Evidence of downstream migration of Sakhalin taimen, Hucho perryi, as revealed by Sr?:?Ca ratios of otolith

Abstract

The migratory history of Sakhalin taimen, Hucho perryi, was examined in terms of strontium (Sr) and calcium (Ca) uptake in the otolith by using wavelength dispersive X-ray spectrometry on an electron microprobe. Otolioth Sr : Ca ratios of freshwater-reared samples remained consistently at low levels throughout the otolith. The Sr : Ca ratios of samples from Lake Aynskoye of Sakhalin Island showed a low value from the core up to a point of 700–2140 µm. Thereafter, the ratios increased sharply and remained at higher levels up to the outermost regions. The difference in Sr : Ca ratio might be the result of the presence of individuals that underwent seawater and freshwater life history phases, probably reflecting the ambient salinity or the seawater–freshwater gradient in Sr concentration. Otolith Sr : Ca ratio analysis revealed downstream migration history in H. perryi.