One opened tin of beautiful mackerel fillets on toast

Britain’s Mackerel Aisle Has a Fish Problem

September 13, 2026

The Pantry Pulse, 1 October 2026.

Two tins of “mackerel” in a British supermarket can now hold fish from different genera, caught in different oceans, with different nutrition panels. One is Atlantic mackerel, Scomber scombrus. The other is Chilean jack mackerel, Trachurus murphyi.

Grocery Gazette reported on 11 September that retailers including Tesco and Sainsbury's have begun selling tinned jack mackerel as Northeast Atlantic mackerel biomass has dropped below a critical threshold. Princes announced on 30 October 2025 that it would move all of its Princes-brand mackerel products to MSC-certified Chilean jack mackerel, with Northeast Atlantic mackerel yet to regain MSC certification.

The Princes tins are labeled jack mackerel, so nothing is mislabeled. Grocery Gazette's question is whether shoppers clearly understand the distinction between the species.

Start With the Species

The UK government's commercial fish list separates them cleanly.

Mackerel refers to fish in the genus Scomber.

Horse mackerel, jack mackerel and scad refer to species in Trachurus and Decapterus.

Jack mackerel has a large fishery of its own: Chile's industrial purse-seine fishery reported a catch of 819,720 tonnes in 2024 and has been MSC certified since April 2019. Princes chose it as a certified sustainable source while Northeast Atlantic mackerel remained uncertified.

Changing the species changes the product. According to Grocery Gazette, Princes describes its jack mackerel as having a milder flavour and meatier texture. The omega-3 figures on the labels differ too.

Two Tins, Different Math

The Sainsbury's listing for Princes Jack Mackerel Fillets in Sunflower Oil gives 0.9 grams of omega-3 per 100 grams.

The Tesco listing for Tesco Mackerel in Rapeseed Oil gives 2,990 milligrams of omega-3 per 100 grams of drained fish.

Only the Tesco label says its figure is for drained fish, so the two panels may not share a basis. They also describe two specific tins, not every Atlantic mackerel against every jack mackerel. Still, 0.9 grams against 2.99 grams is not a rounding error.

Why Britain Started Changing Fish

The problem begins in the Northeast Atlantic, where fisheries in eight countries, among them Norway, Iceland, the Faroe Islands and the UK, fish the same mackerel. Managing it requires those countries to agree on how much should be caught and how the catch is divided. They have not reached a lasting agreement.

The Marine Stewardship Council suspended certification for all Northeast Atlantic mackerel fisheries in March 2019. The stock had fallen below 2.75 million tonnes, the point at which action is considered necessary, and catches were running far above scientific advice. The certificates have not been reinstated amid continuing disputes over how the catch is shared. Princes said when it announced its sourcing change that coastal states had failed to make enough progress toward quotas aligned with scientific advice and a long-term management plan.

From a sourcing desk, the logic is easy to follow. One fishery had certification. The other did not.

From the grocery aisle, the result is stranger. A fish with a different flavour and a different omega-3 line on its label now sits where Atlantic mackerel sat in a shopper's mental pantry.

The Name Is Doing Too Much Work

Commodity food likes broad categories. Tuna. Sardines. Mackerel. Those words make shopping easy, and they say nothing about the species.

Spend time with conservas and the species starts to matter. So do where the fish was caught, who packed it and the oil around it.

The complete tinned fish guide covers the wider category. Within mackerel alone, the range is wide.

Ramón Peña's Mackerel in Olive Oil (shop Ramón Peña Mackerel in Olive Oil) comes from Galicia as boneless, skinless fillets, grilled and then packed by hand in olive oil with a little salt, a plain style for toast with mustard or a bowl of rice with pickled vegetables. José Gourmet's Mackerel Fillets in Curry (shop José Gourmet Mackerel Fillets in Curry) puts the fish in a thick yellow curry. José Gourmet makes its mackerel pâté (shop José Gourmet Mackerel Pâté) from fresh blue mackerel, and says so.

Jack Mackerel Isn't the Problem

Chilean jack mackerel does not need to apologize for not being Atlantic mackerel. If you like it, buy it, knowing what it is.

The useful habit takes about five seconds. Turn the tin around and find the species, then the origin and producer, and the nutrition panel if omega-3 is part of why you're buying mackerel.

Scomber scombrus, Scomber colias, Trachurus murphyi. Those names say more than the big word on the front.

Disclosure: This article links to product pages for the Ramón Peña and José Gourmet tins named above.