Recent observational and numerical studies have suggested that the decadal modulation of the Kuroshio Extension system, driven by mesoscale eddies, profoundly affect the basin scale physical and biogeochemical oceanography. However, it remains unclear how these decadal changes affect distribution and abundance of fish species in this region. In this study, 26,964 swordfish catch data obtained by longliners during 2004–2010 in the western North Pacific are analyzed with an eddy-resolving ocean reanalysis by using mesoscale dynamic parameters and an eddy detection technique, to clarify the effects of mesoscale eddies and their variabilities on the swordfish relative abundance. During this period, the Kuroshio Extension underwent two different dynamic phases: stable path state in 2004, 2005, and 2010; and unstable path state during 2006–2009. Based on our analyses, we show here that swordfish are more concentrated in and near the anticyclonic warm-core eddies in the northern site, 36–45°N, of the Kuroshio Extension system, especially during the unstable path phase. This is found to be caused by the interannual modulation of mesoscale eddy activities due to more warm-core rings generated from the unstable Kuroshio Extension, making it easier for fishermen to target swordfish in this region.

中文翻译：

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中尺度暖核涡流驱动黑潮扩展系统中箭鱼捕捞的年际调制

最近的观测和数值研究表明，由中尺度涡流驱动的黑潮扩展系统的年代际调制深刻影响了盆地尺度的物理和生物地球化学海洋学。然而，尚不清楚这些年代际变化如何影响该地区鱼类的分布和丰度。本研究利用中尺度动力参数和涡流探测技术，对2004-2010年延绳钓渔船在北太平洋西部获得的26,964条旗鱼捕捞数据进行了涡旋分辨海洋再分析，以阐明中尺度涡旋的影响及其变化关于箭鱼的相对丰度。在此期间，黑潮延伸经历了两个不同的动态阶段：2004年、2005年和2010年的稳定路径状态；2006-2009 年的不稳定路径状态。根据我们的分析，我们在这里表明，旗鱼更集中在黑潮延伸系统北部 36-45°N 的反气旋暖核涡流中和附近，尤其是在不稳定的路径阶段。发现这是由于不稳定的黑潮扩展产生的更多暖核环导致中尺度涡旋活动的年际调制引起的，使渔民更容易在该地区捕捞旗鱼。