Sonobuoyによる魚群検知に関するー実験

概要

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The detection of fish shoal by their swimming sound is usually made by research vessels, or, in case of set net fishing, by the cable transmission of under-water sound to coastal receiving stations. To listening simultaneously to the sea noises of several locations or surveying the fish location by the sound originated from fish school, it has been demonstrated that the sonobuoys disposition offers an easier and more economic survey. The observation is made by setting several sonobuoys at sea and receiving the under-water sound through the radio system at a coastal station. The sonobuoy device consists of hydrophone, audio amplifier, radio transmitter and receiver, speaker, pen-recorder and tape recorder. The under-water signal received by hydrophone is recorded on the penrecorder or on the magnetic tape recorder. The effective communication range of sonobuoy is up to 10km. The observation obtained at fixed set-net fishing ground has demonstrated that the sonobuoy can clearly distinguish the sound of fish school (mainly yellow-tail) from the sea noise, and that the frequency of sound generation at the entrance of set-net has a certain relation with probable catch of yellow-tail. We can conclude that in future, the forecast of fish catch may be possible by listening to the sound of fish by means of such a device.