北斗船位数据提取拖网捕捞努力量算法研究

Algorithm of fishing effort extraction in trawling based on Beidou vessel monitoring system data

传统的捕捞努力量统计耗时费力,并且存在延时,不能及时了解宏观的捕捞强度,本研究以象山港拖网渔船为研究对象,选择安装北斗终端的1 508艘渔船,对北斗卫星船位监控系统所获取的渔船船位、航向、航速等信息进行分析挖掘,获得捕捞强度。根据航速统计获得每艘渔船处于捕捞状态的航速阈值,如拖网船300791捕捞状态船位点阈值的航向差最小和最大分别是-50和52°,航速最小和最大分别是0.9和2.0 m/s,两者结合判断捕捞状态点,再采用过滤窗修正,在各渔区格网计算一段时间内渔船捕捞状态点的累计捕捞时间,其值与渔船功率的乘积获得捕捞努力量,物理单位为kW·h,并制作累计捕捞kW·h的格点图和插值图。该方法具有实时、大范围、快速、分辨率高的特点,能够很好地服务于渔业资源保护。

Fishing effort is the effort invested in fishery by the same operating method within a period of time. The traditional expression for fishing effort of trawlers is in time and power or tonnage and time. There are 40 thousand vessels installed with terminals of Beidou Satellite Navigation System in China. The vessel position information has a temporal resolution of 3 minutes and a spatial resolution of 10 meters,from which fishing effort can also be extracted. Computation for traditional fishing effort statistics takes much time and effort,and the fishing intensity in macro dimension cannot be accessed in real time. By mining the data from the Beidou satellite ship position monitoring system,such as the position,course,speed and other information of fishing boat,the fishing effort might be explored. In this paper,the speed thresholds of every fishing boat which reflect their fishing condition are obtained by the statistics of vessel speed under steam and trawling.And fishing state points can be judged by combining the speed threshold and heading deviation. The fishing state of trawler 300791 has heading difference and speed thresholds. Minimum and maximum thresholds of heading difference are- 50 and 52°. Minimum and maximum thresholds of speed is 0. 9 and 2. 0 m /s. Via the correction of the filtering window,the fishing area grid is calculated by the accumulated fishing time in fishing state point of each boat. The fishing effort is the product of the accumulated fishing time and the fishing boat power,such as kW ·h. And the lattice figure and interpolation of the accumulated fishing are made. This method has the characteristics of real-time,large-scale,fast speed and high resolution,which can provide good reference for the protection of fishery resources.