Japan Geoscience Union Meeting 2018

Presentation information

[EE] Oral

H (Human Geosciences) » H-CG Complex & General

[H-CG21] Climate-human system interaction

Mon. May 21, 2018 1:45 PM - 3:15 PM A02 (Tokyo Bay Makuhari Hall)

convener:Kaoru Tachiiri(Japan Agency for Marine-Earth Science and Technology), Tokuta Yokohata(National Institute for Environmental Studies), Katsumasa Tanaka(国立環境研究所, 共同), KIYOSHI TAKAHASHI(National Institute for Environmental Studies), Chairperson:Tanaka Katsumasa(National Institute for Environmental Studies), Takahashi Kiyoshi(National Institute for Environmental Studies)

3:00 PM - 3:15 PM

[HCG21-05] Potential impact of ocean circulation on the declining Japanese eel catches

*Yu-Lin Eda Chang1, Yasumasa Miyazawa1, Michael Miller2, Katsumi Tsukamoto2 (1.Application Laboratory, Japan Agency for Marine-Earth Science and Technology, 2.Nihon University)

Recruitment of Japanese eels, Anguilla japonica, has declined in recent decades possibly due to both anthropogenic and ocean-atmosphere factors. The potential impact of ocean circulation on the decreasing Japanese eel catches in the western North Pacific was examined based on a three-dimensional particle-tracking method, in which virtual larvae (v-larvae) were programmed to swim horizontally and vertically, in addition to being transported by ocean currents after being released in their North Equatorial Current (NEC) spawning area. Transport patterns varied among years between 1993 and 2013, and dispersion of v-larvae towards East Asia decreased in the last two decades, especially for the western Taiwan and Japan regions. In recent years, instead of entering the Kuroshio and moving towards East Asia as in the 1990s’, more v-larvae tended to enter the southern areas due to the weakening of the NEC and strengthening of subsurface southward flow near the spawning area. Changes in ocean circulation in the western Pacific appear to be caused by the weakening of subtropical and tropical wind stress curl in the past two decades. This suggests that decadal changes in ocean circulation have occurred that affect the larval migration success of the Japanese eel to their recruitment areas.