Minister Hoggard: New dredging tool shows promise in Northland trial

A giant underwater dredge device designed to remove large areas of exotic caulerpa seaweed has performed well in recent testing at Omākiwi Cove in Northland, Biosecurity Minister Andrew Hoggard said.

“Known as the submersible dredge planer (SDP), the remotely operated equipment was developed for Biosecurity New Zealand by Northland Regional Council, which contracted local company Johnson Brothers Ltd to design and build it,” Hoggard said.

“The SDP is the last of three removal tools developed using the $10 million we allocated in 2024 to tackle this invasive seaweed. The other two are a UV-C light treatment to irradiate caulerpa, and a scalable enclosure system (the ‘Rehabitat’) that contains and seals chlorine over affected areas.”

The trials, supported by the Cawthron Institute and Ngāti Kuta and Patukeha hapū, demonstrated the SDP’s mechanical performance, maneuverability and functionality.

According to Hoggard, environmental impacts are still being assessed.