基于ESDA的西北太平洋柔鱼资源空间热点区域及其变动研究

Abstract

以西北太平洋（150°E-160°E、38°N-45°N）柔鱼<em>Ommastrephes bartramii</em>为研究对象，以2007和2010年鱿钓渔业的原始点位数据为基础，利用常规统计和探索性空间数据分析（ESDA）中的全局空间自相关分析方法，对西北太平洋柔鱼资源空间分布及其变动进行了研究。结果表明，西北太平洋柔鱼资源呈现较强的聚集分布特征，但不同空间位置差异较大。利用GIS和ESDA的局部自相关方法进行了柔鱼资源热冷点空间分布的制图，结果显示2007年研究区存在3个显著的热点和1个冷点，2010年与之存在较为明显的差异，具有1个热点和4个冷点。变化检测分析表明，两个年份间出现1个热点区域和1个冷点区域未发生变化，另有2个区域从2007年热点变成2010年冷点；此外，非热冷点之间的变动在研究区占据了主导地位。景观指数分析表明，研究区柔鱼资源热冷点格局的复杂性和自相似性并不高，但其异质性和聚集性非常强，且整体性和凝聚度均很高。分析认为，2007年西北太平洋柔鱼渔区的形成受温度和海流的影响，近一半作业渔区产量相对较高，但并未充分保证空间热点的大面积形成，空间热点和冷点分布面积大致相当；2010年整个西北太平洋柔鱼渔场受亲潮势力影响，空间热点较为集中、空间冷点较多且分散。;The oceanic cephalopod <em>Ommastrephes bartramii</em> is widely distributed in the northwestern Pacific Ocean and is an important target species for the fishing industries of Japan, South Korea, China and Chinese Taiwan. Owing to the effects of global climate change and increased fishing activities, the spatial patterns and hot spot dynamics of <em>O. bartramii </em>resources are changing. This study focused on <em>O. bartramii</em> resources, especially within the boundaries of 150°E-160°E and 38°N-45°N, in the northwestern Pacific Ocean. Based on original fishing data from Chinese boats, the study aimed to explore the spatial structure of <em>O. bartramii</em> resources using integrated methods of spatial statistics, global spatial autocorrelation, change detection and landscape metrics. Classical statistics and global spatial autocorrelation-based primary analysis showed that there were vast differences in the resource abundance of <em>O. bartramii </em>over the study area. A relatively strong aggregated distribution was observed for <em>O. bartramii</em> in the northwestern Pacific Ocean. In addition, spatial hot and cold spot maps were produced for the years of 2007 and 2010 using both a geographic information system and local spatial autocorrelation methods. The maps illustrated that there were three obvious hot spots and one cold spot for <em>O. bartramii</em> in the northwestern Pacific Ocean in 2007, whereas in 2010 there was one obvious hot spot and four cold spots. Change detection demonstrated that only one spatial hot spot remained unchanged between 2007 and 2010, while two areas showed a change in status from hot to cold spots. In addition, only one of the cold spots remained unchanged between 2007 and 2010. As a result, the non-hot and non-cold spots that showed non-aggregated or random distributions dominated the pattern of <em>O. bartramii</em> in the northwestern Pacific Ocean. Landscape metrics were also employed in this study to mine the implicit information and knowledge of hot/cold spots of <em>O. bartramii</em> resources. This research demonstrated that relatively low complexity and self-similarity were observed for the <em>O. bartramii</em> resource, while strong spatial heterogeneity and aggregation, as well as high integrity and cohesion, were detected for the same fishery resource. Finally, a sea surface temperature-based analysis revealed the marine environmental characteristics and dynamics of spatial hot/cold spots of <em>O. bartramii</em> in the northwestern Pacific Ocean in both 2007 and 2010. The results showed that, owing to the influence of sea surface temperature and currents within the fishing area of the northwestern Pacific Ocean, approximately half of the area has relatively high production. However, high production alone cannot account for the hot spot clustering within most of the study area. Hence, in 2007, only 7.0% of the study area was classified as hot spots, while most of the area comprised cold spots or areas that were not statistically significant. As a result of the Oyashio Current, the fishing grounds distributed at 40°-45°N and 154°-158°E during the best fishing period displayed relatively aggregated spatial hot spots in 2010, whereas the spatial cold spots were scattered across the northwestern Pacific Ocean.