SCOTLAND’S fish farming industry is worth hundreds of millions of pounds and has been lauded for bringing jobs to coastal communities.
However, the industry has faced criticism over its welfare standards and environmental impacts.
Ferret Fact Service explains the impact of the industry on Scotland, and why it has become a lightning rod for controversy.
How does fish farming work?
FISH farms dot the west coast and north-west coast of Scotland, as well as several islands, with more than 200 facilities in operation. The majority are salmon farms.
Most salmon begin life onshore, where fish are reared in freshwater until they grow to size.
They are then brought to offshore farms where they grow to adult size while kept in netted pens in Scotland’s seas. These pens allow for the constant recycling of seawater. The salmon’s life cycle takes around three years. Once they are fully grown, they are slaughtered and taken to processing plants to be prepared for sale.
How important is the industry to Scotland’s economy?
SCOTLAND’S aquaculture industry consists of both fish farms and shellfish farming.
Salmon farming makes up the majority of the industry, providing 96% of its value in 2021, according to Scottish Government figures. Scotland is the third largest global provider of Atlantic salmon.
Scottish salmon is the UK’s biggest food export, with sales worth £578m in 2022. The industry employs about 2300 people.
Why is salmon farming so controversial?
FISH welfare. Critics of the industry have long argued that the farmed fish are kept in poor conditions, leading to disease and a high number of fish mortalities.
Research has found that the number of mass die-offs of fish has increased, and they are happening at a larger scale in recent years.
They argue that warmer seas and greater reliance on technology are contributing to the rise in deaths.
Scottish Government statistics showed that more than 17 million salmon died in Scotland last year. This was the highest figure recorded.
Some of this mortality is caused by sea lice. Sea lice are a serious issue in salmon farms, causing significant harm to fish. The lice feed on the skin of salmon, and can be lethal to the animals.
The high density of salmon in fish farms makes it very easy for parasites like sea lice to transmit disease between fish.
Salmon are also regularly killed by chemicals used to treat diseases and kill sea lice, as well as rough handling, algal blooms, jellyfish, seals, poor water quality and oxygen shortages.
Animal welfare charities have pointed out that fish are sentient animals that can feel pain, and criticise the conditions in which they have to live, comparing the practice to battery farming.
The salmon farming industry says many fish mortalities are linked to climate change, rather than poor conditions.
Rises in sea temperature have increased algae and brought large numbers of jellyfish, which sting salmons’ eyes, skin and gills, and can result in death.
Phytoplankton algae can reproduce or “bloom” to harmful levels, which can be fatal to farmed fish.
Sustainability
THE salmon farming industry has been considered a more sustainable way to provide fish for consumption because it avoids overfishing of wild species and fish can be reproduced in a controlled way.
The industry body Salmon Scotland argues it is a low-carbon source of protein, compared to meats like chicken, pork and beef.
Environmentalists have suggested claims of sustainability from the industry are not accurate, due to the polluting impacts of farms on the seas, as well as the outbreaks of disease.
A leading Scottish salmon farming company, Loch Duart, was asked to stop branding its business as “sustainable” by the UK’s advertising watchdog after complaints.
Impact on other animals
THERE have been concerns that the sea lice which afflict farmed salmon could risk spreading to wild fish. The Scottish Environmental Protection Agency (Sepa), named 19 fish farms that were at high risk of contaminating wild salmon and trout.
Wild Atlantic salmon were internationally classified as endangered in 2023 after global populations fell by 23% between 2006 and 2020. Lice from fish farms has been identified as one of the causes of the decline, along with invasive species, river barriers, and climate change.
Seals have also come into contact with fish farms in Scotland. Salmon make up a part of the diets of certain seals living in our seas, so they are naturally attracted to fish farms.
Significant numbers of fish are lost each year to seals. It has been reported that 1.4 million fish were lost to seals over a 10-year period.
Fish farms have used various methods to deter seals, including controversial acoustic deterrent devices, which transmit loud sounds into the seawater surrounding farms.
These can have an impact on other marine species including dolphins, porpoises and whales.
