Blocking bighead, silver, and other invasive carp by optimizing lock and dams
Unknown numbers of invasive Silver and Bighead carp presently inhabit the Mississippi River below the Iowa border. This project worked to prevent their upstream spread by developing a scheme to modify lock and dam structures in Minnesota by enhancing their deterrent properties through key, linked steps, which included:
Activity 1: Installed a safe carp deterrent in front of the lock at Lock and Dam #8 located at the Iowa border while guiding efforts to enhance and optimize velocity fields to stop carp movement through its gates while having minimal effects on native fishes. The goal of this activity was to immediately and safely maximize water velocity through the gates of lock and dam #8 near the Iowa border while deploying a simple and safe acoustical deterrent system in its lock chamber as a stop-gap measure.
Activity 2: Quantified the swimming capabilities of both species of adult Bighead carps, thereby producing the data needed to optimize dam function. Swimming performance data for adult carps is essential to accurately forecast passage and optimize gate function so that velocities are not higher than needed.
Activity 3: Tested and developed new acoustical deterrent systems that best deter carp from entering lock chambers while having minimal effects on native fishes. Lock chambers present a potential way for Bigheaded carps to pass upstream, irrespective of gate function. Sound deterrents have special promise because carps are hearing specialists.
Activity 4: Developed numeric solutions to eventually optimize dam operation at all Minnesota lock and dams (#2 through #8) to prevent Bighead carp invasion statewide. The purpose of this activity was to identify potential weaknesses (scenarios by which carp might swim through the lock and dams) in Lock and Dam #2 in Hastings. This Lock and Dam was of special interest because it maintains higher velocities than other dams, is ideally situated far from the invasion front, and is located downstream of the Minnesota River.
Activity 5: In order to test and validate the models previously developed, researchers radio-tagged invasive common carp (as a surrogate to Asian carp) as well as 250 native fish specimens. They monitored the tendency and ability of these fish to challenge the increased flow from the dams as well as how they move through or around the dam. This work occurred at Lock and Dam #2.
Activity 6: Researchers used high-resolution imaging sonar to capture the location of all fish in the lock area when the acoustical deterrent system was turned on and off, which showed whether and how their behavior is affected by the sound. This work occurred at Lock and Dam #8.
Activity 7: In order to test upstream-migrating silver and bighead carp (instead of common carp), researchers designed and helped install an underwater speaker system on the lock gates at Lock and Dam #19 in Iowa.
Activity 8: Developed solutions to address weaknesses in Lock and Dam #4 and optimize its gate operation to prevent passage of invasive carp. This lock and dam system maintains a high velocity than other dams, is situated far from the invasion front, and is located just upstream of Lock & Dam #5, so the two systems can be used in conjunction. The project will include developing a 3D statistical model to calculate water velocities in and around the dam under a variety of conditions; measuring velocities near the dam to validate the model; developing and implementing a computation tool to search through the 3D velocity fields to identify specific swimming pathways that carp could take; and pairing this information with already-known swimming performance data to determine how best to block carp passage while having minimal effect on native fishes.
The overall objective of this work was to make explicit recommendations with (and to) the U.S. Army Corps of Engineers (USACE) for optimization of all Minnesota lock and dams (#2 through #8) to block the invasion of Bigheaded carps while still serving USACE needs and having minimal effects in native fishes.
Researchers successfully collaborated with the United States Army Corps of Engineers (USACE) and developed new ways and technologies to impede the upstream movement of invasive (bigheaded) carp through their locks and dams in the Mississippi River. These approaches have now been implemented at Lock and Dam #8, which is the southernmost Lock and Dam in Minnesota and has thus been a focus. At this structure, dam spillway gate operating protocols were adjusted by the USACE to optimize their ability to stop carp and speakers added to the lock gates to deter carp with few effects on native fish. This is the first structure in the world to be so modified and our calculations suggest it now stops twice as many carp as it once did (well over 90%). Tentative plans for similar modifications to Lock and Dams #2 and #5 (the other most promising structures in Minnesota) have also been presented to the USACE for future deployment at their discretion. This progress was possible because we met all four objectives of this project: 1) added speakers to Lock and Dam #1; 2) quantified and published how well bigheaded carp swim (and thus what flows might stop them); 3) developed and tested several new acoustic systems in the laboratory and field that stop carp but do not affect native fish; and 4) developed new solutions for the gates at Lock and Dam #2-8 and provided specific data (specific solutions) for Locks and Dams #5 and #2, the most promising structures of these.