A species several thousand years old, the gray trout, struggles to reproduce in certain bodies of water, including Lakes Massawippi, Memphrémagog and Mégantic. Less than one trout in five comes from natural reproduction, according to data from the Ministry of the Environment. The exact causes of this phenomenon remain to be clarified, but several experts are already pointing out the deterioration in the quality of the lakes and are proposing to take action.
The Ministry of the Environment judges that the reproduction rate of gray trout, also called lake trout, is worrying
in certain lakes in Estrie.
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In the three affected lakes, there are only 5 to 20% of trout from natural reproduction, according to data from ministry biologist Jean-Sébastien Messier. From 80 to 95% of the specimens recorded during inventories come from almost annual seeding operations in Quebec.
These are worrying proportions. The objective of seeding is really to support the population, and not to 100% ensure its maintenance. Currently, we are close to seeing this situation.
If we stopped seeding, we would really see problems with the populations, and the abundance could decrease very, very significantly.
explains the biologist.
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Jean-Sébastien Messier is a biologist at the Ministry of the Environment.
Photo: - / Thomas Deshaies
Jean-Sébastien Messier explains that more than 20 years ago, around half of the specimens inventoried were of natural origin. Slowly [progressivement]we saw the marked fish [ensemencés] gain momentum.
The ministry has been able to identify stocked fish since 1994, when it began mark by removal of the adipose fin
we explain in a report produced by Mr. Messier. This fin is located between the dorsal fin, on the “back” of the fish, and caudal, at the end of their tail.
Multiple hypotheses
Jean-Sébastien Messier lists several hypotheses which remain to be proven to explain the low reproduction rate of trout, including the warming of the water.
He also believes that increased sediment in the water, from erosion, could harm reproduction. The spawning grounds [les lieux où les poissons déposent leurs œufs] need a coarse substrate with very little sediment, because we must have very deep gaps so that the eggs can hide, safe from predators.
The ministry plans to continue its research to try to identify more precisely the causes of the change in behavior of gray trout. We are on a tour of our main bodies of water to characterize the spawning grounds, to see where they are and in what condition they are.
specifies the biologist.
Concerns in Lac-Mégantic
It’s still quite alarming
exclaims the committed citizen of Lac-Mégantic Robert Bellefleur, who broadcast a video a few days ago on the issue in order to make it known to his fellow citizens. The video has already been viewed more than a thousand times.
He places the blame on the excessive sediment supply in Lake Mégantic. I am a diver, and I notice that the water in the lake deteriorates every year
he emphasizes.
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Robert Bellefleur notes that sediments are present in large quantities around the spawning grounds.
Photo: Courtesy of Robert Bellefleur
A hypothesis that the general director of the Chaudière River Watershed Committee (COBARIC), Véronique Brochu, considers entirely plausible. This is really what is damaging to the environment.
Lake Mégantic would also be more vulnerable than other bodies of water, according to her, because of its geological context
. The territory of the Mégantic sector is sand with large pebbles, she explains. As soon as we have a hydrological surface modification [comme des travaux de construction]all the sand goes into the water. As soon as there is a splash of water, it shows.
The president of the Lac-Mégantic Hunting and Fishing Association, Pierre Grenier, can see this. We have been working on various projects for several years, including cleaning the spawning grounds, but it doesn’t achieve much, because after a few years, the sediment fell back onto the spawning grounds.
he laments.
When we catch a gray trout, it is very rare that it is a wild one.
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Pierre Grenier says he has observed a drop in fish reproduction.
Photo: - / Thomas Deshaies
Projects to try to improve the situation
Despite the discouraging observation, Pierre Grenier is not giving up. You should never throw in the towel and admit defeat
he exclaims. His association hopes to obtain the green light from the government to intervene in the Arnold River, which is responsible for a significant supply of sediments into Lake Mégantic.
The COBARIC is working with the Municipality of Nantes to build a form of sump
which will capture sediment from the water par centrifugation
. With the issues at stake, we must go beyond what is obligatory
underlines Véronique Brochu.
I believe that the efforts we must put are not in understanding this problem. We don’t understand it completely, but we know enough to act.
She believes that we should definitely not wait until we have certainty about the causes of the low reproduction rate of trout before intervening.
Also in action at Lake Massawippi
At Lake Massawippi, the conservation organization Bleu Massawippi also wants to tackle the problem. Every year, approximately 7,000 stocked lake trout are introduced into the body of water.
The current data on the low reproduction rate did not leave the organization’s general director, Laurence Renaud-Langevin, indifferent. We say to ourselves that there is something happening, she emphasizes. It was definitely a surprise.
She wants to intervene to guarantee a beautiful living environment for species
. She would also like to contribute to research by analyzing the contents of the stomachs of fished lake trout. to know if the fish eat the little ones
.
Robert Bellefleur also believes that efforts must be redoubled before the situation becomes even more worrying. The name of Lake Mégantic in the Abenaki language means “the place where the fish hang out,” he explains. Maybe we’ll have to reconsider it, eventually.
he quips.
We know what to do, but do we want to give ourselves the means to do it?
Véronique Brochu also believes that we must improve the water environment
of faster way
while there were few environmental gains, according to her, from 2000 to 2015.
Concerns for several species
Reproductive challenges also concern several other species, according to biologist Jean-Sébastien Messier. For landlocked salmon [une autre espèce de salmonidés]the population depends almost 100% on sowing [au lac Memphrémagog]so it’s problematic
he explains.
We cannot turn things around as quickly as we would like. We are working to find explanations. What we would really like is a situation where natural reproduction would dominate.
He believes that the state of health of lake trout is a good indicator of the quality of the environment
. These are species sensitive to the degradation of habitat quality
. Same story with Véronique Brochu. We must monitor biological indicators like lake trout
she emphasizes.
Jean-Sébastien Messier believes that lake trout are a important heritage to preserve and an important link in the food chain
. It is a fish that arises from the ice age, from the retreat of glaciers
he insists.
The ministry plans to continue collecting data to find more precise answers about the causes of the problem. At the same time, several actions will continue, including the annual rescue of lake trout who are stuck at the bottom of certain dams.
