Anadromous red-spotted masu salmon (Oncorhynchus masou ishikawae), a southernmost sea-migration form of salmonid,displays low variation in both age at seaward migration and sea age |
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| Authors: | Shohei Noda Rui Ueda Tatsuya Tanaka Kotaro Shirai Daisuke Kishi Takuya Sato |
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| Institution: | 1. Department of Biology, Graduate School of Sciences, Kobe University, Kobe, Japan;2. Department of Chemical Oceanography, Atmosphere and Ocean Research Institute, The University of Tokyo, Tokyo, Japan;3. Gifu Prefectural Research Institute for Fisheries and Aquatic Environments, Gero, Japan |
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| Abstract: | We examined variations in age at seaward migration and sea age for the anadromous form of red-spotted masu salmon (Oncorhynchus masou ishikawae) in two Japanese rivers. The anadromous form of red-spotted masu salmon expressed only two sea migration patterns in the two rivers: (a) the majority of the salmon (95%, n = 81) were of age-0, and age-1 migrants were rare (n = 4); and (b) all the salmon examined (n = 22) made a return migration within a year, with 23% of the salmon exhibiting potamodromy in the river. Owing to low variation in their sea migratory patterns, the anadromous form of red-spotted masu salmon is likely vulnerable to environmental fluctuations. |
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| Keywords: | migration pattern oncorhynchus masou ishikawae sea age seaward migration smolt age |
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