Canada should embrace invasive species

Our editorial: Hostility toward foreign flora and fauna has become official policy in many places in Canada. Is there any logic to it?

Shipping companies, scientists and environmentalists have long debated how to stop the onslaught of exotic species such as zebra mussels in the Great Lakes. Now, lawyers are getting involved. Many of the 183 invasive species known to inhabit the lakes arrived in ballast water dumped by oceangoing ships. A Michigan law that took effect this year requires freighters to sterilize ballast before discharging it into the state's waters. (U.S. Department of Agriculture/AP/CP)

(U.S. Department of Agriculture/AP/CP)

As peaceful and welcoming as Canadians like to think of themselves, we spend an awful lot of time claiming to be under attack from foreign threats.

Last month, for example, the discovery of aquatic visitors from Asia in Ontario lakes prompted a familiar cry: “Freshwater jellyfish invade Lake Erie” screamed the London Free Press, which called the incursion “another unwelcome addition to a long list of invasive species in the Great Lakes region.” In Montreal recently, a flock of sheep was unleashed on a local park because they eat “invasive species like buckthorn and … uproot them so they don’t grow back.”

This sort of panic and intolerance regarding non-native species can be considered official policy. All provinces as well as Ottawa and many cities have invasive species programs meant to whip up animosity against alien invaders. “Be suspicious of exotic plants,” warns the Invasive Species Council of British Columbia; to protect “biodiversity,” it urges citizens to “eradicate” any trespassers.

Such hostility toward foreign flora and fauna is wildly overdone—a result of an unscientific belief that non-native species are universally bad. Consider purple loosestrife. A majestic and colourful addition to many roadsides, it is widely considered a mortal threat to other life forms. B.C.’s invasive species website blames it for choking ponds and causing animal extinctions in local areas. Ontario even once imported a non-native beetle to eat it. Yet a 2010 study by biologist Claude Lavoie of Université Laval in the academic journal Biological Invasions found the case against purple loosestrife to be entirely anecdotal—and wholly unconvincing. “There is certainly no evidence that purple loosestrife ‘kills wetlands’ or ‘creates biological deserts,’ as is repeatedly reported,” Lavoie concludes. Most of the plant’s alleged sins, he finds, are due to broader ecological factors caused by humankind. But as a foreigner, purple loosestrife makes a convenient scapegoat.

Prejudice toward non-native species often blinds us to a broad array of potential benefits. “Zebra mussels are an iconic invasive species—everyone really hates them,” says Ken Thompson, author of the provocative 2014 book, Where Do Camels Belong? While Thompson, a retired biology professor, admits these tiny water creatures can damage pipes and swimmers’ feet, they also filter pollution. The clarity of many Canadian lakes has improved dramatically since their appearance. “If you didn’t think of them as an alien species, you’d have to admit they’re doing a great job,” he says in an interview. An aggressive, stringy type of Japanese seaweed often blamed for fouling fishing nets and beaches on the east coast of North America has a similarly unrecognized upside. Evidence last month in the Proceedings of the National Academy of Sciences shows it offers a vital habitat for young crabs, shrimp and fish.

While some invasive species admittedly do considerable damage—emerald ash borers are destroying many urban forests across Canada—such cases are surprisingly rare. The vast majority of alien arrivals are entirely benign; those Lake Erie jellyfish will likely have no discernible effect on the ecosystem, beyond improving overall biodiversity by adding another species to the mix.

For Thompson, this hatred of invasive species reveals an unwarranted preference for the status quo. “If something new shows up, people automatically think it must be bad, or out of place,” observes Thompson. “But nature is in a state of flux all the time.” Camels first evolved in North America but are now native to Asia. Honeybees, on the other hand, were unknown on this continent prior to the colonial era. (Indigenous peoples originally called them “English flies.”) For all the official disapproval, often the only difference between native and non-native species is the passage of time. And when problems do arise, we should weigh both good and bad consequences of new arrivals—relying on science rather than prejudice to determine our actions. Canadians warmly embrace human immigration for the dynamism and diversity it provides our country. We should be as open-minded about visitors from the natural world as well.


Canada should embrace invasive species

  1. Like I said, if we based our society on science…….

    • Maclean’s editorials are seldom so far—or so egregiously—off the mark. The writer(s) of this laughably facile missive apparently have no idea about the difference between introduced (a.k.a alien, foreign, exotic) species and those that become invasive (environmentally, ecologically, or economically detrimental). Plus, Ken Thompson is seen as a crank with no street cred in the scientific community and his non-scientific book has been so widely panned that it’s a wonder it’s still on anyone’s radar. This argument about invasion scientists showing bias toward non-indigenous species has also been empirically dismissed: they are just as biased against native species that become invasive (or irruptive—a special case of a native species suddenly undergoing unnatural population explosions that can devastate landscapes. e.g., white-tailed deer). The arguments put forth here are pure idiocy and have completely overlooked the very real, tractable problems caused in Canada by a host of invasive species, which have annual economic costs to Canadians in the billions of dollars (not including the costs of control and eradication here—just pure economic impact). And I’m not just saying that because I wrote the upcoming Yale University Press book “The Aliens Among Us: How Invasive Species are Transforming the Planet—and Ourselves.” Of which this editorial would be a a clear, though decidedly bassackwards, example.

  2. ‘Foreign species’ and ‘invasive species’ are not one and the same thing although some ‘foreign species’ may be ‘invasive’. ‘Foreign’ presumably means something that was not present, at least in recent history. The horse is of course a foreign species in North America having been imported in historic times while the so-called thoroughbred horse is an even more modern import – from Scotland where it was also a foreign species. One could call the horse a moderately invasive species in parts of Canada except that we generally like horses. As we know, some native species given the right opportunity can become invasive: consider the lamprey. Others simply become ‘invasive’ when humans invade their territory: consider public park beavers and backyard bears (but not those ‘cute’ backyard deer). Some foreign and invasive species are even lionized: bass fishing tournaments abound. To be sure governments tend to suppress certain species but that is not focused on foreign and/or invasive species: certainly they are ever at war with wolves. Sometimes, they even go the opposite direction: introducing the sawfly which is every bit as mean as the deer fly to Canadian forests (we call them ankle-biters because they’ll bite you in places that are too boney to appeal to a deer fly).

  3. In the editorial on August 17, 2017 ‘Canada Should Embrace Invasive Species’, the author has missed critical key messages. First of all, there is a distinct difference between non-native species and invasive species. Canada has welcomed, and continues to welcome, thousands of non-native species – think of spring daffodils or tulips – these are friendly additions to our gardens and communities. There is only a small percentage of non-native species considered invasive and of concern. It is only these few invasive species, not all non-native species. that directly impact the biodiversity of Canada’s landscapes and cost our economy billions of dollars per year. Some invasive species even pose a direct threat to human health.

    Many of our invasive plants were intentionally planted prior to gardeners and homeowners realizing the long-term impact of this decision. High profile species, such as Giant hogweed, are triggering local governments across Canada to control or remove Giant hogweed from parks in order to avoid increased hospital visits due to the ‘sap’ causing second-degree burns. Millions are being spent annually to contain Knotweeds which can penetrate foundations, bridges and roadways. Knotweeds are very aggressive plants originally seen as providing a good ‘barrier’. Today, with more information, gardeners and landscapers are taking action to ensure they are ‘PlantWise’ to avoid planting invasive species leading to long-term impacts. Preventing new invasive plants avoids long-term costs to governments and landowners.

    Our lakes and waterways are a jewel of Canada and are being disrupted by invasive species such as European milfoils, Zebra mussels and Asian carp. None of these are arriving due to warmer winters but instead, they are introduced by people. Highly prolific, these species out-compete our native species and cause ripple effects across the local ecosystem. So, while the author thinks that mussels have changed the water clarity, he fails to mention that this is at the expense of the native aquatic species. Mussels have won the competition for food supply. However, he fails to recognize the environmental disaster that they create and the millions lost for irrigation, recreation and hydro facilities. Again, people have introduced these species and need to take action to avoid moving invasive species to new locations. Emerald ash borer, Japanese beetle or Asian gypsy moth have all arrived due to trade and none are the result of climate change.

    Our Council totally agrees that our landscapes constantly change and evolve – this is part of a natural cycle. Whether it is pioneer species being replaced by later stage species or warmer winters that allow new species to overwinter. What is not natural is when people transport ‘foreign’ species into Canada and plant or release them into our landscapes without their natural ‘predator or pests’ that keep their population in balance. Our Council is not seeking status quo but is working with partners across the country to avoid the impacts of a very few non-native species, that are scientifically recognized as invasive species.
    Canadians from coast to coast to coast are proud of our natural landscapes – with their natural rich diversity. We have invested in environmental policies and world-leading parks systems to highlight this richness. Invasive species is the second biggest threat to our biodiversity and we can all make a difference in reducing their spread. Let’s all work together to find out what we can do to protect our local landscapes. Invasive species are not part of the natural cycle!

    Gail Wallin
    Executive Director, Invasive Species Council of BC,
    Co-chair, Canadian Council on Invasive Species