Pest control hub
What does it look like?
Chinese mitten crabs are usualy light-brown to olive green shell, which reaches up to 10 cm across. Hairy 'mittens' on its front claws, which is a feature not shared by any native New Zealand crab or other introduced species of crab. These caws have white pincer tips. There are four spines or serrations present on each side of the shell and a distinct raised notch between eyes.
Chinese mitten crabs burrow into sand, mud or clay banks. Adult specimens inhabit the bottom and banks of freshwater rivers and tidal creeks, before migrating to brackish and saltwater to reproduce. Their larvae develop into juveniles in marine coastal areas, which then migrate back to rivers and creeks. Chinese mitten crabs are able to survive in highly polluted habitats.
Why is it a problem?
Burrowing by this species weakens banks and causes accelerated erosion. Damage to fishing nets and catch is also common. Where there are high densities of the species, water blockages can be an issue. This species also hosts liver fluke (Paragonimus sp.) that is harmful to human health.
The Chinese mitten crab is also a generalist feeder, having impacts on the freshwater and brackish environment where in high densities tends to cause an imbalance in the local ecosystem.
You can help prevent the spread of marine pests by:
• Regularly cleaning your boat’s hull – ideally keep fouling growth to no more than a light slime layer.
• Applying a thorough coating of antifouling paint and keep it in good condition.
• Ensure your hull is clean and free of fouling before you travel to a new area.
• Clean and dry any marine equipment (e.g. ropes, lines and pots) before using in a new area.
• Inspect areas on your boat that retain water for signs of marine life.
• Check for aquatic weeds tangled around anchors, trailers and other equipment.