[2019 AWARD WINNING PAPER] Evaluation from otolith Sr stable isotope ratios of possible juvenile growth areas of Japanese eels collected from the West Mariana Ridge spawning area

Fish Sci (2019) 85:483–493
https://doi.org/10.1007/s12562-019-01304-4

Authors

Tsuguo Otake, Yosuke Amano, Kotaro Shirai, Noritaka Mochioka, Toshiro Takahashi, Seinen Chow, Hiroaki Kurogi, Shouzeng Dou, Asuka Yamaguchi & Katsumi Tsukamoto

Abstract

The widely distributed East Asian Japanese eel Anguilla japonica constitutes a single genetically homogeneous population with a single spawning area near the West Mariana Ridge. Otolith ⁸⁷Sr/⁸⁶Sr ratios of adults (categorized as “river“, “estuarine” or “sea” eels, according to their habitat use history determined from otolith Sr:Ca ratio analysis) collected from the spawning area in 2008 and 2009 were examined in an attempt to determine their juvenile growth areas. In addition, ⁸⁷Sr/⁸⁶Sr ratios of water samples from rivers in China, Taiwan, Korea, and Japan were determined. Otolith ⁸⁷Sr/⁸⁶Sr ratios of the “river”, “estuarine” and “sea” eels were 0.707793, 0.708580-0.709944 and 0.709068, respectively, and water sample ratios from China, Korea, Taiwan, and Japan were 0.7104320-0.7141010, 0.7190826-0.7227976, 0.7115523-0.7146914 and 0.706191-0.712484, respectively. “River” and “estuarine” eels, which had otolith ⁸⁷Sr/⁸⁶Sr ratios less than 0.7092 (seawater ratio), appeared to have inhabited Japanese rivers and/or estuaries because similarly low isotope ratios were recorded only from Japan. However, the juvenile growth areas of other eels were unknown, as their origins could not be determined from otolith ⁸⁷Sr/⁸⁶Sr ratios alone, and required further information regarding otolith elemental and isotope compositions.

Keywords

Anguilla japonica / Japanese eel / Juvenile growth area / Otolith 87Sr/86Sr ratio

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