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

河流景观变化中对幼年大西洋鲑鱼（Salmo salar）种群的捕食影响

• 批准号: RGPIN-2019-05964
• 负责人: Linnansaari, Tommi
• 金额: $ 2.77万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=687190
• 关键词: Predation; effects; juvenile; Atlantic; salmon

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.

捕食等自然过程在所有种群中都起着作用。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种群因捕食压力而产生的影响。由于许多大马哈鱼种群受到威胁，任何人为引起的变化都可能是有害的。本文提出了一种基于野外的研究方法，主要评估了在自然流和流量调节河流中三种情况下捕食对鲑鱼幼鱼的影响。******第一个项目侧重于评估在新不伦瑞克省圣约翰河（SJR）的大型水电调节中的陷阱和卡车管理策略。我们之前的研究表明，在水电站附近，晚秋的捕食威胁是未孵化的大马哈鱼。这一假设的有效性是通过使用新型的捕食标签声遥测来检验的。捕食事件的频率和位置数据（来自捕食标签）将与来自常规声学标签的捕食者运动数据（条纹鲈鱼Morone saxatilis和muskellunge Esox masquinongy）相结合，并将捕食频率作为水温的函数进行检查。******第二个项目的重点是评估新墨西哥州米拉米奇河（Miramichi River）条纹鲈鱼种群扩大（约100万）对鲑鱼幼崽的捕食威胁。项目将在整个幼鱼洄游窗口中，对不同体型的条纹鲈鱼在时间和空间上的捕食行为进行量化，并将这些数据与鲑鱼幼鱼的日总洄游规模相结合，揭示不同体型类别的潜在捕食威胁。这些资料将用于修订鲈鱼渔业的渔业管理咨询意见。******第三个项目将A)比较半水生哺乳动物在不同冰况（即无冰和覆盖冰）的可涉水溪流中的季节性捕食水平，B)检验既定的假设，即捕食的威胁是幼年鲑鱼在冷水温度下停止日间活动的驱动力。这两个研究组成部分都依赖于跟踪幼年鲑鱼的被动集成应答器技术的新发展。P3A项目的实地研究将在NB省的小溪中进行，那里的冰过程是根据以前的研究而已知的。项目P3B将发生在格陵兰的Kapisillit河；这是世界上唯一一条鲑鱼种群在没有哺乳动物捕食的情况下进化的河流。因此，预计大马哈鱼的冬季行为将反映出与进化中存在冬季捕食的种群不同的活动模式。******提出的研究将提供关于捕食在气候变化中调节季节性小苗圃溪流中鲑鱼种群的作用的新信息，并将提供直接适用于更好地管理北美重要鲑鱼河流中受威胁和社会经济重要的鲑鱼种群的建议。