America Exports Invasive Crayfish

December 12, 2004 By: Marshall Cutchin

Looks like here in the U.S. we’ve managed to export our own invasive species: the signal crayfish. Colonies have been found in the River Ettrick, a main tributary of the Tweed. “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.” On Scotsman.com.