Predation effects on juvenile Atlantic salmon (Salmo salar) populations in changing riverscape

自然过程，如捕食，在所有种群中都起作用。不同的人为活动（如渔业管理，水电，气候变化）可能会改变大西洋鲑鱼（萨尔莫salar）种群实现由于捕食压力的影响。许多A。鲑鱼种群受到威胁，任何人为引起的变化都可能是有害的。本文提出的基于实地的研究重点是评估捕食对幼鱼的影响。鲑鱼在自然流和流量调节河流的三种情况下。 第一个项目的重点是评估建议的陷阱和卡车管理战略，在一个大型水电调节圣约翰河（SJR），新玩法（NB）。我们以前的研究表明，晚秋捕食威胁的前小鲑鱼A。在一个水电站附近的鲑鱼。这一假设的有效性进行了检查，通过使用新的捕食标签声学遥测。捕食事件（从捕食标签）的频率和位置的数据将结合从定期的声学标签（条纹低音Morone saxatilis和muskellunge Esox masquinongy）和捕食频率的捕食运动数据作为水温的函数进行检查。 第二个项目的重点是评估扩大（> 100万）条纹鲈种群的捕食威胁A。在米拉米奇河鲑鱼小鲑鱼，NB。项目将量化捕食不同大小类别的条纹鲈鱼在时间和空间在整个小鲑鱼迁移窗口，并联合收割机这些数据与总的日常运行大小的A。鲑鱼幼鱼揭示了潜在的捕食威胁的大小类别。这些信息将用于修订鲈鱼渔业内部的渔业管理建议。 第三个项目将A）比较半水生哺乳动物在可涉水河流中与对比冰制度（即无冰和有冰）的季节性捕食水平，B）检验既定假设，即捕食威胁是幼鱼A在冷水温度下停止白天活动的驱动力。三文鱼这两个研究组件依赖于新的发展被动综合应答器技术跟踪青少年A.鲑鱼。项目P3A的实地研究将在NB的小溪流中进行，根据以前的研究，那里的冰过程是已知的。项目P3B将发生在格陵兰岛的Kapisillit河，这是世界上唯一一条A.鲑鱼种群是在没有哺乳动物捕食的情况下进化的。冬性行为因此，预期鲑鱼反映出与进化上存在冬季捕食的种群不同的活动模式。 这项研究将为捕食在调节A.鲑鱼种群的季节性小苗圃流在不断变化的气候，并将提供建议，是直接适用于更好地管理受威胁和社会经济重要的A。在北美重要的鲑鱼河流中的鲑鱼种群。

Natural processes, such as predation, are at play in all populations. Different anthropogenic actions (e.g. fisheries management, hydropower, climate change) may alter the effect that Atlantic salmon (Salmo salar) populations realize due to predation pressure. With many A. salmon populations threatened, any human-induced change may be detrimental. The field-based research proposed herein focuses on assessing effects of predation on juvenile A. salmon under three case situations in natural-flow and flow-regulated rivers. The first project focuses on assessing a proposed trap-and-truck management strategy in a large hydropower regulated Saint John River (SJR), New Brunswick (NB). Our previous studies suggest late-autumn predation threat for pre-smolt A. salmon at the vicinity of a hydropower station. The validity of this hypothesis is examined by using novel predation-tag acoustic telemetry. Data on frequency and locations of predation events (from predation tags) will be combined with predator movement data from regular acoustic tags (striped bass Morone saxatilis and muskellunge Esox masquinongy) and the frequency of predation is examined as a function of water temperature. The second project focuses on assessing the predation threat of expanded ( >1 million) striped bass population on A. salmon smolts in the Miramichi River, NB. Project will quantify predation by different size categories of striped bass in time and space throughout the smolt migration window, and combine these data with the total daily run size of A. salmon smolts to reveal a potential predation threat by size category. The information will be used to revise fisheries management advice within bass fishery. The third project will A) compare seasonal levels of predation by semiaquatic mammals in wadable streams with contrasting ice-regimes (i.e. ice-free and ice covered) and B) examine the established hypothesis that threat of predation is the driving force of cessation of daytime activity in cold water temperature in juvenile A. salmon. Both research components rely on new developments in Passive Integrated Transponder technology for tracking juvenile A.salmon. Field research for project P3A will be undertaken in small streams in NB where ice processes are known based on previous research. Project P3B will occur in the Kapisillit River in Greenland; the only stream in the world where an A. salmon population has evolved in the absence of mammalian predation. Winter behavior of A. salmon is therefore expected to reflect different activity patterns than in populations where winter predation has evolutionarily been present. The proposed research will contribute novel information regarding the role of predation in regulating A. salmon populations in seasonal small nursery streams in changing climate, and will provide advice that is directly applicable for better managing threatened and socio-economically important A. salmon populations in significant North American salmon rivers.