Invasive species

Procambarus clarkii

What is an Invasive Alien Species?

An alien species is a species introduced outside its natural past or present distribution; if this species becomes problematic, it is termed an invasive alien species (IAS). 

IAS are the most common threat to amphibians, reptiles and mammals on The IUCN Red List; they may lead to changes in the structure and composition of ecosystems detrimentally affecting ecosystem services, human economy and wellbeing. IAS are such a problem that Aichi Biodiversity Target 9 and one clause of UN Sustainable Development Goal 15 – Life on Land specifically address the issue.

The movement of people and goods around the world increases the opportunity for introduction of IAS. The most effective way to stop the negative impacts of IAS is through prevention of spread by regulating the trade or movement of a species. Once an IAS has arrived, early detection, monitoring and eradication can stop the species spreading. 

What is IUCN doing to address IAS?



  • IUCN, with the ISSG provide technical and scientific advice to work towards achieving Aichi Target 9. 
  • The ISSG provide technical and scientific advice to national and regional agencies when developing policy and strategies to manage the risk of IAS.


  • IUCN develop capacity for combatting IAS on the ground. The InvaZiles Project for example, works with organisations in the Western Indian Ocean to develop capacity and networks for preventing and managing IAS.
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