Swordfish: Characteristics, Fishing and Attacks on Humans and Sharks

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Swordfish (Scientific name: Xiphias gladius) are a large billed fish that can weigh up to 590 kilograms (1300 pounds) and reach lengths of 4.5 meters (15 feet). The biggest swordfish ever caught by a fisherman was caught in Chile in 1953. It weighed 536 kilograms (1,181 pounds). One gigantic swordfish measured 6 meters (20 feet) long was captured by commercial fishermen, making it the longest of all bony fish (some species of non-bony sharks are larger).

Found in tropical and temperate — and sometimes cold — waters, around the globe, they are a popular fish among sportsmen and seafood gourmets. Aristotle wrote the swordfish "leaps out of the sea as high as the dolphin" to get rid of parasitic copepods. The "little worm...which resembles a scorpion, and is about the size of a spider, causes them to suffer.”

Also known as broadbill swordfish, espada, emperado, a’u, mekajiki and shutome, swordfish are regarded the world's fastest swimmers along with marlin and sailfish. They can reach speed of around 65 miles per hour.

Swordfish are found in the Atlantic, Indian, and Pacific Oceans, including the waters around the U.S. Pacific Islands and off the U.S. West Coast. Swordfish live in surface water to mid-water but feed throughout the water column. Scientists know little about the migration of Pacific swordfish, but tagging data suggest swordfish move eastward from the central Pacific, north of Hawaii, toward the U.S. West Coast..

Websites and Resources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se ; Encyclopedia of Life eol.org ; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems


swordfish swimming

Billfish bills are elongated upper jaws. The are use them to harpoon and batter prey and likely wield them against predators such as sharks. Billfish such as swordfish, sailfish and marlin have the ability to regurgitate their stomachs and reswallow them without suffering any ill effects. They do this to rid themselves of spines, beaks, bones and teeth of the prey they consume.

Even though large billfish are often called bulls, they are usually females. Females are considerably larger than males. Some species have long bills relative to their bodies weeks after they are born. Swordfish don’t begin developing their bills until they are a couple of feet long.

There have been some reports of marlin, swordfish and other billfish ramming and attacking small boats, including ones with copper-sheathed hulls — and sinking them. One Dutch explorer wrote in his log in 1618, "there was such a noise...knowing not what meant." Back in port "we found a Horne sticking in the Ship, much like for thickness...a common Elephants tooth" and it “penetrated three planks and turned upward."

Swordfish Characteristics

Swordfish have a long, flattened bill that looks like a sword, as their name implies. They are gray in color and have a stout, rounded body and large eyes. Their first dorsal fin is tall and crescent-shaped. The second is much smaller. Their anal fins are similar in shape to the dorsal fins but smaller. They have a broad, crescent-shaped tail. Their color is darkest on top, generally black or brown. Adult swordfish have no teeth or scales. [Source: NOAA]

Swordfish are one of the fastest and largest predators in the ocean. Their streamlined body allows them to swim at high speeds, up to 50 miles per hour. They grow rapidly, reaching a maximum length of 4.2 meters (14 feet) and almost 544 kilograms (1,200 pounds) (although the average size caught in the fishery is 22-90 kilograms, 50–200 pounds).

The body of swordfish widens and then tapers to a narrow tail. Their dorsal and tail fins raise high like sails, enabling the fish to maintain relatively high speeds for long periods of time. Swordfish look bronze and bluish grey out of the water but appear white in the water. The only color comes from it bright blue eyes, which are very close to the mouth.

Swordfish Feeding and Hunting

Swordfish feed on a variety of fish and invertebrates such as squid. They capture their prey by slashing their bills back and forth, stunning or injuring the prey in the process. Adult swordfish are usually solitary hunters. Like tuna and marlin it has two sets of swimming muscles. White ones used for short bursts of speed when making attacks and dark red ones used for cruising long periods of time. They have developed unique characteristics, such as special eye muscles and a heat exchange system that allow them to swim in deep cold water in search of prey.

The swordfish bill is flat, bony extension of the fish's upper jaw. It makes up a third of the fish's total length and is clearly used as a weapon. Swordfish catch food by surging into a school of herring, mackerel or squid and slashing around with its bill, injuring and stunning prey that they catch and later slices up into bite size pieces or eat whole. The bill is also used as a defense against predators such as sharks.

Swordfish feed at the top of the food chain and are rarely preyed upon by other animals but they are sometimes hunted by mako sharks and blue sharks. Juvenile swordfish are sometimes eaten by shark,s and larger predatory fish including tuna, marlin and several species of sea lampreys.

Swordfish Reproduction, Development and Populations

Atlantic swordfish

Swordfish are able to reproduce when they reach 5 to 6 years old. They spawn numerous times throughout the year near the surface of warm tropical and sub-tropical waters. In cooler waters, they spawn several times during the spring and summer. Swordfish are productive, and their eggs are fertilized externally and float at the sea surface where they incubate for about 2 1/2 days.

Swordfish spawn throughout the year, especially between April and September. There are swordfish spawning grounds off of Sicily and Cuba. The eggs resemble little globes. Baby swordfish look nothing like adults. They have a translucent body and their head is covered with spikelike projections. The bill begins to appear when the swordfish is two to three feet long.

There are two stocks of North Pacific swordfish: the Eastern Pacific Ocean stock and the Western and Central North Pacific Ocean stock. According to the most recent stock assessments: The Eastern Pacific Ocean stock is not overfished but is subject to overfishing (2014 stock assessment). The Western and Central North Pacific Ocean stock is not overfished and is not subject to overfishing (2018 stock assessment). There are above target population levels in both stocks. The fishing rate is at recommended level in the Western and Central North Pacific but is reduced to end overfishing in the Eastern Pacific. [Source: NOAA]

Sharks Impaled by Swordfish

The sharks don’t always win their battles for food and survival. A number of sharks impaled by swordfish have washed up on Mediterranean shores, backing up old fishermen’s tales about battles between the two marine predators. Joshua Sokol wrote in the New York Times: The first victim washed up in September 2016. The police in Valencia, Spain, saw a blue shark dying in the surf along a tiny stretch of beach. They lugged the 8-foot corpse to the yard behind the police station. Then they called Jaime Penadés-Suay, who soon suspected foul play. The shark had what looked like a bit of wood embedded in her head. He pulled. Out slid a broken fragment from a swordfish sword that had lanced straight through her brain. “I thought it was crazy,” said Penadés-Suay, a graduate student at the University of Valencia and a founder of LAMNA, a Spanish consortium that studies sharks. “I was never sure if this was some kind of joke.” [Source: Joshua Sokol, New York Times, October 28, 2020]

“But since then at least six more sharks have washed up on Mediterranean coasts, each impaled with the same murder weapon, and almost always in the head. In the latest example, an adult 15-foot thresher shark — itself equipped with a whiplike tail capable of stunning blows — washed up in Libya. Inside was a foot of swordfish sword that had broken off near its heart.Taken together these cases offer what may be preliminary scientific evidence of high-speed, high-stakes underwater duels that had previously been confined to fisherman’s tales.

Pacific swordfish

Historically, whalers, fishermen and scholars saw swordfish as stab-happy gladiators. But modern scientists were skeptical. Sure, swordfish sometimes impale boats, whales, submarines and sea turtles. But perhaps these swordfish had aimed for smaller prey and rammed something else by mistake. Or maybe not. When sharks die, their bodies typically sink to the bottom of the sea. So a published record of half a dozen stranded sharks with suspiciously precise wounds could indicate that these encounters are common — and that a swordfish sword is sometimes exactly what it sounds like. “Now at least we have evidence that they might use it really as a weapon, intentionally,” said Patrick Jambura, a graduate student at the University of Vienna.

Jambura led a study of the recent dead thresher shark, which turned up in April. Sara Al Mabruk at Omar Al-Mukhtar University in Libya had spotted a video posted by local citizen scientists. In the video, a man approaches a shark on the beach, then pulls a sword from its back like a bizarre twist on Arthurian legend. “I was like, ‘Oh come on Sara, we have to do something about this. That’s just incredible,’” Jambura said. It’s also puzzling, their team reported in October 2020 in the journal Ichthyological Research. Fishermen often catch swordfish with mangled swords, so breaking one isn’t fatal, but they do help their owners swim faster and feed. And they don’t seem to grow back, at least not for adults. So why do some swordfish risk losing them?

Most victims of swordfish stabbings in the Mediterranean have been blue or mako sharks. Both of those species prey on young swordfish, suggesting one explanation: Maybe juvenile swordfish had felt like their lives were threatened and fought back. But this time the sword fragment looked as if it had come from an adult swordfish, which typically are not eaten by a thresher shark. Instead, they argue, the swordfish might have been taking out an ecological rival. In the overfished Mediterranean, the swordfish might have fought to ensure a larger share of the remaining scraps. Penadés-Suay doubts competition would be enough of a motive given the risks involved in taking on a big, whip-tailed shark. Instead, he thinks, the swordfish might have felt attacked and tried to protect its territory.

Either way, scientists know little about the behavior. After partnering with a seafood company, Penadés-Suay is now working to measure both 1,000 swords and the overall size of the fish that wielded them. That should help scientists extrapolate from the little crime-scene shards left in sharks to the full swordfish that did the deed. Scientists searching for these rare incidents also want to hear from the public. “Maybe a fisherman for 13 years has been catching sharks, and every year he finds this,” Penadés-Suay said. “We need everybody to be looking into this.”

Swordfish Fishing

Commercial fishing for swordfish with longlines

Off the U.S. West Coast, recreational fishermen fish for swordfish with rod-and-reel gear. They are prohibited from selling their catch. Fishermen must have a fishing license to catch and land swordfish and are allowed to keep two swordfish per day. There are no federal regulations for recreational fishing off Hawaii and U.S. Pacific Island territories, but local rules may apply.[Source: NOAA]

Commercial passenger fishing vessels must have a permit and keep a monthly log of their fishing activity. In 2021, the commercial landings in the U.S. of swordfish 860,000 kilograms (1.9 million pounds) and were valued at $7.4 million, according to the NOAA Fisheries commercial fishing landings database. Fishing gear used to catch Pacific swordfish rarely contacts the seafloor so habitat impacts are minimal. Regulations are in place to minimize bycatch.

Commercial fishermen use longline gear to harvest swordfish in federal waters off of Hawaii and on the high seas. In federal waters off the West Coast, commercial fishermen harvest swordfish using drift gillnets and harpoons, and using deep-set buoy gear authorized under exempted fishing permits in recent years. The majority of North Pacific swordfish landed in California is landed by Hawaii-based vessels. Hawaii-based longliners accounted for the majority of U.S. catch of North Pacific swordfish. Fishing gear used to catch swordfish rarely contacts the seafloor so habitat impacts are minimal. Longlines and gillnets can incidentally catch sea turtles, marine mammals, seabirds, sharks, and other finfish species. Gear restrictions and operational requirements are in place to minimize bycatch. U.S. longline and drift gillnet vessels operate under regulations to minimize impacts on other species.

NOAA Fisheries and the Pacific Fishery Management Council manage the North Pacific swordfish fishery on the West Coast. The species are managed under the Fishery Management Plan for U.S. West Coast Fisheries for Highly Migratory Species: 1) Fishermen are required to have permits and to record catch in logbooks. 2) Gear restrictions and operational requirements are in place to minimize bycatch. 3) Longline and drift gillnet fishing boats are required to carry observers when requested. 4) Longline fishing is prohibited within 200 miles of the U.S. West Coast. 5) Longline fishing regulations vary by gear type (shallow-set, deep-set, etc.) and fishing area (eastern Pacific, high seas, etc.). 6) Drift gillnets are allowed in federal waters but not in state waters. 7) Time and areas closures are in place to protect leatherback and loggerhead sea turtles. 8) Training in safe handling and release techniques for protected species is required and all longline vessels must carry and use specific equipment for handling and releasing these animals.

Management of highly migratory species, like Pacific swordfish, is complicated because the species migrate thousands of miles across international boundaries and are fished by many nations. Effective conservation and management of this resource requires international cooperation as well as strong domestic management.

swordfish from Kos, Greece

Two organizations, the Inter-American Tropical Tuna Commission (IATTC) and the Western and Central Pacific Fisheries Commission (WCPFC), manage this fishery internationally. Historically, the International Scientific Committee for Tuna and Tuna-like Species in the North Pacific Ocean (ISC) conducted stock assessments to determine the status of both the Western and Central North Pacific Ocean stock and the Eastern Pacific Ocean stock of swordfish. The IATTC conducted the most recent stock assessment for the Western and Central North Pacific Ocean stock. Working with the U.S. Department of State, NOAA Fisheries domestically implements the IATTC and WCPFC conservation and management measures.

The World Wildlife Fund (WWF) condemned as weak and insufficient a decision to set the minimum size of swordfish allowed to be caught at 90 centimeters (three feet). Jaime Penadés-Suay at University of Valencia told the New York Times that despite how plentiful swordfish are in restaurants and at grocery store fish counters. “Commercial species are only studied for commercial purposes, and that’s a problem.”

Largest Swordfish Ever Caught with a Rod and Reel

According to the International Game Fishing Association (IGFA) the largest swordfish ever caught weighed 536 kilograms (1,182-pounds). It was caught on May 7, 1953 by Louis E. Marron off Iquique, Chile. He was fishing with his wife, Genie, aboard Flying Heart III skippered by Capt. Eddie Wall. The fish was landed in just under two hours after it took a trolled bonito as bait. He used a Black Palm rod and 12/0 Fin-Nor Reel with 39-thread Cortland Super Cutty line. [Source: Marlin magazine]

In May 2018, George Lirantzis and three other members of the Ulladulla Game Fishing Club caught a 436-kilogram (961-pound) swordfish — the second biggest in the world — off the coast of Mallacoota, New South Wales, Australia using 130 pounds of bait. [Source: Brendan Cole, Newsweek May 31, 2018]

Newsweek reported: The quartet had to wrestle the fish for nearly two hours to get it onto the deck of their boat. "When we got the bite of the big one it came screaming up to the surface. We saw it jump out, which was unusual because most of them go back down," Lirantzis told the Illawarra Mercury. "This one stayed on the surface for the whole fight. It was within 50 meters of the boat for the entire fight.It spent the whole time on the surface giving us some explosive jumps. When we finally got it boat side, we all struggled for over an hour to get it in the boat. ... We didn't realize it was going to be second biggest in the world," he said.

The fish beat the previous Australian record of 769 pounds — set by a Melbourne man only a week before — by almost 200 pounds. However, it will not be officially ratified by the Game Fishing Association of Australia (GFAA) because of the equipment used. The monster fish is now in cold storage, and it will be taxidermied and processed for food. Scientists will examine the head and fin to determine its age. The oldest such fish on record was 17 years old and weighed 765 pounds. Lirantzis told Newsweek he would be giving the fish to family and friends. "I hate freezing it, so I will give it out to as many people I know fresh to enjoy it. It's the best-tasting fish you can ever eat," he said.

[Source: Marlin magazine marlinmag.com ]

People Impaled and Killed by Swordfish

According to doctors in Malaysia: There have been very few reports of swordfish attacks on humans and none have resulted in death though there have been several reports of attacks resulting in body and chest injuries. Although there are no reports of unprovoked attacks on humans, swordfish can be very dangerous when provoked and they can jump and pierce their swords into their targets. We describe here an unusual case of death that resulted from intracranial penetrating injury caused by a swordfish. [Source: Swordfish Attack—Death by Penetrating Head Injury by Boon Hui Gooi, W. Khamizar and M.N. Suhani,1 Departments of Surgery and Forensic Pathology,, Hospital Alor Star, Kedah, Malaysia.

Case report: A 39-year-old fisherman was attacked by a swordfish which jumped towards him and pierced his right eye when he flashed a torch light at the water from his fishing boat. He was immediately rushed to the nearby hospital by his companion. Clinical examination revealed a swollen right eye with penetrating wound at the upper eyelid. He was later referred to our hospital for the apparent eye injury. However, on arrival at the hospital, about 20 hours after the incident, he became unconscious with a Glasgow Coma Scale score of 7. He was intubated and the computed tomography scan showed proptosis of right eye with subarachnoid haemorrhage and cerebral oedema at the right frontal region. Pneumocranium was also noted.

He was ventilated for cerebral protection and covered with intravenous antibiotic. Unfortunately, the patient deteriorated rapidly with hyperpyrexia and hypotension despite adequate fluid resuscitation and inotropic support. He succumbed 1 day after admission. The cause of death from postmortem examination was impalement of the head by swordfish. There was a penetrating laceration through the right upper eyelid that had traversed through the right orbit, with subsequent penetration into the third ventricle and cavernous sinus through the right optic canal and the right superior orbital fissure.

The attack was possibly provoked by the flashing light which the fish thought to be food. It was very unfortunate that the sword penetrated into the cranium via the optic foramen and injured the vessels inside the subarachnoid space. The cerebral oedema following the injury was rapidly fatal despite the usual supportive treatment provided for such head injuries.

In 2002, a Florida fisherman was hospitalized after being stabbed with a swordfish in a fight with another fisherman.. In 2015, a Hawaiian fisherman died in struggle with swordfish he speared in a harbor on the Big Island. he fish struck him in the chest with its sharp bill. Reuters reported: “The man, a captain in the charter fishing business, saw the swordfish in the Honokohau small boat harbor and jumped into the water to catch it, the state Department of Land and Natural Resources said. [Source: Reuters, May 30, 2015]

“Witnesses say he speared the fish but it struck him in the chest with its spear-shaped bill, according to the department. Onlookers pulled the unresponsive man out of the water and performed CPR until paramedics took him to a hospital where he was pronounced dead, the department said in a statement. The man was not named in the statement but local television station KITV identified him as 47-year-old Randy Llanes. "He was a tough guy, he was such a tough guy that everyone's scared of him, the whole harbor's scared of him," Kalina Llanes, the man's sister-in-law, told the station. She added that those who knew him well were "not scared of him because he has such a big heart." KITV showed an image of the fish, which according to the Department of Land and Natural Resources measured 3 feet long with a bill that extended another 3 feet, lying dead at the water's edge.

Image Sources: Wikimedia Commons, NOAA

Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.

Last Updated April 2023

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