Shark on the menu at fish and chip shops despite being deemed threatened species

DNA analysis revealed threatened species are being sold as flake. (Supplied: University of Adelaide)

Threatened species of shark might not sound all that mouth-watering, but DNA analysis has revealed they are making their way into servings of fish and chips sold by takeaway shops in parts of Australia.

Research by the University of Adelaide analysed flake fillets sold by more than 100 outlets across Adelaide and regional SA, and identified barely a quarter as the non-endangered gummy shark.

Instead, four threatened species were identified as being sold as flake, including the short-fin mako and smooth hammerhead.

Over six months, researchers collected 125 flake samples “from retailers across the Adelaide metropolitan area and coastal regional areas”, and used a process known as DNA barcoding, which looks for genes specific to various species, to identify them.

“Of the fillets sold under the umbrella term ‘flake’, only 27 per cent were gummy shark and adhered to guidelines of the Australian Fish Names Standards,” the research, recently published in the journal Food Control, stated.

Nine species were identified during the survey, including some which were not found in Australian waters, and researchers further found that as many as one in five fillets was incorrectly labelled when being sold as takeaway.

“Our results highlight the need for clearer national guidelines or labelling laws for shark fillets,” said lead researcher Ashleigh Sharrad.

“This is the key to building trust across the supply chain, boosting demand for local, sustainable catch.”

Retailers were themselves most likely unaware of the issue, because they mostly buy “bulk, processed or frozen fish fillets”.

Senior author and researcher Bronwyn Gillanders said food fraud in the seafood industry had concerning ramifications.

“It can have potential implications on human health, the economy, and species conservation,” she said.