Deadly ISA fish disease hits Scotland

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An infectious disease which can devastate stocks of farmed Atlantic salmon has been reported on a fish farm in Scotland.

An infectious disease which can devastate stocks of farmed Atlantic salmon has been reported on a fish farm in Scotland.

The potentially deadly fish disease Infections Salmon Anaemia (ISA) was discovered in a fish site near Burra, Shetland that had been empty of fish since December 21. The disease is also suspected in two other fish farms in the area.

ISA is a serious viral disease of both wild and farmed Atlantic Salmon in seawater. It may also affect wild populations of the Brown trout (Salmo trutta), Rainbow trout (Oncorhynchus mykiss), and herring.

The virus affects the lining of the blood vessels leading to haemorrhaging and severe anaemia and can cause up to 50% mortality.

Transmission is thought to be via movement of live fish, discharge of untreated blood and contact with infected vehicles and equipment. Infestation by sea lice is also thought to be a factor in infection. It does not affect humans.

Control measuresTo prevent the spread of the disease, European legislation states that all the fish at an affected site may have to be destroyed.

The Scottish Government have set up a National Disease Centre to control the spread of the disease in Shetland and movement restrictions have been placed on all farms within the control zone and a wider surveillance zone.

The Fisheries Research Service is sending a team of inspectors to assess the infected sites, investigate the source and spread of the disease, and advise the industry on control methods necessary.

An outbreak of ISA in 1998 and 1999 on Shetland, the Western Isles and Orkney was estimated to have cost the industry anything up to 100million and led to the loss of 200 jobs. In 2007 over 1 million fish were slaughtered in Chile when found to be infected with the virus.

Environment Minister Michael Russell told the Scottish Government news site: "Whilst this disease is serious, much was learned from the successfully contained outbreak in 1998/99. We will be applying those lessons vigorously with the clear aim of containing and then eradicating the disease from the current affected site.

"To prevent the spread of any disease present, the harvesting of fish from neighbouring sites will be conducted under bio-secure conditions and supervised by the Fisheries Research Services."

Scotland is the world s third largest producer of Atlantic salmon, with sales of about 300 million per year and around 8,500 jobs supported.