Physiological mechanisms of homing migration in salomon

Abstract

There are still many mysteries about the amazing abilities of salmon to migrate long distances from open water to their home streams for spawning. Three different approaches ranging from molecular biology to behavioral biology have been applied to investigate mechanisms of salmon homing migration using chum salmon (Oncorhynchus keta) from the Bering Sea to Hokkaido as well as lacustrine sockeye salmon (O. nerka) and masu salmon (O. masou) in Lake Toya and Shikotsu, Hokkaido, Japan. These fish offer good model systems for studying salmon homing migration. The endocrinological studies revealed that the brain-pituitary-gonadal axis plays leading roles in homing migration. The sensory physiological studies suggested that amino acids dissolved in the natal stream water are possible home stream odorants. The biotelemetrical studies provided new concepts for orientation ability in open water, energetics of migration, and environmental preferences of migrating fish. We are confident that these approaches using our useful model system will provide valuable new information about the physiological mechanisms of homing migration in salmon.