Instruct: Given a question, retrieve passages that answer the question.
Query: Do great white sharks migrate to australia?
According to a recent study, California great whites have migrated to an area between Baja California Peninsula and Hawaii known as the White Shark Café to spend at least 100 days before migrating back to Baja. On the journey out, they swim slowly and dive down to around 900m (3,000ft). After they arrive, they change behavior and do short dives to about 300m (980ft) for up to ten minutes. Another white shark that was tagged off the South African coast swam to the southern coast of Australia and back within the year. A similar study tracked a different great white shark from South Africa swimming to Australia's northwestern coast and back, a journey of 20,000km (12,000mi; 11,000nmi) in under nine months.[27] These observations argue against traditional theories that white sharks are coastal territorial predators, and open up the possibility of interaction between shark populations that were previously thought to have been discrete. The reasons for their migration and what they do at their destination is still unknown. Possibilities include seasonal feeding or mating.[28]
Stephan Swanson came to prominence as a marine researcher when he successfully placed the satellite transmitter on the famous Great white shark Nicole, the first great white shark ever to be tracked on a 20,000 kilometer migration from South Africa to Australia and back. Due to his ability to handle large marine predators, such as the great white shark, he was contracted as an expedition biologist to travel to Guadeloupe and place satellite transmitters on the dorsal fins of Great Whites. His historical capture and release of a 5m long, 1800 kilogram great white shark is documented in the National Geographic Marine Special "Ultimate Shark".
More than any documented bite incident, Peter Benchley's best-selling novel Jaws and the subsequent 1975 film adaptation directed by Steven Spielberg provided the great white shark with the image of being a "man eater" in the public mind.[112] While great white sharks have killed humans in at least 74 documented unprovoked bite incidents, they typically do not target them: for example, in the Mediterranean Sea there have been 31 confirmed bite incidents against humans in the last two centuries, most of which were non-fatal. Many of the incidents seemed to be "test-bites". Great white sharks also test-bite buoys, flotsam, and other unfamiliar objects, and they might grab a human or a surfboard to identify what it is.
At present, hang baits are illegal off Isla Guadalupe and reputable dive operators do not use them. Operators in South Africa and Australia continue to use hang baits and pinniped decoys.[136] In South Australia, playing rock music recordings underwater, including the AC/DC album Back in Black has also been used experimentally to attract sharks.[137]
According to J.E. Randall, the largest white shark reliably measured was a 6.0m (19.7ft) individual reported from Ledge Point, Western Australia in 1987.[38] Another great white specimen of similar size has been verified by the Canadian Shark Research Center: A female caught by David McKendrick of Alberton, Prince Edward Island, in August 1988 in the Gulf of St. Lawrence off Prince Edward Island. This female great white was 6.1m (20ft) long.[5] However, there was a report considered reliable by some experts in the past, of a larger great white shark specimen from Cuba in 1945.[39][40][41][42] This specimen was 6.4m (21ft) long and had a body mass estimated at 3,324kg (7,328lb).[39][41] However, later studies also revealed that this particular specimen was actually around 4.9m (16ft) in length, a specimen in the average maximum size range.[5]
The waters adjoining Dangerous Reef are notable as a place of aggregation for great white sharks. It was a popular site for gamefishing from early in the 20th century until 1997 when the great white shark became a protected species in Australia. Notable gamefishers who visited the waters around Dangerous Reef included the Australian radio personality, Jack Davey, in 1952 and the American novelist, Zane Grey, in 1939. In 1969, the island/reef system was one of the sites used for filming of the great white shark documentary, Blue Water White Death. In 1974, footage of live sharks used in the 1975 American film, "Jaws" was filmed at Dangerous Reef by Ron Taylor. From the 1970s up until 2002, Dangerous Reef was one of the sites used in South Australia for shark cage diving where tourists could observe sharks from within the water.
Neptune Islands Conservation Park is a protected area occupying most of the Neptune Islands in South Australia about south-south east of Port Lincoln. It was established in 1967 principally to protect a New Zealand fur seal breeding colony. The conservation park was subsequently expanded to include the adjoining waters in order to control and manage berleying activities used to attract great white sharks. As of 2002, the conservation park is the only place in Australia where shark cage diving to view great white sharks is legally permitted.
The national conservation status of the great white shark is reflected by all Australian states under their respective laws, granting the species full protection throughout Australia regardless of jurisdiction.[101] Many states had prohibited the killing or possession of great white sharks prior to national legislation coming into effect. The great white shark is further listed as Threatened in Victoria under the Flora and Fauna Guarantee Act, and as rare or likely to become extinct under Schedule 5 of the Wildlife Conservation Act in Western Australia.[101]
Interspecific competition between the great white shark and the orca is probable in regions where dietary preferences of both species may overlap.[72] An incident was documented on 4 October 1997, in the Farallon Islands off California in the United States. An estimated 4.7–5.3m (15–17ft) female orca immobilized an estimated 3–4m (9.8–13.1ft) great white shark.[89] The orca held the shark upside down to induce tonic immobility and kept the shark still for fifteen minutes, causing it to suffocate. The orca then proceeded to eat the dead shark's liver.[72][89][90] It is believed that the scent of the slain shark's carcass caused all the great whites in the region to flee, forfeiting an opportunity for a great seasonal feed.[91] Another similar attack apparently occurred there in 2000, but its outcome is not clear.[92] After both attacks, the local population of about 100 great whites vanished.[90][92] Following the 2000 incident, a great white with a satellite tag was found to have immediately submerged to a depth of 500m (1,600ft) and swum to Hawaii.[92] In 2015, a pod of orcas was recorded to have killed a great white shark off South Australia.[93] In 2017, along the South African coast, four great whites were found washed ashore with their livers removed with what was described as "surgical precision". Local scientists claim that pods of orcas in the area were responsible for the attacks.[94]
However it should be noted that shark and bycatch mortality from drum lines is minor compared to Commercial fishing. On average 15 Great white sharks are caught by the NSW and Queensland shark control programme each year, compared to 186 caught in Australia from other activities. Australia's commercial shark fishing industry is catching over 1200 tonne of shark each year, of which 130 are Great white sharks. The NSW prawn trawling industry alone results in 64 tonne of shark as bycatch each year, with two thirds dying. Tuna and swordfish longline fishing off the coast of South Africa reported 39,000 to 43,000 sharks killed each year between 1995 and 2005. "Sharksavers" estimates that in total 50 million sharks are caught unintentionally each year as bycatch by the commercial fishing industry.
It should be noted that the impact of shark culling is minor compared to bycatch from Commercial fishing. On average 15 Great white sharks are caught by the NSW and Queensland shark control programme each year, compared to 186 caught in Australia from other activities. Australia's commercial shark fishing industry is catching over 1200 tonne of shark each year, of which 130 are Great white sharks. The NSW prawn trawling industry alone results in 64 tonne of shark as bycatch each year, with two thirds dying. Tuna and swordfish longline fishing off the coast of South Africa reported 39,000 to 43,000 sharks killed each year between 1995 and 2005. "Sharksavers" estimates that in total 50 million sharks are caught unintentionally each year as bycatch by the commercial fishing industry.
This shark's behavior and social structure is not well understood. In South Africa, white sharks have a dominance hierarchy depending on the size, sex and squatter's rights: Females dominate males, larger sharks dominate smaller sharks, and residents dominate newcomers. When hunting, great whites tend to separate and resolve conflicts with rituals and displays. White sharks rarely resort to combat although some individuals have been found with bite marks that match those of other white sharks. This suggests that when a great white approaches too closely to another, they react with a warning bite. Another possibility is that white sharks bite to show their dominance.
Johnson was part of the first South African team to successfully attach a satellite transmitters to a great white shark on 24 July 2001.Johnson has tagged Great White Sharks for research purposes. His major scientific discoveries have been the satellite tracking of Nicole (a 3.6m great white shark) on a return migration from South Africa to Australia and back, and documenting the Great White Shark hunting Cape fur seal at night time, a previously unknown behavior. Between 2001 and 2005 Johnson conducted research on the controversial practice of chumming great white shark for tourism, often called cage diving, where he discovered evidence of conditioning, however he did not link this to increased numbers of attacks on human beings. In January 2008 he led a pilot study to Ponto Do Ora (Mozambique) on the Zambezi shark, also known as the Bull shark.
While the term "shark attack" is in common use for instances of humans being wounded by sharks, it has been suggested that this is based largely on the misconception that white sharks and other large predatory sharks (such as bull and tiger sharks) seek out humans as prey. A recent review recommends that only in the very rare instances where a shark clearly predated on a human should the bite incident be termed an "attack," which implies predation, and that otherwise it is more accurate to class bite incidents as "sighting", "encounter", "bite incident", or "fatal bite incident". Sightings do not include physical interaction, encounters include physical interaction without harm, shark bites include minor and major shark bite incidents, including those that do and do not require medical attention, and fatal shark bite incidents are those that result in death. The study suggests that only in a case where an expert validates the predatory intent of a shark would it be appropriate to term a bite incident an attack.[111]
Presently, human-caused shark mortality is continuing, primarily from accidental and illegal catching in commercial and recreational fishing as well as from being caught in beach protection netting, and the populations of great white shark in Australia are yet to recover.[16]
The great white shark (Carcharodon carcharias), also known as the great white, white shark or white pointer, is a species of large mackerel shark which can be found in the coastal surface waters of all the major oceans. The great white shark is notable for its size, with larger female individuals growing to 6.1m (20ft) in length and 1,905kg (4,200lb) in weight at maturity.[3][4][5] However, most are smaller; males measure 3.4 to 4.0m (11 to 13ft), and females measure 4.6 to 4.9m (15 to 16ft) on average.[5][6] According to a 2014 study, the lifespan of great white sharks is estimated to be as long as 70 years or more, well above previous estimates,[7] making it one of the longest lived cartilaginous fish currently known.[8] According to the same study, male great white sharks take 26 years to reach sexual maturity, while the females take 33 years to be ready to produce offspring.[9] Great white sharks can swim at speeds of over 56km/h (35mph),[10] and can swim to depths of 1,200m (3,900ft).[11]
Fox, along with his son, Andrew, after more than 40 years, still continue to run Rodney Fox Great White Shark Expeditions, a shark cage diving operation to view great white sharks in the wild off Southern Australia. This operation also acts as a platform for much needed further research of great white sharks as well as encouraging quality natural history documentaries on the species.
Great White Shark viewing is available at the Neptune Islands in South Australia, South Africa, Isla Guadalupe in Mexico, and New Zealand - where Great White sharks are viewed using shark cages to keep the diver safe. Except for Isla Guadalupe where because of the exceptional visibility underwater more outside the cage diving is done than anywhere else.
It is unclear how much of a concurrent increase in fishing for great white sharks has caused the decline of great white shark populations from the 1970s to the present. No accurate global population numbers are available, but the great white shark is now considered vulnerable.[2] Sharks taken during the long interval between birth and sexual maturity never reproduce, making population recovery and growth difficult.
To more successfully hunt fast and agile prey such as sea lions, the great white has adapted 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 stomach) at temperatures up to 14°C (25°F) [56] above that of the surrounding water, while the heart and gills remain at sea temperature. When conserving energy 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 or mesotherm because its body temperature is not constant but is internally regulated.[31] Great whites also rely on the fat and oils stored within their livers for long-distance migrations across nutrient-poor areas of the oceans.[57] Studies by Stanford University and the Monterey Bay Aquarium published on 17 July 2013 revealed that in addition to controlling the sharks' buoyancy, the liver of great whites is essential in migration patterns. Sharks that sink faster during drift dives were revealed to use up their internal stores of energy quicker than those which sink in a dive at more leisurely rates.[58]
In 1984, Monterey Bay Aquarium's first attempt to display a great white shark lasted 11 days, ending when the shark died because it did not eat. Through a later program named Project White Shark, six white sharks were exhibited between 2004 and 2011 in the Open Sea community exhibit, which was constructed in the 1990s. Researchers at universities in California attributed the aquarium's success at exhibiting white sharks to the use of a net pen, which gave the sharks time to recover from capture prior to transport. A portable tank used to transport the fish to the exhibit allowed the sharks to swim continuously, which they must do in order to respire. These endeavors led to the first instance of a white shark eating in an aquarium.
The earliest known fossils of the great white shark are about 16 million years old, during the mid-Miocene epoch.[1] However, the phylogeny of the great white is still in dispute. The original hypothesis for the great white's origins is that it shares a common ancestor with a prehistoric shark, such as the C.megalodon. C. megalodon had teeth that were superficially not too dissimilar with those of great white sharks, but its teeth were far larger. Although cartilaginous skeletons do not fossilize, C. megalodon is estimated to have been considerably larger than the great white shark, estimated at up to 17m (56ft) and 59,413kg (130,983lb).[21] Similarities among the physical remains and the extreme size of both the great white and C.megalodon led many scientists to believe these sharks were closely related, and the name Carcharodon megalodon was applied to the latter. However, a new hypothesis proposes that the C.megalodon and the great white are distant relatives (albeit sharing the family Lamnidae). The great white is also more closely related to an ancient mako shark, Isurus hastalis, than to the C.megalodon, a theory that seems to be supported with the discovery of a complete set of jaws with 222 teeth and 45 vertebrae of the extinct transitional species Carcharodon hubbelli in 1988 and published on 14 November 2012.[22] In addition, the new hypothesis assigns C.megalodon to the genus Carcharocles, which also comprises the other megatoothed sharks; Otodus obliquus is the ancient representative of the extinct Carcharocles lineage.[23]
The original "SharkPOD" was tested for eight years off Dyer Island with mainly great white sharks, and was the first electronic device that was proven successful in deterring sharks when tested by Ron Taylor and Valerie Taylor in 1997 against great white sharks, tiger sharks, hammerhead sharks, and other shark species in Australia and South Africa with positive results; they made a documentary about it called "Shark POD".
The great white shark has a robust, large, conical snout. The upper and lower lobes on the tail fin are approximately the same size which is similar to some mackerel sharks. A great white displays countershading, by having a white underside and a grey dorsal area (sometimes in a brown or blue shade) that gives an overall mottled appearance. The coloration makes it difficult for prey to spot the shark because it breaks up the shark's outline when seen from the side. From above, the darker shade blends with the sea and from below it exposes a minimal silhouette against the sunlight. Leucism is extremely rare in this species, but has been documented in one great white shark (a pup that washed ashore in Australia and died).[30] Great white sharks, like many other sharks, have rows of serrated teeth behind the main ones, ready to replace any that break off. When the shark bites, it shakes its head side-to-side, helping the teeth saw off large chunks of flesh.[31] Great white sharks, like other mackerel sharks, have larger eyes than other shark species in proportion to their body size. The iris of the eye is a deep blue instead of black.[32]
In 2013, great white sharks were added to California's Endangered Species Act. From data collected, the population of great whites in the North Pacific was estimated to be fewer than 340 individuals. Research also reveals these sharks are genetically distinct from other members of their species elsewhere in Africa, Australia, and the east coast of North America, having been isolated from other populations.[107]