Botanical names: Corbicula fluminea and corbicula australis
Two species of exotic (from overseas) freshwater clams were first found in the Waikato region in May 2023. Corbicula fluminea is native to eastern Asia and is widely established in North and South America and Europe, while Corbicula australis is native to Australia, where it is common and widely distributed.
To date there have been no exotic freshwater clams detected in the Bay of Plenty region or elsewhere in the country outside of the Waikato region.
About the clams
These 2 types of corbicula are prolific breeders, able to produce 400 juveniles a day and up to 70,000 juveniles a year, allowing them to reach extremely high densities in optimal conditions. This means they can clog water-based infrastructure, such as electricity generation plants, irrigation systems, and water treatment plants. They can also compete with native species for food and space.
Management programme
Corbicula fluminea and Corbicula australis have been given the legal status of an Unwanted Organism under the Biosecurity Act. This means that people must not knowingly move them or water that may contain them. To do so would be an offence under the Biosecurity Act.
Corbicula is not currently a listed species within the Bay of Plenty Regional Pest Management Plan (RPMP) 2020–2030 but under rule 7 of the Bay of Plenty Regional Pest Management Plan (RPMP) 2020–2030 provision is made for stopping the spread of freshwater pests by requiring all boat ramp users to certify that their vessel, craft, and trailer are free from freshwater pest fish and pest plants.
The Biosecurity New Zealand website has details of the Check Clean Dry requirements which must be used in the North Island to prevent the spread of this clam, as well as other invasives.
A key difference in the cleaning process is a requirement to soak absorbent gear like lifejackets in hot tap water (50 – 55C) for at least 5 minutes to kill sticky juvenile clams, which can be too small to see.
Te Arawa lakes Controlled Area Notice (CAN)
A CAN applies to the 14 Te Arawa lakes in the Bay of Plenty with additional protections for Lake Ōkataina.
For all 14 Te Arawa lakes
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 'Check Clean Dry' requirements.
For Lake Ōkataina
All boats must be cleaned at a designated wash station in Rotorua before entering the lake. This is in addition to the 'Check Clean Dry' requirements.
The designated wash station is The Wash Place, 338 Te Ngae Road, Rotorua
The Wash Place is a commercial facility open 24/7 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.
At the wash station, boaties will need to:
You can read more information about exotic freshwater clams and the restrictions in place to stop its spread on the Biosecurity New Zealand website.
From Wednesday 24 February, a new automated gate will provide an efficient way for those who have completed Check Clean Dry procedures to access Ōkataina.
The new process:
Please note - There is no overnight parking or camping allowed at the Lake Ōkataina scenic reserve.
Until Wednesday, boat ramp users can continue to access the lake using the current CAN process (see above).
The lake iwi Ngāti Tarāwhai has successfully managed user access to the boat ramp since 2023 and the new process means that they will no longer need to be present to approve access to the lake.
The automated gate project has been led by Bay of Plenty Regional Council and funded by the Bay of Plenty Regional Council, Rotorua Lakes District Council and the Ministry for Primary Industries.
Find out about the new process and the frequently asked questions here.
Pictured: Gate structure being installed (11 February 2025)
