Magdalena Arias of Argentina’s National Scientific and Technical Research Council explains, News.Az reports, citing foreign media.
“This doesn’t mean predators always cause mass strandings, but predator-prey interactions, combined with coastal geography, tides, and strong dolphin social behaviour, may trigger them.”
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In 2021, roughly 350 common dolphins (Delphinus delphis) raced toward San Antonio Bay in Rio Negro province, with eight orcas chasing them. Some dolphins sought refuge in shallow ports, where dozens later died. Necropsies showed the animals were healthy, with empty stomachs, ruling out disease or starvation.
A similar event occurred in 2023 when about 570 dolphins fled toward the bay. This time, local authorities and volunteers successfully rescued many after the orcas turned away.
The research indicates that dolphins may enter shallow areas to evade orcas, which can interfere with the predators’ echolocation and movement. However, these escape routes can trap dolphins among sandbanks and tidal channels. Some orcas may even deliberately drive prey toward bays, a strategy previously observed in coastal hunts of sea lions.
Researchers analyzed drone and mobile phone footage uploaded to the eWHALE platform by tourists, guides, fishers, and local residents. Combining these observations with historical orca sightings, the team mapped predator activity and linked it to the strandings.
Arias emphasizes:
“Understanding these events helps explain mass strandings, sheds light on marine ecosystem dynamics, and demonstrates the power of citizen science in research.”
This study underscores how natural predator-prey interactions, when combined with coastal geography and human observation, can unexpectedly result in large-scale wildlife tragedies.
