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Researchers at Macquarie University have found a significant portion of shark meat sold in Australian fish markets and takeaway shops is mislabeled, including several samples from threatened species.

The , published in the journal Marine and Freshwater Research this month, highlight the ineffectiveness of seafood labeling and the grave implications for both consumer choice and shark conservation.

Research carried out by Masters of Research candidate Teagan Parker Kielniacz, and supervised by Nicolette Armansin and Professor Adam Stow, collected 91 samples of shark meat from 28 retailers across six Australian states and territories.

Using DNA barcoding, a technique that matches genetic sequences to a reference database, they identified the species of each sample and compared it to the label applied by the retailer.

High level of mislabeling

The results of the study were alarming. Around 70% of the samples were mislabeled, either because the species did not match the label or the label did not comply with the Australian Fish Names Standard (AFNS).

Mislabeling was particularly high for samples labeled as "flake," which the AFNS restricts to fish from just two sustainably caught shark species: the gummy shark and New Zealand rig shark.

The research found that 88% of "flake" samples were not from either of these species.

"Our research shows that mislabeling of shark meat is a widespread problem in Australia," said Parker Kielniacz.

"Consumers assume that because you can buy flake, it is a sustainable choice, but it's a bit more nuanced than that; most flake was not from sustainably caught shark species."

The study identified that nine of the samples came from three species listed as threatened in Australia, including the critically endangered scalloped hammerhead and school shark. All were sold as "flake."

Parker Kielniacz says mislabeling was markedly higher in takeaway shops compared to fish markets and wholesalers, indicating the problem worsens down the supply chain.

"I was surprised by the amount of people who didn't know what flake was. They didn't realize it was shark, or even know that shark could be sold," she says.

Setting a baseline

The research underscores the urgent need for improved labeling standards and enforcement, says co-author and research supervisor Armansin.

"Many shark populations are facing unprecedented declines worldwide, and yet consumers have little idea of the provenance of the fish they are eating, and they are not told they are eating a threatened species," she says.

While Australia is signatory to several relevant international conventions, including the 1982 United Nations Convention on the Law of the Sea (UNCLOS) and the 1995 United Nations Fish Stocks Agreement (UNFSA) on sustainable fisheries, the use of AFNS standards is only a recommendation.

"As long as Australia allows shark meat to be sold just as 'shark meat,' we can't enforce labeling standards, which is a problem for both consumers and for threatened species protection," says Armansin.

"Without having a baseline that says this is what you need to tell consumers, there's nothing to say you're doing it poorly.

"Until labeling laws are taken more seriously for seafood in general, we're chasing our tails because there's no standard."

Mislabeling shark meat is a global problem, she adds.

"Ambiguous trade labels like 'flake' are a real hindrance to sustainable consumption."

Mass DNA testing

Professor Stow heads the conservation genetics laboratory at Macquarie University, where this research was conducted, and is corresponding author on the study.

He says DNA testing is rapidly becoming cheap, flexible and fast enough to enable large-scale monitoring of the seafood supply chain.

"DNA barcoding is becoming quite an efficient and tractable way to monitor species of origin when it comes to fish, and in particular, sharks," he says.

Rapid screening methods, such as testing bilge water from fishing boats or wastewater from fish markets, could be used to determine what species have been caught or traded.

"It's possible to collect a sample from drains next to the fish stalls to identify exactly what species are being sold in that fish market and flag any species that is endangered," Professor Stow says.

"One way forward is to industrialize cheap and efficient means of large-scale DNA monitoring."

This study shows that giving consumers access to accurate information is vital for building a more ethical and sustainable shark meat industry in Australia.

"Everybody wants to trust that what they're eating is what the label says it is," Parker Kielniacz says.

"Our study found that for 70% of samples, we're not getting what's on the label—that's really significant."

This content was originally published on The Macquarie University .