About Euthynnus affinis (Cantor, 1849)
Euthynnus affinis has a typical tuna body shape: it is slender and elongated, with a deeply forked tail. It has very few scales, and features 2 or more dark spots between its pelvic and pectoral fins. Its first dorsal fin contains 10 to 15 spines, and is roughly one-third the height of the fish's body. The back of Euthynnus affinis is dark blue for countershading, and marked with 12 oblique stripes. This species can reach a maximum total length of 1.1 metres (3.6 ft) and a maximum weight of 15 kilograms (33 lb).
To distinguish E. affinis (also called kawakawa) from its close relative the black skipjack, which lives in the Pacific Ocean, kawakawa has more broken stripes, while black skipjack has straight stripes that extend along the side of the body. Compared to the little tunny, which occurs primarily in the Atlantic Ocean, the stripes on the back of kawakawa are more orderly.
Euthynnus affinis is an Indo-Pacific species, distributed from the Red Sea to French Polynesia, and can also be found near Baja California. It is a pelagic, highly migratory species that commonly forms schools from the water surface down to depths of 200 metres (660 ft). It tends to stay close to coastal structures and neritic shelves rather than the open ocean, and often inhabits coastal reefs and moves into estuaries. It prefers water temperatures between 18–29 °C (64–84 °F). It is a highly opportunistic feeder that preys on squid, fish, crustaceans, and zooplankton. Like other tuna species, it often forms large multi-species schools with other scombrids such as yellowfin tuna and frigate mackerel. Predators of Euthynnus affinis include larger tuna, billfish, sharks, seabirds, and marine mammals.
