• Korean Journal of Ichthyology
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• v.26 no.4
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• pp.349-354
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• 2014

The diet composition of bullet mackerel, Auxis rochei was studied using 200 specimens collected from December 2013 to May 2014 in the coastal waters of Iloilo, Philippines. The size of A. rochei ranged from 11.1 to 31.2 cm in fork length (FL). A. rochei was epipelagic feeder that consumed mainly fishes. In addition, A. rochei consumed shrimps, copepods, crab larvae, amphipods and cephalopods. The diet also included small quantities of stomatopods, bivalves, and ostracods. Also, analysis of the prey-specific abundance against the frequency of occurrence shows that A. rochei have a narrow food niche, and are specialized feeder with fish as their dominant prey. Although fishes were the primary in food consumed by all size class. The fishes gradually increased with body size.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.6
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• pp.677-683
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• 2011

Eleven individual larvae (3.6-8.0 mm notochord length, NL) were collected from the southern East Sea of Korea in July, 2010, and the adjacent Sea of Jeju Island in August, 2011. Five individuals were identified using mitochondrial DNA cytochrome oxidase subunit I (COI) sequences (494 base pairs). All were identified as Auxis rochei, their mtCOI sequences being consistent with those of adult A. rochei (d=0.000), followed by Auxis thazard (d=0.027). In terms of morphology, A. rochei larvae showed a preflexion stage of 4.8 mm NL, but a flexion stage between 5.2-6.2 mm NL, and subsequently a postflexion stage between 6.6-8.0 mm NL. During the larval stage, A. rochei differed from A. thazard in having no (or few) melanophores in the lateral caudal region.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.1
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• pp.79-85
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• 2015

Three specimens of larvae (5.2~7.8 mm in standard length (SL)), of the family Scombridae, were collected from the southeastern waters off Jeju Island in August, 2014. These specimens were identified to Katsuwonus pelamis have melanophores distributed on the 1st dorsal-fin spines and post ventral margin on caudal peduncle. An analysis of the cytochrome oxidase submit I (COI) sequences (652 base pairs) of mitochondrial DNA showed that our specimens must be K. pelamis, because their sequences were concordant with those of the adult K. pelamis (genetic distance= 0.000~0.002), followed by Auxis rochei (genetic distance= 0.061~0.063) and Euthynnus affinis (genetic distance= 0.077~0.079). During the larval stage, K. pelamis differed from Thunnus spp. species in melanophores distribution period of 1st dorsal-fin spines, lower jaws and ventral margin on caudal peduncle. In conclusion, occurrence of K. pelamis larvae means Korean waters are potential spawning ground of K. pelamis.