A new biosecurity threat, exotic freshwater clam (Corbicula fluminea, also known as gold clam), was discovered in the Waikato River in 2023. It lives in freshwater and estuaries, is highly invasive and reproduces rapidly, seeding 400 juveniles per day and up to 70,000 per year. It can quickly clog water-based infrastructure, such as irrigation systems, and is already causing significant concern in the Waikato.

Biosecurity rules are in place to stop the spread of the clam through two Controlled Area Notices (CAN), one for the Waikato River and one for the Te Arawa lakes.

With biosecurity threats growing in scale and complexity, on-farm biosecurity remains a key priority for farmers. Protecting farms and the primary sector from new and established pests and diseases is an ongoing challenge.

Pests can be transferred on clothing, vehicles and equipment. Machinery or gear that moves between farms is a risk if not properly and thoroughly cleaned. Particles of soil the size of a pinhead are enough to carry pathogens like kauri die-back disease and most aquatic weeds can grow from tiny fragments. The juvenile freshwater clam is the size of a grain of sand and is easily spread by water current or human activities.

If purchasing or moving farm machinery or equipment from the Waikato or elsewhere in the country, always thoroughly clean machinery, and follow the Check Clean Dry method to prevent the spread of pests and protect waterways on-farm and beyond.

Follow these on-farm biosecurity measures for vehicles and equipment:

• Minimise traffic and keep vehicles clean. 
• Clean and disinfect vehicles or equipment carefully before sharing with other properties.
• Routinely and thoroughly clean and disinfect anything that comes into contact with your livestock or birds.

If you see freshwater clam, don’t touch it, but report it to MPI by freephone 0800 809 966 or complete the online form at report.mpi.govt.nz/pest 

For more help identifying and reporting pests in Te Taitokerau, visit the NRC Pest Control Hub.