Salmon affected have a characteristic red-spotted rash on their underbelly and may appear lethargic or moribund. The rash can either be localised or extend along some or most of the fish.

As the disease progresses, skin lesions, signs of bleeding and skins ulcers can develop primarily along the belly area and extend to the head and tail. Secondary fungal infection can further develop, which may ultimately result in death of the salmon.

Fisheries staff are liaising with the Marine Institute Fish Health Unit and international colleagues to monitor and respond to the situation. As part of this, anglers and fishery owners are asked to report any incidences of RSD to help determine the occurrence of the disease.

Anglers who capture such salmon are advised to follow normal biosecurity procedures and disinfect tackle, waders and equipment. Until the cause of the disease has been determined and the risk of spreading the disease established, affected salmon should not be removed from the water.