The data of the ministry do not, however, allow to assess if the number of carp increases, which could indicate that it breeds in Quebec.
Even though the extent of its presence remains for the moment a mystery, the asian carp is always present in the St. Lawrence river, show the most recent data collected by the experts of the Quebec government and obtained by The Duty. This invasive species, which is already installed in the Great Lakes and that has made havoc in the United States, could very well reproduce in the rivers of quebec.
According to the data provided by the ministry of Forests, Fauna and Parks (MFFP), the biologists in charge of the “quebec Program to fight against the asian carp,” have collected a total of 483 samples of water in the St. Lawrence river and its main tributaries (the rivers Richelieu and Ottawa river) in 2019.
“Of these samples, 13 were positive for the grass carp. The sectors concerned are the Richelieu river, the Saint Lawrence river between Montreal and Sorel and lake Saint-Louis, ” says the MFFP. The samples contained in the” environmental DNA ” indicating the presence of this species, which is part of the four species of asian carp. The other species have not been identified in the quebec waters.
In comparison, by 2018, 2 out of the 331 samples collected revealed the presence of the carp, compared to 12 samples in 2017 and 16 in 2016. But in spite of the annual fluctuations in the data collected from 2016, the presence of the species in quebec’s waters, is ” recurring “, insists biologist Olivier Morissette, head of the division for aquatic invasive species in the MFFP.
The data of the ministry do not, however, allow to assess if the number of carp increases, which could indicate that it breeds in Quebec. “With environmental DNA, there is no interpretation on the abundance. All we can say is that the DNA is present in the system. And for the grass carp, the signal is recurring, ” says Mr. Morrissette.
What’s more, experts are still struggling to capture a carp, admits the biologist of the MFFP. “It is a species that is difficult to capture. We need specific techniques. They exist and our teams are able to capture the species, but the system of the St. Lawrence river is very wide. It is therefore a colossal task to attempt to follow the species or catch fish. “The work will continue this year, despite the health crisis.
The only capture of a grass carp back to 2016. It had been taken in the area of Reluctantly and she weighed not less than 27 kilograms. But this fish is a herbivore can become even bigger. The species can reach 1.25 m in length and weigh around 45 kg, in addition to eating up to the equivalent of 40 % of its body weight each day.
One thing is for certain, this invasive species coming from China, seems to favour some sectors of the system of waterways linked to the river St. Lawrence, which the mouth of the Richelieu river. “It is a species that breeds in areas of strong current and that feeds in aquatic plant communities. The system Saint-Laurent has these two elements in large quantities, ” says biologist Olivier Morissette.
The experts of the ministry have not yet found evidence to conclude that the grass carp reproduces in Quebec, even though this risk is entirely plausible, ” he stressed. “We remain very vigilant. “
A report to Fisheries and Oceans Canada, published last year, showed that the grass carp have reproduced already in a tributary of lake Erie. The federal government fears the worst. If the species moved into the Great Lakes, which are connected to the St. Lawrence river, the asian carp ” could become the dominant species to the detriment of native species “, “the almost complete elimination of aquatic plants” and even be “harmful” to the habitat of species of birds, concluded the report of 2019.
In this context, the carp represents “a threat to important ecological, “which” may disrupt the ecosystem and economy of the Great Lakes region if we do not put an end to its spread, ” says the document, Fisheries and Oceans Canada. Over 40 years, the impact would exceed $ 2.6 billion, only for the canadian economy.
The asian carp were imported to the United States in the 1970s for use in aquaculture. In floods, they were able to reach the Mississippi river, then up the mythical river and invade water courses attached to him over a distance of more than 1500 kilometres. In the Illinois river, a few tens of kilometres of the Great Lakes, the carp represent to some places more than 90 % of the animal biomass of the water courses. No action taken to try to eliminate it or to control its presence has not worked in the United States.