Tragic photos released Friday revealed a whale wasteland on a grim Australian beach. The mass stranding of 140 short-finned pilot whales at Hamelin Bay left local parks and wildlife officials bereft and confused as they struggled to push the massive corpses back into the water. Such mass strandings are not unprecedented, but nobody is sure why they happen.
Pilot whales are particularly well known for stranding en masse, so while it’s a tragic event, it’s not atypical for this species of whale, says Darlene Ketten, Ph.D., a neuroethologist at Woods Hole Oceanographic Institution, in an email to Inverse. Large beaching events of many whale species have occurred throughout history, and Ketten notes “there is no indication that whales are stranded more frequently than in the past.” Still, we don’t know why they occur. In an interview with Scientific American in 2009, she said: “Statistically, we are only able to determine the cause of a stranding in about 50 percent of all cases worldwide.”
Among the theories explaining why whales get stranded en masse is one suggesting their navigation systems sometimes get confused. Whales are expert navigators, but it’s possible that a pod of whales responding to a distress call from a single individual that gets beached will come to its rescue only to become beached themselves, explained Oregon State University marine biologist Scott Baker, Ph.D., in a 2010 interview with LiveScience. He pointed out, however, that it’s not easy to tell which whale beached first after the fact.
What is also possible is that the whales’ sound-based navigation systems were confused by sonar technology: in 2014, the Natural Resources Defense Council laid blame on the U.S. Navy’s high-powered military sonar — part of its anti-submarine warfare training — for causing a mass stranding of Cuvier’s beaked whales on the coast of Crete.
It remains unclear whether climate change is affecting the rate of whale beachings. “It is unlikely that sea level rising per se will have any major influence on strandings,” says Ketten, though she notes climate change may indirectly affect the whales’ prey, habitats, and the currents in which they swim. Adelaide University’s Corey Bradshaw, Ph.D., has supported this idea by arguing that warming waters are bringing whale prey — and thus the whales — closer to the dangerously shallow shore.
The scene is grim back at Hamelin Bay, where locals have been warned that sharks may show up to feast on the bodies. Rescue volunteers, however, worked tirelessly to push the few surviving whales back into the water in hopes they’d get a second chance.