Great white shark: Difference between revisions - Wikipedia

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{{Taxobox

| name = Great white shark

| status = VU

| trend = unknown

| status_system = iucn2.3

| image = Whiteshark-TGoss1.jpg

| image_width = 250px

| domain= [[Eukarya]]

| regnum = [[Animal]]ia

| phylum = [[Chordate|Chordata]]

| classis = [[Chondrichthyes]]

| subclassis = [[Elasmobranchii]]

| ordo = [[Lamniformes]]

| familia = [[Lamnidae]]

| genus = '''''Carcharodon'''''

| genus_authority = [[Andrew Smith (zoologist)|Smith]], 1838

| species = '''''C. carcharias'''''

| binomial = ''Carcharodon carcharias''

| binomial_authority = ([[Carolus Linnaeus|Linnaeus]], 1758)

| range_map = Carcharodon carcharias distmap.png

| range_map_width = 250px

| range_map_caption = Range (in blue)

}}

The '''great white shark''', ''Carcharodon carcharias'', also known as '''white pointer''', '''white shark''', or '''white death''', is an exceptionally large [[lamniformes|lamniform]] [[shark]] found in coastal surface waters in all major [[ocean]]s. Reaching lengths of about 6 [[metre]]s (20 [[foot (unit of length|ft]]) and weighing up to 2,250 [[kilogram]]s (5,000 [[pound (mass)|lb]]), the great white shark is the world's largest known predatory [[fish]]. It is the only surviving [[species]] of its [[genus]], ''Carcharodon''.

==Taxonomy==

[[Carolus Linnaeus]] gave the great white shark its first scientific name, ''Squalus carcharias'' in 1758. [[Andrew Smith (zoologist)|Sir Andrew Smith]] gave it the generic name ''Carcharodon'' in 1833, and in 1873 the generic name was identified with Linnaeus specific name and the current scientific name ''Carcharodon carcharias'' was finalised. Carcharodon comes from the [[Greek language|Greek]] words ''karcharos'', which means sharp or jagged, and ''odous'', which means tooth.<ref name="abc">

{{cite web|url=http://sacoast.uwc.ac.za/education/resources/envirofacts/greatwhite.htm|

publisher="The Enviro Facts Project"|

title="The Great White Shark"|

accessdate=2007-07-09}}</ref>

===Related species===

The great white is classified as a mackerel ([[Lamnidae]]) shark. There are four other living species in this [[family (biology)|family]], two [[mako shark|mako]] and two ''[[Lamna]]'' sharks.

[[Image:Megalodon tooth great white shark teeth .jpg|thumb|left|[[Megalodon]] tooth with two great white shark teeth and a [[Quarter (United States coin)|U.S. quarter]] for size comparison]]

Dental features and the extreme size of both the great white and the prehistoric [[Megalodon]] lead many scientists to believe they were closely related, and the name ''Carcharodon megalodon'' was applied to the latter. At present there is considerable doubt about this hypothesis, and other scientists would place the megalodon and white shark as distant relatives - sharing the family Lamnidae but no closer relationship.

Megalodon is only known from its teeth and from a few cartilage remains, and probably reached sizes of {{m to ft|15|abbr=yes}} or more, considerably larger than even the largest great white sharks. From time to time it is suggested that megalodon might still exist. Megalodon teeth have supposedly been found from as recently as 10,000 to 12,000 years ago, but these results appear to be based on misinterpretation of the evidence.<ref>See [[Megalodon]] article for details</ref> However, while megalodon [[fossil]]s are widespread and plentiful, no evidence has surfaced that the species is anything but extinct.

Other evidence suggests that the great white shark is more closely related to the [[mako shark]] than to the megalodon.<ref>{{cite web | url = http://www.livescience.com/animalworld/050426_great_white.html | title = Great White Related to Mako Shark | publisher = [[Live Science]] | date = [[2005-04-26]] | accessdate = 2006-11-18}}</ref> According to this theory, ''[[Carcharodon orientalis]]''{{Verify source|date=August 2007}} and the broad tooth mako ''[[Isurus hastalis]]'' are fossil sharks that are considered ancestral to the great white. The ''[[Carcharocles]]'' and ''[[Otodus obliquus]]'' sharks are in this case considered the ancient representatives of the extinct megalodon lineage; indeed, ''Carcharocles megalodon'' is a popular alternative classification of the megalodon.

==Distribution and habitat==

[[Image:Whiteshark-TGoss5b hf.jpg|thumb|250px|left|White shark at [[Guadalupe Island|Isla Guadalupe, Mexico]]]] Great white sharks live in almost all coastal and offshore waters which have a water temperature of between 12 and 24° [[celsius|C]] (54° to 75° [[Fahrenheit|F]]), with greater concentrations off the southern coasts of [[Australia]], off [[South Africa]], [[California]], [[Mexico]]'s [[Guadalupe Island|Isla Guadalupe]] and to a degree in the [[Mediterranean Sea|Central Mediterranean]] and [[Adriatic Sea]]s. One of the densest known populations is found around [[Gansbaai, Western Cape|Dyer Island, South Africa]] where much research on the shark is conducted. It can be also found in tropical waters like those of the [[Caribbean]] and has been recorded off [[Mauritius]].<ref name="CITES">

{{cite web|url=http://www.cites.org/eng/cop/11/prop/48.pdf|

publisher="CITES"|

title="Proposal to include Carcharodon carcharias (Great White Shark) on Appendix I of the Convention of International Trade in Endangered Species of Wild Fauna and Flora (CITES)"|

accessdate=2007-04-22}}</ref>

It is a [[Pelagic zone|pelagic]] fish, but recorded or observed mostly in coastal waters in the presence of rich game like [[fur seal]]s, [[sea lion]]s, [[cetacean]]s, other sharks and large bony fish species. It is considered an open-ocean dweller and is recorded from the surface down to depths of {{m to ft|1280|abbr=yes}}, but is most often found close to the surface.

In a recent study great white sharks from California were shown to migrate to an [[Shark Cafe|area between Baja California and Hawaii]], where they spend at least 100 days of the year before they migrate back to [[Baja California|Baja]]. On the journey out, they swim slowly and dive down to around {{m to ft|900|abbr=yes}}. After they arrive, they change behaviour and do short dives to about {{m to ft|300|abbr=yes}} for up to 10 minutes. It is still unknown why they migrate and what they do there; it might be seasonal feeding or possibly a mating area.<ref name="LATimes">{{cite web|

url=http://www.latimes.com/travel/outdoors/la-sp-outdoors29sep29,0,4253252.story?coll=la-home-headlines|

publisher="Los Angeles Times"|

title="The Great White Way"|

accessdate=2006-10-01}}</ref>

In a similar study a great white shark from South Africa was tracked swimming to the northwestern coast of Australia and back to the same location in South Africa, a journey of {{km to mi|20000|abbr=yes}} in under 9 months.<ref name="WSharkTrust">{{cite web|

url=http://www.whitesharktrust.org/migration/main.html|

publisher="White Shark Trust"|

title="South Africa - Australia - South Africa "|

accessdate=2006-10-25}}</ref>

==Anatomy and appearance==

[[Image:Carcharodon carcharias01.jpg|thumb|left|225px|''Carcharodon carcharias'']]

The great white shark has a robust large conical-shaped [[snout]]. It has almost the same size upper and lower [[lobes]] on the tail fin (like most [[mackerel shark]]s, but unlike most other sharks).

Great white sharks display [[countershading]], having a white underside and a grey dorsal area (sometimes in a brownish or bluish shade) that gives an overall "mottled" appearance. The colouration makes it difficult for prey to spot the shark because it breaks up the shark's outline when seen from a lateral perspective. When viewed from above the darker shade blends in with the sea and when seen from below casts a minimal silloutte against the sunlight.

Great white sharks, like many other sharks, have rows of [[tooth|teeth]] behind the main ones, allowing any that break off to be rapidly replaced. A great white shark's teeth are serrated and when the shark bites it will shake its head side to side and the teeth will act as a saw and tear off large chunks of flesh. Great white sharks often swallow their own broken off teeth along with chunks of their prey's flesh.

===Size===

A typical adult great white shark measures 4 to 4.8 [[metre|m]] (13 to 16 [[foot (measurement)|ft]]) with a typical weight of 680 to 1,100 [[kilogram|kg]] (1,500 to 2,450 [[pound (mass)|lb]]), females generally being larger than males. The maximum size of the great white shark has been subject to much debate, conjecture, and misinformation. [[Richard Ellis (biologist)|Richard Ellis]] and [[John E. McCosker]], both academic shark experts, devote a full chapter in their book, ''The Great White Shark'' (1991), to analysing various accounts of extreme size.

Today, most experts contend that the great white shark's "normal" maximum size is about {{m to ft|6|abbr=yes}}, with a "normal" maximum weight of about {{kg to lb|1900|abbr=yes}}.

For several decades, many ichthyological works, as well as the ''[[Guinness Book of World Records]]'', listed two great white sharks as the largest individuals caught: an {{m to ft|11|abbr=yes}} great white captured in South [[Australia]]n waters near [[Port Fairy, Victoria|Port Fairy]] in the 1870s, and an {{m to ft|11.3|abbr=yes}} shark trapped in a herring weir in [[New Brunswick]], [[Canada]] in the 1930s. While this was the commonly accepted maximum size, reports of 7.5 to 10 metre (25 to 33.3 ft) great white sharks were common and often deemed credible.

[[Image:Great white shark caught in Seven Star Lake in 1997.jpg|250px|thumb|left|Great white shark caught off [[Hualien County]], [[Taiwan]] on [[May 14]] [[1997]]. Reportedly{{Fact|date=September 2007}} almost 7 metres in length and weighing 2500 kg, .]]

Some researchers questioned the reliability of both measurements, noting they were much larger than any other accurately-reported great white shark. The New Brunswick shark may have been a misidentified [[basking shark]], as both sharks have similar body shapes. The question of the Port Fairy shark was settled in the 1970s, when J.E. Reynolds examined the shark's jaws and "found that the Port Fairy shark was of the order of 5 m (17 feet) in length and suggested that a mistake had been made in the original record, in 1870, of the shark's length.<ref>{{cite web|url=http://homepage.mac.com/mollet/Cc/Mike_Cappo.html |title=Size and age of the white pointer shark, ''Carcharodon carcharias'' (Linnaeus)|accessdate=2006-09-27}}</ref>

Ellis and McCosker write that "the largest White Sharks accurately measured range between 19 and 21 ft [about 5.8 to 6.4 m], and there are some questionable 23-footers [about 7 m] in the popular — but not the scientific — literature".  Furthermore, they add that "these giants seem to disappear when a responsible observer approaches with a tape measure." (For more about legendary exaggerated shark measurements, see [[The Submarine (shark)|the submarine]]).

The largest specimen Ellis and McCosker endorse as reliably measured was {{m to ft|6.4|abbr=yes}} long, caught in [[Cuba]]n waters in 1945; though confident in their opinion, Ellis and McCosker note other experts have argued this individual might have been a few feet shorter. There have since been claims of larger great white sharks, but, as Ellis and McCosker note, verification is often lacking and these extraordinarily large great white sharks have, upon examination, all proved under the 20-21 ft limit. For example, a much-publicized female great white said to be {{m to ft|7.13|abbr=yes}} was fished in [[Malta]] in 1987 by Alfredo Cutajar. In their book, Ellis and McCosker agree this shark seemed to be larger than average, but they did not endorse the 7.13 metres measurement. In the years since, experts eventually found reason to doubt the claim, due in no small part to conflicting accounts offered by Cutajar and others. A [[BBC]] photo analyst concluded that even "allowing for error ... the shark is concluded to be in the 18.3 ft [5.5 m] range and in no way approaches the 23 ft [7 m] reported by Abela." (as in original) <ref>{{cite web |url=http://www.zoo.co.uk/~z9015043/news_archives.html#record |title=Maltese '7 metre' great white shark was not a world record|accessdate= 2006-09-27}}</ref>

According to the Canadian Shark Research Centre, the largest accurately measured great white shark was a female caught in August 1988 at [[Prince Edward Island]] off the Canadian (North Atlantic) coast and measured {{m to ft|6.1|abbr=yes}}. The shark was caught by David McKendrick, a local resident from Alberton, West Prince{{Fact|date=February 2007}}.

The question of maximum weight is complicated by an unresolved question: when weighing a great white shark, does one account for the weight of the shark's recent meals? With a single bite, a great white can take in up to {{kg to lb|14|abbr=yes}} of flesh, and can gorge on several hundred kilograms or pounds of food.

Ellis and McCosker write in regards to modern great white sharks that "it is likely that [Great White] sharks can weigh as much as 2 tons", but also note that the largest recent scientifically measured examples weigh in at about 2 [[tonne]]s (1.75 [[short ton]]s).

The largest great white shark recognized by the [[International Game Fish Association]] (IGFA) is one landed by Alf Dean in south Australian waters in 1959, weighing {{kg to lb|1208|abbr=yes}}. Several larger great white sharks caught by anglers have since been verified, but were later disallowed from formal recognition by IGFA monitors for rules violations.

==Adaptations==

[[Image:Great white shark 100.JPG|250px|thumb|right|A great white shark going after a buoy]]

Great white sharks, like all other sharks, have an extra sense given by the [[Ampullae of Lorenzini]], which enables them to detect the electromagnetic field emitted by the movement of living animals. Every time a living creature moves it generates an electrical field and great whites are so sensitive they can detect half a billionth of a [[volt]]. Most fish have a less developed but similar ability in the horizontal line along their body.

To more successfully hunt fast moving and agile prey such as sea lions, the [[poikilothermic]] great white shark has developed adaptations that allow it to maintain a body temperature warmer than the surrounding water. One of these adaptations is a "[[rete mirabile]]" (Latin for "wonderful net"). This close web-like structure of veins and arteries, located along each lateral side of the shark, conserves heat by warming the cooler arterial blood with the venous blood that has been warmed by the working muscles. This keeps certain parts of the body (particularly the brain) at temperatures up to 14°C<ref>[http://www.elasmo-research.org/education/white_shark/p_body_temp.htm Body Temperature of the Great White and Other Lamnoid Sharks]</ref> above the surrounding water, while the heart and gills remain at sea-temperature. When conserving energy (a great white shark can go weeks between meals), the core body temperature can drop to match the surroundings. A great white shark's success in raising its core temperature is an example of [[gigantothermy]]. Therefore, the great white shark can be considered an [[endothermic]] [[poikilotherm]], because its body temperature is not constant but is internally regulated.

==Diet and hunting==

[[Image:Whale carcas with shark bites.JPG|thumb|250px|left|A carcass of a whale with typical sharks bites]]

Great white sharks are [[carnivorous]], and primarily eat [[fish]] (including [[Batoidea|ray]]s, [[tuna]], and smaller [[shark]]s), [[dolphin]]s, [[porpoise]]s, [[whale]] carcasses and [[pinniped]]s such as [[Earless seal|seal]]s, [[fur seal]]s and [[sea lion]]s. [[Sea otter]]s and [[sea turtle]]s are also taken at times. Great whites have also been known to eat objects that they are unable to digest. In great white sharks above 3.41 metres (11 ft, 2 in) a diet consisting of a higher proportion of mammals has been observed.<ref name="Feeding">{{cite web|url=http://home.uchicago.edu/~arice/Estrada.et.al.2006.pdf|title=Use of isotopic analysis of vertebrae in reconstructing ontogentic feeding ecology in white sharks

|author="James A. Estrada, Aaron N. Rice, Lisa J. Natanson, and Gregory B. Skomal"|publisher="Ecological Society of America"|accessdate=2006-10-20}}</ref> These sharks prefer prey with high contents of energy-rich fat. Shark expert Peter Klimley used a rod-and-reel rig and trolled carcasses of a seal, a pig, and a sheep to his boat in the South [[Farallon Islands|Farallons]]. The sharks attacked all three baits but rejected the lower fat content sheep carcass.<ref>[http://www.elasmo-research.org/education/topics/b_catch.htm Catch as Catch Can]</ref>

The great white is regarded as an [[apex predator]] with its only real threats from humans and, in at least one incident, the [[orca]].<ref>[http://edition.cnn.com/EARTH/9710/08/whale.vs.shark/ Clash of the titans: Whale vs. Shark] CNN [[October 8]], [[1997]].</ref> Although their diets overlap greatly, there are few reports of encounters between orcas and great whites, and they don't seem to directly compete with each other. Great whites are also sometimes preyed on by larger specimens.

[[Image:Surfacing great white.JPG|thumb|right|250px|Surfacing great white]]

A great white shark primarily uses its extra senses (i.e, electrosense and mechanosense) to locate prey from far off. Then, the shark uses smell and hearing to further verify that its target is food. At close range, the shark utilizes sight for the attack.

Great white sharks' reputation as ferocious predators is well-earned, yet they are not (as was once believed) indiscriminate "eating machines". They typically hunt using an "ambush" technique, taking their prey by surprise from below. Near the now-famous [[Seal Island, South Africa|Seal Island]], in South Africa's False Bay; studies have shown that the shark attacks most often occur in the morning, within 2 hours after sunrise. The reason for this is that it is hard to see a shark close to the bottom at this time. The success rate of attacks is 55% in the first 2 hours, it falls to 40% in late morning and after that the sharks stop hunting.<ref name="NHmag">{{cite web|url=http://nhmag.com/master.html?http://nhmag.com/1006/1006_feature.html|title=Sociable Killers

|author="R. Aidan Martin and Anne Martin"|publisher="Natural History Magazine, Inc"|accessdate=2006-09-30}}</ref>

The hunting technique of the white shark varies with the species it hunts. When hunting [[Cape fur seal]]s off Seal Island, South Africa; the shark will ambush it from below at high speeds and hit the seal at mid-body. They go so fast that they actually breach out of the water. They have also been observed chasing their prey after a missed attack. The prey is usually attacked at the surface.<ref>[http://www.elasmo-research.org/education/white_shark/predation.htm White Shark Predatory Behavior at Seal Island]</ref>

When hunting [[Northern elephant seal]]s off California, the shark immobilizes the prey with a large bite to the hindquarters (which is the main source of the seal's mobility) and waits for the seal to bleed to death. This technique is especially used on adults which are large and dangerous. Prey is normally attacked sub-surface. [[Harbour seal]]s are simply grabbed from the surface and pulled down until they stop struggling. They are then eaten near the bottom. [[California sea lion]]s are ambushed from below and struck in mid-body before being dragged and eaten.<ref>[http://www.sharkresearchcommittee.com/predation.htm Predatory Behavior of Pacific Coast White Sharks]</ref>

When hunting dolphins and porpoises, white sharks attack them from above, behind or below to avoid being detected by their [[Animal echolocation#Toothed whales|echolocation]].<ref>Long, D. J; Jones, R. E (1996) ''White shark predation and scavenging on cetaceans in the Eastern North Pacific Ocean.''</ref>

A new study from the University of New South Wales in Sydney, Australia, is using CT scans of a shark's skull and complex computer models to measure the maximum bite force of the great white. The study will reveal what forces and behaviours the carnivore's skull is adapted to handle and will help resolve competing theories about its feeding behaviour.<ref>{{cite news |title=Measuring the great white's bite |url=http://www.cosmosmagazine.com/node/1499 |work=Cosmos Magazine |date=[[27 July]][[2007]]}}</ref>

==Behaviour==

[[Image:Great white shark at his back.JPG|thumb|250px|left|Great white shark lunging towards tuna bait while on its back]]

The behaviour and social structure of the white shark is not well understood but recent research shows that white sharks are more social than previously thought. In South Africa, white sharks seem to have a pecking order depending on size, sex and squatter's rights. Females dominate over males, larger sharks dominate smaller sharks, and residents dominate new comers. When hunting the white sharks tend to space out between each other and resolve conflicts with rituals and displays.<ref name="NHmag"/> White sharks rarely resort to combat although some individuals have been found with bite marks that match that of other white sharks. This suggests that when their personal space is intruded upon, a white shark will give the intruder a warning bite. Another possibility is that white sharks may softly bite other individuals as a way of showing their dominance.

Also, as noted above, white sharks can be [[cannibalism (zoology)|cannibalistic]].

The great white shark is one of only a few sharks known to regularly lift its head above the sea surface to gaze at other objects such as prey; this is known as "[[Whale behaviour#Spyhopping|spy-hopping]]". This behaviour has also been seen in at least one group of [[blacktip reef shark]]s, but this might be a behaviour learned from interaction with humans (it is theorized that the shark may also be able to smell better this way, because smells travel through air faster than through water). They are very curious animals, and can display a high degree of intelligence and personality when conditions permit (such as in the clear waters off of [[Guadalupe Island|Isla Guadalupe]], [[Mexico]]).

==Reproduction==

There is still a great deal that is unknown about great white shark behaviour, such as their [[mating]] habits. Birth has never been observed, but several pregnant females have been examined. Great white sharks are [[Ovoviviparity|ovoviviparous]], the eggs developing in the female's uterus, hatching there and continuing to develop until they are born, at which point they are perfectly capable predators. The embryos can feed off unfecundated eggs. The delivery takes place in the period transitioning spring and summer. When giving birth, the female has to fast to prevent herself from eating her young after they are born.

The young, which number 8 or 9 (with a maximum of perhaps 14) for a single delivery, are about 1.5 metres (5 ft) long when born. Their teeth are provided with small side cusps. They grow rapidly, reaching 2 metres of length in the first year of life. Almost nothing, however, is known about how and where the great white mates. There is some evidence that points to the near-soporific effect resulting from a large feast (such as a whale carcass) possibly inducing mating.

Great white sharks can also mate when a male is twelve-years old and a female is around fourteen. A great white's lifespan has not been definitively established, though many sources estimate that great whites live 30 to 40 years. It would not be unreasonable to expect such a slow maturing animal to live longer however.<ref>[http://www.prbo.org/cms/176 Natural History of the White Shark]</ref>

==Relationship with humans==

===Shark attacks===

[[Image:Jaws Great White Shark South Australia 1138572075.jpg|thumb|right|The great white shark is unique in the fact it is one of the few sharks that can spyhop above water.]]

More than any documented attack, [[Steven Spielberg|Steven Spielberg's]] 1975 film ''[[Jaws (film)|Jaws]]'' provided the great white shark with the image of a "man eater" in the public mind. While great white sharks have been responsible for fatalities in humans, they typically do not target humans as prey: for example, in the [[Mediterranean Sea]] there were 31 confirmed attacks against humans in the last two centuries, only a small number of them deadly. Many incidents seem to be caused by the animals "test-biting" out of curiosity. Great white sharks are known to perform test-biting with [[buoy]]s, [[flotsam]], and other unfamiliar objects as well, and might grab a human or a [[surfboard]] with their mouth in order to determine what kind of object it might be.

Other incidents seem to be cases of mistaken identity, in which a shark ambushes a bather or surfer, usually from below, believing the silhouette it sees on the surface is a seal. Many attacks occur in waters with low visibility, or other situations in which the shark's senses are impaired. It has been speculated that the species typically does not like the taste of humans, or at least that the taste is unfamiliar.<ref> http://serendip.brynmawr.edu/biology/b103/f00/web1/mccabe.html </ref>

However some researchers have hypothesized that the reason the proportion of fatalities is low is not because sharks do not like human flesh, but because humans are often able to get out of the water after the shark's first bite. In the 1980s John McCosker noted that divers who dived solo and were attacked by great whites were generally at least partially consumed, while divers who followed the buddy system were normally pulled out of the water by their colleagues before the shark could finish its attack. Tricas and McCosker suggest that a standard attack modus operandi for great whites is to make an initial devastating attack on its prey, and then wait for the prey to weaken before going in to consume the wounded animal. A human's ability to get to land (or onto a boat) with the help of others is unusual for a great white's prey, and thus the attack is foiled.<ref>{{cite journal | first= T.C.| last=Tricas |coauthors=John McCosker|McCosker, J.E.| title= [[California Academy of Sciences|Proceedings of the California Academy of Sciences]] | journal=Predatory behavior of the white shark, ''Carcharodon carcharias'', and notes on its biology | volume=43 | issue=14 | pages=221-238 | date=1984 }}</ref>

Humans, in any case, are not healthy for great white sharks to eat because the sharks' digestion is too slow to cope with the human body's high ratio of bone to muscle and fat. Accordingly, in most recorded attacks, great whites have broken off contact after the first bite. Fatalities are usually caused by loss of blood from the initial limb injury rather than from critical organ loss or from whole consumption.

Biologist Douglas Long and Tyler B. write that the great white shark's "role as a menace is exaggerated; more people are killed in the U.S. each year by dogs than have been killed by great white sharks in the last 100 years."<ref>{{cite web|url=http://www.ucmp.berkeley.edu/nAMEvertebrates/Doug/shark.html|title=The Great White Shark |accessdate=2003-09-27}}</ref> However, such comments should be taken in context; interaction between humans and canines takes place far more regularly and in greater numbers than it does between humans and sharks.

Many "shark repellents" have been tested, some using scent, others using protective clothing, but to date the most effective is an electronic beacon ([[Protective Oceanic Device|POD]]) worn by the diver/surfer that creates an electric field which disturbs the shark's sensitive electro-receptive sense organs, the [[ampullae of Lorenzini]].

=== Attacks on boats ===

Great white sharks infrequently attack and sometimes even sink boats, in a few cases they have attacked boats up to 10 meters in length. They have bumped or knocked people overboard, usually 'attacking' the boat from the stern. In one case (in 1936), a large shark leapt completely into the South African fishing boat ''Lucky Jim'', knocking a crewman into the sea. The sharks do not do this to attack the people or sink the boat, but to investigate it.{{Fact|date=September 2007}}

===Great white sharks in captivity===

[[Image:Great white aqurium.jpg|thumb|left|200px|Great white shark in the [[Monterey Bay Aquarium]] in September, 2006]]

All attempts to keep a great white shark in captivity prior to August 1981 lasted 11 days or less. However, that month a great white broke previous records by lasting 16 days in captivity at [[SeaWorld]] [[San Diego]] before being released into the wild.<ref>{{cite web| url=http://www.usatoday.com/news/science/2004-10-02-great-white_x.htm |title=Great white shark sets record at California aquarium |publisher= [[USA Today]] |date=2004-10-02| accessdate=2006-09-27}}</ref>

In 1984, shortly before opening day, the [[Monterey Bay Aquarium]] in [[Monterey, California]] housed its first great white shark, which died after 10 days. In July 2003, Monterey researchers captured a small female and kept it in a large, netted pen off Malibu for five days, where they had the rare success of getting the shark to feed in captivity before it was released.<ref>{{cite web| url=http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2004/09/16/BAGCM8PN3E1.DTL |title= Great white shark puts jaws on display in aquarium tank |publisher=San Francisco Chronicle| date=2004-09-16| accessdate=2006-09-27}}</ref> It was not until September 2004 that the aquarium was the first to place a great white on long-term exhibit. The young female, who was caught off the coast of Ventura, was kept in the aquarium's massive 1 million-gallon (3,800,000 litres) Outer Bay exhibit for 198 days before her successful release back to the wild in March 2005. She was tracked for 30 days after her early morning release.<ref>{{cite web| url=http://www.mbayaq.org/cr/whiteshark.asp |title=White Shark Research Project| publisher=[[Monterey Bay Aquarium]]| accessdate=2006-09-27}}</ref> On the evening of [[August 31]] [[2006]] the aquarium introduced a second shark to the Outer Bay exhibit. The juvenile male, caught outside [[Santa Monica Bay]] on [[August 17]] <ref>{{cite web| url=http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2006/09/01/MNG1IKTP904.DTL|title= Great white shark introduced at Monterey Bay Aquarium| publisher=San Francisco Chronicle | date=2003-09-01| accessdate=2006-09-27}}</ref>, had its first official meal in captivity (a large salmon steak) on [[September 8]], 2006 and as of that date, the shark was estimated to be 1.72 metres (5 ft 8 in) and to weigh approximately 47 kilograms (104 lb). He was released on [[January 16]] [[2007]] after 137 days in captivity.

Probably the most famous great white shark to be kept in captivity was a female named "Sandy", which in August 1980 became the first and only great white shark to be housed at the [[Steinhart Aquarium]] in [[San Francisco, California]]. She was returned to the wild because she would not eat anything given to her and constantly bumped against the walls.<ref>{{cite web| url=http://www.elasmo-research.org/education/white_shark/electroreception.htm |title=Electroreception |publisher=Elasmo-research| accessdate=2006-09-27}}</ref>

===Shark tourism and cage diving===

[[Image:Chuming the water.jpg|thumb|right|Putting chum in the water]]Shark cage-diving is when a group of tourists, or those who wish to study the sharks up close are lowered into the water beside a boat, protected by a steel cage. From this view point it is easier to view the sharks up close without the dangers of being bitten. Cage diving is most common off the coasts of [[Australia]], [[South Africa]], and [[Guadalupe Island]] off the coast of Baja California as these are places where great white sharks are most likely to be seen.

Viewing sharks from the safety of a cage gives tourists an [[adrenaline]] rush and has become a booming industry. A common practice is to [[chum]] the water to draw in sharks for the tourists to view. These practices have raised the fear that sharks may be becoming more accustomed to people in their environment and beginning to associate human activity with food - a potentially dangerous situation. It is claimed that certain methods of chumming, such as when bait on a wire is drawn towards the divers in the cage, which may result in the shark striking the cage, exacerbate this problem. Other operators purposefully draw the bait away from the cage causing the shark to swim past the divers.

Companies respond that they are being made the scapegoats, as people try to find someone to blame for shark attacks on humans. Most point out that lightning tends to strike humans more often than sharks bite humans.<ref>{{cite web|url=http://www.flmnh.ufl.edu/fish/Sharks/attacks/relarisklightning.htm |title=Shark Attacks Compared to Lightning|publisher= [[Florida Museum of Natural History]] |date=2003-07-18|accessdate=2006-11-07}}</ref> Their position is that further research needs to be done before banning practices such as chumming which are said to alter sharks' natural behaviour.<ref>{{cite web| url=http://news.bbc.co.uk/1/hi/world/africa/3716093.stm |title=SA shark attacks blamed on tourism |publisher= [[BBC]] |date=2004-04-15| accessdate=2006-10-24}}</ref>

It has been advised that all dive boats should only use chum in areas in which Whites are known to actively patrol anyway, and these should be far enough away from human leisure areas so as not to draw the sharks towards them. Also, responsible dive operators will not feed the sharks; only sharks that are willing to scavenge will follow the chum trail, and if they find no food at the end then the shark will soon swim off and not associate chum with a meal. It has been suggested that government licensing strategies may help enforce these suggested advisories.

The shark tourist industry has some financial leverage in conserving this animal. For a fisherman with limited income, a single set of White jaws can fetch up to £20,000, a very substantial amount of money for a day's fishing. However, the value of the dead animal is a fraction of the value of viewing a live shark, which can become a more viable and sustainable economic activity to the local community. For example, the dive industry in Gaansbai South Africa, consists of about six boat operators with each boat taking around 30 people out to sea a day; if each person pays anywhere between £50 to £150, then in a single day a solitary live shark that visits each boat can create anywhere between £9,000 to £27,000 of revenue daily.

==Conservation status==

It is unclear how much a concurrent increase in fishing for great white sharks had to do with the decline of great white shark population from the 1970s to the present. No accurate numbers on population are available, but populations have clearly declined to a point at which the great white shark is now considered endangered. Their reproduction is slow, with sexual maturity occurring at about nine years of age, the population, therefore, can take a long time to rise.

The [[Convention on International Trade in Endangered Species]] (C.I.T.E.S.) has put the great white shark on its 'Appendix II' list of [[endangered species]]. The shark is targeted by fishermen for its jaws, teeth, and fins, and as a game fish. The great white shark, however, is rarely an object of commercial fishing, although its flesh is considered valuable. If casually captured (it happens for example in some [[tonnara|tonnare]] in the [[Mediterranean]]), it is sold as ''[[smooth-hound shark]]''.

From April 2007 great white sharks are fully protected within 200 [[nautical miles]] of [[New Zealand]] and additionally from fishing by New Zealand-flagged boats outside this range.<ref>{{cite web| url=http://www.nzherald.co.nz/section/story.cfm?c_id=1&objectid=10413182| title=Great white sharks to be protected |publisher=[[New Zealand Herald]]| date=2006-11-30| accessdate=2006-11-30}}</ref>

==References==

;General references

* {{IUCN2006|assessors=Fergusson ''et al''|year=2000|id=3855|title=Carcharodon carcharias|downloaded=[[08 May]] [[2006]]}} Database entry includes justification for why this species is vulnerable

* {{ITIS|ID=159903|taxon=Carcharodon carcharias|year=2006|date=23 January}}

* {{FishBase_species|genus=Carcharodon|species=carcharias|year=2005|month=10}}

* [http://repositories.cdlib.org/sio/lib/3/ Biology of the White Shark, a Symposium.] Gretchen Sibley editor; Jeffrey A. Siegel, Camm C. Swift assistant editors. Los Angeles: Southern California Academy of Sciences, 1985. Memoirs of the Southern California Academy of Sciences, volume 9.

* {{marinebio|id=38|name=Great White Shark, ''Carcharodon carcharias''}}

* [http://www.sharkresearchcommittee.com Shark Research Committee]

</div>

==External links==

* [http://www.sharkattacksurvivors.com/ Shark Attack Survivors Shark Attack Education and Prevention]

* ARKive - [http://www.arkive.org/species/GES/fish/Carcharodon_carcharias/ Images and movies of the great white shark, ''Carcharodon carcharias'']

* [http://www.zoo.co.uk/~z9015043/gws_conserv.html Review of the great white shark] Ian K. Fergusson, Shark Trust & IUCN Shark Specialist Group

* [http://sacoast.uwc.ac.za/education/resources/envirofacts/greatwhite.htm Envirofacts: Great white shark]

* [http://www.pbs.org/kqed/oceanadventures/episodes/sharks/indepth-senses.html In-depth article: Shark's Super Senses from the PBS Ocean Adventures site]

* [http://www.sharkinformation.org/sharkprofiles/great-white-shark/ Photos and profile of the great white shark]

* [http://www.livescience.com/animalworld/050426_great_white.html Are great whites descended from mega-sharks?]

* [http://www.jawshark.com/great_white_fatalities_by_country_usa.html Great White fatalities by country]

* [http://www.underwater.com.au/article.php/id/7395/ "Great White Sharks - The Truth"] by documentary maker Carly Maple - Australian focus

* [http://www.topp.org/species/white_shark/ TOPP, Tagging of Pacific Predators], a research group that tags and studies the habits and migration of the white shark.

===Videos===

* [http://www.diveaday.tv/content/view/57/37/ Spectacular video of cage diving with Great White Sharks in Guadalupe, Mexico]

* [http://www.cbsnews.com/stories/2005/12/06/60minutes/main1099368.shtml Great white shark gets stuck in cage/ shark tourism issues]

* [http://www.bbc.co.uk/nature/animals/planetearth/realmedia/video/bb/pe0107_16x9_bb.ram Slow motion sequence of great white shark attacking seals] from [[Planet Earth (TV series)]]

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