Crucial work is going on at Wild Place Project as part of a project to save one of the most endangered native species in the UK: the white-clawed crayfish.
More than 30 of the tiny captive-born creatures have been released into an historic pond, deep in the woods at the zoo.
Its exact location is being kept under wraps to ensure the crayfish can live undisturbed and hopefully breed successfully.
This is the latest step in a programme involving experts from Bristol Zoological Society which began more than 10 years ago.
Neil Green, UK Biosecurity Conservation Officer with Bristol Zoological Society, said: “The pond has been there for more than 100 years and was once used to wash the wheels from horse-drawn carriages.”
It took a mechanical digger and a team of environmentalists, including 10 volunteers, two years to clear the pond which was full of mud, fallen branches, old wheels, tyres and a lorry load of litter.
The pond, which is around the size of a tennis court, was then left to refill with rain water before it was replanted. Around 100 small plastic pipes were then added to mimic natural refuges in which crayfish live.
Once the habitat and water quality were acceptable, 34 captive-born, white-clawed crayfish, aged between two and four years old, were released.
Neil said: “We are hoping that the majority of them will survive because they are free of the pressures and predators that would be found in a river.”
It is hoped the crayfish will breed in the pond, which will then provide a source of crayfish from which additional ark sites can be established. This will help bolster the dwindling numbers of white-clawed crayfish, which are at risk of becoming extinct in Britain within 20 years.
The white-clawed crayfish are under threat of extinction due to the spread of invasive North American signal crayfish, which compete for food and habitat and carry crayfish plague - a disease which is deadly to white-clawed crayfish.
As a result, they have suffered a 70 per cent decline in numbers in the south-west of England.
Neil said: “White-clawed crayfish are important, they are the UK’s only native crayfish and they are like a barometer because if they are healthy then the rest of the ecosystem around them will be in good shape.”
The white-clawed crayfish were bred and reared at Bristol Zoo Gardens and at Bristol Water’s fishery at Ubley, near Blagdon in Somerset.
The ark site at Wild Place Project is part of Bristol Zoological Society’s active white-clawed crayfish captive-breeding and reintroduction programme. Over the past two years, two additional crayfish ark sites have been established in Somerset, which are home to over 280 of the species.
Future ark sites are also being planned, whilst the team continues to monitor and manage the ark sites they have established so far.
More than 5,000 white-clawed crayfish have been hatched and reared by Bristol Zoological Society since 2008.
Bristol Zoological Society’s white-clawed crayfish conservation project is supported by Enovert and Bristol Water.
To find out more about Bristol Zoological Society’s conservation projects, visit our conservation page.
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