A
beached whale is a
whaleWhale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...
that has stranded itself on land, usually on a beach. Beached whales often die due to
dehydrationIn physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
, the body collapsing under its own weight, or drowning when high tide covers the
blowholeIn biology, a blowhole is the hole at the top of a cetacean's head through which the animal breathes air. It is homologous with the nostril of other mammals. As whales reach the water surface to breathe, they will forcefully expel air through the blowhole. Not only is air expelled, but mucus and...
.
Species
Every year up to 2,000 animals beach themselves. Although the majority of strandings result in death, they pose no threat to any species as a whole. Only about 10
cetaceaThe order Cetacea includes the marine mammals commonly known as whales, dolphins, and porpoises. Cetus is Latin and is used in biological names to mean "whale"; its original meaning, "large sea animal", was more general. It comes from Ancient Greek , meaning "whale" or "any huge fish or sea...
n species frequently display mass beachings, with 10 more rarely doing so. All frequently involved species are
toothed whaleThe toothed whales form a suborder of the cetaceans, including sperm whales, beaked whales, dolphins, and others. As the name suggests, the suborder is characterized by the presence of teeth rather than the baleen of other whales.-Anatomy:Toothed whales have a single blowhole on the top of the head...
s (Odontocetes), rather than
baleen whaleThe Baleen whales, also called whalebone whales or great whales, form the Mysticeti, one of two suborders of the Cetacea . Baleen whales are characterized by having baleen plates for filtering food from water, rather than having teeth. This distinguishes them from the other suborder of cetaceans,...
s. These species share some characteristics which may explain why they beach. Body size does not normally affect the frequency, but both the animals' normal habitat and social organization do appear to influence their chances of coming ashore in large numbers. Odontocetes that normally inhabit deep waters and live in large, tightly knit groups are the most susceptible. They include the
Sperm whaleThe sperm whale, Physeter macrocephalus, is a marine mammal species, order Cetacea, a toothed whale having the largest brain of any animal. The name comes from the milky-white waxy substance, spermaceti, found in the animal's head. The sperm whale is the only living member of genus Physeter...
, a few species of
PilotPilot whales are cetaceans belonging to the genus Globicephala. There are two extant species, the long-finned pilot whale and the short-finned pilot whale . The two are not readily distinguished at sea and analysis of the skulls is the best way to tell the difference between them...
and Killer whales, a few
beaked whaleBeaked whales are 21 species of toothed whales, members of the family Ziphiidae, are notable for their elongated beaks. Beaked whales are one of the world's most extreme divers. They can dive for long periods—20 to 30 minutes is common, and 85 minute dives have been recorded—and to...
s and some
oceanic dolphinOceanic dolphins are the members of the Delphinidae family of cetaceans. These marine mammals are related to whales and porpoises. They are found worldwide, mostly in the shallower seas of the continental shelves...
s. Solitary species naturally do not strand en masse. Cetaceans that spend most of their time in shallow, coastal waters almost never mass strand.
Causes
Strandings can be grouped into several types. The most obvious distinctions are between single and multiple strandings. The carcasses of deceased cetaceans are likely to float to the surface at some point; during this time,
currentAn ocean current is a continuous, directed movement of ocean water generated by the forces acting upon this mean flow, such as breaking waves, wind, Coriolis effect, cabbeling, temperature and salinity differences and tides caused by the gravitational pull of the Moon and the Sun...
s or
windWind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...
s may carry them to a coastline. Since thousands of cetaceans die every year, many become stranded posthumously. Most whale carcasses never reach the coast and are
scavengedScavenging is both a carnivorous and herbivorous feeding behavior in which individual scavengers search out dead animal and dead plant biomass on which to feed. The eating of carrion from the same species is referred to as cannibalism. Scavengers play an important role in the ecosystem by...
or decomposed enough to sink to the ocean bottom, where the carcass forms the basis of a unique local ecosystem called
whale fallWhale fall is the term used for a whale carcass that has fallen to the ocean floor. Whale falls were first observed in the 1980s, with the advent of deep-sea robotic exploration....
. Single live strandings are often the result of illness or injury, which almost inevitably end in death in the absence of human intervention.
Multiple strandings in one place are rare and often attract media coverage as well as rescue efforts. Even multiple offshore deaths are unlikely to lead to multiple strandings due to variable winds and currents.
A key factor in many of these cases appears to be the strong social cohesion of toothed whales. If one gets into trouble, its distress calls may prompt the rest of the pod to follow and beach themselves alongside. Many theories, some of them controversial, have been proposed to explain beaching, but the question remains unresolved.
Natural
Whales have beached throughout human history, so many strandings can be attributed to natural and environmental factors, such as rough weather, weakness due to old age or infection, difficulty giving birth, hunting too close to shore and navigation errors.
A single stranded animal can prompt an entire pod to respond to its distress signals and strand alongside it.
In 2004, scientists at the
University of TasmaniaThe University of Tasmania is a medium-sized public Australian university based in Tasmania, Australia. Officially founded on 1 January 1890, it was the fourth university to be established in nineteenth-century Australia...
linked whale strandings and weather, hypothesizing that when cool
AntarcticThe Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...
waters rich in
squidSquid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
and
fishFish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
flow north, whales follow their prey closer towards land. In some cases predators (such as killer whales) have been known to panic whales, herding them towards the shoreline.
Their
echolocationEcholocation, also called biosonar, is the biological sonar used by several kinds of animals.Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects...
system can have difficulty picking up very gently-sloping coastlines. This theory accounts for mass beaching hot spots such as
Ocean Beach, TasmaniaOcean Beach is a long stretch of beach running north of Macquarie Heads and Hells Gates on the West Coast of Tasmania. It is close to Strahan and parallel to the Strahan Airport runway...
and Geographe Bay, Western Australia where the slope is about half a degree (approximately 8 metres (26.2 ft) deep 1 kilometre (0.621372736649807 mi) out to sea). The
University of Western AustraliaThe University of Western Australia was established by an Act of the Western Australian Parliament in February 1911, and began teaching students for the first time in 1913. It is the oldest university in the state of Western Australia and the only university in the state to be a member of the...
BioacousticsBioacoustics is a cross-disciplinary science that combines biology and acoustics. Usually it refers to the investigation of sound production, dispersion through elastic media, and reception in animals, including humans. This involves neurophysiological and anatomical basis of sound production and...
group proposes that repeated reflections between the surface and ocean bottom in gently-sloping shallow water may attenuate sound so much that the echo is inaudible to the whales. Stirred up sand as well as long-lived microbubbles formed by rain may further exacerbate the effect.
Disruption in magnetic field
A theory advanced by Geologist
Jim BerklandJim Berkland is an American geologist studying earthquake prediction. He claims to have developed a method for predicting earthquakes, and offers his predictions through media appearances and publications. Before his retirement, Berkland was the County Geologist for Santa Clara County for...
, formerly with the U.S. Geological Survey, attributes the strandings to radical changes in the
Earth's magnetic fieldEarth's magnetic field is the magnetic field that extends from the Earth's inner core to where it meets the solar wind, a stream of energetic particles emanating from the Sun...
just prior to earthquakes and in the general area of earthquakes. Berkland says when this occurs, it interferes with sea mammals' and even migratory birds' ability to navigate, which explains the mass beachings. He claims dogs and cats can also sense the disruptions, which explains elevated rates of runaway pets 1–2 days before earthquakes. Research on
Earth's magnetic fieldEarth's magnetic field is the magnetic field that extends from the Earth's inner core to where it meets the solar wind, a stream of energetic particles emanating from the Sun...
and how it is affected by moving
tectonic platesTectonic Plates is a 1992 independent Canadian film directed by Peter Mettler. Mettler also wrote the screenplay based on the play by Robert Lepage. The film stars Marie Gignac, Céline Bonnier and Robert Lepage.-Plot summary:...
and earthquakes is ongoing.
"Follow-me" strandings
Some strandings may be caused by larger cetaceans following dolphins and porpoises into shallow coastal waters. The larger animals may habituate to following faster-moving dolphins. If they encounter an adverse combination of tidal flow and seabed topography, the larger species may become trapped.
Sometimes following a dolphin can help a whale escape danger. A recent example occurred when a local dolphin was followed out to open water by two
Pygmy sperm whaleThe Pygmy Sperm Whale is one of three species of toothed whale in the sperm whale family. They are not often sighted at sea, and most of what is known about them comes from the examination of stranded specimens.-Taxonomy:...
s that had become lost behind a sandbar at Mahia Beach, New Zealand. It may be possible to train dolphins to lead trapped whales out to sea.
An interesting observation is that pods of killer whales, predators of dolphins and porpoises, very rarely strand. Heading for shallow waters may protect the smaller animals from predators and that killer whales have learned to stay away. Alternatively, killer whales have learned how to operate in shallow waters, particularly in their pursuit of seals. The latter is certainly the case in Península Valdés, Argentina, and the
Crozet IslandsThe Crozet Islands are a sub-antarctic archipelago of small islands in the southern Indian Ocean. They form one of the five administrative districts of the French Southern and Antarctic Lands.-Geography:...
of the Indian Ocean, where killer whales pursue seals up shelving gravel beaches to the edge of the littoral zone. The pursuing whales are occasionally partially thrust out of the sea by a combination of their own impetus and retreating water and have to wait for the next wave to carry them back to sea.
SONAR
There is evidence that active sonar leads to beaching. On some occasions whales have stranded shortly after military sonar was active in the area, suggesting a link. Theories describing how sonar may cause whale deaths have also been advanced after necropsies found internal injuries in stranded whales. In contrast, whales stranded due to seemingly natural causes are usually healthy prior to beaching:
The large and rapid pressure changes made by loud sonar can cause hemorrhaging. Evidence emerged after 17
beaked whaleBeaked whales are 21 species of toothed whales, members of the family Ziphiidae, are notable for their elongated beaks. Beaked whales are one of the world's most extreme divers. They can dive for long periods—20 to 30 minutes is common, and 85 minute dives have been recorded—and to...
s hauled out in the Bahamas in March 2000 following a
United States NavyThe United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
sonar exercise. The Navy accepted blame agreeing that the dead whales experienced acoustically-induced hemorrhages around the ears. The resulting disorientation probably led to the stranding. Ken Balcomb, a whale zoologist, specializes in the Killer Whale populations that inhabit the
Strait of Juan de FucaThe Strait of Juan de Fuca is a large body of water about long that is the Salish Sea outlet to the Pacific Ocean...
between Washington and
Vancouver IslandVancouver Island is a large island in British Columbia, Canada. It is one of several North American locations named after George Vancouver, the British Royal Navy officer who explored the Pacific Northwest coast of North America between 1791 and 1794...
. He investigated these beachings and argues that the powerful sonar pulses
resonatedIn physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...
with airspaces in the whales, tearing tissue around the ears and brain. Apparently not all species are affected by SONAR.
Another means by which sonar could be hurting whales is a form of
decompression sicknessDecompression sickness describes a condition arising from dissolved gases coming out of solution into bubbles inside the body on depressurization...
. This was first raised by necrological examinations of 14
beaked whaleBeaked whales are 21 species of toothed whales, members of the family Ziphiidae, are notable for their elongated beaks. Beaked whales are one of the world's most extreme divers. They can dive for long periods—20 to 30 minutes is common, and 85 minute dives have been recorded—and to...
s stranded in the
Canary IslandsThe Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
. The stranding happened on 24 September 2002, close to the operating area of Neo Tapon (an international naval exercise) about four hours after the activation of mid-frequency sonar. The team of scientists found acute tissue damage from gas-bubble lesions, which are indicative of decompression sickness. The precise mechanism of how sonar causes bubble formation is not known. It could be due to whales panicking and surfacing too rapidly in an attempt to escape the sonar pulses. There is also a theoretical basis by which sonar vibrations can cause supersaturated gas to nucleate to form bubbles.
The overwhelming majority of the whales involved in SONAR-associated beachings are
Cuvier's Beaked WhaleCuvier's beaked whale is the most widely distributed of all the beaked whales. It is the only member of the genus Ziphius. Another common name for the species is goose-beaked whale because its head is said to be shaped like the beak of a goose. Georges Cuvier first described it in 1823 from part...
s (
Ziphius cavirostrus). This species strands frequently, but mass strandings are rare. They are so difficult to study in the wild that prior to the interest raised by the SONAR controversy, most of the information about them came from stranded animals. The first to publish research linking beachings with naval activity were Simmonds and Lopez-Jurado in 1991. They noted that over the past decade there had been a number of mass strandings of beaked whales in the Canary Islands, and each time the
Spanish NavyThe Spanish Navy is the maritime branch of the Spanish Armed Forces, one of the oldest active naval forces in the world. The Armada is responsible for notable achievements in world history such as the discovery of Americas, the first world circumnavigation, and the discovery of a maritime path...
was conducting exercises. Conversely, there were no mass strandings at other times. They did not propose a theory for the strandings.
In May 1996 there was another mass stranding in West
PeloponneseThe Peloponnese, Peloponnesos or Peloponnesus , is a large peninsula , located in a region of southern Greece, forming the part of the country south of the Gulf of Corinth...
,
GreeceGreece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....
. At the time it was noted as "atypical" both because mass strandings of beaked whales are rare, and also because the stranded whales were spread over such a long stretch of coast with each individual whale spacially separated from the next stranding. At the time of the incident there was no connection made with active SONAR, the marine biologist investigating the incident, Dr. Frantzis, made the connection to SONAR because of a Notice to Mariners he discovered about the test. His scientific correspondence in Nature titled "Does acoustic testing strand whales?" was published in March 1998.
Dr. Peter Tyack, of Woods Hole Oceanographic Institute, has been researching noise's effects on marine mammals since the 1970s. He has led much of the recent research on beaked whales (and Cuvier's beaked whales in particular). Data tags have shown that Cuvier's dive considerably deeper than previously thought, and are in fact the deepest diving species of marine mammal. Their surfacing behavior is highly unusual because they exert considerable physical effort to surface in a controlled ascent, rather than simply floating to the surface like sperm whales. Deep dives are followed by three or four shallow dives. Vocalization stops at shallow depths, because of fear of predators or because they don't need vocalization to stay together at depths where there is sufficient light to see each other. The elaborate dive patterns are assumed to be necessary to control the diffusion of gases in the bloodstream. No data show a beaked whale making an uncontrolled ascent or failing to do successive shallow dives.
The whales may interpret the unfamiliar sound of SONAR as a predator and change its behavior in a dangerous way. This last theory would make mitigation particularly difficult since the sound levels themselves are not physically damaging, but only cause fear. The damage mechanism would not be the sound.
Carcass
After a beached whale dies, it can become a source of
diseaseA disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
and
pollutionPollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
. Due to
blubberBlubber is a thick layer of vascularized adipose tissue found under the skin of all cetaceans, pinnipeds and sirenians.-Description:Lipid-rich, collagen fiber–laced blubber comprises the hypodermis and covers the whole body, except for parts of the appendages, strongly attached to the musculature...
's high
thermal insulationThermal insulation is the reduction of the effects of the various processes of heat transfer between objects in thermal contact or in range of radiative influence. Heat transfer is the transfer of thermal energy between objects of differing temperature...
capacity, a whale carcass' internal temperature can remain 30 °C (86 °F) for up to three days, making it an ideal environment for
anaerobic microorganismsAn anaerobic organism or anaerobe is any organism that does not require oxygen for growth. It could possibly react negatively and may even die if oxygen is present...
.
Such very large corpses are difficult to move. On at least one occasion, humans have
blown upThe term exploding whale most often refers to an event at Florence, Oregon, in 1970, when a dead sperm whale was blown up by the Oregon Highway Division in an attempt to dispose of its rotting carcass. The explosion threw whale flesh over away...
a whale carcass with explosives, with unsatisfactory side effects.
A beached whale
carcassWith regard to living things, a body is the physical body of an individual. "Body" often is used in connection with appearance, health issues and death...
should not be consumed. In 2002, fourteen
AlaskaAlaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
ns ate
muktukMuktuk is the English word for the traditional, pre-agrarian, Inuit/Eskimo and Chukchi meal of frozen whale skin and blubber...
(whale blubber) from a beached whale, and eight of them developed
botulismBotulism also known as botulinus intoxication is a rare but serious paralytic illness caused by botulinum toxin which is metabolic waste produced under anaerobic conditions by the bacterium Clostridium botulinum, and affecting a wide range of mammals, birds and fish...
, two requiring
mechanical ventilationIn medicine, mechanical ventilation is a method to mechanically assist or replace spontaneous breathing. This may involve a machine called a ventilator or the breathing may be assisted by a physician, respiratory therapist or other suitable person compressing a bag or set of bellows...
. This is a possibility for any meat taken from an unpreserved carcass.
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