Tins of mackerel sold in many of the UK’s major supermarkets no longer contain the true mackerel fish, according to recent reports. This change has been made due to concerns over overfishing, which has led to a decline in the true mackerel population. Instead, suppliers like Princes have switched to a different type of fish called Chilean jack mackerel, which, despite its similar name, is not the same species. Chilean jack mackerel has fewer calories and less omega-3 compared to true mackerel, and some consumers have reported issues such as larger bones and a metallic smell in the product. Major supermarkets like Tesco and Sainsbury’s sell Princes tinned fish, while others like Lidl and Waitrose have been moving away from fresh true mackerel. Waitrose, for example, cited overfishing concerns in April and has begun phasing out its canned mackerel products, selling only existing stock. This shift follows a broader trend across Europe, which has been marked by disputes known as the “mackerel wars.” These conflicts involve countries such as the UK, Norway, the EU, Russia, Iceland, Greenland, and the Faroe Islands, all competing for mackerel fishing rights. According to the International Council for the Exploration of the Sea (Ices), mackerel stocks in the north-east Atlantic have dropped by three-quarters in the past decade. Scientists have warned that fishing should be reduced by over 70 per cent to prevent the collapse of these fish stocks. However, since 2010, mackerel quotas have been set higher than recommended by scientists, averaging 39 per cent above the advised levels. Conservationists have expressed concern that while some management measures are in place, enforcement of these rules remains weak. Chilean jack mackerel, also known as the Peruvian jack mackerel, belongs to the Carangidae family and is found in the waters of South America. Stewart Harper, former managing director of North Atlantic Fishing Company, expressed disappointment that consumers are now eating imported fish instead of locally caught mackerel, calling pure mackerel a superior choice. Industry data suggests that wholesale Chilean jack mackerel costs about one-third of the price of Atlantic mackerel, yet some supermarkets sell both types for similar prices. The Financial Times reports that some retailers, such as Lidl, have been labeling jack mackerel products as “mackerel” despite the difference in species. In response, Lidl GB stated it is “committed to sourcing fish and seafood from responsibly managed fisheries.” The company also said it would review whether north-east Atlantic mackerel continues to meet its sourcing policies and scientific guidelines before its next purchasing window for smoked mackerel. This highlights the ongoing debate between cost, consumer expectations, and the need for sustainable fishing practices.