What pushes whales ashore?

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145 pilot whales were recently found dead as a result of a mass stranding on a remote beach in New Zealand. Whale stranding is anything but new in New Zealand especially during the spring and summer months along the Southern Hemisphere. Multiple theories behind the repeated occurrences have been speculated but no certain conclusion has been reached to help create a solution.

In fact, whales have a long history of beaching themselves dating back to at least 300 B.C. However the trend in recent years has been growing significantly and scientists continue to be puzzled about the reasons why it occurs. Many scientists have conducted a list of possible reasons for the increase in whale beaching.

As many as 145 pilot whales died after a mass stranding which was discovered by a hiker on Saturday, Nov. 24, 2018. /AP Photo

1. Sickness or injury

Just as human beings are subject to sickness or natural diseases, whales may suffer from ailments that make them too weak to swim. On top of that, whales can become injured or disoriented after collisions with ships or boats so they end up stranding themselves.

Stranded whales on the beach at Hamelin Bay, March 23, 2018. /Reuters Photo

2. Pollution or temperature changes

Gradual intakes of man-made chemicals and waste in the sea can also sicken whales or even poison them. Moreover, changes in the water temperature may pose another factor that triggers a different behavior.

3. Man-made sonar

Whales use echolocation to tell them about the space around them, man-made sonars may disturb their brainwaves and make them lose their sense of direction.

A dead pilot whale lies on a sandbank after one of the country's largest recorded mass whale strandings, in Golden Bay, at the top of New Zealand's South Island. /Reuters Photo

4. Swimming in packs

Whales are highly social marine animals, and they normally swim in large pods or groups. If any individual whale becomes disoriented, others in the pod could also be misled away from the sea.

5. Altruistic gestures

Seeing that many of the stranded whales were all healthy and had no injuries, some scientists are inclined to attribute the stranding as a way for the whales to show their care for other distressed members of their group. However, the mechanism behind this is still unknown.

6. Natural instinct

Whales are sea mammals that evolved from their ancestors who previously lived on land. Thus some biologists believe that if the whales are distressed, their instinct guides them back to land to seek safety. They may find it easy to rest in shallow waters when they are sick, but further injuries can also lead to death, such as cuts and abrasions as well as internal pressure on their organs from unsupported body weight.

Volunteers look after a pod of stranded pilot whales as they prepare to release them after one of the country's largest recorded mass whale strandings, in Golden Bay, at the top of New Zealand's South Island, February 12, 2017. /Reuters Photo

Once stranded, these animals need to be pushed back into water as soon as possible. Otherwise, the unsupported body weight will start crushing their internal organs. This left rescuers racing against time to move the whales back into the sea.

Equipment such as heavy movers, slings or cranes can be used when it comes to rescue operations. And by keeping these mammals cool and wet as long as possible, rescuers can gain more time to save more of them.

Volunteers attend to some of the hundreds of stranded pilot whales still alive. /Reuters Photo

If worse comes to worst, the animals that are unable to swim away, are euthanized in an effort to end the slow pain in a humane manner as quickly as possible.