Alien crab heading further north

Jonathan Hart-Woods, environment manager for British Waterways, said: "Mitten Crabs are not unusual but to find them this far North on British Waterways' navigations is a first. This is sure to be one of many as this is a very resilient and invasive species, which can travel great distances.

"It is an offence to put the crab back in the water so we will have to find a means of dispatching it humanely."

Invasions by non-native species – like Chinese mitten crabs, which have been reported in the Humber since 1976 – are a cause for concern. They can increase erosion as they burrow into flood defences.

Other species like Himalayan balsam and Japanese knotweed quickly drive out native vegetation.