Authorities and researchers in Argentine Patagonia have been placed on high alert following the deaths of hundreds of southern right whale calves in recent months. The surge in fatalities has occurred during the current breeding season, leading scientists to investigate a potential bacterial infection as the primary cause for the exceptionally high mortality rate.
Just this week, dozens of dead whale calves have appeared on beaches in the province of Chubut, in southern Argentina. Cases have been recorded since June, affecting one of this species' main breeding grounds in the South Atlantic. This region, particularly the area around Puerto Madryn and the Valdés Peninsula, serves as a critical breeding refuge for the species. Every year, these waters host large groups of whales that arrive to mate and raise their young. As adults, these cetaceans can reach lengths of approximately 17 metres and weigh around 40 tonnes.
Mariano Coscarella, a researcher at the Marine Mammals Laboratory of the National Scientific and Technical Research Council (Conicet), noted that the mortality rate among calves is notably high this season. Veterinarians are now investigating whether erysipelas, an infectious disease caused by bacteria that are often present on the skin of these mammals, could be behind the deaths. Official analyses also suggest the presence of a common marine bacterium. However, the investigation remains ongoing to determine the definitive cause of the fatalities.
Regarding the possibility of human involvement, Coscarella stated that while current evidence points toward a natural cause, the influence of human activity cannot be entirely ruled out at this stage. The provincial government is collaborating with the scientific community to track the origin of the episode.
Data provided by Coscarella indicates that 1,375 whales were recorded in the area this year, including nearly 400 calves. This follows a record count of 2,110 whales in 2025, which included approximately 800 juveniles. Despite the current spike in deaths, experts do not believe the episode poses a medium-term threat to the regional population, citing the longevity of the southern right whale, which can live for approximately 60 years.
