The marine ecosystems around Japan are very productive and have typical wasp-waist structure dominated by small pelagic fishes such as sardine, exhibiting large low-frequency fluctuations in biomass. Whereas studies on the variability in abundance of individual species such as sardine and anchovy are popular, only a few studies focused on the long-term variability of fish assemblage around Japan. In this study, 13 species/taxa ranging from small forage to large predatory species and from warm- to cold-water species were selected to indicate essential characteristics of the fish assemblage and their drivers were analysed based on fishery, oceanographic and climatic data sets from 1901 to 2018. Results show that two outstanding peaks during the 1930s and 1980s were characterized by abundant sardine. Additionally, species composition showed high similarities during similar temperature regimes while exhibiting contrasts during different temperature regimes. Variations and regime shifts in dominant patterns and fish community indices coincided well with the Atlantic Multidecadal Oscillation (AMO) and regional sea surface temperature (SST). Furthermore, gradient forest analysis identified AMO and regional SSTs as most important predictors of dominant patterns and fish community indices, suggesting that the decadal and multidecadal variability in the fish assemblage around Japan was forced by basin-scale climate variability as inherent in the AMO through its connections with regional SSTs. Autocorrelation coefficient demonstrated that the ecological indicators have the potential to be early warning signals of regime shifts, which suggests the possibility of coming cold regime since around 2015 and has important implications for fisheries management.

中文翻译：

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上个世纪日本周围鱼类群落的长期变化和政权更替的预警信号

日本周围的海洋生态系统非常多产，具有典型的蜂腰结构，以沙丁鱼等小型中上层鱼类为主，生物量表现出较大的低频波动。尽管对沙丁鱼和凤尾鱼等单个物种丰度变化的研究很受欢迎，但只有少数研究关注日本各地鱼类群落的长期变化。在这项研究中，选择了 13 个物种/分类群，从小型饲料到大型掠食性物种，从暖水到冷水物种，以表明鱼类组合的基本特征，并根据渔业、海洋学和气候数据集分析了它们的驱动因素1901 年至 2018 年。结果显示，在 1930 年代和 1980 年代，两个突出的高峰期以沙丁鱼丰富为特征。此外，物种组成在相似的温度范围内表现出高度相似性，而在不同的温度范围内表现出差异。主导模式和鱼类群落指数的变化和制度转变与大西洋多年代际振荡 (AMO) 和区域海面温度 (SST) 非常吻合。此外，梯度森林分析将 AMO 和区域 SST 确定为主要模式和鱼类群落指数的最重要预测因子，这表明日本周围鱼类组合的年代际和多年代际变率是由 AMO 固有的流域尺度气候变率通过其与区域 SST 的联系。自相关系数表明生态指标有可能成为政权转变的预警信号，