Identifying the nursery origins of individual Pacific halibut (Hippoglossus stenolepis) is critical to a refined understanding of regional productivity, the effects of environmental forcing on population dynamics, and the spatial impacts of mortality and bycatch. Otolith microchemistry may provide a tool for identifying fish origins, but a precursor to using microchemistry-based assignment models is to evaluate the extent to which there exists detectable spatial structure in these natural tags. Here, we examined assignment accuracy as a function of spatial scale using canonical discriminant function analyses (DFA) applied to microchemical data from age-2 Pacific halibut in the western Gulf of Alaska (GOA) and southeastern Bering Sea (SEBS). Element:calcium ratios were assayed for fourteen trace elements using inductively coupled plasma mass spectrometry; δ¹³C and δ¹⁸O were determined via isotope ratio mass spectrometry. Substantial assignment success (∼75–90 %) was observed at spatial scales that are consistent with stock management. Elemental signatures were defined primarily by δ¹⁸O, δ¹³C, and ⁸⁸Sr:⁴⁸Ca, with a minor contribution from ⁵⁵Mn:⁴⁸Ca. Individuals were most commonly mis-assigned to adjacent locations. However, discontinuities were observed within the western GOA that suggest that elemental signatures do not vary along strictly longitudinal and latitudinal clines. These results highlight the need to exercise caution when attempting to use otolith microchemistry to assign fish to their origins when the baseline elemental data are unable to resolve missing nursery sources from the locations that are included in the discrimination models.

确定单个太平洋大比目鱼（Hippoglossus stenolepis）的苗圃起源) 对深入了解区域生产力、环境强迫对人口动态的影响以及死亡率和兼捕的空间影响至关重要。耳石微化学可以提供一种识别鱼类来源的工具，但使用基于微化学的分配模型的前身是评估这些天然标签中存在可检测空间结构的程度。在这里，我们使用适用于阿拉斯加湾西部 (GOA) 和白令海东南部 (SEBS) 的 2 岁太平洋大比目鱼的微化学数据的典型判别函数分析 (DFA) 来检查分配准确性作为空间尺度的函数。使用电感耦合等离子体质谱法测定了 14 种微量元素的元素：钙比率；δ ¹³ C 和δ ¹⁸O 通过同位素比质谱法测定。在与库存管理一致的空间尺度上观察到大量分配成功（~75-90%）。元素特征主要由 δ ¹⁸ O、δ ¹³ C 和⁸⁸ Sr：⁴⁸ Ca 定义，⁵⁵ Mn 的贡献较小：⁴⁸大约 个人最常被错误分配到相邻位置。然而，在西部 GOA 内观察到不连续性，这表明元素特征不会沿着严格的纵向和横向倾斜度变化。这些结果强调，当基线元素数据无法从判别模型中包含的位置解析缺失的苗圃来源时，尝试使用耳石微化学将鱼类分配到其来源时需要谨慎行事。