Winter survival of stream salmonid fishes and implications for population dynamics

冬季被认为是北温带淡水鱼类生存的关键时期。相对较少的工作集中在直接估计生存率，特别是对补充和鱼类种群动态的影响。为了估计冬季生存率，计划了三个研究生项目。首先，我要解决这个问题：“卵子的存活率是否与冬季严酷程度有关？”在新不伦瑞克省的各种溪流中，野生卵/鱼卵的存活率将根据孵化环境（redd）的物理化学干扰（冰、溶解氧浓度）来确定。回答“冬季是种群生存瓶颈吗？”这个问题。第二个项目的重点是野生大西洋鲑鱼幼鱼（parr）。基于使用无源集成转发器（PIT）技术跟踪小鱼类的成功修改，具体目标将是通过在整个冬季和春季跟踪大河段中带有 PIT 标记的帕尔鱼，并响应冻结和洪水等干扰事件，区分冬季死亡率和帕尔鱼迁移。这些结果将成为模拟阶段间生存以及环境和生物因素对驱动鲑鱼种群动态的相对重要性的基础。 加拿大大西洋地区的气候变化情景预测冬季降水量增加，仲冬分裂事件的可能性更高。这种变化可能会影响 parr 的生存。然而，还没有实验研究调查冬季排放事件与鲑鱼身体状况（和生存）之间的关系。这是第三个项目的重点。使用室外水箱和模拟冬季“洪水”事件，将确定三个年龄级别的未成熟和成熟帕尔的状况、能量含量、完成银化的能力和存活率。拟议的研究具有很强的保护重点，并试图确定自然环境压力源（冰、可变流量）的影响，特别是当这些压力源可能因气候变化情景（例如，仲冬分手）而加剧时。结果应提高对环境因素与生物群之间关系的理解，以及我们保护处于危险中的人群的能力。

Winter is perceived as a critical period of survival for freshwater fishes in north temperate latitudes. Relatively little work has focused on direct estimates of survival and especially the influence on recruitment and fish population dynamics. To estimate winter survival, three graduate projects are planned. First, I address the question "Is egg survival a function of winter severity?" In various New Brunswick streams, wild egg/alevin survival will be determined in response to physico-chemical disturbance (ice, dissolved oxygen concentration) of the incubation environment (redd). To answer the question "Is winter a population survival bottleneck?" the focus of the second project will be on wild juvenile Atlantic salmon (parr). Based on successful modifications for tracking small fishes using passive integrated transponder (PIT) technology, the specific objective will be to distinguish between winter mortality and emigration of parr by tracking PIT-tagged parr in large river reaches throughout winter and spring and in response to disturbance events like freeze-up and flooding. These results will form the basis for modeling inter-stage survival and the relative importance of environmental and biological factors for driving salmon population dynamics. Climate change scenarios for Atlantic Canada predict increased winter precipitation, and a higher probability of mid-winter break-up events. Such changes may affect parr survival. However, no experimental studies have investigated the relationship between winter discharge events and body condition (and survival) of salmon parr. This is the focus of the third project. Using outdoor tanks and simulated 'flood' events over winter, the condition, energy content, ability to complete smoltification, and survival of three age-classes of immature and mature parr will be determined. The proposed research has a strong conservation focus and attempts to identify the effect of natural environmental stressors (ice, variable flows) especially as these stressors may be exacerbated by climate change scenarios (e.g., mid-winter break-ups). Results should improve understanding of the relationships between environmental factors and biota, and our ability to protect populations at risk.