Natal homing and straying are behavioural tactics of migratory animals that return to nursery habitats to breed as adults. Straying has evolutionary and ecological importance for species flexibility, interpopulation connectivity and success of invasive species in new environments. This study aimed to estimate the relative importance of straying and homing in introduced brown trout Salmo trutta spawning in a model coastal tributary (Silverstream) of a large New Zealand river using otolith microchemistry. The data on natal homing and straying are important for the understanding of the ecological resilience of salmonid populations and metapopulations, and the development of effective management measures at stream or catchment scales. To examine brown trout homing and straying in a river catchment, otolith microchemical analysis was applied. We used linear discriminant function analysis to compare the trace element composition in the otoliths of YoY (young-of-the-year) trout collected at spawning streams across the catchment and adult trout reproducing in Silverstream. The results showed that only six from a sample of 30 spawning adults in Silverstream originated from Silverstream. Another 14 fish likely originated from other Taieri tributaries further upstream, but the origin of the remaining 10 could not be determined. Contrary to published studies based on wild populations of brown trout in Europe, and several other species of salmonids, a large proportion of brown trout spawners collected in Silverstream were strays. The large number of strayers identified in Silverstream may be a consequence of the geomorphology of the Taieri catchment and highlights the adaptability of brown trout to different environmental contexts.

中文翻译：

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用耳石微化学评价新西兰一条大河集水区褐鳟的流浪

出生时的归巢和流浪是迁徙动物返回苗圃栖息地繁殖成年后的行为策略。流浪对于物种灵活性、种群间连通性和入侵物种在新环境中的成功具有进化和生态重要性。本研究旨在估计在引进的褐鳟鱼Salmo trutta中流浪和归巢的相对重要性。使用耳石微化学在新西兰一条大型河流的模型沿海支流（Silverstream）中产卵。出生归巢和流浪的数据对于了解鲑鱼种群和复合种群的生态恢复力，以及在河流或集水区制定有效的管理措施很重要。为了检查河流集水区中褐鳟的归巢和流浪情况，应用了耳石微化学分析。我们使用线性判别函数分析来比较在跨集水区的产卵溪流和 Silverstream 繁殖的成年鳟鱼的耳石中的微量元素组成。结果表明，Silverstream 的 30 只产卵成虫样本中只有 6 只来自 Silverstream。另外 14 条鱼很可能来自更上游的其他泰伊里支流，但其余 10 条的来源无法确定。与基于欧洲野生褐鳟鱼和其他几种鲑鱼种群的已发表研究相反，在 Silverstream 收集的大部分褐鳟产卵鱼是流浪动物。Silverstream 中发现的大量流浪者可能是 Taieri 流域地貌的结果，突出了褐鳟对不同环境背景的适应性。