Tagged fish lead to historic week for Asian carp captures on Pool 6 of the Mississippi

Trempealeau, Wis. — Kayla Zankle, Minnesota DNR invasive carp specialist, and her fisheries team spent many long, frustrating days this past summer trying to catch and tag Asian carp. Some days consisted of removing logs and other debris from their gill nets in the Mississippi River.

That spring and summer work paid off Thursday, Nov. 30, when the Minnesota DNR partnered with the Wisconsin DNR to catch 323 carp in Pool 6 of the river. It was the largest single capture of Asian carp in Minnesota to date.

The momentum rolled into Monday, Dec. 7, when the team captured an additional 77 Asian carp for a total of 400 over two days. Netting the carp required competent people, multiple agencies, and new technology like transmitters to track the fish.

Zankle said the spring and fall seasons are typically when schools of carp are in one place. Once the summer hits, the carp start to disperse. The efforts for Nov. 30 started about a week before the actual capture.

On Wednesday, Nov. 22, the DNR manually tracked a school of fish in Pool 6 because an automatic tracking system had been removed to prepare for winter. Since all six fish were tracked, Zankle wanted to try and capture some live fish.

On Nov. 30, the commercial fishermen started pulling the gill net near the Minnesota shoreline while Zankle and her team tracked and found the six transmitted carp. The gill nets were pulled to about 10 feet of water and the two DNR crews and commercial fishermen started sorting the fish.

“We need a bigger boat”

Once the count reached 30 carp, Zankle contacted the U.S. Fish and Wildlife Service as well as Grace Loppnow, Minnesota DNR invasive fish coordinator, and shared the Mississippi River equivalent of, “We need a bigger boat.”

“Once we hit 30 (carp), it was like we’re in trouble,” Zankle said. “At that point, when we hit 30 fish, I gave Grace (Loppnow) a call to let her know we did have fish and then I called Mark Fritts from (U.S.) Fish and Wildlife Service to let him know that we’ll have a lot of fish to work up.”

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The team in Pool 6 tied the net off and started dumping fish into Zankle’s boat, but reached a maximum weight after 70 carp. Then, the fish were put into a commercial fisherman’s boat until that maxed out, too.

It eventually took two maxed boats and one mostly full commercial fisherman’s boat to haul all the carp from the gill nets. Zankle said they confirmed 200 carp during the boat launch, but needed to fully count before an exact total was determined.

About 195 fish, weighing about 4,000 pounds, headed to the USFWS to work up so the agency could get information on each fish. The rest went up to the DNR metro office. On Dec. 1 and 2, the Minnesota DNR received another 21 carp from commercial fishermen.

Keeping the pressure on

Zankle said the team found evidence of another school near the Nov. 30 capture area. The team said it was potentially three times larger than the school from Nov. 30, so Zankle wanted to keep the pressure on them.

On Monday, Dec. 4, the Minnesota and Wisconsin DNR as well as commercial fishermen returned to Pool 6 and found the transmitted carp with a school of fish. After pulling the gill nets and sorting, they found 77 carp for another successful day.

“For this particular instance, honestly, it was a little bit of relief that we finally got our hands on these fish,” Zankle said. “After chasing them around all summer, especially having so many jump below Lock and Dam 5 in late May, it was honestly a little bit relief. It was a major success. These fish can put us in challenging places not only on the river, but mentally.”

The team is planning more capture efforts while open water holds out. Zankle said they have a short amount of time before the water freezes and the team can’t launch its boats.

The goal after the two days of captures is to place transmitters in as many carp as possible.

Unfortunately, Zankle said the DNR can’t perform transmitter surgeries when the water temperature drops below 38 degrees Fahrenheit. The team will have to wait on implanting transmitters until the spring.

Tagged fish key to it all

In 2023, Zankle said the DNR placed transmitters in 17 carp, which is more than the six to seven they’ve had in past years. The transmitters help the agency understand movement and locations of carp, and those fish eventually led to capturing 400-plus carp in two days.

“The more fish we can have tagged and back in the water, the better off we’re going to be,” Zankle said. “It’s hard to just tag one fish and base all of your sampling efforts off of the behavior of one fish.”

Loppnow said the DNR studied the captured carp and doesn’t believe there’s been reproduction in Minnesota. The carp show signs of reabsorbing their eggs for energy, and the age-structure of the fish suggests they came from downstream during flooding this past spring.

She added the spawning activities have occurred around Lock and Dam 19, and a large class of carp was formed in 2016 and 2020. The majority of the 400 captured carp were from the 2016 class, Zankle said.

As for the future, Loppnow said the DNR plans to continue adding transmitters to more fish to understand their advance. The team also plans to work with Wisconsin DNR and USFWS for more capturing efforts and monitoring.