Fish biodiversity and their conservation measures in the Mathabhanga river, Chuadanga, Bangladesh

The study was concerned to determine the present status of the fish biodiversity in the Mathabhanga river, Chuadanga and its conversation measures based on the questionnaire interview with 40 fishers, focus group discussion with river bank community members and cross check interview with key informants. A field study was conducted for a period of four months from December, 2021 to March, 2022 to assess the fish biodiversity in the Mathabhanga river, investigate the existing fishing practices and also to identify proper management strategies for the conservation of fish biodiversity in the river. The results revealed that three categories of fishers were engaged in the Mathabhanga river namely, professional fishers (45.0%), seasonal fishers (37.5%) and subsistence fishers (17.5%). Shannon-Weaver diversity (H) and Margalef’s richness (D) values revealed that diversity and richness of fish species were the highest in March (H = 2.99, D = 4.45), followed by February (H = 2.96, D = 3.69) and January (H = 2.63, D = 3.15), while the lowest values were obtained in December (H = 2.60, D = 2.80). The Pielou’s evenness (e) values were found to be slightly varied with the variations of total number of species, being the highest in December (e = 0.94) and the lowest in January (e = 0.91). Different types of fishing gears like seine net, gill net, cast net, hook and line, and traps were found to be operated to catch fish by the fishers during this survey. A total of 26 fish species were identified in the catches of the Mathabhanga river. According to the survey, indiscriminate and overexploitation were found to be responsible for almost 40% loss, and pollution and siltation caused about 25% loss of ecosystem. Around 20% and 15% loss of ecosystem were caused by habitat destruction and changes of river course, respectively. As a result, the water quality was deteriorating day by day, and the availability of fish species and other aquatic biodiversity were decreasing gradually. During the survey, almost 16 fish species was found at a risk to be endangered. The specific conservation measures including community based fisheries management, establishment of sanctuary, control of pollution, maintenance of fishing gears and the implementation of fisheries act should need to be made for the sustainable utilization and conversation of fish biodiversity in the Mathabhanga river.