A particularly feared invasive species, the Asian carp has found suitable habitats in areas of the St. Lawrence River, and now it seems, also in the Richelieu River.
After several decades of colonizing the Mississippi Basin, Asian carps now account for nearly 90% of the biomass in places and are significantly altering fish habitats, leading to a loss of biodiversity and the collapse of the availability of fish stocks. The United States and the Canadian federal government have implemented extensive measures to prevent the arrival and the establishment in the Great Lakes of Asian carps.
The newest invaders, bighead carp, black carp, grass carp, and silver carp that originated from Asia are collectively known as "Asian carp."
It is estimated that the establishment of Asian carps in the Great Lakes region alone could cause the loss of several billion dollars in economic spinoff because of the negative impact they would generate on the sportfishing, subsistence fishing and commercial fishing industries, boating and tourism, in addition to the risk of causing major health problems. Impacts similar to those measured in the Great Lakes region are expected in Québec.
This presence is all the more worrying as Asian carps, which group together four species, have wreaked havoc in American rivers, after being introduced by mistake. In some cases, they have virtually wiped out native species.
Natural invasion routes into Canadian waters include the artificial link between the Mississippi River and the Great Lakes through the Chicago Canal. Asian carps in the Great Lakes are set to enter the St. Lawrence River. Other natural or artificial connections can afford access routes for Asian carps, for example the link between the Hudson River and Lake Champlain and the Rivière Richelieu.
Certain human activities also pose a risk of introducing Asian carps into Canada, including Québec. For example, the use of live baitfish represents a potential pathway for the introduction of Asian carps since young fish can easily be confused with the fish usually used as lures. Activities at risk also include fishkeeping, maritime transport, the illegal importing of and illegal trade in live Asian carps for food, and religious rituals that involve releasing the live fish into the natural environment.
The Ministère des Forêts, de la Faune et des Parcs confirmed the presence of grass carp in the St. Lawrence River system in early 2017, based on the capture of one fish in May 2016 and the detection of the DNA specific to this species in water samples collected in 2015 and 2016. No indication of the presence of silver carp, bighead carp or black carp has been detected until now.
A live grass carp was even accidentally caught by a sport fisherman in July 2020 in the Chambly sector. This was the first catch of a live carp since 2016.According to a recent article by Le Devoir, this fish measured about 40 centimeters and that it was possibly a juvenile individual. By way of comparison, the grass carp caught in 2016 in the Contrecoeur sector weighed no less than 27 kilograms (kg). But this herbivorous fish can get even bigger. The species can reach 1.25 meters in length and weigh nearly 45 kg, in addition to eating up to the equivalent of 40% of its body weight each day.
According to a Fisheries and Oceans Canada report published in 2019, if grass carp settles in the Great Lakes, which are connected to the St. Lawrence, this Asian carp "could become the dominant species to the detriment of native species", "Almost completely eliminate aquatic plants" and even be "harmful" to the habitat of bird species. In 2018, the federal government decided to invest $ 20 million over five years to fight against the species.
What should you do if you think you have seen an Asian carp?
Read the comprehensive articles published by Le Devoir on this subject -( by following the link.)