Reduction of the “ngege”, Oreochromis esculentus (Teleostei: Cichlidae) populations, and resultant population genetic status in the Lake Victoria region

Ngege, Oreochromis esculentus, originally formed the mainstay of the Lake Victoria Region (LVR) fisheries. Together with its indigenous congener O. variabilis, it was displaced from Lakes Victoria and Kyoga of LVR and was found to survive as isolated small populations within the peripheral minor lakes and reservoirs around the two lakes. Displacement of the two LVR indigenous tilapiines was thought to be principally driven by changed lake environment and predation by the introduced Nile perch, but also competition and genetic swamping by the closely related introduced and comparatively more ecologically versatile tilapine species. In a study carried out in the LVR between 1993 and 2003, micro satellites and RAPD markers were used to analyse the remnant populations so as to establish the population structure and extant genetic diversity of O. esculentus. Analyses indicated that the surviving O. esculentus retained a high proportion of genetic diversity with high differentiation between units an indication of genetic exchange between indigenous and introduced Nile tilapia where the two forms co-existed. While this heightened concern for genetic swamping of the remnant population units by the introduced tilapiines it was noteworthy that in a few of the satellite lakes where the O. esculentus was dominant evidence for introgression was weak.

The bottom trawl survey of Lake Victoria, Uganda in July to August 2003

The objective of the bottom trawl survey in July/August 2003, was to monitor the changes in the fish stocks in the Uganda sector of Lake Victoria with particular emphasis on species composition, distribution, abundance and population structure.

Preliminary assessment of the artisanal fishery sector around Lac Maï-Ndombe in the Lac Tele-Lac Tumba (LTL) CARPE Landscape

The WorldFish Center was contracted by the World Wide Fund for Nature (WWF) to lead a preliminary assessment of the Lac Maï-Ndombe fishery, one of three water bodies for which such an assessment will be completed in the Lac Tele-Lac Tumba Landscape of the CARPE program. Between Aug.29-Sept.5, 2007, a joint WorldFish Center-WWF team traveled to Lac Maï-Ndombe in Bandundu Province, and conducted an analysis of the conditions surrounding the fishery and fisherfolk livelihoods in a total of 19 villages and camps. Included in this assessment were preliminary analyses of market-chain networks and stakeholders’ receptivity to NGO capacity-building to improve commercialization of fish catches and/or to introduce local fisheries management regimes. While perceptions of declining fish stocks prevail, the absence of changes in reported fish sizes bring into doubt any urgent need for fishery management interventions. However, lacking scientific fish population structure data the team would not recommend any NGO interventions to increase fishing effort. Lac Maï-Ndombe fisherfolk have highly diversified levels of dependence on fishing, and while there is evidence that some stakeholder groups are flourishing, the majority of the fishery appears to be characterized by a livelihood insecurity and a lack of capital. This limits fishers’ abilities to negotiate with transporters and with Kinshasa-based market brokers, and in combination with a heavy burden of rent-seeking behavior by civil servants, this condition forces over half of the fishers to sell their fish and buy all manufactured products through local intermediaries at disadvantageous prices.

Population genetic structure of Neogobius caspius (Eichwald ,1831) in the South Caspian Sea using PCR-RFLP Marker

Neogobius caspius is a small benthic fish that is native to the Caspian Sea. The importance of this fish is because of it is role as a main food resource of the sturgeon fish. The genetic diversity of N. caspius population in the Caspian Sea was studied using PCR- RFLP technique. A total of 135 samples of N. caspius were collected from coastal line in the north Caspian sea, including specimens from coasts of Anzali , Torkman Port and Chalus. Genomic DNA was extracted by phenol-chloroform method and then was amplified using a pair primer of cytochrom b gene, 2 tRNA gene and the control region sequences by a thermal cycler. D2 (5'-CCGGAGTATGTAGGGCATTCTCAC-3'), CY1 (5'-YYTAACCRRGACYAATGACTTGA-3') 12 restriction enzyme were used to digest the target gene region including: Alul HincII —Tas1 —Rsa1 -MboI -DraI -BSeNI(BSRI) Alw261(BsmAI). Bsul 51 Hin11 Bsh12851- BsuRI(HaeIII) digested PCR products were observed by silver staining method followed by Polyacrylamide gel electrophoresis (PAGE). The results were shown the same pattern among the species. There was no polymorphism and no differentiation in population in the Neogobius caspius fish and all individuals have shown homogenous genotype.