SWORDFISH / Xiphias gladius Linnaeus, 1758; XIPHIDAE FAMILY ; also called broadbill, broadbill swordfish
Found worldwide in temperate and tropical oceanic and continental shelf waters from the surface to depths of 400 500 fathoms or more. Except when spawning, adult female swordfish prefer cool, deep waters near submarine canyons or coral banks. Males prefer to remain in somewhat warmer waters.
Characteristically, the swordfish has a smooth, very broad, flattened sword (bmadbill) that is significantly longer and wider than the bill of any other billfish. It also has a nonretractable dorsal fm, rigid, nonetractable pectoral fins, and a single, but very large keel on either side of the caudal peduncle. Adult swordfish lack scales and swordfish of all sizes lack ventral fins. The back may be dark brown, bronze, dark metallic purple, grayish blue or black. The sides may be dark like the back or dusky. The belly and lower sides of the head are dirty white or light brown.
This pelagic, migratory species usually travels alone. It uses its sword for defense and to kill or stun food such as squid, dolphin, mackerel, bluefish and various other midwater and deep sea pelagic species. Occasional attacks on boats have been authenticated by the recovery of swords found broken off in wooden hafts. One swordfish attacked Alvin, the Woods Hole Oceanographic Institute submarine, at a depth of 330 fathoms and wedged its sword so tightly into a seam that it could not be withdrawn.
Fishing methods include presenting trolling baits or deep drifting at night with bait such as squid Swordfish often bask on the surface with their dorsal and tail funs protruding from the water, making them susceptible to harpooners and longliners who make the majority of swordfish catches. Swordfish ace finicky, easily frightened by an approaching boat, and rarely strike blindly. Usually the bait must be presented carefully and repeatedly before the swordfish will take it. Even then the soft mouth makes hookup uncertain and the slashing bill can sometimes make short work of an angler's line or leader. Once a swordfish has been spotted the speed of the boat should not be changed appreciably and the bait should be eased quietly and gently in front of the fish. Squid is the most popular bait, though Spanish mackerel, eel, mullet, herring, tuna and live or dead bonito are also used. To land a broadbill is considered by many to be the highest achievement in angling.
Very large swordfish are always females. The males seldom exceed 200 16 (90 kg). The meat of the swordfish is excellent eating, making this fish the object of large commercial fisheries.