抄録
One of the most interesting and challenging mysteries in the fish biology is the homing
mechanism of salmon to migrate long distances from the open water to their natal river for
spawning, but there are still many unknowns because the lack of a suitable model system to fol
low their whole life cycles, especially during the oceanic migration. In addition to chum salmon
(Oncorhynchus keta) that migrate from the north Pacific Ocean to Hokkaido, lacustrine sockeye
salmon (O. nerka) and masu salmon (O. masou) in Lake Toya, Hokkaido, Japan, where the lake
serves as a model ”ocean”, offer good model systems for studying the physiological mechanisms
of the homing migration in salmon. Three biotelemetry instruments (ultrasonic transmitter,
electromyographic radiotransmitter, and micro-datalogger) have been applied to investigate the
homing behaviors of mature chum, sockeye, and masu salmon. Since each instrument has great
advantages and/or minor disadvantages, we are developing an automatic salmon-tracking robot
boat consisting interrelated four equipment systems; a robot boat, an ultrasonic tracking system,
a signal processing and control system, and a telecommunication system between a land base
and the robot boat. These new biotelemetry technologies make it possible to clarify the physio
logical mechanisms of the homing migration.
