Fanworm pest elimination programme to close

14 June 2010

MAF Biosecurity New Zealand's (MAFBNZ) programme to rid New Zealand waters of the introduced marine pest the Mediterranean fanworm (Sabella spallanzanii) has been called off, with new information showing the pest is too widespread to eradicate.

The Mediterranean fanworm is what's known as a fouling pest. It can form dense populations, potentially smothering other native marine species and altering underwater ecosystems.

The fanworm was first detected in Lyttelton Port in March 2008, and with no other known populations at the time, Government funded a $3.5 million treatment programme to attempt to eliminate it from the port. The programme involved searching for and manually removing all specimens found.

In August 2009 a further small population of the fanworm was detected in Auckland's Viaduct Basin - five individuals on wharf structures and a heavy infestation on a barge tied up in the area. MAFBNZ decided to treat the area, including the barge, as a part of the existing programme. In January this year, however, a much larger and well established infestation was found in a number of locations in the wider Waitemata Harbour.

The chair of MAFBNZ's Response Strategic Leadership Team for the fanworm programme, Dr Doug Lush, says it is disappointing, but the scale of the Waitemata infestation means that elimination of the fanworm from New Zealand is no longer feasible.

"We looked at a number of possible options but in the end, continuing to fund this effort did not add up given the geographical spread of the pest and the high cost of what is a very intensive process to remove them. The Government has, therefore, determined that the response to the Mediterranean fanworm be stood down" Dr Lush says.

"All operations in Lyttelton Port and the Waitemata Harbour will now cease and MAFBNZ will continue to work on addressing the means of marine pest introduction and spread generally, rather than focus on one specific species."

Dr Lush says the decision is no reflection on the effectiveness of the Lyttelton programme. Regular checks as part of the effort showed that in the two years of treatment, the population there had been significantly reduced by the treatment. As well, the programme, which had cost $1.3 million to date, had demonstrated that where there are limited populations of some marine pests in confined locations, the 'search and remove' technique is likely to be an effective treatment.

"It's important to note that the closure of the fanworm elimination programme in no way rules out action against introduced marine pests in the future, but it recognises that once an organism is well established in the marine environment, it is very difficult to eliminate it.

"Boat owners and operators also have a role to play in limiting the further spread of the Mediterranean fanworm, and other fouling pests like it, around New Zealand's coastline," he says.

"These kinds of pests attach to boat hulls and can be transported from location to location. Vessel owners can avoid this by keeping their boat bottoms clean and their antifouling paint up to date and thoroughly applied."

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Last Updated: 22 September 2010

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