The U.K. consumer group, Which?, has criticized the growing trend of supermarkets to sell a cheaper, less nutritious alternative to tinned mackerel in what they identify as an example of "skimpflation" — reducing the quality of a product or service without changing its price.

Princes — which supplies major supermarkets — has substituted jack mackerel, an entirely different species, for mackerel, with similar tins also being sold by Lidl. The company says it has made the change to enhance sustainability.

BBC News says the switch was prompted by dwindling stocks of Atlantic mackerel after years of overfishing, with its Chilean counterpart more sustainable and a third of the cost.

The Guardian says that, although the tins are clearly labeled, food experts say jack mackerel is a poor replacement for the oily fish, as it is a different species with a different flavor and different nutritional values. They also argue shoppers may not realize a product has changed until they get it home.

Which?, the largest independent consumer group in the U.K., in March also identified the pricing tactic being used on a string of popular Easter eggs from big-name brands, including Cadbury, Galaxy and Toblerone.

Princes announced in October 2025 that, given recent developments to the status of Northeast Atlantic Mackerel (Scomber Scombrus), the company was taking a “leading position in the market,” changing all of its Princes brand mackerel products to Chilean mackerel (Trachurus murphyi), or Jack mackerel as it’s commonly known.

“This species meets the Marine Stewardship Council’s (MSC) sustainability standards, which considers fish stock health, ecosystem impact, and the effectiveness of fishery management,” the food producer’s statement continued. “The move reinforces Princes’ commitment to certified sustainable wild caught seafood whilst environmental NGOs criticize overfishing of the species across the North Atlantic.”

The BBC says the switch to jack mackerel is happening beyond the U.K. Supermarkets in the Netherlands no longer sell Atlantic mackerel, and at least one supermarket chain in Sweden has switched to jack mackerel.