Longfin mako shark | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Chondrichthyes |
Subclass: | Elasmobranchii |
Subdivision: | Selachimorpha |
Order: | Lamniformes |
Family: | Lamnidae |
Genus: | Isurus |
Species: | I. paucus |
Binomial name | |
Isurus paucus Guitart-Manday, 1966 | |
Range of the longfin mako shark | |
Synonyms | |
Isurus alatusGarrick, 1967Lamiostoma belyaevi Glückman, 1964 Isurus oxyrinchus (non Rafinesque, 1810) misapplied Contents |
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 220 m (720 ft). Growing to a maximum length of 4.3 m (14 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 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". [3] [4] [5]
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. [6] The specific epithet paucus is Latin for "few", referring to the rarity of this species relative to the shortfin mako. [7]
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). [8] 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)). [9] [10] 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. [6]
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 (360–720 ft) and is rare at depths above 90 m (300 ft). Off New South Wales, most catches occur at a depth of 50–190 m (160–620 ft), in areas with a surface temperature around 20–24 °C (68–75 °F). [11]
The longfin mako is the larger of the two mako 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 (150 lb); females grow larger than males. [12] The largest reported longfin mako was a 4.3-metre-long (14 ft) female caught off Pompano Beach, Florida, in February 1984. [11] Large specimens can scale over 200 kg (440 lb). [13] 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. [6] [12]
The pectoral fins are as long or longer than the head, with a nearly straight front margin and broad 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 three to seven 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. [6] [12]
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 1,000-fold by the shortfin mako in fishery landings. [1] [6] The longfin mako's slender body and long, broad pectoral fins evoke the oceanic whitetip shark (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. [6] 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 environments, though whether the longfin mako is capable of the same is uncertain. [6]
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-metre-long (11 ft) female with the broken bill from a swordfish (Xiphias gladias) lodged in her abdomen was caught in the northeastern Indian Ocean; whether the shark was preying on swordfish as the shortfin mako does, or encountered the swordfish in some other aggressive context is not known. [6] [11] Adult longfin mako have no natural predators except for killer whales, while young individuals may fall prey to larger sharks. [12]
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-metre-long (11 ft) female pregnant with eight well-developed embryos was caught in the Mona Passage near Puerto Rico in January 1983. [11] The developing embryos are oophagous; once they deplete their supply of yolk, they sustain themselves by consuming large quantities of nonviable eggs ovulated by their mother. No evidence of sibling cannibalism is seen, as in the sand tiger shark (Carcharias taurus). The pups measure 97–120 cm (3.18–3.94 ft) long at birth, relatively larger than the young of the shortfin mako, and have proportionally longer heads and pectoral fins than the adults. [12] [14] Capture records off Florida suggest that during the winter, females swim into shallow coastal waters to give birth. [15] Male and female sharks reach sexual maturity at lengths around 2 m (6.6 ft) and 2.5 m (8.2 ft), respectively. [11]
No attacks on humans have been attributed to the longfin mako shark. [6] Nevertheless, its large size and teeth make it potentially dangerous. [7] 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 gillnets 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. [1] The carcasses may be processed into animal feed and fish meal, while the skin, cartilage, and jaws are also of value. [12] [15]
The most significant longfin mako catches are by Japanese tropical longline fisheries, and those sharks occasionally enter Tokyo fish markets. From 1987 to 1994, United States fisheries reported catches (discarded, as this species is worthless on the North American market) of 2–12 tons per year. [1] Since 1999, retention of this species has been prohibited by the U.S. National Marine Fisheries Service Fishery Management Plan for Atlantic sharks. [16] 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. [17] 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. [1] 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. [3] [4]
The shortfin mako shark, also known as the shortfin mako, blue pointer, or bonito shark, is a large mackerel shark. It is commonly referred to as the mako shark, as is the longfin mako shark. The shortfin mako can reach a size of 4 m (13 ft) in length and weigh 570 kg (1,260 lb). The species is classified as Endangered by the IUCN.
The Lamnidae are the family of mackerel sharks known as white sharks. They are large, fast-swimming predatory fish found in oceans worldwide, though prefer environments with colder water. The name of the family is formed from the Greek word lamna, which means "fish of prey", and was derived from the Greek legendary creature, the Lamia.
The porbeagle or porbeagle shark is a species of mackerel shark in the family Lamnidae, distributed widely in the cold and temperate marine waters of the North Atlantic and Southern Hemisphere. In the North Pacific, its ecological equivalent is the closely related salmon shark (L. ditropis). It typically reaches 2.5 m (8.2 ft) in length and a weight of 135 kg (298 lb); North Atlantic sharks grow larger than Southern Hemisphere sharks and differ in coloration and aspects of life history. Gray above and white below, the porbeagle has a very stout midsection that tapers towards the long, pointed snout and the narrow base of the tail. It has large pectoral and first dorsal fins, tiny pelvic, second dorsal, and anal fins, and a crescent-shaped caudal fin. The most distinctive features of this species are its three-cusped teeth, the white blotch at the aft base of its first dorsal fin, and the two pairs of lateral keels on its tail.
The snubnosed eel, Simenchelys parasitica, also known as the pug-nosed eel, slime eel, or snub-nose parasitic eel, is a species of deep-sea eel and the only member of its genus. Some authors classify it as the sole member of the subfamily Simenchelyinae of the family Synaphobranchidae, or cutthroat eels, while others place it in its own monotypic family, the Simenchelyidae. It is found in the Atlantic and Pacific Oceans, typically at a depth of 500–1,800 m (1,600–5,900 ft) near the bottom. Although typically a scavenger, it is better known for using its powerful jaws and teeth to burrow into larger fishes as a parasite. This species is harmless to humans and of no interest to fisheries. The generic name Simenchelys translates literally as "pug-nosed eel".
The bigeye thresher is a species of thresher shark, family Alopiidae, found in temperate and tropical oceans worldwide. Like the other thresher sharks, nearly half its total length consists of the elongated upper lobe of the tail fin. Its common name comes from its enormous eyes, which are placed in keyhole-shaped sockets that allow them to be rotated upward. This species can also be distinguished by a pair of deep grooves on the top of its head, from which its scientific name is derived.
The silvertip shark is a large species of requiem shark, in the family Carcharhinidae, with a fragmented distribution throughout the tropical Indian and Pacific Oceans. It is often encountered around offshore islands and coral reefs, and has been known to dive to a depth of 800 m (2,600 ft). The silvertip shark resembles a larger and bulkier grey reef shark, but can be easily identified by the prominent white margins on its fins. It attains a maximum length of 3 m (10 ft).
The common thresher, also known as Atlantic thresher, is the largest species of thresher shark, family Alopiidae, reaching some 6 m (20 ft) in length. About half of its length consists of the elongated upper lobe of its caudal fin. With a streamlined body, short pointed snout, and modestly sized eyes, the common thresher resembles the pelagic thresher. It can be distinguished from the latter species by the white of its belly extending in a band over the bases of its pectoral fins. The common thresher is distributed worldwide in tropical and temperate waters, though it prefers cooler temperatures. It can be found both close to shore and in the open ocean, from the surface to a depth of 550 m (1,800 ft). It is seasonally migratory and spends summers at lower latitudes.
The pelagic thresher is a species of thresher shark, family Alopiidae; this group of sharks is characterized by the greatly elongated upper lobes of their caudal fins. The pelagic thresher occurs in the tropical and subtropical waters of the Indian and Pacific Oceans, usually far from shore, but occasionally entering coastal habitats. It is often confused with the common thresher, even in professional publications, but can be distinguished by the dark, rather than white, color over the bases of its pectoral fins. The smallest of the three thresher species, the pelagic thresher typically measures 3 m (10 ft) long.
The crocodile shark is a species of mackerel shark and the only extant member of the family Pseudocarchariidae. A specialized inhabitant of the mesopelagic zone, the crocodile shark can be found worldwide in tropical waters from the surface to a depth of 590 m (1,940 ft). It performs a diel vertical migration, staying below a depth of 200 m (660 ft) during the day and ascending into shallower water at night to feed. Typically measuring only 1 m (3.3 ft) in length, the crocodile shark is the smallest living mackerel shark. It can be distinguished by its elongated cigar-shaped body, extremely large eyes, and relatively small fins.
The bigeye sand tiger is an extremely rare species of mackerel shark in the family Odontaspididae, with a possible worldwide distribution. A large, bulky species reaching at least 3.6 m (12 ft) in length, the bigeye sand tiger has a long bulbous snout, large orange eyes without nictitating membranes, and a capacious mouth with the narrow teeth prominently exposed. It can be distinguished from the similar smalltooth sand tiger by its teeth, which have only one lateral cusplet on each side, and by its uniformly dark brown color.
The bignose shark is a species of requiem shark, in the family Carcharhinidae. Distributed worldwide in tropical and subtropical waters, this migratory shark frequents deep waters around the edges of the continental shelf. It is typically found at depths of 90–430 m (300–1,410 ft), though at night it may move towards the surface or into shallower water. The bignose shark is plain-colored and grows to at least 2.7–2.8 m (8.9–9.2 ft) in length. It has a long, broad snout with prominent nasal skin flaps, and tall, triangular upper teeth. Its pectoral fins are long and almost straight, and there is a ridge on its back between the two dorsal fins.
The graceful shark or Queensland shark is a species of requiem shark, in the family Carcharhinidae, found in the tropical Indo-Pacific, from the Gulf of Aden to northern Australia. It is a midwater species that has been recorded to a depth of 50 m (160 ft). A stoutly built shark growing up to 1.7 m (5.6 ft) long, the graceful shark has a short, wedge-shaped snout, large, sickle-shaped pectoral fins and first dorsal fin, and black tips on most fins.
The spinner shark is a type of requiem shark, in the family Carcharhinidae, named for the spinning leaps it makes as a part of its feeding strategy. This species occurs in tropical and warm temperate waters worldwide, except for in the eastern Pacific Ocean. It is found from coastal to offshore habitats to a depth of 100 m (330 ft), though it prefers shallow water. The spinner shark resembles a larger version of the blacktip shark, with a slender body, long snout, and black-marked fins. This species can be distinguished from the blacktip shark by the first dorsal fin, which has a different shape and is placed further back, and by the black tip on the anal fin. It attains a maximum length of 3 m (9.8 ft).
The blackspot shark is a small species of requiem shark in the family Carcharhinidae found in the tropical Indo-West Pacific Ocean between latitudes 24°N and 30°S, from the surface to a depth around 40 m (130 ft). Its length is a little under one meter (yard) and it is not considered to be dangerous to humans. It feeds mainly on fish, crustaceans, and squid. This shark is also caught in small-scale fisheries for human consumption.
The night shark is a species of requiem shark, in the family Carcharhinidae, found in the temperate and tropical waters of the Atlantic Ocean. An inhabitant of the outer continental shelf and upper continental slope, this shark most commonly occurs at depths of 50–600 m (160–1,970 ft) and conducts a diel vertical migration, spending the day in deeper water and moving into shallower waters at night. Off northeastern Brazil, large numbers congregate around seamounts of varying depths. A slender, streamlined species, the night shark typically reaches a length of 2 m (6.6 ft). It can be identified by its long, pointed snout and large, green eyes, and is dark grayish blue or brown above and white below.
The false catshark or sofa shark is a species of ground shark in the family Pseudotriakidae, and the sole member of its genus. It has a worldwide distribution, and has most commonly been recorded close to the bottom over continental and insular slopes, at depths of 500–1,400 m (1,600–4,600 ft). Reaching 3.0 m (9.8 ft) in length, this heavy-bodied shark can be readily identified by its elongated, keel-like first dorsal fin. It has long, narrow eyes and a large mouth filled with numerous tiny teeth. It is usually dark brown in color, though a few are light gray.
The Australian weasel shark is an uncommon species of ground shark in the family Hemigaleidae. It inhabits shallow waters off northern Australia to a depth of 170 m (560 ft); smaller sharks frequent sand and seagrass habitat and shift to coral reefs as they grow older. A slim, drab species reaching a length of 1.1 m (3.6 ft), it has sickle-shaped fins with dark tips on the second dorsal fin and caudal fin upper lobe. Its upper teeth are broad with strong serrations only on the trailing edge. The lateral line along each side is prominent and exhibits a downward curve below the second dorsal fin.
The sand devil or Atlantic angel shark is a species of angelshark, family Squatinidae, native to the northwestern Atlantic Ocean. It occurs off the eastern United States, in the northern Gulf of Mexico, and possibly in parts of the Caribbean Sea. This bottom-dwelling shark is found in shallow inshore waters in summer and fall, and deep offshore waters in winter and spring. The sand devil's flattened body and enlarged pectoral and pelvic fins give it a ray-like appearance. There is a band of enlarged thorns running along the middle of its back. It is gray or brown in color, with scattered small dark spots. This species reaches 1.2–1.5 m (3.9–4.9 ft) in length.
The cloudy catshark is a common species of catshark, belonging to the family Scyliorhinidae. It is a bottom-dweller that inhabits rocky reefs in the northwestern Pacific Ocean, from the shore to a depth of 320 m (1,050 ft). Growing up to 50 cm (20 in) long, this small, slim shark has a narrow head with a short blunt snout, no grooves between the nostrils and mouth, and furrows on the lower but not the upper jaw. It is also characterized by extremely rough skin and coloration consisting of a series of dark brown saddles along its back and tail, along with various darker and lighter spots in larger individuals.
Isurus is a genus of mackerel sharks in the family Lamnidae, commonly known as the mako sharks. They are largely pelagic, fast predatory fish capable of swimming at speeds up to 50 km/h (31 mph).