Micro X-ray fluorescence (mu-XRF) analysis of otoliths was evaluated as a method to estimate the proportion of stocked one-summer-old whitefish Coregonus lavaretus L. in catches of adult fish (n = 20) ascending the River Kemijoki to spawn. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis was applied as control. Polished otoliths were scanned with mu-XRF to obtain strontium maps that were used to infer visually the provenance of the whitefish. Thirteen of the fish showed signs of being stocked as one-summer-old fingerlings. LA-ICP-MS was applied to determine the elemental composition in a spot outside the core of the otolith. The results were largely consistent with the visual inspection of the mu-XRF mapped otoliths. In conclusion, mu-XRF mapping successfully identified whitefish stocked as one-summer-old fingerlings. The vast majority of whitefish returning to the River Kemijoki to spawn were stocked fish.

中文翻译：

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通过耳石的显微 X 射线荧光分析推断芬兰 Kemijoki 河放养白鱼的流行率

耳石的微 X 射线荧光 (mu-XRF) 分析被评估为一种估计放养的一夏龄白鱼 Coregonus lavaretus L. 在沿 Kemijoki 河上游产卵的成鱼 (n = 20) 渔获物中的比例的方法. 激光烧蚀电感耦合等离子体质谱 (LA-ICP-MS) 分析用作对照。用 mu-XRF 扫描抛光耳石以获得锶图，用于直观地推断白鱼的来源。13 条鱼显示出作为一夏龄鱼种放养的迹象。LA-ICP-MS 用于确定耳石核心外一个点的元素组成。结果与 mu-XRF 映射耳石的目视检查基本一致。综上所述，mu-XRF 映射成功地识别出作为一夏龄鱼种放养的白鱼。返回 Kemijoki 河产卵的绝大多数白鱼都是放养的鱼。