The carcass of a seal that was likely eaten by a white shark washed up in Rivière-au-Tonnerre on Wednesday, halfway between Sept-Îles and Havre-Saint-Pierre. Discoveries of this type, reported more and more often in the Gulf of St. Lawrence, signal the possible return of the large predator to the mouth of the river.
“Last year, we started receiving more reports of seals with specific injuries,” explains Patrick Weldon, head of the intervention program at the Quebec Marine Mammal Emergency Response Network (QMMERN). “We are working with partners to identify the origin of these injuries, and in about 40 cases, in 2023, it is probable predation by great white sharks that explains them.”
Necropsies carried out at the Faculty of Veterinary Medicine in Saint-Hyacinthe confirmed 14 cases that bear the claw—or rather the tooth—of the great white shark. A figure that contrasts sharply with previous years, underlines Patrick Weldon.
“We have a lot more. In 2023, having 40 suspected incidents, whereas before we had 2 or 3, is definitely a good increase!”
Several factors can explain the statistic. First, the RQUMM benefits from greater resources to fulfill its mission. “The Network has existed for 20 years, and for the first 15 years, I would say that surveillance relied almost entirely on a network of volunteers of about 200 people, but spread across the territory and with limited resources. Since 2018, we have truly had internal intervention teams. We have five today, which increases our capacity to collect data tenfold.”
In light of the cases recorded by the RQUMM, researchers are looking into the habits of the white shark in the Gulf of St. Lawrence and are sketching out hypotheses that point to an increased presence of the species in its waters, attributable less to global warming than to the significant presence of its main prey: the seal.
“The number of documented cases of shark predation appears to have increased over the past two years,” wrote Ysanne Michaud-Simard and Stéphane Lair of the Canadian Wildlife Health Cooperative last September. “This situation could be caused by an increase in the Gulf’s use by this species.”
The two researchers also suggest that white sharks are more familiar with the seal’s preferred sites and are expanding their hunting territory.
The Brion23 expedition, led last year by EcoMaris and the St. Lawrence Shark Observatory (ORS) off the eponymous island, showed how much the “great whites” prized these waters off the Magdalen Islands.
The choice of Brion Island was not random. This isolated and uninhabited island of 6.5 km2located 16 km north of La Grosse Île, is home to a seal population estimated at 10,000 individuals, according to the ORS. In 2022, 42 white sharks had been spotted near the archipelago’s gray seal colonies.
Such a pantry has long made Hollywood’s most famous marine predator salivate. Since the beginning of the 18th centurye century, fishermen’s stories reported the presence of a bad fish which attacked boats – and devoured its unfortunate passengers.
“The white shark could be on the verge of making a comeback and thus reestablishing its former hunting grounds in the St. Lawrence, particularly on Brion Island,” the Observatory indicates on its website. This comeback, if true, would result mainly from the protection measures enjoyed by endangered white sharks and their main prey, the seal. Global warming would thus play a secondary role in the increased presence of the white shark in the Gulf of St. Lawrence. It frequented these waters well before the industrial era: white shark teeth dating from 5,000 to 950 years BCE were found in the Montreal region, the ORS also reports.
Swimmers, fishermen and divers should not fear suffering the same fate as the seal found Wednesday in Rivière-au-Tonnerre. The last fatal encounter between a shark and a human in Canada dates back to 1953. The cause of death is believed to be… drowning.