DTU Aqua, National Institute of Aquatic Resources, Section for Freshwater Fisheries Ecology, Technical University of Denmark, , Vejlsøvej 39, 8600, Silkeborg, Denmark.
Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, 1125 Colonel By Dr, Ottawa, K1S 5B6, Canada.
Sci Rep. 2019 Feb 20;9(1):2422. doi: 10.1038/s41598-019-39153-x.
Kelts - individuals of anadromous fish species which have successfully spawned and may return to sea to repeat the cycle - are perhaps the least studied life stage of iteroparous fish species. To date, our understanding of what makes them successful in their return migration to sea is limited. We investigated the relationship between three physiological parameters (baseline cortisol, baseline glucose and low molecular weight antioxidants) and the timing and success of Atlantic salmon (Salmo salar) and sea trout (Salmo trutta) kelt migration. To do so, we combined blood samples obtained within 3 minutes of capture and acoustic telemetry to track 66 salmon and 72 sea trout as they migrated out of rivers, into fjords and out at sea. We show that baseline cortisol may be a good predictor of migration success. Individuals with high baseline cortisol levels exited the river earlier but were less likely to successfully reach the sea. Similar relationships were not observed with glucose or antioxidants. We provide the first evidence to support the role of physiological status in migration success in Atlantic salmon and sea trout kelts. Our findings contribute to our understanding of the relationship between physiology and fitness in wild animals. Further, we suggest that migration timing is a trade-off between stress and readiness to migrate.
幼鱼——已成功产卵并可能返回大海重复生命周期的洄游性鱼类个体——可能是研究最不充分的多次产卵鱼类生命阶段。迄今为止，我们对于是什么使它们在返回大海的洄游中取得成功的了解是有限的。我们研究了三种生理参数（基础皮质醇、基础葡萄糖和低分子量抗氧化剂）与大西洋鲑（Salmo salar）和海鳟（Salmo trutta）幼鱼洄游时间和成功的关系。为此，我们结合了在捕获后 3 分钟内获得的血液样本和声学遥测技术，来跟踪 66 条鲑鱼和 72 条海鳟，观察它们从河流洄游到峡湾，再游到大海的过程。我们表明，基础皮质醇可能是洄游成功的良好预测指标。皮质醇水平较高的个体较早地离开河流，但成功到达大海的可能性较小。在葡萄糖或抗氧化剂方面，没有观察到类似的关系。我们提供了第一个证据来支持生理状态在大西洋鲑和海鳟幼鱼洄游成功中的作用。我们的研究结果有助于我们理解野生动物生理与适应力之间的关系。此外，我们认为，洄游时间是压力和准备好进行洄游之间的权衡。
