Scotland’s salmon farms saw, in October, the worst month ever of monthly mortalities. The most recent figures, published by industry-body Salmon Scotland, show that the deaths, were, at 4.82% of the salmon farmed, the highest percentage they have ever been.

A year after Scotland’s ‘record worst year’, this is another year of worsts. Fish Farm Inspectorate figures show that between January and October 2023, 13.5 million salmon mortalities were reported, compared with 11.5 million during the same period in the previous 'record year' . 

It's in the context that a newsletter by Chris Packham, broadcaster and president of the RSPCA, calling for a moratorium on the expansion of salmon farming, has caused fresh questioning of the future of the industry.

Last week at a parliamentary committee meeting on the Scottish Government’s biodiversity strategy, MSP Monica Lennon questioned Salmon Scotland’s CEO,  Tavish Scott, over the newsletter.

Mr Scott replied: “Mr Packham has been a well-known opponent of our sector and has been for a long time and he’s trotted out his usual arguments. Is mortality an issue? Yes, it is. Are we needing to tackle it in an ever greater way? Yes, we are. Are we determined to do that? Absolutely - and millions of pounds of investment are going into that.“

Following the meeting, Ms Lennon said:  “When the President of the RSPCA raises serious concerns about the salmon farming industry in Scotland, even in a personal capacity, that must be taken seriously by the Scottish Parliament and regulators.

“At the Net Zero Committee, I welcomed the opportunity to raise Chris Packham’s intervention with Salmon Scotland chief executive Tavish Scott during an evidence session on the Scottish Government’s response to the nature emergency.

“With record numbers of dying fish in our seas, there needs to be more transparency and accountability. The sharp rise in on-farm mortalities brings into question the long-term sustainability of the salmon farming industry and its current practices. More scrutiny is needed.”

The rise in these mortalities is possible to see in graphs charting the years since monthly reporting started.

However, the Scottish Government points out that mortality figures alone do not allow for direct comparisons between years  – and that “the survival to harvest of a year class provides a better comparison”. But figures that back this from the Scottish Fish Farm Production Survey, 2021, only go as far as 2019.

Meanwhile, there are other clear signs of an industry in crisis. Many salmon farm companies this year had to slash their harvest volume predictions.

Tavish Scott, speaking at last week's parliamentary committee, observed that “the fundamentals” driving mortalities over the past year “have been warmer seas”.

“We are an evidence and data-based sector. That is the only way we can successfully develop our businesses and that is why we spent so much time working with scientists oceanographers and others to ensure we understand what is happening.”

“But the most fundamental reason is we’ve seen types of organism in the marine environment over the last couple of years which haven’t been seen for a decade or more in our waters. We are working as fish farmers to find ways to manage that and put in the correct mitigations.”

Some insight into what is driving these high mortalities can be gleaned from reports published by the Fish Health Inspectorate and Salmon Scotland. 

Alongside mortality events and their sizes the Fish Health Inspectorate records explanations, but they offer a far from clear picture. "Gill health" problems are the chief reason given, though these are often linked to other explanations, among them Amoebic Gill Disease.

Though the rising plague of microjellyfish and plankton are often blamed, these are mentioned only three times in FHI data. Loss during treatment (chiefly done for lice) is the third most frequent. Lice are mentioned just twice.

'Notes' attached to mortalities in Salmon Scotland's monthly report for October, however, show a more frequent recognition of a jellyfish problem. 

This doesn’t mean that jellyfish and lice, which tend to thrive on fish that are already in poor health, are not contributors to the gill health problems ultimately blamed. Scientists studying one microjellyfish species have found it to be associated with outbreaks of gill disease – and that the range of this organism has expanded in recent years, and is linked to warmer water.

CEO of Bakkafrost, Regin Jacobsen, described to The Herald earlier this year how he believes the jellyfish impact the salmon by stinging and burning their gills as they run through them, and effectively reducing their capacity to breathe.

The Scottish Government, however, continues to support the expansion of the industry and created a new Vision for Sustainable Aquaculture last summer.

Mr Packham, in his letter, which was written for the charity Animal Equality,  joins a long queue of voices calling for such a moratorium.

Many cite a 2018 Scottish Government report which advised that "further development and expansion must be on the basis of a precautionary approach and must be based on resolving the environmental problems" and that "the status quo is not an option".

Numerous groups and individuals have been making these calls over the past few years. The Scottish Green Party included it in its election manifesto. Earlier this year eight members of the Scottish parliament, including Scottish Green party spokesperson Ariane Burgess, signed a letter coordinated by Animal Equality and OneKind calling for any expansion of the industry to be paused.

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Ariane Burgess, the Scottish Green spokesperson for Rural Affairs, said this week: “The Scottish Greens’ election manifesto included a moratorium on new salmon farming, and we still believe that a pause on expansion is necessary, until environmental and welfare impacts are significantly reduced.

“Mortalities amongst farmed fish are getting worse, sea lice are getting worse, the impact on Scotland’s endangered wild salmon is getting worse, as is the impact on other marine wildlife and ecosystems. Yet the industry is still expanding.

In November 2022, after one of the largest in Scottish waters, was approved by Orkney Islands Council, the No East Moclett fish farm group on Papa Westray wrote to Mairi McAllan calling for a moratorium on fish farms based on the recommendations of a Scottish parliamentary committee asking for an improvement in fish farm welfare.

A spokesperson for the group said earlier this week: “We were concerned about the massive increase in fish farming in what is now being called the Westray Production Area.

"Now, instead of looking seriously at a moratorium, the fish farm industry in the pristine waters of the Northern Orkney islands is accelerating its plans to increase production and the size of the fish pens by a significant level.”

The Herald: A worker at a Scottish salmon farmA worker at a Scottish salmon farm

Responding to Chris Packham’s letter last week, Dr Iain Berrill, technical director of Salmon Scotland said: “Chris Packham has a significant platform, so it is disappointing that he has included several misconceptions used by anti-salmon activists in this letter.

“The truth is that Scottish salmon farmers provide the highest welfare standards anywhere in the world for the animals in their care, and are independently certified by RSPCA Assured.

“The stocking density of Scotland’s salmon farms required by RSPCA Assured is a minimum of 98% water when the fish are fully grown – plenty of room for salmon to naturally shoal, as animal experts know.

“While no farmer wants to lose any animal, the care our farmers are able to provide means that survival rates for farm-raised salmon - which spend up to two years in the sea - are significantly higher than their wild cousins, with average monthly survival rates of around 97%.”

A Scottish Government spokesperson said: “Scottish salmon is a high quality premium product, providing healthy animal protein from carbon efficient production.

“Salmon farming in Scotland is a highly regulated industry subject to a number of fish health, environmental and local authority planning controls. The industry is subject to stringent animal health and welfare legislation The vast majority of salmon farms in Scotland are members of the RSPCA assurance scheme and are regularly checked for compliance.

“We recognise an increase in mortality which has largely been associated with earlier climate events and we expect producers to drive mortality to the lowest possible levels. Our recently published Vision for Sustainable Aquaculture sets out our ambitions for the sector, placing an emphasis on addressing the key challenges faced by the sector, including further improving fish health and welfare.”