DNA reveals threatened sharks in Australian chip shops

A study in Australia has found that threatened shark species are on sale under the umbrella of shark ‘flake’ in retail stores, with a high level of mislabelling that could point to fraud in the supply chain.

The researchers collected samples of shark flake at 104 retailers, including, wholesalers, takeaways and fish and chip shops, and found using mitochondrial DNA analysis identified nine species, including four that are classed as being under threat, including the short-finned mako and smooth hammerhead.

“Of all the samples and shops analysed, only 11 per cent of retailers correctly identified the species they sold, another 20 per cent were mislabelled and the remaining only had ambiguous labelling,” they write in the journal Food Control.

In Australia, only two species of shark are recommended as sustainable sources, namely the gummy shark and New Zealand rig.

The use of the term flake as an umbrella term for shark meat makes the market difficult to monitor, but the scientists say that their DNA barcoding is “an effective tool to test ambiguous labelling in processed and cooked shark meat products.”

Seafood is still caught in the wild and traded globally, so illegal activities can be difficult to detect or monitor, in particular due to the practice of transferring catches in the open ocean, which is known as transhipment.

Some governments and non-governmental organizations have been pushing for a ban on transhipment at sea, which is also a problem in the tuna industry, as well as for improved traceability schemes to combat illicit trade and prevent illegal fishing.

For example, the European Parliament has adopted a policy that calls for a mandatory digital and harmonised system to make seafood products in the EU market fully traceable.

According to the researchers – from the School of Biological Sciences at the University of Adelaide - the main motivator for this type of fraud is higher profit margins at the point of sale, or to conceal from buyers the possible health implications or environmental impact of the product being sold.

Image by baechi from Pixabay