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In six Norwegian rivers have salmon genetic material has been diluted as a result of interference from farmed salmon.
Asle Rønning
journalist
Saturday 20 August 2011
at. 5:00
The salmon genes are affected by escaped farmed salmon in six Norwegian rivers, according to a new survey. (Photo: Colourbox)
Norwegian rivers have unique salmon stocks that are the result of adaptations to the environment locally.
Now, says the most comprehensive survey of its kind that the genes of the salmon for at least six Norwegian rivers are affected by escaped farmed salmon.
This means that farmed salmon have successfully propagated in the river.
It was long uncertain whether farmed salmon on the run would be able to have offspring in the wild. The new results from the Institute, however, confirms findings from a smaller 2006 study that shows that the escapees have managed to put the genetic traces.
In addition to salmon lice have the risk of genetic pollution from farmed salmon has been one of the biggest concerns associated with the rapid growth in the Norwegian aquaculture industry.
The researchers compare genes from up to thirty-year-old samples and compare with current salmon genes.
The entire coast
In six of 21 investigated rivers, they can detect genetic changes that they believe can only be due to mixing of farmed genes.
The entire Norwegian coast could be affected. Effects of farmed salmon are found from Jæren in the south to the Varanger Fjord in the north.
The six rivers with proven genendringer is Berby River in Østfold, Figgjo in Rogaland, Lone, Vosso and Opo of Bergen and the western Jakobselv in Finnmark.
In 15 of the waterways that were examined were found changes.
Differences disappear
The researchers use a method in which they measure changes in so-called micro-satellite DNA.
The method says that stocks have become more similar to each other, and the researchers have no other explanation than interference from farmed salmon.
- We can not see that there may be other possible reasons behind the changes, says project leader Øystein Skaala at the Institute of forskning.no.
The method gives good indications of changes in the genetic material, but can not be directly associated with visible changes in how the fish looks or behaves.
Such changes may have come, and the fear is that the already vulnerable wild salmon stocks will lose important characteristics.
- Minimum Numbers
Norwegian farmed salmon is bred for the purpose of the fastest growing in protected cages. It requires different characteristics to survive in the wild - in sacking out on the rivers and the ocean.
The research results were presented in Trondheim recently, but has not yet been published in any scientific journal.
Skaala says that the method does not capture all changes in the salmon genes, emphasizing that the number six of the 21 rivers is a minimum figure. The salmon in rivers could be affected.
The researchers are also working on a new method, which looks at the so-called SNP markers in Atlantic salmon genes. This method can provide new and more accurate answers.
Extensive escapes
Extensive escaped from Norwegian fish farms has led to demands for restrictions in the production of salmon and the introduction of new technology to stop escapes.
Figures from the Institute shows that the number of reported escapes peaked with over 900,000 salmon escaped in 2006. In recent years, escapes been at a lower level, but it could be the big unknown.
Head Raoul Bierach in the Directorate for Nature Management said that the Directorate takes a serious threat of genetic effects on wild salmon.
- What concerns us greatly, is what happens with regard to the future - but also what may already have happened, says Bierach the forskning.no.
He points specifically to the situation on the west coast, where there has been a lot of escaped farmed salmon in a long time.
High proportion of escaped salmon
Bierach says that despite the reported escapes numbers have been lower in recent years, the proportion of escaped salmon in the rivers still high and stable - between 14 and 18 percent.
Many questioned whether the escape figures are correct.
- In summer, for example, we had a situation here in Trøndelag where it has been taken large amounts of farmed salmon without any known escapes, says Bierach.
The new findings may change the debate on the Norwegian aquaculture industry. Fisheries authorities ensure that the threat be taken seriously.
- This only confirms that there is a reason that both the government and the aquaculture industry focuses on the prevention of escapes, says Fisheries Minister Lisbeth Berg-Hansen in an email to forskning.no.
She refers to the government's two year old sustainability strategy for the aquaculture industry in which it outlined a number of measures, including secure cages and more research. It is just introduced new rules for the design of fish farms.
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Topic: Wild Salmon Genes Affected By Farming (Read 4558 times)