scholarly journals The impacts of introduced species on lake ecosystems: A case of Lakes Victoria and Naivasha, Kenya.

2019 ◽  
Author(s):  
Nicholas Outa ◽  
Dan Mungai ◽  
James Last A. Keyombe
Keyword(s):  
Introduced Species ◽  
Fish Species ◽  
Largemouth Bass ◽  
Water Hyacinth ◽  
Native Species ◽  
Nile Tilapia ◽  
Lake Victoria ◽  
Nile Perch ◽  
Lake Naivasha ◽  
Lake Ecosystems

Fish and other aquatic organisms have been introduced into new environments for various reasons. Provision of sports fishery, supplemental to stocks, to fill empty niches, control weeds, and disease vectors and even create a commercial fishery are some of the reasons why fish species are introduced into new ecosystems. Lake Victoria and Lake Naivasha in Kenya have seen several introductions as discussed in this paper. In Lake Victoria for example, some of the species introduced include Nile perch, Lates niloticus, Nile tilapia, Oreochromis niloticus, Tilapia zilii, and Oreochromis esclentus among others. The most successful introductions have been that of the Nile perch, Nile tilapia and water hyacinth. Lake Naivasha too has witnessed a number of introductions into its fisheries too. Some of the successful introductions into the lake are those of the Common carp, Cyprinus carpio, the largemouth bass, Micropterus salmoides, the Nile tilapia, O. niloticus and Louisiana red swamp crayfish, Procambarus clarkia. Aside from the fish species mentioned, some invasive plant species have also been introduced into these two lake ecosystems. Of notable success and impacts have been the water hyacinth, Eichhornia crassipes and Nile cabbage, Pistia stratiotes. These introductions have had both negative and positive impacts on the fisheries and the ecology of the two lakes. Some of the impacts have been predation on the native species by the introduced species like in the case of Nile perch and largemouth bass in Lake Victoria and Naivasha respectively. Competition for resources and hybridization with the native species has also been witnessed in the case of the tilapiines in the two lakes with undesirable results. Blockage of navigation routes caused by the invasive plants has been a major problem in the two lakes sometimes leading to massive postharvest losses by the fishermen. On the other hand, some introduced species have led to an increase in fish landings as well as utilization of the niches that were initially vacant within these ecosystems. It can therefore be concluded that introduced species often have more negative effects on the native species and therefore such introductions should be based on sound scientific research in order to minimize their effects within the new environments.

scholarly journals Socio-Economic Drivers of Fish Species Consumption Preferences in Kenya’s Urban Informal Food System

2021 ◽  
Vol 13 (9) ◽  
pp. 5278
Author(s):  
Oscar Ingasia Ayuya ◽  
Katrine Soma ◽  
Benson Obwanga
Keyword(s):  
Fish Species ◽  
Nile Tilapia ◽  
Food System ◽  
Lake Victoria ◽  
Informal Settlement ◽  
Clarias Gariepinus ◽  
Future Market ◽  
African Catfish ◽  
Nile Perch ◽  
Haplochromine Cichlids

In an effort to contribute to resilient food and nutritional security in urban slums, a food system approach was applied to understand the key socio-economic factors driving fish species consumption in Kibera, the largest informal settlement in Africa located in Nairobi, Kenya. Data were collected from 385 randomly selected households using a structured questionnaire. A multivariate probit model was applied to estimate the relationship between the variables in order to determine the socio-economic drivers of preferences for different fish species. The results indicated that Lake Victoria sardine (Rastrineobola argentea) had the highest preference (73%) among the respondents, followed by Nile tilapia (Oreochromis niloticus) (70%) and Nile perch (Lates niloticus) (23%), respectively, with other fish species at 12%, including African catfish, marbled lungfish, common carp, fulu and tuna (Clarias gariepinus, Protopterus aethiopicus, Cyprinus carpio, Haplochromine cichlids and Thunnus sp., respectively). Large household size showed an increase in preference for the Lake Victoria sardine, while higher income influenced preference for Nile tilapia and Nile perch positively, implying that when more income is available, Nile tilapia is the preferred fish over other fish species. Increased fish prices positively influenced preference for Nile tilapia, which is explained by the willingness to pay extra for quality and origin, for instance, to avoid the cheaply cultivated Chinese fish. In the case of the Lake Victoria sardine, lower prices positively affected the preferences. Religious and cultural practices and beliefs influenced preference for species and consumption of fish. Residents who migrated from western Kenya had a higher preference for the Lake Victoria sardine, while residents born and raised in Kibera had a higher preference for Nile tilapia. Neighbourhood effects reduced the preference for consuming Nile perch. These findings provide insights into future market opportunities for specific target groups. For instance, given that small-sized fish like the Lake Victoria sardine is highly demanded, in order to increase resiliency in food and nutrition security, small-sized cheap Nile tilapia will have a large potential in the future, with ever higher demand specifically from the residents born and raised in Kibera.

Are fisheries management, measures in Lake Victoria successful? The case of Nile perch and Nile tilapia fishery

2007 ◽  
Vol 45 (3) ◽  
pp. 315-323 ◽  
Author(s):  
M. Njiru ◽  
P. Nzungi ◽  
A. Getabu ◽  
E. Wakwabi ◽  
A. Othina ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Nile Tilapia ◽  
Lake Victoria ◽  
Nile Perch ◽  
Management Measures

scholarly journals Ecology of the Critically Endangered Singidia Tilapia (Teleostei: Cichlidae: Oreochromis esculentus) of lake Kayanja, Uganda and its conservation implications

2020 ◽  
Vol 12 (10) ◽  
pp. 16251-16256 ◽  
Author(s):  
Richard Olwa ◽  
Herbert Nakiyende ◽  
Elias Muhumuza ◽  
Samuel Bassa ◽  
Anthony Taabu-Munyaho ◽  
...  
Keyword(s):  
Fish Species ◽  
Nile Tilapia ◽  
Fish Farming ◽  
Critically Endangered ◽  
Nile Perch ◽  
Introduced Fish ◽  
Plant Materials ◽  
Blue Green Algae ◽  
Conservation Implications ◽  
In The Wild

Singidia Tilapia Oreochromis esculentus is a Critically Endangered native tilapia fish species endemic to lakes Victoria and Kyoga basins of East Africa, however, it disappeared from these main lakes due to overfishing, environmental degradation and predation by the introduced Nile Perch Lates niloticus.  Remnant populations of this fish species is now restricted to satellite lakes including Lake Kayanja of the Victoria basin.  This study provides updated information about the population abundance, critical habitat, threats and diet of Singidia Tilapia to inform conservation decisions to revive its populations in the wild.  Fish data collection and mapping of nursery and breeding habitats of Singidia Tilapia on Lake Kayanja was conducted between February 2016 and October 2017.  In all the areas mapped and sampled, Singidia Tilapia (with a size range of 11–27 cm TL) was the most abundant (43%) relative to exotic Nile Tilapia Oreochromis niloticus (21%) and Redbelly Tilapia Coptodon zillii (36%).  The emergence of introduced (exotic) tilapias like Nile Tilapia recorded in this study could be attributed to cage fish farming being carried out in this Lake.  The diet of Oreochromis esculentus consisted mainly of detritus (60.8 %), plant materials (27.7%) and blue-green algae (5.5%).  Destruction of critical habitats and presence of introduced fish species were noted as the major threats to this fish and its habitats.  The generated information could contribute to guiding stakeholders to undertake appropriate actions to conserve this threatened fish species and its habitats.

scholarly journals A review on the status of some major fish species in Lake Victoria

2019 ◽  
Author(s):  
Nicholas Outa ◽  
Edwin Yongo ◽  
Jameslast Keyombe ◽  
Namwaya David
Keyword(s):  
Fish Species ◽  
Lake Victoria ◽  
Nile Perch ◽  
Management Measures ◽  
Ecological Changes ◽  
The Status ◽  
Domestic Use ◽  
Food Fish ◽  
Labeo Victorianus ◽  
Alien Fish Species

Lake Victoria, the second largest freshwater lake in the world supports a huge flora and fauna with a large human population around the Lake. The Lake is a source of food (fish), water for domestic use and crop and livestock production, transportation, tourism among others. Due to its varied uses, human intervention within the lake and its catchment has caused several ecological changes in the recent years with profound effects on the resource resources. One of the most notable change is the reduction and risk of extinction of some fish species, including the endemic tilapiine species (Oreochromis esculentus and O. variabilis), catfishes (Xenoclarias eupogon), haplochromines and cyprinids (Labeo victorianus and Barbus altinialis) within the lake. The reduction in biodiversity and extinctions within the lake has been ascribed to the introduction of alien fish species (Nile perch (Lates niloticus) and Nile tilapia (O. niloticus) into the lake, habitat loss and the cultural eutrophication. These changes if left unchecked will have devastating effects on the lake’s resources and at large to people living around the lake and beyond who depend on the lake for their livelihood. There is, therefore, an urgent need for management measures based on sound scientific research to be taken in order to curb the loss of ichthyodiversity within the lake and to save livelihoods of the direct and indirect dependents of the lake

scholarly journals Status and targets for rebuilding the three major fish stocks in Lake Victoria

2020 ◽  
Author(s):  
Laban Musinguzi ◽  
Mark Olokotum ◽  
Vianny Natugonza
Keyword(s):  
Fisheries Management ◽  
Nile Tilapia ◽  
Lake Victoria ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Nile Perch ◽  
Fish Stocks ◽  
Illegal Fishing ◽  
Stock Status ◽  
Low Levels

AbstractWe determined fisheries management reference points for three major fish stocks in Lake Victoria (Nile tilapia, Nile perch and Dagaa) for Uganda and the whole lake. The aim was to ascertain stock status and define reasonable objectives and targets for rebuilding to sustainable levels. Dagaa was found to be healthy in Uganda and the whole lake but tending to overfished status. In Uganda, the stock status of Nile tilapia and Nile perch was recruitment impaired but tending more towards collapsed and overfished status respectively. In the whole lake, the stock status of Nile tilapia and Nile perch was collapsed and overfished respectively with the latter tending more towards recruitment impaired. Estimates of maximum sustainable yield (MSY) showed that catches could be increased under good management. Rebuilding the Nile tilapia and Nile perch stock biomasses to MSY level (Bmsy) could respectively increase the catches above the current level by 9.2% and 29.5% in Uganda and by 72.8% and 15.1% in the whole lake. The immediate objective for fisheries management should be to rebuild biomass for the Nile tilapia and Nile perch stocks to Bmsy. Elimination of illegal fishing practices has proved to be effective. In addition, management needs to keep catches at low levels until biomass for the stocks is ≥Bmsy for at least three consecutive years.

Are fisheries management, measures in Lake Victoria successful? The case of Nile perch and Nile tilapia fishery

2006 ◽  
Vol 0 (0) ◽  
pp. 061206032120001-???
Author(s):  
M. Njiru ◽  
P. Nzungi ◽  
A. Getabu ◽  
E. Wakwabi ◽  
A. Othina ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Nile Tilapia ◽  
Lake Victoria ◽  
Nile Perch ◽  
Management Measures

First evidence of microplastics in the African Great Lakes: Recovery from Lake Victoria Nile perch and Nile tilapia

2016 ◽  
Vol 42 (1) ◽  
pp. 146-149 ◽  
Author(s):  
Fares John Biginagwa ◽  
Bahati Sosthenes Mayoma ◽  
Yvonne Shashoua ◽  
Kristian Syberg ◽  
Farhan R. Khan
Keyword(s):  
Great Lakes ◽  
Nile Tilapia ◽  
Lake Victoria ◽  
Nile Perch ◽  
African Great Lakes

scholarly journals Fatty Acid Composition and Levels of Selected Polyunsaturated Fatty Acids in Four Commercial Important Freshwater Fish Species from Lake Victoria, Tanzania

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Agnes Robert ◽  
Prosper Mfilinge ◽  
Samwel M. Limbu ◽  
Chacha J. Mwita
Keyword(s):  
Fatty Acids ◽  
Polyunsaturated Fatty Acids ◽  
Human Health ◽  
Fish Species ◽  
Lake Victoria ◽  
Nile Perch ◽  
Commercial Fish ◽  
Tilapia Zillii ◽  
Significant Difference ◽  
Commercial Species

Fatty acids (FAs) particularlyω3 andω6 polyunsaturated fatty acids (PUFAs) play important role in human health. This study aimed to investigate the composition and levels of selectedω3 PUFAs in four commercial fish species, Nile perch (Lates niloticus), Nile tilapia (Oreochromis niloticus),Tilapia zillii, and dagaa (Rastrineobola argentea) from Mwanza Gulf in Lake Victoria. The results indicated that 36 types of FAs with different saturation levels were detected. These FAs were dominated by docosahexaenoic (DHA), eicosapentaenoic (EPA), docosapentaenoic (DPA), and eicosatetraenoic acids.O. niloticushad the highest composition of FAs (34) compared toL. niloticus(27),T. zillii(26), andR. argentea(21). The levels of EPA differed significantly among the four commercial fish species(F=6.19,  P=0.001). The highest EPA levels were found inR. argenteafollowed byL. niloticusandO. niloticusand the lowest inT. zillii. The DPA levels showed no significant difference among the four fish species studied(F=0.652,  P=0.583). The study concluded that all four commercial species collected from Mwanza Gulf are good for human health, butR. argenteais the best for consumption because it contains higher levels ofω3 FAs, mainly EPA.

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