Stock Assessment and Rebuilding of Two Major Shrimp Fisheries (Penaeus monodon and Metapenaeus monoceros) from the Industrial Fishing Zone of Bangladesh

Abstract

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.

Assessment of Three Major Shrimp Stocks in Bangladesh Marine Waters Using Both Length-Based and Catch-Based Approaches

“…Tiger shrimp is a desired item in the export market [8], but the stock is now heavily overfished. These results are generally consistent with some previous studies on major industrial shrimp stocks [1,7,8,10], which found that the biomass of tiger shrimp population is suffering from depletion, as are other main commercial fish species, which corresponded to the lowered CPUE trend in finfish in the historical catch along Bangladesh marine waters [59].…”

“…Table 5 showed that the present and previous study's results vary in all parameters. Particularly for tiger shrimp, a significant variation is observed in K and r. The estimated K values by Barua et al (2020) [8] and Alam et al (2022) [7] were much lower than the present study. However, the 95% confidence intervals of their estimates of K overlapped with the range of this study's estimates.…”

“…Despite the high demand and economic potential, the shrimp fishery has not been valued as such, particularly in management and research. Though there are a few studies available in national and international journals for tiger and brown shrimps [1,7,8,10,16,17], no study has been found yet that solely focuses on the assessment of white shrimp. Therefore, this would be the first study on assessing white shrimp stock also.…”

“…Although 37 species of shrimp have been documented from the maritime waters of Bangladesh [5,6], the tiger shrimp (Penaeus monodon), brown shrimp (Metapenaeus monoceros), and white shrimp (Fenneropenaeus indicus) are the most economically important shrimp species [1,3,6]. The tiger shrimp is superior to other species when considering economic value [7,8]. The extensive collection of post-larvae (PL) and brood stock (mature shrimp) from the wild has made the tiger shrimp fishery in Bangladesh vulnerable [8].…”

Application of Length-Based Assessment Methods to Elucidate Biological Reference Points of Black Pomfret Stock in the Bay of Bengal, Bangladesh

“…These previous studies were carried out using length-frequency data only by applying FAO-ICLARM stock assessment tools (FiSAT) to elucidate stock exploitation status but the spawning stock biomass, population percentage related to exploitation, and selectivity pattern were not considered. Moreover, in Bangladesh, commercial marine fisheries are mainly operated by earmarking fishing areas, limiting fishing days, mesh size regulation of gears, closure of spawning grounds, and fishing bans during spawning seasons [14,[20][21][22]. However, the implementation of fishing ban activities only during the propagation period is not as effective [23] as associated with implementing a catch quota for sustainable management of fisheries.…”