Restrictions in place for parts of Waiheke Island; new location found near Kawau

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.

Map showing the Waiheke Island controlled area which extends from the western point of Mawhitipana Bay, north including Nani Island, northwest to 500m off Thompson Point and finishing at Waihihi Point on the eastern side of Onetangi Bay. It includes the marine waters up to and including the high-tide mark and to a depth of 22 metres.

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 knotiki 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.

New area of exotic caulerpa confirmed at Kawau Island

Exotic caulerpa has been confirmed at a second location at Kawau Island in the Hauraki Gulf.

There is an existing area of exotic caulerpa at Iris Shoal, to the north-west of the island.

NIWA divers surveyed Bostaquet Bay on the south coast of the island following reports of suspected caulerpa by University of Auckland divers.

The dive team examined six locations in the bay covering areas of seabed from 5-24 metres deep and across a range of substrates including sand, gravel, shell, reef and muddy sand.

Exotic caulerpa was confirmed in five out of those six locations, showing up in small, sparse patches but distributed across a wide area.

A team with representatives from mana whenua, Biosecurity New Zealand, Department of Conservation, Auckland Council and Revive our Gulf has formed to organise further surveys to help understand the extent of the infestation and to consider next steps. This could include removal with existing tools such as benthic mats.

Boaties are asked to, where possible, avoid anchoring and fishing in Bostaquet Bay as exotic caulerpa can be spread as fragments snagged on anchors, anchor chains and fishing or diving gear.

In any area, before moving location, check the anchor, chain and fishing or diving equipment for attached seaweed. Remove it, bag it and dispose of it ashore.

For more information:

For detailed information about the caulerpa response go to: www.biosecurity.govt.nz/caulerpa

Find out about exotic caulerpa in Northland

View a map of places caulerpa has been found in the Auckland region and Coromandel