Graduate School of Frontier Sciences/Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan.
Institute of Fisheries Science and Department of Life Science, College of Life Science, National Taiwan University, Taipei, Taiwan.
PLoS One. 2018 Apr 10;13(4):e0195544. doi: 10.1371/journal.pone.0195544. eCollection 2018.
Spawning ground of Japanese eel (Anguilla japonica) is located near the West Mariana Ridge seamount. The species travels through the North Equatorial Current (NEC) and then enters the Kuroshio Current (KC) on the migration toward East Asian growth habitats. Therefore, El Niño-Southern Oscillation (ENSO) events serve as the potentially important drivers of interannual variability across the equatorial Pacific. Because the NEC bifurcation and salinity profiles are related to ENSO events, we investigated the influence of locations of the NEC bifurcation and salinity front on the success of larval entry to the KC by numerically modeling particle transport in ocean currents from 1972 to 2013 and possible effects on the size of glass eels at continental recruitment and, via otolithometry on the duration of larval migration. Circulation and hydrography used for particle tracking were obtained from the results of the Model for Interdisciplinary Research on Climate (MIROC) high-resolution forecasting experiment. Our results demonstrated that during El Niño years, (1) the southward movement of the salinity front might cause the larvae to experience slower currents and (2) the northward movement of the NEC bifurcation might broaden the separation between their spawning ground and NEC bifurcation, thus prolonging the time needed for the larvae to enter the KC from their spawning ground, because of which the duration of entrainment in the water column and body size increase when eels reach estuarine waters. In addition, this might cause more water to flow into the Mindanao Current (MC), leading to a decline in the rate at which larvae get entrained into the KC.
日本鳗鲡（Anguilla japonica）的产卵场位于西马里亚纳海山附近。该物种在洄游到东亚生长栖息地的过程中，通过北赤道流（NEC），然后进入黑潮（KC）。因此，厄尔尼诺-南方涛动（ENSO）事件是赤道太平洋年际变化的潜在重要驱动因素。由于 NEC 分支点和盐度剖面与 ENSO 事件有关，我们通过数值模拟 1972 年至 2013 年期间海流中的颗粒输运，研究了 NEC 分支点和盐度锋的位置对幼体进入 KC 的成功的影响，以及对大陆补充时玻璃鳗大小的可能影响，并通过耳石测量来研究幼体洄游时间的影响。用于粒子跟踪的环流和水文学资料来自气候多学科研究模型（MIROC）高分辨率预测实验的结果。我们的结果表明，在厄尔尼诺年，（1）盐度锋的南移可能导致幼虫经历较慢的海流，（2）NEC 分支点的北移可能扩大它们的产卵场和 NEC 分支点之间的分离，从而延长幼虫从产卵场进入 KC 所需的时间，由于这个原因，鳗鱼到达河口水域时，在水柱中的停留时间和身体大小增加。此外，这可能导致更多的水流入棉兰老流（MC），从而降低幼虫进入 KC 的速度。
