Where exotic freshwater clams have been found
Corbicula fluminea (commonly known as 'gold clams' or 'freshwater gold clams') is native to eastern Asia and is widely established in North and South America and Europe. In New Zealand, it 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 is native to Australia, where it is common and widely distributed. In New Zealand, Corbicula australis was found in March 2024 at the Lake Taupō Aqua Park in a small man-made lagoon.
Since the discovery of Corbicula fluminea in 2023, Biosecurity New Zealand and partners have been working to contain the spread.
The initial biosecurity response to the clam discovery
After the discovery of Corbicula fluminea in the Waikato River, Biosecurity New Zealand immediately established a response. This was done in partnership with river iwi and through working with stakeholders, including the Waikato Regional Council, the Waikato River Authority, the Department of Conservation, Toitū Te Whenua Land Information New Zealand, and others.
The response focused on:
- identifying the spread of the clams
- containing them to their known locations.
Corbicula long-term management plan
Biosecurity New Zealand and the response partners have developed a long-term management plan for Corbicula.
The focus of the plan is to:
- contain Corbicula fluminea to the current known areas in the Waikato River catchment area
- reduce its impact where feasible and develop tools to achieve this.
The Freshwater Biosecurity Partnership Programme is overseeing the long-term management of Corbicula.
The programme involves key partners Biosecurity New Zealand, Department of Conservation, Fish & Game New Zealand, Land Information New Zealand, the Tūwharetoa Māori Trust Board, other mana whenua, power companies, Te Uru Kahika (regional council collective), and industry groups.
Local councils and the Department of Conservation are leading operational delivery of the plan in partnership with iwi.
The work programme includes:
- development of a national surveillance strategy
- a rapid assessment plan for new incursions
- expanding public awareness
- research to better understand the clam’s impact on our waterways
- and exploring regulatory options to improve pathway management.
Corbicula fluminea collaborative long-term management plan [PDF, 766 KB]
Surveillance of clams
Surveillance is focused on detecting any spread of these clams outside the known locations.
Early detection allows a quick response and provides an opportunity to eliminate Corbicula from other areas where newly detected populations are not well established.
eDNA testing of high-risk water bodies across New Zealand, in partnership with regional councils and iwi during 2023 and 2024, found no indication of Corbicula.
A national surveillance programme including risk sites (those locations with significant movements of people and water equipment from the Waikato) is being managed under the long-term programme.
A new surveillance strategy is being developed to help identify if there has been spread to new waterways. Surveillance will include sampling at high-risk sites throughout the country.
