Bull. Jpn. Soc. Fish. Oceanogr. 81(1), Page 18-28, 2017   The biological traits of spotted mackerel Scomber australasicus in the Emperor Seamounts Yasuhiro Kamimura1†, Atsushi Kawabata2, Shiroh Yonezaki3, Masanori Takahashi4, Ryuji Yukami1 and Chikako Watanabe1 1 Research Center for Fisheries Management, National Research Institute of Fisheries Science, Japan Fisheries Research and Education Agency, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa 236-8648, Japan 2 Resources and Environment Research Division, Resources Enhancement Promotion Department, Fisheries Agency, 1-2-1 Kasumigaseki, Chiyoda-ku, Tokyo 100-8907, Japan 3 Oceanic Resources Division, National Research Institute of Far Seas Fisheries, Japan Fisheries Research and Education Agency, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa 236-8648, Japan 4 Research Center for Environmental Conservation, National Research Institute of Fisheries and Environmental of Inland Sea, Japan Fisheries Research and Education Agency, 2-17-5 Maruishi, Hatsukaichi-shi, Hiroshima 739-0452, Japan † E-mail: yasukami@affrc.go.jp Age, growth, maturity and food habits of spotted mackerel Scomber australasicus caught at the Emperor Seamounts from 2008 to 2015 by bottom trawl fishing vessels were examined. Fork length (FL) ranged from 211.1 to 443.5 mm FL. Ages were estimated from 0-9 years by scale reading. The von Bertalanffy growth formula based on the age-FL relationship was expressed as FLt=432.7×(1−exp(−0.24(t+2.59))), where FLt is the FL (mm) at t (year). Seasonal changes in the gonad-somatic index suggested that the spawning period extended from March to July. Stomach contents analysis showed that the major prey organisms were Euphausiidae, Decapodiformes, Thecosomata, Salpidae, Pyrosomatidae and Piscese. The year-class in 2008 was the most dominant and clear recruitments of other year-classes were not found. Since previous surveys reported high egg production of spotted mackerel around southern waters off Hachijo-jima in the Izu islands in 2008, it is likely that individuals spawned in these waters were transported to the Emperor Seamounts by the Kuroshio and Kuroshio Extension. Key words: spotted mackerel, growth, mature, food habit, Emperor Seamounts