Water snails, crabs, shellfish, starfish, and other aquatic
Pyura stolonifera praeputialis
This species is present in New Zealand. It has been detected growing on rocks in a number of locations in the far north of Northland.
Page last updated: 27 June 2011
Charybdis japonica
This pest is in New Zealand. It is widespread in the Hauraki Gulf and has been detected in small numbers in Whangarei Harbour.
If you suspect you have found this crab in any other location in New Zealand, report it to: 0800 80 99 66.
If you are the owner/operator of a moored vessel, you can help prevent the spread of this marine pest by ensuring your boat’s hull is clean and well antifouled.
Description
The Asian paddle crab (Charybdis japonica) is a swimming crab native to South East Asia. It is normally found in the waters of Japan, Korea and Malaysia. It is typically found in estuaries where there is firm sand or muddy fine sand.
Charybdis japonica is a relatively large crab with paddle-like hind legs. Adults have a shell width of around 12cm. The adults also have six distinct spines or spikes on each side of the eyes.
The crabs range in colour from pale green through olive green, to a deep chestnut brown with purplish markings on the carapace (shell). Most of the crabs found in the Waitemata tend to have yellow-orange and brown-orange markings on the shell and legs. They have white tips on the claws.
Impact
This aggressive crab has the potential to compete with native crabs for space and food. It is a potential threat to marine farming as it preys on shellfish and other aquaculture species. It is also known for its aggressive temperament and can inflict a vicious bite if disturbed.
It is not, however, reported to be a pest in its native habitat or in other countries.
It was first reported in New Zealand in Auckland in late 2000. It is now widespread in the Waitemata Harbour and wider Hauraki Gulf. A single specimen was found in Whangarei Harbour in 2003 and in 2009, two further specimens have been found in this harbour.
How the paddle crab spreads
Adult paddle crabs can produce hundreds of thousands of offspring. The larvae can float in the water for three to four weeks, during which time they can be moved large distances by tides and currents. Adults are also capable of swimming large distances.
Human activities associated with boating, shipping, fishing and marine farming could increase its rate and distance of spread – either as a hitchhiking pest on a dirty boat bottom or marine equipment, or as larvae in ballast water or bait tanks.
How you can prevent its spread
Operators of ships, barges, yachts and other moored vessels should:
- Keep the hull clean and antifouling paint in good condition.
- Carry out cleaning in a facility that captures all removed material and disposes of it away from the sea.
- Avoid uptake of ballast water from the north eastern North Island coastal region – especially in spring/summer when crab larvae are likely to be present. If uptake is necessary, avoid discharging into other coastal areas.
Commercial fishers
- Keep nets and traps clean and flush live bait tanks, bait buckets and containers with freshwater before moving between sites.
- Avoid moving seawater in bait tanks from the north eastern North Island coastal region.
Marine farmers
- Ensure stock and equipment being transferred to other sites is free from unwanted hitchhikers.
- Freshwater wash or thoroughly air dry equipment before moving it to new areas.
Recreational fishers and divers
- Check your boat and gear for unwanted hitchhikers.
- Do not move water from the north eastern North Island coast to other areas.
- Keep nets clean and flush bait buckets and containers with freshwater before moving sites.
- Rinse your dive gear with freshwater after use.
Page last updated: 30 March 2009
Perna perna
South African Brown Mussel
Photos: A. Hosie, NIWA
This pest was detected on an oil rig in New Zealand waters in 2007. MAFBNZ actions have, however, reduced the likelihood of its successful establishment in New Zealand to negligible.
Historical background
An oil rig was defouled (had fouling organisms removed from its below-water surfaces) in Tasman Bay in December 2007.
It was later determined that Perna perna had been present on the oil rig at the time of its defouling. MAFBNZ initiated a response to this detection and in early March 2008 dredged the drop zone beneath the rig defouling sites. Debris from the seabed was removed and disposed of in a landfill. Any suspected Perna perna were removed, and the risk of the species establishing in New Zealand was greatly reduced.
What you can do
Marine farmers in the top of the South Island (Golden and Tasman Bays, Marlborough/Nelson) can keep a close eye on mussel lines and spat gathering areas.
Report any mussels or spat of concern to: 0800 80 99 66
Description
Perna perna is an edible bivalve mollusc belonging to the Mytilidae family. It is native to the tropical and sub-tropical regions of the Atlantic Ocean. It is found in waters off the west coast of Africa and the coast of South America up to the Caribbean.
It is generally a brown/brown-yellow colour and is sometime tinged with green around the margins. It grows to approximately 90 mm long, although can reach sizes of up to 120 mm.
Illustration of left valves from specimens of mussels showing Perna perna and other mussel species found in Tasman Bay
- A. Blue mussel Mytilus sp.from Tasman Bay
- B. Green lipped mussel Perna canaliculus from Tasman Bay
- C. Native green lipped mussel Perna canaliculus collected from Ocean Patriot rig in Taranaki
- D. Perna perna dredged up from defouling site in from Tasman Bay
- E. Perna perna collected from Port Elizabeth, South Africa
- F. Native bearded mussel Modiolus areolatus (without beard) collected from Tasman Bay.
Apart from the colouration, another distinguishing feature is that Perna perna appears to have a straighter and proportionately longer hinge line in comparison to the total length of the shell than the native green lipped mussel. (see illustration below showing hinge line)
- A. Green lipped mussel Perna canaliculus
- B/C. South African brown mussel Perna perna
The blue mussel (Mytilus sp.) may occasionally appear similar to Perna perna due to naturally occurring colour variation. One way to distinguish the genus Mytilus from the genus Perna is by looking at the muscle scar pattern inside the shell. Perna has a divided posterior adductor muscle, giving the appearance of two muscle scars whereas in Mytilus the scar is continuous (see illustralion below).
- A. Perna perna
- B. Mytilus sp
Impact
In its native range (South Africa) Perna perna is competitively inferior, being out competed by the European mussel (a Mytilus species), as it is not as resistant to human disturbance (such as harvesting activities) and certain parasites.
It is, however, an invasive species in the Gulf of Mexico and has the potential to be an invasive species in New Zealand. It naturally colonises rocky shores but can also attach to submerged man-made structures, and if it establishes in the Tasman Bay area, could pose a threat to the marine farming industry in the top of the South Island by competing with farmed green lipped mussels. The brown mussel is listed on a world database of invasive species, although it's not known how it would perform in the New Zealand environment.
Habitat and spread
At the site in Tasman Bay where the oil rig was defouled, extensive dredging has collected a very small number of Perna perna, which indicates that the numbers of Perna perna originally on the oil rig was low.
MAFBNZ does not know of any populations of the brown mussel in New Zealand. The only mussels are in the area that has been dredged. If no other populations exist, and the dredging operation removed most of the Perna perna present, then the chance of successful establishment in New Zealand is considered extremely low.
Perna perna prefers rocky shores and grows in the intertidal and shallow subtidal areas. It does not do well in sandy-bottomed areas. It can, however, survive on sand at depths where current movement is weak.
It is not known how Perna perna would perform in New Zealand. The adult brown mussel can tolerate a temperature range of 10 to 30°C and a salinity range of about 15 to 50 ppt. Perna perna does not develop from larvae into spat (baby mussels) at temperatures below 18°C. This indicates that populations in New Zealand may only establish in warmer areas such as the top of the South Island and warmer parts of the North Island.
The mussel uses external fertilisation during its spawning season over the summer months. The two sexes release eggs and sperm to the water during spawning to produce larvae. Fifteen hours after fertilisation the larvae have well-developed hinge teeth and 10-12 days after fertilisation the larvae settle on rocky surfaces. The larvae can travel up to 20km in ocean currents.
Keep boats and equipment clean
As well as the natural spread detailed above, this pest can spread easily on fouled hulls of vessels, aquaculture and other marine equipment, and in ballast water.
Its human-assisted spread can be prevented by:
- ensuring vessel hulls and marine equipment are free of fouling, and regularly treated with antifouling paint
- regularly cleaning hulls in a facility with collection and land-based disposal of fouling material
- minimising the movement of excessively fouled structures from one location to another.
Some useful resources
Further information on Perna perna can be found at:
Media
- Dredging for pest mussels complete in Tasman Bay 20 May 2008
- Good progress on biosecurity mussel dredging in Tasman Bay 14 March 2008
- Ocean floor cleaned as part of Tasman Bay biosecurity operation 27 February 2008
Page last updated: 28 October 2008
Page last updated: 5 November 2008
Abalone Virus Ganglioneuritis
This abalone disease is currently prevalent in abalone populations on the Victorian coast in Australia, where it is having a severe impact on the abalone industry.
AVG is not currently present in New Zealand.
Because a number of different abalone species are affected in Australia, it is suspected that New Zealand's native päua could become infected, should the virus be transferred here.
If you suspect you have seen this virus in New Zealand paua, call 0800 80 99 66.
Symptoms
Abalone Virus Ganglioneuritis (AVG) is a herpes-like virus affecting black and green lip abalone populations in Australia.
AVG causes inflammation of the shellfish's nervous tissue, resulting in the edges of the foot curling inwards, swelling and protrusion of the mouth and excess mucous production.
Active signs of viral infection include animals losing muscle control and sliding or falling off their usual locations or surfaces. In an infected environment, intact dead abalone or shiny empty shells are found on beaches.
Impact
AVG has severe impacts on the abalone industry. Stock abundance surveys in Australia have suggested declines in affected populations of between 40 - 95 percent. In February 2007, abalone divers in south west Victoria were forecasting a $5 million loss in this season's earnings as a result of the virus. Both mandatory and voluntary closures of areas of coastline to commercial and/or recreational harvest have been imposed. The virus has the potential to severely impact New Zealand's päua industry.
Spread
This virus is not currently present in New Zealand. It is, however, spread along almost 200km of Australia's Victorian state coastline and infection has been found close to the Victorian border with South Australia.
Management
MAF Biosecurity New Zealand has measures in place at the border aimed at preventing the introduction of this virus to New Zealand abalone/paua stocks.
Various Import Health Standards are in place to mitigate risk in this area. Live abalone (Haliotis spp.) is not eligible for importation into New Zealand because it is not eligible under any IHS. The Import Health Standard for Ornamental Fish and Marine Invertebrates from all Countries lists species of marine fish and invertebrates (other than abalone) that are eligible for importation into New Zealand. All consignments of fish and marine invertebrates that are eligible under this standard are required to go through quarantine before they maybe given Biosecurity Clearance. All marine fish and invertebrates are quarantined for a minimum of three weeks.
All marine shells and shell ornaments (including abalone/paua) may be given biosecurity clearance provided that they are dry and non-viable as per the IHS for the Importation into New Zealand of Ornamental Animal Products. This also applies to all Australian abalone shell products. Abalone products for human consumption need to be shelled and cooked as per the IHS for Marine fisheries products for human consumption.
Used equipment associated with marine aquatic animals or marine water activities from any country can only be given biosecurity clearance provided that equipment is visibly clean and completely dry on arrival into New Zealand (IHS for Equipment Associated with Animals and Water). Particular attention is paid to equipment associated with aquaculture. Where equipment is not clean and dry it is treated by inspectors to remove possible disease organisms such as AVG.
MAF Biosecurity New Zealand has a highly trained group of Risk Screeners in place at our border to stop any goods posing a risk of transmitting this virus from entering New Zealand. The situation is being continuously monitored and analysed.
Useful Resources
- Paua AVG Virus Factsheet
(115 KB) - A review of the Abalone Virus Ganglioneuritis (AVG) (466 KB) - November 2007, Julie Hills
Media Releases
Page last updated: 20 June 2008
Eudistoma elongatum
This marine pest is established in Northland.
Photo: Hugh Blomfield
Page last updated: 12 November 2010
Asterias amurensis
If this seastar arrives in New Zealand it could have a serious impact on our aquaculture industry and our marine environment generally. The Northern Pacific Seastar is currently found in huge numbers in two areas of Australia (Derwent Estuary in Tasmania and Port Philip Bay, Melbourne).
It feeds on wild and farmed shellfish and a wide variety of other marine animals. It is normally found in shallow water but can be found from the intertidal area through to the subtidal as deep as 200 m. It can be found on muddy, sandy, pebbly seabeds as well as on rocks and man-made surfaces, even mussel lines. You would not normally see it in areas with high wave action.
Mode of distribution
Northern Pacific Seastars could reach New Zealand in ships’ ballast tanks (as the free swimming larvae) in ships’ water intakes or among other marine fouling on the outside of ship or yacht hulls particularly around the propeller or rudder area.
Description
Key features: Northern Pacific Seastar has five arms which have pointed and often up-turned tips. The arms join onto a central disc and are covered by clumps of small chisel-like spines.
Size: 10 cm diameter, individual arm length can be 40-60 mm.
Colour: Yellow and/or purple to red.
Topside: Arms covered with numerous unevenly arranged small spines with jagged ends.
Underside: On each arm the spines are in a single line either side of the groove where tube feet lie.
Information about Northern Pacific Sea Star
- Fact Sheet (173 KB)
Public Advertising
Click image to view the advertisement in PDF format.
Information on viewing PDF files
(830 KB)
Page last updated: 22 October 2008
Didemnum vexillum
This pest is established in New Zealand in the Marlborough Sounds and in Whangamata and Tauranga. Efforts are being made to manage it in Marlborough.
Page last updated: 27 October 2010
Cherax tenuimanus
All known populations of this organism in New Zealand have been eradicated, however, other unknown populations may still exist.
Report any sightings to hotline, phone 0800 809 966.
Page last updated: 12 August 2010
Styela clava
This pest is established in certain locations in New Zealand. It is an unwanted organism.
Page last updated: 15 November 2011
Potamocorbula amurensis
This species is NOT in New Zealand.
Report any sightings to ph 0800 809 966
General information
Asian clam is a shellfish with a distinctive uneven overbite and found in estuaries and brackish waters. It is 2-3cm across and the shell is a dirty white, yellow or tan colour.It can live in fresh and salt water and consumes large amounts of phyto- and zooplankton, so can substantially change any marine community. It is native to Japan, Korea and China, though has now invaded parts of the west coast of the United States.
Young clams can be caught up in a ship's ballast water while adults can attach to fishing equipment.
Management
- Action Plan
from Biodiversity web site
Fact Sheet (98 KB)
Useful Resources
Public Advertising
Click image to view the advertisement in PDF format.
Information on viewing PDF files
(830 KB)Page last updated: 18 June 2008
