You can hear it in their voice, the distress. So how do strandings happen? What goes on during a rescue? And are we getting any better at saving whales? Whales can strand alone, often sick and unable to keep swimming. A sperm whale might wash up with a belly full of plastic. Or animals can strand in groups, as commonly happens with pilot whales and other orcas such as killer whales. The biggest stranding on record involved more than pilot whales in New Zealand in Marine scientist Vanessa Pirotta says there are plenty of theories, from misadventure to navigation errors.
Food shortages could be to blame, forcing whales to travel into less familiar waters to chase prey closer to shore, as could a flight from predators, poor weather or changes to the nutrient-rich sea currents that whales follow around the world. Earthquakes, solar flares and noise pollution from military sonar have also been linked to strandings.
Since navies began using sonar to guide their submarines in the s, researchers have found 12 mass strandings of beaked whales coincided with naval exercises, while 27 others involving the species happened near a naval base or ship. Another study suggested exposure to this sonar could even explain why some stranded beaked whales had shown signs of decompression sickness , known as the bends, commonly experienced by scuba divers and astronauts.
Perhaps a sick or confused matriarch wanders into dangerous waters. But Meynecke notes that a pod of hundreds is not typically led by one leader. And that means mass strandings of this scale happen in more of a chain reaction than one mad rush. Some come in, and then later, hours, even days on, more come. Whales, such as this humpback calf, can communicate with each other over vast distances.
But noise pollution is making it harder for them to hear one other. Credit: Shutterstock. In such a case, he says, many subgroups may have come together and the leader of one, perhaps confused or starving, may have led her own companions astray.
Sometimes a sick animal will move to shallow water to try to survive. Whales are marine mammals after all — they breathe air. Workers cover a beached pilot whale but not its blowhole to keep the sun off as they attempt to rescue it after a mass stranding at Marion Bay, Tasmania, in Whales do not normally venture into shallow water. But some stretches of coast can trap them in the geography, with waters shifting suddenly from deep water to sand banks and mud. In another very rare event in September , three humpback whales took a wrong turn inland and ended up in a Northern Territory river filled with crocodiles.
Two quickly turned back out to sea, but one whale travelled upstream more than 30 kilometres before returning safely to the open ocean more than a week later, at high tide, under the anxious gaze of rangers.
By the time the whales realise they have strayed too far, they are trapped. They panic. In Hervey Bay, Franklin and his wife, Trish, have studied humpback whale mothers teaching their young to navigate the shallows without beaching.
Tasmania and neighbouring New Zealand are hotspots for mass strandings — the site of the September pilot whale stranding, Macquarie Harbour, is notoriously treacherous for boats, let alone whales. The whales stranded on a sandbank at Macquarie Harbour off Strahan in September. She said photographs of the animals, believed to be a pod of juvenile males, would be shared with the cetacean strandings investigation programme and it was now the responsibility of the council and beach owners to plan what happened to the bodies.
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