Lab technique distinguishes wild and farmed fish

For generations, bighead carp in the Yangtze River Basin has been an important food source in China, although in recent times the species has been threatened by pollution, urban development, and overfishing.

In 2020, the Chinese authorities introduced a 10-year ban on fishing of the species, which is still available as a farmed option for consumers. However, it faces significant challenges in freshwater fish traceability, particularly with live fish in the domestic market, due to the complexity of supply chains, lack of standardised labelling, and the difficulty in separating fish from different sources at retail.

It has been reported that profit-motivated illegal fishing of bighead carp is now a problem, so researchers in China have developed a method of distinguishing between wild and farmed samples based on metabolomics – the set of metabolites present within an organism.

In the journal Food Chemistry, the team report how they identified 20 biomarkers measurable using a standard UHPLC-MS/MS measurement, including eight that could be used to link samples to the Yangtze River, from small samples of muscle tissue that could be collected in the field.

Samples were taken from fish collected at seven different locations, including fish farms and from wild carp, with differing levels of some of the biomarkers, allowing the sources to be distinguished.

"To enhance efforts against illegal fishing and food fraud, it is crucial to identify biomarkers that distinguish between wild and farmed bighead carp in the Yangtze River Basin," write the authors in the paper.

They conclude that the technique has the potential to improve product traceability and authenticate fishery products and holds "significant implications for ecological conservation, market regulation, and the sustainable advancement of aquaculture."

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