Te Ana Marina Stunned by Discovery of 600 Fanworm

27 March 2024

Lurking beneath the surface of the water in Lyttelton Harbour is a large, tube-dwelling worm that attaches itself to vessels and structures.

This Mediterranean Fanworm (Sabella) was detected in Lyttelton Harbour in 2008, the first time it was found in New Zealand.

It likely originated from a vessel travelling from overseas. The fanworm grows in dense clumps and, with its fan-like appendage, blocks light and food to native species, starving them.

Over the years, Biosecurity NZ, the Canterbury Regional Council (Environment Canterbury) and Lyttelton Port Company (LPC) have undertaken efforts to reduce the fanworm population within the inner harbour and stop the spread into the wider Lyttelton Harbour and beyond.

In 2021, LPC and contract divers removed 900 fanworm from the jetties and pontoons in the inner harbour.

Six-monthly surveillance since this time has shown that the population is increasing again.

Part of the rationale for removing Jetties 4, 5 and 6 was to remove a potential source population of fanworm.

To date, 210 fanworm have been removed with the jetty piles.

A recent dive survey of Lyttelton Harbour, jointly funded by Environment Canterbury and Biosecurity NZ, has shown very little spread of fanworm outside the inner harbour, which is good.

Recreational vessels are the biggest source of spread.

600 Fanworms found at Te Ana Marina

Environment Canterbury funded fanworm removal at Te Ana Marina.

Over two days, divers hand-picked 600 invasive fanworm from the pontoons, piles and vessels at the marina.

The biggest worm found was 70cm long.

LPC is working on a Te Ana Marina Biosecurity Plan, and the marina team are doing a great job screening new vessels that wish to visit. Vessels must prove they have a clean hull before entering the marina and maintain this during their stay.

Ngāti Wheke is strongly advocating for a clean hull policy for Lyttelton Harbour. With collaboration between organisations, we are hoping to reduce the risk of fanworm within Lyttelton and stop the spread to other locations.