Longfin Mako

Longfin mako. Photo courtesy National Marine Fisheries Service
Longfin mako. Photo courtesy National Marine Fisheries Service

Isurus paucus

Named for its decidedly long and rounded pectoral fins, little is known about the life and habits of this slender relative of the shortfin mako and white shark.

Order – Lamniformes
Family – Lamnidae
Genus – Isurus
Species – paucus

Common Names

Importance to Humans

Because of its poorer quality meat, it isn’t highly sought after by recreational or commercial fishers, but demand for shark meat and shark fins does bring many to market (Compagno, 2001).

Danger to Humans

According to the International Shark Attack File, there have been no confirmed attacks on humans. However, there have been 8 incidents by unidentified Isurus spp. Though these are likely Isurus oxyrunchus (Shortfin Mako).

Conservation

The conservation status of this species is uncertain. Problems for the longfin mako include the rarity of this shark in most places (except perhaps the western Atlantic Ocean); limited knowledge of its biology; large maximum size; apparently lower fecundity than the shortfin mako; and occurrence as a limited but complementary bycatch of high-intensity oceanic fisheries targeting shortfin makos, other sharks, and pelagic scombroid fishes. These problems should arouse the concern of conservation and fisheries organizations, because of increased mortality of an uncommon or rare species due to finning and possibly capture trauma. It is thought to have a very low, minimum population with a doubling time of more than 14 years.

ICUN lists longfin makos as “Vulnerable” due to their increasing rarity due to fisheries bycatch and the shark fin trade (Amorim et al., 1998; Compagno, 2001).  Currently, there are no species-specific conservation measures in place.

> Check the status of the longfin mako at the IUCN website.

The IUCN is a global union of states, governmental agencies, and non-governmental organizations in a partnership that assesses the conservation status of species.

Geographical Distribution

World distribution map for the longfin mako
World distribution map for the longfin mako

I. paucus can be found in the Indian, Pacific, northwestern and eastern Atlantic Oceans. Regularly seen off the coast of Cuba, where it was first described (Compagno, 2001).

 

Habitat

There is little data available on the habitat and range of the species but this epipelagic shark this most often seen in tropical and temperate waters. As in other Lamnids, the longfin mako has counter current vascular heat exchange.  Allowing the musculature, eyes, brain and viscera to be heated. Often being seen at the surface, but specimen’s stomach contents include deepwater squids that have suggested a broad range of habitable depths for the species (Compagno, 2001; Castro, 2010).

Distinguishing Characteristics

Longfin mako (Isurus paucus). Illustration courtesy FAO, Species Identification and Biodata
Longfin mako (Isurus paucus). Illustration courtesy FAO, Species Identification and Biodata

1. Pectoral fins are as long or longer than head

2. Pectoral fins have broad tips

3. Caudal fin is lunate with single keel

4. Eyes are large

5. Teeth protrude from mouth

Biology

Distinctive Features

The longfin mako has a slender, torpedo-shaped body with a moderately long conical snout. Like other members of the family Lamnidae, I. paucus has elongated gill slits for more efficient gas exchange. The mouth is shorter than it is wide with the lower teeth extruding. The eyes are large, round and lateral. The spiracles are minute and scarcely perceivable. Pectoral fins are wide with a round tip, ranging between 22.5-30.7% of TL (equal or larger than the length of the head). The pelvic fins are short with concave posterior margins. The first dorsal fin is large with a light free rear tip. Both anal and the second dorsal fins are small. There are strong keels on the caudal peduncle and short secondary keels on the caudal base. The caudal fin is semi-lunate, and the upper lobe is not much larger than the lower one. The terminal caudal lobe is not prominent, and the subterminal notch is well distinguished (Compagno, 2001; Castro, 2010).

Shortfin Mako. Photo © Jeremy Stafford-Deitsch
Shortfin Mako. Photo © Jeremy Stafford-Deitsch

Similar species include: the shortfin mako (Isurus oxyrinchus), the blue shark (Prionace glauca), the white shark (Carcharodon carcharias), and the porbeagle (Lamna nasus). The longfin mako has proportionally larger fins and eyes than the shortfin mako. The blue shark lacks a strong caudal keel and a lunate caudal fin that are present in Isurus paucus. The white shark has a snout that is less narrow sporting serrated triangular teeth. The porbeagle’s caudal fin has small secondary caudal keels and teeth have lateral cusplets that are not present in the longfin mako (Compagno, 2001; Castro, 2010).

Coloration

The dorsolateral coloration is a dark slate-blue or gray-black, with a white ventral side. However, the underside of the snout and jaw is darker in adults and large juveniles, spreading to the origin of the pectoral fins. This dark color of the flanks extends ventrally onto abdomen in adults (Compagno, 2001; Castro, 2010).

Longfin mako jaw. Photo © Cathleen Bester/Florida Program for Shark Research
Longfin mako jaw. Photo © Cathleen Bester/Florida Program for Shark Research

Dentition
Teeth are narrow and triangular monocuspids with a wider base. Teeth have both smooth and cutting edges, and the first anterior tooth has a complete cutting edge. The first two teeth are wider and straight, the third symmetrical and with straight edges. There are 12 to 13 teeth on either side of the upper and lower jaws (Castro, 2010).

Dermal Denticles

Denticles are packed posterior margin is slightly “W” shaped. The denticles have 3 – 7 crests and are ellipse-shaped with a longer vertical than horizontal width (Castro, 2010).

Size, Age, and Growth

The maximum size is believed to be 426.7 cm (14 ft.) (Castro et al. 1999, Compagno 2001, Castro, 2010). While age at maturity is not known, females have been reported mature at > 300 cm (10.) and male at 229 cm (7.5 ft.) (Castro, 2010). The species lifespan is as of yet still unknown.

Longfin makos attain lengths up to 13.7 feet. Photo courtesy National Marine Fisheries Service
Longfin makos attain lengths up to 13.7 feet. Photo courtesy National Marine Fisheries Service

Food Habits

There is not much data on the food habits of the longfin mako, but it presumably feeds on schooling fishes and pelagic cephalopods (Compagno, 2001; Castro, 2010).

Reproduction

The longfin mako is ovoviviparous. The fetuses of the longfin mako are larger than those of the shortfin mako. Fetuses are believed to be cannibalistic in utero, consuming other eggs in the womb (oviphagy) (Compagno, 2001). The female give birth to 2-8 pups measuring 122-135 cm (4-4.5 ft.). (Castro, 2010; Compagno, 2001; Manday, 1975) Reproductive periods and gestation times are currently unknown.

Predators

Larger sharks may feed upon juvenile longfin makos. Adult longfin makos likely fall prey only to humans.

Longfin mako. Image courtesy FAO Vol. 4 Part 1, Sharks of the World
Longfin mako. Image courtesy FAO Vol. 4 Part 1, Sharks of the World

Parasites
There is no biological information available on common parasites of the longfin mako. It most likely shares parasites with other sharks in similar habitats.

Taxonomy

The longfin mako was originally described as Isurus paucus in 1966 by Guitart Manday. It has a synonym of Isurus alatus, Garrick, 1967. The genus name, Isurus, is translated from the Greek “isos” meaning equal and “oura” meaning tail.

Revised by: Tyler Bowling 2019

Prepared by: Trudy Wilson, and Travis Ford

 

References

Amorin, A.F., Arfelli, C.A. and Fagundes, L. 1998. Pelagic elasmobranchs caught by longliners off southern Brazil during 1974–97: an overview. Marine and Freshwater Research 49(7): 621–632.

Castro, J.I., 2010. The sharks of north America. Oxford University Press.

Castro, J.I., Woodley, C.M. and Brudek, R.L. 1999. A preliminary evaluation of the status of shark species. FAO Fisheries Technical Paper 380. FAO, Rome

Compagno, L.J.V. 2001. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Vol. 2. Bullhead, mackeral and carpet sharks (Heterodontiformes, Lamniformes and Orectolobiformes). FAO species catalogue for fisheries purposes. No. 1. Vol. 2. FAO, Rome.

Compagno, L.J., 1984. Sharks of the world: an annotated and illustrated catalogue of shark species known to date (No. QL 638.9. C65).

Gilmore, R.G. 1993. Reproductive biology of lamnoid sharks. Environmental Biology of Fishes 38: 95–114.

Manday, D.G., 1975. Las pesquerías pelágico-oceánicas de corto radio de acción en la región noroccidental de Cuba.