| Clubbed tunicate/ Leathery sea squirt Styela clava | Established | - Fast growing and forms dense groups
- Filter feeder that competes with native and aquaculture species for food (planktonic larvae) and space
- Nuisance fouler of vessels, aquaculture and fishing equipment and other artificial structures
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| Mediterranean fanworm Sabella spallanzanii | Established | - Forms dense groups
- Competes with native species for food and space
- Negative impact on the establishment of new generations of some species, and on nutrient flow in the water column
- Dense beds foul fishing equipment and aquaculture structures
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| Japanese kelp Undaria pinnatifida | Established | - Rapidly forms dense stands that overgrow and exclude native seaweed species
- Nuisance fouling causes problems and increased costs for aquaculture
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| Asian paddle crab Charybdis japonica | Established | - Aggressive crab that can out-compete native crabs for space and food
- Threat to aquaculture as it preys on shellfish
- Carries White Spot Syndrome virus which can infect native and farmed prawns, crabs and lobsters
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| Pyura Pyura doppelgaengera (previously P. praeputialis) | Established | - Forms dense populations or mats, and can survive in a wide geographical range
- Could displace important native New Zealand species, including green-lipped mussels
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| Australian droplet truncate Eudistoma elongatum | Previously detected, not established in the environment | - Quickly spreads and smothers other algae, seagrasses and invertebrate communities
- Out-competes native species for food or light and produces toxic compounds
- Vast beds can destroy native species diversity and fish habitat
- Tangles in nets and anchors
- If aquarium Caulerpa was to escape into the marine environment, there is a high risk of it establishing and severely damaging the marine environment
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| Asian clam Potamocorbula amurensis | Not Detected | - Reduces planktonic food sources, causing decline in abundance and diversity of native species, and decline or collapse of commercial fisheries and farmed shellfish
- Reaches extremely high population densities, altering the soft sediment community structure of an area by changing the sediment structure, and reducing the space available for other species
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| Chinese mitten crab Eriocheir sinensis | Not Detected | - Burrowing weakens banks and causes accelerated erosion
- Hosts liver fluke (Paragonimus sp.) that is harmful to human health
- Consumes both plants and animals
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| European shore crab Carcinus maenas | Not Detected | - Highly adaptable invasive species
- Voracious predator – eats mussels, crabs, oysters, limpets, barnacles, worms, juvenile crabs and shellfish, including scallops
- Potential to significantly alter ecosystems causing mortality in native crab and shellfish populations
- Implicated in decline of native shellfish populations overseas, some of commercial importance
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| Northern Pacific seastar Asterias amurensis | Not Detected | - Voracious predator of native species and economically important farmed shellfish
- Potentially serious impacts on aquaculture, fisheries and wild shellfish populations
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