Animals feeding at sea inherit a chemical record reflecting the area where they fed, which can help track their movements, according to a new study by scientists from the University of Southampton, UK. Chemical testing of the source of marine food products could be a powerful tool to help fight food fraud, maintain healthy sustainable fish stocks or marine protected areas and ensure consumer confidence in marine eco-labeling, the researchers suggest.Chemical variation in jellyfish is an indicator of where they have lived and fed. Image credit: Pixabay.Chemical variation in jellyfish is an indicator of where they have lived and fed. Image credit: Pixabay.

The Southampton research team, led by Dr. Clive Trueman, associate professor in marine ecology, and PhD student Katie St. John Glew, built maps of chemical variation in jellyfish caught across the North Sea. They then compared the same chemical signals in scallops and herring caught in known places across the North Sea and used statistical tests to find the areas of the North Sea with the most similar chemical compositions.

They found that the chemical tests were able to accurately link scallops and herring to their true locations and could be used to determine if the chemical composition of an animal matches a claimed area of origin.

“Understanding the origin of fish or fish products is increasingly important as we try to manage our marine resources more effectively," says Trueman. "Recently, genetic tests have revealed widespread mislabeling of the type of fish being sold worldwide. But currently we don’t have any way of testing where a fished product was caught.”

While fish harvested from sustainable fisheries can fetch a premium price, concerned consumers want to be confident that the fish really were caught from sustainable sources, the researchers add.

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