ZSEA Banham Zoological Gardens

Norfolk zoo celebrates commitment to conservation with the arrival of endangered native crayfish

Posted: 23rd May, 2022

Banham Zoological Gardens in Norfolk has announced the successful transfer of four female white-clawed crayfish to their on-site hatchery in collaboration with the Norfolk Rivers Trust.

White-clawed crayfish are a native species facing local extinction in Norfolk and are threatened by low survival rates in the wild. After rearing the young of these four females in captivity, Banham Zoo and the Norfolk Rivers Trust aim to later re-release them back into the wild.

Banham Zoological Gardens, which is run by the Zoological Society of East Anglia (ZSEA), was awarded a £95,300 grant from the Government’s Green Recovery Challenge Fund in 2021 to help boost nature recovery across Norfolk. The fund is a key part of the Prime Minister’s 10 Point Plan to kick-start nature recovery and tackle climate change, and has enabled the Norfolk zoo to build a hatchery to help protect the endangered white-clawed crayfish.

Staff from ZSEA and the Norfolk Rivers Trust travelled to North Norfolk to catch females carrying eggs (known as berried females), who were then carefully transported to Banham Zoo to be slowly acclimatised to the hatchery.  Once the eggs have hatched, the team will then begin the rearing process to ensure these young crayfish grow strong and healthy.

Sarah Lee, Head of Conservation at ZSEA, said: “This project is so important for the conservation of these incredible freshwater invertebrates – their numbers are falling dramatically and we must take action. The Norfolk Rivers Trust are doing everything they can to protect and save our native crayfish, and through our vital partnership, we are committed to saving this keystone species from local extinction in Norfolk with our on-site hatchery. We are so grateful to the Green Recovery Challenge Fund grant for enabling us to build this hatchery and continue our commitment to vital conservation work.

“The crayfish are doing well and are settling into the hatchery. Once their eggs have hatched, the young crayfish will need to grow to a suitable size before release, so they stand the best chance of survival back in the wild. Once they have been health checked they will be released into safe ‘ark’ sites where new populations can be safely established.”

The white-clawed crayfish is the UK’s only native freshwater crayfish which has declining population numbers in the wild due to the pressures of habitat loss, pollution, crayfish plague, and competition from invasive species such as the North American signal crayfish. Young crayfish are small and vulnerable to predators and disease with a survival rate of only around 5% in the wild. If reared in a hatchery, their survival rate can increase up to 90%.

The hatchery was completed in early 2022, with the majority of the build completed by Zooscapes Ltd. Once the hatchery staff were satisfied with the water chemistry, parameters and temperatures, the team travelled to Bristol to collect five crayfish: one male and four females, which had been reared by white-clawed crayfish expert Jen Nightingale, UK Conservation Manager for Bristol Zoo, to bring back to Banham Zoological Gardens.

Sarah Lee added: “Jen and her team have been our mentors and fantastic support throughout this whole process. We have been looking after these five crayfish for a number of weeks and they have been feeding well and have settled in brilliantly.

“With the arrival of the wild caught crayfish, these five will be moved to an on-show facility in the Discovery Centre for Conservation Education so our guests at the zoo can see the crayfish up close. We hope visitors will enjoy learning about this project and why it is vitally important for the conservation of this species.”

Ursula Juta, Education and Catchment Manager at the Norfolk Rivers Trust said: "The white-clawed crayfish is our largest freshwater invertebrate and while they are rapidly declining or extinct across the many parts of the UK, we are very fortunate to still have a few healthy populations in Norfolk. The Norfolk Rivers Trust and Norfolk Crayfish Group have been desperate to try and get a hatchery running for a few years to secure the future for the crayfish, and we are so thankful for the support of the Zoological Society of East Anglia.

“Managing the invasive signal crayfish and associated crayfish plague is our biggest challenge; the crayfish plague is highly likely to be carried on traps so stopping illegal crayfish trapping and informing and educating people is key to saving our native crayfish and the wider ecosystems."

To find out more about ZSEA’s conservation work, visit https://www.zsea.org/

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