Great white shark
The great white shark, Carcharodon carcharias, also known as the great white, white pointer, white shark, or white death, is a species of large lamniform shark which can be found in the coastal surface waters of all the major oceans. The great white shark is mainly known for its size, with the largest individuals known to have approached or exceeded 6.1 m (20 ft) in length and 2,268 kg (5,000 lb) in weight. This shark reaches its maturity around 15 years of age and can have a life span of over 30 years.
The great white shark is arguably the world’s largest known extant macropredatory fish, and is one of the primary predators of marine mammals. It is also known to prey upon a variety of other marine animals, including fish and seabirds. It is the only known surviving species of its genus Carcharodon, and is ranked first in having the most attacks on humans.
Great white sharks live in almost all coastal and offshore waters which have water temperature between 12 and 24 °C (54 and 75 °F), with greater concentrations in the United States (Atlantic Northeast and California), South Africa, Japan, Oceania, Chile, and the Mediterranean. One of the densest known populations is found around Dyer Island, South Africa, where almost all of the shark research is done.
The great white is an epipelagic fish, observed mostly in the presence of rich game, such as fur seals, sea lions, cetaceans, other sharks, and large bony fish species. In the open ocean, it has been recorded at depths as great as 4,000 ft (1,200 m). These findings challenge the traditional notion about the great white as being a coastal species.
Distribution and habitat
Cypron-Range_Carcharodon_carchariaAccording to a recent study, California great whites have migrated to an area between Baja California 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 900 m (3,000 ft). After they arrive, they change behavior and do short dives to about 300 m (1,000 ft) for up to ten minutes.
Another white shark that was tagged off of the South African coast swam to the southern coast of Australia and back within the year. This refuted traditional theories that white sharks are coastal territorial predators and opens 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 that may support this idea include seasonal feeding or mating. A similar study tracked a great white shark from South Africa swimming to Australia’s northwestern coast and back, a journey of 20,000 km (12,000 mi; 11,000 nmi) in under nine months.
White Shark Cage Diving
Cage diving is most common at sites where great whites are frequent including the coast of South Africa, the Neptune Islands in South Australia, and Guadalupe Island in Baja California. Cage diving and swimming with sharks is a focus for a booming tourist industry due to its popularity.A common practice is to chum the water with pieces of fish to attract the sharks. These practices may make sharks more accustomed to people in their environment and to associate human activity with food; a potentially dangerous situation. By drawing bait on a wire towards the cage, tour operators lure the shark to the cage, possibly striking it, exacerbating this problem. Other operators draw the bait away from the cage, causing the shark to swim past the divers.
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.
Companies object to being blamed for shark attacks, pointing out that lightning tends to strike humans more often than sharks bite humans. Their position is that further research needs to be done before banning practices such as chumming, which may alter natural behavior. One compromise is to only use chum in areas where whites actively patrol anyway, well away from human leisure areas. Also, responsible dive operators do not feed sharks. Only sharks that are willing to scavenge follow the chum trail and if they find no food at the end then the shark soon swims off and does 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. A single set of great white jaws can fetch a one-time price of up to £20,000. However, that is a fraction of the tourism value of a live shark, a more sustainable economic activity.
For example, the dive industry in Gansbaai, South Africa, consists of six boat operators with each boat guiding up to 30 people each day. With fees between £50 to £150 per person, a single live shark that visits each boat can create anywhere between £9,000 and £27,000 of revenue daily.