The new scare involving Infectious Salmon Anaemia in the Shetland Isles, the Western Isles and Orkney has prompted the Scottish Executive to embark on an urgent review of the present controls.

A spokesman confirmed these were among the first cases in the world of the ISA virus being detected in wild salmon.

These latest figures bring to 24 the total number of farms in Scotland which have been suspected of having the disease over the last 18 months.

Further investigation

Announcing the review, Fisheries Minister John Home Robertson said: "This is disappointing news. It comes at the end of the year when there have been few outbreaks and we have lifted restrictions in some areas.

"Of course we will be carrying out our usual investigations into the source of the infection on the new farms but, as well as fulfilling our responsibility to impose controls on these farms, we are urgently considering the implications of this new evidence that the virus is present in wild fish.

The industry supports thousands of jobs

"That means we will be reviewing our current controls and will be taking stock of what action may be necessary in relation to wild fish.

"The disease has no implications for human health but can have devastating effects on fish farms. I want to stress therefore that we intend to continue to do everything possible to stamp out the disease where it is found."

Andrew Wallace, director of the Association of Salmon Fishery Boards, said the effects on wild salmon were unknown but this was a potentially serious threat.

He accused the government of playing "Russian roulette" with Scotland's wild salmon stocks.

The association, which represents the 52 fishery boards, wants tougher controls on the fish farming industry to prevent cross-contamination from escaped salmon.

Affected areas

The farms affected include three on Shetland, two in the Western Isles in Loch Roag and one in south Orkney.

The virus has been detected in sea trout in Laxo Voe, Shetland; and the River Snizort in Skye and Eel in Loch Uisg, Mull.

"Russian roulette", the industry says

Other results indicate it could be in brown trout in the Rivers Conan and Easaidh; Atlantic salmon parr in the Rivers Conan, Easaidh and the Tweed and rainbow Trout in freshwater farms in Aberdeenshire and Kinross-shire.

In February, Scottish salmon farmers were offered a £9m government compensation package for fish damaged by ISA.

Under the previous Scottish Office the money was only going to be made available if the industry matched the government's contribution pound for pound.

But the Scottish Executive changed the rules and the unconditional funding will be channelled through Highlands and Islands Enterprise.