Genetic improvement and utilisation of indigenous tilapia in Southern Africa
Aquaculture and Fish Genetics Research
Central Research Department (now Research and Evidence Division)
University of Stellenbosch
Africa, Southern Africa
To develop a reliable technology for mass production of genetically male tilapia (GMT) in O.mossambicus.
To analyse genetic resources and production potential of O.mossambicus in Southern Africa to aid exploitation through breeding programmes.
Many inhabitants of Southern Africa have very low proportions of animal protein in their diets. For example, the South African Medical Research Council has established that malnutiriton is evident among both permanent and seasonal labour forces in the Western Cape, especially among children.
Also, many parts of the region are suffering famine. Case studies have shown that tilapia is a very acceptable dietary item to such communities and is preferred to other low value fish such as carp. Very modest dietary supplements with fish protein are able to achieve striking results in most underweight children.
Also, aquaculture remains extremely under-developed in the region, and with stable or declining yields from once rich fisheries aquaculture expansion is required, in order to meet the growing demand for fish consumption and to provide alternative and diversified livelihood opportunities to resource poor rural farmers.
In many parts of Southern Africa the nile tilapia (Oreochromis niloticus, the commonly preferred tilapia species for freshwater aquaculture) is not endemic, but the Mozambique tilapia (O.mossambicus) is. Considerations of environmental protection of local biodiversity, which is being threatened by the introduction of exotic species such as O.niloticus, have led to the promotion of the Mozambique tilapia as a species that should be suited to small-scale aquaculture in southern Africa.
To develop an assembly of accessions of up to 15 strains of O.mossambicus from throughout Southern Africa. To conduct growth trials for a minimum of eight strains.
To undertake genetic characterisation of available strains of O.mossambicus using molecular markers to identify, where possible, levels of genetic variability, population structure and stock/species specific markers.
The adaptation and development of the YY male technology for production of genetically male tilapia (GMT) to strains of O.mossambicus.
On-farm trials of GMT.
Evaluation of potential social and economic impact of GMT production by small-scale farmers.
To address the current demand for uptake of tilapia technologies, and in particular its extension to other regions of South Africa.
To initiate the process of developing a strategy/policy for the sustainable development of indigenous aquatic resources, for aquaculture development in the Southern African region.
Progress and Impact:
Rational choice of most promising strains of O. mossambicus for use in small-scale aquaculture and for GMT production.
The successful completion of the nursery phase (Trial A) and the two grow-out Phases (Trial B) provided consistent and reliable information on the comparative growth performance of the various accessions of O. mossambicus in on-station environments. Four strains were identified as superior in terms of growth performance and are considered the most appropriate for the development of tilapia aquaculture in Southern Africa. Three of these superior strains were used in the development of the YY male technology breeding programme. The OVI for this output was met.
Recommendations on choice of strains, future strategies for further genetic improvement, and management of genetic diversity of O. mossambicus
Quantitative data and the molecular characterisation of strains in terms of genetic variation and phylogeographic relationships have provided important information with regard to the choice of strains, and strategies for further genetic improvement, as well as for the management of genetic diversity of O. mossambicus. During the workshop on ,Sustainable Development of Indigenous Resources for Aquaculture Development in the Southern African Region, it was apparent that valid concerns exist among stakeholders over the threats to genetic diversity of indigenous species, that will be posed by aquaculture development. The research demonstrated clear population structuring in O. mossambicus in southern Africa and thus demonstrated the utility of genetic markers as a tool for managing genetic diversity of commercially important species. The recommended strategy for further genetic improvement of the species for aquaculture development in southern Africa is that a selective breeding programme should be initiated utilising a base strain comprising of the Ndumu, Boesmans, Kasinthula and Makathini strains. A proposal has already been developed for such a breeding programme. However, with regard to conservation of key pools of genetic diversity, strains should also be maintained in isolation and these strains should be used for aquaculture locally under conditions where environmental impact assessment indicates that significant threats to indigenous genetic diversity would be posed by tilapia aquaculture development.
The OVI for this output was largely met as the results have been presented in various fora. It is apparent that University of Stellenbosch (UoS) and its partners will be the main responsible agencies for promoting and disseminating superior and improved strains.
Reliable genetic technology for the production of all-male O. mossambicus developed
The progress in the breeding programme towards the generation of YY males and the mass production of GMT was significant, but somewhat slower than projected. Results indicated that transfer of the technology to southern African O. mossambicus is viable although further work is required, including an element of selection for sex ratio, in order for the technology to be developed on a commercial scale. Availability of monosex seed in the best strains of the species would represent an important catalyst to tilapia aquaculture development in southern Africa.
The OVI for this output was not fully met but it is anticipated that YY males and GMT will be available for distribution within 18 months.
Benefits of application of GMT to small-scale aquaculture quantified
The socio-economic benefits of GMT technology to rural development could not be demonstrated or assessed, due to delays in GMT production. The assessment of the contribution of tilapia technology in general to small-scale aquaculture was however evaluated. The assessment concluded that tilapia has the potential to sustainably contribute towards small-scale aquaculture amongst rural communities, with significant benefits to the livelihoods of these communities in te
The project was successful in generating new knowledge on the genetic status of indigenous O. mossambicus in the context of both exploitation and conservation of this resource. The project also made significant advances with regard to the development of an improved breed of the species for aquaculture through identification of fast growing strains and the production of YY males which will lead to the availability of high yielding GMT. These strategic developments will provide a more competitive resource for aquaculture enhancing its efficiency and thus the profitability and sustainability of aquaculture systems in which it is utilised. With the central position and reputation of UoS within the informal aquaculture development "community" UoS and its partners will be the primary source of seed and broodstock of O. mossambicus throughout the region. In addition, the presence of the Project and the outputs of an improved fish have very much provided a focus and acted as a catalyst in promoting a greater awareness of the potential for the development of aquaculture systems based on this indigenous species. This awareness and interest is coming from agencies implementing rural development initiatives and business enterprises alike. This presents the very real prospect of project outputs impacting on target beneficiaries through direct uptake by rural farmers and indirectly through generation of employment and improved supply of affordable fish protein. With activities proposed and in place to move the development process from a strategic to an adaptive phase, the Project outputs are expected to directly benefit several hundreds of small-scale farmers and indirectly benefit many thousands of rural and urban poor, within 3-5 years.
Total Cost to DFID:
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