Two species of exotic freshwater clams are in the Waikato region
Corbicula fluminea was found in the Bob’s Landing area of the Waikato River near Lake Karāpiro in May 2023. Later, it was also found in the Waikato River from Lake Maraetai Landing to Tuakau.
Corbicula australis was found in March 2024 at the Lake Taupō Aqua Park in a small man-made lagoon.
Find out more about the freshwater clams (Corbicula)
Technical advisory group report on the invasive clams
Following the first detection of Corbicula, a technical advisory group (TAG) was formed to provide scientific and technical expertise.
The TAG included 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.
Advice from the TAG provided a foundation for decisions about the management of Corbicula.
The TAG agreed that:
- eradicating Corbicula fluminea from the Waikato River is not feasible with current technologies
- a strategy of containment and suppression is feasible.
It recommended a copper sulphate treatment be used to eliminate Corbicula australis from the lagoon near Taupō. Treatment will occur in 2025 and will take up to 10 weeks. Following treatment, the lagoon will be filled in.
Eliminating this population of clams from the lagoon is feasible because this is an isolated, contained and relatively small body of water. This method is not suitable for eliminating Corbicula from such a large river system as the Waikato River.
Biosecurity response to Corbicula fluminea in the Waikato River [PDF, 824 KB]
Research reports on the freshwater clams
To inform the response and long-term management of Corbicula, Biosecurity New Zealand commissioned NIWA to research the effectiveness of a variety of treatment methods for killing juvenile Corbicula fluminea (less than 2 days old). We also commissioned NIWA to conduct a survey of Corbicula fluminea to collect data on population density, habitats occupied, and depth profiles in which they are found. This will ensure future suppression trials are designed appropriately.
Treatment trials for killing juvenile Corbicula fluminea [PDF, 1.8 MB]
Corbicula fluminea suppression trial: step one baseline [PDF, 5.4 MB]
Independent research on Corbicula fluminea
The Cawthron Institute has published research on habitats in Aotearoa New Zealand that may be suitable locations for Corbicula fluminea to establish.
Although not funded by Biosecurity New Zealand, this research will be useful to both Biosecurity New Zealand and our partners to inform ongoing surveillance of the clam.
NIWA research programme
NIWA has a $10 million research programme on Corbicula fluminea.
