New Zealand screwshell (Maoricolpus roseus)
Introduction
The New Zealand screw shell has a hard, smooth conical shell up to 9cm in length. It is a native New Zealand species that can survive in a range of different habitats, and has established successful populations in New South Wales, Victoria and Tasmania.
It forms a dense covering on the sea floor with live and dead shells at depths up to 100m, and competes with native shellfish for food.
Identification
Photo: CSIRO
Photo: CSIRO
Key features
- Smooth spiralled cone (no beads) up to 9cm long
- Yellow/red-brown in colour, often marbled or streaked
Known locations
- Twofold Bay and continental shelf off Merimbula and Bermagui
- Vic and Tas
Habitat
- Lying on, or partially buried in sand, mud or gravel
- Intertidal to subtidal
- From 1-130m depth
Impacts
- Densely blankets sea floor with live and dead shells
- Can affect growth of scallops and displace native shellfish
Similar native species
These native species may be confused with this marine pest.
Photo: Patty Jansen, Australain Shells
Velacumantus australis
Key features:
- Broader, rough spiralled shell up to 2-5cm long
- Dull grey colour
- Soft sediments in sheltered waters, estuaries, mangroves, tidal flats, seagrasses
Photo: Holly Barlow, Australian Museum
Gazameda gunnii
Key Features:
- Shorter shell, up to 5-6cm long
- More mottled appearance, lighter colouration - white/light brown
- Has fine beads forming ridges around the shell
Habitat:
- Inner continental shelf at depths to 140m
Photo: Patty Jansen, Australian Shells
Pyrazus ebeninus
Key features:
- Dark brown shell with flaring lip
- Up to 11cm long
Habitat:
- Mudflats and mangrove swamps in esturies
How can you help?
Learn to recognise, and be aware of, the New Zealand screwshell so that you can report any suspected new sighting.
Report any suspected new sightings on the 24 hour recorded hotline: 02 4916 3877 or email aquatic.pests@industry.nsw.gov.au.
If you see this pest in NSW, please report it immediately
- Note the exact location
- If possible take a photo and/or collect a sample
- Freeze sample in a plastic bag
- Report your sighting