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Friday 4 November 2011

Shortfin Mako Shark (Isurus oxyrinchus)

The shortfin mako shark is thought to be the fastest shark species. This shark is widely distributed throughout temperate and tropical oceans worldwide. Their speed, leaping ability and determination make the shortfin mako a popular game fish.
The name mako comes from the Maori word for “shark.” The shortfin mako’s genus, Isurus, means “equal tail,” in reference to its lunate tail fins. Its species name oxyrinchus means “sharp nose.”

Description:

Shortfin makos have a beautiful blue coloration on their back which lightens to a white ventral surface (belly). They grow to a maximum length of about 13 feet and weight of about 1,220 pounds. The largest shortfin mako ever caught was one off the coast of Massachusetts that weighed 1,221.

Classification:

Shortfin mako sharks are part of the group known as the mackerel sharks (Lamnidae, or lamnoids), which have five pairs of gill slits, two spineless dorsal fins, and an anal fin. They have large eyes, an extremely hydrodynamic body and lunate tail fins.
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Elasmobranchii
  • Order: Lamniformes
  • Family: Lamnidae
  • Genus: Isurus
  • Species: oxyrinchus

Distribution:

Shortfin makos are found in the pelagic zone in temperate and tropical oceans. Off North and South America, shortfin makos range from California to Chile in the Pacific Ocean and Canada to Brazil in the Atlantic, with sharks also found in the Gulf of Mexico, Caribbean Sea and off the Aleutian Islands.
In the eastern Atlantic, shortfin makos are found from Norway to South Africa. They are also found in the Mediterranean Sea, Indian Ocean and the western Pacific Ocean from Japan to New Zealand.

Feeding:

Shortfin makos have sharp, non-serrated teeth. They are active predators who eat other sharks, bony fish and squid. They are fast enough to prey upon the swordfish and sailfishes, which can reach speeds over 60 mph.
Researchers at the Scripps Institution of Oceanography found that the muscle structure propelling the mako's tail is similar to that of a tuna, another fast ocean predator. The shark, and tuna, have a high-performance muscle system formed by powerful red muscles that transfer energy to the fish's tail, allowing for quick, continuous travel (Read More).

Reproduction:

Shortfin makos are sexually mature at 4-6 years of age. Shortfin makos are ovoviviparous. In the womb, the developing fetus eat less developed or unfertilized eggs, which is known as oophagy. The female gives birth to the surviving 4-16 live young after a gestation period of 15-18 months.
Females are estimated to live up to 25 years.

Conservation:

Shortfin makos are listed as lower risk/near threatened on the IUCN Red List.
Because of the shortfin mako's popularity as a seafood and as a delicacy for shark fin soup, this species is subject to overfishing. Shortfin makos are a popular game fish and seafood species. According to NOAA, overfishing of this species occurs, but it is not considered to actually be overfished. Makos are also often caught as bycatch in the swordfish and tuna industries. They also reproduce slowly, making overfishing more of a concern.
Because of their aggressiveness, shortfin makos are considered a threat to humans. Attacks are relatively rare, though, since this species spends most of its time in the open ocean. They are known to be dangerous when caught by fishermen and may damage boats and injure fishermen after they are hooked.

Sources:

  • Waller, Geoffrey, ed. SeaLife: A Complete Guide to the Marine Environment. Smithsonian Institution Press. Washington, D.C. 1996.

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