Endangered sharks are being served at chip shops across the United Kingdom, according to researchers who used DNA to prove the disturbing findings.

The majority of shops that were tested were found to be selling spiny dogfish — a shark species that is listed as endangered in Europe by the International Union for the Conservation of Nature — under generic names like huss, rock, flake and rock salmon.

“It’s almost impossible for consumers to know what they are buying,” Catherine Hobbs of the University of Exeter and lead author of the study published in Scientific Reports, told the Guardian on Tuesday. “People might think they’re getting a sustainably sourced product when they’re actually buying a threatened species.”

The scientists discovered shark meat among 117 tissue samples taken from 90 different chip shops and fishmongers in southern England between February 2016 and November 2017. They used a process known as DNA barcoding to identify the species.

One British wholesaler was unwittingly selling globally endangered scalloped hammerheads, shortfin mako and smalleye hammerhead sharks.

Other shops and sellers were peddling starry smooth-hounds, nursehounds and blue sharks.

The study also revealed that fishmongers were selling shark fins destined for sale in Asian restaurants or supermarkets. Some originated from Mozambique.

Many shark species are permitted by the government to be sold under generic names — like rock — but the researchers say more accurate labeling on food is needed.

“There are also health issues,” noted Hobbs. “Knowing what species you are buying could be important in terms of allergies, toxins, mercury content and the growing concern over microplastics in the marine food chain.”