XIPHIAS GLADIUS

Although it is not an Istiophorid billfish, a species that must be discussed when talking billfish depths is the swordfish. Like marlin, swordfish are capable of heating their eyes and brain, but they are regularly caught in the deep waters of the aphotic zone during the day, and much shallower at night. The swordfish has the widest range of temperature tolerance of any billfish, but it generally prefers temperatures between 64 and 72 degrees Fahrenheit. In the western North Pacific, swordfish depth residency reaches about 1,800 feet, but there have been records of them diving almost as deep as 9,500 feet. And in the western Atlantic, tagged swordfish have been found in the upper part of the water column at night but down to 1,300 feet during the day, with a record diving depth of 4,751 feet. The tremendous diving excursions taken by swordfish give them the reigning title of Diving Champions of the “Billfish” World.