Collaborating for crayfish: successful crayfish release in Yorkshire with Flamingo Land

2025 has been a monumental year for Flamingo Land and the Yorkshire Crayfish Hatchery as they reach a major milestone in the 'Claws for Thought' project – a collaborative effort under the Yorkshire Crayfish Forum.

Building on the essential first stage of the project, which focused on developing husbandry skills through the care of captive-bred crayfish, the team has now advanced to working with wild individuals from North Yorkshire. The hatchery was established in response to the dramatic decline of the white-clawed crayfish, one of the UK’s most endangered freshwater species, due to habitat loss, pollution, and the spread of the invasive signal crayfish.

In March 2025, 35 captive-reared crayfish – 4 adults from Northumberland and 31 yearlings from Wingham Wildlife Park, all originally bred at Bristol Zoo – were transported back to their place of origin near Bristol and released into the wild. This marked the first of many planned releases. Following this, the hatchery underwent a complete deep clean to prepare it for the next vital stage: housing wild adult females carrying eggs.

In May, the project progressed further when 16 berried (egg-carrying) females and 10 males were collected from an at-risk population in North Yorkshire. With support from the Environment Agency and Yorkshire Wildlife Trust, these crayfish were transferred to the hatchery. This dual approach allowed the females to hatch their eggs in a safe, controlled environment, while also giving the vulnerable males time to moult and recover before being released into a specially designated Ark site within the same river catchment, discovered and chosen by colleagues at the Yorkshire Wildlife Trust.

Vanessa Barlow, Crayfish Project Officer at Yorkshire Wildlife Trust, says, “Creating ark sites is a vital part of crayfish conservation in the UK, and a key objective of the Yorkshire Crayfish Forum in providing a safe refuge for native crayfish populations. Identifying suitable locations can be an extensive process, because crayfish require specific conditions to thrive including appropriate levels of calcium for their exoskeleton.

“It is vital that the ark site is isolated to prevent the threat of invasive crayfish invasion, so we are very happy with this site. A large waterfall acts as a barrier to any possible upstream movement of signal crayfish in the future, and it also has plenty of good habitat, such as rocks and cobbles and vegetation, which the crayfish will hide under during the day. We are very hopeful that this programme and this ark site will have huge benefits for Yorkshire’s native white-clawed crayfish population.”

By June, the first eggs began to hatch. The team carefully monitored the females as they carried their hatchlings, which cling to the mother’s underside during their earliest stage of life. The young remain dependent until they moult, develop mouthparts, and begin swimming independently.

In July, once the juveniles had left their mothers, the adult females were transferred to a separate tank and provided with plenty of food to help them recover and moult. By late July, both the adult males and females were released into the Ark site, taking the total number of released crayfish to over 50 in the hatchery’s very first operational year.

Ryan Stringer, Team Leader of the Keeper Team Caring for the Crayfish, says: “The Crayfish Hatchery has been an exciting project to be a part of for myself and the rest of the keeping team involved. From the early stages of constructing the facilities to now having the juvenile crayfish being raised for release there has been a monumental amount of work and effort put in by all to get to this stage and the reward of being able to release hundreds of endangered crayfish back into the yorkshire waters is an amazing project to be involved in. From starting as an ectotherms keeper at Flamingo Land I never expected to spend a vast chunk of my day caring for native crayfish but the journey has been extremely rewarding and we have learnt a lot throughout which will hopefully be the foundations for further exciting conservation projects in the future."

But the real work begins now. The team estimates there are at least 200 young crayfish currently being raised at the hatchery. Over the next 12–18 months, they will be monitored closely to ensure healthy growth and development, with the ultimate aim of releasing them in 2026. In the wild, only around 5% of crayfish typically survive to adulthood, but with expert care in the hatchery, the team hopes to boost that figure to an incredible 95%.

“Joining the Yorkshire Crayfish Forum and creating this hatchery has had an enormous impact for us here at Flamingo Land and has really secured our first steps into being a conservation powerhouse,” says Kieran Holliday, Science and Conservation Officer at Flamingo Land. “These recent steps forward for the hatchery have really started to make this project feel real to the team. The keepers have done an exceptional job of caring for the adults and the juveniles are doing well and growing as expected, and we can’t wait for the releases next year.”