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Unwanted organism
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A number of species have been declared nationally as Unwanted Organisms. For the most up-to-date list of Unwanted Organisms, visit the MPI website.
Unwanted Organism status means that it is prohibited from sale, propagation and distribution in accordance with sections 52 and 53 of the Biosecurity Act. Freshwater gold clam is not a pest to be managed under our Pest Plan, however, unwanted organisms may be controlled in other ways in accordance with our Biosecurity Strategy.
Asian paddle crab
Asian paddle crabs have a 12 cm shell, paddle-like hind legs, and spines on their claws and shell, with colours ranging from pale-green to chestnut-brown; they inhabit estuaries and coastal zones.
Clubbed tunicate
Styela clava, or clubbed tunicate, is a long, club-shaped marine animal that can grow up to 160 mm, featuring a knobbly surface, two siphons on top, and is typically found attached to various structures in shallow waters.
Didymo
Didymo is a thick pinkish-brown layer that covers rocks and plants in freshwater, often forming flowing 'rat tails' with white-cream ends that look like soggy toilet paper, and feels like wet cotton wool.
Exotic caulerpa
Exotic Caulerpa has green, oar blade-shaped fronds up to 10 cm long, growing from horizontal stems that form dense mats on the seafloor.
Freshwater gold clam
Freshwater gold clam is a tiny invasive clam that clogs waterways, threatens native species, and spreads via boats.
Great willowherb
Great willowherb is a tall, pink-flowering plant that grows up to 2 m in damp places like wetlands, riverbanks, and ditches. It forms thick stands that squeeze out native plants, change water flow, and spread by seed, wind, water, machinery, shoes—and even underground roots. Report this pest!
Mediterranean fanworm
The Mediterranean fanworm is a tube-dwelling worm with a leathery appearance, growing up to 80 cm and featuring a large spiral of colourful feeding tentacles.
Purple loosestrife
Purple loosestrife is a tall wetland weed with purple flower spikes that outcompetes natives, and blocks waterways. A single plant can produce up to 2.5 million seeds a year, spread by wind, water, and machinery. Report this pest!
Yellow Flag Iris
Yellow Flag Iris is poisonous to humans and animals. It grows up to 1.5 meters tall, with broad, flat, sword-shaped leaves, and bright yellow flowers.
Undaria
Management: Unwanted Organism | Undaria is an invasive seaweed that grows 1 to 2 meters long. It has a crinkly texture and comes in brown, green, and yellow colours, with a noticeable midrib and a spiral structure at the base.
Official New Zealand Pest Register
For the most up-to-date list of Unwanted Organisms, visit the MPI website. for the Official New Zealand Pest Register (ONZPR).
Regional Pest Management Plan
The Regional Pest Management Plan (Pest Plan) sets out the framework for how pest plants and animals specified in the plan will be managed in Otago over the next 10 years.
Biosecurity strategy and plans
This Strategy sets out ORC’s broader role in biosecurity, and a number of important actions and projects to better manage pests and harmful organisms.
