Shortfin mako sharks

6/30/2016

They're fast. They're acrobats. They're deadly (to their prey). Meet the shortfin mako (Isurus oxyrinchus).

Believed to be the fastest of all sharks (with speed clocking in at 35 km/ph), and can propel themselves out of the water up to six metres. They're the definition of "grace" in the water... and what we're talking about in this bio.

They go by a number of names: "Atlantic mako," "blue pointer," "bonito shark," "mackerel porbeagle," and "sharpnose mackerel shark." Note that porbeagle sharks are a different species than the shortfin mako! The shortfin mako is not to be confused with the lesser known longfin mako (Isurus paucus).

The shortfin mako is a brilliant blue color, with a stark white underbelly; juveniles tend to have a black mark on their snout. Their razor-sharp teeth are like jagged nails, perfect for capturing their prey of choice: slippery fish! Fish include, but are not limited to, swordfish, tuna, mackerel, cod, and sea bass. These sharks also eat other sharks, such as blue sharks (Prionace glauca), grey sharks (Carcharhinus sp.) and hammerheads (Sphyrna sp.). Other prey items include squid and sea turtles.

Like the great white shark, they have a heat exchange circulatory system called the rete-mirable. These makos can get up to 4 m and weigh up to 570 kg! Surprisingly, little else is known of its biology. We know they are viviparous with yolk-sac, and that uterine cannibalism (known as oophagy) occurs.

They are a wide-ranging shark found in tropical and temperate waters throughout the world’s oceans; yes, New Zealand, we even have them down here! This species might migrate seasonally to warmer waters (a good idea I wish I could follow).

The shortfin mako is classified as Vulnerable (VU) by the IUCN, as they are frequently caught as bycatch by tuna and swordfish fisheries. Jaws, teeth, fins and liver oil are popular byproducts from these animals; Melissa has seen mako jaws for sale in seaside markets before! The U.S. National Marine Fisheries Service (NMFS) has included the shortfin mako on their list of managed pelagic sharks.

what are your thoughts on makos?

glossary

Bycatch: The part of a fishery’s catch that is made up of non-target species.
Cosmopolitan: Worldwide distribution.
Dorsal fin: Fin located on the back.
Fecundity: The natural capability to produce offspring.
Gestation: The period in which a fetus develops, beginning with fertilization and ends at birth.
IUCN: International Union for Conservation of Nature.
Teleost: Bony fishes.
Oophagy: Sometimes called "oviphagy;" when developing embryos feed on unfertilized eggs.
Pectoral fins: Fins located behind the gills on either side.
Pup: Give birth to baby sharks (pups).
Pups: Baby sharks.
Rete-mirable: Closely packed veins/arteries on either side of the shark that helps in conserving heat (especially in the stomach), making the shark warmer than the surrounding environment.
Viviparous with yolk-sac: Also known as aplacental viviparous and previously known as ovoviviparous/ovoviviparity; it is the production of eggs that are fertilised and hatch inside the female shark but the embryos lack a placental connection to the oviduct or uterus and so do not feed off the mother.