Freshwater Fisheries in Canada: Historical and Contemporary Perspectives on the Resources and Their Management

Abstract

Abstract.—The number of nonnative freshwater fish species introduced into, and within, Canada has increased over time. Twenty-one exotic species, not native to Canada, are now established in Canada and were historically introduced through legal stocking. More recently, several species were introduced through ballast water, a vector that now appears to be effectively regulated, and species illegally released into the wild from the live food trade appear to be the emerging primary vector of introduction of exotic species. The primary impacts of exotic species are competition with and, to a lesser degree, predation on or hybridization with, native species. At least 26 species native to Canada have become introduced and established beyond their native range. These human-mediated range expansions of domestic nonnative species were the result of legal stocking, which no longer legally occurs. However, illegal stocking continues to be an ongoing problem. Most domestic nonnative species compete with native species but, unlike exotic species, many also predate on native species. Under Canada’s national aquatic invasive species (AIS) regulations, only four species are prohibited from importation nationally and the introduction of 26 domestic species is prohibited beyond their native range. Five provinces have AIS regulations that include prohibition of some exotic and domestic nonnative freshwater fish species. The ongoing introduction, establishment, and spread of both exotic and domestic nonnative freshwater fish species across the country is an indication that existing AIS regulations are not working. Unless AIS regulations are more effectively implemented, the introduction of exotic and domestic nonnative species will continue and likely be exacerbated by climate change.