Swordfish | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Order: | Carangiformes |
Suborder: | Menoidei |
Family: | Xiphiidae Swainson, 1839 |
Genus: | Xiphias Linnaeus, 1758 |
Species: | X. gladius |
Binomial name | |
Xiphias gladius | |
Global distribution of swordfish in blue | |
Synonyms [4] | |
The swordfish (Xiphias gladius), also known as the broadbill [5] 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 550 m (1,800 ft), and exceptionally up to depths of 2,234 m. [3] They commonly reach 3 m (10 ft) in length, and the maximum reported is 4.55 m (14 ft 11 in) in length and 650 kg (1,430 lb) in weight. [4] [6]
The swordfish is named after its long pointed, flat bill, which resembles a sword. The species name, Xiphias gladius, derives from Greek ξιφίας (xiphias, "swordfish"), itself from ξίφος (xiphos, "sword") and from Latin gladius ("sword"). [6] 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. [8]
Several extinct genera are known, such as a large sized Xiphiorhynchus and Aglyptorhynchus . [9] Unlike modern taxa these have equally long lower jaws.[ citation needed ]
They commonly reach 3 m (10 ft) in length, and the maximum reported is 4.55 m (14 ft 11 in) in length and 682 kg (1,500 lb) in weight. [4] [6] [10] The International Game Fish Association's all-tackle angling record for a swordfish was a 536 kg (1,182 lb) specimen taken off Chile in 1953. [3] Females are larger than males, and Pacific swordfish reach a greater size than northwest Atlantic and Mediterranean swordfish. [6]
They reach maturity at 4–5 years of age and the maximum age is believed to be at least 9 years. [6] 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. [11]
Swordfish are ectothermic animals. Along with some species of sharks, they have special organs next to their eyes called heater cells which function to heat their eyes and brains. [12] Their eyes are heated to temperatures measured between 10 and 15 °C (18 and 27 °F) above the surrounding water temperature; this heating greatly improves their vision and, consequently, their predatory efficacy. [13] [14]
The swordfish is one of 22 species of fish – including the marlin, tuna, and some sharks – known to have a heat-conservation mechanism. [13] [14]
The popular image of the swordfish skewering its prey with its nose is based on little evidence. In a typical environment, swordfish most likely use their noses to slash at prey and inflict weakening injuries. [6] The hypothesis that they may use their noses as spears in a defensive capacity against sharks and other predators is still under review.
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 100 km/h (60 mph) is unreliable. [15] Research on related marlin ( Istiophorus platypterus ) suggest a maximum value of 36 km/h (22 mph) is more likely. [16]
Swordfish are not schooling fish. They swim alone or in very loose aggregations, separated by as much as 10 m (35 ft) 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.[ citation needed ]
Swordfish prefer water temperatures between 18 and 22 °C (64 and 72 °F), [3] but have the widest tolerance among billfish, and can be found from 5 to 27 °C (41 to 81 °F). [6] This highly migratory species typically moves towards colder regions to feed during the summer. [6] 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 550 m (1,800 ft; 300 fathoms) and have exceptionally been recorded as deep as 2,878 m (9,442 ft; 1,574 fathoms). [3] Adults feed on a wide range of pelagic fish, such as mackerel, barracudinas, silver hake, rockfish, herring, and lanternfishes, but they also take demersal fish, squid, and crustaceans. [4] [6] 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, scombrids, butterfish, bluefish, and sand lance. [17] Large prey are typically slashed with the sword, while small are swallowed whole. [6]
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 copepods. [6] [18] 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. [19]
Fully adult swordfish have few natural predators. Among marine mammals, killer whales sometimes prey on adult swordfish. [6] It is believed that sperm whales may also prey on swordfish on rare occasions. [20] 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. [21] Juvenile swordfish are far more vulnerable to predation, and are eaten by a wide range of predatory fish. [6] [22] Intensive fishery may be driving swordfishes and sharks into harder competition for reduced amounts of prey and therefore pitting them to fight more. [22]
Human fishery is a major predator of swordfishes. The annual reported catch in 2019 of the North Atlantic swordfish amounted to a total of 1.3 million kilograms (2.9 million pounds). [23]
In the North Pacific, batch spawning mainly occurs in water warmer than 24 °C (75 °F) during the spring and summer, and year-round in the equatorial Pacific. [3] In the North Atlantic, spawning is known from the Sargasso Sea, [24] and in water warmer than 23 °C (73 °F) and less than 75 m (246 ft; 41 fathoms) deep. [3] Spawning occurs from November to February in the South Atlantic off southern Brazil. [3] Spawning is year-round in the Caribbean Sea and other warm regions of the west Atlantic. [6]
Large females can carry more eggs than small females, and between 1 million and 29 million eggs have been recorded. [3] The pelagic eggs measure 1.6–1.8 mm (1⁄16–5⁄64 in) in diameter and 2+1⁄2 days after fertilization, the embryonic development occurs. [24] [6] The surface-living and unique-looking larvae are 4 mm (5⁄32 in) long at hatching. [4] [6] The bill is evident when the larvae reach 1 cm (3⁄8 in) in length. [4]
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 feluccas and are part of the cuisine in that area. [26] [27] [28]
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. [29]
This section needs additional citations for verification .(February 2010) |
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 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 2.5 kg (5 lb) or more of weight to get the baits deep enough during the day, up to 460 m (1,500 ft) is common. [30] Night fishing baits are usually fished much shallower, often less than 90 m (300 ft; 50 fathoms). 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.
Swordfish are classified as oily fish. [31] Many sources, including the United States Food and Drug Administration, warn about potential toxicity from high levels of methylmercury in swordfish. [32] [33] The FDA recommends that young children, pregnant women, and women planning to become pregnant not eat swordfish. [34]
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.[ citation needed ]
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 often being rosier.
A dispute exists as to whether swordfish should be considered a kosher fish according to the laws of kashrut. Standard Orthodox opinion is that swordfish is not kosher, while Conservative Judaism does consider swordfish kosher. All kosher fish must have both fins and scales. The Talmud and the Tosefta are believed by some to present swordfish ("achsaftias") as an example of a kosher fish without scales because swordfish are born with scales they later shed once attaining a length of about 1 meter. The 17th-century Turkish Sephardi halakhic authority Rabbi Chaim ben Yisrael Benvenisti wrote that "It is a widespread custom among all Jews to eat the fish with the sword, known in vernacular as fishei espada, even though it does not have any scales. Because it is said that when it comes out of the water, due to its anger, it shakes and throws off its scales." A 1933 list of kosher fish published by the Agudas HaRabbonim includes swordfish. The following year, Rabbi Yosef Kanowitz published the same list of kosher fish with swordfish still included. Swordfish was widely considered kosher by halakhic authorities until the 1950s. Orthodox opinion began to shift in 1951, when Rabbi Moshe Tendler examined swordfish and decided it was not kosher due to the lack of scales. Tendler's opinion provoked strong debate among halakhic authorities during the 1960s. [35] [36] Among Mediterranean Jews there was a longstanding minhag of considering swordfish kosher. Swordfish was and possibly still is consumed by Jews in Italy, Turkey, Gibraltar, Morocco, Tunisia, and England. Due to Tendler's opinion, swordfish are generally not considered kosher by Orthodox Jews in the United States and Israel. [37]
In 1998, the U.S. Natural Resources Defense Council and SeaWeb hired Fenton Communications to conduct an advertising campaign to promote their assertion that the swordfish population was in danger due to its popularity as a restaurant entree. [38]
The resulting "Give Swordfish a Break" promotion was wildly successful, with 750 prominent U.S. 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 from the Public Relations Society of America, as well as Time magazine's award for the top five environmental stories of 1998.
Subsequently, the U.S. National Marine Fisheries Service 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, 343,600 km2 (132,670 sq mi) 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. [39] 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. 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. [40]
In 2010, Greenpeace International added the swordfish to its seafood red list. [41]
In 2007, a fisherman died after being attacked by a swordfish which pierced his eye and its bill penetrated into the man's skull. [42]
In 2024, Giulia Manfrini, an Italian surfer died in a rare incident after being struck by a swordfish while surfing off the coast of West Sumatra, Indonesia. [43]
The swordfish (Xiphias) has been used by astronomers as another name for the constellation of Dorado. [44]
The word swordfish is used as a password in the 1932 Marx Brothers film Horse Feathers . It has since appeared as a password in many films, television series, books, and videogames. [45]
The bluefish is the only extant species of the family Pomatomidae. It is a marine pelagic fish found around the world in temperate and subtropical waters, except for the northern Pacific Ocean. Bluefish are known as tailor in Australia and New Zealand, elf and shad in South Africa. It is a popular gamefish and food fish.
Longline fishing, or longlining, is a commercial fishing angling technique that uses a long main line with baited hooks attached at intervals via short branch lines called snoods or gangions. A snood is attached to the main line using a clip or swivel, with the hook at the other end. Longlines are classified mainly by where they are placed in the water column. This can be at the surface or at the bottom. Lines can also be set by means of an anchor, or left to drift. Hundreds or even thousands of baited hooks can hang from a single line. This can lead to many deaths of different marine species. Longliners – fishing vessels rigged for longlining – commonly target swordfish, tuna, halibut, sablefish and many other species.
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 fastest known shark species, able to reach speeds of 74 km/h (46 mph) in bursts, the shortfin mako can attain 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 yellowfin tuna is a species of tuna found in pelagic waters of tropical and subtropical oceans worldwide.
The white marlin, also known as Atlantic white marlin, marlin, skilligalee, is a species of billfish that lives in the epipelagic zone of the tropical and subtropical Atlantic Ocean. They are found between the latitudes of 45° N and 45° S in waters deeper than 100 m. Even though white marlin are found in bodies of water that are deeper than 100 m they tend to stay near the surface. White marlin have been found near banks, shoals, and canyons, but they are not limited to those locations. They prefer warm surface temperatures greater than 22 °C.
The Atlantic blue marlin is a species of marlin endemic to the Atlantic Ocean. It is closely related to, and usually considered conspecific with, the Indo-Pacific blue marlin, then simply called blue marlin. Some authorities consider both species distinct.
The billfish are a group of saltwater predatory fish characterised by prominent pointed bills (rostra), and by their large size; some are longer than 4 m (13 ft). Extant billfish include sailfish and marlin, which make up the family Istiophoridae; and swordfish, sole member of the family Xiphiidae. They are often apex predators which feed on a wide variety of smaller fish, crustaceans and cephalopods. These two families are sometimes classified as belonging to the order Istiophoriformes, a group which originated around 71 million years ago in the Late Cretaceous, with the two families diverging around 15 million years ago in the Late Miocene. However, they are also classified as being closely related to the mackerels and tuna within the suborder Scombroidei of the order Perciformes. However, the 5th edition of the Fishes of the World does recognise the Istiophoriformes as a valid order, albeit including the Sphyraenidae, the barracudas.
The striped marlin is a species of marlin found globally in tropical to temperate oceans not far from the surface. It is a desirable commercial and game fish, although conservation measures are in place to restrict its commercial landings. An epipelagic predator, it hunts during the day in the top 100 metres (330 ft) or so of the water column, often near the surface. One of its chief prey is sardines.
Marlin fishing or billfishing is offshore saltwater game fishing targeting several species of fast-swimming pelagic predatory fish with elongated rostrum collectively known as billfish, which include those from the families Istiophoridae and Xiphiidae (swordfish). It is considered by some fishermen to be a pinnacle of big-game fishing, due to the size, speed and power of the billfish and their relative elusiveness.
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 longfin mako shark 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. 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.
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 velvet belly lanternshark is a species of dogfish shark in the family Etmopteridae. One of the most common deepwater sharks in the northeastern Atlantic Ocean, the velvet belly is found from Iceland and Norway to Gabon and South Africa at a depth of 20–2,490 m (66–8,169 ft). A small shark generally no more than 45 cm (18 in) long, the velvet belly is so named because its black underside is abruptly distinct from the brown coloration on the rest of its body. The body of this species is fairly stout, with a moderately long snout and tail, and very small gill slits. Like other lanternsharks, the velvet belly is bioluminescent, with light-emitting photophores forming a species-specific pattern over its flanks and abdomen. The ventral photophores are thought to function in counter-illumination, which camouflages the shark against predators and prey. The bioluminescent flank markings may play a role in intraspecific communication.
The little tunny, also known as the bacora, little tuna, bonita, or erroneously as the blue bonito, is a species of tuna in the family Scombridae. It can be found in the Atlantic Ocean and the Mediterranean and Black seas; in the western Atlantic, it ranges from Brazil to the New England states. The little tunny is a pelagic fish that can be found regularly in both offshore and inshore waters, and it is classified as a highly migratory species. The little tunny is best identified by the "worm-like" markings on its back and the dark spots appearing between its pectoral and ventral fins.
A bait ball, or baitball, occurs when small fish swarm in a tightly packed spherical formation about a common centre. It is a last-ditch defensive measure adopted by small schooling fish when they are threatened by predators. Small schooling fish are eaten by many types of predators, and for this reason they are called bait fish or forage fish.
The following outline is provided as an overview of and topical guide to fish:
Brama is a genus of marine ray-finned fishes from the family Bramidae, the pomfrets. Currently, there are 8 species within the genus.
Brachioteuthis riisei is a species of squid in the family Brachioteuthidae.
The Condor Seamount is a submarine mountain located at 17 kilometres (11 mi) west-southwest of Faial Island in the Azores. It is approximately 1,800 metres (5,900 ft) high, 39 kilometres (24 mi) long and 23 kilometres (14 mi) wide, stretching from a depth of 185 metres (607 ft) up to 2,003 metres (6,572 ft). It is an elongated shaped volcano, oriented east-west, with the top relatively flat with smooth sedimentary flanks. Most seamounts lie in deep sea and/or open ocean, and thus are inaccessible and difficult to study. The Condor bank, constitutes an interesting case study due to its accessibility, located close to Faial island.
Of the twelve species of billfish, there are six species of Billfish in the Indian Ocean.
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 [270 kg] swordfish to embed its sword 3 feet [90 cm] in the timbers of ships, as has been known to occur; the figure seems to have entered the literature without question.