In July 2021 Biosecurity New Zealand announced that an invasive non-native seaweed had been detected in Blind Bay. Underwater surveillance by NIWA showed that it was very widespread across the seabed in this bay. An extension of this surveillance to neighbouring bays revealed that pockets of the seaweed were also present in Tryphena and Whangaparapara harbours, and soon afterwards the incursion was found to have spread to Ahuahu, Great Mercury Island. Following discussion with Aotea mana whenua, Aotea Great Barrier Local Board, Auckland Council and the Department of Conservation, Biosecurity New Zealand imposed legal controls on Blind Bay, Tryphena Harbour, and Whangaparapara Harbour in the form of a Controlled Area Notice (CAN). Mana whenua supported this response with the establishment of a rāhui over the same areas.