IT sits in a remote river where the young fish should evolve in the pristine waters before becoming fully grown and part of Scotland’s £1billion farmed salmon industry.

But campaigners are calling for a salmon hatchery to have its licence revoked amid concerns it was found pumping sewage into a protected river where endangered freshwater pearl mussels are found.

Kinlochmoidart Hatchery, in Lochaber, was branded as “very poor” during a Sepa inspection of the site in 2017.

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Now email exchanges uncovered as the result of a Freedom of Information request by campaign group Scottish Salmon Watch (SSW) have revealed concerns that effluent waste from the farm was encroaching on environmentally sensitive areas of the River Moidart.

The river is designated as a Special Area of Conservation due to the presence of rare protected freshwater pearl mussels that are on the brink of extinction after decades of illegal pearl fishing, poor water quality and habitat damage.

The emails, which span a year and include images that appear to show pollution from the fishery floating on stretches of the river, reveal increasing frustration from one of the environment protection agency’s senior environment protection officers over the farm operators’ lack of action, despite pledges to carry out vital work to improve the effluent treatment system.

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Eventually, the Sepa officer issued an interim compliance assessment report that highlighted the “gross breach” of the operator’s licence caused by solid effluent, including clumps of fungal growths that had broken from the hatchery settlement tank and entered the river.

The report also highlighted the poor condition of the farm’s effluent treatment infrastructure, and the failure to deliver on agreements to improve it.

Concerns over the farm’s operation led to it being downgraded from a previous “excellent” status in 2014, to “poor” the following year and eventually “very poor” in 2017.

SSW is now calling on government agencies to halt operations at the fish farm by withdrawing the farm’s licence from its current operators, The Scottish Salmon Company.

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Don Staniford, director of SSW, said: “The Scottish Salmon Company has been found guilty by Sepa of gross pollution of the River Moidart, which is an EU-protected ‘Special Area of Conservation’.

“The time has come for Scottish Natural Heritage, ministers, Highland Council and Sepa to close down the Kinlochmoidart Hatchery which has plummeted from ‘Excellent’ to ‘Poor’ and now ‘Very Poor’.

The Scottish Salmon Company, which operates at 60 sites across the West Coast of Scotland and Hebrides and produces 30,000 tonnes of salmon a year, took over ownership of the Kinlochmoidart Hatchery after the issue of effluent matter seeping into the River Moidart had already been raised by the Sepa inspector.

A spokesman for the Scottish Salmon Company (SSC) said: “SSC acquired the Kinlochmoidart Hatchery in May 2017, midway through the period to which the Sepa report in question relates.

"As part of SSC’s long-term investment plan, the site was reviewed and improvement areas identified with significant investment and resource dedicated to ensure SSC’s commitments to environmental sustainability and fish welfare were met.”

According to Scottish Natural Heritage, freshwater pearl mussels are a UK wildlife crime priority and are tottering on the edge of extinction.

The River Moidart is said to support one of the largest and healthiest populations of freshwater pearl mussels in the UK.

A Sepa spokesman said: “Following repeated effluent breaches at the Kinlochmoidart Hatchery in 2017, an environmental plan has been agreed with the company to ensure that improvements are made to the hatchery’s site infrastructure, to bring the site back into compliance.

“Whilst environmental performance at the site is clearly unacceptable, overall compliance at the hatchery has shown improvement during 2018 and effluent quality sampling during 2019 has, to date, remained compliant”.