Implications of historic development and economic performance of molluscan fisheries in China 1950-2017

1667-1679This is the first attempt that discusses molluscan fisheries of China in terms of economic perspective. The originality of this research stems into the analysis of a long series of data, 1950-2017, 68 years covering pre and post-reform era, starting from the time when China had limited infrastructure to becoming world’s largest producer of aquatic products. Since its liberation, the Chinese economy has gone through various disruptions and transformations, which include famine, Cultural Revolution and accession to world trade organization during the late 1950s, the late 1960s and in 2011 correspondingly. Coupled with various macroeconomic perturbations, Chinese fisheries sector has also gone through various transformations of its own such as the shift from inshore to offshore fishing with the passage of time. Consequently, molluscan fisheries sector has experienced remarkable changes. Molluscan fisheries landings have considerably increased from 1950 (90500 t) to 2017 (1797475 t). However, the decline in the capture production has been observed after 2000 due to overexploitation. Trade (export + import) of molluscs (volume + value) is on the move since 1984 as a result of market liberalization and development policies. The tendency for molluscs consumption is also increasing with the passage of time

Maximum sustainable yield appraisal for Indian Oil Sardine <em>Sardinella longiceps </em> in Pakistani marine waters: An update

522-528The highest and the lowest catch quantity of S. longiceps was observed in 1993, 92704 Mg, and 2010, 20127 Mg respectively, whereas average catch quantity of this fishery resource remained 44265 Mg year-1 during the study period (1990-2010). To estimate MSY we applied IP (B1/K) of 0.7 because the initial catch was about 70% of the maximum catch. For Fox model computed values of MSY, CV and R2 by using log and log-normal assumption were 21734 Mg, 0.2180, 0.841 and 27477 Mg, 0.1033 and 0.815 in that order. Calculated figures of same parameters for Schaefer model were 27609 Mg, 0.1925, 0.838 and 32665 Mg, 0.1217, 0.815 respectively, while for Pella-Tomlinson model their values were 27609 Mg, 0.2062, 0.838 and 32665 Mg, 0.1173, 0.815 correspondingly. Gamma error assumption did not produce rational results in all the three models used. Fox model appeared to be more conservative as compared to other models in terms of MSY calculation and produced higher R2 values. Obtained results suggest that fishery stock of this aquatic resource is in safe condition and therefore harvest should be kept at the current level

Bioeconomic analysis and management aspects of metapenaeus shrimp fisheries in Pakistan

1413-1419Fishery input (FI) and fishery output (FO) data, 1984-2009, related to Metapenaeus shrimp fisheries sector in Pakistan is analyzed in order to access its bioeconomic and management aspects. The maximum, minimum and average catch of this fishery resource remained 14824 t (1984), 5004 t (2006) and 7925 t y-1, correspondingly. Data was analyzed by using two specialized fishery software i.e. CEDA and ASPIC. Three surplus production models (SPMs) viz. Fox (FM), Schaefer (SM) and Pella-Tomlinson (PTM) were used in CEDA. Furthermore, error assumptions (EAs) viz. normal (NEA), log normal (LNEA) and gamma (GEA), for each SPM were also applied in CEDA. Two SPMs, FM and LM, were used in ASPIC. In CEDA by using an initial proportion (IP) of 1, FM estimated MSY, CV and R2 as 6474 t (tons), 0.048 and 0.670 for NEA. While, the computed values of these parameters for LNEA remained as 6108 t, 0.061 and 0.574, correspondingly. For this model, GEA produced minimization failure (MF). Estimated MSY for all EAs by SM and PTM were remained same viz. 7731 t, 6959 t and 7102 t, correspondingly. FM results showed the highest value of R2 (0.670). In ASPIC, FM estimated MSY, FMSY, CV and R2 as 6200 t, 0.219 y-1, 0.054 and 0.896, respectively, whereas, LM computed same parameters as 6769 t, 0.207 y-1, 0.100 and 0.846, correspondingly. The obtained results suggest that this fishery resource is overexploited. Thus, harvest levels of this fishery resource must be lowered for their sustainable maximum economic contribution and conservation as well

Assessment of maximum sustainable yield of <i>Acanthopagrus berda</i> from Pakistani marine waters by applying surplus production models

1410-1416Picnic Sea bream (Acanthopagrus berda) fishery in the Northern Arabian Sea from Pakistani marine waters was analyzed using catch and effort data (1991-2008). Maximum, minimum and average catch was recorded as 1088 mt in 1999, 586 mt in 1991 and 828 mt year-1 respectively. MSY (Maximum sustainable yield) and other key fish population parameters of K (carrying capacity), q (catchability coefficient), r (intrinsic population growth rate) and CV (coefficient variation) values of the calculated MSY were estimated by CEDA (catch and effort data analysis) and ASPIC (a surplus production model incorporating covariates) computer software packages. The fishing mortality at maximum sustainable yield FMSY = 0.114 from logistic model and FMSY= 0.057 from Fox model was estimated by ASPIC. The stock biomass given MSY BMSY = 11990 (CV= 0.083) from Fox model and MSY BMSY = 13630 (CV= 0.037) was estimated in ASPIC. In CEDA the initial proportion (IP) of 0.5 was used, because starting catch was approximately 50% of the maximum catch. The estimated results of MSY using CEDA with three surplus production models Fox, Schaefer and Pella Tomlinson under three error assumptions of Normal, Log-Normal and Gamma were about 620-800 mt, which was lower than the catch of 897 mt in 2008, indicating that the A. berda fishery in the marine waters of Pakistan has been overexploited, therefore it is suggested that measures should be taken to reduce fishing effort for the rational exploitation of the fishery

Aquaculture in Pakistan: Status, Opportunities and Challenges

1872-1878This study finds that aquaculture sector in Pakistan is making progress at a greater pace but still the rate is low. Despite of having enormous aquatic resources fisheries production is stumpy. Unfortunately, mariculture is almost absent in Pakistan. However, aquaculture sector contributes significantly in the agriculture GDP. In order to further boost the contribution of this sector in national economy concrete steps are direly needed

Maximum sustainable yield estimation of shellfish fishery in Chinese marine waters by using surplus production modelling approach

1774-1781In this study, maximum sustainable yield (MSY) of shellfish fishery from Chinese marine waters is estimated through two stock assessment softwares i.e. ASPIC (a surplus production model incorporating covariates) and CEDA (catch and effort data analysis). The initial catch was approximately 90%; hence, the MSY was estimated with initial proportion (IP) of 0.9 in both softwares. In ASPIC for this IP value, estimated MSY and goodness of fit (R2) parameters for FM were observed as 336100 t and 0.857 while for LM their estimated values remained as 316600 t and 0.856, correspondingly. In CEDA for IP value 0.9, SM and PTM estimated same MSY 213957 t, 322791 t and 266213 t for all the three error assumptions. FM for log and log normal error assumptions estimated MSY as 249382 t and 338355 t and R2 = 0.756 and 0.786, respectively. However, gamma error assumption produced minimization failure (MF)

Stock Assessment of Molluscan Fisheries in Pakistani Marine Waters by using CEDA and ASPIC computer packages

692-697Molluscan fishery input and output data, 1999-2009, from Pakistani marine waters was analyzed by using two specialized software, CEDA and ASPIC, used in fisheries management. The highest and the lowest molluscan catch values were observed in 1999 (10208 t) and 2006 (6162 t) respectively, with an average catch of 8109 t y-1. Among five surplus production models (SPMs) used in this study, three were from CEDA i.e. Fox, Schaefer and Pella-Tomlinson along with log error assumption and two were from ASPIC i.e. Fox and Logistic. Calculated MSY and R2 values for CEDA models, by using IP (B1/K) of 1, were 8449 t, 7248 t, 7248 t and 0.52, 0.50, 0.50 respectively. While for ASPIC, their values remained 8527 t, 7343 t and 0.711, 0.698 in that order. Computed MSY values, along with higher values of R2, validate ASPIC results as compared to CEDA and suggest that overall this fishery resource is in safe condition and in future catch should be managed at current level. However, molluscan fisheries sub-groups should be further investigated for their stock status

Assessment of some demographic trends of Spadenose shark (<em>Scoliodon laticaudus</em>) of the Bay of Bengal, Bangladesh

1986-1995Present study featuring the assessment of demographical trends of Scoliodon laticaudus that were analyzed on the basis of monthly length frequency data from the Bay of Bengal, Bangladesh from July 2014 to June 2015. Total length (TL) range of the collected 1520 specimens were 26 to 70 cm and weight (W) 329 to 2758 g. The relationship of length and weight was W = 0.3409L2.1137, R2 = 0.9987). The von Bertalanffy growth model parameters were L∞ = 73.75 cm and K = 0.30 yr-1, hypothetical age at zero length of t0 = - 0.3922 years and goodness of the fit of Rn = 0.112. The natural mortality rate at average annual water surface temperature of 220C was 0.5651 yr-1. The total mortality was 1.31 yr-1 while fishing mortality was 0.745 yr-1 and the current exploitation ratio 0.57. The Beverton-Holt yield per recruit model was done by FiSAT-II in which when tc was 1 the Fmax was estimated at 0.95 yr-1 and F0.1 was 0.8 yr-1. Current age at the first capture was approximately 1 year, Fcurrent = 0.745 yr-1 which is smaller than F0.1 indicating the current stock of S. laticaudus of Bangladesh is in safer state but more work is needed for the sustainable management of this fishery resource

Molluscan fisheries in Pakistan: Trends in capture production, utilization and trade

929-935Overall, molluscan capture production has increased manifolds; however after 2000 there is decreasing trend in its production. There is no recorded data for its consumption in Pakistan. Trade values show that this commodity is mainly exported and there is negligible sporadic import in few years. Export and percentage contribution of molluscan fisheries in total seafood production is decreasing with the passage of time

Estimation of the marine Pomfret fishery status of the Bay of Bengal, Bangladesh: Sustainability retained

686-693The status of Pomfret fishery of the Bay of Bengal, Bangladesh was analyzed by using non-equilibrium surplus production models with a view to evaluate MSY based on (2003-2015) 13 years catch and effort data. Three surplus production models of Fox, Schaefer and Pella-Tomlinson including three error assumptions of normal, log-normal and gamma were used by applying CEDA software package. Initial proportion (IP) value of 0.2 was used because the starting catch was only about 20% of the maximum catch. The MSY output of Fox models were 22,177MT and 21,177MT under the error assumptions of normal and log-normal, while Schaefer and Pella-Tomlinson models produced similar MSY of 33,511MT and 33,138MT. The outcomes from the log-normal error assumption of Fox model was produced goodness of fit R2 (0.678) value which was smallest among all models whereas highest biomass, Bfinal (137640) was found from the same model. The estimated MSY from Schaefer and Pella-Tomlinson models were not as suitable to accept as because the value of coefficients of variation (CV) were too small. The Fox model estimates (normal and log-normal assumption) are close to the recent landings (11,067MT) of Pomfrets which are more conservative and hence the best fit. This study points out that Pomfrets stock of Bangladesh remains in a satisfactory level