The Prediction Model Of Recuitment Of Portunus Trituberculatus In Northern Of Zhejiang Fishing Ground

Portunus trituberculatus is one of the important marine capture species in China.It has high protein and economic value.Before 2010,the yield of P.trituberculatus was fluctuated in Zhejiang province.After 2010,however,the yield of P.trituberculatus in Zhejiang province has been rising year by year with the annual growth rate of about 30%.Except for the stock enhancement and releasing,the increase of yield should be affected by therecruitment,which is greatly affected by climate and environmental factors,particularly marine disasters.Based on the catch data of P.trituberculatusin in Northern Zhejiang sea area and the climate and environmental data from 2001 to 2014,including the grade of El Nino,the area of red tide,the typhoon wind scale,thewind speed and the sea surface height anomaly.General additive model(GAM)was used to analyze the relationship between the natural recruitment(removed the possible effect may come from the stock enhancement)of P.trituberculatus and the environmental factors(the data of 2002,2005,2008,2010 and 2012 were excluded for the used of model verification),through which tofind out the main environmental factors affecting the variation of the recruitment of P.trituberculatus.The Matlab software was used to establish multivariate linear prediction model and multivariate nonlinear prediction model to predict the recruitment of P.trituberculatus from above environmental factors.By comparing above two models,a more appropriate predict model was selected.The research results are as follows:The cumulative deviance explanation rate of the 5 factors for the recruitment was 99.1%,and the typhoon wind scale account for the largest contribution,with deviance explanation of 66.2%,and has a significant correlation with recuitment(p<0.05),The deviance explanation of the area of red tide,the sea surface height anomaly were 14.6%,9.3%respectively,which are have correlation with recuitment(p<0.1),and followed by thethe grade of El Nino,Wind speed with the contribution rate of 5.7%,3.3%which have little correlation with recuitment(p>0.1).The multivariate linear fitting equation of the resources of recuiment of Portunus trituberculatus is:R = 9555.9 + 0.1×AORT-131.6×TIOT-7011.1×SSHAThe relative error of the predicted value and the actual value of the resources of recuiment of Portunus trituberculatts are-9.8%、-23.7%、29.3%、10.7%、-7.5%in 2002、2005、2008、2010、2012.The multivariate nonlinear fitting equation of the resources of recuiment of Portunus trituberculatus is:R = 16380-0.043 × AORT-633.1 × TIOT-61678 × SSHA + 0.000044 × AORT2＋ 8.87 ×TIOT2 ＋74839×SSHA2-0.011× AORT×TIOT + 2211.7×TIOT x SSHA-3.3213 × AORT ×SSHA + 0.004 × AORT × TIOT× SSHAThe relative error of the predicted value and the actual value of the resources of recuiment of Portunus trituberculatus are 16.7%、15.9%、12.5%、41%、3.5%in 2002、2005、2008、2010、2012.Studies shows that there are significant differences bettween the two fitting equation in predicting the resources of recuiment of Portunus trituberculatus,the maximum relative error of multivariate linear fitting equation reach 41%,the results show that the fitting value and the actual value are obviously opposite trend in 2001-2002,2005-2011;the maximum relative error of multivariate nonlinear fitting equation reach 29.3%,the results show that the fitting value and the actual value are obviously opposite trend in 2005-2009.In future study,we will combine population dynamics,physical oceanography and collect more environmental factors and growth information of Portunus trituberculatus to perfect the prediction model.The results can be used as the references to study the change of abundance of Portunus trituberculatus and sustainable development management.