An invasive species of shrimp, commonly known as the ‘killer shrimp’ has been found at Grafham Water reservoir in Cambridgeshire. This is the first time the shrimp has been found in this country.
Two keen-eyed anglers spotted the unusual shrimp on Friday 3 September and sent samples to the Environment Agency for identification. Once the shrimp was identified as possibly being Dikerogammarus villosus, the Environment Agency worked quickly with Anglian Water to put precautionary biosecurity measures in place.
The shrimp is a voracious predator (hence its common name of ‘killer shrimp’). It kills a range of native species, such as freshwater invertebrates, particularly native shrimps and even young fish. This alters the ecology of the habitats it invades. It often kills its prey and leaves it uneaten. It tends to dominate the habitat, sometimes causing the extinction of native species.
Insects such as damselflies and water boatmen, common sights on British lakes and rivers, could be at risk, with knock-on effects on the species which feed on them.
It has spread across most of Western Europe over the last 10 years. It can be as small as 3mm but may grow up to 30mm long, much larger than our native freshwater shrimp.
An expert in Holland has conclusively identified the species.
Defra Minister, Richard Benyon said: ‘I am extremely concerned to hear that this highly invasive species has been found in Britain. Anglian Water has acted quickly to put biosecurity measures in place and the Environment Agency is working hard to establish the extent of the problem and what action may need to be taken. We need to do everything we can to protect our native wildlife and young fish from the potential damage the killer shrimp can cause.’
Expert biologists are currently testing water entering and leaving Grafham to see if the shrimp can be found in it. The results from this will indicate how widespread the problem might be and what measures need to be taken.
The shrimp could have arrived at Grafham in a variety of ways, including boating, angling, fish-stocking or naturally via birds.
Dr Paul Leinster, Chief Executive of the Environment Agency, said: ‘We are devastated that this shrimp has been found in Britain, and very grateful to the keen-eyed anglers who found it. We are currently establishing the degree of the problem, and whether the shrimp is only in Grafham Water or if it is in nearby lakes and the Great Ouse as well.’
Ciaran Nelson from Anglian Water said: ‘We have put precautionary biosecurity measures in place around Grafham Water as containing the shrimp is of paramount importance. We are also assisting with investigations to establish if it is already more widespread. The presence of this species poses no risk to the quality of drinking water supplies.
‘We are asking all water users at Grafham to take the actions asked of them on-site. This includes checking their equipment for shrimp when they leave the water and removing any that they find. They should also ensure their equipment is thoroughly cleaned and dried before it is put into any other water. Subject to these controls, recreational activities on the reservoir can continue.’
Water users from Grafham wanting more information on the measures they should take can contact Anglian Water on: 08457 91 91 55, or via www.anglianwater.co.uk.
If you think you have seen an unusual shrimp, please email a photograph to firstname.lastname@example.org for identification.
For further information, go to http://www.riverflies.org/index/Killer_shrimp_alert.html for identification.