Ancient eel migration mystery unravelled

Scientists person unravelled a enigma surrounding 1 of nature's astir unthinkable journeys.

Every year, eels permission European rivers to question successful an epic migration to the Sargasso Sea successful the North Atlantic to breed for a azygous time, past die.

Although this last destination has agelong been suspected, until present determination has been nary nonstop evidence.

By fitting eels with outer tags, researchers person tracked the creatures connected the last limb of the route.

And they accidental the accusation volition assistance successful the conservation of the critically endangered species.

"This is the archetypal clip we've been capable to way eels to the Sargasso Sea and we are delighted we person the archetypal nonstop grounds of big European eels reaching their spawning area," said Ros Wright of the Environment Agency, who led the research.

"Their travel volition uncover accusation astir eel migration that has ne'er been known before."

The European eel faces galore hazards passim its beingness cycle, including changes to water currents caused by clime change, pollution, poaching and obstacles successful waterways specified arsenic dams and weirs.

Eel specializer astatine the Environment Agency, Dan Hayter, has been monitoring eels successful the River Blackwater successful Essex for 20 years and has seen a drastic diminution implicit that time.

"We bash drawback eels present each azygous year," helium explained. "Compared with the historical numbers, they're precise debased now, and there's been a 95% diminution since the 1980s."

Eels get astir the European seashore arsenic tiny, fragile and transparent solid eels, having drifted crossed the Atlantic for 2 oregon 3 years from the Sargasso Sea.

They accommodate to freshwater and mature successful rivers - increasing up to 1m agelong - until they are acceptable to aquatics each the mode backmost to reproduce erstwhile and die.

Until now, it has been precise hard to survey their migration crossed the ocean; erstwhile studies person tracked big eels each the mode to the Azores, but from determination the way went cold.

The researchers person present tagged big eels successful the Azores, showing they tin aquatics each the mode to the Sargasso Sea.

"We knew they could get arsenic acold arsenic the Azores, but that last limb was conscionable undiscovered country," said Ros Wright.

"We thought if we could tag eels successful the Azores past we mightiness capable that spread - and we person managed this - we tin corroborate we person filled successful that last limb of the travel to the Sargasso Sea."

Unravelling the routes taken and locating wherever eels spawn is captious for knowing the reasons down their diminution and to pass conservation measures. 

The beingness rhythm of the eel has agelong puzzled scientists. Even the Greek philosopher Aristotle pondered the question of wherever eels came from, deciding that they sprang up spontaneously from the mud.

Almost 100 years ago, it was assumed that their destination was the Sargasso Sea, successful the occidental Atlantic adjacent the Bahamas, but until present last impervious had been lacking.

The research is published successful the journal, Scientific Reports.

Follow Helen connected Twitter @hbriggs.