Migration history of masu salmon <i>Oncorhynchus masou</i> in the Naka River, Tochigi, Japan, estimated from otolith Sr:Ca ratio analysis
Migration history of masu salmon <i>Oncorhynchus masou</i> in the Naka River, Tochigi, Japan, estimated from otolith Sr:Ca ratio analysis
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根据耳石 Sr:Ca 比率分析估算日本栃木县那珂川马苏鲑鱼 <i>Oncorhynchus masou</i> 的洄游历史
DOI：
10.11369/jji.18-009
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
白井 厚太朗
中科院分区：
文献类型：
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作者：
綱川 孝俊;白井 厚太朗
用x射线电子探针分析了在日本枥木市那卡河采集的马苏鲑个体的耳石锶（Sr）和钙（Ca）浓度，阐明了马苏鲑个体的洄游史。测图和线分析表明该物种有三种迁徙类型。除淡水洄游和典型溯河洄游（在海水中生活1年）等传统洄游类型外，还出现了短期溯河洄游（在海水中生活数月）的新洄游模式。根据耳石Sr波动和老化，从耳石规模和耳石日增量两方面估计了海洋短期无产卵个体的详细生活史。因此，估计有一半以上的那喀河种群在12 - 1月达到全长178-252毫米（1岁）时迁移到海洋环境，此后在海水中停留约5个月，然后在5 - 7月回到河流中，总长345-463毫米。这些发现可能有助于建立一种作为休闲渔业资源的增强方法。未来的研究，包括标记、年龄评估方法的验证和基因分析，都是确认海洋短期雌雄同体存在的必要条件。
The migratory histories of individual masu salmon Oncorhynchus masou collected from the Naka River, Tochigi, Japan were clarified from otolith strontium (Sr) and calcium (Ca) concentrations using X‒ray electron microprobe analysis. Mapping and line analysis indicated three migratory types of the species. In addition to the conventional types, such as freshwater resident and typical anadromous (spending one year in marine waters), a new migratory pattern of short marine term anadromous (remaining in marine waters for several months) was apparent. Detailed life histories of short marine term anadromous individuals were estimated from otolith Sr fluctuations and ageing, from both scale and otolith daily increments. Consequently, more than half of the Naka River population was estimated to migrate to a marine environment upon reaching a total length of 178‒252 mm (one year old) in December‒January, thereafter staying in marine waters for approximately five months, before returning to the river in May‒July at 345‒463 mm total length. These findings may help establish an enhancement method for this species as a recreational fishery stock. Future investigations, including tagging, verification of age evaluation methods, and gene analysis are necessary to confirm the existence of the short marine term anadromous form.