This article is republished from The Conversation under a Creative Commons license.
Cod sold in some European supermarkets is being mislabeled and is actually fished far from its claimed origin, according to our new study. We sampled cod sold in Germany, Spain, France and the UK and found that about 30% of it originated in a different location.
Seafood mislabeling, in which one species is sold as another, is a common problem. It may happen by mistake or by deliberate fraud, in which case, there is at least hope for improvement, as various DNA methods are now available for testing species.
But our new research highlights another problem: the mislabeling of geographical origin. As with species mislabeling, this issue can affect the sustainable management of fisheries, the conservation of fish in the wild and consumer trust.
Within a single species, some fish stocks can be severely depleted while others are sustainably harvested. Our findings suggest that mislabeling of geographical origin is commonplace. This means consumers could be unknowingly buying seafood from overfished stocks, or from regions where illegal, unreported or unregulated fishing is common, along with human rights abuses.
Atlantic cod is a useful subject for an investigation into the origins of fish people buy. This species is widely distributed and organized into several regional populations across the north Atlantic that all vary in their conservation status.
The north-east Arctic cod stock is large, relatively stable and well managed. The North Sea cod stock, meanwhile, is depleted and overfished. This discrepancy between two commercially important fish stocks in Europe highlights the importance of accurate labeling. Yet, until now, there had been no investigation into the extent of geographical mislabeling among European retailers.
We sampled 108 Atlantic cod products and compared the reported catch location for 31 of them with their geographical origin, which we determined using DNA analysis.
Less than 2% of our samples belonged to haddock instead of cod, which suggests species mislabeling is on a downward trend in Europe thanks to robust traceability and labeling regulations.
But the geographic origins of nearly a third of the samples was incorrectly reported in written or verbal communication. We might have expected fish from the over exploited North Sea stock to have been passed off as fish from the remote and less heavily fished northeast Arctic, but the opposite was observed. Somewhat surprisingly, errors were more prevalent among samples that were labelled as originating in the overexploited North Sea stock.
The mislabelling of cod on fishmonger stalls, like this one in France, was more common for North Sea fish. Cusa et al. (2025)/Fisheries Research
Why Misreport Fishing Locations?
Whether deliberate or not, the reasons behind the mislabeling of any seafood product are not straightforward, but range from economic incentives to supply chain complications.
Mislabeling a product’s fishing location can hide serious infringements—by passing off fish from a depleted stock as sustainably caught, for example. It can also be motivated by consumer preferences. People tend to prefer local products, and in the case of cod, may prefer fish from regional waters, especially if they are unaware that it is a depleted stock.
Despite a relatively strong framework for tracing and labeling seafood in the EU and in the UK, enforcement is inconsistent. Issues persist with paper-based methods for tracing fish origins, though a fully digital system could replace this in the EU in the near future.
Atlantic cod is a staple fish and one of the most comprehensively studied. The prevalence of mislabeled origins for this species—and in a market with relatively stringent regulation—should raise concerns about the misrepresentation of other species elsewhere.
Methods for investigating species mislabeling have been refined, while those designed to evaluate the fishing location of marketed seafood are underused. This must change. The routine application of DNA testing could aid the monitoring of wild fish and the sustainable consumption of seafood.
When buying fish from a fishmonger, ask where it was caught, instead of asking if it is local. This can help you select fish that was caught in the region rather than fish caught by local fishers in a distant sea. When buying from a supermarket, check that the fishing location is indicated on the label. Some regions are associated with higher risks of human rights abuse or illegal, unreported and unregulated fishing. Inform yourself on which regions are affected by these problems, and if possible, try and avoid seafood from there.
Staying informed can help you avoid falling hook, line and sinker for mislabeled fish next time you shop.
Marine Cusa, Pew Marine Fellow; Marine Policy Advisor, Oceana Europe & Research Scientist, Technical University of Denmark
Stefano Mariani, Professor of Marine Biodiversity, Liverpool John Moores University
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