What is an invasive alien species?
Invasive alien species are animals, plants or pathogens that would not naturally occur in Ireland but are here because of human activity. When introduced, they survive and thrive to the point of negatively impacting on our wildlife, on the services nature provides, on our economy, and the way we live.

Do all alien species become invasive?
Most alien (also known as non-native) species do not cause any harm and only a small proportion are considered to be invasive.

How do alien species get here?
Invasive alien species can be introduced intentionally for many reasons such as planting in gardens, or to keep as pets but they may then disperse or escape. They may be intentionally released to the wild for hunting or food, although this is illegal in Ireland.
Invasive alien species can also arrive here accidently as hitchhikers on our vehicles, belongings or as contaminants on products.

There is an increasing trend of introduction of invasive alien species to Ireland, a trend seen globally that is linked to increased movements of people, goods and increased connectivity of our trade networks.

What is the economic cost of their impact?
The estimated annual cost of invasive species to the economies of Ireland and Northern Ireland is over €261 million euro (Kelly et al., 2013 report).

What can be done to tackle the threat of invasive alien species?
Key to tackling the threat from invasive alien species, is to take measures to prevent their introduction to Ireland and their spread within it. This involves a combination of regulatory measures such as banning intentional introductions  traded species, pre and at entry point checks for contaminated goods/vehicles, and also, to encourage uptake of biosecurity measures such as Check, Clean, Dry or Disinfect for all equipment/gear that comes in contact with the aquatic environment.

If they do arrive, we need to detect and report them as soon as possible, so rapid response actions to contain and remove them can be undertaken. Failing that, the species may spread and become widely established. Long-term control may then be the only remaining option – and that’s just where it is possible or feasible.
Everyone can help prevent the introduction and spread of invasive alien species by being aware of biosecurity actions you can take and supporting early detection by reporting your sighting.

Once introduced, control, management and eradication where possible of invasive species can be very difficult and costly; therefore early detection and reactive measures are desirable.

Below are detailed definitions from the Convention on Biological Diversity – COP 6 Decision VI/23 ‘Alien species that threaten ecosystems, habitats or species’.

alien species” refers to a species, subspecies or lower taxon, introduced outside its natural past or present distribution; includes any part, gametes, seeds, eggs, or propagules of such species that might survive and subsequently reproduce
invasive alien species” means an alien species whose introduction and/or spread threaten biological diversity
introduction” refers to the movement by human agency, indirect or direct, of an alien species outside of its natural range (past or present). This movement can be either within a country or between countries or areas beyond national jurisdiction
intentional introduction” refers to the deliberate movement and/or release by humans of an alien species outside its natural range
unintentional introduction” refers to all other introductions which are not intentional
establishment” refers to the process of an alien species in a new habitat successfully producing viable offspring with the likelihood of continued survival.

For a searchable database of definitions please visit the Convention on Biological Diversity (CBD) Glossary of Terms web page: www.cbd.int/invasive/terms.shtml