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New measures to combat fish farm sea lice infection of wild salmon have come into effect.

The initial phase of the Scottish Environment Protection Agency (SEPA) regulatory system, which includes a network of protection zones in the Western Isles, means Scotland has become one of the first countries to tackle sea lice risks from fish farms on wild populations.

The introduction of the Sea Lice Framework earlier this month follows a two-year consultation and introduces regulations that SEPA say employ “a proportionate, evidence-based approach” that draws on international best practices and advanced scientific methodologies.

Reducing the risk of sea lice transmission from fish farms is seen as key to halting the long-term decline of the Atlantic wild salmon population. Sea lice are marine parasites that, if left untreated, can injure or kill salmon, spread rapidly on fish farms, and infect migrating wild salmon.

The new framework will influence the expansion of existing fish farms in the Western Isles and West Coast, as well as the evaluation of new farm applications. SEPA says the 120 or so areas identified in the Western Isles and along the West Coast are where migrating wild salmon are at greatest risk from sea lice.

The protection zones now in place are designed to steer aquaculture development towards areas of minimal sensitivity and enforce stricter sea lice control measures for finfish farm operators within these regions, the environmental agency said.

“Scotland is renowned for its salmon, with a leading aquaculture sector delivering high-quality produce across the world and contributing significantly to our economy,” said Peter Pollard, SEPA’s Head of Ecology, in a press statement.

“However, we know a range of pressures, including commercial aquaculture, habitat barriers, and invasive species, mean populations of wild salmon are dwindling here and across the North Atlantic.”

“SEPA is part of an international community working to address this shared challenge, with Scotland one of the first countries to take action to manage the risk posed by sea lice from fish farms. Reaching the first phase of the Sea Lice Framework’s implementation is an important milestone and achievement for all those who we have engaged with.”

Pollard emphasised the framework’s role in setting a regulatory precedent and its potential for industry adaptation.

“We’re confident the industry will be successful in adapting to this new regulatory landscape and look forward to continuing to work with producers and all other interests on future phases,” Pollard added.

In addition to the new framework, SEPA is also developing monitoring programs within the protection zones to give a more accurate assessment of sea lice impacts and thus guide future framework phases. This includes plans to protect sea trout populations from March 2025 in Scotland’s West Coast, Western Isles and Northern Isles. 

The introduction of the Sea Lice Framework follows a decision by Scottish Ministers in 2021 to assign SEPA as the lead organisation in managing sea lice risks to wild salmon and sea trout.

The more than two years of consultations with regulators, the fish farm industry,  environmental NGOs, coastal community groups, and wild fishery interests also included input from leading Scottish and Norwegian scientists.

However, the first draft met stiff opposition from the industry in Scotland and the trade body Salmon Scotland. The fish farm industry expressed concern that the plans as drafted amounted to over-regulation amid claims that sea lice are not a problem on fish farms. Outbreaks, it was claimed, are low, and the industry contended it was constantly innovating to address a naturally occurring problem.

After noting the feedback, SEPA said it had made numerous revisions to the implementation details and timelines.

Last year, conservation organisation WildFish released a report claiming the salmon farming industry was breaching its own guidelines on sea lice management, citing an example of one fish farm with five million lice.

Commenting on their findings, Rachel Mulrenan, Scotland Director of WildFish, said: “During the period of young salmon migration, when salmon are most vulnerable to sea lice due to their small size, the Scottish salmon and trout industry reported sea lice levels that exceeded the industry limits on 1 in 4 occasions. The Norwegian company Mowi recorded sea lice levels as high as 8.2 lice per fish on one of its farms, 16 times the industry limit, and 40-80 times higher than what would be permitted in the company’s home country of Norway.”

Wild Atlantic Salmon, one of Scotland’s most iconic fish, has seen stocks dwindle from eight to ten million in the 1970s to an estimated three million today.

The Scottish salmon farming industry produces 200,000 tonnes of fish annually, worth £360m to the Scottish economy.