Invasive fish species have become a growing concern, particularly in this case for waterways of North America, especially in the coastal regions, Great Lakes and surrounding areas. Invasive fish species have the potential to cause serious harm to the surrounding environment and natural ecosystem by disrupting the natural balance of the ecosystem, threatening species diversity and the abundance of native species present. The resulting loss of native species such as fish due to newly introduced invasive species may lead to other non-environmental consequences such as economic loss through the commercial, agricultural, aquaculture, and recreational industries.
Due to the ease and frequency of waterway contamination by non-native fish, the introduction of invasive fish species is of a great concern. Usually, non-native aquatic species are introduced via the dumping of large amounts of ballast water by large ships. On a macroscale world wide, with the exchange of ballast water daily in international waters, aquatic organisms ranging from phytoplankton and zooplankton to fish are released into areas where they have never been found before. On a microscale, species can be introduced into new water ways and systems via recreational activities such as boating and fishing, as well as, humans illegally dumping unwanted household aquaria into the water system.
A new invasive fish species making an infamous name for itself in North America is the Northern Snakehead. The Northern Snakehead is a predatory fish which is native to the waterways of China, Russia, North and South Korea. It has been found in some American states such as New York and Maryland, as well as, recently found (and removed) in the Canadian province of British Columbia. To the adult Northern Snakehead, there is no known natural predators, making it a top predator in its newly inhabited ecosystem. Their diet consists of fish and their eggs, toads and frogs, small reptiles, mammals and birds. Having a high ability to adapt to various grades of ecosystems – it can survive out of water in moist conditions such as wetlands – and thrive in poorly oxygenated water making it a threat to the local native species.
To combat this invading species and prevent it from coming into Ontario’s waterways, the province of Ontario has implemented a ban on all 28 subspecies of the snakehead under the Invasive Species Act, thus making it illegal to buy or keep as a pet.
Monitoring of waterways and systems is a critical way to prevent and control the distribution of invasive aquatic species. Monitoring allows for us to understand the extent of the situation and is a critical step in determining appropriate responses. There are several ways to monitor a body of water for invasive fish species. Some include visual sightings, catching or trapping, and taking DNA from cells shed into the environment via water, soil or air. The DNA collected undergoes a qPCR analysis; the data is then inputted into the invasive fish species database which identifies locations tested and positive sightings of species being monitored.