Ontario Fishing Lodges and Resorts

The Grass Carp Invasion: A Threat Lurking in Canadian Waters

Brennan Harbour
Anglers Kingdom
Ellen Island Camp
Northern Walleye Lodge
Lake Herridge
Grass carp

What Are Grass Carp?

Grass Carp are one of the four species of invasive Asian carps that are members of the cyprinid family and are related to several varieties of minnows. These carps are all native to the rivers, reservoirs, and lakes in China and southern Russia, and although there have been a few rare captures of individual Grass Carp, there are currently no established populations of Asian carps in the Canadian waters of the Great Lakes. We want to keep it that way!
Of the four species of Asian carps (Grass, Bighead, Black & Silver), Grass Carp pose the most imminent threat to the Canadian waters of the Great Lakes. Grass Carp eat primarily aquatic plants and can consume up to 40% of their body weight in food daily! That is like a person eating 40 large pizzas, 430 cups of lettuce, or 180 burgers! Of this 40%, only about half of the plant material that they consume each day is digested. The remaining waste is expelled into the water, creating pollution, promoting the growth of toxic algal blooms, and reducing overall water quality. These aggressive eating habits alter ecosystems by reducing food sources, shelter, and spawning areas for native wetland species, especially native fish species. If Grass Carp were to become established in the Canadian waters of the Great Lakes, negative impacts would be predicted for 33 native fish species, including reductions in population sizes for popular sport fishing species such as Walleye, Smallmouth bass, Muskellunge, Yellow perch, Northern pike, and Largemouth bass.

Grass Carp

What Do Grass Carp Look Like?

The body of a Grass Carp is oblong shaped with a slightly flattened head and moderately small eyes centered on the side of the head. They are covered with large overlapping scales, and coloration varies from blackish to olive-brown with brassy or silvery-white on the sides and belly. Scales on the back and sides are outlined by pigment giving a cross-hatched effect. Identifying Grass Carp can be a difficult process due to the number of non-invasive look-a-likes. Common look-a-like species during adult life stages include Common Carp, Golden shiner, Fallfish, Creek chub, White sucker, and Bigmouth Buffalo. In addition to this, identification also proves to be difficult during the juvenile life stages, as young Grass Carp can resemble common baitfish species such as the Bluntnose minnow, Brassy minnow, Fathead minnow, Common shiner, and more! Grass Carp can reach massive sizes reaching lengths up to 5 ft and can weigh up to 100 lbs! With these rapid growth rates, it’s unlikely that their population sizes could effectively be controlled by native predator species.

Grass carp

Credit: Asian Carp Canada

Economic Impacts

Aside from the ecological impacts Grass Carp would produce if they became established in the Great Lakes, such as habitat loss/degradation, and reductions in native species biodiversity, there would also be a correlation between Grass Carp establishment and Canada’s economy. The Great Lakes basin is an incredibly valuable resource to the Canadian economy through several ventures, including recreational, commercial, and subsistence fishing. The Canadian recreational fishing industry alone is worth $556 million USD. A large amount of this money is

Credit: Invasive Carp Regional Coordinating Committee

contributed by anglers through the purchases of fishing licenses, fishing equipment, gear, and tourism. Reduced recreational fishing opportunities due to Grass Carp establishment would have an impact on other businesses and livelihoods that depend on the development of this sector, including bait and tackle shops. Beyond the fishing industry, Grass Carp establishment could also have the potential to negatively impact industries such as hunting, recreational boating, wildlife viewing, beaches, and lakefronts.

Credit: Toronto and Region Conservation Authority

What Should I Do if I Catch a Grass Carp?

In Ontario, invasive species should be reported to the Invading Species Hotline (1-800-563-7711), the EDDMaps app (available for Apple and Android), or eddmaps.org
Reporting suspected sightings of Grass Carp is crucial in preventing their establishment in the Canadian waters of the Great Lakes and reporting can’t take place without proper identification!

If you think you have caught or seen a Grass Carp, follow these steps found in the Grass Carp Identification and Reporting Guide: https://www.asiancarp.ca/grass-carp-identification-and-reporting-guide/

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