Council and marinas wage war on marine pests

NASTIES: Mediterranean fanworms are some of the marine pests being checked for on boat hulls in Northland this summer.PHOTO/FILE

About 1500 boat hulls are expected to be checked at popular holiday spots in Northland this summer for marine pests.

That number is almost three times more compared with checks last summer when 400 vessels were inspected by the Northland Regional Council's dive contractors.

Council chairman Bill Shepherd said the region's marinas were also playing their part in the war on marine nasties and were now insisting on tougher entry criteria.

Dive contractors Vince Kerr and Associates will have a four-strong team checking vessels for a range of marine pest animals and plants including Mediterranean fanworm, the sea squirt Styela clava and the seaweed undaria.

Depending on the pests found, owners will be asked to haul the vessels out and clean or treat them in what can potentially be a costly process.

"As well as reducing the risks from a biosecurity perspective, it also makes good financial sense to check your vessel carefully before heading to Northland," Mr Shepherd said.

Other parts of New Zealand, including Auckland, have populations of unwanted pests like Mediterranean fanworm and the council's usual message for boaties was to check their vessels' hulls before venturing north remained, he said.

Northland's marina operators have come up with a plan to protect their own assets from marine pests and now required evidence of a clean hull before they allowed entry.

"Operators will need to see a receipt proving a vessel conforms to what's been dubbed the 'six or one' initiative; being either antifouled within six months of leaving a known fanworm-infected area or having undergone a 'lift and wash' within one month of leaving an infected area like Auckland."

However, some vessels that have adhered to the recommended "six or one" messaging have still encountered issues with fanworm surviving in "niche" areas antifoul has not reached.

"Marine pests can be concealed in these niche areas and can easily be missed during antifouling or cleaning. We strongly suggest you double-check areas like the base of the keel, behind anodes, and the bow thrusters before your vessel goes back in the water."

Mr Shepherd said in recent months, council staff have found fanworm in previously uninfected areas including Tutukaka, Whangaroa Harbour and Parua Bay, which reinforced the need for extra vigilance.

-General information on marine pests can be found at www.nrc.govt.nz/marinepests.