A freshwater cod believed to have become extinct in our rivers may not have had its chips yet after all.

For scientists plan to reintroduce the burbot to the Great Ouse and its tributaries, which it once inhabited.

Norfolk Rivers Trust hopes the fish, which was last seen in 1970, can be reintroduced using young specimens from European rivers.

Its technical director Jonah Tosney said: "We're hoping to get them in the river in two to three years' time but there's still a bit of uncertainty.

"We'll import baby fish from Belgium, raise them up to juvenile fish size, about 10cms, then they'll be released."

Eastern Daily Press: A misty dawn on the River Ouse at Ten Mile Bank, near Downham Market, which is one of the rivers where scientists hope to reintroduce the burbotA misty dawn on the River Ouse at Ten Mile Bank, near Downham Market, which is one of the rivers where scientists hope to reintroduce the burbot (Image: Archant)

Dr Tosney said tens of thousands of fish would be released to compensate for an expected high mortality rate, in the hope of re-establishing a breeding population in the Fens.

"We're as confident as we can be," he said. "There's several years of feasibility work gone into it, but there are so many variables like water temperature and water quality so we can't be 100pc certain we'll succeed but we're confident enough to have a go."

If the species does return, it may have a positive effect, for the omnivorous bottom-feeders are likely to eat the alien signal crayfish, which has decimated stocks of the native white-clawed crustacean.

The species went into decline after the Second World War because of pollution and changes to rivers, including dredging and straightening which reduced the amount of slack water the eggs could hatch in before they were washed away downstream.

Burbot, which resemble a cross between an eel and a cod, were once common throughout East Anglia. The last recorded capture was at Denver Sluice, near Downham Market, in 1970.

Eastern Daily Press: A project is under way aiming to reintroduce the burbot to Norfolk rivers. This image is from British Fresh Water Fishes by Rev W. Houghton, illustrated by AF LydonA project is under way aiming to reintroduce the burbot to Norfolk rivers. This image is from British Fresh Water Fishes by Rev W. Houghton, illustrated by AF Lydon (Image: Rev. W. Houghton/A.F. Lydon/WikimediaÂ)

Fen fisherfolk knew them as pout eel, while around the Theford area, they were known as coney fish, as they were believed to spend much of their time hiding in holes in the bank.

“It is olive green, marbled boldly with black and a conspicuous feature is the long, pointed, beard-like tag which hangs down beneath its chin,” the EDP's renowned nature columnist Ted Ellis wrote in 1958.