Eels breed in the Sargasso Sea, part of the Atlantic Ocean, running from the Gulf of Mexico to the coast of South America, before swimming into freshwater across Europe and Northern Africa.
They can also cross grass wetlands to reach water courses, where they can spend around 10 years maturing and reaching sizes of up to a metre (3ft) in length, before returning to the Atlantic to breed.
Jones said the second sighting in the Sherbourne suggests the quality of the water in the river is improving.
“They like a diverse habitat and relatively clean water, so the fact they’re returning is a good sign we may be starting to achieve those things in Coventry,” he said.
However, the extent to which eels are returning to rivers in Coventry and Warwickshire is not known and Jones is asking for help in tracking numbers.
“If you do see an eel and can snap a photo and send it off to the Warwickshire Biological Centre or the ecology inbox at Coventry City Council, so we can start to see if there are more and maybe it’s just that people have been missing them, that would be fantastic,” said Jones.