(Disponible en français : La carpe asiatique aux portes des Grands Lacs)
The recent discovery of Asian carp near the Great Lakes and the confirmation of the presence of grass carp DNA in the St. Lawrence River system seem to indicate that the fight against this invasive aquatic species is on the verge of failure.
According to Fisheries and Oceans Canada (DFO), aquaculture managers in the southern United States (U.S.) imported Asian carp in the early 1970s. Major flooding in this part of the U.S. apparently allowed the species to reach the tributaries of the Mississippi River and subsequently enter the Illinois River, which flows only a few kilometres from the city of Chicago and Lake Michigan.
Asian carp species
Four species of Asian carp have been introduced to North America: the bighead carp, silver carp, grass carp and black carp. Generally speaking, these fish can grow to over one metre in length and weigh more than 40 kg. They consume between 5% and 20% of their body weight each day and reproduce very rapidly. They feed primarily on phytoplankton, zooplankton, algae, aquatic plants and mollusks.
Potential spread and establishment in the Great Lakes
According to a 2004 DFO report on the risk Asian carp pose to Canada, the concept of “establishment” refers to the colonization and maintenance of a population in an area. The United States Geological Survey (USGS) reports that the bighead carp has been recorded from within or along the borders of at least 18 states and is established in two. The silver carp has been found in 12 states and is established in two. The grass carp is the most widespread, having been found in 45 states and being established in a number of locations along the Mississippi River. The black carp has been recorded in four states, but no evidence has been found to indicate it has become established.
According to the experts, the Chicago Area Waterway System is the most likely path for Asian carp to reach the Great Lakes. To prevent them from migrating to the Great Lakes and, eventually, the St. Lawrence River, the U.S. Army Corps of Engineers installed electric dispersal barriers in the Chicago Sanitary and Ship Canal in the early 2000s. Human activity, such as the live fish trade and aquaculture, is another way that Asian carp can spread.
Click here for map description
Maps prepared by the Library of Parliament, Ottawa, 2017 using data from the U.S. Geological Survey. Nonindigenous Aquatic Species Database, Gainesville, FL. Accessed 3 August 2017; data for Asian Carp Sampling Program provided by the Department of Fisheries and Oceans, Ottawa, ON. The following software was used: Esri, ArcGIS, version 10.3.1. Contains information licensed under Open Government Licence – Canada and in U.S. public domain.
As outlined in the DFO binational assessment published in 2012, the probability of the bighead and silver carp reaching Lake Michigan by physical connections is “very likely” but “low” to “very unlikely” for the other Great Lakes. Once introduced into the Great Lakes, their probability of survival, establishment and spread would generally be very high. These carp would likely reach Canadian waters in less than five years.
As for the grass carp, the DFO ecological risk assessment published in January 2017 states that it has already arrived in Lake Michigan (by physical connection) and Lake Erie (by human activity). Over the next five to 10 years, the likelihood of its survival and establishment varies by lake from “high” to “very high,” except for Lake Superior, where winter climatic conditions are more challenging. The likelihood of the grass carp spreading throughout the Great Lakes would be more variable across the various lakes, but generally ranges from “very unlikely” to “moderate.” The experts report that it will take less than 10 years for the grass carp to reach Canadian waters after its arrival into the connected Great Lakes basin by Lake Michigan and less than a year if it is introduced into western Lake Erie. DFO does not appear to have issued a specific science advisory report on the black carp.
Why are they a threat?
DFO’s binational risk assessment states that the consequences of the presence of bighead and silver carp would include “changes in planktonic communities, reduction in planktivore biomass … and reduced stocks of piscivores [fish-eating species].” In addition, DFO’s 2017 ecological risk assessment found that the grass carp’s consumption of aquatic plants could degrade vegetated wetlands, which would have negative consequences for the entire ecosystem.
Owing to their weight, the bighead and silver carp can damage boats and fishing nets. Known for its ability to jump up to three metres out of the water when startled, the silver carp (or “flying carp”) can also injure people.
In a 2014 report, DFO estimated that the presence of Asian carp in the Great Lakes could have a “moderate” to “high” impact on commercial fishing, recreational fishing, recreational boating and beach use activities.
In 2015, under the Fisheries Act, the federal government made the Aquatic Invasive Species Regulations, which in specific geographical areas prohibit the import, possession and transport of invasive species, including Asian carp, in Canada unless they are dead and eviscerated. The Canada Border Services Agency is responsible for enforcing the import ban. In Ontario, under the Invasive Species Act, it is illegal to possess, transport or sell live Asian carp. On 1 April 2017, Quebec amended its baitfish regulations to prohibit the use of live baitfish throughout Quebec and the use of dead baitfish during the summer.
In addition to research on the ecological risks, including that of the Centre of Expertise for Aquatic Risk Assessment, DFO is carrying out various activities (research, monitoring and response) with the American states that surround the Great Lakes and a variety of organizations, such as the Great Lakes Fishery Commission. The effort to stop Asian carp from reaching the Great Lakes is overseen by the Asian Carp Regional Coordinating Committee (ACRCC). DFO, together with the Ontario Ministry of Natural Resources and Forestry, is implementing the Great Lakes eDNA Monitoring Program in the Canadian waters of the Great Lakes. The two departments are taking samples to detect the presence of Asian carp and taking response actions where necessary. The Quebec Department of Forests, Wildlife and Parks is monitoring and sampling Quebec waters through its Program to Fight Asian Carp.
Asian Carp Regional Coordinating Committee. Asian Carp Response in the Great Lakes, “Current Actions.”
Asian Carp Regional Coordinating Committee. Asian Carp Action Plan for Fiscal Year 2017, December 2016.
Asian Carp Canada. “Legislation for Aquatic Invasive Species.”
House of Commons, Standing Committee on Fisheries and Oceans. Invasive Species That Pose a Threat to the Great Lakes System, Fourth report, 1st Session, 41st Parliament, April 2013.
Conover, G., R. Simmonds, and M. Whalen. Management and Control Plan for Bighead, Black, Grass, and Silver Carps in the United States, Washington, Asian Carp Working Group, Aquatic Nuisance Species Task Force, October 2007, 223 pages.
Environment Canada and Ontario Ministry of the Environment and Climate Change, Canada-Ontario Agreement on Great Lakes Water Quality and Ecosystem Health, 2014.
Fisheries and Oceans Canada, Canadian Council of Fisheries and Aquaculture Ministers Aquatic Invasive Species Task Group, A Canadian Action Plan to Address the Threat of Aquatic Invasive Species, 1 September 2004.
Author: Geneviève Gosselin, Library of Parliament