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Regional | Ngāti Manuhiri

Ngāti Manuhiri moves from monitoring to eradicating Caulerpa

Ngāti Manuhiri Settlement Trust wants to cull the toxic invasive seaweed Caulerpa as fast as it can because it is growing across Kawau Bay.

Chief executive Nicola Macdonald says the “major infestation” of the caulerpa seaweed has been challenging to manage considering the vast spread of it reaching the Bay of Islands and Aotea/Great Barrier Island.

Macdonald says the trust has a caulerpa protocol: “Remove, reduce and eradicate.” And that means getting to work right away.

“That means we’re not going to sit around monitoring and taking scientific data. It means we’re getting in the water, and we’re going to remove that pest plant and get it out of here.

“We’re calling on all of our communities, mana whenua, iwi right across the country to say ‘Hey, this is the No.1 protocol.’”

Biosecurity NZ, the Northland Regional Council and mana whenua of the region sent divers on the Caulerpa hunt back in early June.

Trust can’t wait

Macdonald says the trust can’t just sit and monitor like the ministry or NIWA due to the speedy growth of the seaweed going from the size of a small coin to a rugby field in a few weeks that can destroy kaimoana.

“A really good example is what happened in Aotea. They had a very small marginal strip two years ago. Now they’re dealing with over 80 hectares. It has completely suffocated all of their bays.

“We’ve got a few small patches and that’s why early detection is so important… we’ve got to get divers in there and hand-pick it out. If hand-picking doesn’t work, we have to look at other suppression methods.”

Macdonald is asking anyone out in the water to be mindful as Caulerpa can spread on the side of boats and even anchors and contact Biosecurity NZ if it is seen.

The trust will also have conversations in two weeks’ time with Californian Caulerpa experts who have been using tools to fight the invasive sea pest, with Northland already trialling it for use in its waters.

Public Interest Journalism