Science Questions

Why do whales beach themselves?

Sun, 29th Nov 2009

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Etienne De Villiers asked:

Why do whales beach themselves?


Helen -   That’s a great question, but unfortunately part of the answer is, we actually don’t know.  In only around half of the whales stranded around the world is a cause found. And there are usually all sorts of things we know can cause whales to beach themselves, often fatally. 

These include things like diseases, trauma if they’ve been hit by a boat or something like that, or an anomaly in magnetic fields.  We know a little about how whales use magnetic fields to navigate. If there’s an anomaly that doesn’t seem to make sense to them, or perhaps a change to a coastline, they might get confused, and that may lead them into an area that can’t escape from and eventually end up on a beach.

Also, things like underwater noise has been implicated including military sonar though there’s very little evidence that is what’s going on.  We need a lot more studies to really understand if that is a problem because whales can be very sensitive to underwater noise.  We know that they can hear each other so if humans are being very noisy, that can certainly is likely to confuse them and end up having these big problems.

You also have to remember that these mass strandings, when lots and lots of whales and dolphins end up on a beach, has been going on for an awfully long time. Since Aristotle's time people have been seeing these mass strandings, so clearly a long time before we were making really big impact on the oceans. 

This means that there must be a natural element to it as well.  There are reports of increased mass strandings at the moment, but there are also more people looking for them and more of us at the coast.  So that might be one reason, and we should really be taking all these things into account when we’re considering what’s causing it, and whether we should be trying to do something to stop it.


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This is a real puzzle.

It may be due to distortions in the Earths magnetic field, although it is questionable whether whales use this field for navigation.

It may be due to shipping. In 2002, 14 beaked whales came ashore in the Canary Islands. Navy ships in the area were using active sonar.

Some may come ashore due to illness making them too weak to swim. Or it could be that they come into shallow water for support during this time to avoid drowning and get washed further inshore than they intended by waves or left in too shallow water by receding tides.

Only a couple of days ago 55 False Killer Whales beached near Cape Town. Volunteers helped them back into the water, but they turned back and beached themselves again.

It has also been suggested that it could be due to pollution, but this strange phenomenon is known to have been going on for hundreds of years, so man cannot be blamed for this.

The fact is, we just don't know the answer to this question. Read this interview with DARLENE KETTEN Don_1, Fri, 5th Jun 2009

I have studied seismic activity and Earthquakes around the world for over 26 years. I have found to prove that with most whales or Dolphins beaching is caused by underwater sounds from seismic activity is very excruciating on these animals and they beach to get out of the water. Even trying to put them back into the ocean they will simply turn around and beach again. I have noticed in my finding that a few days after the beaching earthquakes above 6.0 usually occur in the surrounding regions. An example late last month whales beaches in New Zealand near Wellington, a few days after Christchurch was hit be a 7.1 earthquake. I have much more evidence and information available on this. Sonar from naval submarines etc also upsets them. Its like a dog whistles, we can not hear it, but it drives dogs crazy. Regards Gary Matthews Adelaide Australia Gary Matthews, Mon, 13th Sep 2010

Diving pods of offshore toothed whales and dolphins (odontoceti) feed on squid above mid-oceanic ridges where they are often exposed to oscillations in ambient water pressure when shallow-focused earthquakes suddenly erupt in the seafloor below them. On rare occasion these changes in pressure are too excessive and/or too rapid to be counterbalanced by the whales' pressure regulating anatomy resulting in barotrauma in the sinuses and air sacs of each animal's head. Since echo-navigation and echo-location are not possible without intact and functional sinuses and air sacs, a pressure related injury in this system renders the victims unable to use their acoustic navigation system to determine their position and find food. Nor are they able to dive without suffering intense pain. The injured pod huddles together for protection against sharks and swims slowly away from the epicenter, but not in a random direction. Rather, increased resistance (drag) to swimming against or perpendicular to the surface flow will turn the whales headfirst and point them in the path of the least drag, which is always downstream with the flow of the surface currents. Many barotraumatized pods recover after an unknown period of rest on the surface. Those that do not recover are eventually: (a) guided to a stranding beach by the surface current, (b) harvested by sharks and killer whales, or (c) die and sink to the bottom. Decomposing gases will form in the carcasses that sink in water less than 100 meters deep. After about a week underwater, the gases formed will re-float these carcasses and they will be carried by the surface currents to a beach. Non-navigating whales, carcasses, and flotsam are deposited on beaches because the current that carried each grain of sand to build the beach in the first place, is the same energy determining the path of everything floating on the surface. Where currents wash shoreward, there are beaches, flotsam, and beached whales; where current does not wash toward the shore, there are no beaches, no flotsam, and no beached whales. D. Williams, Sun, 7th Aug 2011

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