An oceanic species occurring above and below the thermoclines. Pelagic in open water , but rarely seen near reefs. They school primarily by size, either in monospecific or multi-species groups. Larger fish frequently school with porpoises, also associated with floating debris and other objects. Feed on fishes, crustaceans and squids. It is sensitive to low concentrations of oxygen and therefore is not usually caught below 250 m in the tropics. Peak spawning occurs during the summer, in batches. Eggs and larvae are pelagic. Encircling nets are employed to catch schools near the surface. Marketed mainly frozen and canned , but also fresh and smoked. Highly valued for sashimi.