Status and Decline Causes of Fish and Prawn Diversity and Catch Efficiency of Fishing Gears in Gorai River, Bangladesh

Gorai River is one of the important rivers in Bangladesh for rich aquatic biodiversity. The river is originated from the Ganges-Padma River system, a trans-boundary river between India and Bangladesh. Once the river was rich in fish biodiversity, but due to man-made and natural causes the availability of fish reduced drastically. A comprehensive analysis of fish diversity indices, gear efficiency, catch composition and decline causes of fish diversity in Gorai River, Bangladesh was accompanied. The data were collected monthly basis from January to December 2018 from four major fishing sites of the river. A total of 62 fish and 2 prawn species under 12 orders and 24 families were recorded. Cypriniformes was the leading order consisting 27% of the total catch. The overall values of Shannon-Weaver diversity (H'), Margalef’s richness (d) and Pielou’s evenness (J') indices were recorded as 1.478, 15.115 and 0.481, respectively. The highest and lowest CPUE were recorded from seine net (5.2±1.72 kg gear-1 haul-1) and hook & long lines (0.0135±0.0015 kg gear-1 haul-1), respectively whereas, highest and lowest gear efficiency were recorded from lift net (0.321±0.036 kg gear-1 person-1 hour-1) and fish trap (0.0005±0.0002 kg gear-1 person-1 hour-1), respectively. Alternatively, the highest fish catch were recorded on April (21228±464.38 kg) and lowest on August (3855±138.21 kg). The fishermen identified a few noteworthy dangers to fish diversity, which should be addressed properly to enhance the fish biodiversity of Gorai River