Development of a migration path and environmantal factor recording system

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The developing process is separated into two parts ; one is the development of an apparatus of ultrasonic pinger to know fish heart beat rate in free-ranging natural swimming condition and the other is to develop new sonic signal receiving and positioning system through sonic signals of a pinger on the ship with higher than 5 knot towing speed. The final goal is to combine both systems effectively and available in the sea for long periods. The receiving and positioning system is consisted of 4 phydrophones and its analyzing system through personal computer. The target fish direction is able to detect the difference of sound pressure among phydrophones as well as heart beat rate. The heart beat rate is measured by an electrode inserted into the muscle near the heart of the test fish. It was transformed into electro volt through a pre-amplifier to make a sonic signal. We can count these sonic signals through the phydorphone system on the ship. The new recording system was tested at first in 1997 at the Wakasa Bay using an adult red sea bream for 2 months and obtained its swimming path and migration behavior. The heart rate beat was recorded in the artificial fish farming pond in Hakatashima in 1997. Heart beat rate was continuously measured for 30 hours. We found the system is able to use in the sea.