Pollution ruins reintroduction programme
A programme to reintroduce a threatened species to a British waterway after it was decimated by pollution has been wrecked by second spill.
While perhaps not the most glamorous species in the UK’s rivers and streams, white-clawed crayfish play an important role in the ecosystem.
In the south of England that native crayfish has faced being wiped out by the triple threat of disease, pollution and displacement by the invasive, and much larger, American signal crayfish.
Cumbria has remained a stronghold for the species over the past 50 years but sheep dip contamination of waterways is now taking its toll.
At Mill Beck near Windermere more than 100 of the crayfish have been found dead, killed by insecticide, just a year after the Environment Agency restocked the waterway to help the recovery of the species after a previous spill.
Ecologists believe it will take the population years to recover from this second blow.
More than 100 threatened white-clawed crayfish have been killed from suspected sheep dip contamination of a stream in Cumbria, only a year after the Environment Agency restocked the waterway.
Ecologists believe it will take years for the native crayfish population in Mill Beck near Windermere to recover, only five years after a similar pollution incident in the stream almost wiped out the species.
“We had a major sheep dip pollution incident in 2000 which wiped out over one thousand of the crayfish,” said Brian Ingersent, EA ecologist. “And the remaining population wouldn’t have had the time to reach these kinds of numbers.”
“So unfortunately the majority of the crayfish killed this month would have been those from last years restocking.”
Mr Ingersent said while Mill Beck was free of the invasive signal crayfish, the impact of losing more than 100 of the native species – both adult and juvenile – would be another major setback for a waterway that has a sordid history of pollution incidents.
“The Environment Agency were very keen to safeguard the species and accepted 200 native crayfish for restocking last year after a nearby reservoir was partially lowered for maintenance work.
“But this was not a normal procedure and it may take years for the native crayfish to get back to the level they were only last month.”
Mr Ingersent said smaller tributaries that ran into Mill Beck had escaped the pollution that covered half a mile of the stream and he hoped some of the crayfish had survived in these side waters.
Environment Agency agricultural policy manager Rob Robinson said: “Less than one teaspoon of cypermethrin sheep dip can wipe out aquatic insect life for hundreds of metres and may ruin fishing.
“Farmers do need to take extra care when using and disposing of sheep dip.”
“The Environment Agency has been working with the Veterinary Medicines Directorate to develop a sheep dip Pollution Reduction Programme because we believe prompt action is needed to address this issue.
We consulted on the draft PRP at the beginning of 2006 and a range of organisations including regulators and associations representing farmers, anglers, veterinarians, manufacturers and wildlife interests responded to the consultation. We are presently revising the PRP to take on board comments received and will be publishing it later this summer.”
Farmers can find out more about using and disposing of sheep dip safely on the Environment Agency website.
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