Isurus — the mako sharks

Characteristics

Mako sharks are built for speed. Typical adult lengths range from about 2.5 to 4.5 metres and larger individuals may be quite heavy. Distinctive features include a pointed snout, long gill slits, large crescent-shaped caudal (tail) fins and narrow, smooth-edged teeth suited for grasping fish. Like other members of Lamnidae, makos have the physiological ability to keep parts of their body warmer than the surrounding water, a trait that supports sustained high activity.

Species and distribution

The genus contains two living species: the shortfin mako and the longfin mako. The shortfin mako is the better-known and more widely encountered of the two; the longfin mako is rarer and typically found in more tropical or subtropical waters. Both species are pelagic, occupying open-ocean habitats, and they feed mainly on fast-moving fish and cephalopods. Reproduction is by internal gestation, resulting in relatively small litters of live young compared with many bony fishes.

Evolution and fossil history

Isurus has a long fossil record that documents its presence in ancient oceans and shows morphological continuity with earlier lamnid sharks. Fossil teeth similar to modern makos are commonly encountered in marine deposits, and these remains have helped scientists trace the genus’s development and its relationships with other large, predatory sharks.

Human interactions and conservation

Mako sharks are valued in recreational sport fishing for their speed and acrobatic behaviour when hooked. They are also taken in commercial fisheries, sometimes deliberately and often as bycatch on longlines and in gillnets. These pressures, together with their relatively slow reproductive rates, have led to population declines in many regions. Conservation measures and fishery regulations have been proposed or implemented in various jurisdictions to reduce mortality and allow stocks to recover.

Notable facts and distinctions

• Makos are among the fastest-swimming sharks, adapted for active predation in open water.
• Their teeth are slender and smooth-edged, unlike the serrated teeth of some other lamnids.
• There are only two extant species; more detailed species and population information can be found through resources that list the recognized species.