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Managing Michigan

PondsFor Sport FishingThird Edition

Revised April 1994 Third Edition Michigan State University Extension Extension Bulletin E-1554

$3.50

Managing Michigan Ponds For Sport FishingThird Edition

by

John D. SchrouderFisheries Division, Michigan Department of Natural Resources

Charles M. Smith1

Michigan Office, U.S. Department of AgricultureSoil Conservation Services

Patrick J. Rusz2 ,Ray J. White3

Donald L. Garling*Glenn R. Dudderar*

Department of Fisheries and Wildlife, Michigan State University

This bulletin was developed joint-ly by the Michigan Department ofNatural Resources, the U.S. Depart-ment of Agriculture Soil Conser-vation Service, and Michigan StateUniversity Extension. Senior authorJohn Schrouder was responsible forthe parts dealing with fishery man-agement: Chapters 5, 6, 7, 8, 9 and12. Charles Smith wrote Chapters 3,11 and 13. Patrick Rusz did master'sdegree research at Michigan StateUniversity, resulting in the key find-

Acknowledgements

ing that pond depth of 15 feet ormore is needed for maintaining satis-factory fish populations, and heworked on a preliminary draft of thebulletin. Ray White wrote Chapters1, 2, 4 and 10 and coordinated edit-ing of the bulletin throughout.

William McClay of MichiganDNR was particularly helpful inreviewing the manuscript and sug-gesting alterations, as were Ned E.Fogle and David P. Borgeson, also ofthat Department. Glenn R. Dudderar,

Extension Wildlife Specialist in theMSU Department of Fisheries andWildlife, aided in developingChapter 11.

The Pennsylvania State UniversityCooperative Extension Service atUniversity Park provided the draw-ings of aquatic plants by Rae Cham-bers for Chapter 10. The WisconsinDepartment of Natural Resourcessupplied drawings of fishes forChapter 5. Other illustrations wereby Michael Smith and Ray White.

'Retired:Michigan Wildlife Habitat Foundation, 6425 S. Pennsylvania, Lansing, MI 48911'Dept. Fisheries and Wildlife, Montana State University, Bozeman, MT 59717* Revised third edition

1

Managing Michigan Ponds for Sport Fishing

Table of ContentsChapter Page

1. INTRODUCTION 1

The Resource 1What Is Successful Management? 1Caution! Are You Sure You Want a Pond? 2Natural Ponds and Artificial Ponds 2

2. GENERAL CONSIDERATIONS 3

Goals 3Investigation and Planning 4Management Overview, 4Ponds for Commercial Fish Production 4Meeting State Environmental Regulations 5

3. BUILDING FISH PONDS 7

Pond Depth 7Water Supply 9Designing for Control of Aquatic Plants 9Surface Area 10Landscaping and Erosion Control in the Pond's Surroundings 10Excavated or Dug Ponds 11Impoundments 12

4. PONDS AS PLACES FOR FISH TO LIVE 13

Basic Pond Characteristics for Natural Production of Fish 13The Pond Ecosystem 13Consequences of Overenrichment 16Facts About Water and Chemicals Dissolved in It 18Pond Breathing, Circulation and Stratification 19Investigating Pond Suitability for Fish 20

5. KINDS OF FISH TO USE IN PONDS 23

Coldwater Fishes 23Rainbow Trout 24Brook Trout 24Brown Trout 24Hybrid Trout 24

Warmwater Fishes 24Largemouth Bass 24Smallmouth Bass 25Bluegill 25Hybrid Sunfish 26Channel Catfish 26

Forage Fishes 27Fishes Not Recommended for Pond Management 27

6. HOW AND WHERE TO GET FISH FOR STOCKING 29

7. MANAGING WARMWATER PONDS FOR FISHING 31

Determining If a Pond Is Suitable for Warmwater Fish 31Stocking 31Angling Harvest 32

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Higher Stocking Levels and Fish Feeding Not Recommended 34Pond Fertilization and Liming 34Emergency Aeration of the Pond 34

8. MANAGING COLDWATER PONDS FOR FISHING 35

General Considerations 35Determining If a Pond Can Support Trout 35

Stocking 36Preparing the Pond for Stocking 36When to Stock 36Number and Size of Trout to Stock 36Transporting and Planting the Trout 37

When to Start Fishing and How Much to Harvest 37Artificial Feeding 38Special Aquatic Plant Control in Trout Ponds 38Artificially Circulating the Pond Water 38

9. FISH POPULATION CONTROL 39

Intensive Angling 39Predator Stocking 39Spawning Bed Destruction 39Cover Reduction 39Water Level Drawdown 40Seining 40Live-Trapping 41Fish Toxicants 42

10. AQUATIC PLANTS AND THEIR CONTROL 43

Kinds of Plants 43How Nuisance Growths Occur 48Vegetation Control by Restricting Phosphorus Supply 48

Materials from Surrounding Land 48Pond Fertilization 49Fish Food Application 49

Vegetation Control by Temporary Methods 49Physical Disruption and Removal 50Deepening the Pond to Control Vegetation 51Waterlevel Drawdown 51Selective Discharge 52Pond Flushing and Dilution 52Phosphorus Inactivation/Precipitation 52Pond Aeration 52Pondbed Sealing and Blanketing 52Shading or Coloring the Water 52Herbicides and Algicides 52Biological Control 53

11. CONTROLLING ANIMAL NUISANCES 55

Muskrats and Woodchucks 55Moles 57Birds 57Swimmer's Itch 57Turtles and Snakes 57Mosquitoes 58Leeches (Bloodsuckers) 58

in

12. FISH PARASITES AND DISEASES 59

13. POND SAFETY AND LIABILITY 61

14. STATE REGULATIONS ON POND BUILDING ANDMANAGEMENT IN MICHIGAN 63Pond Construction 63Use of Chemicals to Control Pond Vegetation or Fish 63Fish Stocking 64Introducing Exotic Fish 64Fishing Regulations 64

REFERENCES FOR FURTHER READING 65

APPENDICES 66

District Fisheries Offices of the Michigan Department of Natural Resources 66Sources of Fish for Stocking 66Consulting Biologists for Private Pond Investigation and Management 66Fish Disease Diagnosis and Prescriptions for Control 66

IV

Introduction

This bulletin is primarily for thepresent or prospective owner of aMichigan pond where the main goalis sport fishing—for the owner, hisor her family, and a few friends. Itshould also be useful where thepond is for public fishing, or wherethe pond has some other primaryuse such as for waterfowl, swim-ming or irrigation, and angling is aside benefit.

The emphasis is on pond manage-ment under Michigan conditions,but much of the information shouldapply to other northern U.S. areas.Many other writings on pond fish-eries pertain to conditions in stateswith milder climate and are un-suitable for Michigan.

Our objective is to help owners ofexisting ponds achieve more satis-factory fishing, as well as to aidaspiring owners in foreseeing pondpotentials and problems beforebuilding or buying one. How a pondis situated and constructed stronglyaffects the success of management.

The ResourceMany Michigan land owners want

ponds of their own for fishing,although they have free access tofishing in a greater offering of freshwaters than may exist in any otherU.S. state: four Great Lakes front-ing on some 3,200 miles of shore-line, 9,000 inland lakes, 36,000miles (58,000 km) of streams, andnumerous natural ponds. No personin Michigan is far from a selectionof public fishing sites. But one'svery own fishing water, close athand on the farm or vacation prop-erty—or even in a suburban setting—may be more convenient, as wellas privately controllable, although

not without costs and specialresponsibilities.

Between 25,000 and 40,000 arti-ficial ponds have been built in Mich-igan. About 1,000 new ones arecreated each year. Most of these areprimarily for fishing. Other pur-poses often include swimming, wild-life habitat, livestock watering, ir-rigation, and scenic enhancement. Ifa pond is especially designed andmanaged for one of these other pur-poses, it shouldn't be expected toprovide the same quality of fishingas one designed especially as afishery. For example, a pond thatprovides proper duck habitat maybe too shallow and plant-choked tomaintain enough oxygen for fishduring hard winters.

What qualifies as a pond, andhow does it differ from a lake?There are no sharp differences.Everyone thinks of a pond as beingsmaller than a lake, but opinionsvary as to how much smaller. Thisbulletin is intended to deal primarilywith water bodies ranging in sizefrom 14 acre to 10 acres (0.2 to 4hectares).

Regardless of size, ponds typical-ly provide a few years of goodfishing when new, or when "reno-vated" in various ways, then fishingdeteriorates as fish populationschange. On occasion, ponds may bedismal failures right from the start,usually because of faulty design, im-proper location, or poor waterquality.

What is SuccessfulManagement?

When is a pond a "success" or"failure?" Satisfaction is the key.The owner's or user's idea of what

constitutes angling quality and satis-faction is the ultimate measure of apond's success. Much of this bulle-tin is written to help the many pondowners and users who aren't satis-fied with their fishing. But if thefishing in your own pond does satis-fy you, enjoy it, and don't pay toomuch attention to what others say isa more successful kind of pond.

Because satisfactory fishing is somuch a matter of personal taste(some people are disappointed atanything less than trophy-sized bassor trout, while others are delightedwith catching stunted bluegills orbullheads), we try not to tell ownersand users what the right kind ofpond or pond management is. In-stead, we explain principles anddescribe alternatives from which tochoose.

Caution! Are You SureYou Want a Pond?

Creating and managing a pond canrequire substantial time, effort andmoney. There is risk of waste or prop-

erty damage. Matters of legal liability,such as injuries and drownings are ofconcern. Another problem is over-abundance of aquatic weeds. Tryingto prevent or control them can be frus-trating, although we'll provide infor-mation to ease the job.

Many owners soon discover thathaving a fishing pond is a bit likehaving a pet or an automobile. Itneeds to be well cared for if it is toserve its purpose. Trying to maintaina prime fishing pond is like strivingto keep a hunting dog or racing carin good shape. Performance dependson great attention to details. Do youreally have time for that?

Natural Ponds andArtificial Ponds

Many naturally-formed pondsexist in the Michigan landscape.They typically have marshy, gradu-ally-sloping edges. Many of themhave only a few feet of water at thedeepest point, not enough to main-tain good fishing, but fine forwildlife. Natural marshy or swampy

ponds can be highly enjoyable justfor the sights and sounds, possiblyalso for the hunting they offer. Ifsuch a pond provides some fishing,it's a bonus. If a natural pond is deepenough (about 15 feet or more) tofurnish proper habitat for a flourish-ing fishery, then the owner is fortu-nate indeed.

This bulletin should help in realiz-ing added fishing from naturalponds, whether they are of low orhigh potential. However, owners arecautioned that radical management,especially in the form of reshapingthe basin or altering plant life tobenefit fish, may destroy some wild-life habitat or damage other featureswhich the owner values. Naturalponds may be protected by statelaws to preserve the wildlife valuesof weltands.

The artificial pond, designed formaximal fish abundance and mini-mal maintenance, is quite differentfrom most natural ponds. It hassteeply-sloping banks, an averagedepth over 8 feet, and a maximumdepth greater than 15 feet, no matterwhat the surface area.

General Considerations

There's more to satisfactory pondfishing than just putting in somefish. Ponds, like gardens, need pro-per design and management if a sub-stantial crop is to be harvested. Justas in gardening, many questionsmust be answered before manage-ment can be done well. Some of theimportant questions are:

• What is my goal in havingthe pond? Fishing? Swim-ming? Wildlife? Irrigation?Livestock watering? Naturestudy? Scenery?

• If there are several goals,which is the main one, andhow do the others rank inpriority?

• What, roughly, is the pond'spotential for producing fishin terms of space, water fer-tility, and other aspects ofpond quality?

• What water depth should Ibuild (or rebuild) for?

• What kind(s) of fish should Istock? What sizes? Howmany? When?

• When can I start fishing thepond?

• How many fish should beharvested each year and atwhat sizes?

• How can I prevent or remedyoverpopulation of fish andstunted growth?

• How can I prevent or controlnuisance growths of aquaticweeds and algae?

• Am I willing and able tospend the time and effortneeded to achieve the resultsI desire?

This bulletin provides informa-tion to help the owner or managerdevelop answers that apply to his orher particular pond.

GoalsLack of a clear goal is often at the

root of unsatisfactory pond con-struction and management. Fre-quent switching between severalgoals is also a problem. It is best todecide on and work toward a singleprimary goal based on carefulassessment of pond potential. It's agood idea to write the goal downand keep it in view. Stick to the goalfor enough years to see whether itworks.

Satisfactory fishing is undoubted-ly the primary goal, or at least a sec-ondary one, for people reading thisbulletin. We urge you to write thegoal down in terms of the kinds offish desired and also to list what thelesser goals are.

Don't be misled by the "multiple-use" concept. Trying to accomplishtoo many things with the pond canmean that none works out well.Don't expect swarms of large fish ina clearwater situation with flocks ofducks and geese, a livestock water-ing area, and large amounts of irri-gation water to be provided by thesame pond. With effort, you'll belucky to achieve one major benefitand a few pleasant side effects. Forexample, a soundly managed bass ortrout pond might also offer a littleswimming and skating, as well as anemergency water supply and be ascenic asset frequented by song-birds and visited occasionally bymigrating ducks.

A reasonable goal for a pondfishery in our region is a moderateamount of angling for small tomedium-sized fish. Some anglingfun and a meal of fish now and thenare reasonable expectations. Michi-gan ponds can't produce as many

large, fast-growing fish as do thewarmer ponds in southern states.

Investigationand Planning

Undertake pond construction andmanagement only after thoroughstudy of the situation. After readingabout ponds, examine the pond (orpotential pond sites) in as muchdetail as possible. Several sectionsof this bulletin suggest characteris-tics of the pond and its fish popula-tion that can be measured andanalysed. Consider hiring a profes-sional fishery biologist to analysethe pond and devise a managementplan.

Pond design and construction arehighly important to the success ofthe fishery. If you intend to build apond, see the section on that subjectin this bulletin and contact the U.S.Soil Conservation Service office inyour county about engineeringdesign services.

Management OverviewAfter planning carefully, act with

moderation. Overmanagement andapplying management techniquessimply because the manager knowshow to do them (or is fascinated bythe activity) are common mistakesthat may detract from efficiencyand success in achieving a desirablefishery. Knowing when to leavethings alone is important.

The usual steps in managing aMichigan pond for fishing are:

1. Build or rebuild for best depthand slopes (Chapter 3).

2. Eradicate all fish in the pond(Chapter 9).

3. Stock suitable fish (Chapters5, 6, 7, and 8).

If it is a trout pond, restockingwill generally be done each year. Ifit is a warmwater pond, the fish (un-less hybrids) will almost always re-produce, and no further stockingshould be done—except when pan-fish are used, whereupon overpopu-lation and stunting usually occur,and the population must be "reno-vated" by eradication and restock-ing.

The interrelated ideas of balancebetween predator and food organ-

isms and of the happy medium orhaving the right amounts (ratherthan too much or little) of certainthings in the pond are important tomanagement for sustained qualityof fishing. To maintain the pond asa good place for fish to live, waterfertility, other chemical characteris-tics, and temperature must staywithin certain limits—and there willbe a happy medium for each pondcondition where fish will best thrive.

There can be too little water fertil-ity, a range of fertility in which thepond life functions well, or toomuch fertility. With too little fertili-ty, not enough plant and animal lifewill grow to feed many fish. Withexcessive fertility (all too often thecase in Michigan), plants clog thepond, organic matter accumulatesin great amount, and the pondbecomes unstable for fish becauseorganic rotting from time to timereduces dissolved oxygen to insuffi-cient levels. Too much artificialfeeding results in the same problem.

Growing fish in a pond is muchlike growing cattle on a pasture.Both fish and cattle grow well andyield much meat as long as there areenough breeding stock, and thefood supply isn't overgrazed. Toomany fish or cattle ruin the foodsupply. Undernourishment andpoor growth follow.

For example, if you stock twosmall, identical ponds with unequalnumbers of fish, 1,000 in one and10,000 in the other, each pond willhave about the same total weight offish a year later. But the fish in thepond stocked with 1,000 will belarger than those in the pond stock-ed with 10,000. Don't overstock,and don't let the fish become toonumerous!

In ponds managed as trout orbass fisheries, angling harvest mustbe carefully restricted if fish are tolive long enough to reach large size.On the other hand, where panfishare present, severe cropping ofsmall-sized fish is needed if over-population is to be avoided. Keep-ing panfish populations in check byangling alone is rarely if ever suc-cessful in Michigan, however.

For best bass fishing, panfishshould be excluded from Michiganponds. This contrasts with manage-

ment in more southerly states.There, apparently due to warmerwater and longer growing seasons,bass prey more heavily on panfish,control their abundance, and main-tain a productive predator-preybalance. Bass in Michigan pondsusually don't eat enough bluegills orother panfish to maintain such abalance because bass are overfished.The result of having panfish in aMichigan pond, with or withoutbass, is a panfish overpopulationand consequent stunted growth ofall kinds of fish in the pond. Preda-tion by bass, however, may stave offthe panfish overcrowding if bassover 15 inches are protected. Ade-quate numbers of large bass mightneed to be present to exert effectivecontrol.

Despite the disadvantages of pan-fish in our climate, they need not becompletely disregarded. Various op-tions for their management inMidwestern ponds exist. The pondcan be treated with toxicants toeradicate all fish after panfish over-population and poor growth havedeveloped and then restocked, butwith loss of a year's fishing eachtime this is done. Sterile hybrid pan-fish can be used instead of ones thatreproduce, but these are expensive,hard to obtain, and there are almostalways fertile "mistakes" amongthe hybrids, which means that even-tually a breeding populationdevelops. Another alternative issimply to accept and enjoy fishingfor stunted panfish. Such fishing isideal for small children who like tocatch lots of little fish.

Ponds forCommercial Fish

ProductionSome pond owners envision finan-

cial profit, either by raising fish tosell or by charging anglers a fee tofish. Both "fish farming" and "fee-fishing" are different pond uses thansport fishing. Ponds must be man-aged differently to support more fishin commercial ponds. Special man-agement skills, careful managementand larger investments in facilitiesand equipment are required for asuccessful commercial operation. If

you are interested in commercial fishculture, planning materials and assis-tance are available from your statefish culture extension specialist.

Meeting StateEnvironmental

RegulationsThe construction and management

of ponds can cause safety and envi-ronmental problems. Therefore, statelaws regulate the following matters

relating to ponds:— Damming and diking— Excavation and dredging wet-

lands and any land within 500 feet ofany surface water

— Filling of wetlands and anyland within 500 feet of surface water

— Discharge of fish food andwastes into streams or lakes

— Fish stocking— Cutting of aquatic vegetation— Use of chemicals as aquatic

herbicides (algae or weed killers),

fish toxicants, or fertilizers.There are federal regulations on

the use of chemicals to controlplants and fish, as well. Beforeundertaking any of these activities,consult the nearest office of theDepartment of Natural Resources onhow to proceed within the law.

Various permits may be needed.Proper application for a permit maynot only spare future grief but resultin tips from state officials on the bestways to accomplish your objectives.

Building Fish Ponds

Two general types of fish pondconstruction are used in Michigan:

Excavated or dug ponds. Theseare the most common type in Michi-gan. They are usually rather smallponds in fairly level terrain, madeby digging a pit deeper than thegroundwater table. The hole thenfills with groundwater by seepage,or water flows in from nearbysprings. Less commonly, pits areplaced to catch runoff water fromsurrounding land or receive waterdiverted from a stream. Thesesources are less desirable than aregroundwater springs and seepages.

Impoundments. Usually formed byearthen dams, impoundments are notrecommended if construction requiresdamming a stream. Impoundments needgreater land slope and tight soils. Ifcreated by damming a stream, they willbe a settling basin for silt, sediment, anddebris moving downstream and gradu-ally fill in and become less suited forfish. There is also virtually no way tocontrol immigration of undesirable fishfrom the stream making management allbut impossible. If an impoundment isbuilt, it is better for pond quality to im-pound water from springs rather thanfrom runoff or streams. Dammingstreams of any size is strictly controlledin Michigan and requires a state permit.

Ponds can also be built by a com-bination of excavation and dam-ming.

Proper site selection and carefulplanning of construction play largeparts in successful fish pond man-agement. Contact your county's of-fice of the U.S. Soil ConservationService (SCS) for help in choosing asite and designing the pond. Manymistakes have been made by failureto seek this advice.

When choosing a contractor tobuild the pond, compare the costsand services of several. Find out thecontractor's previous performanceby talking with others for whom thefirm has built ponds.

A state permit is needed for con-struction of the pond if any of thefollowing is true:

— It is to be formed by dammingany running water.

— It is to be connected to anyother running or standing waterbody, including wetlands.

— It is to be within 500 feet ofany other water body.

Contact the nearest DNR officeearly in the planning stage to findout what restrictions may apply toyour situation.

Key considerations in designing asuccessful fish pond are waterdepth, water supply, and formingthe basin and its surroundings toavoid overabundance of nutrientsand aquatic plants. Usually ofsomewhat lesser importance are thesize of the pond's surface and land-scaping details. All of these designconsiderations are interrelated, withone often greatly influencing one ormore of the others.

Pond DepthPond depth is one of the most im-

portant factors for achieving satis-factory fishing. Whether the pond isformed by digging or impounding,and no matter how large its surfacearea, a better fish population is like-ly to result from having water depthof 15 feet (5 meters) or more, wheresoil conditions permit, throughoutas much of the pond as possible.This helps avoid winter and summer

oxygen depletion and resultantstress on fish which can end in poorgrowth or mass die-off. Michiganponds with less than 15 feet of waternot only are more subject to com-plete winterkill in especially coldwinters, but may, in most years,have disappointing fish popula-tions—fewer fish, smaller fish, andless desirable kinds of fish—owingto near-winterkill conditions.

Lesser depth may suffice wherestrong flow of well-oxygenatedspring water prevents dissolved oxy-gen depletion. This is the case introut ponds with large outflow.Even in such ponds, however, depthgreater than 15 feet tends to result insuperior fishing. This may be a mat-ter of more room for the fish and a

greater range of living conditionsfor them—and their food organ-isms—to choose from.

Having depth of 18 to 20 feet isdistinctly better than 15 feet, and 25feet is still better. Beyond thatdepth, we aren't sure whether fur-ther improvement takes place. Therecommendations of 10 to 12 feetfor pond depth, which one oftensees, are based on conditions inmore southerly states and are inap-propriate for the harsh winterclimate of the northern tier ofstates.

We recognize that there are twoproblems which sometimes preventattaining pond depths of at least 15feet—cost and unfavorable soil con-ditions. Excavation costs tend to

become disproportionately higher asdepth increases. If money isn'tavailable for digging at least 15 feetdeep, it would be well to save up un-til there is enough rather thancreating an inadequate pond and adisappointing fishery.

A soil problem which can occur iswhen the proper depth cannot bedug because doing so would per-forate a clay layer, thereby breakinga natural seal, and allowing thepond water to drain away. It dependson the structure of the soils andshould be investigated in advanceby SCS or other knowledgable in-dividuals. If natural clay sealing isbroken to achieve proper depth, thepond bed can be resealed with clay,but that can be expensive.

Berm to prevent runoff into pond

Water depth at least 15 feet4

nutrients is minimized, (2) much ofthe bottom is too deep and dark forplants, and (3) the shallow, well-litside slopes are steeper than plants"like."

One way to minimize nutrient in-flow is to locate the pond where lit-tle land slopes toward it so littlerunoff enters. Runoff can also bediverted away from the pond bymeans of earthen berms, diversionsor grassed water-ways. A filter stripof unmowed grass and other lowplants along the banks reducesnutrient inflow. Other aspects oferosion control are discussed in thesection on landscaping below. If thepond is formed by a dam, an outletstructure that allows discharge fromthe bottom enables draw-off ofnutrient-rich water that accumulatesthere in summer and winter.

As discussed, making pond depth15 feet or more keeps much of thebed dark enough to reduce growthof rooted plants.

Submerged side slopes that extend3 feet into the pond per foot of drop(a 3:1 slope) are sufficiently steep toreduce plant growth while not beingso abrupt as to cause unreasonabledanger to wading children. If the in-cline is of find sand, it is likely to beunstable and slump if steeper than3:1. Coarse sand, peat, or loam maybe stable at a slope of 2 feet horizon-tal distance per foot of drop, andclay slopes of 1:1 may be stable. Ifyour objectives are plant controland maximum amount of deepwater, the steeper the side slopes thebetter, but a slippery clay incline of3:1 or greater will be a great hazardto people or animals that mightwade or stumble into the pond andbe unable to keep their footing.

Wildlife P o n d -Fishing Pond System

Ponds built in areas of heavy ero-sion or nutrient runoff will have ashort life as a sport fishing pond.The erosion will fill in areas of thepond and, combined with the extranutrients, result in increased aquaticplant growth. Under these condi-tions, it may be better to build awildlife pond or a wildlife pond-fishing pond system.

Wildlife ponds or marsh ponds are

typically built with a maximumdepth of about 6 feet. The averagedepth should be 1 to 2 feet. Thepond bank should slope gradually atabout 100:1. These conditionsencourage aquatic plant growth thatwill be consumed or used for coverby various types of wildlife. Nutrientinput from runoff is removed by themarsh plants. Nesting islands orboxes can also be placed in the mid-dle of the pond to encourage water-fowl reproduction.

A wildlife pond can serve as a set-tling pond to cleanse water of excessnutrients and sediments when builtin conjunction with a fish pond.Runoff water should be divertedaway from the fish pond and into thewildlife pond by berms (moundsabout 18 inches high and 3 or 4 feetwide). The wildlife pond should beseparated from the fish pond by adike. The dike will prevent sedi-ments from moving into the fishpond and will prevent fish fromescaping predation in the shallowweedy areas of the wildlife pond(see chapter 5, page 25). An over-flow tube should be installed in thedike to prevent over-topping anddike washout during heavy rains.

A prototype wildlife pond-fish-ing pond system has been built nearthe Bird Sanctuary at the KelloggBiological Station in HickoryCorners, Michigan. For more infor-mation on building and managing aWildlife Pond-Fishing Pond Sys-tem, contact your fisheries orwildlife Extension specialist atMichigan State University.

Surface AreaAs a rule, the larger the pond, the

more dependable its fish populationwill be. While trout ponds of only aquarter acre may support passablefishing if they have strong springflow, most ponds don't provide sat-isfactory fishing unless they are ahalf acre or more—preferably muchmore.

Small ponds may need much moreintensive care than large ones. Thedisadvantages of small ponds may besomewhat alleviated by making themvery deep. Pond depth seems evenmore important to fish populationsthan pond surface area.

10

Landscaping andErosion Control in thePond's SurroundingsWith a little planning, a fish pond

and the area around it can be madevery attractive. Decide whether youwant a natural setting or a morelawn-like one. In a natural landscape,logs, stumps, rocks and unevenground may be fitting. If much of thearea is to be mowed, you may needto smooth the ground and eliminateobstacles during pond construction.

Plant cover should be establishedquickly on raw areas after construc-tion to prevent erosion. Sod or aheavy stand of grasses and legumesis needed on areas of greatest slopeand washing, such as berms, runoffdiversion waterways, tops and slopesof dam embankments, emergencyspillways, and bank slopes of thepond perimeter. The latter should bequickly vegetated back at least 20feet from the water.

Deep-rooted plants such as alfal-fa, sweet clover, shrubs and treesshouldn't be planted on earthen damsor fill embankments. Deep roots tendto weaken such structures and causeleaks, some ponds need reinforce-ment, called "rip-rap," with stone of8-10 inches (20-25 cm) diameterpiled along the shoreline to protectagainst wave erosion, especially inthe case of dam and fill embank-ments.

Mixed clumps of evergreens anddeciduous trees, bordered by shrubs,provide food and cover for wildlifeand give the pond surroundings apleasing appearance. But trees andshrubs shouldn't be planted so nearthe pond that many leaves fall orblow into the water when shed.Leaves that get into the pond use upoxygen when they rot, and they cre-ate layers of litter on the pond bed,as well as furnishing nutrients forovergrowth of water plants. Keepsuch vegetation at least as far backfrom the water's edge as the greatestheight the tree or shrub will reach —preferably much farther back thanthat. It isn't necessary to set ever-greens so far back. Trees and shrubson the shore area may also interferewith fishing.

Fence livestock away from the

Water SupplyIt's advantageous if the pond's

water supply is exclusively ground-water, either from wells, springs, orslower seepage, rather than fromrunoff or stream water. Ground-water tends to be well filtered,whereas runoff and stream wateroften bring in excessive amounts ofnutrient phosphorous and othermaterial. Excessive phosphorouscreates the overabundances ofplants and other organic matter thatcause oxygen problems for fish. Ob-viously, runoffs from barnyards,pastures, and fertilized or erodingcropland are nutrient sources to beavoided. Fertilized lawns andgardens are other sources. Even

stream water that appears clear and"pure" often carries far more nutri-ent into a pond—where plants takeit up—than it flushes out.

Precautions may also be neededwith seepage and spring water. Suchwater is sometimes too low indissolved oxygen for fish as itemerges from the ground. It mayalso be too high in carbon dioxide.Various methods of aeration canalleviate these problems—perhapsat considerable added cost. Ex-cessive amounts of iron and, as itoccurs in some places in the UpperPeninsula, copper dissolved in thewater can also be unfavorable forfish. Have the water tested beforeinvesting in a pond fed by wells,springs or seepage—unless presence

of fish in the same water supplyshows its suitability.

Designing for Controlof Aquatic Plants

While a moderate amount ofrooted aquatic plants may benefitfish in a pond, their overabundanceimpedes fishing and certain manage-ments. Plant overabundance sooneror later creates unfavorable condi-tions for fish. Much can be done indesign and construction to make apond less subject to this problem.

Rooted aquatic plants need lightand nutrients, and they grow best onrather level pond beds. Therefore,they can be kept in check by struc-turing the pond so that (1) inflow of

3:1 slope

Water depthat least 15 feet

Three types of pond construction.

Excavated or dug pond

Impounded pond

Combinationimpoundment and excavation

•

pond. They destroy vegetation of thepond-bank buffer strip, and theirdroppings overenrich the water.Grazing and trampling also weakendams, embankments and spillways. Iflivestock watering is a purpose of thepond, pipe the water to an area wherethe animals won't harm the pond.

Excavatedor Dug Ponds

Dug ponds are built mostly inrather level areas not suited for pondsformed by dams. Many parts ofMichigan are favorable for dug pondsbecause they are fairly flat, the soilsare soft and porous, and groundwaterlies close beneath the soil surface.The pond is then fed by water slowlyseeping in one side of the pit and outthe other. Dug ponds can also bepositioned so that springs upwellwithin the pond or flow into it from ashort distance up-slope. Groundwatercan be pumped into ponds from near-by wells. Sometimes windmills are

used for this. Less desirably (seedrawbacks in section on water sup-ply), dug ponds can be catchment pitsfor overland runoff if soils are clay orother fine material that will holdwater— or if clay or other sealantscan be obtained to line the pond bed.

Groundwater seepage ponds are themost common in Michigan. They aregenerally located in sand or sand-gravel soils through which water eas-ily percolates. Such ponds are possi-ble even in many areas with rathernon-sandy surface soils becausewater-bearing sands and gravels lieclose beneath, and excavation reachesdown into them.

The water level may fluctuate sig-nificantly in seepage ponds as thegroundwater table rises and falls —higher in wet years and wet seasons,lower during drought. Plan excava-tion depth to be more than 15 feetbelow the lowest level that thegroundwater table reaches in a verydry year. Consult an SCS engineer, orother field personnel, for such a

determination. Make test borings tofind the water table in late summer ofa dry year.

When contracting for a dug seep-age pond, obtain written agreementfrom the contractor as to the waterdepth that will be achieved. Con-tracting for a certain pit depth will dolittle good if the water doesn't risesufficiently in it. Again, 15 feet ormore depth during the low point ofsummer water levels is advisable, ifsoil conditions permit.

The type of equipment that is bestfor digging ponds depends largelyupon pond size, site characteristics,and depth desired. Draglines or bull-dozers are generally used. Bulldozersare more adapted to the dryer pondbeds.

The material dug out of the pond,called the "spoil," should besmoothed back away from the pondedge or piled far enough from thepond that it won't erode back into thewater. Using some of the spoil tobuild a gentle berm around the pond

BOTTOM DRAW-OFF DAM - WITH RISER AND STOPLOGS - "TIN WHISTLE"

Corrugated metal riser(diameter at least 4 feet )~ I S ' ^ ^ H a t — L « v e l o f P« v e d emergency spillway

Spillway p i p e s ^ V ^ - C o l l a r to

(diameter at least 18 inches) core trench

SURFACE OVERFLOW DAM — WITH DROP INLET SPILLWAY AND OPTIONAL BOTTOM DRAW TUBE

Concrete riser (diameter at least 4 feet)covered by trash rock

and baffle plateLevel of paved emergency spillway

Bottom draw-off tubewith valveWater depth

at least 15 feet

Bottom drain tube with valves Core trench' Seepage plate

Two common types of outlet structures for dams that form fish ponds. Riser-and-stoplog construction is the simplest design thatallows controlled bottom draw-off. A drop-inlet spillway can accommodate greater variation of flow. It is needed where run-offfrom large land area supplies the pond and where sudden high water is expected.

II

can be helpful in diverting unwantedoverland runoff away.

Ponds dug by draglines are seldomwider than about 90 feet but may bemuch longer. Excavation width isgoverned by the distance a draglinecan move back before it is blocked byits spoil piles—unless the spoil canbe moved.

ImpoundmentsIn "embankment" or "fill-type"

ponds, water is impounded by anearthen dam containing a core ofwatertight material. Such ponds aresuited to areas where slopes rangefrom gentle to steep. It is best tohave a site where a great volume ofwater can be stored by only a smallamoung of embankment fill. Theideal location is where the valley isnarrow at the damsite, and the pondarea is wide and flat but with steepsides.

For fishing ponds, avoid damminga stream. As described earlier in thischapter, they are collecting basins forsilt, sediment, and debris, and unde-sirable fish species can easily enterthe pond. One or more permits may

be needed depending on applicablestate laws. Also avoid sites where theimpoundment dams a river or streamand where there is flooding.

Wave erosion on the dam em-bankment can be a problem in largeponds. Try to choose a site where theprevailing wind doesn't blow alongthe length of the pond toward thedam.

A properly designed impoundmentwill have two outlets for the water—a trickle tube or mechanical spillwayand a vegetated earthen emergencyspillway. The emergency spillway isfor flood flows.

As in the case of dug ponds, it willbe best for fish if the water supply isfrom groundwater rather than fromrunoff. If, however, the impoundmentmust be designed to catch runoffwater, the pond must be located sothat its drainage basin is large enoughto provide sufficient runoff to fill it—and to maintain it in the face of evap-oration and seepage losses. Calculatesurface runoff according to the area ofland draining into the pond, amount ofprecipitation, and runoff characteris-tics involving land slope and porosity,vegetation, and human disturbances of

the land. For a Michigan pond thatdepends entirely on runoff water, 8 to14 acres of runoff basin land are need-ed per acre of pond surface.

Clay and silty clay are good soilsfor impoundment beds. Sandy clay issuitable only if the cost of extra mate-rials for sealing the pond is accept-able. Sites in some areas of limestoneor gypsum are especially unsuit-able—even hazardous—for impound-ments. There may be crevices allow-ing water to drain from the pond. Afair clue to the success of buildingimpoundments in such areas is theprevious experience of nearby pondowners.

Soils for earthen dams should beabout 20% clay by weight and con-tain a wide range of particle sizes,varying from fine sand to coarse sandor gravel. The earth must be com-pacted to minimize percolationthrough the dam. To insure propercompaction, soil moisture must becontrolled in certain ways duringconstruction.

For the dam's vegetated spillway,clay, sandy clay and silty clay aresuitable. Avoid loose sand and othereasily erodible soils.

12

Ponds As Places For Fish To Live

Basic PondCharacteristics forNatural Production

of FishThe ideal Michigan sportfishing

pond has:— a surface area of one-half acre

(one-fifth hectare) or larger,— steep side slopes (about one foot

vertical per three horizontal),— at least a quarter of the bed 15

to 25 feet deep (5-8 meters),— a water supply exclusively by

seepage of groundwater (ratherthan stream water or runofffrom land—even during thehardest rains and greatest snow-melt),

—150-250 parts per million dis-solved minerals,

— an acidity-alkalinity rating of7-8 on the pH scale,

— a location in land with fertilesoil,

— an inflow of only moderateamounts of nutrient chemicals—amounts such as would enterthe pond if the land werecovered by natural, undisturbedvegetation (inflow only ofgroundwater helps avoid ex-cessive nutrient enrichment),

— a moderate amount of rootedplants and algae grown fromnaturally moderate amounts ofnutrients—less than !4 of thepond bed covered by denseplant growths,

— concentrations of dissolved oxy-gen which seldom fall muchbelow 5 parts per million, evenin the deepest water,

— a balance between amount offish and amount of natural foodso that body growth is rapid.

These ideal guidelines applyregardless of whether the pond is forwarmwater fishes or for trout. Apond can have somewhat differentcharacteristics in any of the cate-gories and still produce worthwhilefishing. In many locations, some ofthe ideals cannot possibly be met,even with considerable manage-ment. For example, regulating thedissolved mineral content of ground-water will usually be infeasible, andone should not hesitate to have apond just because the water has only50-100 parts per million.

An ideal coldwater pond for troutwill differ from a warmwater pondprimarily by having greater seepageof well-oxygenated groundwater(springs), which keeps water tem-perature lower in summer.

This section of the bulletin brieflyexplains why the previously men-tioned pond characteristics are im-portant to the well-being of fish.The functioning of ponds is com-plex, but it is understandable andpredictable enough that knowledgeof it can help us manage for betterhabitat and food supply for kinds offish that the owner wants—andthereby to achieve sustained fishingquality.

The Pond EcosystemThe pond is an organized system

of water, soils, dissolved substancesand living organisms. We call thisthe pond ecosystem. Its vast numberof parts continually change and in-teract, driven by energy from thesun, wind and gravity.

Matter and energy enter and leavethe pond continuously. Most miner-als and organic materials that wash,flow or fall into the pond are trap-

Flow of energy and matter into and outof the pond and its drainage basin.

Outflowof water

and energy

Outward

Ra

Water, soil add organic matterwashed in by overland runoff Runoff filtered

/ / by marshMatter washed inby stream inflow

Groundwater seepage filtered by soil

ped and stored there. In contrast,most water and gases that flow insoon flow out again. The pond'senergy is always dissipating outwardas heat, and pond processes cancontinue only if it is replenished.

The pond ecosystem is part of thelarger land-and-water ecosystem ofthe area which drains toward it, call-ed the drainage basin. What goes onin the drainage basin greatly affectshappenings in the pond. For exam-ple, disturbance of vegetation in thedrainage basin may increase runoffof rainwater and the amount of soilit washes into the pond.

Some solid mineral and organicmatter that reaches the pond settlesto the bottom, and some is brokenup and dissolved. Much mineral and

organic matter enters in the dissolv-ed state. Plants use the dissolvedchemicals as nutrients to make moreplant matter.

Some plants are eaten by animals,and some die and fall to the pondbed. Some of the plant-eatinganimals die and drift downward,too, while others are preyed upon byother animals—which in turn maybe eaten by still others. The plantand animal material which animalsconsume is either stored in theirbodies or passes out into the wateragain as solid or dissolved wastes.

The dead plants, dead animalsand wastes undergo at least partialdecomposition and redissolving bythe action of scavenger animals,microorganisms and chemicals. The

14

PRIMARY PRODUCERS

CONSUMERS

DECOMPOSERS

\ ' /

Anglers Other

Large fishes- ^J

Algae, higher plant

Dissolved minerals

Dissolved gases

Water

Small fishesand large invertebrates

Small invertebratesthat eat green plants

redissolved material serves asnutrient for further plant growth.Those materials not completelydecomposed pile up on the pondbed, forming organic mud.

Thus, little of the mineral andorganic matter that comes into apond leaves it, even if there is out-flowing water. Only a bit departs inflights of emerging insects or in fishcarried away by natural predators oranglers.

The interlinked food relationshipsbetween organisms form a "foodweb." The web-like structure givesstability to the fishes' food supplyand to the pond's living community.When a part of the web breaks, aswhen a disease kills off one kind ofanimal, other kinds remain whichmay substitute in its role as food forsome animals and as a consumer ofother organisms—until repopula-tion of the devastated animal cantake place.

When we manipulate a pond eco-system to make it produce especiallygreat amounts of one or severalkinds of fish, this often involves alessening of the kinds of habitatsand kinds of organisms in the pond.This removes many links of the foodweb and may make the living com-munity less stable.

For example, we purposely buildponds to have little diversity ofhabitat so that only a few kinds oforganisms can thrive there—thefishes we particularly want and afew kinds of food organisms forthem. We build uniformly steeppond side slopes to discourageplants because they interfere withfishing and allow development oftoo many young fish. We dredgesmooth, deep pond bottoms suitedfor maximum fish growth and forseining to remove undesired fish.We try to ensure a short, efficientfood chain by stocking only one or

15

The food pyramid of a pond. The totalmass of organisms at any level requires afar greater amount of matter for supportin the level below it. Disparity betweenamounts at each level is far greater thanshown.

Important gases:\ nitrogen,

t carbon dioxide,' oxygen, hydrogen

/ dissolve through surface

Leaves and fragmentsof land plants

some leavesdecay, dissolve ^ A | g a e

\ and *bacteria /

• ,f -.Some dissolves T' Zoo plankton eat

y l d b t iT p

' • y algae and bacteria

Deadorganisms some

decayingorganismsdissolve

Scavengers and microorganisms

two kinds of fish and by eradicatingall others.

Such artificially shortened foodwebs boost production of the in-tended kinds of fish. This is usuallywhat the pond owner wants, ratherthan an "interesting" natural com-munity of fish that doesn't provideas much angling. But we shouldrealize that the simplified communi-ty may be less able to bounce backfrom occasional catastrophes suchas disease, cold snaps, and drouth.Substantial and repeated manage-ment is often needed to keep an un-

natural pond community the waythe owner wants it. There is a sayingin pond management that "onceyou start managing, you have tokeep managing like mad."

Another bothersome kind of im-balance and instability in the pond'scommunity of living things happenswhen there is an insufficient numberof predator fishes (bass). Then smallfish (bluegills, other sunfishes, min-nows) may become so abundant thatthe water flea population is croppeddown to numbers that can't con-sume much of the algae that are pro-

duced. This leads to an overabun-dance of algae, which is not only un-sightly and foul smelling but alsoreduces dissolved oxygen in thepond depths.

Consequences ofOverenrichment

A pond's suitability for fish candeteriorate severely if its supply ofnutrient phosphorus becomes great,as when topsoil, leaves, fertilizers,or human and livestock wastes flow

16

I Heat from[ pond bed

I and decay

Heat andwater vapor

given offby plants t«,' <Heat and

water vaporgiven offby pond

Seepageom pond Int

ound water

ss

More material depositsat pond bed than

redissolves back into water

Inner workings of the pond in rough outline. This sketch ofmovement of energy and matter looks complicated, but the ac-tual situation is far more complex. Most mineral and organicmatter entering the pond becomes trapped in it and is to someextent recycled. Most energy that enters from the sun leavesagain rather soon. Water also flows through.

Food web (top) and food chain (bottom) contrasted. The ar-rows point in the direction of predatory or "grazing"pressure. A chain-like system may produce more of certainfishes that we desire, but a break in one link may severely dis-rupt production. The web-like system has many more partsand is therefore more stable and more productive in total—but not necessarily of the fishes which anglers most appreciate.

17

POND WITH MODERATE FERTILITY

SUMMER

Deep light penetration

Sparserootedplantgrowth

Sparse algal growth

Sparse algal growth

arm water

thermocline

-cold water-

OVERENRICHED POND

SUMMER

Shallow light penetration 5$.V Dense algal growth -"-^

Dead algae sink _ y Denserooted

plantToo dark for algal growth growth

Plants replenish dissolved O2 throughout

WINTER

No light penetration

,i''.'"iiin in .uTir

Much decay of organic matterDepletion of dissolved O2 in lower zone

WINTER

No light penetration

• snow^

Enough dissolved O2 remains for fishthroughout pond because little is

consumed by plants anddead matter

B g — ice ^ ijn.iTT

Overabundant.^Depletion ofrooted plants dissolved O2

Overabundant algae-* throughout

Decay of organic matter

Winterkill of fish

The hazards of pond overenrichment.

in—or if fish feed is added. Algaeand other plants then become over-abundant. Stagnant lower layersmay lose dissolved oxygen and havesuch build-up of toxic gases in sum-mer and winter that fish becomesick or die. This problem is especial-ly acute in winter under ice cover,and mass die-offs of fish, termed"winter kills," are common inshallow ponds with much organicmatter.

Facts About Waterand ChemicalsDissolved in It

Water is the chemical basis of life.It moves and carries things with it,including the many substances itdissolves. It affects light entering apond. It buoys up plants andanimals of a pond. It changes indensity as it changes in temperatureand chemical content. Water isalmost unique among substances in

18

being lighter as a solid than as a li-quid. The fact that ice floats atopponds in winter rather than growingupward from the bottom (or fallingthere after forming at the surface) isprofoundly important to pond life.

Although rain and snowmeltwater wash solid and dissolved sub-stances from the land, a pond canoften get much of the carbon,nitrogen, oxygen and hydrogen itsorganisms need right from the gasesin the air. Pond water can be rich orpoor in other plant nutrients (cal-cium, potassium and phosphorus),depending on their abundance andsolubility in the surrounding land.

Many ponds have only low ormoderate amounts of aquatic vege-tation in them because, although allother conditions are right for grow-ing many plants, little phosphorusenters from surrounding land. Awell-vegetated landscape will permiteven less phosphorus to enter thepond. In such situations, phosphorusis the "limiting factor."

90° 85°

mixed 40 toover 100 ppm

over 100 ppm

Pond alkalinity regions of Michigan. Most of the regions havea rather broad mixture of water alkalinities.

Table 4-1. Pond carrying capacity related to alkalinity of thewater. These are very rough indications of how much fish canbe supported by naturally-occurring food in a pond. Par-ticularly for trout, much greater amounts can be sustained inthe pond by artificial feeding, but with drawbacks explained inChapters 7 and 8.

Approximate carrying capacity (pounds/acre)

ColdwaterWarmwater ponds ponds

Alkalinity of waterBass orcatfish

Bluegillsor otherpanfish Total** Trout**

More than 100 ppm* 50-100 200-400 250-500 150 or more40 to 100 ppm 25-50 75-200 100-250 25-150Less 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 theform of young fish that are too small for angling. In coldwaterponds, all or most of the trout will usually be large enough forangling—and the poundage shown may provide about as muchfishing as that shown for warmwater fishes on the same line.

The amount of phosphorusdissolved in the water does indeedlimit, in most ponds during thegrowing season, the algal and leafyplant production which is the basisof the food web. Increasing theamount of phosphorus increasestotal production of pond life—butthis does not always result in greaterproduction of fish. Often only aportion of total algal production isfrom kinds of algae that are usefulto fish. The size of that portiondepends on the alkalinity of thewater.

Alkalinity is the amount of cer-tain minerals dissolved in the water.The main constituent in the alkalini-ty of Michigan water is usually cal-cium carbonate (CaCO3), the"lime" we see deposited in the bot-tom of a tea kettle when "hard"water is heated and evaporated.

When water is of low alkalinity,presence of a small amount of phos-phorus results in small amounts ofthe kinds of algae that water fleasand other fish food organisms liketo eat. As more and more phos-phorus is added to low alkalinitywater, however, a point is soonreached where these beneficial algaecease to increase. Instead, the addedproduction takes the form of"bluegreen" algae, a class which

algae-eating animals don't like.Thus, rather than supporting thefood web that leads to more fish,bluegreen algae proliferate withoutbeing cropped back by grazers,reach nuisance abundances, die, anddirectly support decay bacteria—which become so abundant as todraw excessively on the pond's sup-ply of dissolved oxygen. The resultof too much phosphorus for theamount of alkalinity is, then, a con-dition of occasional oxygen stresswhich may harm fish.

Water that is more alkaline willenable more phosphorus, if present,to grow a greater amount of thekinds of algae that result in morefish. At any level of alkalinity, how-ever, there still can be a phosphoruslevel above which bluegreen algaewill begin to dominate the pond.

Thus, the more alkaline a pond is,the greater its potential for produc-ing fish. But the fulfillment of thatpotential will be seen only if there isjust the right amount of phosphorusand if other conditions, such astemperature, are also just right.

There are other benefits frommoderate to high water alkalinity,as well. Alkalinity helps avoid avariety of chemical conditions un-favorable to fish and other aquaticlife. The dissolved minerals "buf-

fer" against extreme acidity. Acidscan come from various sources. Forexample, rainwater is becoming in-creasingly acidic, owing to air pollu-tion of certain kinds, and this ismaking conditions unsuitable forfish in ponds that aren't well buf-fered. Alkalinity also maintainsconditions in which fish are less sub-ject to poisoning by the presence ofcertain dissolved metals.

Michigan ponds range in alkalini-ty from about 4 parts per million(ppm) to over 300 ppm. Most arebetween 50 and 240 ppm. Alkalinityof 40 ppm seems to be a pivotalvalue below which fish productiondeclines and above which fish pro-duction is moderate to high, butwith no steady trend of increasewith increasing alkalinity because ofvariability in other key conditions.

Pond Breathing,Circulation andStratification

A pond exchanges gases with theair above it. This is a form ofbreathing. The gases and otherdissolved and drifting materials aremoved about the pond by water cir-culations caused by wind and gravi-ty. In winter, ice may greatly reduce

19

circulation and almost completelyblock pond breathing. In both sum-mer and winter, the pond watersorts itself into layers representing agradation of temperature, hence dif-ferent density. The heaviest waterlies on the bottom and the lightest atthe top. During summer stratifica-tion or layering, only the upper partof a deep pond will be circulated bythe wind. The lower part will berather still. Summer and winterstratifications are usually broken upin fall and spring during the timethat cooling and warming change allthe water to an equal temperatureand equal density. These events aredescribed in the figure at right.

Investigating PondSuitability for Fish

Pond owners often ask if thewater can be tested simply for fertil-ity and other chemical characteris-tics to evaluate its fish-producingcapacity or to find out why fishhaven't done well. Determiningthese things is far more involvedthan just sending water samples to alaboratory. As previously described,ponds are complex, and their condi-tions change continually. The fore-most need is to be alert against landdisturbances, water runoff into thepond, and human or livestockwastes that could cause overenrich-ment. Such observation of thepond's surroundings, combinedwith a program of water temper-ature and dissolved oxygen mea-surement in the pond, may provideenough information for pond man-agement.

Judging a pond's productivecapacity or diagnosing its problemsis best done by a professional biolo-gist. (Obtain list of consultants asshown in Appendix.) Properly train-ed aquatic biologists can evaluateconditions of the pond site and sur-roundings and can interpret temper-ature and oxygen data. At consider-able added cost, the consultantshould be able to make keymeasurements (alkalinity, pH, inor-ganic nitrogen, phosphorus, tem-perature and a few others) usingspecial instruments and methodsjust after the ice goes out in spring,and with the results estimate total

WindAUTUMN OVERTURN

About 39° F \throughout )

Water all of same densityFull circulation Dissolved oxygen replenished

WindSUMMER LAYERING Wind.

WINTER LAYERING

Dark throughout

°For"a bTTcooTerDissolved oxygen diminishes

due to organic decayin layers cut off from circulation

WindSPRING OVERTURN

. ^Whole pond same ~\Vtemperature in range/V J about 40-60° fjJ

Water all of same densityfull circulation. Dissolved oxygen replenished

production of algae and the amountthat contributes to the food web forfish—as well as the amount that willbe in the form of bluegreen algae.Such a detailed analysis shouldresult in advice on adjusting thebalance of alkalinity and phos-phorus for best fish productivity.

The pond owner may be able toparticipate with a professionalbiologist in pond investigation—or,after study of references, mayundertake measurements on his/herown. Much depends on knowledgeof science, the amount of time onecan spend, and the instruments andmaterials available. Various handyanalysis kits for dissolved oxygenand other determinations are nowsold (see Appendix).

Professional help is especially ad-visable with regard to design of theinvestigational program and inter-pretation of the results. Design in-volves planning the right samplingat the right times. Interpretation in-volves judging what the data meanin terms of pond biology and whatthe implications for managementare.

Knowing maximum water depthand calculating mean depth are im-portant, as are observing abundanceof aquatic plants and keeping

Circulation and thermal (or density)layering of water in ponds. Not onlytemperature but amount of oxygenavailable to fish is strongly influenced bythe progression of circulation and layer-ing through the seasons. Very shallowponds (not shown) may have completecirculation for much of the summer, butthey are much more likely to have deple-tion of dissolved oxygen in winter.

records of fish caught (species,length and weight). It is essential toidentify possible sources of phos-phorus overenrichment, such as sep-tic systems, livestock wastes, soiland fertilizer erosion, and roadwayrunoff.

Much of direct importance to fishcan be learned by systematicallymonitoring dissolved oxygen (DO)and water temperature within thepond. Along with the chemical kitfor DO measurement, a specialsampling device (DO sampler)should be obtained (see sources inAppendix).

Crucial times to analyze watertemperature and DO are (1) in midor late summer after a week or moreof very hot weather and (2) in winterafter ice and snow have been on thepond for a month or more. For amore detailed picture, monitor the

20

Table 4-2. Water temperature at various depths1 in an exam-ple of a pond, measured on the 15th of each month at thedeepest point in the pond which is 1812 feet deep. These aresame measurements shown in the figure at right.Waterdepth _(feet) Jan;

Temperature (°F) at Mid-MonthFeb1 Mar! Apr May Jun Jul Aug Sep Oct Nov Dec2

surface24689101112141618

3236383939

39

39393939

3233363839

39

39393939

4444444444

44

44444444

5050505050

50

50505050

606060606060585250505050

676767676767625552525252

717171717171655853535353

757575757575706154545454

626262626262605754545454

5151515151

51

51515151

4646464646

46

46464646

3239393939

39

39393939

'Measurements made at regular 2-foot intervals, except at one-foot in-tervals in areas of rapid temperature change.

2Pond covered by ice.3About one week after ice has melted.

Figure at upper right:General example of water temperature change during the yearin a small, fairly deep "warmwater" pond. These are plots ofsome of the data in Table 4-2.

Variation can be great between different ponds and fromone year to the next in the same pond, depending on waterdepth, wind strength, air temperature and other factors.Temperature affects water density. Water is heaviest at 39 °F(4°C). Thus, water nearest 39°F tends to be at the bottom,with warmer—or, in winter, cooler—water floating on top ofit. This vertical density layering, when it occurs, results in agradation of temperature from top to bottom. Then fish canchoose the depth offering preferred temperature—if notprevented by insufficient dissolved oxygen.

Winter Layering—Ice covers the surface. Water is 32° justunder ice and is progressively warmer at greater depths.Deepest water is near 39°. Warming by groundwater seepagemay alter the curve.

Springtime Overturn and Even Warming—After ice melts inMarch of April, wind mixes water evenly throughout as thepond warms. Temperature stays equal from top to bottom aswarming occurs.

Late Spring and Summer Layering—Will not often occur inmany ponds, especially not in ones shallower than shown here.Layering happens if upper water becomes, by intense warm-ing, so much lighter than lower water that wind cannot over-come the density difference and can no longer mix all the wayto the bottom. Then mixture occurs only in upper water. Thewell-mixed upper layer has a thinner layer of water with rapid-ly decreasing temperature between it and the cooler waterbelow.

The upper layer will usually extend deeper than shown.Wind may become strong enough to destroy layering after ithas formed.

Seepage of very cool ground water into the pond may makelayering more distinct and stable.

Autumn Overturn—Surface water cools, becomes denser,and sinks, mixing with warmer water just beneath. Thus, up-per layer is cooled to density near that of lower layer, and windcan mix the whole pond again. Complete fall mixing can occursolely by sinking of upper water as the weather becomes col-der; wind is not needed. Fall overturn halts when ice blockswind action and upper water becomes colder, hence less dense,than water beneath it which is nearer 39 °F.

POND TEMPERATURE PROFILESEarly spring

Winter overturn Late Summerlayering and warming spring layering

Surface Or-«K l c e '/—<?—r-9— —"M»—9 9 1 nO

Q.©•o

Pond bed

Late fall overturnand cooling

15-

80° F10° 20°C

Water temperature

DISSOLVED OXYGEN PROFILES In this range during_ spring and fall overturnsour- ~" Ice

Duringlate winter

layering

Duringsummerlayering

face 0

£ 5

Q.

m

15

Pondbed

0 2 4 6 8 10 12Milligrams of oxygen per liter of water (parts per million)

Dissolved oxygen at different depths in the same pond, asaffected by the wind mixing and thermal/density layeringshown in the figure on page 20.

During Spring and Fall Overturn—Large amounts of ox-ygen can dissolve into the pond from the air because water thatis cooler can hold greater concentration of dissolved gases.Amounts of dissolved oxygen are the same at all depthsbecause water is well circulated throughout. Concentrations of9-12 ppm commonly occur.

During Summer Layering—Warmer water of upper layercannot hold as much dissolved oxygen as could the coolerwater in spring time. Cool water of the deep layer could holdmore dissolved oxygen, but decay of organic matter consumesoxygen, and the lower water cannot obtain more because den-sity layering prevents it from being circulated into contact withthe atmosphere. Therefore, dissolved oxygen decreases in thelower layer, and it may become unfit for fish.

During Winter Layering—Ice and snow block entry of lightand of oxygen. Plants have too little light for photosyntheticproduction of oxygen, and none can dissolve into the pondfrom atmosphere. Respiration and decay consume dissolvedoxygen. Concentrations decrease the most near pond bottomwhere there is more organic matter. Fish are forced upward in-to layers having sufficient dissolved oxygen.

21

complete annual cycle of pondtemperature and DO by samplingevery week or two.

In summer, make temperatureand DO measurements before 6a.m. and again at 3 p.m. Sample atintervals of 1-3 feet (30-100 cm)throughout the water column wherethe pond is deepest. (Once found,this point can be marked with a sim-ple buoy, such as a plastic milk car-ton on a string attached to a brick.)If an electric thermometer isn'tavailable, use a fisherman's ther-mometer encased in a water-collect-

ing vial (available at sporting goodsstores). Lower to desired depth,then wait for the thermometer to ad-just to temperature.

Results of the temperature andDO measurements should be record-ed as tables and possibly also asgraphs. Examples are shown onpage 21. These are called temper-ature and DO profiles. If taking andanalysing DO samples at each of thedepth intervals is too time-con-suming, then take just a few keysamples. For example, take one atthe bottom of the pond, where DO

is most likely to be inadequate, andone at a medium depth.

General guidelines for determin-ing suitability of ponds for warm-water or coldwater fishes arecovered in Chapters 7 and 8 on man-agement for fishing in each of thesekinds of ponds. Proper temperatureand DO levels are discussed there.

Additional reading of literatureon pond and lake biology is recom-mended, especially if the owner in-tends to make and interpret his/herown measurements. A list of refer-ences is at the end of the bulletin.

22

Kinds of Fish To Use In Ponds

It's important to know somethingabout the lives of fishes used inponds. Each species differs from allothers in its characteristics offeeding, surviving, growing and re-producing. Ponds should be design-ed and managed with specific re-quirements of the fish in mind. Ifthe pond environment is unsuitablefor the kind of fish stocked in it, re-duced growth, insufficient repro-duction, or poor survival mayresult.

There are two basic categories ofpond fishes—warmwater and cold-water fishes. Warmwater fishes suchas bass, bluegills, other panfishes,or catfish, do best in ponds wheresummer water temperature is morethan 70 °F (21 °C). A pond may besuited for coldwater fishes (thevarious kinds of trout) if summerwater temperature remains below70° when measured a foot below thesurface near the center of the pondand if dissolved oxygen concentra-tion stays above 5 ppm.

The so-called "coolwater" fishessuch as northern pike, muskellunge,

walleye and perch, generally don'tthrive in small bodies of water. Theyaren't considered suitable for pondfisheries in Michigan.

Information on stocking, harvestand other management is in Chap-ters 7, 8, and 9 of this bulletin. In-formation on where to get fish forstocking is in Chapter 6.

Coldwater FishesThe coldwater fishes include trout

and their relatives such as salmon,grayling and white fishes or ciscoes.Of these, only trout are presentlyconsidered suitable for coldwatersportfishing ponds in Michigan. Tosurvive and grow well, trout requirewater temperatures that seldom riseabove 70 °F (21 °C). Dissolved oxy-gen levels should stay above 5 ppm,which is high compared to the needsof warmwater fishes.

As with other fishes, trout growthvaries greatly between ponds,depending on food supply, crowd-ing, and size of fish.

Trout eat a wide variety of organ-

Table 5-1. Summer length ranges at various ages for fishes in Michigan ponds. Theseare rough statewide values. Growth may be somewhat greater where fish are un-crowded and temperature and food supply are ideal. Growth can be much slower,especially where ponds are overpopulated.

Kind of fish

Rainbow trout**Brook troutLargemouth bassSmallmouth bassChannel catfishBluegill

Firstsummer(Age 0)*

4-62-41-41-41-41/2-2

Secondsummer

(Yearling)

9-146-86-84-75-73-4

Length

Thirdsummer

(2-yr-old)

14-178-128-107-108-104-5

in inches

Fourthsummer

(3-yr-old)

15-199-1410-1210-1211-135-6

Fifthsummer

(4-yr-old)***

11-1612-1412-1413-156-7

Sixthsummer

(5-yr-old)* • *

* * *

13-1713-1715-17

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

Three kinds of trout that can be used incoldwater ponds. The brown trout isusually not advisable, however.

UARGt SPOTS

SQUARE TAIL

RAINBOW TROUT

BROWN TROUT

SMALL DARK SPOTS

BROOK TROUT

WHITEUN EDGE

isms. They prefer zooplankton, in-sect larvae and crayfish. Supple-mentary feeding is not recommend-ed unless large numbers of trout arestocked.

Trout spawn on gravel beds instreams. They don't spawn suc-cessfully in most ponds. Popula-tions are maintained by periodicstocking. Brook trout can some-times reproduce in gravel or coarsesand where springs upwell in pondbottoms.

Rainbow Trout (Salmo gairdneri)Rainbow trout are the most adap-

table of the trouts for use in Michi-gan ponds. They are readily avail-able from dealers, grow fast, areeasily caught, can withstand warmerwater than other kinds of trout, andgenerally do well in all parts of thestate where coldwater ponds exist.Rainbow trout grow best when thewater is between 54-66°C (12-19 °C).They commonly reach a size of 15inches (38 cm) in about three years.Few usually live long enough in apond to reach 20 inches (50 cm).

Brook Trout (Salvelinus fontinalis)Brook trout are also very suitable

for Michigan coldwater ponds, butfor best growth they need water of48-60 °F (9-16°C), which is coolerthan for rainbow trout. Therefore,

brook trout are more widely used innorthern than in southern Mich-igan. Brook trout are also easy tocatch and can provide especially tas-ty table fare. They may grow as wellas rainbow trout up to a size of 10inches (25 cm), after which theirgrowth is slower. A 15-inch (38-cm)brook trout is an exceptionally largeone, but a few of 18 inches (46 cm)or longer occur in Michigan ponds.For fishing variety, rainbow troutmay be stocked together with brooktrout.

Brown Trout (Salmo trutta)Brown trout are less desirable in

ponds because they are relativelyhard to catch. While this may fur-nish a welcome challenge to skilledanglers, it disappoints many people,and a stocking of brown trout usual-ly produces a far lower total harvestover the years than does a stockingof rainbow or brook trout. They canlive 5-7 years, despite heavy fishing,even by skilled anglers. Trout over18-20 inches (46-50 cm) can be verycannibalistic which may render fur-ther stocking with fingerling oryearling trout infeasible—unless thelarge brown trout are removed. Thismay require use of fish toxicants.

Hybrid TroutHybrids between various kinds of

trout are sometimes available andcan be interesting to use. They areunusual and often grow faster thanpurebred trout, but may be hard tocatch. They usually aren't practicalfor the pond owner who is simplyinterested in recreation and a fewfish on the table.

Warmwater FishesThe primary warmwater fishes us-

ed in Michigan ponds are membersof the sunfish or bass family: thepredatory largemouth and small-mouth basses and the smaller sun-fishes, such as bluegills, pumpkin-seeds, and green sunfish. Anothercommonly used warmwater fish isthe channel catfish. Various min-nows of use in ponds could also beclassed as warmwater fishes, but wewill discuss them later under theheading of forage fishes.

Largemouth Bass (Micropterussalmoides)

Largemouth bass are stocked inmost of Michigan's warmwaterponds. They adapt to a wide rangeof pond conditions, can grow tolarge size, and are a very populargame fish. Their growth in Michi-gan varies, depending on food sup-ply, competition with other fishes,and water temperature. They grow

24

deep notch

LARGEMOUTH BASS

upperextends beyond" eye fes; - ; - < * : •

dark lateral band

shallow notch

SMALLMOUTH BASS

upper jaw to centerof eye vertical bars

Largemouth and smallmouth bass. Thelatter is especially suitable where watertemperature is a bit too cool for large-mouth bass but too warm for trout.

fastest when the water is above 75 °F(24 °C). Although largemouth bassmay live for 10 years, the averagepond has very few older than 5years.

Young bass eat water fleas, in-sects, and very small fish and cray-fish. Adults prey on almost anyavailable animal that fits in theirmouth, such as fish (including theirown offspring), crayfish, tadpoles,frogs, worms and insects. In Michi-gan, it's best to stock minnows asforage for largemouth bass. Thebass prefer them by far to bluegillsand other panfish.

Most female largemouth bass firstspawn when 2-4 years old, or about10 inches (25 cm) long in Michiganponds. Spawning occurs in May orJune when the water is between 60°and 75 °C (15-24°C). To form anest, the male sweeps a shallow cir-cular depression in sand or organicbottom at a water depth of 2-6 feet(60-180 cm) and usually near hidingcover. He fertilizes the eggs as thefemale scatters them on the nest,and he guards them and the newlyhatched fry until they leave the nestin a school. Numbers of largemouthfry hatched per nest vary consider-ably. An average of 4,375 wasfound in one Michigan study. Lessthan one percent of the eggs carriedby each female will usually surviveuntil the first autumn.

Survival may be reduced by sud-den drops in water temperature, bypredation on eggs and fry (particu-larly that of bluegills and other sun-fish), and by competition for foodwith other fishes.

Smallmouth Bass (Micropterusdolomieui)

The smallmouth bass, anotherlarge member of the sunfish family,is suitable for ponds that have cleangravel beds for spawning and some-what cooler water than is best forlargemouth bass. For these reasons,old gravel pit ponds often furnishexcellent smallmouth bass fishing.Smallmouths are sometimes classi-fied as a "coolwater" fish ratherthan in the warmwater group. Manyanglers like smallmouth bass betterthan largemouth because they fightharder. Their feeding, growth,reproductive habits, and manage-ment are roughly similar to those oflargemouth bass.

Bluegill (Lepomis macrochirus)The bluegill is probably the fish

that is most frequently stocked inwarmwater ponds, but it is often un-satisfactory in Michigan because ofstunting. Pond owners who wish tostock bluegills should be cautionedthat, although several years of goodfishing will probably follow the in-itial stocking, intensive management

is required to maintain desirablebody growth. This is because blue-gills breed prolifically, overpopulatethe pond, and severely overgraze thefood supply, whereupon growthdecreases. Despite stunted bodysize, they remain prolific.

Bluegills feed on a wide variety oforganisms, including insects, waterfleas, fish eggs, and very small fish.Some rooted aquatic plants andalgae are also eaten.

Growth varies, depending largelyon how crowded the bluegills are.Under favorable conditions, theyreach 6 inches (15 cm) in 2-3 yearsbut in many ponds, they reach thissize only after 4-6 years.

In Michigan, female bluegillsreach sexual maturity by the secondto fourth summer of life and pro-duce 6,000 to 27,000 eggs per year,depending on body size. Bluegillsspawn over almost any type of bot-tom in water 1 to 3 feet (30-90 cm)deep, starting in May or June. Aswith bass, the male bluegill buildsand guards the nest. Nests are usual-ly 6-12 inches (15-30 cm) in diameterand close together. The average nestcontains about 18,000 fry whichmay be from more than one female.

Bluegills have a long spawningseason, generally lasting from lateMay to August. Females ripen atdifferent times, and the eggs from asingle fish mature gradually. A

25

female may deposit eggs in batchesover a several-week period. Thelong spawning season assures thatthere will be offspring even ifadverse conditions occur duringsome parts of it.

The bluegill does have some desir-able qualities: It is easily caught, is agood scrapper on light tackle, and istasty. It's ideal where you want fastaction for kids.

Hybrid SunfishHybrid sunfish are artificial crosses

usually between green sunfishfemales and males of other specieslike the bluegill or redear sunfish. Ifthe fish farmer producing the hybridsunfish was very careful in selectingthe parents so that only female greensunfish and only males of the otherspecies are present in the breedingpond, the resulting offspring couldrange from 65 to nearly 100 percentmales. Since most hybrid sunfish aremale, reproduction may be reduced inponds that contain only hybrids.Under these conditions, the hybridsunfish may also grow faster thannormal bluegill sunfish. However,hybrid sunfish should not be stockedunder the following conditions:

— If normal green sunfish orbluegills are already in the pond; thehybrids can backcross with their par-ent types since the hybrids are fertile.

— If ponds already have a stuntedsunfish population; they will competefor the same food and will not growfaster, they will also be able to breedwith the stunted sunfish.

— If the pond is shallow andweedy; the weeds will provide placesfor the offspring of the hybrid sunfishto avoid predation. Overpopulationwill only be forestalled by a few years.

Channel Catfish (Ictaluruspunctatus)

Catfish stocking in Michiganponds has increased, owing to theirgreater availability since extensivesouthern catfish farming developedin the 1960's. But the catfish hascertain drawbacks in ponds of nor-thern states. They do not generallyspawn successfully in ponds unlessspecial spawning structures are in-stalled. Also, their growth in Mich-igan is slow compared to growth inthe South. The catfish is a truly

stiff blackopercular flap GREEN SUNFISH

olive dingy colored body

PUMKINSEEDlarge mouth

short'and red spot onrounded pectoral opercular ftap

finssmalt mouth

flexible blackopercular flap

"sunny" sides

long pointed pectoralfins

black spot ons-••••"•;•> dorsal fin

BLUEGILL

7-8 dorsal spines

dark markings

BLACK CRAPPIE

WHITE CRAPPIE

Panfishes — these generally are unsatisfactory in Michigan ponds.

warmwater fish which grows fastestin water over 80 °F (27 °C). In fact,catfish farming is possible only insouthern states or where the waterexceeds 70 °F (21 °C) for at least 4months each year.

Nevertheless, catfish graduallygrow large enough to provide recre-ational fishing in many southernMichigan ponds. They normally

reach 12 inches (30 cm) after 3-4years.

Catfish eat many types of food,both living and dead: insect larvae,crayfish, snails, worms, clams, fishand various items which fall into thepond.

Females usually mature at 13-16inches (32-40 cm) in length. Theyspawn in a cavity such as beneath

26

CHANNEL CATFISH

bluish or si/ver grey color

tail deeply forked

upper jaw longer ihsn tower

BLACK BULLHEAD

BROWN BULLHEAD

pectoml spine with sharp teeff)

YELLOWBULLHEAD

|pectoral spine w'tfh sharp teeth

Channel catfish and bullheads.

Olive gray color

FATHEAD MINNOWLarge scales

GOLDEN SHINER

Silvery gold color

Olive back Black spotabove dark stripe \ K J KK a

\ J0£%&t, Spot

BLUNTNOSE MINNOW

undercut banks or in hollow logswhen water reaches 75 °F (24 °C).The male guards the eggs and fryuntil they school and leave the cavi-ty.

Forage FishesSmall fishes, such as minnows

and shiners, can be stocked in pondsto provide forage for bass and cat-fish, although it will not always benecessary to do so. NEVER STOCKFORAGE FISH FOR TROUT.Trout don't need them, and thesmall fishes will compete for thefood that the trout do eat.

The most suitable bass foragefishes in Michigan are the fatheadminnow (Pimephales promelas) andthe bluntnose minnow (P. notatus).The golden shiner (Notemigonuscrysoleucas) can often also be usedwith success. These all feed onplankton and insects and willreproduce in Michigan ponds ifthere is suitable spawning habitat.

Bluntnose minnows seldom ex-ceed 4 inches (10 cm), and fatheads3 inches (7.5 cm). Golden shiners at-tain a maximum length of about 10inches, and if many in the pondreach 6 inches (15 cm) or larger, thismay create competition for the foodof young bass. This is a disadvan-tage of golden shiners, and for thisreason, fathead minnows are usual-ly preferable as bass forage.

All 3 species will spawn when 2-3inches long and normally severaltimes throughout spring and sum-mer. Spawning starts when thewater warms to 65 °F (18.5 °C) inareas which are 1-2 feet (30-60 cm)deep. Golden shiners deposit theireggs on aquatic plants. Fathead andbluntnose minnows lay eggs on theunderside of rocks, tile, boards orlogs. Adult fatheads usually dieshortly after spawning.

Fishes NotRecommended forPond ManagementSome fish are not recommended

for stocking in Michigan ponds if

Forage fishes for bass or catfish in Mich-igan ponds. NEVER stock minnows orother forage fishes in trout ponds!

27

many years of quality fishing is thegoal. Bluegills may be put in thiscategory (see page 25 and also chap-ter 7 for more detailed discussion).These and others may enter pondsduring floods or through pond out-lets from nearby waters.

Trespassers, such as well-meaningneighborhood kids, are notoriouslyfond of stocking fish from nearbyditches, streams and lakes. Pondowners should learn to readily iden-tify the following fish and try tokeep them out of their ponds for thefollowing reasons:

Crappie (Pomoxis spp.), YellowPerch (Perca flavescens), GreenSunfish (Lepomis cyanellus), andBullheads (Ictalurus melas, natalisand nebulosus)

These fish, like bluegills, tend tooverpopulate the pond and becomestunted. They compete with and preyupon the eggs of other gamefish,particularly bass. These fishesshould only be stocked in largerponds if largemouth bass greaterthan 12 to 14 inches are present andprotected by catch and release fish-ing. Additional controls on theirnumbers may also be required toprevent overpopulation and stunting,such as destruction of nests and trap-ping and removing young.

Carp (Cyprinus carpio), andSuckers (Catostomus spp. andothers)

These also compete with gamefishfor food and prey on their eggs.They are bottom feeders which roilthe water, hampering sight-feedingby gamefish. Common carp aresometimes used to help control nui-

Some of the fishes usually best kept out of ponds.

sance aquatic plants because theyuproot plants and the increased tur-bidity reduces light penetration forplant growth.

Northern Pike, (Esox lucius),Walleye (Stizostedion vitreum vit-reum), and Muskellunge (Esoxmasquinongy)

Although survival is certain inmost ponds, these "coolwater" fisheswon't reproduce and are very expen-sive to purchase. They often preyheavily on bass and catfish, but noteffectively enough on stunted pan-fish populations to remedy suchproblems.

ExoticsMany species of fish exist in the

world which are not native to Michi-

gan and most would not survive inthe wild here. However, certainspecies have the potential not onlyto survive here, but to reproduce.When this occurs, they become anuisance and compete unfavorablywith native fishes. The commoncarp is the best example of an in-troduced exotic which has hadadverse effects on some native fishpopulations. The grass carp (whiteamur), Japanese weatherfish, ide,rudd, bitterling and tench are otherexotics which could become estab-lished in Michigan waters and com-pete with native fish for food andliving space. For this reason, thesespecies may not be imported intoMichigan as eggs, larvae, juveniles,or adults.

28

How and Where To Get Fish For Stocking

There are two ways to obtain fish foryour warmwater pond—purchase themfrom a licensed game fish breeder (livefish dealer), or catch them and plantthem yourself. Obtaining them from alicensed game fish breeder is easiest,most economical and safest in the longrun because you can get them at justabout any time and in the number need-ed. A list of Michigan licensed gamefish breeders is available at no cost fromDNR District offices (Appendix), orany of the county SCS field offices.

If you choose to catch your own fishto stock your pond, be sure they are freeof unwanted parasites and in good con-dition. The stress from catching the

fish, holding them in a cooler or on astringer, and transporting them to yourpond could make the fish unsuitable forstocking. You might obtain them fromsomeone else's pond or from publicwaters. In the latter case, you mustadhere to all state fishing laws. Thismeans you must have a fishing licenseand abide by the regulations governingseason, bag limits and size limits. Forthese and other regulations, especiallythose governing the use of seines andnets, consult the "Michigan FishingGuide," the DNR's annual statement ofregulations, available where licensesare sold.

29

30

Managing Warmwater Ponds For Fishing

Determining If a PondIs Suitable for

Warmwater FishFor warmwater fish, much of the

pond should be warmer than 70 °F(21 °C) for most of the summer. Ifcooler, it may be better for trout(Chapter 8).

Measure water temperature on ahot summer afternoon a foot belowsurface near pond center. If over70°F, it's probably suited for warm-water fish. This is just a roughguide. Warmwater fish grow best at75°F(24°C) or more.

In case of borderline tempera-tures, there are three alternatives toconsider:

— Try trout. Often they do well ina borderline pond for severalyears until dissolved oxygencontent of the water falls toolow (under about 5 parts permillion) due to accumulation oforganic matter.

— Try smallmouth bass (with orwithout minnows). They prefersomewhat cooler water than dolargemouth bass and otherwarmwater fishes.

— Try largemouth bass.Try trout only before any other

kind of fish is stocked. This willavoid competition from residualbass or minnows. In borderlinecases you can economize by usingonly a token stocking of a dozen orso fish per acre, then follow theirprogress by catch-and-release fish-ing. If they survive and grow wellthe first year, stock more.

For warmwater fish, summerdissolved oxygen can be as low asabout 3-4 parts per million, butshould be higher than 5 ppm most

of the time. Oxygen will be moreplentiful in summer and winter ifwater depth is at least 15 feet (5meters) and plant nutrients low tomoderate, so excessive build-up oforganic matter doesn't occur.

For more information, see Chap-ter 4, "Ponds as Places for Fish toLive."

StockingWhile stocking is far from being

the only important aspect of manag-ing for good fishing, the kind of fishused, their body size, amountstocked, and time of stocking willdo much to determine fishing quali-ty, especially in the first 3-5 yearsafter a pond is built or renovated.Special details on stocking ofvarious kinds and combinations offish are given below. For other in-formation on each kind of fish seeChapter 5. Chapter 9 deals with fishpopulation control.

Largemouth bass, bluegills andother panfish usually won't need re-stocking, since they reproduce wellin most ponds. Adding to establish-ed populations of these fishesgenerally results in loss of the newly-stocked fish—or to competition andpoor growth of survivors. Small-mouth bass may have to be re-stocked, and channel catfish usuallywill.

Bass (largemouth or smallmouth)without other fish. In ponds lackingother fishes which compete forfood, bass often thrive on worms,insect larvae and crayfish. Westrongly recommend trying bassalone. If growth is unsatisfactory,forage fish can always be added.Smallmouth will work better thanlargemouth bass where the water is

on the cool side. They may also dobetter than largemouth bass in newor renovated ponds that haven't yetdeveloped much forage. Small-mouths often don't spawn success-fully, because they need gravel andthe young require more dissolvedoxygen than largemouth fry.

Bass with forage minnows. Stockminnows before the bass or wait tosee if they're really needed. Fatheadminnows are generally best, sincethey don't grow larger than 3 in-ches. Bluntnose minnows can alsobe used. Golden shiners usuallywork well, but sometimes grow toobig for bass to eat, if large bassaren't maintained in the pond asrecommended in this bulletin.Should golden shiners become toolarge, they compete with bass forfood. If the bass deplete the minnowpopulation in a few years, simplystock more, scattering well to reduceimmediate predation. A moderateamount of rooted plants in the pondgives minnows some shelter frombass and allows enough to surviveand reproduce for an ongoing popu-lation. Installing tile pipes or raised"spawning boards" may also aidminnow reproduction.

Channel catfish and minnows.Channel catfish grow slowly and sel-dom reproduce in Michigan ponds.They usually must be restocked forcontinued fishing. If shelters such asmilk cans, kegs, or closed pipe areprovided, they may occasionallybreed. Use the same kinds of min-nows as for bass forage.

Sometimes, for variety, channelcatfish are added to a pond havingbass and/or panfish. If adult bassare present, use catfish larger than 7inches (17 cm) to minimize preda-tion. Bass and panfish will prey onany catfish fry produced.

Largemouth bass and bluegills.BEWARE of this combination! It'sa favorite in the South, where it canwork, but it has been oversold in theNorth. Bass are supposed to controlbluegills by predation, but it doesn'twork that way in our climate. Thebluegills overpopulate the pond,and then both bass and bluegillshave stunted growth. If you wantbass and bluegills anyway, give thebass 1-2 years head start in growth

Table 7.1. Stocking guide for Michigan warmwater ponds to achieve maximumgrowth without supplemental feeding and aeration.

Kindof fish

Number to stockper surface acre

Length(inches)

Timeof year

Largemouthorsmallmouthbass alone

*100 fingerlingsOR

25-50 yearlingsOR

6-8 adults (both sexes)

2-4

6-10

12 +

July-August

April-October

October OR May

Basswithminnows

Channelcatfishwith minnows

Largemouth**bass withbluegills

Bluegil! orother panfishwith NO bass

Hybridsunfish

500 adult minnows,then, after minnows spawn,

stock bass as above

500 adult minnows,then, after minnows spawn

*100 fingerling catfish

Stock bass as above,then, after 1 or 2 years

500 fingerling bluegills

500 fingerlingsTHIS ALTERNATIVE IS NOTRECOMMENDED!

400-800 fingerlings

•Reduce by half if water alkalinity under 50 ppm.**Don't use smallmouth bass, as they eat very few bluegills.

2-3

2-3

2-4

1-2

1-2

1-3

April-May

April-May

July-August

July-August

July-August

July-October

and spawning. Then they may havemore effect on the bluegills.

Bluegills or other panfish withoutbass. This results in overpopulationand stunting even sooner than withthe bass-bluegill combination. If abluegill-only pond is desired, con-sider stocking only fingerlings. Thisdelays the onset of stunting by giv-ing the initial population some timeto grow before they have offspringwhich will then compete with themfor food.

Hybrid sunfish with or withoutbass. Artificial crosses between greensunfish females and other species ofsunfish (bluegills, redear, etc) mayhave the advantages of hybrid vigorand are predominantly male. Withreduced reproduction, food supplyand room to grow are maintained.But, beware — purebred sunfish arefrequently included among the hybridfingerlings stocked. These purebredsand the hybrids can mature, spawn,and start the pond on its way to over-population. Still, the number of fertilemistakes and female hybrids is usual-ly so low that the onset of crowdingand stunting is delayed for at leastseveral years—with excellent fishingfor panfish in the meantime. Theadvantages can be extended if the

32

hybrid sunfish are stocked with large-mouth bass because bass can prey onthe limited number of offspring.Hybrid fingerlings are of little or novalue when stocked with existingpanfish populations or in shallow,weedy ponds. If larger sized hybridsare stocked (6 inches or larger), theymay improve fishing by changing thesize structure of the sunfish popula-tion, particularly if catch and releasefishing is practiced.

Exotic fishes. Fishes not native toMichigan are sometimes desired bypond owners. Most of these, such asgrass carp, tench and Japanese weath-erfish, are inadvisable and illegal. Seediscussion in Chapter 5.

Angling HarvestBassThe harvest of bass should be

delayed until they have spawnedonce. This insures that they willbecome well established before otherfishes (especially panfish) disrupt thefood supply. It may mean waiting 2-3years if you stock fingerlings, 1-2years if you stock yearlings, or untilthe next mid-June if you stock adults.

If you stock 100 bass fingerlingsper acre, expect to have 25-30 adultsper acre after 2 full summers in the

BASS

0 2 4 (

5

4

3M•o

o

2

1

3/4

%

1/4

() 100

Inches} 8 10 12 14 16 18 20

\z-f

1

IH

j-17r

-

200 300 400 500 61

Millimeters

2000

1500

M

CB

o

1000

500

n)0

14

13

12

11

10

9

8

(00 7O I

3

o 6

5

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3

t

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u

BLUE

1

GILL;

2

t

3

—*>

0 50

4Inch

S

/

esi

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7 I

1\I

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100 150 200

Millimeters

9 10

ih300

250(0

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150

100

50

250

pond. The original bass stocked asfingerlings must support the first 5years or more of the pond's bassfishing. Therefore, harvest themlightly!

Light harvest means not removingmore than 20-25 pounds of bass peracre each year. Record length andweight of all fish taken from thepond. (Recording informationabout caught-and-released fish alsocan be useful.) After the year'squota has been taken, release allfurther bass caught.

There are many ways to manageharvest in an established Michigan basspond, especially if panfish have alsobeen stocked. Since panfish can easilyoverpopulate and stunt in Michiganponds, it is important to protect the sizesof bass that are effective panfishpredators. Bass 12 to 16 inches (30-46cm) are effective predators on 3-5inch (8-13cm) panfish like the bluegill.

The easiest way to insure that these pan-fish predators are available is to releaseall 12-16 inch bass. Once the pond con-tains a healthy population of this sizebass, you can harvest a few 10-12 inchbass (25-30cm) and those over 16 in-ches. Harvesting some of the 10-12 inchbass will help select for the fastestgrowing fish. Since slower growing fishwill be 10-12 inches for a longer timethan the faster growing fish, they willbe more likely caught than the fastergrowing fishes.

At any time that bass of a certainsize appear thin and poorly-fed,harvest bass of that size more heavi-ly. If a bass weighs less than 95% ofthe standard weight for its length, itis too thin. Use the graph on thispage to check whether your bass areof standard weight.

Channel Catfish

If you stock channel catfish as

33

Determining whether a bass or bluegill isof proper weight for its length. Weighthe fish to the nearest half ounce or 10grams, if less than Vi pound. If heavier,it may be weighed a bit less precisely.Measure length to the nearest eighthinch or millimeter. Plot weight on thevertical scale and length on the horizon-tal scale. Draw a horizontal line lightlywith pencil at the fish's weight and a ver-tical line at its length. If the point wherethe two lines intersect is on the heavycurved line, the fish is of standard (oraverage) weight for its length. If thepoint lies above the curve, it is heavierthan average. If it lies below the curve,the fish is underweight.

fingerlings, start harvesting them inthe second or third year after stock-ing when they have reached 9 to 10inches. If the catfish population isone of those rare ones in Michiganthat can sustain itself by naturalreproduction, remove only 10-15fish per acre each year. Usually,however, replenishment will be byannual restocking, and all fishcaught above whatever size pleasesthe owner can be harvested.

Bluegills and Other PanfishStart harvesting as soon as they

are a size you like. In new ponds orones where fish have been eradi-cated, some bluegills stocked asfingerlings should exceed 4 inchesthe next summer and 6 inches thesummer after that.

Follow two harvest rules: (1) Re-move as many under-6-inchers asyou can. (2) Greatly restrict harvestof over-6-inchers. This worksagainst overcrowding and helpssuperior brood stock survive. Justas with bass, the biggest, fastestgrowing bluegills bite most readilyand tend to be caught first.

The table on page 33 indicateslengths bluegills should reach ateach age. The graph on page 33shows how much bluegills shouldweigh at each length. If the bluegillsare growing too slowly or are thin, itis an indication of overcrowding.

The Bass-Bluegill CombinationFollow the procedures outlined in

the above sections on bass and onbluegills. Harvest at least 4 poundsof bluegills for each pound of bassharvested. This helps bass keep theupper hand longer. It is especiallyimportant to restrict harvest ofover-15-inch (43 cm) bass. At thatlength, they may be nearly 2 poundsand are probably just beginning toeat enough bluegills to have mucheffect in controlling their popula-tion. Have fun catching large bassand releasing them alive. Try to

build up a substantial population ofbass weighing 3, 4, and 5 pounds.

No matter how intensively youmanage the bass-bluegill pond, theday will probably come when thebluegills simply take over. Bassspawning success will decline, largebass and bluegills will disappear,and there will be hordes of smallbluegills—all about the same size.When this occurs, the owner is oftentempted to plant more and biggerfish—maybe even walleye or nor-thern pike. Resist such impulses!Walleye and northern pike are notsuited to life in small warmwaterponds (Chapter 5), and the onlycure for stunted panfish is a soundprogram of population control(Chapter 9).

Higher Stocking Levelsand Fish Feeding

Not RecommendedHigher stocking levels may lead to

the fish outstripping the natural foodsupply. Although many fish will eatpelleted fish feeds, it is usually best forpond health, appearance and yourpocketbook to manage so that the fishare sustained by the food that occursnaturally in the pond. Adding pellets,bread or other fish food may increasefish growth in an overcrowded pond-but it will probably also accelerategrowth of algae and other aquatic plantsto excessive amounts. The result maybe not only unsightly and interfere withfishing, but build-up of organic matterin the pond may cause oxygen deple-tion and die-off of fish.

Pond Fertilizationand Liming

Fertilizing and liming are generallynot recommended for Michigan sport-fishing ponds. Although often advisedin the soft water ponds in the DeepSouth to increase algae growth to

enhance the food chain, fertilizationhere usually causes excessive weed andalgae growth. The result is plant con-trol problems (Chapter 10), dissolvedoxygen shortage for fish due to rottingof accumulated organic matter, andeventual stress or even death of fish.

NEVER use fertilizer for creatingalgal growth to stifle rooted plants,as is done in the South. Such enrich-ment is so strong as to run grave riskof causing winterkill of fish.

Liming is sometimes used to raisealkalinity of the water to counteractacidity problems or to allow thepond to handle phosphorus fertilityin ways that boost production offish rather than of bluegreen algaenuisances (Chapter 4).

Fertilizing and liming of pondsshould be done only under directionof a water chemistry expert whounderstands proper balance betweenalkalinity and phosphorus contentand who can determine the rightdosage of phosphorus or lime.

Emergency Aerationof the Pond

In Chapters 8 and 10 are describ-ed ways to inject a stream of airbubbles at the deepest part of thepond to circulate the water and keepsufficient dissolved oxygen in thedeep zone. Aeration rarely is effec-tive in aquatic plant control but in anemergency can be used to rescue fishfrom a temporary crisis of diminish-ing dissolved oxygen content, suchas on especially hot summer nightsor during an especially hard winter.Aerators are particularly useful inpreventing winterkill of fish. Thecirculation achieved by the bubblestream maintains an open area ofice-free water through which thepond can take on oxygen. However,an aerator should not be needed in aproperly designed pond.

34

Managing Coldwater Ponds For Fishing

General ConsiderationsThe usual way of managing cold-

water fish ponds involves the fol-lowing steps:1. Stock small trout.2. Fish for them when they grow to

desirable size.3. Restock as the population dimin-

ishes.Restocking is usually done an-

nually. The interval can be greater iflittle fishing is done and the troutsurvive other hazards well. Annualstocking with fingerlings or year-lings is often desired because itcreates an interesting populationwith several year classes and a varie-ty of sizes present. Keep in mindthat trout rarely reproduce in ponds,so replenishment of the populationusually depends on stocking. SeeChapter 5 for information about thedifferent kinds of trout.

Trout don't thrive when there areother kinds of fish in the pond.Bass, pike and catfish will eat largenumbers of trout. Panfish, bull-heads, suckers, carp and even thesmallest kinds of minnows competefor the main types of food that troutneed. When competitor fishes are ina pond, trout growth is poor.

The common idea that trout needsmall fish as food is mistaken. Theyusually grow better on invertebratessuch as water fleas, insect larvae andcrayfish. KEEP MINNOWS OUT!

Where to obtain trout for stock-ing is discussed in Chapter 6.

Determining If a PondCan Support Trout

Trout need water that is cool andrather rich in dissolved oxygen. Therule of thumb is that water tempera-ture a foot below the surface should

seldom exceed 70 °F (21 °C) and thatdissolved oxygen should rarely fallbelow 5 parts per million. Dissolvedoxygen content of 7-8 ppm is mostfavorable. Some ponds where theupper water is a little over 80 °F(27 °C) for a few hours on some dayssupport trout because there isenough deep, cool, well-oxygenatedwater.

Much depends on pond depth andwater supply. As a rule, the deeper,the better. Although trout can oftendo well in only 6-9 feet (2-3 meters)of water, if there is very strongspring flow, they usually surviveand grow even better if that samepond is deepened. For best results,have it deeper than 15 feet (5meters). See Chapters 3 and 4 formore information on pond depthconsiderations.

A practical way to find out if apond can support trout is to simplyplant a few. If the pond was proper-ly designed and built there probablyisn't much to worry about. But, ifthere is some doubt, and you don'twant to risk the expense of fullystocking the pond, stock a tokennumber of 5-to-8 inch (13-20-cm)trout in springtime or fall. Then, dosome test fishing to check on growthand survival over one full year. Fora trial program, stock at least 10 fishper acre—in no case less than 20 perpond. If the trout survive both sum-mer and winter, this shows that thepond can support trout.

During the trial period, you maywant to keep records of temperatureand dissolved oxygen in the pond.This information may warn of deter-iorating conditions and provide anexplanation if fish do not survive.See Chapter 4 for temperature andoxygen measurement procedures.

Some ponds on the borderlinebetween coldwater and warmwaterconditions can support trout onlyfor a few years. As vegetationdevelops, dead organic matter ac-cumulates and consumes more oxy-gen. Temperatures may also in-crease. A decreasing water supply,as during drouth, can aggravate thissituation. Such a marginal pond canbe managed for trout until the un-favorable conditions develop. Thenbass or other warmwater fishes canbe stocked.

Table 8-1. A guide for stocking trout to achieve maximum growth without ad-ditional feeding and aeration.

StockingPreparing the Pond for Stocking

A new pond, properly built(Chapter 3) for coldwater fish,usually needs no further prepara-tion. In converting an old pond tosupport trout or readying a reno-vated trout pond, certain actionsmay be needed before stocking.

If other kinds of fish are in thepond, they must be completely re-moved (Chapter 9).

Screen inlets and outlets to pre-vent entry of the smallest fish.Maintaining screens can be quite aproblem, so it is far better to buildthe pond without connections toother waters which would harborfish. Caution children and friendsnot to bring in minnows, panfish,goldfish or any other fish!

You may at this time want tocombine a re-digging operation witha fish-removal drawdown. Draglinedigging with the pond bed exposedand somewhat dry may be muchcheaper than suction dredging ordrag-lining when the pond is full.

Even if you don't dig the ponddeeper during a drawdown, take ad-vantage of the situation to rake outaquatic plants and debris. Reducingorganic matter will usually improvea pond for trout. See Chapter 10 forplant control methods.

When to StockApril, May, and possibly June are

good trout stocking months becausewater temperatures have warmedconsiderably but are still moderate,and natural food organisms are in-creasing in abundance. Fish plantedat this time tend to survive betterand start growing sooner.

Typeoftrout

Size Number*in to stock

inches per acre

Timeto

stock Comments

Springfingerlings

Fallfingerlings

Springyearlings

"Adults"

2-3

5-6

6-7

over 7

200-300

50-150

50-150

25-50

April-May Cost least. May be hard to get. UseONLY FOR INITIAL STOCKINGof new pond or one which has hadall fish removed.

Sept-Oct For initial stocking or restocking.

April-June For initial stocking or restocking.More expensive than fingerlings.

spring or For initial stocking or restocking,fall Can be very expensive.

*The lower number is for ponds with alkalinity less than 50 ppm or which will be lightly fished.The higher number is for ponds with alkalinity over 150 ppm and/or which will be heavilyfished, hence be more rapidly "thinned out."

Trout can also be stocked inSeptember and October when thepond is becoming cooler. However,there is less chance for growthbecause the pond soon becomes toocold. Fall stocking is usually doneonly in new or redredged ponds—orwhere the fish have been eradicatedduring summer. Except in unusuallygood ponds, many fall-stockedtrout may die during harsh winterconditions. The losses may be out-weighed by much lower cost of fallfingerlings. Also, the longer timethat fall-stocked fish are on naturalfeed before the fishing season oftenresults in better appearance andflavor than newly-stocked fish.

Stocking trout in summer is inad-visable due to risk of thermal shockwhich can kill many or all of the fishplanted.

Number and Size of Trout to Stock

Table 8-1 is a guide to achievingtrout populations which grow wellon natural food supplies. ONLYONE of the types listed should bestocked in one year, although"adult" trout can be restocked asoften as they are fished out.

A common mistake is to stock toomany trout—which results in poorgrowth. The stocking rates recom-mended are conservative and arelower than often suggested in thepast. We believe it far better to riskstarting with too few trout than torisk ruining the food supply. If thetrout are fast-growing (see diagram,

page 37) and stay plump all year,then stocking can be done at a some-what higher rate the next time.

The number and size of trout tostock depend on conditions of theindividual pond: amount and size oftrout already present, how fast theyare to be harvested, the food supply,and whether there is natural repro-duction. Adjust stocking from yearto year according to past experienceand current conditions.

Infertile ponds may support onlyabout 20-25 pounds of trout peracre. Very fertile ponds may sustainupwards of 150 pounds per acre onthe natural food supply.

Pond capacity for trout produc-tion can be increased several fold byartificial feeding, and then thestocking rate can be raised.However, feeding can cause variousproblems (page 38).

As a rule, the larger the body sizeof the trout stocked, the greater thepercentage that survive to be caught—and, of course, the sooner therewill be fishing for big trout. When-ever you stock, consider using thelargest fish that the pocketbookallows. Price per stocked fish risessharply with increasing size, but thenumber needed to adequately stockthe pond decreases.

Experimenting in the pond overthe years should reveal the best sizesand numbers to stock. Keep carefulrecords of fish stocked and of fishcaught. Calculate the cost perpound caught—or per fish of desir-able size caught. You may find that

36

these costs decrease if you raise thesize of fish stocked somewhat be-yond the smallest, cheapest fishavailable.

For the first stocking of a new orrenovated trout pond, it may bemost economical to use spring fing-erlings. Plan not to fish them untilthe next spring when they should be7-8 inches (17-20 cm) long. How-ever, you may want to do some testfishing in the interim.

If you want an initial springtimestocking to provide more immediatefishing, use yearlings of 6-7 inches.In excellent ponds, they will grow aninch a month during spring, summerand fall.

For restocking in ponds withestablished trout populations, don'tuse fish smaller than fall fingerlings(5-6 inches or 12-15 cm). If largerfish are used, there will be fewerlosses to cannibalism by trout whichhave survived from previous stock-ing. Annual restocking may providefar more consistent fishing than re-stocking at greater intervals.

Transporting and Plantingthe Trout

Contact the state fishery officenearest to your pond (see Appendix)to see whether a permit for stockingis required. One will be needed if thepond has any connection with otherwaters or if certain other conditionsapply. Allow at least a month forthe inspection and permit issuance.

Be sure the trout are healthy whenstocked. Don't accept fish that areobviously diseased or that appearweak or abnormal in behavior. Fishstressed by improper handling andtransport will die soon after stock-ing. Even under the best conditions,10-20 percent of them may die in thefirst 2-4 weeks.

If you transport your own fish,keep the water at a rather constantlow temperature (50-60 °F or10-15 °C). Handling stress is greatlyreduced in cool weather.

Besides being cold, the watermust be well-oxygenated andunchlorinated. There are small aera-tion devices that operate on bat-teries or automobile current—oryou can attach a tube with clamp-valve and airstone to a spare tire.

Cool the container of water (plastictrash cans work well) with ice. It'susually most convenient and reliableto let the dealer deliver the fish.

As mentioned, stocking trout insummer is inadvisable. Since troutmust be transported in water that ismuch colder than the summer sur-face water of most ponds, they mayundergo lethal stress in passingthrough the warm upper layers ofthe pond toward the cool waterbelow. Resulting deaths may not beevident immediately, but may takeseveral hours or days to occur.

If more than a 10°F (5°C) differ-ence exists between transport waterand the pond, "temper" the trout tothe new water gradually. To do this,add small amounts of pond water tothe transport tank until its water isof pond temperature. If the fish aretransported in plastic bags, trashcans or other small containers, thesecan be set in the pond until the waterinside is the same temperature as thepond.

CAUTION: If the transport bagshave been filled with oxygen andtied off, do not open the bag (unlessfish are in distress) until temperinghas been accomplished and you areready to release the fish into thepond.

Flushing the trout through a largetube from the transport truck direct-ly into the cold pond depths isanother way to reduce thermalshock losses, but few dealers havesuch equipment. All in all, it is bestnot to stock in summer.

When to Start Fishingand How Much

to HarvestDo some catch-and-release

fishing periodically to see how thetrout are growing. Start keepingthem as soon as you start catchingsome of desirable size. Reasonablesize at which to start harvest is 7-10inches. If you delay harvest untilthey are much larger, the total returnmay be severely reduced. This isbecause loss of fish by non-fishingor "natural" causes is usually rapid,especially in the case of rainbow orbrook trout. Few live to be over 3years old, and at some point before

Trout — inches

0 4 8 12 16 20

5

4

•O3

3O0,

2

1%1/2V*

(

/t

//

/

/

iI

Gra

ms

) 100 200 300 400 500 600

Millimeters

Determining whether a trout is of properweight for its length. Weigh the fish tothe nearest half ounce or 10 grams, ifless than VA pound. If heavier, it may beweighed a bit less precisely. Measurelength to the nearest eighth inch ormillimeter. Plot length on the horizontalscale and lightly pencil a vertical linethere. Plot weight on the vertical scaleand draw a light horizontal line there. Ifthe point where the two lines intersectlies on the heavy curved line, the fish isof standard weight for its length. If thepoint lies above the curve, it is heavierthan average. If it lies below the curve,the fish is underweight.

37

then, total weight loss by naturaldeaths in the population begins toexceed total weight gain by bodygrowth. The more fish that aretaken by angling, the fewer that canbe lost to other causes. The greatestyield of fish and enjoyment canusually be obtained by doing mostof the harvest during the fishingseason in which the trout reach 7-10inches.

Experience over the years mayshow how much you should spreadout the angling harvest over theseason to get the results that youwant.

Under a "put-grow-and-catch"scheme of management, trout growwhile the harvest is spread out overthe season each year. You should beable to harvest an amount of troutabout equal in weight to the totalpoundage that exists in the pond atthe start of summer. This is becausebody growth of the remaining troutfills in for those removed.

Under "put-and-take" manage-ment for rapid catch-out of one orrepeated stockings of trout in oneseason, many times more pounds oftrout can be caught than is themomentary capacity of the pond tosupport—but you'll never catch asmany pounds of trout as were stock-ed. There isn't time for the trout tomake use of the food supply and togrow enough to compensate for theusual high post-stocking mortality.The cost per pound of fish caughtwill be much higher than in put-grow-and-catch stocking.

A put-and-take fishery may beappropriate for ponds wheretemperatures are suitable for troutonly in spring and fall.

Artificial FeedingSupplemental feeding shouldn't

be needed if the stocking rates inTable 8-1 are followed. At thesedensities, the trout should haveenough natural food to sustaindesirable growth.

Higher population densities canbe maintained if feed is added.Some people keep as much as 5,000pounds of trout per acre in hard-water ponds with artificial feeding—and harvest that amount annual-ly. This can only be done where a

strong supply of spring water keepstemperatures low and rapidly re-plenishes the oxygen consumed bydecaying feed and fish wastes.

However, there are disadvantagesto such intense management. Oncethe population is built up to the levelneeding feed, then the trout must befed almost daily during the growingseason. "Feed lot" conditions arecreated, and pond appearance maybecome unpleasant. Excess feed andthe unavoidable large amounts oftrout feces raise water fertility tolevels causing undesirable algaegrowths. The accumulation of unus-ed feed, trout wastes, living anddead plant matter, and decay micro-organisms in the pond consumeslarge amounts of dissolved oxygen.Having too little oxygen hamperstrout growth and, if severe enough,kills them. In softwater pondsespecially, excess enrichment cancause fluctuations of pH (acidity-alkalinity) which are intolerable fortrout. This situation gets so bad thatthe pond must be redredged if it is tobe further used for trout.

If there must be supplementalfeeding, give no more feed at onetime than the trout eat immediately.This minimizes residue of unusedfeed and reduces cost.

Convenient pelletized dry feed isavailable from livestock feed stores.Use only those especially made fortrout. Feeds for other animals (suchas chickens) don't have the ingredi-ents in the right proportions andwon't work. In most cases, floatingpellets are best. They stay up wheretrout can find them longer—andwhere you can see when they havehad enough.

Special Aquatic PlantControl in Trout Ponds

Amounts of algae and rootedplants should be kept moderatelylow in trout ponds. While waterplants produce oxygen in daylight,they consume more than they pro-duce at night. An overabundance ofplants, together with the decay ofdead plants, may reduce dissolvedoxygen levels below the trout'sneeds especially on hot summernights or in the darkness of winter

38

ice cover. See Chapter 10 for infor-mation on aquatic plant control.

CAUTION: Trout are generallymore sensitive than are warmwaterfishes to chemicals used to kill algae(algicides) or rooted plants (herbi-cides). Some of the chemicals willkill trout at the concentrations need-ed to kill the intended plants. Forexample, the commonly used algae-killing chemical, copper sulfate,should never be used in trout ponds.Before buying any chemical forkilling aquatic plants in a trout pond,determine its effect on trout. It maybe safer to remove plants bymechanical means (Chapter 10).

Artificially Circulatingthe Pond Water

If the pond is having dissolvedoxygen problems which threaten tomake it unsuitable for trout, re-dredging is the best solution. How-ever, it may help to circulate thewater by the air-lift method toachieve better aeration. Injecting astream of air bubbles at the bed inthe deepest part of the pond createsvertical circulation of the pondbecause the bubbles draw bottomwater toward the top as they rise. Atthe surface, the oxygen-poor waterspreads and takes on oxygen fromthe atmosphere. Surface water circu-lates to the bottom to replace it.

The bubble stream is produced bya compressor on the pond bank.The air passes through a hose alongthe pond bed to an air stone or otherdispenser. A variety of air-lift circu-lation systems are sold especially forlake and pond use (Appendix).

The circulation prevents pondwater from layering and stagnationwhich may occur in summer andwinter. Circulation may also keeppart of the pond surface unfrozen inwinter.

One risk with circulating a troutpond in summer is that the entirepond may be warmed beyond toler-ance for trout. There are specialdevices for aerating only the deep,cool part of the pond, without mix-ing into it the warm surface water.

Fish Population Control

Pond owners sometimes need toreduce or eliminate fish populationsbefore further management. Anolder pond may have become con-taminated with undesirable fish,such as carp, suckers or bullheads.A trout pond may contain unwantedwarmwater fishes which are com-peting for food and reducing troutgrowth and survival. It may be thata pond has suffered a winterkill forone kind of fish but not for others,disrupting the predator-prey bal-ance. Or perhaps panfish are over-abundant and stunted. When suchsituations occur, various methodsexist to alter fish population struc-ture or remove the population com-pletely.

Intensive AnglingIt is often thought that panfish

overabundance can be prevented orremedied by fishing hard and keep-ing many. That's fine in theory, butalmost nobody has time for enoughfishing to accomplish it. For reduc-ing panfish overpopulation, anglingis rarely effective. To best preventoverabundance follow the harvestsuggestions outlined in Chapter 7 ofthis bulletin.

Predator StockingSome people reason that stocking

northern pike, muskellunge or wall-eyes should result in panfish con-trol. But in numerous efforts toachieve this, there isn't one well-recorded example of success.

Bluegills and other sunfish havedeep bodies with a spiny fin alongthe back, and predators must haveespecially large throats to swallowthem. Although largemouth bass at-

tain the necessary throat size at asmaller size and earlier age thanother piscivorous fishes do, they donot keep bluegill populations incheck in Michigan.

All piscivorous fishes, includinglargemouth bass, much prefer to eatforage fishes that are more cigar-shaped and lack spiny fins. Thus, nopredator fishes eat many panfishuntil other, more convenient prey,such as minnows, are used up.

Having northern pike in bass-bluegill ponds often results in morepredation on bass than on bluegills.Even though they also have spines,bass are less deep-bodied and areeasier for pike to swallow.

Control of carp and suckers inponds is rarely achieved by intro-ducing large predators. By the timesuckers or carp become a problem,they are usually too large andnumerous for piscivorous fish toachieve control.

Spawning BedDestruction

Some people have tried to controlsunfish populations by destroyingtheir eggs, either through raking ortrampling the nests. However, youhave to get almost every nest to beeffective. Sunfish spawn over such along period, hatch in so few days,and hatch so many fry in each nestthat such control is a long, hard taskwith high risk of failure. Even if itwere effective, the result wouldn'tbe worth the effort.

Cover ReductionPanfish can rapidly overpopulate

a pond when cover in which theycan hide from predators is abun-

dant. This commonly occurs whereoverly dense stands of aquaticplants occupy too much of thepond. Scattered stands with moder-ate plant density (about 80 stems persquare yard or meter) promote abetter balance between predator andprey fishes. Methods for controllingaquatic plants are discussed inChapter 10.

Water Level DrawdownIn some cases, fish populations

can be controlled by manipulatingpond water level. The water levelcan most easily be drawn down andraised again if the pond is formed bya dam with a proper water controlstructure to regulate the outlet. Todraw down undrainable ponds, low-head pumps or a siphon can beused. The length of time needed forthe pond to refill should be con-sidered.

Whenever water is dischargedfrom a pond, take care to insurethat downstream waters or proper-ties are not damaged by flooding,erosion or sedimentation. It is theowner's responsibility to release thewater in a judicious, reasonable andprudent manner.

Fish present in the pond may notbe released into public waterswithout a permit from the MDNRFisheries Division. Unauthorized in-troductions of fish can disruptnatural fish populations to the detri-ment of public interest. Contact theMDNR District Fisheries Biologistwhenever a drawdown or otherwater release from a pond is desired.

Total Drawdown is used to elimi-nate all fish from the pond. Aspecial effort must be made not tooverlook fish that may find refugein residual puddles. Spot applica-tions of fish toxicant chemicals mayhelp in attaining complete kill.Desired fish, such as large bass, canusually be salvaged and kept alivefor restocking, if other water forholding them is available.

Partial drawdown is usually usedto concentrate fish so that predatorslike bass can become more efficient.This tactic depends on havingenough predators to consume alarge portion of the unwanted fish.When the pond refills, the survivors

may be able to make better use ofthe existing food supply, if over-abundant aquatic plants have beenkilled by drying during the draw-down, as is often the case. Preda-tory reduction of small fishes will bemost effective if the partial draw-down is done for a month or morein July or August. Carefully con-sider whether there will be increaseddanger of oxygen depletion andmass fish die-off during partialdrawdown.

SeiningFish can be removed by drawing a

seine through the water. This isoften the most effective method forreducing numbers of unwanted fishin small ponds. Seining is usuallydone by two people, each holding awooden upright which supports anend of the net. Floats keep the seinetop at the water surface, andweights hold the bottom edge on thepond bed. For best results, the seinemust be deeper than the deepest partof the pond so that it will "belly"without being pulled away from thepond bed as it is drawn along. Theseine must stay tight along the pondbed, or fish will escape underneath.

Small "minnow seines" of 15-40feet (5-12 meters), available atsporting goods shops, can be usedalong shorelines to remove panfishfry and finger lings. Small seinesmay be especially useful on panfish

Seining a pond.

during spawning periods. Longer,deeper seines allow greatercoverage. Seines of 50-200 feet(15-60 meters) can be built to fityour pond.

Use nylon netting. It is most rip-resistant and lasts long with littlemaintenance. For removing smallpanfish, use netting with mesh offrom !4 to Vi inch (Vi to 1 cm).Smaller mesh isn't needed and isharder to draw through the water.Larger mesh will let those fishescape that are often the most im-portant to remove.

Ready-made or custom-builtseines can be ordered from varioussuppliers (Appendix). You can alsomake them yourself with netting,cord, floats and weights from thesame sources.

For seining, the pond bed shouldbe smooth and free of snags such asrocks, logs and brush. Dense weedbeds also impede *seining. Water-level drawdown (described previous-ly in this chapter) can aid in seiningby drawing the water away fromweed beds and other shore-zoneobstructions, as well as decreasingthe area and depth to be seined.

If the seine spans the pond'swidth, two people can draw it thelength of the pond in one sweep.This is the most efficient method. Ifthe pond is too wide for that, pullthe seine out from shore in an arc—using a boat if needed—and back toshore. Draw the arc tighter and into

40

SEINE BAG SEINE

Bottom line with lead weights

Top panel preventsfish from jumping

,\ Top line with floats

Bottom line drawn ahead of top line

A seine and a bag seine.

shallow water or onto shore. Suchshoreline seining, even whenrepeated all around the pond, usual-ly achieves a far less complete catchthan with a seine that spans thepond and is of proper depth.

Draw the seine so that the bottomedge stays ahead of the upper edge.Many fish escape if a seine rolls upat the bottom as it is pulled along.

To salvage bass, large panfish, orminnows and return them to thepond uninjured, pocket the seine inshallow water at the end of the haul,rather than dragging it ashore. Roll-ing or sandwiching the net cangreatly harm fish by bruising themand by removing their slimy cover-ing and scales, thus increasingsusceptibility to infection and dis-ease. Minnows are very prone tosuch injury—especially in hotweather.

To "thin out" populations ofbluegills or other sunfishes, seinefrequently in the warm season whenthere is almost continual hatching ofsunfish. Remove panfish that areless than 6 inches (15 cm) long, andreturn the over-6-inchers plus anybass or channel catfish (not bull-heads!). This amounts to selectivebreeding for the trait of fast growth—while making room for thatgrowth to occur.

Keep seining until about 80 per-

cent of the pond's estimated sum-mer poundage of panfish has beenremoved. Estimating the totalweight of panfish in a pond is dif-ficult, and it is best to consult a pro-fessional biologist in your local areaon this.

Seining is hard work but can befun. It can provide useful informa-tion about the fish population butcan also give misleading impres-sions. Bass and carp, especially theolder ones, are adept at avoidingnets. When you seine up only smallbass or carp, don't conclude that bigones aren't there.

Various kinds of fish traps.

Live-TrappingFish traps may be useful for

reducing populations in ponds thathave obstacles to seining. An effec-tive trap can be made of !/2-inch(1-cm) hardware cloth on woodenframing.

Use traps with or without"wings," which are like fences ex-tending outward from the mouth ofthe trap. They guide fish toward theopening. Wings can be any lengththat is convenient.

Place traps in water which is justdeep enough to cover them, parallel

41

or at right angles to the shore, offpeninsulas, or in shallow bays wheresmall fish gather. Support traps andwings with poles or iron reinforcingrods driven into the bed. Up to 10traps per acre (25 per hectare) maybe needed.

For panfish thinning, remove thesame amounts and sizes of fish asdescribed in the section on seining.Take fish out of traps daily. Other-wise, turtles may be attracted andeat the desirable fish.

Gauze bags of bait, such as bread,oatmeal, soybean cake, or cottagecheese, can be hung in traps to in-crease catch, but aren't necessary.

Fish ToxicantsPerhaps the best method of

"reclaiming" ponds from panfishoverpopulation or presence of unde-sirable fishes is to kill all fish with achemical especially formulated to bea fish toxicant* or "piscicide." Thenstart anew by stocking a suitablepopulation after the water has detox-ified.

"Partial treatments" to removeonly certain species or sizes of fish,or to merely reduce rather thaneradicate the population, can bedone by applying special dosages orby treating only small parts of alarge pond at one time. Partial treat-ments are usually very difficult.

Only two chemicals, rotenone andantimycin, are now legally registeredfor use as fish toxicants. Federal lawrequires that only legally registeredfish toxicants be used — and thatthey be applied strictly in accordancewith instructions on the productlabel. Only certified aquatic pesticideapplicators can apply piscicides inMichigan. Lists of certified aquaticpesticide applicators can be obtainedfrom the Michigan Department ofAgriculture, Pesticide and Plant Man-agement Division, P.O. Box 30017,Lansing, MI 48909.

The amount of toxicant neededfor total removal of fish may de-pend on several factors, includingthe kind(s) of fish to be killed, pond

*The chemical is absorbed into the fish's gills andkills by interfering with respiration. This does notmean that the pond is made poisonous for humans,for any vertebrate animals other than fish, or formore invertebrates when used at the dosagesprescribed for killing fish.

CYLINDRICAL FISH TRAP

CYLINDER

PORTION

FUNNEL PORTION

BOX FISH TRAP

FRONT VIEW SIDE VIEW WING TOP VIEW

2 " x 2 " LUMBER

ENDPORTION

STEEL POST

DOUBLE FUNNEL FISH TRAP

FUNNELS

CYLINDER

PORTION

4'

COMPLETED TRAP

Fish trap construction.

volume water temperature, waterhardness, light conditions, abun-dance of aquatic plants, and amountof other organic matter present.Correct application of fish toxicantsis difficult.

A special permit is requiredbefore applying a fish toxicant toany pond. Contact the DNR DistrictFisheries biologist to learn how toobtain the permit. If the pond has anoutlet, special care must be taken toinsure that fish aren't killed down-stream. The person who applies thetoxicant is legally and financiallyresponsible for fish killed beyond

42

the limits of the pond. For more in-formation, contact the MichiganDNR District Fisheries Biologist.

Aquatic Plants And Their Control

Aquatic plants play essential rolesin the recreational fish pond. Thehealthy pond will have moderateamounts of a variety of plants.Plants become overabundant andinterfere with pond use when—andonly when—nutrients are too abun-dant. We then view the plants asweeds to be controlled.

Control of the overenrichment-overvegetation problem is one of themost common pond managementneeds. The way to prevent a pondfrom becoming algae-ridden orweed-choked is to keep excessiveamounts of nutrients from gettinginto the water. The only permanentway to restore a pond from plantoverabundance is to halt the over-supply of nutrients. Trying to con-trol plants by cutting or withchemicals is only temporary. Over-zealous use of chemicals (herbicidesand algicides) to poison plants maydamage the health of the pond com-munity and should be avoided.

Plants not only release oxygenand serve as the producer base ofthe pond's food web, they also fur-nish cover in which fish like to rest,and they support organisms thatfish eat. Having a few well-spacedplant beds can provide prime fishingspots. Certain vegetation also at-tracts waterfowl and other en-joyable wildlife.

The disadvantages of too manypond plants can include:

— Unfavorable build-up of or-ganic matter on the bed.

— Daytime overproduction ofoxygen to an extent toxic forfish.

— Nighttime overconsumptionof oxygen to a point where fishdo not get enough.

— Daily changes in acidity/alka-

linity balance of the waterwhich are unfavorable to fishand other organisms.

— Too much cover for small fishto hide from predator fish, re-sulting in overpopulation ofthe pond with small fish.

— Interference with fishing, boat-ing and other activities— in-cluding seining to control fishpopulations.

If less than a fourth of the pondsurface is covered by plants, there isprobably no problem unless this in-terferes seriously with use of thepond. Even much more vegetationthan that may pose no threat to thewelfare of pond fish.

Kinds of PlantsThe many kinds of pond plants

are in two general groups: algae androoted leafy plants. The latter haveflowers.

Algae (the plural of alga) aresingle-cell plants or colonies of cellslacking true roots, leaves or flowers.There are three types of algae:

—Planktonic algae drift free inthe water, are usually microscopic insize, and, when abundant, make thewater look murky. Algal murk mayrange in color from green to yellowand brown or even gray.

—Filamentous algae are thread-like or netlike. They may be smalland free-drifting but often occur as"mossy" growth on rocks, plantsand other firm objects. Some kindsform a water surface scum or aslimy, felt-like mat on the pond bed.Most scums and mats are actuallycommunities containing many bac-teria and fungi, as well as algae.

—Chara algae, also called musk-grass or stonewort, grow attached to

the pond bed without true roots,have clustered needle-like projec-tions, and are often mistaken forleafy plants. The two common kindsare chara and nitella. When mashedbetween the fingers, they both feelgritty and give off a musk-like odor.There is often a white or brownishcrust of lime or "scale" on theplants. Chara occurs under naturalconditions as small clumps about 6to 8 inches high. When over-fertilized, it forms continuous

stands several feet high. Overabun-dance of chara is a common pondproblem.

Rooted, leafy plants also occur inthree general forms:

—Submergent plants (or sub-mersed plants) grow rooted to thebottom with most parts beneathwater. Some have a few leavesfloating at the surface. Many thrustblossoms above the water. Commonsubmergents are pondweed (Potam-ogeton in many varieties), coontail,

milfoil, waterweed (Elodea), waterbuttercup and bladderwort.

—Floating plants have all or mostof their leaves and flowers at thewater surface and roots danglingfree in the water or rooted in thepond bed.

—Emergent plants (or emersedplants) have stems and leaves thrustabove the water. These grow atpond margins and may extend intowater several feet deep.

Algae Submergent Plants

Planktonic algae (many species) —free-floating, usually minute, may besingle-celled or in colonies. When abun-dant, they may color the water murkygreenish to brownish—or in extremecases give the water a pea-soup ap-pearance.

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

Chara algae (muskgrass or stonewort)—Upright plants attached to pond bed.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 shallowwaters having high alkalinity. They arerough to the touch. When crushed be-tween fingers, it feels gritty and gives offan ill-smelling, skunk-like odor.

Coontail (Ceratophyllum demersum)—Whorls of leaves at joints of stems.Leaflets forked once or more, havetoothed edges. Leaves densely crowdednear tip of stem. Grows in hard water.

Fanwort (Cabomba caroliniana)—Leaves fan-shaped. Leaflets forked andwider at tip than at base. Sometimessmall floating leaves. Plants havegelatinous slime. Flowers white tolavender.

Water milfoil (Myriophyllum species)—Leaves whorled on stem and dividedfeather-like, not forked as in coontail.

iVr

Naiad (Najas species)—Leaves occuras opposite pairs or whorled, very nar-row, toothed on edges. Commonlygrows in water 1 to 4 feet deep butsometimes much deeper.

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

44

Elodea (Elodea canadensis)—Flat,thin leaves occur in opposite pairs orwhorled. This plant commonly used inhome aquaria.

Submergent Plants (continued)

Floating pondweed (Potamogetonnatans)—Has two types of leaves.Underwater leaves are narrow, grass-like, and appear as stalks. Floatingleaves are oval to heart-shaped, eachwith notched base. Flowers and seeds ona spike.

Leafy pondweed (Potamogeton folio-sus)—Leaves ribbon-like, about1/16-inch wide, lack sheath at base.

Curly pondweed (Potamogeton cris-pus)—Leaves alternate, have finelytoothed, crinkled, or puckered edges.No floating leaves. Flowers and seeds inspike at tip extending above water forfertilization. Grows in fertile hard water.Introduced from Europe.

Sago pondweed (Potamogeton pectin-atus)—Leaves fine, thread-like, andspread as a fan, have sheathed base. Nofloating leaves. Stems usually multi-branched. Tubers grow from horizontalroots.

Water-stargrass (Heteranthera dubia)—Looks like some narrow-leaved pond-weeds (Potomogeton), but leaves lack amidvein. Flower yellow, star-like.

Wild celery (Vallisneria americana)—Light green, ribbon-like leaves may beas long as 6 feet (but usually much less),with tips floating on surface.

Floating Plants

White waterlily (Nymphaea odorata)—Round floating leaves grow to 10 in-ches diameter, split to stem at center,often purple on underside. Flowersshowy, usually white but sometimespink. Flowers open from morning untilshortly after midday.

Duckweed (Lemna species)—Tiny,free-floating, bodies are flat and roundor lobed, oatmeal-sized or smaller, oftenmistaken for algae. Barely-visible rootsdangle thread-like. Sometimes severalplants attached. Masses of this plant ac-cumulate as a scum blanketing quietshallows. As scum dies, it turnsyellowish or whitish.

Lotus (Nelumbo luted)—Round float-ing leaves grow to 24 inches with adepression in center where stem attach-ed. Leaf veins radiate from center.Flowers yellow, large, showy.

45

Emergent Plants

Arrowhead {Sagittaria species)—Leaves usually arrow-shaped, but somemay be tongue-like or ribbon-like,especially at base of plant or under-water. Flowers white, 3-petaled, whorl-ed and grow near tip of a stalk. Fruitsare tightly-packed balls of seeds.

iLm

Bi

iRush {Juncus effusus)—Clumps of

stems rise from stout horizontalrootstocks, grow 3 to 4 feet tall resem-bling grasses and sedges. Greenish-brown flowers near tip of stem.

Bulrush (Scirpus americanus)—Hor-izontal rootstocks give rise to stems withtriangular cross section (but round insome bulrushes). Height usually 2 to 3feet. Flowers and seeds on spikes alongstem near tip. The plants may formdense stands after several years.

Pickerelweed (Pontederia cordata)—Leaves heart-shaped, similar to those ofarrowhead but rounded at tip and cor-ners. Curving veins follow leaf margin.Flowers blue and 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.

Burreed {Sparganium eurycarpum)—Leaves long, erect, ribbon-like, usually 1to 3 feet high. Stems bear male flowersat tip, female flowers below. Fruitingheads are one-inch round balls contain-ing many seeds.

46

Emergent Plants(Continued)

Water primrose (Jussiaea repens)—Leaves oval to lance-shaped, grow to 3inches long. Plants sprawl or partly floatin shallow water. Rooted at nodes onstem. Flowers yellow.

Water smartweed (Polygonum am-phibium)—Leaves eliptical, up to 4 in-ches long. Stems upright or sprawling inwater or on mud banks. Deep pink flow-ers in spike at tip of plant.

Watercress (Nasturtium officinale)—Grows in tangled or billowy masses.Leaves compound with 3 or more seg-ments, of which the one at tip is largest.Roots form at stem joints. Flowers verysmall and white in lacy clusters. Espec-ially common in springs.

Cattail (Typha latifolia)—Leavesreach to 6 feet tall, ribbon-like, taper toa point. Flowers on stalks taller thanleaves. Male flowers at tips, femaleflowers below. The plants grow atwater's edge but commonly also todepths of 3 to 4 feet.

Chara algae or "muskgrass" grows in small, isolated clumps only 6 to 8 inches high when nutrients are in low to moderate supply(left), but rapidly form dense, continuous stands up to 5 or 6 feet high in the water when pond overenrichment occurs (right).

Leafy submergent plants also change from growths of tolerable density (left), beneficial to fishes and other pond life, to dense, con-tinuous stands (right) that crowd out other life and interfere with recreation when ponds receive too much nutrient.

47

How NuisanceGrowths Occur

Understanding how pond plantoverabundance happens helps indetermining how to prevent it orhow to do something about it once ithas happened.

Shallow ponds and shallow partsof deep ponds tend to be ideal placesfor plant growth. Most of the waterand pond bed are well lighted. Thewater here becomes warm. Pondvegetation increases until it has usedup the nutrient substance which isscarcest relative to the needs of theplants. The vegetation will increaseand decrease during the growingseason according to availability ofthe key nutrient, called the "limitingfactor." Therefore, controlling theavailability of that key nutrient con-trols the amount of pond vegetation.

The key nutrient is usually phos-phorus. Even if phosphorus is notthe limiting factor in a particularpond at the moment, it usually canbe reduced enough to make it thelimiting factor. Nitrogen tends tobecome the limiting factor in pondswhich receive more phosphorusthan the plants need. But in thesecases, it may be much easier tolower the phosphorus supply belowthe level where it becomes limitingthan to sufficiently reduce the nitro-gen supply. This is because nitrogenis readily available as a gas in theair. Certain algae and bacteria con-vert it to a form that pond plantscan use. In contrast, phosphorusdoesn't occur as a gas in air. It istightly held in land vegetation andtopsoil. Nuisance-causing amountsof phosphorus aren't usually avail-able to pond plants unless humanactivity disturbs surrounding land,and topsoil erodes into the pond—or unless fertilizers and the wastesof humans or animals are allowed towash into the pond. These unnat-ural sources of phosphorus canoften be much reduced or complete-ly eliminated.

A deep pond with much of its bedbelow the well-lit zone absorbs morenutrient without undergoing nuis-ance plant growth and has greaterself-restorative powers, once thenutrient oversupply is shut off.Phosphorus becomes tied up in the

bodies of plants and other organismswhich die and drift to the pond bed,forming organic deposits rich in thisnutrient. Where the pond bed is sodeep as to prevent the mud fromreceiving enough light for plantgrowth, most of the phosphorusstays locked away in the mud, aslong as the water just at the mud sur-face contains dissolved oxygen.Without oxygen, chemical reactionsoccur which allow phosphorus to dif-fuse back up into the pond. If themud deposit builds up high enoughthat its surface is raised to a levelreceiving enough light for rootedplants to grow in it, these plants willpump phosphorus from the mud intothe pond water. This acceleratesoverenrichment and plant produc-tion throughout the pond.

Vegetation Controlby Restricting

Phosphorus SupplyBecause high phosphorus levels

usually contribute to nuisance plantgrowth, reducing the pond's phos-phorus supply is usually the mostessential step in controlling plants.

There are many sources of phos-phorus, however, the most impor-tant ones and some actions toremedy them are:

Materials from Surrounding LandSoil erosion from land distur-

bance, such as cropland tillage orroad and housing construction.Keep landscape disturbance to aminimum in the pond's drainagebasin. Tillage and constructionshould be done in ways that cause aslittle erosion as possible.

Inflow of storm water, whetherdirectly from surrounding slopes orthrough ditches and pipes. Theproblem is made worse by pave-ment, roofs and other hard surfacesthat prevent water from soaking in-to the ground. Do not connectponds with storm drains. Divertlocal runoff away from ponds withberms and ditches. Keep a bufferstrip of vegetation around as muchof the pond edge as possible, so asto intercept local runoff. Soil, leavesand other nutrient material washedor blown from surrounding land willlargely be caught in a "bristle filter"of high grass and marsh plants.

Table 10-1. Common nitrogen sources for lawn fertilization.

Type offertilizer

Watersoluble,inorganic

Watersoluble,organic

Waterinsoluble,naturalorganic

Waterinsoluble,syntheticorganic

Commonname

Ammoniumnitrate

Ammoniumsulfate

Urea

Processedsewage

Urea form-aldehydes

IBDU

Nitrogencontent &release rate

33%(rapid)

20%(rapid)

45%(rapid)

5 to 6%5 to 10%(moderatelyslow)

38%(slow)

31%(slow)

Lbs. neededto equal 1Ib. nitrogen

3

2.2

20-1720-10

2.6

3.2

Remarks

Most effective for rapid green-up andgrowth when soil temperature is below55-60 °F (before May 15). Stronglyacidifying on soil. May cause burningof growing turf if not watered-in im-mediately.Slightly less available than soluble,inorganic forms when soil temp, isbelow 55-60 °F, but othercharacteristics are similar. May causeburning of growing turf, if notwatered-in immediately.Also contains some phosphorus. Re-lease of available nitrogen forms mostrapid when soil temperature is above55-60°F. Minimum danger of burningturf.Slow nitrogen release until soil temp-erature is above 55-60°F. Normallymixed with soluble, readily availableforms. Minimum danger of burningturf when used alone.

Faster nitrogen release with higher soilmoisture. Larger IBDU particles giveslow nitrogen release. Not greatly af-fected by temperature. Minimumdanger of burning turf when used.

48

Inflow from streams and agricul-tural drains. Even the purest-looking stream water will usuallybring in excessive phosphorus andflush out little. Water from tiledfields and other wetland drainagetends to be especially rich inphosphorus. Do not use streams ordrains as source-water for ponds,and locate ponds where they won'tbe flooded by high water fromstreams.

Tree leaves can be a massivesource of phosphorus. Don't havetrees so close as to shed leaves intothe pond.

Crop and lawn fertilizers. Applythese sparingly and at times and inways that reduce their loss in run-off. Use little or no fertilizer onland draining toward the pond. Usemainly nitrogen (Table 10-1) notphosphorus unless soil tests show it isneeded, which is seldom the case.Rather than bluegrass, use fescuewhich needs less fertilizer andwater. To promote healthy turf thatneeds less fertilizer and retains itbetter, keep it raked free of leaves,set mowing height at 2 to 2Vi inches,and water sparingly, especially onsandy soil for less nutrient leaching.

Livestock wastes. Runoff fromfeedlots, barnyards and pasturesshould obviously be avoided.

Human wastes. Septic systemseventually leak phosphorus throughthe ground for distances as great as300 or 400 feet in many Michigansituations—farther if the soil isshallow or the effluent seeps out ofthe ground and runs over land. Soilsaround septic systems become satur-ated with phosphorus and no longerremove it from the effluent. Thebetter your soil passes the "percola-tion test," the more rapidly it maybecome saturated with phosphorusand let it through to your pond.

There are various ways to reduceor prevent escape of phosphorusfrom septic systems to pond. Locatethe tank and/or drain field at least300 feet away from the pond and insuitable soils at proper depth and ona slope not too steep. Add a dosagechamber to the septic system—andmaintain it. Use no phosphatedetergents or other phosphatecleansers. This reduces phosphoruscontent of septic effluent. No mat-

ter how septic systems are main-tained, those closer than 300 or 400feet to a pond probably won't begood for the pond. Some bettermethod than septic systems shouldbe used.

Consider alternative methods ofwaste disposal, such as compostingtoilets, other kinds of self-containedon-site sewage systems, municipalsewer hookup, or simply the tradi-tional outhouse privy. Compost kit-chen wastes rather than flushingthem down a disposal grinder. Pourdishwater on your garden, lawn orangleworm-rearing bed rather thanwasting it down the drain.

Pond Fertilization

Fertilizing a Michigan pond cando great damage if you wish tomaintain it as a pleasant recrea-tional fishery. Recommendationsfor fertilizing commercial or recrea-tional ponds in southern states aresometimes applied in the North withunfortunate results. Fertilizer isused to increase southern fish pro-duction, also to create algal murk sodense that rooted plants are shadedout. But in regions of significant icecover, this almost assures winter killof fish. It can also cause summerkill, bring on other disadvantages ofplant over-abundance and build upnutrients of shallow muds that leadto a continuing problem. If fertiliza-tion is done to stimulate such algalturbidity to control weeds, waterquality and appearance may becomeobjectionable.

Fish Food Application

Artificial feeding of fish shouldbe avoided or greatly restricted if ex-cessive vegetation is to be prevented.The wisest approach will often be tomaintain no more fish than cangrow well on the food naturally pro-vided by the pond. However, if youwant to have unnatural abundancesof fish through supplemental feed-ing, feed as sparingly as possi-ble—and be aware that you may bemaking a tradeoff in pond quality.

Vegetation Control byTemporary MethodsPond treatments that don't con-

trol nutrient inflow can't control

aquatic vegetation more than temp-orarily. Increasing pond depth bydredging or by raising the waterlevel may be of longer-lasting effectthan other temporary treatmentsbut has high initial cost and otherdrawbacks. Measures such as pois-oning the plants with toxic chemi-cals, introducing other chemicals toinactivate nutrients, or removing theplants physically must be repeatedfor as many years as relief is desired.The cumulative cost can be huge,and more than one treatment peryear may be needed.

The "temporary symptomaticrelief" afforded by such measuresmay be desirable to ease the un-pleasantness of nuisance vegetationduring the time it takes to find andcontrol nutrient sources for perma-nent solution. However, the cosme-tic effects of short-term treatmentsshouldn't be allowed to so obscurethe problem that one loses sight ofthe underlying causes to be cured.

Eliminating one type of vegeta-tion may just make room for re-placement by some other equallybothersome kind. This takes placeannoyingly soon in some cases. Forexample, less than a month aftercutting or poisoning rooted plants,the area may become clogged withstringy algae. Nature abhors avacuum. As long as light, warmthand nutrients exist in a pond, it willstrive to fill the water with vegeta-tion.

The vegetation of most ponds willcontinually change, even if unal-tered by humans. One type of planttends to be replaced by others. Wecall this "natural succession." Bythis process, a pond vegetationproblem may alleviate itself in a fewyears. For example, nuisancegrowths of chara algae have beenreplaced by other plants that are lessbothersome in some cases—with nocontrol needed.

If short-term controls, such asoutlined below, are to be used, itmay be a good idea to switchmethods every year or two. Thekinds of plants that can best with-stand one type of treatment may in-crease, but are likely to be con-trolled if the method is changed.

49

Pulling plants out by hand will often be the simplest way to control vegetation inshallow water.

Physical Disruption and Removal

This method can be one of thesimplest and most practical of tem-porary plant control methods. Thecost can be low for some methods—or quite high for others. Themethods are akin to cultivating,weeding and hoeing in a garden, orto mowing a meadow. Most aquaticplants are more fragile than gardenweeds, however, and to this extentphysical control may be easier forwater plants than for land plants.

Frequent disturbance, such asraking of pond shallows, or tramp-ling of beach areas by swimmers,can keep areas weed-free. Cattailsare easily killed by trampling or cut-ting the new shoots in springtime.This may also work for most otheremergent plants.

You can simply wade in and up-root many kinds of plants by hand.This works for cattails, rushes andother emergents when they aregrowing as isolated plants, as well asfor submergent plants that can bereached in this manner. The first"weeding" of a well-establishedplant bed may be hard work, butfollow-ups repeated often enoughmay keep the difficult situationfrom developing again.

A scythe or hoe can be useful forcutting aquatic weeds in shallowareas. Caution: Wielding a bladeunder water can be much moredangerous than in the air! Always

wear protective boots! The cutplants will float and should beremoved from the pond as soon aspossible. Deposit them where thenutrients will not run back into thepond as the plants decay.

A rake can be used for uprooting,tearing loose and dragging outplants. The head of a garden rake,fitted with an extra-long handle andmanipulated from a boat or wadingposition is suitable for reaching intodeep water. A floating rake is lesstiring for work near the surface. Ifyou don't have an all-wooden, peg-tined rake, make a floating rake.Fashion a rake-head block by driv-ing long spike nails at 2-to-3-inch in-tervals into a piece of light woodwhich is about 2x2 inches in cross-section and 18 to 24 inches long—orlonger if you can handle it. Cut thespike heads off. Drill a hole in theblock so a handle can be affixed. Abamboo pole makes a good handle.It can be very long yet light.

For weed growths too extensive toscythe or rake, a log loosely wrap-ped and stapled with barbed wirecan be dragged through the pondbehind a tractor driven along theshore. A heavy chain connecting logto tractor helps to sink the log to thepond bed. Add more weight asneeded. The log can be guided witha rope manipulated by a person onan opposite shore. The barbwire logseems to be an improvement overthe dragging often tried with bed-

50

springs—from which it is more dif-ficult to disentangle weeds.

Mechanized harvesters are avail-able in a wide range of sizes. Smallmodels, costing less than $1,000,can be mounted on a rowboat.These have cutter bars like those onhay mowers. With such boat-mounted units, weeds can be cut toa depth of about 4 feet. After theweeds are cut, they are raked to aremoval point on shore. Other weedcutters are manufactured as mowerbars on small paddlewheel barges.These can operate in very shallowwater, as well as to depths of 5 feetor so. They range in price fromabout $2,000-$20,000. Large "har-vester" units which draw plants on-to the barge as they are cut are avail-able for upwards of $50,000.

Some plants are difficult to con-trol with mechanized harvesters.Chara sinks when cut and is there-fore hard to pick up. Milfoil, coon-tail and elodea are also hard to col-lect once they are cut. These kindsof plants spread by fragmentation.Each piece cut and not picked upmay become a new plant. In smallponds, removal of these plants byhand or rake is probably preferableto mechanical harvest. Most plantsare, however, easier to harvestmechanically than chara, milfoil,coontail and elodea.

Plant removal is best done attimes of spring or summer when itwill result in the maximum amountof plant material removed and stillallow full recreational use of thepond. Such timing depends on yourknowledge of the growth of theplants in the pond and your plansfor pond use. Often, the best ap-proach in a small pond will be peri-odic trimming as in caring for alawn or garden. In new ponds, con-trol plants by frequent hand or rakeremoval before they become abun-dant.

Harvested plants make goodgarden mulch, soil conditioner andcomposting material. The thin cellwalls of aquatic plants break downrapidly and the resulting fine-tex-tured matter may even be suitablefor spreading on lawns.

Deepening the Pond to ControlVegetation*

Deepening to renovate an existingplant-clogged pond, can be achievedby dredging out the pond bed, or ifa dammed pond, by raising thewater level. One effect of greaterpond depth on aquatic vegetation isto put more of the bed at a level thatis too dark for rooted plants. It'shard to say what water depth will becritical in preventing nuisancegrowths of rooted plants. Thatdepends on water clarity, the kindsof plants present and nutrient sup-ply. Having 15 feet of water shouldgreatly reduce plant growthsreaching close enough to the watersurface to interfere with boating andswimming. Depths of 18 feet ormore will often rule out nuisancegrowths of plants. Warning: sincelate 1960s a new aquatic weed,Eurasian water milfoil, has enteredMichigan. It "takes over" pondsand lakes which have abnormalnutrient enrichment. In some situa-tions, it has grown to the surface inwater 18-20 feet deep.

In the case of dredging, anothereffect on rooted plants is to deprivethem of nutrients from organicdeposits in shallow water. Dredgingcan also create steeper side slopes onwhich plants seem to grow poorly.

Increasing the depth and volumeof the pond can have other benefi-cial effects with regard to its abilityto deal with nutrient load and itssuitability for fish. Consider these indeciding whether the expense is just-ified. The cost of deepening a pondcan be immense, whether one modi-fies a dam, dredges by suction, digswith a dragline, or drains and bull-dozes the bed. Finding a site for dis-posal of dredged materials and con-taining them so they do not flowback into the pond or spill intoother water bodies can be difficult.

Waterlevel Drawdown*

Lowering the pond's water leveland exposing all or much of thepond bed to air can have severalfavorable effects and may cost little.Many kinds of aquatic plants will bekilled by drying. It is preferable to

•Contact nearest DNR office (Appendix) to securepermit for this procedure.

A log-and-barbed wire drag for remov-ing vegetation.

do the drawdown in winter when thefreezing of plant tissues, includingperhaps the roots, will give evenmore extensive and lasting kill.Summer drawdown is particularlyineffective on plants such as coon-tail and elodea which grow as free-floating fragments. Still other plantsincrease as a result of summer draw-down. Summer drawdown seems ac-tually to stimulate cattails. Winterdrawdown does not adversely affectwild rice, a plant sometimes desiredat the pond edge.

Where sediments are soft organicmaterial, drying consolidates them,and several inches or feet of ponddepth may be gained. Drawdowncan also facilitate dredging.

For ponds formed by dams ofproper design, draining is especiallyeasy. In dug ponds, pumping isneeded. Low-head, high volumepumps of relatively cheap operationcan usually be used, as the waterneed not be lifted far. Pumps cap-able of draining ponds at least aslarge as 12 acres and 15 feet deep areavailable through contractors. Inaddition to mobile pumps especiallydesigned for drainage, some peoplehave, for small ponds, used old fireengines. It is also possible to makelow-head pumps from outboardmotors.

A word of caution: If shallowwater is left for many days of thegrowing season in parts of the pondpreviously too deep for rootedplants, then the newly lighted en-vironment may allow seeds or plantfragments to sprout and take rootthere. Upon refilling the pond,

A floating rake.

especially if the water level is raisedtoo slowly, the plants may grow up-ward into the normally lighted zoneand become a nuisance. To prevent

51

this, draw the water down as far aspossible, and when the drying and/or freezing has had its effect, raisewater level as rapidly as possible. Ifplants have begun to grow in theshallow drawdown pool, it may bewell to destroy them by raking orother means before refilling thepond.

To avoid fish kills caused by lowdissolved oxygen levels, special cau-tion is advised when using draw-down.

Selective Discharge*In a pond formed .by a dam,

designing the outlet facilities so as tovary the depth from which water isreleased may help control water fer-tility. At certain times of the yearwhen dissolved nutrients are con-centrated at certain levels, dischargewater can be drawn from thosedepths to reduce the pond's totalnutrient load. Possible adverse ef-fects of nutrient-rich discharge ondownstream waters should be con-sidered.

Pond Flushing and Dilution*It is sometimes thought that

removing nutrient-rich pond waterand replacing it with "sterile" water—or simply diluting it—will alleviatealgal blooms and other plant prob-lems. If truly nutrient-poor water isavailable from a well or elsewhere,this might be possible. But the ef-fects would likely be brief if nutri-ents occur in shallow muds whererooted plants can use them or ifnutrients flow from land—which iswhat probably caused the problemin the first place. Also, it is oftenbelieved that diverting "clean"stream water through a pond willkeep nutrient levels low. Althoughnutrient concentration in the streammay be relatively low (not alwaysthe case!), the net effect is to depositnutrients in the pond. The waterslows down and the pond acts as aphysical and biological trap.

Phosphorus lnactivation/Precipita-tion*

Introducing certain chemicals canchange dissolved phosphorus toforms less available to plants or canentrap it and carry it down to thepond bed. The effect may be brief,

as described in the section on pondflushing. Various compounds ofaluminum, iron, calcium and otherelements can be used. The chemicalsare typically broadcast as a powderor injected as a slurry into outboardmotor wash. Aluminate and alum,used in combination, may be avail-able to the pond owner, as may zeo-lite, fly ash, powdered cement andclay. Before using these materials,consult with a limnologist whounderstands the effects and possiblepitfalls of using these materials.Hire a licensed applicator.

Pond AerationPumping air into the depths of a

pond and creating a rising stream ofbubbles, will help aerate a pond.This is done by an on-shore com-pressor which passes air through ahose to the deepest part of the pondwhere a special dispenser, such as anair stone, plastic foam block ormetal baffle, breaks it into fine bub-bles. The rising bubbles draw waterupward, causing the pond water tocirculate from bottom to top andtake on oxygen from the atmos-phere. More oxygen is gainedthrough the pond surface than fromthe stream of bubbles. With thewater of the pond bottom ox-ygenated, the surface of the pondmud is kept oxidized, holdingphosphorus in an insoluable formand less available for growingplants.

In the case of deep trout ponds,there is special equipment (hypolim-netic aerators) for circulating coolwater of the deep zone to the surfaceand back during summer withoutmixing it with the upper layers. Thisavoids detrimentally warming thedepths.

It may be especially important toaerate the pond in winter. Thiskeeps an area ice-free and allowscontinual movement of oxygenfrom the atmosphere into the depthsof the pond. It also reduces transferof phosphorus from mud to waterwhich occurs during winter stagna-tion.

Pondbed Sealing and Blanketing*The pond bed can be covered with

black plastic sheeting weighted witha gravel layer. Use a rake or pitch-

fork to puncture the sheet first withmany small holes to allow escape ofgas formed under it, otherwise theplastic may balloon up through thesand and gravel. The sheet makesmud nutrients less available to plantroots. You can also use a 6- to8-inch layer of sand or gravel aloneto cover organic sediments. This hasthe disadvantage of decreasingvaluable pond depth and appears tohave less lasting effect than whenused on a plastic sheet.

Shading or Coloring the WaterSheets of black plastic supported

by a floating wooden frameworkcan be used to cover large sectors ofpond surface. Such a covering is an-chored in one spot for the 3-4 weeksneeded to shade out plants beneathit, then moved to a new place.Shading with plastic is apparentlyeffective on most submergent plants(except chara) but not on emergents.The device may be cumbersome andunsightly.

Special dyes are available (onewith the trade name, Aquashade)which temporarily color the waterso as to cut off light and controlplants.

Herbicides and AlgicidesKilling pond plants with toxic chem-

icals is another form of temporarychemical treatment. Substances toxic toalgae are called algicides. Those forpoisoning rooted, leafy water plants areaquatic herbicides. You may need apermit from the DNR to use herbicidesand algicides in your pond. Only pondsthat are under single-party ownershipand that have no outlet are exempt frompermits (see Chapter 15).

Chemical treatments have advan-tages of convenience, but the fol-lowing drawbacks should be consid-ered:

— Poisoning kills plants withoutremoving them from the pond.After death, the materialsinks, consuming oxygen,creating odors and releasingnutrients for new plantgrowth.

— The poisoned plants disappearonly slowly from the treatedarea. One to several weeks

•Contact nearest DNR office (Appendix) to seepermit for this procedure.

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may pass before the nuisanceplant masses sink away.

— Since each herbicide killsseveral or many kinds ofplants, beneficial species maybe killed along with the nui-sance plants.

— Localized treatment is diffi-cult. Even ponds that appearplacid have currents that cancarry poison from a problemarea to an area with plant bedsthat should be preserved.

— There is risk of harm to otherlife in the pond and surroun-ding area.

Due to increasing knowledge andconcern about risks of toxic chemi-cal use, various products have beenprohibited by State and Federalauthorities. The list of permissiblesubstances is much shorter now thana few years ago. Full considerationof other alternatives in aquatic plantcontrol is advised before resortingto chemical treatment.

To use plant poisons effectively andwith least hazard to other life, the kindof plant must be identifed, the properchemical obtained, the volume of thepond calculated, and the proper dosageapplied. A list of chemicals presentlyallowed in Michigan for pond vegeta-tion control and the plants they controlcan be obtained from your county Ex-tension Office or from the MDNR In-land Lake Management Unit, Land andWater Management Division, Box30028, Lansing, MI 48909. You shouldobtain an updated copy of this list eachspring since the recommendations canchange. Using chemicals other than onthis list may be illegal and dangerous!Only use chemicals labeled for use inlake and ponds so you have completeinstructions on their use and any specialprecautions to take when applying thechemical to water for weed control.

Dosage rates will be shown on theproduct label. These should beclosely followed. Do not overtreat!Avoid the idea that "if a teaspoon-ful is called for, then a wholeshovelfull will do the job better."This not only wastes money, butmay cause plant decay so rapid thatdissolved oxygen is depleted andfish suffocate—or the chemicaloveruose may poison fish and otherlife. Distribute the chemical evenly

over the area to be treated, whetherusing spray, powder or granularplant poisons. Too much applied inone place increases the risk of killingfish and other organisms. Mostplant poisons work best when watertemperature is above 65 °F (18 °C).

Carefully follow safety precautionsprinted on the product label. Don't letthe chemical reach crops and otherdesirable plants or trees. Choose a calmday for treatment in order to avoid winddrift. Don't use the treated water forirrigation, agricultural sprays, livestockwatering or swimming until a periodhas elapsed as advised on the label.Recommended waiting periods beforevarious pond uses are included with theannual list of approved chemicals avail-able from the county Extension officesor the MDNR. Don't eat fish from thepond for 3 days after treatment, orlonger if stated on the label. Bathe andchange clothes following use. In caseof contact, immediately flush skin oreyes with much water for at least 15minutes. Call a doctor immediately andhave the chemical label with you forquick reference. Thoroughly washspray equipment after each use. Disposeof all empty containers and clean up allspills. Take care that insecticide con-tamination of the pond does not occurfrom previous use of the sprayer for in-sect control.

Copper sulfate has been widelyused to kill algae and is commonlyavailable from agricultural supplyoutlets which sell it for other pur-poses. They generally don't provideinstructions for its use as analgicide. No copper sulfate or othercopper-based chemicals should everbe used in trout ponds. Neithershould copper sulfate be applied ex-tensively in other fishing ponds, eventhough it is frequently described assuitable for use in human drinkingwater supplies or where fish will beconsumed. The high copper contentcan harm fish food organisms andfish reproduction. Copper sulfate isdifficult to use properly. Its effectsvary greatly depending on waterhardness and other factors. In ex-tremely softwater ponds, very littlecopper sulfate may kill the algae—but also kill the fish. In a very hardwater situation, it may take muchmore copper sulfate to kill the algae,yet the danger to fish may be much

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less. Never apply more than thedosage listed on the label.

Copper sulfate is best applied bydissolving the crystals in water andspraying on the surface or by plac-ing them in a burlap bag and pullingit through the pond until dissolved.Simply throwing copper sulfatecrystals into the water results in ac-cumulations on the bottom where itmay poison fish food organismswhile having little effect on the algalproblem.

If you wish to poison algae withcopper, the risk may be loweredsomewhat by using chelated copper.It is available as a product (trade-name "Cutrine") well-labeled withinstructions for use, and it achievesthe same algicidal effect as coppersulfate with a much lower concen-tration of copper. This is less likelyto harm fish and other pond life.

Chara algae can be particularlyhard to control with toxic chem-icals, because it often has a crust oflime (calcium carbona te or"scale"). Therefore chara should bechemically treated only in the springbefore a heavy crust forms. Coppersulfate is not advised for control ofchara. The amount needed to killthis plant would be hazardous toother pond life. Cutrine and Hydra-thol 47 may be more effective onchara.

Biological ControlControlling aquatic vegetation with

plant disease organisms or by plant-eating fish, waterfowl or other animalshas been tried in many parts of theworld but holds little promise at presentfor Michigan conditions. The plant-eat-ing Asiatic grass carp (Ctenopharyn-godon idella), euphemistically called"white amur" by its promoters, hasbeen legalized in some states. In addi-tion to eating problem plants, it eatsbeneficial plants that are used asbreeding habitat for pike and muskies,that serve as cover for young game-fishes and that are food for wildlife,especially waterfowl. Since the grasscarp will not eat all aquatic plants andalgae, the plants it won't eat will growin place of the plants that it will eat.Recent studies show that the totalamount of plant material remains thesame after grass carp are stocked; onlythe types of plants change. Con-

muskrats and from normal waterlineto the top of the dam or to the top ofthe bank for woodchucks.

• Use soil cement in the top 6inches of earth from 3 feet belowlow waterline to 3 feet abovenormal water level for muskratsand from the normal water- lineto the top of the bank or dam forwoodchucks.

• Cover with vinyl coated chickenwire from 3 feet below lowwaterline to 3 feet above normalwater level for muskrats andfrom the normal waterline to thetop of the dam or bank for wood-chucks.

Reducing Muskrat andWoodchuck Populations

Damage caused by muskrats andwoodchucks can be greatly reducedby eliminating as many woodchucksand muskrats as possible, if the pondis not adjacent to extensive muskrator woodchuck habitat. If the areasurrounding the pond has extensivewetlands or extensive meadows,hayfields, or agricultural lands, thenthe animals that are eliminated willbe replaced very quickly by new ani-mals from the surrounding habitat,and damage will be reduced onlyslightly, if at all.

Muskrats and woodchucks can beeliminated by shooting, trapping,and fumigation. All of these methodsrequire either a legal hunting license,trapping license, or a damage controlpermit issued by a DNR conser-vation officer. Because these regula-tions change occasionally, check theannual hunting and trapping regula-tions and consult your local conser-vation officer concerning specialprovisions for damage control.

ShootingMuskrats can be shot as they swim

across the pond surface or foragealong the edge of the water especial-ly in the early morning and lateevening. For safety reasons, use ashotgun loaded with shells contain-ing No. 1, 2, 3, or 4 shot. Muskratshooting requires a damage controlpermit. Woodchucks can be easilyshot as they forage around their bur-row openings throughout the dayexcept in the middle of an extremelyhot, sunny day. Since it is usually

Bait set

Various types of trap sets for removing muskrats.

difficult to get within shotgun rangeof a woodchuck, shooting usuallyrequires a rifle. Woodchuck shootersneed either a hunting license or adamage control permit.

TrappingThe easiest way to trap muskrats

and woodchucks is to use a bodygripping trap that kills the animalinstantly. These traps, called coni-bear traps, are placed directly overthe burrow entrance or along run-ways or in areas where muskrats aredigging into the bank for under-ground roots, bulbs, etc. When theanimal tries to pass through the trap,the trap is set off and the animal isinstantly killed. Use conibear trapsize 110 for muskrats, 120 for wood-chucks less than ten pounds, and 160for woodchucks over ten pounds. Atrapping license or damage controlpermit is required. When muskratsare trapped under a trapping license,all trapping regulations must beobeyed. If leg hold traps are used tocatch muskrats, they can be set as

Turtle trap.

bait sets, slide sets, float sets, orunder-ice sets, but be certain to fas-ten traps to stakes placed in deepwater so muskrats quickly drownand don't twist or gnaw feet off andescape. Again, all sets must be made ,in accordance with trapping regula-tions if done under a trappinglicense. If you obtain a damage con-trol permit for use on your own land,

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trapping regulations do not apply.You may also use repeater traps inthe burrows to catch several musk-rats at one setting.

Muskrats and woodchucks can becaught in the appropriate sized wirebox trap. Bait these traps with slicesof apple, white or sweet potato, orbanana, pieces of carrot or any simi-lar item that the woodchuck andmuskrats readily accept. Animalscaught in the wire box traps canthem be humanely destroyed ortransported to another location andreleased providing you have the per-mission of the landowner uponwhose land you release the animal.A trapping license or a damage con-trol permit is also needed.

Burrow Fumigation

Muskrats and woodchucks can beasphyxiated in their burrows byfumigation with concentrated smokeor toxic gas. A damage control per-mit is required. Additional informa-tion and certain supplies for damagecontrol can be obtained from theUnited States Department ofAgriculture Animal Damage ControlOffice. Check with your MSUExtension County Office or theDistrict DNR Office for the addressand phone number of the state ADCoffice. Whenever using fumigation,apply the material as directed by thelabel then seal the burrow entrancewith a piece of inverted sod or alarge wad of damp cloth or newspa-per. Wait five minutes to see if aplume of smoke is rising from a sec-ond entrance. If the plume of smokeis seen, treat the second entrance inthe same manner. After three days,check to see if the burrows havebeen reopened. If they have beenreopened, re-treat in the same man-ner during night hours.

MolesMole burrows can destroy patches

of sod on dams or pond banks,which causes erosion. Mole damagecan be controlled by direct killing,trapping, or burrow fumigation. Inail cases, only treat active tunnels.To «££ if a tunnel is being activelyused, gefttly flatten a short section ofthe ridge above the tunnel. If in use,

the ridge will be raised again within24 to 48 hours. Applying any moledamage control method to inactiveburrow systems is futile. For furtherdetails contact your local MSUExtension county office.

BirdsSeveral kinds of fish-eating birds

consume fish from fish ponds, espe-cially kingfishers, herons, mer-gansers, and domesticated ducks.Fish-eating birds may also carry par-asites that infect fish. All of thesebirds can be scared away by noisemaking devices, such as gas pow-ered automatic explosion cannonsand bird scaring shotgun shellswhich fire an explosive charge intothe air that detonates 50 to 100 yardsaway. Use exploders and scare shellsin combination. The locations, firingintervals, and firing times must bevaried, at least every third day, orthe birds soon become accustomedto these frightening techniques.

Scarecrows, artificial snakes,hawk or owl decoys, and special birdfrightening balloons can also be usedto scare birds away. These devicesmust be positioned imaginativelyand must be moved frequently, atleast every other day, or they soonbecome ineffective. They are mosteffective if used in combination withscare shells and automatic explosioncannons.

Discourage herons by gradingpond edges to form rather steepunderwater side slopes. Three feet ofhorizonal distance per foot of slopeis the maximum slope recommendedfor safety (see Chapter 3 — PondConstruction). If necessary, suspendchicken wire horizontally at or nearthe water surface along the shallowparts of the pond edge.

Discourage kingfishers by remov-ing all perches, such as posts anddead tree limbs, close to the pond. Ifmuscovy ducks are kept in the pond,confine them to a small part of it.Kingfishers, herons, mergansers andother migratory birds are protectedby federal law. Consult the U.S. Fishand Wildlife Service or U.S. Depart-ment of Agriculture Animal DamageControl about regulations.

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Swimmer's ItchSwimmer's itch is caused by a

minute free-swimming parasite thatburrows into and irritates the skin.This parasite is carried by waterbirdsand develops in certain kinds ofsnails before it attacks humans.

Ridding a pond of swimmer's itchmeans controlling the water birdsand snails. Do not feed ducks, geeseand other water birds that can carrythe parasite. Remove plants andpond bottom debris to help furtherreduce water bird numbers and tohelp control snails. Copper sulfatehas also been used to poison snailsunder an extra-label exemption. Formore information contact theMichigan Inland Lakes ManagementUnit of the Land and Water Manage-ment Division of the DNR (Box30028, Mason Building, Lansing, MI48909, 517-373-8000). Do not usecopper sulfate treatment in pondscontaining trout; trout are extremelysensitive to copper.

Turtles and SnakesTurtles, especially snapping tur-

tles, and snakes, especially northernwater snakes, eat fish. Turtles alsoeat fish eggs, fish on stringers, andbait from hooks. In recreational fishponds, turtles and snakes rarely eatenough fish to have an effect on thefish population. Turtles and snakesdo not feed daily as do mammals andbirds, and then they feed primarilyon minnows, other small fish, andthe smaller game fish. Because onlysmall game fish are taken and thentaken infrequently, the effect of thispredation rarely reduces the numbersof large catchable game fish.

Some pond owners want to re-move turtles and snakes simplybecause they are afraid of them ordon't like them. Snake and turtlepopulations can be reduced by mow-ing pond bank vegetation andremoving logs, tree roots, branches,and large stones from the shoreline.Reducing this habitat reduces theopportunity for these animals to sur-vive, but mowing eliminates theadvantages of having a vegetationalbuffer strip to filter nutrients and siltout of water that runs off into thepond. Persistent killing can also

reduce snake populations, but indis-criminate killing of all snakesregardless of species accomplisheslittle and may create or intensifyother problems, such as rodents.

If it becomes necessary to removeturtles from a pond, turtles are easilytrapped using a trap that is easilyconstructed from chicken wire. Tomake the trap, roll a piece of one-inch mesh chicken wire 60" wideand 60" long into a cylinder 60"long. On both ends of the cylinder,make 4 cuts, 15" apart. Each cutshould be 12" deep. Now fold theseends of the cylinder inward and reat-tach the cut ends to each other tocreate funnels pointing inward witha small end opening of approximate-ly 12" by 6". A trap of this size willcatch all but the largest snapping tur-tle. To trap a very large snappingturtle that weighs more than 20 lbs.,start with a piece of chicken wirethat is 6 by 8 feet. Follow the previ-ous directions but this time make theopening of the small end of the fun-nel leading into the trap approxi-mately 10" by 18".

To use the trap, place it in shallowwater where turtles are most likelyto feed. Make sure that the top partof the trap is above water so thatentrapped turtles or other animalsaccidently trapped do not drown.Nylon rope or metal cable should befastened to the trap and tied securelyto a tree, rock, stake or other non-moveable object on shore so thatentrapped animals do not roll thetrap into deeper water and drown.Almost any meat bait will workeffectively in the trap, but one of themost convenient and effective baitsavailable is a partially opened can ofsardines. Place the partially opened

can into the trap before putting thetrap in the pond.

MosquitoesMosquitoes don't generally thrive

in fish ponds. If much of a fish pop-ulation exists, the mosquito larvaewill be eaten. Moreover, mosquitoesneed calm water surfaces for devel-opment. Any parts of a pond thatwind ripples will be unsuitable. Onlyvery shallow, protected pond edgeswill support them. Small fish usuallydispose of most larvae in theseplaces.

Most kinds of mosquitoes thatcause problems for people comefrom temporary puddles that lackfish. Keeping a stable pond waterlevel prevents the frequent floodingof shoreland which would make iso-lated puddles for mosquito breeding.Don't try to control mosquito breed-ing unless you have found exactlywhere they're breeding. Then con-fine control efforts to those sites.

Beware of using insecticides nearponds to control mosquitoes. Thesechemicals are very likely to kill thefish.

A safe, effective, and pleasantmosquito control is to install a pur-ple martin house near the pond or atthe area of human activity. Onecolony of martins will usually keepmosquitoes at a tolerable level dur-ing daytime and early evening.

Another biologic way to controlmosquitoes is with gambusia fish.These small warm-climate fish canbe stocked in marshes, swales andseasonal puddles where our nativemosquito-eating fishes are frozenout in winter. Gambusia also die incold weather, but it's easy to recap-

ture a few and keep them indoorsduring the winter, then stock themagain in late spring. A few in eachseparate water area will multiply fastand keep mosquito larvae croppeddown.

Leeches(Bloodsuckers)

Michigan has about 50 species ofleeches, of which only four attach tohumans. Most kinds of leeches feedon other animals, such as turtles, oron dead matter. Therefore, the firstthing to determine is whether leech-es are attaching themselves to peo-ple—or whether leeches have mere-ly been sighted in the water. No con-trol is needed unless the leeches aredefinitely causing a problem.

Often, the most effective way toreduce leech populations is to reducethe amount of organic debris on thepond bed. Leeches dwell in accumu-lations of twigs and leaves at the bot-tom of the pond and swim up orreach out to attach to host animals.Some leeches attach to aquatic plantsand stretch to amazing lengths insearch of passing food. Preventing orcontrolling beds of dense vegetationmay also help to control leeches.

Another method for controllingleeches is to have plenty of bass inthe pond — or trout, if it is a cold-water pond. Such fishes are avidpredators on most of the trouble-some leeches. In fact, some kinds ofleeches are highly effective fishingbaits, and they are a hot-selling itemat bait shops. Stocking 25 to 50yearling (6-8-inch) bass per acreshould reduce leech populations sothat they are no longer a problem.

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Fish Parasites and Diseases

It's normal for pond fish to haveparasites such as grubs, or wormson or in the skin, attached to thegills, within the gut, or embedded inthe flesh. No fish parasites inMichigan pose a threat to humanhealth if the fish is cookedthoroughly before being eaten.Neither should the parasites affectflavor of the fish. The sight of themmay be unappetizing, but few of themany fish parasites are detected bymost people during cleaning, cook-ing and eating.

Parasites may be especiallynumerous on fish that live inshallow, weedy ponds. Fish from

deep ponds with few weeds general-ly have fewer parasites. Many of theparasites that infest fish live part oftheir lives in host animals, such asclams and snails, that dwell inshallow water or on plants. Becausethere are so many kinds of these in-termediate hosts, it's impractical totry to control fish parasites in mostponds—other than by making thepond deeper and less weedy.

Some of the more common kindsof fish parasites are: threadworms,spiney-headed worms, tapeworms,anchor worms, flukes, fish lice orgill lice, leeches, lamprey, and vari-ous microscopic organisms. The

Table 12-1. Common Fish Diseases and Their Symptoms

Name of disease(and fishes affected) Causative agent Symptoms

Skin fungus or water mold(all fishes)

Columnaris(all fishes)

Red sore(northern pike)

Furunculosis(trout and salmon)

Black spot or black grub(mostly warmwater fishes*)

"Ich" or white spot(mostly warmwater fishes)

Lymphocystis(perch, walleye, sunfishes)

Tumors and other deformities(all fishes)

Saprolegnia fungus(often results from injuryto skin)

Chondrococcuscolumnaris bacterium

Aeromona liquefaciensbacterium

Aeromonas salmonicidabacterium

strigeoid trematodes

Ichthyophthiriusmulfifilis protozoan

Injuries, dietary problems,genetic causes, etc.

Tufted growths of fine white orgray threads radiating V3 inchor more from body.

Grayish-white spots surroundedby red on parts of head, gills,fins or body.

Open bleeding sores from whichscales are lost.

Boils or furuncles on skin, in-flammation of inner body walls,many small internal hemor-rhages, bright red spleen andswollen kidneys.

Small black spots just underskin and in muscle. These arecysts containing a microscopicstage of this fluke.

Tiny white spots on body.

Raised nodular masses of light-colored tissue resembling wartson skin.

External and internal tumors ofvarious sorts, spinal defor-mities, shortened or flattenedheads.

•Also trout where the water is unfavorably warm.

Life cycle of the yellow grub.

broad tapeworm of man, infre-quently found in fish from a fewwaters in Michigan's Western UpperPeninsula, is the only real threat tohumans—but again, only in cases ofinadequate cooking.

Aside from effects of parasites onthe appearance of fish flesh, someparasites and diseases can severelyhamper fish growth and survival.This is most likely to be a problemwhere fish are crowded, as in troutponds where the number of fish iskept unnaturally high by heavystocking and supplemental feeding.Disease is also more likely to occurwhen the fish are stressed by un-favorable temperature, low oxygensupply, or other water quality pro-blems.

Common diseases of Michiganfishes are listed in Table 12-1. If thesymptoms described there arenoted, or if abnormal numbers ofdead fish occur, contact a privatefisheries consultant for positiveidentification and proper treatment.See the Appendix for informationon private consultants. Disease orparasite identification and treat-ment recommendations can also beobtained for a fee by sending speci-mens of the fish to the MichiganState University Animal DiagnosticLaboratory (East Lansing 48824).

Pond owners should carefully ex-amine fish they intend to stock. Ifthe fish show signs of distress, para-sites or disease, don't stock them.They may be a poor investment andmay infest other fish in the pond. Afish breeder or dealer who deliversdiseased fish for stocking should beinstructed to keep and treat all fishor destroy them. Under no circum-stances should diseased fish bestocked into public waters. In fact,for this very reason, no fish shouldbe stocked in public waters withouta state permit

Life cycle of the "ich" skin parasite.

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Pond Safety and Liability

A fishing pond may also furnishsome swimming, boating, hunting,ice skating, wading, and picnicking,although it may be designed to makeit best for fish and without idealfeatures for other uses. It will be aspecial attraction to children.

Because a pond attracts people, itpresents an accident hazard.Drownings are second only tomotor-vehicle mishaps as a cause ofaccidental death among people inthe active age groups, particularlychildren.

Each pond owner has moral andlegal obligations to family, friends,neighbors, and even trespassers tomake the pond as safe as possible.Providing certain safeguards canprevent an incident from becomingan accident or even a fatality. Simp-ly posting a pond against trespassdoesn't relieve the owner of respon-sibilities. Legal liability is often bas-ed on whether the owner has takenall reasonable precautions againstmishaps. A pond owner should con-sult his or her attorney and insur-ance company about liability forserious accident or death and aboutlegal requirements for safety pre-cautions at the pond.

Find out what both communityand state liability laws are for injuryor death resulting from use of thepond. Local laws may vary greatly.This is especially important if theowner intends to open the pond tothe public and charge a user fee.

Here is a list of fairly economicalsafety measures:

— Grade the pond bed to elimi-nate steep slopes or drop-offs.

— Remove stumps, logs, largerocks, and trash that couldpose a hazard to waders,swimmers, and boats. Broken

glass and other sharp objectsare especially to be eliminated.Place warning signs near spe-cific danger areas, tellingwater depth and location ofnearest telephone.If there is to be swimming,mark a safe special area for itwith buoyed lines.Install life-saving equipmenton the pond bank where it canbe easily seen and used.Be sure that piers, rafts, andlandings are well-constructedand braced.Erect adequate fencing andgate with lock to prevent un-authorized entry, especially bychildren.Keep boats used on the pondin good condition. Never over-load them. Instruct passengersnever to stand up in the boat.Provide one Coast Guard ap-proved life preserver for eachperson on board. Use com-mon-sense boat safety in allother respects!Beware of thin ice! Test icestrength with a spud or auger,and actually measure ice thick-ness before venturing overdeep water. Don't walk orskate on freshly-formed icethat is less than three inchesthick. If ice is thawing, it mayhave to be much thicker thanthat. Snowmobiles shouldn'tbe driven onto ice less thanfive inches thick.Keep a wooden ladder at thepond edge in winter. This canbe shoved to someone who hasfallen through the ice.Never let a child play at thepond alone, no matter whatthe season.

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— Everyone who lives, works, orplays near a pond shouldknow how to swim and how togive artificial respiration. Findout more about it from yourlocal Red Cross organization.

Follow these steps to install a rescuestation:1. POST—a 6-ft two-by-four orfour-by-four, preferably paintedyellow. Set post about 2 ft intoground, standing no more than 4 ftout of ground, near water at anypoint where swimmers might get in-to trouble. Paint "THINK, THENACT" down length of post on allsides. About 1 ft from top of post,attach metal shelf bracket, woodenarm, or 60-penny spike as hook forcoiled rope and jug float.2. JUG—a gallon plastic jug withan inch of water inside for throw-ing. Paint "FOR EMERGENCYUSE ONLY" on side.3. LINE—a 40-ft length of plastic-coated clothesline. Tie one end tohandle of plastic jug. At oppositeend, fasten a 4-inch piece of two-by-four to prevent line from slippingcompletely through hands or fromunderfoot when thrown.4. POLE—a 10-ft or 12-ft bamboopole or sapling. Since pole will beused to extend to anyone strugglingin water, tip and butt should bewrapped with friction tape to reduceslippage. Paint pole white. Holdpole in upright position by placing itin two 6-ounce tin cans, nailed nearbottom of the post about 6 inchesapart.5. TIN CONTAINER—a 46-ouncejuice can or a 2- or 3-lb coffee can.Remove one end, then slide can overtop of post. Fasten down with onenail through center of top so it ispossible to rotate and read theposter described below.6. POSTER—a sheet of safety tips,rescue methods, and emergency tele-phone numbers. After applying acoat of spar varnish to can, attachposter to can and mount can at topof post. Let dry thoroughly, thenvarnish poster to protect againstweather.Note: Add a ladder to the rescue sta-tion, if the pond is likely to be usedin winter.

Steps in making a rescue station.

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State Regulations On Pond BuildingAnd Management In Michigan

The Michigan Department ofNatural Resources (MDNR) activelyregulates pond construction and man-agement. The laws exist to protectour state's environmental resources.

Pond ConstructionAny pond built in violation of

local, state, or federal law or withoutthe appropriate permits may be con-sidered illegal. Civil action may beinitiated and the court can order theremoval of the pond and renovationto the pre-existing habitat at theowner's expense. A state permit isneeded for constructing a pond ifany of the following are true:

— It will be formed by dammingany running water.

— It will be connected to any run-ning or standing body of waterincluding wetlands.

— It will be within 500 feet ofany other water body.

Contact the nearest DNR office orSoil Conservation office early in thepond planning to find out whatrestrictions may apply to your situa-tion and to determine what local,state, or federal permits, if any, willbe needed.

Using ChemicalsAny use of chemicals to kill or

control algae, weeds, fish, or aquaticpests (for example, swimmer's itch)may require a permit or require certi-fication of the applicator. Permits arerequired for chemical application to aporrd. jf any of the following are true:

— It is not entirely private orunder single-party ownership.

— It has any type of outlet.— It is within 500 feet of any

other water body.— It is 10 surface acres or greater.Contact the Inland Lakes Manage-

ment Unit, Land and Water Manage-ment Division of the DNR (P.O. Box30028, Mason Building, Lansing, MI48909, 517-373-8000) for permitapplications to control algae, weeds,or aquatic pests. Contact the FishDivision of the DNR for permits tocontrol unwanted fish populations.

Lists of certified aquatic pesticideapplicators can be obtained from theMichigan Department of Agriculture,Pesticide and Plant Pest ManagementDivision (P.O. Box 30017, Lansing,MI 48909, 517-373-1087).

Fish StockingAn MDNR permit is required for

fish stocking in public waters, inprivate waters having fish migrationfrom public waters, and in privatewaters connected by any water routewith bodies of water in other owner-ship. "Private" means that the pondis in single-party ownership. Nostocking permits are needed in pondswhich are completely landlockedand under single-party ownership.

A state license is also required foranyone who wishes to sell fish forstocking. This is called a "fishbreeder's license." A seller of fishmust have this license whether ornot he or she is the actual breeder ofthe fish or just a dealer for fish thatsomeone else has bred.

Tight regulation of fish sellingand stocking is needed to controlfish diseases and to prevent entry ofcertain kinds of fish into waterswhere they might be harmful.Importation of fish into Michiganfrom other states or Canada needs afurther special permit.

For stocking the kind of pond thatneeds a fish stocking permit,contact the nearest MDNR DistrictFishery Biologist (list in Appendix).There is no application fee. Apply atleast a month in advance. Helpfuladvice on how best to stock thepond may be gained in the process.

IntroducingExotic Fish

Exotic is the term applied to kindsof fish not native to an area. Fishesexotic to Michigan may not bebrought in or possessed here with-

out a special permit from MDNR.No permits will be issued for impor-tation of any exotic species until ithas been proved that such an intro-duction would not cause harm.Much environmental degradation hasbeen caused by exotics introduced inthe past. The common carp is anexample.

The recently much publicized Asi-atic grass carp (white Amur) andvarious kinds of tilapia fishes are ex-otics often suggested as aids in pondweed control or food production.Present policy forbids issuance ofpermits for them. Their harmless-ness hasn't been proved, and there ismuch reason to suspect that the grasscarp would damage lake and pondhabitat for fish, waterfowl, and othervalued animals. Don't purchase oraccept gifts of grass carp or otherexotics.

Fishing RegulationsA current Michigan fishing license

is required for all persons of 17years or older when fishing on pondsthat are public or have a connectionthrough which fish may enter frompublic waters at some time of theyear. In such ponds, statewide fish-ing seasons, size and creel limitsapply.

In landlocked ponds with singleownership of the banks, statewidefishing laws don't apply, and nofishing license is needed. Anglerstaking trout, bass, or other game orpanfishes from such ponds duringclosed seasons or in numbers orsizes at variance with state lawshould obtain written verificationthat the fish were taken from privatewaters before transporting them on apublic road or highway.

64

References for Further Reading

Pond Planning andConstruction

Gibson, G. R., Jr. 1979. ARiparian's Guide for Self-Help In-land Lake Water Quality Manage-ment. Extension Bull. E-1117,Michigan State Univ., East Lansing.67 pp.

U.S.D.A. Soil Conservation Ser-vice. 1973. Building a Pond. U.S.Dept. of Agriculture. Washington,D.C. 13 pp.VanDusen, P., W.M. Marsh & T.E.Borton. Undated. Planning andManagement Guidelines for InlandLake Property Owners. Inland LakeManagement Unit, Mich. Dept.Natural Resources, Lansing. 12 pp.

Life of Ponds—General(Identification of organisms,

biology, ecology.)

Amos, W. H. 1967. The Life of thePond. McGraw-Hill Book Co., NewYork. 232 pp.Brown, E. S. 1955. Life in FreshWater. Oxford Univ. Press, Lon-don. 64 pp.Coker, R. E. 1968. Streams, Lakes,Ponds. Harper & Row, New York.327 pp.Klots, E. B. 1966. A New FieldBook of Freshwater Life. G. P. Put-nam's Sons, New York. 398 pp.Reid, G. K. 1967. Pond Life: AGuide to Common Plants and Ani-mals of North American Ponds andLakes. Golden Press, New York.160 pp.

Wa>4 H. B., & G. C. Whipple.1959. Fresh-water Biology. 2nd Edi-tion (W. T. Edmondson, ed.). Wiley& Sons, New York. 1248 pp.

Identification of FishesEddy, S. 1969. How to Know theFreshwater Fishes. Wm. C. BrownPubl., Dubuque. 286 pp.Hubbs, C. L., & K. F. Lagler. 1964.Fishes of the Great Lakes Region.Univ. of Michigan Press, Ann Ar-bor.Scott, W. B., & E. J. Crossman.1973. Freshwater Fishes of Canada.Bull. 184, Fisheries Research Boardof Canada, Ottawa. 966 pp.

Identification of AquaticInvertebrates

Pennak, R. W. 1978. Freshwater In-vertebrates of the United States.Wiley, New York. 803 pp.See also various references under"Life of Ponds—General", above.

Identification of AquaticPlants

Fassett, N. C. 1957. A Manual ofAquatic Plants. Univ. of Wis.Press, Madison. 405 pp.Prescott, G. W. 1964. How to Knowthe Freshwater Algae. Wm. C.Brown Co., Dubuque. 348 pp.Stodola, J. 1967. Encyclopedia ofWater Plants. T. F. H. Publica-tions, Neptune City, N.J. 368 pp.Winterringer, C. G., & A. C.Lopinot. 1966. Aquatic Plants ofIllinois. Illinois State Museum. 141PP.

Nutrient Overenrichmentand Aquatic PlantProblems/Control

Anonymous. 1978. Aquatic Plantsand Their Control. Div. of Land

65

Resource Programs, Mich. Dept.Natural Resources, Lansing. 9 pp.Dunst, R. C. et. al. 1974. Survey ofLake Rehabilitation Techniques andExperiences. Tech. Bull. 75, Wis.Dept. Natural Resources, Madison.179 pp.King, D. L. 1979. Lake Eutrophica-tion: Definition and Causes. Pages5-11 in "Inland Lake Eutrophica-tion: Causes, Effects, and Rem-edies." Institute of Water Research,Michigan State Univ., East Lansing.

McNabb, C. D., Jr. 1977. AquaticPlant Problems in RecreationalLakes of Southern Michigan. Exten-sion Bull. E-1135, Michigan StateUniv., East Lansing. 25 pp.

Nichols, S. A. 1974. Mechanicaland Habitat Manipulation forAquatic Plant Management. Tech.Bull. 77, Wis. Dept. NaturalResources, Madison. 34 pp.

Smith, S. A., D. R. Knauer & T. L.Wirth. 1975. Aeration as a LakeManagement Technique. Tech.Bull. 87, Wis. Dept. Natural Re-sources, Madison. 39 pp.

Vallentyne, J. R. 1974. The AlgalBowl: Lakes and Man. Environ-ment Canada Fisheries and MarineService, Ottawa. 186 pp.

Pond FisheryManagement

Bennett. G. W. 1971. Managementof Lakes and Ponds. Van NostrandReinhold, New York. 375 pp.Eipper, A. W., & H. A. Regier.1962. Fish Management in NewYork Farm Ponds. Extension Bull.1089. Cornell Univ., Ithaca.Klingbiel, J. H., L. C. Strieker & O.J. Rongstad. 1972. Wisconsin FarmFish Ponds. Univ. of Wisconsin Ex-tension. Madison. 44 pp.

Lopinot, A. C. 1972. Pond Fish andFishing in Illinois. Fishery Bull. No.5, Illinois Dept. of Conservation,Springfield. 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.

Novinger, G. D., & J. G. Dillard,eds. 1978. New Approaches to theManagement of Small Impound-ments. Special Publ. No. 5, NorthCentral Div. American FisheriesSociety. 132 pp.

Pond FishingCary, R. 1967. How to Catch Fish inFresh Water. Fisherman's InformationBureau, 20 N. Wacker Dr., Chicago,Illinois. 31 pp.

Merwin, J., ed. 1980. Stillwater Trout.Nick Lyons Books, Doubleday & Co.,Garden City, N.Y.

Prospects forCommercial Aquaculture

Cain, K. and D. Garling. 1993. TroutCulture in the North Central Region.North Central Regional AquacultureCenter. Fact Sheet Series #108.

Chopak, C.J. 1992. Promoting Fee-fishing Operations as Tourist Attrac-tions. MSUE Bulletin E-2409.

Chopak, C.J. 1992. What ConsumersWant: Advice for Food Fish Growers.MSUE Bulletin E-2410.

Chopak, C.J. 1992. What Brokers,Wholesalers, Retailers, and Restau-rants Want: Advice for Food FishGrowers. MSUE Bulletin E-2411.

Chopak, C.J., and J.J. Newman.Aquaculture. Status and Potential ofMichigan Agriculture. MAES SpecialReport 50.

Garling, D.L., and L.A. Helfrich.1984. Making Plans for CommercialFish Culture in Michigan. MSUEBulletin E-1775.

Garling, D.L. 1992. Making plans forcommercial aquaculture in the NorthCentral Region. North Central Re-gional Aquaculture Center, Fact SheetSeries #101.

Kinnunen, R.E. 1990. Salmonid eggand fingerling purchases, productionand sales. North Central RegionalAquaculture Center, TechnicalBulletin Series #103.

Kohler, S.T. 1992. Choosing an orga-nizational structure for your aquacul-ture business. North Central RegionalAquaculture Center, Publication #103.

66

Appendices

District Offices of theMichigan Department ofNatural Resources

Contact the nearest one regardingpermits for the following pond man-agement activities: damming; ponddigging or redredging within 500 ft.of any flowing water; fish stocking;pond draining; use of algicides orweed-killing chemicals; use of fishtoxicant chemicals; and aquaticweed cutting or harvest.

1. North U.S. 41, Box 440Baraga, MI 49908(906-353-6651)

2. 1420 U.S. 2 WestCrystal Falls, MI 49920(906-875-6622)

3. 6833 Highway 2, 41 & M-35Gladstone, MI 49837(906-786-2351)

4. P.O. Box 77RR 1, South M-123Newberry, MI 49868(906-293-5131)

5. 1732 M-32 WestGaylord, MI 49735(517-732-3541)

6. 8015 Mackinaw TrailCadillac, MI 49601(616-775-9727)

7. P.O. Box 939191 S. Mt. Tom RoadMio, MI 48647(517-826-3211)

8. 503 W. Euclid Ave., Suite 98Bay City, MI 48706(517-684-9141)

9. 350 Ottawa, N.W.Grand Rapids, MI 49503(616-456-5071)

10. 621 W. 10th StreetBox 333Plainwell,MI 49080(616-685-6851)

11. 301 E. Louis Glick Hwy.Jackson, MI 49201(517-780-5000)

12. 38980 Seven Mile Rd.Livonia, MI 48152(313-953-0241)

Michigan State UniversityExtension

MSU Extension county offices arelisted in the phone book under yourcounty government. They can provide alocal source for additional copies ofthis bulletin and additional bulletinsand information about ponds and com-mercial fish culture.

Sources of Fishfor Stocking

Contact one of the above offices fora free list of licensed fish breeders.

Consulting Biologists forPrivate Pond Investigationand ManagementList available from:

Extension Aquatic ProgramDept. of Fisheries & WildlifeMichigan State UniversityEast Lansing, MI 48824(Phone 517-355-7493)

Fish Disease Diagnosisand Prescriptionsfor ControlAnimal Health Diagnostic LaboratoryMichigan State UniversityEast Lansing, MI 48824(Phone 517-353-1683)

Aquatic PlantControl PermitsMDNR Inland Lake Management UnitLand and Water Management DivisionBox 30028Lansing, MI 48909(Phone 517-373-8000)

Certified Aquatic PestApplicators ListMDA Pesticide and Plant Pest

Management DivisionP.O. Box 30017Lansing, MI 48909(Phone 517-373-1087)

Animal DamageControl PermitsUSDA Animal Damage Control108 Spring StreetSt. Johns, MI 48879(Phone 517-224-9517)

67

M S U IS a n Affirmative-Action Equal-Opportunity Institution. MSU Extension programs are open to all without regard to race, color,national origin, sex, disability, age or religion.

Issued in furtherance of Cooperative Extension work in agriculture and home economics, acts of May 8, and June 30, 1914, incooperation with the U.S. Department of Agriculture. Gail L. Imig, director, Michigan State University Extension, E. Lansin3rJi/U-48824.

This information is for educational purposes only. Reference to commercial products or trade names does not imply endorsement by the MSU Extension or biasagainst those not mentioned. This bulletin becomes public property upon publication and may be reprinted verbatim as a separate or within another publicationwith credit to MSU. Reprinting cannot be used to endorse or advertise a commercial product or company.

Minor Revision-7.5M-4:94-TCM-FP-Price $3.50, for sale only.File 23.232 (fish and Wildlife Habitat)