Wild Atlantic salmon, once a plentiful species, is now classified as endangered in Britain, with numbers declining by approximately 70% since the 1980s. This decline is attributed to a combination of river pollution, habitat destruction, and climate change, according to the Atlantic Salmon Trust charity.
While salmon remains the most popular fish in Britain, largely consumed in its farmed form, concerns are mounting over the environmental and ethical impacts of open-net fish farming. These farms, common along the coasts of Scotland and Norway, involve large underwater enclosures that critics argue create detrimental conditions.
Environmentalists point to issues such as overcrowding, the accumulation of waste that can smother marine habitats, and the proliferation of sea lice. Sea lice, a type of parasite, thrive in these crowded conditions and can inflict severe damage on farmed fish, and also pose a threat to wild salmon smolts passing through or near the farms. To combat these parasites and diseases, noxious chemicals, including formalin, are reportedly used in the pens. This has led to investigations into some organic salmon companies for illicit use of such chemicals.
The escape of farmed fish is another significant concern. When farmed salmon escape, they can spread diseases to wild populations and interbreed, potentially weakening the genetic resilience of wild stocks. In one instance last year, approximately 75,000 fish escaped from a farm operated by Mowi, a major supplier of farmed salmon in the UK.
Furthermore, the production of farmed salmon is resource-intensive. It is estimated that it takes about 1.5 pounds of feed to produce one pound of salmon. This feed often includes smaller wild fish, which can deplete stocks crucial for other ecosystems and for consumption in lower-income countries. The high mortality rates in farmed salmon, which have quadrupled in Scotland between 2002 and 2019, add to the sustainability questions.
In response to these issues, a growing number of chefs and restaurants are opting out of serving farmed salmon. Campaigns like 'Off The Table' aim to remove farmed salmon from menus entirely, with establishments such as Angela Hartnett's Murano group and The Pig hotels joining the initiative.
As an alternative, investment is increasing in land-based fish farms, where salmon are raised in enclosed onshore tanks. Proponents argue these facilities offer complete separation from wild fish, mitigating risks associated with sea lice and escapes. However, some critics suggest that while this may reduce direct impacts on wild salmon, it does not address the broader environmental footprint of the industry. Concerns also persist regarding the welfare of fish raised in tanks for their entire lives.
The debate over farmed salmon continues, with calls for stricter regulation, greater transparency, and a revival of wild salmon populations before many consumers and industry professionals will consider it a sustainable choice.