TOWN OF ROXBURY - The next steps in the rehabilitation of Mud Lake are about to begin as state fisheries crews and Dane County staff later this month transfer a variety of game fish and panfish fish back into the lake.
In January 2018, the Department of Natural Resources, in cooperation with Dane County and the Crystal-Fish-Mud Lake Rehabilitation District, treated Mud Lake in the Town of Roxbury with a naturally occurring chemical to rid it of nuisance common carp. The carp were harming water quality, the aquatic plant community, and the fishery.
Follow-up investigations after the treatment indicated it was successful, and now the next phase of the rehabilitation -- re-stocking -- can begin, says Nate Nye, DNR fisheries biologist based in Poynette and DNR's lead on the project.
"We're excited to be bringing fish back to prevent carp from taking over again and to provide fishing opportunities for anglers," he says.
DNR and Dane County staff with help from local volunteers will use nets to capture fish in Fish Lake and transfer them across the road to Mud Lake, reversing last fall's transfer of fish from Mud Lake to Fish Lake before the treatment.
Bluegill, largemouth bass, pumpkinseed, yellow perch, and golden shiner will be the main species returned to the lake. Nye says the transfer of these species will have no negative impact on Fish Lake.
"Our data indicates a very robust bass-bluegill fishery in Fish Lake and the fact we transferred fish from Mud Lake before the treatment will mitigate any losses from Fish Lake," he says. Additional native non-game species may be transferred as well.
The goal of the fish transfers is to create an environment unfavorable for carp so that if they ever return to Mud Lake, they will be unable to become abundant enough to disrupt the lake again, Nye says. Bluegill will act as the primary control mechanism for common carp because they eat carp eggs and fry, which limits juvenile carp survival.
Anglers and others urged to leave the fish transfer to DNR and Dane County crews
Anglers and others who are interested in the lake's rehabilitation are urged to leave the fish transfers to DNR and Dane County staff.
"It's important that people do not move live fish from any waterbody to Mud Lake because of the risk of introducing aquatic invasive species, fish diseases, or unwanted fish species to Mud Lake," says Pete Jopke, a water resources planner with the Dane County Land and Water Resources Department.
Transferring live fish between waterbodies is banned except in certain specific cases; the fish transfer is allowed here because the waters are connected. However, barriers have been installed in the connections between the lakes to prevent carp from Fish Lake from re-populating Mud Lake.
Dane County to install aeration system, another step to prevent carp return
After the fish transfers, DNR and Dane County will monitor the progress of the rehabilitation, and additional fish stocking may occur if needed, Jopke says.
As well, Dane County will install an aeration system in Mud Lake to prevent future winter fish kills due to low oxygen levels. In the past, carp have survived such winterkills while species like bluegill have died, preventing them from keeping carp populations in check.
For more information about the next phase of the rehabilitation, please contact Nathan Nye, Poynette Area Fisheries Biologist, Wisconsin Department of Natural Resources, (608) 635-8122 firstname.lastname@example.org or Pete Jopke, Water Resources Planner, Dane County Land and Water Resources Department, (608) 224-3733 email@example.com