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Data from: Revisiting the latitudinal cline of catadromy in Japanese eels

Yokouchi, Kazuki1; Fukuda, Nobuto1; Nishimoto, Atsushi1; Aoki, Kazuhiro1; Yamamoto, Toshihiro1; Shirai, Kotaro2

Published Jul 07, 2026 on Dryad. https://doi.org/10.5061/dryad.8w9ghx3w2

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Abstract

Partial migration, widely observed across various taxa, plays a crucial role in species resilience. Element profiles in eel otoliths provide a means to approximate connectivity by reconstructing migration history, as eels exhibit partial migration between rivers and seas. Shifts in migratory contingents may reflect changes in the balance between riverine and marine productivity. Previous studies in the 2000s indicated an association between higher latitudes and increased estuarine-marine habitat reliance. However, the impact of recent anthropogenic changes on these latitudinal trends remains unverified. To address this, we conducted a large-scale analysis of otolith Sr/Ca ratios in Japanese eels from 2015–2019. Results show a significant preference for estuarine-marine areas by eels at high latitudes and revealed sex-specific differences: females more often used lower-estuarine/marine areas than males. This study underscores the need for ongoing monitoring of eel life-history patterns in response to further climate change.