Longfin mako  (Isurus paucus)

Classified as Vulnerable (VU) on the IUCN Red List (1).

A little known, elusive shark, the longfin mako is a large, powerful, oceanic predator. With a long, pointed snout, a large dorsal fin and broad pectoral fins, the body of the longfin mako is streamlined for efficient movement through the water (3). Physically similar to the more common and closely related shortfin mako (Isurus oxyrinchus), the longfin mako is distinguished by conspicuous eyes, a conical snout, a more slender body and, as its common name suggests, comparatively longer fins (4). The mouth is armed with an array of sharply pointed, serrated teeth that protrude from the jaw, giving the shark a fearsome appearance (3). The longfin mako is a blue to blackish colour on the upperparts, fading to white on the underside, with a dusky colour under the head (5).     

Occurring in all tropical and warm waters worldwide, the longfin mako has a widespread range (3). However, due to the secretive nature of this species, it is rarely encountered, and consequently, its exact distribution is unclear (2). 

Very little is known about the habitat of the longfin mako, but most records of this pelagic shark are from the ocean surface in deep waters (2).

Despite a widespread range, surprisingly little is know about the biology and behaviour of this enigmatic shark. Slow and sluggish compared to the vigorous shortfin mako, the solitary longfin mako may be observed cruising slowly near the ocean’s surface (3) (6). However, when hunting it is capable of short bursts of rapid movement, primarily preying upon schools of small bony fish, but also taking squid and occasionally larger fish, such as swordfish. These high levels of activity are maintained by the possession of a specialised heat exchange circulatory system that enables the body to be warmer than the surrounding water (3).   

An ovoviviparous shark, developing offspring consume unfertilised eggs in the mother’s uterus, resulting in a litter of two to eight well developed live young, measuring between 90 and 95 centimetres at birth (3). It is possible that pregnant females move towards coastal nursing grounds to give birth in shallow waters that offer the developing young protection from predators (1).

Already uncommon throughout much of its range, there are serious concerns that longfin mako populations are further threatened by bycatch in tropical pelagic longline fisheries for tuna and swordfish. Driven by the demand for shark fins in Southeast Asia, where they are considered a delicacy, the fins of the longfin mako are removed, with the remaining carcass thrown overboard (7). Historically, the species was also targeted by shark fisheries in Cuba, where it was the sixth most commonly fished shark between 1971 and 1972, and in the United States, with annual catches between two and 12 tons from 1987 to 1997 (2) (3). Although the flesh is considered unpalatable in many countries, the longfin mako may also be captured using hook and line techniques and consumed fresh, frozen or dried and salted (3). As a direct consequence of such severe pressure, the longfin mako is suspected to have undergone a period of dramatic decline. The true extent of this is unclear, as it is often mistaken for the more common, similar looking shortfin mako. The species’ ability to recover from this decline is also severely limited by its comparatively slow reproduction rate (1).   

In the absence of international binding treaties for the management of sharks, including the regulation or outlawing of finning, the unsustainable capture of the longfin mako continues (8). The conservation of this oceanic species is further complicated by its cosmopolitan distribution, as any future conservation measures require international cooperation. However, careful fisheries management and measures to protect marine habitats, such as the establishment of no-fishing areas, will improve the future prospects for this majestic species (1).  

View information on this species at the UNEP World Conservation Monitoring Centre.

To find out more about the threats to sharks, see:

• The Shark Trust:
  http://www.sharktrust.org/
• The Shark Research Institute: 
  http://www.sharks.org/
• Conservation International: 
  http://www.conservation.org/learn/biodiversity/species/profiles/sharks/Pages/threats.aspx