Marine pest surveys in five Wellington marinas reinforce the need for boaties to clean boat hulls before travelling

The discovery of Mediterranean fanworm on three boats in the Wellington region highlights the need for boat owners and marina operators to be vigilant to avoid the spread of invasive marine pests. Heavily fouled vessels will be prevented from entering other regions over the summer.

Greater Wellington (GW) and Top of the South (TOS) Marine Biosecurity Partnership conducted an initial Level of Fouling (LOF) boat hull survey from 2-5 December 2024 at Chaffers Marina, Clyde Quay, Evan’s Bay Marina, Seaview Marina, and Mana Marina. 

A yacht at Chaffers Marina was found to have a solitary Mediterranean fanworm, as was a yacht berthed at Seaview Marina. Two Mediterranean fanworm were found on a yacht in Mana Marina. None of the fanworm were reproductively mature and all were successfully removed by divers.

 Mediterranean fanworm is an Unwanted and Notifiable Organism under the Biosecurity Act 1993 and is not established in the Wellington Region.

“Finding these fanworm highlights the benefits of the GW partnership with TOS and the importance of developing a new Marine Biosecurity Programme, which aims to protect marine environments,” says Dr Megan Melidonis, Senior Coastal Scientist at GW.

“Greater Wellington currently does not have pathway management rules and marine pest species listed in our Regional Pest Management Plans. We rely on local marina clean hull rules and pathway management implemented by other councils.”

Although the inspection of hard structures was not part of the December survey, divers searched jetties and piles immediately adjacent to the fanworm-infected boats and no fanworm were found.

“It is important to note that not every vessel in the five marinas was inspected during this survey,” says Dr Melidonis, “and there is the possibility that Mediterranean fanworm may exist on vessels not inspected. That’s why we want to remind boat owners how important it is to regularly clean and antifoul their boats.”

Mediterranean fanworm is primarily brought to new locations by vessel biofouling and can spread quickly after spawning, forming dense colonies that outcompete native organisms for space and food. These filter feeders and other marine pests can negatively impact marine environments. When attached to vessels, marine pests may increase fuel costs due to increased drag, and cause infestation of other areas currently free of the unwanted marine pest.

Top of the South Marine Biosecurity Partnership is a regional partnership to prevent marine pests from being introduced or established in the marine environment, manage established pests, and respond efficiently to new incursions when they are detected. It aims to ensure marine users clearly understand good practice, as well as conducting surveys and responding to incursions. The Partnership is led by Tasman District Council, Nelson City Council, Marlborough District Council, Greater Wellington, and Biosecurity New Zealand. 

What to do if a suspected marine pest is found:

In Greater Wellington, report suspected marine animal or marine plant pests to Biosecurity NZ by calling the BNZ Exotic Disease and Pest Hotline 0800 80 99 66 or log it online. Include a photo and record the location of the organism.