Killer shrimp in Britain

Thursday, October 4th, 2012

Last week The Environment Agency, Broads Authority and the Norfolk Non-native Species Initiative held a “Meet the Killer Shrimp” workshop, which ecologists from The Ecology Consultancy’s Norfolk office attended. The aim of the event was to increase awareness of the species, and to inform people on how to identify it and where to report suspected cases.

Dikerogammarus villosus aka killer shrimp is native to south-eastern Europe, but is highly invasive and has spread westwards through the continent in recent decades. The species was first found in Britain in 2010 in Cambridgeshire and then in the Norfolk Broads earlier this year.  The killer shrimp has been assessed as being the most dangerous non-native species in Britain due to its appetite for destruction. It is omnivorous but also has a nasty habit of shredding all forms of native aquatic life that it happens upon, often not eating them, and as such it quickly dominates aquatic habitats. In places where killer shrimp is the only remaining invertebrate species, it becomes cannibalistic.

The killer shrimp is generally larger than our native freshwater shrimps, although size varies with age: Most are 10-20mm from head to tail although they can grow up to 30mm. It also usually has a distinctly striped back. The truly diagnostic feature, however, is the presence of two distinctive cone-shaped protrusions on the back at the base of the tail.

It is an offence under Section 14 (1a) of the Wildlife & Countryside Act 1981 (as amended) to release or allow to escape any animal which is not ordinarily resident in and is not a visitor to Great Britain. As such,  good biosecurity is essential to reduce the risk of spreading this species which can be transferred on angling gear, boats, trailers and clothing. The Environment Agency recommends that anyone working in water should “Check, Clean and Dry” all equipment and clothing before moving to another waterbody. If you suspect you have found this species please send a record, including a photograph, to

With an in-house entomologist and specialists in aquatic ecology The Ecology Consultancy is ideally positioned to undertake assessments for this and other aquatic, invasive, or invertebrate species.

Alex Prendergast (Photo: Amy Buckenham)

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