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Isotope analysis reveals proportional change and site‐selection variation of river‐ and lake‐produced eggs of a landlocked migratory fish
Author(s) -
Sawada Hayato,
Shigeta Kanji,
Kawakami Masaki,
Yuma Masahide,
Maruyama Atsushi
Publication year - 2020
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.14200
Subject(s) - biology , landlocked country , fish <actinopterygii> , selection (genetic algorithm) , fishery , variation (astronomy) , ecology , zoology , physics , artificial intelligence , political science , computer science , astrophysics , law
Changes in the proportions of river‐ and lake‐produced eggs of a landlocked amphidromous fish, ayu ( Plecoglossus altivelis altivelis ) in the Lake Biwa water system, Japan, were monitored by stable isotope analysis, based on different δ 15 N and δ 13 C values of prey organisms between the lake and its tributaries. During the 3 month reproduction season, the δ 15 N values of spawned eggs decreased with time. This result implies that there was a shift from lake‐produced eggs to river‐produced eggs within a reproductive season, based on the observation that adult fish in the lake had previously been shown to have eggs with distinctly higher δ 15 N values in their ovaries than those in the tributaries. This explanation was also supported by the change in δ 13 C values of the spawned eggs. Furthermore, eggs with lower δ 15 N and higher δ 13 C values tended to be spawned at less variable depths, suggesting that females spawning river‐produced eggs selected the spawning sites from a narrower range. We conclude that stable isotope ratios of spawned eggs can be indicators of the relative contributions of different food chains and can enable comparisons of reproductive characteristics between types of egg.