DEVASTATING outbreaks of sea lice are costing Scotland's lucrative fish farm industry £300 million a year as tough new restrictions to halt the spread are introduced.

Campaigners who want more stringent controls on sea lice in salmon farms claim tighter rules are being resisted by the fish farming industry.

They say documents obtained under Freedom of Information laws show the parasite is costing the industry £300m a year.

New Scottish Government rules, which come into force on April 1, mean that any fish farm found to have a sea lice infestation above a certain threshold will then have to draw up an action plan in conjunction with the Fish Health Inspectorate.

Fish farming is estimated to be worth £650m and supports around 8,000 jobs but it is estimated by that one in five farms would fail the new tests.

Scotland is the largest producer of salmon in the EU and the third largest in the world, sustaining many fragile communities in the Highlands and Islands.

But the Global Alliance Against Industrial Aquaculture (GAAIA) claims the industry is not sufficiently tackling the devastating problem of sea lice.

Don Staniford, the controversial spokesman of the GAAIA, said: "The fact that salmon farming's biggest cheerleader, the Scottish Government, is reading the riot act is symptomatic of the industry's escalating problems."

He highlighted a private briefing paper sent to the Cabinet Secretary (Fergus Ewing) in August which said: "Industry are engaged in improving sea lice management but remain resistant to increased legislative controls citing lack of evidence of impacts and significant commercial risks associated with offences or Enforcement Notices."

Meanwhile a letter in October from the Scottish Government's Marine Laboratory in Aberdeen conceded that since 2007 the sector had been hit hard by "reduced efficacy of sea lice treatments, the emergence of amoebic gill disease and increased challenges associated with sea lice control, all contributing to increased sea lice numbers across the Scottish salmon farming industry".

Another document from Marine Scotland said: "Recent analysis suggests that parasites account for an annual loss of up to 16.5 per cent of the value of UK aquaculture production. The vast majority of this relates to the treatment of sea lice."

Mr Staniford said since Scottish aquaculture production was valued at £1.8 billion in Scotland Food & Drink's 2016 publication "Aquaculture Growth to 2030", the annual losses due to sea lice could be around £300 million.

Campaigners have long argued that information on rates of sea lice infestation should be published for each fish farm, and another briefing paper in July 2016 admitted that: "Scotland is arguably out of kilter with the other major salmon producing countries in terms of sea lice publication and the industry’s inability to manage sea lice infestation better makes it challenging to hold this line."

Mr Staniford said "Instead of allowing the industry to hide from public scrutiny, the Scottish Government should publish site specific sea lice data as is already the case in Norway, Ireland and Canada. Salmon farms breaching sea lice limits should be named and shamed and then closed down if non-compliance continues."

Industry body the Scottish Salmon Producers Organisation declined to respond to Mr Staniford, but a Scottish Government spokesman said ministers recognised that sea lice management presents a major challenge:

“We have worked cooperatively with the aquaculture industry to agree a new sea lice management policy, which represents a significant step forward in regulatory control of sea lice levels. We consider this change will result in improvements to the management of sea lice by the aquaculture industry in Scotland. It is the aim of both the Scottish Government and the Scottish aquaculture industry to manage sea lice to the lowest achievable level.

“As with any new policy, this will be reviewed on a regular basis to ensure that Scotland’s legislative and regulatory framework continues to provide the right balance between sustainably growing aquaculture and protecting the environment,” he said.