Yongtong Mu

MSY Estimates of Cephalopod Fishery and Its Bioeconomic Implications in Pakistani Marine Waters

In this study maximum sustainable yield of cephalopod fishery resource, 1999-2009, was estimated by employing surplus production models through CEDA and ASPIC computer packages. Obtained results show that this fishery resource is overexploited. CEDA software computed MSY in a range between 4,600-4,900 t (tons). On the other hand, ASPIC range for MSY estimation remained between 4,800-5,200 t for this fishery resource. It is vivid that MSY range computed by both the computer packages overlap each other. CEDA showed conservation in MSY estimation as compared to ASPIC. Moreover, ASPIC results showed higher R 2 values. Considering the MSY estimates, it is recommended that target reference point of MSY for cephalopod fishery resource in Pakistani marine waters should be around 4,900-5,000 t. Harvest of this fishery resource beyond 5,200 t should be considered as limiting reference point. Thus, concrete steps are directly needed to conserve this fishery resource for future.

Fishery stock assessment of Kiddi shrimp ( Parapenaeopsis stylifera ) in the Northern Arabian Sea Coast of Pakistan by using surplus production models

Pakistani marine waters are under an open access regime. Due to poor management and policy implications, blind fishing is continued which may result in ecological as well as economic losses. Thus, it is of utmost importance to estimate fishery resources before harvesting. In this study, catch and effort data, 1996–2009, of Kiddi shrimp Parapenaeopsis stylifera fishery from Pakistani marine waters was analyzed by using specialized fishery software in order to know fishery stock status of this commercially important shrimp. Maximum, minimum and average capture production of P. stylifera was observed as 15 912 metric tons (mt) (1997), 9 438 mt (2009) and 11 667 mt/a. Two stock assessment tools viz. CEDA (catch and effort data analysis) and ASPIC (a stock production model incorporating covariates) were used to compute MSY (maximum sustainable yield) of this organism. In CEDA, three surplus production models, Fox, Schaefer and Pella-Tomlinson, along with three error assumptions, log, log normal and gamma, were used. For initial proportion (IP) 0.8, the Fox model computed MSY as 6 858 mt (CV=0.204, R2 =0.709) and 7 384 mt (CV=0.149, R2 =0.72) for log and log normal error assumption respectively. Here, gamma error produced minimization failure. Estimated MSY by using Schaefer and Pella-Tomlinson models remained the same for log, log normal and gamma error assumptions i.e. 7 083 mt, 8 209 mt and 7 242 mt correspondingly. The Schafer results showed highest goodness of fit R2 (0.712) values. ASPIC computed MSY, CV, R2, FMSY and BMSY parameters for the Fox model as 7 219 mt, 0.142, 0.872, 0.111 and 65 280, while for the Logistic model the computed values remained 7 720 mt, 0.148, 0.868, 0.107 and 72 110 correspondingly. Results obtained have shown that P. stylifera has been overexploited. Immediate steps are needed to conserve this fishery resource for the future and research on other species of commercial importance is urgently needed.