River Ecosystem Degradation and Its Impacts on Fish Biodiversity and Capture Fisheries in Major River Basins of Bangladesh: A Policy‐Focused Study

ABSTRACT This study investigates the widespread degradation of river ecosystems in Bangladesh and its impact on fish biodiversity and identifies potential strategies for ecosystem restoration. Combining community perceptions from focus group discussions (FGDs) with fish market study for spatial analyses of fish species diversity across the Barak–Meghna, Brahmaputra–Jamuna and Ganges–Padma basins, the research identifies pollution, destructive fishing practices, habitat destruction and mismanagement of water bodies as major threats. Results from 36 FGDs indicated that pollution from poultry farms, industrial waste from factories and pesticide runoff from agriculture were major contributors to the degradation of the Barak–Meghna basin, collectively affecting fish biodiversity. Fish market study identified a total of 57 fish species across the basins, far fewer than the over 260 species known to inhabit the freshwaters of Bangladesh. The Shannon–Wiener Diversity Index revealed low indices in Dhaka (0.00) and Rajshahi (1.73), signifying ecological degradation and anthropogenic stress, respectively, while Chandpur (2.52) and Pabna districts (2.30) exhibited comparatively higher diversity, pointing to potential conservation hotspots. The study highlights the perceptions of declining fish biodiversity with the percentages of FGDs reporting a decline of 83.3%, 90.9% and 91.7% in Barak–Meghna, Brahmaputra–Jamuna and Ganges–Padma basins, respectively. The study recommends an integrated approach combining physical interventions like collaborative dredging of rivers with pollution control measures, strengthened fisheries governance, community‐based co‐management, equitable water body leasing policies and transboundary coordination to ensure sustainable river restoration and biodiversity conservation.