The Tinned Mackerel Swap: What 'Skimpflation' Really Costs Your Weekly Shop

If you have reached for a tin of mackerel recently and noticed something slightly different about the taste, the texture, or even the small print on the label, you are not imagining things. Across UK supermarket shelves, a quieter kind of change has been taking place. The familiar Atlantic mackerel that has filled British store cupboards for decades is being replaced by a cheaper species from the other side of the world, and consumer campaigners are not impressed.

The consumer group Which? has described the switch as an example of "skimpflation", a term that has crept into the household budgeting vocabulary alongside shrinkflation. Where shrinkflation shrinks the size of a product while holding the price steady, skimpflation quietly downgrades what is actually inside. According to reporting on the change, the fish now appearing in many tins is jack mackerel, a different species entirely, and one that costs a fraction of the real thing at wholesale.

For anyone trying to keep a grip on the weekly food bill, this matters. Tinned fish has long been a reliable, affordable source of protein and healthy fats. If the nutritional value is dropping while the price stays the same, shoppers are getting less for their money without necessarily realising it.

What Exactly Has Changed

The company at the centre of the story is Princes, a major supplier to British supermarkets. It announced in October last year that it would move all of its tinned mackerel products over to jack mackerel. Lidl has followed a similar path, selling jack mackerel under its own house brand. Both companies point to sustainability as the driving factor, and there is genuine substance to that argument, which we will come to shortly.

The catch, quite literally, is that jack mackerel is not really mackerel at all. Despite the name, it belongs to a completely different fish family. Traditional mackerel sits in the Scombridae family, while jack mackerel is a member of the Carangidae family, which also includes fish sold as scad, trevally and horse mackerel. The two are not close relatives, and the difference shows up on the plate as well as on the nutrition label.

That nutritional gap is the part budget-conscious shoppers should pay attention to. Jack mackerel contains roughly half the omega-3 of traditional mackerel and around a third of the vitamin B12. For a food many people buy specifically for its health credentials, that is a meaningful reduction.

Sue Davies, head of food policy at Which?, put the concern plainly, warning that shoppers can end up paying the same price for a product that delivers significantly less nutritional quality when manufacturers quietly downgrade everyday staples. Her broader point was about transparency. Manufacturers face real supply pressures, she acknowledged, but they still have a responsibility to be upfront when a recipe changes.

The Labelling Question

Here is where the story becomes genuinely interesting from a consumer protection angle. Until December 2025, UK law did not even allow Carangidae species to be marketed as "jack mackerel". They could be sold as "jack", "scad", "trevally" or "horse mackerel", but the word mackerel on its own was reserved for the real thing.

That changed shortly after Princes launched its new product. The Department for Environment, Food and Rural Affairs amended the rules to permit the "jack mackerel" labelling. The timing has raised eyebrows, and it is easy to see why. A product name that would have been non-compliant one month became perfectly legal the next, allowing a cheaper fish to carry a name that sounds reassuringly close to the premium original.

Princes maintains that its jack mackerel products are clearly identified and were introduced only after extensive product and consumer testing. The firm describes the fish as having a milder flavour and a meatier texture. Lidl GB has said it is committed to sourcing fish and seafood from responsibly managed fisheries. Yet some shoppers have still complained about differences in taste and texture, and about how obvious the substitution really is when you are scanning shelves in a hurry.

The Scottish Pelagic Fishermen's Association has flagged the potential for confusion, arguing that consumers should be able to clearly understand what they are buying. This is a recurring theme in UK consumer protection, and it echoes debates in other areas of household spending where the headline looks familiar but the underlying value has shifted. It is the same principle that applies when you look under the bonnet of any purchase, whether that is groceries or the running costs that quietly eat into a car budget. The label tells one story, and the real cost sometimes tells another.

Why the Switch Is Happening

It would be unfair to paint this purely as a cost-cutting exercise, because the sustainability crisis behind it is real and serious. Atlantic mackerel stocks in the north-east Atlantic have been in steep decline, and the numbers are sobering.

According to the International Council for the Exploration of the Sea, stocks have fallen by roughly three-quarters over the past decade. The Marine Stewardship Council reports that catches have exceeded scientifically advised levels by an average of 39 per cent over the past 15 years. Last year, the Marine Conservation Society described the Atlantic mackerel population as being at breaking point.

The root of the problem is a long-running failure to agree how the fish should be shared. The so-called "mackerel war" has pitted the UK, Iceland, Greenland, Norway, the Faroe Islands, the EU and Russia against one another over quotas for years. Without a unified system, each party has tended to set its own limits, and the collective result has been overfishing well beyond what the science recommends. For 2026, scientists have advised cutting the north-east Atlantic mackerel catch by around 70 per cent to give the stock a chance to recover.

The consequences have already reached the shops. Atlantic mackerel has lost its MSC certification, which means it no longer meets many retailers' sustainability policies. Jack mackerel from Chilean waters, by contrast, is MSC-certified. That certification gap explains a great deal about why supermarkets have been willing to make the switch. In February, Waitrose went further than most, suspending sales of fresh, chilled and frozen mackerel entirely and planning to phase out tinned products as existing stock sold through. The Marine Conservation Society welcomed the move as leading and decisive.

The Environmental Counter-Argument

Sustainability, though, is not a simple one-way case. Hannah Fennell, chief executive designate of the Scottish Pelagic Fishermen's Association, has pushed back on the idea that switching species is straightforwardly greener. She argues that moving away from north-east Atlantic mackerel unfairly punishes the UK industry while sourcing a less omega-3-rich fish from the other side of the world carries a significantly higher carbon footprint for the UK market.

That tension sits at the heart of the debate. On one hand, buying a certified, more abundant species eases pressure on a collapsing stock. On the other, shipping fish halfway around the globe to replace a local product raises its own environmental questions, and it does nothing to support British fishing communities already squeezed by quota disputes. There is no tidy answer here, and shoppers are effectively being asked to weigh competing goods without always having the full picture in front of them.

What This Means for Your Budget

For the everyday shopper, the practical lesson is about attention rather than alarm. Skimpflation works precisely because it is easy to miss. You may not notice a product has changed until you have carried it home and opened the tin. As further reporting on the warning highlights, that delay between purchase and discovery is what makes the practice feel so underhand to consumers.

A few habits can help you keep control of what you are actually buying:

• Read the species name on the tin, not just the front-of-pack branding. "Jack mackerel" and "mackerel" are not the same product.
• Compare nutritional panels if omega-3 or B12 content is the reason you buy the product in the first place.
• Watch the price per 100 grams rather than the headline price, so you can judge whether the value has genuinely shifted.
• Consider alternatives such as tinned sardines or pilchards if you want oily fish with a strong nutritional profile.

Being alert to hidden changes in value is a skill that extends well beyond the tinned fish aisle. The same instinct applies to understanding how broader economic forces move prices, from the cost of your groceries to the way government borrowing through gilts feeds into interest rates and household finances. Small awareness in one area tends to sharpen judgement across the board.

It is worth remembering that manufacturers are not necessarily acting in bad faith. The collapse of Atlantic mackerel stocks is a genuine crisis, and doing nothing was never a realistic option. The frustration voiced by Which? and others is chiefly about how the change has been communicated rather than the change itself.

The tinned mackerel story is a small window onto a larger truth about modern shopping. Prices on the shelf are only half the equation. What sits inside the packaging, and how honestly it is described, is the other half. Keeping an eye on both is how you make sure your money is buying what you think it is.