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DNA testing: Is your Friday night takeaway the reel deal?

April 21, 2017

Fish and chip shops without a Marine Stewardship Council (MSC) certificate are five times more likely to serve the wrong species to their customers according to DNA tests released today. Conducted as part of regular MSC authentication tests, the study revealed fish mislabelling at a rate of just 1.64% in shops with an MSC certificate, compared to over 8% in a parallel sample of the nearest non-certified shops.

George Clark, MSC Senior Commercial Manager for the UK explains, “British consumers are more savvy than ever when it comes to food provenance. They want to know exactly what is in their food and where it comes from – especially when they’re choosing fish specifically for its environmental credentials. The DNA results are clear, your Friday night takeaway is far more likely to be the fish you think you’ve bought if it’s MSC labelled. It’ll also be sustainable, responsibly caught and fully traceable.”

 DNA tests on MSC products in the past have shown consistently that in most cases (97.8 – 100% of products tested ) the fish purchased is the species it claims to be.

The overall results indicate a marked improvement in mislabelling in the industry. In 2014, the consumer organisation Which? conducted a study of fish and chip shops in conjunction with the Institute of Global Food Security (IGFS), Queen’s University Belfast. Their Stop Food Fraud campaign, found one in six (16%) fish were mislabelled. The MSC tests also show that British chippies are far ahead of the global seafood mislabelling rate of 30%.

Professor Chris Elliott, founder of the IGFS, comments, “It’s reassuring that the level of fish mislabelling in the UK is much lower than other reported regions in the world. However, the fact that the MSC certified shops performed so much better is a clear indication of the importance of the programme. Not only does it help assure customers of the sustainability of their fish but also that they are getting what they’ve paid for.”

DNA testing results

The DNA tests were conducted by SASA laboratory on samples of battered fish from 122 shops in the UK and Ireland, half of which were MSC certified5. The results showed that five out of the nearby 61 non-MSC shops (8.2%) sampled served fish that differed from the species advertised. One of them was serving cheaper whiting (Merlangius merlangus) instead of cod (Gadus morhua). In contrast, only one sample from the 61 MSC certified shops (1.64%) was found to be haddock instead of cod.

The MSC label assures diners that a fish is not only sustainable and fully traceable, but also the species it claims to be5. Independent DNA testing is a key component in the monitoring of the effectiveness of the MSC programme as a whole.

Fish and chip shops that sell MSC labelled seafood are helping to protect fish supplies for the future by supporting sustainable fishing practices and encouraging other fisheries to reach the MSC standard.

Testing and results

The MSC regularly carries out authentication tests on MSC ecolabelled products collected at certified dealers as part of assurance activities. In this study, an MSC fish meal was anonymously purchased without prior warning from every certified fish and chip shop during March – October 2016 (61 shops at the time) and an equivalent product of the same species was purchased from the nearest available non-MSC shop. The samples (61 MSC and 61 non-MSC) were DNA tested to verify the species by an independent laboratory, the Wildlife DNA Forensics – Diagnostics, Wildlife & Molecular Biology Section at Science and Advice for Scottish Agriculture (SASA). SASA is accredited by the United Kingdom Accreditation Service (UKAS) to carry out Species identification by DNA sequencing.

The negative results that indicated misdescription incidents are shown in the table below:


Sample type

Species purchased

Result species

MSC certified shop 1


Melanogrammus aeglefinus (haddock)

Non-MSC certified shop 1


Gadus morhua (Atlantic cod)

Non-MSC certified shop 2


M. aeglefinus (haddock)

Non-MSC certified shop 3


G. morhua (Atlantic cod)

Non-MSC certified shop 4


M. aeglefinus (haddock)

Non-MSC certified shop 5


Merlangius merlangus (whiting)

Five times more likely...

The non-certified chippies were 5.36 times more likely to serve the wrong species as calculated using the Odds Ratio, where MSC certification is viewed as the ‘treatment’ and misdescription as the ‘event’. 


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