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Can Genetically-Sterilised Farmed Salmon Help Save Wild Populations?

27 March 2015

UK - Scientists at the University of East Anglia are researching whether genetically sterilising farmed salmon would prevent them from breeding with their wild counterparts.

It is hoped that inducing the condition, known as ‘Triploidy’, will help dwindling wild salmon stocks.

The project is possible thanks to a £300,000 joint grant from the Biotechnology and Biological Sciences Research Council (BBSRC) and the Natural Environment Research Council (NERC).

Wild Atlantic salmon stocks have declined by around 90 per cent to their lowest recorded levels. One of pressures behind this is salmon farming.

Lead Researcher Prof Matt Gage from UEA’s school of Biological Sciences said: “Around 95 per cent of all Atlantic salmon on Earth are farmed, and domestication has made them very different to wild populations.

“Farmed salmon have been selected over nearly 50 years for fast growth in dense rearing cages, and they have become more naïve at dealing with predators. These domestic traits are good for producing fish for the table, but not for the stability of wild populations, each of which is shaped to be perfect for their own natural river system.

“The problem is that hundreds of thousands of farmed salmon are lost each year, which can enter wild spawning populations, where they reproduce and erode wild gene pools, introducing these negative traits.”

The research project will investigate whether inducing a genetic condition called Triploidy effectively sterilises farmed salmon – so that if they do escape, they cannot disrupt wild gene pools.

Triploid salmon can be produced by exposing just-fertilised salmon eggs to high pressure, which stops the normal shedding of the second set of maternal chromosomes. The resulting offspring develops with the usual set of chromosomes from its father, but instead has two sets from its mother, which can induce sterility.

Prof Gage said: “This method is routinely applied for farming rainbow trout, and its implementation is now being considered for salmon. However, the reproductive effects can vary between individual species, so we will verify whether triploidy completely sterilises Atlantic salmon. If sterility is complete, this will provide an excellent biosecurity solution for wild populations when farm salmon escape into them.”

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