With its very long beak and body aerodynamicswordfish is unlike any other species. Close-up on one of the most fast of the ocean.
Swordfish, sword fish
Swordfish (Xiphias gladius) is a species of fish pelagic tropical and temperate seas, belonging to the order of Perciformes. He is the sole representative of the family of Xiphiidae. Its scientific name comes from the association of two words: xiphias in Greek (sword) and gladius in Latin (sword), evoking his rostrum, main characteristic of this fish. The size of the animal is on average 3 meters and its weight is 400 kilos.
Swordfish: a long, flat beak
The swordfish is distinguished from other fish by its very long flattened beak, or rostrum, which can exceed the third of the total length of the animal. The elongated body of the swordfish takes on a color grey, blue on the back, silver on the sides and white on the ventral part. Sporting large round black eyes, the adult animal is devoid of teeth and D’scales. It has a pair of pectoral fins triangular, placed symmetrically with respect to its dorsal fin. Shaped like a crescent moon, its tail fin helps it to slice through the water with ease and speed.
Swordfish, an ectothermic animal
The swordfish is an ectothermic animal, that is to say that its organism produces little or no heat. However, it does have special organs located near the eyes that warm them to improve vision and make it easier to spotting of its prey. Such a capacity is only observed on a few species of predatory fish such as marlin, tuna and some sharks. The swordfish is thus endowed with good visual acuity, allowing it to evolve in thedarkness from the depths.
The swordfish, cut for speed
Like many large pelagics, swordfish are very lively swimming and sculling virtuoso. The combination of its long rostrum, its aerodynamic body, its powerful muscles and a modest weight compared to its size allows it to reach top speeds of the order of 110 km / h. As such, it is among the fastest fish in the ocean. This animal rather solitary can however swim in groups, keeping a distance of ten meters with its congeners. Swordfish offer a spectacular view when they leap out of the water.
Swordfish: preferably the ocean
The range of swordfish is in the oceans Indian, Atlantic and Pacific as well as in the Sea of Marmara, the Black Sea or the Mediterranean. This pelagic and mainly oceanic fish generally lives between 200 and 600 meters deep and in waters with a temperature between 18 and 22 ° C. However, it can go looking for its prey, especially cephalopods, up to 700 meters deep in waters at 7 ° C. Very mobile, swordfish often migrate to warmer waters in winter and colder in summer.
The swordfish knocks out its prey
Swordfish feed on a wide variety of fish, particularly species that form benches like exocets, herrings, anchovies and mackerel. It also feeds on crustaceans and cephalopods (squid, cuttlefish, squid). The predator uses its vision adapted to a wide spectrum of light to hunt both day and night. To capture its prey, swordfish beats its rostrum in concentrations of fish to knock out its victims and feast on them.
Swordfish: its eggs over the water
The swordfish is mature sexually around the age of 5-6 years. The mating season usually begins in late spring and continues throughout the summer. In Mediterranean, reproduction takes place in July and August when the water temperature reaches 22 ° C. At this time, swordfish congregate in areas of spawning : the females lay their eggs in open water which are then fertilized by the sperm of the males and dispersed by the currents.
The rapid growth of swordfish
Upon hatching, the larvae develop in the plankton. Measuring about 4 mm at birth, the fry already has its rostrum but remains vulnerable and must escape its predators for long weeks. It feeds on the larvae of other fish and zooplankton. When the young reach 1 meter long – including the rostrum – their teeth and scales shrink and then disappear. They consume small crustaceans (amphipods, mysids, etc.). The swordfish shows a very rapid growth during the first years of life. At the age of one year, the juveniles measure between 80 and 90 cm without the rostrum. Females grow faster than males and reach sizes superior their.
Swordfish: a declining population
The numbers of swordfish fell particularly in Mediterranean. Highly prized in commercial and recreational fishing, swordfish have seen a decline in 70% of its population in thirty years. The vast majority of fish caught that did not reach the sexual maturity, they cannot reproduce. In 2016, the International Commission for the Conservation of Atlantic Tunas (ICCAT) established a management plan Mediterranean swordfish over the next fifteen years (catch quotas per country, minimum size and age, etc.) in order to preserve stocks. The longevity swordfish is 15 years in the Atlantic and 10 years in the Mediterranean.