The river The Severn in England plays a crucial role for the eel in Sweden.

Millions of fry that have been released into Swedish waters have been fished up there and then transported to Sweden.

But in addition to legal fishing, The Severn and some other rivers in Western Europe are also crime scenes.

The illegal trade in eel is both large and organized, says British police officer Ian Guildford, who specializes in crimes related to wildlife.

- Most people do not understand the extent of it, says Ian Guildford.

“The World's Most Smuggled Animals” 

Ten years ago, the export of glass eels from Europe was banned, as the species was listed as critically endangered.

Since then, Europol has made numerous arrests.

The market is in China, where eel fry are grown on thousands of eel farms for a coveted delicacy. 

A suitcase with a glass eel can be worth one million kronor.

- It is impossible to ignore that they are the world's most smuggled animals, both in number and value.

It's amazing.

One thinks: Why do we hear so much about rhino horns and shark fins, but nothing about eels?

says British journalist Joe Crowley, who reviewed the glass eel trade for the BBC.

Small risk of getting caught

When Assignment Review accompanies Joe Crowley for an evening along The Severn, several fishermen are out.

Most fish legally, but the temptation to sell black to an illegal buyer is great.

- You can get up to 10,000 pounds per kilo on the black market, if it goes to Asia.

But I do not want to do that, says a man who wishes to remain anonymous.

Unlike the illegal drug trade, the risk of getting caught up in the illegal trade in eel is small - and the penalties are low.

- Once the eel is caught, it is difficult to keep track of where it is going.

Many eels disappear from the system, says journalist Joe Crawley.

"Incredible pictures from Sweden"

Old age has been going on for decades.

Only about one percent of the number of eel fry that reached Sweden's coasts in the 60s comes today.

Assignment review has been able to tell about how hydropower is a big reason why so many eels die. 

At the same time, millions of fry are disappearing into the illegal trade. 

- It is very well organized and gives a huge amount of money.

Those who trade in drugs, people and weapons have also started with eels, says Andrew Kerr from Sustainable Eel Group

To kill an adult, playful, white eel, Andrew Kerr calls madness.

- There will be incredible pictures from Sweden and Scandinavia of large eel females killed in turbines.

But people do not realize the importance of it.

Each kilogram of female female eel corresponds to one million eggs.

This is where the future lies.