Barriers go up in bid to keep salmon river free of killer crayfish

The voracious North American signal crayfish, which feasts on salmon eggs and freshly hatched salmon, has already been found in the catchment of the River Clyde, where they are threatening to devastate stocks of the King of Fish, the Scotsman reports.

In a pioneering bid to prevent their spread in the south of Scotland, Scottish Natural Heritage has joined forces with Annan District Salmon Fisheries Board, the Clyde River Foundation and South Lanarkshire Council to install two dams 20 metres apart at a site close to where the headwaters of the rivers Clyde and Annan meet.

The invasive crustaceans were first seen in Scotland in 1995, in the catchment of the River Dee in Kirkcudbrightshire, and in the Clyde a year later, the newspaper said. Although the crayfish can move up river systems on their own, criminal gangs are stocking rivers with them before harvesting them for clandestine sales to restaurants. Once established in rivers, they are virtually impossible to eradicate.