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Lice Research Deals Blow to Fish Farming

CANADA - Rather than benefiting wild fish, industrial aquaculture may contribute to declines in ocean fisheries and ecosystems.

Recently published research suggests that farmed salmon are commonly infected with salmon lice (Lepeophtheirus salmonis), which are native ectoparasitic copepods. This is a major threat to wild populations because the results suggest that salmon farms act as a reserve for parasite populations and can cause outbreaks that erode the capacity of a coastal ecosystem to support wild salmon populations.

Not 'bearing' up. Wild salmon stocks are affected by the presence of aquaculture. Fish farms habour more parasites than coastal ecosystems can cope with, says research.

The studies, conducted at the Universities of Edmonton in Alberta; Dalhousie in Halifax, Nova Scotia and at the Salmon Coast Field Station, Simoom Sound, British Columbia, shows that recurrent louse infestations of wild juvenile pink salmon (Oncorhynchus gorbuscha), were all associated with salmon farms. The infestations have depressed wild pink salmon populations and placed them on a trajectory toward rapid local extinction.

The louse-induced mortality of pink salmon is now commonly over 80 per cent and exceeds previous fishing mortality. Researchers say that if outbreaks continue, then local extinction is certain, and a 99 per cent collapse in pink salmon population abundance is expected in four salmon generations.

Environment and conservation groups have welcomed the research. They say it confirms the devastation caused by intensive aquaculture and the need for greater controls. The industry is far from sustainable and very damaging.

“This study conclusively demonstrates that industrial salmon farming in British Columbia, has seriously undermined the health and welfare of surrounding wild fish populations," said Wenonah Hauter, Executive Director of Food & Water Watch.

Intensive aquaculture is not sustainable. It can undermine surrounding wild fish populations, says pressur groups.

She said that this research proved that industrial fish farms were causing more harm than the commercial fishing industry that used to exist in the area.

“This is precisely the same sort of unforeseen consequence that needs to be studied and addressed before our nation plows forward to allow industrial fish farming in federal waters as the Gulf of Mexico Fishery Management Council is now proposing to do," said Ms Hauter.

She said that the Council’s action was ostensibly premised on reducing commercial fishing’s stress on wild fish populations; however, the plans were likely to cause more problems.

"The plan to raise fish could be extremely detrimental to marine resources in the Gulf. More studies like this one will continue to prove that offshore aquaculture is not the solution. We need to find sustainable alternatives to easing pressure on our collapsing wild fish populations,” she added.

The Canadian Research Project was carried out by Martin Krkoek, Mark A. Lewis and Subhash Lele of the University of Edmunton; Jennifer S. Ford and Ransom A. Myers of Dalhousie University Alexandra Morton, Salmon Coast Field Station

For more information visit: www.sciencemag.org

Ellen Hardy

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