Premium
Distribution of wild and stocked Japanese eels in the lower reaches of the Tone River catchment revealed by otolith stable‐isotope ratios
Author(s) -
Itakura Hikaru,
Arai Kohma,
Kaifu Kenzo,
Shirai Kotaro,
Yoneta Akihito,
Miyake Yoichi,
Secor David H.,
Kimura Shingo
Publication year - 2018
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/jfb.13782
Subject(s) - otolith , estuary , habitat , japonica , biology , biological dispersal , drainage basin , anguilla rostrata , stable isotope ratio , ecology , fishery , fish <actinopterygii> , population , geography , botany , demography , cartography , physics , quantum mechanics , sociology
The natural occurrence of Japanese eels Anguilla japonica in Japan's highly altered catchments is a critical measure of habitat restoration and ecosystem health, yet this metric may be obscured by the incidence of co‐occurring cultured eels. Distribution of wild and stocked A. japonica in the lower reaches of the Tone River cachment was investigated using otolith oxygen and carbon stable‐isotope ratios (δ 18 O and δ 13 C). We developed a discrimination model to classify wild and cultured eels for 560 individuals and applied it to eels captured in the lower reaches of the Tone River catchment. Wild eels were found at all study sites of this part of the catchment, indicating natural recruitment of the species occurred from the estuary to third‐order streams at least as far as Lake Imbanuma. The proportion of wild eels ranged from 86 to 100% at river and stream sites and was only 23% at upstream Lake Imbanuma sites. This difference probably depends on whether or not eels were released near the corresponding site. More than 50% of stocked eels occurred at sites proximate to release locations, indicating limited dispersal by cultured eels.