Estimating the growth parameters, exploitation rate, biomass and maximum sustainable yield of long whisker catfish Mystus gulio (Hamilton, 1822) in the coastal waters from southwestern Bangladesh.

The research provides a comprehensive analysis of Mystus gulio including growth pattern, growth parameters, recruitment patterns, mortality rates, biomass, exploitation rate ( E ), and the estimation of maximum sustainable yield ( MSY ) within the southwestern coastal waters of Bangladesh. From January to December 2017, fishers provided around 1200 specimens. FAO-ICLARM Stock Assessment Tool and Excel-add-in-solver were used to assess stock status through length-frequency data. Indeed, the research findings indicated that the population of M. gulio displayed negative allometric for both individuals ( b  = 2.53 for male, b  = 2.50 for female), as demonstrated by the calculated allometric coefficient value. Nonetheless, the population's dynamic characteristics revealed an asymptotic length ( L ∞ ) of 19.34 cm, 23.28 cm and growth coefficient ( K ) 0.94 year-1 and 0.81 year-1 for male and female M. gulio . The growth performance indexes (Ø') of 2.55 and 2.64 for male and female and maximum lifespan ( t max ) 3.20 years and 3.70 years respectively. This study revealed that the slightly variations in the natural mortality rate ( M ) for both specimens at 1.55 year-1 and 1.59 year-1 . The fishing mortality rate ( F ) 2.75 year-1 and 1.98 year-1 and total mortality rate ( Z ) 4.30 year-1 and 3.57 year-1 for male and females, respectively. The maximum permissible exploitation rate ( E max  = 0.421) was lower than the actual exploitation rate ( E  = 0.63). The MSY was calculated at 67.968 metric tons. Without a doubt, overfishing stands out as the most critical threat to the wild stock. Therefore, it is clear that the existing fishing approach was not efficiently managed the standing stock in a sustainable manner. The findings would be useful for established proper fishing regulations in coastal waters and the surrounding ecosystems.