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Overview

Brief Summary

Biology

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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Description

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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Comprehensive Description

Description

  Common names: swordfish (English), pez (Espanol)
 
Xiphias gladius Linnaeus, 1758


Swordfish


An elongate, rounded body, tapering to rear; head large, with a very long flattened bill; no teeth on jaws in adult;  1st  dorsal fin short based, high, curved, 34-49, well separated from 2nd  dorsal (4-6), which is small, at rear of body; no pelvic fins; pectoral fins low on the sides, 16-18; 1st  anal fin, 13-14, short based, fin long and curved, between the 2 dorsals, 2nd  anal 3-4, tiny, under 2nd  dorsal; tail base with a large keel on each side and a deep notch above and below just before tail fin; tail fin large, strongly concave; no scales in adult.


Blackish brown on back fading to light brown or silvery on sides; first dorsal fin dark blackish brown; other fins brown or blackish brown.

Maximum size 457 cm; all-tackle world rcord 100.24 Kg.

Habitat: pelagic, oceanic.

Depth: 0-2878 m.

Circumglobal in tropical, temperate, and adjacent cold seas; southern California to the mouth of the Gulf of California to Peru and the offshore islands, common around the Galapagos.   
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Biology

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)) but 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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Distribution

National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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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
  • North-West Atlantic Ocean species (NWARMS)
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Zoogeography

See Map (including site records) of Distribution in the Tropical Eastern Pacific 
 
Global Endemism: All species, TEP non-endemic, Circumtropical ( Indian + Pacific + Atlantic Oceans), "Transpacific" (East + Central &/or West Pacific), All Pacific (West + Central + East), East Pacific + Atlantic (East +/or West), Transisthmian (East Pacific + Atlantic of Central America), East Pacific + all Atlantic (East+West)

Regional Endemism: All species, Eastern Pacific non-endemic, Tropical Eastern Pacific (TEP) non-endemic, Continent + Island (s), Continent, Island (s)

Residency: Resident

Climate Zone: North Temperate (Californian Province &/or Northern Gulf of California), Northern Subtropical (Cortez Province + Sinaloan Gap), Northern Tropical (Mexican Province to Nicaragua + Revillagigedos), Equatorial (Costa Rica to Ecuador + Galapagos, Clipperton, Cocos, Malpelo), South Temperate (Peruvian Province )
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Atlantic, Indian and Pacific: tropical and temperate and sometimes cold waters, including the Mediterranean Sea, the Sea of Marmara, the Black Sea, and the Sea of Azov. Highly migratory species, Annex I of the 1982 Convention on the Law of the Sea (Ref. 26139). 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).
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Circumglobal in tropical to temperate seas (including Baltic Sea, North Sea, Mediterranean Sea, Black Sea, Red Sea, Mascarenes, Hawaiian Islands).
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Atlantic, Indian and Pacific Oceans: tropical and temperate and sometimes cold waters, including the Mediterranean Sea, the Sea of Marmara, the Black Sea, and the Sea of Azov.
  • Bigelow, H.B. and W.C. Schroeder, 1953; Collette, B.B., 1995; Frimodt, C., 1995; Nakamura, I., 1985; Nakamura, I., 1997; Nishikawa, Y. and S. Ueyanagi, 1974; Palko, B.J., G.L. Beardsley and W.J. Richards, 1981; Wilson, C.A. III, 1984.
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Depth

Depth Range (m): 0 (S) - 2878 (S)
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Range

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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Physical Description

Morphology

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

Length max (cm): 457.0 (S)
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Size

Maximum size: 4500 mm TL
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Max. size

455 cm FL (male/unsexed; (Ref. 40637)); max. published weight: 650.0 kg (Ref. 4689)
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to 450.0 cm TL (male/unsexed); max. weight: 650 kg.
  • Bigelow, H.B. and W.C. Schroeder, 1953; Collette, B.B., 1995; Frimodt, C., 1995; Nakamura, I., 1985; Nakamura, I., 1997; Nishikawa, Y. and S. Ueyanagi, 1974; Palko, B.J., G.L. Beardsley and W.J. Richards, 1981; Wilson, C.A. III, 1984.
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Diagnostic Description

Description

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).
  • Anon. (1996). FishBase 96 [CD-ROM]. ICLARM: Los Baños, Philippines. 1 cd-rom pp.
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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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Ecology

Habitat

Habitat Type: Marine

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Known from seamounts and knolls
  • Stocks, K. 2009. Seamounts Online: an online information system for seamount biology. Version 2009-1. World Wide Web electronic publication.
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nektonic
  • North-West Atlantic Ocean species (NWARMS)
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oceanic but sometimes found in coastal waters
  • North-West Atlantic Ocean species (NWARMS)
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Habitat and Ecology

Habitat and Ecology
This is an oceanic species, but sometimes found in coastal waters; generally above the thermocline, preferring temperatures of 18–22°C. It is primarily a warm-water species that migrates toward temperate or cold waters for feeding in the summer and back to warm waters in summer for spawning and overwintering. Adults are opportunistic feeders, known to forage for their food from the surface to the bottom over a wide depth range (Nakamura 1985). Swordfish typically forage in deep water during the day and stay in the mixed layer at night (Abascal et al. 2010). Based on records of forage organisms taken by swordfish, its depth distribution in the northwestern Pacific ranges normally from the surface to a depth of about 550 m but there are depth records down 2,878 m.

This species uses its sword to kill prey. It feeds mainly on fishes but also on crustaceans and squids. Large individuals may accumulate high concentrations of mercury in the flesh (Collette 1995).

The distribution of larval 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 (Nishikawa and Ueyanagi 1974). In the Atlantic Ocean, spawning occurs in the upper water layer at depths between 0–75 m, at temperatures around 23°C, and salinity of 33.8–37.4 ppt. Pairing of solitary males and females is thought to occur when spawning (Palko et al. 1981). Spawning in southern Brazil occurs from November to February in between 20–28°S and 40–47°W (Amorim and Arfelli 1980). Estimates of egg numbers vary considerably, from one million to 16 million in 168,000 g female (Palko et al. 1981) and 29 million in a 272,000 g female (Wilson 1984).

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 (Arocha et al. 2003, DeMartini et al. 2006). Longevity is estimated to be 15 years (based on Arocha et al. 2003, DeMartini et al. 2006), and age of first maturity is estimated to be five years (based on Arocha and Lee 1996, Hinton and Maunder, unpublished data). These life history parameters do not differ greatly between stocks, therefore, the generation length for this species was estimated to be 6.5 years globally. The generation length is calculated as: age of first reproduction + z * (longevity - age of first maturity), where z is 0.15 (Collette et al. 2011).

Maximum size is 445 cm. The all-tackle game fish record is of a 536.15 kg fish caught odd Iquique, Chile in 1953 (IGFA 2011).

Systems
  • Marine
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Environment

pelagic-oceanic; oceanodromous (Ref. 51243); marine; depth range 0 - 800 m (Ref. 9354), usually 0 - 550 m (Ref. 54934)
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Depth range based on 154895 specimens in 1 taxon.
Water temperature and chemistry ranges based on 146797 samples.

Environmental ranges
  Depth range (m): 0 - 4700
  Temperature range (°C): 1.478 - 27.910
  Nitrate (umol/L): 0.050 - 32.106
  Salinity (PPS): 30.771 - 37.537
  Oxygen (ml/l): 2.521 - 7.737
  Phosphate (umol/l): 0.022 - 2.072
  Silicate (umol/l): 0.481 - 80.155

Graphical representation

Depth range (m): 0 - 4700

Temperature range (°C): 1.478 - 27.910

Nitrate (umol/L): 0.050 - 32.106

Salinity (PPS): 30.771 - 37.537

Oxygen (ml/l): 2.521 - 7.737

Phosphate (umol/l): 0.022 - 2.072

Silicate (umol/l): 0.481 - 80.155
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Depth: 0 - 800m.
Recorded at 800 meters.

Habitat: pelagic. Oceanic but sometimes found in coastal waters (Ref. 9354). Generally above the thermocline (Ref. 9354). Prefers temperatures of 18°C to 22°C (Ref. 9987). Larvae are frequently encountered at temperatures above 24 °C (Ref. 9702). Migrates 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). Uses its sword to kill its prey (Ref. 9354). Feeds mainly on fishes but also on crustaceans and squids (Ref. 9354). Good food fish, 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).
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Pelagic; marine; depth range 0 - 800 m. Oceanic generally above the thermocline in temperatures 18°C - 22°C. Larvae are frequently in water temperatures above 24°C. Seasonal migration - toward temperate or cold waters in summer and to warm waters in fall. Sometimes found in coastal waters.
  • Bigelow, H.B. and W.C. Schroeder, 1953; Collette, B.B., 1995; Frimodt, C., 1995; Nakamura, I., 1985; Nakamura, I., 1997; Nishikawa, Y. and S. Ueyanagi, 1974; Palko, B.J., G.L. Beardsley and W.J. Richards, 1981; Wilson, C.A. III, 1984.
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Salinity: Marine, Marine Only

Inshore/Offshore: Offshore Only, Offshore

Water Column Position: Surface, Near Surface, Mid Water, Water column only

Habitat: Water column

FishBase Habitat: Pelagic
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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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Migration

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

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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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Trophic Strategy

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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Fishes mainly, but also crustaceans and squids. Adults are opportunistic feeders, and forage over a wide depth range. The sword is used to kill prey.
  • Bigelow, H.B. and W.C. Schroeder, 1953; Collette, B.B., 1995; Frimodt, C., 1995; Nakamura, I., 1985; Nakamura, I., 1997; Nishikawa, Y. and S. Ueyanagi, 1974; Palko, B.J., G.L. Beardsley and W.J. Richards, 1981; Wilson, C.A. III, 1984.
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Feeding

Feeding Group: Carnivore

Diet: octopus/squid/cuttlefish, Pelagic crustacea, bony fishes
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Life History and Behavior

Behavior

Diet

Feed mainly on fishes but also on crustaceans and squids
  • North-West Atlantic Ocean species (NWARMS)
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Life Cycle

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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Life Expectancy

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

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Reproduction

Spawning occurs throughout the year in equatorial waters, but only during spring and summer at higher latitudes. Fertilization is external; solitary males and females are thought to pair during spawning. Estimates of egg numbers vary from 1 million to 16 million in 168,000 g female and 29 million in a 272,000 g female. In the Atlantic Ocean, spawning takes place at depths between 0 and 75 m with temperatures around 23 °C, and salinity of 33.8 to 37.4 ppt. In the Pacific Ocean, the distribution of larval broadbill swordfish suggests that spawning occurs mainly in waters with a temperature of 24°C or more.
  • Bigelow, H.B. and W.C. Schroeder, 1953; Collette, B.B., 1995; Frimodt, C., 1995; Nakamura, I., 1985; Nakamura, I., 1997; Nishikawa, Y. and S. Ueyanagi, 1974; Palko, B.J., G.L. Beardsley and W.J. Richards, 1981; Wilson, C.A. III, 1984.
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Egg Type: Pelagic, Pelagic larva
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Evolution and Systematics

Functional Adaptations

Functional adaptation

Tails aid fast swimming: swordfish
 

The tails of swordfish help them swim fast over long distances due to their stiffness and crescent shape.

     
  "The fast marathon swimmers of the ocean, like the tunny or the swordfish, have very stiff crescent-shaped tails. This shape also makes it easier for the fish to change direction suddenly. The tunny is the speediest of the ocean fishes, able to attain 70 kmph." (Foy and Oxford Scientific Films 1982:188)
  Learn more about this functional adaptation.
  • Foy, Sally; Oxford Scientific Films. 1982. The Grand Design: Form and Colour in Animals. Lingfield, Surrey, U.K.: BLA Publishing Limited for J.M.Dent & Sons Ltd, Aldine House, London. 238 p.
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Xiphias gladius

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 86
Specimens with Barcodes: 120
Species With Barcodes: 1
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Barcode data: Xiphias gladius

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 28 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

ACACGTTGATTTTTCTCGACCAATCACAAAGACATCGGCACCCTCTATCTAGTATTTGGTGCTTGAGCCGGTATAGTAGGCACAGCCCTA---AGTCTACTAATCCGAGCAGAACTCAGCCAACCTGGCGCCCTACTAGGGGAT---GACCAGATTTACAACGTAATCGTTACAGCTCACGCCTTTGTAATGATCTTCTTTATAGTAATGCCAATCATGATTGGAGGGTTCGGAAATTGACTAATTCCCCTAATG---ATTGGAGCCCCCGATATAGCATTCCCTCGAATGAATAACATAAGCTTCTGACTCCTCCCTCCATCATTCCTCCTCCTCCTTGCTTCTTCTGGAGTTGAAGCTGGCGCTGGAACCGGGTGAACTGTCTACCCTCCTCTAGCAGGTAACCTAGCCCACGCAGGTGCATCTGTTGACCTT---ACCATCTTCTCCCTTCACCTAGCTGGGATCTCCTCTATTCTGGGGGCAATCAACTTCATCACAACTATTATCAATATAAAACCAGCTGCCGTTTCTATGTACCAGATTCCTCTGTTCGTGTGAGCCGTACTAATTACAGCTGTCCTCCTTCTCCTCTCCCTTCCCGTTCTAGCTGCC---GGAATTACCATGCTCTTAACAGACCGTAATTTAAACACCGCCTTCTTTGACCCTGCAGGAGGTGGGGATCCCATCCTCTACCAACACCTGTTCTGATTCTTCGGCCACCCCGAAGTATATATTCTGATCCTCCCCGGCTTCGGAATAATTTCCCATATTGTTGCCTACTACTCAGGCAAAAAA---GAGCCTTTCGGCTATATGGGTATGGTATGGGCTATGATGGCCATCGGCCTTCTAGGCTTCATTGTATGAGCTCACCACATGTTTACAGTCGGAATGGATGTAGACACCCGAGCCTACTTTACATCCGCCACAATAATTATCGCTATCCCGACTGGTGTAAAAGTCTTCAGCTGGCTC---GCAACTCTGCACGGAGGT---GCTATTAAATGGGAAACCCCTCTACTATGGGCCCTTGGCTTTATTTTCCTCTTTACGGTAGGTGGACTAACTGGAATTGTCCTGGCTAATTCCTCTCTGGATATTGTGCTCCACGACACTTACTATGTAGTTGCCCACTTCCACTACGTA---CTTTCAATGGGTGCCGTCTTCGCCATTGTTGCAGCCTTTGTACACTGATTCCCCCTGTTTACGGGCTACACCCTTCACAGCACATGAACAAAAATCCACTTCGGAGTTATATTCGTCGGTGTTAACCTTACCTTCTTCCCTCAACACTTCCTAGGACTGGCTGGCATGCCTCGA---CGATATTCAGACTACCCAGATGCTTACGCA---CTGTGAAACACAGTCTCCTCTATCGGATCCTTAGTTTCTCTAGTAGCAGTTATTATGTTCCTATTTATCATTTGAGAAGCATTTACCGCCAAGCGAGAGGTT---CTCTCAGTAGAACTAACCGCCACAAAC
-- end --

Download FASTA File
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Genomic DNA is available from 3 specimens with morphological vouchers housed at British Antarctic Survey
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Conservation

Conservation Status

National NatureServe Conservation Status

Canada

Rounded National Status Rank: NNR - Unranked

United States

Rounded National Status Rank: NNR - Unranked

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NatureServe Conservation Status

Rounded Global Status Rank: GNR - Not Yet Ranked

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IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2011

Assessor/s
Collette, B., Acero, A., Amorim, A.F., Bizsel, K., Boustany, A., Canales Ramirez, C., Cardenas, G., Carpenter, K.E., de Oliveira Leite Jr., N., Di Natale, A., Die, D., Fox, W., Fredou, F.L., Graves, J., Guzman-Mora, A., Viera Hazin, F.H., Hinton, M., Juan Jorda, M., Minte Vera, C., Miyabe, N., Montano Cruz, R., Masuti, E., Nelson, R., Oxenford, H., Restrepo, V., Salas, E., Schaefer, K., Schratwieser, J., Serra, R., Sun, C., Teixeira Lessa, R.P., Pires Ferreira Travassos, P.E., Uozumi, Y. & Yanez, E.

Reviewer/s
Russell, B., Elfes, C. & Polidoro, B.

Contributor/s

Justification
Globally, this species has shown a 28% decline over three generation lengths (20 years). The only stock that is not considered to be well-managed is the Mediterranean, which comprises less than 10% of the species' global range. It is therefore listed as Least Concern, as it is below the threshold for a threatened category under Criterion A1.

History
  • 1996
    Data Deficient
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IUCN Red List: Listed, Data deficient

CITES: Not listed
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Status

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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Population

Population
The Atlantic population is comprised of three stocks that are genetically distinct: South Atlantic, North Atlantic and Mediterranean. The best scientific evidence indicates that there are four stocks of Swordfish in the Pacific Ocean (Hinton and Alvarado Bremer 2007), with centres in the northwest, northeast, southwest, and southeast. The Indian Ocean population is currently assessed as a single management unit.

The North Atlantic stock of Swordfish is not overfished and overfishing is not occurring (ICCAT 2009). The stock is rebuilding with current biomass levels increasing by 4.4% over a three generation length period based on the ASPIC base case (Figure 20, ICCAT 2009). The reduction was calculated using the first and last data points of the time series considered. The stock is considered to be under adequate management.

The South Atlantic stock was overfished and overfishing had been occurring, but at present, fishing mortality is below FMSY, stock biomass is slightly above BMSY and under current management quotas (13,700 t TAC), the stock is projected to remain above the BMSY and slightly rebuild further (ICCAT 2009). The reduction in biomass for the South Atlantic stock over three generations has been approximately 30.3% based on the ASPIC base case (Figure 30, ICCAT 2009). The reduction was calculated using the first and last data points of the time series considered. The stock is considered to be under adequate management.

The Mediterranean stock is currently considered to be overfished and stock is experiencing slight overfishing. The International Commission for the Conservation of Atlantic Tunas Standing Committee on Research and Statistics (ICCAT-SCRS) report that the Mediterranean Sea swordfish compose a unique stock separated from the Atlantic, although more research is needed to clearly define the stock boundaries. Mitochondrial 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 (Kotoulas et al. 1995). The spawning stock biomass (SSB) in 2008 was 46% below the value that would maximize yield-per-recruit. In addition, the majority of the catch includes juveniles. However, landings statistics and population parameters indicate a certain stability over the past 20 years. The estimated decline in total biomass over a three generation period (20 years) ranged from 27–50% depending on whether a regression line or first and last points of the data series were used (Figure 21, ICCAT 2010). The Mediterranean population of Swordfish was therefore regionally assessed as Near Threatened in an overview of the conservation status of Mediterranean fishes (Abdul Malak et al. 2011). This stock is not considered to be well-managed.

In the North Pacific, a two-stock scenario analysing the western and central Pacific (subarea 1) and the eastern Pacific (subarea 2) was considered the most plausible based on analyses of Japanese longline catch per unit data (CPUE) data. Using the two-stock Bayesian production model (Brodziak and Ishimura 2009), a decline of 43.9% was estimated for subarea 1, and an increase of 111.2% in subarea 2 over a three generation length period (20 years). The decline was calculated using a linear regression over the time period considered. The results indicate that the North Pacific population is stable (Brodziak and Ishimura 2010).

In the Western Central Pacific, a MULTIFAN-CL stock assessment of south-west Pacific Swordfish showed a decline in total biomass ranging from 25.7% (optimistic scenario) to 36.9% (pessimistic scenario) over three generation lengths (20 years) (Figure 29, Kolody et al. 2008). The reduction was calculated using the first and last data points of the time series considered. The stock is considered to be under adequate management.

In the Southeastern Pacific, spawning biomass is estimated to have increased by 3.3% over three generation lengths (Figure 4.4, Hinton and Maunder 2006). The percent change was calculated using a linear regression over the time period considered. The stock is considered to be under adequate management.

For the Indian Ocean, an ASPIC model showed a decline in total biomass of 57.8% over the last three generation lengths (20 years) (Figure 59, IOTC 2010). The reduction was calculated using the first and last data points of the time series considered. The model results indicate that biomass is close to the BMSY level, and that overfishing is not presently occurring. The stock is considered to be under adequate management.

Globally, this species has shown a 28% decline over three generation lengths (20 years). The only stock that is not considered to be well-managed is the Mediterranean, which comprises less than 10% of the species' global range.

Population Trend
Decreasing
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Threats

Comments: North Atlantic stock is overfished, but fishing quotas have been reduced in order to let the stock rebuild.

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Major Threats
This species is a highly important food and game species. Swordfish are caught by longline, harpoon, drift gill net, set net and other fishing gear in commercial fisheries. For the most part, swordfish captures are incidental in tuna longline fisheries. Major sport fishery areas, trolling, and drifted baited lines are located off the coast of California to Ecuador, Peru and northern Chile (Nakamura 1985). In the Mediterranean Sea, it is mostly caught by drift nets, long lines, but also by harpoons, tuna traps and sport and recreational fisheries. It is a good food fish, marketed fresh or frozen.

The largest proportion of Atlantic catches are made using surface drifting longlines, mostly by Spain, United States, Canada and Portugal. However, many additional gears are used (STECF 2009). Other directed swordfish fisheries include fleets from Brazil, Morocco, Namibia, EC-Portugal, South Africa, Uruguay, and Venezuela. The primary by-catch or opportunistic fisheries that take swordfish are tuna fleets from Chinese Taipei, Japan, Korea and EC-France. The tuna longline fishery started in 1956 and has operated throughout the Atlantic since then, with substantial catches of swordfish that are produced as a bycatch of tuna fisheries (ICCAT 2009). In the Atlantic, the Mediterranean stock is considered to be overfished and that overfishing is occurring. The stocks of the North and South Atlantic are considered to be well-managed (ICCAT 2009).

In the Indo-Pacific the main fisheries are Japan and Taiwan. Taiwan has had stable standardized CPUE trends, and Japan has shown variable CPUE trends depending on the fishing area (IOTC 2009). The Indian Ocean, Western Central Pacific and Southeastern Pacific are similarly considered to be under adequate management at present (fishing mortality below Fmsy and biomass above Bmsy; Kolody et al. 2008, IOTC 2009, Hinton and Maunder 2006).
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Least Concern (LC)
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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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Management

Conservation Actions

Conservation Actions
This is a highly migratory species, listed in Annex I of the 1982 Convention on the Law of the Sea (FAO Fisheries Department 1994).

Atlantic
There have been some changes in U.S. regulations which may have impacted catch rates, but the effects of these remain unknown. It is important to note that since 2003 the catches have been below the total allowable catches (TACs), greatly increasing chances of a fast recovery (STECF 2009). The total allowable catch in the North Atlantic during the 2007–2008 period was 14,000 t per year. The reported catch during that period averaged 11,536 t and did not exceed the TAC in any year. The total allowable catch in the South Atlantic for the years 2007 through 2008 was 17,000 t. The reported catch during that period averaged 13,365, and did not exceed the TAC in any year. There are two minimum size options that are applied to the entire Atlantic: 125 cm LJFL with a 15% tolerance, or 119 cm LJFL with zero tolerance and evaluation of the discards.

North Atlantic
Since 1994 there have been quotas and minimum size limits to restrict the harvest of north Atlantic Swordfish. There are also longline area closures in place in the U.S. Atlantic. Reduced landings have been attributed to the International Commission for the Conservation of Atlantic Tunas (ICCAT) regulatory recommendations and shifts in fleet distributions, including the movement of some vessels some years to the South Atlantic or out of the Atlantic. In addition, some fleets, including the United States, EC-Spain, EC-Portugal and Canada, have changed operating procedures to opportunistically target tuna and/or sharks, taking advantage of market conditions and higher relative catch rates of these species previously considered as by-catch in some fleets. Recently, socio-economic factors may have also contributed to the decline in catch. Consistent with the goal of the Commission’s swordfish rebuilding plan (Rec. 96-02), in order to maintain the northern Atlantic Swordfish stock at a level that could produce maximum sustainable yield (MSY) with greater than 50% probability, the Committee recommends reducing catch limits allowed by Rec. 06-02 (15,345 t) to no more than 13,700 t. This reflects the current best estimate of maximum yield that could be harvested from the population under existing environmental and fishery conditions. Should the Commission wish to have greater assurance that future biomass would be at or above BMSY while maintaining F at or below FMSY, the Commission should select a lower annual TAC, depending on the degree of precaution the Commission chooses to apply in management. The Committee noted that allowable catch levels agreed in (Recs. 06-02 and 08-02) exceeded scientific recommendations. The successful rebuilding of this stock could have been compromised if recent catches had been higher than realized. Because of the poor size-selectivity of longliners, regulating minimum landing size may inadvertently have resulted in under-reporting of juvenile catches. Alternative methods for reducing juvenile catches, such as time and/or area closures or technological changes in gear deployment, may be more effective and their utility should be further investigated (STECF 2009). Future TACs above MSY are projected to result in 50% or lower probabilities of the stock biomass remaining above BMSY over the next decade (SWO-ATL-Figure 13) as the resulting probability of F exceeding FMSY for these scenarios would trend above 50% over time. A TAC of 13,000 t would provide approximately a 75% probability of maintaining the stock at a level consistent with the Convention Objective over the next decade (ICCAT 2009).

South Atlantic
Until more research has been conducted to reduce the high uncertainty in stock status evaluations for the southern Atlantic swordfish stock, the Committee emphasizes that annual catch should not exceed the provisionally estimated MSY (15,000). Considering the unquantified uncertainties and the conflicting indications for the stock, the Committee recommends a more precautionary Fishery Management approach, to limit catches to the recent average level (~15,000 t), which are expected to maintain the catch rates at about their current level (STECF 2009). In general, catches of 14,000 t or less will result in increases in the biomass of the stock, catches on the order of 15,000 will maintain the biomass of the stock at approximately stable levels during the period projected. Catches in the order of 16,000 t or more will result in biomass decrease. The current TAC is 17,000 t (ICCAT 2009).

Mediterranean Sea
In the Mediterranean Sea, there are minimum size regulations, such as 90cm lower jaw-fork length in Spain, 140 upper jaw fork-length in Italy, 130 UJFL in Turkey. However, these minimum size regulations were cancelled because it was considered ineffective as a management tool. In Greece, the fishing season is closed from October to January. In 2009, ICCAT adopted a closed season for the Mediterranean Sea from 1 October to 31 November. The EU has banned all drift nets since January 2002 and ICCAT banned them since 2005 (some illegal drift nets still occur).

Pacific
In Chile there is a size limit for this species, and total effort for this species has declined as they moved from driftnets to longlines. However, recent catches in this region are mostly targeted by the Spanish fleet. Given the potential for rapid change in the nature of the gill-net and longline fisheries that are increasingly targeting swordfish in the Eastern Pacific region, the trends in standardized catch per unit effort should be closely monitored for indications of changing status of these stocks (Hinton 2003, Hinton and Maunder 2006). The Western Central Pacific Fisheries Commission has recommended to limit the number of boats as well as catch and effort for the southwestern stock (WCPFC 2008).

Indian
The Scientific Committee recommends that management measures focused on controlling and/or reducing effort in the fishery targeting Swordfish in the southwest Indian Ocean be implemented (IOTC 2006).
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Conservation

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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Relevance to Humans and Ecosystems

Benefits

Importance

fisheries: commercial; gamefish: yes
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Wikipedia

Swordfish

This article is about a type of fish. For other uses, see Swordfish (disambiguation).

Swordfish (Xiphias gladius; from Greek ξίφος: sword, and Latin gladius: sword), also known as broadbills in some countries, are large, highly migratory, predatory fish characterized by a long, flat bill. They are a popular sport fish of the billfish category, though elusive. Swordfish are elongated, round-bodied, and lose all teeth and scales by adulthood. 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).[2] They commonly reach 3 m (9.8 ft) in length, and the maximum reported is 4.55 m (14.9 ft) in length and 650 kg (1,430 lb) in weight.[3][4]

They are the sole member of their family Xiphiidae.[5]

Physiology[edit]

The swordfish is named after its bill resembling a sword (Latin gladius).[4] 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.[6]

They commonly reach 3 m (9.8 ft) in length, and the maximum reported is 4.55 m (14.9 ft) in length and 650 kg (1,430 lb) in weight.[3][4] The International Game Fish Association's all-tackle angling record for a swordfish was a 1,182 lb (536 kg) 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.[4] They reach maturity at 4–5 years of age and the maximum age is believed to be at least 9 years.[4] 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.[7]

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. Temperatures of 10 to 15 °C 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.[8][9] 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.[8][9]

Behavior and ecology[edit]

Contrary to popular belief, the "sword" is not used to spear, but instead may be used to slash at its prey to injure the prey animal, to make for an easier catch.[4] Mainly, the swordfish relies on its great speed and agility in the water to catch its prey. It is undoubtedly among the fastest fish, but the basis for the frequently quoted speed of 97 km/h (60 mph) is unreliable.[10]

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).[4] This highly migratory species typically moves towards colder regions to feed during the summer.[4] 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) and have exceptionally been recorded as deep as 2,878 m (9,442 ft).[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][4] 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.[11] Large prey are typically slashed with the sword, while small are swallowed whole.[4]

Swordfish are not schooling fish. They swim alone or in very loose aggregations, separated by as much as 10 m (33 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] 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, and copepods.[4]

Except for humans, fully adult swordfish have few enemies. Among marine mammals, killer whales sometimes prey on adult swordfish.[4] 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.[12] Juvenile swordfish are far more vulnerable to predation, and are eaten by a wide range of predatory fish.[4]

Reproduction[edit]

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,[3] and in water warmer than 23 °C (73 °F) and less than 75 m (246 ft) deep.[2] Spawning occurs from November to February in temperatures above 20 °C (68 °F) in the South Atlantic off southern Brazil.[3] Spawning is year-round in the Caribbean Sea and other warm regions of the west Atlantic.[4]

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 (0.063–0.071 in) in diameter and 2.5 days after fertilization, the embryonic development occurs.[3][4] The surface-living and unique-looking larvae are 4 mm (0.16 in) long at hatching.[3][4] The bill is evident when the larvae reach 1 cm (0.39 in) in length.[3]

Fisheries[edit]

Global capture of swordfish in tonnes reported by the FAO, 1950–2009[13]

Swordfish have been fished widely since ancient times, among others in the sea between Sicily and Calabria, such as off the Tyrrhenian coast in the Reggio Province. It is a typical dish in the cuisine of this region.[14]

Swordfish were harvested by a variety of methods at small scale (notably harpoon fishing) until the global expansion of long-line fishing.

Swordfish are vigorous, powerful fighters. When hooked or harpooned, they have been known to dive so quickly, they have impaled their swords into the ocean bottom up to their eyes. 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.

Recreational fishing[edit]

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. 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 five pounds or more of weight to get the baits deep enough during the day, up to 2000 ft is common. Night fishing baits are usually fished much shallower, often less than 90 metres (300 ft). 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[edit]

Swordfish are classified as oily fish.[15] Many sources, including the United States Food and Drug Administration, warn about potential toxicity from high levels of methylmercury in swordfish. [16][17] The FDA recommends that young children, pregnant women, and women of child-bearing age not eat swordfish. (See mercury in fish for more details.)

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 animals, 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.

Conservation status[edit]

Swordfish on deck during long-lining operations

Swordfish are listed as a threatened species.

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.[18]

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, 132,670 sq mi (343,600 km2) 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.[19] 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.[20]

In 2010, Greenpeace International has added the swordfish to its seafood red list.[21]

References[edit]

  1. ^ Sepkoski, Jack (2002). "A compendium of fossil marine animal genera". Bulletins of American Paleontology 364: 560. 
  2. ^ a b c d e f g h Collette, B., Acero, A., Amorim, A.F., Bizsel, K., Boustany, A., Canales Ramirez, C., Cardenas, G., Carpenter, K.E., de Oliveira Leite Jr., N., Di Natale, A., Die, D., Fox, W., Fredou, F.L., Graves, J., Guzman-Mora, A., Viera Hazin, F.H., Hinton, M., Juan Jorda, M., Minte Vera, C., Miyabe, N., Montano Cruz, R., Masuti, E., Nelson, R., Oxenford, H., Restrepo, V., Salas, E., Schaefer, K., Schratwieser, J., Serra, R., Sun, C., Teixeira Lessa, R.P., Pires Ferreira Travassos, P.E., Uozumi, Y. & Yanez, E. (2011). "Xiphias gladius". IUCN Red List of Threatened Species. Version 2011.2. International Union for Conservation of Nature. Retrieved 15 December 2011. 
  3. ^ a b c d e f g h Froese, Rainer and Pauly, Daniel, eds. (2011). "Xiphias gladius" in FishBase. December 2011 version.
  4. ^ a b c d e f g h i j k l m n o p Gardieff, S. Swordfish. Florida Museum of Natural History. Accessed 26 December 2011
  5. ^ Froese, Rainer, and Daniel Pauly, eds. (2011). "Xiphiidae" in FishBase. December 2011 version.
  6. ^ Pepperell, J. 2010. Fishes of the Open Ocean: A Natural History and Illustrated Guide. ISBN 978-0-226-65539-0
  7. ^ Jesse Marsh, Margot Stiles, 2007. "Seafood Watch, Seafood Report, Monterey Bay Aquarium, Swordfish"
  8. ^ a b Fritsches, K.A., Brill, R.W., and Warrant, E.J. 2005. Warm Eyes Provide Superior Vision in Swordfishes. Current Biology 15: 55−58
  9. ^ a b Hopkin, M. (2005). Swordfish heat their eyes for better vision. Nature, 10 January 2005
  10. ^ 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.
  11. ^ Stillwell and 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.
  12. ^ The Shark Trust. "Shortfin mako". Archived from the original on 2011-07-14. Retrieved 2011-12-26. 
  13. ^ Based on data sourced from the relevant FAO Species Fact Sheets
  14. ^ http://nuke.prolocobagnara.it/BagnaraCalabra/Storia/LaPesca/LaPescadelPescespada/tabid/495/Default.aspx http://www.biologiamarina.eu/PesceSpada.html http://www.ganzirri.it/spip.php?article9
  15. ^ "What's an oily fish?". Food Standards Agency. 24 June 2004. 
  16. ^ FDA (1990–2010). "Mercury Levels in Commercial Fish and Shellfish". Retrieved 2011-09-14. 
  17. ^ EPA. "What you need to know about mercury in fish and shellfish". Retrieved 2011-09-14. 
  18. ^ Swordfish Fenton Communications
  19. ^ NOAA/NMFS FishWatch - North Atlantic Swordfish, Retrieved on April 7, 2010
  20. ^ Seafood Watch - Seafood Report - Swordfish Monterey Bay Aquarium, 16 July 2008
  21. ^ "Greenpeace International Seafood Red List". Retrieved 14 September 2012. 
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