For marine fishes of commercial interest, defining how individuals vary in certain attributes, through ontogeny, and across space and time, can help expose the structure of harvested populations and guide their management. The chemical markers locked within otoliths are, in principle, ideal for such applications, providing life-long, bio-environmental records for individuals and populations. However, substantial uncertainty still surrounds how intrinsic (i.e., within-individual) and extrinsic (i.e., environmental) processes shape chemical incorporation into otoliths, constraining our ability to predict marker variability when sampling is patchy. To tackle these issues, we measured otolith elemental (Li, Mg, Ca, Mn, Zn, Sr, Ba) and stable isotopic (δ 13 C, δ 18 O) concentrations from juvenile Atlantic herring ( Clupea harengus ) captured in Icelandic nursery sites, and built models to isolate ontogenetic (i.e., age-, growth-related) from environmental influences on otolith chemistry. Otolith Li:Ca, Mg:Ca, Mn:Ca and Sr:Ca declined with age within sites. Age slopes differed among sites for Li:Ca and Mg:Ca, and Sr:Ca was lower in larger fish within an age-class. Individual-level variation (i.e., within site, within age-class) was high for all markers, our models highlighting the importance of temperature and salinity (or proxies these represent) in explaining population-level δ 13 C and δ 18 O trends. Age- and year-specific predictions for each marker, at each site, generally accorded well with empirical observations, providing inference on island-wide heterogeneity in otolith chemistry across the juveniles’ full distributional range. Such ‘isoscapes’, generated from mechanistically-focused models as presented here, might benefit investigations of population structure for other exploited species, particularly where sampling limitations hamper fishery-management efforts.

中文翻译：

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分离个体发育的影响有助于预测全岛范围内鱼类耳石化学的变异性

对于具有商业利益的海洋鱼类，通过个体发育以及跨空间和时间定义个体在某些属性上的差异，可以帮助揭示捕捞种群的结构并指导其管理。原则上，锁定在耳石内的化学标记物是此类应用的理想选择，可为个人和人群提供终生的生物环境记录。然而，大量的不确定性仍然围绕着内在（即个体内部）和外在（即环境）过程如何将化学物质结合到耳石中，从而限制了我们在采样不完整时预测标记变异性的能力。为了解决这些问题，我们测量了耳石元素（Li、Mg、Ca、Mn、Zn、Sr、Ba）和稳定同位素（δ 13 C、δ 18 O) 来自冰岛育苗场捕获的幼年大西洋鲱鱼 (Clupea harengus) 的浓度，并建立模型以将个体遗传（即与年龄、生长相关）与环境对耳石化学的影响分离。耳石 Li:Ca、Mg:Ca、Mn:Ca 和 Sr:Ca 在站点内随着年龄的增长而下降。Li:Ca 和 Mg:Ca 站点之间的年龄斜率不同，并且 Sr:Ca 在一个年龄段内较大的鱼中较低。所有标记的个体水平变化（即，在站点内，在年龄等级内）都很高，我们的模型强调了温度和盐度（或这些代表的代理）在解释种群水平 δ 13 C 和 δ 18 O 趋势方面的重要性。每个地点的每个标记的年龄和年份特定预测通常与经验观察结果一致，提供对整个幼鱼整个分布范围内耳石化学全岛异质性的推断。这种“isoscapes”由此处介绍的以机械为重点的模型产生，可能有益于其他开发物种的种群结构调查，特别是在采样限制阻碍渔业管理工作的情况下。