Salmon shark

The salmon shark, fish genus ditropis, was initial delineated  by Hubbs and Follett in 1947. The genus name fish genus is translated from Greek "lamna, -es" as a voracious fish. The species name ditropis is from the Greek "di" which means 2, and "tropis" which means keel. before 1947, salmon sharks were thought to be Lamna nasus sharks, Lamna nasus (then fish genus cornubica). though these species area unit closely connected, their ranges don't overlap. Salmon sharks area unit a Pacific species, associate degreed porbeagles area unit an Atlantic species.

Common Names

The salmon shark gets its name from one in all its prey things, the Pacific salmon (Oncorhyncus spp.). though it's thought-about to be one in all the most predators of Pacific salmon, the salmon shark is truly associate degree expedient feeder with a wide-ranging diet.

As mentioned higher than, the salmon shark was known as the Lamna nasus before it had been recognized as a separate species. It belongs to the Lamnidae, the mackerel sharks. In French, the salmon shark is understood as requin-taupe saumon, in Spanish, marrajo salmón, and in German, Pazifischer Heringshai. The salmon shark is plentiful in Japanese waters, and it's many native names in Japan, together with the japanese shark, nezumizame, mokazame, radukazame, and sakezame.

Geographical Distribution

The salmon shark happens solely within the coastal and oceanic waters of the Pacific Ocean. they will be found within the waters off Japan (including the ocean of Japan), off the western Pacific coasts of Asian nation, Asian nation, Russia (including the ocean of Okhotsk), and within the sea. The japanese portion of their vary is finite by the japanese seashore of the North American country, the U.S., and probably northern United Mexican States. as a result of the salmon shark solely happens within the Pacific, it will be simply distinguished from its relative the Lamna nasus, within the hemisphere, that solely happens within the Atlantic.

The salmon shark could be a primarily water species, however will be found in epipelagic, offshore, and coastal areas. It seems to like cold boreal to cool down temperate waters, however has been caught in water temperatures from thirty six.5° to 75°F (2.5° to 24°C). The species will be found at the surface to depths below five hundred foot (152 m), and has been photographed at 837 foot (255 m).

As is common among water cartilaginous fish species, the salmon shark makes long oceanic migrations over the course of the year. during this species, these migrations seem to be extremely correlate with
those of the water fish that it chiefly preys on, also like generative seasons. The salmon shark provides birth within the spring and doubtless mates within the summer or fall. Populations within the northwest Pacific breed in Japanese waters or in waters off the coast of Kamchatka and Sakhalin. In winter, once the water warms, they migrate north to a lot of distant feeding grounds within the ocean of Okhotsk, the sea, and therefore the ocean of Japan. within the spring, they come back south to Japanese waters, areas of the open ocean, and therefore the southern Kuril region, wherever the females offer birth.

Populations of the northeast Pacific perform an identical north-south migration within the waters off Calif., Oregon, Washington, Alaska, and Canada. The females migrate south within the spring to provide birth off American state and Calif., wherever a big range of neonates and young juveniles area unit found aground at that point once a year.

There seems to be a robust sexual segregation during this species with males dominating the western Pacific Ocean and females dominating the japanese Pacific Ocean. In fact, males and females in all probability don't type mixed teams, as catches of salmon sharks area unit nearly always dominated by one sex or the opposite. though trans-Pacific movements haven't been documented, they're suspected to occur, significantly throughout the pairing amount, that is perhaps in summer or fall.

Salmon shark populations additionally seem to be separate by size, with massive sharks usually inhabiting the a lot of northern reaches of the species' vary, and smaller sharks staying within the southern components. The larger, a lot of mature sharks area unit a lot of active in migrations, just like the ones delineated  higher than, whereas juveniles tend to stay in nursery areas till they reach concerning three.6 to 3.9 foot (110 to a hundred and twenty cm) long. The waters off the coast of Calif. seem to be a serious nursery ground for the northeast populations, with juveniles remaining there for one to 2 years once birth. The northwest salmon shark populations have nursery grounds within the open-water Pacific, Japanese waters, and therefore the southern Kuril region.

The salmon shark encompasses a serious cigar-shaped body with a brief blunt conic snout. The gill slits area unit massive. The caudal peduncle is powerfully keeled, with short secondary keels on the caudal base. The fin is crescent. the big initial fin encompasses a free rear tip. the tiny second dorsal and anal fins will pivot.

The salmon shark is usually mistaken for the man-eating shark (Carcharodon carcharias), however it will be distinguished by its shorter snout and therefore the presence of secondary keels on the caudal base (the man-eating shark has none).

The dorsal and lateral surfaces of the salmon shark area unit blue grey to black in color. Its fin is all dark, together with the rear tip. The ventral surface of the snout anterior to the mouth is additionally dark, however the remainder of the ventral surface of the body is white, typically with dusky blotches (in adults only) and white patches over the pectoral bases. The dark blotches also can be wont to distinguish the salmon shark from the man-eating shark.
The salmon shark encompasses a most total length of concerning ten foot (305 cm) and most weight of over 992 lbs (450 kg). There area unit unconfirmed  accounts of salmon sharks twelve.1 to 14.1 foot (370 to 430 cm), however these could have resulted from confusion with the larger man-eating shark. within the japanese Pacific Ocean, feminine salmon sharks will live to a minimum of twenty years, males to a minimum of twenty seven years.

In the western Pacific Ocean, males mature at concerning five.8 to 6.1 foot (177-186 cm) in total length and five years, and females mature at concerning vi.6 to 7.3 foot (200-223 cm) and 8-10 years. Salmon sharks within the japanese Pacific Ocean seem to possess a quicker rate of growth than those within the western Pacific Ocean associate degreed mature at an earlier age. within the japanese Pacific Ocean, males mature at concerning five.2 foot (158 cm) and 3-5 years, and females at vi.7 foot (205 cm) and 6-9 years. Also, females within the japanese Pacific Ocean area unit generally larger and heavier bodied than those within the western Pacific Ocean.

The salmon shark is mostly viewed as probably dangerous to man. However, although it's a comparatively massive shark and is said to infamously dangerous species just like the man-eating shark (Carcharodon carcharias) and therefore the mako (Isurus oxyrinchus), it's ne'er been completely known in any shark attack. The unsupported reports of this species area unit in all probability attributable to confusion with the man-eating shark. different have viewed teams of salmon sharks underwater with no reports of agonistic behavior by the sharks.

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