KEOKUK, Iowa — Since the 1970s, the Mississippi River basin has seen the spread of several invasive fish species, collectively referred to as Asian carp.
These fish have worked their way throughout the Mississippi, Ohio, Missouri and Illinois rivers, as well as countless other tributaries and connected lakes. Asian carp — including silver carp, bighead carp, black carp, and grass carp — are harmful to waterways because they grow quickly and they aggressively compete with native species for food and habitat.
At Lock and Dam 19, spanning the Mississippi River between Keokuk and Hamilton, Ill.,, a scientific research mission has launched to try and prevent the spread of these invasive creatures any further north.
Leading the effort are the U.S. Geological Survey and the U.S. Army Engineer Research and Development Center (ERDC). The goal is to test a new system, an underwater Acoustic Deterrent System, or uADS.
Marybeth Brey is the lead USGS research fish biologist working on the project. She said the idea is to drive away the invasive fish species without disrupting the behavior of native fish.
"The goal is to find sound signals (combinations of frequencies and decibel levels) in the hearing range of Asian carp, but less so in the hearing range of native fish," Brey said. "Native species will hear parts of the signals, but their behavioral response to what they hear is different than Asian carp. Asian carp are more sensitive to higher frequencies than many native species, so we are using that to our advantage."
Brey also noted that they're looking for frequencies outside of those made by humans operating on the river, sounds like tug boats and lock operations. The research team has said that boaters in the area, once the equipment is fully operational later this summer, might hear the signal through the hulls of their boats, but it will not be hazardous to people and won't interfere with high-frequency sonar or communications equipment.
Installation of the uADS equipment started just after the first of the year and is projected to be completed around the middle of March. Once construction of the system is completed, the research project is expected to run for about three years. Early results are targeted to be compiled in late 2021 or early 2022.
"We have worked with research scientists at the University of Minnesota-Duluth to measure Auditory Evoked Potentials and Particle Acceleration Thresholds (fish hearing tests) on both native fish and invasive species to determine their hearing range," USGS's Brey said. "Some fish hear the sound but do not respond to it, while other fish will hear it and respond. Still others will not be able to hear some sounds. The goal is to couple these hearing tests with behavioral tests to determine what fish hear and what they move away from."
Along with the USGS and the U.S. Army Corps of Engineers, the study is being done in collaboration with the US Fish and Wildlife Service, the Departments of Natural Resources for Illinois, Iowa, and Wisconsin, and the Missouri Department of Conservation. The U.S. Army Corps of Engineers have both the Rock Island District and the Chicago District involved, along with the ERDC.
Lock and Dam 19 was selected for the project because of several factors. The physical height of the dam prevents fish from passing over it, so they would have to move through the lock. The lock is also noted to have structural attributes that provide challenges to overcome, allowing for repeatable sequences that can be tested and measured.
The long-term goal of the project is to prevent the further spread of the Asian carp into other areas, including the Great Lakes through connections to Lake Michigan, where their spread would likely be disastrous for native species.
For anyone interested in learning more about this project and Asian carp research, visit usgs.gov/centers/umesc.