Invasive species in Canada The threat of invasive species

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Science 10 ~ Ecology Class Document

Ms. Pushie

Invasive species in Canada

The threat of invasive species

Invasive species are plants, animals, aquatic life and micro-organisms that outcompete native species when introduced outside of their natural environment and threaten Canada's ecosystems, economy and society. They can come from across the country or across the globe.

In Canada, there are hundreds of invasive species including insects, birds, mammals, reptiles, amphibians, crustaceans, aquatic and terrestrial plants, marine and freshwater fish, algae, fungi, and molluscs. About 10 per cent of all plants are also considered invasive species.

Some better known examples of invasive species in Canada include the emerald ash borer, zebra mussels, sea lamprey and purple loosestrife.

Invasive species generally share common characteristics which can make them difficult to control and contain. These characteristics include higher rates of reproduction, fewer natural predators and the ability to thrive in different environments.

Environmental, social, and economic effects

Invasive species are a serious threat to biodiversity in Canada. They create an imbalance in nature by competing for the same resources that native species need to survive. Like a ripple in a pond, their impact is far-reaching.

New species are continually arriving in Canada. In the Great Lakes alone, a new species is discovered approximately every six to nine months. If given the opportunity, these new species could become invasive and do widespread damage by: 

  • negatively impacting biodiversity;

  • competing with native species until they become threatened, endangered, extirpated or extinct; 

  • degrading and eroding soil; 

  • degrading water and habitats; 

  • altering infrastructures; 

  • introducing disease; 

  • reducing land and water recreational opportunities; 

  • increasing control and management costs; 

  • reducing productivity in forestry, agricultural, and fishing sectors;

  • having export and import trade restrictions imposed; and

  • reducing property values.

Introducing and spreading invasive species

Invasive species are a cost of globalization. They are introduced and spread through various pathways, including:

  • goods such as firewood, plant products or wood packaging; 

  • live food imports; 

  • aquarium and horticultural imports

  • vehicles such as aircraft, commercial and recreational boats; 

  • ballast water from large ships; and 

  • diseases in wildlife.

Key terms 

  • An Invasive Alien Species Strategy for Canada – In September 2004, the federal government and its provincial and territorial counterparts introduced this strategy to reduce the risk of invasive species and conserve our ecosystems.

  • Biodiversity – Variability among living organisms from all sources including terrestrial, marine, and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species, and of ecosystems. 

  • Convention on Biological Diversity - A convention signed by world leaders at the 1992 Earth Summit in Rio de Janeiro. The key objectives of the convention are the conservation of biological diversity, the sustainable use of its components, and the fair and equitable sharing of the benefits from the use of genetic resources. 

  • Ecosystem - A self-sustaining community that consists of a dynamic set of living organisms interacting with each other and with their environment.

  • Ecosystem Diversity - The variety of plants, animals, and micro-organisms that are found in an ecosystem. 

  • Endangered species - A wildlife species that is facing imminent extirpation or extinction.

  • Extirpated species - A wildlife species that no longer exists in the wild in Canada, but exists elsewhere in the wild.

  • Habitat - Location where a plant, animal, aquatic life or micro-organism naturally lives and grows. 

  • Invasive Species – A species of plant, animal, aquatic life or micro-organisms that outcompetes native species when introduced outside of its natural environment and threatens ecosystems, economy and society. 

  • Pathway - The route or mechanism by which an invasive species arrives or spreads in a country or in a region. 

  • Pest - Any species, strain, or type of plant, animal, or pathogenic agent (disease-causing agent, such as a virus or bacterium) that can damage plants or plant products. 

  • Species - A classification of a plant, animal, or micro-organism within a group that has distinct characteristics and reproductive processes. 

  • Species at risk - An extirpated, endangered or threatened species, or a species of special concern designated under Canada´s Species at Risk Act.. 

  • Species of special concern - A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

  • Threatened species - A wildlife species that is likely to become an endangered species if nothing is done to reverse the factors leading to its extirpation or extinction.

Canada´s Response to Invasive Species

An Invasive Alien Species Strategy for Canada aims to reduce the risk of invasive species to the environment, economy, and society, and to promote environmental values such as biodiversity and sustainability. The Government of Canada and its provincial/territorial counterparts introduced this Strategy in September 2004.

The Strategy includes preventing intentional and unintentional introductions of invasive species in Canada from other countries, across provincial and territorial borders, and between ecosystems within a region.

Currently, the partners include: the Canadian Food Inspection Agency, Environment Canada, Agriculture and Agri-Food Canada, Canada Border Services Agency, Fisheries and Oceans Canada, Natural Resources Canada, Parks Canada, Transport Canada and all provincial ministries responsible for forestry, fisheries and aquaculture, parks and natural resources.

Four equally important goals form the foundation of the Strategy: 

  • to prevent the harmful intentional and unintentional introduction of invasive species to Canada; 

  • to detect and identify new invaders; 

  • to respond rapidly to new invaders upon detection; and 

  • to manage established and spreading invaders through eradication, containment and control.

Steps You Can Take

A species that benefits one environment won´t necessarily be conducive to another. For native species to thrive and contribute to a healthier ecosystem, it is important to prevent releasing species from other ecosystems that could spread rapidly and become predators or diseases for native species.

The following are ways you can help:

  • Many invasive species are not easily visible to the naked eye. Leave natural items – like animals, plants, seeds, insects, wood products, soil and water – in their natural habitats to avoid the introduction and spread of invasive species. 

  • Plants, animals and aquatic life bought on the Internet or in a store can impact Canada's ecosystems if they accidentally escape or if you can no longer care for them. With no natural predators, they could overwhelm the ecosystem in which they are released. 

  • There are legislative restrictions on the unauthorized, intentional release of invasive plant or animal species. Never release them into the environment, for any reason. 

  • Be aware and declare. When returning to Canada from abroad, declare all foods, animals, plants and related products to a border services officer. These items could introduce harmful pests to Canada. 

  • Learn about invasive species and ballast water and the Canadian Ballast Water Program.

  • Use the resources on the invasive species Web portal to learn more about the invasive species in your area. If you think you have spotted an invasive species that has not been found in your area before please call 1-800 O Canada or contact us.


List of Invasive Species

  • Altaï larch longhorn beetle

  • Aquatic invasive species

  • Ash bark beetle

  • Asian carp

  • Asian gypsy moth

  • Asian long-horned beetle

  • Birch bark beetle

  • Black fir sawyer beetle

  • Black pine bark beetle

  • Brown spruce longhorn beetle

  • Common pine shoot beetle

  • Emerald ash borer

  • European green crab

  • European oak bark beetle

  • European oak leafroller

  • European spruce bark beetle

  • European spruce longhorn beetle

  • European tent caterpillar

  • Exotic forest insect

  • Eyed longhorn beetle

  • Fungi

  • Garry oak ecosystems

  • Great Capricorn beetle

  • Great spruce bark beetle

  • Gypsy moth

  • Hauser’s engraver

  • Hawthorn spider mite

  • Hazelnut longhorned beetle

  • Hemlock woolly adelgid

  • Japanese cedar longhorned beetle

  • Jointed goat grass

  • Larch bark beetle

  • Large pitch tube bark beetle

  • Large poplar longhorned beetle

  • Leafy spurge

  • Leek moth

  • Mitten crab

  • Monochamus sartor

  • Morawitz's bark beetle

  • Nun moth

  • Pale tussock moth

  • Pine shoot beetle

  • Red-bodied horntail

  • Red-haired pine bark beetle

  • Rosy(pink) gypsy moth

  • Sea lamprey

  • Siberian coniferous silk moth

  • Siberian silk moth

  • Silver fir shoot tortricid

  • Sirex wood wasp

  • Six-spined engraver beetle

  • Six-spined spruce bark beetle

  • Smaller Japanese cedar longhorned beetle

  • Spruce weevil

  • Thin-antenna spruce borer

  • Two spotted oak borer

  • Woolly cupgrass

  • Zebra mussel

What are alien and invasive alien species?

Across the world, many species of plants, animals and even micro-organisms have moved beyond their native range and habitat only to become established in a completely new location. Sometimes species commonly found in one part of Canada become established outside their natural range in another region of the country where they have not historically been found. Most however, come from outside Canada and were relocated as a result of human activity.

Species that have become established in areas outside their natural range are known as "alien species". Generally, alien species do not pose a significant risk and many are even beneficial. However; when alien species are capable of causing significant harm to our environment, the economy or to society, they are referred to as "invasive alien species".

Canada has many examples of both invasive alien species and alien species. A few examples are shown below.

Alien Species

Invasive Alien Species



Black-footed spider


Emerald Ash Borer


Common plantain


Green crab


European hare


Butternut Canker


Red-eared slider


Giant Hogweed


Native Species

Native species are those species that are indigenous to a particular area or region. Typically, these species have evolved over thousands of years, adapting to their surroundings, and have become an important part of the local ecosystem.

Like most species, native species are constantly competing for resources.  Changes to the climate, weather disturbances, fires, floods, the introduction of invasive alien species and human influences can have a significant impact on the growth or decline of a native population. Over time, some species may even be pushed out of a region or area altogether.

Growing or shrinking native species populations can have a big impact on local ecosystems.  In some cases, these shifts can be very harmful.  For example, the forest tent caterpillar (Malacosoma disstria) is a native species whose populations can sometimes grow so quickly that it will strip the leaves from large areas of hardwood forest. Even though this species often lives in balance with other species, its varying population size can cause considerable economic, environmental and social harm.


The Mountain Pine Beetle (Dendroctonus ponderosae) is another native species that can cause devastation to its environment. Adult mountain pine beetles lay their eggs on the bark of a variety of different pine trees. After the eggs hatch, the larva feed on the phloem (inside bark area) which can ultimately kill the tree.  Like the tent caterpillar, major increases in the beetle larvae population can seriously harm the local tree population.  

The mountain pine beetle has coexisted with the pine forests of British Columbia for centuries, and although outbreaks have occurred, they have been short-lived and regional in area. Recently however, the Mountain Pine Beetle population has exploded causing unprecedented tree mortality and problems for forest industry.

 Although the scale of this epidemic has never been experienced before, the mountain pine beetle is currently only impacting forests within its historic or native range. This situation is being closely monitored however and its status will be re-evaluated should the conditions change and it moves into areas where it is considered to be invasive.

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