Establishment of a fish sanctuary for conserving indigenous fishes in the largest freshwater swamp forest of Bangladesh: A community-based management approach.

Fish sanctuary is considered as an important structural management tool for restoring fish biodiversity and enhancing fisheries production. Therefore, this study was conducted in the Ratargul Swamp Forest (RSF) of Bangladesh to evaluate the impact of a fish sanctuary on native fish biodiversity in and around the forest ecosystem. The investigation was carried out through focus group discussions, personal interviews, and direct catch assessments during fishing operations by the local fishers. After two years of study, 65 species of indigenous fishes were recorded for 46 genera under 23 families covering 9 orders, where Cypriniformes and Cypriniidae are the dominant order and family, respectively. After the establishment of the fish sanctuary, there was an increasing tendency of fish population was observed in the RSF and the adjacent Shari-Goyain and Kapna Rivers. In the RSF, fish diversity indices such as Simpson dominance index (D), Shannon-Wiener diversity index (H), Margalef richness index (d), and Pielou evenness index (J) varied from 0.12-0.09, 2.77-2.98, 6.15-6.14, and 0.66-0.71, respectively indicating species diversity enrichment in the final year compared to baseline assessment year which is supposed to be associated with the impact of fish sanctuary establishment. That assumption is further supported by remarkable increase in average fish catch (11.38%). Local fishers and people adjacent to RSF perceive that sanctuary became useful for protecting biodiversity, increasing fish production as well as improving their livelihood conditions.