Oregon Department of Fish and Wildlife, Corvallis, OR 97333, U.S.A.
J Fish Biol. 2014 Jul;85(1):52-80. doi: 10.1111/jfb.12380. Epub 2014 Apr 28.
This study evaluated estuarine habitat use, life-history composition, growth and survival of four successive broods of coho salmon Oncoryhnchus kisutch in Salmon River, Oregon, U.S.A. Subyearling and yearling O. kisutch used restored and natural estuarine wetlands, particularly in the spring and winter. Stream-reared yearling smolts spent an average of 2 weeks in the estuary growing rapidly before entering the ocean. Emergent fry also entered the estuary in the spring, and some resided in a tidal marsh throughout the summer, even as salinities increased to >20. A significant portion of the summer stream-resident population of juvenile O. kisutch migrated out of the catchment in the autumn and winter and used estuary wetlands and adjacent streams as alternative winter-rearing habitats until the spring when they entered the ocean as yearling smolts. Passive integrated transponder (PIT) tag returns and juvenile life-history reconstructions from otoliths of returning adults revealed that four juvenile life-history types contributed to the adult population. Estuarine-associated life-history strategies accounted for 20-35% of the adults returning to spawn in the four brood years, indicating that a sizable proportion of the total O. kisutch production is ignored by conventional estimates based on stream habitat capacity. Juvenile O. kisutch responses to the reconnection of previously unavailable estuarine habitats have led to greater life-history diversity in the population and reflect greater phenotypic plasticity of the species in the U.S. Pacific Northwest than previously recognized.
本研究评估了美国俄勒冈州鲑鱼河（Salmon River）内连续四代银大麻哈鱼（Oncoryhnchus kisutch）的洄游栖息地利用、生活史组成、生长和存活情况。亚成体和成年银大麻哈鱼使用了恢复和天然的河口湿地，尤其是在春季和冬季。在进入海洋之前，溪流养殖的成年幼鱼在河口平均停留 2 周，快速生长。刚孵出的幼鱼也在春季进入河口，有些幼鱼在整个夏季都留在潮汐沼泽中，即使盐度增加到>20。夏季溪流中幼年银大麻哈鱼的相当一部分在秋季和冬季迁移出集水区，并将河口湿地和相邻溪流用作替代冬季育肥栖息地，直到春季作为成年幼鱼进入海洋。被动集成 Transponder（PIT）标签返回和从返回成鱼的耳石重建的幼鱼生活史表明，四种幼鱼生活史类型构成了成年鱼群体。与河口相关的生活史策略占四个繁殖年份返回产卵的成年鱼的 20-35%，这表明基于溪流栖息地容量的传统估计方法忽略了大麻哈鱼总产出的相当大一部分。幼鱼对以前无法获得的河口栖息地的重新连接的反应导致了种群中生活史多样性的增加，并反映了美国太平洋西北地区的大麻哈鱼物种比以前认识到的具有更大的表型可塑性。
