New Waikato River restrictions to curb gold clam

Freshwater gold clams were first found in May 2023, but may have been in the Waikato for two to three years prior.

Concerns about invasive gold clams have seen Biosecurity New Zealand enforce a new rule for boaties on the Waikato River.

From midnight on Friday, November 24, wake boats used on an area of the Waikato cannot be used anywhere else.

John Walsh, Biosecurity New Zealand director of readiness and response, said the notice applied to a significant stretch of the river.

“The new rule, introduced through a mechanism under the Biosecurity Act called a Controlled Area Notice (CAN), affects all wake boats using the stretch of the Waikato River from the Whakamaru Dam down to the river mouth at Port Waikato.”

“Wake boats that have been on this controlled stretch must not be used in any other waterways including other parts of the Waikato River outside the controlled area. The CAN comes into effect at 11.59pm on Friday 24 November 2023.”

The rule was intended to curb the spread of the freshwater gold clam, which was first spotted in the Waikato River in May 2023.

The pest was fairly new to New Zealand, but had already spread from its native Asia throughout South America and Europe, where eradicating them had proven impossible.

A prolific reproducer, the gold clam can clog water treatment plants and other infrastructure.

There is also concern they could out-compete native species for resources like food.

The new rule currently applies only to wake boats, which is any craft with an internal bladder or tank that could not be completely drained.

This was due to their increased risk of transmitting pests, said Walsh.

“Wake boats present a higher risk of transmitting the freshwater gold clam as there is currently no known reliable method of cleaning the internal tanks and bladders.

“Biosecurity New Zealand is investigating whether a reliable cleaning method can be developed. If so, the special requirements for wake boats will be reviewed.”

Other users of the Whakamaru Dam to Port Waikato area of the river were still expected to follow the Check, Clean, Dry requirements for clams and other pests under the Controlled Area Notice.

This included boats and kayaks, as well as fishing or kaimoana gathering equipment, water skis, wakeboards and inflatable toys.

Signs informing river users of the new requirements were being installed at around 70 locations, with all expected to be in place by Sunday.

Biosecurity New Zealand established a permanent wash station at the Mighty River Domain at Lake Karāpiro to assist the public with the Check, Clean, Dry requirements, as well as funding a mobile station which could be taken to events and busy spots along the river as needed.

The efforts needed to keep the gold clam in check were significant but vital, said Walsh.

“Extensive surveillance shows that we are successfully stopping the spread of the clam.

“CANs are a critical tool in our ongoing efforts to protect our waterways.

“This new CAN replaces and strengthens the existing measures that are in place for the Waikato River and adds to the biosecurity rules we’ve put in place for Te Arawa lakes in the Bay of Plenty recently.”

• For more information about the gold clam, and the new biosecurity measures, visit https://www.biosecurity.govt.nz/clam.

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