Beginning April 5, the Minnesota Department of Natural Resources will lead an intensive invasive carp removal effort in Pool 8 of the Mississippi River near La Crosse, Wis. The innovative Modified Unified Method (MUM) combines netting and herding techniques to drive and concentrate invasive carp from a large area of water into a small zone for removal.
This is the first time the MUM method has been used in Minnesota or Wisconsin waters and the first time it has been used anywhere as an early detection and rapid response technique. The DNR is conducting this work in partnership with the Wisconsin Department of Natural Resources, the U.S. Geological Survey (USGS) and the U.S. Fish and Wildlife Service.
This MUM exercise was designed as part of a response to the capture of 39 silver carp and 12 grass carp in Pool 8 in March 2020. To date in 2021, there have been eight additional invasive carp captured in or near Pool 8. The goal is to remove invasive carp present in Pool 8, curb the potential for invasive carp reproduction, and prevent their establishment in the Upper Mississippi River Basin. The operation will also yield more detailed information about any current invasive carp presence in Pool 8.
“Thanks to the Minnesota Department of Natural Resources, we continue to break ground in the effort against invasive carp in our waters,” said Christine Goepfert, associate director of the National Parks Conservation Association and co-lead of the Stop Carp Coalition. “This field exercise to reduce carp in the Mississippi River is a positive step forward. This effort will help protect waters upstream, including the national park waters of the Mississippi National River and Recreation Area and the St. Croix National Scenic Riverway.”
This thorough search and removal effort will last for seven to 10 days. Progressive areas of Pool 8 will be closed for one to three days during this time, temporarily suspending commercial fishing and recreational use of portions of Pool 8. The operation will pause on Saturdays and Sundays, due to typically higher weekend boat traffic. The DNR has been contacting commercial fishing operations and others who might be affected to inform them of the effort and share the expected long-term benefits.
The MUM method, developed by the USGS, uses block nets to create compartments or “cells” from which the fish can be driven. The USGS then uses electrofishing boats and boats outfitted with underwater speakers to herd carp from each cell. When a cell is cleared, another net is used to close the cell and prevent the fish from returning. This process is repeated one cell at a time, gradually reducing the area available to the carp and concentrating the fish into a harvest removal area, where a large commercial seine will be used to draw out the congregated fish. Native fish do not seem to respond in the same way as the invasive carp, preferring to hide, rather than run, from the sound stimulus.
Five invasive carp previously tagged with acoustic transmitters will complement this effort by increasing effectiveness of targeting fish in Pool 8 and providing insights into their movements and other behaviors.
The DNR and other agencies will report the results when the operation and follow-up analyses are complete.
Invasive carp captures must be reported to the DNR immediately. Call 651-587-2781 or email [email protected]. Take a photo and transport the carp to the nearest DNR fisheries office or arrange for it to be picked up by a DNR official.
More information about invasive carp is available on the DNR invasive carp webpage.