Bighead and silver carp are both species of Asian carp that continue to be of concern in the Upper Mississippi and Ohio rivers. Their feeding habits starve other native species cause turbidity in the waters where they feed, detrimentally altering the habitat that supports native species.
On the Mississippi River, while Lock 19’s lack of moveable dam gates has slowed the Asian carp’s spread upstream, both bighead and silver carp have established reproducing populations as far upstream as Pool 17 in southeastern Iowa. Every year, the Minnesota Department of Natural Resources conducts controlled fish captures in locations favored by invasive carp and publishes the results in an annual report. In 2018, two bighead carp were captured in the St. Croix River and one was captured in the Minnesota River. St. Anthony Falls in Minneapolis provides a barrier to upstream movement into the Mississippi’s headwaters since the Upper St. Anthony Falls lock was closed to navigation in June 2015.
The U.S. Fish and Wildlife Service (USFWS) is the federal lead on the Asian carp issue. The USFWS works with the U.S. Army Corps of Engineers via lead coordination through the Great Lakes and Ohio River Division. The USFWS participates in the Mississippi Interstate Cooperative Resource Association’s Asian Carp Advisory Committee. In November 2015, the committee published its “Monitoring and Response Plan for Asian Carp in the Mississippi River Basin.” The plan includes best practices, sampling, monitoring and response plans, control and removal plans, and coordination and outreach plans.
Strategies for limiting upriver movement of Asian carp include acoustic and bubble barriers in the lock chambers and adjusting gate operations to make it more difficult for the carp to swim through the gated portion of dams.
The Corps’ St. Paul District is working with other federal and state agencies to increase awareness of Asian carp behaviors and likely deterrents. The St. Paul District is permitting the University of Minnesota’s Aquatic Invasive Species Research Center (UMAISRC) to conduct flow modeling and field studies on Asian Carp swimming capabilities and behaviors at Locks and Dams 1, 2, 4, 5 and 8.
The St. Paul District has permitted installation of an acoustic barrier speaker system and has received approval for a trial run to modify dam gate operations at Lock and Dam 8 to resist the passage of Asian carp. Further investigations by the UMAISRC are underway at Lock and Dams 2, 4 and 5, but the Corps is not currently considering operational changes at these sites.
Congress authorized the Corps via 33 U.S.C. Section 408 to permit alterations and modification to existing Corps projects if the proposed action does not adversely impact the project purpose and is not injurious to the public.
Asian carp related activities are funded, as needed, out of the Special Investigations program.