Single sex 'superfish'
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CTA. 1996. Single sex 'superfish'. Spore 64. CTA, Wageningen, The Netherlands.
Permanent link to this item: http://hdl.handle.net/10568/47382
The mainstay of small-scale aquaculture for many poor farmers, particularly in Africa and Asia, is the Nile tilapia ( Oreochrornisniloticus). However, because it achieves sexual maturity while still very small, uncontrolled reproduction leads to...
The mainstay of small-scale aquaculture for many poor farmers, particularly in Africa and Asia, is the Nile tilapia ( Oreochrornis niloticus). However, because it achieves sexual maturity while still very small, uncontrolled reproduction leads to harvests which contain many small fish of low nutritional and commercial value. Having fish of only one sex in a pond would therefore be an advantage and, in the case of tilapia, the desired sex would be male, as they grow faster than females. During the last ten years scientists at the School of Biological Sciences at the University of Wales, Swansea, supported by the ODA Fish Genetics Research Programme, have succeeded in the production of a reliable technology for generating male monosex fish. Some male fish are treated with hormones, changing them to females. These are then crossed with normal males and some of their progeny are 'supermales' males who produce only male (genetically male tilapia or GMT) offspring when bred with normal females. The GMT, without the distraction of females, can put all their energy into growing quickly. Techniques developed earlier for producing male tilapia used male hormones to convert female into male fish and meant that the hormonally treated fish were the ones that were harvested and eatem The use of GM 1 fish produces higher yields of larger and more uniform fish than nonGM l fish and ones that are several stages removed from the hormone treated fish. In the Philippines and Thailand on-farm trials showed that, despite differences in husbandry and other variables between farms, the overall increase in net returns for the same inpults was very consistent between pond, cage and tank culture conditions, with the increase averaging about 120%. The technology is proving very popular with farmers in these countrles. Professor J A Beordmore Proglomme Manager ODA Fish Generics Research Programme School of Biological Sciences Singleton: Park Swansea SA22 8PP UK