DNA study reveals fish is not what it seems

85553fa4-4c49-47b1-9a5e-5c2195345a9c

Editor's Picks
Features Post
The brightest pupils
04 October 2021
Features Post
Dealing with egg ‘fungus’
04 October 2021
Features Post
Rathbun’s tetra in the wild
13 September 2021
Fishkeeping News Post
Report: 2021 BKKS National Koi Show results
13 September 2021
Features Post
The World's forgotten fishes
16 August 2021


Scientists are increasingly using DNA barcoding techniques developed for identifying fish species to spot fishmongers who are selling cheaper fish as "cod" or "haddock."

Experts Dana Miller and Stefano Mariani of University College Dublin recently applied the molecular technique to the analysis of fish samples from fish and chip shops, fishmongers and supermarket fish counters to reveal that 25% of "cod" were in fact completely different species.

Their findings, which have just been reported in the journal Frontiers in Ecology and the Environment, found that 28 out of 34 samples of smoked fish were also incorrectly labeled, and 26 out of 28 samples of smoked cod were also other species.

Dana Miller said: ""In light of recent findings from North American scientists using the same approach, it seems mislabeling seafood is pervasive on a global scale. This, coupled with the enormous rise in seafood demand, raises alarm. There is an increasing need for effective and sustainable seafood industry management and especially for transparency within the seafood industry itself on an international level."

The study follows a similar one in the US which found that 25% of fish on sale in US restaurants were also mislabeled.

"Consumers should be able to go to a shop and know they are eating what they paid for, especially when the product is purchased within the EU, where numerous policies relating to labeling and tracing are already in place," said Mariani.

The authors argue that these findings suggest mislabeling could contribute to overfishing—that is, mislabeling cod in Ireland could be creating a false perception of market availability.

"There are many problems associated with mislabeling fish, like in the case of mislabeling the depleted red snapper to enhance perceptions of availability in the US," continued Miller.

"Consumers may think that if 'cod' keeps showing up in markets and restaurants across Ireland, the stocks must be healthy."

The same kind of DNA barcoding techniques are also being developed for the identification of aquarium fish species.