Bay of Plenty Regional Council is asking moored boat owners to help keep marine pests out of the Bay by regularly checking, cleaning and antifouling their hulls this summer.

Bay of Plenty Regional Council biosecurity officer Hamish Lass says by keeping boat hulls clean, owners will make it harder for pests to latch on and become more widespread.

Photo: Supplied.

'The golden rule for hull maintenance is ‘no more than light slime, all the time'. We're also asking people to re-check and clean their hull before they sail to a different area, every time,” he says.

Regional Council, assisted by Ministry for Primary Industries and University of Waikato, has been assessing boat fouling levels in the Tauranga Harbour as part of the Council's marine pest surveillance programme. Hamish says about 50 per cent of boats on Tauranga Harbour swing moorings are in need of cleaning.

'Marina berth holders are doing better. About 90 per cent of the boat hulls we've seen in Tauranga Bridge and Sulphur Point Marinas are clean enough to avoid pest attachment. Regardless of where a boat is moored, it will only take one infested boat in the wrong place, at the wrong time to create a costly problem in the Bay,” Hamish says.

Heavily fouled hulls should be hauled out for cleaning so the removed foul can be contained and disposed of on land. Haul out facilities are available at Bridge Marina.

Marine pests such as Mediterranean fanworm (Sabella spallanzanii) and clubbed tunicate sea squirt (Styela clava) have become established in parts of Auckland and Northland, but not the Bay of Plenty. Japanese kelp (Undaria pinnatifida) and Didemnumsea squirt (Didemnum vexillum) are established in the Bay of Plenty but not in other parts of New Zealand. Marine pests are known to hide on hull fouling, and can easily become established in new locations if they spawn or are knocked off there.

Because of their aggressive growth habits, marine pests can interfere with fisheries and create problems for boat owners and marine-based businesses.

'If you own a swing mooring, it's also important to make sure that any visiting boats are cleaned, preferably at their port of origin, before you let them tie-up. Swing mooring holders are required to notify the harbourmaster before loaning out their mooring,” Hamish says.

Since September 2013, when a Mediterranean fanworm was first detected in Pilot Bay, Regional Council has maintained a vigilant surveillance programme to prevent unwanted marine pests from becoming established in the Bay of Plenty. To date, five infested boats and 29 individual Mediterranean fanworms have been found and removed from the Tauranga Harbour.

The marine pest surveillance programme involves bi-annual underwater checks on 450 moorings, 800 boat hulls, 10km of marina pontoons and 1.5km of rock walls in the southern Tauranga Harbour. Boats and moorings in Whakatane and Ohiwa Harbours, and lower risk sites in Tauranga Harbour and off-shore are checked every two years.

'We can't be everywhere, all the time. We really need boat owners to protect the marine environment they love by maintaining their boats, keeping their mates honest, and watching out for new incursions,” Hamish says.

Anyone who sees a heavily fouled hull or suspicious marine life in the Bay of Plenty should report it to Regional Council by calling 0800 ST0P PESTS (0800 780 773).

A boat cleaning guide and further information about marine pests is available at www.boprc.govt.nz/marinepests