How Does Hydroelectric Power Impact The Mobility Of Fish?

Hydroelectric power is a renewable energy source that is produced from the movement of water. It involves the construction of structures like dams, which convert the potential energy of water into electricity. While hydroelectric power is a clean and sustainable source of energy, it has a significant impact on the natural ecosystems surrounding the power plants. One of the major concerns with hydroelectric power is the potential impact on fish mobility.

The Impact of Dams on Fish Mobility

The construction of dams for hydroelectric power generation creates significant obstacles for fish migration. Fish require the movement of water in order to migrate to their spawning grounds and to find food. Dams create barriers that interrupt the natural flow of water and therefore impede fish migration. The impact of dams on fish mobility can be seen across all fish populations that live in or migrate through the rivers that are dammed. This includes salmon, trout, sturgeon, eel and many others.

Depending on the height of the dam, the impact on fish mobility can vary significantly. Low dams and weirs may only present a minor obstacle to some fish, but even these small structures have an impact. For instance, fish have to expend more energy to navigate around these structures, which can cause exhaustion and weaken the fish making them easier prey for predators. In contrast, taller dams can completely block the migration of fish and have drastic effects on fish populations.

Moving Fish Around Dams

One strategy to mitigate the impact of dams on fish is to provide fish passages. Fish passages are designed to provide fish with a way to bypass the dam. There are many types of fish passages, such as fish ladders and fish lifts, which allow fish to navigate around dams and continue their migratory routes. Fish passages can be effective, but they are not perfect. Fish need to find and learn how to use the passages, which can take time and many fish are simply not able to navigate them. Additionally, some fish may be deterred by the noise and vibration of the turbines.

A newer strategy to help fish get past dams is the use of fish cannons. Fish cannons use air pressure to launch fish up and over dams. Fish are sucked into a tube where they are then launched over the structure and into the river on the other side. While this technology is still being developed, it is showing great promise in providing a safer and more effective way for fish to pass dams.

Impact on Fish Populations

The impact of hydroelectric dams on fish populations is complex and varies from one species to another. In many cases, the building of a dam can cause a decline in fish populations. This may be due to the disruption of the natural migration patterns or the loss of habitat that the dam causes. Additionally, dams may alter the water quality of the river. This can affect fish populations by reducing the quality of spawning habitat.

Despite these potential negative impacts on fish populations, dams can also benefit some fish. In particular, dams can create reservoirs that can provide new habitat for fish species. Moreover, impounding water slows down the movement of the water, creating eddies and other features that can provide habitat for fish. Dams can also regulate the flow of water, which can be beneficial in drought-prone areas by ensuring that enough water remains in the river to support fish populations.


Hydroelectric power has become an increasingly important source of energy worldwide, but it has a significant impact on the mobility of fish. Dams and other hydroelectric structures can create barriers that impede fish migration. However, many strategies exist to mitigate these impacts, including fish passages and other technologies like fish cannons. Ultimately, the impact on fish populations will vary depending on the particular circumstances surrounding each hydroelectric power plant. By understanding the potential impact of hydroelectric power on fish, we can work to minimize these impacts and continue to produce a sustainable source of energy for years to come.

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