Stockpiles of disinfectant have been sent to Scottish salmon fishery boards in an attempt to keep a deadly parasite away from native fish.

The measures, which also include sending out hundreds of warning signs, are aimed at protecting rivers from Gyrodactylus salaris (GS), which has already had a devastating impact in Norway.

The move comes as anglers gear up for the start of the salmon season on the River Tay on Wednesday.

Brian Davidson, director of the Association of Salmon Fishery Boards, said: "The consequences of GS entering a river system are extremely grave, the parasite is very destructive and is probably the single greatest threat to Scotland's salmon stocks.

"It's a hot topic at the moment, but we're confident enough has been done to keep it out Scottish rivers."

The association warns that the bug, which can be found in Scandinavia, France, Germany, Portugal, Russia and Spain, has the ability to wipe out wild salmon fish stocks.

Mr Davidson said about 1,200 warning signs have been sent to many of the 42 Scottish district salmon fishery boards over the past few weeks. The signs are being erected along river banks.

The disinfectant, called Virkon, would be used to treat fishermen's tackle and on canoe equipment which may have been taken to infected areas.

Mr Davidson said: "The signs are mostly to warn anglers and canoeists. These are the people most likely to have been abroad, perhaps Scandinavia or other countries.

"People will be asked to sign declaration forms to make sure they understand the risks and have taken appropriate action.

"The disinfectant is also something practical we can do."

He said the association worked with the Scottish Government on the scheme.

Signs are already in place at the major salmon rivers, such as the Tay, Spey and Dee, Mr Davidson said.

But some smaller rivers such as those in Argyll, the Western Isles and the south west had none.

The Scottish Government said it will conduct a "field exercise" this year to test contingency plans for contamination.

A delegation visited Norway last year to see how the problem has been treated there.

Under the Aquaculture and Fisheries (Scotland) Act 2007, powers are available to contain and treat an outbreak, should it be brought into Scottish waters.

Fears over Scottish fish stocks were raised earlier this month when Infectious Salmon Anaemia (ISA) was confirmed at a Shetland salmon farm.

It was also suspected at two further sites in the Burra area, west of Shetland.

The farm where ISA was confirmed has been empty of fish since December 21, while one of the other two sites has been empty for six weeks.

The government set up a national disease control centre and pledged to take action to control the spread of ISA - which does not affect humans but can cause serious damage to stocks of farmed Atlantic salmon in the sea.