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Asian Carp

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If you think you have found an aquatic invasive species:

  1. do not return the species to the water
  2. take photos
  3. note:
    • the exact location (GPS coordinates)
    • the observation date
    • identifying features
  4. contact us to report it
Common Carp, Cyprinus carpio, while originally from Asia, arrived in North America much earlier and is not one of those species referred to as Asian carps.

Common Carp, Cyprinus carpio, while originally from Asia, arrived in North America much earlier and is not one of those species referred to as Asian carps.

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The term “Asian carps” collectively refers to a group of four species of carps: Bighead, Silver, Grass and Black carps. All are members of the cyprinid family, which includes carps and several varieties of minnows.

Where they have been found

To date, there have been a few rare captures of individual Bighead Carp and Grass Carp in the Canadian waters of the Great Lakes. Of the Bighead Carp, only three specimens have been collected, all in western Lake Erie, between 2000 and 2003, and are believed to have been intentionally released. Of the Grass Carp specimens, there have been approximately 23 single captures since 2012 in the waters or tributaries of Lake Huron, Lake Ontario, and Lake Erie (the most recent in Lake Erie in 2018). Of those captured fish, most were found to be infertile, or “triploid”. It is likely that the fish caught were escapees from areas where populations were being used for aquatic plant control, or live releases. No Silver Carp or Black Carp have been found in the Great Lakes.

Recently, juvenile Grass Carp caught in the Sandusky River in Ohio, which empties into Lake Erie, were found to have been produced by natural reproduction. There is as yet no evidence of an established population in Canadian waters, and surveillance continues.

Physical, ecological and economic impacts

Video: Protecting the Great Lakes from Asian carps

Video: Protecting the Great Lakes from Asian carps

The physical threat

The physical danger comes primarily from Silver Carp, which are responsible for generating much of the public’s attention on this species. When startled by noise, such as a passing boat motor, it will leap from the water, sometimes as high as three meters above the surface. Video of a school of these leaping fish is an impressive sight and has made it a sensation on the internet. Because Silver Carp can grow to as large as 40 kilograms, the leaping behaviour presents a serious danger for anyone on the surface of the lake or river where the fish are present.

Silver and Bighead carps can also impact fishing gear and nets as a result of the fishes’ large sizes, the density of their schools and their rigorous movement. The established population of Silver carp in the Mississippi and Illinois River systems poses a threat to boaters safety.

The ecological threat

Asian carps, and in particular the Silver and Bighead carps, have steadily been outcompeting native fishes in the Mississippi River and in the lakes and tributaries that feed the river. They are voracious eaters, able to consume 5 to 20 per cent of their body weight each day, leaving far less of the microscopic plant and animal life (phytoplankton and zooplankton) to support native fishes.

Grass Carp primarily consume aquatic plants, and their foraging can disturb lake and river bottoms, and destroy valuable wetlands. Their foraging also results in increased murkiness of the water, making it more difficult for other fish to find food. The destruction and loss of aquatic vegetation also leaves native juvenile fishes without adequate cover from predators and reduces possible spawning habitats.

Asian carps are also prolific breeders and in some areas where they have established they have dominated habitats, making up as much as 80 per cent of the biomass. That extent of biodiversity loss is apt to make the entire eco-system more fragile.

Another unknown threat involves the potential of introducing new diseases and parasites from Asian carps. Asian carps host a variety of parasites, such as the Asian Tapeworm. We don’t yet know the specific hazard these parasites might pose to native fish species.

For more information on the ecological threat, please see the 2012 Binational Risk Assessment (CSAS resdocs - 2011/114).

The socio-economic threat

Should Asian carps reach the Great Lakes, they are expected to have a huge impact on many of the activities and industries that currently take place there. A 2011 risk assessment focusing on Bighead Carp and Silver Carp reaching the Great Lakes found that the activities most likely to experience a detrimental impact are commercial, recreational and subsistence fishing, recreational boating, wildlife viewing, and beach and lakefront use.

For more information on the socio-economic threat, please consult:

Origins and mode of arrival

All of the species known collectively as Asian carps (i.e. Grass Carp, Silver Carp, Bighead Carp and Black Carp) originated in major river systems in China and Russia. These river systems, including the Pearl, Yangtze, Min, Amur and Yellow, cover a geographic range from southern Russia to Northern Vietnam, and a climatic range from sub-tropical to temperate. This range bears enough similarity to North American climatic systems to make it likely that Asian carps could survive and thrive here.

During the early 1970s, aquaculture managers in the southern United States imported these species for biological control of algae, plants and snails in their ponds. Subsequent flooding events in the southern U.S. allowed the species to escape the ponds and enter the Mississippi River system via its tributaries. Finding themselves in an ideal aquatic habitat free of any natural predators, Asian carps have been able to spread throughout that river system. Within 20 years they have reached as far northward as the Illinois River and its tributaries.

Mode of dissemination

There are two ways for these fishes to reach the Great Lakes: They could spread on their own or be transported by human activity.


The most likely path for Asian carps to spread to the Great Lakes is through the Chicago Area Waterway System (CAWS), a series of canals built in the early 20th century, creating a water connection between the Great Lakes Basin and the Mississippi watersheds. Since its original development, it has grown into a major shipping route, hosting a steady flow of barge traffic between the Great Lakes and the inland United States. It is the only permanent water connection between the St. Lawrence and Mississippi watersheds.

While there is only one permanent connection between the two watersheds, there are several other pathways that may connect these waters. Most of these areas are not liable to allow the passage of fishes, although could serve to provide pathways for other aquatic invasive species, such as invertebrates or viruses. Some of the areas of concern however, such as Eagle Marsh in Illinois, are low-lying areas, marshes, etc., that can temporarily connect the two watersheds during flooding, allowing fishes to spread. Historically there have been times when overland flooding provided such a connection.

Within the U.S., a number of steps have been taken to monitor and prevent any further migration of Asian carps northwards into the Great Lakes basin. Authorities monitoring and maintaining the control measures at the CAWS believe Asian carps have not yet reached the Great Lakes through that pathway. For more information about the defense of the CAWS and other projects and plans underway to control the spread of Asian carps, please visit the Asian Carp Regional Coordinating Committee’s website.

The US Army Corps of Engineers (USACE) is responsible for operating and maintaining the electrical defenses in the CAWS. In early 2014, USACE published the Great Lakes Mississippi River Interbasin Study report, commissioned in 2009. It lays out a range of options and technologies U.S. officials and agencies might use to prevent aquatic invasive species’ movement between the two watersheds.

Human Activity

Human activity creates several possible routes through which Asian carps might reach the Great Lakes (listed alphabetically):


All of the Great Lakes U.S. states and the Province of Ontario have legislation pertaining to restricted or prohibited transport possession or sale of live Asian carps.

Government action to stop Asian Carps from spreading to the Great Lakes

Figure 1. Map of Fisheries and Oceans Canada’s Asian carp sampling and monitoring sites in the Great Lakes. The early detection and scouting sites are indicated for the year 2013. The early detection sites indicated are on Lakes Huron and Erie, and include Mississagi, Serpent River, Spanish River, Coldwater River, Nottawasaga River, Sauble River, Pine River, Maitland River, Bayfield River, Ausable River, Detroit River, Canard River, Ruscom River, Thames River, Cedar Creek, Rondeau Bay, Jeanette’s Creek, Kettle Creek, Big Otter Creek, Long Point Bay, Nanticoke Creek, and Grand River. There are also scout sites indicated at Hog Creek and Sturgeon River.

The search for evidence of Asian carps comprises a major part of Fisheries and Oceans Canada’s efforts to combat this invasive species. In addition to traditional electrofishing and new sampling techniques, U.S. and Canadian researchers are currently exploring the results of environmental DNA (eDNA) testing (Great Lakes eDNA Monitoring Program), for its use in Asian carp surveillance. In Canadian waters, biologists from the Ontario Ministry of Natural Resources and Forestry and Fisheries and Oceans Canada work closely together to collect information and share findings. DFO and OMNR also implement response activities following any find of Asian carps in Canadian waters. Coordinating with the province of Ontario, Fisheries and Oceans Canada’s Response Plan ensures effective communications among the various agencies involved, follow-up monitoring and eDNA sampling to find out whether the specimen is an isolated incident or indicative of Asian carps having successfully established.

For a more complete description of eDNA science and technique, please visit the Asian Carp Regional Coordinating Committee.

The effort to stop Asian carps from reaching the Great Lakes continues on two fronts: blocking their spread and stopping people from bringing them here.

There is an extensive partnership of government agencies and non-government organizations involved in the effort to stop Asian carps from reaching the Great Lakes. The Asian Carp Regional Coordinating Committee (ACRCC) is the primary overseer of these efforts. Most of its members are U. S. federal or state bodies. Fisheries and Oceans Canada, the Ontario Ministry of Natural Resources and Forestry and the Quebec ministère du Développement durable, de l'Environnement, de la Faune et des Parcs are part of this vital coordinated effort. For comprehensive information on the activity of ACRCC, please see the organization’s latest framework document.

Since the early 2000s, Fisheries and Oceans Canada has done extensive work assessing the risks of Asian carps reaching the Great Lakes, as well as cooperating with partner agencies to develop and improve monitoring and control methods.

As well, Fisheries and Oceans Canada scientists are exploring alternative ways of directing fish movement to help defend those pathways through which Asian carps might reach the Great Lakes, or to help control their spread if they successfully reach the Great Lakes.

Blocking the spread of Asian Carps

U.S. federal and state agencies are managing this effort because all of the potential pathways and established populations are in American territory. Canadians can be confident of our neighbours’ motivation to maintain this effort. As our co-steward of the Great Lakes, the U.S. shares the same concerns as Canada does if Asian carps successfully establish in the St. Lawrence watershed.

The current primary defense of Asian carps’ most likely arrival route is a series of electro-magnetic fields generated within the Chicago Area Waterway System (CAWS). The fields cause fishes to experience an increasing level of discomfort as they approach, forcing them to turn away. The United States Army Corps of Engineers (USACE) built the first field generator in 2002 to test whether it could successfully repel fish. Researchers tracking radio tagged adult fish near the canal report a 100 per cent success rate so far. USACE has since installed two other generators, allowing operators to stagger their maintenance. Contract tendering is underway for the permanent replacement of the original temporary generator.

Researchers and politicians continue to explore other means of stopping the advance of the carps. As examples, engineers are testing the effectiveness of devices that fire high pressure bursts of water to create barriers to fish passage. Scientists are also experimenting with pheromones to see whether they can effectively attract or repel fishes. USACE is also embarking on plans for a renewed berm and fish fence at Eagle Marsh near Fort Wayne, Indiana, to prevent fish passage during a flood event. Researchers and engineers continue to monitor other low-lying areas along the divide between the two watersheds. Debate and research is also ongoing as to the potential to create a permanent separation of the Mississippi and St. Lawrence watersheds by closing the CAWS. In early 2014, USACE released a report from its Great Lakes Mississippi River Interbasin Study, which presents a range of options and technologies available to prevent aquatic invasive species’ movement between the two watersheds.

Stopping people from bringing them here

One of the most important elements in stopping the transport of Asian carps into Canadian waters is bringing public attention to information sources like this one. The more people know about the potential for harm from the fishes establishing in the Great Lakes, the more people will be motivated to add their efforts to stop it. Fisheries and Oceans Canada continues to play a significant role in monitoring this threat and in informing the public through various channels about the status of Asian carps.

Since Asian carps started to spread through the Mississippi system, a patchwork of laws governing the import, sale, or transport of the fish has gradually evolved into a more consistent and shared strategy. All of the Great Lakes-U.S. states and the Province of Ontario have made it illegal to buy, sell, or possess live Asian carps.

The Ontario Ministry of Natural Resources and Forestry conducts inspections of food fish importers and monitors retailers for compliance as well. Conservation officers spend approximately 2,000 hours a year on inspections, covering dozens of wholesale and import companies that work through more than a thousand different locations. In 2011 and 2012 for example, the Ontario Ministry of Natural Resources and Forestry stopped six live fish haulers, carrying more than 13 thousand kilograms of Asian carps. Those seizures resulted in several convictions and more than $100,000 in fines. Enforcement continues.

The Canada Border Services Agency is an important participant in this battle because it watches everything coming across the border. In doing so, it helps enforce not only Ontario’s ban on the import of Asian carps, but also regulations under Environment and Climate Change Canada Wildlife Services and the Canadian Food Inspection Agency.

The Great Lakes Fishery Commission, an international commission established in 1955 by the Canadian/U.S. Convention on Great Lakes Fisheries, is also pushing for clearer regulations concerning what constitutes a dead fish, since there have been confirmed reports of food fish still being alive despite being packed in ice. The Great Lakes Fishery Commission recommends that all jurisdictions on the Great Lakes adopt rules that specify Asian carps being transported as food must be dead and eviscerated. Ontario is currently considering such changes to its Fish and Wildlife Conservation Act.

Government action to stop Asian Carps from reaching Canadian waterways

Fisheries and Oceans Canada puts aquatic invasive species in general, and Asian carps specifically, among its highest priorities. Accordingly, DFO is engaged in the battle through science, monitoring and surveillance, policy and economics, and outreach and education.


In 2004, Fisheries and Oceans Canada published “Risk Assessment for Asian carps in Canada (CSAS resdocs - 2004/103)”. This report examines where Asian carps originate, analyzes the habitat and climatic conditions necessary for the species to survive and spawn, and compares those to conditions in Canadian waterways. The report’s authors found that the risk of arrival and establishment of these species in the Great Lakes ranged from moderate to high, with Lake Erie being the most likely candidate for infiltration, because of its warm, shallow waters.

The 2004 risk assessment was one of the first major Canadian activities aimed at addressing this looming threat and it materially affected legislation. Based on the report’s findings, Ontario banned the sale or possession of Asian carps.

In 2011, Fisheries and Oceans Canada led the completion of the “Bi-national Ecological Risk Assessment of Bigheaded Carps for the Great Lakes Basin” (CSAS SAR - 2011/071). This document presents a breakdown of all the possible pathways through which Asian carps might arrive at the Great Lakes. It also includes a detailed assessment of their chances for long term survival once they arrive. Its authors intended that the document provide scientifically-defensible advice for policy makers. A key element identified in the risk assessment is that there is a moderate-to-high risk that the entire system could be infiltrated and dominated by the fish within 20 years if as few as ten breeding pairs of Bighead or Silver carp were to reach any of the Great Lakes.

In 2017, Fisheries and Oceans Canada led the completion of the Binational Ecological Risk Assessment of Grass Carp for the Great Lakes Basin (CSAS SAR - 2016/057). This paper outlines the risk to the Great Lakes basin and provides useful scientifically defensible advice on prevention, monitoring, early detection and management actions that are underway or could be taken.

In addition to the risk assessments and ongoing surveillance, DFO is engaged in research that could help control the movement of Asian carp populations. A project underway at the Centre for Inland Waters in Burlington, Ontario will use confined radio-tagged fish to allow scientists to see a real time 3-D model of how the fish react to barriers created using bubbles and sound. If successful, this kind of barrier could enhance the electrical field generators currently defending the Chicago Area Waterway System, and could also lead to the creation of portable barriers that could be deployed to protect specific rivers or streams during spawning.

DFO research also continues into the likely dispersal patterns of Asian carps should they reach the Great Lakes. This movement study focuses on the Welland Canal, which connects Lake Ontario to Lake Erie, and the St. Mary’s River, which joins Lakes Huron and Superior. Both are key routes through which aquatic invasive species have spread. Scientists are tracking radio-tagged fish of varying sizes and swimming abilities through these areas to develop a clearer picture of how they disperse.

Monitoring and surveillance

Fisheries and Oceans Canada is actively engaged in monitoring and surveilling Canadian waters near the most likely arrival points for signs of Asian carps, using techniques such as environmental DNA sampling, netting and electro-fishing.

The Ontario Federation of Anglers and Hunters operates the Invasive Species Hotline, providing a valuable avenue through which the general public can contribute to the defense against Asian carps. Anyone who finds or catches a fish in Canadian waters suspected of being an Asian carp is encouraged to report it immediately at 1-800-563-7711 or Report a Sighting here.

Other Canadian partners and agencies are engaged with Fisheries and Oceans Canada in minimizing the risk of an Asian carp invasion, such as the Canada Border Services Agency, Environment and Climate Change Canada, the Great Lakes Fishery Commission and the Invasive Species Centre. Fisheries and Oceans Canada also partners with the Ontario Ministry of Natural Resources, which contributes to prevention efforts directly through provincial legislation, science and fisheries management.

Socio-economic analysis

The department’s 2004 publication of the risk assessment report was intended to provide advice and guidance for policy makers on how to respond to the threat of an Asian carp invasion of the Great Lakes. The province of Ontario responded by implementing legislation to prohibit the sale, possession or transport of any of the Asian carp species.

Outreach and education

Fisheries and Oceans Canada has maintained a policy of alerting the public when Asian carp specimens have been captured in the Great Lakes. This policy keeps stakeholders informed about the current status of Asian carps and also helps increase awareness among the general public about the risk of an invasion. To date, the public has been receptive to information and supportive of the department’s response and ongoing investment in this battle.

Since Asian carps are traditional food fish in China and other parts of Asia, the department is seeking more specific ways of educating immigrant communities in Canada about the potential danger of an invasion. The department would also like to expand its education efforts for Canada’s aboriginal communities, who would face both a loss of subsistence harvest and a significant cultural impact should Asian carps successfully establish in the Great Lakes.

Fisheries and Oceans Canada continues to work with stakeholders and industry to educate and advise them on best practices in relation to Asian carps.

What you can do to prevent Asian Carps spreading

Spread the word, not the fish.

One of the most effective ways for members of the public to assist in this vital effort is simply to share the Asian carp story with your friends, family and colleagues. The more people who appreciate the costs and dangers posed by this potential invasion, the more motivated people will be to take an active part in defending Canadian waterways from the threat.

If you are a boater or a fisher, make sure your activities never offer a free ride to an invasive plant, fish or animal via your boat bilge or your bait buckets. Many public docks offer information to boaters and other travelers about invasive species and specific local concerns, but every individual must be vigilant.

If you or anyone you know trades in live fishes, either for food or for pets, make sure you and they observe all regulations governing banned species and ask for expert help if there is any question about the identity of a particular fish.

The Ontario Federation of Anglers and Hunters operates the Invading Species Hotline. Anyone who finds or catches a fish in Canadian waters suspected of being an Asian carp is encouraged to report it immediately at 1-800-563-7711 or

Find out more

The following websites provide a thorough selection of research material and departmental reports about Asian carps and the efforts to control them:



For further information


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