Migration of anadromous white-spotted charr Salvelinus leucomaenis, as determined by otolith strontium : calcium ratios

The migratory history of anadromous white-spotted charr Salvelinus leucomaenis collected from Japanese coastal waters, was examined in terms of strontium (Sr) and calcium (Ca) uptake in the otolith, by means of wavelength dispersive X-ray spectrometry using an electron microprobe. Otolith Sr concentration or Sr : Ca ratios of anadromous S. leucomaenis, fluctuated strongly along the life history transect in accordance with the migration (habitat) pattern from sea to fresh water. The anadrmous S. leucomaenis showed phase L (low Sr: Ca ratio) from the core to the point 1000-2500 mu m distant, averaging 1.3 x 10(-3) to 2.7 x 10(-3) and thereafter, the ratios increased sharply, being higher than 5.0 x 10(-3) to 10.0 x 10(-3). These findings indicated that otolith Sr : Ca ratios reflected individual life histories, enabling a sea habitat to be identified from a freshwater habitat in this species.