不同气候模态下西北太平洋柔鱼渔场环境特征分析

柔鱼冬春生群体广泛分布于西北太平洋,其种群分布与大小受气候变化和环境因子调控。本实验根据中国鱿钓组提供的1995—2011年渔业捕捞数据和海洋环境数据包括海表温度(SSTA)、海表面高度(SSHA)和混合层深度(MLDA)的距平值,分析不同气候模态下(PDO暖期和PDO冷期)柔鱼渔场环境的变化。结果显示,PDO暖期时,柔鱼CPUE高;PDO冷期时,CPUE变低。柔鱼渔场SSTA、SSHA和MLDA年间变化显著,各环境变量的时间变化与PDO冷暖相位对应。SSTA和SSHA与PDO指数负相关,滞后时间分别为–9~10月和–20~17月,且均在0月时相关系数最大;而MLDA与PDO指数呈正相关,滞后时间为–6~5月,在–1月相关系数最大。利用经验正交函数分析了SSTA、SSHA和MLDA时空变化的主要模态,前5个模态特征向量分别反映了西北太平洋柔鱼渔场SSTA、SSHA和MLDA分布场78.73%、32.82%和64.57%的信息。研究表明,气候模态变化驱动柔鱼渔场环境的变化,进而对西北太平洋柔鱼资源丰度产生显著影响。

Analysis of variations in the environmental conditions on the fishing ground of neon flying squid (Ommastrephes bartramii) in the Northwestern Pacific Ocean under different climate modes

The western stock of the winter-spring cohort of neon flying squid, Ommastrephes bartramii, is widely distributed in the Northwest Pacific Ocean, and its distribution and abundance are mediated by the climate variability and environmental conditions. Based on the fishery data during 1995-2011 from the Chinese Squid-jigging Science and Technology Group and the environmental data including the anomalies of sea surface temperature (SSTA), sea surface height (SSHA) and mixed layer depth (MLDA), we analyzed variability in the spatio-temporal distribution of environmental factors under different climate modes (warm and cold phases of the Pacific Decadal Oscillation, PDO). The results suggested that the catch per unit effort (CPUE) was high during the warm PDO phase and low during the cold PDO phase. Significant interannual variations were found in the SSTA, SSHA and MLDA, which corresponded to the variability of the warm/cold PDO phases. A negative correlation was found between the PDO index and the SSTA as well as the SSHA with time-lags of -9- -10 and -20-17 months, respectively, both with the highest correlation coefficient at the time-lag of 0 month; while the MLDA was positively correlated with the PDO index with a time-lag of -6-5 months, and the highest correlation coefficient occurred at the time-lag of -1 month. The empirical orthogonal function method was used to analyze the major mode of spati-temporal variability of SSTA, SSHA and MLDA, the first five modes of EOF for each environmental factor contributed to 78.73%, 32.82% and 64.57% of variation, respectively. Our findings suggested that shifts in the climate mode largely drove the variations in the environmental factors on the squid fishing ground, which led to significant abundance variability of O. bartramii in the Northwest Pacific Ocean.