The fish farming industry has admitted that it had to throw away up to ten million salmon last year – nearly a quarter of its stock – because of diseases, lice and other problems.

Official figures reveal the tonnages of dead fish disposed of has more than doubled from 10,599 in 2013 to a record high of 22,479 in 2016. Most are transported south to be burnt at an incinerator in Widnes near Warrington in northwest England.

Campaign groups warn that the industry is facing an “environment catastrophe”, is “haemorrhaging cash” and “shames Scotland”. Companies accept that they have been plagued by disease and sea lice, and that businesses have suffered.

Unwanted mortalities at salmon farms have long been a problem but in the last three years they have risen to record levels. There have been successive, significant increases in 2014, 2015 and 2016.

Latest figures for the months up to June 2017 show another another 7700 tonnes of dead salmon, suggesting that the problem is not going away. On 9th October 2017 the BBC reported that “lorry loads” of dead salmon were being transported from Loch Eireasort on the Isle of Lewis after a bacterial infection.

The company suffering the biggest losses was Marine Harvest, headquartered in Norway, whose mortalities leapt threefold to 7609 tonnes between 2013 and 2016. Over the same period, the Scottish Salmon Company, which is registered in the Channel Islands, saw its dead fish more than double to 5873 tonnes.

Critics estimate the total number of dead, discarded salmon last year to have been between 10m and 20m. But the industry says it sustained losses of “between 6 and 10 million fish, depending on their size”.

Scottish Government figures show that in 2016 the total number of smolts – young salmon – put into fish farm production in Scotland was just under 43m. Total salmon production was 162,817 tonnes.

The whole salmon farming business model is broken Lynn Schweisfurth, Scottish Salmon Think-Tank

The Scottish Salmon Think-Tank, a new group of fish farm critics, accused the industry of failing to address “appalling” collateral damage. “Self-regulation is simply not working,” said the group’s Lynn Schweisfurth.

“The whole salmon farming business model is broken and far from sustainable as it claims to be. These worrying figures are the hallmarks of an industry in crisis and it’s our rural communities that will suffer as the problems continue.”

She urged next year’s parliamentary inquiry into fish farming to tackle the industry’s “systemic” problems. “Until they do, lorry loads of dead fish and the broader environmental and welfare issues that beset the industry will continue to shame Scotland.”

Dr Richard Luxmoore, senior nature conservation adviser for the National Trust for Scotland, described the disposal of huge amounts of rotting fish as “stomach churning” and a waste of good food. “It is the sign of an environmental catastrophe,” he said.

“The salmon farming industry has lost the ability to control fish diseases and this results in escalating quantities of toxic chemicals being poured into the sea in an increasingly fruitless attempt to control them. It also inevitably leads to the release of an infectious soup of disease organisms into our coastal waters.”

He called for the industry to shift to a “closed containment system” that would protect the fish and the marine environment. The same demand was made by the wild fish campaign group, Salmon and Trout Conservation Scotland.

“Disease and mortalities on Scottish salmon farms continue at shocking levels,” said the group’s Guy Linley-Adams. “What concerns us is that the Scottish Government has almost no idea what the effects are on wild salmon and wild sea trout in Scottish sea lochs.”

Don Staniford from the Global Alliance Against Industrial Aquaculture warned that plans to double the salmon farming business by 2030 were “environmental lunacy”. “Infectious diseases and lice infestation are crippling the Scottish salmon farming industry which is haemorrhaging cash,” he claimed.

Last year saw some problems which resulted in the loss of between 6 and 10 million fish, depending on their size Scott Landsburgh, Scottish Salmon Producers' Organisation

The Scottish Salmon Producers’ Organisation (SSPO), which represents the industry, said there had “unfortunately” been losses. “Last year saw some problems which resulted in the loss of between 6 and 10 million fish, depending on their size,” said SSPO chief executive, Scott Landsburgh.

“This is something which the industry takes very seriously and is working hard to minimise. Disposal of mortalities is managed in line with the government’s approved methods and legislation.”

Marine Harvest insisted it had been “very transparent” about the issues it had been facing with sea lice and amoebic gill disease (AGD). “We would clearly prefer if we had not had this level of mortalities,” said the company’s business support manager, Steve Bracken.

“But what is more positive is that the picture is changing. We are making strong progress in reducing the sea lice levels and tackling the challenge of AGD.”

The Scottish Salmon Company agreed it had “biological challenges and unprecedented mortalities” in 2016. “We have taken decisive action to tackle these challenges,” said a company spokesperson.

The Scottish Government pointed out that fish and shellfish farming contributes £620m to the Scottish economy every year, supporting more than 12,000 jobs. “We have a duty to protect Scotland’s marine environment and the health and welfare of farmed fish is of utmost importance,” said a spokesperson.

“The Scottish Government is committed to working with the aquaculture sector to develop a strategic health framework that ensures we make progress in tackling major problems, including emerging disease and sea lice.”

Dead salmon thrown away

fish farm companytonnes in 2013tonnes in 2016
Totals10,59922,479
Marine Harvest2,2247,609
Scottish Salmon Company2,4365,873
Wester Ross863,142
Kames512,854
Scottish Sea Farms1,8971,678
Grieg0611
Dawnfresh122200
Loch Duart58133
Others3,202479
source: aquaculture.scotland.gov.uk

2016 salmon farming in numbers

162,817 tonnes production
3,903 tonnes organic production
43m young salmon
10m mortalities
311,496 fish escaped
253 fish farm sites
10 companies
1,486 staff
£1.8bn business
£3.6bn target business for 2030

source: Scottish Shellfish Farm Production Survey 2016, Marine Scotland Science

A version of this story was published in the Sunday Herald on 8 October 2017.