They feed on a variety of fish and squid, foraging over great depths and distances. They are formidable opponents when harpooned and have been known to pierce the sides and planks of ships with their swords. In recent years, longlines light cables suspended by floats near the ocean surface with baited hooks on short lines spaced over its length have been used to catch swordfish and have proven to be more successful and effective than harpooning.
Swordfish are available as fresh or frozen steaks and chunks and can be pan-fried, baked, broiled, barbecued, smoked, poached or cut into 1-inch cubes for kabobs. Keep swordfish refrigerated at degrees F. Recently, the US government took measures to protect juvenile north Atlantic swordfish stocks by closing swordfish nursery areas to fishing.
Coupled with an international swordfish recovery plan , swordfish populations are on the road to recovery. The IUCN is a global union of states, governmental agencies, and non-governmental organizations in a partnership that assesses the conservation status of species. The swordfish is found in oceanic regions worldwide, including the Atlantic, Pacific, and Indian Oceans.
The swordfish is a highly migratory species, generally moving to warmer waters in the winter and cooler waters in the summer. It is often present in frontal zones, areas where ocean currents collide and productivity is high. The swordfish is commonly observed in surface waters, although it is believed to swim to depths of 2, feet m or greater, where the water temperature may be just above freezing. Blood is supplied to the tissue through a specialized vascular heat exchanger, similar to the counter current exchange found in some tunas.
This helps prevent rapid cooling and damage to the brain as a result of extreme vertical movements. The bill is long relative to other billfishes and adults lack teeth in the jaws. While the young have scales, these are lost by the time the fish attain a body length of about 3 feet 1 m.
Adults lack scales and teeth. The body is generally cylindrical. Two dorsal fins are present, although the second is quite small, separated from the first, and set far back on the body. The first dorsal fin is high and rigid. Likewise, there are two anal fins, although again the second is considerably smaller than the first. Pelvic fins are absent.
The caudal fin is lunate, while the caudal peduncle has a pronounced keel on either side. The lateral line is also present in specimens up to 3 feet 1 m in body length, but it too is lacking in adulthood.
Prior to adulthood, swordfish morphology changes greatly, as described below. Coloration The color is blackish-brown above, fading to a lighter shade below.
The fins are brown or dark brown. Size, Age, and Growth Swordfish reach a maximum size of in. Females are larger than males of the same age, and nearly all specimens over lbs. Pacific swordfish grow to be the largest, while western Atlantic adults grow to lbs. The IGFA all tackle record is lb. Swordfish reach sexual maturity at years of age, with a maximum lifespan of at least 9 years. They feed mostly upon pelagic fishes, and occasionally squids and other cephalopods. At lower depths they feed upon demersal fishes.
The sword is apparently used in obtaining prey, as squid and cuttlefishes commonly exhibit slashes to the body when taken from swordfish stomachs. A recent study found the majority of large fish prey had been slashed, while small prey items had been consumed whole. Larval swordfish feed on zooplankton including other fish larvae. Juveniles eat squid, fishes, and pelagic crustaceans. Reproduction Swordfish have been observed spawning in the Atlantic Ocean, in water less than ft.
Estimates vary considerably, but females may carry from 1 million to 29 million eggs in their gonads. Similarly, swordfish are eaten by a wide variety of predators.
When they are newly hatched, they are eaten by other fishes that specialize on eating plankton. The size of their predators increases as they grow, and adult swordfish are not eaten by anything other than large toothed whales and some open ocean shark species.
During spawning, male-female pairs form, but they reproduce through external rather than internal fertilization, where the female releases her eggs into the water column while the male releases his sperm. Once the sperm find the eggs, fertilization occurs. While spawning, a single female may release several million eggs, increasing the likelihood that some will be fertilized and that at least one hatched larva will grow to reach adulthood.
Though almost all fishes are cold blooded, swordfish have a specialized blood vessel structure — called a countercurrent exchanger — that allows them to warm their brains and eyes. This adaptation provides them with a major advantage when hunting in cold, deep water, by allowing them to think more quickly and see more clearly. The swordfish is a highly prized food fish and is fished heavily throughout its range.
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