Application Laboratory, Japan Agency for Marine-Earth Science and Technology, Yokohama, 236-0001, Japan.
Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa, 252-0880, Japan.
Sci Rep. 2018 Apr 3;8(1):5496. doi: 10.1038/s41598-018-23820-6.
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.
近几十年来，由于人为和海洋-大气因素的影响，日本鳗鲡（Anguilla japonica）的捕捞量有所下降。基于三维粒子追踪方法，研究了海洋环流对西北太平洋日本鳗鲡捕捞量减少的潜在影响，该方法中虚拟幼鱼（v-幼鱼）被编程为在释放到北赤道流（NEC）产卵区后进行水平和垂直游动，并被海流输送。1993 年至 2013 年期间，各年的运输模式存在差异，v-幼鱼向东亚的扩散在过去二十年中减少，尤其是在台湾西部和日本地区。近年来，与 20 世纪 90 年代相比，v-幼鱼更倾向于进入南部地区，而不是进入黑潮并向东亚移动，这是由于 NEC 减弱以及产卵区附近的次表层向南流增强所致。西太平洋海洋环流的变化似乎是由于过去二十年亚热带和热带风应力卷曲减弱所致。这表明海洋环流发生了年代际变化，影响了日本鳗鲡幼鱼向其繁殖区的洄游成功。
