Scientists at Cefas (the Centre for Environment, Fisheries & Aquaculture Science) have confirmed that crayfish plague (Aphanomyces astaci) has recently caused mass mortalities of Turkish crayfish (Astacus leptodactylus) in the River Waveney, between Bungay and Lowestoft in Suffolk. The Environment Agency sent samples to Cefas’ laboratory in Weymouth, Dorset, for analysis and the results were confirmed today.

Crayfish plague is caused by a pathogen that was first introduced into the UK by the North American signal crayfish. Commercial fish farmers brought the signal crayfish to England during the 1970s. While crayfish plague does not kill North American crayfish species that carry the infection, it is lethal to the UK’s native, white-clawed crayfish and other European species, such as the Turkish crayfish.

Cefas’ Dr Birgit Oidtmann, an internationally recognised expert on crayfish plague, said: “The most likely route of introduction of crayfish plague into the River Waveney is via the introduction of North American crayfish. In the past, there have been cases of deliberate introductions of North American crayfish into other river systems, but introductions may also occur by accidental co-transport of North American crayfish during stocking events. A less likely, but also possible, route is through contaminated fish, fishing gear, boats or other damp equipment.”

Cefas’ Dr Paul Stebbing, a crayfish specialist, said: “This particular outbreak is a mixed blessing: an invasive non-native species will now be removed, but a highly contagious disease may spread and infect native crayfish populations in nearby rivers.”

Crayfish plague poses no risk to humans, however it is easily transferred between waters and does affect native crayfish species. Anyone who has been working on, angling in or otherwise in contact with the River Waveney in the affected area during the outbreak should take precautions to ensure that all equipment that has been in contact with water is suitably cleaned and disinfected. For more about this see