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INTRODUCTION Farm ponds contribute a significant portion to Iowa's water resource. There are 80,000 ponds statewide with an additional 1,000 being added yearly. Basically, most ponds are located in southern Iowa where the topography is best suited for their construction. Very few are found in the northern part of the state. Iowa's ponds reflect the fertility of its agricultural land. A pond in Iowa will support more fish than ponds located in most other states. Because of this high "carrying capacity" our ponds have the potential to provide outstanding fishing in both sizes and numbers of fish. Each year, personnel of the Iowa Department of Natural Resources are questioned repeatedly by pond owners and fisherman about proper procedures to manage a fish pond. This booklet was published to provide answers to those questions. Because each pond is different, additional help may be needed to solve specific problems. Contact the Iowa Department of Natural Resources concerning questions dealing with fish or wildlife resources and your local Natural Resources Conservation Service representative concerning questions dealing with soil, erosion, pond construction, and cost sharing. Life within a pond is a complex system with the various life forms dependent upon each other. Ponds contain minute single and multicellular plants called plankton. The microscopic plankton are eaten by crustaceans, insects, and tadpoles also living in the pond. Small fish, crayfish and frogs feed on the crustaceans and insects and in turn are eaten by larger fish. Bluegills, although they may grow to nine inches, feed primarily on insects throughout their lives, while bass feed on insects only in their early stages. As bass get larger, they become the major predator in a pond consuming fish, crayfish, and frogs. Each link in this web of life must be present for successive links to be present and survive. Man forms the final link in the chain by actively seeking and consuming fish caught from the pond. How man goes about managing the pond and its surroundings is the most important influence on that environment. POND CONSTRUCTION Pond Watershed: The best ponds in Iowa have about 20 acres of watershed for each surface acre of water impounded. Protected timber is preferred as watershed cover. Other suitable watershed covers include grassland and pasture. Rowcrop is the least desirable watershed because silt laden runoff shortens pond life and fish populations are drastically reduced. Livestock Watering: Ponds can be used for livestock watering if a small pipe (2 in.) is installed in the lower portion of the dam. The pipe should extend into the pond and connect with a standpipe, the top of which should be four feet lower than the water surface when the pond is full. A watering tank could then be placed below the dam and a float valve installed to keep a correct water level in the tank. Using a watering pipe and tank as opposed to allowing livestock access to the pond will provide cool fresh water to the livestock and eliminate livestock trampling the dam and pond banks. The pond and dam should be fenced. Pond Fencing: One of the most important aspects of building a pond is fencing to exclude livestock. Unfortunately, this is the most neglected part of construction and often is the cause of slow fish growth, unbalanced fish populations, lack of wildlife cover and shortened pond life. The fence should be constructed at least 60-100 feet from the pond edge and completely enclose the pond and dam. Fence construction should be adequate to exclude all livestock. Ponds without fences usually have the bank slopes and sod ruined by
livestock, thereby weakening the dam and spillway. Livestock wading into
the water will destroy fish spawning nests and will result in muddy water.
A grass buffer strip inside the fence will protect the pond retarding runoff,
thus allowing most silt and contaminants to settle before reaching the
pond. This strip will provide escape, nesting and cover for many wildlife
species.
STOCKING YOUR POND WITH FISH If you feel your pond meets the above criteria, contact your local NRCS office and sign-up for fish. A Department of Natural Resources employee may contact you to arrange an on-sight inspection of your pond. This contact will allow you an opportunity to obtain additional information concerning fish and wildlife management. The Department employee will discuss the potential of your pond and adjacent area for fish and wildlife and if the pond meets the minimum criteria, it will be approved for stocking. Owners of ponds approved for stocking will be notified by postcard, a minimum of 10 days prior to delivery of fish. The card will also indicate the date, time and location of the truck delivering fish and the gallons of pond water the owner or his representative will need to transport his fish. Bluegill and channel catfish will be distributed in October and the largemouth bass will be distributed the following June. MANAGING YOUR POND FOR FISHING Iowa ponds contain about 250 pounds of bluegills per surface acre of water; hence, this species will provide most of the fishing in a pond. Harvest of bluegills can be started the second year after stocking. Bluegill limits need not be imposed because they are plentiful. Bass populations in a balanced Iowa pond will reach 50-75 lbs/acre, approximately 1/5 that of bluegill. Bass should not be removed from the pond until the fourth year after stocking. No more than 15 bass/acre over 14 inches in length should be removed annually. Greater harvest rates will reduce the quality of both bass and bluegill fishing. Channel catfishing can begin three years after initial stocking. Harvest should not exceed 15 fish per acre. Other Species A list of private fish hatcheries in Iowa which sell fish is available from the Department of Natural Resources upon request. REPRODUCTION & GROWTH Bluegills play a dual role in Iowa farm pond management by providing most of the "take home" catch and also a major portion of the forage for largemouth bass. A bluegill rarely exceeds one pound in weight, but pound for pound it is the sportiest fish around. The average size caught by most anglers is 6 to 7 inches in length and 1/4 to 1/3 pound in weight. The average bluegill life span is about five years, but 13-year-olds have been recorded. Bluegills have a tremendous reproductive capacity and may become to numerous for their food supply, seldom growing too 6 inches when this happens. Bluegills reach sexual maturity at age one with a 4-inch female producing about 4,000 eggs. Spawning takes place from May through late August. Male bluegills construct nests (shallow depressions) in shallow water and drive a female to the nest to lay eggs. After fertilization the male guards the eggs and nest during incubation which takes 2 to 5 days. He continues to guard the newly hatched fry until the yolk sac is absorbed and the fry swim off. He then discontinues parental care.
The best stocking rates and schedule for Iowa farm ponds have been determined from numerous pond experiments. Bluegill fingerlings are stocked at 750 to 1000/surface acre in autumn. Rapid fish growth can be expected from these stocked fish in all new Iowa farm ponds. Bluegills stocked in the fall when they are one to two inches long will grow to 5 inches by the next fall. Two years after stocking they will average 6 1/2 inches long. Largemouth Bass The largemouth bass is the trophy fish in farm ponds and is also the major predator of young bluegill. A past state record largemouth bass, which was caught from an Iowa farm pond, was more than 24 inches long and weighed over 10 pounds. Under ideal conditions bass spawn in their second year of life, but most spawn in the third year of life. Male bass also build nests similar to bluegills, but the nests are larger. Spawning occurs in May and early June in shallow water. A female bass 10 inches long will produce about 2,000 eggs, but an older, larger bass can produce 15,000 eggs. Bass eggs usually take from 3 to 10 days to hatch and male bass provide parental care until the fry are about 10 days old, when parental duties are discontinued. Largemouth bass should be stocked into a new pond in June following the fall stocking of bluegill. They should be stocked at a rate of 70 fingerlings (1-2 inches) per surface acre. June bass planting assures heavy, predation on newly hatched bluegill, very rapid bass growth and control of bluegill populations. Largemouth bass fingerlings can be expected to reach 7 inches by October, although bass in ponds with good bluegill reproduction will often grow to 9 inches by October. In the second year, bass will average 10-11 inches, but some may reach 13 inches in length. Channel Catfish Channel catfish are regarded as bonus fish in Iowa farm ponds because they provide quality angling and their presence in farm ponds usually benefit the bass and bluegill populations. Channel catfish grow large in ponds with some individuals exceeding 15 pounds. Catfish become sexually mature when they are two years old, but most reproduction comes from older fish. A female produces about 4,000 eggs per pound of body weight. Spawning occurs in June when the male builds a nest similar to bass and bluegill, except it is usually more protected, and nudges a female to the nest. Male catfish also guard the nest and care for the young. Channel catfish seldom reproduce successfully in small ponds, which is the result of predation on the young by bass and bluegill. Catfish are stocked in the fall at the same time bluegill are stocked.
One hundred fish per acre are recommended which will grow from 2-inch fish
to about 8 to 11 inches one year later. Two years after stocking, channel
catfish should average 12 inches, with the maximum size about 16 inches.
Pond research has shown about 30% of the catfish population dies each year
and the population must be maintained by stocking 100, 8-inch fish per
acre every 2-3 years.
Ponds can be checked for a balanced fish population with a 30 foot seine or by fishing. Seine hauls should be made in mid-summer. Hauls that contain numerous small bluegill and some bass indicate an acceptable fish population. Seine hauls containing young bass, but no small bluegill indicate an undesirable population with no bluegill present. Stock 50-100 adult bluegill per acre. A population with no small bass, no small bluegill and with many green sunfish, bullheads, or tadpoles is also undesirable. The pond should be drained or chemically renovated and restocked with proper species. Rotenone for chemical renovation can be obtained from Department of Natural Resources field fisheries personnel. Another method of checking the balance of a fish population is through fishing. Fishing effort must be sufficient to sample the available species present in the pond or it will be inaccurate. Bluegill populations with many individuals greater than 6 inches are rare and ponds containing many small bluegill are undesirable. In a pond with too many small 3-5 inch bluegill, remove as many as possible. They can be seined or trapped out. A balanced pond will contain a bass population in which 45-60% of the bass larger than 8 inches are larger than 12 inches. A pond containing numerous bass less than 12 inches may not contain bluegill and they should be stocked. Overcrowded bass can be easily removed by angling. A pond that has a very large proportion of large bass (greater than 75%) is also out of balance. Large numbers of small bluegills have reduced the reproductive success of bass and no small bass are entering the population. Remove 3-5 inch bluegills by trapping or seining and stock 50 ten-inch bass per acre. HOW TO CATCH 'EM Bluegills are most susceptible to angling during the spawning season. Fish bluegill nests, but don't overlook the edges of weed beds, brush, or similar cover in the water. Bluegill can always be caught around brush and submerged tree limbs. Winter is an excellent time to fish for bluegills, although several holes may have to be bored in the ice before the fish, concentrated near the bottom are located. Once the bluegill are found, fishing action is usually fast. The best fishing gear for bluegill is ultralight tackle with 2 or 4 pound test line. The rod should be lightweight and flexible. A small hook, size 6 to 12, baited with a piece of worm, maggot, cricket, or small grasshopper should be fished with a tiny bobber and no weight. The bobber, usually 1/2 to 3/4 inch diameter, should be large enough to just float the bait. The bait should be cast beyond the spawning nest and retrieved slowly across the nests until a strike is felt then set the hook and hang on. Tiny jigs or weighted flies can be used by spin fishermen who prefer artificial baits. Another deadly gear for fishing bluegill is a properly used fly rod. Flycasting around weedbeds and brush with black flies, spiders, and tiny poppers provides great sport and large numbers of pan-sized fish. Ice fishing is a nice way to recreate during the winter and stock up on excellent tasting bluegill fillets. Ice fishing gear includes a small 5-or 6-inch diameter ice auger or spud, ice skimmer, 5-gallon bucket, two small ice fishing rods, and several teardrop lures, maggots or waxworm larvae for bait, and tiny bobbers. A teardrop lure baited with a white maggot or waxworm larvae should be fished 2 or 3 feet from the bottom. Tiny sponge bobbers work best because the ice can be quickly broken from the bobbers by squeezing. The bucket makes a nice chair while fishing and carries everything except the auger when walking. Bass Best bass fishing occurs in the spring and early summer. Live baits such as worms, frogs, crayfish, and minnows can be used, but artificial baits are often just as productive. The best artificial lures consist of plugs resembling natural bass food such as minnows, frogs, and crayfish. Many avid bass fishermen use only artificial lures and fish for sport rather than the tablefare bass provide. Hook sizes should be no smaller than size 1 and usually range up to 6/0. Heavier tackle may be needed in bass fishing to set the hook to "horse" bass away from snags or through the weeds. Most bass rods are medium to heavy action and line strength should be between 8-and 12-pound test. However, light or even ultralight tackle may be preferred, particularly in the springtime, when vegetation is at a minimum. Fish around tree stumps, brush, points jutting from shore and weed bed edges for these are the hangouts frequented by bass. Catfish Fishing for old whiskers in farm ponds requires different techniques than those used in rivers. Catfish naturally avoid light and because of their feeding habits they are usually found near the bottom, often in deep water. Mid-summer is the best time to catch channel catfish, although early spring fishing can be good. Tackle should be medium weight, although catching catfish on ultralight gear is exciting. Line strength should be 6 to 12 pound test and hook sizes should be from 1/0 to 4. Commonly used baits are prepared blood or stink baits, chicken entrails, liver , cut shad, crayfish, and earthworms. Still fishing in ponds is best, but if no bites are obtained in one place within 10 minutes, move to another spot. Cut shad is best during early spring fishing, while liver, chicken entrails, and prepared baits work better during mid-summer. Best results are obtained if baits are fished on or near the bottom using slip sinkers or no weight and an open bail or free spool reel condition. The idea is to present the bait as naturally as possible and provide very little resistance when the bait is taken. The hook is set after the catfish runs with the bait AQUATIC VEGETATION CONTROL  Excessive aquatic vegetation can quickly ruin fishing and upset the balance between bluegill and bass by providing too much cover for young bluegill. Insufficient bass predation will ultimately result in excessive bluegill numbers and stunting will occur. Vegetation control is necessary when aquatic vegetation covers more than 25% of the pond surface. There are four major types of aquatic vegetation. They are classified by their growing pattern or location. The major types are: 1) Algae are primitive plants without true leaves or flowers. Many are free floating by themselves, in clumps or strings. Pond scum and the pea soup scum are types of algae. 2) Free floating plants are those not attached to the bottom. They float on the water surface. Duckweed is a common example of this type. 3) Submersed plants usually are rooted to the pond bottom and grow to the surface. These plants grow into thick beds and are commonly called seaweed, moss, or bass weed. 4) Emersed plants root to the pond bottom and extend above water. Some of the more common emersed plants are bulrush, cattail, water lily, smartweed, and willow. A herbivorous (weed eating) fish species from Asia is the best method to control vegetation in farm ponds. Grass carp, a large vegetation eating minnow species have proven successful in clearing vegetation from ponds. In ponds bothered by excessive vegetation, grass carp stocked at a rate of 5-10 (10-inch) fingerlings/acre will eliminate rooted vegetation. Stocking at a lesser rate (e.g. two 10-inch fingerlings/acre) will control rooted vegetation, and remember that 25% vegetation coverage in a pond is good for fish. Grass carp must be purchased separately by the pond owner as the Department of Natural Resources does not stock this fish in private waters. Check this site for information concerning private fish hatcheries that sell grass carp. Grass Carp Ready for Stocking Many herbicides are available from commercial distributors that will control aquatic vegetation in farm ponds. Advantages of herbicides are: (1) they usually produce rapid results, (2) they are easily applied with a hand sprayer, (3) most chemicals can be purchased locally or at least in Iowa and (4) most chemicals are selective for a certain type of vegetation. Disadvantages of herbicides are: (1) results are unpredictable, (2) chemical control of vegetation is costly (up to $75/acre), (3) most chemicals require more than one application in Iowa ponds, (4) most herbicides must be applied in early spring when the plants are growing rapidly to be effective, (5) all are dangerous, (6) all require an applicators license, and (7) the weed must be identified correctly and the area to be treated has to be calculated. Most major herbicide manufacturers have distributors in Iowa. Check with you area fisheries biologist and/or farm chemical store for herbicides which can be used on Iowa ponds. Muskrat Damage: Muskrats can be discouraged by removing their food source. Cattails and other vegetation form much of this rodent's food. Mechanical or chemical means can be used to rid a pond of vegetation. They may also be driven from the dam area by placing 1/2 cup of creosote or mothballs in holes drilled at three-foot intervals along the face of the dam near the water's edge. The holes should be sealed shut with dirt after the creosote or mothballs have been added. Muskrats can also be removed by trapping during the trapping season. Muskrat trapping has provided spending money as well as fun and education for many. Seepage and Leaks: The best way to avoid these problems is to use proper dam construction techniques and avoid building a pond in area with exposed limestone or permeable soils. Pond dams with a well compacted clay core tied into existing clay substrate rarely leak providing burrowing animals are not allowed too penetrate the core. Repair of a leaky dam or pond bottom is often difficult and expensive and requires first draining the pond. A blanket of clay taken nearby or the addition of bentonite to the bottom will seal leaks. Washout: One major cause of dam washout is failure to place anti-seep collars several places along the length of the mechanical spillway. These collars prevent water from following the tube, creating a cavity through the dam and leading to dam failure. Another major cause of washout is improper size or placement of the emergency overflow spillway. An emergency spillway that is too small for the flood water going over it will quickly washout the dam. Placement of the spillway on newly placed and compacted soil may also result in a washout during high water. The emergency spillway should be constructed on undisturbed soil. Muddy Water: Turbid water in Iowa ponds many times is the result of cattle wading in the pond. Another cause of turbid water is the presence of carp or bullhead. They should be removed by draining or chemical renovation followed by stocking of the proper species of fish. Planting a larger buffer strip around the pond will also act as a filter and will remove much of the silt. Shoreline Deepening: Frequently, many future aquatic vegetation problems can be eliminated during pond construction by deepening shoreline areas. Often this could be done at little or no extra cost if borrow areas for dam material are taken from along the shoreline. These areas should be deepened so there is a slope of 3:1 down to a depth of 6 feet. Limit these steep shorelines to two thirds of the pond closet to the dam. Allow the remaining third shallow for fish spawning, nursery areas, and for other wildlife uses. RENOVATING FISH POPULATIONS IN YOUR FARM POND Rotenone is a fish toxicant that prevents gill tissue from absorbing dissolved oxygen from the water. It is not toxic to warm blooded mammals at concentrations prescribed for killing fish. Rotenone can be purchased either in powder form or as a liquid. The liquid is recommended because of its ease of application. Many things about your pond should be known before attempting renovation of fish populations. The pond surface acreage should be determined by visiting you local SCS Office and asking them to measure the area of your pond from aerial photos on file in their office. Average depth is needed to determine the total water volume. Average depth can be calculated by multiplying maximum depth by .4. Multiply average depth times the surface acres to determine volume in acre feet (one acre foot covers one acre one foot deep). Best results are obtained if the renovation is scheduled in August when water temperature is highest. Liquid rotenone should be used for pond renovation and should be applied at a rate of 3 ppm (parts per million). One gallon of the liquid per one acre equals 3 ppm. Let's say, for example, that you want to renovate your pond to remove an abundance of small bluegills and bullheads. A trip to the NRCS Office and a check of their aerial photographs proves the pond to be 2 acres and a quick test of the depth from a boat using a weighted line shows the depth to be 22 feet. Therefore, to calculate the number of gallons of rotenone you would calculate: Average depth = .4 x maximum depth or Average depth = .4 x 22 feet = 8.8 feet Volume = average depth x surface acres or Volume = 8.8 feet x 2 acres = 17.6 acre feet Therefore you would need 17.6 gallons of rotenone. Rotenone can be applied with the use of an outboard motor and boat. One method is driving around the pond in a boat and pouring rotenone slowly in the water near the outboard. Make more laps over the deeper water than over shallow areas. Continue to mix the rotenone and water with the outboard until all rotenone is applied. In a few minutes, fish will start swimming on the surface and die. Rotenone can be applied by another method , also with a boat and motor. Tie the boat between two steel fence posts in the middle of the dam. Tie the outboard in the center position, start, and run at maximum throttle, in forward gear. Run the outboard for 1/2 to 1 hour, to establish a circulation pattern and begin slowly pouring rotenone in propwash. Continue to mix rotenone and water after all rotenone is applied. Wait for the fish to surface and die. Allow the pond to detoxify for at least one month before restocking. Rotenone can be purchased in gallon quantities from a Department of Natural Resources district office. Address and phone numbers are listed below:
MISCELLANEOUS Fish Parasites: Fish like all other animals, are parasitized by other living things. A healthy fish can tolerate some parasites with little ill effects. The most common parasites in Iowa pond fish are black spot and yellow grub. The terms "wormy" or "grubby" are most frequently applied to fish infested with yellow grub. This parasite is found in both bass and bluegills. The yellow grub is enclosed in a cyst which frequently lies just beneath the skin. Many times a bulge is noticeable at the base of the fins or tail. The living worm when squeezed from this bulge is light yellow in color and about 1/4 inch long and 1/20 inch wide. Black spot consists of small, black grains embedded in the skin and flesh. These black spots are the home to a small fluke. They are found on several species of fish, but are very common on bluegill. Neither of these parasites have man as a host, and therefore are completely safe to eat. In addition, thorough cooking will kill both parasites. It is not practical to try to remove these parasites from a pond. Pond owners and fishermen must be resigned to the fact that occasionally they are going to catch a fish containing one of these parasites. Another problem sometimes found on fish in ponds is a fungus called Saprolegnia. This grayish, cotton-like growth is usually a secondary infection caused by some adverse environmental condition such as disease, low oxygen levels, or spawning stress. Many times it is seen on the tails, sides or bellys of fish which have rubbed these areas raw while spawning. Fish not too badly affected will recover, but some will die. Black Spot on Filet Yellow Grub on Filets Fish Kills: Three major types of fish kills affect Iowa ponds. They are summer kill, winter kill, and pesticide kills. Summer kills result when nutrient rich water enters the pond and a strong algae bloom results. A massive die off of algae sometimes occurs and the resulting decomposition causes a loss of oxygen and some fish die. Summer kills are seldom as drastic as winter kills and many fish populations will recover. The best prevention for summer kills is to have a watershed which is forested, pastured or in hay. Nutrient runoff is lower with this type of watershed than from crop land. Winter kills result when oxygen levels fall too low to support fish under the ice. This usually happens in shallow ponds which have large amounts of aquatic vegetation. As the vegetation dies and rots, it removes oxygen. Thick ice and snow aggravate the situation by reducing the amount of light entering the water. Light is needed for photosynthesis which produces oxygen. Winter kills are often severe enough to kill all of the fish present. Often if bullheads or carp are present they will be the only remaining fish. In such a case, renovate with rotenone and restock with bass and bluegills. The best prevention for winter kills is to maintain an area of open water during ice cover periods. DNR fisheries biologists can provide the necessary consultation regarding equipment needs. A third type of kill results when pesticides wash into a pond in heavy enough concentration to kill fish. This often happens in the spring following application of pesticides or ammonia to a crop field in the watershed followed by a heavy rain. Kills may be slight or complete. It may be necessary to wait several months before such a pond can be restocked. WILDLIFE BENEFITS Buffer strips adjacent to farm ponds will provide critical nesting, denning, winter and escape cover for wildlife. This cover can also greatly improve the quality of the water and add to the life expectancy of the pond by reducing soil losses from erosion. All requirements for wildlife and erosion control can be met when adequate areas adjacent to the pond are properly managed. One program of importance in both erosion control and wildlife nesting is the seeding of suitable areas to grass or legumes. Alfalfa-Brome is one of the best seedings. Similar benefits would be realized through the seeding of some of the native warm season grasses such as Switch grass, Indian grass, or Big bluestem, all of which are excellent for providing wildlife habitat. Other wildlife requirements can be met by planting trees and shrubs in the pond area. Conifers can be used to provide both winter and escape cover. Other medium-sized trees such as Autumn and Russian Olive provide cover as well as food. Shrubs provide many benefits including food production, both escape and winter cover, and provide excellent nesting areas for wildlife species. Planting should be carefully planned to provide the maximum amount of edge and cover diversity so wildlife can benefit. A Wildlife Management Biologist is located in your area and is available for technical assistance in planning for optimum wildlife habitat in the vicinty of your pond. Wildlife seedling packets as well as tree seedlings are available at low cost from the State Nursery to help establish wildlife cover. Wildlife habitat development may be cost shared through ASCS offices (ACP program).
1. NESTING COVER (Bluestem, Switch grass, Indian grass, Birdsfoot trefoil, Sweet clover, Alfalfa) 2. WINTER COVER (Juniper, Cedar, Pines) 3. ESCAPE COVER (Ninebark, Honeysuckle, Dogwood, Bush junipers, Elderberry, Raspberry) 4. SEED PRODUCING TREES (Russian olive, Wild plum, Mulberry, Osage orange) 5. MAST PRODUCING TREES (Walnut, Oak, Choke Cherry)
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Improper
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to Management- Releasing Most Bass
Bluegill Spawning Beds
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