Otolith shape analysis provides a robust tool for the discrimination of many fish stocks in the context of fisheries management. However, there has been little research to examine within-stock temporal stability of otolith morphology in relation to changes in the environment and stock conditions. This study investigated the variability of Northeast Arctic (NEA) cod (Gadus morhua) otolith shape between 1933 and 2015, using elliptical Fourier descriptors extracted from archived material of 2968 mature fish. Series of hierarchical multivariate models were developed to relate shape to the identified optimal windows of some environmental drivers. Differences between years accounted for <3% of the observed variation and no significant differences were found between the average cohort shapes. The models not only confirmed that fish growth was the strongest driver of shape differences, but also highlighted effects of temperature and biomass-related variables at different life stages. Extrinsic factors described only a small fraction of the observed variance, which indicates that environmental changes over time likely account for less than the natural inter-individual variability in otolith shape. These results suggest that overall shape remains relatively stable through time within NEA cod, which further contributes towards a consensus on the biological interpretation of shape differences.

中文翻译：

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东北北极鳕鱼（长期时间的稳定性鳕鳕）耳石形态

耳石形状分析为在渔业管理中区分许多鱼类种群提供了一个强大的工具。但是，很少有研究检查耳石形态与环境和种群条件变化有关的种群内时间稳定性。这项研究调查了东北北极鳕鱼（Gadus morhua）的变异性。）在1933年至2015年之间的耳石形状，使用从2968条成熟鱼的存档材料中提取的椭圆傅立叶描述符。开发了一系列的分层多元模型，以将形状与某些环境驱动因素的最佳窗口相关联。年份之间的差异占观察到的差异的<3％，平均队列形状之间没有发现显着差异。这些模型不仅证实了鱼类生长是形状差异的最强驱动力，而且还强调了不同生命阶段温度和生物量相关变量的影响。外在因素仅描述了所观察到的方差的一小部分，这表明随着时间的推移，环境变化可能比耳石形状的自然个体间变化少。