Reviewing the impacts of dam on migration of aquatic species and migration restoration solutions

Abstract

    For some aquatic species, migration between different habitats in their lifecycle is a necessity for finding food, shelter, breeding or evading predators. However, under the pressure of socioeconomic development, many hydropower dams have been built in many river basins around the world and in Vietnam. This has a great impact on migratory fishes such as obstruction of migration routes, damage due to hydraulic turbines and spillways, loss of habitat, modification of dischage, water temperature and water quality changes, increased exposure to predation. To mitigate these impacts, a number of scientific and technological solutions have been proposed: (1) for upstream migration: upstream passage can be provided through several types of fish pass: pool and weir fishpasses, vertical-slot fish passages, Denil type fish pass (or baffle-type fish passes), nature-like bypass channels, fish lifts, fish locks and culverts; (2) for downstream migration: physical and behavioural barriers. For Vietnam, which has a great network of rivers and more than 10,000 large and small reservoirs built from the North to the South, yet so far only one fishpass has been built at Phuoc Hoa dam (Binh Duong province). This will need a breakthrough in research as well as the construction of fishways through reservoirs in Vietnam in the next time.