In This Issue
 Map credit: U.S. Fish and Wildlife Service
The Minnesota Department of Natural Resources and the U.S. Fish and Wildlife Service have been using environmental DNA (or eDNA) technology to detect invasive carp in the St. Croix, Mississippi and Minnesota rivers. May sampling in the St. Croix River showed silver carp eDNA about four miles north of where invasive carp have been confirmed in the St. Croix.
eDNA is DNA released from an organism into the environment that is detectable at very low concentrations. USFWS screens for three markers: one for silver carp, one for bighead carp and one general invasive carp marker.
?While eDNA results are not conclusive evidence that invasive carp were present, eDNA is another helpful tool the DNR and partner agencies are using to learn more about invasive carp movements,? DNR Invasive Fish Coordinator Grace Loppnow said.
Due to the nature of eDNA and of invasive carp movements, caution must be taken in interpreting these results. eDNA analysis detects DNA in the water but cannot determine whether the DNA came from a living fish or another source such as bird feces or a fish carcass. It also does not determine when the DNA was deposited in that area. Invasive carp are highly mobile, so it is not unexpected that they would range throughout the open stretch of the Lower St. Croix River. For example, since 2017 the DNR has been tracking a tagged bighead carp on the St. Croix that has a home range of about 23 river miles. Tracked invasive carp in other states are known to range more than 60 miles.
USFWS staff notified the DNR last week that eDNA samples from May showed a small percentage of positive samples in the St. Croix River at Andersen Bay near Bayport and the Boom Site just upstream of Stillwater, a priority invasive carp surveillance area. Of the 100 samples taken in Andersen Bay, five tested positive for bighead carp DNA and three tested positive for a general marker for invasive carp DNA. Of the 100 samples taken at the Boom Site, three tested positive for silver carp DNA and one tested positive for the general invasive carp marker.
The DNR regularly samples for invasive carp in Andersen Bay and has removed several bighead and silver carp from the bay and the adjacent portion of the St. Croix River in years past. No invasive carp have been captured in Andersen Bay thus far in 2022. Andersen Bay is one of the locations that the DNR-tagged bighead carp frequents, making this area a target for surveillance and management.
The Boom Site detections are approximately four miles north of the farthest upstream capture of invasive carp in the St. Croix River, and approximately one and-a-half miles upstream from the farthest detection of a tagged invasive carp. In response to these detections, additional sampling at the Boom Site is planned for this fall.
The DNR believes continued eDNA monitoring in both Andersen Bay and the Boom Site is important as part of a proactive approach to invasive carp monitoring and response. Changes in the eDNA detection rate over time can be used as a tool to assess potential changes in the invasive carp population. eDNA may also be used to identify locations to target for management. To that end, the DNR is working with USFWS to explore how eDNA can be used to inform targeted removal efforts, including the Modified Unified Method the DNR, USFWS and other agency partners piloted on the Mississippi River in 2021-2022.
Invasive carp have been progressing upstream since escaping into the Mississippi River in Arkansas in the 1970s. These large fish compete with native species and pose a threat to rivers and lakes. Thus far, there has been no evidence of reproduction or spawning populations in Minnesota waters.
Individual invasive carp have been caught as far upstream as Pool 2 of the Mississippi, near the Twin Cities (bighead, grass and silver), the King Power Plant on the St. Croix River by Oak Park Heights (bighead and silver), and just downstream of Granite Falls in the Minnesota River (bighead). Invasive carp have also been captured in the Missouri River drainage in southwest Minnesota, where control structures are in place to prevent invasive carp movement into Minnesota waters.
The DNR is actively engaged with several other prevention efforts:
- The DNR is an active partner in the Upper Mississippi River Invasive Carp Workgroup. The group includes representatives from Minnesota, Wisconsin, Iowa, Illinois, Missouri, and several federal agencies.
- The Minnesota Aquatic Invasive Species Research Center at the University of Minnesota, in partnership with the DNR, is testing and evaluating carp deterrents in Mississippi River locks and dams.
- The DNR leads a program to monitor fish population changes and impacts of management actions.
- The DNR leads Modified Unified Method events to capture and remove invasive carp, in partnership with the USGS, Wisconsin DNR, USFWS and other agencies.
- The DNR is working closely with stakeholders to update the Minnesota Invasive Carp Action Plan. (files.dnr.state.mn.us/natural_resources/invasives/carp-action-plan-draft.pdf)
State and federal funding sources, including the Environmental and Natural Resources Trust Fund and Outdoor Heritage Fund, have provided key funding for deterrent actions and the DNR invasive carp detection and response program.
Invasive carp captures must be reported to the DNR immediately by calling 651-587-2781 or emailing [email protected]. Take a photo and transport the carp to the nearest DNR fisheries office or make arrangements for it to be picked up by a DNR official. Do not release captured invasive carp. A permit can be requested (mndnr.gov/Permits/Invasive_Species) to keep captured invasive carp for consumption or disposal.
More information about invasive carp is available on the DNR website (mndnr.gov/Invasive-Carp). More information about the eDNA program is available on the Whitney Genetics Laboratory website (fws.gov/office/whitney-genetics-laboratory/what-we-do/projects-research).
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 Photo credit: Minnesota DNR
The Minnesota Department of Natural Resources has been notified of a fish kill that included 140 invasive carp below the Lake Bella Dam in Nobles County. This is the largest documented number of invasive carp in one location in Minnesota.
DNR crews followed up on the report to recover the carcasses and take data on the invasive carp. Low oxygen levels due to low water and high temperatures are believed to be the cause of the fish kill.
Lake Bella is about 100 yards from the Iowa border and is connected to the Ocheyedan River, which in turn connects to the Little Sioux and Missouri Rivers in Iowa. Populations of invasive carp have been confirmed in those rivers of the Missouri Basin, south of the Minnesota border, since at least 2011. The DNR routinely collects invasive carp below Lake Bella Dam.
?There is a dam at the Lake Bella outlet that keeps invasive carp out of the lake, and it would take an extraordinary flood event to overtop the structure, so there is currently no concern about these carp moving farther upstream into the reservoir,? DNR Invasive Fish Coordinator Grace Loppnow said.
Invasive carp have been progressing upstream in the Mississippi, Missouri and Ohio river basins since escaping into the Mississippi River in Arkansas in the 1970s. These large fish compete with native species and pose a threat to rivers and lakes. No breeding populations have been detected in Minnesota waters.
The DNR Invasive Species Program has built partnerships with state and federal agencies, conservation groups, university researchers and commercial businesses to prevent the spread of invasive carp.
The DNR is actively engaged with invasive carp prevention efforts in southwest Minnesota.
- The DNR proactively surveyed the Missouri River watershed in Minnesota to identify locations to prevent expansion of invasive carp populations in southwest Minnesota. The DNR completed eight projects that limit expansion and protect valuable aquatic resources. Lake Bella?s dam structure already prevented fish movement, so no additional work was needed at that location.
- The DNR provided financial support to the Iowa DNR to build an electric barrier at the outlet to the Iowa ?Great Lakes? Okoboji area. The outlet channel also flows into the Little Sioux and Missouri rivers. This barrier helps protect not only the Iowa lakes but also aquatic resources in southern Minnesota.
- The DNR Fish and Wildlife Division leads a comprehensive sampling program to monitor fish population changes and impacts of management actions. This includes routine monitoring in southwest Minnesota.
State funding sources, including the Environmental and Natural Resources Trust Fund and Outdoor Heritage Fund, and the U.S. Fish and Wildlife Service have provided key funding for deterrent actions and the DNR invasive carp detection and response program.
Invasive carp captures must be reported to the DNR immediately by calling 651-587-2781 or emailing [email protected]. Take a photo and transport the carp to the nearest DNR fisheries office or make arrangements for it to be picked up by a DNR official. Do not release captured invasive carp. A permit can be requested (mndnr.gov/Permits/Invasive_Species) to keep captured invasive carp for consumption or disposal.
More information about invasive carp is available on the DNR website (mndnr.gov/Invasive-Carp).
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