Invasive species

What are invasive species?

Invasive species are non-native plants and animals that have been introduced to an ecosystem where they do not naturally occur. Invasive species out-compete native species for water, nutrients, and light and generally lack natural pathogens or predators that keep them under control in their native habitats.  Without these ‘checks’ invasive species can spread rapidly throughout their new ecosystem.  Once established, invasive species are very difficult to control and can form thick patches over large areas known as monocultures.  These infestations can negatively impact  recreation, industry and the environment.

Characteristics of invasive species:

  • Invasive species can be prolific seed producers or reproducers e.g. Purple Loosetrife can produce over 30, 000 seeds per year! Zebra and Quagga Mussels can produce 1 million eggs per year!
  • Invasive species seeds/ eggs/ offspring can spread easily and effectively e.g. Burrs from Burdock and tumble weeds from baby’s breath
  • Invasive species can quickly establish and thrive on disturbed sites, displacing native species e.g. Eurasian water milfoil and dalmatian toadflax
  • Invasive species usually lack natural pathogens or predators e.g. sulphur cinquefoil not palatable or grazed by livestock

What are the impacts of invasive species?

  • Economic– Invasive species threaten the health of our resources and supported industries. If left unmanaged, invasive species could cost BC millions of dollars per year.
  • Social– Invasive species can be toxic to humans, wildlife and livestock and can reduce land and water recreation opportunities.
  • Environmental– Invasive species threaten biodiversity, species-at-risk and the ecosystem as a whole. They represent the second most significant cause of species extinction worldwide after habitat destruction (IUCN).

How do they get here, how do they spread?

  • Unnatural or human assisted movement is the primary way invasive species spread globally.
  • Humans have both intentionally and unintentionally introduced invasive species to a new environment
  • Aquatic Pathways of Spread– Shipping, recreational boating, live bait, aquarium and water garden trade, live food fish
  • Terrestrial Pathways of Spread– Cargo transport, horticulture industry, accidental release, firewood management

See the Government of British Columbia’s Invasive Species web page


Columbia Shuswap Invasive Species Society