Study of dispersal and retention of estuarine fishes in relation to the diadromy

2015 Fiscal Year Final Research Report

• Project/Area Number: 26850125
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Aquatic bioproduction science
• Research Institution: Japan Fisheries Research and Education Agency
• Principal Investigator: Yokouchi Kazuki 国立研究開発法人水産総合研究センター, 増養殖研究所, 研究員 (50723839)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: 通し回遊 / 耳石 / 比重 / 走光性 / 日齢 / 成長速度

Outline of Final Research Achievements

In this study, data analyses for riverine distribution, experiments of specific gravity, phototaxis and body growth, and estimations of individual environmental histories of euryhaline fish larvae were conducted using the Japanese grenadier anchovy Coilia nasus, which was intended to understand the dispersal and the retention of larvae having poor swimming ability in estuaries. As a result of this study, individuals dispersed in the river during egg to larval stage, and durations of the stay in the river showed large variation among individuals. Results suggested that larvae stayed surface layer of water column by swimming with positive phototaxis, and minimized volume of their swim-bladder for the reduction of resistance to water currents and downward transports by river flow during daytime. In the nighttime, it was thought that larvae stopped to swim, enlarged their swim-bladder to slow down to sink and kept the depth.

Free Research Field

魚類生態学