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The Blue Shark

The blue shark also known as blue dog and blue whaler inhabits all the oceans of our planet except the Arctic one. Being quite ubiquitous it can be met as within the open sea, so not far from the shore. Scientists estimate it as so-called pelagic fish what means it dwells in upper ocean: it’s conclusively established the blue shark never dives to the depths over 300 meters. These sharks are often watched by sailors, as they like going along with oceanic liners. Being as large in number as for example salmon or mackerel sharks, the blue dog can be met in tropic  as well as in the middle latitudes (there is data sometimes it is met even in the waters of Primorye).

The blue shark is attractive; it means you may define it without problem. The body of this shark is quite ‘slender’, porrect and pectoral fins are long. This ‘alive torpedo’ has elongated non-wide head with large eyes protected by the third eyelid (nictitant membrane). The blue shark uses – as you may guess - branchial respiration, there are gills with five gill openings at the each side of head. Near the nostrils of the fish there are small skin folds or nasal valves, and also narial passage, that is the hallmark of gray sharks, to whom it refers according to the standard classification.

Blue shark teeth that are on the upper jaw, have a triangular shape and are provided with sawed edges. Mandible teeth are awl-like and slightly sloped to the snout. Such a "design" allows a predator grip even slippery and large prey, while cutting off the pieces.

Long and narrow pectoral fins of the blue shark are sickle shaped, which is its characteristic feature along with elongated "skinny" body. On the back of the fish there are two fins, the front is much larger than the rear. In comparison with the porbeagle, the blue shark caudal peduncle is long and laterally flattened, but it has no keel bone at all. The tail fin is also very remarkable. Its lower blade is much smaller than the upper one, which has flag-like excision.

The color of the blue shark is obvious due to its name. The back of this ocean predator is really blue, and its shades vary from very dark to light blue. The sides are not rich in color, and the shark belly is almost white.

There is some evidence fishermen caught blue sharks of six feet length with nets, but there is no any document confirmation. The largest specimen of this fish, which was measured and weighed, had a length of 3.8 meters, and the mass of 400 pounds. At the same age blue sharks males are smaller than females.

Despite the fact the habitat of the blue shark is very wide, they often come in warm waters of the subtropical climate zone of our planet. They are most common in the Mediterranean, they often come see in the Aegean and Ionian Seas, in the northern part of the Adriatic Sea on the relative shallow depths.

Usually blue sharks swim slowly and even a few lazy, carefully exploring environments for the signs of prey. Once within sight there is a potential victim, they make sharp throws, covering an extremely impressive distance in a relatively short time. Reputable researchers argue blue sharks are second only to mako sharks in terms of rashness, and the speed that they develop is more than 40 km per hour.

Blue sharks are schooling fish, and the associations they form, can include several dozen of species. Their food intake basis is fish such as mackerel, tuna, herring, and squid. It often happens that satiated predators regurgitate the contents of their stomach and continue devour fish. This behavior is caused by the instinct to seek a stock in its own body for the sake of hard times, when the situation with food will not be favorable.

The behavior of the blue shark is characterized by the rapid change from sedentary and "drowsy" fish to a rashing and merciless creature. Scientists claim the blue sharks are sometimes subjected to food fever, and to be close to them at such times is extremely dangerous.

Blue sharks are not fussy about food and they even do not disdain carrion. They may eat any organic compounds, and sometimes they intentionally follow the ships to eat the waste discharged into the ocean.

This type of a shark is viviparous, and embryos obtain nutrients from the mother organism through the placental contact in the last months of their development. The length of newborn sharks is about fifty centimeters, while males reach sexual maturity it sizes of 1.9 to 2.8 meters, and females do from 2 to 3.5 meters. The blue shark females contain sperm for several months after mating. Pregnancy, which is followed by fertilization, lasts from 9 to 12 months. Simultaneously breed embryos number in its womb vary from 4 to 54. These fish breed outside the tropical climate belt, and one of their biggest "maternity" of the blue sharks is the Adriatic Sea, located close to the coastal area, bounded by Rimini and Puntade la Maestra resorts. You always have a chance to watch a lot of blue sharks pregnant females, as well as newly born sharks feeding on small fish.

The instance known a blue shark lifted on the research vessel board, bore 52 sharks, which were completely independent and full-fledged species ready to live independently. Scientists have placed several shark newborns in the aquarium, where they felt themselves perfectly.

It should be mentioned that blue sharks are considered dangerous to humans, and it is proved by grievous statistics. The fact that they are not fearful (unlike, for example, reef sharks), and bold enough to approach the scuba diving fans, especially in cases they are engaged in diving far away from the coast.

In those days, when whaling was not banned, blue sharks are often followed the vessels, on which these marine animals were carved, and picked up tripe. Sometimes whale carcasses were prepared in the water, and then marine predators had a real feast, they tortured whale corpse, even when people stabbed them.

The aggressiveness of blue sharks is disputable. Some believe that these fish attack anything that moves, while others, on the contrary, consider these predators lazy by nature and they reveal their hunting nature toward fish or squid only. As usual, the truth is the golden mean, and the attacks on people, who suffered a shipwreck or other disasters and fell into the open sea, occur more due to the fault of not blue, but other sharks.

These creatures are the subject of sport fishing, and they are often caught with fishing-rod nets According to statistics, the largest specimen was weighed nearly 206 pounds, and it was fished near the coast of Marthas' Vineyard town, Massachusetts (USA).

As the blue shark is not large, the fishermen use fishing rods of 44 kilograms type. Experience has shown that the best bait is a fresh mackerel, its carcass as well as thinly sliced ??strips. By the way, these predators have extremely sensitive olfactory organs, so the bait is almost always used to attract them to the hook with the bait.

It's worthy of note that during such fishing the blue shark males are often fished, with the weight of less 45 kg, and the length of five feet. Since they are fished, fishing sportsmen must release them into the wild. Narragansett Marine Laboratory of sport fisheries, Rhode Island, is the leading institution devoted to blue sharks research. Its staff is implementing a program of tagging fish to trace the routes of their migrations, as well as getting the information about their way of life.

According to the studies, the migratory route is quite interesting and challenging. Actually the blue shark is natural wanderers traveling through vast oceans of our spanless planet, that's why scientists are not surprised by the fact that the species, marked off near blessed Canary Islands, eventually fished in the South Atlantic Ocean. It happens that the blue shark marked ff the coast of New England, are fished later in the Pacific.

Blue shark meat is widely used for food, and as for gastronomy is considered as one of the most valuable. There is no ammonia, it can be eaten smoked, dried or dry-cured. Blue sharks fall under active fishery, and this led to a great decrease of the blue shark number. They become more rare in the world's oceans and fishermen fish them less often. By some estimates, the blue shark population declined by almost 80% in the last few years.

These predators fall under entire extinction. If the international community in the most the near future will not take effective measures for their preservation, it is quite possible that this species of fauna will be irretrievably lost. Therefore, the blue shark is listed in the Red Book.

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