Agencies to continue innovative search for invasive carp

Beginning Monday, Oct. 25, the Minnesota Department of Natural Resources will lead a second intensive invasive carp removal effort in Pool 8 of the Mississippi River near La Crosse, Wis. Thirty-four silver carp were captured in Pool 8 during the first interagency carp removal operation in April.

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. 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.

These MUM exercises were designed as part of a response to the capture of 39 silver carp and 12 grass carp in Pool 8 in March 2020. The goal is to remove invasive carp present in Pool 8, curb the potential for invasive carp reproduction, and prevent their establishment in Minnesota and Wisconsin waters. The operation will also yield more detailed information about any current invasive carp presence in Pool 8.

“This is a great move to get invasive carp out of our rivers. These fish continue to threaten Minnesota waterways, including those that flow through two national parks – the Mississippi National River and Recreation Area and the St. Croix National Scenic Riverway,” said Christine Goepfert, associate director of the National Parks Conservation Association and co-lead of the Stop Carp Coalition. “We need to use every tool we can to remove invasive carp and minimize opportunities for them to reproduce.”

There will be no impacts to the main channel of the Mississippi River or to commercial navigation.

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 net 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.

The DNR and other agencies will report the results when the operation and follow-up analyses are complete.

Anglers are reminded that invasive carp captures must be reported to the DNR immediately. Call 651-587-2781 or email (link sends email). 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.