Evaluation of downward movements of Japanese eel Anguilla japonica inhabiting brackish water areas

This study evaluated the size and age distributions and otolith microchemistry of the Japanese eel Anguilla japonica in freshwater and brackish water areas in the Aki and Tsuchikawa rivers for 1 year, and in brackish water areas in the Asahi River for 3 years to understand the movements of Japanese...

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Bibliographic Details
Published in:Journal of fish biology 2020-02, Vol.96 (2), p.516-526
Main Authors: Wakiya, Ryoshiro, Kaifu, Kenzo, Azechi, Kazuhisa, Tsukamoto, Katsumi, Mochioka, Noritaka
Format: Article
Language:English
Subjects:
Aging - physiology
Anguilla - physiology
Anguilla japonica
anguillid eel
Animal Distribution
Animals
Brackish water
Catadromous fishes
dispersal
Ecosystem
Eels
Estuaries
Estuarine dynamics
estuary
Fresh water
Freshwater
Inland water environment
Japan
Marine fishes
Microchemistry
migration
otolith microchemistry
Otolithic Membrane - chemistry
Rivers
Saline water
Saline Waters
Salinity
Water analysis
Water area
Water sampling
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Summary:This study evaluated the size and age distributions and otolith microchemistry of the Japanese eel Anguilla japonica in freshwater and brackish water areas in the Aki and Tsuchikawa rivers for 1 year, and in brackish water areas in the Asahi River for 3 years to understand the movements of Japanese eels between continental habitats of different salinity after recruitment (n = 759). For all three rivers, the total length (LT) and age distributions were consistent; yellow eels captured in the upper brackish water (Aki River: 353.5 ± 77.4 mm and 3.0 ± 0.8 years; Tsuchikawa River: 287.7 ± 87.3 mm and 3.7 ± 1.3 years; Asahi River: 418.2 ± 112.1 mm and 4.2 ± 1.7 years) were smaller and younger than not only those in the fresh water of the two rivers but also those in the lowest brackish water sampling areas (Aki River: 436.0 ± 71.6 mm and 3.8 ± 1.1 years; Tsuchikawa River: 370.9 ± 121.7 mm and 4.9 ± 2.3 years; Asahi River: 558.5 ± 85.9 mm and 5.7 ± 1.7 years). In the Asahi River, these tendencies were found throughout the 3 years. Otolith analysis indicated that the majority of the eels captured in the lowest brackish water areas had moved down from upstream. These results suggest that Japanese eels inhabiting saline water generally move from the upper estuary as they grow. The upper estuary can be an important area for the management of this species because these eels spend their early continental growth life there.
ISSN:0022-1112
1095-8649
DOI:10.1111/jfb.14236