Squid are the most important prey for blue sharks, but their diet includes other invertebrates, such as cuttlefish, blanket octopuses, and pelagic octopuses, as well as lobster, shrimp, crab, a large number of bony fishes (such as long-snouted lancetfish, snake mackerel and oilfish), small sharks, mammalian carrion and occasional sea birds (such as great shearwaters). Records from the Atlantic show a regular clockwise migration within the prevailing currents. It prefers water temperatures between 12 and 20 ☌ (54–68 ☏), but can be seen in water ranging from 7 to 25 ☌ (45–77 ☏). In the tropics, it spreads evenly between 20° N and 20° S. Its greatest Pacific concentrations occur between 20° and 50° North, but with strong seasonal fluctuations. Blue sharks are found off the coasts of every continent, except Antarctica. It lives as far north as Norway and as far south as Chile. In temperate seas it may approach shore, where it can be observed by divers while in tropical waters, it inhabits greater depths. The blue shark is an oceanic and epipelagic shark found worldwide in deep temperate and tropical waters from the surface to about 350 m (1,150 ft). Female blue sharks have adapted to the rigorous mating ritual by developing skin three times as thick as male skin. Courtship is believed to involve biting by the male, as mature specimens can be accurately sexed according to the presence or absence of bite scarring. Females mature at five to six years of age and males at four to five. The gestation period is between 9 and 12 months. They are viviparous, with a yolk-sac placenta, delivering 4 to 135 pups per litter. The blue shark is also ectothermic and it has a unique sense of smell. The heaviest reported weight for the species was 391 kg (862 lb). Occasionally, a female in excess of 3 m (9.8 ft) will weigh over 204 kg (450 lb). The blue shark is fairly elongated and slender in build and typically weighs from 27 to 55 kg (60 to 121 lb) in males and from 93 to 182 kg (205 to 401 lb) in large females. Occasionally, an outsized blue shark is reported, with one widely printed claim of a length of 6.1 m (20 ft), but no shark even approaching this size has been scientifically documented. Large specimens can grow to 3.8 m (12 ft) long. The male blue shark commonly grows to 1.82 to 2.82 m (6.0 to 9.3 ft) at maturity, whereas the larger females commonly grow to 2.2 to 3.3 m (7.2 to 10.8 ft) at maturity. Like many other sharks, blue sharks are countershaded: the top of the body is deep blue, lighter on the sides, and the underside is white. Understandably, some people want to get into the water either out of fascination or to get photographs, but it is truly dangerous to be around this carcass with so much shark activity,” agency official Jason Redull said.Blue sharks are light-bodied with long pectoral fins. “We don’t want anyone to get hurt if a shark swimming around the carcass mistakes them as food. The Hawaii Department of Land and Natural Resources warned people to stay away from the area where the carcass and Deep Blue have been seen. Ramsey and her team observe and identify sharks, and share that data with state and federal partners. Ramsey studies sharks, advocates for their conservation and leads cage-free shark diving tours. “Big pregnant females are actually the safest ones to be with - the biggest, oldest ones - because they’ve seen it all, including us,” Ramsey said. She said hunger and the need for added nutrients might have brought Deep Blue to Hawaii, where the waters are usually too warm for great whites. Ramsey told the newspaper that the shark was “shockingly wide” and could be pregnant. The Instagram post shows a diver swimming alongside Deep Blue. The Smithsonian says the average female great white shark measures just less than 5 meters, while males measure just less than 4 meters.ĭiver Mark Mohler said in a post on Instagram that he and fellow diver Kimberley Jeffries had confirmed the identity of the shark as Deep Blue. “She was just this big, beautiful gentle giant wanting to use our boat as a scratching post,” diver Ocean Ramsey told The Honolulu Star-Advertiser.ĭeep Blue is believed to be 6 meters long and at least 50 years old. The biggest great white shark on record is visiting the American island state of Hawaii, divers say.Ī group of divers monitoring the carcass of a sperm whale off the coast of Oahu say they have gone swimming with the massive predator, and that based on the size and the markings, the shark is known as “Deep Blue,” one of the largest great whites on record.
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