, Oreochromis niloticus baringoensis and Protopterus aethiopicus were collected on monthly basis from Lake Baringo between September 2012 and August 2013. There was a significant difference (P < 0.05) in the weight at unit length (b) of the length weight relationship between the wet and dry season in all the fish species. However, there was no significant difference (P> 0.05) in condition factor between the two seasons. In all the five species studied, the sex ratio did not deviate from the expected sex ration of 1:1. The b values were within the range of 2.2 and 3.4 in both the dry and the wet seasons respectively, indicating an isometric growth of the fishes. The condition factor (K) for all the five species from Lake Baringo was well above 1 suggesting a relatively good physiological condition of the fishes in the lake. The seasonal variation influenced the length-weight relationship of the fishes but did not affect the condition factor and the sex ratio of all the fish species in Lake Baringo. The authors recommend a further study taking into account the fluctuations of water quality parameters.
The Potential of Marine micro-algae grown in Wastewater to remove Nutrients and Produce Biomass
(Kenya Aquatica Journal, 2022-06) Swaleh Mariam; Abubakar Laila; Mwaguni Saeed; Munga Daniel; Okuku Erik
Abstract Wastewater is a free source of nutrients for microalgae cultivation as it offers an opportunity to produce biofuel hence, significantly lowering their production costs. Microalgae was cultured in wastewater to determine the optimal condition for nutrients removal and production of low-cost biomass. Three different microalgal cultures containing cyanobacteria (Oscillatoria sp.), chlorophyte (Chlorella sp.) and diatoms (Entomoneis sp.) were cultivated in various mixtures of wastewater in seawater, ranging from 0% to 60% volume by volume (v/v). A significant difference (p˂0.05) was recorded between the concentration of phosphates and nitrates before and after the experimental period for all the cultures. Removal of phosphates in the wastewater cultures dominated by Oscillatoria, Entomoneis and Chlorella ranged between 25.4%-86.3%, 14%-100% and 85.7%-100% respectively, while removal of nitrates ranged between 7.5%-64.8%, 8.5%-64.1% and 4.0-67.6% respectively. A significant difference (p˂0.05) was also recorded in the microalgae growth for the different wastewater concentrations. The cultures dominated with Chlorella showed highest biomass production at 60% wastewater concentration, while cultures with Entomoneis and Oscillatoria had highest productivity at 20% wastewater concentration. Seemingly, the optimal conditions of wastewater treatment and biomass production of microalgae depends on the species and nutrient availability.

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