Clubbed tunicate

Report invasive plant or animal sightings

If you have seen or suspect the presence of an invasive plant or animal pest report the sighting to us.

Tunicates are commonly known as sea squirts because they contract and squirt water circulating around their body when removed from the water.

Description

A sea squirt with a long, club-shaped body up to 160mm long, on a tough stalk.
Its surface is tough, leathery, and knobbly
They can be brownish-white, yellowish-brown, or reddish-brown.
Two closely spaced siphons at the top of the body are usually surrounded by warty little bumps.
Often appears fuzzy when viewed underwater.

Clubbed tunicate can be found up to 25m deep, attaching itself to rocky coastlines, reefs, boat hulls, piers, pontoons, and aquaculture structures.

It spreads via vessels, either as larvae held in ballast water or as hull fouling and can also be dispersed as larvae being moved by water currents.

What you need to know

Clubbed tunicates can form dense colonies, competing for space and food with native species (for example mussels and oysters). They are highly effective filter feeders often preying on larvae of commercially important fisheries species.

They can grow rapidly, reaching densities of up to 500-1500 individuals per square metre.

Can easily grow on marine farming lines, vessel hulls and other marine structures that may increase harvesting or fuel costs.

Can tolerate a range of temperatures from sub-zero temperatures and up to 23 degrees.

Management approach

An unwanted organism is an organism classified as a pest by the Ministry for Primary Industries (MPI) because it is capable of causing harm to the natural environment, physical resources or human health in Aotearoa/New Zealand.

Rules

Any species declared a pest cannot be sold or be in a place where plants are being sold. Pests cannot be propagated, bred, multiplied, communicated, released, caused to be released, or otherwise spread.

See the MPI website for more information about unwanted organisms.

Control

To help us build a bigger picture of the distribution of clubbed tunicate, report any sightings to us. If possible, please take photos and record the location. The location could be the name of a vessel and where it was moored, or the physical location if it was found on the sea floor or structures.

Protect Canterbury's beautiful waterways and marine ecosystems by keeping a clean hull.

Limiting the fouling on your hull stops pests from catching a ride with you into uncontaminated areas or transferring from your vessel to others when moored or berthed in a marina. Keeping your vessel in good shape will also improve its fuel economy and speed.

Check out our handy guide to good boat maintenance practices.

For more information on clubbed tunicate and other invasive marine species visit the Marine Biosecurity Porthole.