We have had an unusually hot summer this year. When it gets as hot as it has been for the past two months, it is too hot to even go fishing.

One of my responsibilities with the Robeson County Center of the North Carolina Cooperative Extension Service is aquaculture. In this role, I try to provide information and assistance to people in the county who want to develop aquacultural enterprises on their farms, such as fee fishing, crawfish production, commercial catfish production, fresh water shrimp production, and even bull frog production.

I also assist people in the county with the management of recreational ponds. There are hundreds, possibly thousands, of small recreational ponds in the county. Some of these ponds have been created by damming a run in a stream to create ponds anywhere from a couple of acres in size to as much as 40 acres in size. But most of these ponds have been dug with drag lines or track hoes and usually range in size from a tenth of an acre to as much as a half of an acre.

One of the main objectives of owners of these small ponds is that there be good fishing in the pond. Proper stocking and then managing the fish population throughout the years is the best strategy for maintaining the right fish population. Supplemental feeding encourages fast growth of these fish, which actually makes them more aggressive and more active since they tend to be more healthy.

I often receive phone calls during the summer from pond owners about fish kills in their ponds. They call to say they found several dozen dead fish floating when they went out to the pond.

This is not usual for this time of the year. Well-constructed and well-managed ponds do not usually have this problem, but even these ponds may occasionally experience a fish kill. The ponds most affected are usually those that have other problems, such as weeds, muddy or turbid water, overpopulation, or lots of shallow water.

During the summer, water temperatures in these ponds increases. The warmer the water, the less oxygen it will hold. Weeds in the ponds, like trees and other plants, use carbon dioxide and produce oxygen during the day when the sun is shining. But after the sun goes down, the process reverses. The plants use oxygen and produce carbon dioxide.

If the oxygen level is low in the pond because of warm water temperatures and weather conditions, such as cloudy days, prevent the aquatic plants from generating oxygen, the oxygen level in the pond may drop so low that the fish can no longer survive. Naturally, the weaker fish will be the first to die.

Oxygen levels in ponds will be higher during the day and lower during the night. Fish will warn you if the oxygen level is low. They will gather at the top of the ponds, gulping for air like a gold fish in a bowl. Pond owners should monitor their ponds closely during the summer by watching the fish activity very early each morning.

Another problem associated with these ponds is summer thunderstorms. As mentioned earlier, the warmer the water the less oxygen it will hold. In addition, normally the deeper the water the less oxygen available. When a sudden thunderstorm dumps a lot of cold water into a pond, the water in the pond will do just like air in a room. The cold water will settle to the bottom, and the warmer water from the bottom will rise to the top. Since most fish in the pond use the upper water level for feeding and resting, they are suddenly subjected to water that does not contain enough oxygen for them to survive. This is when most fish kills happen, immediately following a heavy, nighttime thunderstorm.

Naturally, weeds in ponds are like weeds in gardens. They are more severe during the summer than at any other time of the year. I receive many calls from pond owners during the summer wanting to know how to get rid of algae or other weeds in their pond.

When weeds die, they begin to decay. It requires oxygen for the decaying process. So as these weeds decay, they use up a lot of the valuable oxygen from the water. This creates fish kills.

Even though severe weed problems in a pond during the summer may be objectionable, it is best not to do anything about them at this time. Do not do anything that will further upset the delicate balance in the pond. Just leave these weeds alone until the water temperature drops down some in the fall.

Weeds problems in a pond do not happen overnight. They become established in the pond, and since the problem is not too severe, they are ignored. They continue to get worse each year until they eventually become a problem.

Good pond management can prevent weed from becoming a problem in a farm pond. Good management can provide a healthy, balanced fish population. Good management can prevent headaches and unwanted expenses later.

If you have a recreational pond on your property and want to know more about how to manage it, please give me a call. If you are experiencing problems with your pond, I may be able to help. Give me a call at 910-671-3276.

E-mail address: Everett_Davis@ncsu.edu

Mailing Address:
P. O. Box 2280
Lumberton, NC 28359-2280

Phone: 910-671-3276
Fax: 910-671-6278

Date Created 8/25/05