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The Mackerel Shark

Mackerel sharks, genus Lamna, family Lamnidae

Lamna nasus Atlantic mackerel shark

It is also known as blue dog, porbeagle, bottle-nosed shark and Beaumaris shark. It belongs to the family of mackerel sharks (Lamnidae) of Lamniformes order; like any shark it has an elongate body with well-developed fins: two dorsal, two pectoral, anal and caudal fins.

The first dorsal fin, which is particularly large, is located in front of the pectoral fins, while the second one, which is smaller, is directly above the anal fin. The caudal fin is crescent-shaped. The mackerel sharks deep and stout body has a shark conical snout with five pairs of gill slits and powerful jaws with sharp teeth. The upper and the lower jaw have 60 large triangular teeth on each with every single one having a pair of smaller ones on both sides. Its eyes are black and relatively big lacking nictitating membrane.

The upper side of its body has bluish-grey coloration that can be of various shades. The underside is light, close to white. There are neither spots nor stripes on its body except for a small light-colored blotch at the first dorsal fin base.

The Atlantic mackerel shark usually reaches up to 2 meters at an average weight of 100 kg. Although, there is also evidence of the larger specimen weighing up to 200 kg and 3.7 meters long. The average lifespan of this shark species is 25-30 years.

Just as any shark type, mackerel sharks lead an active life and are in constant movement. When resting, they gravitate to the very bottom. Like all the other bony fishes, sharks do not have a swim bladder. So in order not to drown they must be on the move all the time from the very first minutes after birth. It is for this reason that dead sharks do not surface, but stay at the bottom of the ocean.

Like all the other representatives of this family, the Atlantic mackerel shark has a knack for temperature regulation. If necessary, it can change the temperature of its body within the frame of 10 degrees Celsius. The temperature rises by means of blood circulating through the special heat exchangers, which heat it up. This ability allows quick adaptation to cold sea water, as well as the significant increase in movement speed that helps sharks chase down their prey. In fact, such heat exchangers are common with almost every type of mackerel sharks including the famous mako shark the fastest shark in the world.

The habitat of the Atlantic mackerel shark

The Atlantic mackerel shark can be found in the waters of western Atlantic that range from Newfoundland, New Jersey and Canada to Argentina and even Brazil. Its eastern range extends to the waters of Iceland, the western part of the Barents Sea and even the coasts of South Africa. This shark species is also found in the Mediterranean.

The Atlantic mackerel shark lives in the open sea leading a pelagic life, as well as in the coastal waters of the islands and continents. The optimal water temperature for these sharks is no higher than +20 degrees Celsius. The habitat depth is 800 meters and up to the surface.

The primary diet of the mackerel shark is herrings. The experienced fishermen claim that it is the schools of herrings that it can be exactly spotted around. This shark species also feeds on tuna, sardines, mackerels and other schooling fish. Among the bottom dwellers it favors flounders, squids, skates, smaller sharks and all kinds of crustaceans.

The Atlantic mackerel sharks are active and highly mobile predators. They can almost always be seen in schools of 10-30 individuals at the very surface, where they swim with their dorsal fins above the water. They seal off schools of fish, huddle them in huge thick balls and swallow them up liberally.

The mackerel sharks often attack the fishing nets. Bustling with fish, the nets make them literally restless. The sharks rip the nets apart with great skill and the fish rushes out right into the predators jaws. What a feast! Fishermen had a chance to catch a shark right after such a feast and discovered about 60 fishes 15-20 cm in length inside.

Just as most of the known sharks, the Atlantic mackerel shark is ovoviviparous. The shark does not shed embryonated eggs into the water, but breeds them at the rear of the oviduct before birth. First appears the embryonic membrane, which is broken through after a while. At this point the embryo starts developing owing to the secretory products of the mother shark. The embryos are also strenuously feeding on the adjacent ovules.

The pregnancy lasts 8-9 months. The baby sharks are usually born during the warm seasons. They are the eumorphic individuals 50-70 cm in length. A female gives birth to 2-5 babies at a time.

The mating process of sharks is a pretty violent sight and receives little coverage so that the human notion of these animals is not spoiled completely. When courting a female, the male does not only behave aggressively, but also bites her intensely. Marine biologists can accurately identify an impregnated female by trails of blood and bruises on her body. In most cases one female is fertilized by several males.

The males reach puberty at the age of 8 years. By this time they are about 2 meters long. The females mature 4 years afterwards ranging from 2.3 to 2.6 meters.

The Atlantic mackerel shark is a favored target of fishing in many countries. It is caught by fishermen in Canada, Norway, Great Britain, Ireland and the United States in great numbers. This shark species is also a target of sport hunting.

Mackerel shark meat has great taste, thus being considered a delicacy. The only drawback is a pretty nasty distinctive smell, which is intrinsic to all elasmobranches. This smell stems from stakes and sharks having constant osmotic pressure, which is necessary for maintaining salt-water balance in the body, sustained by urea diluted in blood. Experienced chefs possess inside knowledge of how to cook shark meat properly. They cook it in a specific manner, which makes nasty smell go away.

Shark fins and liver are also of great value. The mackerel shark liver oil contains a variety of beneficial elements and is widely used in pharmacology. Its skin suits the production of wallets, belts, suitcases, handbags and other popular items. The cartilaginous skeleton goes into production of fish flour.

The Atlantic mackerel shark is among rather aggressive species and poses a potential threat to humans. Although the evidence holds only two cases of this predators aggression towards humans, both of which ended up with bites, one should definitely keep out of its way. It is no coincidence that its scientific name lamna stems from a Greek word meaning man-eating monster. This shark was the monster, which parents in Ancient Greece used to scare their unruly children with.

The Atlantic mackerel shark becomes gradually extinct from its usual habitat. The intensive fishing is detrimental to its population. Unfortunately, it can now rarely be seen in the Mediterranean, where it has been frequently spotted until recently.

The Atlantic mackerel shark today is under protection of ecologists as a precious species threatened with extinction. This species was assigned the status of Vulnerable by the International Union for Conservation of Nature and Natural Resources. In some countries of the European Union as well as in USA, Canada, Brazil and Australia it is forbidden to fish out mackerel sharks if only for the sake of their fins.

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