Auckland boat brings marine pests to Pilot Bay

20 November 2014

An Auckland boat infested with the marine pests Mediterranean fanworm and clubbed tunicate sea squirt was discovered on a Pilot Bay mooring in Tauranga Harbour last week.

The discovery was made by Bay of Plenty Regional Council contracted divers during the first round of a new proactive marine pest surveillance programme in the Tauranga Harbour.

“We’ve been negotiating with the boat owner to get it hauled out and cleaned as soon as possible,” said Regional Council Biosecurity Officer Hamish Lass.

The vessel was brought to Pilot Bay from Auckland in December last year. It is estimated to be carrying more than 100 individual fanworms on its hull, as well as a number of clubbed tunicate sea squirts. Both pests are classified as Unwanted Organisms under the Biosecurity Act 1993 and are a threat to seafood stocks, aquaculture and local marine life because of their growth and feeding habits. They can also cause costly damage to boat equipment and marine structures.

The unwanted fanworm and sea squirt have become well established in Auckland’s Waitemata Harbour. They are easily transferred to new areas by taking hold on hull fouling and then spawning or being knocked off in a new location, or through the transfer of ballast and bilge water.

“It’s frustrating that the boat owner didn’t clean his boat hull before travelling to Tauranga, or even when he arrived here. He moored up just after we’d completed our last round of dive surveys in Pilot Bay and found it clear of Mediterranean fanworm,” said Mr Lass.

The latest find is the third pest-infested boat found in Tauranga Harbour since September last year.

“Mooring holders have an important role to play in preventing incursions like this. They can stop marine pests from taking hold in Tauranga Harbour by making sure that any boats they allow onto their mooring have clean hulls before they’re brought here,” Mr Lass said.

Mr Lass also said that due to the size and number of fanworms on the hull, and the duration that it’s been moored locally, it’s possible that the fanworms will have spawned in Pilot Bay during the winter and autumn spawning season.

“That will add scale and complexity to our containment efforts. We’re working with Ministry for Primary Industries to develop and implement an appropriate response. It’s likely to involve many hours of underwater searching,” he said.

Mr Lass is asking everyone who uses the harbour to keep an eye out for marine pests and boats with heavily fouled hulls, and report them immediately to him at Bay of Plenty Regional Council by calling 0800 884 880.

“We also need all moored or berthed boat owners to help prevent further spread by keeping their boat hulls clean and anti-foul fresh.”

“Mediterranean fanworms can regrow from fragments so it’s important to keep all hull debris out of the water by hauling out for cleaning, and making sure that anything scraped off is contained and disposed of to land,” said Mr Lass.

Further information about marine pests including Mediterranean fanworm is available at www.boprc.govt.nz/marinepests .

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