The salmon fishing industry worth £18m a year on the River Tweed is under renewed threat from a major predator.
The American crayfish has been discovered in the River Till
American signal crayfish have been found in the River Till - a tributary which joins the Tweed near Coldstream.
Nick Yonge of the Tweed Foundation said the discovery of 24 crayfish, which eat young salmon and disturb their natural habitat, was a major blow.
Last year the crayfish were discovered in other tributaries at the Ettrick Water and Leithen Water.
It is not yet clear how much damage the crayfish have caused or how they got into the tributary.