Every year, European eels embark on a spectacular migration journey, where their final destination is the Sargasso Sea in the North Atlantic, where they mate once and die. Scientists have long speculated that the Sargasso Sea region off the coast of North America is the final destination for the 6,500-kilometer migration of glass sharks (Anguilla anguilla), also known as European eels. However, there is currently no concrete evidence to support this.
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| Over the past 30 years, eel populations across the continent have declined by more than 90%. Photo: Reuters. |
Critically endangered
However, thanks to modern technological equipment, this hypothesis was eventually confirmed. By connecting satellite trackers to European eels, scientists were able to track the animals on the last leg of their annual migration.
This information will help protect the endangered European eel.
"This is the first time we have been able to track European eels in the Sargasso Sea, and we are delighted to have the first direct evidence of adult European eel activity in their breeding grounds." The UK Environment Agency, which led the study.
"This journey will reveal previously unknown information about European eel migration," Mr Wright added.
Despite a decades-long life cycle, European eels currently face many threats. Changes in ocean currents due to climate change, pollution and overhunting have led to a sharp decline in the population of this species on the Old Continent.
In addition, the formation of dams and hydroelectric projects has prevented them from migrating to the sea to breed.
Dan Hayter, a European eel expert at the UK Environment Agency, tracked the species in Essex's Blackwater River. He has witnessed their terrible decline over the past 20 years.
"We catch European eels here every year. Production is now very low compared to historical figures, down 95 percent since the 1980s," said Mr. Haight.
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| Scientists examine habitat indicators for European eels on the Thames River in London. Photo: European Eel Foundation. |
Despite being endangered, European eels, especially juvenile eels, are still considered a delicacy in Spain and some East Asian countries. It is illegal to buy and sell juvenile eels, which is why smuggling such items can lead to huge profits.
In late September, Europol, the European police agency, arrested 29 people in Spain and another 20 in Europe after the seizure of 180 kilograms of young European eels. The black market value of this shipment is around €237,000.
According to the authorities, smuggling of European eels has increased significantly since the lifting of restrictions on the import and export of frozen goods (due to Covid-19).
Key findings from conservation efforts
"Criminal groups have returned to the illegal export of European eels, camouflaged in hand luggage and, in exceptional cases, hidden in oxygenated bags. We also monitored that the cover was only used to transport eels hidden in frozen food. We would like to remind everyone of a complete ban on the export of eels," the Spanish Police Department said in a statement. News about the case.
In 2020, British seafood trader Gilbert Khoo was indicted after police discovered he was illegally exporting £53 million worth of European eels from London to Hong Kong.
After being born in the Sargasso Sea region for about 3 years, young European eels return to European shores when they are still very young. Because at this stage of their life cycle, they are completely transparent – hence the name "glass eel".
They will begin to adapt to fresh water and mature in rivers. They reach a size of about a meter and they will continue to accompany the river until they are ready to swim out of the sea again to breed and then die.
Because the breeding journey of European eels covers large areas of the Atlantic Ocean, it is difficult for scientists to grasp what happens at this stage. Previous studies of them could only track adults when they arrived in the Portuguese Azores.
But now, scientists have been able to install trackers on adult European eels in the Azores, and the results show they can swim to the Sargasso Sea on the other side of the Atlantic.
"We knew before that European eels could swim to the Azores, but what happened after that remains unexplored," Mr Wright said.
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| After 3 years of drifting in the ocean, young European eels will return to the rivers of Europe. At this stage, they are called "glass eels" and are a very popular food. Photo: European Eel Foundation. |
"We think that if we can install a tracking device in the Azores, then we can solve this problem. We did it – tracking the last stop to the Sargasso Sea," Mr. Wright added.
Identifying the spawning area of the eel is important because it will help scientists find the cause of the species' decline and take the necessary conservation measures.