Researchers from the US determined the species of 29 samples of shark meat bought in shops or online. 93% had been labeled ambiguously as ‘shark’, and 31% overall were from four endangered or critically endangered species. Several of these species are known to contain dangerous levels of heavy metals. The authors call for better regulation of labeling and greater consumer awareness.
Sharks have been around for more than 450 million years, but these days they are in deep trouble. Since the 1970s, shark populations have gone down by more than 70% due to unsustainable practices such as shark finning, bycatch, and overfishing, habitat destruction, pollution, and climate change. The International Union for the Conservation of Nature (IUCN) has estimated that of the approximately 550 species of sharks in existence, 14% are vulnerable, 11% endangered, and 12% critically endangered. As a result, 74 species of shark are considered at risk by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), meaning that international trade in their products is banned or heavily regulated – at least on paper.
But now, a study in Frontiers in Marine Science has shown that despite bans and regulations, meat from shark species at risk of extinction is commonly available for sale in the US. And because these products are typically sold under generic labels, customers may buy them without being aware.
“We found critically endangered sharks, including great hammerhead and scalloped hammerhead, being sold in grocery stores, seafood markets, and online. Of the 29 samples, 93% were ambiguously labeled as ‘shark,’ and one of the two products labeled at the species level was mislabeled,” said corresponding Dr. Savannah J. Ryburn, a researcher at the University of North Carolina at Chapel Hill.
The study was carried out by students, teaching assistants, and instructors taking part in a course on seafood forensics at the same university in 2021 and 2022. Its organizers bought 30 shark products – 19 raw steaks and 11 packages of shark jerky – from shops and the internet in Washington DC, North Carolina, Florida, and Georgia. The researchers then used DNA barcoding to determine the species of each product. They compared these with the label under which it had been sold.
Misleading labels
Twenty nine (97%) of the 30 samples were successfully identified to the species level. One of the two samples labeled other than ‘shark’ had been mislabeled: sold as blacktip shark (classified as vulnerable by the IUCN), it really contained meat from the endangered shortfin mako. Only one sample had been sold under an unambiguous, correct label, namely blacktip shark.
Shockingly, 31% percent of the bought samples turned out to be from four endangered or critically endangered species: great hammerhead, scalloped hammerhead, tope, and shortfin mako shark. The others were from another seven species, including the vulnerable spinner, lemon, common tresher, and blacktip shark, and the near threatened smooth-hound and Pacific angelshark. Only one was from a least concern species, the Atlantic sharpnose shark. Moreover, these products were sold remarkably cheaply, at between $6.56 and $11.99 per kilogram for fresh shark meat, and on average $207.37 per kilogram for shark jerky.
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“The legality of selling shark meat in the United States depends largely on where the shark was harvested and the species involved, due to regulations under CITES and the Endangered Species Act,” said Ryburn. “However, by the time large shark species reach grocery stores and markets, they are often sold as fillets with all distinguishing features removed, making it unlikely that sellers know what species they are offering.”
Not only risky for sharks
The authors pointed out that three of the species found in this study – scalloped hammerhead, great hammerhead, and dusky smooth-hound shark – are known to contain high levels of mercury and methylmercury, which damage the brain and central nervous system, and arsenic, which can lead to cancer. All three metals have likewise been implicated in the impaired cognitive development and the death of developing babies.
So what can consumers do to mitigate the risk of consuming toxins and unwittingly contributing to the extinction of species?
“Sellers in the United States should be required to provide species-specific names, and when shark meat is not a food security necessity, consumers should avoid purchasing products that lack species-level labeling or traceable sourcing,” Ryburn counseled.
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