Assessing the Biological Risk of Asian Carps to Canada
Becky Cudmore and Nicholas E. Mandrak
Abstract.—There are four species collectively known as the Asian carps: grass carp Ctenopharyngodon idella, bighead carp Hypophthalmichthys nobilis, silver carp H. molitrix, and black carp Mylopharyngodon piceus. These species have been introduced worldwide for aquaculture purposes. Subsequent to introduction into the southern United States, three species have become well-established in the wild (grass, bighead, and silver carps). Two of these species, bighead and silver carps, have been dispersing rapidly up the Mississippi River basin, wreaking ecological havoc along the way. As there are numerous connections between the Mississippi basin and Canadian watersheds, including the Great Lakes, there is considerable concern about their potential ecological impacts if introduced and established in Canada. In addition to natural dispersal, these species may also be introduced into the Canadian wild through the live food fish trade. In 2004, the Canadian federal department of Fisheries and Oceans Canada conducted a risk assessment to determine the ecological risk of Asian carps to Canada. This assessment included evaluating the risk of survival, reproduction and spread of these species, as well as their pathogens, parasites, or fellow travelers (e.g. other invasive species), should they be introduced into Canada. These components were assessed in an expert workshop using best available information on their biology, potential vectors of introduction, and impacts in both native and introduced ranges. The assessment concluded that the risk of impact was high in, at least, some parts of Canada, including the southern Great Lakes basin by all four Asian carp species.