Thousands of invasive carp removed from Lake Winona in Alexandria
Thousands of carp were removed from Lake Winona on Tuesday, Oct. 19 by the Alexandria Lake Area Sanitary District (ALASD) and commercial fishing crews. Consultants from WSB and Stantec coordinated the personnel involved in the project
About 4,500 invasive carp with a combined weight of over 26,000 pounds were removed from Lake Winona in Alexandria on Oct. 19 from the lake's south shore.
Commercial fishing crews did the job in coordination with the Alexandria Lake Area Sanitary District (ALASD) , DNR Fisheries and Santec and WSB staff. The Alexandria Airport also helped by allowing its runways to be used for access to the lake.
The fish were removed because of the damage they cause to submerged aquatic vegetation, according to Scott Gilbertson, executive director of the ALASD.
"Without the aquatic vegetation, water quality will continue to suffer," said Gilbertson, "Carp cause re-release of internal phosphorous, which produces algal growth and turbid water conditions by stirring up sediments from the bottom of the lake."
Gilbertson said the removal of the fish was accomplished through seine fishing — a method that uses a net, which hangs vertically in the water with its bottom edge held down by weights and its top edge buoyed by floats to surround the carp. They also used sound to push the carp into a specific area.
"A long net called a seine was laid out around the southwestern bay of Lake Winona to surround the carp. The net was dragged through the lake with gas-powered winches until it slowly contracted the fish," said Jordan Wein, an environmental scientist from WSB, whose headquarters is based in Minneapolis, was personally involved in the extraction. "Eventually, the carp were funneled into a holding pen near the shore where they waited until they could be trucked out of the lake."
Once in their holding pens, fishermen waded in the pen and hand loaded the carp into transfer bins located inside boats that float parallel to the pens. As the fishermen loaded the bins, personnel inside the boats used a scanner to check for carp with tags — some of the carp were tagged earlier to estimate how many were in the lake and their migration patterns.
After the bins were filled, the boats would head one at a time to the designated boat landing to get put onto a boat trailer, and then driven a short way to a water-filled-semi-trailer to haul the carp. The bins are weighed before being dumped inside the water-filled trailer where the carp remained alive for transfer.
"This was the first time the netter had worked this lake before, and was he a bit skeptical it could be done," said Wein. "Now, with one effort under his belt, I think we have set the stage for repeat efforts."
"Our goal is for Lake Winona to continue its water quality improvement through ALASD's Adaptive Lake Management Strategy," said Gilbertson, "ALASD is doing all we can to reverse existing lake quality impairments found in Lake Winona."
According to Gilbertson, the harvested carp were transported to be used for human consumption. A market for carp is located in New York.
" FisH2O (a WSB company) brokers the sale of the carp to the fishermen and then will likely be stored in managed ponds in Michigan. When a final buyer desires the fish, the fish will be easily netted and trucked, likely to New York for final sale," said Wein, "The last portion of the carp will go to a buyer in Omaha, Nebraska who sells fresh carp at a specialty carp restaurant.
After removal costs and consultant fees, the project will cost roughly $60,000, according to Gilbertson. Grant money from the Environmental and Natural Resources Trust Fund and the Legislative-Citizen Commission on Minnesota Resources helped fund the removal.
Initial planning and tagging activities started in 2018, with final carp density estimates performed in the fall of 2021, and the actual netting harvest took place on October 18-21.
The process was given the OK by the ALASD board of directors, the Minnesota Department of Natural Resources and the Minnesota Pollution Control Agency. The WSB and Stantec are consulting companies that were brought in the delegate and manage the operation. According to Wein, WSB coordinated all the different personnel, including ALASD staff, Stantec staff, fishing crews, airport crews, truck drivers, buyers of carp, DNR Fisheries staff, and WSB support staff.
Gilbertson said he appreciated the cooperation of the Alexandria Airport in the carp removal effort.
"Kreg Anderson and the staff at the Alexandria airport were extremely helpful in working with the crews to allow access to their boat launch area," said Gilbertson, "The project was successful because of airport staff allowing us access to their boat access."
According to Gilbertson, the ALASD was created by enabling legislation in 1971 to protect water quality in the Alexandria lake area from failing septic systems and upgrade existing treatment plant facilities that were not performing adequately. ALASD provides sanitary sewer services to an estimated population of 27,000, covering over 100 square miles, including the cities of Alexandria, Nelson and Forada, and the townships of LaGrand, Alexandria, Carlos, Ida, Lake Mary, Hudson and Leaf Valley. ALASD collects and conveys wastewater to its advanced wastewater treatment facility for treatment.
"We will need to monitor the efficacy of the carp harvest performed this fall," said Gilbertson. "There is a high probability we will need subsequent harvesting efforts in the spring of 2022 and beyond."
"Not confirmed yet, but WSB recommends further removal activities to occur," said Wein, "With what we have learned, WSB believes carp present in the upper portions near the upstream ponds could be removed into the netting area, and we can pick up where we left off."