THE American signal crayfish has been grabbing headlines again after being found in the River Ettrick, a main tributary of the Tweed.
Unfortunately, the threat of this invasive species is nothing new. It was introduced into England in the mid-1970s to farm for the table and has since established itself in the wild on many southern rivers, where it has wiped out the smaller native white-clawed crayfish.
In Scotland we have no indigenous crayfish but signal crayfish, which grow to over 20cm, are omnivores and can prey on small fish and fish eggs. They also reach high densities per square metre and can bury hard, leading to unstable riverbanks and damage to salmon and trout spawning grounds.
At the start of this year it emerged that colonies were present in the Dee in Kirkudbrightshire and the River Clyde and, indeed, that work had been ongoing for almost five years by the United Clyde Angling Protective Association to try and eradicate them from a section of the Lanarkshire water.
The fact they have now found their way into as rich a salmon spawning area of the Tweed system as the Ettrick is obviously very bad news.
I personally have not came up against these critters but I believe they are being introduced so that people can sell them. I was reading another article in the Herald the other day that was saying the the bailifs on Loch Lomond were stopping people from trying to stock Barbel into the Loch.
Barbel into Loch Lomond
Loch Lomond: Anglers treading a dangerous line
FISHERMEN have been caught deliberately trying to introduce foreign species of fish into Loch Lomond, despite repeated warnings of the damage they do to rare native species.
Water bailiffs around the loch have twice caught fishermen with containers of live barbel, which can grow up to 20lb and which feed on eggs of other fish.