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Genetic Discovey Will Produce Healthier Farmed Fish

by Ellen Hardy
15 February 2008, at 12:00am

NORWAY - Norwegian researchers have identified a gene that controls a the fish's susceptibility to infectious pancreatic necrosis (IPN), a viral disease which has cost Norwegian aquaculture great losses.

This significant breakthrough in molecular research will aid productivity and profits for the aquaculture industry, as a result of fewer losses and better fish welfare, says Aqua Gen the company that discovered the gene.

The technology has already been implemented in the company's practical selective breeding, and it has plans to expand the research to include other important viral diseases, such as pancreas disease (PD).

Selecting

IPN has caused immense loss in the Norwegian aquaculture industry as a result, Aqua Gen started selective breeding to increase resistance against this disease in 1997. Methods which have been employed so far in this work are based on challenge tests and traditional quantitative genetics. Although a meaningful effect can be documented with this approach, the test methods that are used are quite expensive, and cannot be used in direct testing of breeding candidates.

In 2005 Aqua Gen started a three-year long user-directed innovation project with support from The Norwegian Research Council to identify the genes that are responsible for the salmon's ability to withstand the viral disease IPN.

Thomas Moen, AKVAFORSK, is the project leader and research has been carried out in the CIGENE-milieu at UMB. The investigations have identified key markers on the salmons' chromosomes which make it possible to identify IPN resistance directly in the fish by means of DNA analysis. The results of this analysis can be used alone in selection, or can be combined with results from challenge tests in order to further increase the accuracy of selection.

Genetic information has been identified that can explains about 70 percent of the genetic variation. The experiment design is so strong that the results have a very high level of statistical significance, saus Aqua Gen.

These findings and the fact that Aqua Gen's genetic population shows great variation (heterozygosity), makes this new technology a significant step forward in the work of improving disease resistance and robustness among farmed salmon. It has been possible to select random fish on the basis of the average performance of families, but this technology means it will be now possible to select the best genetic candidates within families through direct DNA analysis.

Already in Production

Initial steps to implement these results were made in the autumn of 2007. Breeding stock were selected for Aqua Gen's robust lineage among other things with the help of the new IPN-marker. This selected stock will be used to produce eggs for the aquaculture industry in the next generation.

An independent validation of these findings has been made by another research group in Scotland. It has shown the same genetic material in stock from Landcatch Natural Selection Ltd.

This project started one year before the Norwegian project, and the results have been recently published. Finding the same genetic material in two independent research groups in two different genetic sources is in itself a strong validation of the findings, says Aqua Gen. In addition, the company and AKVAFORSK have taken the research a step farther by identifying the position of specific genes with much greater accuracy, and by showing it has the same effect in fry as it does in the post-smolt stage.

The findings also signal that similar procedures can reveal other valuable genetic markers that could contribute to combating other important diseases of farmed fish.

Ellen Hardy