High levels of mislabelling of shark flesh in Australian fish markets and seafood shops

Context

Overfishing is a major cause of decline for many shark species globally, which can be largely offset by shifting consumer demand to sustainable harvests. The inherent difficulty identifying shark species after processing makes informative labelling fundamental to achieving a sustainable market.

Aims

We evaluated the level of mislabelling in Australia from shark flesh samples obtained from seafood suppliers across the country.

Methods

We used sequence data from the cytochrome oxidase subunit one gene (COI) and the 12S mitochondrial RNA gene (12S) to identify genera and likely species.

Key results

We used genetic sequence data to identify species from tissue samples from 91 fillets labelled as shark. Of these, 64 (70%) were mislabelled, and 9 comprised three species listed as threatened in Australia, the scalloped hammerhead (Sphryna lewini), greeneye spurdog (Squalus chloroculus) and school shark (Galeorhinus galeus). The scalloped hammerhead and greeneye spurdog were being sold under the label ‘flake’. Overall, 70% of samples were mislabelled and the proportion of mislabelling was significantly greater in takeaways compared with fish markets and wholesalers.

Conclusions

High levels of mislabelling of shark product in Australian fish markets and seafood shops was apparent both with respect to the genetically identified shark sample not matching the label and the use of ambiguous labels that do not adhere to the Australian Fish Names Standard. Mislabelling masked the presence of threatened species.

Implications

Our results reveal labelling practices that are not providing consumers with reliable information to identify shark products, and we demonstrate the utility of molecular methods in seafood trade monitoring.