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The mystery surrounding mass whale strandings

In Tasmania, rescuers successfully freed two stranded sperm whales this week. Unfortunately 20 other sperm whales died near Strahan. Two more whales died in nearby Macquarie Harbour. Among the whales was a minke whale, stuck on a mudbank off Elizabeth Island.

Why does this happen? According to experts who were working to free the whales, nobody knows what caused these whales to beach themselves. Ocean Beach in Tassie, the spot where this week’s disaster happened, is called a ‘whale trap.’ More than 80% of the mass strandings in Australia happen in Tasmania.

Every year up to 2,000 animals beach themselves, but whales (especially the toothed type) are more likely to get stranded than other species due to some characteristics that they share. Toothed whales are social and hang out in pods, so if one gets in trouble, the rest could follow. So is it just a matter of one lost whale causing the rest to die, or is there more at play?

Mass strandings are always a cause of speculation when something like this happens. They range from suicide theories, to whales mysteriously getting off course by a natural phenomenon. We list some possible, more plausible, causes here:

1. Natural causes

- rough weather - weakness (age/illness/pregnancy) - water temperature Research by the University of Tasmania showed that when cool water from the South Pole, which are rich in fish, flow north, whales hunt closer to the shore. And the echo-location system that whales possess, doesn’t pick up on very gently sloping ocean floors near coasts very well. Remarkable is that killer whales seem to have developed a way to hunt in shallower waters, while other whales didn’t.

2. Behavioural causes

- navigational errors - predators herding whales towards beaches, or the opposite: whales following prey to close to the beach - social tendencies: toothed whales have very close family bonds

A single stranded animal which sends out distress signals, can cause an entire pod to respond and strand alongside it.

3. Magnetic field disruption

A high-regarded American geologist developed a theory that attributes the strandings to radical changes in the Earth’s magnetic field before an earthquake hits, in the area of an earthquake. Just like more pets start to run away from home days before an earthquake, mammals in the ocean and even migratory birds are affected.

4. Beaching due to sonar

There is even evidence that the use of sonar leads to beaching. Beach strandings have occurred after military sonar use in certain areas. The whales which died after such an event, have found to be injured internally, this while beached whales in most other areas appear to be healthy before they died on the beach.

What is your theory about mass beach strandings? Have you ever seen a beached whale? Share your stories and opinion with us below!