Marine pests

Mediterranean fanworm

Mediterranean fanworm
Chris Woods/NIWA

Marine pests pose a major threat to Canterbury's beautiful coastal waters. It's important that we all work together to limit their spread.

Marine pests are species that have been introduced to our waters and have the potential to severely damage our marine ecosystems by outcompeting native species for food and space. This damage can have a devasting effect on our natural resources, marine industries, water quality and mahinga kai.

Marine pests often enter our region and spread via boat hulls. Find out what these pests look like, how to report them, and how to help stop their spread.

Marine pests to be on the lookout for

Mediterranean fanworm (Sabella spallanzanii)
Mediterranean fanworm
Mediterranean fanworm
Mediterranean fanworm
Mediterranean fanworm
Mediterranean fanworm
Mediterranean fanworm
Photos: Chris Woods/NIWA.

Description
Often between 10-50cm long, the Mediterranean fanworm lives inside a leathery, flexible tube that is brown or grey in appearance. It has feathery filaments that extend out, creating a spiral fan-shape to collect plankton. The fan is banded orange, purple or white, and reaches up to 15cm in diameter.
Where does it live?
They often attach themselves to solid structures like wharves and vessels, or other marine creatures like oysters and mussels.
Why is it a problem?
They form dense colonies of up to 1000 worms per square metre, competing for food and smothering native species. Their tubes also attach themselves to aquaculture equipment or vessels and can cause damage by clogging motors, pipes or propellers.
How do I report a sighting?
Call the Ministry for Primary Industries' Pest and Diseases hotline on 0800 80 99 66. 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.

Alternatively, you can take a photo and upload it to the Find-A-Pest app. If taking a photo of a vessel, be sure to capture the name and its location for tracing purposes.
Find out more
More information, including an identification guide, can be found on the Marine Biosecurity Porthole and on the Ministry for Primary Industries' website.
Clubbed tunicate (Styela clava)
Clubbed tunicate
Clubbed tunicate
Clubbed tunicate
Clubbed tunicate
Clubbed tunicate
Clubbed tunicate
Photos: Chris Woods/NIWA.

Description
Clubbed tunicate are immobile marine invertebrates that can 'squirt' seawater. Growing up to 16cm long, they have a nobbly, club-shaped body that has a tough and leathery texture. Attached to the surface by a stalk and a holdfast (a root-like structure), they vary in colour from brownish-white, yellow-brown or reddish-brown.
Where does it live?
They prefer protected areas such as bays and harbours and can be found in low tide areas through to 25 meters underwater. They can settle on any surface that is not covered in silt or antifouling paint, but prefer hard structures like wharves, moorings and ropes.
Why is it a pest?
They compete for space and food with native species and can live in large clusters of up to 1500 individuals per square metre. They can also be a nuisance by fouling marine farming lines, vessel hulls and other structures.
How do I report a sighting?
Call the Ministry for Primary Industries' Pest and Diseases hotline on 0800 80 99 66. 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.

Alternatively, you can take a photo and upload it to the Find-A-Pest app. If taking a photo of a vessel, be sure to capture the name and its location for tracing purposes.
Find out more
More information, including an identification guide, can be found on the Marine Biosecurity Porthole and on the Ministry for Primary Industries' website.
Undaria / Asian Seaweed / Wakame (Undaria pinnatifida)
Wakame seaweed
Wakame seaweed
Wakame seaweed
Wakame seaweed
Wakame seaweed
Wakame seaweed
Photos: Chris Woods/NIWA.

Description
Undaria often reach one-to-two metres long once mature, and can be brown, green or yellow in colour. They have a holdfast (a root-like structure) and a stem with a sporophyll around its base. Sporophyll are spiral shaped structures that produce spores, enabling the plant to reproduce.
Where does it live?
They usually grow between low intertidal areas and subtidal depths of up to 15 metres, but they have been recorded growing in depths of 40 meters. They can anchor themselves on any hard surface, including marine mooring structures, vessels, aquaculture equipment and reefs.
Why is it a problem?
Undaria is very fast growing and has easily spread throughout New Zealand by fouling on vessel hulls. A single plant can release up to 70,000 spores in one year!

While their impact can vary between locations, they can form dense underwater ‘forests’ that lead to the exclusion and displacement of native plants and animals. They can also be a problem for the aquaculture industry by increasing labour and harvesting costs.
How do I report a sighting?
Call the Ministry for Primary Industries' Pest and Diseases hotline on 0800 80 99 66. 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.

Alternatively, you can take a photo and upload it to the Find-A-Pest app. If taking a photo of a vessel, be sure to capture the name and its location for tracing purposes.
Find out more
More information, including an identification guide, can be found on the Marine Biosecurity Porthole and on the Ministry for Primary Industries' website.

Be a good boatie and make sure pests don't catch a ride with you!

You can help protect Canterbury's beautiful waterways and marine ecosystems by being a good boatie and 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.

When cleaning your hull, do it right. Taking shortcuts can make the problem much worse. You must ensure that no contaminants, like marine pests, are discharged into the water during your cleaning process.

Tips for keeping your vessel clean and pest free
  • Haul out and remove larger fouling organisms by hand. Don’t throw these back into the water where they can easily reproduce! Instead, dispose of them in a secure bin.
  • Water blast or brush off smaller material at a facility where all wash off is contained and treated. Do this at least annually or when fouling builds up beyond a light slime layer. Pay attention to appendages that protrude or retain water such as the keel, intakes/outlets, propellers and shafts.
  • Antifouling paints are useful for preventing a build-up of unwanted organisms and pests on your hull. However, they contain ingredients that can harm marine life. Always follow the manufacturer's instructions when applying antifouling paint and collect and dispose of any waste appropriately.
  • Regularly treat internal seawater systems and flush with freshwater or an approved treatment.
  • Other equipment such as trailers, anchors, dive and fishing gear should be washed with freshwater after use, and then allowed to thoroughly air dry before using in a new location
  • Always check your boat is clean before you move location.

Useful resources

  • Learn more about how to Check, Clean, Dry your vessel and equipment.
  • The marinepests.nz website also offers tips for keeping boats clean and well maintained.
Antifouling paints

Antifouling paint cover is the easiest way to keep your vessel clean. However, the ingredients in the paint, such as cooper, can harm marine life. Always apply and remove antifouling paint with careful consideration.

  • Antifouling paint generally lasts between one and two years, but always renew the paint at the interval recommended by the manufacturer. Clean and renew any paint that has been scraped or damaged, and always dispose of waste appropriately.
  • Antifouling paint works best with more than one coat applied to a clean, dry hull. Allow each coat to dry between applications and allow final coat to cure for 24 hours before re-launching.

For more information download the Environment Protection Authority's PDF guide to safely using antifouling paints.

Seen something unusual? Report it

Ministry for Primary Industries' Pest and Diseases hotline

Call the Ministry for Primary Industries' Pest and Diseases hotline on 0800 80 99 66. 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.

Take a photo and report it using the Find-A-Pest app

The Find-A-Pest app enables you to report potential pest species, including marine, plant, animal and fungal species.

If you come across something out of the ordinary, simply upload a picture to the app and a Find-A-Pest specialist or the iNaturalist community will help identify it. If your observation is considered a potential biosecurity threat, this will be forwarded to Biosecurity New Zealand to contact you if necessary.

If taking a photo of a vessel, be sure to capture the name and its location for tracing purposes.

Resources

Check out the following resources to learn more about marine biosecurity in New Zealand: