Sterile salmon. (Photo Credit: AquaGen)
Sterile-bred salmon can help control interbreeding with wild stocks
Thursday, August 29, 2013, 02:30 (GMT + 9)
New scientific findings can bring a solution to farmed salmon interbreeding with wild specimens by successfully producing sterile salmon.
Escapee farmed salmon has long posed problems to desperate salmon producers worldwide anxious that they would reproduce with their wild counterparts, thus challenging the genetic purity of the species. Now, thanks to new scientific developments regarding the salmon’s genetic map, all this is about to change.
“If we succeed in producing sterile salmon on an industrial scale, we can substantially reduce the negative genetic impact on wild fish populations,” comments Arne Herre Staveland, who leads farmed fish production at Eide Fjordbruk. His aquaculture company is one of the six that are participating in a new project to breed genetically modified sterile salmon in captivity.
Triploid salmon can be produced by exposing salmon eggs to high pressure so as to obtain offspring having the usual one set chromosomes from its father but two from its mother, instead of having only one set of chromosomes from each parent. The extra set of chromosomes prevent the development of viable eggs or sperm, thus yielding sterile offspring.
Sterile specimens are bigger and grow faster than their diploid counterparts since they utilize the ATP they would normally use up during reproduction to grow, yielding much bigger offspring.
This technique is not new but it has proven to be quite challenging to breed sterile salmons in large numbers using this method without obtaining fish with genetic malformations. The technique, developed in the 80s and 90s, has already been successfully applied to other salmonids such as the rainbow trout in Tasmania, France and Scotland.
Now, thanks to new findings in mapping the complete Atlantic salmon (Salmo salar) genome sequence -- as to 2010 there was no genome sequence available for any salmonid --, this previously discouraged technique is seeing new light.
Geir Lasse Taranger of the Institute of Marine Research in Bergen says: “New research indicates that we can prevent the skeletal problems by modifying the diet. Also, new molecular tools help us to better understand how triploid salmon respond to different environmental conditions, which enables us to develop better protocols for how to farm them.”
Triploid salmon are more sensitive to low oxygen concentrations and warmer temperatures. Scientists and producers are now conducting tests on how resistant these triploid fish are to conditions at sea. They also have different nutritional needs than normal salmon as they grow faster, so production methods would also need to be adapted.
The problem is of particular interest to the Norwegian scientific community given the important salmon production in the country, which is reflected in Norway’s gastronomic habits.
The study has been partially funded by the Research Council of Norway in close cooperation with the aquaculture industry.
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- Aquaculture researchers work to develop sterile fish
By Gabriela Raffaele