What is killing whale calves in Patagonia? bacteria under suspicion

Whale calves are dying in alarming numbers along the Argentine Patagonia coast, prompting scientists and authorities to investigate potential causes. This season's mortality rate among southern right whale calves has been exceptionally high, with dozens of carcasses washing ashore in the province of Chubut. Initial findings suggest a possible bacterial infection as the culprit behind the tragic losses.

Marino Coscarella, a researcher at Argentina's National Scientific and Technical Research Council, stated that vets are currently looking into whether erysipelas, a bacterial disease common on marine mammals, could be responsible. Authorities have identified a likely candidate: a prevalent marine bacterium. However, the investigation is ongoing to confirm the exact cause of the fatalities.

Coscarella believes the evidence currently points to a natural cause, but cautions that human activity has not been entirely ruled out as a contributing factor. The provincial government is collaborating with the scientific community to determine the origin of the episode.

Southern right whales gather annually at Puerto Madryn and the Valdés Peninsula, one of the primary breeding grounds in the South Atlantic, to mate and raise their young. These massive creatures can grow up to 17 meters long and weigh around 40 tonnes as adults. In 2025, nearly 2,110 whales were recorded in the area, including around 400 calves.

Despite the recent surge in calf deaths, the researcher maintains that the episode does not yet pose a significant threat to the species' long-term survival. Southern right whales are known for their longevity, with an estimated lifespan of about 60 years.