Alarm over marine pest invasion

EVIDENCE: Fanworms removed from the hull of the infested boat.

Whangaroa Harbour users are calling on authorities to act urgently to halt the spread of an invasive marine pest they say will wipe out jobs and native species.

A fishing boat moored at Whangaroa's Clansman Wharf, the 22m Catherine II, was last week found to be infested with hundreds of Mediterranean fanworms.

Auckland's Waitemata Harbour is already so badly infested with the vigorous sea creature that the Ministry of Primary Industries has given up trying to get rid of it. It is also present in Whangarei Harbour - Marsden Cove marina is locked in a costly battle with the worm - but until now it had not been seen north of Tutukaka.

The fanworm forms dense clumps that crowd out other filter-feeding species, such as shellfish, sponges and sea squirts, and deprive them of food by sucking nutrients from the water. Their rapid growth and sheer weight can also cause problems for boats and floating pontoons.

Whangaroa marina manager Pete Sehmb said 20 families depended on the harbour's oyster farms for work, but those farms could be destroyed if the fanworm became established. The cost of keeping it out could also spell financial ruin for marinas.

Northland Regional Council aquatic biosecurity officer Irene Middleton said divers carrying out an inspection in Whangaroa Harbour found the infested boat on Wednesday. No fanworms were found on harbour structures.

The council originally wanted the vessel hauled out and cleaned at Opua, but because of its size the first suitable tide was Monday next week. That was too long to wait, so Whangarei dive firm Northland Underwater Technical Services (NUTS) was tasked with removing the worms by hand.

Because fanworms could regenerate from fragments, each one had to be covered with a sealable plastic bag before it was pulled off the hull. The vessel will still have to go to Opua for a full clean, with all costs met by the owner.

Three divers took two hours to remove about 300 fanworms on Friday. They have been sent to a laboratory to determine if they were sexually mature and could have spawned in the harbour.

Catherine II owner Guy Weston-Webb said the boat had been hauled out and professionally anti-fouled on November 28, which should have given at least six months' protection against marine pests. The vessel must have become infested when it stopped in Auckland for a few nights three weeks later.

The fanworms could be the last straw for a business already weighed down by red tape and costs, he added.

Whangaroa marina trustee Geoff Mahon said the owner and crew were not to blame.

"They're victims in this. There's not even a sign up at Auckland saying, 'There's fanworm here, you might get it'," he said.

"We'd dearly love the NRC, or some public authority, to create public awareness. The government spends mega-bucks on drink-driving campaigns, but this is also a serious problem. The aquaculture industry, and millions of dollars in tax take, is at risk."

MPI had decided the fanworm could not be eradicated from Auckland, so responsibility for stopping its spread fell to regional councils, which did not have the resources required, Mr Mahon said.

He urged the ministry to give regional councils the resources they needed to fight the invasion and conduct a major publicity campaign.