EA uses radio transmitters to track virile crayfish

According to the agency, the highly aggressive non-native crayfish preys on native wildlife and spreads crayfish plague, which is deadly to native white clawed crayfish.

As a result, the EA is using small radio-transmitters installed on the backs of the virile crayfish to track their progress, with preliminary results showing upstream movement at a rate of 500 metres per month. This is substantially faster than their non-native cousin the signal crayfish, which wiped out the white clawed crayfish in the River Lee, Cheshunt in the 1980s.

Originally from North America, the spread of the virile crayfish is not effected by cold weather. The crayfish were first monitored on the River Lee near Enfield in 2004 and have since colonised more than 17 km of the river and connected waterways, spreading into Hertfordshire.

It is anticipated that monitoring work on the River Lee will provide the EA with a better understanding of the movement and lifecycle of the signal and virile crayfish, contributing to efforts to safeguard native white clawed crayfish elsewhere in the country.

EA environmental monitoring officer Adam Ellis, said: “Whilst rivers in England and Wales are cleaner than they have been for decades, there is still a lot to be done in order to return them to full health. This includes the control of invasive species like virile crayfish.

“By tracking the colonisation of the River Lee by virile crayfish, we will better understand how this species impacts the environment and our native wildlife. However, one of the most important ways to protect our wildlife is to stop the spread of non-native invasive species. We’re appealing to the public not to release unwanted pets into the wild.”

Invasive species cost the UK economy an estimated £1.7bn every year, with rising numbers causing a major challenge to tough new EU targets on the ecology of rivers and lakes.

Carys Matthews