Fishing characteristics of light fishing vessels in open South China Sea based on Beidou position data

Light falling-net is one of the main fishing operations in the open South China Sea. In order to strengthen the monitoring of the production of light falling-nets in the open South China Sea and the effective management of fishing activities of fishing vessels, we had analyzed the positioning time, longitude and latitude and other characteristics based on the Beidou position data of the open South China Sea light fishing vessels from February to May 2017. Combined with the operation time, contour line, etc., we applied the multi-layer filtration method to determine the operation state of the fishing vessels. Then we filtered the fishing vessel operating locations and time by threshold, used the filter window correction method to correct the state of vessels, calculated the operation time of fishing vessels, and compared with the fishing logbook recorded by fishermen. The results show that the error between the extracted results by Beidou position data and the actual results recorded by fishmen was small. The voyage accuracy operation was 100%, and the accuracy of voyage days was 94.30%. The accuracy rate of the same fishing date was 92.72%. The total average absolute error of the operation time was 1.12 h, and the average relative error was 2.1% with good consistency. The methods of judging the state of the light fishing-net vessels, determining the operation location, extracting the operation time and calculating the fishing effort provide new ideas for the analysis of the light fishing-net vessel and the quantification of its fishing intensity.