'Sex traps' set to kill invasive crayfish

Scientists are using the pulling power of pioneering "sex traps" to lure invasive North American signal crayfish from British rivers. In an innovative research project, male American freshwater crayfish are being tricked into thinking they will have a good time if they enter underwater baskets. Once caught, however, they are humanely killed.

Scientists are using the pulling power of pioneering "sex traps" to lure invasive North American signal crayfish from British rivers. In an innovative research project, male American freshwater crayfish are being tricked into thinking they will have a good time if they enter underwater baskets. Once caught, however, they are humanely killed.

The seduction technique is based on the use of pheromones – the natural chemicals produced by crayfish – as a bait to attract a mate into the trap. The project, sponsored by the Environment Agency and English Nature, is seen as vital to protect endangered British crayfish from the more powerful American invaders.

The problem is that signal crayfish like it here. They were introduced to Britain in the 1970s to supply the restaurant trade, but some escaped into the wild and their colonies are spreading.

The American species is more aggressive, breeds at an earlier age and produces more eggs. As well as carrying a fungal disease which has wiped out a large number of crayfish, the signal is a threat to other species.