Whale beachings are a mystery.
One of the world’s largest known strandings off the coast of Tasmania has shone a new light on the phenomenon.
The question of why the beachings occur has puzzled marine biologists for years.
While no-one claims to know the exact reason, it's thought the answer may lie in the animal's character.
Whales are very sociable.
As are dolphins - who are also prone to mass beaching.
They travel together in pods, often following a leader
- and are known to gather around injured or distressed members.
Strandings could be a simple case of misadventure.
One or two get into trouble, and the rest follow.
Another theory relates to electromagnetic fields.
Pilot whales use sophisticated sonar for orientation.
Solar storms or earthquakes can disrupt this.
Some scientists say connections can even be found between naval sonar and strandings.
Rescues are laborious, difficult and often dangerous.
Several people are needed per whale to try push them back into deeper water at high tide.
Rescuers try to keep the whales upright to avoid disorientation.
Harnesses and stretchers are often used,
and even boats to drag them out to sea.
Sometimes, there's nothing to be done.
Wildlife biologist Kris Carlyon is working on the Tasmania rescue.
"So euthanasia is always an option that we have up our sleeve. It's not a simple practice so particularly when we've got animals that remain semi-buoyant. We are not at a stage where we are considering euthanasia at this stage, the animals that are still alive we think we do have a chance with those given that they are wet, they are cool at this stage and we are pushing ahead with rescue at this stage but it is something that we always have in the back of our mind and can use if needed."
New Zealand and neighboring Australia are beaching hotspots,
due to large colonies in the deep surrounding oceans.
The largest stranding in recorded history was 1,000 whales in 1918,
on the shores of the Chatham Islands in the Pacific Ocean.
Pilot whales are regularly trapped in Farewell Spit,
a narrow sand bar that stretches out from New Zealand's South Island.
About 600 pilot whales beached there in 2017.
Cape Cod in Massachusetts is another global hotspot.
It averages more than 200 stranded whales or dolphins each year.
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