Scientists race to solve mystery of scores of southern right whale calves washing up dead on Argentina's Patagonian coast

From the Newshound archive · first published 4 October 2026.

Researchers have found bacteria in tissue samples from dead southern right whale calves, which are coming ashore in troubling numbers around Peninsula Valdes, a key breeding ground in Argentina's Chubut province. Scientists say the final death count will remain uncertain until late November, when the season draws to a close. Marcela Uhart, a veterinarian leading the Southern Right Whale Health Monitoring Program, says 23 years of monitoring confirms the die-off is genuinely unusual. With decomposition setting in quickly, teams are working to gather skin and organ samples before they degrade, sending material to a veterinary school in Tandil for analysis.

The leading theory is that kelp gulls pecking at calves as they surface leave open wounds through which marine bacteria enter and cause fatal infections.

Adult whales have learned to keep their backs underwater, exposing only their heads to avoid gull attacks — but newborn calves cannot yet perform that manoeuvre, leaving them defenceless.

Climate change and El Niño-linked shifts in marine conditions are also being examined as possible contributing factors.