Assessing the Fishery Resource Status of China’s Coastal Waters Using Surplus Production Models

Surplus production models(SPMs)are among the simplest and most widely used fishery stock assessment models.The catch-effort data analysis(CEDA)and a surplus production model incorporating covariates(ASPIC)are softwares for analyzing fishery catch and fishing effort data using nonequilibrium SPMs.In China Fishery Statistical Yearbook,annual fishery production and fishing effort data of the Yellow Sea,Bohai Sea,East China Sea,and South China Sea have been published from 1979 till present.Using its catch and fishing effort data from 1980 to 2018,we apply the CEDA and ASPIC to evaluate fishery resources in Chinese coastal waters.The results show that the total maximum sustainable yield(MSY)estimate of the four China seas is 10.05-10.83 million tons,approximately equal to the marine fishery catch(10.44 million tons)reported in 2018.It can be concluded that China’s coastal fishery resources are currently fully exploited and must be protected with a precautionary approach.Both softwares produced similar results;however,the CEDA had a much higher R2 value(above 0.9)than ASPIC(about 0.2),indicating that CEDA can better fit the data and therefore is more suitable for analyzing the fishery resources in the coastal waters of China.

Can soil respiration estimate neglect the contribution of abiotic exchange?

This study examines the hypothesis that soil respiration can always be interpreted purely in terms of biotic processes, neglecting the contribution of abiotic exchange to COg fluxes in alkaline soils of arid areas that characterize 5% of the Earth＇s total land surface. Analyses on flux data collected from previous studies suggested reconciling soil respiration as organic （root/microbial respiration） and inorganic （abiotic CO2 exchange） respiration, whose contributions in the total CO2 flux were determined by soil alkaline content. On the basis of utilizing mete- orological and soil data collected from the Xinjiang and Central Asia Scientific Data Sharing Platform, an incorpo- rated model indicated that inorganic respiration represents almost half of the total CO2 flux. Neglecting the abiotic module may result in overestimates of soil respiration in arid alkaline lands, which partly explains the long-sought ＂missing carbon sink＂.

Model for end-stage liver disease-sodium predicts prognosis in patients with chronic severe hepatitis B

Background Serum sodium predicts prognosis in chronic severe hepatitis B and may improve the prognostic accuracy of the model for end-stage liver disease （MELD） score, but the available information is limited. The present study was undertaken to study the clinical use of the serum sodium incorporated MELD （MELD-Na） and assess its validity by the concordance （c）-statistics in predicting the prognosis of the patient with chronic severe hepatitis B.Methods A total of 426 adult patients with a diagnosis of chronic severe hepatitis B between January 1, 2007, and December 31, 2007 at a single center were studied. The scores of serum sodium, MELD, MELD-Na, and ΔMELD-Na （ΔMELD-Na=MELD-Na at 14 days after medical treatment -MELD-Na score on admission） of the patients with chronic severe hepatitis B were calculated. The 3-month mortality in the patients was measured, and the validity of the models was determined by means of the concordance （c） statistics.Results The average MELD, MELD-Na scores of survival group were 25.70±5.08 and 26.60±6.90, and those of dead group were 35.60±6.78 and 42.80±9.57 on admission. There was a significant difference in MELD and MELD-Na between the survival and dead groups （P 〈0.01）. The average △MELD-Na score of the survival group was -0.97±3.51, and that of the dead group was 3.45±2.38 at 2 weeks after the treatment. There was a significant difference in △MELD-Na between the survival and dead groups （P 〈0.01）. The areas under the receiver-operating characteristic curves of Na, MELD and MELD-Na for the occurrence of death in 3 months were 0.742, 0.875 and 0.922. The 3-month mortality of the MELD-Na scores group 〈25, 25-30, 31-34, 35-40 and 〉40 were 2.0%, 5.4%, 35.4%, 53.8 % and 86.9%, respectively. There was a significant difference in the 3-month mortality between the five groups （P 〈0.05）. The 3-month mortality of the △MELD-Na〉0 group was 65.9%, and that of the △MELD-Na ≤0 group was 15.8%; there was a significant difference in the 3-month mortality between the two groups （P 〈0.05）.Conclusions MELD-Na score is a valid model to predict the 3-month mortality in patients with chronic severe hepatitis B. △MELD-Na is a clinically useful parameter for predicting the therapeutic effect of chronic severe hepatitis B.

Impact of Renewable Energy Sources on Steady-state Stability of Weak AC/DC Systems

In recent years,the penetration of renewable resources into AC power systems has increased tremendously,creating a significantly impact on the latter’s operations and stability.In this respect,it is also important to gain a basic analytical understanding of such impact on the steady-state stability of power systems with electrically weak AC/DC interconnections,but such works are not very evident in the literature.Therefore,a classical analytic model of the single and multi-infeed HVDC system which now incorporates renewable resources is proposed.Then the well-established concept of voltage sensitivity of the AC/DC interconnection is applied to analyze the impact of the renewable resources on the steady-state stability of these composite system models,as well as on the influence of system conditions and parameters.This impact is also compared with that arising from other types of shunt devices alternatively connected at the same AC/DC interconnection,therefore their relative beneficial or negative impacts will also be benchmarked.

Assessing recent gradual upsurge of marine captured Hilsa stock(Tenualosa ilisha)in Bangladesh

The anadromous Hilsa shad(Tenualosa ilisha)fishery is the prime single species fishery of Bangladesh that driven by open access system which was selected for this study.Key purpose of this study was to assess the MSY(Maximum Sustainable Yield)in order to review the effectivity of the ongoing management policy of this fishery.For this reason,time series maritime or downstream catch-effort data of the Bay of Bengal were assembled from the Department of Fisheries,Bangladesh.MSY,CPUE and other population parameters were estimated through Surplus Production Models(SPMs)using computer software packages of CEDA,ASPIC and TropFishR.Assessed biological reference points of MSY from the best fitted CEDA package was 282,100 t(R^(2)=0.822)for the normal assumptions of the Schaefer and Pella-Tomlinson models.MSY values from the ASPIC packages(324,100 t and 263,500 t;for Fox and Schaefer model)and Schaefer model from TropFishR(345,486t)were larger than the catch in 2017(278,948 t).The values of F ratio(F/FMSY)for all SPMs were found less than 1 and B ratio(B/BMSY)were greater than 1 that clearly indicate the gradual upsurge of the Hilsa stock.Based on the above findings of BRPs,it also proves the effectivity of the current“Hilsa fishery management action plan”by the authorities.