Farmed salmon are escaping from fish farms and interbreeding with wild stocks to a much greater extent than predicted, with a risk that the salmon's long-term genetic diversity may be irreparably damaged, according to a conservation expert.
In some rivers, as much as 90 per cent of salmon was "of farmed origin" confirming that not only are farmed salmon escaping from farms and found in such environments, but surviving and breeding, said Dr Malcolm Windsor of the North Atlantic Salmon Conservation Organisation.
As farmed salmon grew faster, wild salmon were likely to be displaced despite having much greater long-term versatility, he told a conference on "Salmon Aquaculture - the consequences for the environment and public health" in Dublin, which was sponsored by the European Parliament's Green Group.
His organisation was not against fish farming but would not allow the wild salmon to become "a museum piece".
The salmon farming industry had a history of "glossing over and dodging science", according to the former chairman of the UK Shellfish Association, Mr Allan Berry. The Atlantic salmon farming industry had risen from small beginnings fired by political pressure to provide employment in fragile rural economies.
Mr Berry said that his oyster fishery in Scotland was closed in 1993 and he believed salmon farming, with its use of the controversial anti-fouling agent TBT, had contributed to problems with his operation. The science on the effects of salmon farming was inadequate because it was not asking the right questions, he added.
This was most pertinent with the impact of huge discharges of organic wastes into coastal waters, "as they degrade, deplete oxygen and produce changes in dissolved nutrient ratios, affecting biological structure and activity. There are serious questions over the sustainability of such practices".
The conference was hosted by Ms Patricia McKenna MEP, who criticised the Irish Salmon Growers' Association for not attending. While salmon farming was important to the Irish economy, she cited concerns about its impact on water quality and the sea floor, and its use of chemicals.
Bord Iascaigh Mhara's aquaculture development officer, Mr Donal Maguire, said restriction of Irish salmon farm development due to inadequate legislation in the past may have been fortunate, as expansion now would be tightly controlled and closely monitored. Salmon farming accounted for £35 million of a £60 million industry, employing 1,000 people.
