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See Weeds? Report them.

Marine pests can be tricky to identify, but many threaten our harbours, fisheries and native species.

Seaweed species Caulerpa brachypus and or caulerpa parvifolia have been found in Aotea Great Barrier Island and Great Mercury Island, about 65kms off Coromandel's coast. These species smother everything they can, rocks, sand, sponges, shell fish, affecting the mauri of the ocean and the people who live there.

Caulerpa lives up to depths of about 40m, so spread mainly by people - caught in anchors, ropes and fishing gear. The short bright green smothering seaweed grows up to 10cm tall and spreads via creeping horizontal runners. Even the smallest piece of the seaweed can reestablish as a new plant.

A tiny piece of these caulerpa species, arriving in a new location could grow to become a thick mat covering the area of a rugby field within a very short space of time. This is why it is so important for people to be aware of this threat and report any potential sightings immediately. In Aotea, the spread of the pest is so great that existing methods of control are not practical. MPI and mana whenua have formed a governance group to work together on finding solutions for Aotea. A rāhui has been imposed over the affected bays for 2 years to give the governance group time to find a practical solution whilst reducing the risk of spreading the weed further.

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