The ORC’s Environmental Data Portal is experiencing high traffic volumes affecting its effectiveness at present. The site is being worked on at present and people are asked to be patient. Please be considerate in using this tool, some people require access to the EDP for important decision-making today.
Environmental Data PortalThe ORC’s Environmental Data Portal is experiencing high traffic volumes affecting its effectiveness at present. The site is being worked on at present and people are asked to be patient. Please be considerate in using this tool, some people require access to the EDP for important decision-making today.
Common name: | Clubbed Tunicate |
Scientific name: | Styela clava |
Management programme: | Unwanted Organism |
If you have seen or suspect the presence of this pest you must report the sighting to us.
Contact Otago Regional Council on 0800 474 082 or biosecurity@orc.govt.nz
Styela clava, commonly known as the clubbed tunicate, can form dense colonies of up to 1500 individuals per square metre, competing for space and food with native species such as mussels and oysters. They are highly effective filter feeders, preying on larvae of commercially important fisheries species and impacting native biodiversity. Styela clava can grow rapidly on marine farming lines, vessel hulls, and other structures, increasing maintenance, harvesting, and fuel costs.
This pest spreads via vessels, either as larvae in ballast water or as hull fouling, and can also be dispersed as larvae carried by water currents.
It has been detected in Otago, found on artificial structures in Otago Harbour. Styela can impact marine farms, reduce native biodiversity, and increase maintenance costs for vessels and infrastructure. It has not been detected in Southland, and efforts are focused on preventing its spread further South.
Late summer to early autumn (January to April in Southern Hemisphere). This period often coincides with peak settlement and when individuals are most visible. Growth is typically rapid during warmer months, making colonies more prominent.
It is an offence to breed, knowingly communicate, exhibit, multiply, propagate, release, or sell, an unwanted organism (Biosecurity Act 1993).
ORC is currently developing a marine biosecurity programme and needs to obtain more information on species distributions before pursuing management options. If you think you have spotted clubbed tunicate, please let us know by calling 0800 474 082 or emailing biosecurity@orc.govt.nz
Preventing the spread of clubbed tunicate is the best strategy, as removal of invasive marine pests is both difficult and expensive.
Cleaning your craft and gear for biosecurity purposes is an important way to help protect the marine environment. Just as regular maintenance keeps your equipment in good condition, biosecurity cleaning keeps the ocean healthy for everyone.
The three main types of marine biosecurity cleaning for boaties are:
You must notify the Otago Regional Council if you suspect the presence of this organism.
If you think you've seen Styela clava:
An unwanted organism is not managed under the ORC Pest Plan but may be controlled as part of our Biosecurity Strategy.
Do you know what’s lurking beneath your boat? The ORC Biosecurity team works hard to stop harmful pests from spreading in Otago’s coastline and helps people learn how to keep these pests out.