Animals often exhibit extensive flexibility in movement behaviours on a range of temporal and spatial scales in response to cues that reliably predict fitness outcomes. The annual timing of movements between distinct habitats can be crucial, particularly in seasonal environments with narrow ecological windows of opportunity. In polygamous species, sexual selection may further shape sex-specific phenology and movement behaviours. Here, we characterized seasonal, daily and diel movement patterns in adult brown trout, Salmo trutta, between a lake feeding habitat and two spawning streams in northwestern Ireland, using passive integrated transponder (PIT) telemetry. Antennae positioned at the inflow and outflow of the lake were used to monitor movements of 197 lake-tagged adults between lake and stream habitats. Across 2 years in both streams, movements were overwhelmingly nocturnal and exhibited distinct seasonality, with a peak in daily detections close to the winter solstice. In both streams, seasonal movement activity of males began and peaked before that of females (protandry). Daily detection probabilities for both sexes increased as the moon waned (decreasing lunar illumination) and as river depth increased, the latter being associated with reduced water clarity. These findings are consistent with fish favouring movement between fluvial and lacustrine habitats when light (both solar and lunar) or hydrological conditions decrease their exposure to visually oriented predators. The observed protandry also suggests a role for intrasexual male competition, whereby earlier male arrival could increase mating opportunities.

中文翻译：

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鲑鱼与产卵相关的运动似乎是定时的，以减少暴露于视觉导向的捕食者

动物通常在一系列时间和空间尺度上的运动行为中表现出广泛的灵活性，以响应可靠地预测健康结果的线索。不同栖息地之间的年度移动时间可能至关重要，特别是在生态机会窗口狭窄的季节性环境中。在一夫多妻的物种中，性选择可能会进一步影响特定性别的物候和运动行为。在这里，我们使用被动集成转发器 (PIT) 遥测技术描述了成年褐鳟鲑鱼在爱尔兰西北部的湖泊觅食栖息地和两条产卵溪流之间的季节性、日常和昼夜运动模式。位于湖泊流入和流出处的天线用于监测 197 只带有湖泊标记的成虫在湖泊和河流栖息地之间的运动。在两个流中的 2 年间，运动绝大多数是在夜间进行的，并表现出明显的季节性，在接近冬至时的每日检测量达到峰值。在这两条溪流中，雄性的季节性运动活动在雌性之前开始并达到顶峰（protandry）。随着月亮变暗（月球光照减少）和河流深度增加，两种性别的每日探测概率都会增加，后者与水透明度降低有关。这些发现与当光照（太阳和月球）或水文条件减少它们对视觉导向捕食者的暴露时，鱼类喜欢在河流和湖泊栖息地之间移动是一致的。观察到的前突也表明性内雄性竞争的作用，即较早的雄性到来可以增加交配机会。