The translucent larvae of the European eel, fished in Atlantic waters and often sent out to Asian markets, is an endangered species and its trade is prohibited.

The Creteil court outside Paris sentenced two men who had previously been detained to the heaviest sentences of five years in prison.

Two defendants facing heavier jail time were at large, while the four others got lower sentences.

This case is "extraordinary, due to the quantities seized but also the extremely thorough nature of the investigations", prosecutor said during the trial, comparing the trafficking of the larvae to that of cocaine.

One prosecutor described eel larvae as "prohibited goods that increase in value with each border crossing, such as cocaine".

At the heart of this case was the seizure in February 2023 in a clandestine warehouse in the Val-de-Marne department southeast of Paris of more than 300 kilograms (660 pounds) of the eel larvae.

This represented almost double the total amount -- 154 kilograms -- seized by French customs in all of 2024.

The smuggling of European eels, which have been protected by international convention since 2009, is one of the causes of their 75 percent population decline over the past 30 years.

In France, their fishing is highly regulated and subject to strict quotas.

The value of the larvae discovered in France in the case was estimated by investigators at 1.7-2.1 million euros ($1.9-2.3 million).

The eels -- known at this stage of their lives as glass eels -- fetch "between 5,000 and 6,000 euros per kilogramme" in Asian markets after being trafficked, according to France's National Anti-Fraud Office (ONAF).