New American signal crayfish populations in the Clyde catchment

We have had two reports of “new” populations of American signal crayfish in the River Clyde catchment this week, one of which we have confirmed and the other we will be investigating further. While these populations of the alien species could have been present for some time, this brings the total number of areas known to be infested in our catchment to five.  Signal crayfish are impossible to eradicate once established in rivers and because they are large, aggressive omnivores, they can drive ecological and environmental change. Non-native crayfish management is a very sensitive issue and it is currently illegal to trap or be in possession of live crayfish in Scotland without the appropriate licences. Removal of the large crayfish may actually make the impacts worse, not better and moving them around creates incentives for illegal trapping. The best management is to avoid transporting the animals to new locations and to that end, anglers and other water users should practice ‘Check, Clean, Dry‘ on their equipment.  We will be posting further updates from the Clyde, and some snippets from this week’s national Crayfish Conference that we attended shortly.