Bonito

Gillrakers 29 to 33 on first arch; gill teeth 28 or 29; vomerine teeth absent. Anal fin rays 13 or 14. Vertebrae 39; no trace of vertebral protuberances; bony caudal keels on 33 and 34 vertebrae. Colour: dorsal makings composed of broken oblique stripes.

Throughout the warm waters of the Indo-West Pacific, including oceanic islands and archipelagos.A few stray specimens have been collected in the eastern tropical Pacific.

Maximum fork length is about 100 cm and weight about 13.6 kg, common to 60 cm. The all-tackle angling record is a 11.80 kg fish from Merimbala, New South Wales, with a fork length of 96.5 cm taken in 1980. In Philippines waters, maturity is attained at about 40 cm fork length, while in the Indian Ocean it is reached between 50 and 65 cm in the 3rd year of age.

An epipelagic, neritic speciesinhabiting waters temperatures ranging from 18 to 29° C. Like other scombrids, E. affinis tend to form multispecies schools by size, 'i.e. with small Thunnus albacares, Katsuwonus pelamis, Auxis sp., and Megalaspis cordyla (a carangid), comprising from 100 to over 5 000 individuals. Although sexually mature fish may be encountered throughout the year, there are seasonal spawning peaks varying according to regions: i.e. March to May in Philippine waters; during the period of the NW monsoon (October-November to April-May) around the Seychelles; from the middle of the NW monsoon period to the beginning of the SE monsoon (January to July) off East Africa; and probably from August to October off Indonesia. The only available information on fecundity applies to Indian Ocean material: a 1.4 kg female (ca 48 cm fork length) spawns approximately 0.21 million eggs per batch (corresponding to about 0.79 million per season), whereas a female weighing 4.6 kg (65 cm fork length) may spawn some 0.68 million eggs per batch (2.5 million per season). The sex ratio in immature fish is about 1:1, while males predominate in the adult stages. E. affinis is a highly opportunistic predator feeding indiscriminately on fish, shrimps and cephalopods.In turn, it is preyed upon by marlins and sharks.

The reported world catch (eight countries) for the period between 1975 and 1981 fluctuated between about 44 000 and 65 000 t per year. The 1977 catches were exceptionally high, almost 84 000 t. About 67 500 t were reported for 1981 (FAO, 1983). The countries with the largest landings were the Philippines, Malaysia and Pakistan. In India, E. affinis is an important species in local drift net (gillnet) and hooks and lines fisheries, even though this country has not supplied separate statistics for it during the above period. Typically these are multispecies fisheries also taking E. affinis. Besides gillnetting, trolling is the major fishing technique in use. Occasionally beach seines and longlines are also deployed. Some gear types are rather size-selective, i.e. trolling lines take smaller fish than gillnets. The meat is of good quality when fresh, but it deteriorates very fast if not treated adequately.The total catch reported for this species to FAO for 1999 was 169 607 t. The countries with the largest catches were Malaysia (57 281 t) and Thailand (45 768 t).