Several major UK supermarkets, including Sainsbury's, Tesco, and Lidl, are facing criticism for selling tinned fish labeled as mackerel that is, in fact, Chilean jack mackerel. An investigation found that these products no longer contain true mackerel, a species rich in omega-3 fatty acids crucial for brain and heart health. Instead, consumers are purchasing a different fish from the Carangidae family, rather than the Scombridae family of true mackerel. This substitution means consumers are receiving significantly less omega-3, with some products containing only half the amount found in traditional mackerel.
Princes, a major tinned fish producer, switched its mackerel range to Chilean jack mackerel last year. Despite the nutritional differences and a lower cost—Chilean jack mackerel is approximately a third cheaper—these products are often sold at prices comparable to traditional mackerel. For example, the price difference at Tesco is reportedly as little as 20 pence.
Sue Davies, head of food policy at Which?, expressed concern over the practice, stating, "It's a real concern when manufacturers quietly downgrade everyday staples like these as shoppers can end up paying the same price for a product that delivers significantly less nutritional value." Omega-3 fatty acids are vital for cognitive function, supporting blood vessel health, and potentially protecting against dementia. True mackerel is a particularly rich source of these essential fats, often exceeding the levels found in salmon and sardines.
The shift towards Chilean jack mackerel appears to be driven partly by sustainability concerns. Waitrose, for instance, halted sales of true mackerel earlier this year due to overfishing issues in certain regions. Chilean jack mackerel, however, holds sustainability certifications, unlike the true mackerel fishery in the North East Atlantic, which has exceeded scientific catch limits for over 15 years and lost its Marine Stewardship Council certification.
Retailers are selling Chilean jack mackerel under signs that broadly state 'mackerel', conflating the two distinct fish. Lidl has been transitioning to the Chilean variety, selling it under generic 'mackerel in olive oil' labels. Consumers have begun to notice changes in taste and texture, with some describing a metallic or less oily quality.
Historically, Chilean jack mackerel was not permitted to be labeled as 'jack mackerel.' However, rule changes by the Department for Environment, Food and Rural Affairs shortly after Princes introduced its new tins have allowed for this labeling, which critics argue blurs the distinction and misleads consumers. Stewart Harper, former managing director of North Atlantic Fishing Company, told the Financial Times that "Consumers will be suffering because pure mackerel is a much better species to eat than jack mackerel."