The Spatial-temporal Distribution And The Construction Of The Prediction Model Of The Purpleback Flying Squid(Sthenoteuthis Oualaniensis) In South China Sea

In recent years,the fishing pressure is oversized and the decline of the fishery resources is quite serious.As oceanic cephalopods,Sthenoteuthis oualaniensis has abundant biological resources in the South China Sea China,therefore,it is economically beneficial to develop its ocean-going fishing and it is good to share the inshore fishing pressure so as to protect the inshore fishery resources.This thesis carried out a study on the purpleback flying squid(Sthenoteuthis oualaniensis)fishing ground in the South China Sea by making use of the squid production data collected by the Beidou fishery information collection system in the Center of South China Sea Fisheries Resources Monitoring and Assessment and the environmental data sensed by the French Kaiser remote.The overall analysis of the characteristics of Sthenoteuthis oualaniensis fisheries is demonstrated by studying the temporal-spatial distribution,the barycenter fishing ground distribution,the correlation between the environment and the fishing ground and establishing the fishing ground forecasting model.The datum provided by the Beidou fishery information collection system include information on fishing vessels operating in the South China Sea in 2012 ~2014 and their production data(Total of 1361 cases).The datum provided by the Beidou fishery information collection system include information on fishing vessels operating in the South China Sea in 2012 ~2014 and their production data.The datum offered by the France Kaiser remote sensing system comprise sea surface temperature,sea surface salinity,sea surface height,the thermocline depth and chlorophyll a concentration,and the deep remote sensing datum consisting of the tempreture and the salinity in 20 m,30m,50 m,75m,100 m,125m,150,200 m,250m and 300 m water layer.The results are as follows:1.This study has 87.5% light falling net fishing operate in the South China Sea in 9° ~12° N waters.The central Sthenoteuthis oualaniensis fishing ground is more likely to locate 9°~12° north latitudein the South China Sea.China's fisheries environment reflects that the fishermen prefer to fisheries production at 12°N in the South China Sea.The CPUE by the vessel in the South China Sea reaches 2000kg/(vessel·d).2.The barycenter of the Sthenoteuthis oualaniensis fishing ground in the South China Sea is in 11°N,113°E waters which includes the Nansha Islands sea waters where the fishmen mainly operate nearby and where exists a larger Sthenoteuthis oualaniensis fishing ground.There are 1596 kg/(vessel·d)mean CPUE in the barycenter sea area;2018 kg/(vessel·d)in the rich sea area and 1617 kg/(vessel·d)in the potential sea area.3.Generalized linear model results show the following three points.First,among the temporal and spatial factors,year and CPUE suffer the greatest influence,followed by longitude,month and latitude.Second,among the environmental factors,sea surface height and CPUE suffer the greatest influence,followed by the sea surface salinity,sea surface temperature,chlorophyll concentration and thermocline depth.Third,among the interaction factors,these pairs reach a higher degree of influence such as year and sea surface height,longitude and sea Surface height while other interaction factors have a relative low influence degree.The interaction between the temporal-spatial factors and the environmental factors can provide a better explanation for the change of the fishing ground than the influence degree of the single factor to a certain extent.4.These five environmental factors can capture more considerable Sthenoteuthis oualaniensis resources in the appropriate range.First,the sea surface height is below 0m is a more suitable habitat for Sthenoteuthis oualaniensis.Second,the sea surface temperature range from 26? to 29?,which exists little difference compared with other scholars? point of view.Third,the sea surface salinity is in the range of 33.0~33.5‰ and change slightly.Four,the chlorophyll concentration is 0.05~0.10?g/L.when the chlorophyll concentration is above 0.3?g/L inshore,considerable economic benefits are promised.The optimum range of the chlorophyll concentration in ocean-going fishing is opposite to that in inshore fishing.Five,the thermocline depth ranges from 20 m to 40 m which is just the working depth of the light falling net.5.Based on the Bayesian prediction model,the success rate prediction of the Sthenoteuthis oualaniensis low yield fishing ground in the South China Sea is relatively high,which reaches 65.90% while that high yield one is lower,which adds up to 45.57%.The whole Bayesian probability model success rate is 61.18%,which shows that it can provide a quite reliable prediction for the situation of Sthenoteuthis oualaniensis fishing ground in the South China Sea.6.The high yield success rate judged by the classification tree model is 43.36%,while the low yield one is 72.22%.Besides,the overall success rate is 55.58%.Estimated from the average CPUE of the forecast values,the low yield category success rate is 66.66% while the high yield category success rate is 88.88%.Moreover,the category overall success rate is 76.19%.It is unrealistic to predict the case in the fish ground correctly under the condition of complex and changeable ocean environment.However,it is fairly reliable to make a relatively correct judgement on fish ground category by using the fisheries information cumulative by classification tree model.