A growing trend of supermarkets replacing tinned Atlantic mackerel with jack mackerel—a substantially different species—represents "skimpflation" in action, according to consumer advocates. Princes, a major supplier to UK supermarkets, has switched its entire tinned mackerel range to jack mackerel, a move now being replicated by Lidl and other retailers facing mounting sustainability pressures.
The substitution stems from severe depletion of Atlantic mackerel stocks in the north-east Atlantic, driven by decades of overfishing and international quota disputes. Jack mackerel, sourced from Chilean waters, costs roughly one-third as much as Atlantic mackerel and carries Marine Stewardship Council certification, making it an attractive alternative for retailers navigating both cost and environmental concerns. However, the nutritional trade-off is significant: jack mackerel contains approximately half the omega-3 and around one-third the vitamin B12 of traditional mackerel.
Sue Davies, head of food policy at Which?, expressed alarm at the quiet nature of these product changes.
"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 quality,"she said.
"Skimpflation - quietly changing ingredients to cut costs - has become increasingly common, but it can feel particularly sneaky as shoppers may not realise a product has changed until they get it home and eat it."
Some consumers have complained about differences in taste and texture, alongside concerns about labelling clarity. Princes announced in October 2025 that it was converting all tinned mackerel products to jack mackerel, describing the species as having a "milder flavour and meatier texture" and stating its products were "clearly identified". Lidl is selling jack mackerel under its house brand and said it was "committed to sourcing fish and seafood from responsibly managed fisheries".
Why Atlantic mackerel stocks have collapsed
Atlantic mackerel populations have faced catastrophic decline over the past fifteen years, with catches in the north-east Atlantic exceeding scientific advice by an average of 39% annually. According to the International Council for the Exploration of the Sea (Ices), stocks have plummeted by roughly three-quarters over the past decade. The Marine Stewardship Council suspended North East Atlantic mackerel certification in 2019 because of overfishing and quota-sharing failures, making this a long-running supply issue rather than a sudden crisis.
The collapse reflects a long-running international dispute known as the "mackerel war", in which the UK, Iceland, Greenland, Norway, the Faroe Islands, the EU and Russia have repeatedly failed to agree on unified catch quotas and management systems. In December 2025, the UK, Norway, the Faroe Islands and Iceland agreed a 2026 catch limit of 299,010 tonnes, still far above scientific advice and without the EU in the deal. Ices has advised slashing north-east Atlantic mackerel catches in 2026 by roughly 70% to allow stock recovery. The European Commission later warned that the 2026 arrangement could push overall fishing pressure on the stock beyond 400,000 tonnes.
What is jack mackerel and why the confusion?
Despite its name, jack mackerel is not a type of mackerel at all. Jack mackerel belongs to the Carangidae fish family, while traditional mackerel belongs to the Scombridae family. Until December 2025, UK law restricted Carangidae species to labelling as "jack", "scad", "trevally" or "horse mackerel". Shortly after Princes launched its product as "jack mackerel", the Department for Environment, Food and Rural Affairs changed its rules to permit this labelling, a decision that has raised concerns about consumer clarity.
The Scottish Pelagic Fishermen's Association flagged the potential for confusion, with CEO designate Hannah Fennell arguing that
"consumers should be able to clearly understand what they are buying"and warning that
"if retailers move away from Northeast Atlantic mackerel, they are unfairly punishing the UK industry while instead sourcing a different, less omega-3-rich species from the other side of the world with a significantly higher carbon footprint to the UK market."
How are retailers responding?
In February 2026, Waitrose became the first UK supermarket to suspend sales of fresh, chilled and frozen mackerel due to overfishing concerns, with tinned mackerel to follow once stock runs out, and it is promoting herring, sardines and sea bass instead. The Marine Conservation Society heralded the move as "leading and decisive". The shift to jack mackerel is being felt beyond the UK, with supermarkets in the Netherlands no longer selling Atlantic mackerel and at least one supermarket in Sweden switching to jack mackerel.
Davies from Which? emphasised that while manufacturers face genuine supply chain pressures and sustainability challenges, they have a responsibility to be transparent.
"They have a responsibility to shoppers to be completely upfront when they change a product's recipe."
What happens next?
Waitrose's fresh, chilled and frozen mackerel sales will be suspended by 29 April 2026, with tinned mackerel following after current stock sells through. Princes told readers it would consider sourcing north-east Atlantic mackerel again if sustainable management is restored and MSC certification is regained. Lidl said it will review its smoked mackerel sourcing before its next purchasing window.
Key Facts:
- Jack mackerel contains approximately half the omega-3 and one-third the vitamin B12 of Atlantic mackerel
- Atlantic mackerel stocks have fallen by roughly 75% over the past decade due to overfishing and international quota disputes
- The Marine Stewardship Council suspended Atlantic mackerel certification in 2019, while Chilean jack mackerel is MSC-certified
- Ices has recommended a 70% cut in 2026 Atlantic mackerel catches, but international agreements have set quotas well above scientific advice
- The switch to jack mackerel is occurring across multiple countries including the UK, Netherlands and Sweden
