11/11/2025
Recreational lake users are urged to take extra care when moving between waterways, following the recent detection of the invasive Asian Gold Clam (Corbicula fluminea) at Lake Rotomanu.
The gold clam poses a significant risk to our freshwater ecosystems. This species is highly invasive, possessing both male and female reproductive organs enabling self-fertilisation. Gold Clam larvae are extremely small (around the size of a grain of sand) and can be very difficult to detect.
To prevent the spread of gold clam, all waterway users must follow the Check, Clean, Dry method:
-Check gear and equipment for any visible plant matter, mud, or debris.
-Clean thoroughly using hot water (60°C or higher), a bleach solution, or an approved decontamination solution. For slow to dry items, freezing these until solid is a proven solution.
-Dry completely for at least 48 hours, ensuring no moisture remains before using gear in another waterway.
If you come across suspicious shellfish or freshwater organisms in a waterway where you suspect they shouldn’t be, do not move them, take a photo and record the location, and report immediately to MPI via 0800 80 99 66.
For more information on the gold clam and the appropriate Check, Clean, Dry process, you can view the following resources from MPI and NIWA below:
https://www.mpi.govt.nz/biosecurity/exotic-pests-and-diseases-in-new-zealand/long-term-biosecurity-management-programmes/exotic-freshwater-clams-corbicula
https://niwa.co.nz/freshwater/stopping-gold-clam-its-now-or-never/about-clam/gold-clam-life-cycle
https://www.mpi.govt.nz/outdoor-activities/boating-and-water-activities-preventing-the-spread-of-pests-weeds-and-diseases/check-clean-dry
Lake Rotomanu will be closed to motorised watercraft from tomorrow (12 Nov), following the discovery of the freshwater clam Corbicula fluminea.
Here's what you need to know 👇
* As an interim measure, New Plymouth District Council will close Lake Rotomanu to motorised boats, which are at the highest risk of spreading clams.
* Other recreational users will be required to thoroughly check, clean and dry all gear before leaving the lake shore.
* The road access and carparks will remain open.
* Surveys are being carried out this week, checking for clams in the nearby Waiwhakaiho River as well as other lakes across Taranaki.
* Once those results are available, further decisions will be made as to how to manage the incursion and what, if any, restrictions will remain in place. We will keep you informed.
This is the first discovery of the clam in New Zealand outside of the Waikato River and Lake Taupō Aqua Park. We’re disappointed that the clam has made its way to Taranaki, as we had been working hard to keep it out. But our focus now is on working with Biosecurity New Zealand and local partners to ensure it does not spread into other Taranaki lakes or rivers.
We appreciate it is coming into summer and the lake is a favourite spot for many boaties. But you will understand how important it is we act quickly – Corbicula can take over a waterway and have long-term effects on recreation and the environment.
We are asking for your support. Whether it’s Lake Rotomanu or any other waterway, it's more important than ever you check, clean and dry everything that has been in contact with the water before moving between waterways.