Farmed Salmon Threaten Wild Salmon Gene Pool

Sterilizing farmed salmon is a good way to conserve the wild salmon gene pool, researchers say.

According to University of East Anglia researchers, farmed salmon are genetically different than wild salmon. However, they are just as fertile as their wild counterparts, meaning that they can invade wild salmon territory.

Millions of farmed salmon escape into the wild and they could deplete the salmon gene pool by mating with the wild population, researchers caution.

"Around 95 per cent of all salmon in existence are farmed, and domestication has made them very different to wild populations, each of which is locally adapted to its own river system," Prof Matt Gage from UEA's school of Biological Sciences, said.

"Farmed salmon grow very fast, are aggressive, and not as clever as wild salmon when it comes to dealing with predators. These domestic traits are good for producing fish for the table, but not for the stability of wild populations," Gage said in a news release.

For the study, researchers used in vitro fertilization tests to determine the fertility of farmed salmon. The tests were conducted in conditions that mimicked real-world scenarios. Researchers found that farmed fish were just as fertile as their wild counterparts.

 "The problem is that farmed salmon can escape each year in their millions, getting into wild spawning populations, where they can then reproduce and erode wild gene pools, introducing these negative traits.

Conservationists are worried that invasion of farmed fish will wipe out useful wild salmon traits such as body size, disease resistance and timing of migration, Gage said.

Farmed and Fertile                                                                                                               

The idea that farmed fish escaping into the wild is an ecological catastrophe has been around for quite some time now. Stanford researchers said in 2003 that farmed salmon are capable of establishing population and competing for resources with native salmon.  

Parasite infections that affect farmed fish have led to a reduction in populations of wild Atlantic salmon, said another report by Guardian published in 2011.

Other scientists have been looking for signs of infectious salmon anemia, or I.S.A., in Wild Pacific salmon, according to an earlier article in New York Times. The virus, which causes salmon anemia, destroyed several fish farms in Chile. The virus isn't harmful to humans, but can damage wild and farmed fish in the Pacific Northwest.

Genetically altered salmon posing a threat to wild population is also another hotly debated topic. Read more about it, here.

Sterile Farmed Salmon

Researchers say that sterilizing farmed salmon is a good way to ensure that they don't affect the wild salmon gene pool.

Inducing triplody, researchers said, will lead to farmed fish losing reproductive abilities. In this technique, fish eggs are pressure-heated just after fertilization. This leads to the fish developing normally, but with both sex organs.

The research was funded by Natural Environment Research Council (NERC) and the Royal Society and is published in the journal Evolutionary Applications.