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タイトル: Migratory history of wild and released ayu (Plecoglossus altivelis) in the Kurobe River, Japan
著者: Kuroki, Mari
Ma, Tao
Ishida, Rikizo
Tsukamoto, Katsumi
キーワード: ayu
Plecoglossus altivelis
migratory history
otolith
Sr: Ca ratios
Kurobe River
stocking
発行日: 2006年6月25日
出版者: International Coastal Research Center, Ocean Research Institute, the University of Tokyo
掲載誌情報: Coastal marine science. Vol.30No.2, 2006.6, pp. 425-431
抄録: In order to discuss the influence of dam discharge on the movement of ayu Plecoglossus altivelis in a river and the stocking effectiveness of released ayu, the migratory history of 83 juveniles of ayu (standard length=67.9-142.4mm sL) collected in the Kurobe River, Japan during 25 June-23 August 2004 was determined by otolith microchemistry, and the origin of fish was identified as being either native amphidromous ayu or released amphidromous or landlocked fish. Except for otoliths with abnormal morphology (N=10), most specimens (96%, N=70) had inner layers (radius:>400μm) of higher Sr: Ca ratios and outer ones of low values. These specimens were identified as native amphidromous fish that migrated upstream from the sea. Only 4% (N=3) were released ayu (reared fish), which were further divided into two origins, amphidromous fish (N=2) with smaller inner layers (radius:<400μm) of high Sr: Ca ratios, and landlocked fish (N=1) with constantly low values over the whole otolith. There were no specimens with an increase in Sr: Ca ratios in the outer layers of the low Sr: Ca region of the otolith after their upstream migration in spring, suggesting that it is unlikely that any of these ayu had been washed-out from the river by cold and turbulent river water.
URI: http://hdl.handle.net/2261/5665
ISSN: 13493000
出現カテゴリ:Coastal Marine Science
Coastal Marine Science

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