Jacks

This fish plays an important role in the reefs ecosystem and fisheries. They are a kind of schooling fish that can reach 10, 000 individuals in size. One of the common jacks in Pulau Kapas is the blue runner, which is also known as the bluestripe jack. Carangidae is the family name of the jack family. There are 17 species in the genus Caranx. Their maximum length and weight are 70 cm and 5 kg.

This species inhabits predominantly over coral reefs. They are schooling fish. The schooling size can reach 10,000 individuals. They predate on small fishes, shrimps, lobsters, jellyfish, and other invertebrates. As one of the members of complex oceanic food wed, the blue runners are being preyed upon many larger species such as birds, dolphins, barracuda, and blacktip reef sharks.

On the other hand, this fish interacts with humans as well. The blue runner jack is important in fisheries. They are used in fish meal, fish oil, and live bait. Like most fishes, the blue runners communicate with each other by emitting low-frequency calls such as grunts or pulses.

Photo credit: "Jack Fish" by Michael McDonough is licensed under CC BY 2.0