A disease which caused severe damage to fish farms in Norway, Canada and Scotland has been detected for the first time in Ireland - at a farm in Clew Bay, Co Mayo.
The Department of Communications, Marine and Natural Resources has confirmed that positive indication of Infectious Salmon Anaemia (ISA) was isolated during routine testing by the Marine Institute on August 1st, but stresses that there is no evidence of a clinical outbreak to date.
However, a day after the positive result, about 100 fish escaped from the farm into neighbouring wild fisheries, including the Newport and Burrishoole systems.
The Department says that many of these fish have been recovered, but the escape has caused serious concern to fishery owners.
Precautionary measures have now been put in place at the farm, while results of the testing are awaited from the international reference laboratory for the disease in Oslo, Norway.
The Department expects information tomorrow from the Office International des Epizooites (OIE) in Oslo.
If confirmation of the virus's presence is received, it will formally notify the European Commission and an Irish ISA Withdrawal Plan will be put into place, according to a senior official at the Department.
The fish on the farm owned by Seastream Ltd are clinically healthy and are showing no signs of the disease, but the owners have been asked to accelerate harvesting - which was due to take place this month anyway.
The locally owned farm is based at two sites - one in Newport Bay in the northeast of Clew Bay and one at Mulranny - and produces about 800 tonnes of rainbow trout annually.
There is one other farm in Clew Bay but it is 17 km away.
The escape of 100 fish on August 2nd was reported to the Department, but Mr Kieran Thompson of Newport House Hotel and fishery, said he was only informed of the seriousness of the situation on Friday.
Continued harvesting at the farm will only take place under supervision of the Marine Institute and the North-Western Regional Fisheries Board (NWRFB), the Department says.
It has asked the farm to complete its harvest by August 26th.
ISA can kill up to 25 per cent of fish on a farm if left untreated, but a system involving slaughter of fish and "fallowing" of infected sites for a six month period can contain the disease.
There is no evidence of a link between the virus in aquaculture farms and occurrence of the virus in wild fish.
However, Mr Kieran Thompson said that he was concerned about a possible negative impact, and said that fish had escaped from the suspect farm before now.
This could not be confirmed yesterday by the Department.
Mr Richie Flynn of the Irish Salmon Growers' Association (ISGA), speaking for Seastream Ltd, said that the farm owners were co-operating fully with the authorities and were taking it very seriously.
"We have to stress that all the fish are very healthy, but we are being ultra cautious," he said.
Prof Graham Shaw of the Save Our Sea Trout (SOS) association, described it as "a major disaster, but one which was entirely predictable. Sea farming of salmon and rainbow trout, as currently practised, is unsustainable," Prof Shaw said.
He has called for the immediate slaughter of the fish and full investigation by the Minister.
However, Mr Flynn of the ISGA said Prof Shaw was "scaremongering" at a time when no clinical outbreak was evident.
