Institute of Marine Research (IMR), Bergen, Norway.
Institute of Biology, University of Bergen, Bergen, Norway.
Sci Rep. 2020 Feb 26;10(1):3529. doi: 10.1038/s41598-020-60588-0.
Anadromous salmon and sea trout smolts face challenging migrations from freshwater to the marine environment characterised by high mortality. Therefore, the timing of smolt migration is likely to be critical for survival. Time-series comparing migration of Atlantic salmon and sea trout smolts in the same river, and their response to the same environmental cues, are scarce. Here, we analysed migration timing of ~41 000 Atlantic salmon and sea trout smolts over a 19-year period from the river Guddalselva, western Norway. Trout displayed a longer migration window in earlier years, which decreased over time to become more similar to the salmon migration window. On average, salmon migrated out of the river earlier than trout. Migration of both species was significantly influenced by river water temperature and water discharge, but their relative influence varied across the years. On average, body-length of smolts of both species overlapped, however, size differences were observed within the migration period and among the years. We conclude that salmon and trout smolts in this river are highly synchronised and migrate in response to the same range of linked environmental cues.
溯河洄游的鲑鱼和海鳟幼鱼在从淡水到海洋环境的迁徙过程中面临着高死亡率的挑战。因此，幼鱼迁徙的时间可能对其生存至关重要。目前，比较同一条河流中大西洋鲑鱼和海鳟幼鱼的迁徙时间及其对相同环境线索的反应的时间序列数据还很缺乏。在这里，我们分析了来自挪威西部古达尔斯瓦拉河的约 41000 条大西洋鲑鱼和海鳟幼鱼在 19 年期间的迁徙时间。鳟鱼在早些年有更长的迁徙窗口，随着时间的推移，这个窗口逐渐缩短，变得与鲑鱼的迁徙窗口更为相似。平均而言，鲑鱼比鳟鱼更早地离开河流。两种鱼类的迁徙都受到河流水温和流量的显著影响，但它们的相对影响在不同年份有所不同。平均而言，两种鱼类的幼鱼体长重叠，但在迁徙期间和不同年份中都存在大小差异。我们的结论是，这条河里的鲑鱼和鳟鱼幼鱼高度同步，它们根据相同的一系列相关环境线索进行迁徙。
