Spawning migration and redd construction of Sakhalin taimen, Hucho perryi (Salmonidae) on northern Hokkaido Island, Japan

Spatial and temporal patterns of redd construction by Sakhalin taimen, Hucho perryi , were studied in small streams on northern Hokkaido, Japan. Spawning took place in late April with close relation to discharge patterns. Observed redd size (mean ± 95% C.I.) was 145 ± 11·8 cm in length and 84 ± 5·8 cm in width. The number of egg pockets per redd was either one or two, which is fewer than that of other salmonids reported in the literature. Spawning ground distributions in 1991 and 1992 were similar to each other in terms of the distribution mean and dispersion of the redds. Unlike other salmonids Sakhalin taimen probably constructed multiple redds during one spawning season.