Salmon farm deaths nearly twice numbers frequently quoted

In terms of weight, SEPA’s figures for the period covered by the analysis totalled 156 million kg, which is 1.9 times as much as the Fish Health Inspectorate (FHI)  totals of 83 million kg.

For 2022, 11.5 million fish deaths were reported to FHI, but the analysis calculated a figure of 17.5 million from SEPA weights.

John Aitchison of Coastal Communities Network Scotland said:  "That is 6 million missing dead fish in 2022 which are frequently missed from the graphs and data that the public often assumes covers all deaths.”

“It’s unacceptable,” he said. “High mortalities are a sign of poor farmed animal welfare. Why is the government not enforcing its own animal welfare law? It seems not even to know the extent of the problem, or how it is worsening over time.”

He observed: “Many coastal communities “are feeling the salmon farming industry pushing hard to expand. The government is so keen to enable the expansion that it seems to be looking the other way. You can’t have 17 million animals die in a year and claim that the process that is doing that is humane. And that’s only in the sea. The freshwater mortalities are in addition to that and we reckon you would find the same type of under-recording of mortalities in the freshwater stage of salmon farming too.”

There are three official government sources of mortality information - all of which use different metrics and have different reporting criteria. These are the Fish Health Inspectorate data, SEPA data on Scotland’s Aquaculture website and the Scottish Government’s Fish Farm Production Survey.

Most often the figure that reporters like myself publish is the FHI data. However, the closest to an accurate picture of that data is the mortalities figures published by SEPA on Scotland’s Aquaculture website - which only lists mortalities by weight. The total weight of mortalities published there  is dramatically more than that listed by FHI.

SEPA only yesterday published their figures for the final quarter of 2023 and these were not included in the analysis. However, what they reveal is that last year, 2023, SEPA recorded  30.68m kg of mortalities compared with 24.88m kg by the FHI, a 23% difference..

The following bar graphs, based on the analysis, are a snapshot of the data from early last week. 

There is a reason why some deaths are missing from FHI reports – and that, essentially, is that it’s not their job to monitor mortality.

Mr Aitchison said: “The FHI has a very specific function, which is just to look for notifiable diseases but not to ensure general farmed fish welfare. It’s interested in mass mortality chiefly in case there’s a disease coming through that it needs to know about. So it sets quite a high threshold below which the farms don’t have to report deaths. ”

That threshold means that on marine farms, depending on size, either 1% or 1.5% of fish per week may die without being reported. If the farm is of a significant size and the deaths happen over a long period of weeks this can be a significant figure.

"Farms also,” Mr Aitchison said, “don’t have to report deaths for the first six weeks after the fish are put into the sea – which is when a lot of them die, but not from disease. So they are excluding those because it is not part of their remit.”

Those absences are illustrated by the fact that data on the Scotland’s Aquaculture website shows that the Tarbert South farm (Loch Fyne) reported 26.8t of mortalities while having 61t of biomass on site in August 2023 – but there are no matching entries in the FHI mortality spreadsheet. 

“There’s a big discrepancy," said Aitchison, "between the FHI information, with all its exclusions, and the much larger weight of dead fish which is in the SEPA data. The total is getting on for twice as heavy in the SEPA information. That made me think, ‘There’s something funny going on here. How can it be so much more in kg than FHI?’”

Data, yet to be crunched, on the freshwater stage of salmon farming, suggests a similar pattern of what Aitchison calls “under-recording of mortalities”.

A Scottish Government spokesperson said: “Data relating to mortalities by SEPA and the Scottish Government’s Fish Health Inspectorate (FHI) are collected for different purposes, using different measures so it is inappropriate to seek to compare these directly.

The third source of government information on fish farms is the Scottish Government’s Fish Farm Production Survey. However, it gives no indication of overall death numbers, and provides information instead on the survival rate of “total % of year class harvested”.

This survival rate has gone up and down since reporting started, and was at its lowest in 2007, at 71.8% and highest in 2012, at 85%. However, these statistics are not yet available for the past two years of record-breaking mortalities, 2022 and 2023 (the latest figure being 75.9% in 2020).

Mr Aitchison urged action to address the problem. "In 2018 the Scottish Parliament had an inquiry into salmon farming and the conclusion of the parliamentary committee was that urgent and meaningful action must be taken before the industry could expand further, on amongst other things, fish health. We are now 2024, six years on. In that interim period the industry has been given consent by more than 50,000 tonnes of extra salmon production (farming well over 10 million extra fish).

"The mortality figures are enormous and growing worse. They haven’t dealt with the fish health problem but they’ve been allowed to expand anyway.”

READ MORE: Scottish salmon: What dead fish I saw tells us about sector

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A further source of data on salmon mortalities is that produced by the industry body, Salmon Scotland. The figures they publish are in the form of monthly percentage mortalities, but their website also gives a now out-of-date figure for annual compound mortality of 14.5%.

Over the past few years the annual compound figure has risen significantly from around 13% when Salmon Scotland started reporting these figures in 2018 (see graph) to close to 24% in 2022 and last year almost  25%.

These figures also show Scotland's salmon farms are performing poorly in a global context. They are dramatically more than the 16.7% which was described last week as unacceptable when the Norwegian Veterinary Institute published their report on 2023 mortalities.

Norway produces over half the world’s farmed salmon (Scotland is third largest producer in the world). Last year it saw 62.8 million salmon dead in the sea phase of production. But as a percentage of fish farmed, Scotland’s deaths are more.

There are calls for action in Norway. In response to that veterinary report, the CEO of the Norwegian Seafood Association, Sjømatbedriftene stated that mortalities should be halved by 2030. Calls have also been made by Norwegian trade union, Tekna, representing natural scientists and technologists, including fish health professionals, for the country’s salmon farming industry to be given a requirement of a maximum of 5% mortality within five years

Such a target does not exist in Scotland (though there have been calls for a moratorium on expansion of the industry). Rather, the Scottish government continues with plans to expand the industry – chiefly on grounds that it is one of Scotland’s biggest exports and creates rural jobs.

A Scottish government spokesperson said: “Our Vision for Sustainable Aquaculture recognises the importance of high standards of fish health and welfare and we expect producers in Scotland to drive mortality to the lowest possible levels. We are working closely with the sector, regulators, innovation centres and fish vets to support a reduction in mortality where possible.”

Dr Iain Berrill, head of technical at Salmon Scotland, said: “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.

“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 two years in the sea – are significantly higher than their wild cousins, with average monthly survival rates of around 97 per cent.

“Scottish salmon is an eco-friendly food with the lowest carbon footprint of all major animal proteins and one of the most nutritious foods you can put on your plate. With more than 850 million healthy, nutritious meals every year, Scottish salmon is the UK’s biggest food export - and salmon is the country’s most popular fish – and consumer demand for Scottish salmon continues to grow.”