By Rob Waugh Last updated at 1:12 PM on 30th December 2011 An aggressive species of crayfish which has been invading England's waterways is being tracked with radio transmitters in a bid to understand why they move so quickly - and help control their advance. The American predators have colonised the River Lee near Enfield, moving at more than 500m per month. The crayfish have now taken over 17km of the river. The Environment Agency said virile crayfish, which are non-native, prey on native wildlife and spread crayfish plague, a disease deadly to native white-clawed crayfish. It is believed that virile crayfish arrived in the UK after an aquarium owner released them into an east London pond.
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Predatory American crayfish take over river in Enfield
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Moving at a rate of 500m per month
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Eat native wildlife and spread lethal crayfish plague
The predatory North American crayfish are believed to have escaped an aquarium in @placeholder before colonising a river.