The sea sturgeon was initially considered harmful, but was then overfished and is now threatened by dams. Four researchers shed light on this problem and suggest solutions that need to be implemented to better protect this endangered species.
Posted at 12:00 p.m.
Special collaboration with Chloé Bourquin
A past robbery
Overfishing, poaching and, above all, overexploitation of its caviar: the causes of the global decline in sturgeon stocks are well known. Having survived several waves of extinction since the time of the dinosaurs (more than 250 million years ago), more than 85% of all sturgeon species worldwide are now threatened with extinction. However, one species in particular, the sea sturgeon, seems to have been spared the regulation so far. Unique to North America, this freshwater fish lives mostly in the St. Lawrence River and the rivers that feed it. But since 2022 it has been on the Red List of Threatened Species of the International Union for Conservation of Nature (IUCN).
PHOTO YVES PARADIS, DEPARTMENT OF THE ENVIRONMENT, FIGHTING CLIMATE CHANGE, WILDLIFE AND PARKS
The sea sturgeon is now considered an endangered species.
“This new listing of the sea sturgeon on the IUCN list is worrying and somewhat discouraging,” Constance O’Connor sighs. According to this director of the Ontario Northern Boreal Program at Wildlife Conservancy of Canada, the species is threatened today primarily because of its historical decline. Initially considered a noxious species by the first settlers, it was heavily exploited at the end of the 19th century, mainly for its meat: it is believed that more than 1000 tons of sea sturgeon were fished in the Great Lakes in 1900 in just one year. “A depletion from which the species has never fully recovered,” says Constance O’Connor.
While its fishing is only heavily monitored and permitted in a few very specific areas, the sea sturgeon is confronted with a completely different danger: the change in its habitat due to dams.
The dangers of dams for sea sturgeon
“Dams are the biggest threat to the sea sturgeon,” says Yves Paradis, a biologist at the Ministry of Forests, Wildlife and Parks.
It is a species that needs a lot of space and climbs the rapids to reproduce in white water. However, we are building dams at exactly these points that prevent access to the spawning grounds.
Yves Paradis, biologist
The spawning grounds are areas where the sea sturgeon reproduces. In the spring, it can sometimes travel hundreds of kilometers to get there. But even if he manages to gain access, dams can disrupt his life cycle. “The sea sturgeon reproduces on a substrate of large pebbles and with relatively fast currents,” said Samuel Dufour-Pelletier, director of the Environment and Land Office of the Abenakis of Odanak Council. When the eggs hatch, the larvae float with the current until they are mature enough to swim. “So if a dam sheds water or holds too much water during that time, it can affect not only its reproduction, but also the survival rate of eggs, the survival rate of larvae, the nutrition of young fish…” the researcher enumerates.
PHOTO MARTIN TREMBLAY, THE PRESS
Researcher Samuel Dufour-Pelletier studies a population of sea sturgeon.
A fish under the magnifying glass of researchers
However, the study of the sea sturgeon is a delicate task, since this fish can live for over 100 years and reaches sexual maturity after about 20-30 years: any action carried out can therefore take several decades before we can see its real impact (positive or negative ) on populations. However, researchers can rely on indirect indicators to estimate their population, such as the number of individuals, adult females, eggs, or larvae found near a spawning site. Therefore, some solutions have been developed to save the sea sturgeon, both on a small and large scale.
PHOTO SAMUEL DUFOUR-PELLETIER
Researcher Samuel Dufour-Pelletier worked with managers at a hydroelectric power station to encourage the sea sturgeon to reproduce.
In particular, Samuel Dufour-Pelletier studied a population of sea sturgeons located downstream of a dam on the Saint-François river. In particular, he noticed: “The more water there was in the river during the spawning season, the more frequently the sturgeons went to the spawning ground.” must maintain a stable flow, neither too weak nor too strong.”
The researcher worked with hydroelectric power plant managers to adjust its flow rates to avoid future disturbances to the species during its breeding season. However, “every spawning ground is different, everyone has different currents,” emphasizes the researcher. “Ideally, this type of study should be done at each dam to identify the best parameters to maximize the reproductive success of the sea sturgeon and apply them to the plant. »
PHOTO MARTIN TREMBLAY, THE PRESS
The dam at the Drummondville power station where sturgeons spawn.
For their part, Yves Paradis and his colleague Simon Bernatchez have set out to identify all known spawning sites in the Saint Lawrence and Ottawa Rivers in order to better protect them and find suitable solutions for each one. She . “The impact of dams is an important issue for the Department’s management and conservation of the species,” emphasizes Simon Bernatchez. “However, there is still a lot to do, because the distribution area of the sea sturgeon in Quebec is very large,” he admits.
Act before it’s too late
Constance O’Connor welcomes these initiatives, which she sees as vital to the survival of the species. In particular, it is recommended that this type of study be carried out more systematically and on a larger scale. “We have to find solutions so that the dams have less of an impact on sea sturgeon,” she says. “It is important to remember that even if they are not in danger today, they could be in danger. It is currently the least threatened sturgeon population but we need to make sure it stays that way. »
Learn more
Sturgeon numbers: 85% of the 27 sturgeon species are critically endangered, 63% are critically endangered, 4 of them are probably extinct
Source: IUCN