Clam-infested aqua park remains closed

Wednesday, 1 May 2024

Lake Taupō Aqua Park has been closed for more than a month after gold clams were found in its lagoon.

More than a month after the Lake Taupō Aqua Park was temporarily closed due to the discovery of invasive gold clams, officials are still figuring out how to deal with them.

Chemical treatments and filling in the lagoon are potential options.

On March 29, the Ministry for Primary Industries (MPI) and Biosecurity New Zealand (BNZ) closed the aqua park for an initial two weeks after the discovery of the invasive freshwater pest species in its lagoon.

BNZ officials said the clams found in the aqua park are a sub-species of the clams originally found in the Waikato River at Bob’s Landing in May 2023.

Kinloch Marina has banned any boats that have been in the Waikato River from using its moorings in an effort to prevent the spread of gold clams.

BNZ said Corbicula australis looks very similar to the previously found Corbicula fluminea and had been in the park’s lagoon for at least two years.

BNZ director of readiness and response John Walsh said the park would remain closed for the foreseeable future as biosecurity staff worked with the owners “to determine appropriate long-term options for the management, suppression, or removal of the clams”.

“Those options are complex, and we need to take time.”

“Options could include chemical treatments, heat treatment, covering the lagoon or the surface of it, filling the lagoon in, or a combination of these options.”

Gold clams grow to about 2cm in size, but are prolific breeders producing up to 70,000 juveniles a year.

Walsh said the detection of this sub-species did not change BNZ’s response.

“Our focus remains on preventing the spread of these exotic clams to other water ways.”

Attempts to contact the park’s owners have been unsuccessful, but Walsh said BNZ had been speaking with them regarding possible compensation after they were forced to close.

Elsewhere, the board that runs Kinloch Marina on the shores of Lake Taupō has banned any boats that have been in the Waikato River from using its moorings in an effort to prevent the spread of gold clams.

Walsh said BNZ had increased its surveillance of the surrounding areas in response to the aqua park find, including carrying out visual inspections to ensure there is no undetected spread of the clams.

He said the size of the clams and density of the population in the aqua park lagoon indicates the clams have been there for several years.

“We may never know exactly how the clam got into the water at the lagoon, but we do know that human activity is the most likely method of spreading Corbicula from one unconnected water way to another.

“Complying with legal controls and ‘Check, Clean, Dry’ requirements continue to be the best way to prevent the spread.”