- Have a hard external skeleton and two large pincers.
- Very similar in appearance to saltwater crayfish, but do not grow anywhere near as big.
- Two species of freshwater crayfish are currently recognised:
- Paranephrops zealandicus, found in the eastern and southern South Island, and classified as At Risk: Declining; and
- Paranephrops planifrons, found in the North Island and northern and western South Island, and classified as Not Threatened.
- Widespread throughout New Zealand, preferring pools and areas of slow or no flow.
- Live in streams, lakes and ponds, and even in wetlands.
- Shelter between stones on gravelly bottoms, but can burrow into muddy bottoms, and will burrow well down into wetlands to survive dry periods if needed.
- Tend to stay hidden during the day, moving around mostly at night.
- Eat a wide variety of food, mostly scavenging for invertebrates, leaves and other detritus.
- Are a valuable mahinga kai species.
Association with Plantations
- Can occur in plantation forestry areas.
- Plantation streams and lakes often have relatively high populations of indigenous species.
- Destruction of riparian vegetation.
- Disturbance of banks and beds of waterways.
- Habitat destruction from:
- Modification of riparian margins.
- Introduction of aquatic weeds.
- Eutrophication (high nutrients).
- Erosion of banks through grazing by livestock, goats and deer.
- Artificial barriers to upstream migration (e.g. culverts, fords with large lips creating a drop off).
- Depleted flows caused by water abstraction.
Management Options and Methods
- Maintain corridors of riparian vegetation along banks. Corridors should be as extensive as possible (refer to Buxton 1991).
- If possible, expand width of riparian zones during later rotation planting.
- Exclude livestock from riparian areas.
- Control deer and goats that could enter riparian areas.
- Comply with best forest operational management practices to avoid damage to riparian areas.
- Provide adequate passage through/over artificial barriers within streams, e.g. providing mussel spat ropes for them to climb up, or using other designs (refer Buxton 1991, Jowett 1999).
- Manage or prevent water abstraction from critical habitat areas.
- Regulate or prevent harvesting of threatened species.
- Prevent introductions of exotic fish.
- Prevent introductions of aquatic weeds. Educate local users of weed threats and how to prevent spread.
- Undertake surveys to identify presences of species and habitats.
- Consider repeating surveys every few years to ascertain whether key species are still present.
- Liaise with DOC about survey and monitoring methods.
- Report findings to DOC.
- Periodic checks of banks to ensure compliance with best forest operational management practices, pest and weed levels and siltation.
Further Information and Support
- DOC – advice for management, survey, and monitoring. Website http://www.doc.govt.nz/
- Whitmore, N., Huryn, A. D., Arbuckle, C. J., Jansma, F. 2000. Ecology and distribution of the freshwater crayfish Paranephrops zealandicus in Otago Implications for conservation. Science for Conservation 148. 42 p.
- Buxton 1991. New Zealand’s wetlands: a management guide. Wellington, Department of Conservation.
- Jowett I. et al. 1999. Fish passage at culverts: a review with possible solutions for New Zealand indigenous species.
- NIWA website. http://www.niwa.cri.nz