By Forrest Adams

University of Minnesota researchers were back in Chanhassen this week hunting for common carp in Lake Lucy and Lake Susan.

With a commercial fishing group from Cambridge, Minn., they removed some of the bottom feeders and radio tagged others. The group is scheduled to seine for carp on Lake Riley this Thursday.

Researchers from Sorensen Labs started implanting radio tags in carp they caught in Susan and Riley in 2006. The radio tags emit frequencies that allow researchers to track the fish. Sorensen Labs — with funding support Riley-Purgatory Bluff Creek Watershed District — is hoping to develop an internationally applicable carp management plan. Carp are a sport fish in some places, but in others they are blamed for creating poor lake water quality.

Last winter, about 3,300 carp were removed from Lake Susan, far more than the 185 that were removed on Monday. Approximately 890 carp remain in Susan, according to Przemek Bajer from Sorensen Labs. He said this year’s low carp capture was probably because so many were removed last year. He also noted some of the fish were able to get away, as indicated by the movement of radio-tagged fish right after the net was deployed.

“It is possible that some of them have learned how to avoid the gear,” said Bajer. “At this stage we are trying to reduce the number of carp in a controlled fashion to determine the relationship between the density of carp and water quality in the lake. In reality, it is more than merely water quality. We are looking at the effects of carp on vegetation, fish and water quality.”

Researchers expanded their efforts last spring to include Lake Lucy, a small, private Chanhassen lake. The theory is that Lucy is the headwaters of the watershed district. If carp can be controlled there, they can be controlled elsewhere. Last week was the first winter seine from Lake Lucy; 642 carp were captured. All of them were returned to the water with radio tags. Researchers plan to return next winter to capture and remove the fish permanently.

“Once they’re gone, that lake should be cleared out,” said Peter Sorensen, professor of fisheries. “Those are old, adult fish that have been doing a lot of damage for a long time. Lucy is the headwaters. We’re concerned about movement from Lucy out to Ann and down into the other lakes. We want to track how they move between lakes.”

Also on the frozen lake as the fishermen pulled their nets and researchers measured fish, Al Sinnen, a lifelong Chanhassen resident, leaned on his cane. The cold winter wind cut into Sinnen’s face as he spoke about a similar event he took part in decades earlier.

“It had to be back in 1945,” he said. “Big Al Klingelhutz and I and the Klein kids dug holes in the lake with chisels. It was hard work. Some fishermen pulled a net under the ice that covered the whole lake. There were so many carp in that net that the basket wouldn’t hold them. Seeing research in this lake so many years later is pretty neat.”

Readers can contact Forrest Adams at fadams@swpub.com.

Why catch carp?
Researchers from Sorensen Labs out of the University of Minnesota are studying common carp in the Riley-Purgatory Bluff Creek Watershed District, including Chanhassen’s Lake Lucy, Lake Susan and Lake Riley in order to develop a carp management plan that is internationally applicable.