Pond owners can encounter numerous problems when attempting to manage their ponds for fish production. Many of these problems can be prevented or at least lessened by proper planning prior to pond construction and in the initial stages of area development and fish stocking. While it is usually easier to prevent potential causes earlier than it is to treat symptoms later, the following information may help pond owners deal with established problems.
Pond water needs to be reasonably clear for production of desirable sight-feeding fish populations. Clear ponds produce several times the amount of fish as turbid ponds. Most ponds will be muddy after a heavy in-flow, but in good ponds silt should settle out within a week. Water clarity should be at least 1 foot or more during most of the year. If the underwater visibility is less than 1 foot, fish production will be decreased due to water turbidity. This amount of clarity is necessary for the production of algae, an important component of the food chain or web. In addition to limiting food production, muddy water can reduce the success of fish reproduction, particularly bass.
To cure the muddy water problem, the source of the turbidity should be identified. An easy way to determine the cause of turbidity is to collect a jar of water from the pond. If the suspended silt settles out within a week and the water above it is fairly clear, the problem is probably due to wind action or the activities of some animals such as livestock, fish like carp or bullheads, or crayfish. If after a week, the water in the jar still remains muddy, the problem is due to the chemistry of the soil type suspended in the water. Often, the problem is a combination of factors.
Muddiness Caused by Soil Type
This is the most difficult muddy water problem to cure. The turbidity is caused by the suspension of clay particles that repel each other and will not clump together to form a particle large enough to settle out. This problem can be treated by adding material which will cause these particles to clump together and settle out.
Agricultural grade gypsum (hydrated calcium sulfate), available from most fertilizer dealers, can clear colloidal clay problems temporarily. It should be scattered evenly over the surface of the pond at 12 pounds per 1,000 cubic feet of water or 525 pounds per acre-foot of water. An acre-foot is 43,560 cubic feet. To calculate the pond’s volume in acre-feet, the surface area of the pond should be measured in square feet and multiplied by the average depth of the pond in feet. This figure is then divided by 43,560. Some ponds built with Natural Resources Conservation Service assistance have acre-feet volumes calculated and on file. If the pond does not clear within four weeks and there is no other source of turbidity, one-quarter the original amount of gypsum should be added.
Another material that can be used to clear clay turbidity is aluminum sulfate (filter alum). This material will cause the clay to flocculate and settle out. An application of about 50 pounds per acre-foot of water will clear most turbid ponds within a week. Alum should be dissolved in water and then quickly sprayed over the entire surface of the pond on a calm day since wave action will break up the floc so it will not settle out. Alum as an acid reaction with the water. If the pond is acidic (low pH) or has very soft water, about 20 pounds of hydrated lime (calcium hydroxide) should first be added per acre-foot of water. Sometimes this liming will cause the clay to settle out.
Organic matter can also be added to water to settle clay particles. This treatment technique is preferred to the addition of gypsum or alum because organic matter increases the pond’s productivity rather than decreasing it. Organic matter provides food for desirable bacteria. As the bacteria break down the organic matter, by-products cause the clay particles to clumptogether and settle out. Manure, weeds, hays, and cottonseed meal will all work. When organic matter decays, oxygen is consumed. Too much organic matter can cause oxygen deficiency in the pond. If organic matter is added, it is best to use something that will decompose rather slowly, such as dry hay. It should be applied at a rate of two small bales per surface acre at 14-day intervals. The bales should be pulled apart and scattered in the shallow water around the pond. No more than 4 or 5 applications should be made per year. Solid bales can also be placed along the shoreline every 40 feet, just into the water.
The above mentioned methods are only temporary measures. These treatments will probably have to be repeated each year (usually at lower application levels) and after periods of heavy water inflow. Ponds with chronic clay turbidity may be best stocked with channel catfish and minnows, in which case treatment of turbidity is unnecessary. Artificial feeding is desirable in turbid ponds because little natural food exists.
Muddiness Due to Wind and Erosion
Strong Kansas winds often cause shoreline erosion and wave action which keep soil particles in suspension. The effect of wind can be minimized by the use of windbreaks and shoreline protection. A standard windbreak can be planted on the upwind side of the pond to dissipate the prevailing summer winds. If the dam is eroding badly, it can be protected with rock riprap or seeded shoreline vegetation. Erosion on the rest of the shoreline can be lessened by deepening the shoreline during construction, thus eliminating mud flats. Eroded shores and/or mud flats on existing ponds can be stabilized by planting a water-tolerant grass such as reed canarygrass or millet. Millet seed can be broadcast over the mud at 10 pounds per acre. Millet grows rapidly to form a dense cover but must be planted each year to maintain a stand.
Muddiness Due to Animal Activity
Livestock having access to a pond will trample shoreline vegetation and wade in the water, especially during the summer. These activities stir mud which can then be carried over the entire pond by wind and wave action. Livestock should be fenced out of a pond if production of fish is important. If livestock water is needed, a pipe through the dam to a tank below the dam will supply it. If this is not possible or feasible, all but a small corner of the pond should be fenced off. This limited livestock access will cause some muddy water, but less than if stock had access to the entire pond.
Fish such as bullheads and carp will cause water to be muddy because of their feeding activities. Removal or control of these species has been described previously.
A dense crayfish population will cause pond water to be muddy due to their burrowing and bottom feeding activities which stir up the bottom mud. The introduction of predatory fish such as largemouth bass or channel catfish will solve this problem. Ponds with a good population of predatory fish will not have crayfish problems.
All vegetation is not bad. A certain amount is needed for good fish growth and protection. In fact fish will benefit from more vegetation than anglers will typically tolerate. Plants produce food for many insects which in turn are eaten by fish. They also provide habitat for many fish food organisms and cover for small fish. Plants produce oxygen, protect the shoreline from wave erosion, and serve as feeding and nesting habitat for wildlife.
Aquatic plants can become so abundant that they interfere with fishing, swimming, and boating. Excessive vegetation can also provide too many hiding places for small bluegills so bass have difficulty controlling their numbers. This often leads to overpopulated bluegills. Periodic die-offs of dense vegetation, which usually occur after periods of cloudy weather, or when the water is muddy after a rain, or at the end of their growing season, can also threaten fish. Oxygen is consumed by bacteria that decompose dead plants. Low oxygen levels stress fish so they do not feed and grow, and often die (summerkills and winterkills). Decayed plant material also produces offensive odors and imparts undesirable flavors to water.
To control aquatic plants, it is important to know what type is causing problems. Aquatic plants can be grouped into four general categories: algae, floating plants, submersed plants, and emersed or marginal plants.
Algae: Algae are small plants which do not have true leaves or flowers. Different types of algae take on different forms. Microscopic, single-celled, free-floating algae are called phytoplankton. This form is used by microscopic animals (zooplankton) as food. Phytoplankton gives water a green to greenishbrown tint, but individual plants cannot be seen. Filamentous algae, commonly called “moss,” consists of masses of long, stringy, slimy or cottony strands which float on top or just under the surface of the water. Chara, commonly called muskgrass or stonewort, is a larger form of algae which grows on the pond bottom and has stem-like and leaf-like structures. It is often confused with flowering aquatic plants. Filamentous algae and Chara are usually considered undesirable.
Floating Plants: This group includes plants which have leaves that float on the surface and roots that hang down in the water without being connected to the bottom. Duckweed (Lemna) and watermeal (Wolffia) are common members of this group.
Submersed Plants: These plants grow under water, are rooted in the bottom, have stems, leaves, and produce seeds. These plants usually consist of a long flexible stem with clumps of narrow leaves along the stem. Some species have leaves that reach the surface which are a different shape than the lower leaves. Common examples of this group which occur in Kansas are pondweeds (Potamogeton), bushy pondweed (Najas), coontail Ceratophyllum), and water milfoil (Myriophyllum), and water buttercup (Ranunculus).
Emersed or Marginal Plants: Emersed or marginal plants are rooted in the pond bottom and have parts extending above the water’s surface. Shoreline plants are also included in this group. These plants usually occur in shallow water, but some species can grow out from shore, forming a thick belt of vegetation. Common examples of this group of plants are cattail ( Typha), bulrush ( Scirpus), rush ( Juncus), cut-grass ( Zizaniopsis), smartweed ( Polygonum), creeping water primrose ( Jussiaea), arrowhead ( Sagittaria), willow ( Salix), and cottonwood ( Populus).
If aquatic plants occupy more than one-third of the pond area, one of four categories of control can be considered. They are: preventative, mechanical, chemical, and biological.
Preventative: Prevention is always the best control method. Plants are common in ponds that have clear water, high fertility and extensive shallow areas. Plant problems can be minimized through pond construction. All shallow mud flats should be eliminated by digging the shore areas to at least 3 feet deep with a 3:1 slope. Existing ponds with extensive shallow areas can be dug deeper during periods of low water.
High fertility can cause a plant problem because nutrients can be channeled into plants. It is desirable to avoid rich sources of nutrients, such as runoff from livestock holding areas or septic tank drainage.
Mechanical or Physical: Vegetation around the shore can be controlled by hand pulling, cutting, or mowing. Hand pulling is effective for controlling cattails, willow trees and cottonwood trees while they are small. As they get larger, chemical control is needed. Most submersed plants can be partially removed by raking or by pulling a chain or cable through the pond between two tractors.
Submersed vegetation can also be controlled by shading with dark plastic screen, similar to screening used for shade in greenhouses. A large piece of screen should be weighted down on the patch of plants. This compresses and shades the plants and they die. After 2 weeks, the screen can be moved to a new area. The advantage of this method is that fishing, swimming and boating can take place over the screen.
All mechanical and physical methods are temporary and normally affect only a portion of the pond’s vegetation. They must also be used frequently during the growing season.
Chemical: It is important to identify the problem plants, since there is no all-purpose chemical for aquatic vegetation control. Different herbicides are effective on different types of plants. Since the status of chemical registration is always changing, specific chemical names will not be listed. Aquatic herbicides are available at most dealers that handle agricultural chemicals. County agricultural agents and district fisheries biologists can give recommendations on which specific chemical to use.
Chemicals are registered for specific uses. Directions on the label should be followed explicitly and precautions should be observed. Many chemicals have restrictions on the use of water for a period of time after application. With some chemicals, fish should not be eaten for a period after application, or livestock should not drink the water for some time. These restrictions will determine which chemicals can be used.
Most chemicals are applied at a certain dosage per acre-foot of water in the affected area. Volume of the area to be treated can be calculated as described previously in the “Muddiness Caused by Soil Type” section or obtained from the Natural Resources Conservation Service if they designed the pond.
Most aquatic herbicides will not harm fish if applied according to directions. They are most effective if applied during April or May as the vegetation begins to grow. If applied after May or if the growth is heavy, only half of the pond should be treated at a time. The second half of the pond should be treated 2 weeks later. If the entire pond is treated at once, bacteria decomposing the dead vegetation could consume all of the dissolved oxygen, resulting in a fish kill.
One chemical treatment per year is usually sufficient, but, in some cases, a partial treatment is needed later in the summer. Chemical control is only temporary and must be repeated almost every year. It is expensive but effective if executed properly.
Certain chemical dyes can be added to the water to shade out the plants. These also are temporary and they impart an unnatural tint to the water for a period of time.
Biological: The most effective form of biological control is use of the herbivorous fish, the grass carp. This fish is a native of the large rivers of China and Siberia. Grass carp are mobile, and often escape through emergency spillways with high water flow. When small, it feeds on small crustaceans and insects. As it gets larger, its diet consists almost entirely of aquatic plants. It prefers some plants more than others but will eat most submersed aquatic vegetation found in Kansas. It has a voracious appetite and grows rapidly. Grass carp should be stocked at a density of 5-15 individuals per acre in ponds with severe vegetation problems. If adult bass are present, the grass carp should be at least 10 inches long when stocked to avoid predation. Ponds with only a narrow belt of vegetation should not be stocked with grass carp because these fish will eliminate habitat bass and bluegills need. More and bigger fish can be caught from a boat in such a pond than would be taken from shore if no vegetation existed.
Since the grass carp is an exotic fish, its use is not recommended by some federal agencies. In addition, the fish is not permitted to be used by the public in some states. In Kansas, no such bans exist and grass carp are available from many commercial fish growers. However, Kansas law requires that only triploid (sterile) grass carp be stocked. District fisheries biologists can provide further information and suggestions.
Fertilization can be used to control aquatic plants, but as stated previously, it can cause oxygen depletion problems and is not recommended in Kansas. Ducks, geese, or swans have also been used to control aquatic plants. They are esthetically pleasing but can be messy.
It is discouraging to have a new pond fill with water and then see it go dry within a few weeks. Leaky ponds are common in some areas of Kansas, and almost all ponds will leak to some degree, especially new ponds. In Kansas, evaporation can be expected to range from about 4 feet per year in the eastern part of the state to about 6 feet per year in the west. Most evaporation occurs during the summer, especially in hot, dry, windy periods. During this time, about half an inch of water can be lost to evaporation each day. Water loss greater than this can usually be considered leakage. The pond owner can determine his pond’s leakage rate by measuring the water level drop with a marked stick during a period of cold or very humid, calm weather. Leaks in ponds may be the result of permeable sand, gravel, or fractured rock layers that either exist throughout the basin naturally or were exposed by construction. Improper bonding of the embankment to an impermeable foundation soil can also lead to leakage. Some ponds are constructed in areas where all the soil in the basin is permeable, so the leak cannot be pinpointed. Deeper ponds tend to leak more because of the increased water pressure on the porous areas. Techniques are available to seal the leaky and potentially leaky areas. Most sealing techniques are expensive and require considerable work.
If a small gravel or rock area is causing leaks, a bulldozer can be used to remove some of the problem material. The area can then be covered with a layer of soil high in clay (at least 10% clay) from some part of the basin. The added soil should be at least 1 foot thick and preferably 2 feet thick. This soil should be compacted as it is being deposited. A sheepfoot roller is recommended for serious leak areas.
Bentonite is a material that expands greatly when wet. Mixed with sand or permeable soil and water, it seeps into pores making an impermeable layer. Bentonite is usually applied at 1-2 pounds per square foot of pond bottom (more in areas over 1 feet deep). The dry powdered form creates a protective barrier when placed in a thin layer and covered with several inches of soil. Powdered bentonite can also be uniformly applied on the pond bottom and then mixed into the top 4-6 inches of soil with a disc and compacted. This method is quite successful in sealing a pond, but the seal can be punctured if cattle walk on the muddy pond bottom. A leaky pond which contains water can also be sealed by pouring a slurry of bentonite or spreading granular bentonite over the surface of the pond. This technique is usually not as successful as applying bentonite to the dry pond bottom because it is difficult to achieve an even application of the material. Bentonite is available from most feed mills or well drillers.
Trampling a pond basin with cattle or hogs will sometimes seal permeable soil. Livestock should be fenced into the pond area and fed in the dry pond basin for several months. The combination of many hooves and manure and waste feed being worked into the soil sometimes makes a seal. This is especially effective if the pond basin occasionally becomes wet. However, the pond could fill up before the basin has been completely sealed.
For ponds with rock 2 1/2 feet or more below the surface, organic matter can be used for sealing. The soil surface should be covered with about 6 pounds (dry weight) of livestock manure, straw, grass, leaves, or sawdust per square yard. An 8 inch protective layer of soil should then be placed over the organic matter. A biochemical reaction will take place between the soil and the organic matter to seal the basin.
Plastic membranes which can be placed over pond basins are available. They are expensive and must be protected from rupture. If livestock are present, their access to the pond must be prevented.
An emulsion of oil-soluble resinous polymers can be used to seal a pond without draining. The effectiveness of this material varies with condition and character of the soil, water, and climate, as well as manner of application. It is expensive and is toxic to fish, but a pond treated with polymers can be restocked within a few days after the water clears.
In the past, salt was used because sodium disperses clay particles, causing them to plug pores in the soil. It is no longer recommended because of possible water contamination.
Many ponds that are 20-30 years old have filled in so extensively that they are shallow with vast areas of aquatic vegetation. Ponds are temporary features on the landscape because they accumulate silt, debris, and decaying vegetation, eventually becoming marshes and even dry land. Although filling is inevitable, some measure can be taken to slow down the successional process.
If a pond is reclaimed that has received excessive amounts of silt from erosion, soil conservation measures such as terraces, grassed waterways, and minimum tillage should be implemented. Small dams can also be built just upstream from large impoundments to act as settling basins for silt.
Livestock trampling the shoreline can cause the pond’s banks and the dam to slough in. In addition to benefiting fish production, the practice of excluding livestock from the pond also increases the life of the pond.
Aquatic vegetation settles to the bottom when it dies. Part of it decays, but a considerable amount of residue remains on the bottom, filling a pond in over several years. Vegetation control slows this process.
Ponds that are filled in can be renovated, but the process is expensive. It is often easier to build a new pond if other good sites are available. If the pond is located at the only good site available, it can be deepened by dredging with a drag line. A cheaper method is to drain or pump the water out of the pond and let the bottom dry. If the bottom muck is too deep it will dry very slowly, and the pond will fill with water before the bottom gets a chance to completely dry. In most cases, it is best to break the dam with a back hoe down to a level below the pond bottom. After drying for about a year, the pond bottom should be firm enough for a bulldozer to push out the sediments. This material can be pushed out to the back side of the dam and the break can be patched and packed with clay soil. It is important to “stair step” both sides of the break from bottom to top and compact each layer of added clay separately. The pond side of the dam should also have a new layer of soil pushed up against it and packed to be sure the dam is resealed.
Fish populations commonly have high mortality rates. In some ponds, one-quarter to one–half of all fish present will die of natural causes each year. This mortality takes place throughout the year. Many fish succumb to predation. Fish dying from other causes are usually quickly eaten by scavengers, so dead fish are seldom seen. On some occasions in some ponds, noticeable mass mortalities of fish do occur. Once dead fish are seen, it is usually too late to do anything, but knowing the possible causes can sometimes help the pond owner prevent fish kills from recurring or at least reduce their severity.
A variety of chemicals are being introduced into our environment, and those used in agriculture can gain access into ponds. Some pesticides are extremely toxic to fish, and others are low in toxicity. Most herbicides used today have a low toxicity to fish, and most persistent insecticides have now been banned from use. Many of the currently used insecticides are short-lived, especially when exposed to water and are usually broken down and non-toxic by the time they get into ponds. Problems can, however, occur when someone carelessly sprays a pond while spraying a field, or when heavy rains wash pesticide-loaded silt into a pond immediately following application on a nearby field. Washing out a spray tank and equipment in a pond can also cause fish mortalities.
It is difficult to establish with certainty that a fish mortality was related to chemical use. Analysis of water samples is expensive and time consuming, and chemicals will break down by the time analysis is possible. Circumstantial evidence can be used in determining whether chemicals caused a fish kill. The pattern of mortality is usually the best clue. In a chemical poisoning, small fish die sooner than large fish, and all species of vertebrates including turtles and frogs are affected.
In addition to massive fish kills, pesticides can have longrange effects on fish production if sub-lethal dosages are continuous or repeated. Pesticides may affect food organisms; they may alter fish reproduction, or they may be an added stress, causing decreased resistance to low oxygen levels and diseases.
Fish kills are common during the winter in Kansas. Mass mortalities are noticed in late winter when ice cover disappears. This type of mortality is caused by oxygen depletion under the ice. A long period of snow cover on the ice is usual43 ly responsible for a winterkill. Ice is usually clear enough to allow sunlight penetration so that plants can produce oxygen, but snow cover greatly reduces the amount of light penetration so plants are unable to produce oxygen. Instead, there is a steady decline in oxygen due to the decay of organic matter and respiration by bacteria and other organisms. If snow persists long enough, complete oxygen depletion will occur. Winterkill ponds are typically shallow and have a high organic matter content commonly in the form of decaying vegetation or livestock wastes.
Winterkills can often be prevented by controlling aquatic vegetation and reducing the amount of livestock or other wastes that get into the pond. Water depth in Kansas should be at least 8 feet going into the winter to hold enough oxygen to carry fish through a normal period of ice cover. Ponds that rely on surface runoff should be built at least 10 feet deep in eastern Kansas and 15 feet deep in the western part of the state. Removal of even a strip of snow from the ice may prevent winterkill. Another effective way to prevent winterkill is to place an aeration device on the pond bottom or to install a water circulator to keep an area free of ice. Much of the water is then exposed to the air for oxygen absorption. Just cutting a hole in the ice is not effective since too little water gets exposed to the air.
Summerkills are massive fish mortalities which occur during the summer due to oxygen depletion. The chain of events leading to summerkills was described in the “Aquatic Vegetation” section. Fish mortality due to summerkill usually occurs early in the morning, at which time the dissolved oxygen in the pond is at its lowest level. The mortality pattern is different than occurs due to pesticide poisoning, with larger fish dying first and frogs and turtles not affected.
Summerkills can be prevented by keeping aquatic vegetation from becoming too abundant. Excessive nutrients should also be prevented from entering the pond. This will reduce heavy algae blooms. If a fish kill is beginning or about to begin (fish are gulping for air at the surface), heavy mortality can often be prevented by pumping fresh water into the pond or by installing an aeration device.
Summerkills are common in fish feeding programs where high densities of fish are crowded into small shallow ponds. The addition of the organic matter in the form of feed can deplete the oxygen content in the pond.
Diseases and Parasites
Fish are affected by a wide variety of diseases and parasites just like any other group of animals. Diseases can be caused by viruses, bacteria, or fungi. Fish are most susceptible to diseases in early spring when their resistance is low coming out of the winter. In most cases, mortality is not extensive in pond fish populations. Diseases are a greater problem where fish are crowded as in hatcheries and commercial operations. Disease diagnosis is difficult, and treatment is expensive and usually not feasible except in large investment situations such as fish farming.
Most fish will have at least a few parasites. Parasites may be protozoa, flukes, tapeworms, roundworms, leeches, or crustaceans. A healthy fish can tolerate some parasites and show no ill effects. It is difficult to rid a pond of parasites, since there are a variety of parasites that can be readily introduced from a variety of sources. The best way to keep fish populations healthy is to maintain good water quality and prevent overpopulation.
“Black spot” and “yellow grub” are the fish parasites people most commonly encounter. Black spot (or black grub) consists of small, round, black grains (about pinhead size) embedded in the skin and flesh. Sunfish and minnows are commonly affected. Yellow grubs appear as small yellow or white nodules under the skin and in the flesh, especially near the base of fins and the tail. These parasites are found in many species of fishes, but are most noticeable in largemouth bass. The yellow grub is an immature stage of a parasitic flatworm which has a complicated life cycle. The adult worms live in fish-eating birds such as kingfishers and herons. The eggs are expelled into the water and hatch, producing larvae which enter snails. They then undergo massive asexual reproduction and numerous freeswimming individuals are released. These penetrate fish and become embedded. This is the stage that is readily observed by anglers. When the fish-eating bird eats the fish, the grubs have a chance to become adults and complete the cycle.
Most fish diseases and parasites are specifically found in fishes and are not harmful to man, especially if the fish flesh is properly cooked before being eaten.
Identification of Damage
Muskrats damage ponds by burrowing into dams and banks to make dens, thus increasing the chance of seepage and erosion. Den openings are 4-6 inches in diameter and are usually near the surface, though in ponds with frequent water level fluctuations they may be in deeper water. In clear water, dens are usually visible, but in turbid water, they must be detected with hands, feet, or a pole. When ice appears, trails of bubbles and chewed vegetation will lead to active dens.
Beavers burrow into dams and banks, cut trees, and plug outlet tubes. Their work is conspicuous and they are extremely persistent. Bank dens are 12-18 inches in diameter and will be present whether a dammed lodge is present or not. In fall and winter, a pile of fresh cuttings will be evident near the lodge or main den.
Prevention of Damage
Muskrat damage is unlikely in ponds where the dam is sodded, ungrazed, and built to Natural Resources Conservation Service specifications. Hard clay should be used in construction to discourage burrowing. To control burrowing after it has begun, all muskrats in the pond should be trapped, and affected areas should be riprapped. Wire mesh or fencing can also be used, but these materials yield to corrosion after several years. If all muskrats are not removed, survivors will find a way to reopen their traditional burrows.
Beaver burrows are big enough to damage even well-built dams. Riprap will discourage initial burrowing, but all beaver must be trapped if burrows are to be sealed. If burrows break through the surface of the dam, the opening should be collapsed as far back as possible and filled with clay.
To keep beaver from plugging outlet tubes, the pond owner should string electrified fence wire around the tube and connect it to a fencer and battery. Wood or fiberglass posts should be used or the system will not work. After beaver have been shocked a few times, the power can be turned off until problems recur. Outlet tubes are easier to keep free of debris if they are covered with a heavy trash rack of welded metal which is periodically cleaned. “Chicken wire” should not be used, as it cannot be cleaned. To prevent cutting of ornamental trees, bases should be wrapped with 1/4-inch wirecloth or similar fence material. No effective repellent is commercially available.
Sustained population control is the best damage prevention method available for both animals. Small, stable populations of muskrats and beaver will do little damage. Pond owners should not wait until furbearers become overabundant before initiating control, because by then the damage has been done.
For most pond owners, the most feasible method of population control is to have a local trapper work the pond every year. Everyone, including the surviving animals themselves, benefit from this arrangement. The pond owner keeps the problems to a minimum; the trapper earns money for pelts, and the animals are kept within the capacity of the pond to support them. If the pond owner wishes to try trapping beaver and muskrats, he should contact the Kansas State University Extension Service or the nearest Department of Wildlife, Parks & Tourism office for detailed information on proper equipment and methods. These agencies can also provide names of trappers who are available to help with problems. If damage is severe, muskrats and beaver can be shot or trapped out of season provided a permit is obtained from the Department of Wildlife, Parks & Tourism. Pelts obtained out of season must be turned in to the area Natural Resource Officer. The pond owner may pay a trapper market value for fur that is turned in on a permit as incentive for him to work on problems.
Both muskrats and beaver can be live-trapped although equipment costs may be prohibitive. Beaver can be taken in suitcase-style Bailey or Hancock traps, and muskrats can be taken in wire box traps (Havahart type) that are set on a float made from two- by eight-inch boards. Poisons are not recommended for beaver or muskrats due to undesirable effects on non-target species (particularly fish). A permit is required for use of poisons, and these are seldom issued by the Department of Wildlife, Parks & Tourism.
When a pond owner discovers that his pond has crayfish, an image of a leaky pond comes to mind, followed by thoughts of how to eradicate them without harming the fish. Without much effort, crayfish can be managed to provide benefits for the pond owner.
Crayfish burrows rarely cause ponds to leak. Controlling crayfish in established ponds is best done by stabilizing the water level. Crayfish reproduction is closely tied to changing water levels and is most successful in waters that have regular seasonal fluctuation patterns. Wire basket traps or lift nets baited with meat can remove large numbers of these crustaceans in short periods of time.
Having crayfish in a pond isn't all bad. In the process of eating minute plants that grow on submerged vegetation, crayfish also eat larger pond plants, giving limited vegetation control. Since crayfish are consumed as prey throughout their lives by bass, bluegills, and channel catfish, they also provide benefits as a fish food. Catching crayfish using a rod can sometimes be as much a sport as angling for fish. Substituting crayfish for crab, shrimp or lobster in recipes offers an excellent table fare for a fraction of the cost.
Most pond owners and anglers view turtles as a threat to fish communities in ponds. Such is not the case. Turtles are primarily scavengers, feeding on dead or dying fish and other aquatic organisms. They thus serve to clean the pond more than cause harm, and should not be indiscriminately destroyed. Turtles may cause problems by stealing bait and even fish from stringers. Snapping turtles may also prey on small ducks that hatch around the pond.
If the pond owner enjoys turtle soup, stew, or fried turtle, or if turtles become too plentiful, they can be removed by trapping. An effective trap can be constructed by attaching a hardware cloth or “chicken wire” bottom to a square, four-board wood frame. A slanted board is then nailed to the outside of the trap, leading to the top edge. It serves as a ramp on which the turtle can crawl out of the water to the trap. A metal rod is driven horizontally through two of the frame boards. The rod is also passed through another “teeter” board which extends from the edge of the trap to near the middle. When the turtle crawls to the end of the board, his weight will tip it forward and he will fall into the trap. A tough piece of fresh beef or pork should be suspended in the middle of the trap for bait. To keep the turtle in the trap 20 D nails should be driven into the frame, slanting upward, 4 inches apart, 2 inches above the water.
Frogs need water to reproduce. Masses of gelatinous eggs are often found in pond water during spring and summer. In Kansas, the bullfrog is the only common species that has a tadpole stage lasting longer than a year. All others will develop into tiny frogs the same season the eggs are laid. These amphibians are an interesting addition to the aquatic ecosystem, but they usually do not substantially help or hinder the fish community. The adults are quite mobile and often leave the pond. Bullfrogs, however, will take up residence by a pond and can usually be seen sitting on the edge of the water. Frog legs are tasty, and frog harvest during the legal season is another benefit of a pond.
Frogs seldom are a problem because bass and other predators usually keep populations low. Bullfrog tadpoles can become a problem in channel catfish-only ponds or minnow ponds because they can become abundant. Excessive numbers of tadpoles can be reduced by seining, and the adults can be eliminated by capturing them during the legal frogging season.