Abstract:

In order to explore the impact of climate change on fishery resources, using the 2008—2017 Argo grid data (BOA_Argo) and the fishing log data of commercial fishing vessels during the same period, the temporal and spatial characteristics of the thermocline in the main fishing grounds of the yellowfin tuna purse seine in the western and central Pacific Ocean in La Ni’a and El Ni’o years were studied. Combined with GAM (generalized additive model) model, the variables affecting yellowfin tuna were analyzed. The results showed that, in the La Ni’a year, the CPUE moved westward as the high-value zone of the upper bound contracted westward, up to 145°E, and in the El Ni’o year, the CPUE was moved eastward to 165°E. Compared with normal years, the upper boundary depth difference of the thermocline on the east and west sides of the equatorial Pacific was larger than that of the normal year, and the upper boundary depth of 80~130 m was westward. The strength of the thermocline was generally weak in the west and strong in the east. The thickness of the thermocline was based on 15°N and 15°S, and each had a thick band-like distribution structure. The CPUE was distributed in 120—200 m thick. When the temperature range of the upper boundary of the thermocline was 27.5~29.5 ℃ and the intensity range was 0.08~0.13 ℃·m^-1, the CPUE distribution was denser. The upper-bound temperature had the greatest impact on the CPUE. The eastward shift of the CPUE in El Ni’o and the westward shift of the CPUE in La Ni’a moved with the optimal parameter values of the fishing site in the thermocline. The factor of year had a fluctuating effect on the CPUE, and the influence of the La Ni’a year on the CPUE was closer. The areas with high abundance were 5°N—5°S, 150°E—175°E. From the above, the change of thermocline caused by abnormal climate had significant effect on CPUE.

Key words: Central and Western Pacific, thermocline, yellowfin tuna, CPUE, El Nio, La Nia, GAM model

摘要： 为研究气候变化对渔业资源的影响，采用2008—2017年全球海洋Argo网格数据集（BOA_Argo）和同期商业渔船渔捞日志数据,分析了拉尼娜和厄尔尼诺年中西太平洋黄鳍金枪鱼围网主要作业渔场温跃层的时空变化特征，结合GAM（generalized additive model）对影响黄鳍金枪鱼渔场的变量进行分析。结果表明，拉尼娜年，单位捕捞努力量渔获量(catch per unit effort, CPUE)随温跃层上界温度的高值区向西收缩而西移，最西至145°E；厄尔尼诺年，东移至165°E以东。拉尼娜年较正常年份，赤道太平洋东、西侧温跃层的上界深度差拉大，80~130 m上界深度值偏西。温跃层强度整体上呈现西弱东强，温跃层厚度以15°N和15°S为轴线，分别存在一个较厚的带状分布结构，CPUE分布在厚度值120~200 m之间。温跃层上界温度为27.5～29.5 ℃、强度为0.08～0.13 ℃·m^-1时，CPUE分布密集，温跃层参数中上界温度对CPUE分布的影响最大。且厄尔尼诺年CPUE的东移和拉尼娜年CPUE的西移随渔场所在温跃层的最适参数值而移动。时间因子中年份对CPUE的影响是波动性的，拉尼娜年对CPUE的影响更密切。资源丰度较高海域在5°N—5°S，150°E—175°E。综上所述，异常气候导致的温跃层变化对于CPUE具有显著影响。

关键词: 中西太平洋, 温跃层, 黄鳍金枪鱼, CPUE, 厄尔尼诺, 拉尼娜, GAM模型