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Narrow-clawed crayfish
Pontastacus leptodactylus
Status:
Potential
Habitat:
Freshwater
Threats:
Can impact habitat structure and outcompete native crayfish
Find out more ›
New Guinea flatworm
Platydemus manokwari
Status:
Potential
Habitat:
Terrestrial
Threats:
Can cause declines of native snail species, with cascading impacts on food webs, decomposition, and nutrient cycling.
Find out more ›
Noble crayfish
Astacus astacus
Status:
Potential
Habitat:
Freshwater
Threats:
Negatively impact habitat structure with burrows, reduce native species, competition with native crayfish
Find out more ›
North American Beaver
Castor canadensis
Status:
Potential
Habitat:
Terrestrial
Threats:
Drastically reshape ecosystems by altering water flow, vegetation, and chemistry, which can increase flooding and productivity.
Find out more ›
North American signal crayfish
Pacifastacus leniusculus
Status:
Potential
Habitat:
Freshwater
Threats:
Detrimental impacts on white clawed crayfish. Human health impacts.
Find out more ›
Northern giant hornet
Vespa mandarinia
Status:
Potential
Habitat:
Terrestrial
Threats:
Canrapidly destroy beehives, poses a serious human health risk through painful and potentially lethal stings.
Find out more ›
Northern Pacific seastar
Asterias amurensis
Status:
Potential
Habitat:
Marine
Threats:
Causes major ecological and economical damage by preying heavily on native and farmed bivalves.
Find out more ›
Northern Snakehead
Channa argus
Status:
Potential
Habitat:
Freshwater
Threats:
Predation of native fish stocks, vector for disease and parasites
Find out more ›
Northern weatherfish
Misgurnus bipartitus
Status:
Potential
Habitat:
Freshwater
Threats:
The species threatens native wetland fish by spreading quickly and outcompeting them for food and habitat.
Find out more ›
Invasive Species Northern Ireland
About ISNI
About Invasive Species
Research
Invasive Species Maps
Invasive Species Week
Invasive Species Week 2026
Ideas for events and activities
Five things you can do
Useful Resources
Back
Back
Back
Legislation
European Union
Species of Union Concern
Widely Spread Species in NI
Back
Northern Ireland Only
International
Back
Species Accounts
Species Alerts
List of identification guides
Back
Biosecurity & Prevention
What can I do?
Check Clean Dry
Guidance for Anglers
Guidance for Boaters
Guidance for canoeists, kayakers and stand up paddle boarders
Guidance for Aquaculture
Guidance for field workers
Guidance for Divers
Guidance for clubs and managers of water bodies
Guidance for events
Check Clean Dry Resources
Back
Be Pet Wise
Pet Owners
Pet Traders
Be Pet Wise Resources
Back
Be Plant Wise
Are you a retailer?
Are you a gardener/pond owner?
Know What You Grow
Stop The Spread
Compost with Care
Be Plant Wise Resources
Back
Back
Pathway Action Plans
Back
Managing the Problem
Invasive Plant Management
Site Management Resources
Back
Resources
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