Movement patterns of adult Sakhalin taimen,Parahucho perryi,between stream habitats of the Bekanbeushi River system,eastern Hokkaido,Japan

The behavior of endangered adult Sakhalin taimen Parahucho perryi was tracked during 2008–2010 using acoustic telemetry in the Bekanbeushi River system, which flows through eastern Hokkaido, Japan. Movement distances per unit time of tracked P. perryi were compared between mid- and downstream habitats. Results indicated that movement distances were significantly longer in downstream habitats during all seasons. The movement distances in each stream decreased from spring to autumn. Moreover, tracked P. perryi exhibited crepuscular movement patterns; however, patterns were less pronounced in downstream habitats than in up- and midstream habitats. These findings strongly suggested that adult P. perryi exhibit nearly distinctive movement patterns across stream habitats; thus, fish may adopt different foraging tactics in each stream habitat. Fish moved more frequently in spring, which included the post-wintering and post-spawning season, most likely to search for food and more desirable habitat for recovery.