On the records of Internal Wave type of the Ultrasonic Scattering Layer in the East China Sea by the Fish-finder I

The observation was carried out on board the Kagoshima-maru, Faculty of Fisheries Kagoshima University, in the middle area of the East China Sea, in the latter part of March, 1975. The ultrasonic scattering layers of internal wave type were recorded by 200 KHz fish-finder. The following results were obtained. (1) Internal wave type SL and internal wave type DSL were recorded by 200 KHz fish-finder. (2) The wave-motions of internal wave type were grouped into three classes. (3) The wave height of internal wave type was normally 3-5 meters high, and the wave period was normally less than 5 minutes. (4) It was not clear from the results of this survey but the cause of internal wave type may not be biological factor but internal wave which caused in the sea