Signs warn Lake Taupō users to be on the lookout for invasive gold clams.
Signs warn Lake Taupō users to be on the lookout for invasive gold clams.
A highly invasive introduced species could have been in a Taupō lagoon for up to three years.
Biosecurity New Zealand confirmed the presence of freshwater gold clams on March 28, at the Taupō Aqua Park, previously known as the Taupō Wake Park, in Wairakei.
It has ordered the facility to shut down while long-term options for dealing with the clams are looked into.
The 10-year-old, man-made lagoon contains a fun park full of floating structures popular with children.
Its Facebook page stated it was open from November last year and due to close for the cooler months after Easter weekend. The owners did not wish to comment.
Tūwharetoa Māori Trust Board chief executive Rakeipoho Taiaroa said they received a “tip-off” from someone more than three weeks ago and informed Biosecurity NZ at the time.
Biosecurity NZ director of readiness and response John Walsh said a population of gold clams was “seen” by Biosecurity NZ staff last week, after a positive environmental DNA test.
“The size of the population indicates that the clam has likely been in the lagoon for two to three years.”
“The lagoon at the Lake Taupō Aqua Park doesn’t discharge into any other body of water, meaning the most likely way that clams could spread from the lagoon would be human activity.”
He said anyone who had used the aqua park in the last week should “wash their togs and towels in hot water and thoroughly dry them for at least 48 hours before using them in any other river or lake”.
“We’ve increased our surveillance in the surrounding area in response to this find, and so far there are no indications of the clam in any nearby waterways, including the Waikato River and Lake Taupō.”
He said Biosecurity NZ had a national surveillance plan for the clam, with a focus on detecting any spread of the clam beyond its known locations on the Waikato River. The aqua park is separated from the Waikato River by a 25 metre wide strip of land.
Known locations of the clams now included the aqua park and a 200km stretch of the river, from Lake Maraetai Landing to Tuakau.
Taiaroa said they had invested in staff training so they were now able to do their own environmental DNA testing for the clams.
Invasive gold clams have been discovered in a lagoon operated by the Taupō Aqua Park.
He said they were worried about another “foreign being” in the waters of Lake Taupō and the upper Waikato River.
“They will be in direct competition with the native kākahi – that’s the freshwater mollusc that we have in Lake Taupō.”
He said there were also concerns from an infrastructural point of view, for both the Taupō District Council and for Mercury, which has nine power stations along the Waikato River.
“Certainly from our side of the [Tūwharetoa Māori] Trust Board, [we are] very concerned that we will have another being here like catfish and the possibility of didymo ... in terms of this thing, we are still unsure if it can survive but if it can’t we are lucky.”
He said they were talking with Biosecurity NZ to plan areas to be monitored, including the foreshore in the Taupō township, Kinloch and other areas of interest.
Walsh said the ‘Check, Clean and Dry’ message reinforced the best way to prevent the spread of freshwater clams, and that applied to all boating and swimming gear.
