Collaborative Research: Comparative Analysis of Salmon and Cod Population Responses

在GLOBEC调查中，因果关系通常是从观察到的环境指标和人口之间的协变性推断出来的，但作用机制(例如，对某个年龄的个人增长率或存活率的影响)很少为人所知，尽管它们经常是假设的。作用机制的种群动态效应很少被阐明，研究人员往往没有意识到不同年龄的变异性之间或生存或生长变异性之间的种群动态差异。然而，人口动力学的研究正在提高人们对这些因素在人口对环境的敏感性以及环境强迫和反应的可变性的时间尺度方面所造成的差异的认识。鲑鱼和鳕鱼是GLOBEC感兴趣的两个分类群，它们横跨北半球的太平洋和大西洋。它们的种群在发育速度和相应的产卵年龄分布上存在空间差异，它们在不同年龄的存活率和发育速度(以及产卵年龄分布)上都经历了年际时间变化。研究人员将研究种群动态在构建不同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。具体地说，它们将描述作用机制(年龄的可变增长率或存活率)如何在不同的时间尺度上影响人口对环境波动的敏感性，包括人口反应的预期时间尺度。类似研究的例子包括阐明了由于产卵年龄分布的差异，Coho和Chinook鲑鱼对20世纪70年代中期政权转变的种群反应的差异。发现预期的差异是轻微的，将注意力重新集中在反应差异的其他潜在原因上。另一个例子是查明鳕鱼群体共鸣的原因，并提请注意共鸣的增加(对环境变异性的特定时间尺度的敏感性)也导致对气候变化等极低频率的变异性的敏感度增加。有人表示关切的是，这种对随机噪声的高度敏感可能干扰探测缓慢气候变化的努力。这项关于增加捕捞死亡率如何改变种群对不同年龄段的发育率和存活率的环境变化的基本反应的调查将产生社会效益。这将有助于与渔业管理相关的风险分析。此外，描述人口将对其敏感的预期变化范围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，该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.