中小尺度下西北太平洋柔鱼资源丰度的空间变异

Spatial variability of small and medium scales' resource abundance of Ommastrephes bartramii in Northwest Pacific

西北太平洋柔鱼是我国最重要的远洋捕捞对象之一,掌握其资源分布在空间上的分布特征将可为资源的可持续开发和利用提供基础。采用2011年8—10月我国在北太平洋150°—160°E、38°—48°N海域的柔鱼生产统计数据,以单船日产量(CPUE)为资源丰度指标,分经纬度10'×10'、20'×20'、30'×30'、40'×40'、50'×50'、60'×60'和70'×70'等7个尺度,利用地统计学方法对柔鱼资源丰度的空间分布特征进行了分析,探讨柔鱼资源丰度的空间变异特性。结果显示,8—10月柔鱼资源丰度均以指数模型拟合产生的空间自相关异质性程度最好;小尺度下(10'×10'、20'×20'、30'×30')柔鱼资源丰度空间结构表现出中等水平及其以上的空间自相关变异程度,中尺度下(40'×40'、50'×50'、60'×60'和70'×70')则相对比较低,基本上为弱空间自相关变异程度;柔鱼资源丰度空间结构显示有各向异性,8月和9月的方向角分别为西北-东南走向和东北-西南走向,10月受柔鱼性成熟开始南向洄游以及海洋环境的影响,其方向角变化较大。研究认为,CPUE空间变异的研究应以小尺度为适宜,其中30'×30'最为稳定。

Ommastrephes bartramii is one of the most important fishing targets in the Chinese distant- water fishery. Understanding the spatial distribution characteristics of marine resource will provide a basis for sustainable exploiting and utilizing of resources. In this paper, the production data of Ommastrephes bartramii in the waters of 150°-160°E and 38°- 48°N in the North Pacific from August to October in 2011 was used and the capture by one fishing vessel per day （CPUE） is considered as the abundance index, the geostatistics methods were used to analyze the spatial distribution characteristics of CPUE and to explore the spatial variability of abundance index of Ommastrephes bartramii under the seven spatial scales, i. e. latitudes and longitudes for 10′×10′, 20′×20′, 30′×30′, 40′x40′, 50′×50′, 60′x60′ and 70′×70. The results show that the best spatial autocorrelation degree of heterogeneity on CPUE is described by the exponential model during August to October. Under the small spatial scales （ 10′ × 10′, 20′ × 20′ and 30′ × 30′ latitudes and longitudes ） , the spatialautocorrelation heterogeneity shows the middle level and above, while under the medium scales（40′×40′, 50′×50′, 60′× 60′ and 70′ ×70′ latitudes and longitudes ） , the spatial autocorrelation heterogeneity shows the low level. The spatial structure of O. bartramii shows anisotropic, the monthly angle directions during August to September are northwest-southeast and northeast-southwest respectively, while it has great change of angle direction in October which may be affected by the marine environment and the beginning of southwards-migration of Ommastrephes bartramii owing to maturation. It is concluded that the suitable scales for studying the spatial heterogeneity of CPUE are small scales and 30′× 30′ shows the most stable one.