A small number of salmon returning to Irish rivers are showing signs of bleeding and skin ulceration, according to Inland Fisheries Ireland.
The red rash skin disease is also present on some salmon returning to Norway and Scotland.
Salmon first began appearing in Irish rivers with these symptoms in early June and by mid-June, fish with ulceration were reported in at least six rivers on the east and west coast of Ireland.
Affected salmon show signs of bleeding, ulceration and hemorrhaging, mainly along the belly and the head and tail areas. Secondary,fungal infection normally sets in and may result in death of the salmon.
Inland Fisheries Ireland is working with the Fish Health Unit in the Marine Institute to sample live salmon in affected rivers to determine the cause of the skin disease.
Until the cause of the disease has been determined and the risk of spreading is established, affected salmon should not be removed from the water.
Anglers who capture salmon with these symptoms are advised to follow normal biosecurity procedures and disinfect tackle, waders and equipment.
“It is unclear at this time what is causing these symptoms. There is some evidence that the disease may become less frequent with rising water temperatures and the problem has been worst in multi-sea-winter fish entering rivers early in the year in Norway and Sweden,” explained Dr Paddy Gargan, Senior Research Officer, IFI.
There is also a suggestion that the disease is related to a change in salmon diet but this has not yet been established.
“We are asking anglers and fishery owners to report any catches of salmon with these symptoms to us as soon as possible,” he added.
Anglers and fishery owners are being asked to report incidences of salmon with ‘rash like’ symptoms to the IFI or by calling 1890 347424 or 1890 FISH 24