Image caption Scotland has more than 200 fish farms in sea lochs

Demands for "emergency" inspections of all salmon farming operations are to be put to the Scottish government later.

Campaigners from consumer group SumOfUs will deliver the 40,000-signature petition to Marine Scotland.

The petition warns of a "surge of deaths" over the summer and cites evidence of serious welfare abuses at some of Scotland's salmon farms.

Salmon producers insist the sector operates to an unparalleled level of transparency.

The petition requests urgent action from Marine Scotland because a rise in sea temperatures over the summer months increases the likelihood of disease among salmon populations.

Anna Liberadzki, a campaigner at SumOfUs, said: "For years, we've known that Scottish salmon cultivation is as horrific as battery farming. Recent footage of the terrible conditions on salmon farms shows that the problem is only getting worse.

"Marine Scotland must step in. The alternative is a summer surge of salmon deaths and disease."

'Infectious diseases'

Marine Scotland carried out an emergency inspection at a fish farm in Loch Shieldaig last month following reports about fish welfare from salmon campaigners.

Scottish Salmon Watch director Don Staniford, who filmed conditions at that farm, said: "We know from the Scottish government's own surveillance that Scotland's salmon farms are riddled with infectious diseases, pathogens and viruses. Unannounced inspections of salmon farms are urgently needed to prevent further mass mortalities and welfare abuse."

Image copyright Outer Hebrides Fisheries Trust Image caption Wild salmon with lice damage, filmed in the Blackwater River, Outer Hebrides

More than 200 fish farms operate in Scotland's sea lochs, producing more than 150,000 tonnes of salmon a year, however, the amount of salmon produced by Scottish farms dropped last year due to attempts to tackle "biological issues" such as sea lice infestations and disease.

Hamish Macdonell, director of strategic engagement for the Scottish Salmon Producers Organisation, said: "The Scottish salmon farming sector operates to a level of transparency that is unparalleled in other food production sectors.

"The sector is supportive of legitimate independent scrutiny, it is what helps businesses and the sector improve and grow.

"The Scottish government's fish health inspectorate has powers to make unannounced visits at any salmon farm. In addition, farms undergo audits and inspections from retailers, UK and international certification schemes, regulators and other stakeholders so there is seldom a week goes by that their operations are not scrutinised."

In June, the Scottish Environment Protection Agency launched a new evidence-based regulatory framework for the sector, which will apply to all new fish farm applications.

A Scottish government spokesperson said: "Fish farmers and veterinary professionals work hard every day to ensure the health and welfare needs of farmed fish are met.

"Marine Scotland's fish health inspectors are responsible for enforcing fish health legislation. They will report any significant case of poor welfare to the veterinarians in the Animal and Plant Health Agency, who are responsible for enforcing welfare legislation and will fully investigate any welfare complaints."

In October, in a response to a parliamentary question, Rural Economy Secretary Fergus Ewing revealed that there had been only two unannounced site inspections of fish farms "in the last year".