The role of circadian rhythm on the fish school of larval stage

Research Project

Project/Area Number	63560188
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	General fisheries
Research Institution	KYOTO UNIVERSITY
Principal Investigator	SAKAMOTO Wataru Kyoto Univ. Agriculture, Associate Professor, 農学部, 助教授 (50013587)
Co-Investigator(Kenkyū-buntansha)	UENO Masahiro Kyoto Univ. Agriculture, Technician, 農学部, 教務技官
Project Period (FY)	1988 – 1989
Project Status	Completed (Fiscal Year 1989)
Budget Amount *help	¥1,800,000 (Direct Cost: ¥1,800,000) Fiscal Year 1989: ¥700,000 (Direct Cost: ¥700,000) Fiscal Year 1988: ¥1,100,000 (Direct Cost: ¥1,100,000)
Keywords	japanese Anchovy / fish schooling / circadian rhythm / vertical shear / Wakasa Bay / fish larvae / swimming behavior recorder / 日周活動リズム / アカウミガメ / 回遊行動 / 仔稚魚 / 拡散過程 / 鉛直移動
Research Abstract	The process being formed a fish school was determined to correlate with the circadian rhythm of fish larvae and physical flow condition of the sea. The horizontal distribution density of the anchovy larvae was indicated statistically as the concentrated pattern in the surface layer. The pattern was changed by the vertical shear flow condition which was shown as the different flow direction in each depth. Vertical shear flow was measured two different layers, surface and a 10 m depth using 8 drogues. The drogues in the surface layer drifted toward northwest while in the 10 m layer they drifted toward south. This fact suggests that if the fish larvae migrate vertically in accord with the circadian rhythm they do not be dispersed by the flow since in night they rise to the surface and drift toward northern direction while in day time they can return toward southern direction in deeper layer. A new apparatus was developed to measure automatically the behavior of fish larvae throughout the day.