The jacks, or trevally, are a family of strong-swimming predators frequently seen at drop-offs or near reefs. Usually silvery in color, most have streamlined bodies with varying body shapes across genus and forked tails. For most species, the base of the tail is slender and usually reinforced by specially strengthened scales called scutes.
Jacks can grow to over five feet and records have shown close to 200 pounds. Jacks are highly prized as a game fish by fisherman, because of their size and their ability to put on a fight. Jacks are abundant in the Northwestern Hawaiian Islands where they are protected. Schools are frequently seen near reefs or drop-offs, hunting in the early morning or late afternoon. Typically feeding on other fishes, they can also be seen foraging on the bottom for crustaceans and other invertebrates. There are about 140 species of jacks worldwide, 24 occur in the Hawaiian Islands.
The Giant trevally or White ulua is commonly observed in schools or as solitary individuals, on occasion, near shore. They have a distinct steep profile head and a black spot at the base of the pectoral fin that distinguishes this species from other in the same genus. Courting males can be distinguished by an all black appearance and females silver in color. One of the largest of all jacks, they are agile pack hunters displaying aggressive behavior and when curious will bite anything.
*Due to the constant rotation of animals back to the ocean, the presence of any specific animal cannot be guaranteed.