Influence of fish diurnal behavior on acoustic biomass estimation
1999
Ohshimo, S. (Seikai National Fisheries Research Inst., Nagasaki (Japan)) | Katoh, O. | Morinaga, K.
The influence of diurnal fish behaviors on its biomass estimations was studied using acoustic methods, an ADCP and a quantitative echo sounder. The survey was carried out during 11th to 15th January 1994 with the R/V Yoko-maru, and four transects were executed off the western coast of Kyushu. The acoustical data of ADCP and quantitative echo sounder were collected by a new method using four round-trip surveys along each on a transect with a length of about 30 miles during a time period of 24 hours and 50 minutes. Additionally, CTD casts were conducted at an interval of about 3 nautical miles on each transect. A coastal front was formed in the eastern part of the transect between the Goto Islands and Kyushu, and a southward current was clearly observed there. Many fish schools were clearly observed at the coastal front in the Goto-Nada. The estimated biomass varied in a day. In the present study, the acoustic problems resulting from fish behavior were discussed quantitatively
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