SALMON farm production reports will show a “drastic” dip, campaigners predict.

Official figures on the key sector are expected to be published on Monday, covering activity from 2018.

The Scottish Fish Farm Production Survey includes tonnage produced in the previous 12 months and forecasts for the following year.

While the contents of the latest report have not yet been made public, consumer group SumOfUs says it expects confirmation of a “drastic” decrease in production.

The suggestion follows several reports of mass mortalities at separate sites, related to problems like killer lice, which can also be found in wild populations.

The group is campaigning for tighter controls on the multimillion pound aquaculture sector, citing environmental and welfare concerns.

This summer, more than 43,000 people signed a petition by SumOfUs and Scottish Salmon Watch calling for a new emergency inspection regime.

However, the Scottish Salmon Producers Association says members adhere to stringent quality, welfare and environmental standards.

Anna Liberadzki, campaigner at SumOfUs, said: “Salmon farming corporations aren’t just businesses but custodians of our precious marine environment.

“The priority should be to hold them accountable for their disastrous impacts, rather than give the go ahead to new sites off the islands of Canna and Arran.

“Due to growing evidence of terrible conditions on salmon farms, over 43,000 people have signed a SumOfUs petition urging the Scottish Government to carry out emergency inspections. It’s time they took salmon welfare seriously.”

Don Staniford, director of Scottish Salmon Watch, said: “If the forecast is correct, Scottish salmon farming production in 2018 will be less than 15 years ago.

“Far from being a success story, Scottish salmon farming is a welfare nightmare and a disease disaster.”