A parasite has caused the loss of tens of thousands of salmon on fish farms along the west coast due to the recent "Indian summer" which has brought warm and calm sea conditions.
The parasite, a single-celled amoeba, has hit stocks on at least five large salmon farms. It was first identified in Ireland 20 years ago in wild fish but this is the first time it has caused serious problems on sea farms.
The Western Regional Fisheries Board said it was investigating reports of some farms suffering "losses of up to 75 per cent". It was aware of two incidences where large volumes of diseased fish were dumped and burned in Connemara.
The parasite impairs gill function and death is due to respiratory distress - what is described as amoebic gill disease. However, according to Mr Richie Flynn of the Irish Salmon Growers' Association (ISGA), the problem has been stemmed with the help of the Internet and contact with fish farmers in Tasmania.
"We searched the Internet, got in contact with them by e-mail, and established how to tackle the problem. No chemicals or antibiotics are necessary. It's quickly cleared up by immersing fish in fresh water," said Mr Flynn.
Fortunately, no new cases had been reported in the past three weeks. Asked to quantify the losses, Mr Flynn estimated it caused deaths in a handful of cases and "relatively high losses" in one or two cases.
The Western Regional Fisheries Board manager, Mr Michael Kennedy, said: "Our understanding is that one or two smaller operators were wiped out and other farms were badly hit. We have no firm evidence yet. But we have had numerous complaints of fish being dumped and burned."
He said the board was also investigating complaints of fish being dumped at sea. The outbreak was especially worrying as the parasite could cross species and affect crabs and sea urchins.
He criticised the way the board had learned of the outbreak (indirectly from third-hand sources). "Transparency is needed in fin fish farm operations. We should be automatically provided with full information on all disease outbreaks, including the number and extent of mortalities, and the current method of disposal of dead fish."
The ISGA accused the board of behaving mischievously as the fish farms had fulfilled their obligations by reporting to the Department of the Marine and Natural Resources, which had helped to tackle the problem. There was a logistics problem at first but an early warning system and water treatment facilities were now in place thanks to the Tasmanian fish farmers.
