Posted on June 19, 2023
Researchers from the U.S. Army Engineer Research and Development Center (ERDC), along with scientists from the U.S. Geological Survey (USGS), the U.S. Army Corps of Engineers (USACE) and other partners, are currently working on a project to test the effectiveness of underwater sound technology on invasive carps — Bighead Carp, Silver Carp, Black Carp and Grass Carp — and the response of various native species of interest throughout the Mississippi River and Great Lakes basins, as well as additional native watersheds.
According to a recent article in Smithsonian Magazine titled Seven Wild Ways Scientists Are Trying to Stop Invasive Carp, “Invasive carp are swimming north through American waterways and wreaking havoc on ecosystems. The fish can withstand a variety of environments, survive for decades and lay millions of eggs, which allows them to supplant native species.”
Researchers from ERDC’s Environmental Laboratory are working on multiple solutions to combat this growing problem.
One such solution is the use of underwater sound as a deterrent.
“It may come as a surprise to some, but fish can actually hear sound,” said Dr. Christa Woodley, ERDC-EL underwater bioacoustics team lead. “By using their sensory capabilities, we can use sound as a deterrent or attraction to prevent invasive carps from moving past a certain point in a channel.”
The underwater acoustic deterrent system (uADS) consists of an array of 16 projectors, also known as the Soundbar. These projectors are installed on the bottom of the approach to the lock, just downstream of the lower miter gates. The Soundbar plays an acoustic stimulus of varying frequencies and decibels on an on/off cycle every 80 hours. The frequency and decibel combinations are based on ERDC’s Cognitive Ecology and Ecohydraulics Research Flume (CEERF) testing to affect invasive carp.
In mid-April, ERDC personnel led the research team on a project to service the prototype uADS at Lock No. 19 in Keokuk, Iowa. The ERDC team also supported fish tagging efforts led by the USGS which allow for tracking of the fish through and around the lock structure.
The 18,000-pound uADS was lifted to the lower lock top and underwent its second maintenance event. The uADS was equipped with new sound projectors and spliced cabling. Additionally, corrosion and biological material was removed from the unit.
“Based on lessons learned from a previous maintenance event, we modified the design of the projectors,” Woodley said. “The new projector models included a modified cone design and an external ‘wet’ connection, reducing the probability of needing to lift the uADS in future years. The modifications will allow the projectors to be replaced in the water.”
This experimental installation also includes two extensive arrays of hydrophones to monitor the level of acoustic stimuli — frequency range and loudness at specific locations — and acoustic telemetry systems designed to track the movements of invasive carp and native fishes tagged with acoustic transmitters. This allows scientists to determine when and where tagged carp and native fishes move through the approach channel of Lock No. 19.
The uADS is in its third year of operation, with a proposed two additional years of work.