American Economic Statistics OfficeGreen Finance

What are Invasive species?

Find out more about invasive species and why they threaten our world.

Calendar of events

Workshops, conferences and events focusing on invasive species.

Websites and online databases

Search for websites and online databases about invasives species.

Ecology and Management of Invasive Alien Species: Management


What happens when a species is introduced into an ecosystem where it doesn’t occur naturally? Are eco-systems flexible and able to cope with change, or can a new arrival have far-reaching repercussions and do permanent damage? Will something special be lost forever? Does it matter?

In the distant past, the earth’s mountains and oceans represented formidable natural barriers to all but the hardiest of species. Ecosystems evolved in relative isolation. Early human migration saw the first intentional introductions of alien species as our ancestors attempted to satisfy physical and social needs, but the magnitude and frequency of those early introductions were minor compared to those associated with today’s extensive global trade and passenger movements.The introduction of the Western mosquito fish still continues.

History is rich with tales of the disastrous outcomes of some intentional introductions such as that of the Nile Perch, which resulted in the extinction of more than 200 other fish species. We can avoid repeating such mistakes by learning from history. Yet surprisingly, potentially damaging introductions continue. The ongoing release of the mosquito fish, for example, is a good example. Another is the questionable behaviour of some participants in the international garden seed and pet trade. Careless behaviour leads to unintentional introductions. So-called ‘accidents’ now account for the majority of successful invasions.