Carp management is a from-the-ground-up process

Published 10:15 pm Sunday, July 1, 2018

Editor’s note: This is the second in a five-part series on carp management efforts in the area.


If you want to mimic the feeding style of the common carp, you’ll have to start looking for meals by prying up your floorboards.

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There’s a similar associated destruction, too, for the lake’s ecosystem when the common carp population is too high, and managing that population is one way the Shell Rock River Watershed District is trying to restore balance to Fountain Lake.

For district conservation technician Scott Christenson, this effort doubles down on efforts already conducted by the Watershed District in terms of carp management. According to Tony Havranek — senior ecologist for WSB, the firm hired by the Watershed District to aid in carp management — this year’s plan is twofold: confirm the efficacy of already established management strategies and, through tagging and tracking carp, collect data on carp behavior to better inform future population control efforts.


Nothing new to the area, or the state

Common carp are not new to Fountain Lake. They are not new to the Watershed District, and according to Minnesota Department of Natural Resources invasive fish coordinator Nick Frohnauer, they are not new to the state of Minnesota.

“They’ve been around since the early 1900s — since they were originally stocked here — and they’ve become well-established and widespread,” he said.

Common carp are omnivorous fish, and they’re large — the kind of fish that, when they grow up, take two hands to hold. They have large scales, a long dorsal fin base and two pairs of long whiskers the DNR calls barbels and a child might call a moustache.

According to invasive species information provided to the public by the DNR, the common carp is native to Europe and Asia but was introduced to the Midwest as a game fish in the 1880s. In Minnesota, the common carp has a heavier presence in the southern two-thirds of the state’s waters than in the northern third. But Minnesota isn’t alone: the common carp is established in 48 states, the DNR said.

Common carp are benthic-feeding fish, rooting up vegetation, feeding down into the lake bottom and disturbing soil. Phosphorus often binds to sediment, so disturbing that lake bottom means increasing the amount of suspended phosphorus in the water column, which in turn leads to increased algae blooms, Christenson said.

In addition, when carp uproot existing vegetation, they’re destroying habitat used by baitfish as cover in their endless, high-stakes game of hide and seek. Aquatic vegetation also plays a key role in waterfowl resting areas, such as in Upper and Lower Twin lakes, where waterfowl look for places to rest and eat.

While there may be no direct competition between common carp and game fish like bluegill, walleye, perch and pike, the way carp feed still affects their food chain, Christenson said. When a walleye spawns, he said, the baby fish has to be “practically swimming in food” to survive. With murky water caused by disturbed sediment, sight-feeding fish may find it harder to clock food.

If they’re contributing to the food chain at all, it is only as food themselves: baby bluegills are partial to carp eggs, Christenson said, and northern pike will feed on young carp, Havranek said.

Christenson said managing the carp population can help improve fisheries on Fountain Lake.

In Minnesota, the common carp is classified as a regulated invasive species. Fish caught can be returned to the same water body, but not released into the wild.


Starting at the bottom

Aside from staff time and equipment purchases, Christenson said this year’s carp management efforts are covered by Aquatic Invasive Species Prevention Aid funding provided to Freeborn County.

Think Oprah for county government: “You get Aquatic Invasive Species Prevention Aid funding. You get Aquatic Invasive Species Prevention Aid funding. Every county, depending on how many boat launches and boat trailer parking spots you have, gets Aquatic Invasive Species Prevention Aid funding.”

According to the Minnesota Department of Revenue, it divvies out $10 million in Aquatic Invasive Species Prevention Aid each year. The Department of Revenue’s funding calculation of how much each county gets is split half and half between launches and parking based on the county’s share of the overall number of boat launches and trailer parking spots in the state.

To Christenson, this makes sense.

“The more water you have, the more money you should get, because it’s just that much more to monitor,” he said.

WSB’s carp management proposal, submitted to the Watershed District the last day of February, outlines the firm’s task fees based on hourly calculations, totaling $47,138. Equipment costs, including one complete passive integrated transponder station, 10 radio tags each for Albert Lea and Fountain Lake and surgical supplies, hit $9,720. The total hits $56,858, all in the name, WSB’s proposal said, of improved water quality and ecological integrity — from the floorboards up.

“(Carp) affect the whole ecosystem, from the bottom up, and to have a healthy lake, you need to start at the bottom,” Christenson said.

Find the first part of the series here.

Find the third part of the series here.

Find the fourth part of the series here.

Find the fifth part of the series here.

About Sarah Kocher

Sarah covers education and arts and culture for the Tribune.

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