A four-strong dive team has embarked on $100,000 programme to rid Opua of Mediterranean fanworm.

The eradication effort is led by the Northland Regional Council, with support from Biosecurity New Zealand, part of the Ministry for Primary Industries. The dive is the first part of a planned staged attempt at the eradication.

Regional council biosecurity manager Don McKenzie said contractors discovered a single specimen of the marine pest while working in the Opua area in early July.

The Mediterranean fanworm Sabella spallanzanii is unwanted because it can quickly form dense colonies, forcing out native species and interfering with their ability to feed and breed. It had been found growing on scallops in Whangārei Harbour and has the potential to spread on to other shellfish.

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McKenzie said divers were immediately called in to investigate the July Bay of Islands find, discovering – and removing – more than 100 fanworm from the Opua Marina and the surrounding area over the next several weeks.

The divers were then stood down as biosecurity experts analysed the findings and considered the best management approach. The fanworm is thought to have been in the area for several years, probably hitchhiking in on a visiting vessel.

The regional council then committed $60,000 toward the month-long, weather-dependent effort to try to eradicate the pest. Once finished, results from the latest eradication attempt will be reviewed again before further work is considered.

The funding from the council paid for the Commercial Dive Specialists team's time and Biosecurity New Zealand was also contributing $40,000 to the current removal attempt.

"Essentially, this is a 'step-wise' eradication approach, with a review at the end of each round of diver search and destroy effort, to consider what progress has been made and whether continued work is justifiable both economically and practically," McKenzie said.

No one involved was under any illusion as to the scale of the task they face, he said.

"However, our councillors and Biosecurity New Zealand felt that given the importance of the Bay of Islands across multiple fronts – including environmentally, economically and culturally – they could not pass up what may be our only real opportunity to attempt to rid the area of fanworm."

Mediterranean fanworm is unwanted because it can quickly form dense colonies, forcing out native species and impacting shellfish.
Mediterranean fanworm is unwanted because it can quickly form dense colonies, forcing out native species and impacting shellfish.

The council reiterated its earlier messages to boaties that it's vital to ensure their vessel and any associated equipment – moorings and their rope/chain and fishing nets – is clean and free from fouling which may contain marine pests.

McKenzie urges people encountering marine pests to notify the regional council as soon as possible by phoning (0800) 002-004.