The studied area is the single largest fishery in Bangladesh. The present work was conducted at two points of the Padma River (Sureshwar and Tarabunia) from July 2019 to June 2021 to monitor the efficiency of the 5^th Hilsa sanctuary. Proportion of spent rate, length frequency, larvae and Jatka abundance, CPUE of larvae, the length-weight relationship of Jatka, plankton composition, and physico-chemical parameters of water were assessed and found adequate in the Hilsa sanctuary.

The current study was performed to monitor in situ condition and spatio-temporal modelling of the present status of water quality parameters of different spawning grounds and sanctuaries of Hilsha. The study was conducted in nine sites in lower Padma River (Maowa) to lower Meghna River (Bhola, Patuakhali) from 1 August 2015 to 31 January 2016. This study demonstrates surface water temperature, salinity, conductivity and transparency were ranged from 19.00-33.00°C, 0.10-2.90 ppt, 125.60-4720.00 µS/cm and 6.60-74.00 cm respectively. The values of pH, DO, free CO₂, total alkalinity, total hardness and free NH₃ were varied from 6.00-9.50, 4.50-11.60 mg/L, 3.46-24.00 mg/L, 33.00-172.50 mg/L, 34.20-1291.00 mg/L and 0.20-1.40 mg/L respectively. Moreover, water quality model reveals that the present status of some water quality parameters (free CO₂, free NH₃, transparency) deviated from optimum condition suitable for the normal physiological process and spawning of Hilsha.

The Meghna River, vital for Bangladesh’s ecosystems and livelihoods, faces threats from urbanization, agriculture, industrialization, pollution, and climate change. This study examines the basin’s spatio-temporal dynamics, focusing on hydro-physico-chemical properties (temperature, pH, dissolved oxygen, salinity) and bio-resources (phytoplankton, zooplankton, and benthic macroinvertebrates). Field surveys, laboratory analyses, and satellite imagery revealed consistent patterns, highlighting the ecosystem’s vulnerability and the urgent need for conservation strategies to sustain ecological balance and livelihoods.