STUDY ON REASON WHY AYU MIGRATES FROM SEA TO RIVER
The ayu, Plecoglossus altivelis altivelis, migrates from the sea to the river in spring.Hotta(1953) pointed out that the reason why the ayu migrates is coincidence of water temperatures in the river and sea. Wada(1990) pointed out that the water level at the sea greatly affects on the migration number. However, a collective view has not been obtained. In this study, the water level, water temperature, pH, DO, COD, electric conductively, turbidity when the ayu migrates and those when the ayu does not migrate were compared. The ayu wants to migrate when the water temperature is high, the sea water level is high. On the other hand, the ayu does not want to migrate when the discharge is high, due to the water temperature decreases. In such a situation, sometimes DO becomes high.
ayu migration environmental factor Nagaragawa Estuary Barrage
Takayuki Nagaya Yoshiki Shiraishi Kouki Onitsuka Makoto Higashino Tohru Takami Hitoshi Higashi Juichiro Akiyama Atsushi Ono Yoshinobu Akaki
CTI Engineering Co., Ltd., Fukuoka, Japan Civil Engineering, Kyushu Institute of Technology, Kitu-Kyushu, Japan Oita National College of Technology, Oita, Japan Ministry of Land, Infrastructure and Transport Japan, Nobeoka, Japan Oita Prefectural, Oita, Japan
国际会议
第16届亚太地区国际水利学大会暨第3届水工水力学国际研讨会(16th IAHR-APD Congress and 3rd Symoposium of IAHR-ISHS)
南京
英文
435-440
2008-10-20（万方平台首次上网日期，不代表论文的发表时间）