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What causes whale and dolphin strandings?

Whales, dolphins and porpoises are beautiful, mysterious and intelligent animals that populate seas and oceans all around the planet. And sometimes, they get stranded on the shore. This can be tragic, since many die in such strandings, but with the right action if you find a stranded cetacean and act quickly, you might be able to help save it!

The Whale Beached between Scheveningen and Katwijk, with Elegant Sightseers by Esaias van de Velde
The Whale Beached between Scheveningen and Katwijk, with Elegant Sightseers by Esaias van de Velde

What is a cetacean stranding?

Sometimes called ‘beachings’, a stranding is where a cetacean – a whale, dolphin or porpoise – becomes stuck on the shoreline, in water too shallow to swim away in. This is dangerous because the cetaceans can die due to dehydration, can drown if their blow holes are covered by water or something else when the tide comes in if they are unable to move, or can be crushed by their own heavy weight, which is usually supported by the water.

Sometimes, tragically, mass strandings occur. This is where several cetaceans become stranded at one. Sometimes it can be tens, or even (thankfully rarely) hundreds of individuals.

Beached false killer whales at Flinders Bay, Western Australia, 1986 - CC BY-SA 3.0 by Bahnfrend
Beached false killer whales at Flinders Bay, Western Australia, 1986 – CC BY-SA 3.0 by Bahnfrend

What causes cetacean strandings?

So many different species of stranding occur, in so many locations, that the mystery of why it happens hasn’t been solved. It’s been happening for thousands of years, and it’s likely that there are different reasons – some natural, and some that humans have had a hand in.

Some of the natural reasons could include the animal already being ill or poorly, making a navigation mistake, or rough weather and storms. It could also be due to follow prey such as squid into too shallow water, or being ‘herded’ by predators in shore.

Other theories include that some very gently shallowing marine slopes could confuse the cetaceans, so they don’t notice it’s shallowing too much, or that disruption to Earth’s geomagnetic force field, caused by solar storms, might affect their internal navigation systems.

In some cases, low-frequency sonar used by naval and military organisations to locate submarines might injure, disorientate or even kill whales. The mysterious Cuvier’s Beaked Whale, which dives deeper than any other animal, may be particularly susceptible. The sound of sonar might cause them to rise to shallow water too quickly, causing injury.

It’s also possible that global warming plays a part, with warming seas and changes to prey behaviour causing the cetaceans to change their usual patterns in turn, putting them in more vulnerable areas.

Human activity can also cause direct injury; whales and dolphins can be injured if they collide with a boat or ship, which can in turn mean they are more likely to strand.

Volunteers attempt to keep body temperatures of beached pilot whales from rising at Farewell Spit, New Zealand. Public Domain. By Chagai
Volunteers attempt to keep body temperatures of beached pilot whales from rising at Farewell Spit, New Zealand. Public Domain. By Chagai

What should you do if you find a stranded whale or dolphin?

If you find a whale or dolphin that has become stranded, you should call the Cetacean Stranding Hotline immediate, on 0800 652 0333, and provide as much information as you can about the location and the animal or animals affected.

A team of local cetacean experts will be quickly dispatched to try and help the animal if they can.

Dos and Do Nots

  • Do not try to get the animal back into the sea
  • Do not cover the animals’ blow hole – this is what it breathes through
  • Do not go near the tail or blow hole
  • Do stay quiet and calm around the animal, so as not to distress it further
  • Do cover the animal with wet sheets, towels or seaweed, and shade (but be careful to avoid the blow hole)
  • Do look for signs of injury to share with the Cetacean Stranding Hotline

The Discover Wildlife website has a really helpful guide on what to do and what not to do.

Read more:

The Conversation – What causes whale and dolphin strandings? 

Why do whales and dolphins strand?

Tasmania’s whale stranding: what caused it and can it be stopped in the future?

 

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