Marine pest surveys start in Waikato coastal marine areas

A dive team has started surveying the Waikato’s coastal marine areas to determine the presence and extent of marine pest species. 

The divers started in the Coromandel Peninsula this week, after which they will be checking the west coast Port Waikato, Raglan and Kawhia harbours.

This biosecurity surveillance work particularly targets marine pests Mediterranean fanworm (Sabella spallanzanii) and clubbed tunicate (Styela clava).

Marine pests are mainly spread by heavily fouled vessel hulls so the dive team will target pathways of boats and check vessels, marine structures (marinas, wharves, jetties and moorings), popular anchoring spots and mussel and oyster farms.  If infested vessels are found, owners may be requested to remove and antifoul them.

Previous surveys have shown the west coast harbours and the eastern side of the Coromandel to be free of marine pests, however, the west coast of the peninsula is not so good. The natural spread of Mediterranean fanworm is continuing up the coast from the Coromandel Harbour. At the time of the last survey, in 2018/19, fanworm was found as far north as Colville, up from Papa Aroha the previous two years.

This surveillance period, the dive team will be keeping an eye out for the invasive seaweed Caulerpa parvifolia after it was discovered off the coast of Ahuahu/Great Mercury Island last year.

The council regularly checks for marine pests to see how much of a problem they are. Please help prevent their spread: make sure your hull has been checked, cleaned and antifouled before heading away.

Don’t know what a marine pest is?  Check out marinepest.nz for some of the pests we look out for.

Controlled Area Notice and rāhui at Aotea Great Barrier Island and Ahuahu Great Mercury Island

To minimise the spread of Caulerpa species, Biosecurity New Zealand has placed a Controlled Area Notice (CAN) on three affected harbours at Great Barrier Island (Blind Bay, Tryphena Harbour, and Whangaparapara) and the western bay of Ahuahu Great Mercury Island. Mana whenua have imposed a rāhui in the same areas. The CAN and rāhui are in place until 30 September 2022.

Biosecurity New Zealand is reviewing all information gathered on Caulerpa brachypus and Caulerpa parvifolia since they were discovered in New Zealand a year ago. The review will inform future controls to best manage the risk of spread, while taking into account the effect of any requirements on communities and other marine users.

To find out more about Biosecurity New Zealand’s Caulerpa response and what the CAN and rāhui mean for recreational water users, or to subscribe to updates about the response, click here.