No two ponds are alike, and with present knowledge, it is impossible to predict the amount of harvestable crop in ponds. However, certain practices can make the difference between a good harvest and a poor one. To provide good fishing, your pond should contain between three and six pounds of forage fish (bluegills, redears, or minnows) for each pound of bass. Of these, about one pound should be small enough for the bass to eat. This means forage fish of 2.5 inches or less for the average bass.
Sixty to 85 percent of the total weight of fish in a pond should be harvestable size. A bluegill or redear is considered harvestable when it is five inches long, and a bass 12 inches. Ohio ponds that are well managed should produce an annual harvest of 50 to 100 pounds or more per acre.
Here are some practices to increase the chances of good fishing.
Feeding is not necessary to manage the fish population; however, the growth rate of some pond fishes may be accelerated through the introduction of additional food. Several animal food manufacturers offer fish-food pellets for sale. Such foods may be used to feed trout, catfish, bluegills, and redears. Pelleted fish foods should be fed sparingly at first. Feed only as much as the fish will eat at one time. Be careful not to use too much food as unused food may accumulate on the bottom where it will decompose and increase the risk of a fish kill. Feeding catfish and forage fish may result in larger fish but not necessarily better fishing. Bass do not take pelleted food readily.
Any good angler will tell you that the best place to catch pond fish is around structures such as docks, submerged stumps and logs, and at the edges of weed beds. Pond fish use "structure" for a number of things. Forage fish hide in it to escape predators; they also feed on animal organisms such as snails and aquatic insect larvae found on the structure. Finally, most fish seek shaded, darkened areas during hot, sunny days.
Because living plants such as submerged and emergent aquatic plants are usually hard to limit and spread rapidly, don 't leave weed beds to provide structure. Non-growing structures such as bundles of tree branches weighted and submerged in five to six feet of water make good structure, as do piles of large rocks or several old tires wired together.
Discarded Christmas trees can also be used to provide structures for fish. Use wire and a concrete construction block to anchor the tree, and then group three to five trees in six to eight feet of water. Another method is to stand the tree in the center of an old tire, then fill the tire with concrete. The easiest method for submerging trees in a pond is to place them on the ice during the winter and let them sink when the ice melts.
Fishing over and around structures often will produce results when you cannot catch fish elsewhere, although fishing lures may become snagged on structures and lost. The location of structures should be marked so swimmers and boaters can avoid them. (For more information on structures, see Placing Artificial Fish Attractors in Ponds and Reservoirs, OSU Extension Natural Resources Fact Sheet A-1).
Several indicators can be used to monitor the balance of your fish population. A decline in fishing success may, but does not always, mean an unbalanced population. Observing the condition of fish you catch also can be an indicator. Are they healthy and full-bodied, or are they skinny and "bug-eyed"? If few bass are caught and forage fish are small, this, too, may indicate a problem. An absence of bass on spawning beds or new hatches of bass also may suggest a problem. The survival of large numbers of tadpoles is often an indicator of a low bass population.
A scientific way to determine the population balance in the pond is to sample it with a seine. Seine shallow water areas between July 1 and September 1 for an indication of the spawning success of your fish. Using a seine four feet wide and at least 12 feet long with a mesh no larger than 0.5 inch, make several sweeps in shallow areas of your pond. After each sweep, look at the contents of the seine. If the seine contains current reproduction of both bass and forage fish and some intermediate forage fish (2.5 to 4.5 inches), the pond is in balance and producing satisfactorily.
After July 1, any bluegill or redear less than one inch long has hatched that year. Fingerling bluegills and redears can be distinguished from fingerling bass by their deep body form. Bass have a more streamlined shape and a faint dark line running lengthwise along each side.
Your pond is over-populated by forage fish if the seine contains many intermediate-sized and some fingerling forage fish, but no bass fingerlings. Techniques discussed later in this section (see page 15) may be used to restore balance. If the seine contains mostly small intermediate-sized forage fish (three inches or less) and no fingerling bass or forage fish, your pond is unbalanced. Complete eradication of the fish population and restocking may be necessary to correct such a problem. For ponds that are forage-fish heavy, imposing a ban on bass harvest and the stocking of 20 to 30 bass, six inches in length or longer, per surface acre may correct the problem.
Do not be concerned if you do not catch large fish when you seine sample your pond. Larger fish will swim out of the seine. We are interested only in the smaller fish when using this method for determining population balance.
Note: It is unlawful to transport oversized seines (greater than four by eight feet) off the property on which the pond is located. For information on transporting oversized seines, contact your ODNR county wildlife officer. Your county Extension agent or sheriff can help you locate this person.
If observations or seine sampling indicates that your fish population is out of balance, you can try several methods to correct the problem. The first is to regulate harvest. Enforcement of a minimum length limit on bass harvested of 12 to 14 inches may help. You may even want to ban all bass harvest for a season. Encouraging forage fish harvest with all bluegills and redears caught being kept also may help.
The use of larger seines (at least 20 by four feet with 0.5 inch mesh) also may be used to reduce forage fish populations. Ponds should be free of obstructions such as stumps, brush, and large rocks. To seine the pond, make sweeps with the seine ending with moves to the shoreline. Lift the seine onto the bank, immediately remove all bass and large forage fish and return them to the water. Dump small forage fish on the bank or into containers for later disposal.
Fish traps can be used to accomplish the same thing as seining. These are commercially available, or you can build your own. To build a fish trap, use 0.5 inch mesh welded or woven wire or hardware cloth. The body of the trap should be cylindrical and about two feet in diameter and five feet long. Close one end of this cylinder with a cone made of the same wire and pointed away from the body of the trap. Construct a second cone or funnel with a 2.5 inch opening at the small end and attach this, point in, to the open end of the trap. Finally, cut an opening into the body of the trap and construct a trap door to cover it.
Bait fish traps with soybean or cottonseed cake, bread, or other foods that disintegrate slowly in water. Cottage cheese in a cloth mesh bag suspended inside the trap also will attract fish. Place the baited trap in two to four feet of water with the long axis parallel to the shoreline. Traps should be checked daily and desirable fish released and forage fish removed for disposal. Several traps may be used per acre depending on the number of fish you wish to remove.
It is impossible to be exact about how many small forage fish to remove. You will have to experiment in your own pond to determine when you have reached the right amount. With an overabundance of forage fish, removal of 50 to 100 pounds per acre may be necessary to reduce the numbers to a level where the bass can control them.
When seining or fish traps are not practical as population reduction methods, the forage fish population may be reduced using a fish toxicant. Rotenone, long used as an insecticide, is a common ingredient in fish toxicants. Read and follow label directions for proper use of fish toxicants. Rotenone is a restricted-use pesticide. You must be licensed to purchase and use it. The information provided here is intended to clarify and supplement that which is found on the product label.
In situations where the intent is to reduce, but not eliminate, the fish population, usually no more than half the shoreline should be treated at one time. The maximum safe length of shoreline to treat in a one-acre pond is 400 feet, 300 feet in a 0.75-acre pond, and 200 feet in a 0.5-acre pond.
Water temperature influences the effectiveness of rotenone. It acts more slowly at lower temperatures. Do not use rotenone when water temperatures are below 60 degrees F.
Treat the pond at midday on a clear, sunny day with no wind and no prospect of a weather change. Under these conditions, most bass will be in cooler water and will be outside the area to be treated. On a windy day, you will be unable to control the rotenone and some of it may spread into deeper water, killing large fish. You may treat the leeward side of the pond with some safety if there is only a slight breeze.
Mix powdered rotenone with just enough water to form a stiff paste, or mix the emulsified form with about twice its volume of water. Next apply a line of the rotenone under the surface following the shoreline of the pond 10 to 15 feet out from the bank. The rotenone will settle downward and mix with the water on each side of the line of application. Most of the fish between the line of rotenone and the bank will be killed, while those outside the line are likely to move away. If weather conditions are right and care is taken with this method, only small fish will be killed.
Rotenone kills fish by affecting the gills and reducing their capacity to remove oxygen from the water. The end result is suffocation. Moderate amounts of rotenone are not harmful to warmblooded animals. The small amount of rotenone added to the pond in a partial treatment will mix with the total volume of water in the pond in 8 to 12 hours. After that time, water from the pond may be used as before the treatment.
It is difficult to know the poundage of fish killed by a partial rotenone treatment. Two or three treatments at intervals of a week or 10 days should correct a situation where forage fish but not bass were reproducing and where there were moderate numbers of intermediate forage fish.
When a pond is overpopulated with stunted forage fish and neither bass nor forage fish are reproducing, removal of part of the fish population will seldom solve the problem. Complete elimination of all fish and subsequent restocking is recommended. Complete elimination of all fish is also recommended when undesirable fish are in the pond.
Draining the pond will allow you to save the desirable fish. Some ponds are constructed with a drain. Others may be siphoned using sections of fire hose, or they may be pumped down with a high-capacity pump such as that used for irrigation.
Commercially available fish toxicants contain complete directions on the label for total population elimination. Rotenone is a common ingredient in fish toxicants. Read and follow label directions for proper use of fish toxicants. Rotenone is a restricted-use pesticide. You must be licensed to purchase and use it. The information provided here is intended to clarify and supplement that which is found on the product label. Five percent rotenone applied at the rate of two pounds per acre-foot of water, or five percent emulsion at the rate of 1.3 pints per acre-foot of water, will eradicate fish in waters with temperatures above 60 degrees F. To determine the volume of your pond in acre-feet, see the "Pond Measurements" section.
Small ponds may be treated entirely from the shoreline. In ponds larger than one-half acre, apply the fish toxicant from a boat to get better mixing and distribution. An outboard motor will be helpful on large ponds. Collection and disposal of larger fish killed in population eradication is recommended to reduce odor problems.
A pond that has had the population eliminated with a fish toxicant usually can be restocked within 10 days to a month. To make sure all of the toxicant has decomposed, place some minnows in a screen wire cage or a minnow bucket liner in the water. If the minnows live for four days, the water is safe for restocking. Follow the suggestions in this bulletin when restocking