南太平洋长鳍金枪鱼资源不同尺度的空间格局特征

Spatial pattern characteristics of albacore tuna resources at different spatial scales in South Pacific

  • 摘要: 长鳍金枪鱼 (Thunnus alalunga) 是延绳钓渔业主要捕捞目标物种,占金枪鱼年渔获量的1/3。南太平洋的长鳍金枪鱼资源丰富,探究其渔业资源的空间格局特征,分析是否存在空间尺度差异,对其渔业资源的合理利用和保护具有重要意义。根据2015—2019年中国大陆延绳钓渔捞日志数据,按季度以3种空间尺度进行聚合 (1°、2°和5°),以及中西太平洋渔业委员会提供的5°网格数据,分别计算其空间格局特征,以比较不同空间尺度下资源分布格局的差异。结果表明:1) 南太平洋长鳍金枪鱼资源空间格局方向特征的椭圆扁率大,所有尺度的空间格局均呈现显著的东西向分布,且资源的空间格局特征 (资源的分布范围、扁率、分布方位角等) 呈明显的季节性波动特征;2) 同源的3种不同尺度数据反映的资源空间格局差异性较小,而不同源数据反映的则差异性较大;3) 在同尺度5°网格数据中,相较于中西太平洋委员会数据,渔捞日志数据中空间格局的资源中心更偏东南,偏东约10°经度;4) 采用较大尺度聚合的数据反映出的资源空间聚集特征更强,且不同尺度数据得到的资源空间热点区域有一定差异。

     

    Abstract: Albacore tuna (Thunnus alalunga) is the main target species of longline fishery, accounting for 1/3 of the annual catch of tuna. Since the fishery resources of T. alalunga are rich in South Pacific, to explore the spatial pattern characteristics of its fishery resources in that sea area, and to analyze whether there are differences in the spatial scale are important for the rational utilization and protection of its fishery resources in South Pacific. We aggregated the longline fishing logs of the Chinese mainland from 2015 to 2019 at three spatial scales (1°, 2° and 5°) by season, and calculated their spatial pattern characteristics based on the 5° grid data from Western and Central Pacific Fisheries Commission (WCPFC). The results show that: 1) The spatial pattern of T. alalunga resources in the South Pacific was characterized by great ellipticity, and there was a significant eastwest distribution in the direction of the spatial pattern at all scales. The spatial pattern characteristics of resources (Distribution range, flatness, azimuth, etc.) had similar and obvious seasonal fluctuation characteristics. 2) The spatial pattern of resources obtained from three different scales of the same origin had a small difference, while that from different sources had a great difference. 3) For the same scale of 5° grid data, the resource center of the spatial pattern in China was more southeast and about 10° east in longitude than that of the data from the WCPFC. 4) Data aggregated at larger scales reflect stronger spatial aggregation characteristics of resources. Besides, the hot spots of spatial pattern obtained from different scale data of same origin were different to some extent.

     

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