Fanworm pest elimination programme to close

Fanworm pest elimination programme to close

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.”

For further information, see Questions and Answers below.

--

Mediterranean fanworm (Sabella spallanzanii) Questions and Answers

What is the Mediterranean fanworm?
The fanworm is a marine tube worm that attaches to hard underwater surfaces and builds itself a sandy/leathery tube in which it lives. It protrudes from this tube when filter feeding from the water, and withdraws into it when disturbed. This particular fanworm can grow to approximately 40cm in length. Full information about it, including pictures, is at: http://www.biosecurity.govt.nz/pests/mediterranean-fanworm

What are its impacts?
The Mediterranean fanworm can form dense populations, potentially out-competing native species for space and food, and may pose a nuisance for aquaculture operations. MAFBNZ attempted the elimination in Lyttelton as a precautionary measure as there is uncertainty around how it would behave in the New Zealand environment. Overseas experience had found the species to be fast growing and invasive.
What did the Lyttelton programme involve?
The programme involved rounds of treatment by dive teams whereby all piles and structures in the inner Lyttelton harbour were thoroughly inspected, and where specimens of the fanworm were detected, they were removed. The aim was to reduce the population of the fanworm in the port to a level where it could no longer reproduce and sustain itself. Since the first detection of the Mediterranean fanworm in March 2008, divers have searched the more than 6,000 wharf piles in Lyttelton Port at least twice each, removing a total of 344 fanworms.

In between treatment rounds, regular marine surveillance of the port area was also carried out.

How much did this work cost?
Up until the treatment was put on hold following the discovery of the wider Waitemata population, approximately $1.3 million of the allocated $3.5 million had been spent.

Was this money wasted?
No. The money was committed at the time because it was considered that an attempt to eliminate the pest was feasible and responsible. When it became evident that we could no longer contain the fanworm in New Zealand, we re-considered the programme. While it was not successful in eliminating the fanworm, the Lyttelton programme provided useful marine biosecurity knowledge and evidence that the treatment method employed could be used again where a marine pest presents in a small number in a contained area. The information gained may well help us plan for an eradication of a marine pest in, for example, a very high-value site (such as a marine reserve or a marine farming area).

Did the fanworm spread from Lyttelton to Auckland?
We will never know for sure, but the age of the worms found in the Waitemata indicates that the Auckland population possibly pre-dated the Lyttelton group.
Why is it not feasible to have a go at eliminating this pest from the Waitemata?
The projected costs of extending the elimination to such a widespread geographical area were simply not justified by the known impacts. It would also be extremely difficult to locate and remove the fanworms using divers from an area that is over 10,000 hectares in area. By comparison, the Lyttelton Port area is around 50 hectares in area.

Why has it taken nearly six months from the find in the wider Waitemata to make this decision?
The decision has not been taken lightly and has required careful consideration of the conservation issues at stake, balanced against the financial information. All this has been compounded by the uncertainty around the actual impacts on the New Zealand environment. We know the species has proved invasive overseas, but we had no real certainty around how it would behave in New Zealand waters.

Does this situation mean future marine response actions will be limited?
MAFBNZ will continue to respond to marine pest detections based on sound risk analysis and the feasibility of any eradication attempt. We will continue, through our targeted marine pest surveillance, to look out for those pests that we know could have serious impacts on New Zealand’s economy or environment. The earlier populations can be found, the greater the opportunity to treat them.

How can the public help?
We ask those who work and play in and around the marine environment to keep an eye out for anything unusual they may find in the ocean or on the waterfront. Such finds can be reported to 0800 80 99 66. Again, early detection affords a greater opportunity to eradicate.

Those who own boats have a particular role to play in ensuring they don’t transport marine fouling pests from one location to another. This can be prevented by ensuring boat hulls are kept clean (with no more than a light slime layer on board) and thoroughly antifouled.

ENDS

© Scoop Media