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Biology

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Swordfish have evolved to be formidable predators. They possess acute eyesight, with which they can locate prey, and their flesh consists primarily of 'white' muscle which provides energy for sudden bursts of activity, such as when in pursuit of their quarry (3). The swordfish then uses its bill to stun or impale its victim, slashes it into pieces or swallows it whole (3) (5). Swordfish feed during the day (3), primarily on squid, but also fish and occasionally crustaceans (6) (7) (8). They undertake vertical migrations in the ocean, following the movement of many small shrimp, fish and squid that move with the changing light intensity in a (somewhat unsuccessful) attempt to avoid predators (3) (7). Unlike some fish, swordfish are unable to maintain a body temperature higher than the temperature of the surrounding water. Instead, they have a unique muscle and brown tissue that warms blood flowing to the brain and eyes, enabling it to tolerate the extreme cold of the ocean depths (3). Swordfish also undertake lengthy seasonal migrations, to temperate or cold waters in the summer where they feed, and back to warm waters in autumn for spawning (2). Unlike tuna, which have mostly 'red' muscle which is good for endurance activities, the mostly 'white' muscle of swordfish is not suited to swimming for long periods without fatigue (3). Therefore, swordfish undertake their long migrations by moving with prevailing currents (3). Spawning occurs year-round in warm equatorial waters, while in cooler regions it occurs in the spring and summer (2) (4). The best known spawning grounds of the swordfish are found in the Mediterranean Sea, south of the Italian peninsula and Sicily (2). Swordfish eggs have been found here from June to September, and large numbers of juveniles occur throughout the Mediterranean from November to March (2). Fertilization is external (3), whereby a female releases millions of buoyant eggs into the water, which are then fertilised by sperm secreted by the male. From the fertilised eggs hatch swordfish larvae. At only four millimetres long, with a short snout, and distinct, prickly scales (4), the larvae is vastly different to the great predator it will become. During the first year of life the larvae grow at a phenomenal rate, reaching a length of 90 centimetres (3). Female swordfish are thought to reach maturity at around 150 centimetres; whereas males are thought to mature at much smaller sizes, perhaps at around 100 centimetres (3).
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Conservation

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The International Commission for the Conservation of Atlantic Tuna (ICCAT), formed in 1969 to protect populations of tuna, swordfish, marlin, and other large ocean-going commercially fished species (9). In 1999, ICCAT introduced a ten year recovery plan to rebuild the North Atlantic swordfish stocks (10). The plan, involving strict fishing quotas, has been a great success, with signs of improved catch rates within just two years (3). The United States also took steps to protect North Atlantic swordfish stocks by closing swordfish nursery areas to fishing (4) (10). This remarkable recovery highlights the importance of accurate stock assessments and careful fisheries management, actions that will hopefully be undertaken on the lesser known stocks in the future.
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Description

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This fast-swimming predator gets its name from its extremely long, flat, sword-like bill, which is used to impale or slash its prey. The swordfish, the only living member of the family Xiphiidae (3), has a long, cylindrical blackish-brown body that gradually fades to light-brown on the underside (2). The body tapers to large anal fins, which along with the high dorsal fin enable efficient cruising. Adult swordfish are scaleless and possess no teeth; swordfish less than one meter in length have small spines on the body and fine, file-like teeth (2). Usually, female swordfish grow larger and live longer than males (2) (3).
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Habitat

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The swordfish is an oceanic species, usually found in mid-water, at depths from 200 to 600 meters, in water from 18 to 22°C. It is frequently seen swimming at the surface, but may also swim at depths greater than 650 meters (2) (4).
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Range

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Occurs in tropical, temperate and sometimes even cold waters of all oceans, primarily between 50°N to 50°S (2) (3).
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Status

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Classified as Data Deficient (DD) by the IUCN Red List 2007. The North Atlantic stock is classified as Endangered (EN) (1).
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Threats

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Swordfish have been hunted by man for thousands of years, beginning with the harpooning of large female swordfish as they basked on the sea surface (3). Commercial fishing of this species commenced in the 1800s (3). Today, important swordfish fisheries exist in the Atlantic, Pacific and Indian Oceans (2), and the swordfish is captured incidentally in many other fisheries (3). As a result, stock assessments suggest that three out of the six established fisheries (the Mediterranean, South Atlantic and North Atlantic) are, or have been, fished at unsustainable levels (3). Swordfish abundance in the North Atlantic has shown a continuous decline since about 1980 (3), resulting in the World Conservation Union (IUCN) classifying this stock as Endangered (1), and in the Mediterranean, total catch levels and the size composition of the swordfish catch has declined significantly (3). Reliable stock assessments are not available for many other swordfish fisheries (3), and thus IUCN consider there to be insufficient information to determine the entire species' risk of extinction (1). As well as commercial fishing, swordfish are threatened by being a prized catch of recreational anglers (3).
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Life Expectancy

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Swordfish mature sexually in about five or six years, and live on average nine.
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Diagnostic Description

provided by FAO species catalogs
fieldmarks: Bill extremely long, its cross-section flat; no teeth in jaws, in adults a large single median caudal keel on each side; no pelvic fins; body without scales. Body elongate and cylindrical. Upper jaw prolonged into a long bill, flat-oval in cross-section (but both jaws prolonged into long bills in immature individuals); eyes large; mouth not protrusible; fine, file like teeth present in specimens of about 1 m (body length), disappearing with growth; gill openings wide, gill membranes united only basally and free from isthmus; no gillrakers. Two widely separate dorsal fins in adults (continuous in immature specimens), the first much larger than the second; first dorsal with 34 to 49, second dorsal with 4 to 6 rays; two separate anal fins in adults (continuous in immature specimens) the first much larger than the second; first anal with 13 or 14, second anal with 3 or 4 rays; position of second anal fin slightly more forward than that of second dorsal fin; pectoral fins falcate, a little rigid and situated low on body sides, with 16 to 18 rays; pelvic fins and pelvic girdle absent; caudal fin large and lunate. Caudal peduncle with a large keel present on each side and a deep notch on both the dorsal and ventral surfaces; anus situated near first anal fin origin. Lateral line absent in adults, but recognizable specimens to about 1 m body length as a wavy line, disappearing with growth. Adults scaleless but scales with small spines present in specimens to about 1 m body length. Vertebrae 26 (15 or 16 precaudal and 10 or 11 caudal). Colour: back and sides of body blackish-brown, gradually fading to light-brown on ventral side; fin membrane of first dorsal fin dark blackish brown; other fins brown or blackish-brown. In its preadult stage, the swordfish undergoes drastic morphological changes with growth, which affect the body shape, the bill and particularly the dorsal, anal and caudal fins.

References

  • Nakamura, 1983
  • Nakamura, H. et al., 1951
  • Ovchinnikov, 1970
  • Palko, Beardsley & Richards, 1981
  • Tibbo, Day & Doucet, 1961
  • Yabe, et al., 1959

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bibliographic citation
FAO species catalogue. Vo1.5. Billfishes of the World. An Annotated and Illustrated Catalogue of Marlins, Sailfishes, Spearfishes and Swordfishes Known to date.Izumi Nakamura 1985. FAO Fisheries Synopsis No. 125, Volume 5
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Distribution

provided by FAO species catalogs
Cosmopolitan in tropical, temperate and sometimes cold waters of all oceans, including the Mediterranean Sea, the Sea of Marmara, the Black Sea, and the Sea of Azov.Based on data from commercial longliners' catches, the latitudinal range of this species extends from 50° N to 45° S in the western Pacific, from 50° N to 35° S in the eastern Pacific, from 25° N to 45°S in the Indian Ocean, from 50° N to 40 - 45° S in the western Atlantic, and from 60° N to 45 ° - 50° S in the eastern Atlantic.
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FAO species catalogue. Vo1.5. Billfishes of the World. An Annotated and Illustrated Catalogue of Marlins, Sailfishes, Spearfishes and Swordfishes Known to date.Izumi Nakamura 1985. FAO Fisheries Synopsis No. 125, Volume 5
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Size

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This species reaches a maximum size of 445 cm total length and about 540 kg weight. The size range of fish taken by the commercial swordfish Iongliners is 120 to 190 cm body length in the northwestern Pacific; the average weight in the Mediterranean Sea ranges from 115 to 160 kg. Usually females are larger than males, and most swordfish over 140 kg are females. Adults grow over 230 kg (rarely) in the Mediterranean, up to 320 kg in the western Atlantic, and up to 537 kg in the southeastern Pacific. The all-tackle-angling record for this species is a 536.15 kg (1182 lb) fish caught off lquique, Chile in 1953. There is little information on biological minimum size and age and some of the data are contradictory. X. gladius first spawns at 5 to 6 years of age and 150 to 170 cm eye-fork length (which is 85 to 88% of body length) in,the Pacific and Indian oceans (Yabe et al., 1959). Males reach sexual maturity at a length of around 100 cm and females at a length of 70 cm in the Atlantic (Ovchinnikov, 1970). However, recent research conducted on swordfish off the southeast coast of the United States indicates that males mature at a smaller size than females (at about 21 kg for males and 74 kg for females) (E. Houde, pers.comm., cited from Palko, Beardsley & Richards, 1981). Kume and Joseph (1969) regarded swordfish of less than 130 cm eye-fork length as immature.
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FAO species catalogue. Vo1.5. Billfishes of the World. An Annotated and Illustrated Catalogue of Marlins, Sailfishes, Spearfishes and Swordfishes Known to date.Izumi Nakamura 1985. FAO Fisheries Synopsis No. 125, Volume 5
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Brief Summary

provided by FAO species catalogs
This is an epi-and mesopelagic,oceanic species,usually found in surface waters warmer than 13° C, the optimum temperature range being 18° to 22°C in the northwestern Pacific Ocean. The swordfish has the greatest temperature tolerance among billfishes, ranging from 5° to 27°C. Based on records of forage organisms taken by this species, its depth distribution in the northwestern Pacific ranges normally from the surface to about 550 m depth. It is believed, however, to descend occasionally into waters of 5° to 10°C and to depths of at least 650 m.The swordfish is primarily a warm-water species and, generally speaking, its migrations consist of movements toward temperate or cold waters for feeding in summer and back to warm waters in autumn for spawning and overwintering.There are two hypotheses on the migration of the swordfish in the northwestern Atlantic: (1) they migrate to the north and east along the edge of the continental shelf during summer and return to the south and west in autumn, or (2) there are different groups of swordfish migrating from deep waters toward the continental shelf in summer and moving back to deep waters in autumn.Larvae are more frequently encountered at temperatures above 24° C. 'In the Atlantic, spawning apparently occurs throughout the year in the Caribbean, the Gulf of Mexico, and in the waters off Florida, with the peak of the spawning season from April through September. In the Pacific Ocean, it occurs in spring and summer (March through July) in the central part, in spring (September to December) in the western South Pacific, and all the year round in equatorial Pacific waters. The best known spawning grounds of the swordfish are found in the Mediterranean Sea, off the southern part of the Italian Peninsula and Sicily, the main spawn in concentrations occurring in the Straits of Messina. Adults are present on these spawning grounds in all months except January and February, and spawning is most intensive from the end of June to August, when males are often observed pursuing females. Eggs of this species have been found from June to September, and young swordfish up to 5 kg have been recorded from October to December. Large numbers of Juveniles occur throughout the from November to March. Female gonads contain 2 to 5 million eggs. In the Atlantic Ocean swordfish spawn in the upperwater layer at depths between 0 and 75 m, at temperatures around 23°C, and salinity of 33.8 to 37.4°/oo. Adult swordfish are opportunistic feeders, known to forage for their food from the surface to the bottom over a wide depth range. Over deep water, they feed primarily on pelagic fishes, including tunas (Thunnus), dolphinfishes (Coryphaena), Alepisaurus, Gempylus, flyingfishes (Exocoetidae), barracudas (Sphyraenidae) others, and pelagic squids (Ommastrephes, Loligo, Illex and others), while in relatively shallow waters they take chiefly neritic pelagic fishes (mackerels, herrings, anchovies, sardines, sauries, needlefishes, etc.). Large adults often make feeding trips to the bottom where the temperatures may be 5° to 10°C and feed on demersal fishes (hakes, Bramidae, trichiurids, gempylids, redfish, lanternfishes (Myctophydae), Gonostomatidae, Sternoptychidae, etc.). Based on stomach contents from X. gladius, it is most likely true that the swordfish uses its sword to kill some of its prey, particularly squids and cuttlefishes, as is shown by the slashes on the bodies of prey found in swordfish stomachs.
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FAO species catalogue. Vo1.5. Billfishes of the World. An Annotated and Illustrated Catalogue of Marlins, Sailfishes, Spearfishes and Swordfishes Known to date.Izumi Nakamura 1985. FAO Fisheries Synopsis No. 125, Volume 5
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Benefits

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There are important fisheries for X. gladius in the Atlantic, Indian and Pacific oceans. Catches have been reported from 14 FAO Fishing Areas (21, 27, 31, 34, 41, 47, 51, 57, 61, 67, 70, 77, 81 and 87) by about 30 countries (major fishing nations: Japan, USA, Italy, Spain, Canada, Republic of Korea, China (Taiwan Province), the Philippines and Mexico) in the period from 1978 to 1982. The world catch was 40 279 t in 1978, 37 992 t in 1971, 36 402 t in 1980, 37 726 t in 1981 and 40 321 t in 1982. Only 1 439 t of the 1981 catches were taken in the Indian Ocean, while the rest were distributed in halves between the Pacific and Atlantic oceans (including the Mediterranean Sea), particularly in Fishing Area 61 (northwestern Pacific) with 8 085 t predominantly by Japan, and secondly by China (Taiwan Province), Fishing Area 37 (Mediterranean) with 6 584 t predominantly by Italy and Spain, and Fishing Area 77 (eastern central Pacific) with 5 210 t predominantly by Mexico and Japan. [more...] The quality of the flesh is excellent for steaks, canning or "Teriyaki" (grilled meat with sugar; soy-sauce and rice wine in the Japanese way). Marketed mostly fresh or frozen.
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FAO species catalogue. Vo1.5. Billfishes of the World. An Annotated and Illustrated Catalogue of Marlins, Sailfishes, Spearfishes and Swordfishes Known to date.Izumi Nakamura 1985. FAO Fisheries Synopsis No. 125, Volume 5
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Diagnostic Description

provided by Fishbase
Blackish-brown fading to light-brown below; 1st dorsal fin with blackish-brown membrane, other fins brown or blackish-brown (Ref. 43). A long, flat, sword-like bill and no pelvic fins (Ref. 26938).
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Recorder
Cristina V. Garilao
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Life Cycle

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In the Atlantic Ocean, spawning occurs in the upper water layer at depths between 0 and 75 m, at temperatures around 23°C, and salinity of 33.8 to 37.4 ppt.The distribution of larval broadbill swordfish in the Pacific Ocean indicates that spawning occurs mainly in waters with a temperature of 24°C or more. Spawning appears to occur in all seasons in equatorial waters, but is restricted to spring and summer at higher latitudes (Ref. 30448).Fertilisation in broadbill swordfish is external and pairing of solitary males and females is thought to occur when spawning (Ref. 9742). Broadbill swordfish are reported to spawn in the upper layers of the water column, from the surface to a depth of 75 m (Ref. 43).Estimates of egg numbers vary considerably, from 1 million to 16 million in 168,000 g female (Ref. 9742) and 29 million in a 272,000 g female (Ref. 30372).
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Armi G. Torres
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Migration

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Oceanodromous. Migrating within oceans typically between spawning and different feeding areas, as tunas do. Migrations should be cyclical and predictable and cover more than 100 km.
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Morphology

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Dorsal spines (total): 0; Dorsal soft rays (total): 38 - 56; Analspines: 0; Analsoft rays: 16 - 18
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Trophic Strategy

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Juveniles are common only in tropical and sub-tropical waters and migrate to higher latitudes as they mature (Ref. 7176). In southeastern Australian waters, sharp temperature and salinity gradients across oceanic fronts provide favourable conditions for concentrations of broadbill swordfish (Ref. 6390). Little is known of large scale movements by adult broadbill swordfish. Mature fish make only limited local movements (Ref. 9742). Tracking of fish using acoustic tags has shown that broadbill swordfish typically move to surface waters at night and inhabit deeper waters during the day, reaching depths up to 600 m (Ref. 30447). These vertical movements may be rapid and involve changes in waters temperature as great as 19°C (Ref. 6390). Some tagged fish spend daylight hours near the sea bed close to the continental shelf break or submerged banks and move offshore at night (Ref. 6390). In the eastern Pacific broadbill swordfish are commonly seen basking at the sea surface for short periods during the day, a behaviour that may allow the fish to recover from stress associated with low temperature and dissolved oxygen levels in deep water (Ref. 30447). Broadbill swordfish are normally solitary, but pairs of fish are regularly observed at the surface off the Californian coast (Ref. 30447).Larvae are most common within a few m of the surface during the day but may move to depths of 30 m at night (Ref. 30448). Swordfish larvae longer than 10 mm feed almost exclusively on larvae of other fish species (Ref. 6390). Young swordfish is preyed upon by blue shark, tuna and marlins. Parasites of the species include a cestode, Fistulicola plicatus; trematode, Tristoma spp.; monogenean, Tristoma coccineumand T. integrum; nematode, Thynnascaris incurva and a copepod, Pennella filosa (Ref. 5951).
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Susan M. Luna
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Biology

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Oceanic but sometimes found in coastal waters (Ref. 9354). Generally above the thermocline (Ref. 9354), preferring temperatures of 18°C to 22°C (Ref. 9987). Larvae are frequently encountered at temperatures above 24 °C (Ref. 9702). Migrate toward temperate or cold waters in the summer and back to warm waters in the fall. Adults are opportunistic feeders, known to forage for their food from the surface to the bottom over a wide depth range (Ref. 9702). Feed mainly on fishes (Atlantic mackerel, barracudinas, silver hake, redfish, herring and lanternfishes (Ref. 5951); also on crustaceans and squids (Ref. 9354). They use their sword to kill their prey (Ref. 9354). Large individuals may accumulate large percentages of mercury in its flesh (Ref. 9354). Are batch spawners (Ref. 51846). Spawning takes place in Atlantic during spring in southern Sargasso Sea. Migrate to cooler waters to feed (Ref. 4689). Females grow fastest. Determination of age is difficult since the otoliths are very small and scales are missing in adults. Year rings have been successfully counted on cross sections of the fin rays (Ref. 35388). Pelagic eggs measure 1.6-1.8mm and the newly hatched larvae is 4 mm long. Sword is well developed at a length of 10mm and young live pelagically in the upper water layers where they quickly develop into very voracious predators (Ref. 35388). Mt DNA restriction analysis reveal that genetic differentiation occurs between populations inhabiting the Mediterranean Sea and the tropical Atlantic ocean, indicating little genetic exchange occurring between the two (Ref. 12784). Good food fish, marketed fresh or frozen, and can be made into sashimi, teriyaki or fillets (Ref. 9354).
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Christine Papasissi
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Importance

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fisheries: commercial; gamefish: yes
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Christine Papasissi
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分布

provided by The Fish Database of Taiwan
廣泛分布於世界各熱帶及溫熱帶海域,有時也出現於冷水域。台灣各地均有產,尤以東部產量最豐。
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臺灣魚類資料庫
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臺灣魚類資料庫

利用

provided by The Fish Database of Taiwan
重要之經濟性魚種。全世界年產量大約在35,000-42,000公噸。一般漁法以一支釣或定置網捕獲,有些地區以圍網或流刺網法。一般以煮湯或製成罐頭食之,有些地區作味噌魚,味道不錯。亦是遊釣魚種,通常3-4月及7-12月較常釣到。
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描述

provided by The Fish Database of Taiwan
體短壯,尾柄細,平扁,每側具一發達的中央隆起脊,無其它小隆起脊。吻部向前延長為扁而尖銳之劍狀突出。眼大。齒細小,隨著成長而逐漸消失,成魚則不具頜齒。無鰓耙。第一背鰭基底短,與第二背鰭分離甚遠;胸鰭低位;無腹鰭;尾鰭深分叉而有力,尾柄末端上下具深凹。體背及體側呈黑褐色,體腹側呈淡褐色。第一背鰭鰭膜暗褐色;餘鰭褐色或暗褐色。
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棲地

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大洋性中上層洄游魚種,有季節性越冬洄游,一般相信生活於13℃-27℃之暖水域,但亦發現其耐溫性佳。偶然可發現於水溫5℃-10℃之間之冷水域。通常獨游以追逐鯖、飛魚、鱰等魚類為食。活動範圍很廣,從表層到海底幾百公尺都有,在臺灣東部流經的黑潮海域內很多。通常在夏天8-9月產卵。
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Swordfish

provided by wikipedia EN

Swordfish (Xiphias gladius), also known as broadbills[4] 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.[2] 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.[3][5]

They are the sole member of their family, Xiphiidae.[6]

Taxonomy and etymology

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").[5] 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.[7]

Several extinct genera are known, such as a large sized Xiphiorhynchus and Aglyptorhynchus.[8] Unlike modern taxa these have equally long lower jaws.

Description

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.[3][5] 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.[2] Females are larger than males, and Pacific swordfish reach a greater size than northwest Atlantic and Mediterranean swordfish.[5] They reach maturity at 4–5 years of age and the maximum age is believed to be at least 9 years.[5] 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.[9]

Swordfish are ectothermic animals; however, along with some species of sharks, they have special organs next to their eyes to heat their eyes and brains. See heater cells for more information about these specialized modified muscle cells.[10] Temperatures of 10 to 15 °C (18 to 27 °F) 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.[11][12] Of over 25,000 fish species, only 22 are known to have a mechanism to conserve heat. These include the swordfish, marlin, tuna, and some sharks.[11][12]

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.[5] The use as an offensive spear in case of dangers against large sharks or animals is 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.[13] Research on related marlin (Istiophorus platypterus) suggest a maximum value of 36 km/h (22 mph) is more likely.[14]

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.

Swordfish prefer water temperatures between 18 and 22 °C (64 and 72 °F),[2] but have the widest tolerance among billfish, and can be found from 5 to 27 °C (41 to 81 °F).[5] This highly migratory species typically moves towards colder regions to feed during the summer.[5] 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).[2] 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.[3][5] 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.[15] Large prey are typically slashed with the sword, while small are swallowed whole.[5]

Stuffed broadbill swordfish

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 copepods.[5][16] 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.[17]

Fully adult swordfish have few natural predators. Among marine mammals, killer whales sometimes prey on adult swordfish.[5] 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.[18] Juvenile swordfish are far more vulnerable to predation, and are eaten by a wide range of predatory fish.[5][19] Intensive fishery may be driving swordfishes and sharks into harder competition for reduced amounts of prey and therefore pitting them to fight more.[19]

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).[20]

Breeding

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.[2] In the North Atlantic, spawning is known from the Sargasso Sea,[21] and in water warmer than 23 °C (73 °F) and less than 75 m (246 ft; 41 fathoms) deep.[2] Spawning occurs from November to February in the South Atlantic off southern Brazil.[2] Spawning is year-round in the Caribbean Sea and other warm regions of the west Atlantic.[5]

Large females can carry more eggs than small females, and between 1 million to 29 million eggs have been recorded.[2] The pelagic eggs measure 1.6–1.8 mm (116564 in) in diameter and 2+12 days after fertilization, the embryonic development occurs.[21][5] The surface-living and unique-looking larvae are 4 mm (532 in) long at hatching.[3][5] The bill is evident when the larvae reach 1 cm (38 in) in length.[3]

Fisheries

Felucca used in the Strait of Messina to hunt swordfish
Global capture of swordfish in tonnes reported by the FAO, 1950–2009[22]

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.[23][24][25]

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.[26]

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 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.[27] 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.

As food

Swordfish are classified as oily fish.[28] Many sources, including the United States Food and Drug Administration, warn about potential toxicity from high levels of methylmercury in swordfish.[29][30] The FDA recommends that young children, pregnant women, and women of child-bearing age not eat swordfish.[31]

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 often being rosier.

Kashrut

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 in was not kosher due to the lack of scales. Tendler's opinion provoked strong debate among halakhic authorities during the 1960s.[32][33] 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.[34]

Conservation status

Swordfish on deck during long-lining operations

In 1998, the US 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.[35]

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 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 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.[36] 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.[37]

In 2010, Greenpeace International added the swordfish to its seafood red list.[38]

Extinct

In culture

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

References

  1. ^ Fierstine, Harry L. (1990). "A paleontological review of three billfish families (Istiophoridae, Xiphiidae, and Xiphiorhynchidae)" (PDF). Biological Sciences: 11.
  2. ^ a b c d e f g h i Collette, B.B; Di Natale, A.; Fox, W.; Graves, J.; Juan Jorda, M.; Pohlot, B.; Restrepo, V.; Schratwieser, J. (2022). "Xiphias gladius". IUCN Red List of Threatened Species. 2022. doi:10.2305/IUCN.UK.2022-1.RLTS.T23148A46625751.en. Retrieved 14 October 2022.
  3. ^ a b c d e f Froese, Rainer; Pauly, Daniel (eds.) (2018). "Xiphias gladius" in FishBase. February 2018 version.
  4. ^ Grey, Zane. "Tales of Swordfish and Tuna." (2000) p. 107. The Derrydale Press, Lanham and New York.
  5. ^ a b c d e f g h i j k l m n o p Gardieff, S. "Swordfish". Florida Museum of Natural History. Archived from the original on 9 August 2015. Retrieved 26 December 2011.
  6. ^ Froese, Rainer, and Daniel Pauly, eds. (2011). "Xiphiidae" in FishBase. December 2011 version.
  7. ^ Pepperell, J. 2010. Fishes of the Open Ocean: A Natural History and Illustrated Guide. ISBN 978-0-226-65539-0
  8. ^ Fierstine, Harry L. (2006). "Fossil History of Billfishes (Xiphioidei)". Bulletin of Marine Science. S2CID 20606448.
  9. ^ Marsh, Jesse; Stiles, Margot (2007). "Seafood Watch, Seafood Report, Monterey Bay Aquarium" (PDF). Archived from the original (PDF) on 2 February 2017.
  10. ^ Sherwood, Klandorf, Yancey, Animal Physiology: From Genes to Organisms, 2nd edition)
  11. ^ a b Fritsches, K. A.; Brill, R. W.; Warrant, E. J. (2005). "Warm eyes provide superior vision in swordfishes". Current Biology. 15 (1): 55–58. doi:10.1016/j.cub.2004.12.064. PMID 15649365. S2CID 14070646.
  12. ^ a b Hopkin, Michael (2005). "Swordfish heat their eyes for better vision". Nature. doi:10.1038/news050110-2.
  13. ^ "Haulin' Bass". ReefQuest Centre for Shark Research. Retrieved 26 December 2011. 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.
  14. ^ Svendsen, Morten B. S.; Domenici, Paolo; Marras, Stefano; Krause, Jens; Boswell, Kevin M.; Rodriguez-Pinto, Ivan; Wilson, Alexander D. M.; Kurvers, Ralf H. J. M.; Viblanc, Paul E.; Finger, Jean S.; Steffensen, John F. (15 October 2016). "Maximum swimming speeds of sailfish and three other large marine predatory fish species based on muscle contraction time and stride length: a myth revisited". Biology Open. 5 (10): 1415–1419. doi:10.1242/bio.019919. ISSN 2046-6390. PMC 5087677. PMID 27543056.
  15. ^ Stillwell; Kohler (1985). "Food and feeding ecology of the swordfish Xiphias gladius in the western North Atlantic Ocean with estimates of daily ration". Mar. Ecol. Prog. Ser. 22: 239–241. Bibcode:1985MEPS...22..239S. doi:10.3354/meps022239.
  16. ^ Bolin, Jessica A.; Cummins, Scott F.; Mitu, Shahida A.; Schoeman, David S.; Evans, Karen J.; Scales, Kylie L. (11 June 2021). "First report of Kudoa thunni and Kudoa musculoliquefaciens affecting the quality of commercially harvested yellowfin tuna and broadbill swordfish in Eastern Australia". Parasitology Research. 120 (7): 2493–2503. doi:10.1007/s00436-021-07206-8. ISSN 1432-1955. PMID 34115215. S2CID 235404099.
  17. ^ Mattiucci, S.; Garcia, A.; Cipriani, P.; Santos, M. N.; Nascetti, G.; Cimmaruta, R. (2014). "Metazoan parasite infection in the swordfish, Xiphias gladius, from the Mediterranean Sea and comparison with Atlantic populations: implications for its stock characterization". Parasite. 21: 35. doi:10.1051/parasite/2014036. PMC 4109596. PMID 25057787.
  18. ^ The Shark Trust. "Shortfin mako". Archived from the original on 14 July 2011. Retrieved 26 December 2011.
  19. ^ a b Sokol, Joshua (27 October 2020). "Sharks Wash up on Beaches, Stabbed by Swordfish". The New York Times. Retrieved 5 January 2023.
  20. ^ "North Atlantic Swordfish | FishWatch". www.fishwatch.gov. Retrieved 14 May 2021.
  21. ^ a b Froese, Rainer; Pauly, Daniel (eds.) (2011). "Xiphias gladius" in FishBase. December 2011 version.
  22. ^ "Aquatic species: Xiphias gladius (Linnaeus, 1758)". Food and Agriculture Organization. Retrieved 5 January 2023.
  23. ^ "La Pesca del Pescespada". Archived from the original on 26 April 2012. Retrieved 30 December 2011.
  24. ^ "La pesca del pesce spada". www.biologiamarina.eu.
  25. ^ "La tecnica per la pesca del pescespada e la "Feluca" - Ganzirri, il Peloro e lo Stretto di Messina". www.ganzirri.it.
  26. ^ Preuss, Andreas; Marco, Tony (1 June 2015). "Swordfish kills fisherman in Hawaii". CNN.com.
  27. ^ "Daytime Swordfish Tactics That Work Like a Charm". FishingBooker.com. 13 October 2018.
  28. ^ "What's an oily fish?". Food Standards Agency. 24 June 2004. Archived from the original on 10 December 2010. Retrieved 8 July 2009.
  29. ^ FDA (1990–2010). "Mercury Levels in Commercial Fish and Shellfish". Food and Drug Administration. Retrieved 14 September 2011.
  30. ^ EPA. "What you need to know about mercury in fish and shellfish". Retrieved 14 September 2011.
  31. ^ FDA (2 July 2019). "Advice About Eating Fish". FDA. Retrieved 27 September 2019.
  32. ^ "Swordfish: The Fish of Legends". The Biblical Museum of Natural History. Retrieved 8 April 2023.
  33. ^ "Is Swordfish Kosher?". Retrieved 8 April 2023.
  34. ^ "The Turning of the Tide: The Kashrut Tale of the Swordfish" (PDF). Bar-Ilan University. Retrieved 8 April 2023.
  35. ^ "Swordfish". Fenton Communications. Archived from the original on 31 December 2007.
  36. ^ "Species directory: North Atlantic Swordfish". NOAA.gov. 28 December 2022. Retrieved 5 January 2023.
  37. ^ "Seafood Watch – Seafood Report – Swordfish" (PDF). Monterey Bay Aquarium. Archived from the original (PDF) on 14 July 2007. Retrieved 16 July 2008.
  38. ^ "Greenpeace International Seafood Red List" (PDF). October 2010. Archived from the original (PDF) on 10 November 2011. Retrieved 14 September 2012.
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Swordfish: Brief Summary

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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 550 m (1,800 ft), and exceptionally up to depths of 2,234 m. 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.

They are the sole member of their family, Xiphiidae.

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Description

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Occurs at a temperature range of 5° to 27°C, generally above the thermocline but may descend to depths of 800 m (Ref. 9354), but prefers temperatures of 18°C to 22°C (Ref. 9987). Primarily a warm-water species. Although oceanic, sometimes found in coastal waters (Ref. 9354). Its migrations consist of movements toward temperate or cold waters for feeding in summer and back to warm waters in autumn for spawning and overwintering. Lives a solitary life upon the high seas. Larvae are frequently encountered at temperatures above 24 °C (Ref. 9702). Adults are opportunistic feeders, known to forage for their food from the surface to the bottom over a wide depth range (Ref. 9702). Uses its sword to kill its prey (Ref. 9354). Feeds mainly on fishes but also on crustaceans and squids (Ref. 9354). Also caught with harpoons, drift gill nets and set nets by commercial fisheries and by trolling in sports fishing (Ref. 9702). A good food fish, it is marketed fresh or frozen, and can be made into sashimi, teriyaki or fillets (Ref. 9354). Large individuals may accumulate large percentages of mercury in its flesh (Ref. 9354).

Reference

Froese, R. & D. Pauly (Editors). (2023). FishBase. World Wide Web electronic publication. version (02/2023).

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Diet

provided by World Register of Marine Species
Feed mainly on fishes but also on crustaceans and squids

Reference

North-West Atlantic Ocean species (NWARMS)

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Distribution

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Bonne Bay, over the Grand Bank along the offing of Cape Breton and in to the southern Gulf of St Lawrence and along the outer coast of Nova Scotia, southward along the coast of the United States; into Argentina in the South Atlantic

Reference

North-West Atlantic Ocean species (NWARMS)

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Habitat

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oceanic but sometimes found in coastal waters

Reference

North-West Atlantic Ocean species (NWARMS)

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Habitat

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nektonic

Reference

North-West Atlantic Ocean species (NWARMS)

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Habitat

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Known from seamounts and knolls

Reference

Stocks, K. 2009. Seamounts Online: an online information system for seamount biology. Version 2009-1. World Wide Web electronic publication.

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