Eels have a magnetic “sixth sense” that enables them to navigate 5,000 kilometres across the Atlantic from their birthplace in the Sargasso Sea, scientists have discovered.

It enables them to detect changes in the Earth’s magnetic field, which allow them to hitch a ride in the Gulf Stream — a current that carries warm water from the Caribbean to Western Europe. And that reduces the amount of time it takes to make the journey, although it still lasts about 300 days.

The researchers used magnets to simulate conditions at different points on the journey, then noted how this influenced the young eels’ swimming direction. Professor Lewis NaisbettJones, of North Carolina University, said, “We were not surprised to find that eels have a magnetic map, but we were surprised to discover how well they can detect subtle differences in magnetic fields.

“We were even more surprised when our simulation revealed that they use their map not so much to locate Europe, but to target a big conveyor belt — the Gulf Stream — that will take them there.”

Pollution and our enthusiasm for eating eels have seen their numbers plummet by 95 per cent since the 1980s, and they are now critically endangered. It is hoped greater understanding of the animals could help conservation efforts. After their swimming the Atlantic, eels spend the next 15 years growing to maturity in the rivers and estuaries of Europe and North Africa.

Even though festivals of eel catching and eating have been held on rivers across Europe for centuries, their life history had long remained a mystery. It was only in 1922 that their spawning grounds were found, and the late 2000s when the adults’ journey was mapped for the first time.

Ben Upton/The Independent