Beached whale
851060
223383255
2008-07-03T21:02:05Z
86.130.44.150
/* External links */
[[Image:Blackfish.jpg|thumb|right|260px|A mass stranding of [[Pilot Whales]] on the shore of Cape Cod, 1902.]]
A '''beached whale''' is a [[whale]] which has become stranded on land, usually on a beach. Beaching is often fatal for whales, as they become [[dehydration|dehydrated]] and die. Some die when their lungs are suffocated under their own weight or drown when high tides cover their [[blowhole (biology)|blowholes]]. Humans sometimes try to save beached whales; however, such efforts are not always successful.
==Species==
Every year there may be beachings adding up to 2000 animals.<ref name="Martin">{{cite book| last=Martin| first=Anthony R. | title=Whales and Dolphins| date=1991| publisher=Salamander Books Ltd. |location=London}}</ref> Although the majority of strandings will result in death, they pose no threat to the species as a whole. Of all of the species of cetaceans, only about 10 species are frequently involved in mass beachings, with a further 10 species rarely being involved. All of the frequently involved species are [[toothed whale]]s, meaning that none of the [[baleen whale]]s are regularly involved in beachings. 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 whale]], a few species of [[Pilot Whale|Pilot]] and [[Orca]] whales, a few [[beaked whale]]s and some [[oceanic dolphin]]s. Solitary species are naturally excluded from mass strandings. Cetaceans that spend most of their time in shallow, coastal waters are almost never mass stranded, with [[porpoise]]s being essentially immune.
==Causes==
===Overview===
[[Image:Three Beached Whales, 1577.jpg|thumb|right|''Three Beached Whales'', a 1577 engraving by Dutch artist Jan Wierix, depicts stranded Sperm Whales.]]
Strandings can be grouped into several different 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, [[Ocean current|current]]s or [[wind]]s may carry them towards a [[coastline]]. Since thousands of cetaceans must die every year it is natural that many will become stranded. Most cetacean deaths which occur naturally will only involve a single individual, causing these strandings to consist of just one animal, if a stranding occurs at all; however, most carcasses never reach the coast and are [[Scavenger|scavenged]] or [[decomposed]] enough to sink to the bottom of the oceans. Single live strandings are often the result of an illness or injury, which would almost inevitably end in death unless a passer-by knows how to react.
Multiple strandings of dead animals in one locality are rare and often cause a great deal of media coverage as well as rescue efforts by sympathetic humans. Even multiple offshore deaths are unlikely to lead to multiple strandings due to the variable winds and currents scattering the animals across the sea. A key factor in many of these cases appears to be the strong social cohesion amongst toothed whales. If one whale gets into trouble, its distress calls may prompt the rest of the pod to follow and become beached themselves.<ref name="abc-mystery">{{cite web|author=Anton Van Helden
|title=Mass whale beaching mystery solved|work=The Word Today
|publisher=Australian Broadcast Corporation|format=Radio transcript
|date=2003-11-26|accessdate=2006-12-01
|url=http://www.abc.net.au/worldtoday/content/2003/s997632.htm}}</ref> There is no definitive specific cause for mass strandings. Instead they may happen due to numerous factors that can act in combination. Many have been proposed, with some seeking to explain only a subset of cases; however, they are difficult to prove conclusively and are sometimes controversial.
===Natural===
[[Image:Stranded whale Katwijk 1598.jpg|thumb|right|Stranded whale at [[Katwijk]] in [[Holland]] in 1598.]]
Whales have been found beached throughout human history so many strandings can be attributed to natural and environmental factors. There could be many natural reasons like rough weather, weakness due to old age or infection, difficulty giving birth,<ref name="abc-mystery" /> hunting too close to shore and navigational mistakes. A single stranded animal can prompt the entire pod to respond to its distress signals and become stranded. In 2004, scientists at the [[University of Tasmania]] found a link between whale strandings and the weather. It is hypothesised that when cool [[Antarctic]] waters rich in squid and fish flow north, whales follow their prey closer towards land making them more prone to stranding.<ref name="abc-climate">
{{cite web|author=R. Gales, K. Evans, M. Hindell|url=http://www.abc.net.au/7.30/content/2004/s1255082.htm
|publisher=Australian Broadcasting Corporation|format=TV transcript
|title=Whale strandings no surprise to climatologists
|work=7:30 report|date=2004-11-30|accessdate=2006-12-02}}</ref> In some cases predators (such as killer whales) have been known to panic whales, herding them towards the shoreline.<ref name="abc-climate" />
Another proposed cause is that the [[echolocation]] system used by many whales can have difficulty picking up very gently-sloping coastlines.<ref name="fatal shore">
{{cite web|author=B. Montgomery|title=The fatal shore
|url=http://www.biophysics.uwa.edu.au/Bioacoustics/waustralian.html
|work=The Weekend Australian Magazine
|date=1998-05-02
|accessdate=2006-12-03}}</ref> This theory accounts for mass beaching hot spots such as [[Ocean Beach, Tasmania]] and [[Geographe Bay, Western Australia]] where the slope is about half a degree (approximately 8m deep one kilometer out to sea). The [[Bioacoustics]] group at the [[University of Western Australia]] has done research<ref name="uwa-acoustics">
{{cite conference|author=Chambers S., James R. N.
|title=Sonar termination as a cause of mass cetacean strandings in Geographe Bay, south-western Australia|booktitle=Acoustics 2005, Acoustics in a Changing Environment. Proceedings of the Annual Conference of the Australian Acoustical Society, Busselton, Western Australia
|url=http://www.biophysics.uwa.edu.au/Bioacoustics/articles/ChambersJames2005.pdf
|date=9 November 2005}}</ref> indicating 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 [[microbubble]]s formed by rain may further exacerbate the effect.
A controversial theory, researched by [[Jim Berkland]], a former [[geologist]] with the [[U.S. Geological Survey]], attributes the strange behaviour to radical changes in the [[Earth's magnetic field]] 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.<!-- Not active anymore <ref>http://www.flyinglobe.com/1_flyinglobe/feeds/atom.xml+geological+survey+beached+whale+magnetic+field+berkland+-wikipedia&hl=en&gl=us&ct=clnk&cd=2 </ref> --> He says even dogs and cats can sense the disruptions, which explains elevated rates of runaway pets in local newspapers a day or two before earthquakes occur. Research on [[Earth's magnetic field]] and how it is affected by moving [[tectonic plates]] and earthquakes is ongoing.
=== "Follow-me" strandings ===
Another possibility is that a proportion of strandings may be caused by larger cetaceans following [[dolphins]] and [[porpoises]] into shallow coastal waters{{Fact|date=March 2008}}. The larger animals may be familiar with faster moving dolphins in their area and become habituated to following them. If an adverse combination of tidal flow and seabed topography is encountered, the larger species are at much higher risk of being trapped.
Sometimes it may work the other way. A recent example of this was in where a local dolphin was followed out to open water by 2 [[Pygmy sperm whale]]s that had become lost behind a sandbar at [[Mahia Beach]], New Zealand.<ref>{{cite news|title=Dolphin rescues stranded whales|work=CNN|publisher=The Associated Press|date=2008-03-12|accessdate=2008-03-15|url=http://edition.cnn.com/2008/WORLD/asiapcf/03/12/nz.whales.ap/index.html}}</ref>
The possibility of training dolphins to lead trapped whales out to sea is an intriguing one in areas where frequent mass strandings occur, such as New England or Florida.
An interesting observation is that pods of [[killer whale]]s, predators of dolphins and porpoises, are very rarely stranded. There may be two explanations for this - firstly that heading for shallow waters may be a very effective anti-predator mechanism for dolphins and that the killer whales have learned not to take the risk, or else that the 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, where a particular pod of killer whales pursue seals up shelving gravel beaches to the edge of the littoral zone{{Fact|date=March 2008}}. 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 take them back out.
===Man-made===
{{seealso|Noise pollution#Environment}}
[[Image:Whales on beach, Farewell Split, South Island, New Zealand.JPG|thumb|right|Volunteers attempt to keep body temperatures of beached whales from rising. [[Farewell Spit]], [[New Zealand]].]]
There is evidence that very loud noise from [[anti-submarine warfare]] [[sonar]] may hurt whales and lead to their beaching. On numerous occasions whales have been stranded shortly after military sonar was active in the area, suggesting a link. Reasons as to how sonar may cause whale deaths have also been put forward by scientists after [[necropsies]] found internal injuries in stranded whales. In contrast, whales stranded due to seemingly natural causes are usually healthy prior to beaching.
Firstly, it has been argued that the very loud rapid pressure changes made by sonar can cause [[haemorrhaging]]. Evidence emerged after the beachings of seventeen whales and a dolphin in the [[Bahamas]] in March 2000 following a [[United States Navy]] sonar exercise. The Navy accepted blame in [http://www.awionline.org/oceans/Noise/Interim_Bahamas_Report.pdf this Joint Interim Report] which found the dead whales to have experienced acoustically-induced haemorrhages around the ears. The resulting disorientation probably led to the stranding. [[Ken Balcomb]], a [[zoologist]], specializing in the study of whales, particularly the [[Orca]] populations that inhabit the [[Strait of Juan de Fuca]] between [[State of Washington|Washington]] and [[Vancouver Island]], has studied mass beachings of whales.<ref>{{cite web
| url=http://www.sanjuanislander.com/groups/center_for_whale_research/sonar.shtml
| title=US Navy Sonar blasts Pacific Northwest killer whales
| last=Balcomb
| first=Ken
| date=[[2003-05-12]]
| year=2003
| publisher=San Juan Islander
| accessdate=2006-04-30
}}</ref> He investigated the March 2000 beachings and argues that the powerful sonar pulses had used vibrations that [[resonance|resonated]] with airspaces in the whales, causing tearing of tissue around the ears and brain.<ref>{{cite web
| url=http://www.oceanmammalinst.org/kenbalcombletter.htm
| last=Balcomb
| first=Ken
| title=Letter
| date=[[2001-02-23]]
| year=2001
| publisher=Ocean Mammal Institute
| accessdate=2006-04-30
}}</ref>.
Another means by which sonar could be hurting whales is a form of [[decompression sickness]]. This was first raised by pathological examinations after 14 [[beaked whale]]s stranded in the [[Canary Islands]]. The stranding happened on 24 September 2002, close to the operating area of Neo Tapon (an international naval exercise) about 4 hours after the activation of mid-frequency sonar.<ref name="jepson-2003">{{cite journal|author=P. D. Jepson et al.|title=Gas-bubble lesions in stranded cetaceans|journal=Nature|date=9 October 2003|issue=425|pages=575|url=|volume=425|doi=10.1038/425575a}}</ref> The team of scientists found acute tissue damage from gas-bubble lesions, which are indicative of decompressions sickness.<ref name="jepson-2003" /> The precise mechanism of how sonar causes bubble formation is not fully 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.<ref>{{cite journal|author=D. S. Houser, R. Howards, S. Ridgway|title=Can Diving-induced Tissue Nitrogen Supersaturation Increase the Chance of Acoustically Driven Bubble Growth in Marine Mammals?|journal=Journal of Theoretical Biology|date=21 November 2001|issue=2|volume=213|pages=183–195|doi=10.1006/jtbi.2001.2415}}</ref>
Strandings may be caused by poisoning, as happened in 1987-88 to [[Bottlenose Dolphin]]s off the north-eastern coast of the [[United States]].
==Carcass==
After a beached whale dies, it can become a source of [[disease]] and [[pollution]]. Due to the very high efficiency as thermal [[insulator]] of the [[blubber]], a whale carcass can keep its internal temperature over 30 celsius for up to 3 days, making it the ideal environment for [[Anaerobic organism|anaerobic microorganisms]].
As they are very large, such [[Dead body|corpse]]s are difficult to move. There are reports of some cases where humans tried to [[exploding whale|blow up]] the carcass with [[explosive]]s, with unexpected side effects to spectators.
A whale [[carcass]] should not be consumed. In [[2002]], fourteen [[Alaska]]ns ate ''[[muktuk]]'' (whale blubber) from a beached whale, and eight of them developed symptoms of [[botulism]], two of them requiring [[mechanical ventilation]].<ref>{{cite journal
|url=http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5202a2.htm
|title=Outbreak of Botulism Type E Associated with Eating a Beached Whale --- Western Alaska, July 2002
|last=Middaugh
|first=J
|coauthors=Funk, B, Jilly, B, Maslanka, S, McLaughlin J
|journal=Morbidity and Mortality Weekly Report
|date=2003-01-17
|volume=52
|issue=2
|pages=24–26}}</ref> This is a possibility for any spoiled [[meat]], or meat taken from an animal which has been dead for some time without proper preservation of the carcass.
==See also==
*[[Whales]]
*[[Exploding whale]]
==References==<!-- http://www.nrdc.org/wildlife/marine/sound/sound.pdf -->
{{reflist}}
==External links==
*[http://www.nrdc.org/wildlife/marine/sonar.asp Protecting Whales from Dangerous Sonar] (Natural Resources Defense Council)
*[http://english.epochtimes.com/news/5-10-28/33859.html Does Sonar Harm Whales?] (Tasmanian whale stranding October 2005: Epoch Times)
*[http://www.janes.com/defence/naval_forces/news/jni/jni060825_1_n.shtml Sensors and sensibility: navies factor mammals into sonar use] Jane's Navy International, 25 August 2006
*[http://skegnessvideo.com/2007/12/whale-strandings-skegness-beach/ Whale Strandings Skegness East Coast UK, February 2006
[[Category:Cetaceans]]
[[es:Ballena varada]]
[[fr:Échouage des cétacés]]
[[he:החפת לווייתנים]]
[[zh-yue:鯨魚擱淺]]