Using Sensor Fish to Test Fish Ladders in Hydroelectric Dams

By on January 11, 2023
Cheoah Dam Cheoah Dam (Credit: Dantripphoto via Wikimedia Commons CC BY-SA 3.0))

Hydroelectric dams are commonly proposed as a means of generating green energy as the global population tries to shift to more sustainable forms of gathering and storing power. Unfortunately, while these dams can help produce massive amounts of energy, they can also negatively impact the local ecosystem. Dams lead to unnatural changes in water levels above and below the structure, as well as impede fish migration and travel throughout a waterway. Dams can be particularly harmful to migratory fish like salmon, who traverse up and down streams during their seasonal runs.

To mitigate the harm done to migratory fish and allow passage from one side of the hydroelectric dam to the other, many facilities have established some form of a fish ladder. There are many different types of fish ladders that can be used with varying reasons to use one over the other. Still, these structures may be unsuccessful at supporting fish travel due to poor construction or unsafe conditions.

Using Sensor Fish to Test Fish Passages in Hydroelectric Dams

Some dams have deployed the use of a synthetic fish which is used to study the forces a juvenile salmon feels as it passes through hydropower dams. The name for the device originated from scientists at the Pacific Northwest National Laboratory (PNNL), who aptly called it a Sensor Fish. The study that examined the efficiency of Sensor Fish occurred in 2014, and the device has continued to be developed. The tubular device is filled with sensors that analyze stresses that young salmon experience as they pass through hydroelectric dams and other hydro facilities. The PNNL Sensor Fish measures forces like pressure, acceleration, strain and turbulence, all while being capable of passing through hydro structures.

“The earlier Sensor Fish design helped us understand how intense pressure changes can harm fish as they pass through dam turbines,” wrote Daniel Deng, a chief scientist at the PNNL, in an article published by Though originally designed for use along Washington’s Columbia River, newer models of Sensor Fish are compatible with environments across the U.S.

A live juvenile fish (a) and the previous version of the Sensor Fish (b) are shown side-by-side as they’re exposed to a simulated dam turbine environment. (Courtesy of Pacific Northwest National Laboratory)

A live juvenile fish (a) and the previous version of the Sensor Fish (b) are shown side-by-side as they’re exposed to a simulated dam turbine environment. (Courtesy of Pacific Northwest National Laboratory)

Regardless of where the device is deployed, the means and applications stay the same. Researchers simply send Sensor Fish along the same paths that actual fish take as they go through dams. By doing so, the Sensor Fish measures the actual forces and obstacles fish face. Once the devices have passed through, and data are collected, turbine designers and dam operators use the information collected to make fish passages safer.

Sensor Fish can record five minutes of data in their flash memory, according to the FCW. They can take more than 2,000 measurements per second and withstand more than 200 times the force of gravity. The devices record temperatures from -40 to 260 degrees Fahrenheit.


Some of the tweaks they’ve made were to address issues relating to spinning turbine blades, though Gizmag reports that there are still many other harmful forces that need to be fixed–which include abrupt pressure changes in turbine chambers. Over time, Sensor Fish will become more capable of ensuring and recording harsher conditions and will also enable hydroelectric dams to plan for fish migration more effectively. Sustainable and renewable energy is essential to meet future energy needs, but these needs mustn’t come at the price of valuable biodiversity and the surrounding environment.

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