Istiophorus platypterus (Shaw, 1792), Indian Ocean. Some authors, such as Nakamura (1985), differentiate the Atlantic sailfish, I. albicans (Latreille, 1804), as a separate species.
OTHER COMMON NAMES
French: Voilier; Spanish: Pez vela.
Sailfishes reach a maximum size of approximately 11 ft (3.5 m) total length and 220 lb (100 kg). Body fairly compressed. Two dorsal and two anal fins, the first dorsal fin sail-like and remarkably higher than greatest body depth, with 42–49 rays. Second dorsal fin with six or seven rays, slightly posterior to second anal fin which also has six or seven rays. Pectoral fins moderate, 18–20 rays. Pelvic fins extremely long, almost reaching the anus, depressable into a groove, with one spine and several rays tightly fused together. Jaws and palatine bones with small, file-like teeth. Gill rakers absent. Left and right branchiostegal membranes broadly united. Vertebrae, 24. Swim bladder made up of many small bubble-shaped chambers.
Most researchers consider the sailfish to be a single pantropical species occurring in all three major oceans.
An epipelagic and oceanic species, usually found above the thermocline. Sailfishes have a strong tendency to approach continental coasts, islands, and reefs.
Sailfishes occasionally form schools or smaller groups of 3–30 individuals, but more often occur in loose aggregations over a wide area.
FEEDING ECOLOGY AND DIET
has been observed by fishermen: One or several sailfish locate a school of prey fish (such as sardines, anchovies, mackerel, or jack mackerel) and pursue the school at half speed with their fins half-folded back into the grooves. They then drive at the prey at full speed with fins completely folded back and make sharp turns with fins expanded to confront part of the school and strike the prey with their bills. They feed on the killed or stunned fish, usually head first as well as on a variety of fishes, crustaceans, and squid.
Spawning occurs with males and females swimming in pairs or with two or three males chasing one female. Sailfishes spawn throughout the year in tropical and subtropical waters with peak spawning in local summer seasons. Ripe ovarian eggs are approximately 0.03 in (0.85 mm) in diameter and have a single oil globule. Eggs shed from a captured female averaged 0.05 in (1.30 mm) in diameter.
SIGNIFICANCE TO HUMANS
Sailfishes are often taken as bycatch by the commercial surface tuna long liners. United Nations Food and Agriculture Organization (FAO) catch statistics for 1991–2000 show catches of 11.1–23.7 thousand tons (10.1–21.5 thousand metric tons) per year by 42 countries. Sailfishes are primarily important as a sportsfish taken by trolling at the surface. The all-tackle gamefish record is a 221-lb (100.2-kg) fish taken off Santa Cruz Island, Ecuador.
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