AN eel pass is being installed in Bolton-upon-Dearne to help eels swim over a weir and continue their journey up the river.

Eel passes allow young eels (elvers) to wriggle their way over an obstruction. The new pass in the Dearne is being installed thanks to funding secured by the Don Catchment Rivers Trust (DCRT) from the Environment Agency.

Once very commonly found in the rivers in South Yorkshire, eels are a migratory species that breed in the Sargasso Sea in the middle of the Atlantic.

The young eels migrate from the sea to estuaries like the Humber and from there to the rivers and streams where they mature before returning to the sea several years later.

The number of European eels across the continent have declined by as much as 95 per cent since the 1980s. Hundreds of years of industry and the associated pollution in the Dearne Valley and the wider Don Catchment saw a huge decline in all fish species.

Karen Eynon, from the Don Catchment Rivers Trust, said: "Fortunately the rivers in South Yorkshire are improving steadily. Eels are an important creature in our rivers; they're of huge value for biodiversity and any works to improve our eel populations have benefits for other fish and wildlife such as bittern and otter, which rely heavily on eels as a food source."

The Don Catchment Rivers Trust released 50,000 eels into Old Moor RSPB reserve in 2010 and is hoping to release more this year in the Dearne Valley.