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The average annual bycatch off California is 1,800 kg (4,000 lb), though historically it has varied from 2.5 kg (5.5 lb) in 1976 to 9,500 kg (20,900 lb) in 1979. [16] Divers sometimes kill them for sport or to make jewelry out of their fin spines, which may be the cause of a decline in the numbers of horn sharks in the most intensely dived ...
Humans, 2 million years, even the ancestor of chimps and ourselves only takes it back to 6 million years ago, while sharks go back an incredible 450 million years.
Blacktip sharks showing curiosity towards divers has been reported, but they remain at a safe distance. Under most circumstances, these timid sharks are not regarded as highly dangerous to humans. However, they may become aggressive in the presence of food, and their size and speed invite respect. [3]
Through evolutionary time, sharks specifically have developed a suite of adaptive agonistic behaviours to communicate their intentions during such conflict. [1] Sharks display recognizable sequences of behaviour, which mimic the initial phases of their fight sequence, to signal their degree of agitation, along with their intent to fight.
Tracking studies in the tropical eastern Pacific and northern Gulf of Mexico have found that cruising silky sharks spend 99% of their time within 50 m (160 ft) of the surface, and 80–85% of their time in water with a temperature of 26–30 °C (79–86 °F); the pattern was constant regardless of day or night.
Kinsler says the reality of any day at the beach is: There are very often sharks around you, and you just don't know it. "People are in and around sharks when they're swimming just off the shore ...
Sand sharks are not known to attack humans. If a person were to provoke a sand shark, it may retaliate defensively. Sand sharks are generally not aggressive, but harass divers who are spearfishing. In North America, wreck divers regularly visit the World War II shipwrecks to dive with the sharks that make the wrecks their home. [8]
Nurse sharks are an important species for shark research. [3] They are robust and able to tolerate capture, handling, and tagging extremely well. [4] As inoffensive as nurse sharks may appear, they are ranked fourth in documented shark bites on humans, [5] likely due to incautious behavior by divers on account of the nurse shark's calm ...