Skip to main content
Last reviewed:

Keep your boat and gear free of any seaweed before moving locations

Exotic caulerpa can get snagged on anchors, chains and dive and fishing gear and be accidentally moved to new locations. There are simple actions you can take to avoid this.

  • When out at sea – before leaving a location, check your vessel’s anchor and anchor chain, and any equipment you’ve used in the water for any tangled seaweed. If you have an automatic retrieval system, still look out for any attached pieces of seaweed.
  • If you find any type of seaweed – remove it, bag or contain it securely so it can’t get back into the water, and take it ashore for disposal in a rubbish bin.
  • If you can’t securely contain it so it can’t get back into the water – put it back into the water it came from.
  • If you find you’ve picked up seaweed when you’re back at shore – remove it and put it in the rubbish.

What is exotic caulerpa?

Learn more about this pest seaweed and why it's a risk

Help us locate exotic caulerpa

Exotic caulerpa can be found on the seabed, particularly on rocky areas, and occasionally on sandy seafloors. Sometimes it can be found washed up onshore – for example, after a heavy storm.

Seaweed on rocks.
Caulerpa on rocky substrate. Photo: Auckland Council
Little light green seaweed growing in sand.
Sparse caulerpa coverage on a sandy seabed. Photo: NIWA
Ball of seaweed on rocks and sea water.
Beach cast on rocky shore. Photo: Hannah Smith

Tell us if you find any exotic caulerpa

Report suspected sightings:

Follow the legal rules in some caulerpa locations

There are legal restrictions on some anchoring and fishing activities in waters at Aotea Great Barrier Island, Ahuahu Great Mercury Island, Waiheke Island, Hauturu Little Barrier Island, and Te Rāwhiti Inlet in the Bay of Islands.

These rules, called Controlled Area Notices (or CANs), are in place because anchoring and some types of fishing pose a high risk of spreading exotic caulerpa from areas of infestation.

Check the legal rules in force to stop the spread of exotic caulerpa

Information leaflets about the CANs

Information about exotic caulerpa and the legal rules for the Hauraki Gulf area [PDF, 3.7 MB]

Information about exotic caulerpa and the legal rules for Te Tai Tokerau Northland [PDF, 6.1 MB]

MPI business units