Current situation and legal restrictions
Response actions and decisions are informed by scientific advice. Since the discovery of exotic caulerpa in New Zealand in 2021, groups of international technical and scientific advisors with expertise in marine algae, control methods and Mātauranga Māori, have convened to advise on the situation and recommended actions.
The first Technical Advisory Group (TAG) met in December 2021 to provide advice on the incursion in New Zealand and the most appropriate response to its discovery.
The group's report, dated February 2022, concluded that the scale of the incursion is beyond that at which successful eradication has ever been achieved internationally; and that eradication within each infected area is also not possible with the current set of tools available.
The group concluded that the most appropriate course would be to aim for suppression and containment, with a long-term management plan required to limit further spread.
In June 2023, an advisory group gathered to provide advice on the use of diver-controlled suction dredging to remove exotic caulerpa.
The group recommended an immediate scientific trial to provide vital information on the method's potential in our unique environmental conditions and the remote locations of our caulerpa infestations. Trials are about to start at 2 locations – Aotea Great Barrier Island and Te Rāwhiti Inlet in coming weeks (dated 20 July 2023).
Biosecurity New Zealand commissioned NIWA to assess the impacts of exotic caulerpa on the ecosystem and taonga species at Aotea Great Barrier Island.
In a multi-year study, NIWA is monitoring 18 permanent sites in the 3 affected bays at the island - Blind Bay, Tryphena Harbour and Whangaparapara Harbour.
They are looking at any effects on native species, as well as how the caulerpa itself is affected by wave energy and light availability, including storms.
In an interim report, observations suggest that exotic caulerpa may be having a negative impact on the condition and population dynamics of taonga species. However, there is further sampling and analysis required before the extent of any impacts on most of the habitats will be known.
NIWA returned to the sites in May 2023. The report from this phase of the research project is still in development.