The white-clawed crayfish is one of our largest native freshwater invertebrates and needs particular minerals to grow and fortify its hard, outer protective layer (its exoskeleton that covers its body), the same way we need calcium to enrich our bones.

This omnivorous crustacean prefers to spend the day hidden underneath stones and rocks, and in small crevices, from which it emerges to forage for food including invertebrates, carrion, water plants and dead organic matter.

White-clawed crayfish were once widespread and common throughout England and Wales, but since the 1970s they have suffered a dramatic decline. This alarming loss in the UK is primarily due to competition and predation from a larger invasive non-native crayfish species from North America, the signal crayfish Pacifastacus leniusculus, which carries a deadly crayfish plague which can quickly wipe out our native species.

Hampshire & Isle of Wight Wildlife Trust is at the forefront of helping to secure its long-term survival. The Trust’s Southern Chalkstreams Project helps protect and restore the fragile freshwater ecosystems, which the endangered white-clawed crayfish, as well as other native species, depend on.

A significant milestone in safeguarding the species is the recent opening of a crayfish Breeding Centre, as part of a new Native Species Zone, at Marwell Zoo. This centre will play a vital role in strengthening the species’ status in the wild. It provides a biosecure environment where crayfish can be reared before being released into protected ‘ark sites’ in Hampshire, establishing new populations. These specially monitored locations offer a safe haven where they can thrive.

Furthermore, it is intended that crayfish will be released within the river catchments from which their parents were collected, increasing the strength and resilience of our existing populations in Hampshire.

The new centre builds on more than a decade of conservation work carried out by Hampshire & Isle of Wight Wildlife Trust in partnership with Bristol Zoological Society, which has been rearing white-clawed crayfish of Hampshire origin at its hatchery since 2013. Since then, nearly 2,000 of these captive born white-clawed crayfish have been released into the wild.

It also complements the Trust’s partnership work with the Wildheart Trust on the Isle of Wight, who established a Crayfish Conservation Centre at their Wildheart Animal Sanctuary site in 2024.