An investigation has been launched by Environment Southland following the marine pest, Mediterranean fanworm (Sabella spallanzanii), being potentially found in Bluff Harbour this month (Jul).

The Mediterranean fanworm, a segmented marine worm that forms dense colonies on solid structures, can displace native species and threaten fisheries like mussels and oysters as it competes for food.

It is identified by its long, leathery tube that is pale brown with a muddy appearance and extending spiral fan of yellow-orange filaments.

The worm can regenerate quickly and persist in a range of water temperatures and salinity, living for 2–5 years, while its larvae can remain in the water column for up to 20 days before settling.

The worm that was discovered in Bluff Harbour measured 59 cm in length and was found under the town wharf at a depth of five metres followed routine surveillance carried out by NIWA between 7 and 11 July. It has been sent away 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.”

Divers experienced in identifying Mediterranean fanworm will be brought in from outside the region, Adamson said.

Environment Southland are also receiving support from Biosecurity New Zealand.

“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.”

Environment Southland is asking the public and marine industry to keep an eye out and report any suspected sightings.

If you think you’ve seen it, please take a clear photo and email it to [email protected] with your contact details, Adamson said.

Reports can also be submitted via Southland PestHub (pesthub.es.govt.nz).