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At a time when the governments of Quebec and Canada are committed to better protecting the habitat of the St. Lawrence beluga, the bad news continues to accumulate for this endangered species. The most recent assessment of the carcass recovery program shows that mortalities remain high for females and newborns, segments of the population essential to ensure the survival of the species.
According to data published by the Quebec Marine Mammal Emergency Network (RQUMM), 12 belugas were found dead adrift or on the shores during the year 2022. Over a period of five years, i.e. from 2018 in 2022, the toll stands at 74 carcasses. However, these individuals do not represent an exhaustive death toll for this population, which today numbers less than 900 animals.
“What is worrying in this report is the high number of females and newborns counted, a phenomenon that has been observed for ten years”, underlines the RQUMM in its analysis of the data. Among the 12 animals identified, it was possible to determine the sex for 11 of the cetaceans: seven were female and four were male. And among all these animals, four were newborns.
Farrowing
A necropsy report produced by the team from the Faculty of Veterinary Medicine at the University of Montreal revealed a tear in the uterus of a pregnant female found in Tadoussac. Her fetus was almost full term. Dystocia, a complication during birth, would have caused the death of this female and her fetus. In the St. Lawrence beluga, “these dystocia have been common for a few years,” specifies the RQUMM.
“The problems of dystocia still seem to be topical,” emphasizes Stéphane Lair, full professor at the Faculty of Veterinary Medicine at the University of Montreal. The carcass of another female at the end of gestation was also sent to the Faculty of Veterinary Medicine, but the results are still awaited.
In 2021, two females found dead were cases of dystocia. Moreover, a report produced by Stéphane Lair’s team has already concluded that difficult birthing has become “the most important cause of mortality for adult female belugas in the St. Lawrence”.
Scientific Director of the Group for Research and Education on Marine Mammals and Coordinator of the RQUMM, Robert Michaud is concerned about a “serious and lasting trend” of deaths among females and very young belugas, also called “calves”. “Female calves that have not been born since 2010 would have started to produce calves in turn since 2020. The population impact of this selective mortality is yet to come,” he explains to Le Devoir.
Multiple risks
“Presence of ships, contaminants in the water, variation in the abundance of prey and climate change, the factors that affect the beluga are numerous,” indicates the RQUMM. However, it is difficult to name with certainty the causes of this increase in the mortality of females and newborns, “because although several stressors affect the beluga, we do not yet know the contribution of each,” adds Robert Michaud.
With regard to the problems in females, and in particular pregnant females, certain avenues are analyzed by scientists, including the reduction in the quantity and quality of prey, but also the possible increase in energy demand attributable to the disappearance of the winter ice cover.
It must be said that if belugas spend a good part of the year in the estuary, their winter habitat would probably be concentrated in the Gulf of St. Lawrence, particularly along the North Shore and around the island of Anticosti. However, the ice that they use in particular to protect themselves from storms has seriously receded in recent years.
In addition, the Legault government must decide this year whether to authorize two recurring dredging and sediment disposal projects in an area of critical beluga habitat located in the Cacouna region, which is considered a “nursery” for the species. However, there is no scientific study to assess the impact of these operations, recently revealed The duty.
The situation of this emblematic species of the health of the St. Lawrence ecosystem will be the subject of a “symposium” at UQAM from May 3 to 5. This event marks the 35th anniversary of the “International Forum for the Future of Belugas”, which had been a milestone for scientific research and conservation initiatives, including the creation of the marine park.