India, Aug. 8 -- Last autumn around 100 native white clawed crayfish were found dead in the River Wansbeck catchment in Northumberland.

The subsequent investigation determined crayfish displaying similar symptoms - unusual orange patches on their shell - were widespread across the Wansbeck catchment as well as areas of the neighbouring rivers Tyne and Blyth catchments.

Now the Environment Agency is carrying out surveys across Northumberland and the North East through the summer to determine current populations of the native species.

The surveys will also be identifying locations where crayfish are displaying the unusual symptoms.

Intensive surveys on the Hart Burn, where the initial deaths were reported, as well as at some other sites...