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

摘要

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 anadroous S. leucomaenis showed phase L (low Sr∶Ca ratio) from the core to the point 1000–2500 μm distant, averaging 1.3×10?3 to 2.7×10?3 and thereafter, the ratios increased sharply, being higher than 5.0 × 10?3 to 10.0 ×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.