Collaborative Research: Comparative Analysis of Salmon and Cod Population Responses

在GLOBEC调查中，因果关系往往是从观察到的环境指标和人口之间的协变推断出来的，但作用机制（例如，对个体生长速度或某一年龄的存活率的影响），尽管经常被假设，但很少为人所知。作用机制的群体动态效应很少得到阐明，研究人员往往不知道不同年龄变异性之间或生存或生长变异性之间的群体动态差异。然而，在人口动态的研究是越来越多的人认识到这些差异，在人口对环境的敏感性和环境强迫和响应的可变性的时间尺度。鲑鱼和鳕鱼是GLOBEC感兴趣的两个分类群，它们横跨北方半球的太平洋和大西洋。它们的种群在空间上的发展速度和随之而来的产卵年龄分布各不相同，它们在不同年龄的生存率和发展速度（以及产卵年龄分布）方面都经历着年际间的时间变化。研究人员将研究种群动态在构建各种鲑鱼和鳕鱼种群对环境变异性和气候变化的不同反应中所起的作用。具体而言，他们将描述作用机制（可变的生长率或年龄存活率）如何影响人口对各种时间尺度环境波动的敏感性，包括人口反应的预期时间尺度。类似的研究的例子，包括在20世纪70年代中期，由于产卵年龄分布的差异，coho和chinook鲑鱼的种群反应的差异。发现预期的差异是轻微的，重新将注意力集中在反应差异的其他潜在原因上。另一个例子是确定鳕鱼群体共振的原因，并提请注意这样一个事实，即共振的增加（对环境变化的特定时间尺度的敏感性）也导致对非常低频率的变化的敏感性增加，例如可能在气候变化中看到。有人表示关切的是，这种对随机噪音的高度敏感性可能会干扰探测缓慢气候变化的努力。这将有助于与渔业管理有关的风险分析。此外，说明种群将敏感的预期变异尺度将有助于海洋观测系统的设计和分析。从人力资源的角度来看，本项目将培养一名学生和两名博士后学者。

In GLOBEC investigations, causality is often inferred from observed covariability between environmental indicators and populations, but mechanisms of action (e.g., an effect on individual growth rate or survival at a certain age) are seldom known, though they are frequently hypothesized. The population dynamic effects of the mechanism of action are seldom elucidated, and investigators are often not aware of the population dynamic differences between variability at different ages or between variability in survival or growth. However, research in population dynamics is increasing awareness of the differences these make in terms of sensitivity of populations to the environment and the time scales of variability of the environmental forcing and the response. Salmon and cod are two taxa that have been of interest to GLOBEC and they span the Pacific and the Atlantic Oceans in the Northern Hemisphere. Their populations vary spatially in development rates and the consequent distribution of spawning ages, and they experience inter-annual temporal variability in both survival at various ages and development rates (and spawning age distributions). The investigators will examine the role of the differences that population dynamics makes in structuring the different responses of various salmon and cod populations to environmental variability and climate change. Specifically, they will describe how the mechanism of action (variable growth rate or survival rate at age) influence population sensitivity to environmental fluctuations at various time scales, including expected time scales of population response. Examples of similar studies include out elucidation of the differences in population responses of coho and chinook salmon to the regime shift in the mid-1970s due to differences in spawning age distributions. Discovering that the expected differences were slight re-focused attention on other potential causes of the differences in response. Another example is identification of the causes of cohort resonance in cod and the drawing of attention to the fact that increasing resonance (sensitivity to specific time scales of environmental variability) also led to increasing sensitivity to variability at very low frequencies such as might be seen in climate change. Concern was expressed that this heightened sensitivity to random noise could interfere with attempts to detect slow climate change.A societal benefit will be derived from this investigation of how the addition of fishing mortality rate changes the basic response of populations to environmentally induced variability in development rates and survival rates at various ages. This will aid in the risk analysis associated with fishery management. Also, description of the expected scales of variability to which populations will be sensitive will aid in the design and analysis of ocean observing systems. From a human resources point of view, this project will be train one student and two postdoctoral scholars.