Bonito - Euthynnus affinis
Sep 12, 2022
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Euthynnus affinis, the mackerel tuna, little tuna, wavyback skipjack tuna, kawakawa, or tongkol is a species of ray-finned bony fish in the family Scombridae, or mackerel family. It belongs to the tribe Thunnini, better known as the tunas. This is an Indo-Pacific species which is found from the Red Sea to French Polynesia.
Euthynnus affinis formerly was known as Euthynnus yaito.
- Large median keel with 2 smaller keels on either side of caudal peduncle
- 29–34 gill rakers on first gill arch
- 8–10 dorsal finlets, 6–8 anal finlets
- Interpelvic process 2 flaps
- Teeth small and conical in single series
- Tongue with 2 longitudinal ridges
- Narrow interdorsal space not wider than eye
- Body scaleless behind a corselet of enlarged, thickened scales
Bluish black above, silver below. Scaleless corselet area containing a series of oblique dark stripes behind mid-first dorsal fin. Usually 1–3 small dark spots between pectoral and pelvic-fin bases.
Up to 100 cm TL, and up to 14 kg in weight.
Warm waters of the Indo-West Pacific, including oceanic islands and archipelagos.
Inshore pelagic, found at depths from the surface to 50 m.
Mostly eats small fishes, particularly clupeids and atherinids, but also squids, crustaceans and zooplankton. Forms size segregated same species and multi-species schools. Maturity of Euthynnus affinis varies by region, off the coast of India, length at where 50% of individuals are mature is estimated at 49 cm FL and 49.7 cm FL for females and males respectively. In waters off Taiwan, age of first maturity is estimated at 2 years. Euthynnus affinis migrate to waters off the coast of Taiwan, north of the Philippines for spawning. Spawning season occurs from April to August, peaking in July. Maximum age is estimated at 9 years.