Sign In / Register
A giant underwater dredge device designed to remove large areas of exotic caulerpa seaweed has performed well in recent testing, says Biosecurity Minister Andrew Hoggard.
Known as the submersible dredge planer, the remotely operated equipment was developed for Biosecurity New Zealand by Northland Regional Council.
“I’m thrilled that field tests over the past few weeks have shown the machinery works as expected and will be a useful addition to our toolbox of treatment methods,” said Hoggard.
Caulerpa has been found at Iris Shoal and Bostaque Bay in Kawau Bay. Currently, no legal restrictions are in place there but Auckland Council has asked boaties to avoid anchoring and fishing using any method that makes contact with the seafloor.
Caulerpa is more established at Great Barrier Island and no anchoring is permitted in a controlled area on its western side.
The invasive weed blankets the seabed, and can devastate marine ecosystems.
The trials, supported by the Cawthron Institute and Ngāti Kuta and Patukeha hapū, demonstrated the SDP’s mechanical performance, manoeuvrability and functionality. Hoggard said the environmental impacts are still being assessed.
“Developing the SDP has been a mammoth effort. Two key components – the remotely operated vehicle (ROV) and the control room had to be sourced from Scotland. There was no off-the-shelf solution available anywhere in the world, so it’s been custom designed for New Zealand conditions. Its unique screw propulsion system, for example, allows it to operate effectively on soft, sandy seabeds.”
“It’s driven by remote control and fitted with blades to cut through caulerpa mats and a large dredge system to suction material to the surface for disposal. It’s a great example of Number 8 wire Kiwi ingenuity.”
Having a range of tested treatment tools – including large-scale removal technology like the SDP is important so we can respond quickly to control or eliminate invasive species in future,” Hoggard said.
