Great big conger eel deposited on the towpath at Strand on the Green

Conger eel carcass on the towpath at Strand on the Green; photograph Jeremy Day

Did he take a wrong turn up the Thames on his way to the Sargasso Sea?

Whether washed up by the tide, or dragged there by a scavenger, locals were less than impressed to find the carcass of a great big eel on the towpath at Strand on the Green on Thursday morning (9 October).

“That’s a conger and a quickly decomposing one at that”, Paul Coulson FIFM, Chief Executive of the Institute of Fisheries Management, told The Chiswick Calendar.

“Pretty cool to see, despite its state”.

‘Pretty cool’ was not everyone’s reaction, but armed with that knowledge, a quick Google tells me they are fascinating creatures. Talked about by the Ancient Greeks and Egyptians, their origins are thought to be prehistoric.

While European eels are freshwater creatures, living in lakes and rivers for up to 30 years, congers are sea creatures, ranging up to two metres long. They are predators with strong jaws and teeth; they eat anything and have been known to attack humans.

A diver was attacked by a European conger eel in Kilary Harbour in Ireland in 2013. The eel, reportedly more than 1.8m long and “about the width of a human thigh”, took a chunk out of the diver’s face.

Their technique with bigger prey is to body roll it, like a crocodile.

Eels are more a risk from humans than we are from them though. They used to be so plentiful in the River Thames that jellied eels were a staple dish for impoverished Londoners, but now they are on the endangered species list. The Marine Conservation Society rate them at 5 (on a scale of 1-5), under threat from pollution, habitat loss and over-fishing.

The Environment Agency and various environmental charities have been working to improve the eel stocks in the River Thames by introducing measures such as ‘eel ladders’ or passes which allow freshwater eels to move upstream over weirs.

Scientists tracked the migration of eels from Europe to the Sargasso Sea in 2022 by fitting them with satellite tags; map – Centre for Environment, Fisheries and Aquaculture

They are also more at risk than other species because they are semelparous, meaning they spawn only once in their lifetime.

Their lifecycle is fascinating. Typically congers live for between ten and 20 years, and as they become sexually mature they undergo physical changes in preparation for spawning. Like the freshwater European eels, they migrate to the western Atlantic to breed and then die.

They set off in the autumn, around the time of the harvest moon (6 October this year).

So our decomposing conger eel at Strand on the Green may have been on their way to the Sargasso Sea when they met their death. So much more romantic than the indignity of being laid out on the towpath for passers-by to gawp at.

Read more stories on The Chiswick Calendar