Photo / Richard Ling, Wikimedia Commons

Exotic caulerpa, the invasive seaweed, has been detected in several new locations outside of the existing Controlled Area Notices (CAN).

These new affected sites include Bowling Alley Bay, the Broken Islands, Shag Point, and the eastern coast of Kaikoura Island. 

The current Controlled Area Notice has been implemented over Blind Bay, Tryphena Harbour, and Whangaparapara Harbour, making it illegal to fish or anchor a vessel due to the seaweed's presence.

We have asked MPI if they plan to increase the CAN area.

Ngāti Rehua/Ngāti wai ki Aotea, last week lodged a complaint against the Crown with the Waitangi Tribunal over its handling of Caluerpa since it arrived on Aotea in 2021.

It has since spread to Te Tai Tokerau (Northland), and Kawau island in Tāmaki Makaurau (Auckland).

The grievance cites the Crown’s negligence in controlling the spread of the marine pest, leading to the degradation of the waters. 

The tribe claims that inaction directly undermines its rights under Te Tiriti o Waitangi.

Biosecurity New Zealand says it's been working with mana whenua and other partners including local authorities to control the pest 'where possible'.

Last week north Auckland iwi Ngāti Manuhiri called in Californian scientists to help rid their coastline of caulerpa.

The group had some success using chlorine tablets under tarpaulins, although Ngāti Rehua/Ngāti wai ki Aotea says they strongly favour a mātauranga Māori led approach.

See it, snap it, report it

The seaweeds Caulerpa brachypus and Caulerpa parvifolia, although distinct, appear identical. 

Characterized by green fronds that resemble oar blades and rise from lengthy roots or stolons, they can establish themselves between 2 and 30 metres below the tideline. 

Their rapid proliferation results in them forming dense underwater mats, competing with native species and disturbing local marine ecosystems.

Boaters and marine enthusiasts are urged to be vigilant. The seaweed can hitch a ride on anchors, chains, and equipment, making its spread swift and far-reaching. 

Before changing locations, all marine equipment should be inspected and cleared of any seaweed. If any seaweed is found post-trip, it should be disposed of in the rubbish – reintroducing it to the sea could exacerbate the issue.

The Ministry for Primary Industries (MPI) is asking anyone who spots the invasive seaweed to snap a photograph and note the location. 

Reporting can be done via freephone at 0800 80 99 66 or through the online form at report.mpi.govt.nz.