23 April 2026
Kia ora tatou. In this issue:
- Updates on new detections and the National Steering Group
- Recent events - Whitianga Seaweek event, Bay of Plenty ambassadors
- Our people – Nyze Manuel; Dave Pickering
- Coming up – Revive Our Gulf Community Forum; May Seaweed workshops, Hutchwilco Boat Show.
UPDATE – New detections
Pictured above: A new caulerpa sighting from the Waiheke Marine Project.
A number of new detections have been reported since our last update. Following the biomass reduction this past year, we have continued to see some expected summer re-growth and expansion into new areas.
Many organisations have been undertaking surveillance recently – councils, Earth Sciences New Zealand – funded by Biosecurity New Zealand, community organisations and iwi or hapu. We have also received reports of sightings from observant members of the public which are very helpful.
As a result, current new detections include:
- a local photographer and conservationist reported a range extension of exotic caulerpa at Tiritiri Matangi Island in Hauraki Gulf - video of this detection can be viewed below;
- Auckland Council divers found patches of exotic caulerpa just outside Leigh Harbour during delimitation work, an extension of a known patch that is under treatment inside the harbour;
- just south of Leigh Harbour, an Auckland University student studying exotic caulerpa found a small patch at Mathesons Bay;
- Waiheke Marine Project’s surveillance team found patches of caulerpa off the outer reef of Enclosure Bay in February and more new patches between Palm Beach and Enclosure Bay in March.
In March, Biosecurity New Zealand contracted Earth Sciences New Zealand to undertake a follow-up survey to assess the extent of exotic caulerpa regrowth at sites in the Hauraki Gulf and Coromandel Peninsula. The dive team revisited sites that were surveyed in November 2025 and sites that hadn’t been checked for some time.
As a result, exotic caulerpa changes include:
- a new infestation of exotic caulerpa was found at Ōtata in the Noises Island group: small patches were found on reef and sandy gravel in about 12m depth;
- exotic caulerpa has increased at Hauturu-o-Toi Little Barrier Island, Kawau Island, and several sites in the northern Coromandel;
- a second new site detected at Tiritiri Matangi Island; and
- exotic caulerpa extended to several new sites on the western side of Rākino Island.
All of these detections continue to be isolated patches. To date, there are still no known continuous, multi-hectare mats of caulerpa as previously seen. Planned surveillance will continue in the coming months.
Below: A map showing recent Hauraki Gulf surveillance sites, coloured according to status.
50-second video of a new detection at Tiritiri Matangi (click the image)
NEW DETECTIONS MANAGEMENT
Management of new detections is done as a collaboration with local interest groups – often community groups, tangata whenua, regional councils and Department of Conservation. This may include confirming extent of presence, planning management and organising treatment.
The patches at Leigh Harbour have been treated by Auckland Council and University of Auckland, and the Te Kohuroa Rewilding initiative is working with Auckland University and Ngāti Manuhiri to delimit and treat the patches of exotic caulerpa at Mathesons Bay.
Biosecurity New Zealand will further discuss the recent detections at Waiheke and Tiritiri Matangi with hapu and iwi, Auckland Council, DOC and community groups.
These new detections and the increase in exotic caulerpa in known areas reiterate the need for all who go in or near marine areas to report any detections of exotic caulerpa and for boaties in the area from North Cape to East Cape to keep checking your anchor and gear for any exotic caulerpa and bag and bin any seaweed you find.
UPDATE – Steering Group meets for first time
The Exotic Caulerpa National Steering Group met for the first time in Auckland in March. They discussed the Exotic Caulerpa National Strategy, which they will champion and advise on. They received reports on development of control tools, research activities, geographic coverage of exotic caulerpa, biomass changes and the role of CANs in supporting awareness and behaviour change alongside ambassador and advocacy initiatives.
The next major milestone for the group will be reviewing the proposed operational plan for the coming financial year.
To learn about the membership and keep up with Steering Group developments through meeting minutes, see this webpage.
EVENT – Seaweek workshop in Whitianga
A workshop in Whitianga during Seaweek in March (pictured above) proved to be a good opportunity for local community discussions about exotic caulerpa. The workshop was hosted by Biosecurity New Zealand’s Caulerpa Programme team, Waikato Regional Council, Department of Conservation and Ngāti Hei.
More than 36 locals came along, including long‑time residents, recreational fishers, students and divers keen to learn about how to recognise exotic caulerpa, the work happening across the Coromandel and what locals can do to support early detection and prevent spread. The mix of ages and perspectives created a really engaged room, with plenty of kōrero about what people are seeing on the water and how they can help. These community‑led conversations are vital in strengthening the wider response and helping us keep ahead of emerging risks.
EVENT – BOP ambassadors make connections
It’s been a busy summer both on and off the water for Bay of Plenty Regional Council marine biosecurity ambassadors Jack Bowick (pictured above) and Rachel Collins.
During Seaweek in March they got kids in the Eastern Bay fishing for marine pest knowledge. Six-hundred people attended the event hosted by a local community organisation in Whakatāne over four days, and the response from those who attended was overwhelmingly positive. The primary-school and kohanga kids attempted to catch both native and invasive marine species represented by magnetised photos.
The activity proved to be a great conversation starter, keeping the kids entertained while hooking the parents in for a more serious conversations about exotic caulerpa and the other marine pests represented. Fortunately, caulerpa has not been found in the Bay of Plenty waters so the focus for the team is on education and ensuring people follow the right marine biosecurity behaviours. Asian paddle crab was also a focus pest at the event, having first been detected in nearby Ohiwa Harbour in 2021.
Windy conditions over summer weren’t great for boating in the Bay, but Rachel, who was employed by the Council for the season, spent time at the approximately 30 public coastal and harbour boat ramps. She spoke with people who were heading out, educating and assessing people’s current marine biosecurity knowledge. The surveying, which has been running for several years now, indicates boaties are becoming more aware of marine biosecurity.
Other initiatives over the summer included attending the weigh-in day at the Kids Hunting and Fishing competition in Katikati and presentations to the local boat and fishing clubs. Also, Jack has recently been running a series of 45-minute biosecurity briefings for five classes of Year 12 and 13 students at Mount Maunganui College to ensure that the next generation of boaties and divers keep marine biosecurity front of mind when they head out on the water.
OUR PEOPLE – Nyze Manuel – National Steering Group
Nyze Manuel (pictured above) was elected chair of the Northland Conservation Board in 2021. And since the discovery of exotic caulerpa in Te Rāwhiti Inlet, she has had the support of iwi to act as kaitakahaere (organiser) for caulerpa response across Tai Tokerau. Recently she was appointed as a member of the new Exotic Caulerpa National Steering Group.
Nyze recalls the moment that set her on this path: she was back in Whangaroa where she grew up, having spent several years away for education and work. She was out on a boat with her dad and at one point asked about a scallop bed she knew as a child. He said it had disappeared.
That moment was an awakening. She realised that te taiao – the natural living world – needs protection. “Taiao is how we live – we are one with the environment. It’s just who I am. I’m a kaitiaki (guardian).”
For Nyze (Ngāti Kahu ki Whangaroa, Ngāpuhi ki Whangaroa, Ngāpuhi and Te Arawa), being a kaitiaki means taking a coordination role - building networks so everyone stays informed about risks and can participate in responding when they choose. “The key for us is to unlock the extensive amount of knowledge of those who live here and bring them on the journey.”
Among the situations she has been active in, iwi and hapu called for a Rahui on the Whangaroa scallop beds and went on to successfully advocate for the closure of the Scallop 1 area to harvesting.
Having just met in March for the first time, the Steering Group’s priority is to get on with operationalising the National Strategy for Exotic Caulerpa. Nyze wants this to happen “in a targeted and deliberate manner, so the resources are well-spent and the objectives are being hit… I’m excited and ready to roll.”
OUR PEOPLE – Dave Pickering – Scientific diver
View a profile of Dave Pickering in Dive Pacific’s online newsletter. Dave, from the marine biosecurity team at Waikato Regional Council, is urging recreational divers to get involved in reporting exotic caulerpa sightings.
COMING UP – Revive Our Gulf Community Forum, 28 April
The next quarterly Revive Our Gulf Community Forum on Exotic Caulerpa will be held on Tuesday 28 April. Presentations will include updates from Biosecurity New Zealand, the latest research from the University of Auckland, a UV-C treatment update from Advanced Aquarium Technologies and iwi-led response insights — including from recent surveillance work from Aotea Great Barrier Island. Biosecurity New Zealand will report in its exotic caulerpa work programme. Use this link to sign up for this hui.
COMING UP – Seaweed workshops - Russell and Aotea
In mid May, Dr Roberta D’Archino of Earth Sciences New Zealand, Biosecurity New Zealand and partners will lead Seaweed workshops for interested public, in Northland and on Aotea Great Barrier Island. The workshops will cover: how to identify exotic caulerpa and other key seaweed species, how to report problem species, and an update on the exotic caulerpa situation and management. The workshops will be held in Russell, Bay of Islands on the evening of Thursday 14 May and twice on Aotea during the afternoons of Saturday 16 and Sunday 17 May. Further details will be shared via this newsletter mailing list closer to the time.
COMING UP – Hutchwilco Boat Show site in May
Biosecurity New Zealand Caulerpa Programme team members will be on the Protect Our Paradise stand (451) at the Hutchwilco Boat Show – being held at Auckland Showgrounds from Thursday 14 to Sunday 17 May.
Nāku noa, nā – The Exotic Caulerpa Programme team on behalf of the exotic caulerpa management partners.
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For more information about exotic caulerpa seaweeds in New Zealand visit the Ministry for Primary Industries Biosecurity New Zealand website.