An independent fish farming firm has unveiled Scotland’s first salmon fingerprint scheme to counter fakes.

Highland-based Loch Duart says fraudsters have been passing off lower-quality produce as its fish.

So starting next year it will new technology - pioneered by law enforcement to identify the backgrounds of human corpses - that will mean all of its salmon are traceable to each of its farms in Sutherland and the Hebrides.

Its move - unprecedented in Scotland - comes after the aquaculture industry aims to increase its annual value to £2 billion by the year after next, despite ongoing controversy over farming.

Scotland is this year expected to export £500m of salmon to countries outside the UK alone.

But premium producers like like Loch Duart, whose fish is aimed at an upmarket restaurant and hotel market, are concerned about their brand image.

Fish from premium producers should come with a plastic tag in the gills - or tails.

But fish do not have the complex electronic farm tagging of, say, Scotch beef with protected geographic indication or PGI, to ensure their provenance.

The firm’s sales director, Andy Bing, told The Herald he was aware of specific cases of disreputable wholesalers supplying generic fish while saying it was from Loch Duart.

Mr Bing said: “We know Loch Duart salmon being offered up to a high profile restaurant chain by a London-based wholesaler.

“This wholesaler wasn’t buying Loch Duart salmon but was passing off another farmed salmon as ours to get the contract.”

“A common ruse used by those ‘passing off’ other salmon as ours is to buy the odd case of Loch Duart salmon from our nominated distributor in Billingsgate market, open an account with a London restaurant using the Loch Duart sequentially numbered gill tags (from the genuine case), and then continue supplying using another, cheaper salmon but invoicing it out as Loch Duart salmon.

The firm has hired a firm called Oritain to prevent passing off. A spokesman explained how: “Oritain’s testing measures trace elements that occur naturally at each farm and are absorbed by the salmon raised there. Further analysis creates a unique fingerprint that is then used to verify the origin of the fish.”

Rupert Hodges, of Oritain, said; Our pioneering use of forensic analysis allows us to not only identify the country and region from which the salmon we test is from, we can actually trace it back to the individual farm.

“This means that from now on customers across the globe, can be assured that when they buy Loch Duart salmon, we can prove that it is what they are getting.”

Loch Duart produces about 5,200 tonnes of salmon a year and employs 115 people across North West Scotland.