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Invasive species in Canada are non-native organisms including plants, animals, insects, viruses, fungi, and pathogens that have the potential to cause harm within various ecosystems due to their general adaptability and ability to outcompete native species for immediate resources such as food, habitat, and nutrient availability.
Over 1400 invasive species of fish, plants, insects and invertebrates have been introduced to Canada through intentional and unintentional means. Over 450 invasive flora and over 400 invasive insects have been identified. The Great Lakes region is home to nearly 200 invasive species, making it one of Canada's most heavily affected ecosystems. Freshwater ecosystems are disproportionately more imperilled compared to terrestrial ecosystems.
Most invasive species are introduced and moved around through human activities such as the transportation of shipping vessels and other marine vehicles, the movement of firewood, as well as through the horticultural industry. The regulation of these pests is managed on a provincial and federal level; It is the responsibility of each province/territory to monitor the spread of invasive species.
While ecological invasion is a naturally occurring phenomenon, anthropogenic activities have increased the occurrence and scale of invasions. The spread of invasive species is increasing due to habitat fragmentation, climate change, increased global trade and mobility. Invasive species are one of the top drivers of biodiversity loss globally, only second to habitat loss. Significant ecological, economic, and environmental damage can occur due to invasive species spread.
Impacts Invasive species cause significant damage and pose threats to Canadian agriculture, forestry, commercial fishery, recreation, culture, and biodiversity.
Economic Impacts Invasive species have economic impacts across animal production, arts and recreation, construction, crop production, forestry, hunting, mining, private households, public administration, transportation, and utilities.Canadian Food Inspection Agency. Invasive Alien Plants in Canada. CFIA. Ottawa, ON, 2008. In 2004, it was estimated that the annual cost for 16 invasive species was between CAD $13.3 and $34.5 billion annually. Leafy spurge, for example, has cost the province of Manitoba $19 million in treatment costs annually.
Environmental Impacts Environmental impacts include ecosystem diversity, structure and function, displacement of native species, and endangering other species at risk. Ecosystem functioning can also be altered through the spread of invasive plants through changes in carbon sequestration and dense canopies that shade undergrowth.
Pacific & Western Canada
In Western Canada, the ecological impacts of invasive species are increasingly intersecting with changing climate patterns, particularly through the amplification of wildfire cycles. Invasive flora fundamentally alters local fuel loads and forest compositions, transforming vulnerable ecosystems into volatile fire hazards. Invasive plants significantly modify regional fire regimes by changing the density, structure, and flammability of ground cover. For example, the rapid colonization of cheatgrass (Bromus tectorum) across dry interior ranges in British Columbia introduces a highly flammable, continuous fine fuel bed. Cheatgrass dries out much earlier in the summer season than native perennial bunchgrasses, creating a continuous carpet of fine kindling that accelerates fire ignition and increases the rate of spread across provincial rangelands.
Similarly, densely growing wood-heavy invasive species like Scotch broom (Cytisus scoparius) pose a significant wildfire hazard as they act as fuel ladders. According to data tracked by the BC Ministry of Forests, Scotch broom actively invades recently cleared forest stands and resource corridors, altering soil chemistry and compounding fire behavior and control concerns. Because of its high oil content, dry branch architecture, and capacity to form dense, impenetrable thickets, it functions as a volatile flash fuel in coastal areas like Vancouver Island and the Lower Mainland. These structural attributes allow low-intensity ground fires to climb easily into the forest canopy, dramatically elevating the likelihood of destructive crown fires and complicating suppression efforts by regional fire services.
Invasive Species Strategy In 2004 the federal government of Canada released their invasive alien species strategy. Four key priorities for establishing an invasive species management strategy; prevention, early detection, rapid response, and management.
Prevention Prevention of invasive species introduction includes conducting comprehensive risk analysis for planned introductions and measures to reduce unintentional introductions.Environment Canada. 2004. An invasive alien species strategy for Canada. Ottawa - Ontario : Environment Canada September 2004. CW66-394/2004E-PDF There are many strategies for preventing unintentional invasions including the play clean go strategy: removing dirt and plant matter from boots and gear after outdoor activities and staying on designated trails. The buy local burn local strategy encourages the use of buying firewood where you plan to burn it to prevent the unintentional spread of tree-killing insects and pathogens. In addition, the plant wise strategy encourages gardening and landscaping with native or non-invasive fauna and flora to prevent the unintentional spread of invasives.
Early Detection Early detection through large-scale surveillance is a key step in effective management of invasive species. It involves site specific monitoring around critical points of entry, and protected areas and can be done through government bodies, non-governmental organizations, or citizen science. Once an unknown species has been reported, it can be identified and a determination of rapid response and management can be done. Early detection is often low due to logistic and financial feasibility that limits the strength of detection programs.
Invasive plants can be hard to identify in the early stages of growth resulting in their ability to establish strong populations before they have been detected. The evolvement of technologies like remote sensing, environmental DNA, and artificial intelligence have improved the capabilities for early detection and response given their ability to detect new species in earlier stages. Crowdsourcing through citizen science can also enhance early detection programs.
Rapid Response Rapid response is a systematic effort to eradicate or contain invasive species while infestations are still localized.NISC (National Invasive Species Council). 2008. 2008–2012 National Invasive Species Management Plan Integrated risk analysis is used to determine appropriate rapid response measures when an invasive species is identified. Systems for rapid decision-making and implementation are essential for responding before a species can become established or cause harm. Early and rapid responses are more likely to be effective than control or eradication attempts occurring later in established colonies.Haley, A. L., Lemieux, T. A., Piczak, M. L., Karau, S., D’Addario, A., Irvine, R. L., Beaudoin, C., Bennett, J. R., & Cooke, S. J. (2023). On the effectiveness of public awareness campaigns for the management of invasive species. Environmental Conservation, 50(4), 202–211. https://doi.org/10.1017/S037689292300019X
Management Eradication, containment, control and public awareness are strategies used for management of invasive species. Management can be undertaken through multiple methods including chemical, biological, or physical control. Chemical control is the use of pesticides, herbicides, fungicides or insecticides, this strategy involves proper application to ensure application is limited to the appropriate area to prevent damage to other species. Biological control is when another living organism is used to control or eradicate an invasive species, usually this involved the introduction of the invasive species' natural predator to contain the spread. This method does run the risk of introducing additional invasive species or other unintended consequences if the other organism is not thoroughly assessed and monitored. Mechanical or physical control involves many methods including hand-pulling, digging, flooding, installing physical barriers, prescribed burns, girdling, mowing. Physical control is typically labour intensive and is most effective for small colonies or in conjunction with other methods. Public participation can also support management strategies through individual-scale actions and volunteer-based initiatives.
Government goals and targets
2020 Biodiversity Goals and Targets In 2015, the 2020 Biodiversity Goals and Targets were adopted by Canada with 19 targets to protect Canada's nature and biodiversity. Goal B was to reduce the pressures on biodiversity and create more sustainable consumption of biological resorces. Target 11 within goal B specifically addressed invasive alien species with the stated goal of developing management plans:"By 2020, pathways of invasive alien species introductions are identified, and risk-based intervention or management plans are in place for priority pathways and species."Environment and Climate Change Canada. 2016. 2020 Biodiversity Goals & Targets For Canada. Retrieved from https://publications.gc.ca/collections/collection_2016/eccc/CW66-524-2016-eng.pdfIndicators of the target were the number of known invasive alien species in Canada, percentage of federally regulated unestablished invasive species, and the number of intervention or management plans in place. In the 2020 final assessment, the target was met based on pathways of introduction being identified and management strategies in place for priority pathways and species.
2030 Nature Strategy After signing the 2022 Kunming-Montreal Global Biodiversity Framework, the 2030 Nature Strategy was introduced to provide a path forward for how Canada will implement the framework.
Target 6 on Invasive Alien Species of Canada's 2030 Nature strategy is to"Eliminate, minimize, reduce and or mitigate the impacts of invasive alien species on biodiversity and ecosystem services by identifying and managing pathways of the introduction of alien species, preventing the introduction and establishment of priority invasive alien species, reducing the rates of introduction and establishment of other known or potential invasive alien species by at least 50 per cent by 2030, and eradicating or controlling invasive alien species, especially in priority sites, such as islands."This target builds off of the existing pathways and management plans created through the 2020 Biodiversity Goals and Targets.
Indigenous Perspectives and Management As stewards of the land and water, Indigenous peoples' knowledge and experience of the land can be integrated into invasive species management for a more nuanced and wholistic approach to management.