Biosecurity New Zealand and mana whenua for the Waikato River are urging people who work and play in and around the river to keep a lookout for a new-to-New Zealand clam species that has been found at Bob’s Landing near Lake Karāpiro.
The freshwater gold clam (also known as the Asian clam or by its scientific name Corbicula fluminea) is native to eastern Asia. It is also widely established in North America, South America and Europe.
These shellfish are pest species overseas because they reproduce rapidly and can clog up water infrastructure such as hydroelectricity plants, municipal water supply and irrigation systems. They are also potentially a threat to native species, as they consume a lot of plankton in large populations.
Biosecurity New Zealand Deputy Director General Stuart Anderson said how the freshwater gold clam would behave in New Zealand conditions is unknown. However, it has proved difficult to control overseas, and no successful eradication has been documented.
"We are partnering with Waikato-Tainui, the Waikato River Authority, the Waikato Regional Council, Te Papa Atawhai Department of Conservation and Toitū Te Whenua Land Information New Zealand to understand this incursion and how best to respond to it,” said Anderson.
"This includes setting up a panel of technical and mātauranga experts to provide us with management advice.”
Initial checks have found the freshwater gold clam present over a 45-kilometre stretch of the Waikato River, from 1.5km upstream of Bob’s Landing, just upstream of Lake Karāpiro, and downriver to Hamilton.
Anderson continued that the plan now was to search further within the Waikato River and other rivers and lakes linked through human activity.
"This wider surveillance will include using targeted eDNA testing.”
To support this science, Biosecurity New Zealand asks people who work around the river, or boat, fish or swim there, to keep a lookout and report any sightings of this new-to-New Zealand freshwater clam.
"They are a dirty white to yellow or tan, and adult ones are 2-3 cm across. They can be found in the water, on sandy or muddy surfaces, or buried shallowly within them. They’re quite distinctive. No New Zealand species look like this in the river."
Freshwater gold clams are not safe to eat from the Waikato River, which has high concentrations of toxins in the river. The clams filter-feed from the water and accumulate toxins in their gut.
For more information regarding the clams, please click here.
