en Ecology Ecology پژوهشي Orginal research papers <span style="font-size:11pt"><span style="text-justify:inter-ideograph"><span style="line-height:120%"><span style="vertical-align:baseline"><span sans-serif="" style="font-family:Calibri,"><span lang="TR" style="font-size:12.0pt"><span style="line-height:120%"><span new="" roman="" style="font-family:" times=""><span style="color:black">This study analyzed the stomach contents of Chub mackerel, <i>Scomber japonicus</i>, collected from purse seine and set net fisheries samples in the South Sea of Korea in March 2020 to February 2022 for juvenile, mature, and older fish, which are useful to identify ecosystem functions and study food competition, interspecific feeding relationships, and the food web. The size of <i>S. japonicus</i> samples ranged from 5.5 to 46.6 cm in fork length<i>. S. japonicus</i> were a carnivore that feed mainly on euphausiids and pisces. The estimated average trophic level of <i>S. japonicus</i> ranged from 3.65&plusmn;0.64 to 4.00&plusmn;0.78. Examination of the feeding habits according to ontogenic feeding patterns of <i>S. japonicus</i> revealed that the mean weight of prey (<i>mW</i>/<i>ST</i>) continuously increased. There were differences in the composition of the stomach contents of<i> S. japonicus</i> by the sampling period and size class, and also the interaction between them. <i>S. japonicus</i> were specialized feeders with pisces and euphausiids as their dominant prey.</span></span></span></span></span></span></span></span></span> Scomber japonicus, South Sea of Korea, Feeding habits, Opportunistic feeder 352 367 http://jifro.ir/browse.php?a_code=A-10-4560-2&slc_lang=en&sid=1 D.G. Kim ghdl4546@naver.com 100319475328460047762 100319475328460047762 No Gyeongsang National University G.Ch. Seong sgc0720@naver.com 100319475328460047763 100319475328460047763 No Gyeongsang National University D.Y. Kang decade8899@naver.com 100319475328460047764 100319475328460047764 No Gyeongsang National University S. Jin sss6170@naver.com 100319475328460047765 100319475328460047765 No Gyeongsang National University H.Y. Soh hysoh@chonnam.ac.kr 100319475328460047766 100319475328460047766 No Chonnam National University G.W. Baeck gwbaeck@gnu.ac.kr 100319475328460047767 100319475328460047767 Yes Gyeongsang National University