Escapee farmed salmon infiltrate fitter wild populations

Genomewide evolutionary changes in farmed salmon adds further threats to wild populations

There is growing concern about the threats that farmed Atlantic salmon escapees constitute to wild salmon populations.

Consumers and environmentalists are concerned about farmed salmon yet heritable changes that have accumulated in farmed strains at the genetic level are largely unknown.

In new research published in the journal Molecular Ecology, researchers have found scientific evidence that farmed salmon have evolved genetically differently to wild salmon, therefore backing claims that any integration of farmed salmon back into the wild through escapees could have a negative impact on the health of wild salmon populations.

Christian Roberge and Louis Bernatchez, two of the co-authors on this research paper explain: “Using a 3,557 genes microarray and a unique set-up in which farmed and wild salmon of the corresponding natural population were grown in identical conditions, we document for the first time genome-wide changes in transcription profiles that evolved in parallel between farmed strains from North America and Europe within five to seven generations.”

“The magnitude of the accumulated differences was of approximately 20% for 1.5% of the expressed genes in juvenile salmon. These findings provide support to the claim that hybridisation with farmed escapees may alter the gene pool of wild salmon, reduce its fitness and accelerate its decline.”