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Swordfish (''Xiphias gladius''), also known as broadbills in some countries, are large, highly migratory predatory fish characterized by a long, flat, pointed 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. These fish are found widely in tropical and temperate parts of the Atlantic, Pacific, and Indian Oceans, and can typically be found from near the surface to a depth of , and exceptionally up to depths of 2,234 m. They commonly reach in length, and the maximum reported is in length and in weight.Gardieff, S.
Swordfish.
' Florida Museum of Natural History. Accessed 26 December 2011
They are the sole member of their family, Xiphiidae.


Taxonomy and etymology

The swordfish is named after its long pointed, flat bill, which resembles a
sword A sword is an edged, bladed weapon intended for manual cutting or thrusting. Its blade, longer than a knife or dagger, is attached to a hilt and can be straight or curved. A thrusting sword tends to have a straighter blade with a pointed ti ...
. The species name, ''Xiphias gladius'', derives from Greek (''xiphias'', "swordfish"), itself from (''xiphos'', "sword") and from Latin ("sword"). This makes it superficially similar to other billfish such as marlin, but upon examination, their physiology is quite different and they are members of different families. Several extinct genera are known, such as a large sized '' Xiphiorhynchus'' and '' Aglyptorhynchus''. Unlike modern taxa these have equally long lower jaws.


Description

They commonly reach in length, and the maximum reported is in length and in weight. The International Game Fish Association's all-tackle angling record for a swordfish was a specimen taken off Chile in 1953. Females are larger than males, and Pacific swordfish reach a greater size than northwest Atlantic and Mediterranean swordfish. They reach maturity at 4–5 years of age and the maximum age is believed to be at least 9 years. The oldest swordfish found in a recent study were a 16-year-old female and 12-year-old male. Swordfish ages are derived, with difficulty, from annual rings on fin rays rather than otoliths, since their otoliths are small in size. Swordfish are ectothermic animals; however, along with some species of sharks, they have special organs next to their
eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...
s to heat their eyes and brains. Temperatures of above the surrounding water temperature have been measured. The heating of the eyes greatly improves their vision, and consequently improves their ability to catch prey.Fritsches, K.A., Brill, R.W., and Warrant, E.J. 2005.
Warm Eyes Provide Superior Vision in Swordfishes.
' Current Biology 15: 55–58
Hopkin, M. (2005).

' Nature, 10 January 2005
Of the 25 000+ fish species, only 22 are known to have a mechanism to conserve heat. These include the swordfish, marlin, tuna, and some sharks.


Behavior and ecology


Movements and feeding

The popular belief of the "sword" being used as a spear is misleading. Their nose is more likely used to slash at its prey to injure the prey animal, to make for an easier catch. The use as an offensive spear in case of dangers against large sharks or animals is
under review Under may refer to: * "Under" (Alex Hepburn song), 2013 * "Under" (Pleasure P song), 2009 *Bülent Ünder (born 1949), Turkish footballer *Cengiz Ünder (born 1997), Turkish footballer *Marie Under Marie Under ( – 25 September 1980) was one o ...
. Mainly, the swordfish relies on its great speed and agility in the water to catch its prey. It is no doubt among the fastest fish, but the basis for the frequently quoted speed of is unreliable.ReefQuest Centre for Shark Research.
Haulin' Bass.
' Quote: ''"The 60 mph figure listed for the swordfish is based on a corrupted version of calculations made by Sir James Gray to estimate the impact speed necessary for a hypothetical 600-lb swordfish to embed its sword 3 feet in the timbers of ships, as has been known to occur; the figure seems to have entered the literature without question."'' Accessed 26 December 2011.
Research on related marlin (''
Istiophorus platypterus The Indo-Pacific sailfish (''Istiophorus platypterus'') is a sailfish native to the Indian and Pacific Oceans and is naturalized in the Atlantic where it has entered the Mediterranean Sea via the Suez Canal as a Lessepsian migrant. It is dark bl ...
'') suggest a maximum value of is more likely. Swordfish are not
schooling A school is an educational institution designed to provide learning spaces and learning environments for the teaching of students under the direction of teachers. Most countries have systems of formal education, which is sometimes compuls ...
fish. They swim alone or in very loose aggregations, separated by as much as from a neighboring swordfish. They are frequently found basking at the surface, airing their first dorsal fin. Boaters report this to be a beautiful sight, as is the powerful jumping for which the species is known. This jumping, also called breaching, may be an effort to dislodge pests, such as remoras or lampreys. Swordfish prefer water temperatures between , but have the widest tolerance among billfish, and can be found from . This highly migratory species typically moves towards colder regions to feed during the summer. Swordfish feed daily, most often at night, when they rise to surface and near-surface waters in search of smaller fish. During the day, they commonly occur to depths of and have exceptionally been recorded as deep as . Adults feed on a wide range of pelagic fish, such as
mackerel Mackerel is a common name applied to a number of different species of pelagic fish, mostly from the family Scombridae. They are found in both temperate and tropical seas, mostly living along the coast or offshore in the oceanic environment. ...
, barracudinas, silver hake, rockfish,
herring Herring are forage fish, mostly belonging to the family of Clupeidae. Herring often move in large schools around fishing banks and near the coast, found particularly in shallow, temperate waters of the North Pacific and North Atlantic Oceans, i ...
, and lanternfishes, but they also take
demersal fish Demersal fish, also known as groundfish, live and feed on or near the bottom of seas or lakes (the demersal zone).Walrond Carl . "Coastal fish - Fish of the open sea floor"Te Ara - the Encyclopedia of New Zealand. Updated 2 March 2009 They occ ...
,
squid True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...
, and crustaceans. In the northwestern Atlantic, a survey based on the stomach content of 168 individuals found 82% had eaten squid and 53% had eaten fish, including gadids,
scombrid The mackerel, tuna, and bonito family, Scombridae, includes many of the most important and familiar food fishes. The family consists of 51 species in 15 genera and two subfamilies. All species are in the subfamily Scombrinae, except the butterf ...
s,
butterfish Butterfish may refer to: * Stromateidae, found in coastal waters off the Americas, western Africa and in the Indo-Pacific * Sablefish The sablefish (''Anoplopoma fimbria'') is one of two members of the fish family Anoplopomatidae and the onl ...
, bluefish, and
sand lance A sand lance or sandlance is a fish belonging to the family Ammodytidae. Several species of sand lances are commonly known as "sand eels", though they are not related to true eels. Another variant name is launce, and all names of the fish are ...
. Large prey are typically slashed with the sword, while small are swallowed whole.


Threats and parasites

Almost 50 species of parasites have been documented in swordfish. In addition to remoras, lampreys, and cookiecutter sharks, this includes a wide range of invertebrates, such as tapeworms, roundworms, Myxozoans and
copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor) ...
s. A comparison of the parasites of swordfish in the Atlantic and in the Mediterranean indicated that some parasites, particularly Anisakis spp. larvae identified by genetic markers, could be used as biological tags and support the existence of a Mediterranean swordfish
stock In finance, stock (also capital stock) consists of all the shares by which ownership of a corporation or company is divided.Longman Business English Dictionary: "stock - ''especially AmE'' one of the shares into which ownership of a company ...
. Fully adult swordfish have few natural predators. Among marine mammals, killer whales sometimes prey on adult swordfish. The shortfin mako, an exceptionally fast species of shark, sometimes take on swordfish; dead or dying shortfin makos have been found with broken-off swords in their heads, revealing the danger of this type of prey.The Shark Trust. Juvenile swordfish are far more vulnerable to predation, and are eaten by a wide range of predatory fish. Intensive fishery may be driving swordfishes and sharks into harder competition for reduced amounts of prey and therefore pitting them to fight more. Human fishery is a major predator of swordfishes. The annual reported catch in 2019 of the North Atlantic swordfish amounted to a total of .


Breeding

In the North Pacific, batch spawning mainly occurs in water warmer than during the spring and summer, and year-round in the equatorial Pacific. In the North Atlantic, spawning is known from the
Sargasso Sea The Sargasso Sea () is a region of the Atlantic Ocean bounded by four currents forming an ocean gyre. Unlike all other regions called seas, it has no land boundaries. It is distinguished from other parts of the Atlantic Ocean by its charac ...
, and in water warmer than and less than deep. Spawning occurs from November to February in the South Atlantic off southern Brazil. Spawning is year-round in the Caribbean Sea and other warm regions of the west Atlantic. Large females can carry more eggs than small females, and between 1 million to 29 million eggs have been recorded. The pelagic eggs measure in diameter and days after fertilization, the embryonic development occurs. The surface-living and unique-looking larvae are long at hatching. The bill is evident when the larvae reach in length.


Fisheries

Swordfish were harvested by a variety of methods at small scale (notably harpoon fishing) until the global expansion of long-line fishing. They have been fished widely since ancient times in places such as the Strait of Messina, where they are still fished with traditional wooden boats called
felucca A felucca ( ar, فلوكة, falawaka, possibly originally from Greek , ) is a traditional wooden sailing boat used in the eastern Mediterranean—including around Malta and Tunisia—in Egypt and Sudan (particularly along the Nile and in protect ...
s and are part of the cuisine in that area. Swordfish are vigorous, powerful fighters. Although no unprovoked attacks on humans have been reported, swordfish can be very dangerous when harpooned. They have run their swords through the planking of small boats when hurt. In 2015, a Hawaiian fisherman was killed by a swordfish after attempting to spear the animal.


Recreational fishing

Recreational fishing has developed a subspecialty called swordfishing. Because of a ban on long-lining along many parts of seashore, swordfish populations are showing signs of recovery from the
overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in th ...
caused by long-lining along the coast. Various ways are used to fish for swordfish, but the most common method is deep-drop fishing, since swordfish spend most daylight hours very deep, in the deep scattering layer. The boat is allowed to drift to present a more natural bait. Swordfishing requires strong fishing rods and reels, as swordfish can become quite large, and it is not uncommon to use or more of weight to get the baits deep enough during the day, up to is common. Night fishing baits are usually fished much shallower, often less than . Standard baits are whole mackerel, herring, mullet, bonito, or squid; one can also use live bait. Imitation squids and other imitation fish lures can also be used, and specialized lures made specifically for swordfishing often have battery-powered or glow lights. Even baits are typically presented using glow sticks or specialized deepwater-proof battery operated lights.


As food

File:Unfinished cutting of swordfish, Cefalù, Sicily.jpg, Swordfish in seafood shop File:Marinated grill swordfish.jpeg, Marinated swordfish File:Fried Swordfish collar.jpg, Fried swordfish collars File:Swordfish in Limnionas, Kos, Greece (5653643083).jpg, Swordfish dish in Kos Swordfish are classified as oily fish. Many sources, including the United States Food and Drug Administration, warn about potential toxicity from high levels of
methylmercury Methylmercury (sometimes methyl mercury) is an organometallic cation with the formula . It is the simplest organomercury compound. Methylmercury is extremely toxic, and its derivatives are the major source of organic mercury for humans. It is a ...
in swordfish. The FDA recommends that young children, pregnant women, and women of child-bearing age not eat swordfish. The flesh of some swordfish can acquire an orange tint, reportedly from their diet of shrimp or other prey. Such fish are sold as "pumpkin swordfish", and command a premium over their whitish counterparts. Swordfish is a particularly popular fish for cooking. Since swordfish are large, meat is usually sold as steaks, which are often grilled. Swordfish meat is relatively firm, and can be cooked in ways more fragile types of fish cannot (such as over a grill on skewers). The color of the flesh varies by diet, with fish caught on the East Coast of
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
often being rosier.


Conservation status

In 1998, the US Natural Resources Defense Council and SeaWeb hired
Fenton Communications Fenton Communications is a public relations firm that was founded by David Fenton in 1982. They describe themselves as the "largest public interest communications firm in the country", and maintain offices in Washington, DC, Los Angeles, San Franci ...
to conduct an advertising campaign to promote their assertion that the swordfish population was in danger due to its popularity as a restaurant entree. The resulting "Give Swordfish a Break" promotion was wildly successful, with 750 prominent US chefs agreeing to remove North Atlantic swordfish from their menus, and also persuaded many supermarkets and consumers across the country. The advertising campaign was repeated by the national media in hundreds of print and broadcast stories, as well as extensive regional coverage. It earned the
Silver Anvil award Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical cond ...
from the Public Relations Society of America, as well as'' Time'' magazine's award for the top five environmental stories of 1998. Subsequently, the US
National Marine Fisheries Service The National Marine Fisheries Service (NMFS), informally known as NOAA Fisheries, is a United States federal agency within the U.S. Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) that is responsible for the stew ...
proposed a swordfish protection plan that incorporated the campaign's policy suggestions. Then-US President Bill Clinton called for a ban on the sale and import of swordfish and in a landmark decision by the federal government, of the Atlantic Ocean were placed off-limits to fishing as recommended by the sponsors. In the North Atlantic, the swordfish stock is fully rebuilt, with biomass estimates currently 5% above the target level. No robust stock assessments for swordfish in the northwestern Pacific or South Atlantic have been made, and data concerning stock status in these regions are lacking. These stocks are considered unknown and a moderate conservation concern. The southwestern Pacific stock is a moderate concern due to model uncertainty, increasing catches, and declining
catch per unit effort In fisheries and conservation biology, the catch per unit effort (CPUE) is an indirect measure of the abundance of a target species. Changes in the catch per unit effort are inferred to signify changes to the target species' true abundance. A decr ...
. Overfishing is likely occurring in the Indian Ocean, and fishing mortality exceeds the maximum recommended level in the Mediterranean, thus these stocks are considered of high conservation concern. In 2010, Greenpeace International added the swordfish to its seafood red list.


Extinct

*''
Xiphiorhynchoides ''Xiphiorhynchoides'' is an extinct genus of swordfish from the Oligocene of Austria. Its fossils have been found in the Paisslberg Formation in Tyrol, which is thought to represent a deepwater environment close to the shore. It is the best pre ...
''


In culture

*The swordfish (''Xiphias'') has been used by astronomers as another name for the constellation of Dorado.


References


Further reading

*


External links


Swordfish, Seafood Watch, Monterey Bay Aquarium


{{Authority control Cosmopolitan fish Oily fish Sport fish Hawaiian cuisine Greek cuisine Fish described in 1758 Extant Pliocene first appearances Taxa named by Carl Linnaeus