Exotic Caulerpa

CAN in place at Waiheke Island

New biosecurity controls are in place over an area of Waiheke Island waters to prevent the spread of the invasive seaweed exotic caulerpa.

The controlled area notice (CAN) comes into force at midnight tonight and sets legal requirements for some fishing and boating activities in an area around Thompson’s Point and across Onetangi Bay. This is the area of Waiheke Island where exotic caulerpa has been found.

Within this zone (see map below), people will still be able to anchor but must follow equipment cleaning directions before they leave the controlled area.

The law requires boaties to check their anchor, anchor chain and any equipment used in the water for attached seaweed or plant material. This includes, for example, diving and fishing gear, wetsuits and fins.

Any seaweed found must be removed, bagged or securely contained, and taken ashore for disposal in a rubbish bin. If secure containment isn’t possible, it can be put back into the waters it came from. The important thing is that it is not taken to other waters outside the controlled area. The equipment should be washed down with fresh or seawater and, where possible, left to dry before being used in another area.

Launching vessels, including amphibious Sealegs-type craft is permitted, as is motoring or sailing through the waters of the controlled area.

The controls at Waiheke are not as restrictive as those for the Aotea and Te Rāwhiti CAN zones because the caulerpa is less dense at Waiheke.

The CAN also restricts some types of fishing activities that risk spreading caulerpa.

You must not fish in the area using any method that makes contact with the seabed and can potentially snag and relocate caulerpa. This means no netting, dredging, bottom trawling or potting.

Line fishing from the shore or drift fishing from a vessel, spear fishing and hand gathering, and shore-based longlining – for example from a kontiki or drone – are all allowed.

Biosecurity New Zealand has engaged with a range of partners and groups on a proposal to introduce a CAN in the area for some months. This has included Ngāti Paoa, the Local Board, Auckland Council, the Waiheke Marine Project, the local tourism sector and representatives of Auckland yachting and boating clubs. All agreed some controls were necessary.

Tighter restrictions, including, potentially, a ban on anchoring, were initially considered. However, in a new development, a decline or reduction event has been confirmed at Waiheke. As a result, a less stringent CAN is now considered appropriate.

CANs are an important tool to help prevent the spread of exotic caulerpa. This pest seaweed can spread over long distances as small pieces, caught on anchors, anchor chains and other equipment including fishing and diving gear. It’s interesting to note that most of the locations it has been found in are popular anchorages.

Updated 16 December 2024