By Takaomi Arai, Takafumi Hirata, Yasuaki Takagi
Marine Environmental Research, Volume 63, Issue 1, February 2007, Pages 55-66, ISSN 0141-1136, DOI: 10.1016/j.marenvres.2006.06.003.

Trace element levels in otoliths of chum salmon Oncorhynchus keta were examined by means of laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). A close linear relationship in the Sr:Ca ratios between EPMA (X-ray analysis with an electron microprobe) and LA-ICPMS analyses was found (p < 0.0001), suggesting that the latter technique could be used to separate the marine and freshwater life phases. Mg:Ca, Cr:Ca, Zn:Ca and Ba:Ca ratios in either the core region or the oceanic growth zone of the otoliths varied among sites. These differences suggest that elemental compositions may reflect environmental variability among spawning (breeding) or habitat sites. Thus, those element ratios demonstrate the potential to be used to distinguish between fish spawning (breeding) sites and habitats for this species of salmon.
Keywords: Oncorhynchus keta; Otolith microchemistry; Trace element; Laser ablation technique; Migration

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