Tackling the invasive seaweed Caulerpa in Northland

09:35 am on 5 July 2023

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NRC marine biosecurity officer Toby Dickson attaches the edge of a heavy tarpaulin mat to the Albert Channel seafloor in the New Zealand-first caulerpa treatment trial set up in the Bay of Islands on 13 June 2023. Photo: Supplied/ Brett Sutton, Marine Environmental Field Services

Caulerpa is an invasive exotic seaweed that can grow from a speck to the size of a rugby field in a matter of weeks in the right conditions, smothering everything in the water column.

The seaweed called Caulerpa has been found in waters at Great Barrier Island (Aotea), Great Mercury Island (Ahuahu), and the Bay of Islands, and is worrying marine experts. 

A collaborative project between the Northland Regional Council and MPI is now underway to try to tackle the Caulerpa problem in the Bay of Islands. 

They're taking a two-pronged approach to fight the invasive species, sinking swimming pool chlorine pellets, and nailing down tarpaulins in the Albert Channel.

Kathryn speaks with John Walsh, MPI's Director of Response and Kaeden Leonard Northland Regional Council's Marine Biosecurity Manager. 

If you spot Caulerpa, take a photo, record your location and phone the Pest and Disease Hotline at 0800 80 99 66 or complete the online reporting form at report.mpi.govt.nz.