Longfin mako
Encyclopedia
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 commonly 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 220 m (721.8 ft). Growing to a maximum length of 4.3 m (14.1 ft), 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 cephalopod
s. It is uncertain whether this shark is capable of elevating its body temperature above that of the surrounding water like the other members of its family, though it possesses the requisite physiological adaptation
s. Reproduction in this species is aplacental viviparous, meaning that the embryo
s hatch from eggs inside the uterus
. In the latter stages of development, the unborn young are fed non-viable 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; it is caught unintentionally in low numbers across its range. The International Union for Conservation of Nature (IUCN) has assessed this species as Vulnerable
due to its rarity, low reproductive rate, and continuing bycatch
mortality.
. 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, and 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 makos 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 Ma).
, it is known from the Gulf Stream
off the east coast of the United States
, Cuba
, 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
.
An inhabitant of the open ocean, the longfin mako generally remains in the upper mesopelagic zone during the day and ascends into the epipelagic zone at night. Off Cuba, it is most frequently caught at a depth of 110–220 m (360.9–721.8 ft) and is rare at depths above 90 m (295.3 ft). Off New South Wales
, Australia, most catches occur at a depth of 50–190 m (164–623.4 ft), in areas with a surface temperature around 20–24 °C (68–75.2 F).
, in February 1984. This species has a slim, fusiform shape with a long pointed snout and large eyes that lack nictating membranes (protective third eyelids). There are 12–13 tooth rows on either side of the upper jaw and 11–13 tooth rows 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 slit
s are long and extend onto the top of head.
The pectoral fins are as long or longer than the head, with a nearly straight front margin and broadly tips. The first dorsal fin
is large with a rounded apex, and is placed behind the pectoral fins. The second dorsal and anal fins are tiny. The caudal peduncle is expanded laterally into strong keels. The caudal fin is crescent-shaped, with a small notch near the tip of the upper lobe. The dermal denticles are elliptical, longer than wide, with 3–7 horizontal ridges leading to a toothed posterior margin. The coloration is dark blue to grayish black above and white below. The unpaired fins are dark except for a white rear margin on the anal fin; the pectoral and pelvic fins are dark above and white below with sharp gray posterior margins. In adults and large juveniles, the area beneath the snout, around the jaw, and the origin of the pectoral fins have dusky mottling.
(Carcharhinus longimanus) and the blue shark
(Prionace glauca), both slow-cruising sharks of upper oceanic waters. This morphological
similarity suggests that the longfin mako is less active than the shortfin mako, one of the fastest and most energetic sharks. Like the other members of its family, this species possesses blood vessel
countercurrent exchange
systems called the rete mirabilia (Latin for "wonderful net", singular rete mirabile) in its trunk musculature and around its eyes and brain. This system enables other mackerel sharks to conserve metabolic heat
and maintain a higher body temperature than their environment, though it is uncertain whether the longfin mako is capable of the same.
The longfin mako has large eyes and is attracted to cyalume sticks (chemical lights), implying that it is a visual hunter. Its diet consists mainly of small, schooling bony fishes and squids. In October 1972, a 3.4 m (11.2 ft) long female with the broken bill from a swordfish
(Xiphius gladias) lodged in her abdomen was caught in the northeastern Indian Ocean; it is unknown whether the shark was preying on swordfish as the shortfin mako does, or encountered the swordfish in some other aggressive context. Adult longfin makos likely have no natural predators, while young individuals may fall prey to larger sharks.
As in other mackerel sharks, the longfin mako is aplacental viviparous and typically gives birth to two pups at a time (one inside each uterus
), though a 3.3 m (10.8 ft) long female pregnant with eight well-developed embryos was caught in the Mona Passage
near Puerto Rico
in January 1983. The developing embryos are oophagous: once they deplete their supply of yolk, they sustain themselves by consuming large quantities of non-viable eggs ovulated
by their mother. There is no evidence of sibling cannibalism as in the sand tiger shark (Carcharias taurus). The pups measure 97–120 cm (3.2–3.9 ft) long at birth, relatively larger than the young of the shortfin mako, and have proportionally longer heads and pectoral fins than the adults. 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 of about 2 m (6.6 ft) and 2.5 m (8.2 ft) respectively.
No attacks on humans have been attributed to the longfin mako shark, and in fact this species is not known to have been observed underwater. Nevertheless, its large size and teeth make it potentially dangerous. This shark is caught, generally in low numbers, as bycatch
on longlines intended for tuna, swordfish, and other pelagic sharks, as well as in anchored gillnet
s and on hook-and-line. The meat is marketed fresh, frozen, or dried and salted, though it is considered to be of poor quality due to its mushy texture. The fins are also considered to be of lower quality for use in shark fin soup
, though are valuable enough that captured sharks are often finned
at sea. The carcasses may be processed into animal feed
and fishmeal, while the skin, cartilage, and jaws are also of value.
The most significant longfin mako catches are by Japanese tropical longline fisheries, and those sharks occasionally enter Tokyo
markets. From 1987–1994, United States
fisheries reported catches (discarded, as this species is worthless on the North American market) of 2–12 tons per year. Since 1999, retention of this species has been prohibited by the U.S. National Marine Fisheries Service
(NMFS) Fishery Management Plan (FMP) for Atlantic sharks. Longfin makos were once significant in the Cuban longline fishery, comprising a sixth of the shark landings from 1971–1972; more recent data from this fishery is not available. The International Union for Conservation of Nature (IUCN) has assessed this species as Vulnerable due to its uncommonness, low reproductive rate, and susceptibility to shark fishing gear. In the North Atlantic, stocks of the shortfin mako have declined 40% or more since the late 1980s, and there are concerns that populations of the longfin mako are following the same trend.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of mackerel shark
Lamniformes
Lamniformes is an order of sharks commonly known as mackerel sharks . It includes some of the most familiar species of sharks, such as the great white shark, as well as more unusual representatives, such as the goblin shark and the megamouth shark.Members of the order are distinguished by...
in the family Lamnidae
Lamnidae
Lamnidae is a family of sharks, commonly known as mackerel sharks or white sharks. They are large, fast-swimming sharks, found in oceans worldwide....
, with a probable worldwide distribution in temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
and tropical waters. An uncommon species, it is commonly lumped together under the name "mako
Mako
-Biology:*Isurus, the mako shark genus, consisting of two living and several fossil species:**Shortfin mako shark, Isurus oxyrinchus, the more common mako**Longfin mako shark, Isurus paucus, the rarer mako-Places:*Mako, Ethiopia, a town in Ethiopia...
" with its better-known relative, the shortfin mako shark
Shortfin mako shark
The shortfin mako shark, Isurus oxyrinchus , is a large mackerel shark. Along with the closely related longfin mako it is commonly referred to as a "mako shark".-Etymology:...
(I. oxyrinchus). The longfin mako is a pelagic species found in moderately deep water, having been reported to a depth of 220 m (721.8 ft). Growing to a maximum length of 4.3 m (14.1 ft), 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
Shoaling and schooling
In biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...
bony fishes and cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s. It is uncertain whether this shark is capable of elevating its body temperature above that of the surrounding water like the other members of its family, though it possesses the requisite physiological adaptation
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
s. Reproduction in this species is aplacental viviparous, meaning that the embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s hatch from eggs inside the uterus
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
. In the latter stages of development, the unborn young are fed non-viable eggs by the mother (oophagy
Oophagy
Oophagy , literally "egg eating", is the practice of embryos feeding on eggs produced by the ovary while still inside the mother's uterus. The word oophagy is formed from the classical Greek ᾠόν and classical Greek φᾱγεῖν ....
). The litter size is typically two but may be as many as eight. The longfin mako is of limited commercial value
Commercial fishing
Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often pursue fish far into the ocean under adverse conditions...
as its meat and fins are of lower quality than those of other pelagic sharks; it is caught unintentionally in low numbers across its range. The International Union for Conservation of Nature (IUCN) has assessed this species as Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
due to its rarity, low reproductive rate, and continuing bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
mortality.
Taxonomy and phylogeny
The original description of the longfin mako was published in 1966 by Cuban marine scientist Dario Guitart Manday, in the scientific journal Poeyana, based on three adult specimens from the Caribbean SeaCaribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....
. An earlier synonym
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
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
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
teeth that could not be confirmed as belonging to the longfin mako, and thus the name paucus took precedence over belyaevi despite being published later. The specific epithet paucus is Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for "few", referring to the rarity of this species relative to the shortfin mako.
The sister species relationship between the longfin and shortfin makos has been confirmed by several phylogenetic studies based on mitochondrial DNA
Mitochondrial DNA
Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...
. In turn, the closest relative of the two mako sharks is the great white shark
Great white shark
The great white shark, scientific name Carcharodon carcharias, also known as the great white, white pointer, white shark, or white death, is a large lamniform shark found in coastal surface waters in all major oceans. It is known for its size, with the largest individuals known to have approached...
(Carcharodon carcharias). Fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
teeth belonging to the longfin mako have been recovered from the Muddy Creek Marl of the Grange Burn formation, south of Hamilton
Hamilton, Victoria
Hamilton is a city in western Victoria, Australia. It is located at the intersection of the Glenelg Highway and the Henty Highway...
, Australia, and from Mizumani Group in Gifu Prefecture
Gifu Prefecture
is a prefecture located in the Chūbu region of central Japan. Its capital is the city of Gifu.Located in the center of Japan, it has long played an important part as the crossroads of Japan, connecting the east to the west through such routes as the Nakasendō...
, Japan. Both deposits date to the Middle Miocene
Middle Miocene
The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene....
epoch (15–11 Ma).
Distribution and habitat
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 OceanAtlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, it is known from the Gulf Stream
Gulf Stream
The Gulf Stream, together with its northern extension towards Europe, the North Atlantic Drift, is a powerful, warm, and swift Atlantic ocean current that originates at the tip of Florida, and follows the eastern coastlines of the United States and Newfoundland before crossing the Atlantic Ocean...
off the east coast of the United States
East Coast of the United States
The East Coast of the United States, also known as the Eastern Seaboard, refers to the easternmost coastal states in the United States, which touch the Atlantic Ocean and stretch up to Canada. The term includes the U.S...
, Cuba
Cuba
The Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...
, and southern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
in the west, and from the Iberian Peninsula
Iberian Peninsula
The Iberian Peninsula , sometimes called Iberia, is located in the extreme southwest of Europe and includes the modern-day sovereign states of Spain, Portugal and Andorra, as well as the British Overseas Territory of Gibraltar...
to Ghana
Ghana
Ghana , officially the Republic of Ghana, is a country located in West Africa. It is bordered by Côte d'Ivoire to the west, Burkina Faso to the north, Togo to the east, and the Gulf of Guinea to the south...
in the east, possibly including the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
and Cape Verde
Cape Verde
The Republic of Cape Verde is an island country, spanning an archipelago of 10 islands located in the central Atlantic Ocean, 570 kilometres off the coast of Western Africa...
. In the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
, it has been reported from the Mozambique Channel
Mozambique Channel
The Mozambique Channel is a portion of the Indian Ocean located between the island nation of Madagascar and southeast Africa, primarily the country of Mozambique. It was a World War II clashpoint during the Battle of Madagascar...
. In the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, it occurs off Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
and Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, northeastern Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, a number of islands in the Central Pacific northeast of Micronesia
Micronesia
Micronesia is a subregion of Oceania, comprising thousands of small islands in the western Pacific Ocean. It is distinct from Melanesia to the south, and Polynesia to the east. The Philippines lie to the west, and Indonesia to the southwest....
, and southern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
.
An inhabitant of the open ocean, the longfin mako generally remains in the upper mesopelagic zone during the day and ascends into the epipelagic zone at night. Off Cuba, it is most frequently caught at a depth of 110–220 m (360.9–721.8 ft) and is rare at depths above 90 m (295.3 ft). Off New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, Australia, most catches occur at a depth of 50–190 m (164–623.4 ft), in areas with a surface temperature around 20–24 °C (68–75.2 F).
Description
The longfin mako is the larger of the two makos and the second-largest species in its family (after the great white), reaching upwards of 2.5 m (8.2 ft) in length and weighing over 70 kg (154.3 lb); females grow larger than males. The largest reported longfin mako was a 4.3 m (14.1 ft) long female caught off Pompano Beach, FloridaFlorida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, in February 1984. This species has a slim, fusiform shape with a long pointed snout and large eyes that lack nictating membranes (protective third eyelids). There are 12–13 tooth rows on either side of the upper jaw and 11–13 tooth rows 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 slit
Gill slit
Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of Cartilaginous fish such as sharks, rays, sawfish, and guitarfish. Most of these have five pairs, but a few species have 6 or 7 pairs...
s are long and extend onto the top of head.
The pectoral fins are as long or longer than the head, with a nearly straight front margin and broadly tips. The first dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
is large with a rounded apex, and is placed behind the pectoral fins. The second dorsal and anal fins are tiny. The caudal peduncle is expanded laterally into strong keels. The caudal fin is crescent-shaped, with a small notch near the tip of the upper lobe. The dermal denticles are elliptical, longer than wide, with 3–7 horizontal ridges leading to a toothed posterior margin. The coloration is dark blue to grayish black above and white below. The unpaired fins are dark except for a white rear margin on the anal fin; the pectoral and pelvic fins are dark above and white below with sharp gray posterior margins. In adults and large juveniles, the area beneath the snout, around the jaw, and the origin of the pectoral fins have dusky mottling.
Biology and ecology
The biology of the longfin mako is little-known; it is somewhat common in the western Atlantic and possibly the central Pacific, while in the eastern Atlantic it is rare and outnumbered over a thousandfold by the shortfin mako in fishery landings. The longfin mako's slender body and long, broad pectoral fins evoke the oceanic whitetip sharkOceanic whitetip shark
The oceanic whitetip shark, Carcharhinus longimanus, is a large pelagic shark inhabiting tropical and warm temperate seas. Its stocky body is most notable for its long, white-tipped, rounded fins....
(Carcharhinus longimanus) and the blue shark
Blue shark
The blue shark is a species of requiem shark, family Carcharhinidae, that inhabits deep waters in the world's temperate and tropical oceans. Preferring cooler waters, blue sharks migrate long distances, for example from New England to South America. Although generally lethargic, they can move very...
(Prionace glauca), both slow-cruising sharks of upper oceanic waters. This morphological
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
similarity suggests that the longfin mako is less active than the shortfin mako, one of the fastest and most energetic sharks. Like the other members of its family, this species possesses blood vessel
Blood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...
countercurrent exchange
Countercurrent exchange
Countercurrent exchange is a mechanism occurring in nature and mimicked in industry and engineering, in which there is a crossover of some property, usually heat or some component, between two flowing bodies flowing in opposite directions to each other. The flowing bodies can be liquids, gases, or...
systems called the rete mirabilia (Latin for "wonderful net", singular rete mirabile) in its trunk musculature and around its eyes and brain. This system enables other mackerel sharks to conserve metabolic heat
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
and maintain a higher body temperature than their environment, though it is uncertain whether the longfin mako is capable of the same.
The longfin mako has large eyes and is attracted to cyalume sticks (chemical lights), implying that it is a visual hunter. Its diet consists mainly of small, schooling bony fishes and squids. In October 1972, a 3.4 m (11.2 ft) long female with the broken bill from a swordfish
Swordfish
Swordfish , also known as broadbill in some countries, are large, highly migratory, predatory fish characterized by a long, flat bill. They are a popular sport fish of the billfish category, though elusive. Swordfish are elongated, round-bodied, and lose all teeth and scales by adulthood...
(Xiphius gladias) lodged in her abdomen was caught in the northeastern Indian Ocean; it is unknown whether the shark was preying on swordfish as the shortfin mako does, or encountered the swordfish in some other aggressive context. Adult longfin makos likely have no natural predators, while young individuals may fall prey to larger sharks.
As in other mackerel sharks, the longfin mako is aplacental viviparous and typically gives birth to two pups at a time (one inside each uterus
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
), though a 3.3 m (10.8 ft) long female pregnant with eight well-developed embryos was caught in the Mona Passage
Mona Passage
The Mona Passage is a strait that separates the islands of Hispaniola and Puerto Rico. The Mona Passage connects the Atlantic Ocean to the Caribbean Sea, and is an important shipping route between the Atlantic and the Panama Canal....
near Puerto Rico
Puerto Rico
Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...
in January 1983. The developing embryos are oophagous: once they deplete their supply of yolk, they sustain themselves by consuming large quantities of non-viable eggs ovulated
Ovulation
Ovulation is the process in a female's menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum . Ovulation also occurs in the estrous cycle of other female mammals, which differs in many fundamental ways from the menstrual cycle...
by their mother. There is no evidence of sibling cannibalism as in the sand tiger shark (Carcharias taurus). The pups measure 97–120 cm (3.2–3.9 ft) long at birth, relatively larger than the young of the shortfin mako, and have proportionally longer heads and pectoral fins than the adults. 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
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
at lengths of about 2 m (6.6 ft) and 2.5 m (8.2 ft) respectively.
Human interactions
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
on longlines intended for tuna, swordfish, and other pelagic sharks, as well as in anchored gillnet
Gillnet
Gillnetting is a common fishing method used by commercial and artisanal fishermen of all the oceans and in some freshwater and estuary areas. The gillnet also is used by fisheries scientists to monitor fish populations. Because gillnets can be so effective their use is closely monitored and...
s and on hook-and-line. The meat is marketed fresh, frozen, or dried and salted, though it is considered to be of poor quality due to its mushy texture. The fins are also considered to be of lower quality for use in shark fin soup
Shark fin soup
Shark fin soup is a popular soup item of Chinese cuisine usually served at special occasions such as weddings and banquets, or as a luxury item in Chinese culture. The shark fins provide texture while the taste comes from the other soup ingredients.There is controversy over the practice of shark...
, though are valuable enough that captured sharks are often finned
Shark finning
Shark finning refers to the removal and retention of shark fins and the discarding of the rest of the fish. Shark finning takes place at sea so the fishers only have to transport the fins.Shark finning is widespread, and largely unmanaged and unmonitored...
at sea. The carcasses may be processed into animal feed
Compound feed
Compound feeds are feedstuffs that are blended from various raw materials and additives. These blends are formulated according to the specific requirements of the target animal...
and fishmeal, while the skin, cartilage, and jaws are also of value.
The most significant longfin mako catches are by Japanese tropical longline fisheries, and those sharks occasionally enter Tokyo
Tokyo
, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...
markets. From 1987–1994, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
fisheries reported catches (discarded, as this species is worthless on the North American market) of 2–12 tons per year. Since 1999, retention of this species has been prohibited by the U.S. National Marine Fisheries Service
National Marine Fisheries Service
The National Marine Fisheries Service is a United States federal agency. A division of the National Oceanic and Atmospheric Administration and the Department of Commerce, NMFS is responsible for the stewardship and management of the nation's living marine resources and their habitat within the...
(NMFS) Fishery Management Plan (FMP) for Atlantic sharks. Longfin makos were once significant in the Cuban longline fishery, comprising a sixth of the shark landings from 1971–1972; more recent data from this fishery is not available. The International Union for Conservation of Nature (IUCN) has assessed this species as Vulnerable due to its uncommonness, low reproductive rate, and susceptibility to shark fishing gear. In the North Atlantic, stocks of the shortfin mako have declined 40% or more since the late 1980s, and there are concerns that populations of the longfin mako are following the same trend.