Principles of Pond Mangement
Some basic biological principles must be understood before a pond can be properly managed. The pounds of fish that can be produced are limited and are affected by several factors: proper construction, nutrients, the quantity and quality of fish food, proper brood stock, elimination of unwanted competition, and efficient harvest of surplus fish.
A question often asked is “how many bream and bass should I harvest from my pond?” Carrying capacity and yield limit are terms often used by biologists to answer this question. Biologists define the carrying capacity of a pond as the maximum pounds of fish that can be maintained in the pond without depleting the food supply of the fish. Yield limit is defined, as the maximum pounds of harvestable-sized fish a pond will yield from year to year without detrimental effects to the balance of the fish population. Yield limit is dependent on the species of fish present, amount of food available to the fish, rate of harvest and other factors. Yield limit as used in this booklet refers to the harvest of bream and largemouth bass, since this stocking combination is normally used in Alabama.
Nutrients are very important in the production of fish food organisms and therefore in the production of fish. Simply stated, nutrients increase the amount of food available to the fish, which results in greater fish production. Nutrients are needed to promote plankton, which are microscopic plants and animals that cause pond water to appear green, brown, blue, yellow or red. Plankton form the base of the food chain in bass and bream ponds. Plankton are consumed by small microscopic animals such as water fleas, insects, worms, and others which are eaten by fish.
Plankton cannot grow without sunlight and adequate amounts of nutrients. Nitrogen, phosphorous, and potassium are the primary nutrients. However, they are not usually available in ponds in sufficient quantities to produce adequate plankton populations needed in the food chain of fishes. Therefore, nutrients must be added to ponds for maximum fish production. Nutrients are usually applied in the form of inorganic, commercially produced fertilizers. Ponds that are fertilized and managed properly can yield about 175 pounds of bream and largemouth bass per acre per year. In comparison, unfertilized ponds will yield only 25 to 50 pounds per acre annually. The total weight of fish that a pond supports may be comprised of many fish too small to be desired by anglers or of a lesser number of large fish that are appealing to sportsmen. A desirable bass-bream population is one in which 60 to 85 percent of the total weight is composed of harvestable-sized fish. If a pond maintains such a population and provides satisfactory yields of fish from year to year, it is considered to have a balanced fish population.
The time of year the pond is stocked is critical in achieving a balanced fish population. Bream are stocked in the fall and winter months. Bass are stocked the following May or June. A bream-largemouth bass population normally attains a balanced condition 12 to 14 months after the bass fingerlings are stocked. During the first 20 months after bream are stocked, growth and reproduction rates are very high. The pond experiences a population explosion because large amounts of food are available. The fish reproduce and increase in weight until most of the food is utilized. At that time, their growth rates decrease or stop until some of the fish die, are caught, or otherwise are removed from the population. At this point (usually one year after the initial stocking of bass) the pond is ready for fishing. As fish are removed, competition for food decreases, their growth rate increases, and the remaining fish reproduce to replace larger fish that have been harvested.
The rate at which fish are harvested must be controlled, especially during the first few weeks of fishing. When the fish population first attains a balanced condition, the total weight is comprised primarily of harvestable-sized adults (initial stock). Most of the remaining weight is composed of small (1- to 5-inch) fish that are offspring of the initial stock. Rapid harvest of adults can result in excessive numbers of small fish, which can lead to poor fishing.
A desirable yield from a properly managed pond is about 145 pounds of bream and 30 pounds of largemouth bass per acre per year. The catch should be distributed over the entire year rather than a few days or weeks. Therefore, an accurate record of the numbers and weights of bass and bream removed from the pond is very important. A set of weighing scales and a notebook should be readily available to anglers to log in their catch after each trip. Proper pond management requires an understanding of harvest, both above, and even below, recommended rates.Each pair of adult bluegill may produce over 5,000 offspring each season. Bluegill grow faster and spawn more abundantly when their food supply is increased. Therefore, a sudden removal of too many pounds of adult fish will result in accelerated growth and reproduction by the bream that remain. The outcome may be a population of stunted bream that are too small to be desirable.
The diet of adult largemouth bass consists almost entirely of small bream; therefore, the removal of bass must be controlled. If bass are caught faster than they are replaced by natural reproduction, the result can also be an overpopulation of small, stunted bream.