LAKE AERATION PROJECT SHOWING POSITIVE SIGNS

There are two pump stations for the 20 diffusers located throughout the lake. This year the department of conservation hopes to only use one pump per station to keep the lake from stratifying during the summer. The other pumps will remain idle, unless they are needed as a backup.

This week the Missouri Department of Conservation performed a number of maintenance tasks at Perry County Community Lake. Some kinks in the aeration lines had to be straightened out and some other fish surveys were performed to gauge how well the system worked during its first year.

Last year, the department installed an aeration system into Perry County Community Lake in an attempt to destratify the lake. The goal of this project is to produce bigger and healthier fish for anglers.

A stratified lake means that there are layers of water with varying levels of oxygen. The layers are easily detected by swimmers because of a dramatic decrease in water temperature between the layers.

Stratified lakes are a common problem in small impoundments like Perry County Lake.

The lake would stratify in the summer months. Last year the lake was stratified in June when the installation was completed. It took the system until August to destratify the lake.

The aeration system was on from June to October last year and was turned on again this year in April. It will be turned off again in October.

In the past summers, at this lake, all of the fish were located in the top 7-feet of water. The oxygen levels in water below 7-feet were too low to support any fish.

The lake's depth goes to 32 feet. So all the fish were located in the upper layer and its temperature in the summer months was a tepid 86 degrees or warmer.

Fish in conditions such as these do not grow well, many don't feed at all. While some fish do feed in these warm conditions, they use up almost all of their energy to survive under the warm conditions. Meaning they do not grow very much during this time.

While the lake has plenty of cool water in depths below 7-feet, there was not enough oxygen to support the fish.

In short, if the fish wanted to cool off, they had to hold their breath.

An aeration system was added to try to fix this problem. The stratified lake has led to a stunted crappie population. But the aeration system was put in to help all the fish.

A population estimate done in 1997 showed there were approximately 27,000 white crappie in the 100-acre lake that were larger than 5-inches. Of those, 95 percent were smaller than 9-inches.

"Typically, what we see in situations like this is either a lake with a large amount of small crappie or one with a small amount of large crappie," Steven Fischer, fisheries research biologist for the Missouri Department of Conservation, said.

The aeration system is in reality acting as a mixer for the lake. While it is pumping needed air into the lake, its main purpose is to move the cooler water upwards and the warm, oxygenated water downward.

Last summer the system succeeded in reducing the water temperature by an average of four to five degrees Fahrenheit, Paul Cieslewicz, fisheries management biologist with the Missouri Department of Conservation, said.

Some other signs of success with the project have been signs of more insects in the lake's sediment in areas that before couldn't support life. This in turn creates more food for the fish.

"We've seen a big boom in insect production," Fischer said.

Fischer said he is also working on a similar lake near Kansas City.

This is the first such aeration system of its kind in the state and hopefully the next three years will show other signs of success that include 3-year-old crappie at 9 inches or greater. Right now the crappie are about 8 inches at that age in this lake, Cieslewicz said.

The system is up and running two months earlier than last year and it is hoped that only 10 of the 20 air diffusers and only two of four pumps will have to be used to keep the lake from stratifying this summer. If the system at half power won't do the job, the other half is ready to go.

Each month Fischer does field studies to monitor the lake's progress. Electrofishing surveys are performed to collect scales and measure and age fish. Also, food analysis studies are made to document any change in food habits and to determine if the fish are eating any invertebrates and fish.

The more insects in the fish's diet will be an early indication of the aeration system's success.

This year's electrofishing survey revealed a good number of bass around 19 to 20 inches. And they looked healthy. They are making nests now and the fishing is good.

The redear sunfish are really good at the lake and there are plenty of redears over 10 inches. The bluegill fishing is good with many at 6 and 7 inches.

The crappie for the most part have left the shoreline, but some males are still swimming along the shore.

Conservation Agent Eric Abbott said many anglers are leaving the lake with their limit of crappie.