Public meeting on Whangarei Harbour marine pest spread

A public meeting on marine pests and how we can all help prevent their spread in Whangarei Harbour is planned for early next month.

The 7-9pm Thursday April 07 meeting at the McLeod Bay Hall has been called by the Northland Regional Council after summer dive surveys revealed Mediterranean fanworm on boat hulls and mooring lines at Parua Bay.

An internationally recognised marine animal pest that competes with native filter-feeding species like scallops and mussels, the fanworm can heavily foul marinas and other structures and may impact on farmed shellfish.

Council chairman Bill Shepherd says since the discovery (by divers contracted by the council) fanworm had also been found on rocky substrates and on the seafloor in the area.

Councillor Shepherd says the pest is common in other parts of New Zealand, including Auckland and was first found in Whangarei Harbour several years ago.

"The regional council, biosecurity experts, marine industry and boaties have been working hard since to try to stop its spread in our region and have implemented a number of initiatives in this regard."

"However, the unfortunate reality is fanworm is predicted to eventually establish in other bays within Whangarei where the habitat is suitable."

"We urge vessel owners within Whangarei to ensure their boat hulls are maintained by ensuring fresh antifouling or a regular 'lift and wash'. When our staff are made aware of fanworm, the owner is directed to clean the hull."

Councillor Shepherd says fresh antifouling or regular lifting and washing helps prevent pests from attaching to boats.

"We must avoid these vessels carrying marine pests to our most pristine places. Other Northland harbours are currently fanworm-free, but there is a very real risk of these pests being transported to them or into other special places like the Hen and Chickens and Poor Knights Islands"

He says marine pests like fanworm exploit niche areas on the hull where antifoul is often at its weakest.

"This means the very base of the keel and around prop housings, intakes, and grills and are places that all need extra attention."

Councillor Shepherd says surveys conducted in other harbours over summer showed a high proportion of vessel hulls were carrying significant levels of biofouling and divers had discovered several with marine pests including the sea squirt Styela clava and fanworm on their hulls.

"Unfortunately, it's very clear vessels are carrying more than just a slime layer and we are urging boaties to take extra care to prevent these marine pests spreading. Again, only fresh antifoul or a lift and wash will stop these marine hitchhikers."

Councillor Shepherd says some councillors will attend the April 07 McLeod Bay meeting, which will include presentations from council biosecurity staff on the fanworm find and other marine pests in Northland. Pamphlets and other information on marine pests will also be available on the night.