Invasive Species Controls



Invasive Species

Non-native invasives are species that have been introduced, generally by human intervention, outside their natural range and whose establishment and spread can threaten native ecosystems.

The number of non-native freshwater species recorded in Irish watercourses increased significantly in the 20th century. However, not all non-native species are invasive and current problems are caused by only a small percentage of those species that have been introduced. The presence of a truly invasive species is evidenced by a demonstrable adverse impact on native communities or habitats.

Many of the most problematic species present in Ireland today were introduced in the last 20 years and some as recently as 2005. The rate of species introductions is accelerating because of increased international travel and trade.


What is the problem and how is it caused?

Invasive species represent one of the greatest threats to biodiversity, second only to that caused by direct habitat destruction. They do this by competitively excluding or out-competing our less robust native species, by preying on native species or by altering the natural aquatic or riparian habitat in which they reside.

In addition to their biological effects, invasive species can adversely impact the recreational and amenity use of infested watercourses by restricting angling, boating, swimming and other water-based leisure pursuits. They can impact on industry by clogging engines, turbines and water intake pipes. These adverse effects have resulted in significant costs to the economy.


How are they introduced and spread?

Non-native invasive species are commonly introduced by human action, either accidentally (e.g. hull fouling or ballast water) or intentionally (e.g. water garden planting or stocking). Spread within the country is often mediated by water flow in river catchments


Increasing awareness

The primary purpose of this information is to create an awareness of the existence of non-native invasive species in Ireland and of the environmental hazard that they represent. It should also help one to identify some of the more high impact invasive species that are present in and adjacent to our waters.

Another objective is to actively discourage people from accidentally or intentionally spreading invasive plants, invertebrates or fish. The spread of these species can be minimised by promoting good environmentally sensitive recreational behaviour and sound aquatic gardening practices.


How can you help?

Please, thoroughly clean and disinfect all fishing equipment: clothing, boots, nets, boats and engines, preferably with hot water

Never dispose of non-native aquatic plants, invertebrates or fish in natural rivers, lakes or canals. Better still, only use native species in your ponds.

Always check for and remove any attached vegetation or obvious animal life from your boat when removing it from the water. Always drain any water from the boat or engine.

For further information about the Invasive Species Group see:

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