The Scottish salmon farming industry is under fire following an investigation that showed companies have possibly been misreporting on chemical use.
Farmed salmon are treated with chemicals to ward off disease and infestations such as sea lice but there are limits on how much they can use.
However, the BBC’s Panorama team has learned that Mowi, the world's biggest salmon farming company, is one of a number of firms currently under investigation by the Scottish Environment Protection Agency (SEPA).
Mowi denied any wrongdoing and said it used medications sparingly.
BBC’s Panorama, which aired on Monday night, raised concerns that the chemicals, as well as faeces and food waste coming from the thousands of salmon in the fish farm nets, could be damaging the environment in some of Scotland's lochs.
SEPA is increasing its inspections and taking a tougher approach following criticism of how salmon farming is regulated. It will publish new guidelines on salmon farming in the next two weeks.
Terry A’Hearn the chief executive of SEPA said: “If companies do the right thing, then they have nothing to worry about. If companies do the wrong thing, we’re there to find that out and make sure they improve their game. If that’s going to take tough action, you can be assured we’ll take it.”
SEPA recently completed “one of the largest and most comprehensive marine research projects into aquaculture”. The findings increased “the now substantial weight of scientific evidence that the existing approaches do not adequately protect marine life”, said SEPA at the time.
The agency released proposals for a new, stricter regime, including tighter standards for the organic waste deposited by fish farms and more powerful modelling to assess and understand the risks presented by aquaculture to the local environment. A new enforcement unit will also be created, whilst operators will have to invest in more accurate monitoring, including of waste coming from fish farms.
However, campaigners have raised concerns that industry plans to double in size by 2030 could cause too much damage. The Scottish salmon farming sector has rapidly increased, with more than 200 fish farms now operating in the country, producing more than 150,000 tonnes of salmon a year.
“Every year about 9.5 million fish die in the salmon farms, about 20% of the total,” the BBC reported. “Disease, parasites and even chemicals designed to treat them can all prove fatal.”
The Scottish Salmon Producers Organisation said its members remain committed to good environmental performance. It is in everyone’s interest to maintain a high-quality environment in which fish are raised. The sector is committed to quickly addressing issues where they do occasionally arise and in 2017 had an average compliance of 81%, SSPO said.