SCOTS salmon are being dosed with chemicals to “armour plate” them and ensure more fish return from the ocean.
A three-year experiment has seen young fish taken from the wild and raised in pens.
Before being set loose they are being treated with a solution which prevents sea lice latching onto them as they begin their journey to open water.
The move has already increased the numbers of fish returning to some Scottish salmon rivers
As a result of the trial more mature fish are now returning to spawn in Scotland’s rivers – providing a boost for the multi-million pound industry.
The River Lochy, near Fort William and the Carron, in Wester Ross, have both benefited from the scheme.
In the Lochy and extra 400 fish have been caught by anglers, and increase of 10% and stocks on the Carron are said to have made a “phenomenal recovery” following years of dwindling numbers.
The scheme will now be expanded over the next few years, with up to 100,000 treated smolts set to be released.
The move will also help the farmed salmon industry on the West coast of Scotland to expand.
Evidence that sea lice from farmed fish have been harming wild stocks has previously held back growth in the industry.
Young wild salmon had to swim past cages of farmed salmon and were previously at risk of infestation from the variety of sea lice which affects farmed fish.
Jon Gibb, who manages a hatchery for wild fish on the River Lochy said the smolts were treated with an anti-sea lice medication called SLICE, provided by pharmaceutical firm Merck International after being raised in pens owned by a fish farming company.
The medication protects them for six weeks – long enough to swim past any fish farms and into open water.
He said: “Two weeks later, mingling with their truly wild brethren, the little treated smolts exit the river on their seaward journey – a veritable army of armour-plated young travellers.”
Wild salmon campaigners have long argued that breeding farmed fish in cages near salmon rivers is to blame for a decline in wild stocks, by spreading parasites among the fish.
But the farming industry has hit back, calling the campaigners ill-informed.
Mr Gibb believes the new treatment could lead to more harmony and cooperation between the two warring groups, and also help the economy.
He said: “the idea is that these fish return to the river and they not only boost the fishery potential, with the hotels, the pubs and garages that benefit from the spin-offs but it also adds to the long-term survival of the river. You have to think that for every adult female that comes back, it’s carrying about 5000 eggs with it, so that is boosting the future of the river. It’s restoration and enhancement at the same time and we are so encouraged by these trial results that the programme will now move into full production.
“it is fairly early days but I am utterly convinced, as a manager of the largest west coast salmon fishery, that this is the way forward for a few rivers on the west coast. If you can mitigate the impact of the farm, then it has a better future and the jobs stay.”
But Guy Linley-Adams who heads a campaign by the Salmon and Trout Association to protect wild salmon said: “I think the question you have to ask is why the fish farms want to fund this sort of work? They realise that fish farms, particularly those in inappropriate places at the mouths of wild salmon rivers, are very likely to have an effect on wild smolt leaving the river for the first time and swimming past lice.
He added that treatment with SLICE was a way of preventing farms from having to be relocated or for the industry to have to change its methods.