What is the cause of the killer whale mass stranding in Argentina?

Scientists are investigating the cause of the mass stranding of 26 ecotype D killer whales in Argentina's San Sebastian Bay, but so far autopsies have revealed no signs of injuries or trauma.

When was the last time a global mass stranding of killer whales occurred?

Prior to this incident in Argentina, the last recorded global mass stranding of killer whales was in 2022 in the Strait of Magellan, where 9 orcas were found dead. Before that, the only other such event was in 1955 in New Zealand, where 17 orcas were discovered stranded.

Home / Environment / Rare Ecotype D Orcas Found Dead in Unprecedented Global Event

Rare Ecotype D Orcas Found Dead in Unprecedented Global Event

Q: How rare is the ecotype D killer whale?

The ecotype D killer whales are a rare and distinct subspecies, characterized by their small eye patches, rounded heads, and faint markings behind their dorsal fins. This makes the mass stranding of 26 of these orcas an even more puzzling and concerning event.

16 Oct

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Summary

26 ecotype D killer whales stranded dead on an Argentine beach
Third recorded global mass stranding of orcas in history
Scientists investigating cause, no signs of injuries or trauma

On September 18th, 2025, marine biologists were stunned to discover 26 dead killer whales, or orcas, washed up on a beach in Argentina's San Sebastian Bay. The victims were identified as ecotype D orcas, a rare and distinct subspecies characterized by their small eye patches, rounded heads, and faint markings behind their dorsal fins.

This mass stranding is only the third of its kind ever recorded globally. The previous incidents occurred in 1955 in New Zealand, where 17 orcas were found dead, and in 2022 in the Strait of Magellan, where 9 orcas turned up deceased.

A team of researchers from the National Scientific and Technical Research Council (CONICET) and the Southern Centre for Scientific Investigation (CADIC) have launched an investigation to determine the cause of this unprecedented event. So far, autopsies have revealed no signs of injuries or trauma on the killer whales. The scientists are now collecting biological samples and analyzing environmental factors to uncover what led to this tragic and puzzling mass stranding.

Killer whales are the apex predators of the ocean and play a crucial role in maintaining the balance of marine ecosystems. The loss of 26 orcas, especially a rare ecotype, is a concerning development that has left the scientific community searching for answers.

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