Abstract
Wintering habitat and focal point of masu salmon juvenile Oncorhynchus masou and white-spotted charr Salvelinus leucomaenis were studied by snorkeling surveys in two tributaries of the Ani River. All wintering habitats were found near the bottom of pools. Water velocity at the focal point of masu salmon was faster than charr. Height from the streambed at the focal point of masu salmon was higher than charr. Statistical comparison between the pools where masu salmon were present, and pools where masu salmon were absent, indicated that the “present” pools were deeper in mean water depth, and slower in mean water velocity near the bottom, than the “absent”pools. The density of masu salmon was positively correlated with mean water depth and negatively correlated with mean water velocity near the bottom in a pool. These results suggest that the deep pools with slow water velocity near the bottom are important as wintering habitats of masu salmon and white-spotted charr.
