In order to maintain the Energy Department’s commitment to environmental stewardship, the Pacific Northwest National Laboratory (PNNL), has been working diligently on a diverse set of tools to better understand and mitigate the impacts of hydropower development on its surrounding environment. Over the past 15 years, PNNL has developed and improved a small device called the Sensor Fish that measures the physical forces fish experience as they pass through hydroelectric facilities such as dam turbines and spillways. The Sensor Fish provides researchers with quick, reliable feedback on changes in pressure, acceleration, strain, turbulence, and other forces as the neutrally-buoyant device moves through hydro facilities—providing a close picture of what the fish would experience.
The Sensor Fish collects information that can be used to evaluate conditions encountered by juvenile salmonids and other fish as they pass through hydroelectric dams on their way to the ocean. Sensor Fish are deployed in turbines, spillways, and sluiceways and measure changes in pressure, angular rate of change, and linear acceleration during passage. Approximately smolt-sized, the Sensor Fish is a polycarbonate cylinder containing triaxial accelerometers, a pressure gauge, and rate gyros that measure angular rotation. It is reusable and contains modules that charge its internal battery, program the sensor settings, acquire data, and convert analog signal to digital form. The acquired data, collected at a 2,000 Hz sampling frequency over a recording time of up to approximately 4 minutes, are stored on an internal memory card and transferred to computers via a wireless infrared link using an external infrared link modem.
The Sensor Fish, funded in part by the Energy Department’s Water Power Program, represents a big breakthrough for biologists and engineers, who previously relied largely on live fish tests or computer models to study spillway and turbine passage environments. Researchers can now use the Sensor Fish in combination with other available methods to collect better data and help improve the design of more fish-friendly turbines and hydropower projects, improving the survival rate of fish populations and lessening the chance of individual fish injuries.