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This research examined the biological reference points (BRPs) and stock status of the sardine fishery in the Bay of Bengal (BoB), Bangladesh, to determine the sustainability of this resource. The Monte Carlo method (CMSY), the Bayesian state-space Schaefer surplus production model (BSM), and the ASPIC (a Stock Production Model Incorporating Covariates) software suite, were used to analyze catch–effort data obtained from the Yearbook of Fisheries Statistics of Bangladesh. All models derived maximum sustainable yields (MSY) ranging from 37,900 to 41,280 t, which is quite near to the catch from the latest year (38,051 t in 2020), indicating the fully exploited status of sardines. The estimated B < BMSY and F > FMSY values from the BSM and Schaefer models indicate a poor biomass and an unsafe fishing status. For Schaefer and BSM, the calculated F/FMSY values were 1.07 and 1.06, and the B/BMSY values were 0.92 and 0.75, which also indicate the overexploited status of the sardine fishery in the BoB, Bangladesh. This information will aid in developing management strategies and conservation policies for the sustainability and rebuilding of this commercially important resource in the BoB on the Bangladesh coast. [ABSTRACT FROM AUTHOR]

The black pomfret (Parastromateus niger) is one of the high-income-generating carangid fish species and the only known member of its genus. This study aims to identify existing gaps in stock status and population demography of this species and provide viable management recommendations to enhance the sustainability of this fishery. Therefore, three methodological approaches have been used in this study; TropFishR to present the current exploitation status, the length-based spawning potential ratio (LB-SPR) to quantify stock spawning biomass, and Froese's sustainability indicators (LBI) to establish a basic standard for sustainable management of the fishery. In the length-weight relationship of black pomfret, an allometric growth pattern (b = 2.19) was found. The VBGF life history parameters for black pomfret were L∞ = 55.25 cm, K = 0.54 year−1, and based on LCCC analysis, the total mortality (Z = 1.61 year−1), natural mortality (M = 0.69 year−1) and fishing mortality (F = 0.91 year−1) are calculated. The result reveals that this fishery is currently suffering from overexploitation and the stock's spawning biomass (SPR = 13%) is below the limit reference point because most of the catch (82%) was found to be under the maturity level. Based on the results, this study recommended strictly maintaining the mesh size of the net to ensure not to catch immature fish with a length smaller than 30.63 cm, recommended the length to catch be between 29 and 35 cm, and reducing fishing pressure by one-third to ensure the sustainability of the black pomfret fishery. [ABSTRACT FROM AUTHOR]

Six most abundant and commercially valuable croakers (Sciaenidae) stocks in the coastal water of Bangladesh were evaluated using a length-based Bayesian Biomass (LBB) approach. The ratios B/B0 (current relative biomass) were smaller than the BMSY/B0 in five of the six stocks. For the six estimated populations, two (Otolithes ruber and Pterotolithus maculatus) are grossly overfished, one (Otolithoides pama) is overfished, two (Johnius belangerii and Panna heterolepis) are slightly overfished, and only donkey croaker (Pennahia anea) is in the healthy (B/B0 > BMSY/B0) status. Furthermore, the optimal length at first capture (Lc_opt) was higher than the length at first capture (Lc) in four populations, indicating growth overfishing, suggesting that increasing mesh size would benefit the catch and biomass. Findings from the present study confirm the declining trend of fisheries resources, particularly the croaker species in the BoB, Bangladesh coastal water. Management strategies (such as effort control, choosing the appropriate mesh size, total allowable catch limit, identify and enhance protection of the feeding, breeding, and nursery ground, etc.) should be taken for the sustainable management and recovery of the country's marine fishing resources, particularly the valuable croaker species. [ABSTRACT FROM AUTHOR]

As one of the largest and most commercially valuable finfish species, Leptomelanosomaindicum (Indian salmon) significantly contributes to Bangladesh's marine catches. The length-based Bayesian biomass (LBB) method and catch-based Monte Carlo method (CMSY) are among the most recent and powerful methods for predicting the state of fisheries resources from data-limited fisheries. CMSY requires catch and resilience data, as well as quantitative stock status information. For LBB, only length–frequency (LF) data are required. The stock status of L. indicum was estimated using these two independent methods, utilizing twenty-one years of catch–effort and length–frequency data (978 individuals) from commercial fisheries on the Bangladesh coast. Here, a BSM (Bayesian state-space implementation of the Schaefer surplus production model) was also employed. The current study's findings showed that the B/B0 ratio of currently exploited biomass to unexploited biomass (0.1) was smaller than BMSY/B0 (0.36) and B/BMSY = 0.28 was smaller than the reference value of 1.0, indicating the grossly overfished and depleted condition of the stock. Similar trends in the results were found for B/BMSY = 0.11 (<1.0) from CMSY. In addition, the exploitation rate (F/FMSY = 5.66), biomass (B < BMSY), and fishing status (F > FMSY) further justify the severely overfished conditions of L. indicum stock in the study area. Furthermore, the Lc_opt (optimal length at first capture) was higher than the Lc (length at first capture), indicating that this species is being overfished, and that mesh sizes should be increased for better management. This study provides information on biological reference points (BRPs), and confirms the severely overfished status of L. indicum in the coastal waters of Bangladesh. More specific and prompt management measures are required to recover and sustainably manage this valuable species, and protect the fish stock from commercial extinction. [ABSTRACT FROM AUTHOR]

The Bombay duck (Harpadon nehereus) forms the second-largest single-species marine fishery in Bangladesh and therefore has a significant impact on the local economy, providing employment, food, and nutrition to thousands of people. Despite the immense importance, this fishery has never been a priority for the relevant regulatory authorities. To enhance the sustainability of this fishery, an effective management policy based on the scientific evaluation of the current stock's status is urgently required. Therefore, this study used three methodological approaches (traditional size structure-based stock assessment to reveal current exploitation status; the length-based spawning potential ratio (LB-SPR) to evaluate the stock's spawning biomass; and Froese's sustainability indicators for sustainable fishing) to conduct a thorough assessment of the Bombay duck stock to establish basic standards for the sustainable management of this fishery. The results revealed that this fishery is presently suffering from overexploitation and the stock's spawning biomass (SPR = 8%) is below the limit reference point because of the juvenile-oriented fishing behavior of the fishery. Based on the outputs, this study recommended the mesh size regulation of the set bag nets (SBNs) (5 cm mesh size for the codend) to ensure not to catch immature fishes with a length equal to or smaller than 17.95 cm; and reduce the existing number of SBNs by half to reduce fishing pressure on the stock to ensure the sustainability of this fishery. [ABSTRACT FROM AUTHOR]

The two economically important shrimp species in Bangladesh are the tiger shrimp, Penaeus monodon, and the brown shrimp, Metapenaeus monoceros. However, a continuous decline in the landing of these species from the industrial trawling made it critical to assess their stock biomass status to explore their response to the present degree of removal. Given the minimum data requirement and robustness, this study employed the depletion-based stock reduction analysis (DB-SRA) to assess these fisheries rigorously. For the industrial fishing zone (beyond the 40 m depth in the EEZ of Bangladesh), the estimated historic mean carrying capacity (K) was 5015 metric tons for the Penaeus monodon and 35,871 metric tons for Metapenaeus monoceros. The estimated overfishing limits (OFL), which were much smaller than the reported catches throughout the time series, indicate the overfishing status of these fisheries. As a result, the estimated biomass for the reference year (B2020) for both species was lower than BMSY, indicating that these fisheries are not producing MSY. Therefore, for the rebuilding and sustainable management of these stocks, this study recommended a catch limit of 100 metric tons for P. monodon and 750 metric tons for M. monoceros for the next ten years from biomass projections. [ABSTRACT FROM AUTHOR]

This research evaluated fisheries reference points and stock status to assess the sustainability of the croaker fishery (Sciaenidae) from the Bay of Bengal (BoB), Bangladesh. Sixteen years (2001–2016) of catch-effort data were analyzed using two surplus production models (Schaefer and Fox), the Monte Carlo method (CMSY) and the Bayesian state-space Schaefer surplus production model (BSM) method. This research applies a Stock–Production Model Incorporating Covariates (ASPIC) software package to run the Schaefer and Fox model. The maximum sustainable yield (MSY) produced by all models ranged from 33,900 to 35,900 metric tons (mt), which is very close to last year's catch (33,768 mt in 2016). The estimated B > BMSY and F < FMSY indicated the safe biomass and fishing status. The calculated F/FMSY was 0.89, 0.87, and 0.81, and B/BMSY was 1.05, 1.07, and 1.14 for Fox, Schaefer, and BSM, respectively, indicating the fully exploited status of croaker stock in the BoB, Bangladesh. The representation of the Kobe phase plot suggested that the exploitation of croaker stock started from the yellow (unsustainable) quadrant in 2001 and gradually moved to the green (sustainable) quadrant in 2016 because of the reduction in fishing efforts and safe fishing pressure after 2012. Thus, this research suggests that the current fishing pressure needs to be maintained so that the yearly catch does not exceed the MSY limit of croaker. Additionally, specific management measures should implement to guarantee croaker and other fisheries from the BoB. [ABSTRACT FROM AUTHOR]

Stock assessment is necessary to understand the status of fishery stocks. However, for the data-poor fishery, it is very challenging to assess the stock status. The length-based Bayesian biomass (LBB) technique is one of the most powerful methods to assess the data-poor fisheries resources that need simple length frequency (LF) data. Addressing the present gap, this study aimed to assess the stock status of three sardines (Sardinella fimbriata, Dussumieria acuta, and D. elopsoides) in the Bay of Bengal (BoB), Bangladesh using the LBB method. The estimated relative biomass for S. fimbriata was B/B0 < BMSY/B0, indicating the overfished biomass, while the assessed B/B0 > BMSY/B0 for D. acuta and D. elopsoides indicates healthy biomass. Additionally, for S. fimbriata, the length at first landing was smaller than the optimum length at first landing (Lc < Lc_opt), indicating an overfishing status, but a safe fishing status was assessed for D. acuta and D. elopsoides (Lc > Lc_opt). Therefore, increasing the mesh size of fishing gears may help to ensure the long-term viability of sardine populations in the BoB, Bangladesh. [ABSTRACT FROM AUTHOR]