Investigators probe deaths of hundreds of whales in Patagonia

Scientists are investigating a suspected bacterial infection responsible for the deaths of hundreds of baby whales in Patagonia, according to a marine mammal expert. This follows a disturbing trend of dead calf carcasses washing up on beaches in southern Chubut Province since June. Mariano Coscarella, a researcher at the Marine Mammals Laboratory of the CONICET national scientific research council in Puerto Madryn, noted that the death rate among young whales is unusually high this season.

While infant mortality among southern right whales is common, Coscarella stated that the number of recorded deaths this season is higher than usual.

Veterinarians investigating the cases suspect an outbreak of erysipelas, a serious bacterial disease often found on the whales' skin. However, this hypothesis has yet to be confirmed. Coscarella emphasized that the cause is likely a natural phenomenon, although he acknowledged that human activity could potentially play a role. The Chubut provincial government confirmed that they are collaborating with scientists and research teams to examine the dead whales and analyze samples.

According to the government, the suspected bacteria is common in the sea and can cause systemic infection in baby whales. However, there is currently no evidence to attribute the deaths to human activity. The breeding grounds of Patagonia, specifically Puerto Madryn and Peninsula Valdés, are internationally recognized as crucial for southern right whales in the Southwest Atlantic. These whales can reach lengths of up to 17 meters and weigh around 40 tons.

In 2025, a record 2,110 whales were counted in the area, including over 800 calves. This year's survey recorded 1,375 specimens, comprising nearly 400 young whales. Coscarella noted that the recent deaths do not pose a medium-term threat to the population, as acute mortality generally affects only a fraction of newborn whales. Southern right whales have an average lifespan of around 60 years.