Genetic status of selected fish taxa in relation to conservation of genetic and species diversity in the Victoria and Kyoga Lake basins

Cichlids are known for their explosive radiation especially in the African Great Lakes marked with a high level of lake endemism. These fishes have been characterized mainly along trophic and habitat differences, by variation in morphological structures such as teeth and jaws and by differences in body shape and coloration. Cichlids are important as a microcosm of macroevolution. The explosive radiation, young evolutionary scale, and the isolation of groups characterized with high levels of endemism and presence of living fossils makes the group important for evolutionary and genetic studies. Lake Victoria region cichlids which are isolated and relatively more recent in evolution were the last to be appreciated in their diversity. Recently Ole Seehausen has found scores of rock fishes in Lake Victoria which were up to then thought to be absent from the Lake and only known to occur in Lakes Malawi and Tanganyika. Greenwood put together the species groups of Lake Victoria, and later in the early 1980's revised the classification of haplochromine species to reflect the phyletic origin and interrelationship of the various groups in Lake Victoria region. Melan Stiassny has been interested in early evolution of cichlids while the likes of Paul Fuerst and Lees Kaufman and Axel Meyer have been interested and are working to explain the speciation mechanisms responsible for the explosive radiation and evolution of cichlids. Locally S.B Wandera and his student Getrude Narnulemo are spearheading the biodiversity and taxonomic studies of cichlids in Lake Victoria regio

A note on recent advances in the genetic characterization of tilapia stocks in Lake Victoria region

Oreochromis esculenta, the original "ngege" is virtually extinct in Lake Victoria, and is limited to satellite lakes and reservoirs in the greater Lake Victoria region. Oreochromis variabilis can still be found in Lake Victoria and some satellite lakes in the Kyoga System, but in small numbers and only at a few localities (WANDERA and KAUFMAN, unpub. data). Little is known about the influence that species translocations have had on the genetic structure of these crucial fishery species, and even the source of the parent stocks for the introductions remain obscure. Genetic variability was examined within and among allopatric populations of three species in the tilapiine genus Oreochromis: O. esculentus (endemic to Lakes Victoria and Kyoga), and two exotic species introduced to Lake Victoria in the late 1950's to supplement the failing fisheries for native tilapiines, O. niloticus and O. leucostictus

Characterization of genetic biodiversity of Nile perch, Lates niloticus, Tilapiines, Haplochromine flock and Ningu (Labeo victorianus) in the Victoria Lake Basin: an overview

Genetic biodiversity is the variation among individuals within and between units of interbreeding individuals (populations) of a species. It includes inheritable and transmittable differences that occur between individuals and/or populations of a given species through reproductive interaction. There exists enormous variability among individuals and/or populations of a species for most living organisms, and most of this variation is inheritable. differences among individuals arise through mutation and via recombination of genes during meiosis. These differences are then transmitted to successive generations through sexual reproduction and maintained in the populations through processes such as natural selection and genetic drift. Unfortunately much of this variation is normally threatened and often in danger of extinction because most focus in conservation of natural resources is put at saving species or habitats than varieties or strains of a species

Use, Production and Existence of Local Artemia Resources in Uganda and Africa: A Review

The research was funded by National Agricultural Research Organisation (NARO) of Uganda. AbstractThis study was aimed at reporting the existing Artemia habitats, its use and production in Uganda and Africa as a continent. In light of the great importance of Artemia as a starter feed in the aquaculture industry, its current shortage in supply, the need for commercial exploitation of local Artemia resources and development of new Artemia resources. Over 50 peer reviewed journal articles were reviewed to provide an understanding of the current status of Artemia use, production and existence of local existing Artemia resources in Uganda and Africa as continent. The study revealed neither local occurring Artemia resources nor commercial Artemia production is currently existent in Uganda, with its use mainly restricted to a few existing commercial hatcheries. Generally Artemia use in Africa is mainly restricted to the few commercial fish hatcheries. Literatures points to North African countries boarding the Mediterranean to be leading in the number of Artemia sites and production in Africa. Keywords: Artemia habitats, Hypersaline lakes, Aquaculture DOI: 10.7176/JNSR/9-18-04 Publication date:September 30th 2019

Hatchability of Selected Commercial Artemia Strains Using Waters from Selected Saline Crater Lakes of Western Uganda

The research was funded by National Agricultural Research Organisation (NARO) of Uganda. Abstract Hatchability of Artemia strains; Artemia franciscana from Great Salt Lake (GSL), A. franciscana from salt ponds in Vin Chao (VC), Chinese strain (Chinese), TUZ Parthenogetic Artemia from Kazakhstan (TUZ) and Parthenogenetic Artemia strain from Siberia (PAS) was examined using waters from lakes Katwe, Mururmuri, Bunyampaka, Bagusa and Maseche. The study purpose was to identify the best performing Artemia strain as well as the best suited saline crater lakes in Western Uganda for Artemia production based on hatchability. Artemia cysts were hatched under conditions described by Van Stappen (1996) in fabricated Artemia hatching cones at a salinity of 40ppm, temperature of 27±2°C, and light of 2000lux.  Hatchability was monitored after 24hour and 48hour of incubation. Artemia franciscana (VC) had significantly higher hatching percentage than all tested strains (P-value <0.05).  Lakes Katwe, Bunyampaka and Maseche waters presented the highest hatching percentages therefore are best suited for Artemia production. Keywords: Artemia, Hatching percentage, saline crater lakes DOI: 10.7176/JNSR/9-18-05 Publication date:September 30th 2019

Widespread colonisation of Tanzanian catchments by introduced Oreochromis tilapia fishes: the legacy from decades of deliberate introduction

From the 1950s onwards, programmes to promote aquaculture and improve capture fisheries in East Africa have relied heavily on the promise held by introduced species. In Tanzania these introductions have been poorly documented. Here we report the findings of surveys of inland water bodies across Tanzania between 2011 and 2017 that clarify distributions of tilapiine cichlids of the genus Oreochromis. We identified Oreochromis from 123 sampling locations, including 14 taxa restricted to their native range and three species that have established populations beyond their native range. Of these three species, the only exotic species found was blue-spotted tilapia (Oreochromis leucostictus), while Nile tilapia (Oreochromis niloticus) and Singida tilapia (Oreochromis esculentus), which are both naturally found within the country of Tanzania, have been translocated beyond their native range. Using our records, we developed models of suitable habitat for the introduced species based on recent (1960–1990) and projected (2050, 2070) East African climate. These models indicated that presence of suitable habitat for these introduced species will persist and potentially expand across the region. The clarification of distributions provided here can help inform the monitoring and management of biodiversity, and inform policy related to the future role of introduced species in fisheries and aquaculture

A note on recent advances in the genetic characterization of Tilapia stocks in Lake Victoria Region

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Microsatellite DNA analyses reveal population subdivisions among the recently introduced Nile perch (Lates spp.) in Lake Victoria

Nile perch (Lates spp.) was introduced into Lake Victoria only five decades ago but is now well established and distributed throughout the lake. Given the extensive size of the lake, there is a possibility of isolation by distance that can lead to local adaptations. Microsatellite DNA variability was used to assess the genetic diversity and to define the population structure of Nile perch collected from 22 different geographical locations within Lake Victoria. In total, 432 individuals were genotyped at nine microsatellite loci. Analyses of multilocus microsatellite genotypes revealed that genetic diversity of Nile perch of Lake Victoria is relatively high (HE = 0.68). Results also reveal shallow but significant genetic differentiation (FST = 0.029, P < 0.05). STRUCTURE indicated that Nile perch of Lake Victoria was made up of two (K = 2) genetically distinct populations. Separate analysis for each of the two groups also revealed relatively high genetic diversity for each group (HE[N1] = 0.73 and HE[N2] = 0.64). These results are surprising given that Nile perch was only recently introduced and is known to be migratory by nature.We interpret these results in light of multiple introductions from two different source populations of Nile perch and discuss implications of these results for the region’s fisheries management.Key words: Lake Victoria, Nile perch, genetics, microsatellites

Morphological variation of Nile tilapia populations from major water bodies of Uganda

With increasing demand for improved farmed Nile tilapia (Oreochromis niloticus) fish seed, there is heightened demand for quality and proven broodstock by hatchery operators throughout the country and in the East African region. Uganda, fortunately, is endowed with vast natural Nile tilapia (Oreochromis niloticus) stocks in lakes Albert, Edward and George, as well as in Albert Nile River. To aquaculturally benefit from the different attributes of different stocks/strains, it is important to establish the existing strains in a manner that is phenotypically discernible where such differences are apparent. In this study, we used a suite of morphological traits to identify strains of Nile tilapia among 425 individuals sampled from the four major water bodies, lakes – Albert, Edward-George, Kyoga and Victoria. Morphological variation was investigated using multivariate approaches including principal component analysis, discriminant analysis and cluster analysis of 22 morphometric characters. These analyses indicated that there was high morphological variation among the different populations of Nile tilapia and the fish could be grouped into their respective sampled areas based on these morphological differences. Most of the variation (86.97%) was associated with the fish body size, the peduncle length and the interorbital distances. Findings imply that there are four major Nile tilapia strains in Ugandan waters that will be subjected to aquaculture performance evaluation before being used in the genetic improvement programme to produce improved Nile tilapia fish broodstock/seed for use in fish farming. Differences among populations may reflect genetic differences and/or environmental factors.Keywords: Morphometrics, Oreochromis niloticus, strain identificatio