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Bull. Jpn. Soc. Fish. Oceanogr. 77(4), Page 266-273, 2013 |
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Seasonal changes in hatch date distribution of age-0 yellowtail, Seriola quinqueradiata, caught on the east coast of Noto Peninsula, Sea of Japan
Toshihiro Tsuji1†, Yongjun Tian2 and Mami Saito3
1 Ishikawa Prefecture Fisheries Research Center, 3-7 Ushitsushinko, Noto, Housu, Ishikawa 927-0435, Japan
2 Japan Sea National Fisheries Research Institute, Fisheries Research Agency, 1-5939-22 Suido, Chuo, Niigata, Niigata 951-8121, Japan
3 JAPAN NUS Co., Ltd., Yokohama, Kanazawa High-technology Center 5F, 1-1 Fukuura, Kanazawa, Yokohama, Kanagawa 236-0004, Japan
† E-mail: t-tuji@pref.ishikawa.lg.jp
Hatch dates of age-0 yellowtail Seriola quinqueradiata collected by set-nets in the eastern coastal area around the Noto Peninsula in the Sea of Japan between 2005 and 2007 were determined using the otolith daily growth increments. Hatch dates of 1146 individuals in total (range of 96-448 mm in fork length) were estimated by subtracting the number of otolith daily increments from the sampling dates. Estimated hatch dates of the age-0 fish samples indicated a protracted spawning season from late January to mid August. Then hatch month distributions of the recruitment in the whole fishing season were calculated by weighting the total catch by the number of age-0 fish from the set-net fishery in this area. Results showed that 57.7-69.5% of fishes were hatched during the period from March to April in every survey year. This suggests that age-0 fishes caught in the eastern coastal area of the Noto Peninsula mostly originated from the shelf break region of the East China Sea, the main spawning ground of yellowtail. On the other hand, hatch month distributions shifted later in progressive catching periods originating from other spawning grounds. Furthermore, age-0 fishes that hatched from March to April were hardly found in the coastal waters around the Noto Peninsula after December, and may migrate to other areas.
Key words: otolith daily increment, hatching date, yellowtail, Sea of Japan |
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