Grass eating carp helping to clean up lake

Isaac Hett, superintendent at Marion County Park and Lake, sits next to Stone Arch Cove where the grass-eating carp were released. In just two months since the carp were released the moss and algae have cleared substantially. Patty Decker/Free PressResidents at Marion County Park and Lake’s Stone Arch Cove called in some real “gluttons” to save their inlet from moss overtaking the area.

Gordon Pendergraft, one of the cove residents, said he did some research on grass carp, and discovered they feed exclusively on vegetation present at the lake.

“I was told (grass carp) eat 10 times their body weight a day,” he said. “They were also expensive, but several neighbors shared the cost.”

The Kansas Department of Wildlife, Parks and Tourism signed off on the grass carp being introduced to the cove.

In an effort to keep the grass carp isolated in the cove, a gated fence wrapped with chicken wire was positioned at the opening of the stone archway, Pendergraft said.

“We didn’t publicize the idea (of the grass carp) too much,” he said, “but they seem to be doing their job.”

These particular carp were purchased from Culver Fish Farm, McPherson, just over two months ago, and Pendergraft said he has a good feeling about how it’s going.

“The cove is about 2.5 acres, and the average amount of grass carp needed were 10 per acre,” he said. “I wanted grass carp about 10 to 14 inches long, but they didn’t have that size, so these are slightly smaller.”

In total, he said, 25 to 30 small grass carp were released in the cove once the fencing was in place.

One reason, Pendergraft said, the cove had too much moss could have been because of the warmer, earlier spring weather prompting a more than average growth of vegetation.

Adding to that, the cove is fairly stagnant, save a fountain that moves the water during certain times of the day.

Isaac Hett, superintendent at Marion County Park and Lake, said that for people living on the cove, the overgrowth of moss wasn’t a welcome sight.

“It was difficult to maneuver boats through the moss, there was no fishing and something needed to be done,” Hett said.

This shows the results of the carps efforts.Patty decker/Free PressEven though the grass carp are experimental, Pendergraft said the fish have already made a big difference.

“I would love to see one of the grass carp and how they are growing,” he said. “Once the water clears up, I should be able to see them from my deck.”

For now, the experiment seems to be working, but both Hett and Pendergraft are aware that they need to watch how much the fish are consuming.

Being able to eat anywhere from two to 10 times their weight every day, they might gain five to 10 pounds in a year, Hett said, and they can grow up to 50 pounds or more.

“The larger they get, the more plant material they consume,” Hett said.

Some of the concerns Pendergraft said he is watching for is how much the carp eat and how quickly the moss is disappearing.

“We don’t want them to eat all the vegetation because the smaller fish need that for protection,” he said.

Since grass carp cannot reproduce, they are an excellent way to control and prevent the spread of aquatic flora and submerged plants, Hett explained.

Without knowing how well the grass carp would be able to clear away a lot of the moss, Pendergraft said, it’s been amazing how fast these fish work.

“I don’t think the gate will be permanent (between the cove and main lake), it’s an experiment. But, in talking to Culver Fish Farm, once the fish get accustomed to the area, they probably won’t leave the cove,” he said.

“We will wait and see what happens as they get bigger and what they are eating,” he added.

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