Fraud in the aquatic food sector is often invisible to consumers — until it becomes a serious health hazard. From mislabelling and species substitution to misbranding and adulteration, deceptive practices in seafood markets are more widespread than many realize.

On the International Day of Women and Girls in Science, we spoke with Esther Garrido Gamarro, Food Scientist and Nutritionist and FAO Fisheries Officer at the Food and Agriculture Organization of the United Nations (FAO), about the scope of the problem and the tools available to combat it.

The Hidden Face of Seafood Fraud

The most common forms of fraud in aquatic foods are mislabelling and species substitution — practices that frequently occur where visual identification is difficult, such as in restaurants, catering services, and processed seafood products.

“Consumers often see a fillet, not the whole fish,” explains Garrido Gamarro. “This makes it easy for one species to be substituted for another anywhere along the value chain.”

Other fraudulent practices include:

• Misbranding regarding origin or production method

• Adulteration through unauthorized additives

• Selling protected or regulated species under false names

Fraud in the aquatic food sector is often invisible to consumers until it poses a health risk. Repeated freezing and defrosting of tuna can, for example, pose serious health risks to consumers.

In 2022, more than 12,000 aquatic species were traded globally. With such vast biodiversity — and often significant price differences between species — the opportunity for fraud increases.

For example, farmed salmon is generally less expensive to produce than wild-caught salmon. This price gap creates incentives for dishonest substitution.

When Fraud Becomes a Health Risk

Some forms of seafood fraud pose direct threats to public health.

“If tuna is frozen, then defrosted, and frozen again, histamine levels can become dangerously high,” says Garrido Gamarro. “This presents a serious risk to consumers.”

Aquatic foods are highly susceptible to fraud due to wide price differences and difficulty for consumers to detect fraudulent practices.

Without proper intervention, such products could reach dinner tables. Coordinated enforcement between food safety authorities and law enforcement agencies has helped prevent tonnes of fraudulent and unsafe fish from entering markets worldwide.

These findings are detailed in the new FAO report, “Food Fraud in the Fisheries and Aquaculture Sector.”

Why Aquatic Foods Are Especially Vulnerable

Aquatic foods face unique fraud risks due to:

• The high number of traded species (12,000+ in 2022)

• Major price variations between species

• The difficulty of visual identification once fish are processed

• Low likelihood of detection without laboratory testing

Proving fraud often requires specialized lab analysis — a costly process that not all countries are equipped to perform.

Fraud is more likely to go undetected where:

• Regulatory frameworks are weak or incomplete

• Inspection systems lack capacity

• Laboratory testing infrastructure is insufficient

Science Is Strengthening the Fight

Encouragingly, science is rapidly advancing new tools to detect fraud. Among them:

• Isotope analysis

• Next-generation DNA sequencing

These technologies can accurately determine species identity and origin, even in processed products.

According to Garrido Gamarro, effective governance, coordinated enforcement mechanisms, and a clear understanding of the seafood value chain are essential to stopping fraud “in its tracks.”

Beyond Health: Protecting Biodiversity

Seafood fraud can also undermine conservation efforts.

In some cases, a protected species caught unintentionally may be sold under the name of a similar, non-protected species. Without DNA testing, such substitutions can be difficult to detect.

Selective fishing gear offers a preventative solution. By targeting abundant species and reducing bycatch, fishers can avoid capturing vulnerable species that might otherwise enter the market illegally.

Select types of food fraud and percentage of occurrence in the United States and the European Union. Source: Adapted from Lawrence, S., Elliott, C., Huisman, W., Dean, M. and van Ruth, S. 2022. The 11 sins of seafood: Assessing a decade of food fraud reports in the global supply chain. Comprehensive Reviews in food Science and food Safety, 21(4): 3746-3769. https://doi.org/10.1111/1541-4337.12998

What Can Consumers Do?

While authorities serve as the first line of defence, consumers also play a role.

Garrido Gamarro advises consumers to:

• Learn what their favourite species look like

• Read labels carefully

• Purchase from trusted suppliers

However, she emphasizes that coordinated institutional oversight remains critical — especially since food fraud often crosses international borders.

Block diagram of the seafood supply chain and the authentication  of origin using provenance technology. Source FAO

Inspiring the Next Generation of Scientists

On this day celebrating women and girls in science, Garrido Gamarro also shared a message for young aspiring scientists:

“Science is fun. Science is curiosity,” she says. Recently fascinated by toxins, she explains how these invisible chemical substances can interfere with hormonal, endocrine, neurological, and gastrointestinal systems.

“They’re not alive, yet their molecules can have profound effects,” she notes. Unlike many microbiological hazards that can be neutralized through freezing or cooking, chemical toxins are far more complex — and often more dangerous.

This scientific challenge, she says, has driven her career: finding ways to protect people from food-related risks.

As global seafood trade continues to expand, the fight against fraud will depend on vigilance, innovation and cooperation. With stronger governance, cutting-edge science, and informed consumers, the tools to tackle aquatic food fraud are already within reach.