- The illegal trafficking of critically endangered European glass eels continues to thrive, generating up to 3 billion euros ($3.5 billion) in peak years, with more than 1 million live eels seized in 2023 alone — mostly en route to East Asian aquaculture farms where they’re raised to maturity to produce the delicacy unagi.
- Europol describes the trade as a highly organized transnational crime involving smuggling, document fraud and money laundering, with sophisticated players using scientific expertise to keep smuggled eels alive during transit.
- Conservationists warn that removing juvenile eels from the wild disrupts their life cycle and ecosystem functions, worsening the species’ 90% population decline since the 1970s and threatening biodiversity in connected marine and freshwater systems.
- Experts call for stronger enforcement, improved monitoring, public awareness and habitat restoration to combat the trade and avert further ecological damage.
Tiny, translucent and no longer than a finger, juvenile European eels, also known as glass eels, might not look like much. But demand for these slippery creatures, particularly in East Asia, has made them one of the world’s most trafficked animals, driving the species to the edge of extinction.
A new 2025 Europol serious and organized crime threat assessment estimates that illegal glass eel trafficking has generated up to 3 billion euros ($3.5 billion) during peak years, placing it among the most lucrative wildlife crimes globally. A separate 2025 report by wildlife trade watchdog TRAFFIC confirms the scale: EU authorities seized more than 1 million live eels in nearly 5,200 cases in 2023.
Their destination? Aquaculture farms in China, Japan, South Korea, Taiwan and Hong Kong, where they’re raised to maturity and sold, often ending up grilled at high-end restaurants as unagi, a prized Japanese delicacy.
A decades-old trade still booming
The illegal trade in European eels (Anguilla anguilla) isn’t new; it began surging in the 1990s, when Japan’s native eel stocks began to collapse. To fill the gap, East Asian farms turned to importing wild-caught European eels.
Unlike sturgeon, which can be bred in captivity to produce caviar, European eels can’t be commercially bred; according to the U.N. Office on Drugs and Crime, adult eels have never been successfully bred in captivity. That leaves farms entirely dependent on wild-caught juveniles, making glass eels a high-value commodity.
Despite being listed under Appendix II of CITES, the international wildlife trade convention, and subject to a European Union export ban since 2010, European eels are still trafficked in huge numbers. The species, now listed as critically endangered by the global conservation authority IUCN, has seen its population decline by more than 90% since the 1970s due to overfishing and other threats.
Yet the trade shows little sign of slowing. “Persistent demand and significant profits make it attractive to organised criminal groups,” Mònica Pons-Hernández, a green criminology postdoctoral research fellow at the University of Bergen in Norway, told Mongabay by email. “They’re highly motivated to adapt — finding new routes and ways to smuggle eels out of the EU despite increased enforcement.”
New data from TRAFFIC’s 2025 EU wildlife seizure report reveals the central role Europe plays in this ongoing trade. In 2023 alone, EU member states recorded nearly 5,200 wildlife seizures involving more than 1 million specimens. Remarkably, 86% of those specimens were European eels — most of them live individuals, often trafficked by air and recorded by weight.
Smugglers stay ahead of the game
Enforcement is ramping up, but trafficking networks continue to evolve. Europol describes eel trafficking as a complex, highly organized crime involving wildlife smuggling, document fraud, tax evasion and money laundering. Highly sophisticated criminal networks in Europe and Asia work in tandem to traffic live juvenile eels. Some networks even employ biologists, veterinarians and chemists to ensure the animals survive long enough to reach their final destination.
“Criminal networks active in wildlife crime are characterised by high levels of expertise, with specialists … either part of networks or offering their knowledge on a crime-as-a-service basis,” Europol noted. “This knowledge is combined with a strong understanding of the market, access to a relevant network of buyers and sellers, and awareness of the regulations and market dynamics. “
Louisa Musing, TRAFFIC’s senior program officer for Europe, told Mongabay the scale and diversity of the illegal trade, including in glass eels, demands a far more proactive response. “This underscores the urgent need for coordinated enforcement at both EU and national levels, stronger legislation, and greater public awareness.”
Pons-Hernández said there’s a “clear need to harmonise legislation across jurisdictions” to close legal loopholes. In a 2024 paper in the European Journal of Criminology, she explained that while the EU bans eel exports and imports, those restrictions don’t apply to non-EU countries like Morocco and post-Brexit U.K., turning them into key transit hubs for trafficking.
Within the EU, patchy national regulations also leave room for exploitation, Pons-Hernández’s study found. France, for instance, sets national quotas and offers subsidies for restocking, while Spain’s laws vary by region, allowing traffickers to operate in areas with looser controls. In Portugal, glass eel fishing is allowed only in the Minho River, but traffickers reportedly inflate legal catch records there to launder hauls taken illegally from other rivers.
The hidden ecological toll
Beyond the financial and criminal implications, the illegal eel trade is taking a toll on nature.
A January 2025 study published in Science of The Total Environment found that glass eels rescued from smuggling operations suffer immense stress. When released back into their native habitats in Europe, they take up to two months to recover from the harsh transport conditions. During this time, their immune systems are weakened, making them vulnerable to bacterial infections that could spread through wild populations, said Ignasi Sanahuja, study lead author and physiology professor at the University of Barcelona.
European eels play multiple roles in aquatic ecosystems, Sanahuja said. As juveniles, they’re prey for birds, mammals and larger fish. As adults, they become predators, feeding on invertebrates, small fish and organic matter. Their migrations between marine and freshwater systems help transport nutrients and maintain food web balance, and they shape habitats through their burrowing behavior.
With no viable captive-breeding option, the taking of each wild eel has lasting ecological consequences, conservationists say. The species’ complex life cycle — from spawning in the Sargasso Sea to maturing in European rivers — links marine, estuarine and freshwater ecosystems.
“Disruptions at any stage — especially through overharvesting of glass eels — can collapse the entire population structure,” Sanahuja told Mongabay by email. “Continued unregulated trade exacerbates this decline, threatening not only the species but also the ecological balance of the habitats they occupy.”
The risks extend beyond Europe. Researchers have warned since the early 2000s about the ecological dangers of farming nonnative European eels in Asia. Escaped or discarded individuals have been detected in Japanese and Taiwanese waters, where they compete with native eel species and potentially interbreed, raising fears of hybridization and species collapse.
As demand for grilled eel dishes in Asia continues, experts warn that pressure on wild populations will only increase unless enforcement and international cooperation improve. Sanahuja and other researchers say conservation must go beyond seizures and arrests: better monitoring, public education, habitat restoration, and reintroduction programs are also needed.
“The illegal or excessive harvest of glass eels strips away a critical life stage,” he said. “That disrupts their ecological role — leading to a cascade of effects like overpopulation of aquatic insects, reduced food for eel predators, and weakened ecosystem resilience.”
Banner image: Glass eels are a juvenile form of the European eel (Anguilla anguilla), a species that undergoes an incredible 10,000-km (6,200-mi) migration. Image courtesy of Alessandro Cresci.
Conservationists aim to save critically endangered European eels on Italy’s Po River
Citations:
Pons-Hernández, M. (2024). Inside the slippery world of glass eel trafficking: Lessons learned from Spain to prevent the illegal trade of European eels. European Journal of Criminology, 21(6), 908-928. doi:10.1177/14773708241262885
Sanahuja, I., Fernandez-Alacid, L., Sangiacomo, C., & Gisbert, E. (2025). The hidden cost of illicit trade: Evaluating the physiological health of smuggled European glass eels (Anguilla anguilla). Science of The Total Environment, 960, 178346. doi:10.1016/j.scitotenv.2024.178346
