Catch and effort data were analyzed to estimate the maximum sustainable yield （MSY） of King Soldier Bream, Argyrops spinifer （Forsskal, 1775, Family： Sparidae）, and to evaluate the present status of the fish stoc...Catch and effort data were analyzed to estimate the maximum sustainable yield （MSY） of King Soldier Bream, Argyrops spinifer （Forsskal, 1775, Family： Sparidae）, and to evaluate the present status of the fish stocks exploited in Pakistani waters. The catch and effort data for the 25-years period 1985-2009 were analyzed using two computer software packages, CEDA （catch and effort data analysis） and ASPIC （a surplus production model incorporating covariates）. The maximum catch of 3 458 t was observed in 1988 and the minimum catch of 1 324 t in 2005, while the average annual catch ofA. spinifer over the 25 years was 2 500 t. The surplus production models of Fox, Schaefer, and Pella Tomlinson under three error assumptions of normal, log-normal and gamma are in the CEDA package and the two surplus models of Fox and logistic are in the ASPIC package. In CEDA, the MSY was estimated by applying the initial proportion （IP） of 0.8, because the starting catch was approximately 80% of the maximum catch. Except for gamma, because gamma showed maximization failures, the estimated results of MSY using CEDA with the Fox surplus production model and two error assumptions, were 1 692.08 t （R^2=0.572） and 1 694.09 t （R^2=0.606）, respectively, and from the Schaefer and the Pella Tomlinson models with two error assumptions were 2 390.95 t （R^2=0.563）, and 2 380.06 t （R^2=0.605）, respectively. The MSY estimated by the Fox model was conservatively compared to the Schaefer and Pella Tomlinson models. The MSY values from Schaefer and Pella Tomlinson models were the same. The computed values of MSY using the ASPIC computer software program with the two surplus production models of Fox and logistic were 1 498 t （R^2=0.917）, and 2 488 t （R^2=0.897） respectively. The estimated values of MSY using CEDA were about 1 700-2 400 t and the values from ASPIC were 1 500-2 500 t. The estimates output by the CEDA and the ASPIC packages indicate that the stock is overfished, and needs some effective management to reduce the fishing effort of the species in Pakistani waters.展开更多
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(...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.展开更多
基金Supported by the Special Research Fund of Ocean University of China(No.201022001)
文摘Catch and effort data were analyzed to estimate the maximum sustainable yield （MSY） of King Soldier Bream, Argyrops spinifer （Forsskal, 1775, Family： Sparidae）, and to evaluate the present status of the fish stocks exploited in Pakistani waters. The catch and effort data for the 25-years period 1985-2009 were analyzed using two computer software packages, CEDA （catch and effort data analysis） and ASPIC （a surplus production model incorporating covariates）. The maximum catch of 3 458 t was observed in 1988 and the minimum catch of 1 324 t in 2005, while the average annual catch ofA. spinifer over the 25 years was 2 500 t. The surplus production models of Fox, Schaefer, and Pella Tomlinson under three error assumptions of normal, log-normal and gamma are in the CEDA package and the two surplus models of Fox and logistic are in the ASPIC package. In CEDA, the MSY was estimated by applying the initial proportion （IP） of 0.8, because the starting catch was approximately 80% of the maximum catch. Except for gamma, because gamma showed maximization failures, the estimated results of MSY using CEDA with the Fox surplus production model and two error assumptions, were 1 692.08 t （R^2=0.572） and 1 694.09 t （R^2=0.606）, respectively, and from the Schaefer and the Pella Tomlinson models with two error assumptions were 2 390.95 t （R^2=0.563）, and 2 380.06 t （R^2=0.605）, respectively. The MSY estimated by the Fox model was conservatively compared to the Schaefer and Pella Tomlinson models. The MSY values from Schaefer and Pella Tomlinson models were the same. The computed values of MSY using the ASPIC computer software program with the two surplus production models of Fox and logistic were 1 498 t （R^2=0.917）, and 2 488 t （R^2=0.897） respectively. The estimated values of MSY using CEDA were about 1 700-2 400 t and the values from ASPIC were 1 500-2 500 t. The estimates output by the CEDA and the ASPIC packages indicate that the stock is overfished, and needs some effective management to reduce the fishing effort of the species in Pakistani waters.
基金This work is supported by the special research fund of Ocean University of China(201022001).
文摘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.
