Thousands of rainbow trout have been culled in a lake in Co Cork following an outbreak of a stress-related disease which could pose a threat to wild Atlantic salmon.
The trout were suffering from the most deadly form of ERM, (enteric redmouth disease) brought on by stress after mink attacked their breeding cages at Lough Allua in Ballingeary.
It was the first time in 30 years that mink had attacked the breeding cages used to stock the board's lucrative managed lakes in Cork and Kerry, Mr Aidan Barry, chief executive of the South Western Regional Fisheries Board, told this month's meeting at the fishery board headquarters in Macroom on Tuesday night.
Around 5,000 fish died after the attack, and an analysis of fish samples by the Marine Institute afterwards identified ERM, a disease rainbow trout are susceptible to, especially when stressed, Mr Barry said. Some 6,000 fish have now been culled and cages left empty for three weeks. The lake will be stocked with brown trout and rainbow trout inoculated against the disease will be reintroduced after a time.
The cages have now been protected against mink attack and mink traps have been set.
The damage has led to calls for the study of mink numbers in the area. The clean-up treatment had cost the board thousands, but the rainbow trout had the most deadly form of the American ERM disease and had to be culled.
If introduced into the managed lakes the disease would wreak havoc, and the variant identified in the Lough Allua fish is one which could be transferred to the wild Atlantic salmon, Dr Patrick Buck, assistant chief executive officer said. Other species were not susceptible to the disease.