Summer checks to keep gold clam out of Kai Iwi

Local authorities and the Department of Conservation are joining forces with local tangata whenua again this summer to keep an unwanted freshwater invader – the gold clam – out of the Kai Iwi Lakes.

Northland Regional Council member Jack Craw, who chairs the council’s Biosecurity and Biodiversity Working Party, says gold clams, first detected in the Waikato River in May last year, are a significant biosecurity threat.

“This summer, we’re proud to again work in partnership with Te Kuihi, Te Roroa, Papa Atawhai/Department of Conservation and Kaipara District Council (KDC) to run biosecurity checks at Lake Taharoa, Kai Iwi Lakes.”

“Our biosecurity checks encourage everyone to play their part in protecting our waterways.”

“This collaboration with iwi and community partners highlights the strength of teamwork in safeguarding these special places for current and future generations to enjoy.”

Under KDC’s Taharoa Domain Bylaw 2018 the owner or master of a vessel or power-driven vessel can be denied access to the lakes if they refuse to undertake a biosecurity check if requested.

Councillor Craw says gold clams are an issue because they are filter feeders that can potentially compete with native species for food.

Gold clam populations can also clog water-based infrastructure including electric generation facilities, irrigation systems and water treatment plants.

Native to Eastern Asia, the clam is widely established in North and South America and Europe where it has become a pest.

“It’s a highly invasive pest that reproduces rapidly – up to 400 juveniles a day and up to 70,000 a year.”

Councillor Craw says the clams reproduce rapidly and tiny gold clam larvae – just 0.2mm in size – can survive out of water for up to 10 days, making them challenging to manage.

“It’s important for all users of freshwater to follow the Check, Clean, Dry method for boats and gear to prevent their spread.”

“It is hard, if not impossible, to fully empty and dry boat ballast tanks, which means the clam can survive between boating sites.”

“Best practice is to use a high-pressure steam cleaner or a power wash on to grass or gravel where there is no likelihood of runoff entering back into a waterway or stormwater system.”

“For absorbent materials, such as lifejackets or waders, they must be frozen overnight, or washed with a five percent bleach solution, or washed in hot water (45C degrees plus) for 20 minutes.”

Meanwhile, Cr Craw says under a Ministry for Primary Industries ‘Controlled Area Notice’ (CAN) all wake boats that have been in the controlled stretch of the Waikato River (from the Whakamaru Dam to the outflow at Port Waikato) must not be used in any other waterways outside the controlled area.

“This means no wake boats that have been used on this stretch of the Waikato River can be brought to Northland.”

Similarly, any other boats or gear used on this stretch of the river must have an updated Check, Clean and Dry process before moving it from the controlled area to another freshwater environment or brackish water.

Further information about gold clams is available from: mpi.govt.nz