When you move from one part of the river to another or from one river or lake to another – Check, Clean, and Dry watercraft, gear, or clothing that has come into contact with river water.
Note, procedures to manage human spread of Corbicula fluminea will also manage other freshwater pest species.
You must Check, Clean, Dry before moving:
Allow gear to dry to touch, inside and out, then leave it to dry for at least 48 hours (2 days) before using again.
Dry areas inside the watercraft where water has pooled, for example with an old towel, and then leave the craft to dry for at least 48 hours (2 days). The hull of a watercraft will dry when towed.
|
Type of treatment |
Method |
|---|---|
|
Hot water |
Above 60°C for at least 1 minute, or Between 50 to 54°C (hot household tap-water) for at least 5 minutes, or Above 45°C for at least 20 minutes. |
|
Freezing |
Until solid (that is, freeze overnight). |
Other treatment options |
|
|
Type of treatment |
Method |
|
Bleach |
Mix household bleach in a 10% (1 in 10) ratio with water and immerse for 1 hour. |
|
Isopropyl alcohol |
70% isopropyl alcohol, taking care as it is toxic and flammable, and there are requirements around storage and transport of isopropyl alcohol. |
Note, the 'Check, Clean, Dry' advice may be adjusted as further technical information becomes available or the need arises. Refer to the manufacturer’s instructions for gear and any commercial treatments.
The freshwater gold clam is native to eastern Asia and is widely established in North and South America and Europe.
These clams reproduce rapidly and form large populations that can clog water-based infrastructure such as electricity generation plants, irrigation systems, and water treatment plants. They are filter feeders that can potentially compete with native species for food. We do not yet know how this species will respond in New Zealand conditions.
Overseas, this clam has proved difficult to control and eradication has never been achieved.
The response to the freshwater gold clam incursion in the Waikato River was informed by the scientific and technical expertise of a Technical Advisory Group (TAG).
On the TAG were national and international scientists with extensive experience in freshwater invasion ecology, mollusc control and experience with Corbicula.
Representatives from Waikato iwi brought important local knowledge and perspectives.
The expert scientific and technical knowledge from the TAG provides a foundation on which future decisions about the management of Corbicula fluminea can be made.
The TAG found that eradicating freshwater gold clam in the Waikato River is not feasible with current technologies, but a strategy of containment and suppression is feasible.
Biosecurity Response to Corbicula fluminea in the Waikato River [PDF, 820 KB]
The freshwater gold clam has been given the legal status of an Unwanted Organism under the Biosecurity Act.
What this means is that people must not knowingly move or spread the freshwater gold clam or water that may contain it. To do so would be an offence under the Biosecurity Act. However, people can still use the Waikato River for recreation, including boating and fishing, or gathering of kai (food) as long as they meet the Check, Clean, and Dry conditions on this page before moving their equipment or craft.
This means that recreational river users must Check, Clean, and Dry their equipment, boats and other watercraft that have been in contact with the water before moving to another part of the river upstream of Lake Maraetai, or from any part of the Waikato River and lakes to another waterway.
The majority of holders of consents to take water from the Waikato River under the Resource Management Act – such as for irrigation or municipal water supply, or other commercial use of the Waikato River – will notice no impact.
Section 52 permissions of the Biosecurity Act 1993 [PDF, 182 KB]
Special permits are considered for the taking of water likely to contain the freshwater gold clam which isn’t already covered in the general permissions. This could include for example research, sampling, or taking of water not previously consented under the RMA. Consent holders who want to carry out movements that differ from their usual business should also seek a special permit.
To apply for a special permit, contact Biosecurity New Zealand on corbicula.permitting@mpi.govt.nz
The clams were first found in the Bob's Landing area of the Waikato River near Lake Karāpiro in early May 2023.
Biosecurity New Zealand specialists immediately carried out initial surveillance to determine whether the finding at Bob’s Landing was isolated.
They found significant numbers of the clam up to 1.5kms upstream from Bob's Landing, and as far downstream as Hamilton city, indicating a well-established breeding population that had potentially been present there for several years.
After DNA results confirmed the species as the freshwater gold clam (Corbicula fluminea), a full Biosecurity New Zealand response, in partnership with river iwi, and other river stakeholders was established.
Partners include the Waikato Regional Council, the Waikato River Authority, Te Papa Atawhai Department of Conservation, Toitū Te Whenua Land Information New Zealand, and other organisations.
A 3-phase surveillance programme to determine how widely the clams are distributed is ongoing. To date, all detections are within the Waikato River.
This phase involved visual checks and water sampling of 25 sites for environmental DNA (eDNA) testing in the Waikato River and Lake Taupō. This phase is complete.
The furthest upriver the freshwater gold clam has been detected is in Lake Maraetai, near the Mangakino Recreation Reserve. This is the currently known upper limit of the incursion on the Waikato River.
Phase 2 is surveillance of rivers flowing into the Waikato River, prioritising the Waipā River.
This phase is a national survey of high-risk water bodies, collecting water samples for environmental DNA (eDNA) testing. These are lakes and rivers where there are links to the Waikato River through human activities such as boating.
An eDNA test for Corbicula fluminea has been validated and testing of water samples has begun. This testing allows us to do wider initial surveillance and respond rapidly in the event of a detection outside the Waikato River.
Biosecurity rules are in place to stop the spread of the clam through a mechanism under the Biosecurity Act called a Controlled Area Notice (CAN).
Two CANs are in force – one for wake boats in the Waikato River and another for the Te Arawa lakes with additional protections for Lake Ōkataina.
A CAN with specific rules for all wake boats applies to the Waikato River from the Whakamaru Dam to the river mouth at Port Waikato. This will come into effect at 11.59pm on Friday, 24 November 2023 and will be in place until further notice. Wake boats are any craft with an internal tank or bladder that cannot be completely drained.
Waikato River Controlled Area Notice [PDF, 408 KB]
Clam-specific Check, Clean, Dry protocols
A CAN applies to the 14 Te Arawa lakes in the Bay of Plenty with additional protections for Lake Ōkataina. This came into effect from noon on Friday 10 November 2023 and will be in place until further notice.
Te Arawa lakes and Lake Ōkataina Controlled Area Notice [PDF, 225 KB]
All boats must be cleaned at a designated wash station in Rotorua before entering the lake. This is in addition to the clam-specific Check Clean Dry requirements
Access to Lake Ōkataina will be controlled. The lake will be open Friday to Sunday between 6.30am and 7pm.
Any boat that has been in the Waikato River in the previous 30 days must be cleaned at a designated wash station before entering the water. This is in addition to the clam-specific Check Clean Dry requirements
Local lake updates, including events and closures, are on the Rotorua Te Arawa Lakes website.
Lake updates – Rotorua Te Arawa Lakes Programme
The designated wash station is The Wash Place, 338 Te Ngae Road, Rotorua
At the wash station, boaties will need to:
The Wash Place is a commercial facility and there will be a cost for washing your boat and trailer depending on the length of the cycle chosen. You can pay with cards or coins.
The station is open 24/7 and detailed instructions about how to complete the wash are provided.
Biosecurity New Zealand is working through options for additional wash stations in the Bay of Plenty.
This clam is found in freshwater or in brackish water. It's able to survive a wide range of temperatures and salinities and can be found within the water, sitting on top of sandy or muddy surfaces, or buried shallowly within them. You may see their shells partly exposed. They can also be found amongst debris, such as leaves, that may have settled on the riverbed.
Freshwater gold clams are prolific breeders, able to produce 400 juveniles a day and up to 70,000 juveniles a year.
They are small clams that can grow to 2cm to 3cm in length but can be much smaller. Colour ranges from pale to gold when small, and gold when larger, but may be blackened. They have an obvious ribbed texture on the shell.
Small freshwater gold clams may look like native pea-clams or small freshwater mussels (kākahi/kāeo). The key features to look for when distinguishing freshwater gold clams are ribbing on the shell, the shape and colour. If in doubt, report it.
Smaller kākahi can have a similar golden colour and ridges but are more elongated and asymmetrical. Adult kākahi are large and black (up to 10-12 cm across).
These very small (generally less than 6 mm) shellfish do not have distinct rings, or ribs. They are circular in shape. Colour is pale/white to translucent.
You can help us build a picture of where this clam is present by reporting suspected sightings to Biosecurity New Zealand.
If you think you've seen the freshwater gold clam:
You can then either:
If you are using the online reporting form, you'll need to start by saying you are a member of the public, that you want to make a report about 'a marine or freshwater issue' and then select 'freshwater fish or crustacean' from the dropdown box that will appear. Then you will be taken through some further questions including contact information and asked to load your images.
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