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The swordfish ( Xiphias gladius), also known as the broadbill
in some countries, are large, highly migratory predatory fish characterized by a long, flat, pointed bill. They are the sole member of the family Xiphiidae. They are a popular sport fish of the billfish category. 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 , and can typically be found from near the surface to a depth of , and exceptionally up to depths of 2,234 m. They commonly reach in length, and the maximum reported is in length and in weight.
Several extinct genera are known, such as a large sized Xiphiorhynchus and Aglyptorhynchus. Unlike modern taxa these have equally long lower jaws.
They reach maturity at 4–5 years of age and the maximum age is believed to be at least 9 years. The oldest swordfish found in a recent study were a 16-year-old female and 12-year-old male. Swordfish ages are derived, with difficulty, from annual rings on fin rays rather than , since their otoliths are small in size.
The swordfish is one of 22 species of fish – including the marlin, tuna, and some sharks – known to have a heat-conservation mechanism.
Mainly, the swordfish relies on its great speed and agility in the water to catch its prey. It is no doubt among the fastest fish, but the basis for the frequently-quoted speed of is unreliable. Research on related marlin ( Istiophorus platypterus) suggest a maximum value of is more likely.
Swordfish are not schooling fish. They swim alone or in very loose aggregations, separated by as much as from a neighboring swordfish. They are frequently found basking at the surface, airing their first dorsal fin. Boaters report this to be a beautiful sight, as is the powerful jumping for which the species is known. This jumping, also called breaching, may be an effort to dislodge pests, such as or lampreys. Swordfish prefer water temperatures between , but have the widest tolerance among billfish, and can be found from . This highly migratory species typically moves towards colder regions to feed during the summer. Swordfish feed daily, most often at night, when they rise to surface and near-surface waters in search of smaller fish. During the day, they commonly occur to depths of and have exceptionally been recorded as deep as . Adults feed on a wide range of pelagic fish, such as mackerel, , silver hake, Sebastes, herring, and , but they also take demersal fish, squid, and . 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 Gadidae, , Stromateidae, bluefish, and sand lance. Large prey are typically slashed with the sword, while small are swallowed whole.
Fully adult swordfish have few natural predators. Among marine mammals, sometimes prey on adult swordfish. It is believed that may also prey on swordfish on rare occasions. The shortfin mako, an exceptionally fast species of shark, sometimes take on swordfish; dead or dying shortfin makos have been found with broken-off swords in their heads, revealing the danger of this type of prey.The Shark Trust. Juvenile swordfish are far more vulnerable to predation, and are eaten by a wide range of predatory fish. Intensive fishery may be driving swordfishes and sharks into harder competition for reduced amounts of prey and therefore pitting them to fight more.
Human fishery is a major predator of swordfishes. The annual reported catch in 2019 of the North Atlantic swordfish amounted to a total of .
Large females can carry more eggs than small females, and between 1 million and 29 million eggs have been recorded. The pelagic eggs measure in diameter and days after fertilization, the embryonic development occurs. The surface-living and unique-looking larvae are long at hatching. The bill is evident when the larvae reach in length.
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.
Various ways are used to fish for swordfish, but the most common method is deep-drop fishing, since swordfish spend most daylight hours very deep, in the deep scattering layer. The boat is allowed to drift to present a more natural bait. Swordfishing requires strong fishing rods and reels, as swordfish can become quite large, and it is not uncommon to use or more of weight to get the baits deep enough during the day, up to is common. Night fishing baits are usually fished much shallower, often less than . Standard baits are whole mackerel, herring, mullet, bonito, or squid; one can also use live bait. Imitation squids and other imitation fish lures can also be used, and specialized lures made specifically for swordfishing often have battery-powered or glow lights. Even baits are typically presented using glow sticks or specialized deepwater-proof battery operated lights.
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.
The resulting "Give Swordfish a Break" promotion was wildly successful, with 750 prominent U.S. chefs agreeing to remove North Atlantic swordfish from their menus, and also persuaded many supermarkets and consumers across the country.
The advertising campaign was repeated by the national media in hundreds of print and broadcast stories, as well as extensive regional coverage. It earned the Silver Anvil award from the Public Relations Society of America, as well as Time magazine's award for the top five environmental stories of 1998.
Subsequently, the U.S. National Marine Fisheries Service proposed a swordfish protection plan that incorporated the campaign's policy suggestions. Then-US President Bill Clinton called for a ban on the sale and import of swordfish and in a landmark decision by the federal government, of the Atlantic Ocean were placed off-limits to fishing as recommended by the sponsors.
In the North Atlantic, the swordfish stock is fully rebuilt, with biomass estimates currently 5% above the target level. No robust stock assessments for swordfish in the northwestern Pacific or South Atlantic have been made, and data concerning stock status in these regions are lacking. These stocks are considered unknown and a moderate conservation concern. The southwestern Pacific stock is a moderate concern due to model uncertainty, increasing catches, and declining catch per unit effort. Overfishing is likely occurring in the Indian Ocean, and fishing mortality exceeds the maximum recommended level in the Mediterranean, thus these stocks are considered of high conservation concern.
In 2010, Greenpeace International added the swordfish to its seafood red list.
In 2024, Giulia Manfrini, an Italian surfer died in a rare incident after being struck by a swordfish while surfing off the coast of West Sumatra, Indonesia.
The word swordfish is used as a password in the 1932 Marx Brothers film Horse Feathers. It has since appeared as a password in many films, television series, books, and videogames.
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