Probing question: Why do whales beach themselves?

Apr 25, 2008

Whales are the largest marine mammals in the world — the smallest species weigh in at several tons. When whales beach themselves, they can die simply from the crushing weight of their own bodies or from overheating due to their blubber, which is needed for insulation in cold ocean waters. What causes these often fatal incidents?

Strandings are of several types, said Susan Parks, a research associate in the Environmental Acoustics program in the Applied Research Laboratory at Penn State. Individual strandings often are caused by isolated incidents such as sickness, injury or old age. Said Parks, "Entanglement in fishing gear is one of the leading causes of mortality for marine mammals, many of which wash up on shore dead or injured." The tide carries these whales into shallow water, depositing them on the beach.

Then there are multiple-species strandings, explained Parks. "This occurs when different species of marine mammals beach themselves at the same time and place, suggesting that they all died from the same cause," she said.

Scientists have been researching possible causes of this phenomenon. One explanation involves the whale "pod" social structure. For instance, whales that travel in pods use a "strength in numbers" survival strategy, but this can backfire when the dominant whale runs aground. According to Parks, "The rest of the pod may follow a disoriented or sick whale onto shore." Another theory is that pods may venture too close to the beach when hunting prey or evading predators and become trapped by low tides.

Weather also may play a part in beachings. Explained Parks, "In 1998, there was a major stranding on the West Coast of the United States where many different species, particularly sea lions, starved to death." This mass stranding, she added, was thought to be caused by El Nino's effects on sea-water surface temperatures. Many marine mammals depend on plankton and kelp that thrive in cool, nutrient-rich waters. In the case of sea lions, when food is scarce, the adults wean pups earlier and leave them behind while they hunt for fish in colder waters further offshore. These young seals are often the ones that become stranded.

Some theories about beaching suggest that defects in a whale's navigation system may be the cause. According to Parks, "The problem with these theories is that we don't know exactly how whales navigate.” Some species travel vast distances every year and find their way back to where they started. Right whales, for example, travel more than a thousand miles from the Gulf of Maine to the coastal waters of Florida and Georgia to give birth, then swim back to northern waters. Said Parks, it is known that some whales use echolocation to identify objects in their environment but "it is unclear whether these species need to rely on it for navigation."

Some researchers have proposed that whales navigate by using passive listening to hear waves crashing against the coast or steer themselves via undersea topography or the angle of the sun. But, interjected Parks, "the distance that animals can see is often very limited in the ocean, and isn't thought to be a useful for long-distance navigation."

Another navigation theory proposed recently is that whales have a bio-magnetic sense, which allows them to sense magnetic fields in the earth's crust. "This would be similar to how homing pigeons orient themselves," explained Parks. Whales following magnetic field lines could beach themselves in areas where the field lines intersect with the coast. "A study in the UK by Margaret Klinowska found a correlation between local magnetic field lines and sites where whales were stranded alive," added Parks. However, more research is needed to solidify the connection.

Several multiple-species strandings have occurred following military use of mid-frequency sonar, sparking public outcry. "One reason for the level of concern about these incidents is that they involved the rarely seen beaked whales," explained Parks. "These whales were found beached five, sometimes 10 at a time. The problem with the sonar theory," she added, "is that we still don't fully understand the cause and effect mechanism of how sonar might affect whales or why it might affect beaked whales in particular."

Research into the cause of strandings is ongoing, noted Parks. Meanwhile, many coastal areas have rescue groups to find and rehabilitate these stranded mammals and to release them back into the wild. When the rehab patient weighs in at more than 40 tons, that can be a whale of a job.

Source: By Marissa McCauley, Research Penn State

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sheber
5 / 5 (3) Apr 25, 2008
To Mercury 01- I love your comment!
waterman
5 / 5 (2) Apr 26, 2008
You said it much better than I could Mercury_01. Totally agree.
techsquirrel
5 / 5 (2) Apr 26, 2008
As Mercury 01 said rather elequently, this is a pretty simple concept to grasp. The marine mammals are literally inundated with intolerable levels of sound from the military sonar. Under fight or flight, they react and flee, however, they are unable to sense the world around them normally because the primary sense they use, the auditory sense, is inundated. So they are "blinded" and fleeing blind. At that point, it is simply a matter of time before they are exhausted and sink and die, or beach themselves in their frantic attempts to get away from the sonar.

The underwater sound pressure levels generated by military sonar are 60-100 decibels above the detection threshold of marine mammals. This sounds tolerable to us; after all, we experience levels from 60-100 dB above our 0 dB threshold and generally don't panic. However, this is a misleading concept to map to our human acoustic experience. First, we are primarly vision-based, not auditory-based. Second, for hearing in air, se have sophisticated impedance-matching units called "ears" that bring the sound from the relatively inefficient propogation medium called 'air' into our water-based inner ears. (Try plugging your ears hard and tight, and see how well you hear.) Our water-density bodies experience about 40dB less energy coming at us in the air- in effect it bounces off our skin. So, we don't experience the kind of saturated sound in our bodies the way marine mammals do. Exception: divers- the Navy itself has exposure limits for divers, based on actual research with divers, that are far below what they advocate as tolerable for maine mammals- a functional oxymoron. And, divers who have been underwater near military sonar will tell you how disturbing it is.

In water, sound penetrates right into and through marine mammals bodies at around 4900 feet/second; the mammal body density is essentially identical to sea water- there is effectively no resistance or energy loss. Sonar signals enter right into mammal bodies, ensonifying and vibrating tiny air pockets and resonant cavities in internal organs, and saturating the inner ears. It has been my assertion for many years, as it has been for many others who have studied the problem, that effectively blinded by sonar, the marine mammal panics and is simply trying to leave the area. The Navy has spent a lot of money with focus on the potential for "tissue damage" by sonar, without acknowledging the very simple, basic-survival mechanism in all mammals of fight-or-flight that occurs at levels far below those that could create tissue damage. Would a person hang around if exposed to sound levels sufficient to blow out their ears? No. They would leave. Marine mammals flee the area, and we see occasionally the evidence, the beached whales. Even the Navy can never know how many marine mammals sink from exhaustion and die out of sight of the Navy sighting teams ordered to observe during sonar trials.

It takes a real degree of humanity to accept that marine mammals are dying not from some mysterious condition that needs more research but simply because they are being blinded, panic, and run to exhaustion. However, the Navy's primary mission is total domination of the seas; not the welfare of marine mammals. No matter what the Navy says in press releases and spends on "research", the fact is, the Navy conducts warfare and nationsl defense, not stewardship of the oceans. They do not want to limit their operations at all, certainly not for whales, as evidenced by their persistent legal battles to fight off any restrictions on unfettered full power military sonar operations, even in and around marine sanctuaries. The US Navy (and other navies around the world) are in the killing business- of course, in the name of national defense. Perhaps it is time for more Americans to speak out about how far things should go. If we clear the oceans and leave them sterile of life so military vessels are detectable, what have we gained? It would be clear in time, what we will have lost.
Egnite
5 / 5 (1) Apr 28, 2008
"These whales were found beached five, sometimes 10 at a time. The problem with the sonar theory," she added, "is that we still don't fully understand the cause and effect mechanism of how sonar might affect whales or why it might affect beaked whales in particular."

WTF needs fully understood? The problem is there and the cause is fairly obvious if 5-10 are beached at a time! All they need to do is implement a solution. Ofc that will be costly for the millitary and I bet expense is of higher importance to them than the whale safety. Typical.
googleplex
4 / 5 (1) May 01, 2008
I can guarantee it is sonar. A navy contractor operates in the Monterey bay area, which is the largest marine sanctuary. They were testing some new experimental military sonar equipment which caused 2 apparently healthy blue whales to beach. They immediately stopped operations. This is "de facto" proof that Navy sonar causes beachings.
To echo earlier posts, the Navy is in the killing industry so they are not the best advocates for animal rights. Change will need to come from outside the Navy.
[Where is the original posting by Mercury-01]
EarthScientist
not rated yet May 06, 2008
While sonar can effect anything in the water,the fact that 50 ships full of mercury were dropped to the bottom of the ocean during WW2 and the recent finding of the Norway sub is just the tip of the iceberb.

The Iceland study of genetic difficulties and intellect problems with their population and further assay as the mercurized whale meat they were ingesting and the amelioration of the problem with sequestering whale meat from pregnant moms and children that has turned the problem completely backwards speaks volumes.

The whales beach themselves from sickness and confusion from the tons of mercury infested crill they eat from the warm waters every day when they are in those waters.

When you find out the locations of the 30 ships of mercury that have already been worked on by the brits quietly,you will get a clue ,maybe.

The removal of postings doe not just effect the humanity on this planet sphere,it speaks volumes as to who some moderation taskers work for, they are treasonous to the United States of America.

Plain and simple talk from this old grid scientist who knows even more than I speak out as to the mercury ship process.
TerrifiedCitizen
not rated yet May 31, 2009
It's odd that this report from people who basically represent American academia is so heavy on such vague theory. The existence of whales is ancient and has provided man ample opportunity to understand much more than is explained here.
If it wasn't for the comments from readers, I would walk away from this report with more questions than answers.
I would like to thank all the readers for great suggestions and information for further research, and would particularly like to know the same thing that Googleplex asks; [Where is the original posting by Mercury-01] ???
tunasashimi
not rated yet May 31, 2009
http://www.answer...ew/17393

Thus, the real ANSWER for why whales and dolphins mass strand themselves is barotrauma resulting from exposure to a series of dangerous pressure changes (seaquakes) generated when thrusting earthquake erupts in the seabed below the feeding pod.


- CAPT David Williams
Deafwhale Society, Inc
www.deafwhale.com


These guys seems to have put a lot of research into this, and their findings sounds plausable. Shame, poor whales.

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