Dolphins have been stranding in droves on the shores of Patagonia. Scientists think they've found the culprit

"In a new study published in the journal The Royal Society, researchers show how in both cases, the presence of killer whales nearby may have spooked the dolphins, causing them to flee into San Antonio Bay's perilous shallow waters. Dolphin stranding may be triggered by myriad issues, from changing tides to prey behaviour—but the study provides novel evidence that predators may play a role, too."

"This study provides, for the first time, evidence supporting the hypothesis that such coastal incursions may be triggered by stress induced by predator presence, specifically killer whales in the area, the authors write. Orcas are known to hunt dolphins (although there is evidence some killer whales team up with other dolphin species to hunt, too)."

Multiple mass strandings of dolphins have occurred in San Antonio Bay, Patagonia, with scores of healthy dolphins washing ashore for unclear reasons. In 2021, 52 dead dolphins appeared with no wounds or disease signs. A year and a half later, hundreds more dolphins stranded in shallow waters with no deaths reported. Researchers have identified killer whales as a likely cause, showing that orca presence may have frightened dolphins into the bay's perilous shallow waters. This study provides the first evidence that predator-induced stress from killer whales can trigger coastal dolphin incursions, adding to known causes like changing tides and prey behavior.

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