Swim behavior and temperature selection of homing chum salomon

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Aquatic animals often show migration behavior and strong homing behavior. The salmons are well known for their strong homing behavior. Chum salmon return to their natal river after spending for a few years for feeding in the North Pacific. Thus many scientists are interested min such behavior and studied on their mechanisms of homing behavior and mechanisms of osmo regulation system from point view of physiology and behavior. However nothing is known how salmon swim in the ocean. We conducted the experiments of measurement of their swim behavior and ambient temperature by attaching the micro data loggers during their homing migration to the natal river and examined how temperature environment affect their migration behavior. The results showed that fish avoid high temperature water mass of the surface layr and sank to the bottom. This was understood that fish saved their energy loss by swimming cooler water and then they detected the bottom topography for their geolocation to compensate the odor homing mechanism which only function in the surface layr.