The degree of spatial autocorrelation in population fluctuations increases with dispersal and geographical covariation in the environment, and decreases with strength of density dependence. Because the effects of these processes can vary throughout an individual’s lifespan, we studied how spatial autocorrelation in abundance changed with age in three marine fish species in the Barents Sea. We found large interspecific differences in age-dependent patterns of spatial autocorrelation in density. Spatial autocorrelation increased with age in cod, the reverse trend was found in beaked redfish, while it remained constant among age classes in haddock. We also accounted for the average effect of local cohort dynamics, i.e. the expected local density of an age class given last year’s local density of the cohort, with the goal of disentangling spatial autocorrelation patterns acting on an age class from those formed during younger age classes and being carried over. We found that the spatial autocorrelation pattern of older age classes became increasingly determined by the distribution of the cohort during the previous year. Lastly, we found high degrees of autocorrelation over long distances for the three species, suggesting the presence of far-reaching autocorrelating processes on these populations. We discuss how differences in the species’ life history strategies could cause the observed differences in age-specific variation in spatial autocorrelation. As spatial autocorrelation can differ among age classes, our study indicates that fluctuations in age structure can influence the spatio-temporal variation in abundance of marine fish populations.

中文翻译：

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鱼类种群空间自相关的年龄相关模式

人口波动的空间自相关程度随着环境中的分散和地理协变而增加，随着密度依赖的强度而降低。由于这些过程的影响在个人的整个生命周期中可能会有所不同，因此我们研究了巴伦支海三种海洋鱼类的丰度空间自相关如何随年龄变化。我们发现密度空间自相关的年龄相关模式存在很大的种间差异。鳕鱼的空间自相关随着年龄的增长而增加，在喙红鱼中发现了相反的趋势，而在黑线鳕的各个年龄段中它保持不变。我们还考虑了本地队列动态的平均影响，即给定去年本地队列密度的年龄等级的预期本地密度，目的是将作用于某个年龄段的空间自相关模式与在较年轻年龄段形成并被结转的空间自相关模式分开。我们发现，老年人群的空间自相关模式越来越多地由前一年队列的分布决定。最后，我们发现这三个物种在长距离上具有高度的自相关性，这表明这些种群存在深远的自相关过程。我们讨论了物种生活史策略的差异如何导致观察到的空间自相关年龄特定变化的差异。由于空间自相关在年龄等级之间可能不同，我们的研究表明年龄结构的波动会影响海洋鱼类种群丰度的时空变化。