There are tens of thousands of white-clayed crayfish in the River Eden
A campaign to preserve a species of crayfish has been launched in Cumbria.
It is feared the native white-clayed variety could be wiped out from of one of its last strongholds, the River Eden.
It is under threat from the much larger American signal crayfish, which carries crayfish plague which kills the white variety of the species.
The Environment Agency is urging anglers to disinfect their tackle to stop the spread of the disease.
It is also urging members of the public not to pick up crayfish and try to move them.
The white-clayed variety is protected by law and cannot be fished or eaten.
John Shatwell, environment manager for the Agency in Penrith, said: "Although the signal crayfish is much bigger and stronger than the white-clayed variety, people still get them confused and try and move them if they see them, thinking they are protecting them.
"Their intentions may be good but they are being naive and may be moving the wrong variety and messing with the ecology of the waters. Also they pinch so it is best not to touch them."
He said the River Eden contained tens of thousands of the under-threat species and the Agency did not want the population to fall to dangerous levels.