Longfin mako shark

Species of shark

The longfin mako shark (Isurus paucus) is a species of mackerel shark in the family Lamnidae, with a probable worldwide distribution in temperate and tropical waters. An uncommon species, it is typically lumped together under the name "mako" with its better known relative, the shortfin mako shark (I. oxyrinchus). The longfin mako is a pelagic species found in moderately deep water, having been reported to a depth of Growing to a maximum length of , the slimmer build and long, broad pectoral fins of this shark suggest that it is a slower and less active swimmer than the shortfin mako. Longfin mako sharks are predators that feed on small schooling bony fishes and cephalopods. Whether this shark is capable of elevating its body temperature above that of the surrounding water like the other members of its family is uncertain, though it possesses the requisite physiological adaptations. Reproduction in this species is aplacental viviparous, meaning the embryos hatch from eggs inside the uterus. In the later stages of development, the unborn young are fed nonviable eggs by the mother (oophagy). The litter size is typically two, but may be as many as eight. The longfin mako is of limited commercial value, as its meat and fins are of lower quality than those of other pelagic sharks; however, it is caught unintentionally in low numbers across its range. The International Union for Conservation of Nature has assessed this species as endangered due to its rarity, low reproductive rate, and continuing bycatch mortality. In 2019, alongside the shortfin mako, the IUCN listed the longfin mako as "Endangered".

The original description of the longfin mako was published in 1966 by Cuban marine scientist Darío Guitart Manday, in the scientific journal Poeyana, based on three adult specimens from the Caribbean Sea. An earlier synonym of this species may be Lamiostoma belyaevi, described by Glückman in 1964. However, the type specimen designated by Glückman consists of a set of fossil teeth that could not be confirmed as belonging to the longfin mako, thus the name paucus took precedence over belyaevi, despite being published later. The specific epithet paucus is Latin for "few", referring to the rarity of this species relative to the shortfin mako. The sister species relationship between the longfin and shortfin mako has been confirmed by several phylogenetic studies based on mitochondrial DNA. In turn, the closest relative of the two mako sharks is the great white shark (Carcharodon carcharias). Fossil teeth belonging to the longfin mako have been recovered from the Muddy Creek marl of the Grange Burn formation, south of Hamilton, Australia, and from Mizumani Group in Gifu Prefecture, Japan. Both deposits date to the Middle Miocene Epoch (15–11 million years ago (mya)). The oligo miocene fossil shark tooth taxon Isurus retroflexus may be the ancestor to or even conspecific with the Longfin Mako.

Widely scattered records suggest that the longfin mako shark has a worldwide distribution in tropical and warm temperate oceans; the extent of its range is difficult to determine due to confusion with the shortfin mako. In the Atlantic Ocean, it is known from the Gulf Stream off the East Coast of the United States, the Caribbean, and southern Brazil in the west, and from the Iberian Peninsula to Ghana in the east, possibly including the Mediterranean Sea and Cape Verde. In the Indian Ocean, it has been reported from the Mozambique Channel. In the Pacific Ocean, it occurs off Japan and Taiwan, northeastern Australia, a number of islands in the Central Pacific northeast of Micronesia, and southern California. The largest reported longfin mako was a female caught off Pompano Beach, Florida, in February 1984. Large specimens can scale over and can scale up to around This species has a slim, fusiform shape with a long, pointed snout and large eyes that lack nictitating membranes (protective third eyelids). Twelve to 13 tooth rows occur on either side of the upper jaw and 11–13 tooth rows are on either side of the lower jaw. The teeth are large and knife shaped, without serrations or secondary cusps; the outermost teeth in the lower jaw protrude prominently from the mouth. The gill slits are long and extend onto the top of head. Capture records off Florida suggest that during the winter, females swim into shallow coastal waters to give birth. Male and female sharks reach sexual maturity at lengths around and , respectively. Longfin mako were once significant in the Cuban longline fishery, comprising one sixth of the shark landings from 1971 to 1972; more recent data from this fishery are not available. The IUCN has assessed this species as "Vulnerable" due to its uncommonness, low reproductive rate, and susceptibility to shark fishing gear. It has also been listed under Annex I of the Convention on Migratory Species Migratory Shark Memorandum of Understanding. In the North Atlantic, stocks of the shortfin mako have declined 40% or more since the late 1980s, and concerns exist that populations of the longfin mako are following the same trend. In 2019, along with its relative the shortfin mako, the IUCN listed the longfin mako as "Endangered" due to continuing declines alongside 58 elasmobranch species.