Gold clam threat to freshwater mussel

Freshwater gold clams.

An invasive pest species is threatening rivers in the region.

The recent discovery of freshwater gold clams in Waikato waterways had local authorities on high alert. Horizons environmental manager Craig Davey said the small clams could be destructive to our region’s lakes and rivers, which is why the ‘Check, Clean, Dry’ behaviour is important.

The onus was on anyone with boats or equipment to check, clean and dry all their gear before entering a new waterway.

“Anyone coming from the Waikato should take action to help stop the spread of the gold clams because they threaten the survival of our freshwater mussels – kākahi. Gold clams are filter feeders which may compete with kākahi for food,” he said.

“The clams reproduce really fast, forming massive populations which can turn river and lake edges into ‘clam pavements’. They will also clog water-based infrastructure such as electric generation plants, irrigation systems and other water takes.

“Freshwater gold clams are difficult to control and eradication has never been achieved overseas.

An invasive gold clam species is threatening rivers in the region.

“Check, Clean, Dry ensures any equipment or boats that have been in water in the Waikato region don’t bring these clams into our region’s waterways. Clams less than a millimetre in size can move between waterways in or on wet equipment.

“You should remove any visible plant or clams from your gear prior to leaving the waterway. Then, clean everything, ideally with very hot water. Finally, ensure your gear is completely dry for at least five days before you use it in another waterway.”

Davey said it’s possible the clams may have already spread from the Waikato.

“If you think you have seen the freshwater gold clam, please report sightings to Biosecurity New Zealand on 0800 80 99 66 or online at report.mpi.govt.nz. You will need to provide a precise location, close-up photo of the clam as well as its surroundings,” said Davey.

“Early detection of the clams provides a greater opportunity of controlling the spread further. We really hope to minimise the impact for our region by not only prevention, but also early detection.”

Davey said the freshwater gold clam (Corbicula fluminea) is native to eastern Asia and are small, with adults growing between 2cm to 3cm in length.

“They are dirty white, yellow or tan and have a ribbed texture on the shell,” he said.

“They are found in freshwater and have the ability to produce 400 juveniles a day or up to 70,000 juveniles a year.”

For more information about the Check, Clean, Dry process or about freshwater gold clams, visit www.mpi.govt.nz.

- Public Interest Journalism funded through NZ on Air.