Possible Mediterranean fanworm discovered in Bluff Harbour
Environment Southland has been notified and is investigating the discovery of a possible single Mediterranean fanworm (Sabella spallanzanii) in Bluff Harbour during routine surveillance carried out by NIWA between 7 and 11 July.
The worm, measuring 59 cm in length, was found under the town wharf at a depth of five metres. The specimen was collected and sent for formal identification.
Environment Southland acting general manager integrated catchment management David Adamson said that while no further specimens were detected during follow-up dives, the wharf’s extensive structure means further surveillance is required to determine the extent of the spread.
“We’re unclear if the marine pest is more widespread in Bluff waters, so we’re planning further surveys to confirm its spread as a part of response planning.”
To support this response, divers experienced in identifying Mediterranean fanworm will be brought in from outside the region. Environment Southland are also receiving support from Biosecurity New Zealand.
The Mediterranean fanworm is a segmented marine worm that forms dense colonies, displacing native species and threatening fisheries. It attaches to solid structures such as wharf pilings and aquaculture equipment, potentially increasing harvesting and fuel costs. It competes with mussels and oysters for food, affecting their growth and viability.
The worm has a long, leathery tube that is pale brown with a muddy appearance and extends a spiral fan of yellow-orange filaments to collect food particulars, such as plankton. It can regenerate quickly and persist in a range of water temperatures and salinity, living for 2–5 years. Its larvae can remain in the water column for up to 20 days before settling.
Environment Southland is asking the public and marine industry to keep an eye out and report any suspected sightings.
“Our goal at the moment is to establish whether it is Mediterranean fanworm and if it has spread. We want the public to continue to be vigilant and report sightings, as well as ensure their gear and hulls are clean.
“We also need to know if this pest is elsewhere in Southland.”
If you think you’ve seen it, please take a clear photo and email it to service@es.govt.nz with your contact details. Our team will follow up to gather more information.
Reports can also be submitted via the Southland PestHub (pesthub.es.govt.nz).
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For further information contact the communications team on 0800 76 88 45 or communications@es.govt.nz
Notes to editor:
The Mediterranean fanworm is larger than native fanworms in New Zealand. Tubes typically grow to 10–50 cm, though specimens up to 80 cm have been recorded. The worm’s distinctive spiral fan is used to filter plankton from the water.
