Managing Wisconsin Fishponds · Managing Wisconsin ... response to the growing interest in managing...

1

William Swenson

Stanley Nichols

Scott Craven

Jeff Malison

Thomas Thrall

Susan Marcquenski

Jim O. Peterson

G3693

Managing Wisconsin Fish Ponds

About this publication

This publication was written inresponse to the growing interest inmanaging ponds for both recre-ational and commercial fishing. Its

purpose is to provide a source of reli-able, up-to-date information for thoseinterested in building new ponds or man-aging existing ones. The referencesection is designed to serve as a guideto the vast body of information thatdeals with fish pond management. Thispublication replaces Wisconsin FarmFish Ponds published by the Universityof Wisconsin–Extension in the late1960s.

Throughout this manual we explainprocesses and principles for you tochoose from, rather than specific man-agement practices that you must follow.Adapt the information here to your ownspecific interests and needs, and use itas a guide for planning pond construc-tion and management for either sport orcommercial aquaculture. Most of thegeneral information here focuses onsport fishing ponds, but the sections onponds and fish management apply toboth sport and commercial pond aqua-culture (Chapter 9 deals specifically withcommercial pond aquaculture).

Whether your pond is a commercialenterprise or is used for recreation, ourhope is that this manual will help youachieve better results.

The authors

AcknowledgmentsMuch of the information in this publica-tion is based on Managing MichiganPonds for Sport Fishing, Third Edition,1994, (Michigan State University BulletinE-1554) written by J.D. Schrouder, C.M.Smith, P.J. Rusz, R.J. White, D.L.Garling and G.R. Dudderar. All graphicsand material that originally appeared inthe Michigan bulletin are used with per-mission. We gratefully acknowledge thecontribution of our Michigan colleagues.

chapter 1Overview . . . . . . . . . . . . . . 1

The resource . . . . . . . . . . . 1

When is a pond a “success”or “failure”? . . . . . . . . . . . . 1

Caution! Are you sure you want a pond? . . . . . . . . . . . . 2

Natural and artificial ponds . . . . 2

chapter 2 General considerations . . . . . . . 3

Goals . . . . . . . . . . . . . . . 3

Investigate and plan . . . . . . . 3

Management overview . . . . . . 4

Commercial aquaculture . . . . . 4

Meeting state environmental regulations . . . . . . . . . . . 4

chapter 3 Designing and building ponds . . . 5

Types of ponds . . . . . . . . . . 5

Water depth . . . . . . . . . . . . 6

Water supply . . . . . . . . . . . 6

Designing for control of aquatic plants . . . . . . . . . 7

Safety . . . . . . . . . . . . . . . 7

Wildlife pond/fishing pond system . . . . . . . . . . 7

Surface area . . . . . . . . . . . 7

Landscaping and erosion control in the pond’s surroundings . . . 7

Construction of excavated or dug ponds . . . . . . . . . . . 8

Construction of impoundments . . 8

Construction of levee ponds . . . 9

chapter 4 Ponds as places for fish to live . . 11

Basic pond characteristics for fish production . . . . . . . . 11

The pond ecosystem . . . . . . 11

Consequences of overenrichment . . . . . . . . 15

Facts about water and the chemicals dissolved in it . . . 15

Pond breathing, circulation and stratification . . . . . . . . . . 16

Investigating a pond’s suitability for fish. . . . . . . . . . . . . 17

chapter 5 Types of fish to raise in Wisconsin sport fishing ponds . . . . . . . . 19

Coldwater fish . . . . . . . . . . 20

Warmwater fish . . . . . . . . . 21

Forage fish. . . . . . . . . . . . 24

Fish not recommended for Wisconsin ponds . . . . . . . 24

Exotic species . . . . . . . . . . 25

chapter 6 Implementing pond management . 26

Keeping records . . . . . . . . . 26

Selecting the best fish for the pond . . . . . . . . . . . 27

Where to get fish for stocking 28

Anticipating fish management activities and costs . . . . . . 28

chapter 7 Managing coldwater ponds for sport fishing . . . . . . . . . . 29

Stocking . . . . . . . . . . . . . 29

When to start fishing and how much to harvest. . . . . . . . 31

Supplemental feeding . . . . . . 31

Special aquatic plant control in trout ponds . . . . . . . . . . 32

chapter 8 Managing warmwater ponds for sport fishing . . . . . . . . . . 33

Selecting the right fish species . . . . . . . . . . . . 33

Stocking . . . . . . . . . . . . . 33

Angling harvest . . . . . . . . . 35

Not recommended: higher stockinglevels and fish feeding . . . . 36

Pond fertilization and liming . . . 36

Emergency aeration of the pond 36

contentscontents

chapter 9 Managing ponds for commercial fish production . . . . . . . . . . . 37

General considerations . . . . . 37

Planning . . . . . . . . . . . . . 37

Water temperature and species selection . . . . . . . . . . . 40

Site selection . . . . . . . . . . 41

Pond design and construction . . 42

Managing for different types of fish . . . . . . . . . . . . . 42

Water quality and harvest . . . . 43

chapter 10 Fish population control . . . . . . 45

Angling intensively . . . . . . . . 45

Stocking predators. . . . . . . . 45

Destroying spawning beds . . . 45

Seining. . . . . . . . . . . . . . 45

Live-trapping . . . . . . . . . . . 47

Electrofishing . . . . . . . . . . 47

Drawing down the water level . . 47

Fish toxicants . . . . . . . . . . 48

chapter 11 Aquatic plants and their control . . 49

Kinds of plants . . . . . . . . . . 49

Algae . . . . . . . . . . . . . 50

Submergent plants . . . . . . 50

Floating plants . . . . . . . . 51

Emergent plants . . . . . . . 52

Pond plant biology . . . . . . . . 53Managing the growth of nuisance plants . . . . . . . . 54

Physically disrupting and removing plants . . . . . . 54

Deepening the pond to control vegetation . . . . . 56

Water level drawdown . . . . 56

Discharging selectively . . . . 57

Flushing and diluting the pond 57

Inactivating phosphorus . . . 57

Aerating the pond. . . . . . . 57

Sealing and blanketing the pond bed . . . . . . . . . . 57

Shading or coloring the water 57

Herbicides and algicides . . . 58

Biological control. . . . . . . . . 59

chapter 12 Wildlife around the pond. . . . . . 63

Controlling wildlife problems. . . 63

Wildlife control considerations . . 63

Problem species . . . . . . . . . 64

Muskrats and woodchucks . . 64

Beavers . . . . . . . . . . . . 65

Otters . . . . . . . . . . . . . 65

chapter 12 (continued)Moles . . . . . . . . . . . . . 66

Birds . . . . . . . . . . . . . 66

Turtles and snakes . . . . . . 67

For more information or on-site assistance . . . . . . . . . . 68

Other problems . . . . . . . . . 68

Swimmer’s itch . . . . . . . . 68

Mosquitos . . . . . . . . . . . 68

Leeches. . . . . . . . . . . . 68

chapter 13 Fish health management . . . . . 69

Factors influencing fish health . . 69

Managing fish health . . . . . . 69

Introduction to common fish parasites and diseases . . . . 70

Parasites . . . . . . . . . . . 70

chapter 14 Pond safety and liability . . . . . . 72

Installing a rescue station . . . . 73

chapter 15 Regulations . . . . . . . . . . . . 74

Pond construction regulations . . 74

Registration as a tool to regulate pond management . 75

Permits as a way to regulate pond management . . . . . . 75

Liability. . . . . . . . . . . . . . 75

chapter 16References . . . . . . . . . . . . 76

Major sources of information . . 76

General . . . . . . . . . . . . 76

Commercial aquaculture . . . 77

Videos . . . . . . . . . . . . . . 77

Further reading . . . . . . . . . 78

Pond planning and construction . . . . . . . . 78

Pond fishery management . . 78

Prospects for commercial aquaculture . . . . . . . . 78

Life in ponds (General—identification of organisms, biology, ecology) . . . . . . 78

Identification of fishes. . . . . 78

Identification of aquaticinvertebrates . . . . . . . . 78

Identification of aquatic plants 79

Nutrient over-enrichment and aquatic plant problems/control . . . . . . 79

Wildlife damage control . . . . 79

Fish health . . . . . . . . . . 79

Pond management . . . . . . 79

Overview

This publication provides an overviewof ponds as aquatic systems andtells how to manage ponds toachieve different goals. It is

designed primarily for current orprospective pond owners with an inter-est in sport fishing, but it is also valuableto those interested in commercial pondaquaculture. Chapter 9 provides anintroduction to this topic and much of thematerial from other sections also appliesto commercial enterprises. Those inter-ested in managing ponds for waterfowl,swimming or irrigation, where fish pro-duction may be a side benefit, will alsofind this publication useful.

Another of the publication’s main goalsis to help pond owners achieve betterresults from their ponds, and to aidaspiring owners in understanding apond’s potential and problems beforethey commit to building or buying one.

Though the emphasis here is on pondmanagement under typical Wisconsinconditions, much of the information alsocarries over to other areas of the northcentral United States.

The resourceApproximately 15,000 inland lakesprovide Wisconsin with roughly 1.27million acres of surface area. Portions ofLakes Michigan and Superior lie withinWisconsin’s boundaries as well, addingnearly 8.5 million acres of water to thestate.

In spite of the many lakes and easyaccess to fishing in public waters, manyprivate landowners want their ownponds. Having your very own fishingspot, close at hand on the farm or vaca-tion property, or even in a suburbansetting, offers convenience andcontrol—though not without cost andadded responsibilities.

Interest in commercial fish production isincreasing in Wisconsin due in part tothe growing demand for fish, a decline inproduction from wild stocks andimproved opportunities for diversifiedaquaculture brought about throughresearch. The management and educa-tional challenges involved in owning apond also attract many people.

Many ponds are constructed primarily forsport fishing. Other reasons to build apond include commercial aquaculture,swimming, wildlife habitat, water for live-stock, irrigation, hunting dog trials, fireprotection, water quality improvementand scenic enhancement. If a pond isdesigned and managed for anotherpurpose, do not expect it to provide thesame fishing quality as one designedspecifically for fishing. For example, apond that provides good duck habitat

chapter I chapter I

may be too shallow and choked withplants to provide enough oxygen for fishduring hard winters.

How does a pond differ from a lake?The fact is that there are no sharp differ-ences between the two. Most peoplethink of a pond as being smaller than alake, but opinions vary on what sizeconstitutes a pond. This publicationdeals primarily with ponds that range insize from a quarter acre to 10 acres (0.2to 4 hectares).

Regardless of their size, sport fishingponds often provide a few years of goodfishing when new or renovated; fishingoften deteriorates as fish populationschange. Occasionally, ponds may bedismal failures right from the start,usually because of faulty design,improper location or poor water quality.

When is a pond a “success”or “failure”?In commercial pond culture, profit is typi-cally identified with success. However,the level of profit and other rewards con-sidered “successful” varies with eachowner. An owner’s or user’s level of sat-isfaction is the ultimate measure of apond’s success.

Much of this publication is geared to themany pond owners and users who aren’tsatisfied with their fishing success. But ifthe fishing in your own pond doessatisfy you, enjoy it, and don’t pay muchattention to someone else’s idea of whatmakes a successful pond.

Because satisfaction is a matter of per-sonal preference, we try not to tellowners and users what kind of pond ormanagement is the “right” kind. Instead,we explain principles and describe alter-natives from which you can choose.

Caution! Are you sure youwant a pond?Creating and managing a pond requiressubstantial time, effort and money. Inaddition, there are some risks involvedsuch as potential legal liability frominjuries or drowning. Another problemcan be an overabundance of aquaticweeds. Trying to prevent or controlweeds can be frustrating, but we offerinformation here to make the job easier.

Maintaining a prime fishing pond is likestriving to keep a racing car in goodcondition. Performance depends onattention to details. You need to askyourself: Do I really have time for this?

Natural and artificial pondsThe landscape contains many pondsthat have formed naturally. Most often,these ponds have marshy, graduallysloping edges, and are only a few feetdeep at their deepest points—notenough to maintain good fishing, but finefor wildlife. Marshy or swampy pondscan be extremely enjoyable just for theirsights and sounds, and sometimes forthe hunting they offer. If they providesome fishing, it’s a bonus. If a naturalpond is deep enough (15 feet or more)to furnish proper habitat for a flourishingfishery, the owner is fortunate indeed.Many shallow ponds are suited for pro-duction of fish bait or fingerling gamefish.

This publication can help you increasefish production from a natural pondwhether it has high or low potential.However, we caution owners that radicalmanagement, especially in the form ofreshaping the basin or altering plant lifeto benefit fish, may destroy some wildlifehabitat or damage other valuable fea-tures. Natural ponds are often protectedby state laws to preserve the wildlifevalues of wetlands.

The artificial pond, designed for maximalsport fish abundance and minimummaintenance, is quite different from mostnatural ponds. It has steeply slopedbanks, an average depth of more than8 feet, and a maximum depth greaterthan 15 feet, no matter what the surfacearea.

2M A N A G I N G W I S C O N S I N F I S H P O N D S

General considerations

Good fish pond management involvesmore than just putting in some fish.Ponds, like gardens, need properdesign and management. Just as in

gardening, many questions must beanswered before management can beeffective. Some of the important ones are:

■ What is my goal in having the pond?Fishing? Profit? Swimming? Wildlife?Irrigation? Water for livestock?Nature study? Scenery?

■ If there are several goals, which isthe main one, and how do the othersrank in priority?

■ What, roughly, is the pond’s potentialfor producing fish in terms of space,water fertility and other aspects ofpond quality?

■ How deep should I build (or rebuild)the pond?

■ What kind(s) of fish should I stock?What sizes? How many? When?

■ When can I start fishing (or harvest-ing) the pond?

■ How many fish should I expect to beable to harvest each year and atwhat sizes?

■ How can I prevent or remedy fishoverpopulation and stunted growth?

■ How can I prevent or control aquaticweeds and algae?

■ Am I willing and able to spend thetime, money and effort needed toachieve the results I want?

GoalsLack of a clear goal is often at the rootof unsatisfactory pond construction andmanagement. Changing goals frequentlycan also be a problem. Select and worktoward a single primary goal based oncareful assessment of a pond’s poten-tial. Write down your goal and keep sightof it. Stick to it long enough to seewhether it works.

Satisfactory fishing is undoubtedly aprimary goal, or at least a secondaryone, for many pond owners. Write thisgoal down in terms of the kinds of fishyou want. Also create a list of your othergoals. Record your goals on the firstpage of your pond management logbook (see page 26). Once you decide tobuild or manage a pond, a log book isan invaluable tool for keeping track ofyour management efforts.

Trying to accomplish too many thingswith your pond might mean that noneworks well. For example, maintainingschools of large fish along with flocks ofducks and geese in a clearwater envi-ronment and also using the pond as alivestock watering area are not compati-ble goals. Concentrate on one majorbenefit and a few pleasant side effects.For example, a soundly managed bassor trout pond might also offer a littleswimming and skating, as well as anemergency water supply. It can alsoserve as a scenic asset frequented by

songbirds and visited occasionally bymigrating ducks.

A reasonable goal for a sport fishingpond in Wisconsin would be to obtain amoderate amount of angling formedium-sized fish. Angling fun and ameal of fish now and then are reason-able expectations. Whether you areinterested in sport or commercial fishpond management, you should under-stand that northern ponds cannotproduce as many large, fast-growing fishas warmer ponds in southern states.

Investigate and planUndertake pond construction and man-agement only after carefully studying thesituation. After reading about ponds,examine your pond (or potential pondsite) in as much detail as possible.Several sections of this publicationsuggest characteristics of ponds andtheir fish populations that can be meas-ured and analyzed. Consider hiring aprofessional to analyze the pond andassist you with a management plan.

Pond design and construction are highlyimportant to a successful fishery. If youintend to build a pond, see Chapter 3and contact the U.S. Natural ResourceConservation Service (NRCS) office inyour county about engineering designservices. Your county LandConservation Department may also beable to provide technical advice. Thecounty Extension office can help youidentify design services or develop abusiness plan if your interests lie incommercial aquaculture.

chapter 2 chapter 2

Management overviewKnowing when to leave things alone isimportant. Overmanaging and applyingmanagement techniques simplybecause you’ve heard of them arecommon management mistakes.

The usual steps in managing a pond forsport fishing are:

l. Building or rebuilding for the bestdepth and slopes (Chapter 3)

2. Assessing and modifying fish popula-tions (Chapter 10)

3. Stocking suitable fish (Chapters 5, 6and 7)

If you manage a trout pond, you gener-ally need to restock it each year. If youmanage a warmwater pond, naturalreproduction usually maintains thefishery.

The interrelated ideas of balancebetween predators and food organismsand of a happy medium, or consistentlymaintaining the right amounts of certainelements in the pond, are important forsustained quality fishing. To maintain thepond as a good place for fish to live,water fertility, chemical characteristicsand temperature need to stay withincertain limits.

Water fertility ranges from too little tojust right to too much. With too little fer-tility, not enough plant and animal lifegrows to feed resident fish. With exces-sive fertility (often the case), plants clogthe pond, organic matter accumulateson the bottom and the pond becomesunsuitable for most desirable fish.

Fish grow well and produce good yieldsas long as there is enough breedingstock and food. Too many fish ruin thefood supply, resulting in undernourish-ment and poor growth. For example, ifyou stock two small, identical ponds withunequal numbers of fish—1,000 in oneand 10,000 in the other—each pond willhave about the same total weight of fisha year later. But the fish in the pondstocked with 1,000 will be larger. Don’toverstock, and don’t let the fish becometoo numerous!

In ponds managed as trout or bass fish-eries, angling harvest must be limited iffish are to live long enough to reach agood size. On the other hand, wherepanfish are present, severe cropping ofsmall fish may be needed to avoid over-population. Keeping panfish populationsin check by fishing alone is difficult innorthern ponds.

For the best bass fishing, it may bebest to exclude panfish. This contrastswith management in southern stateswhere, due to warmer water and longergrowing seasons, bass prey heavily onpanfish, control their populations andmaintain a productive predator-preybalance. Bass in northern ponds usuallydon’t eat enough panfish to maintainsuch a balance, and bass are oftenoverfished. The result of having panfishin a northern pond, with or without bass,is often panfish overpopulation andstunted growth. Adequate numbers oflarge bass are needed to exert effectivepanfish control.

Managing panfish in our climate is diffi-cult but various options exist. You cantreat the pond to eradicate or reducefish populations, use sterile hybridpanfish or simply accept and enjoyfishing for smaller panfish. Such fishingis ideal for children who like to catch lotsof fish.

Commercial aquaculture Some pond owners envision financialprofit, either by raising fish to sell or bycharging anglers a fee to fish. Ponds forcommercial purposes should bedesigned specifically for that purpose(see Chapters 3 and 9). Both “fishfarming” and “fee fishing” are risky ven-tures that require managerial skills andconsiderable investments in facilities. Tobe competitive, producers have tomarket their product at a profit. Westrongly suggest “entering the business”via effective in-depth planning before

investing in commercial aquaculture(see Chapter 9).

Meeting state environmental regulationsThe construction and management ofponds can cause safety and environ-mental problems. State laws regulatethe following activities (see Chapter 15):

■ Damming and diking

■ Excavating and dredging within 500feet of any surface water

■ Filling wetlands and any land within500 feet of surface water

■ Discharging fish food and wastesinto streams or lakes

■ Stocking fish

Federal regulations administered by thestate Department of Agriculture, Tradeand Consumer Protection (DATCP) andthe Wisconsin Department of NaturalResources (DNR) also regulate the useof chemicals to control plants and fish.Before undertaking any of these activi-ties, consult the nearest DNR office onhow to proceed within the law.

Various permits may be needed. Properapplication for a permit may not onlyspare you future grief but might result intips from state officials on the best waysto accomplish your objectives.


Designing and building fish pondsTypes of pondsThere are three main types of fish ponds

(figure 1):

1) Excavated ponds

2) Impoundments

3) Levee ponds

Each has different land requirementsand applications. Excavated ponds andimpoundments are used primarily forsport fishing, while levee ponds aremore appropriate for commercial aqua-culture.

Excavated ponds are often built in fairlylevel terrain where the groundwatertable is close to the surface. An exca-vated pond is made by digging a pitdeeper than the groundwater level. Thepit fills when groundwater seeps in, orwhen water flows in from nearbysprings. Because the excavated pond isdug below the water table (usually witha dragline), it is typically one acre orless in size.

Less commonly, pits are dug that catchrunoff water from surrounding land orreceive water diverted from a stream.These sources of water are generallyless desirable than groundwater springs

or seepage because they can introduceunwanted species and chemical contaminants. Diversion can alsochange the temperature and flow inthese systems, adversely impactingnative fisheries.

Because excavated ponds cannot bedrained, they can be difficult to manageand are most suited to sport fish produc-tion. However, they can be designedand are often used for commercial pro-duction of bait or fingerling game fish.

Impoundments or watershed pondsare appropriate for rolling or hilly areas.They are formed by constructing earthendams. Impoundments are most appropri-ate in areas with steeper land slopesand low-permeability soils. Where possi-ble, material is excavated from thefuture pond bottom to form the dam anddeepen the pond. If the dam is properlyconstructed, a watershed pond can bedrained. This enhances fish manage-ment options.

Pond water quality is generally better ifthe water is impounded from springsrather than from runoff or streams.Impoundments are not recommended iftheir construction calls for damming astream. Impoundments on streams canbecome settling basins for silt, sedimentand debris, causing the streams to fill inand become less suitable for fish. In addi-tion, it may be difficult to stop undesirablefish from entering the pond, making fishmanagement extremely difficult.

Damming streams of any size is strictlyregulated in Wisconsin and is generallynot permitted.

A levee pond is usually built on levelground by removing 1–4 feet of materialfrom what becomes the pond bottom.The excavated material is used to buildlevees, or embankments, around thepond’s perimeter. The end result is thatmost of the water stays above thegroundwater level.

Clay soils are best for levee pondsbecause they hold water and the above-groundwater construction reduces con-struction costs. Suitable 3- to 5-acrelevee ponds can be built for approxi-mately $3,000 per acre.

Levee ponds are appropriate for com-mercial aquaculture because construc-tion costs are low. The ponds areshallow, drainable and responsive tointensive management because of theirregular shape. Levee ponds are notgood candidates for sport fishingbecause they require pumping and fillingfrom wells or surface water and mainte-nance costs are high.

Selecting the right site and planningconstruction carefully plays a large partin a pond’s overall success. Contactyour county office of the U.S. NaturalResources Conservation Service(NRCS) for information about soils andadditional advice on site selection. Alsocontact the nearest WisconsinDepartment of Natural Resources (DNR)office early in the planning stage. Findout what restrictions may apply to yoursituation and what permits you need.Fish managers often possess valuableexpertise with pond management andcan help assess your plans.

chapter 3 chapter 3

Stocking fish may require that youobtain a fish stocking permit (seeChapter 15). This process involves avisit to the site by the DNR fishmanager. You should also try to identifycontractors with previous experience andgood reputations by talking with some oftheir customers. Experienced contractorsand pond owners serve as good sourcesof information.

Key considerations in designing a suc-cessful fish pond are:

■ Water depth

■ Water supply

■ A properly formed basin and sur-roundings that will help avoid anoverabundance of nutrients andaquatic plants

These design considerations are interre-lated, and changes to one can influenceone or more of the others. Landscapingdetails are somewhat less important.

Water depthWater depth is one of the most impor-tant elements in achieving satisfactoryfish habitat in ponds. No matter howlarge the pond’s surface area and how itwas formed, a better fish populationusually results when most of the pond isat least 15 feet deep. This depth helpsavoid winterkill and summer oxygendepletion that stresses fish and cancause die-off or poor growth.

Shallow ponds are more subject to win-terkill, especially in cold winters. Theyusually have fewer, smaller and lessdesirable kinds of fish because of nearwinterkill conditions.

Shallow water will do where a sufficientflow of well-oxygenated spring watermoderates temperatures and preventsdepletion of dissolved oxygen. This isthe case in trout ponds with large inflow.

Aeration is used to prevent winterkills andsummer oxygen depletion in shallowponds. You need power at the pond sitebut periodically operating a good aerationsystem need not be cost prohibitive. Ingeneral, greater depth is better for sport-fish ponds, providing more room and agreater range of living conditions for thefish and their food organisms.

Two main problems can prevent estab-lishment of a 15-foot water depth: 1)excavation costs (which become dispro-portionately higher as depth increases);and 2) soil conditions.

Before you begin construction, NRCSstaff or other knowledgeable individualsshould investigate the potential pond’ssoil structure and profile. In some situa-tions, excavation to the desired depthmay perforate the clayey soil layer thatseals the bottom, allowing the pondwater to drain away. If the natural clayseal is broken, the pond bed can beresealed with clay or commercial plasticliners, which can be expensive. It isbetter to avoid breaking the seal. Thesoils may also be unstable and the sideslopes will not hold up.

Water supplyGroundwater, either from wells, springsor seepage, provides a better watersupply than runoff or stream water.Groundwater tends to be well-filtered,while runoff and stream water tempera-tures vary and bring excessive amountsof nutrients, sediment and other materi-als into the pond. Even stream waterthat appears clear and “pure” oftencarries nutrients into a pond.

Excessive nutrients create the over-abundance of plants and other organicmatter that deplete oxygen for fish.Avoid runoff from barnyards, pasturesand fertilized or eroding cropland.Fertilized lawns and gardens are othersources of unwanted nutrients.

Even with seepage and spring water,you should take precautions. As itemerges from the ground, such watermight be very high in iron or too low indissolved oxygen for fish. Aeration alle-viates the problem but adds to the oper-


berm to prevent runoff into pond

3:1 slope

Excavated or dug pond

water depth at least 15 feet

Impounded pond

water depth at least 15 feet

3:1 slope 2:1 slope

earth fill dam

Levee pond

levee levee

Figure 1. Three types of pond construction.

7D E S I G N I N G A N D B U I L D I N G F I S H P O N D S

ational cost. Test the water before youinvest in a pond fed by wells, springs orseepage.

Designing for control ofaquatic plantsWhile a moderate amount of rootedaquatic plants benefit fish, too many canproduce an overabundance of small fishand impede fishing and management.You can significantly reduce thisproblem with good pond design andconstruction.

Rooted aquatic plants need light andnutrients, and grow best on level pondbeds. Minimize aquatic plant nuisancesby:

1. Minimizing inflow of nutrients

2. Keeping the bottom too deep anddark for plants to survive (15 feet)

3. Constructing steep side slopes

In commercial aquaculture ponds, fertil-ity is sometimes increased to promoteadequate phytoplankton levels to restrictlight penetration and the growth ofrooted aquatic plants. However, this isnot recommended for sport fishingponds.

One way to minimize nutrients flowinginto groundwater- or spring-fed ponds isto situate the pond where as little landas possible slopes toward it. This helpsreduce the amount of surface runoffentering the pond.

Excessive runoff can also be diverted bymeans of earthen berms or water diver-sion ditches. A filter strip of unmowedgrass and other low plants along thepond banks is another way to reducenutrient inflow. Other aspects of erosioncontrol are discussed in the section onlandscaping.

If the pond is formed by a dam, an outletstructure that allows discharge from thebottom enables draw-off of nutrient-richwater that accumulates there in summerand winter. Rapid water exchange fromgroundwater also reduces these problems.

SafetySide slopes that extend 3 feet into thepond per foot of drop (a 3:1 slope) aresufficiently steep to reduce plant growthwhile not being so abrupt as to causeunreasonable danger to wading children.However, a slippery clay incline of 3:1 orgreater can be a great hazard to peopleor animals that might wade or stumbleinto the pond.

It is recommended that escape ramps of5 feet horizontal distance per foot of drop(a 5:1 slope) be installed periodicallyaround the pond for escape in situationswhere soil type and slope pose a dangerto humans or animals. If the incline ismade of fine sand, it is likely to be unsta-ble and slump if steeper than 3:1. It is rec-ommended that all other soils have slopesno steeper than 2 feet horizontal distanceper foot of drop (a 2:1 slope) for stability. If your objectives are plant control and amaximum amount of deep water, thesteeper the side slopes the better.

Wildlife pond/fishing pond systemSome sites may be better suited forwildlife ponds. A pond built in an area ofheavy erosion or nutrient runoff will havea short life as a fishing pond. Erosion willfill in areas of the pond and, combinedwith the extra nutrients, bring increasedaquatic plant growth. Under these condi-tions, it may be better to first provideerosion control and then build a wildlifepond or a wildlife pond/fishing pondsystem.

Wildlife ponds or marsh ponds typicallyhave a maximum depth of about 6 feetwith the average depth being about 1 to2 feet. The pond bank should slopegradually (8:1 or flatter). These condi-tions encourage aquatic plant growththat will be consumed or used for coverby various types of wildlife. Marsh plantsremove the nutrient input from runoff.

A wildlife pond can serve as a settlingpond to cleanse water of excess nutri-ents and sediments when built in con-junction with a fish pond. Use berms todivert runoff water away from the fishpond and into the wildlife pond.

Separate the wildlife pond from the fishpond by a dike. The dike prevents sedi-ments from moving into the fish pondand prevents fish from escaping preda-tion in the shallow weedy areas of thewildlife pond (see Chapter 5). Install anoverflow tube, concrete or sheet piling ora rock-lined channel in the dike toprevent over-topping and dike washoutduring heavy rains.

Surface areaAs a rule, the larger the pond, the morestable its fish population. While troutponds of only a quarter acre maysupport adequate fishing if they havestrong spring flow, most ponds don’tprovide satisfactory fishing unless theyare a half acre or more—and preferablymuch more.

Small ponds usually need much moreintensive care than large ones. Theirdisadvantages may be somewhat allevi-ated by making them very deep. Also, ifsomething goes wrong it is easier andquicker to fix the problem in a smallpond. Make your decisions based onyour goals.

Landscaping and erosion control in thepond’s surroundingsWith a little planning, a fish pond andthe area around it can be made veryattractive. Decide whether you want anatural setting or the look of a mani-cured lawn. In a natural landscape, logs,stumps, rocks and uneven ground maybe fitting. If much of the area will bemowed, you may need to smooth theground and eliminate obstacles duringpond construction.

To prevent erosion, establish plantcovers quickly on exposed areas. Sod ora heavy stand of grasses prevent soilfrom washing away. Some recom-mended grasses include Kentucky blue-

grass, smooth bromegrass, creeping redfescue and timothy.

Don’t plant deep-rooted plants such asalfalfa, sweet clover, shrubs and treeson earthen dams or embankments.Deep roots weaken these structures andcause leaks. Some ponds may needreinforcement, called “rip-rap,” withstone of 8–10 inches diameter piled 11⁄2to 2 feet thick along the shoreline. Rip-rap protects against wave erosion, espe-cially in the case of dam and fillembankments.

Mixed clumps of evergreens and decidu-ous trees, bordered by shrubs, providefood and cover for wildlife and give pondsurroundings a pleasing appearance.Don’t plant trees on embankments.Roots cause structural problems, anddense shade suppresses cover andencourages soil erosion.

Shrubs shouldn’t be planted so near thepond that leaves or twigs fall or blowinto the water. Leaves use up oxygenwhen they rot and create layers of litteron the pond bed. They also furnish nutri-ents for excess water plants. Keepshrubs at least as far back from thewater’s edge as the greatest height thetree or shrub will reach—and preferablymuch farther. It isn’t necessary to setevergreens back quite as far. Trees andshrubs on the shore area may also inter-fere with fishing.

Fence livestock away from the pond.Animals destroy vegetation in the pond-bank buffer strip, and their droppingsadd nutrients to the water. Grazing andtrampling also weaken dams, embank-ments and spillways. If livestock water-ing is one of the pond’s functions, pipethe water to an area where the animalswon’t harm the pond.

Construction of excavated or dug pondsMany parts of Wisconsin provide favor-able terrain for dug ponds because theyare fairly flat, with soft, porous soils andgroundwater that lies close beneath thesoil surface. These are usually areaswhere sand and gravel are at or nearthe surface. Groundwater percolateseasily through sand and gravel.

However, many areas which seem suit-able may be designated wetlands ormay adjoin designated wetlands. Underthese conditions strict restrictions apply.DNR water quality specialists and NRCSstaff can help you understand the regu-lations and evaluate the site to deter-mine if it is designated as a wetland.

Peaty, acidic soils characteristic of manywetland areas are not suitable for pondconstruction. The decaying organicmaterial in these soils depletes dis-solved oxygen levels in pond water. Thecharacteristically low pH of waters drain-ing from many wetlands can retardgrowth or even kill fish.

The water level may fluctuate signifi-cantly in seepage ponds as the ground-water table rises and falls—higher in wetyears and lower during drought. Plan toexcavate more than 15 feet below thelowest level that the groundwater tablereaches in a very dry year. ConsultNRCS or other experienced peopleabout how to make test borings to findthe water table in late summer of a dryyear. Depending on soil conditions,groundwater can be pumped into pondsfrom nearby wells. Sometimes windmillsare used for this.

Catchment pits for overland runoff canbe dug if soils are clay or other finematerial that will hold water, or if clay orother sealants can be obtained to linethe pond bed. Because there is usuallyless water exchange and more potentialto pick up sediments and other pollu-tants, using runoff water to fill ponds isgenerally less desirable for ponds builtto support sport fishing.

The type of equipment that is best fordigging ponds depends largely upon thepond’s size, site characteristics anddesired depth. Draglines or bulldozersare generally used. Bulldozers are moreadapted to the drier pond beds. Pondsdug by draglines are seldom wider thanabout 90 feet but may be much longer.Excavation width is governed by the dis-tance a dragline can move back beforeit is blocked by its spoil piles—unlessthe spoil can be moved.

The material dug out of the pond, calledthe “spoil,” should be graded back awayfrom the pond edge and landscaped to

improve overall appearance. Usingsome of the spoil to build a gentle bermaround the pond can help divertunwanted overland runoff.

Construction of impoundmentsIn impoundments or “fill-type” ponds,water is impounded by an earthen damcontaining a core of watertight materialsuch as clay. It is best to build on a sitewhere a great volume of water can bestored by constructing an embankmentwith a small amount of fill.

The most desirable location is in a valleythat is narrow at the dam site. The pondarea should be wide and flat with steepsides. Excavation is usually required todeepen the site and also provides theearth for the dam. Wave erosion on thedam embankment can be a problem inlarge ponds. If possible, try to choose asite where the prevailing wind doesn’tblow along the length of the pondtoward the dam.

A properly designed impoundment willhave two water outlets; a trickle tube ormechanical spillway and a vegetatedearthen emergency spillway (figure 2).The emergency spillway is for floodflows. To manage fish and control weedsit is very desirable for the pond to havean outlet designed with a draw downcapability for drainage. Contact a profes-sional engineer to design the proper sizeand type of spillway.


It is best for fish if the water supplycomes from groundwater rather thanfrom runoff. If the impoundment must bedesigned to catch runoff water, situate itso that the drainage basin is largeenough to provide sufficient runoff to filland to maintain water levels even indrought conditions.

You can calculate surface runoff accord-ing to the area of land draining into thepond, the amount of precipitation, andrunoff characteristics involving landslope, soil porosity, vegetation andhuman disturbances of the land.Generally, for a Wisconsin pond thatdepends entirely on runoff water, fiveacres of runoff basin land is needed peracre/foot of pond water. An acre/foot isdefined as the volume in 1 acre of water,1 foot deep.

Clay and silty-clay are good soils forimpoundment basins. Sandy-clay is suit-able only if the cost of extra materials forsealing the pond is acceptable. Becareful not to excavate through the soilsthat best hold water. Sites in someareas of limestone or dolomite are espe-cially unsuitable—even hazardous—forimpoundments. There may be crevicesallowing water to drain very quickly fromthe pond. To get a good bond betweenthe earth and fill material, you mustremove all vegetation (including stumpsand roots) and topsoil from the dam siteprior to construction.

Soils for earthen dams should be atleast 20% clay by weight and contain awide range of particle sizes up to coarsesand or gravel. Fine-grained silts andclays are best to limit seepage. Placethe most impervious material in theupstream two-thirds of the embankment.The earth must be compacted to mini-mize seepage through the dam.Sheepfoot compactors or loaded rubber-tired scrapers are used to compact eachlayer. Typically, fill is placed in 9-inchlayers and compacted.

To ensure proper compaction, you mustcontrol soil moisture during construction.Soils that are too wet or too dry will notcompact adequately. Carefully compactthe soils by hand around any pipes inthe dam. For the dam’s vegetated spill-way, clay, sandy-clay and silty-clay aresuitable. Avoid loose sand and othereasily erodible soils. Dam cross-sec-tions, side slopes and wave protectionare part of site-specific design.

Construction of levee pondsLevee ponds are best suited for com-mercial aquaculture. Prior to startingconstruction make sure the site is suit-able for the facilities being planned. Anadequate water supply must be avail-able in terms of volume, water qualityand pumping ability. The soils should betight enough to prevent water lossthrough the pond bed or levees and theyshould not have high levels of chemicalcontaminants. The site should not besubject to flooding and should be easy

9D E S I G N I N G A N D B U I L D I N G F I S H P O N D S

corrugated metal riser(diameter at least 4 feet)

spillway pipes(diameter at least 18 inches)

water depthat least 15 feet

3:1 sloperemovable stoplogs

collar to block seepage

core trench

2:1 slope

3:1 slope 2:1 slope

water depthat least 15 feet

core trenchseepage plate

level of paved emergency spillway

level of paved emergency spillway

bottom draw-off tubewith valve

bottom drain tube with valves

concrete riser (diameter at least 4 feet) covered by trash rack

and baffle plate

Surface overflow dam

Bottom draw-off dam

Figure 2. Two common types of outlet structures for dams that form fish ponds.

Riser-and-stoplogconstruction is thesimplest designthat allows con-trolled bottomdraw-off. A drop-inlet spillway canaccommodategreater variation offlow. It is neededwhere runoff from alarge land areasupplies the pondand where suddenhigh water isexpected.

to drain. Generally less earth will haveto be moved and the cost will be lowerin level areas than on hilly or rollingareas.

Decisions on the number and size ofponds will depend on what fish you wantto raise, the land available and othervariables. You should look at the cost ofbuilding ponds of different sizes andconfigurations. Typically commerciallevee ponds are built in sets of four.Square or rectangular ponds reduceconstruction cost and increase accessi-bility and ease of management. Thelevees should be at least 8 feet wide atthe top and extend at least 11⁄2 feetabove the intended water level. If possi-ble they should be constructed with a3:1 or greater slope. However, the actualslope will depend on the soil type.

As with impoundments, all vegetationand topsoil must be removed from thesite prior to starting levee construction toallow a good bond between the founda-tion soil and fill material.

Self-loading earth movers are the mostefficient equipment to use in buildinglevee ponds. They give the best com-paction of fill material when completewheel track coverage is made over eachlayer of fill placed in the levee. Vibratingor sheepsfoot compacters are also fre-quently used. For proper compaction thesoil must have at least a 15% moisturecontent.

Leave open the area of the levee wherethe drain is to be placed to serve as adrain for storm water until constructionnears completion. Install the drain pipe

of appropriate diameter as soon as thepond bottom is graded. Dig a smallsloped ditch, approximately one third thediameter of the pipe, to give uniformsupport for the pipe (figure 3).

Place moist fill materials along the sidesand over the top and compact it by handto a distance of at least two feet abovethe pipe. The hand-compacted fill pro-vides protection from heavy equipmentwhile the levee is being completed. Insome situations the pond drainpipeshould be installed first, so that stormwater can drain through the pipe duringconstruction. In either situation, install atleast 2 anti-seep collars around thedrain pipe to avoid seepage along theoutside of the pipe. Such seepage cancause erosion and even failure of thelevee.

The ponds should be built with a 0.1–0.2foot drop per 100 lineal feet from theshallow to the drain end. The level of thepond bottom at the drain must be highenough to drain to a ditch which carrieswater away from the site by gravity.

To prevent unwanted fish from enteringthe pond through the pipe during drain-ing, elevate the drain pipe 2 feet abovethe ditch. Several types of draw-downstructures can be used; simple turndownpipes are recommended for large fishproduction. More elaborate structureswith harvest kettles can be used for fin-gerlings or small fish, but these are quiteexpensive.

Don’t forget Wisconsin’s winter ice con-ditions. If you are using a simple turn-down pipe and keeping the pond fullduring winter, aeration or continuouswater input should be installed next tothe drainpipe to keep water from freez-ing around the pipe and heaving orbreaking it. The drain system must besecure enough to prevent unintentionaldraining and large enough to allow thepond to be drained completely in 5–7days, preferably less. Typically a 6" pipeis used for a 1-acre pond and an 8" pipefor a 3-acre pond.


drain pipes

inflow pipe

levee

16'

1320'

660'

660'

1320'

well

drainage ditch

Figure 3. Layout of typical levee type ponds.

Ponds as places for fish to liveBasic pond characteristics for fish productionThe ideal Wisconsin sport fishing pondpossesses the following attributes:

■ A surface area of at least one acre

■ Steep side slopes (about 1 foot verti-cal per 3 feet horizontal)

■ At least one quarter of the pondmore than 15 feet deep

■ Water comes exclusively fromgroundwater seepage rather thanstreams or runoff from land

■ Dissolved carbonate mineral concen-tration (hardness) of 150–250 partsper million (conductivity of 200–500µmhos/cm)

■ pH between 7–8

■ Inflow with only moderate amountsof nutrient chemicals—amounts thatwould naturally enter the pond froman undisturbed landscape

■ Less than 1⁄4 of the pond bedcovered by dense plant growth

■ Concentrations of dissolved oxygennot much below 5 parts per millionduring the growing season, even inthe deepest water

■ A balance between the amount offish and the amount of natural foodso that fish grow rapidly

Few ponds are ideal in every respectand different characteristics in any of thecategories can still produce worthwhilefishing. In many locations, some of theideals cannot possibly be met, even withconsiderable management. Forexample, regulating the hardness ofgroundwater is usually not feasible, andyou should not hesitate to own a pondjust because hardness is not optimum.Throughout the state, ponds with amaximum depth of 7–10 feet producegood fishing for many years.

An ideal coldwater pond for trout differsfrom a warmwater pond primarily byhaving a good seepage of groundwater(springs), which keeps water tempera-ture lower in summer.

This chapter explains why the pondcharacteristics listed above are impor-tant to the well-being of fish. The func-tioning of ponds is complex—but under-standable and predictable enough tohelp you manage for quality fishing.

The pond ecosystemA pond is an organized system of water,soils, dissolved substances, solarenergy and living organisms. These ele-ments comprise the pond ecosystem.

The parts of the ecosystem continuallychange and interact. Material andenergy enter and leave the pond contin-uously (figure 4). Most minerals andorganic materials that enter the pond aretrapped and stored there. In contrast,most water and gases that flow in soonflow out again. The pond captures solarenergy to produce food and warm thewater.

The pond is part of a larger land-and-water ecosystem called the watershed.The watershed includes all the land areathat drains into the pond either throughsurface or groundwater. What goes onwithin the watershed greatly affects whathappens in the pond. For example, dis-turbance of vegetation in the drainagebasin may increase rainwater runoff andsoil and nutrients that wash into thepond.

Some mineral and organic materialenters the pond in solid form (dirt) thatsettles to the bottom. This material accu-mulates in the pond. Other minerals andorganic matter enter the pond alreadydissolved. Plants can readily use dis-solved nutrients to grow.

chapter 4 chapter 4

Some plants are eaten by animals;others die and settle to the pond bottom.The plant-eating animals die and drift tothe bottom or are eaten by otheranimals—which in turn may be eaten bystill others. The plant and animal mate-rial that animals consume is eitherstored in their bodies or passes into thewater as solid or dissolved wastes.

The dead plants and animals, wastesand solid materials washed into the pondpartially decompose and redissolve dueto scavenger animals, microorganismsand chemicals (figure 5). The redissolvedmaterial serves as nutrients for furtherplant growth. Materials not completelydecomposed accumulate on the pondbottom and so the cycle continues (figure 6).


outflow of water and energy

outward seepage

outward radiation of heat

rain

run-off filtered

by marsh

streamoutflow

matter washed inby stream inflow

groundwater seepagefiltered by soil

water, soil and organic matterwashed in by overland runoff

primary producers

consumers

decomposers

anglers other

large fishes

small fishes and large invertebrates

small invertebrates that eatdead organic matter

small invertebrates that eat green plants

algae, higher plants

waste products

bacteria and fungi

dissolved mineralsdissolved gases

water

Figure 4. Flow of energy and matter into and out of the pondand its drainage basin.

Figure 5. The food pyramid of a pond.

13P O N D S A S P L A C E S F O R F I S H T O L I V E

groundwater table

leaves and fragmentsof land plants

heat from activity of organisms

heat from pondbed and decay

wateroutflow

seepage from pond into groundwater

root

ed a

quat

ic pl

ants

more material depositsat pond bed than

redissolves back into water

scavengers and microorganisms

som

e de

cayin

g pl

ant

mat

ter d

issol

ves

zooplankton eat algae and bacteria

some dissolves

some sink to bed

some leavesdecay, dissolve

somesink

to bed deadorganisms

somesink

algaeand

bacteria

somedecaying

organismsdissolve

smallfishes

largefishes

heat and water vapor

given off by pond

heat and water vapor

given off by plants

important gases:nitrogen, carbon dioxide,

oxygen, dissolve through surface

groundwater seepsinto pond

mineral subsoil

organic mud layer

eroded soil and organic matter

Figure 6. Inner working of a pond in rough outline.

This sketch of the movement of energy and matter looks complicated, but the realsituation is far more complex. Most mineral and organic matter entering the pondbecomes trapped in it and is, to some extent, recycled. Most energy that entersfrom the sun leaves again rather soon. Water also flows through.

R.J and S.A. White

Much of the mineral and organic matterthat enters a pond stays there, even ifwater flows out. Some nutrients arecarried away by emerging insects or infish taken by natural predators oranglers.

The food relationships that link organ-isms form a “food web” (figure 7). Theweb-like structure provides a stable foodsupply to fish and other pond creatures.When a part of the web changes, forexample, when disease reduces thenumbers of one animal, other creaturesstill remain to serve as food for fish.

When we manage a pond to produceone or several kinds of fish, we oftenreduce the kinds of habitats and organ-isms in the pond. This removes manylinks from the food web and may makethe pond ecosystem less stable.

We purposely build ponds with littlehabitat diversity so that only a few kindsof organisms can thrive—the fish wewant and a few food organisms forthem. We build uniformly steep pondside slopes to discourage plants thatinterfere with fishing and provide habitatfor too many young fish. We dredgesmooth, deep pond bottoms suited formaximum fish growth and for seining toremove fish. We try to ensure a short,efficient food chain by stocking only oneor two kinds of fish.

Such artificially simplified and shortenedfood webs boost production of thedesired fish. This is usually what thepond owner wants, rather than an “inter-esting” and diversified natural commu-nity of fish that doesn’t provide as muchangling.

However, keep in mind that this simpli-fied community is less stable and maynot be able to bounce back from occa-sional catastrophes such as disease,cold snaps and drought. Substantial andrepeated management is often neededto keep a pond community the way youwant it. There is a saying in pond man-agement: “Once you start managing,you have to keep managing like mad.”

Another problem occurs when there areinsufficient predator fish (bass). Smallfish (bluegills, other sunfishes, minnows)may become so abundant that they sig-nificantly reduce the “water flea” popula-tion, which consumes algae. This leadsto an overabundance of algae, which isnot only unsightly and foul smelling butalso harms the pond’s oxygen levels.


Figure 7. Food web andfood chain contrasted.

The arrows point in the direc-tion of predatory or “grazing”pressure. A chainlike systemmay produce more of certainfish that we want, but a breakin one link may severelydisrupt production. The web-like system has many moreparts and is therefore morestable and more productiveoverall.

Phyto-plankton

Consequences of overenrichmentA pond’s suitability for fish deterioratesseverely if the pond contains too manynutrients. This happens when topsoil,leaves, fertilizers, or human and live-stock wastes flow in—or if too much fishfood is added. Algae and other plantsthen become overabundant. Stagnant,deep areas may lose dissolved oxygenand develop such a buildup of toxicgases in summer and winter that fishbecome sick or die. This problem isespecially acute in winter under icecover. Mass die-offs of fish, termed “win-terkills,” are common in shallow pondswith much organic matter. “Summerkills”may occur with prolonged periods of hot,still weather (figure 8).

Facts about water and thechemicals dissolved in itWater travels, carrying along substancesthat dissolve in it. Algae, dissolved mate-rial and other substances in the wateraffect the amount of light entering thepond, which in turn affects the amountand depth of rooted plant growth.

Pond water can be rich or poor in plantnutrients (calcium, potassium, phospho-rus and others) depending on their abun-dance and solubility in the surroundingland. Many ponds grow only small ormoderate amounts of aquatic vegetationbecause few nutrients enter from thewatershed. A well-vegetated landscapereduces nutrient inputs to the pond.

Depending upon their amounts, the keynutrients nitrogen and phosphorus candetermine growth levels in many ponds.Algae form the base of the food web andincreasing the amount of nutrientsincreases total production of algae. Thiscan become a nuisance. More algaedoes not always result in more fish sincenot all of the algae is useful to fish or fishfood organisms.

Alkalinity is a measure of the acid-neu-tralizing capacity of water. The mainconstituents of alkalinity are carbonate(CO3

=) and bicarbonate (HCO3-) dis-

solved from limestone (CaCO3) anddolomite in Wisconsin’s soils andbedrock (figure 9).

In water with low alkalinity, a smallamount of phosphorus yields the kindsof algae that water fleas and other fishfood organisms eat. At higher phospho-rus levels, the added production may be“bluegreen” algae—a type that algae-eating animals don’t like. Thus, ratherthan supporting the food web that pro-motes fish production, bluegreen algaeproliferate without being eaten. As nui-sance algae develop, die and decay,they draw excessively on the pond’ssupply of dissolved oxygen. The result isoxygen stress that may harm fish.

Ponds with more alkalinity have greaterpotential for producing fish. But the ful-fillment of that potential will be seen onlyif there is just the right balance of nutri-ents and if other conditions, such astemperature, are right.


overenriched pondpond with moderate fertility

deep light penetration

warm water

thermocline

cold water

plants replenish dissolve O2 throughout

sparse algae growthsparse rootedplant growth

sparse algae growth

summer

shallow light penetration

much decay of organic matterdepletion of dissolved O2 in lower zone

dense algae growthdead algae sink

dense rootedplant growth

too dark for algae growth

summer

snow

ice

winterkill of fish

no light penetration

depletion of dissolved O2throughout

overabundant rooted plants too much algae

decay of organic matter

winterno light penetration

winter

enough dissolved O2 remains for fish throughout pond because

little is consumed by plants and dead matter

> 30 mg/l < 30 mg/l < 15 mg/l

Figure 8. Hazards ofpond overenrichment.

Figure 9. Alkalinity of Wisconsin lakes.

Another benefit of moderate to highwater alkalinity is the action of a varietyof chemical conditions unfavorable tofish and other aquatic life. The dissolvedminerals provide a buffer againstextreme changes in pH. In addition, fishneed the nutrients associated with alka-linity to grow.

Ponds range in alkalinity from less than10 parts per million (ppm or mg/L) toover 300 ppm. Most are between 50 and240 ppm. An alkalinity of 40 ppm seemsto be a pivotal value below which fishproduction declines and above which itis moderate to high. There is no steadytrend of increased production withincreased alkalinity because of variabilityin other key conditions (table 1).

Water changes in density as it changesin temperature and chemical content.Water is nearly unique among sub-stances in being lighter as a solid thanas a liquid. The fact that ice floats atopponds in winter rather than growingupward from the bottom (or falling thereafter forming at the surface) is pro-foundly important to pond life.

Pond breathing, circulationand stratificationA pond exchanges gases with the airabove it. This is a form of “breathing.”Gases and other dissolved and driftingmaterials are moved about the pond bywater circulations caused by wind andgravity. In winter, ice greatly reduces cir-culation and almost completely blockspond breathing. In both summer andwinter, the pond water may stratify intolayers representing a gradation of tem-

perature, hence different density. Theheaviest water lies on the bottom andthe lightest at the top.

During summer stratification,or layering,wind circulates only the upper part of adeep pond. In shallow ponds that areexposed to the wind, summer stratifica-tion may occur for only a few days underextremely still conditions. In deeper pro-tected ponds, stratification may last allsummer. Generally, ponds less than8 feet deep will not stratify for longperiods in the summer unless they arewell-protected from the wind.


Table 1. Pond carrying capacity related to alkalinity of the water.

These are very rough indications of how much fish can be supported by naturallyoccurring food in a pond. Particularly for trout, much greater amounts can be sus-tained in the pond by artificial feeding, which has certain drawbacks.

Approximate carrying capacity (lbs/acre)Coldwater

———— Warmwater ponds ———— pondsAlkalinity Bass or Bluegills or of water catfish other panfish Total** Trout**

More than 100 ppm* 50–100 200–400 250–500 150 or more

40 to 100 ppm 25–50 75–200 100–250 25–150

Less than 40 ppm under 25 under 75 under 100 under 25

*parts per million

**In warmwater ponds, much of the total poundage will be in the form of young fish thatare too small for angling. In coldwater ponds, all or most of the trout will usually be largeenough for angling—and the poundage shown may provide about as much fishing asthat shown for warmwater fishes on the same line.

water all of same densityfulll circulation—dissolved oygen replenished

water all of same densityfull circulation—dissolved oygen replenished

wind

windwind

wind

dissolved oxygen diminishesdue to organic decay in layers

cut off from circulation

whole pond same temperature in range

of about 40-60˚F

spring overturn

about 39˚F throughout

autumn overturn

65-75˚F —well lighted

cooler

summer layering

39˚F or a bit cooler

dark throughout

winter layering

32˚F

Figure 10. Circulation and thermal layering of water in ponds.

Not only temperature but the amount of oxygen available to fish is strongly influ-enced by the seasonal cycles of circulation and layering. Very shallow ponds(not shown) may have complete circulation for much of the summer, but aremuch more likely to be oxygen-depleted in winter.

In fall and spring when cooling orwarming change all the water to anequal temperature and equal density,the water mixes easily and stratificationdoes not occur. These events aredescribed in figure 10.

Investigating a pond’s suitability for fishPond owners often ask whether watercan be simply tested for fertility andother chemical characteristics to evalu-ate its fish-producing capacity or to findout why fish haven’t thrived. Thesedeterminations are far more involvedthan just sending water samples to alaboratory.

As previously described, ponds arecomplex, and their conditions changecontinually. The foremost need is to bealert for land disturbances, water runoffcoming into the pond and the entry ofhuman or livestock waste that couldcause overenrichment. Such observa-tion of the pond’s surroundings, com-bined with a program of water tempera-ture, water clarity and dissolved oxygenmeasurement in the pond, providesenough information for basic pond man-agement.

Alkalinity, pH, inorganic nitrogen andphosphorus are additional tests that canhelp you manage your pond. Somepond testing equipment is relativelyinexpensive to purchase or make, or you

may consult a professional biologist foradvice.

Judging a pond’s productive capacity ordiagnosing its problems is best done bya professional. Properly trained aquaticbiologists can evaluate conditions of thepond site and surroundings and caninterpret temperature and oxygen data.

You may be able to participate with aprofessional in pond investigation—or,after doing some research, undertakemeasurements on your own. Muchdepends on your knowledge of science,the amount of time you can spend andthe equipment available. Various handyanalysis kits for dissolved oxygen andother determinations are commerciallyavailable.

Working with a professional is especiallyvaluable in designing the investigationand interpretation of results. Designinvolves planning the right sampling atthe right times, while interpretationinvolves judging what the data mean interms of pond biology and what theimplications are for management.

Knowing maximum water depth and cal-culating mean depth are important, as isobserving the abundance of aquaticplants and keeping records of the fishcaught (species, length and weight). It isessential to identify possible sources ofnutrient overenrichment, such as septicsystems, livestock wastes, soil and fertil-izer erosion and roadway runoff.

Dissolved oxygen and temperature arecrucial to fish and should be systemati-cally monitored. Electronic or chemicalkits for dissolved oxygen measurementand sampling devices (dissolved oxygensamplers) should be used. Contact theDNR or your county Extension office forpossible sources of these items.

Important times to analyze water tem-perature and dissolved oxygen (DO)are: 1) in mid-or late summer after aweek or more of very hot weather; and2) in winter after ice and snow havecovered the pond for a month or more.For a more detailed picture, monitor thecomplete annual cycle of pond tempera-ture and DO by sampling every week ortwo (table 2). A specialist can assist youin developing a schedule for tests at avariety of depths.


Table 2. Water temperature at various depths1 over time.

This is an example of a pond measured on the 15th of each month at the deepest point (181⁄2 ft deep).

Waterdepth temperature (˚F) at mid-month

(feet) Jan2 Feb2 Mar3 Apr May June July Aug Sept Oct Nov Dec2

surface 32 32 44 50 60 67 71 75 62 51 46 32

2 36 33 44 50 60 67 71 75 62 51 46 39

4 38 36 44 50 60 67 71 75 62 51 46 39

6 39 38 44 50 60 67 71 75 62 51 46 39

8 39 39 44 50 60 67 71 75 62 51 46 39

9 60 67 71 75 62

10 39 39 44 50 58 62 65 70 60 51 46 39

11 52 55 58 61 57

12 39 39 44 50 50 52 53 54 54 51 46 39

14 39 39 44 50 50 52 53 54 54 51 46 39

16 39 39 44 50 50 52 53 54 54 51 46 39

18 39 39 44 50 50 52 53 54 54 51 46 391Measurements made at regular 2-ft intervals, except at 1-ft intervals in areas of rapid temperature change.2Pond covered by ice. 3About 1 week after ice has melted.

Great temperature variations exist frompond to pond and even within the samepond depending on the water depth,wind strength, air temperature and otherfactors. Temperature affects waterdensity. Water is heaviest at 39˚F (4˚C).Thus, water nearest 39˚F tends to be atthe bottom with warmer—or in winter,cooler—water floating on top of it. Thisvertical layering, when it occurs, causesa gradation of temperature from top tobottom. Fish can choose the depth withtheir preferred temperature—as long asthere is enough oxygen for them.

Winter layering—Ice covers thesurface. Water is 32˚ just under the iceand progressively warmer at greaterdepths. Deepest water is near 39˚.Warming by groundwater seepage mayalter the curve.

Spring overturn and even warming—After ice melts in March or April, windmixes water evenly throughout as thepond warms. Temperature stays equalfrom top to bottom as warming occurs.

Late spring and summer layering—Does not often occur in many ponds,especially not in ones shallower thanshown here. Layering takes place if upperwater becomes, by intense warming, somuch lighter than lower water that windcannot overcome the density differenceand can no longer mix all the way to thebottom. Then mixing occurs only in upperwater. The well-mixed upper layer has athinner layer of water with rapidlydecreasing temperature between it andthe cooler water below.

The upper layer usually extends deeperthan shown. Wind may become strong

enough to destroy layering. Very coolgroundwater seeping into the pond maymake layering more distinct and stable.

Autumn overturn—Surface watercools, becomes denser and sinks,mixing with warmer water just beneath.Thus, the upper layer is cooled to adensity near that of the lower layer andwind can remix the whole pond.Complete fall mixing can occur onlywhen the upper water sinks as theweather gets colder; wind is not needed.Fall overturn halts when ice blocks windaction and the upper water becomescolder, hence less dense, than waterbeneath it, which is nearer 39˚F.

Figure 12. Dissolved oxygen at different depths in the same pond, as affected by the wind mixing andthermal/density layering.

During spring and fall overturn—Large amounts ofoxygen can dissolveinto the pond from theair because water thatis cooler can holdgreater concentration ofdissolved gases.Amounts of dissolvedoxygen are the same atall depths becausewater is well circulatedthroughout.Concentrations of 9–12ppm commonly occur.

During summer lay-ering—Warmer waterin the upper layercannot hold as much

dissolved oxygen as could the coolerwater in springtime. Cool water of thedeep layer could hold more dissolvedoxygen, but decay of organic matterconsumes oxygen and the lower watercannot obtain more because density lay-ering prevents it from being circulatedinto contact with the atmosphere.Therefore, dissolved oxygen decreasesin the lower layer and it may becomeunfit for fish.

During winter layering—Ice andsnow block light and oxygen from enter-ing. Plants have too little light to produceoxygen and oxygen from the atmos-phere cannot dissolve in the pond.Respiration and decay consume dis-solved oxygen. Concentrations decreasethe most near the pond bottom wherethere is more organic matter. Fish areforced upward into layers with enoughdissolved oxygen.


early springoverturn &

warminglate

spring

surface

30˚

10˚ 20˚C0˚

15

10

5

5

3

4

2

1

00

40˚ 50˚ 60˚ 70˚ 80˚F32˚pond bed

summerlayering

early fall

late fall overturnand cooling

water temperature

wat

er d

epth

in fe

et

met

ers

winter layering

ice

Pond temperature profiles

surfaceice

0 2 4 6 8 10 12

15

10

5

0

pond bed

in this range during spring and fall overturns

during summerlayering

during late winterlayering

Milligrams of oxygen per liter of water (parts per million)

wat

er d

epth

in fe

et

Dissolved oxygen profiles

Figure 11.Water temperaturechange during theyear in a small,fairly deepwarmwater pond.

Types of fish toraise in Wisconsinsport fishing ponds

It’s important to know something aboutthe lives of the fish you choose toraise in your pond. Species differ intheir requirements for feeding,

growing, reproducing and surviving. Ifthe pond is unsuitable for the kind of fishstocked, be prepared for reduced growthand poor reproduction or survival rates.

There are two basic categories of pondfish—warmwater and coldwater.Warmwater fish such as bass, bluegills,other panfish or catfish, do best inponds where summer water tempera-tures are more than 70oF. A pond maybe suited for coldwater fish (variouskinds of trout) if summer water tempera-tures remain below 70oF.

Temperature should be measured a footbelow the surface near the center of thepond. Most species do best when dis-solved oxygen concentration remainsabove 5 ppm, but warmwater fish cansurvive lower levels of dissolved oxygenand all fish can survive lower levelsduring the winter. The so-called “coolwa-ter” fish such as northern pike, muskel-lunge, walleye and perch, generallydon’t thrive in small bodies of waterwithout intensive management (seeChapter 9).

chapter 5 chapter 5

Table 3. Summer length ranges at various ages for fish in Wisconsin ponds.

Growth may be somewhat greater where fish are uncrowded and temperature and food supply are ideal. Growth can be muchslower, especially where ponds are overpopulated.

———————————————————length in inches———————————————————first second third fourth fifth sixth

Kind summer summer summer summer summer summerof fish (age 0)* (yearling) (2-yr-old) (3-yr-old) (4-yr-old) (5-yr-old)

Rainbow trout** 4–6 9–14 14–17 15–19 *** ***Brook trout 2–4 6–8 8–12 9–14 11–16 ***Largemouth bass 1–4 6–8 8–10 10–12 12–14 13–17Smallmouth bass 1–4 4–7 7–10 10–12 12–14 13–17Channel catfish 1–4 5–7 8–10 11–13 13–15 15–17Bluegill 1⁄2–2 3–4 4–5 5-6 6–7 61⁄2–71⁄2

*Fingerling **From fall-spawning stock in hatcheries ***Very few survive to this age, and growth is extremely variable.

Coldwater fishThe coldwater fish include trout and theirrelatives (salmon, whitefish). Trout aremost suited for coldwater sport fishingponds or small lakes (figure 13). Trouteat a wide variety of organisms. Theyprefer zooplankton, insect larvae andcrayfish. Supplementary feeding is notrecommended unless the fish arestocked in large numbers.

Trout spawn on gravel beds in streams.Typically, they do not spawn success-fully in ponds. Therefore, populationsare maintained by periodic stocking.Brook trout can sometimes reproduce ingravel or coarse sand where springswell up in the pond bottom. As with otherfish, trout growth varies greatly betweenponds, depending on oxygen levels,food supplies, crowding and fish size.

Rainbow trout (Oncorhynchusmykiss). Rainbow trout are the mostadaptable of the species and are readilyavailable from dealers. They also growfast and are easy to catch. Generallythey can withstand warmer water thanother kinds of trout, and do well in allparts of the state. Rainbow trout growbest when the water is between54˚–66˚F. They commonly reach a sizeof 15 inches in about three years. Fewlive long enough in a pond to reach 20inches.

Brook trout (Salvelinus fontinalis).Brook trout do best in spring-fed coldwa-ter ponds with water temperatures of48˚–60˚F. Brook trout are also easy tocatch and can provide especially tastytable fare. They may grow as well asrainbow trout up to a size of 10 inches,after which their growth slows. A 15-inchbrook trout is an exceptionally large one.For fishing variety, stock rainbow trouttogether with brook trout.

Brown trout (Salmo trutta). Browntrout tolerate slightly higher tempera-tures than other species. However, theyare relatively hard to catch and thereforemay be less desirable. Brown troutusually produce a far lower total harvestover the years than rainbow or brooktrout. Brown trout can live 5–7 years,despite heavy fishing even by skilledanglers.

The wary 18–20 inch browns are canni-balistic which may make further stockingwith fingerling or yearling trout unrealis-tic unless the large brown trout areremoved. This may require use of fishtoxicants.

Hybrid trout. Hybrids between variouskinds of trout are sometimes availableand can be interesting to raise. They areunusual and often grow faster than pure-bred trout, but may be hard to catch.They usually aren’t practical for the pondowner who is simply interested in recre-ation and a few fish on the table.


Figure 13. Three kinds of trout that can be used in coldwater ponds. Thebrown trout is usually not advisable, however.

Warmwater fishThe primary warmwater fish raised inWisconsin ponds are members of thesunfish or bass family. They include thepredatory largemouth and smallmouthbass (figure 14) and smaller sunfish,such as bluegills, pumpkinseeds andgreen sunfish (figure 15). Black crappiehave also been managed successfully insome instances. Another commonlyraised warmwater fish is the channelcatfish. Various minnows are also classi-fied as warmwater fish. Some speciesmake excellent forage fish.

Largemouth bass (Micropterussalmoides). Largemouth bass are themost commonly stocked species inwarmwater ponds. They adapt to a widerange of pond conditions, can grow quitelarge and are a very popular game fish.Their growth rates are influenced byfood supply, competition with other fishand water temperature. They growfastest when the water is above 75˚F.

Bass prefer minnows as forage overbluegills and other panfish. They tend togrow and reproduce better where theyare stocked with minnows.

Largemouth bass may live for 10–13years, though the average pond hasvery few older than 5 years. Mostfemale largemouth bass first spawnwhen they are 2–4 years old, or about10 inches long. Spawning occurs in Mayor June when the water is between60˚–70˚F.

To form a nest, the male either sweepsa shallow circular depression in thebottom or cleans off a clump of grass-like aquatic plants by fanning with histail. Males select nest sites at depthsbetween 2–6 feet. The nests usually aredeveloped near overhanging logs orother cover.

The male fertilizes the eggs as thefemale scatters them on the nest. Heguards the embryos and newly hatchedfry, which school near the nest until theyare well developed (about one week).

Numbers of fry hatched per nest varyconsiderably. An average of 4,375 wasfound in one study. Young bass eatwater fleas, insects and very small fishand crayfish. An adult will prey onalmost any available animal that fits inits mouth, such as fish, crayfish, tad-poles, frogs, worms and insects. Youngbass make an excellent forage foradults. By preying on their own young,largemouth bass can live successfully ina pond or small lake without otherspecies. They also hold their numbers incheck reducing the risk of overpopula-tion, stunting and poor fishing.

Survival of largemouth bass embryosand fry in the nests may be reduced bysudden drops in water temperatureduring the spawning period. Smalleradult males are also less successful indefending their nests against predation.They can be overwhelmed by largenumbers of bluegills or other species.Competition for food, predation, reducedwinter pH and starvation during winterall influence first year survival.

Food competition with other fishes suchas young bluegills can cause mortalityby reducing the growth of first yearlargemouth bass. Those that do not getbig enough starve or are killed by preda-tors during the winter. Young bass areextremely inactive during the winter anddo not feed even if food is plentiful.

Smallmouth bass (Micropterusdolomieui). Smallmouth bass are best-suited for ponds that have clean gravelbeds for spawning and somewhat coolerwater than is best for largemouth bass.For these reasons, old gravel pit pondsoften furnish excellent smallmouth bassfishing. Smallmouths are sometimesclassified as a “coolwater,” rather thanwarmwater, fish. Many anglers like small-mouth bass better than largemouthbecause they fight harder. Their feeding,growth, reproductive habits and manage-ment are roughly similar to those oflargemouth bass. Their young are proba-bly more susceptible to mortality by pre-dation in systems overpopulated withbluegills. The fry are black and conspicu-ous. Smallmouth young are also subjectto winter pH stress and starvation.

21T Y P E S O F F I S H T O R A I S E I N W I S C O N S I N S P O R T F I S H I N G P O N D S

Figure 14. Largemouth and smallmouthbass. The latter is especially suited towater where the temperature is a bit toocool for largemouth bass but too warmfor trout.

Bluegill (Lepomis macrochirus). Thebluegill is probably the fish stocked mostfrequently in warmwater ponds. Bluegillsare caught easily, are good scrapperson light tackle and are very tasty. Theyalso provide fast action for kids.However, pond owners who wish tostock bluegills should be cautioned that,although several years of good fishingwill probably follow the initial stocking,intensive management is required tomaintain desirable body growth.Bluegills breed prolifically, overpopulatethe pond and severely overgraze thefood supply, decreasing growth. Evenwhen stunted, they remain prolific.

Bluegills feed on a wide variety oforganisms, including insects, waterfleas, fish eggs and small fish. Rootedaquatic plants and algae have also beenfound in their stomachs. However, plantmaterial provides little if any of theirnutritional needs. Bluegills, like all othernorthern game fish, must meet theirnutritional needs by feeding on otheranimals. Growth varies, dependinglargely on how crowded they are. Underfavorable conditions, they reach 6inches in 2–3 years but in many ponds,they reach this size only after 4–6 years.

Female bluegills reach sexual maturityby the second to fourth summer of lifeand produce 6,000–27,000 eggs peryear, depending on their size. Bluegillsspawn over almost any type of bottom inwater 1–3 feet deep, starting in May orJune.

Spawning occurs at slightly higher tem-peratures than in largemouth or small-mouth bass and continues into earlysummer. As with bass, the male bluegillbuilds and guards the nest. Nests areusually shallow depressions in thebottom, 6–12 inches in diameter andclose together. The average nest con-tains about 18,000 fry which may comefrom more than one female.

Females mature at different times, andthe eggs from a single fish ripen gradu-ally. A female may deposit eggs inbatches over a period of several weeks.The long spawning season assures thatthere will be offspring even if adverseconditions occur during parts of it.

Black crappie (Promoxis nigromacula-tus) and white crappie(P. annularis).Black and white crappie possess manyof the characteristics of other membersof the sunfish family (figure 15). Crappieshave been managed successfully insome ponds and small Wisconsinprivate lakes.

Under the appropriate conditions,crappie grow faster and larger thanbluegills. They spawn earlier thanbluegills and their spawning period ismore restricted, reducing the probabilityof overpopulation. They eat water fleas,insects and minnows and feed in moreopen water. Therefore, they do better inwaters with fewer rooted aquatic plants.They are not generally suitable forsmaller ponds (less than 6 acres).


Figure 15. Panfishes.

Hybrid sunfish. Hybrid sunfish are arti-ficial crosses, usually between greensunfish females and males of otherspecies like bluegills or redear sunfish. Ifthe fish farmer producing the hybrids isvery careful in selecting the parents sothat only female green sunfish and onlymales of other species are present inthe breeding pond, the resulting off-spring should range from 65% to nearly100% males.

Since most hybrid sunfish are male,reproduction is reduced in ponds thatcontain only hybrids. Under these condi-tions the hybrid sunfish may grow fasterthan normal bluegill sunfish.

Do not stock hybrid sunfish under thefollowing conditions:

■ If normal bluegill or green sunfishare already in the pond. The hybridscan back-cross with their parenttypes since the hybrids are fertile.

■ If the ponds already have a stuntedsunfish population. They willcompete for the same food and willnot grow very fast. They will alsobreed with the stunted fish.

■ If the pond is shallow and weedy.The weeds will provide places for theyoung of the hybrids to avoid preda-tion. Overpopulation will be fore-stalled by only a few years.

Channel catfish (Ictalurus punctatus)(figure 16). Interest in stocking catfish inWisconsin ponds has increased. This isdue largely to extensive catfish farmingthat developed in southern states in the1960s.

Catfish have certain drawbacks in north-ern ponds. They do not generally spawnsuccessfully in these ponds unlessspecial spawning structures areinstalled. They also grow slowly com-pared to their counterparts in the South.

The catfish is a truly warmwater fish thatgrows fastest in water over 80˚F. Butcatfish will still grow large enough toprovide recreational fishing in manysouthern Wisconsin ponds because theynormally reach 12 inches after 3–4years. Females usually mature at 13–16inches in length.

When the water temperature reaches75˚F, catfish spawn in cavities such asthose found beneath undercut banks orin hollow logs. The male guards theembryos and fry until they school andleave the cavity.

Catfish eat many types of food, bothliving and dead: insect larvae, crayfish,snails, worms, clams, fish and variousitems that fall into the pond.


Figure 16. Channel catfish and bullheads.

Forage fishSmall fish, such as minnows andshiners, may be stocked as forage forbass and catfish, though this won’talways be necessary. Trout don’t needthe forage and the small fish usuallycompete for food with the trout.Therefore, planting forage fish in cold-water ponds is not recommended.

The most suitable bass forage speciesare the fathead minnow (Pimephalespromelas), the bluntnose minnow (P.notatus) and the golden shiner(Notemigonus crysoleucas). These allfeed on plankton and insects and willreproduce in ponds if there is suitablespawning habitat.

All three species spawn when they are2–3 inches long. Normally, they spawnseveral times throughout spring andsummer. Spawning starts when thewater warms to 65˚F in areas 1–2 feetdeep. Golden shiners deposit their eggson aquatic plants and sometimes inbass nests. Fathead and bluntnoseminnows lay eggs on the undersides ofrocks, tiles, boards or logs. Fathead andbluntnose minnows are repeat spawnersand males protect the embryos duringdevelopment, thus increasing survivalrates and the forage supply.

Although these forage species are pro-lific, bluntnose minnows seldom exceed 4inches in length, and fatheads, 3 inches.They are easy prey for largemouth andsmallmouth bass which can wipe themout if the bass population is not held incheck or there is not enough dense coverto protect reproductive populations.

Golden shiners attain a maximum lengthof about 10 inches so their populationsare less likely to be depleted by preda-tion. But if many golden shiners in thepond reach 6 inches or larger, they maycompete with young bass for food.

Fish not recommended for Wisconsin ponds The most common problems forWisconsin pond and small lake manage-ment are the presence of too many fishand undesirable species (figure 17). Ifyou are managing a pond for sportfishing, there are two important things toremember:

1. The food resources of ponds arevery limited. Placing too many fish ina pond destroys the food supply.

2. Fish have the capacity to multiplyquickly. Introducing a small numberof a new species “to see what willhappen” often results in the expen-sive task of removing and disposingof thousands of unwanted fish a fewyears later. In addition to the costs ofremoval (if removal is feasible)fishing can be harmed for manyyears. To produce a usable crop thefocus should be on managing forone or a few species.

Unwanted species can be introduced ina variety of ways. Well-meaning childrenor neighbors may transfer fish from near-by ditches or lakes. Fish may also enterfrom nearby waters during periods offlooding. They may be introduced inad-vertently when stocking game or foragefishes. Pond owners should learn toreadily identify undesirable fish and try tokeep them out of their ponds. Any fishnot included as part of the managementplan should be viewed as undesirable.

Some species present special problems.The spines of bullheads (Ictalurusmelas, I. natalis and I. nebulosus)protect them from predation, allowingthem to take over a pond within a fewyears. Young bullheads are often mixedin with forage fish or fingerling game fishbeing stocked. Inspect these carefully toweed out bullheads.

Carp (Cyprinus carpio), suckers(Catostomus spp.) and various nativeminnow species can also be mixed inwith fish destined for stocking. Theycompete for food and prey on the eggsof gamefish. Carp are bottom feederswhich stir up the water, hampering sight-feeding by gamefish.

Fish such as walleye (Stizostedionvitreum) and northern pike (Esox lucius)are often introduced to control an abun-dance of stunted bluegills. This approachis seldom effective because bass are verysusceptible to predation by these species.Therefore, introducing them often resultsin fewer bass but no change in bluegillpopulation numbers or growth rates.

Yellow perch (Perca flavescens), pump-kinseed sunfish (Lepomis gibbosus) andgreen sunfish (Lepomis cyanellus), likebluegill, tend to overpopulate ponds andbecome stunted. Use these fish only inlakes or larger ponds where largemouthbass over 12–14 inches are present andtheir numbers are maintained throughcatch and release fishing. Additionalcontrols may also be required to preventoverpopulation and stunting, such asdestruction of nests, trapping andremoval of young (see Chapter 10).


Fathead minnow

Golden shiner

Bluntnose minnow

olive gray color

silvery gold colorlarge scales

deeply dipping lateral line

spotolive back above

dark stripeblack spot

Exotic speciesMany species of fish exist in the worldwhich are not native to Wisconsin andmost would not survive here in the wild.However, certain species have thepotential not only to survive, but toreproduce. They become a nuisance,often destroying populations of nativefishes. To protect the state’s resources,Wisconsin has passed laws that prohibitimporting and transporting species notnative to the state either as eggs,larvae, juveniles or adults.

The common carp is the best exampleof an exotic fish species that producesadverse effects. The European ruffe isalso established in Wisconsin waters ofthe Great Lakes and is doing extensivedamage. The grass carp (white amur),Japanese weatherfish, ide, rudd, bitter-ling and tench are other exotics that arepresent in U. S. waters and couldreduce the abundance of native fish.

Besides fish, two exotic plants—curlyleaf pondweed and Eurasian water-milfoil—invade Wisconsin ponds andcan cause serious nuisances. Purpleloosestrife, a wetland exotic plant,invades wetlands adjacent to ponds anddestroys wildlife habitat. A number ofother exotic species like the zebramussel, spiny water flea and rusty cray-fish are present in Wisconsin waters,ready to invade ponds of the unsuspect-ing.

Introduction of unwanted species is amajor problem in pond management.The pond owner should learn to recog-nize “exotics” and undesirable nativespecies and take special care to guardagainst their introduction.

Pond owners also have a responsibilityto ensure species are not released fromtheir ponds into natural waterways. Eventhe release of native species could altera natural system by increasing competi-tion, changing predator-prey dynamicsor introducing diseases or parasites.


Figure 17. Some of the fish best kept out of ponds.

Implementing pond managementKeeping recordsA pond logbook is invaluable for record-ing and reviewing water quality condi-tions, the kinds of fish stocked, theirsource, weed treatments that worked,the costs of stocked fish or treatments,and the success of each managementactivity. Visits from wildlife, catches andfish sizes should also be recorded(figure 18).

In addition to a written logbook that youcan carry with you in the field, a com-puter spreadsheet helps maintainrecords of water monitoring information,costs, the number and size of fishstocked, the numbers of fish caught,their size and the hours you and othersspent enjoying the pond.

You are not likely to remember all of thisinformation without good record keeping.In addition to being a key part of themanagement process, reviewing thepond records may be one of the rewardsthat you and other family membersreceive for your investment in pondmanagement.

Figure 18. Pond logbook.

Dec. 15, 2001: Finished construction of pond.Figured total costs at $3,000 on spread-sheet.

Dec. 17, 2001: Pond full. Water flowing overstop logs. Measured at 85 GPM.

Jan. 15, 2002: Pond 2⁄3 frozen over. Oxygen 8ppm at surface pH 7.5.

April 10, 2002: Finished smoothing areaaround pond and seeded with grass and cover.Installed fish screen at stop logs.

April 25, 2002: Stocked 125 13⁄4–2-inchrainbow trout.

June 20, 2002: Algae forming along edge ofpond. Removed with rake.

Aug. 15, 2002: Temperature at surface 58˚F;bottom 52˚F; air temp 90˚F. Trout visiblealong shore around 6 in long. Muskrats inpond.

Oct. 1, 2002: Stocked 100 6-in trout fromFairweather Hatchery.

Oct. 20, 2002: A lot of muskrat activity.

chapter 6 chapter 6

27I M P L E M E N T I N G P O N D M A N A G E M E N T

Selecting the best fish for the pondThe best pond will not produce a goodcrop of fish if the species is not suited tothe pond’s conditions. Evaluate yourpond conditions before you select fish tostock. Record your observations in alogbook so that you can make soundjudgements.

Water temperature is probably the mostcritical factor in determining the kind offish to manage. The water sourceshould give some indication of whetherthe pond is suitable for trout or warmwa-ter species. Unless you are sure, it isbest to measure water temperature on ahot summer afternoon a foot below thesurface near the center of the pond. Tryto read the thermometer at that depth(the reading can change rapidly if it isbrought to the surface) or collect alarger volume of water and immerse the

thermometer in it, or use a sampler fordissolved oxygen measurements. If thenear surface temperature is more than70˚F, the pond is probably best suitedfor warmwater fish.

Similarly, you can obtain a bottom tem-perature by lowering a screw-top jar orcan full of water, with a thermometer pro-truding through the lid to near the bottomfor two to three hours (figure 19). Readthe bottom temperature when you bringthe jar to the surface. If the bottom tem-perature is the same as that on thesurface, you know that the pond is mixingand there should be oxygen at all levels.If it is above 74 ˚F, the pond is too warmfor trout.

In the case of borderline temperatures,try trout. They often do well in a border-line pond for several years until the dis-solved oxygen content of the water fallstoo low (under about 5 parts per million)from accumulated organic matter.

Since trout are not likely to reproduce inthe pond, it will be easy to switch to awarmer water species if the trout plant-ing fails. This is not true of warmwaterspecies that will live and reproduce incolder ponds but do not grow well. Trytrout only before you stock any otherkind of fish. This will avoid competitionfrom warmwater species.

In borderline cases you can economizeby using only a token stocking of adozen or so fish per acre; then followtheir progress by catch-and-releasefishing. If they survive and grow well thefirst year, stock more.

Dissolved oxygen should be above 5parts per million (ppm) for coldwater fishbut can be as low as about 3–4 ppm forwarmwater species during summer. Coldwater holds more oxygen than warmwater; therefore the higher levels requiredby trout are not generally a problem if thewater is cold enough and stock densitiesare not high.

Oxygen is more plentiful in deeper pondsand in those where plant nutrients arelow to moderate. Dissolved oxygen willprobably not remain at or above 5 ppmduring winter months under the ice inWisconsin ponds. However, the metabo-lism of fish is lower during winter. Cold-water fish should survive at 2–3 ppm.Warmwater species will generally survivein ponds even when dissolved oxygenfalls to 1–2 ppm during late winter.

In some Wisconsin ponds, pH may be aproblem. Few fish grow well in acidicsystems at pH 6 or below. You shouldsuspect low pH if the water is bog-stained or if the pond was constructed inan area that was previously a bog.

Low pH can also occur in ponds in sandyareas fed primarily by rain water. Liming issometimes used to raise the water’s pHand alkalinity to counteract acidity prob-lems. Liming also allows the pond tohandle phosphorus fertility in ways thatboost production of fish rather than of nui-sance bluegreen algae (see Chapter 4).High pH can also be a problem in somefertile ponds. On a sunny afternoon, pHcan reach 9.5 because of carbon dioxidedepletion. This can aggravate problemswith ammonia toxicity.

Figure 19. Bottom temperatures can be obtained by lowering a screw-top jar orcan of water to the bottom and leaving it until its temperature is the same as thesurrounding water. Then take the temperature of the contents when it is broughtto the surface.

27


Where to get fish for stockingCarefully consider and investigate thesource of fish for your pond. Purchasingfish from a licensed game fish breeder(licensed hatchery) is usually theeasiest, most economical and safest inthe long run. You can get the fish at justabout any time, in the numbers youneed and at the appropriate sizes. Youwill also reduce the chances of introduc-ing unwanted plant and animal species.

For coldwater ponds, purchasing troutrepresents the obvious choice. A list oflicensed Wisconsin game fish breedersis available at no cost from theWisconsin Department of Agriculture,Division of Trade and ConsumerProtection (see Chapter 16). Check withseveral hatcheries. In addition to com-paring prices, you may wish to visit themto see how the fish were raised and toevaluate their quality. Some breedersare registered as “disease free “and thismay be a factor to consider. Recordprices and other relevant information inyour logbook.

It is possible to catch fish for planting ina warmwater pond. However, bear inmind that you will want the fish to befree of unwanted parasites and in goodcondition. The stress that fish undergowhen they are caught, held in a cooleror on a stringer and transported to yourpond could make them unsuitable forstocking.

You might also obtain fish from someoneelse’s pond or from public waters. In thelatter case, you must adhere to all statelaws. You are also required to registeryour pond as a fish farm to catch andtransport game fish to plant in your ownwarmwater pond (see Chapter 15).

Anticipating fish manage-ment activities and costsIn addition to assessing what kind of fishto plant and the costs and benefits ofvarious stocking options, you will want toestimate the need for other manage-ment activities and their costs.Subsequent chapters will help youdetermine the fish management activi-ties that will probably be required topromote the success of your pondproject. Developing an understanding ofthe alternatives and their costs will befacilitated by the same kind of carefulassessment required to build a good fishpond. Keeping careful records in yourpond logbook will help you make goodchoices.

Determining whether aeration isneeded and how much it will cost arequestions you should evaluate beforebeginning your pond management. Ifdissolved oxygen levels are at or nearthe minimum required for the desiredspecies, aeration can increase oxygenconcentrations.

The most common and inexpensivemethod is to circulate the water by anair-lift system. A stream of air bubbles isinjected near the pond bed in the deeperpart of the pond. Rising bubbles drawbottom water toward the top, creating avertical circulation of water. At thesurface, the oxygen-poor water takes onoxygen from the atmosphere. Surfacewater circulates to the bottom to replaceit. The bubble stream can be producedby a compressor powered by electricity.In some instances wind-powered com-pressors are used. Air passes through ahose along the pond bed to an air stoneor other dispenser. A variety of air-lift cir-culation systems are sold for lake andpond use.

Aeration systems should be designed tomeet the specific needs of each pond.One risk with circulating a trout pond insummer is that the entire pond may bewarmed beyond trout’s tolerance limit.There are special devices for aeratingonly the deep, cool part of the pond,without mixing it with warm surfacewater. Aeration may also keep part ofthe pond’s surface unfrozen in winter.This can help protect the outlet pipefrom damage by freezing. However, theopen water and thin ice increase a pondowner’s liability. If aeration is needed,part of the assessment process shouldinclude determining how you will protectpeople, livestock, pets or wildlife fromthe open water and thin ice areascaused by winter aeration.

For occasional use, consider cascadeaeration (pumping water over a cascadebox), using a power take-off or engine-driven pump.

Knowing the costs of getting power tothe pond site, aeration equipment, thetime the equipment will be running andrelated operating costs will help imple-ment successful fish management onponds that need aeration.

Managing coldwater ponds for sport fishingThe main steps in managing coldwaterfish ponds include:

1. Stocking small trout

2. Fishing for them when they grow to adesirable size

3. Restocking as the population diminishes

Restocking is usually done annually, butcan be done less often if you don’t fishmuch and the trout survive otherhazards. Annual stocking with fingerlingsor yearlings is often good because itcreates an interesting population withfish of different ages and sizes. Keep inmind that trout do not reproduce in mostponds, so replenishing the populationdepends on stocking. See Chapter 5 forinformation about the different kinds oftrout.

Trout usually grow best on a diet ofinvertebrates such as freshwater shrimp(Gammarus), water fleas, insect larvaeand crayfish. They do not thrive whenthere are other kinds of fish in the pond.Bass, pike and catfish eat largenumbers of trout. Panfish, bullheads,suckers, carp and even the smallestkinds of minnows compete with trout forfood. When competitor fish are in apond, trout growth and survival is poor.

Before stocking the pond, refer toChapter 6 to determine whether thepond can support trout.

StockingPreparing the pond for stocking isusually not necessary for a new, prop-erly built pond (Chapter 3). If you areconverting an old pond to support troutor readying a renovated trout pond, youmay need to do certain things beforeyou begin stocking.

If other kinds of fish are in the pond,remove them (Chapter 10). Screeninlets and outlets to prevent the smallestfishes from entering. Maintainingscreens can be quite a problem, so it isfar better to build the pond without con-nections to other surface waters thatharbor fish. Caution children and friendsnot to introduce minnows, panfish, gold-fish or any other fish.

You may wish to combine a re-diggingoperation with a fish-removal drawdown.Dragline digging with the pond bedexposed and somewhat dry may bemuch cheaper than suction dredging ordraglining when the pond is full.

Even if you don’t dig the pond deeperduring a drawdown, take advantage ofthe situation to rake out aquatic plantsand debris. Reducing organic matterusually improves a pond for trout. SeeChapter 11 for plant control methods.

The best times to stock are April, Mayand possibly June because water tem-peratures are still moderate and naturalfood organisms are increasingly abun-dant. Fish planted at this time tend to dobetter and start growing sooner.

You can also stock trout in Septemberand October when the pond is becomingcooler. However, there is less chance forgrowth because the pond soon becomestoo cold. Fall stocking is usually doneonly in new or redredged ponds—orwhere unwanted fish have been eradi-cated during the summer.

Fall-stocked fish that live on natural feedgenerally look and taste better thannewly stocked fish. Fall-stocked troutmay die during harsh winter conditions,but the losses may be outweighed bythe much lower cost of fall fingerlings.

Stocking trout in summer is inadvisabledue to the risk of thermal shock that cankill many or all of the planted fish.

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Suggested numbers and sizes oftrout to stock for populations that willgrow well on natural food supplies aresuggested in table 4. Only one of thetypes listed should be stocked in oneyear, although “adult” trout can berestocked as often as they are fishedout.

A common mistake is stocking too manytrout, which results in poor growth. Thecurrent recommended stocking rates areconservative and lower than often sug-gested in the past. We believe it is farbetter to risk starting with too few troutthan to risk ruining the food supply. If thetrout are fast-growing and stay plump allyear, stocking can be done at a some-what higher rate the next time.

The number and size of trout to stockdepend on an individual pond’s condi-tion: the amount and size of troutalready present, how fast they are to beharvested, the food supply and whethernatural reproduction occurs. Adjuststocking from year to year according topast experience and current conditions.

Infertile ponds may support only about20–25 pounds of trout per acre. Veryfertile ponds may sustain upwards of150 pounds per acre on the natural foodsupply.

Pond capacity for trout production canbe increased several fold by supplemen-tal feeding, and then you may raise thestocking rate. However, feeding cancause various problems (see page 31).

As a rule, the larger the trout stocked,the greater the percentage that surviveto be caught—and, of course, thesooner there will be fishing for big trout.Whenever you stock, consider using thelargest fish that the budget allows. Priceper stocked fish rises sharply withincreasing size, but the number neededto adequately stock the pond decreases.

Experimenting in the pond over theyears should reveal the best sizes andnumbers to stock. Your logbook recordswill be extremely useful in assessingwhich size to stock and how well fishfrom different sources grow. You cancompare growth rates with regionalaverages using figure 20 (see page 32).Calculate the cost per-pound-caught, orper-fish-of-desirable-size caught. Youmay find that these costs decrease ifyou stock fish somewhat larger than thesmallest, cheapest ones available.

The first time you stock a new or reno-vated trout pond, it may be most eco-nomical to use spring fingerlings. Plannot to fish them until the next springwhen they should be 7–8 inches long.However, you may want to do some testfishing in the interim.

If you want an initial springtime stockingto provide more immediate fishing, use6- to 7-inch yearlings. In excellentponds, they will grow an inch a monthduring spring, summer and fall.

For restocking in ponds with establishedtrout populations, don’t use fish smallerthan fall fingerlings (5–6 inches ). Therewill be fewer losses to cannibalism bytrout that have survived from previousstocking. Annual restocking may providefar more consistent fishing than restock-ing at greater intervals.

Inspect the trout before planting themto be sure that they are healthy. Don’taccept fish that are obviously diseased,that appear weak or behave abnormally.Fish stressed by improper handling andtransport will die soon after stocking.Even under the best conditions, 10–20percent of the stocked fish may die inthe first 2–4 weeks.


Table 4. A guide for stocking trout to achieve maximum growth without additional feeding and aeration.

Type of Size in Number to Time totrout inches stock per acre stock Comments

Spring fingerlings 2–3 200–300 April–May Least expensive. May be hard to get. Only for initial stocking of new pond or one which has had all fish removed.

Fall fingerlings 5–6 50–150 Sept–Oct For initial stocking or restocking.

Spring yearlings 6–7 50–150 April–June For initial stocking or restocking. More expensive than fingerlings.

“Adults” over 7 25–50 spring or fall For initial stocking or restocking. Can be very expensive.

*The lower number is for ponds with alkalinity less than 50 ppm or that will be lightly fished. The higher number is forponds with alkalinity over 150 ppm and/or will be heavily fished; hence, more rapidly “thinned out.”

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You may need a special hatcherylicense to transport your own fish. If youdecide on this approach, keep the waterat a rather constant low temperature(50–60˚ F). Cool weather greatlyreduces handling stress. Besides beingcold, the water must be well-oxygenatedand unchlorinated. You may use smallaeration devices that operate on batter-ies or automobile current—or you canattach a tube with a clamp valve and air-stone to a spare tire. Cool the containerof water (plastic trash cans work well)with ice. However, never place ice madewith chlorinated tap water in with yourfish. It is usually most convenient andreliable to let the dealer deliver the fish.

As mentioned, stocking trout in summeris not advisable. Since trout must betransported in water that is much colderthan the summer surface water of mostponds, they may undergo lethal temper-ature stress in the warm upper layers ofthe pond and oxygen stress in the coolwater below. Resulting deaths may notbe evident immediately, but may occurover several hours or days.

If more than a 6˚F difference existsbetween transport water and the pond,“temper” the trout to the new water grad-ually. To do this, add small amounts ofpond water to the transport tank until itswater is at pond temperature. If youtransport the fish in plastic bags (oxygenpacks), trash cans or other small con-tainers, set them in the pond until thewater inside is the same temperature asin the pond. If the transport bags havebeen filled with oxygen and tied off, donot open the bag (unless fish are in dis-

tress) until tempering has been accom-plished and you are ready to release thefish into the pond.

Flushing the trout through a large tubefrom the transport truck directly into thecold pond depths is another way toreduce thermal shock, but few dealershave such equipment. All in all, it is bestnot to stock in summer.

When to start fishing andhow much to harvestDo some catch-and-release fishing peri-odically to see how the trout aregrowing. Recording their sizes in yourlogbook allows you to estimate theirgrowth rates. Start keeping fish as soonas you start catching some of desirablesize. A reasonable size at which to startharvesting is 7–10 inches. If you delayharvest until the fish are much larger,your total return may be severelyreduced. This is because loss of fish bynon-fishing or “natural” causes usuallyoccurs rapidly, especially in the case ofrainbow or brook trout and few live to beover 3 years old.

The more fish that are taken by angling,the fewer that can be lost to othercauses. The greatest yield of fish andenjoyment is usually obtained by doingmost of the harvesting in the seasonwhen the trout reach 7–10 inches.Review your records over the years tosee how best to spread out the harvestto get the desired results.

Under a “put-grow-and-catch” manage-ment scheme, trout grow while theharvest is spread out over the seasoneach year. You should be able to harvestan amount of trout about equal in weightto the total poundage that exists in thepond at the start of summer. This isbecause the remaining trout grow enoughto compensate for mortality.

A put-and-take fishery may be appropri-ate for ponds where temperatures aresuitable for trout only in spring and fall.Under “put-and-take” management forrapid catch-out of stockings of trout,many times more pounds of trout can becaught than the pond can support. Butyou will never catch as many pounds oftrout as were stocked. There isn’t timefor the trout to make use of the foodsupply and to grow enough to compen-sate for post-stocking mortality. The costper pound of fish caught will be higherthan in a put-grow-and-catch manage-ment program.

Supplemental feedingSupplemental feeding shouldn’t beneeded if you follow the stocking ratesin table 4. At these densities, the troutshould have enough natural food tosustain desirable growth.

Higher population densities can bemaintained if feed is added. Somepeople keep as much as 5,000 poundsof trout per acre in hard water pondswith artificial feeding—and harvest thatamount annually. This can only be donewhere a strong supply of spring waterkeeps temperatures low and rapidly

replenishes the oxygen consumed bydecaying feed and fish wastes.

However, there are disadvantages tosuch intense management. Once thepopulation is built up to the levelneeding feed, the trout must be fedalmost daily during the growing season.“Feedlot” conditions may be created,and the pond’s appearance couldbecome unpleasant. Excess feed andthe unavoidable large amounts of troutfeces raise water fertility to levels thatcan cause undesirable algae growth.The accumulation of unused feed, troutwaste, living and dead plant matter anddecayed microorganisms in the pondconsume large amounts of dissolvedoxygen. Having too little oxygenhampers trout growth and can kill themif the problem is severe enough. In soft-water ponds especially, excess enrich-ment can cause fluctuations of pH whichare intolerable for trout. High trout densi-ties also attract predators, particularlybirds.

If you must feed supplementally, give nomore feed at one time than the trout eatimmediately. This minimizes the residueof unused feed and reduces cost.

Convenient pelletized dry feed is avail-able. However, use only food especiallymade for trout. Feeds for other animals(such as chickens) don’t have the ingre-dients in the right proportions and won’twork. In most cases, floating pellets arebest. They stay up where trout can findthem longer—and where you can seewhen they have had enough.

Special aquatic plant control in trout pondsKeep the amount of algae and rootedplants in trout ponds moderately low.While water plants produce oxygen indaylight, they consume it at night. Anoverabundance of plants, together withdecaying dead plants, may reduce dis-solved oxygen levels below the trout’sneeds, especially on hot summer nightsor under winter ice cover. See Chapter 10for information on aquatic plant control.

CAUTION: Trout are generally moresensitive to chemicals used to kill algae(algicides) or rooted plants (herbicides)than are warmwater fish. Some of thesechemicals kill trout at the concentrationsneeded to kill plants. Be very carefulwith the common algae control chemi-cal, copper sulfate, in trout ponds. Youneed to know the water hardness todetermine whether copper compoundscan be used safely. Other copper com-pounds such as Cutrine (chelatedcopper) also require extreme care.Before buying any chemical for killingaquatic plants in a trout pond, obtain theappropriate permits and determine theeffect on trout. It is safer to removeplants by mechanical means (seeChapter 11).


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0 100 200 300 400 500 600

4 8 12 16 202500

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1/2

3/4

1/4

500

1000

1500

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Trout—inches

millimeters

po

un

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ms

Figure 20. Determiningwhether a trout is the properweight for its length.

Weigh the fish to the nearest halfounce or 10 grams, if less than1⁄4 pound. If heavier, it may beweighed a bit less accurately.Measure length to the nearest 1⁄8inch. Plot length on the horizon-tal scale and lightly pencil a ver-tical line there. Plot weight onthe vertical scale and draw alight horizontal line there. If thepoint where the two lines inter-sect lies on the heavy curvedline, the fish is of standardweight for its length. If the pointlies above the curve, it is heavierthan average. If it lies below thecurve, the fish is underweight.

Managing warm-water pondsfor sport fishingSelecting the rightfish speciesMost warmwater fish do well at summerdissolved oxygen concentrations of 5ppm and temperatures between70˚–80˚F. Typically these warmwaterponds have less water flow; thereforethey need greater depth (15 ft) tosustain oxygen concentrations abovethe level required for winter survival.Managing warmwater ponds is mademore difficult by many species’ highreproduction rates. Overproduction ofsmall fish and stunting are major prob-lems, though less so in larger ponds orsmall lakes (6–10 acres). Managing forone or two species also greatlyincreases your chances of avoidingproblems.

Stocking While stocking is not the only importantaspect of management, the type of fish,the number stocked, their body size, andthe time of stocking will do much todetermine fishing quality, especially inthe first 3–5 years. Special details onstocking various kinds and combinationsof fish are given and summarized intable 5. For more information on thebiology of each species, see Chapter 5.

Largemouth bass, bluegill and otherpanfish usually won’t need restocking,since they reproduce well in mostponds. Adding to established popula-tions of these fish generally results inloss of the newly stocked fish due tocompetition and poor growth. You mayhave to restock smallmouth bass, andwill likely need to restock channelcatfish.

Bass (largemouth or smallmouth)without other fish. In ponds lackingother fish that compete for food, bassthrive on worms, insect larvae and cray-fish. They also feed heavily on their ownyoung which helps keep their populationunder control. We strongly recommendtrying bass alone. If their growth isunsatisfactory, you can always add forage fish.

Smallmouth bass work better than large-mouth bass where water is on the coolside. Smallmouth bass may also dobetter than largemouth in new or reno-vated ponds that haven’t yet developedmuch forage. Smallmouths often don’tspawn successfully, because they prefergravel and the young seem to requiremore dissolved oxygen than largemouthfry.

Bass with forage minnows. Stockingfathead minnows before stocking bass issafe if you carefully remove allunwanted species beforehand. Fatheadminnows are recommended, since theydon’t grow larger than 3 inches. You canalso use bluntnose minnows.

Golden shiners also work well, butsometimes grow too big for bass to eat.If large bass are not maintained in thepond as recommended in this publica-tion, golden shiners may become tooabundant and compete with young bassfor food. If bass deplete the minnowpopulations in a few years, you canstock more and reduce the size of thebass population by fishing.

Restocking minnows should always bedone carefully so that unwanted specieslike bullheads are not unintentionallyintroduced. Scattering the minnowswhen stocking serves to reduce immedi-ate predation. A moderate amount ofrooted plants in the pond gives minnowscover from bass predation and usuallyallows enough to survive and reproduceto maintain their populations. Installingtile pipes or raised spawning boardsalso aids minnow reproduction.

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Channel catfish and minnows.Channel catfish grow slowly and seldomreproduce in Wisconsin ponds. Theymust usually be restocked for continu-ous fishing. If shelters such as milkcans, kegs or closed pipes are provided,they may occasionally breed. Use thesame kinds of minnows recommendedfor bass forage. Sometimes, for variety,channel catfish are added to a pondcontaining bass and/or panfish. If adultbass are present, use catfish larger than7 inches to minimize predation. Bassand panfish will prey on any catfish fryproduced.

Largemouth bass and bluegills orcrappies. Largemouth bass in combina-tion with bluegills is a favorite in south-ern states, where it works in smallponds (0.5–3 acres), but it has beenless successful in the North. Bass aresupposed to control bluegills by preda-tion, but it doesn’t work that way in ourclimate, particularly in smaller ponds.Bluegills overpopulate the pond, result-ing in stunted growth of both bass andbluegills. If you want bass and bluegills,give the bass a 1- to 2-year headstart ongrowth. The combination works better inlarger ponds and small lakes if the bassharvest is greatly restricted.

In Wisconsin, crappie may be a betterchoice than bluegill in combination withbass. Because crappies spawn earlierand their reproduction period is shorter,there is less chance for overpopulation.In addition they tend to use the openwater of a pond where they are moreavailable to bass. However, too fewpond owners have tried this combination

for it to be fully evaluated. Some ownershave had good success with crappies inlarger ponds.

Bluegills or other panfish withoutbass. This results in overpopulation andstunting even sooner than the bass-bluegill combination. If a bluegill-onlypond is desired, consider stocking onlyfingerlings. This delays the onset ofstunting by giving the initial populationsome time to grow before it producesoffspring which compete with theparents for food.

Hybrid sunfish with or without bass.Artificial crosses between green sunfishfemales and other species of sunfish (forexample, bluegill and redear) may havethe advantages of hybrid vigor and arepredominately male. With reducedreproduction, the food supply and roomto grow are maintained. But beware—purebred sunfish are usually includedamong the hybrid fingerlings stocked.These purebreds and the hybrids canspawn and start the pond on its way tooverpopulation. Their offspring typicallygrow much slower than native sunfish.Still, overcrowding can be delayed forseveral years—with excellent fishing inthe meantime. The advantages can beextended if the hybrid sunfish arestocked with largemouth bass becausethe bass prey upon the limited numberof sunfish offspring. Hybrids are of littleor no value when stocked in the pres-ence of existing panfish populations orin shallow weedy ponds.

If large (6 inches or more) hybrids arestocked, they may improve fishing bychanging the size structure of thesunfish population, particularly if youpractice catch and release fishing.

You should check with your area DNRfish manager before stocking hybridsunfish. Because green and redearsunfish are not found in some areas ofWisconsin, and the offsping of hybridsgrow slowly, stocking is restricted.

Exotic species include fish and otherorganisms such as crayfish not native toWisconsin that are sometimes desiredby pond owners. All of these, such asgrass carp, tench and Japanese weath-erfish, are illegal and have the potentialto damage your pond and adjoiningpublic waters (see discussion in Chapter 5).


Table 5. Stocking guide for Wisconsin warmwater ponds to achieve maximum growth without supplemental feeding and aeration.

Number to stock Length Kind of fish per surface acre (inches) Time of year

Largemouth or 100 fingerlings* 2–4 July–Augustsmallmouth bass alone or

25–50 yearlings 6–10 April–Octoberor

6–8 adults (both sexes) 12 October or May

Bass with minnows 500 adult minnows, then, 2–3 April-Mayafter minnows spawn, stock bass as above

Channel catfish 500 adult minnows 2–3 April–Maywith minnows after minnows spawn

-100 fingerling catfish 2-4 July–August

Largemouth Stock bass as above; 1–2 July-Augustbass** with after 1 or 2 years bluegills or crappie 500 fingerling bluegills

Bluegill or other panfish 500 fingerlings 1–2 July–Augustwith NO bass THIS ALTERNATIVE IS

NOT RECOMMENDED

Hybrid sunfish 400–800 fingerlings 1–3 July–October

* Reduce by half if water alkalinity is less than 50 ppm

**Don’t use smallmouth bass; they eat very few bluegills.

Angling harvestDelay bass harvest until the fish havespawned once. This ensures that theyare well established before other fish(especially panfish) disrupt the foodsupply. It may mean waiting 2–3 years ifyou stock fingerlings; 1–2 years if youstock yearlings; or until mid-June of theyear following stocking of adults.

If you stock 100 bass fingerlings peracre, expect around 25–30 adults peracre after 2 full summers in the pond.The original bass stocked as fingerlingsmust support the first 5 years or more ofthe pond’s bass fishing. Therefore,harvest them lightly!

Light harvest means not removing morethan 20–25 pounds of bass per acreeach year. Recording the length andweight of all fish taken in your pondlogbook is essential to determining whenthis level of harvest is reached. After theyear’s quota is taken, you can still enjoythe pond by changing to catch-and-release fishing. Recording informationabout caught-and-released fish is alsouseful in estimating growth and changesin growth.

There are many ways to manageharvest in an established Wisconsinbass pond, especially if panfish havealso been stocked. Since panfish caneasily overpopulate and stunt inWisconsin ponds, it is important toprotect the bass that are panfish preda-tors. Bass 12- to 16-inches prey on 3- to5-inch panfish effectively .

The easiest way to ensure that thesepanfish predators are available is torelease all 12- to 16-inch bass. Whenthe pond contains a healthy populationof this size bass, you can harvest a few10- to 12-inch bass (25–30cm) as wellas those over 16 inches. Harvestingsome of the 10- to 12-inch bass will helpselect for the fastest growing fish. Sinceslower growing fish will be 10–12 inchesfor a longer time than the faster growingfish, they are more likely to be caughtthan the faster growing fish.

Any time that bass of a certain sizeappear thin and poorly fed, harvest bassof that size more heavily. If a bassweighs less than 95% of the standardweight for its length, it is too thin. Usefigure 21 to check whether your bassare of standard weight. Here again,keeping good records of the length andweight of the fish you catch is essential.

Channel catfish. If you stock channelcatfish as fingerlings, start harvestingthem in the second or third year afterstocking, after they have reached 9–l0inches. If the catfish population is one ofthose rare ones in Wisconsin that sus-tains itself by natural reproduction,remove only 10–15 fish per acre eachyear. Usually, however, replenishment isaccomplished by annual restocking, andall fish caught above whatever sizepleases the owner can be harvested.

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Figure 21. Determiningwhether a bass or bluegillis the proper weight for itslength.

Weigh the fish to thenearest half ounce, if lessthan 1⁄4 pound. If heavier, itmay be weighed a bit lessprecisely. Measure length tothe nearest 1⁄8-inch or mil-limeter. Plot weight on thevertical scale and length onthe horizontal scale. Draw ahorizontal line lightly withpencil at the fish’s weightand a vertical line at itslength. If the point wherethe two lines intersect is onthe heavy curved line, thefish is of standard (oraverage) weight for itslength. If the point liesabove the curve, it isheavier than average. If itlies below the curve, thefish is underweight.

Bluegills and other panfish. Start har-vesting as soon as they are a size youlike. In new ponds or those where fishhave been eradicated, some bluegillsstocked as fingerlings should exceed 4inches the next summer and 6 inchesthe summer after that. Follow twoharvest rules:

l. Remove as many fish under 6inches as you can.

2. Greatly restrict the harvest of fishover 6 inches. This works againstovercrowding and helps superiorbrood stock survive. Just as withbass, the biggest, fastest growingbluegills bite most readily and tendto be caught first.

Figure 21 shows how much bluegillsshould weigh at each length. If thebluegills are thin or growing too slowly,suspect overcrowding. Apply increasingcatch rates and other population controltechniques (see Chapter 10).

The bass-bluegill combination. Followthe procedures outlined in the abovesections on bass and bluegills. Harvestat least 4 pounds of bluegills for eachpound of bass harvested. This helpsbass keep the upper hand longer. It isespecially important to restrict harvest ofbass over 16 inches. At that length, theymay be nearly 2 pounds and are proba-bly just beginning to eat enough bluegillsto have an effect in controlling theirnumbers. Have fun catching large bassand releasing them alive. Try to build upa substantial population of bass weigh-ing 3, 4 and 5 pounds.

No matter how intensively you managethe bass-bluegill pond, bluegills may stillsimply take over. Bass spawningsuccess will decline, large bass andbluegills will disappear, and there will behordes of small bluegills—all about thesame size. When this occurs, the owneris often tempted to plant more andbigger fish—maybe even walleye ornorthern pike. Resist such impulses!Walleye and northern pike are generallynot suited to life in small warmwaterponds (Chapter 5), and the only cure forstunted panfish is a sound program ofpopulation control (Chapter 10).

Not recommended: higher stocking levels and fish feeding Adding pellets, bread or other fish foodmay increase fish growth in a pond—butit can also accelerate the growth ofalgae and other aquatic plants to exces-sive amounts. The result may be notonly unsightly and interfere with fishing,but a build-up of organic matter in thepond may cause oxygen depletion andfish die-off.

If you wish to do some supplementalfeeding, use demand or ring feeders toreduce food loss. Because you areadding nutrients, supplemental feedingshould be done in moderation and incombination with other populationcontrol measures. Higher stocking levelsmay lead to the fish outstripping thenatural food supply. Although many fishwill eat pelleted fish feeds, it is usuallybest for pond health, appearance andyour pocketbook to manage so that thefish are sustained by the food thatoccurs naturally in the pond.

Pond fertilization and limingFertilizing and liming are generally notrecommended for Wisconsin sportfishing ponds. Fertilization here usuallycauses excessive weed and algaegrowth, resulting in plant control prob-lems (Chapter 11) and a lack of dis-solved oxygen for fish.

Never use fertilizer to create algalgrowth to stifle rooted plants, as is donein the South and in commercial aquacul-ture ponds. Such enrichment is sostrong that it poses the grave risk of win-terkill of fish.

Liming is sometimes used to raise thewater’s alkalinity to counteract acidityproblems or to allow the pond to handlephosphorus fertility in ways that boostfish production rather than that of nui-sance bluegreen algae (Chapter 4).Fertilizing and liming ponds should bedone only under the direction of a waterchemistry expert who understands theproper balance between alkalinity andphosphorus content and who can deter-mine the right dosage of phosphorus orlime.

Emergency aeration of the pondChapter 6 describes ways of injecting astream of air bubbles at the deepest partof the pond to circulate the water andkeep sufficient dissolved oxygen in thedeep zone. This procedure can be usedto rescue fish from a temporary oxygencrisis, such as on hot summer nights orduring an especially hard winter.

Aerators are particularly useful in pre-venting winterkill of fish. The circulationachieved by the bubble stream or apump and cascade aerator systemmaintains an open area of ice-free waterthrough which the pond can take onoxygen. However, an aerator should notbe needed in a properly designed sportfishing pond. The open water resultingfrom winter aeration can represent asafety and liability problem.


Managing pondsfor commercial fish productionGeneral considerationsThe four basic methods commonly usedto raise fish for profit are:

1. Flow-through systems, which gen-erally consist of a set of tanks, con-crete or earthen raceways or poolswith a large volume of fresh watercontinuously flowing through them.This is how most Wisconsin trout areraised.

2. Water reuse or recirculationsystems, which are normally builtindoors and rely on continuous waterpumping and filtration. (These workin a manner similar to that of mosttropical fish aquariums.)

3. Open-pond culture, in which fish areraised unconfined, and in ponds thatare usually designed and built specifi-cally for commercial aquaculture.

4. Net-pens, in which fish are confinedin cloth or plastic mesh cages; gen-erally located in large bodies ofwater or ponds.

Regardless of the method used, com-mercial aquaculture in Wisconsin is reg-ulated by both the Department ofAgriculture, Trade and ConsumerProtection (DATCP) and the Departmentof Natural Resources (DNR).

DATCP is responsible for the annualregistration of fish farms, import permitsfor live fish and eggs and for all mattersrelated to fish health and processing.DNR regulates fish stocking into publicwaters, water use, water discharge andimportation of non-native fish. Both ofthese agencies should be contactedearly in the planning stage. You shouldalso contact the University of WisconsinSea Grant Institute, which supports agreat deal of aquaculture research.

Of the four methods used for commer-cial aquaculture, open pond culture isusually the most economical way toraise fish if you can meet a givenspecies’ environmental requirements.Primarily because of this economicadvantage, pond culture is responsiblefor more than 60% of total worldwidefish production. A good example of asuccessful large-scale industry based onpond culture is the production of channelcatfish in the southern U.S.

In Wisconsin, commercial aquaculturehas traditionally used a combination offlow-through and pond culture techniquesto raise coldwater trout. Most open-pondaquaculture currently involves raisingcoolwater and warmwater game fish fin-gerlings and baitfish. Production of foodfish, particularly yellow perch, has alsobegun. Net pen culture is being exploredand may have potential.

In contrast to many other uses of ponds,such as recreational fishing, swimmingor scenic enhancement, the primarygoal of commercial aquaculture is tomake a profit. The importance of carefulplanning cannot be overstated for a suc-cessful commercial aquaculture venture.The planning process includes an accu-rate business prospectus and enterprisebudget.

Planning Careful planning may take years, but itshould be viewed as a mechanism bywhich you can develop much of theknowledge and skill essential to makingyour business a success. It is a way toenter the business before you actuallyinvest in it. Planning helps you learnabout the species you plan to grow, themarket for your products, what isrequired in terms of time and money, aswell as potential rewards and problems,both short- and long-term.

The planning process helps you decideif commercial aquaculture is the bestinvestment of your time and resources.Entering any business without theknowledge and skills developed throughcareful planning usually leads to busi-ness failure and financial loss. It canalso result in the loss of self-confidence,friends and even family.

chapter 9 chapter 9

The planning process (figure 22) shouldhelp you develop understanding andskills in:

1. Producing the product(s)

2. Operating a business, including mar-keting the product

3. Developing the financial resourcebase

4. Developing the personal supportbase

Throughout the process you shouldmaintain good records of the informationyou have reviewed. These records willserve as a guide in developing the busi-ness prospectus and for implementingyour plan.

Planning production of aquacultureproducts. For many, an interest inaquaculture starts with a strong desire torear a preferred species. The importantquestions to ask yourself are:

■ Can I rear the species in commercialquantities?

■ Can I sell the product at a price thatwill earn an acceptable profit?

You may find that the probability ofsuccess would be higher with otherspecies or a combination of species, orby combining aquaculture with market-ing the products of other producers. Youwill then need to decide if you have theinterest to go ahead with the project.

We suggest starting with a broad per-spective and investigating a variety ofaquaculture alternatives. For example,starting with the idea of bait culture isbetter than focusing on one species ofbait. This approach will increase yourbreadth of knowledge about aquacultureas a business, and thereby increaseyour chances of success.

Efficient production of large quantities offish or other aquaculture speciesrequires detailed knowledge of thespecies. Unless you have previous train-ing with the species and the aquacultureindustry, you will need to start gatheringreliable detailed information on thegroup or species you may be culturing.

You also need to develop enough expe-rience to correctly interpret how theinformation applies to your potentialbusiness venture. Although most of thechapters in this publication focus onpond management for sport fishing, theinformation provides a good startingpoint for developing a basic understand-ing of pond management.

After reviewing this publication you willneed to develop much more detailedinformation about the culture of appro-priate species at the high densities char-acteristic of commercial aquaculture.You will want to study information ontemperature-oxygen requirements andmanagement, growth under differentfeeding regimes, mating behavior, eggincubation techniques, the varioussources of stock, diets, feeding behaviorand techniques, potential diseases andtheir control. The reference section listssources of more detailed information.

In addition to reading, getting up-to-dateinformation on commercial aquaculturerequires interacting with those already inthe business. Contacting or joining theWisconsin Aquaculture Association (seethe list of references, p. 76) is an excel-lent starting point. Members, the group’smeetings and its newsletter, the Creel,provide invaluable information on aqua-culture in Wisconsin. In addition, thenewsletter is an excellent way to learnabout state, regional or national meet-ings that introduce the most recent infor-mation on aquaculture techniques andproducts. Having up-to-date informationon culture techniques and products iscritical to your business plan.


fish cultureknowledge

businessmarketing

personalsupport

fiscalresources

Figure 22. Aquaculture planning.

Careful consideration to the fourareas identified below will help youdetermine the feasibility of an aqua-culture business and develop theknowledge required to make gooddecisions regarding commercialaquaculture.

Presentations at aquaculture meetingscan provide key information essential tomaking your business a success.However, you must know how to interpretthe information correctly. For example, aresearcher’s success in growing a certainspecies under research conditions shouldnot be interpreted as evidence that thefish can be grown under less controlledconditions at a profit.

Investors should continually remindthemselves that the researchers devel-oping better aquaculture techniques areoften enthusiastic about their new find-ings. Also, research presentations areusually narrow in scope so one or evena few presentations are not likely to tellyou everything you need to know to rearthe species successfully.

Presentations and published informationis often provided by for-profit consultantsand persons selling equipment and sup-plies to the industry. Although such infor-mation may be honest and accurate,keep in mind that the livelihood of thesource depends on your purchases. It isessential to get the latest informationfrom several sources covering the rangeof important topics.

After you have gathered, summarizedand reviewed the information, askanother key question: Is anyone elseoperating this type of business success-fully? If the answer is no, you will wantto find out why. If the answer is yes, itsuggests the species can be raised prof-itably in Wisconsin. The next step is tofind out all you can about how the suc-cessful businesses operate.

Business planning and marketing.There is a saying: “You cannot makemoney raising fish.” Aquaculture is likedairy farming—you not only need toproduce the product, you have to sell itfor more than it cost to produce.

Each individual must decide how muchprofit is acceptable. To determine profit,you will need to evaluate productioncosts, the costs of marketing the product(including getting it to market ) and itsvalue in the marketplace. You need tounderstand that aquaculture is a rela-tively new agricultural business in theU.S. and definitive information is notreadily available on the production costs(dollar investment) and/or market values(dollar return) for many fish species.Accordingly, rough estimates of invest-ments and returns are often used forplanning purposes. When using suchestimates, a sound business plan shouldbe conservative; that is, the cost figuresshould range toward the high side andthe returns should range to the low side.

You will want to look at alternative pro-duction methods not only in terms of theamount and quality of the product pro-duced but in terms of production costs.Production costs include the expense ofpond construction, water management(pumping and aeration), animals forstocking, feed, harvest equipment,chemicals or fertilizers and outside help.Do not overlook insurance, office sup-plies, technical services and equipmentmaintenance. For most businesses,there are start-up costs to cover theoperation’s expenses before the firstcrop is brought to market. For example,

if you are growing yellow perch inWisconsin, you could expect a minimumof two years before you produce anyproduct.

Carefully assess accurate information onthe product’s market and current markettrends. Do not rely upon figures quotedby those promoting the industry. Find outwhat people will pay for your product.

Generally speaking, one of the advan-tages of aquaculture is that relatively fewpeople are involved in it. But the marketin your area may be highly competitiveor may need to be developed. Becauseaquaculture is a small industry, manyproducers do their own marketing andtransport their product to the market.

Developing a market takes some skilland may require considerable time. Infact, skill in developing the market maybe just as critical to success as produc-ing the product. Before investing you’llwant to know who will buy the productand what price they are likely to pay.You will also want to learn about thelong-term market projections for yourpotential product.

Plan ways to develop the market for thevarious products you could raise. Thecost of transport equipment, marketingmaterials and the time, travel and othercosts associated with market develop-ment should be included in the businessprospectus. You will want to develop aplan to expand production and theproduct’s market over a several yearperiod. Contact your county Extensionoffice for help in developing a businessplan.

Planning the personal support base.While commercial aquaculture is pro-moted by the Wisconsin Department ofAgriculture, Division of ConsumerProtection (see the references listed atthe end of this publication) it is importantto clearly understand the kind of govern-ment and private support available if youinvest in such an enterprise. Thoseinvolved in traditional agriculture knowthat appropriate feeds, a neighbor’splow, the local vet and the county agri-cultural Extension agent are available toassist them as needed. That level ofinfrastructure is not yet available tothose investing in aquaculture.

You may need to contact individualsacross the state or country to obtain thesame kind of help available locally tothose in traditional agriculture. Touch basewith the many people with whom you willneed to work before you invest. Getting toknow people in the business well enoughto work with them on marketing, buyinglarge quantities of food at a lower price orsharing equipment helps reduce yourcosts, increases production and the priceyou get for your product. In addition toWisconsin Aquaculture Associationmembers, get acquainted with other pro-ducers in your area, those who sell prod-ucts you may need, aquaculture researchscientists in the region and localUW–Extension, DATCP and DNR staff.You will also find a wealth of informationon the Internet (see references).

39M A N A G I N G P O N D S F O R C O M M E R C I A L F I S H P R O D U C T I O N

Like traditional agriculture, the successof many aquaculture businesses inWisconsin depends on the commitmentof an entire family. If the kind of opera-tion you envision involves other familymembers, it is important to include themin the planning process, making surethey understand the business and theirroles in it fully .

Approaching the planning process as afamily promotes development of oppor-tunities that might otherwise be over-looked. For example, one family wasinterested in buying a property equippedwith a coldwater fish pond. However, thepond could not make a profit if it wasmanaged for food fish production. Aftersome careful planning, the family real-ized that the property could be commer-cially profitable if fee-fishing on the pondwas paired with the operation of a bedand breakfast. The family membersdecided this was something they couldcommit to together. Approaching theplanning process in this manner isimportant to success.

Planning the financial needs. Thesoundness of a business plan andprospectus will considerably influencethe financial resources available to you.Contact the Wisconsin Department ofCommerce for information on low-inter-est loans. The amounts to be borrowed,the interest rates and the risk associatedwith borrowing should all be assessedcarefully as part of the planning process.

To reduce risks and the cost of bor-rowed money, investigate a variety ofscenarios. It is not uncommon forsomeone new to aquaculture to startsmall by initiating a low investment pilotproject before making a major invest-ment. This approach reduces risk andstart-up cost while increasing the aqua-culturist’s hands-on experience.

Water temperature and species selectionThe choice of fish species to raise isusually dictated by market; in otherwords, select species you can sell at aprofit. From a biological perspective, themost important criteria for selectingpond species is water temperature.Simply put, the temperature of a ponddictates which species will survive andgrow well.

Ponds in most locations have an annualtemperature cycle that depends on theclimate. For example, the water temper-atures in most Wisconsin ponds arebelow 45˚F from December throughMarch and range from 65˚–85˚F fromJune through September. The growthrate of fish depends largely on tempera-ture, so it follows that the growth of fishdepends on the season and does notoccur uniformly throughout the year.

When considering species and climate,a primary goal should be to keep watertemperatures as near as optimal for thespecies’ growth as possible. A generalrule of thumb for commercial aquacul-ture is that the growing season shouldbe at least 180–200 days per year.However, each fish species has amaximum temperature that cannot beexceeded for even a short time withoutcausing serious disease problems andheavy losses. Some warmwater fishalso have a minimum temperature belowwhich they cannot survive.


In Wisconsin, only very deep ponds orthose with substantial groundwater inputremain cold enough to raise coldwaterspecies like trout and salmon throughoutthe year. Most other Wisconsin pondssimply get too warm in the summer tosupport coldwater fish. Cool waterspecies, such as yellow perch, walleye,northern pike, muskellunge and sometypes of baitfish are probably thespecies best suited for Wisconsin pondculture.

For these coolwater fish, the water tem-perature should never exceed 80˚–85˚F.Well-designed ponds should be able tomeet this criteria, and a growing seasonof 180–200 days is possible for coolwa-ter fish, at least in the southern part ofthe state. You can raise some warmwa-ter fish, such as catfish and bass inWisconsin ponds, but the growingseason for warmwater fish is muchshorter than in southern states.Accordingly, pond culture of warmwaterfish is more economical in the Souththan in Wisconsin.

Site selectionThe source of the water is a main con-sideration in selecting a site for pondaquaculture.

Compared to the other methods of fishculture, ponds require a moderateamount of water. On average, pondculture requires about 50 times morewater to rear each pound of fish thanrecirculation systems. Flow-throughsystems, in turn, require about 50 timesmore water to rear each pound of fishthan do ponds. To estimate the amountof water needed for pond culture, keepin mind the following calculation: At acontinuous flow rate of 50 gallons perminute it will take approximately 22.6days to fill a one-acre pond to a depth offive feet, assuming that no water is lostthrough seepage or evaporation andnone is added via rainfall or runoff.

The two primary sources of water forponds are groundwater and surfacewater; either can be used. Ground- orwell water has the advantage of a rela-tively constant temperature (rangingfrom about 44˚F to 52˚F in Wisconsin);therefore it can be used to cool ponds inthe summer and to warm ponds andminimize ice buildup in the winter.

Groundwater also contains relatively fewnutrients, pollutants or unwanted organ-isms. In many or most locations,however, groundwater must be pumpedinto ponds, adding additional expense.Permits are needed from the DNR tooperate high-capacity wells.

Surface waters such as rivers and lakescan often be used without pumping, butcan vary greatly in temperature through-out the season, and may containunwanted chemicals and organisms.You should also consider that divertingtoo much water from a stream can alterits temperature and flow, thus changingthe species that it supports.

A third source, which has yet to be usedin Wisconsin, is the heated dischargefrom industry, particularly facilities thatgenerate electric power. This source hasthe potential to extend the growingseason to 365 days per year.

Water discharge is another major factorto consider when you select a site for acommercial fish pond. Most commercialponds discharge water from time totime, or at a minimum must be drainedoccasionally (such as at harvest time).The DNR regulates these discharges.The regulations vary and depend on thespecies and quantity of fish produced,the amount and type of nutrients dis-charged, and the water quality of thereceiving waterway. For example, theregulations and restrictions for discharg-ing into trout streams with outstandingwater quality are generally much morestringent than for discharging into largewarmwater rivers. Wetlands and crop-

lands can also be considered potentialwater discharge sites.

Regardless of the factors above, all newponds should be subject to the best rea-sonable management practices to mini-mize the discharge of potential pollu-tants. Settling ponds are very effectiveat minimizing the chemical and biologi-cal effluents discharged from ponds andare relatively inexpensive to build.

The land itself is an important considera-tion for selecting a site for pond aquacul-ture. Before discussing the relationshipbetween the land and ponds, however, itshould be emphasized that the cost ofbuilding a pond is often the largest singlecapital investment made in the develop-ment of a pond-based fish farm—moreexpensive even than purchasing theland. Accordingly, the cost of construct-ing the pond will have a major impact onthe farm’s ultimate profitability.

Pond construction costs are directlyrelated to the amount of material thatmust be moved, as well as how oftenand how far it is moved. The cheapestway to move earth is with a bulldozer ora self-loading earth mover, which mighttypically cost $0.75–$1.50 per cubicyard. It is more expensive to use a backhoe, and it costs even more if the soilhas to be moved long distances withdump trucks. This may cost upwards of$3–$5 per cubic yard.



Land requirements vary greatly depend-ing on the type of pond you want tobuild. Construction of the three types ofponds—excavated ponds, impound-ments or watershed ponds, and leveeponds—are described in Chapter 3.

Excavated ponds are being used suc-cessfully for commercial aquaculture inWisconsin, but they may not be the bestchoice for commercial fish farming. Theyare expensive to build and difficult orimpossible to drain, thereby impeding anumber of pond management strategiesimportant to commercial fish culture.

Watershed ponds are currently used toraise fish in some parts of the country,but are not commonly found inWisconsin. They can be built only inspecific locations, and usually have anirregular shape that can make them diffi-cult to manage. Construction costs,however, can be quite low.

Levee ponds are the most common typeof pond used for commercial fishfarming. They are well-suited for aqua-culture because of their relatively lowconstruction costs and because theycan be built with regular shapes andsloping bottoms to permit complete andrapid draining. The best location for alevee pond (those where constructioncosts are lowest) is a flat area with adeep layer of clay subsoil. For any typeof pond, plastic liners can be usedinstead of clay to prevent seepage, butpond liners typically cost$10,000–$20,000 per acre or more. In

Wisconsin under appropriate conditions,a 3- to 5-acre levee pond suitable foraquaculture can be built for $3,000 peracre or less; a 1- to 2-acre pond can bebuilt for approximately $6,000 per acre.

Pond design and constructionPonds used for aquaculture inWisconsin can range in size from lessthan 1⁄4 acre to more than 5 acres.Larger ponds are less expensive to buildper acre, but ponds larger than 5 acresget progressively more difficult tomanage. One problem with very smallponds is that water quality and otherfactors change more rapidly than inlarge ponds (see Chapter 3). On theother hand, problem conditions in smallponds can be more rapidly correctedthan in large ones. Normally, smallerponds are best suited for raising finger-lings, small or bait fish, while largeponds are better suited for growing largefish.

The exact shape of a pond is oftendetermined by the topography and prop-erty boundaries of the land. Most aqua-culture ponds are rectangular. Squareponds are somewhat less expensive tobuild than rectangles, but rectangularponds, particularly if they are large, areeasier to manage.

Ponds built for commercial aquacultureare generally shallower than recreationalponds, primarily to reduce constructioncosts. If aquaculture ponds will be usedyear-round, they should be a minimumof 7 feet deep. This helps prevent win-terkill and also reduces excessivewarming during summer hot spells.Smooth-bottomed ponds with an ade-quate slope from the shallow to thedeep end allow for complete drainageand easy fish harvest. See Chapter 3 formore detail on levee pond construction.

Managing for different types of fishTrout. Wisconsin’s aquaculture has his-torically revolved around trout produc-tion. Most trout production takes place inareas with high water flow using flow-through raceway systems. Thesesystems allow high densities of trout tobe raised using intensive artificialfeeding programs because the waterflow removes waste rapidly. Ponds areused for grow out, holding fish and feefishing. Pond management for commer-cial fee fishing operations is somewhatsimilar to the techniques described inChapter 7 and will not be treated furtherhere.

Fingerling game fish. Small fish fry andfingerlings of many species depend onzooplankton and/or phytoplankton astheir initial food source. Fingerling pondsare often fertilized to increase theamount of plankton available andthereby the number of fish that can beraised.

Inorganic fertilizers including liquid orsoluble phosphorus and nitrogen stimu-late phytoplankton growth. Organic fertil-izers, such as alfalfa, soybean meal ormanures stimulate phytoplankton growthto some extent, but also promote thegrowth of bacteria and protozoans,which in turn are consumed by zoo-plankton. Often a combination of organicand inorganic fertilizers are used.

The optimum amount and frequency offertilization varies greatly from pond topond, depending on the pond’s naturalfertility. Ponds used by the University ofWisconsin Aquaculture Program at theLake Mills State Fish Hatchery are fertil-ized weekly with 50–250 pounds ofsoybean meal and 5–10 pounds of 54%inorganic phosphorus and 46% inor-ganic nitrogen per acre. Take care not toover-fertilize ponds, as this will depletedissolved oxygen.

The number of fingerlings or small fishthat can be produced depends on thespecies as well as fish size at harvest.For yellow perch, 200,000 fingerlingsper acre can be produced if the fish areharvested at 3⁄4 inch. Many walleyehatcheries average 80,000–120,000 fishper acre if the fish are harvested at 11⁄4inch. When perch and walleye are har-vested at 2 inches or more, the numberof fish drops to 30,000–50,000 per acreor less. The fingerlings of walleye, large-mouth bass, smallmouth bass and otherspecies are usually marketed to organi-zations that plant them in public andprivate lakes.

Grow-out. When the fish are 3⁄4 inch to11⁄2- inch long, some species learn toaccept commercially available formu-lated feeds. For larger fish, a floatingdiet is a great advantage in pond culturebecause you can readily observe thefeeding response of the fish and avoidoverfeeding. Some fish species, likeyellow perch, readily accept floatingfeeds only if they are fed when thereisn’t much daylight (near dusk anddawn).

Currently there is little definitive informa-tion on how many pounds of fish can beraised per acre in Wisconsin ponds.These limits are determined by themaximum amount of food that can beput into a pond before dissolved oxygenis depleted. Catfish farmers in the Southtypically raise 4,000–5,000 pounds ofcatfish per acre.

In several trials, University of Wisconsinresearchers successfully raised 4,000pounds of yellow perch per acre whilelimiting the amount of water added tothe pond to the minimum needed fortemperature control. In another trial theyraised 10,000 pounds per acre usingsufficient flow-through to exchange theentire volume of the pond every 2–3weeks.

Bait. Fish bait production represents thelargest aquaculture business in thestate. Bait producers grow approxi-mately one-third of commercially soldbait fish. Two thirds is harvested fromthe wild. Baitfish that are grown mayhave several advantages, such asincreased uniformity and better healthand “shelf life,” compared to those thatare harvested from the wild. The amountof wild harvest versus production varieswith the species. For example, suckersare hatched from eggs and the fryplanted in coolwater ponds or raceways.Fathead minnows are typically har-vested from wild ponds but the pondsare managed somewhat similarly tothose used for fingerling gamefish. Thepotential for using existing ponds lowersthe cost of bait production.

Water quality and harvestOxygen and aeration. One of the mostimportant routine management proce-dures of pond culture is to regularlymeasure dissolved oxygen concentra-tions just before sunrise, particularlywhen potential dissolved oxygen deple-tions are anticipated. Because of highfertility in commercial ponds, regularoxygen monitoring is much more criticalthan in recreational ponds.

Many types of mechanical aerators areused in pond culture. Some devices areused primarily to circulate the water in apond, others provide continuous activeaeration and others are of the stand-bytype, used only under emergency condi-tions when dissolved oxygen is depleted.

In general, intensive aeration devicesare becoming more popular in pondculture because they can increase fishproduction. It is important to recognize,however, that most oxygen in a pond isnot used directly by the fish but ratherby bacteria, plankton and plants.

Aeration and water circulation systemsprovide several significant benefits topond culture. First, because of the largequantities of nutrients added to them,ponds used for intensive aquacultureoccasionally suffer from dissolvedoxygen depletion. During extreme situa-tions catastrophic fish losses result ifremedial action is not taken. Second,without top-to-bottom water circulation,ponds frequently stratify. Although strati-fication can be desirable in recreationalponds to increase habitat variety, inhighly fertile commercial ponds thewater at the pond bottom often loses all


its oxygen. Under these conditions,aerobic decomposition of waste prod-ucts, which is essential for maintainingthe high productivity of aquacultureponds, does not occur. Third, in northernclimates aeration is used to keep pondspartially ice-free and to prevent winterkill.

Adding water. At a minimum, somewater is added to aquaculture ponds tomake up for water lost through seepageand evaporation. Water flow-through isalso used to minimize ice formation andthickness in the winter. In summer, it isused to reduce pond temperaturesduring hot spells. Depending on theamount of water available, flow-throughcan also be used to reduce the overallnutrient loads in ponds.

Harvest methods. Several methods arecommonly used to harvest aquacultureponds. For a complete harvest, conducta drawdown along with seining orcapture in internal or external catchbasins. Catch basins are used toharvest small fish or fingerlings. The useof internal basins is usually restricted tosmall fish or fingerlings. Ponds thatremain full can be partially harvestedusing seines, trap nets or gill nets. Acommon technique to selectively harvestlarge fish from ponds is to use a size-selective seine in a partial pond draw-down.

Regardless of the method used, it isimportant to recognize that harvestingprocedures are very stressful for fish,due to physical and mechanical abra-sions as well as rapid changes in waterquality. If harvested fish are to be keptalive, every effort should be made tominimize the stresses of harvest.

For several reasons, commercial fishponds should be completely harvested,drained and allowed to remain dry for aperiod of time at least once everyseveral years. First, complete harvestallows for an accurate inventory of fish.Second, drying eliminates many diseaseand other organisms such as snails,salamanders and crayfish, that spreaddisease or can otherwise be detrimentalto fish culture. Third, the organic mate-rial accumulated on the pond bottomdecomposes quickly when exposed toair. If the buildup is excessive it can bemechanically removed.


Fish populationcontrol

Pond owners sometimes need toreduce or eliminate fish populationsbefore moving forward with manage-ment plans. Older ponds may

contain undesirable fish, such as carp,suckers or bullheads. A trout pond maycontain unwanted warmwater fishes. Apond that has suffered a winterkill mayhave a predator-prey imbalance. Orperhaps panfish are overabundant andstunted. When such situations occur,various methods exist to alter fish popu-lation structure or to remove fish popula-tions completely.

Angling intensivelyA common perception is that intensiveangling brings fish populations intobalance. That idea is fine in theory, but itseldom works except in very smallponds. The overabundant fish areusually not large enough to catch, orelse they are an undesirable speciesthat no one wants. The time required forintensive angling is also substantial. Toprevent overabundance or reduce thechances that undesirable species will beintroduced, follow the harvest sugges-tions outlined in Chapters 7 and 8.

Stocking predatorsSome people reason that stocking north-ern pike, muskellunge or walleyes con-trols stunted panfish. After numerousattempts however, there are no well doc-umented success stories with thisapproach.

Bluegills and other sunfish have deepbodies with a spiny fin along their backs.Predators need large throats to swallowthem. Even largemouth bass that attainthe necessary throat size at an earlierage than other predatory fish usually donot keep bluegill populations in check inWisconsin ponds.

All piscivorous (fish-eating) fishes, includ-ing the largemouth bass, prefer to eatcigar-shaped forage fish without spinyfins. Thus, they tend not to eat manypanfish until more favored prey, such asminnows, or young largemouth bassbecome scarce. Having northern pike inbass bluegill ponds often results in morepredation on bass than on bluegills. Eventhough they also have spines, bass areeasier for pike to swallow.

Introducing large predators rarely con-trols carp and suckers in ponds. By thetime these fish become a problem, theyare usually too large and numerous tobe controlled by piscivorous fish.

Destroying spawning bedsSome people control sunfish populationsby destroying the fish embryos, either byraking or trampling the nests. A largepercentage of the nests must bedestroyed for this technique to be effec-tive. Because most sunfish species areprolific and spawn over a long period,this method requires considerable effort.It is simple, however, and can be effec-tive in delaying or reducing overabun-dance problems, particularly when usedwith other methods such as properlymanaged largemouth bass populationsand/or seining, trapping or electrofishing.

SeiningFish can be removed by drawing aseine, or large vertical net, through thewater (figure 23). Seining is usuallydone by two people, each holding anupright that supports the ends of the net.Floats keep the seine top at the watersurface, and weights hold the bottomedge on the pond bed. The seine muststay tight along the pond bed, or fish willescape underneath. Therefore, the seineshould be deeper than those portions ofthe pond where it is to be used so that itwill “belly” without being pulled awayfrom the pond bed as it is drawn along.

chapterchapter 10 10

For seining, the pond bed should besmooth and free of snags such as rocks,logs and brush. Dense weed beds alsoimpede seining. Water-level drawdown(described later in this chapter) can aidseining by drawing the water away fromweed beds and other shore-zoneobstructions, as well as decreasing thearea and depth to be seined.

Small seines are especially useful onpanfish during the spawning period.Minnow seines, 15–40 feet long andavailable at sporting goods shops, areused along shorelines to remove panfishfry and fingerlings which concentratethere. Longer, deeper seines allowgreater coverage. Ready-made orcustom-built seines can be ordered fromvarious suppliers.

Use nylon netting. It is most rip-resistantand lasts a long time with little mainte-nance. However, sunlight rots nylonquickly so do not leave it exposed to thesun. For removing small panfish, usenetting with mesh 1⁄4- to 1⁄2-inch long.Smaller mesh isn’t necessary; in fact, itis harder to draw through the water.

If the seine spans the pond’s width, twopeople can draw it the length of thepond in one sweep. This is the most effi-cient method. If the pond is too wide forthat, pull the seines out from shore in anarc—using a boat if needed—and backto shore. Draw the arc tighter and intoshallow water or on to the shore. Drawthe seine so that the bottom edge staysahead of the upper edge. Many fishescape if a seine rolls up at the bottomas it is pulled along.

To salvage bass, large panfish orminnows and return them to the ponduninjured, leave a pocket in the seine inshallow water at the end of the haul,rather than dragging it ashore. Rolling orsandwiching the net can bruise fish andremove their slimy covering and scales,thus increasing their susceptibility todisease. Minnows are very prone tosuch injury—especially in hot weather.

To “thin out” populations of bluegills orother sunfish, seine frequently in thewarm season but after the young basshave developed enough so that they canwithstand capture without injury (whenthey are approximately 1 inch long).Remove panfish that are less than 6inches long, and return those larger than6 inches plus any bass or channelcatfish (not bullheads!). This amounts to

selecting for fast growing fish whilemaking room for growth to occur.Subsequent generations of fish shouldgrow faster if you use this strategy.

If possible, keep seining until about 80%of the pond’s estimated summerpoundage of panfish is removed.Estimating the total weight of panfish in apond is difficult, and you may wish toconsult a professional biologist for assis-tance.

Seining is hard work but can be fun. Itprovides useful information about thefish population. In your pond logbook,record the effort invested and thenumbers of fish removed. Also recordthe numbers of young and adult bassand larger panfish that were released,along with information on the foragebase. Remember that bass and carp,especially older ones, are adept atavoiding nets. When you seine up onlysmall bass or carp, don’t conclude thatbig ones aren’t there.


Figure 23. A seine and bag seine.

Seine

top line with floats

bottom line drawn ahead of top line

bottom line with lead weights

top panel prevents fish from jumping

Bag seine

47F I S H P O P U L A T I O N C O N T R O L

Live-trappingFish traps may be useful for reducingpopulations in ponds where seining isdifficult. You can make an effective trapusing 1⁄4- to 2-inch hardware cloth onwooden framing (figure 24).

Use traps with or without a “lead.” A leadis like a fence that typically extends fromthe center of a trap’s mouth to theshore. It guides fish moving along shoreinto the trap. A seine or seine material(with floats and weights attached) canbe attached to the mouth of yourwooden-framed traps to make a lead.Hanging gauze bags of bait, such asbread, oatmeal, dog food, soybean cakeor cottage cheese in traps increases thecatch. You can experiment with bait todetermine whether it improves on your

trapping success. This method addsnutrients and is often not necessary.

Place traps in shallow areas wheresmall fish gather. Set the traps at rightangles to the shore in water that is justdeep enough to cover them. Run thelead into shore. Fish moving along shorewill follow the lead to the opening andenter the trap. For panfish thinning, upto 10 traps per acre may be needed.

Remove the same amounts and sizes offish as described in the section onseining. Remove the fish from the trapsdaily to avoid stress and turtle predationon the desirable fish that you will want toreturn to the pond.

ElectrofishingFish are sensitive to electricity and are“galvanotactic.” That is, they move in thedirection of direct current (DC) electricity.Modern electrofishing equipment, operat-ing on this principle, makes it possible tocapture large numbers of fish with elec-tricity without injuring them. The fish swimtowards the probes of the shocker whereoperators capture them in dip nets.Because electrofishing works in areas ofrelatively heavy cover and is effective incollecting small or large fish, it can bevery useful in population control.

Bear in mind, however, that the electricalcurrent required for electrofishing can belethal to humans. This technique is noteffective in soft water and should not beattempted by the pond owner usinghomemade equipment. We recommendcontacting one of the many private con-sulting companies to evaluate your situ-ation and carry out the task. In addition,be sure that whomever you hire usesmodern, safe equipment and is coveredby insurance.

Drawing down the water level Draining represents a good method ofpopulation control in ponds that can bedrained easily. Not only are undesirablefish easily destroyed but desirable fishcan be saved and restocked. If the pondis formed by a dam with a proper watercontrol structure, draining should beeasy. With the appropriate bottom slopethe fish will come to the outlet areawhere they can be seined and sorted asthe water level drops .

Low head pumps or a siphon can beused in some ponds. Even if the pondcannot be completely drained, reducingthe water level in late fall so the pondfreezes to the bottom serves to controlunwanted fish populations. Seining canbe used to capture wanted fish. Thelength of time needed for the pond torefill should be carefully consideredbefore a drawdown.

Contact the DNR district fisheries expertwhenever you are considering a draw-down or other water release from yourpond. Permission from the DNR may berequired to drain or refill a pond.

Fish cannot be discharged with the pondwater to other waters except underspecial permit from the DNR, as thisconstitutes stocking. Unauthorized intro-ductions of fish can disrupt natural fishpopulations to the detriment of the publicinterest.

Figure 24. Various kinds of fish traps.

Screening the outlet and/or the ponddischarge to prevent fish from escapingis often necessary. Take care to ensurethat downstream waters or propertiesare not damaged by flooding, erosion orsedimentation. It is the owner’s respon-sibility to release the water in a judi-cious, reasonable and prudent manner.

Total drawdown is used to eliminate allfish from the pond. A special effort mustbe made to find fish that may takerefuge in residual puddles. Spot applica-tions of fish toxicant chemicals may helpattain a complete kill. Desirable fish,such as large bass, can usually be sal-vaged and kept alive for restocking ifother water for holding them is available.

Partial drawdown can concentrate fishso that predators like bass can becomemore efficient. This tactic depends onhaving enough predators to consume alarge portion of the unwanted fish. Withdrawdown, seining is also more efficient.Conducted properly, a partial drawdowndestroys overabundant aquatic plants.Predatory reduction of small fish is mosteffective if the partial drawdown is donefor a month or more in July or August.Carefully consider whether a partialdrawdown will increase the danger ofoxygen depletion and whether asummer drawdown will aggravateaquatic weed problems.

Fish toxicantsAnother method of reclaiming pondsfrom panfish overpopulation or the pres-ence of undesirable fishes is to kill allfish with a specially formulated chemi-cal—a fish toxicant* or piscicide. Thenstart anew by restocking after the waterhas detoxified. Some fish can be sal-vaged before or during treatment andkept alive in other water for restocking.The amount of chemical used and thecost can be reduced if the chemicaltreatment is made in combination with apartial drawdown. Because discharge offish toxicants into public waters is unlaw-ful, partial drawdown may be requiredfor ponds that discharge into publicwaters.

Partial treatments to remove only certainspecies or sizes of fish, or to merelyreduce rather than eradicate the popula-tion, can be done by applying specialdosages or by treating a portion of alarge pond. However, partial treatmentsare usually very difficult and generallyineffective.

Only two chemicals, rotenone andantimycin, are legally registered for useas fish toxicants. The commercial brandnames and best local sources can beobtained from your DNR district offices(see references). Federal law requiresthat only legally registered fish toxicantsbe used—and that they be applied instrict accordance with instructions on theproduct label. In Wisconsin, only alicensed applicator may apply thesechemicals. A DNR fish farm environmen-tal permit coordinator will be able to helpyou identify licensed applicators.

The amount of toxicant needed for totalremoval of fish may depend on severalfactors, including the kind(s) of fish to bekilled, the pond volume, water tempera-ture, water hardness, light conditions,abundance of aquatic plants andamount of other organic matter present.


* The chemical is absorbed into the fish’s gills and kills by interfering with respiration. This does not mean that the pond is made poisonous for humans, for any vertebrate animals other than fish, or for most invertebrates when used at the dosages prescribed for killing fish.

Aquatic plants and their control

Aquatic plants play essential roles ina pond. They provide oxygen andproduce the pond’s food web. Theyalso furnish cover for fish and

support organisms that fish eat.

A few well-spaced plant beds providesome prime fishing spots and certaintypes of vegetation attract waterfowl andother enjoyable wildlife.

Plants easily become overabundant.The disadvantages of too many pondplants include:

■ Unfavorable build-up of organicmatter on the pond bed

■ Nighttime depletion of oxygen

■ Daily changes in pH that are unfa-vorable to fish and other organisms

■ Too much cover for small fish to hidefrom predator fish, resulting in smallfish overpopulating the pond

■ Interference with fishing, swimming,boating and other activities—includ-ing seining to control fish populations

If less than a fourth of the pond’ssurface is covered by plants, there islikely no problem unless they interfereseriously with use of the pond. Evenmore vegetation may pose no threat tothe welfare of the fish.

Kinds of plantsIt is important to know the kinds ofplants in your pond so you can interpretchanges and prescribe the appropriateplant management measures. Pondplants are separated into two generalgroups: algae and rooted leafy plants.

Algae are single-celled plants orcolonies of cells lacking true roots,leaves or flowers. There are three typesof algae:

1. Planktonic algae drift free in thewater, are usually microscopic and,when abundant, make the water lookmurky. Their coloration ranges fromblue-green to green, to yellow andbrown, or even gray.

2. Filamentous algae are threadlike ornetlike. They may be small and free-drifting, but often occur as “mossy”growths on rocks or thick mats float-ing on the pond surface. Most scumsand mats contain bacteria and fungias well as algae.

3. Chara algae, also called muskgrassor stonewort, grow attached to thepond bed without true roots. Theyhave clustered needle-like projec-tions and are often mistaken for leafyplants. The two common kinds arechara and nitella. When mashedbetween the fingers, they feel grittyand give off a skunk-like odor. Thereis often a white or brownish crust oflime or “scale” on the plants. Chara

occurs under natural conditions assmall clumps about 6 to 8 inches tall.Under some conditions it forms acontinuous stand several feet high.Overabundant chara is a commonpond problem.

Rooted, leafy plants occur in threegeneral forms:

1. Submergent (or submersed) plantsgrow rooted in the bottom with mostgrowth beneath the water. Somehave a few leaves floating on thesurface. Many thrust blossomsabove the water. Common submer-gents are pondweeds(Potamogetons in many varieties),coontail and waterweed (Elodea).

2. Floating plants are characterized byhaving all or most of their leaves andflowers at the water’s surface withfree-dangling roots in the water orattached in the pond bed. Duckweedand water lily are examples.

3. Emergent plants (or emersedplants) such as bulrush, cattail andarrowhead, have stems and leavesthrust above the water. These growat pond margins and may extendinto the water several feet deep.


Planktonic algae (many species)—free-floating, usually minute, may besingle-celled or found in colonies. Whenabundant, may color the water murkygreen to brown—or in extreme cases,pea-soup green.

Filamentous algae (many species)—long strands, filaments or nets. Oftenform floating mats.

Chara algae (muskgrass or stonewort)—Upright plants attached to the pondbed. Roughly resemble rooted, floweringplants, but are really algal colonies withstems and whorled branches. Each jointof the stem consists of a single cell.Even-lengthed branches are clustered ateach joint. Chara algae occur in shallowwater having high alkalinity. They arerough to the touch. Feels gritty andgives off a skunk-like odor whencrushed between the fingers.

Submergent plants


Algae

Bladderwort (Utricularia species)—Tiny oval bladder near bases of finelydivided leaves. Often floats free underthe surface without roots. Found in cold,acid water. Flowers yellow or purple.

Naiad (Najas species)—Leaves occuras opposite pairs or whorled, verynarrow, toothed on edges. Commonlygrows in water 1–4 feet deep but some-times much deeper.

Waterweed or elodea (Elodeacanadensis)—Flat, thin leaves grow inopposite pairs or whorled. Commonlyused in home aquaria.

Water star grass (Zosterella dubia)—Looks like some narrow-leaved pond-weeds (Potomogeton), but leaves lack amid-vein. Flower is yellow, star-like.

Wild celery (Vallisneria americana)—Light green, ribbon-like leaves may beup to six feet long (but usually muchless), with tips floating on the surface.

Water milfoil (Myriophyllumspecies)—Leaves whorled on stem anddivided feather-like, not forked as incoontail.

Hornwort or coontail (Ceratophyllumdemersum)—Whorls of leaves at jointsof stems. Leaflets forked once or more,have toothed edges. Leaves denselycrowded near tip of stem. Grows in hardwater.

Floating plants

51A Q U A T I C P L A N T S A N D T H E I R C O N T R O L

Floating leaf pondweed(Potamogeton natans)—Two types ofleaves. Underwater leaves are narrow,grasslike and appear as stalks. Floatingleaves are oval to heart-shaped, eachwith a notched base. Flowers and seedon a spike.

Leafy pondweed (Potamogeton foliosus)—Leaves, ribbon-like, about1⁄16-inch wide. Lacks sheath at base.

White (fragrant) waterlily(Nymphaea odorata)—Round, floatingleaves grow to ten inches in diameter,split to stem at center, often purple onthe underside. Flowers are showy,usually white but sometimes pink.Flowers open from morning until shortlyafter midday.

Duckweed (Lemna species)—Tiny,free-floating bodies are flat and round orlobed, oatmeal-sized or smaller; oftenmistaken for algae. Barely visible rootsdangle thread-like. Sometimes severalplants are attached. Masses of thisplant accumulate as a scum blanketingquiet shallows. As scum dies, it turnsyellowish or whitish.

Sago pondweed (Potamogeton pectinatus)—Fine, thread-like leavesthat fan out with a sheathed base. Nofloating leaves. Stems usually multi-branched. Tubers grow from horizontalroots.

Curly leaf pondweed (Potamogetoncrispus)—Leaves alternate; has finelytoothed, crinkled or puckered edges. Nofloating leaves. Flowers and seeds inspike at tip extend above water for fertil-ization. Grows in fertile hard water.Introduced from Europe.

Emergent plants


Arrowhead (Sagittaria species)—Leaves usually arrow-shaped, but somemay be tongue-like or ribbon-like, espe-cially at base of plant or underwater.Flowers white, petaled, whorled andgrow near tip of a stalk. Fruits are tightlypacked balls of seeds.

Burreed (Sparganium eurycarpum)—Leaves, long, erect, ribbon-like, usually1–3 feet high. Stems bear male flowersat tip; female flowers below. Fruitingheads are 1-inch round balls with manyseeds.

Cattail (Typha latifolia)—Leaves reachto 6 feet tall, ribbon-like, tapering to apoint. Flowers on stalks taller thanleaves. Male flowers at tips, femaleflowers below. The plants grow at thewater’s edge, but commonly also todepths of 3–4 feet.

Chairmaker’s rush (Scirpus ameri-canus)—Horizontal rootstocks give riseto stems with triangular cross section(but round in some bulrushes). Heightusually 2–3 feet. Flowers and seeds onspikes along stem near tip. The plantsmay form dense stands after severalyears.

Pond plant biologyUnderstanding how pond plants growhelps in managing nuisance plant prob-lems. All plants need water, light, a placeto be, nutrients (fertilizers) and the righttemperature. If any of these elements arein short supply, plant growth will bereduced or eliminated.

Water is usually not a limiting factor inponds. Although, as discussed in otherparts of this publication, if a pond isdesigned so it can be drained, drainingor dewatering it can offer a useful plantmanagement option.

Light diffuses rapidly in water, so plantgrowth decreases as the light getsdimmer. The water’s clarity determineshow quickly light dissipates and thusaffects plant growth. In clear lakes andponds, rooted plants might grow in waterup to 30 feet deep. In very turbid ormuddy water, rooted plants may notgrow in water deeper than 18 inches.Rooted plants rarely reach the water’ssurface where they become a nuisancein water deeper than 15 feet. Ponddesign as it relates to depth is importantto managing the area where rootedplants grow.

Although some green, rooted plants canbe found under the ice, rapid growthusually doesn’t start until water tempera-tures reach about 60˚–65˚F. Algae aremore tolerant of broader temperatureranges. Different species of algae maydominate the pond depending on watertemperature.


Pickerelweed (Pontederia cordata)—Leaves heart-shaped, similar to those ofarrowhead but rounded at tip andcorners. Curving veins follow leaf margin.Blue flowers that grow in a spike.

Spikerush (Eleocharis species)—Clumps of stems rise from shallowroots, remain much shorter than rushes.Oval fruiting spike at end of stem.

Water smartweed (Polygonumamphibium)—Leaves eliptical, up to 4inches long. Stems upright or sprawlingin water or on mud banks. Deep pinkflowers in spike at tip of plant.

Rush (Juncus effusus)—Clumps ofstems rise from stout horizontal root-stocks, grow 3–4 feet tall resemblinggrasses and sedges. Greenish-brownflowers near tip of stem.

Although not much can be done tomanage temperature in an outdoorpond, temperature is important forchemical weed control. Herbicides workbest when plants are growing. Watertemperatures should be 60˚–65˚F beforeyou use herbicides.

There is a direct relationship betweennutrient levels (primarily nitrogen andphosphorus) in water and algae growth.Generally speaking, the more nitrogenand phosphorus in the water, the greaterthe algae growth. Any method of reduc-ing nitrogen and phosphorus in the pondwill limit this growth.

Proper pond design and land manage-ment around the pond is essential toprevent excessive nutrient input.Chapter 3 discusses these techniques.

The relationship between nutrient levelsin the water and rooted plant growth isnot as direct. Rooted plants get themajority of their nutrients from the pondbottom. Therefore, it is more difficult tocontrol nutrient availability to rootedplants. Limiting nutrients in the watermay cause rooted plants to spreadbecause the clearer water will allowdeeper light penetration and thusprovide more area for plants to grow.

The type of plants in ponds often changeseven when the plants aren’t managed.One type of plant replaces another. Bythis process a pond vegetation problemmay alleviate itself or get worse depend-ing on the species involved. Nuisancegrowths of chara, for example, have beenreplaced by other plants that are lessbothersome—with no control needed.

Managing the growth of nuisance plantsThe best way to avoid plant problems isto design the pond so that there is littlearea suitable for plant growth. Thisusually means making the pond deepenough so that rooted plants can’t growand nutrients don’t get into the pond tostimulate algae and other plant growth.

Assuming you already have a pond witha problem, the next best thing is to try toadjust one critical factor—light, nutrientsand sometimes water—to limit growth ofthe nuisance plants. These techniquesprovide the most long-lasting control.

If your options are limited, you may haveto control plants by physically removingor chemically killing them. You willusually need to do this on a regularbasis. Consider it part of pond mainte-nance much like mowing is a part oflawn maintenance.

Certain control techniques are moreeffective for certain species. Some tech-niques are best suited for algae controland others for rooted plants. This re-emphasizes the importance of knowingthe species that are causing problems.

Eliminating one type of vegetation maymake room for some equally bother-some replacement. This phenomenontakes place soon in some cases. Forexample, less than a month after cuttingor poisoning rooted plants, the area maybe clogged with stringy algae. Youshould keep records of vegetationchanges because your management

strategy may change as new problemsoccur.

When deciding on a plant managementtechnique, consider not only how welland for how long the technique works,but also the environmental impacts, theuse limitations imposed by using or notusing the technique and the costs interms of both time and money.

Physically disrupting and removing plants This method is one of the simplest andmost practical, akin to weeding a gardenor mowing a meadow. Most aquaticplants are more fragile than gardenweeds, so physical control may beeasier for water plants than for landplants.

You can keep areas free of weeds bycausing frequent disturbances, such asraking the pond shallows, or lettingswimmers trample beach areas. Cattails

are easily killed by trampling or cuttingthe new shoots in springtime. Cuttingcattail shoots in the fall so they freezeunder the ice is another effective controltechnique. Both techniques may work onother emergent plants.

You can simply wade in and uprootmany plants by hand. This works for cat-tails, rushes and other emergents whenthey are growing as isolated plants, aswell as for submergent plants that youcan reach. The first “weeding” of a well-established plant bed may be hard work,but repeated follow-ups prevent the situ-ation from developing again.

A scythe or hoe is useful for cuttingaquatic weeds in shallow areas.Caution: Wielding a blade underwatercan be dangerous! Always wear protec-tive boots!


Pulling plants out by hand is often the simplest way to controlvegetation in shallow water.

Cut plants will float and should beremoved from the pond as soon as pos-sible. Deposit them where the nutrientswill not run back into the pond as theplants decay.

A rake can be used for uprooting,tearing loose and dragging out plants.The head of a garden rake, fitted with anextra-long handle and manipulated froma boat or while wading is suitable forreaching into deep water. A floating rakeis less tiring for work near the surface.

You can construct a floating rake froman 18- to 20-inch, 2x2 board by driving arow of spikes two or three inches apart,then cutting off the heads. A bamboopole makes a good handle. It can belong, yet light. Hand-operated andpower-operated weedcutters designedfor underwater use are available fromcommercial sources, as are floatingrakes.

For weed growth too extensive to cutwith a scythe or rake, a log wrappedloosely and stapled with barbed wire canbe dragged through the pond behind atractor driven along the shore. A heavychain connecting the log to the tractorhelps sink the log to the pond bed. Addmore weight as needed. The log can beguided with a rope manipulated bysomeone on the opposite shore. Thebarbed wire log seems to be animprovement over the often recom-mended method of dragging bedsprings. Weeds are difficult to removefrom bed springs.

Mechanized harvesters are available ina range of sizes. Small models, costingabout $1000, can be mounted on arowboat. These have cutter bars likethose on hay mowers. With this type ofboat-mounted unit, weeds can be cut toa depth of about 4 feet. After the weedsare cut, they are raked to a removalpoint on shore. Other weed cutters aremanufactured as mower bars on smallpaddlewheel barges. These can operatein very shallow water, as well as todepths of 5 feet or so. They range inprice from $2000–$20,000. Large har-vester units which draw plants onto thebarge as they are cut are available forupwards of $50,000.

Some plants are difficult to control withmechanized harvesters. Chara sinkswhen cut and is therefore hard to pick up.Milfoil, coontail and elodea are also hardto collect once they are cut. These kindsof plants spread by fragmentation. Eachpiece cut and not picked up may becomea new plant. In small ponds, removingthem by hand or rake is probably prefer-able to mechanically harvesting them.

It is best to remove plants during thespring or summer because you canremove the largest number of plants andstill allow full recreational use of thepond. The timing depends on your knowl-edge of the growth habits of the plants inyour pond and your plans for the pond’suse. Often, the best approach in a smallpond is periodic trimming as in caring fora lawn or garden. In new ponds, controlplants by frequent hand or rake removalbefore they become abundant.

Harvested plants make good gardenmulch, soil conditioner and compostingmaterial. The thin cell walls of aquaticplants break down rapidly and the result-ing fine-textured matter is also suitablefor spreading on lawns.


A floating rake.

A log and barbed wire drag for removingvegetation.

56

Deepening the pond to control vegetationYou can renovate a plant-clogged pondby dredging out the pond bed, or if it isdammed, by raising the water level todeepen the pond. One effect of greaterpond depth on aquatic vegetation is toput more of the bed at a level that is toodark for rooted plant growth. It is hard tosay what water depth will be critical toprevent nuisance growth of rootedplants. That depends on the waterclarity, the kinds of plants present andnutrient supplies. Maintaining a depth of15 feet should greatly reduce problems.

Dredging reduces the amount of nutri-ents available to plants from organicdeposits in shallow water, and cancreate steeper side slopes where plantsseem to grow poorly.

Increasing the depth and volume of thepond can have other beneficial effectson nutrient levels and suitability for fish.Consider these in deciding whether theexpense is justified. See Chapter 3 for adiscussion of the techniques, relativecost and environmental impacts of ponddeepening.

Water level drawdownLowering the pond’s water level andexposing all or much of the pond bed toair can have several favorable effectsand may cost little. Table 6 lists commonaquatic plants that are susceptible tosummer and winter drawdowns. Dryingkills many kinds of aquatic plants. It ispreferable to conduct the drawdown inwinter when the freezing of plant tissues,including the roots, gives more extensiveand lasting control. Summer drawdownis particularly ineffective on plants suchas coontail and elodea which grow asfree-floating fragments. Other plantsincrease as a result of summer draw-down, and cattails or other emergentscan invade exposed mud flats.

Where sediments are composed of softorganic material, drying consolidatesthem, and you may gain several inchesor feet of pond depth. Drawdown canalso facilitate dredging. See Chapter 10for a discussion of drawdown techniques.

A word of caution: If shallow waterremains in the pond for much of thegrowing season, the extra light maypermit seeds or plant fragments tosprout and take root. When the pond isrefilled, especially if the water level israised too slowly, the plants may con-tinue to grow and become a nuisance.To prevent this, draw the water down asfar as possible, and when the dryingand/or freezing has had its effect, raisethe water level rapidly. If plants havebegun to grow in shallow pools, it maybe advisable to destroy them by rakingor other means before refilling the pond.

M A N A G I N G W I S C O N S I N F I S H P O N D S Table 6. Plant susceptibility to drawdawn

Summer WinterScientific name Common name drawdown drawdown

Bidens beckii water marigold - I

Brasenia schreberi water shield D D

Carex sp. or spp. —— I -

Ceratophyllum demersum hornwort V V

Chara sp. or spp. muskgrass V V

Eleocharis acicularis needle spike rush I D

Elodea canadensis common waterweed V V

Lemna sp. or spp. —— V V

Myriophyllum heterophylium various leaved water milfoil V V

Myriophyllum sibiricum spiked water milfoil V V

Myriophyllum spicatum eurasian water milfoil V V

Najas flexilis slender naiad V I

Najas guadalupenis southern naiad - D

Nelumbo lutea american lotus V V

Nuphar advena yellow pondlily D -

Nuphar variegatum bull-head pondlily V D

Nymphaea odorata fragrant waterlily V D

Polygonum amphibium water knotweed I V

Potamogeton amplifolius large leaf pondweed - V

Potamogeton diversifolius water thread pondweed - I

Potamogeton epihydrus ribbon leaf pondweed - V

Potamogeton gramineus variable leaf pondweed - V

Potamogeton natans floating leaf pondweed D I

Potamogeton pectinatus sago pondweed - V

Potamogeton richardsonii clasping leaf pondweed - V

Potamogeton robbinsii fern pondweed - D

Potamogeton zosteriformis flatstem pondweed - V

Scirpus americanus chairmaker’s rush - I

Scirpus validus softstem bulrush I I

Sparganium chlorocarpum —— V V

Spirodela polyrhiza great duckweed - D

Typha latifolia broadleaf cattail V V

Utricularia purpurea purple bladderwort D -

Utricularia vulgaris great bladderwort - D

Vallisneria americana eel grass - I

I = increases with drawdown D = decreases with drawdown V = variable response- = indicates information unknown or unreported

Discharging selectivelyIn a pond formed by a dam, designingthe outlet facilities so you can vary thedepth from which water is released mayhelp control water fertility. At certaintimes of the year when dissolved nutri-ents are more concentrated, dischargewater can be drawn from those depthsto reduce the pond’s total nutrientsupply. Possible adverse effects of nutri-ent-rich discharge on downstreamwaters should be considered.

Flushing and diluting the pondIt is sometimes feasible to remove nutri-ent-rich pond water and replace it with“sterile” water. If enough water is avail-able, continual flushing keeps planktonicalgae population low. Diluting nutrient-rich water may also alleviate algaeblooms. To accomplish this, truly nutri-ent-poor water must be available from awell or elsewhere. The benefits of thisstrategy will be brief, however, if thesource of the nutrients that caused theproblem remains.

Inactivating phosphorusIntroducing certain chemicals canchange dissolved phosphorus to formsless available to plants or can trap andcarry it down to the pond bed. The effectof this action may be brief. Various com-pounds of aluminum, iron, calcium andother elements can be used. The chemi-cals are typically broadcast as a powderor injected as a slurry into outboardmotor wash. Sodium aluminate and

alum, used in combination (to maintainpH) may be available to the pond owner,as may zeolite, fly ash, powderedcement and clay.

Aerating the pondPumping air into the depths of a pondand creating a rising stream of bubbleshelps aerate a pond. You can do thiswith an on-shore compressor thatpasses air through a hose to thedeepest part of the pond. There aspecial dispenser, such as an air stone,plastic foam block or metal baffle,breaks the air into fine bubbles. Therising bubbles draw water upward,causing the pond water to circulate frombottom to top and take on oxygen fromthe atmosphere. More oxygen is gainedthrough the pond surface than from thestream of bubbles. With the water at thepond bottom oxygenated, the surface ofthe pond mud is kept oxidized, holdingphosphorus in an insoluble form andmaking it less available for growingplants.

In the case of deep trout ponds, specialequipment (the hypolimnetic aerator) isavailable. This brings the cool water ofthe deep zone to the surface and backduring summer without allowing the coolwater to mix with the upper layers. Thus,an undesirable warming of the deepwaters is avoided.

It may be especially important to aeratethe pond in winter. This keeps the areaice-free and allows oxygen to move con-tinually from the atmosphere to the ponddepths. It also reduces transfer of phos-

phorus from mud to water which occursduring winter stagnation. Running aera-tors in the winter causes safety hazardsfrom thin ice and open water—use care.

Selective discharge, pond flushing, nutri-ent inactivation and aeration are tech-niques designed to reduce algae bloomsby limiting nutrients in the water. Theywill probably have little impact on rootedplants and may aggravate the problemof nuisance rooted plant problems byincreasing water clarity. These tech-niques usually require a close estimateof the nutrient “budget” in the pond.Before spending time, effort and moneyon these techniques, you should consulta competent limnologist to decide if theywill work in your pond.

Sealing and blanketing the pond bedTo control rooted plants, pond beds canbe covered with black plastic sheetingweighted with gravel or rocks. However,research shows that the results of thistechnique are short-lived. As soon assediment accumulates on top of theplastic, weed growth resumes. Blackplastic isn’t recommended unless youare willing to continually manage thearea.

Newer products made of fiberglassscreening are commercially availableand effective. It is recommended thatthese products be removed periodically,usually annually, and cleaned for themto remain effective.

Shading or coloring the waterSheets of black plastic supported by afloating wooden or styrofoam frameworkcan be used to cover parts of the pondsurface. Such a covering is anchored inone spot for the 3–4 weeks needed toshade out plants beneath it, then movedto a new place. Shading with plastic isapparently effective on most submergentplants (except chara) but not on emer-gents, and the device may be cumber-some and unsightly.

Special dyes are available (for example,“Aquashade”) that temporarily color thewater to cut off light and control plants.For dyes to be effective, you must main-tain the recommended concentration inthe water. This can be difficult in pondswith streams or a lot of groundwaterentering the pond. Dyes should beapplied early in the growing seasonbefore plants reach the surface.Sediment in the water reduces the effec-tiveness of some dyes. Dyes should notbe applied to ponds where the water isused for human consumption.

Another method of shading portions ofthe pond is by planting trees on thesouth and east sides of the pond so thatthey shade the water. Conifers are pre-ferred because they provide year-longshade and don’t drop leaves into thepond.


Herbicides and algicidesKilling pond plants with chemicals isanother form of treatment. Substancestoxic to algae are called algicides.Those for poisoning rooted, leafy waterplants are aquatic herbicides. You mayneed a permit from the Wisconsin DNRor be certified by DATCP to use herbi-cides and algicides in your pond (seeChapter 15 on permits and licenses).

Chemical treatments have the advan-tage of convenience, but consider thefollowing drawbacks:

■ Poisoning kills plants without remov-ing them from the pond. After theydie, plants sink, consuming oxygen,creating odors and releasing nutri-ents for new plant growth.

■ Poisoned plants disappear onlyslowly from the treated area. One toseveral weeks may pass before themasses of nuisance plants sinkaway.

■ Since each herbicide kills manykinds of plants, beneficial speciesmay be killed along with the nui-sance plants.

■ Localized treatment is difficult. Evenponds that appear placid have cur-rents that can carry poison from aproblem area to one where plantbeds should be preserved.

■ There is risk of harm to other life inthe pond and the surrounding area.

■ Most chemical treatments requirethat pond use be restricted after-wards (for example, no swimming,irrigation or fishing). Make sure youcan abide by these restrictions.

To use chemicals effectively and presentthe least hazard to other life, you mustidentify the kind of plant you wish todestroy, obtain the proper chemical, cal-culate the volume of the pond and applythe proper dosage. Also, for personalsafety, wear proper protective clothing.Use safe procedures for handling pesti-cides and disposing of empty containers.

A list of chemicals generally used forweed control, their trade names and userestrictions are provided in tables 7, 8and 9. These recommendations andrestrictions change rapidly so check withthe DNR at least annually for currentregulation. Using chemicals other thanthose on this list may be illegal and dan-gerous! Use only chemicals labeled foruse in lakes and ponds so you havecomplete instructions on their use andknow of any special precautions.

Dosage rates will be shown on theproduct label. Follow these closely. Donot overtreat! Avoid thinking “If a tea-spoonful is called for, then a wholeshovelful will do the job better.” This notonly wastes money, but may cause plantdecay so rapid that dissolved oxygenbecomes depleted and fish suffocate. Achemical overdose may poison fish andother life. Distribute the chemical evenlyover the area to be treated, whetherusing spray, powder or granular plantpoisons. Too much applied in one place

increases the risk of killing fish andother organisms. Most plant poisonswork best when water temperature isabove 65˚F.

Carefully follow safety precautionsprinted on the product label. Don’t letthe chemical reach crops and otherdesirable plants or trees. Choose a calmday to avoid wind drift. Don’t use thetreated water for irrigation, agriculturalsprays, livestock watering or swimminguntil the time period advised on the labelhas elapsed.

Most emergent plants have a waxy outersurface. For chemical treatments towork, an adjuvant or surfactant must beadded to the herbicide so it “sticks” tothe plant and penetrates the waxysurface to vital parts. Check with theDNR’s or DATCP’s aquatic nuisancecontrol specialists for adjuvant and sur-factant recommendations and userestrictions.

Copper sulfate is widely used to killalgae and is commonly available fromagricultural supply outlets. Extreme careis needed when using copper sulfate orother copper-based chemicals in fishponds. Even though it is frequentlydescribed as suitable for use in humandrinking water supplies or where fish willbe consumed, a high copper contentharms fish food organisms and kills fish.

Copper sulfate is difficult to use properly.Its effects vary greatly depending onwater hardness and other factors. Inextremely softwater ponds, very littlecopper sulfate may kill the algae—butalso may kill the fish. In very hard water,

it may take much more copper sulfate tokill the algae, yet the danger to fish maybe much less. See your nearest DNRbiologist for locally recommendeddosages.

Copper sulfate is best applied by dis-solving the crystals in water and spray-ing the pond’s surface or by placing thecrystals in a burlap bag and pulling itthrough the pond until the crystals dis-solve. Simply throwing copper sulfatecrystals into the water may result in theiraccumulation on the bottom where theyhave little effect on the algae problem.

If you wish to poison algae with copper,you may lower the risk somewhat byusing chelated copper. It achieves thesame algicidal effect as copper sulfatewith a much lower concentration ofcopper. This is less likely to harm fishand other pond life and is much moreeffective in hard water ponds.

Chara algae can be particularly hard tocontrol with toxic chemicals because itoften has a crust of lime (calcium car-bonate scale). Therefore chara shouldbe chemically treated only in the springbefore a heavy crust forms. The amountof copper sulfate needed to kill chara ismore than for other algae. Additionalcaution is advised because copper con-centrations could be hazardous to otherpond life.


Biological controlControlling aquatic vegetation with plantdisease organisms, plant-eating fish,waterfowl or other animals has beentried in many parts of the world, butholds little promise for northern ponds.The plant-eating Asian grass carp(Ctenopharyngodon idella), also calledthe white amur has been imported intothe southern U.S. to control weeds infish ponds. In addition to eating problemplants, it eats beneficial plants that areused as breeding habitat by some desir-able fish, serve as cover for younggame fishes or that supply food forwildlife, especially waterfowl. Sincegrass carp do not eat all aquatic plantsand algae, the plants they don’t eatgrow in place of the plants they do.

It is illegal to bring grass carp intoWisconsin or to possess them, includingthe sterile, triploid grass carp.

The rusty crayfish (Orconectes rusticus)has invaded some Wisconsin lakes andeliminated aquatic plant growth.Although this may sound appealing tosome pond owners, the crayfish causesproblems because it eats fish eggs andburrows into pond banks. Furthermore, itrequires some gravel substrate to repro-duce and achieve abundance levelsrequired for plant control. Planting cray-fish in ponds to control plants is not rec-ommended and it is illegal to possess ortransport live crayfish in Wisconsin.

Plant-eating waterfowl have also beentried for controlling leafy aquatic plants.One pair of domesticated swans andtheir one or two offspring can keep anacre of pond plant-free. However, theswans must be provided with someopen water and shelter in winter (or keptin a barn), and they may need supple-mental feeding which adds nutrients tothe pond.

Ducks and geese that eat plants aren’tsuitable for pond weed control. Theyobtain much food through supplementalfeed or by foraging outside the pond,bring nutrients to the pond as feces, andincrease the plant problem.

Algae typically replace the higheraquatic plants consumed by animalsused to control pond plants. In somecases, dense blooms of planktonic algaemay be more tolerable than largeweeds.

Often in a pond, rooted plants and algaecompete for nutrients and light. Oneproblem acts as a biological control overanother. You may be able to chooseyour problem, but managing both at thesame time is difficult.



Table 7. Susceptibility of aquatic plants to herbicides*

Scientific name Common name Endothall Diquat 2,4-D Glyphosate Fluridone

Acorus calamus sweetflag N N C - -

Brasenia schreberi water shield N N C - N

Ceratophyllum demersum hornwort C C C - C

Chara sp. or spp. (1) muskgrass ? N N N N

Eleocharis acicularis needle spikerush - - - - ?

Eleocharis palustris creeping spikerush - - - - ?

Elodea canadensis common waterweed ? C N - C

Juncus pelocarpus brown-fruited rush - - - - C

Lemna sp. or spp. — N C N - C

Lemna minor small duckweed N C N - C

Myriophyllum sp. or spp. — ? C C - -

Myriophyllum heterophyllum various leaved water milfoil ? - - - ?

Myriophyllum sibiricum spiked water milfoil ? - - - C

Myriophyllum spicatum eurasian water milfoil ? C C N C

Najas sp. or spp. — C C - - ?

Najas flexilis slender naiad ? C N N C

Najas guadalupensis southern naiad C C N - C

Nelumbo lutea american lotus ? ? C ? -

Nitella sp. or spp (1) — - - - - -

Nuphar sp. or spp. — N N C C C

Nuphar variegatum bull-head pondlily ? - C C -

Nymphaea sp. or spp. — ? N C C C

Nymphaea odorata fragrant waterlily ? - C C C

Phragmites australis common reed - - - C ?

Polygonum sp. or spp. — ? N C C ?

Potamogeton sp. or spp. — ? - - ? -

Potamogeton amplifolius large leaf pondweed C ? N - -

Potamogeton crispus curly leaf pondweed C C N - C

Potamogeton diversifolius water thread pondweed C ? N - C

For use as a general guideline only. C = plant generally controlled. ? = questionable control; results highly dependent on chemicalformulation or environmental conditions. N = plant generally not controlled. (1) = plant usually controlled with copper compounds.- = information unknown or unreported.


Table 7. (continued)

Scientific name Common name Endothall Diquat 2,4-D Glyphosate Fluridone

Potamogeton filiformis thread leaf pondweed C - - - C

Potamogeton foliosus leafy pondweed C C N - C

Potamogeton illinoensis illinois pondweed - - - - ?

Potamogeton natans floating leaf pondweed C C ? - C

Potamogeton nodosus long leaf pondweed C ? N - ?

Potamogeton pectinatus sago pondweed C C N - C

Potamogeton pusillus small pondweed C C N - -

Potamogeton richardsonii clasping leaf pondweed C N N - C

Potamogeton strictifolius stiff pondweed C C N - -

Potamogeton zosteriformis flatstem pondweed C N N - -

Ranunculus sp. or spp. — ? C ? - -

Ranunculus tricophyllus white water crowfoot ? C - - -

Ruppia maritima widgeon grass N C N - -

Sagittaria sp. or spp. — N N C - ?

Sagittaria latifolia common arrowhead - - - - ?

Scirpus sp. or spp. — N ? C - C

Scirpus acutus hardstem bulrush - - - - ?

Scirpus americanus chairmaker’s rush - - - - ?

Scirpus validus softstem bulrush - - - - ?

Sparganium sp. or spp. — C N N - -

Spirodela polyrhiza great duckweed - C ? - ?

Typha sp. or spp. — N C ? C ?

Utricularia sp. or spp — N C N - -

Utricularia gibba humped bladderwort - - - - C

Vallisneria americana eel grass ? ? - - N

Wolffia sp. or spp. — N C N -

Wolffia columbiana common watermeal - - - - ?

Zannichellia palustris horned pondweed C ? N - ?

Zosterella dubia water star grass C C N - -

For use as a general guideline only. C = plant generally controlled. ? = questionable control; results highly dependent on chemicalformulation or environmental conditions. N = plant generally not controlled. (1) = plant usually controlled with copper compounds.- = information unknown or unreported.


Table 8. Aquatic herbicides commonly used to control weeds inponds

Common name Trade name

Copper Sulfate Copper Sulfate Medium Crystals

Triangle Brand Copper Sulfate

Copper Sulfate Instant Bluestone

Copper Sulfate Superfine Crystals

Kocide Copper Sulfate Crystals

Copper Chelates Algimycin Pll-C

Aquatrine Algaecide

AV-70 (also AV-70 plus)

Cutrine-Plus Algaecide/Herbicide

Slow Release Algimycin

Stocktrine II

Komeen

K-Tea Algaecide

Endothall Aquathol

Aquathol K

Hydrothol 191a

Diquat Reward

2,4-D Weed R-64

Aqua-kleen

Navigate

Glyphosate Rodeo

Fluridone Sonar A.S.

Sonar S.R.P.

a Fish will be killed by dosages greater than 0.3 ppm.

Table 9. General restrictions on use of treated water (number of days)

——————Human————— ——Animal—— ——Irrigation——Drink- Swim- Fish con- Drink- Food

Herbicide ing ming sumption ing Turf crop Forage

Copper sulfate 0 0 0 0 0 0 0

Copper chelate 0 0 0 0 0 0 0

Endothall 0 0 3 7-25 7-25 7-25 7-25

Diquata 1-3 1 14 1 5 14 14

2,4-Db 14 0-2 c 14 14 14 14

Glyphosateb 0 0 0 0 0 0 0

Fluridoneb 0 0 0 0 7-30 7-30 7-30

a = A drinking water tolerance of 0.01 ppm has been established for Diquat. b = Although no waiting period is established for recreation or domestic purposes, a drinking watertolerance of 0.07 ppm has been established for 2,4-D, 1 ppm for glyphosate and 0.15 ppm for fluri-done.c = No established waiting period.

Wildlife around the pond

Ponds are an excellent way toenhance wildlife habitat on yourproperty. For many species, asource of water provides much more

than just a place to get a drink. To repro-duce, most amphibians (frogs andtoads) must make a seasonal move towater. Waterfowl (ducks and geese)feed, rest and nest in, on or near water.Turtles and aquatic mammals such asmuskrat and beaver all depend on waterfor a home. Thus, if you have a pond,you can expect these animals to bepresent.

However, there is a difference betweenwildlife ponds and ponds constructed topropagate and harvest fish. Any waterwill attract some animals, but wildlifeponds are generally shallower and morevegetated with sides that slope moregradually than fish ponds. Resourceagencies may provide technical assis-tance and cost sharing for constructionof wildlife ponds, but usually not for fishponds. In the case of ponds designedfor fish production, the presence ofabundant and diverse wildlife is moreoften a liability than anasset.

Because this publication focuses onponds for fish production and fishing,wildlife here is discussed primarily in thecontext of nuisance and damage prob-lems. If you are interested in creating ormanaging a pond for wildlife, refer toyour local Wisconsin DNR office, NRCSoffice, Extension wildlife specialist orone of the many informative print materials available.

Controlling wildlife problemsThe mere presence of wildlife does notnecessarily mean you will have problems.Furthermore, you and your guests willlikely enjoy the opportunity to observe thewildlife around a pond. However, it is veryimportant to be aware of the problemsthat can occur and be prepared to takethe necessary steps to control themshould they arise. Many mammals andbirds eat fish, several mammals can dosignificant structural damage to dikes,dams and shorelines, and some species(such as Canada geese) can be a nui-sance on grassy shorelines.

Animal damage problems are usuallymuch more complicated than aquaticweed or insect control. Wild animals aremobile, often wary, usually protected bystate and/or federal law—even on privateland—and are often highly valued bysociety. In addition, problems are con-founded by differences in site, weather,season and other factors. Consider thefollowing general guidelines, techniquesand sources of assistance. Advice spe-cific to individual species is presented forthe major problem species.

Also, don’t expect animal damagecontrol to be totally effective or perma-nent. The control techniques describedhere will reduce or eliminate losses, butin most cases you will need to repeatthem from time to time.

Wildlife control considerationsKeep these things in mind as youattempt to resolve conflicts with wild animals.

■ Anticipate rather than react. Try toanticipate a problem and take stepsto prevent it. For example, if fish-eating birds are common, removepotential perches before damageoccurs. Wildlife problems are mucheasier to avoid than stop after ananimal has established a behaviorpattern.

■ Understand wildlife laws. You mustfind out what you can and cannot dowith regard to harassing, relocatingor killing any wild animal. A fewspecies (rats, mice, some othersmall mammals and a few birds likepigeons and starlings) are not pro-tected by laws. Most, however, areprotected by state and/or federal law.Although there are some special pro-visions for landowners, you will notbe able to kill or capture certainspecies, no matter how serious theproblem. Permits, licenses or otherforms of permission may berequired. Laws also vary from stateto state and even within some


municipalities (use of firearms, forexample). The sections of this publi-cation dealing with problems causedby certain species contain basiclegal information but check first withyour local DNR office or warden.

■ Be sensitive to values other thanyour own. A problem for you may bea delight to your neighbors or viceversa. Neighbors may have differingopinions about killing or relocating“pest” species or the use of pesti-cides. This is especially true in thecase of fish-eating birds.

■ Know your adversary. Your effortsto control a wildlife problem can begreatly enhanced by an understand-ing of the animal’s basic life history.What does it eat (helps with baitchoice)? Where does it live (helpswith trap placement or habitat modifi-cation)? How prolific or mobile is it?Furthermore, better knowledge of thewildlife in question may lead you todecide your problem is really not sobad given the benefits the animalmay provide.

■ Understand the basic tools andtechniques of wildlife damagecontrol. Wild animals are much dif-ferent than weeds or insects. Fewchemical pesticides are registered(available) for animal control (that’sgood!) and cookbook solutions(apply X to Y, wait 3 days, problem isgone) are rare for wildlife problems.

The following general options are usedin wildlife control:

1. Exclusion. Prevent the animal fromgetting to a site where it may causedamage. Examples: a fence, a meshcover over a small rearing tank orpond, or monofilament lines strung inparallel rows over a raceway for birdexclusion.

2. Removal. Remove the animal fromthe scene. Examples: remove liveanimals—capture and relocate viawire live trap, net, hand, etc.; killanimals—shoot, use toxicants, kill-traps (like a wooden-base rat trap).

3. Repellents. Prevent the animal fromdoing damage or gaining entry byusing olfactory or taste-based repel-lents. Examples: Rejex-it® applica-tions on grass to discourage Canadageese.

4. Scare tactics. Frighten the animalaway. Examples: gunfire over apond, owl decoys, mylar or plasticstreamers, other noisemakers,“scare-eye” balloons, propanecannons, radios.

5. Habitat modification. Eliminate akey component of the animal’shabitat thus causing it to leave thearea. Examples: eliminate deadsnags or posts used as perches byfish-eating birds; riprap a bank usedby muskrats.

6. Increased tolerance. Rethink thesituation! Examples: The sounds orsights provided by the animal inquestion may be worth the hassle orloss, or maybe there are more fishthan you really needed anyway.

Problem speciesMuskrats and woodchucksMuskrats and woodchucks dig burrowsthat may cause pond bank cave-ins,weaken dams or result in leaks. Theyprefer to dig in steep banks. Muskratstunnel from beneath the pond surfacewhile woodchucks typically tunnel intothe high portions of the banks or dams.

Muskrats make burrow entrances 6"–18"below the water line, sometimes deeper.Burrows may penetrate banks or dams 9feet or more, but the average length is5–6 feet. The tunnel leads to a dry nestchamber above water level. Frequentlymuskrats also burrow upward from thenest chamber tunnel to the surface, thuscreating a second burrow entrance highon the bank or dam.

Woodchucks, also called groundhogs,burrow into pond dams and banks wellabove the waterline. The burrows maypenetrate 50 feet or more and rise to thesurface creating a second burrowentrance on the other side of the dam,or well away from the pond. The tunnelslead to underground nesting chambersand chambers for food storage, bodywaste and traps for water that enters theburrows.

Habitat management. Eliminating orreducing habitat reduces or eliminatesthe attractiveness of banks and dams towoodchucks and muskrats. Maintaindams and banks in grasses such asfescue and brome. Eliminate all broad-leafed plants, especially legumes likeclover, alfalfa and trefoil. Eliminatemuskrat food, such as cattails, arrow-head and other emergent plants. If thepond is not properly constructed, con-sider regrading the banks, and deepen-ing the pond to reduce the zone whereemergent plants grow (see Chapter 3).


Remember, habitat modification will helpto solve problems, but will also reducethe attractiveness of your pond to othermore desirable species. To completelyeliminate the possibility of muskrat andwoodchuck damage to bank and dam,reinforce banks and dams with materialsthat will prevent burrowing. Reinforcingthese embankments is the only way tocompletely prevent muskrat and wood-chuck damage when the pond is locatednear other waterways, wetlands oruplands that are in unmowed meadows,hay fields or other agricultural uses.

Reinforcing the shore and dam. Theshore and bank can be reinforced todeter muskrat or woodchuck burrowingin one of the following ways.

■ Cover with at least 2 layers of rocks(called riprap) at least 6 inches indiameter from 3 feet below the lowwaterline to 3 feet above the normalwaterline for muskrats. For wood-chucks, cover with 2 layers of riprapfrom normal waterline to the top ofthe dam or to the top of the bank.

■ Use soil cement in the top 6 inchesof earth from 3 feet below low water-line to 3 feet above normal waterlevel for muskrats and from thenormal waterline to the top of thebank or dam for woodchucks.

■ Cover with vinyl-coated chicken wirefrom 3 feet below low waterline to 3feet above normal water level formuskrats and from the normal water-line to the top of the dam or bank forwoodchucks.

Reducing muskrat and woodchuckpopulations. If the pond is not adjacentto extensive muskrat or woodchuckhabitat, damage caused by muskratsand woodchucks can be greatly reducedby eliminating as many of the animalsas possible. If the area surrounding thepond has extensive wetlands ormeadows, hayfields or agricultural lands,the animals that are eliminated will bereplaced very quickly by new ones fromthe surrounding habitat and damage willbe reduced only slightly, if at all.

Because these regulations change occa-sionally, check the annual hunting andtrapping regulations and consult yourlocal conservation officer about specialprovisions for damage control.

Beavers Beavers may cause problems by fellingtrees, plugging culverts and spillwaysand digging bank dens. Major revisionsin Wisconsin regulations in 1990changed private landowners’ beavercontrol options. Consult your local DNRoffice and request a copy of BeaverDamage Control. In general, you mayshoot or trap beaver on your own prop-erty and remove dams without a specialpermit. In northern Wisconsin the USDAWildlife Services office in Rhinelanderruns an intensive beaver controlprogram.

Beaver are most likely to be attracted tomoving water where they can engineertheir own flowage. In this case, there areseveral devices that utilize PVC pipesinstalled through the dam with intakesand outflows well above and below thedam. For some reason, the animals donot seem to figure out the “leak” in theirpond and water continues to flow. Lookfor information on the “Clemson Beaver

Pond Leveler” if this idea sounds useful.There is an excellent chapter on beavercontrol in the Handbook of WildlifeDamage Control published by theUniversity of Nebraska. Most Wisconsincounty UW-Extension offices have acopy, or you can request a copy of thesection on beavers from your Extensionwildlife specialist.

OttersOtters are playful creatures but fish arethe main component of their diet. Afamily of otters in a fish pond is a majorproblem. The otters should be capturedand removed as soon as possible. Minkmay also take some fish but they earntheir keep by preying on muskrats.

65W I L D L I F E A R O U N D T H E P O N D

MolesMole burrows cause erosion by destroy-ing patches of sod on dams or pondbanks. Applying any mole damagecontrol method to inactive mole burrowsystems is futile. In all cases, treat onlyactive tunnels. To see if a tunnel is beingactively used, gently flatten a shortsection of the ridge above the tunnel. Ifthe tunnel is in use, the ridge will beraised again within 24–48 hours.

A new repellent, Mole-Med® can beapplied directly to grassy areas, for 1–2months of relief from burrowing activity.For further details contact your localUW-Extension county office for a copy ofthe publication Mole Control (G3200).Pocket gophers could be confused withmoles but they are found only in thewest-central and southwestern parts ofWisconsin. Gophers are rodents (molesare not) and can be controlled withpoison baits.

BirdsSeveral kinds of fish-eating birdsconsume fish from ponds, especiallykingfishers, herons, osprey, mergansersand domesticated ducks. Fish-eatingbirds may also carry parasites that infectfish. All of these birds can be scaredaway by noise-making devices, such asgas-powered automatic cannons andbird-scaring shotgun shells that fireexplosive charges designed to detonate50–100 yards away. Use exploders andscare shells in combination. You mustvary the locations, firing intervals andfiring times at least every third day orthe birds soon become accustomed tothese techniques. Use of these devicesrequires a federal permit if endangeredor threatened species are involved.Noise ordinances may also be a factor ifyou are near a developed area.

Scarecrows, artificial snakes, hawk orowl decoys and special balloons thatfrighten birds can also be used to scarebirds away. These devices must be posi-tioned imaginatively and moved fre-quently, at least every other day, or theywill soon become ineffective. They aremost effective if used together withscare shells and automatic explosioncannons.

Discourage herons by grading thepond’s edges to form steep underwaterside slopes. Three feet of horizontal dis-tance per foot of slope is the maximumslope recommended for safety (see theinformation on pond construction inChapter 3). If necessary, suspendchicken wire horizontally at or near thewater surface along the shallow parts ofthe pond edge. Discourage kingfishersby removing all perches, such as postsand dead tree limbs, close to the pond.If Muscovy ducks are kept in the pond,confine them to a small part of it.

All birds that may cause potential prob-lems around ponds are protected byfederal (and often state) law. In extremecases, a permit may be issued to shootoffending birds. But be aware of thepublic relations consequences of suchactions. For more information andnecessary control permits,contact the nearest USDA WildlifeServices office. There is an excellentchapter on “Bird Damage at AquacultureFacilities” in the Handbook of WildlifeDamage Control from the University ofNebraska mentioned earlier.

A pair of Canada geese and theirgoslings may be a welcome addition, butlarge flocks of local or migrating geesecan be a major nuisance if your pond issurrounded by a well-maintained turf.Geese defecate profusely which leads toa visual and sanitation problem.Persistent grazing by geese candamage turf. Scare tactics such as birdscreamers, shell crackers or gunfire willhelp. Hunting pressure during the appro-priate open season is very useful. A rel-atively new repellent called ReJex-It® (aformulation of methyl anthranilate) canbe applied directly to the turf to discour-age geese.


Turtles and snakesIn recreational fish ponds, turtles andsnakes rarely eat enough fish to affectthe fish population. Unlike mammals andbirds, turtles and snakes may not feeddaily and they concentrate on minnowsand other small fish.

Some pond owners want to removeturtles and snakes simply because theyare afraid of them or don’t like them.Snake and turtle populations can bereduced by mowing pond bank vegeta-tion and removing logs, tree roots,branches and large stones from theshoreline. Mowing this habitat reducesthe opportunity for these animals tosurvive, but it also reduces the effective-ness of a vegetated buffer strip for nutri-ent and sediment control.

Indiscriminate killing of all snakesregardless of species accomplishes littleand may create or intensify other prob-lems, such as rodents. In recognition ofthe value of many reptile species, lawsand regulations change rapidly. Be sureto check with your local DNR officebefore taking action.

If it becomes necessary to removeturtles from a pond, they are easilycaught using a trap constructed ofchicken wire. Commercial turtle trapsare also available. To make a trap, roll apiece of one-inch mesh chicken wire 60inches wide and 60 inches long into acylinder 60 inches long. On both ends ofthe cylinder, make four cuts, 15 inchesapart. Each cut should be 12 inchesdeep. Next fold these ends of the cylin-der inward and reattach the cut ends toeach other to create funnels pointinginward with a small end opening ofapproximately 12 inches by 6 inches. Atrap of this size will catch all but thelargest snapping turtle.

To trap a very large snapping turtle thatweighs more than 20 lbs., start with apiece of chicken wire that is 6 by 8 feet.Follow the previous directions, but this

time make the opening of the small endof the funnel leading into the trapapproximately 10 inches by 18 inches.

Cut a door panel in the side of the trapand wire it tightly closed.

To use the trap, place it in shallow waterwhere turtles are most likely to feed.Make sure that thetop part of the trapis above water sothat entrapped turtles or otheranimals accidentally trapped donot drown. Nylon rope or metalcable should be fastenedto the trap and tiedsecurely to a tree, rock,stake or other nonmov-able object on shore so thatentrapped animals do not roll the trapinto deeper water and drown. Almostany meat or fish bait will work in thetrap, but one of the most convenient andeffective baits available is a partiallyopened can of sardines. Place the par-tially opened can into the trap beforeputting the trap in the pond. Capturedturtles can be removed by hand or witha dip net through the door panel.

Check with the local DNR office for reg-ulations on trapping turtles in your pond.

67W I L D L I F E A R O U N D T H E P O N D

For more information or on-site assistanceWisconsin Cooperative Extension —

County extension offices or statewildlife specialists have a wealth ofinformation available. Extensionwildlife damage control publicationscontain the details needed for mostproblems and most county officeshave a copy of the Handbook ofWildlife Damage Control (Universityof Nebraska, 1995).

State Natural Resource ManagementAgencies (DNR) —Agency staff canprovide information, legal advice andpermits.

U. S. Department of Agriculture-Animal and Plant HealthInspection Service-WildlifeServices—This agency’s role variesfrom state to state but WildlifeServices staff can be a great help inagricultural and aquacultural prob-lems. The agency maintains districtoffices in Waupun (800-433-0663)and Rhinelander (800-228-1368) anda statewide office in Sun Prairie(608-837-2727).

Private contractors—There has been arecent proliferation of individuals whowill handle wildlife damage problemsfor a fee. Check the Yellow Pages orthe county Extension office for a ref-erence.

Self reliance—With some good informa-tion, a little thought and good equip-ment you can solve most wildlifeproblems yourself.

Other problemsSwimmer’s itchSwimmer’s itch is caused by a minute,free-swimming parasite that burrows intoand irritates the skin. This parasitedevelops only in certain kinds of snailsbefore it attacks humans. Ducks alsoassist in the life cycle of the parasite butany attempt at duck control is likely tobe undesirable and ineffective. Feedingducks at pondside will only exacerbatepotential swimmer’s itch problems andshould be avoided.

Ridding a pond of swimmer’s itch meanscontrolling the snails. To control snailswith least harm to the pond’s fish,remove plants and pondbed debris,which provide the snails’ habitat. Sowingpea-sized copper sulfate crystals ontothe pond bed (2 lb/1000 sq ft or 87lb/acre) poisons snails but also killsmany other fish food organisms, andpossibly some fish, especially trout. Toavoid chemical control, simply be sureall swimmers quickly and vigorouslytowel dry themselves immediately uponleaving the water.

MosquitosIn general, mosquitos don’t thrive in fishponds because fish eat mosquito larvae.Moreover, mosquitos need calm water todevelop. Any spot where a breeze canripple across a pond’s surface is unsuit-able for mosquitos. Only very shallow,protected pond edges support them, andsmall fish usually dispose of mosquitolarvae in these places.

Most mosquitos that cause problemscome from temporary puddles.Maintaining a stable pond level preventsflooding of shoreland which creates iso-lated puddles for mosquito breeding.Don’t try to control mosquito breedingunless you have found exactly where itoccurs. Then confine your control effortsto those sites.

A safe, effective and pleasant mosquitocontrol is to install a purple martin housenear the pond or at the area of humanactivity. One colony of martins will helpkeep mosquitos at a tolerable levelduring daytime and early evening.Beware of using insecticides to controlmosquitos near ponds. These chemicalsare very likely to kill the fish.

LeechesMost leeches feed on animals, such asturtles, or on dead matter. Only fourspecies attach to humans. Therefore,the first thing to determine is whetherleeches are attaching themselves topeople or whether they have merelybeen sighted in the water. No control isneeded unless the leeches are definitelycausing a human problem.

Often, the most effective way to reduceleech populations is to reduce theamount of organic debris on the pondbed. Leeches dwell in accumulations oftwigs and leaves at the bottom of thepond and they swim up or reach out toattach to host animals. Some leechesattach to aquatic plants and stretch toamazing lengths in search of passingfood. Controlling beds of dense vegeta-tion may also help control leeches.

Another method for controlling leechesis to have plenty of bass or trout in thepond. These fish prey on most of thetroublesome leeches. In fact, somekinds of leeches are highly effectivefishing baits, and they are a hot-sellingitem at bait shops. Stocking 25 to 50yearling (6- to 8-inch) bass per acreshould reduce leech populations so thatthey are no longer a problem.


Fish health managementFactors influencing fish healthThe health of fish, whether they live in thewild, in a hatchery or in a pond dependsupon the interactions of the fish (the sus-ceptible host), the presence of diseaseorganisms (bacteria, viruses, parasites orfungi) and the living environment (figure25).

Fish and disease organisms can co-exist without causing significant fishhealth problems or mortality. But healthproblems occur when one (or somecombination) of three conditions exists.

1. Something happens to affect thefish’s susceptibility to a disease orparasite. For example, when fishpopulations reach a high density, fishcan become stressed, and diseasecan occur and spread quickly. Overtime, the genetic makeup of a fishpopulation canchange so that the fish are more or lesssusceptible to certainpathogens.

2. Increased environmental stressdirectly or indirectly causes fishhealth problems. Decreased oxygenin the water, increased ammonialevels and low pH can directly affectthe gill structure, leading to bacterialor enviromental gill disease.Exposure to poor water quality, pesti-cides or limited food supply can indi-rectly affect fish health by supressingthe immune system.

3. New fish stocked into a pond maycarry new disease organisms thatcan result in significant fish healthproblems. Or disease organismsalready present can mutate to morevirulent forms and cause diseaseoutbreaks.

Managing fish health Pond design specifications, stockingrates and other fish management rec-ommendations in this manual weredeveloped to promote healthy fish popu-lations. But some health problems mayoccur even when these recommenda-tions are followed. Close attention topond conditions, oxygen, temperatureand the relative growth of fish, coupledwith regular observation of fish behavioris important to assessing the health offish. Fish that are lethargic, pip for air atthe surface, or “flash” against rocks orthe pond bottom may have underlyinghealth problems. In general, make surefish introduced into your pond are notstressed or carrying heavy loads of fishparasites or disease organisms.


Figure 25. Relationship of management to disease problems.

stressfulenvironment

pathogen host

diseaseoccurs

improvedenvironment

hostpathogen

poor management good management

Your understanding of fish parasites anddisease organisms will help you evalu-ate the status of the fish intended forplanting and those already present inyour pond. Establishing that a group offish are disease free requires the skillsof a trained professional.

If you plan to raise trout or salmon, it isalways a good idea to ask potential fishsuppliers for a copy of the most recentfish health inspection report for theirfacilities. Results from an inspectionindicate the disease organisms thatwere detected at the time of the inspec-tion. To minimize the introduction of newdisease organisms, it is always best toreceive eggs (that are surface disinfec-

ted) rather than fish. Fish cannot be“disinfected” and may carry any combi-nation of fish pathogens.

Introduction to common fishparasites and diseasesTable 10 gives an overview of some ofthe more common organisms that canmake fish sick and explains how youcan tell if those organisms are present.Parasites and bacterial infections aremost common in pond fish.

ParasitesParasitic infections are common inpond-reared fish and can be difficult tocontrol. Some parasites live their entirelife on the same fish, while othersrequire a variety of intermediate andfinal hosts (figure 26).

The life cycle of the parasite causing“black spot” is typical of most fish para-sites. Adult flukes live in the intestines ofkingfishers and shed eggs that arepassed in the bird’s feces. Once in thewater, the eggs hatch, releasing a larvaethat infects certain species of snails.Larvae develop in the snail and thenemerge and “swim” until they encounter

a fish. The larvae then burrow into theskin or muscle of the fish and secrete aprotective wall around themselves. Thefish also secretes a protective layeraround the parasite and we see this asthe black spot. When the kingfisher eatsan infected fish, the larvae mature to theadult stage and the cycle repeats. Sincethe parasite spreads via free-flying king-fishers, susceptible fish and residentsnails, it is very difficult to eradicate itfrom a pond.

Other birds and mammals carry similartypes of parasites that spend part oftheir life cycle on fish. Therefore, wher-ever there are abundant wildlife popula-tions, it is very likely that parasites willinfect fish that are reared outdoors. Ingeneral however, these types of para-sites do not pose a threat to the fish orthose who eat them. By keeping the fishpopulation at low densities, you may beable to reduce the number of encystedlarvae per fish, but this may not beacceptable if low fish densities are notpart of your pond management plan.

Columnaris is a disease caused by thebacteria Flavobacterium columnare. Thisbacterium is very common in lakes andponds. The bacteria invade gill and skintissue and sometimes infect the internalorgans. Signs of this disease includeyellow to grey mucus on the gills, erosionof the skin on the head and body anderosion of gill filaments. Trout or salmontend to develop “saddle back” lesionsthat look like grey patches of skin oneither side of the dorsal fin. Undercertain conditions the disease can causehigh levels of mortality. The bacteria


Table 10. Common fish diseases and their symptoms.

Name of disease (and fish affected) Causative agent Symptoms

Skin fungus or Saprolegnia fungus Tufted growths of fine white or gray threads water mold (all fish) (often results from injury to skin) radiating 1⁄3 inch or more from body.

Columnaris Flavobacterium columnare Grayish-white spots surrounded by red on (all fishes) bacterium parts of head, gills, fins or body.

Red sore (northern pike) Aeromona hydrophila bacterium Open bleeding sore from which scales are lost.

Furunculosis Aeromonas salmonicida Boils or furuncles on skin, inflammation of inner (trout and salmon) bacterium body walls, many small internal hemorrhages,

bright red spleen and swollen kidneys.

Black spot or black grub Digenetic trematodes Small black spots just under skin and in muscle. (mostly warmwater fish*) These are cysts containing a microscopic

stage of this parasite.

“Ich” or white spot Ichthyophthirius multifilis Tiny white spots on body.(mostly warmwater fish) protozoan

Lymphocystis (perch, a virus Raised nodular masses of light-coloredwalleye, sunfishes) tissue resembling warts on skin.

Fish lice (warm and Injuries, dietary problems, External and internal tumors of various sorts, coolwater fish and brook trout) genetic causes, etc. spinal deformities, shortened or flattened heads.

*Also trout where the water is unfavorably warm.

thrive at temperatures above 65˚ F. Fishcan develop an immunity to this bac-terium if they survive the initial infection.

Columnaris bacteria increase on fishunder stress and pose a particularproblem in commercial ponds with highfish densities. Stress caused by low dis-solved oxygen, high temperatures, highammonia levels, an inadequate diet orinsufficient space or water flowincreases the likelihood of mortalitywhen disease organisms are present.

Depending upon the situation,Columnaris disease and parasitic infec-tions are controlled by a variety of treat-ments. Guidance for treatments can beobtained from other fish farmers, someveterinarians, the U.S. Fish and WildlifeService, DATCP, the DNR and fishhealth reference books. The U.S. Foodand Drug Administration regulates fishtherapeutants. Anyone who treats fishmust follow U.S. FDA guidelines.

If your pond has an outlet, you shouldbe aware that fish health problems willbe passed downstream to other fish.Responsible natural resource steward-ship will minimize fish health problemsat your pond and in fish downstream.The key to successfully raising fish in apond is to remember that fish are livingorganisms. If you can provide an ade-quate food supply and a quality environ-ment for your fish, the chance fordisease problems to occur will be small.

There are many opportunities to learnmore about fish health. The U.S. Fishand Wildlife Service conducts a week-long course entitled “An Introduction toFish Health.” The course is usually heldin February in LaCrosse. Contact theU.S. Fish and Wildlife Service LaCrosseFish Health Center for more informationabout this course. See the references onpage 77 for the address for theLaCrosse Fish Health Center and a listof reference materials on fish diseases.

71F I S H H E A L T H M A N A G E M E N T

Figure 26. Life cycles of the yellow grub (above) andthe “ich” skin parasite (below).

Blue heronfinal host

Parasite eggsreleased into waterwith bird droppings.

Larvae enter snailand develop tosecond larval form

Heron eats infectedfish and adult stage

develops.

Second stage larvaeburrow into skin of fish

and develop into a thirdstage larvae.

Second stage larvaeswim out of the snail

and search for susceptible fish.

Pond safety andliability

Afishing pond may furnish someswimming, boating, hunting, iceskating, wading and picnicking, eventhough it may be designed primarily

for fish. It will be a special attraction tochildren.

Because ponds attract people, theypresent an accident hazard. Drowningsare second only to motor vehiclemishaps as a cause of accidental deathamong people in the active age groups,particularly children.

Each pond owner has moral and legalobligations to family, friends, neighborsand even trespassers to make the pondas safe as possible. Providing certainsafeguards can prevent an incident frombecoming an accident or even a fatality.

Simply posting a notice prohibitingtrespassing at a pond does notrelieve an owner of responsibility.Legal liability is often based on whetheran owner has taken all reasonable pre-cautions against mishaps. Pondowners should consult their attor-neys and insurance companies aboutliability for serious accidents or death, aswell as about the legal requirements forsafety precautions at the pond.

Find out about both community andstate liability laws regarding injury ordeath resulting from use of the pond.Local laws may vary greatly. This isespecially important if an owner intendsto open the pond to the public andcharge user fees.

Here is a list of fairly economical safetymeasures.

■ Grade the pond bed to eliminatesteep slopes or drop-offs.

■ Remove broken glass and othersharp objects, stumps, logs, largerocks and trash that could pose ahazard to waders, swimmers andboats.

■ Place warning signs near specificdanger areas, giving the depth of thewater and the location of the nearesttelephone.

■ If you permit swimming, mark a safespecial area for it with buoyed lines.

■ Install life-saving equipment on thepond bank where it can be easilyseen and used.

■ Be sure that piers, rafts and landingsare well-constructed and braced.

■ Erect adequate fencing and lockedgates to prevent unauthorizedentry—especially by children.

■ Keep boats used on the pond ingood condition. Never overload them.Instruct passengers never to standup in the boat. Provide one CoastGuard approved life preserver or per-sonal flotation device (PFD) for eachperson on board. Use common-sense safety in all other respects!

■ Beware of thin ice! Test the strengthof the ice with a spud or auger, andactually measure its thickness beforeventuring over deep water. Don’twalk or skate on freshly formed icethat is less than three inches thick. Ifthe ice is thawing, it may need to bemuch thicker than that. Snowmobilesshould not be driven onto ice lessthan five inches thick.

■ Keep a wooden ladder at the pond’sedge in winter. This can be shovedout to someone who has fallenthrough the ice.

■ Never let a child play at the pondalone, no matter what the season.

■ Everyone who lives, works or playsnear a pond should know how toswim and how to give cardiopul-monary resuscitation. Find out moreabout it from your local Red Cross.

chapter chapter 11 4 4

Installing a rescue stationUse the materials and process describedbelow to install a rescue station.

1. Post—A 6-ft two-by-four or four-by-four, preferably painted yellow. Setthe post about 2 ft into the ground,standing no more than 4 ft out of theground, near the water at any pointwhere swimmers might get intotrouble. Paint “THINK, THEN ACT”down the length of the post on allsides. About 1 ft from the top, attacha metal shelf bracket, wooden armor 60-penny spike to use as a hookfor coiled rope and the jug float.

2. Jug—A gallon plastic jug with aninch of water inside to be thrown to aperson in trouble. Paint “FOREMERGENCY USE ONLY” on theside.

3. Line—A 40-ft length of 3⁄8 inchpolypropylene. Tie one end to thehandle of the plastic jug. At theopposite end, fasten a 4-inch pieceof two-by-four to prevent the linefrom slipping completely throughhands or from underfoot whenthrown.

4. Pole—A 10- or 12-ft bamboo pole orsapling. Since the pole will beextended to anyone struggling in thewater, its tip and butt should bewrapped with friction tape to reduceslippage. Paint the pole white. Hold itin an upright position by placing it intwo 6-ounce tin cans, nailed near thebottom of the post about 6 inchesapart.

5. Tin container—A 46-ounce juicecan or a 2- or 3-lb coffee can.Remove one end, then slide the canover the top of the post. Fasten itdown with one nail through thecenter of the top so it is impossibleto rotate.

6. Poster—A sheet of safety tips,rescue methods and emergencytelephone numbers. After applying acoat of varnish to the can, attach theposter to the can and mount the canat the top of the post. Let dry thor-oughly; then varnish the poster toprotect against weather.

Note: Add a ladder to the rescue stationif the pond is likely to be used in winter.

73P O N D S A F E T Y A N D L I A B I L I T Y

1.

2. 3.

4. 5.

6.

Steps in making a rescue station.

Regulations

To protect Wisconsin’s pricelessnatural resources for future genera-tions, legislation has been enactedthat regulates pond construction and

management. While the permit processmay seem cumbersome, it serves toremind those interested in pond con-struction and management of theirresponsibility to the state’s naturalresources and the potential liability thatmay be involved. You can start theprocess by requesting a fish farm infor-mation packet from DATCP.

In Wisconsin, all navigable waters arepublic property and are protected topromote the public interest. In addition,because over 50% of Wisconsin’s andthe nation’s wetlands have already beendestroyed, both state and federal lawsprotect existing wetlands.

Pond construction regulationsThe type of pond and its placementdetermine the regulations that concernyou. As suggested earlier, ponds thatmight affect public navigable waterwaysor wetlands are of particular concern.

A navigable waterway is any body ofwater large enough to float a canoe atany time of the year. Generally, a stream3 feet wide and 8 inches deep at anytime of the year is classified as a navi-gable waterway. A wetland is any areawith water at or near the surface thatsupports wetland plants.

The DNR determines whether the wateris a navigable waterway or a wetland.Your county or local units of governmentmay also have designated sites as wet-lands. The U.S. Army Corps ofEngineers reviews permits involving wetlands.

You should contact your DNR fish expertat the nearest local or district office (seereferences) to find out which permitsapply to your project. You should alsocontact your county, city and villagezoning office or building inspector to findout whether local permits are required.

Any pond to be located within the flood-plain of a navigable waterway mayrequire a permit. A permit is alwaysrequired if you are planning to build apond within 500 ft of a navigable water-way. A special permit is also required ifthe project involves changing the courseof a navigable waterway or divertingwater from or discharging water to anavigable water.

Navigation and safety are a considera-tion for impoundments. Federal as wellas state regulations prohibit constructionof dams on navigable waterways. If yourplans call for placing a dam on a non-navigable waterway, the law requiresthat the plans be reviewed andapproved by the DNR to protect publicsafety as well as the public’s naturalresources. Some county land conserva-tion departments have professional staffwho can assist in the pond design andthe permit processes.


Registration as a tool to regulate pond managementThe destruction caused to waterways bythe European carp illustrates why fishpond management is regulated.

Registration is used to implement manyregulations related to fish pond manage-ment, and the collection of wild animalsfor sale by the bait industry.

The state gains a way to keep track ofwho is involved in fish management andthe specific sources of fish beingstocked in public waters through thenatural waterbody permits and stockingpermits issued by the DNR.

Fish farms are registered by DATCP. Ifyou choose to register your pond withDATCP, you may:

1. Fish on your pond without a statefishing license

2. Stock fish into the pond withoutobtaining a DNR stocking permit

3. Ignore state fishing regulations onsize, bag limits or open/closedseasons

If you do not register your pond withDATCP, anyone older than 16 must havea state fishing license to fish there; theymust abide by state fishing regulations;and you must obtain a stocking permitfrom DNR to put fish in your pond.There is no fee for the stocking permit.

DATCP has the right to inspect privatefish farms and to revoke a registration ifviolations are observed. The Fish FarmRegistration Law is provided in Chapter95.60 of the State Statues.

Bait dealers are regulated by the DNRand are required to obtain a Class Alicense ($49.25) if they sell more than$2,000 worth of bait per year, or a ClassB license ($9.25) if their sales are lessthan that.

The license allows for the sale of anyspecies of minnow (the state lists spe-cific native species as bait) or frog usedas fish bait. Crayfish may only be solddead in Wisconsin. The gear that canlegally be used to collect bait by thelicense holder is specified by the state.For example seines to capture bait frompublic waters cannot exceed 35 ftexcept for smelt seines which may be75 ft. The law governing bait harvest isfound in Chapter 29 of the WisconsinStatutes.

Wisconsin residents who hold a baitdealer’s license can import bait into thestate. All fish imported into the staterequire an importation permit fromDATCP. If the imported species areexotic, DNR and DATCP will co-issuethe import permit. Licensed bait dealersfile annual reports and wardens mayinspect their businesses at any reason-able hour to ensure compliance with theterms of the license.

Permits as a way to regulatepond managementA permit process is used to regulate theimportation of all plant and animalspecies for the purpose of introducing orstocking. The purpose of the regulationsis to protect the native animal popula-tions of the state from foreign species ordisease organisms that might be carriedby species coming into the state.

Under the new statutes, if a fish farm isself-contained, it does not need anaquatic pesticide permit to use toxicants.If the fish farm discharges to surfacewater, a permit is needed to use thechemicals unless the discharge of thatchemical is allowed under a (WPDES)Wisconsin Pollution DischargeElimination System permit.

LiabilityCertain pond management operationsmay affect other people. If this effect isdetrimental, the parties involved maybring legal action. In this respect itmakes little difference if the pond is aregistered private fish hatchery. Fishpoisons or plant toxicants that damagepublic resources may result in legalaction. Damage to another’s propertyduring construction or as a result of anuncontrolled discharge may initiate alawsuit. Drowning of pets, livestock orpeople can occur and result in legalaction. Always manage your pond withthorough consideration of its effects onthe surrounding area.

75R E G U L A T I O N S

References Major sources of information GeneralWisconsin Department of NaturalResources

Aquaculture, fish health608-266-7715, 608-266-2871

Regional officesContact the nearest WisconsinDepartment of Natural Resources (DNR)regional office or your local DNR ServiceCenter about permits for the followingpond management activities: damming;pond digging or dredging within 500 ft ofany navigable water; fish stocking; ponddraining; use of algicides or weed-killingchemicals; use of fish toxicant chemi-cals; and aquatic weed cutting orharvest.

Northern RegionBox 309Spooner, WI 54801715-635-2101or

Northern RegionBox 818Rhinelander, WI 54501715-365-7616

North-Eastern RegionBox 10448Green Bay, WI 54307920-492-5800

West-Central RegionBox 4001Eau Claire, WI 54701715-839-3700

South-Central Region3911 Fish Hatchery RoadMadison, WI 53711608-275-3266

South-East RegionBox 12436Milwaukee, WI 53212414-263-8500

Wisconsin Cooperative ExtensionYour Cooperative Extension countyoffice is listed in the phone book under“county government.” The county agentcan put you in contact with state fishery,wildlife or plant specialists, local peoplewho can assist in planning and manag-ing your pond, or, if you are interested incommercial aquaculture, with one of theUWEX Small Business DevelopmentCenters.

Aquaculture Information Center,National Aquaculture Library, 10301Baltimore Blvd, Room 111, Beltsville,MD 20705, 301-344-3704

The Internet Many companies that produce aquacul-ture products advertise and conductbusiness on the Internet. All aspects ofpond aquaculture are represented byvarious home pages and mail groups.Listservers and web pages can provideyou with much valuable information.

Listservers are automated e-mail listingsand can be very useful in gettinganswers to specific questions. Whensubscribers to the listserver group senda message, the message is distributedto all subscribers. PONDS-L is anexample of a listserver that deals withpond aquaculture. To subscribe, sendthe e-mail message: “subscribe ponds-l”to [email protected]. Many list-servers offer summaries of messagesfor you to review before you join.

The World Wide Web offers access to awhole universe of information in the formof web sites. One web site typically linksto others with related information. Youcan select the various links to find infor-mation you want. You can get to a par-ticular web site by knowing its address,or URL (uniform resource locator). Twoexamples of URLs for aquaculture sitesare the AquaNIC homepage(http://ag.ansc.purdue.edu/aquanic/)and the The Aquaculture Health site(http://geocities.com/capecanaveral/

lab/74901).

You can also find information on theInternet by conducting a search usingkey words like “aquaculture,” “recre-ational pond,” “fisheries,” “bass,” orother terms that might take a searchengine to sites of interest. When youfind a good web site, save it as a “book-mark” so you can return to it quickly.


Commercial aquacultureAquaNic homepagehttp://ag.ansc.purdue.edu/aquanic/Provides access to information on commercial aquaculture.

Aquaculture InstituteGreat Lakes Research Facility 600 E. Greenfield Milwaukee, WI 53204 414-382-1700 A research center that focuses onaquaculture.

Aquaculture MagazineP.O. Box 2329 Asheville, NC 28802704-254-7334A trade magazine with articles on allsubjects of aquaculture; issued bi-monthly; $19/year.

Aquaculture NewsP.O. Box 416Jonesville, AL 71343318-339-4660A monthly newspaper providing information on aquaculture, especially in the U.S.

Fish Farming NewsP.O. Box 37Stonington, ME 94681207-367-2396A bi-monthly newspaper that provides information on all aspectsof aquaculture; $10/year.

North Central Regional Aquaculture CenterOffice of the Associate Director,Department of Animal Ecology124 Science II, Ames, Iowa, 50011515-294-5280More than 100 specialized publica-tions and videotapes on mostaspects of commercial aquaculture.

University of Wisconsin Aquaculture Program123 Babcock Hall1605 Linden DriveUniversity of Wisconsin–MadisonMadison, WI 53706608-263-1242A research center that can provideup-to-date information on pondaquaculture.

Wisconsin Aquaculture AssociationBox 115Lewis, WI 54851715-653-2271http://www.wisconsinaquaculture.com/Meetings and the newsletter, Creel, provide key information onaquaculture in Wisconsin.

Wisconsin Department of Agriculture,Trade and Consumer Protection2811 Agricultural DriveMadison, WI 53704608-267-9644Information on planning, grants and loans.

VideosThe videos listed below provide eithergeneral or detailed information on pondculture. Most titles are available throughthe North Central Regional AquacultureCenter. For more titles, see the AquaNicweb site.

Kulka, K. and E. Norland. 1993. WeedControl in Ohio Ponds Contact:Ohio State University ExtensionPiketon Research and ExtensionCenter, 1864 Shyville RoadPiketon, Ohio 45661614-289-2071(Detailed. 30 minutes, Note: Fifteen titles covering a rangeof topics available).

Swann, L. 1993. Investing in Freshwater AquacultureNorth Central Region AquacultureCenter Video Series 103Contact: Aquaculture ExtensionOffice. Dept. of Animal SciencePurdue UniversityWest Lafayette, IN 47909 317-494-6264 (Detailed. 95 minutes Note: Other titles available).

Swenson, W. A. 1999Fish Farming: Some IndustryPerspectives.Contact: University of Wisconsin–Extension county Extension officesor Media Resources CenterUniversity of Wisconsin–SuperiorSuperior, WI 54880715-394-8340(General. 22 minutes).

Swenson, W. A. 1990Managing PondsContact: University of Wisconsin–Extension county Extension officesor Media Resources CenterUniversity of Wisconsin–SuperiorSuperior, WI 54880715-394-8340(General. 22 minutes).


Further ReadingPond planning and constructionGibson, G. R., Jr. 1979.

A riparian’s guide for self-help inlandlake water quality management.Extension bulletin E-1117Michigan State UniversityEast Lansing, 67 pp.

U.S.D.A. Soil Conservation Service(revised 1997). Ponds—Planning, Design,Construction. Agriculture Handbook No. 590. U.S. Dept. of Agriculture.Washington, D.C., 85 pp.

Pond fishery managementBennett. G.W. 1971.

Management of Lakes and PondsVan Nostrand ReinholdNew York, 375 pp.

Eipper, A. W., & H. A. Regier. 1962. Fish Management in New York Farm Ponds Extension Bull. 1089. Cornell Univ., Ithaca.

Lopinot. A. C. 1972. Pond Fish andFishing in Illinois. Fishery Bull. No. 5, Illinois Dept. of Conservation,Division of Fisheries, Springfield, IL 62706, 72 pp.

Marriage, L. D., A. E. Borell, & P.M.Schaefer. 1971. Trout Ponds forRecreation. Farmer’s Bulletin No.2249, U.S. Dept. of Agriculture SoilConservation Service, Washington, D.C., 13 pp.

Schrouder, J.D. et.al. 1994. ManagingMichigan Ponds for Sport Fishing(E1554). Michigan State University,Lansing, 67 pp.

Prospects for commercial aquacultureCain, K. and D. Garling. 1993.

Trout culture in the North CentralRegion. North Central RegionalAquaculture Center. Fact Sheet Series # 108.

Chopak, C.J. 1992. Promoting feefishing operations as tourist attrac-tions. Michigan State UniversityExtension bulletin E-2409

Chopak, C.J. 1992. What consumerswant: advice for food fish growers.Michigan State University ExtensionBulletin E-2410.

Chopak, C.J. 1992. What brokers,wholesalers, retailers and restau-rants want: advice for food fishgrowers. Michigan State UniversityExtension Bulletin E-2411.

Garling, D.L. 1992. Making Plans forCommercial Aquaculture in the NorthCentral States. North Central RegionAquaculture Center, Fact SheetSeries #101.

Life in ponds (General—identification of organisms, biology, ecology)Amos, W. H. 1967. The Life of the Pond.

McGraw-Hill Book Co., New York, 232 pp.

Coker, R. E. 1968. Streams, Lakes,Ponds. Harper & Row, New York,327 pp.

Klots, E. B. 1966. A New Field Book ofFresh Water Life. G. P. Putnam’sSons, New York, 398 pp.

Reid, G. K. 1967. Pond Life: A Guide toCommon Plants and Animals ofNorth American Ponds and Lakes.Golden Press, New York, 160pp.

Ward, H. B., & G. C. Whipple. 1959.Fresh-water Biology. 2nd Edition (W. T. Edmondson, ed.). Wiley Sons,New York, 1248 pp.

Identification of fishesBecker, G.C. 1983. Wisconsin Fishes.

University of Wisconsin Press, 114 North Murray Street, Madison, WI. 53715, 1054 pp

Eddy, S. and J. C. Underhill. 1974.Northern Fishes. University ofMinnesota Press, Minneapolis, MN, 414 pp.

Scott, W. B., & E. J. Crossman. 1973.Freshwater Fishes of Canada. Bull.184, Fisheries Research Board ofCanada, Ottawa, 966 pp.

Identification of aquatic invertebratesPennak, R. W. 1978. Freshwater

Invertebrates of the United States.Wiley, New York, 803 pp.

Hilsenhoff, W. L. Aquatic Insects ofWisconsin (G3648). Publ. No. 2, Nat. Hist. Council, Univ. ofWisconsin–Madison, 60 pp. Availablefrom Cooperative ExtensionPublications, Rm. 170, 630 W. Mifflin St., Madison, WI 53703, toll free 1-877-WIS-PUBS (947-7827).


Identification of aquatic plantsBorman, S., R. Korth and J. Temte.

1997. Through the looking glass, afield guide to aquatic plants. Pub.FH-207-97, Wisconsin Department ofNatural Resources, Madison, WI,248 pp.

Fassett, N. C. 1957. A manual of aquaticplants. University of WisconsinPress, 2537 Daniels St., Madison,WI. 53704, 405 pp.

Hoyer, M.V. and D. E. Canfield, Jr., eds.1997. Aquatic plant management inlakes and reservoirs. Prepared bythe North American LakeManagement Society and theAquatic Plant management Soceityfor U.S. Environmental ProtectionAgency, Washingtn, D.C., 103 pp.

Prescott, G. W. 1964. How to know thefreshwater algae. Wm. C. BrownCo., Dubuque, Iowa, 348 pp.

Stodola, J. 1967. Encyclopedia of waterplants. T. F. H. Publications, Neptune City, N.J, 368 pp.

Voss, E.G. 1972. Michigan flora Part I.Bull. 55. Cranbrook Inst. of Science,Bloomfield Hills, MI, 488 pp.

Nutrient over-enrichment andaquatic plant problems/controlApplied Biochemists, Inc. 1976. How to

identify and control water weeds andalgae. 5300 West County Line Road,Mequon WI, 64 pp.

Helsel, D. and S. Syzmanski, 1999.Management of Aquatic Plants andAlgae in Ponds: Protecting YourPiece of Paradise. Department ofNatural Resources (DNR) publcation#FH228. Wisconsin LakesPartnership, Stevens Point, WI 15 pp.

Lopinot, A.C. 1979. Aquatic weeds: theiridentification and control. FisheryBull. No. 4. IL Dept. of Conservation,Springfield, 56 pp.

McNabb, C. D., Jr. 1977. Aquatic PlantProblems in recreational lakes ofsouthern Michigan. Extension Bull.E-1 135, Michigan State Univ., EastLansing, 25 pp.

McComas, S. 1994. Lake smarts.Terrene Institute, 1717 K Street NW,Washington, DC 20006,202-833-8317

Nichols, S. A. 1974. Mechanical andhabitat manipulation for aquatic plantmanagement. Tech. Bull. 77, Wis. Dept. Natural Resources,Madison, 34 pp.

Nichols, S.A., S. Engel and T. McNabb,1988. Developing a plan to managelake vegetation. Aquatics 10:(3)10–19

Smith, S.A., D.R. Knauer and T. L.Wirth. 1975. Aeration as a lake man-agement technique. Tech. Bull. 87,Wis. Dept. Natural Resources,Madison, 39 pp.

Wildlife damage controlUniversity of Nebraska. 1995. Handbookof wildlife damage control. Availablefrom most Wisconsin county Extensionoffices, or from your Extension wildlifespecialist.

Fish healthRichard Nelson, Director

U.S. Fish and Wildlife ServiceLaCrosse Fish Health Center555 Lester Ave.Onalaska, WI 54650608-783-8444

Further reading on fish parasites anddiseases. Note that there are numerousfree pamphlets available on this topic.

Post, G. 1987. Textbook of fish health.TFH Publications, Neptune City, New Jersey

Hoffman, G and F. Meyer. 1974Parasites of freshwater fishes: Areview of their control and treatment.TFH Publications, Neptune City, NewJersey, 224 pp.

Sniezko, Stanislas. 1971. Diseases offishes—bacteria.TFH Publications,Neptune City, New Jersey.

Pond managementIllinois Dept of Conservation, 1990.

Management of small lakes andponds in Illinois. Div. of Fisheries,Springfield. 72 pp.


Authors: Jim O. Peterson and Stanley Nichols are professors and Extension specialists with the Environmental ResourcesCenter at the University of Wisconsin–Madison. William Swenson is a professor and Extension fishery specialist at theUniversity of Wisconsin–Superior. Scott Craven is a professor of wildlife ecology with the University of Wisconsin–Madisonand a wildlife specialist with the University of Wisconsin–Extension. Jeff Malison is director of the University of Wisconsin-Madison Aquaculture Program. Thomas Thrall is an aquatic biologist with the U.S. Natural Resources Conservation Service.Susan Marcquenski is a fish health specialist with the Wisconsin Department of Natural Resources.

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S.Department of Agriculture, University of Wisconsin–Extension, Cooperative Extension. University of Wisconsin–Extension pro-vides equal opportunities in employment and programming, including Title IX and ADA requirements. If you need this informa-tion in an alternative format, contact the Office of Equal Opportunity and Diversity Programs or call Extension Publishing at(608)262-2655.

© 2000 by the Board of Regents of the University of Wisconsin System doing business as the division of CooperativeExtension of the University of Wisconsin–Extension. Send inquiries about copyright permission to: Director, CooperativeExtension Publishing, 201 Hiram Smith Hall, 1545 Observatory Dr., Madison, WI 53706.

You can obtain copies of this publication from your Wisconsin county Extension office or from Cooperative ExtensionPublications, 45 N. Charter St., Madison, WI 53713 (608)262-3346. Outside Madison, call our toll free number: 1-877-WIS-PUBS (947-7827). Before publicizing, please check on this publication’s availability.

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Managing Wisconsin Fish Ponds (G3693) I-6-00-3M-000

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