'Highly invasive' American crayfish in River Gaunless

A "highly invasive" alien species of crayfish has been discovered in a County Durham river.

The American signal crayfish had been found in the River Gaunless, a tributary of the River Wear, the Wear Rivers Trust (WRT) said.

They were "effectively eating machines" which would damage the river's ecosystem, it said.

Project officer Steve Hudson urged river users to check and dry equipment to stop them spreading.

"This could be very damaging for the watercourse," he said.

"The American signal crayfish have a ferocious appetite and also damage the river banks through burrowing.

"They could have made their way here in a multitude of ways, and it is difficult to pinpoint the source, whether it be flown in on birds or ducks, carried in on vehicles, via anglers' waders or canoeists' paddles."

The species came from America in 1976 and has become widespread, carrying a disease which is endangering the native white-clawed crayfish.