Recent research by the Marine Institute indicates that salmon farming do not play a significant role in the low numbers of salmon returning to Irish rivers.
The research was based on tests of more than 350,000 fish over a nine-year period.
It claimed that the “level of marine mortality attributable to sea lice infestation is very small — approximately 1%”.
The research was war-mly welcomed by Bord Iascaigh Mhara, which wants to develop a 500- hectare deep sea salmon farm 6km off Inis Oírr in the Aran Islands.
However, Save Bantry Bay, an action group fighting plans by Marine Harvest to develop a €3.5m organic salmon farm at Traflask, near Adrigole in West Cork, claims the new research does not discount long-held views, but rather supports them.
“Overall survival rate of salmon smolts coming back to the rivers from sea is only 5% at the best of times.
“Everything at sea wants to eat them. But other recent international studies show that ‘sea lice-induced mortality is significant in just under 40% of the releases in the study’,” said Tony Lowes of Save Bantry Bay and Friends of the Irish Environment.
Karin Dubsky of Coastwatch also stated that the Marine Institute research “supports the view that infestation of outwardly migrating salmon smolts with salmon lice has a negative impact on fitness and can contribute to increased marine mortality”.
However, chief executive of Bord Iascaigh Mhara, Jason Whooley has said the study was “a confirmation of the validity of the approach BIM had taken with regard to the development of the salmon farming industry”.
“The scare stories in relation to sea lice being a threat to wild salmon, put out by the opponents of salmon farming, have no basis in scientific fact,” he said last week.
Inland Fisheries Ireland, which is in charge of the country’s rivers, has already said the Marine Institute study provides “clear acceptance of the negative impact of sea lice on juvenile salmon”.
“The debate can now progress to identify the best methodologies to reduce or eliminate this impact,” said IFI head of business development, Suzanne Campion in the days after the research was released.
“IFI would also like to see similar progress in relation to the issue of escaped farmed salmon.
“In recent years, approximately 5% of all juvenile salmon going to sea return back to their native rivers as adults to spawn.
“Precisely because natural mortality rates of salmon are high, even a proportionally small additional mortality from sea lice can amount to a large loss in salmon returning.
“To put this average 1% reduction in return rates, as reported by the MI, in context, if 3,000 salmon return to a river, and this represents a 5% return rate, a reduction in the return rate to 4% translates into a reduction of 20% of the adult salmon, or 600 fewer fish returning.”
Secretary of Save Bantry Bay, Alex O’Donovan said such findings should lead to a moratorium on the expansion of open net salmon farming in the National Seafood Programme 2007-2013.
And the chairman of Great Fishing Houses of Ireland, Patrick O’Flaherty said attempts by BIM “to pretend that salmon farming does not affect wild fish stocks would be, if not so serious, laughable”.
“They most certainly must cause raised eyebrows among the international marine science community who, almost to a man, cite aquaculture as a serious threat to wild salmon stocks,” he said.