The Asian paddle crab is an aggressive predator that competes with native crabs for space and food. They prey on a wide range of native species, including shellfish, fish, other crustaceans, and polychaete worms, posing a significant threat to local marine ecosystems. These crabs reproduce rapidly, with females producing up to 85,000 eggs multiple times a year. The larvae can survive in varying water temperatures and salinities, allowing them to spread over large distances via tides and currents.

• Size: Adults have an upper shell that can reach up to 12 cm across.
• Appearance: They have paddle-like hind legs and six distinct spines on each side of the shell below the eyes. Each claw features five prominent spines on its upper surface. Their colour ranges from pale-green or olive-green to deep chestnut-brown with purplish markings.
• Shell Texture: The upper shell is often covered in small hairs, though these may not always be visible.
• Similar Species: They can be distinguished by their large size, paddle-like hind legs, and distinctive spines on the claws and shell.
• Habitat: In New Zealand, Asian paddle crabs are typically found in estuaries with firm sand, muddy fine sand, or muddy-shelly fine sand. In their native range in Southeast Asia, they inhabit inter-tidal and sub-tidal zones down to about 15 meters, including sandy, muddy, or rocky reefs.

Late spring to early autumn (October to March in the Southern Hemisphere). This period aligns with the warmer months when crabs are most active, feeding, and reproducing. Juveniles and adults are more mobile and visible in these months, making surveys more effective.

It is an offence to breed, knowingly communicate, exhibit, multiply, propagate, release, or sell, an unwanted organism (Biosecurity Act 1993).

ORC is currently developing a marine biosecurity programme and needs to obtain more information on species distributions before pursuing management options. If you think you have spotted Asian paddle crab, please let us know by calling 0800 474 082 or emailing biosecurity@orc.govt.nz

Preventing the spread of Asian paddle crab is the best strategy, as removal of invasive marine pests is both difficult and expensive.

Cleaning your craft and gear for biosecurity purposes is an important way to help protect the marine environment. Just as regular maintenance keeps your equipment in good condition, biosecurity cleaning keeps the ocean healthy for everyone.

The three main types of marine biosecurity cleaning for boaties are: