以遥感夜间灯光数据为基础的西北太平洋秋刀鱼渔船识别

Detection of Pacific saury(Cololabis saira) fishing boats in the Northwest Pacific using satellite nighttime imaging data

研究和开发利用大洋性生物资源是实现我国海洋渔业可持续发展的重大战略需求,西北太平洋秋刀鱼是近年来我国重点开发的大洋性渔业资源之一,因此利用卫星来监测渔船时空分布动态成为了解秋刀鱼渔业资源变动的重要数据源。本研究采用峰值检测和阈值分割等方法对西北太平洋夜间灯光数据进行识别,利用地理信息系统技术对渔船位置信息和数量进行提取分析。通过西北太平洋秋刀鱼资源调查的渔捞日志和经过筛选的北太平洋渔业委员会(NPFC)渔船列表数据对识别结果进行验证。结果显示,本研究所用的夜间灯光渔船识别方法可以精确识别西北太平洋密集作业及外围分散作业的秋刀鱼渔船。以此为基础可以有效地分析秋刀鱼渔场的时空变动。结合美国国家海洋和大气管理局(NOAA)提供的海表温度(SST)数据绘制等温线,进一步分析作业渔场的时空变化,发现夜间灯光渔船作业的温度范围随着秋刀鱼洄游而变化。2016年7—9月渔场的SST波动较大是因为这一时期秋刀鱼在黑潮—亲潮广泛的交汇区域洄游,分布更为广泛,9月之后作业渔场SST变动趋于稳定。该研究结果将来会对远洋渔场环境实时变化、鱼群分布预测、渔船动态及法律支撑等提供有效信息。

Pacific saury(Cololabis saira) is one of the most important commercial pelagic fish species being harvested in the Northwestern Pacific Ocean region. Spatial and temporal dynamic monitoring of fishing boats has become an important data source for understanding the distributional dynamics of fisheries. Visible infrared imaging radiometer suite(VIIRS) Day/night band(DNB) night-time remote sensing images can be used to monitor night fishing boat lights. In this study, peak detection and threshold segmentation techniques were used to identify fishing boats employing DNB images in the Northwest Pacific. GIS tools were used to extract and analyze the fishing boat position and numbers. The fishing log of C. saira resources and the selected NPFC fishing boats list were used to validate the identified results. The results show that the method proposed in this study can effectively identify the location and operation status of C. saira fishing boats, and provide useful information for understanding the spatial distribution and dynamics of Pacific saury fishing zones in the northwest Pacific region.Sea surface temperature data provided by the National Oceanic and Atmospheric Administration(NOAA) were used to analyse temperature changes in the fishing ground of C. saira. The results showed that the SST range of lighting fishing boats changes with the migration of saury. From July to September 2016, the range of fishing ground SST fluctuated greatly because Pacific saury are widely distributed, making extensive migrations from subtropical to subarctic regions throughout the Kuroshio-Oyashio Currents transition zone. After September, the SST of the fishing ground tended to be stable. In the future, this information will be useful to forecast the potential fishing zone and to assess the fishing resources.