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

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.