Undaria is a golden-brown kelp, which can reach 1 - 2 metres in length. Mature undaria is easily distinguished from native kelp by its ‘frilly’ spore-producing structure (the sporophyll) near the base of the plant.

Undaria was introduced to New Zealand in the 1980s, probably in ballast water. Since its initial discovery, undaria has become established in many ports and extensive parts of the eastern coastline.

It is currently only known in a small part of Port Taranaki where populations are being controlled and monitored.

Asian kelp, wakame.

Undaria is a highly invasive species. Once established it has the ability to replace or exclude native seaweed species and associated marine flora. By modifying coastal habitats and smothering other useful species, undaria may displace paua, mussels, and other traditional food sources of value to Māori and other seafood gatherers.

Undaria can interfere with marine activities by fouling mussel farms, salmon farms, and boats. Heavy infestations may also clog marine farming equipment, slow growth of mussels, and restrict water circulation. Heavy fouling of boats seriously decreases their efficiency.

You must destroy all adult and juvenile forms of undaria in a manner that does not result in the further spread of the plant.

What is the 'Pest Management Strategy' for Taranaki?

1. Remove the entire plant, including the sporophyll and holdfast. Ensure no fragments are left in the water.

2. Dispose of plants on land – undaria makes good compost.

3. When removing fouling from hulls, do so out of the water and clean hull thoroughly.

4. Keep your vessel and equipment clean and your hull regularly anti-fouled.