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 in length, and records have shown them weighing in at close to 200 pounds. Jacks are highly prized as game fish by fishers 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, and they hunt in the early morning or late afternoon hours. 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 of which are present in Hawaiian waters.
The giant trevally or white ulua is commonly observed in schools or as solitary individuals. They have a distinct steep profile head and a black spot at the base of their pectoral fin that distinguishes this species from others in the same genus. An all-black appearance can distinguish courting males, whereas females are silver in color. One of the largest jacks, they are agile pack hunters who display aggressive behavior and bite anything when curious.
*Due to the constant rotation of animals back to the ocean, we cannot guarantee the presence of any specific animal.
Maui Ocean Center will be CLOSED Sunday, AUGUST 16, 2026, due to anticipated severe weather conditions.
We plan to resume normal operations on Monday, August 17, 2026, weather permitting.
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Seascape at Maui Ocean Center restaurant will be closed on August 8, 2026 for a private event.
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