| Fishing boat monitoring is an important source for acquiring fishing information of fishing boat.Based on nighttime light remote sensing technology,it can provide an up-to-date monitor of fishing boats which use fish lamp at night to attract fish.Compared with the traditional fishing boat monitoring measures,fishing boat monitoring by nighttime light remote sensing technology has the advantages of low cost and high accuracy,which has a good development prospect in marine fishery.But,the pelagic light-fishing boats monitoring by nighttime light remote sensing is still using the way of visual interpretation to extract the fishing information of operating pelagic light-fishing boats.The missing of an automatic algorithm for extracting and reporting the detection of operating pelagic light-fishing boats has limited its application in pelagic light-fishing fishery.Designing an automatic detection algorithm for operating pelagic light-fishing boats based on nighttime light remote sensing image,can provide a new,low cost,near real time,high precision fishing boats operating information source,which has important significance in pelagic light-fishing fishery informatization management,fishery resource assessment,fishing ground analysis,fishery forecast and safeguarding the legitimate rights and interests of fishing boats.The main contents of this paper are can be summarized as follows:(1)Using the DNB image of NPP/VIIRS,designed an automatic detection algorithm for operating pelagic light-fishing boats which based on the spike median index(SMI),maximum entropy method(MaxEnt)threshold segmentation and local spike detection(LSD).The accuracy of the algorithm is 92% or more which was verified by the data of the vessel monitoring system(VMS)data in the chub mackerel light-seine fishing ground of the Northwestern Pacific Ocean of 2015;(2)Based on the automatic detection algorithm for operating pelagic light-fishing boats,there are 120 effective days,totaling 4644 effective fishing information data were collected in the main fishing season of the chub mackerel(Scomber japonicas)in the northwest Pacific Ocean of 2015.(3)Combined with satellite sea surface temperature(SST)and sea surface height(SSH)data,a generalized additive model(GAM)was used to study the effects of SST and SSH on the fishing effort of the chub mackerel light-seine boats in the Northwestern Pacific Ocean;a visualization analysis by arcgis was used to analyze the spatialtemporal distribution characteristic and the potential relationship between SST,SSH and fishing effort of chub mackerel light-seine boats;and then the method of frequency analysis and empirical cumulative distribution function(ECDF)was adopted in order to find out the suitable SST and SSH range for chub mackerel light-seine boats.The results are as follows: SST and SSH have significant correlation with the fishing effort of chub mackerel light-seine boats,and SST has a higher effect than SSH.The fishing effort of chub mackerel light-seine boats is concentrically distributed at the confluence of oceanic fronts,close to the cold front side;and the confluence of cold eddies and warm eddies,near the cold eddies side.The SST range from 11.9 ℃ to 17.2 ℃ and the SSH range from 13.6 cm to 37.0 cm can be regarded as an indication of the suitable fishing environment for chub mackerel light-seine boats.The innovation work of this paper is mainly as followed:(1)Designed an automatic detection algorithm for operating pelagic light-fishing boats based on NPP / VIIRS night light remote sensing image,provided a supplemental fishing information data source for pelagic light-fishing fishery.(2)Explored the application in fishing ground analysis of fishing information data of pelagic light-fishing boats which was extracted by nighttime light remote sensing images.provided a new idea to solve the problem of shortage of fishing condition information in pelagic light-fishing fishery caused by the lack of fishery data. |
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