As more than 3000 paddlers hit Waikato waters for the Waka Ama National Sprints Championships, measures are underway to halt the spread of invasive gold clams.

The Ministry for Primary Industries (MPI), first discovered the freshwater pests, Corbicula fluminea, also known as Asian gold clams, along a stretch of the Waikato River in May last year.

Monitoring of high-risk water bodies, such as the 14 Te Arawa lakes near Rotorua and Lake Taupō, has been continuous since.

Biosecurity New Zealand’s Check Clean Dry team and Waka Ama New Zealand worked together in the lead-up to the event at Lake Karāpiro to ensure all lake users would be ready to take necessary prevention steps.

BNZ director of readiness and response John Walsh said it did not just take one person to protect the waterways.

“It takes all of us to protect what we have got here and we all have a part to play in making sure we do everything we can to stop this pest clam from getting into any other river or lake.”

The 2024 Waka Ama National Sprint Championships have kicked off at Waikato's Lake Karāpiro. Photo / Kate Durie

“International experience indicates these clams could have a serious impact on freshwater environments, as they breed profusely and take up the space and food used by native species.

“They can also clog water-based infrastructure, such as electricity generation plants, irrigation systems, and water treatment plants.

“Overseas, this clam has proved difficult to control and eradication has never been achieved. It is unknown how this species will respond in New Zealand conditions, but we are taking a precautionary approach to attempt to stop it spreading to new locations”, he said.

MPI developed a guidance sheet which was shared with competitors and given before the event, with a supporting development of a video with a waka ama navigator.

The Check Clean Dry team had been in contact with event organisers of Waka Ama for several months, ensuring their participants were aware of the high need to check, clean, and dry their equipment.

Check Clean Dry ambassadors will be present for parts of the event, and there will be wash-down stations for competitors to check, clean, and dry their waka’s and gear.

MPI's, Check Clean Dry team, will be present on selected days at the Waka Ama National Sprints Championships this year. Photo / Malisha Kumar

Waka Ama chief executive, Lara Collins, said a plan for competitors is well in place.

“At the end when everybody is finished, all the waka, life jackets, paddles, and equipment, get washed down at one of the stations before they leave the lake.

“There’s also a diluted bleach solution that goes into big buckets of water that you dip your equipment in, and it prevents the spread as the clams can’t live in that substance. It’s a pretty thorough process that everybody will go through.

“Waka ama clubs and their whānau are all fully behind this kaupapa, and we just want to make sure we do whatever we can to help the situation”, she said.

The freshwater gold clam is an Unwanted Organism under the Biosecurity Act, meaning it’s forbidden to knowingly spread the clam, or water containing it.

It is a legal requirement in waterways that the clam has compromised to follow the new check, clean, and dry procedures from the stretch of Waikato River, from Lake Maraetai to the river mouth.

“The most important thing is that people take personal responsibility and make sure that they check, clean and dry their boats and other equipment when leaving the affected stretch before moving to other waterways”, Walsh said.

The seven-day Waka Ama National Sprints Championships end on January 20.