Skip to main content

What's in your fish dish

What's in your fish dish

A team of researchers at the University of Salford is working on a process to stop an insidious practice that is contributing to the mismanagement of fish stocks worldwide.

Stefano Mariani - Research - University of SalfordThe mislabelling of fish is now a major international concern. Fish stocks around the world are being over-exploited – in the last 50 years nearly one in four of the world’s fisheries has collapsed – and there has also been a dramatic rise in so-called IUU (illegal, unreported and unregulated) fishing. Worth as much as €20 billion a year, it’s an industry that is putting further pressure on the sustainability of our fisheries in part due to mislabelling.

Led by Dr Stefano Mariani, a marine biologist from the School of Environment & Life Sciences, a team is investigating how to optimise and standardise the way in which seafood products are genetically identified, and ultimately make it easier to prosecute mislabelling offenders. According to Mariani, part of the problem stems from the fact that most fish are now processed at sea, where many of the features that set individual species apart are removed.

As a result, fish is sold in such a processed state that it’s hard to know exactly what type of fish it is. This can lead to product substitution, when less valuable, more common species are mislabeled as rarer and often more expensive fish. As well as breaking quotas for certain species, and putting a further strain on the sustainability of fish stocks, it’s a practice that also cheats the consumer and may also expose them to the risk of food allergies. “But don’t blame the fisherman,” says Mariani. “It’s a complicated supply chain and it’s the big processing plants, supermarket chains and suppliers that will decide the fate of different batches and orders of fish.”

Worldwide issue

It’s a problem that is rife all over the world.

Fish Mislabelling - Research - University of SalfordA recent survey in America showed shocking levels of mislabelling, with over 50% of fish wrongly marked. And despite the strong regulations introduced by the EU, there’s evidence that tuna and swordfish caught in the Mediterranean, as well as North Sea cod, are also being mislabelled. What Mariani believes is needed is a forensic test that will enable investigators to check whether fish have been caught illegally, or whether a product in a supermarket or restaurant has been mislabelled. DNA testing is central to this, and offers a quick, cost-effective and reliable method, which can distinguish between species and provide the forensic evidence needed to take a case to court. However, at the moment, a variety of different methods are being used.

 “The ultimate aim of the research is to produce a simple, standardised process that allows you to take a piece of fish, subject it to the extraction of the DNA, and then the sequencing of a particular portion of the DNA that identifies the actual species that you are dealing with,” explains Mariani. “It’s a process that is very similar to that which has been used in the recent horse meat scandal.”

Mariani’s research is part of a European project called LABELFISH, which includes partners in Ireland, Portugal, Spain, France and Germany, and will focus on eight of the most popular species - Atlantic cod, haddock, hake, monkfish, plaice, tuna, ling and sardine. The research will also test the effectiveness of EU legislation.

Mariani’s team, and those in the partner countries, have been testing shop-bought samples of fish using a variety of different DNA testing technologies.

“Traditionally different countries and different governments had different control labs that were using different techniques to achieve the same results, and there was a lot of inconsistency. This can be a problem with potential legal cases.

“We are aiming to standardise this whole process as much as possible and hopefully this will then become a model used around the world.

 “We want to ensure that in terms of procedure, collecting, delivery and reproducibility of all the results, regardless of what country or laboratory you’re in, it’s going to be 100% reliable.

“Ultimately,” he adds, “I would love to see national, compulsory and well-enforced genetic testing, and random spot checking of products along the production chain in every country.”

Fish mislabelling - Research - University of Salford