Scottish salmon farmers who do not adopt closed containment systems will not be able to get accreditation from the World Wildlife Fund (WWF), the organisation's final draft standard says. The draft will lead to certification for farmed salmon through the Aquaculture Stewardship Council (ASC).

Currently, almost half (more than 17 million) of the farmed salmon smolts raised in Scotland are held in net pens within freshwater lochs, the majority of which have populations of native migratory fish such as salmon and sea trout.

The Scottish Salmon Producers' Organisation (SSPO) would only tell FF&FT: "We are considering the content of the 74 page draft standards and will submit any appropriate comments before the end of the consultation process.”

However, welcoming the draft, Tony Andrews, Chief Executive of the Atlantic Salmon Trust (AST) said: “We believe this sends a very strong message to Scottish politicians, who have dragged their heels on the issue of smolt pens in salmonid lochs. Scotland has been lagging behind in adopting closed containment technologies for raising smolts.

“Recirculating aquaculture systems (RAS) are used for this stage of farming in the other countries which produce salmon, so the technology is thoroughly tried and tested, and easily available. We simply do not believe that salmon can be farmed sustainably in open net pens in freshwater systems which contain migratory fish.”

Dr Andy Walker, Chairman of the Sea Trout Group, (STG) said: “The presence of these pens appears to be interfering with the natural behaviour of migratory fish. It’s also generally accepted that, alongside the occasional and well-publicised large-scale escapes from such pens, there’s an ongoing ‘leakage’ of small numbers of fish, amounting to large numbers over time. These losses of fish from captive culture pose a very serious threat to the gene-pool of wild salmon.

“In addition, while fish farmers may do all they can to avoid diseases among their stocks and treat them where they need to, we are concerned that open pens containing intensively reared fish increase the risk of pathogens spreading to susceptible wild fish, whose health status is very difficult to monitor effectively and whose treatment in the event of an outbreak is completely impracticable.

The draft criteria for the ASC salmon standard will now go out to public consultation for 60 days. Details can be found on the WWF website at: www.worldwildlife.org

• Meanwhile, a new study by the Atlantic Salmon Trust (AST) into sea lice and its impacts on wild salmonids looks set to put more pressure on the Scottish government to force salmon farmers to adopt closed containment systems. The study, Policy on the Management of Sea Lice, advocates a completely new approach to sea lice management. “We believe that what’s needed is what we’d term a ‘bay-by-bay’ approach,” said AST chief executive, Tony Andrews. “Experience has shown that the impact of salmon cages on lice loadings on wild salmon and sea trout differs from one bay/sea loch/fjord to another. This impact is dependent not only on how well salmon farmers control lice on their stock, but also on migration routes and feeding patterns of wild salmonids, and, crucially, factors such as prevailing currents and winds, the morphology of the bay/loch, weather patterns, etc.

“All of these factors have an impact on how sea lice larvae disperse and are transported within a sea loch, and the consequent risk to wild fish.”

The AST says it is not pointing the finger at the salmon farm industry but says there is nevertheless a “demonstrable” need for a strong, mandatory basis for localised management and that existing regulations and rules are fully enforced in countries such as Scotland and Ireland. The policy calls for mandatory single-generation management of sea lochs/bays, and synchronised fallowing and treatment regimes, plus officially validated lice monitoring regimes, with results publicly available.