Invasive Alien Species in Canada

Alien spices are microorganisms, animals, and plants that usually move to another area due to human activity. Invasive alien species that have relocated to Canada include species such as butternut canker, green crab, emerald ash borer, and giant hogweed. Such non-native species can have a significant negative impact on society, economy, and the environment.

How Aliens Species Were Brought to Canada

Most alien species were brought by immigrants to Canada during the 17th and 18th century. This is a period marked with waves of immigration, trade, and colonization. The majority of invasive species were brought from Western Europe during this period. Today, other factors contribute to the spread of non-native species, including ecosystem destruction, climate change, and species being introduced randomly or unintentionally.


The series Wild Species 2010 show that out of 11.950 species analyzed 12 percent are alien. According to estimates of 2002, more than 1,440 invasive alien species are found in Canada, among which invertebrates, insects, plants, and fish. Non-native species include 55 types of freshwater fish, several molluscs and fungi, 4 amphibians, 2 reptiles, 26 mammals, 24 birds, 181 insects, and some 27 percent of vascular plants. Some of the most invasive species have been introduced to Canada, among which rainbow trout, common carp, gypsy moth, spiny water flee, and green crab. New species are continuously brought to Canada by water, land, and air. This is mainly due to increased international travel, e-commerce, and increased trade volumes.

The majority of species inhabit the country’s lakes, rivers, forests, rangelands, and farmlands. Invasive species can cost billions of dollars because some aliens can spread to every region. Researchers estimate that a sample of 16 species such as spotted knapweed and leafy spurge cause losses between about $13 and $34 billion each year.

Harm to the Environment and Economy

Invasive plants decrease crop yields and biodiversity and change soil composition so that local species are unable to survive. They interbreed with other species, compete for resources, and contribute to habitat destruction. The chemicals used to control and eliminate aliens also cause environmental harm as they require burning of dead plants, cutting, and spraying.

Non-native pathogens fall in different categories, including viruses, bacteria, protozoa, fungi, insects, and worms. In recent years, they have been responsible for disease outbreaks across Canada, including species such as chytrid fungus, duck plague, avian influenza, and the West Nile virus which is spread to people, reptiles, birds, and mammals.

Invasive Alien Species Strategy

The Invasive Alien Species Strategy was developed in 2004 in cooperation between the federal government and the territorial and provincial authorities. The main goals of the strategy are to prevent the introduction of new species, detect invasion, and control and eliminate invaders. Different control and eradication strategies can be used, including biological, chemical, and physical as well as integrated approaches. The measures target different sectors such as industry, transportation, forestry, wildlife, aquaculture and fisheries, agriculture, and human health.

The Invasive Alien Species Partnership Program is another initiative that aims to control and prevent invasion of non-native species. Projects targeting alien invasion are offered funding, and recipients include Crown corporations, municipal, territorial, and provincial governments,  companies, research and educational institutions, Aboriginal groups, and non-profit and non-governmental organizations.