| Biology: |
Caught with set nets and drifting jigs (Ref. 417). Maximum mantle length of both sexes is the same, 100 cm, possibly to 130 cm (Ref. 97142). Maximum depth from Ref. 104455. An oceanic species (Ref. 83938), only rarely approches the shelf zone (Ref. 122970). Occupies epipelagic to upper mesopelagic depths, and undergoes diel vertical migrations. Cosmopolitan, common circumglobal inhabitant of warm tropical and subtropical open waters, only rarely approaching the shelf zone (Ref. 97142). Occurs in a front (Ref. 122966). Avoids the oligotrophic central waters of the open ocean. Also reaches higher latitudes into temperate boreal and notalian regions, transported by warm currents, e.g. the Tsushima, Kuroshio, Agulhas, Brazil Currents and the Gulf Stream. Not an active swimmer during most of its life cycle, rather, it propels itself slowly by gentle undulation of its long, broad, diamond-shaped fins. However, is capable of a powerful reactive jet of short duration when threatened. Such low-energy life style promotes very high growth rates, among the highest of all squids. By the age of 300 days, may reach 800 mm mantle length and 17.5 kg body weight. Males reach maturity mainly at 400 to 550 mm mantle length (age 170 to 200 days), and females mature at 550 to 650 mm mantle length (age 230 to 250 days). Life span is 1 year. Spawning lasts throughout the year in tropical waters and during the warm season in peripheral regions. Spawning is intermittent, with multiple fillings and evacuations of the oviducts. Mating occurs in the "head to head" position. The social organization is unique among squids: consists of pairs formed of same-sized males and females that occur at an immature stage of less than 100 mm mantle length, and probably remain together constantly during their lifetimes (monogamy). Small schools of pairs may be locally common. Arm length and probably the anal photophore play the key role in pair formation in immature squids. Juveniles feed on crustaceans, small cephalopods and fishes in subsurface waters, but subadults and adults feed mainly in daytime in deep-water layers mostly from 400 to 650 m on dense concentrations of non-active midwater fishes. Predators include different species of ommastrephid squids, dolphin fish, lancet fish, various species of tuna, swordfish, Gempylus serpens, sharks and mammals (e.g. dolphins, rough-toothed dolphin, false killer whale, sperm whale). Valued for its firm and flavorful flesh, its high commercial value makes it an important target species along the coastal waters of the Sea of Japan and around Okinawa (Ref. 97142). |
