February 26, 2021

Order grouper and serve perch of the Nile | Science

Order grouper and serve perch of the Nile | Science

The biologist José Luis Hórreo and his colleagues have spent the last months eating fish, paid for with their money, in restaurants in Madrid. Specifically, in 53 establishments in the districts of Arganzuela, Carabanchel, Centro, Chamartín, Chamberí, Latina, Moncloa, Salamanca and Tetuán. When the waiter did not look, they took a sample from the plate and put it into a small cylindrical plastic container, which they hid in their pocket. When they got home, they put the fish in the freezer.

The DNA analysis of 77 of these dishes suggests that 36% of the fish were mislabeled. In a restaurant in Centro, for example, they asked for grouper and they put perch of the Nile, a fish native to Ethiopia. In another inn in Chamartín, the menu offered shark, a kind of shark, but in its place it was served as a fish, which is not even similar. And, in another establishment in the Barrio de Salamanca, the turbot became Pleuronectes punctatissimus, a species of lower value.

"It could be a fraud for economic reasons, but we do not know", recognizes the biologist José Luis Hórreo

"It could be a fraud for economic reasons, but we do not know," says Hórreo, a researcher at the National Museum of Natural Sciences. "You can also get a fish more expensive than the one you ordered because it's getting bad, so you do not have to throw it away," he speculates. His study, published in the specialized magazine Food Control, does not inquire into the causes or the origin of the erroneous labeling. "We need more funding to do more research and find out," he explains.

Hórreo recalls a previous study, directed in 2011 by the biologist Eva García Vázquez, from the University of Oviedo. DNA analysis of 18 lots of hake showed that 39% of the pieces were mislabeled in the market. Species from South Africa, cheaper for the lower salary of the fishermen, were sold as if they were from European waters. The alleged fraud appeared more in processed products – like fillets – than in whole fish.

In the new work, the authors have included results with a slight margin of error, since the DNA of the sample matches only 98% with the genetic profiles of other species. If only 100% similarities are taken into account, nine of 32 samples (28%) were mislabeled. Hórreo emphasizes that the mistake in the marking of a fish can occur at any time of the process, from fishing to the restaurant, passing through the fish market and the supermarket.

Another investigation in 22 Spanish establishments has shown that half of them sold some fish with the wrong name, such as light tuna served as bluefin tuna

The biologist warns that wrong labeling can hide harmful effects on the environment. "We may be overexploiting endangered species and we do not know," he says. In 2012, the team of Eva García Vázquez detected that 60% of the roosters of the fishmongers are mislabelled, after analyzing 264 specimens in five different markets. What was sold as a European rooster was, often, a spotted rooster, a species subjected to invisible overfishing. The scientists also observed that 90% of the roosters that arrived at port were registered as European, although the analysis of their DNA revealed that 50% were spotted roosters, fish without control.

The new research has involved four scientists from the National Museum of Natural Sciences and the ecologist Alberto Jiménez, from the University of Alcalá. The authors warn that "food fraud" can also "produce health problems for consumers". A person can be allergic to a fish and eat it without being aware of it. And the parasites also vary between one species and another.

"The size of our sample is small, but the results are quite striking," says Hórreo. His team has found fish sold under the wrong name in 37% of the restaurants studied and in 71% of the districts. The problem is, apparently, extended by Madrid, without great differences between some areas and others. "There are no more mistakes in the labeling in the Barrio de Salamanca than in Tetuán," says the biologist.

In April, an investigation in 180 hotels and restaurants in 23 European countries revealed that 31% sold some fish with a wrong name. In Spain, half of the 22 establishments analyzed offered some species and served others, according to the study, headed by Begoña Pérez and Miguel Ángel Pardo, of the AZTI Technology Center, in Derio (Bizkaia). In a restaurant in Madrid, they ordered bluefin tuna and ate light tuna.


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