OUTDOOR CORNER: GETTING THE FACTS ON LAKE GIRARDEAU

It seems that there has been some interest in the management of two of Southeast Missouri's more popular lakes: Lake Girardeau and Wappapello Lake.

In the past year there has been some controversy concerning several management activities involving Lake Girardeau and Wappapello Lake. This week we'll take a look at Lake Girardeau and next month we'll discuss Wappapello Lake.

I thought it would be fun to play a game and at the same time try to address these issues. So let's play 'Fact or Fiction'.

Fact or Fiction? The fertilizer we apply to Lake Girardeau each year causes extremely high pH readings (the acidity or alkalinity) of the water. Fiction! We fertilize the lake to increase it's fertility and productivity. The result is more plankton (microscopic plants and animals which form the base of the food chain) which helps grow more bass and crappie. The normal pH value in a productive system like Lake Girardeau should be 7-9.

We have checked the pH levels nearly every month for the past year and have not found any abnormal readings. This spring we measured the pH immediately before and after the fertilizer was applied and two weeks after application. There were no abnormal readings.

Fact or Fiction? The fertilizer we apply in Lake Girardeau each year makes the water turn green, which causes no sunlight to reach the fish eggs, and prevents the eggs from hatching.

Fiction! The opposite is true. Sunlight will actually damage the eggs so applying fertilizer will not hurt spawning success.

Fact or Fiction? The muskies that have been stocked into the lake have eaten most of the other fish.

Fiction! During our annual electrofishing survey this past April we caught 609 adult bass or 254 bass per hour which was the highest catch rate in over 10 years. We also caught 852 bluegill or 473 per hour, which is also a high catch rate.

Fact or Fiction? Muskie survival has been poor in Lake Girardeau.

Fact! If our spring netting efforts are accurate, then stocked muskies have not fared well in Lake Girardeau. This spring, we only caught three muskies during our netting surveys; two were almost 40 inches long and one was 34 inches long. It is possible that the large bass in the lake ate many of the small muskies soon after stocking, or some other environmental factor caused poor survival.

Fact or Fiction? There aren't as many large bass in the lake as there used to be.

Fact! This spring, the percent of bass longer than 15 inches was 7% and 3% for those longer that 18 inches, which is slightly less than the 10-year averages.

Why are there fewer large bass in the lake? There are plenty of bluegill and gizzard shad for the bass to eat so food is not the problem.

The number of bass decrease just above the 12- to 15-inch slot limit, suggesting that anglers are harvesting many bass longer that 15 inches. If more anglers would release the larger bass they catch, then these number should increase.

Fact or Fiction? There are no crappie left in the lake.

Fiction! Last spring we caught numerous crappie less than 6 inches long and fair numbers of large crappie, over 11 inches long, in our muskie nets.

We also sampled the crappie population with trap nets last fall, which is the standardized method used by biologists statewide to assess crappie populations. We again caught good numbers of crappie less that 7 inches long. Most of these were black crappie, with fair numbers of white crappie.

It is true that few crappie were caught between 7 and 11 inches long which has caused most of the concern about the crappie fishery. However, this missing year class is nothing to be alarmed about because some years crappie don't spawn successfully and there is no apparent reason why. The numbers of small crappie are encouraging and should provide good fishing for several years.

Mark Boone is a fisheries management biologist with the Missouri Department of Conservation.