Kathmandu, April 12 Asian Development Bank has suggested that special measures are needed in Nepal’s hydel and irrigation projects to control rapid decline in the fish stocks in the rivers, thanks to river-related development projects. A research conducted by ADB on the impact of dam construction on aquatic biodiversity has concluded that there is a sharp decline in the fish population in Nepal’s river basins because of dams. Deepak Bahadur Singh, the co-author of a study on ‘’The Impact of Dams on Fish in the Rivers of Nepal,’’ suggested that technical considerations while building dams would be helpful in saving the fish. “Providing a fish ladder, building a fish passage and a fish bypass channel,  catch and haul system, fish lock and fish lift are some ways of saving the fish and other aquatic faunas,” he said. The study also suggests that breeding fish in hatcheries and annually releasing them upstream and downstream of the dam to maintain their population can be an effective measure to maintain river fish stocks. The study was conducted in 13 dam projects, including  Kali Gandaki, Marshyangdi, Middle Marshyangdi, Kulekhani, Khimti, and Trishuli hydropower projects, and the Babai irrigation project. The study adds that the rate of damming rivers is expected to increase rapidly in the future for more hydro-power projects and irrigation systems. The rivers flowing through the varied ecological realms of the country host many indigenous, rare and endangered fish species and other aquatic organisms, creating unique river ecosystems. The study has also suggested that a few tributaries in each major river basin could be declared as aquatic life protection areas or fisheries national park. Speaking at the programme, ADB’s country director for Nepal Mukhtor Khamudkhanov said, “We hope this study will open the door for more discussion and extensive research on the topic.” The study had recorded 223 dams at different phases of development at different locations in the rivers of Nepal. There are more than 6,000 rivers in the country. The four major river basins of Nepal host about 230 species of freshwater fish and scores of unique aquatic flora and fauna.