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Ashland NFWCO
 Midwest Region
 Dedicated To The Tribal Aquaculture Program March 1996 - Volume 15
  **Administrative        Coordinator:**        **Frank G. Stone        (715-682-6185) Ext.****202        U.S. Fish and Wildlife Service****Email:        [email protected]**      **Edited        By:**        **Elizabeth W. Greiff        (715-349-2195)        St. Croix Tribal Nat. Res. Depart.****Email:****[email protected]**
  Topics Of Interest: Bacterial Diseases Rules ofChemotherapuetic Treatment Pond Culture ofWalleye Fingerlings Water QualityTest Methods for Aquaculture Effluents fromCoolwater Fish Ponds Hatchery Tip  **Bacterial Diseases** **By: A. K. Hauck, Aquaculture Magazine, July/August 1995** Reduction of stress in the environment can be accomplished by examining and improvingmanagement practices. This includes proper pond loadings and reduced handling, adding0.1-0.3% sodium chloride to hauling containers, treating with drugs only when necessary,avoiding rapid temperature changes (greater than 10F) during stocking, cleaning pondsregularly (not allowing excessive fecal or food buildup), sanitizing containers before andafter stocking, cutting down feedings, and reducing the pathogen load from the watersupply. Unnecessary drug treatments are harmful to fish. I recall a case when trout weresuffering from bacterial gill disease. My manager expected his fish to improve immediatelyafter treatment. It didn't happen. He then impatiently added more of the same drug to thefish. They got worse. The manager then added a different chemical to the water.Each treatment caused an accumulated stress to the fish. When I examined the gills, theylooked like fried chicken livers. Chemical treatments, when given in the water, primarilyaffect gills and skin. Gills respond by producing more mucous and cells. Often drug therapies are applied without knowing if the target bacterium will bekilled. Therefore, it is extremely important to conduct bacterial susceptibility testsprior to therapy. If the target bacterium is insensitive to the drug being used, then fishwill continue to die, and money is flushed down the raceway. Bacterial resistance to adrug will develop when a therapy program is not carried full term. If a drug labelauthorizes treatment for 10 consecutive days, treatment for less time will allow bacteriato develop resistance. Some culturists stop an authorized treatment before its completionbecause the fish look and act better. Even though money can be saved in the short run,this practice is wrong and will likely lead to greater expenditures in the future. If thispractice continues, the drug will eventually become useless as a disease control tool atthe hatchery. This should be especially alarming to growers because of the present lack oflegalized drugs in the fish medicine chest. Legality of therapy is a critically important issue. The U.S. FDA regulates the use offish drugs. The few drugs that have been approved for aquaculture by U.S. FDA are: MS222,Formalin-F, Paracide-F and -S, Romet 30, Sulfamerazine and Terramycin. **HOW TO PROTECT YOUR FISH** Many years ago I visited a hatchery in Oregon. I was bringing them eggs from a publicresearch station. The hatchery manager met me off station. He kindly, but firmly usheredme and eggs to an outside site, checked my identification, and reviewed my egg shipmentpermit. Then he proceeded to surface disinfect the eggs, whereupon he placed them into hisown container, and bid me farewell. I was not even permitted to set foot in his hatchery.This made a lasting impression. The manager understood well how pathogens are spread. Hetook no chances in contaminating his station. He thoroughly acquainted himself withdisease histories from inspections. It was his livelihood. The fish grower should be familiar with the fish pathogens and diseases in his area.Governmental policies should be checked well in advance of importing eggs or fish. Thisknowledge enables us to make informed decisions on which groups of fish to import andwhich to stay away from. **HOW TO NOT SPREAD DISEASE (AND STILL SPREAD GOOD WILL)** Historically, the spread of most pathogens to hatcheries and watersheds has resultedfrom improper sanitation and stocking practices. A senior citizen pathologist onceexplained to me how enteric redmouth was spread into several Western States by one truckcontaining contaminated water and fish. Most fisheries professionals now realize that anygroup of fish may be carrying pathogens. It is not prudent to assume that an empty fishcontainer no longer contains pathogens just because its load of fish has been stocked.Many pathogens are resistant to drying. Placement of the next group of fish into thecontainer may allow further contamination and distribution of the pathogen. Vehicles andequipment must be thoroughly sanitized by following a few rules. Vehicles should be sanitized after hauling and before entering another hatchery byusing 200 ppm active chlorine for 60 minutes. Neutralization of chlorine water can be donewith 2.2 lb sodium thiosulfate/Lb or 1.5 g/liter of 200 ppm chlorine. Wash mud fromexterior of vehicle using high pressure steam. Metal surfaces sensitive to chlorine can besanitized with quaternary ammonia compounds. All sanitation should be followed by copiousrinsing with clean water. Equipment (nets, pumps, sampling utensils, rain gear, boots, sorters) used at one    hatchery (or body of water) should not be taken onto another hatchery (or body of water)    without first being properly sanitized. Afterwards, rinsing with clean water may be    necessary to prevent toxic chemical residues from affecting healthy fish. An excellent    example of the importance of disinfecting comes from a report of spreading the whirling    disease pathogen on shipment containers. Equipment should not be transferred between    raceways without proper sanitation. Wood and Styrofoam items can not be thoroughly    sanitized by immersion in chemicals and should be replaced with metal or plastic.  If your fish have suffered an outbreak of disease, always sanitize concrete raceways    before placing a new batch of fish in them. Sanitation can never be overdone but it can be underdone. Always inspect vehicles andequipment arriving from other hatcheries to assure sanitation. Following sanitation, makesure adequate rinsing of tanks occurs to remove the toxic chemical. Hands should always bewashed well before working in hatchery water at another station. A good rule is trust noone and nothing; your livelihood may be at stake. **Rules ofChemotherapeutic Treatment of Fish Diseases** **By: Terry Ott, La Cross Fish Health Center, La Crosse, WI 54650, 608-783-8444** Fish should be examined to diagnose the disease or problem to be treated. Seekprofessional assistance if in doubt. **A "shotgun" treatment is poorpolicy.** This type of treatment can lead to higher chemical costs and drugresistant microorganisms. Determine species, age, and condition of fish before treatment. Fish may not be able towithstand standard treatments. In this case, it is advisable to sample a small group offish using the approved chemical or provide serial treatments with progressively higherconcentrations of the chemical. Clean the holding unit before chemical treatment. Manychemicals are inactivated by organic materials. A holding unit which is not clean willprovide a sanctuary for the organism under attack. Remove fish from their feeding schedule24 to 48 hours prior to treatment. Oxygen consumption and metabolism is reduced when fishare taken off feed and fish are more apt to withstand the treatment. All leaks in theholding unit should be repaired prior to a static treatment. This rule is important inorder to maintain a constant chemical concentration. Auxiliary aeration devices should be on hand and operative. This rule applies to statictreatments where oxygen depletion is more likely. Determine proper dosage, amount orconcentration of chemical to be used. **Always double check your chemicalcalculations.** Determine the appropriate method and route of application.Determine the approved withdrawal time of the chemical on the species of fish receivingtreatment. Compare economic value of fish with cost of chemical. If cost of chemical used in thetreatment is greater than the economic or resource value of the fish, it may be worthchanging your choice of chemical or even abandoning the treatment. Always check the routeof chemical effluent at the facility. It is possible that the chemical in use may causeenvironmental damage after it leaves the holding unit being treated. Before startingtreatment, visibly check the physical condition of the chemical being used. Some chemicalsare altered when improperly stored or expired. This alteration could yield an ineffectiveor a toxic chemical. Check concentration of the stock chemical. Many treatmentrecommendations are based on active ingredient(s). Dilute the chemical in a containerbefore applying it to the holding unit. This will ensure proper mixing and distribution ofthe chemical in the water column. Observe fish closely during treatment. **NEVER** leave the scene whiletreatment is in progress. If distress is observed in the fish, the treatment should beterminated, or if low dissolved oxygen is the problem, additional aeration should beprovided. Do not stress (by handling, feeding, crowding, etc.) treated fish for 24 to 48hours after treatment. Make every effort to determine the predisposing factor or factorsfor the condition being treated and correct for them if possible. If the predisposingfactor is not removed, it is likely that the condition will reappear. **Pond Culture ofWalleye Fingerlings** **By: L. M. Harding and C. P. Clouse, graduate research assistants, R. C.Summerfelt, professor, and J. E. Morris,** **Extension Fisheries/Aquaculture, Iowa State, University** **The MTAN felt that the following information, although general in nature,would be of benefit to Tribal hatchery workers who may be just beginning their careers incoolwater fish culture. The information may also be helpful for Tribal resource managerswho may need to present a general overview of walleye fish culture practices to youngstudents.** **INTRODUCTION** **The objective of this publication is to introduce basic concepts of walleyeaquaculture, and to summarize briefly the methods most commonly used for rearing walleyefingerlings in ponds. Research is being conducted on methods to rear walleye to food size,but there are no economically viable methods at this time.** Walleye has potential to be an aquaculture species in the North Central Region because: it is native to the region;  it maintains optimum growth at temperatures lower than many other current aquaculture    species (such as channel catfish);  it is a highly-prized sport fish;  its flesh is considered a delicacy; and  the fillets are high in protein and low in fat, making walleye an attractive food    selection for today's health conscious consumer. Currently the highest return on investment for the walleye culturist is in theproduction of l-3 inch fingerlings in culture ponds. Fingerlings can be sold for stockingof farm ponds and both private and public lakes. Research has shown that walleyeintroductions are more successful when fingerlings 2 to 3 inches long are stocked insteadof fry. **BIOLOGY** Walleye are native to most rivers and natural lakes in the North Central Region. Theyhave been introduced (through stocking) into many lakes, and annual maintenance stockingis common. Females will produce about 30,000 eggs per pound of body weight. Spawningoccurs in early spring when water temperatures are 40-50 F. Hatching of the eggs istemperature dependent, but at 44 it occurs in 10 days. At hatching, fry are  to inchlong. They do not begin feeding until the yolk sac is absorbed, which is 5-8 days afterhatching. Walleye are strike feeders that rely on vision to capture their prey. Initially,very small planktonic animals (zooplankton) are the primary prey of the fry. Eventuallylarger prey such as insect larvae become important in the diet. Walleye are cannibals;they will begin eating their siblings when only  inch long. The optimum watertemperature for growth of fingerling walleye is 69 -72. Depending on water temperature,fry can be expected to grow to a length of 1  to 2 inches in 30-55 days. **POND MANAGEMENT** **Even though walleye fingerlings have been raised in outdoor rearing ponds bystate agencies for many years, there is no single culture method that has proven to beoptimum.** Suggested methods are general and are dependent on many variables, including pondtypes, water source, and weather. To date, the most effective fingerling walleye cultureis done in drainable earthen ponds. Ponds may be 1-5 acres in area, 4-10 feet in depth,and have a longitudinal slope of  to 1 foot per 100 feet of length ( to 1 percent).Though harvest will be less efficient in non-drainable ponds, they are usable as long asthere are no other fish in the pond that will prey on fry or fingerlings. If suchpredators exist, they must be removed by chemical means (rotenone), unless the pond isshallow enough to winterkill before fry are stocked. **POND FILLING** Assuming the pond to be used is drainable, it should be dry for at least 24-48 hours tomake sure all gill breathing organisms (competitive fish and amphibians) are dead. Fill the pond 7-14 days prior to fry stocking (shorter time period will suffice if surfacewater is used) so that a good zooplankton population can be established. Without predatoryinsect populations also being established, some aquatic members of the Hemiptera (truebugs) and Coleoptera (beetles) orders are predacious on fish fry. Zooplankton will be theprimary food source for the fry in the early phase of the culture period. Water forfilling the culture pond may originate from a holding reservoir, a well, surface runoff,or other surface water sources like streams. **Filter water from a surface watersource to eliminate all fish eggs and all wild fish that may prey on walleye fry.** Filling procedures vary depending on the water source. Fill well-water ponds ahead ofstocking so an adequate zooplankton population can develop. Several types of simplefilters can be used, with cloth filters being the most common. **FERTILIZATION AND ZOOPLANKTON INOCULATION** One of the most critical factors in pond culture is the available food supply forwalleye fry. Nearly all surface waters naturally contain zooplankton, and, given enoughtime, less fertile waters will be colonized. Because fish usually are cultured at highdensities, zooplankton densities also must be high. Fertilizers are commonly added to fishculture ponds to increase zooplankton numbers by increasing zooplankton food - organicmaterial, bacteria, and algae. Many different types, kinds, application rates, andapplication schedules for fertilizers are available. There seems to be little indicationof an optimal treatment, and success can be highly variable. **Fertilizers are classified into two types:** Inorganic fertilizers (such as 10-35-0) are chemical compounds. The grade of a    fertilizer refers to percentages by weight of nitrogen, phosphorus, and potassium. These    nutrients stimulate algal growth.  Organic fertilizers are plant and animal materials - alfalfa, soybean meal, bone meal,    and manures. Organic fertilizers can provide food for the fish by stimulating algal growth, as doinorganic fertilizers. However, zooplankton can feed directly upon organic fertilizers aswell as bacteria and protozoa, which are also food for zooplankton. Organic fertilizershave been commonly used for walleye culture throughout the North Central Region becausealgal growth is usually slow at low temperatures. **Depleted oxygen, high ammonia,and variable pH levels may be lethal to walleye.** Organic fertilizers may increase oxygen demands on the system, and manures may increaseammonia levels. Ponds with intense "blooms" of algae may exhibit low dissolvedoxygen (DO) in the morning (less than 2 ppm) and high pH levels in the afternoon. At pH of8, water temperature of 68, and total ammonia nitrogen (TAN) of 0.5 ppm, walleyefingerling growth will be reduced. Fingerlings will be killed at 5.0 ppm TAN. If pH levelsor water temperature increase, a lower concentration of TAN will be toxic to fish.Consider such water quality parameters prior to selecting a fertilizer; measure waterquality parameters at regular intervals following fertilizer application. To determine fertilizer application rates and schedules, monitor zooplanktonpopulations. Common application rates of alfalfa hay or pellets in drainable ponds in theNorth Central Region are 500-1500 lb. per surface acre applied in 3-5 portions over the4-6 week culture period (150-300 lb. per week). However, a particular regime must bedetermined for each setting. Fertilizer applications in walleye culture ponds (in contrastto some fertilizer regimes used in Southern areas), are not determined by watertemperature. If the culturist waits for the water temperature to reach 70, as recommendedin the southern region, the walleye culture season could be over before fertilizationtakes place. Zooplankton inoculation is another method whereby zooplankton populations can bemanaged. The purpose of inoculation is to seed the system so an adequate density ofzooplankton is available to the walleye throughout the culture period. The inoculum (alarge number of desirable zooplankters) is usually collected and concentrated from anearby water source that is without fish but rich in zooplankton. Inoculation can be veryimportant in systems using well water or in plastic-lined ponds, or where zooplanktonpopulations have crashed. In nutrient-rich waters, or where the ponds are filled fromsurface water sources, the value of zooplankton inoculation may be limited. **WATER QUALITY** Pond culturists must monitor the water quality in their ponds throughout the cultureperiod. Water chemistry is complex and most variables are temperature and pH dependent.Monitor all major parameters, including dissolved oxygen (DO), temperature, pH,alkalinity, and ammonia. **AQUATIC VEGETATION CONTROL** As in other forms of agriculture, undesirable forms of vegetation may pose a problem tosuccessful fish culture. This is especially true in nutrient rich, fertilized waters.Types of vegetation that may be present in ponds are algae, and submergent, emergent, andfloating aquatic vascular plants. At low levels, vegetation is normally not a problem, butwhen abundant it can sometimes cause low dissolved oxygen at sunrise, or it cansignificantly interfere with harvest. The control of established aquatic vegetation mayresult in initial low dissolved oxygen associated with decaying vegetation, or decreasedzooplankton population levels. Vegetation control may be accomplished using a pre-fillingtreatment of the pond bottom with recommended herbicides or by treating problem vegetationafter it develops; in either case, it is preferable to avoid excess vegetation. **ZOOPLANKTON AND BENTHOS MONITORING** Take zooplankton and benthic (bottom material) samples weekly to ensure that there isan adequate food supply available to the walleye. Important food items throughout thepond's entire depth include zooplankton (copepod and cladoceran "water fleas")and Chironomids (midge larvae or blood worm) usually found on the pond bottom. Zooplanktoncan be sampled by towing a fine mesh plankton net (80 u mesh opening) a known distancethrough the water column. Other methods, e.g. tube samplers and pumps, may be used tocollect zooplankton samples. Night sampling of zooplankton is most reliable because mostzooplankton species migrate to the upper pond layers at night; but samples taken duringperiods of relatively low light should be adequate to assess the zooplankton population. Classify and count the zooplankton samples to determine composition and density. Nominimum density required for pond culture of walleye fingerlings has been established, buta general guideline is that no less than 800 large-bodied (e.g. copepod and cladoceran)zooplankton per gallon should suffice. If zooplankton cannot be counted, hold up a clearcontainer filled with pond water; a large number of these animals should be seen movingabout with characteristic jerky movements. The naked eye should be able to see the outlineof these animals. A grab sample of the bottom (via a dredge or by hand) should yield some chironomids.There are no set guidelines for desired chironomid populations, but these benthicorganisms can be a valuable food source to fingerling walleye, especially near the end ofthe culture period when zooplankton populations may have been depleted and fingerlingsrequire more energy. **FISH MANAGEMENT** A critical component of walleye pond culture is the quality of fry. Finding a reliablesource of good and healthy fry is essential. Fry are usually received in a plastic bagpartly filled with water and pure oxygen. Fry should be at least two days old (post hatch)before stocking, but not more than five days old. **After receiving the fry, comparepond temperatures and the temperature of the water in the bag. The fry should betemperature acclimated one-half hour for each 2 temperature difference between bag waterand pond.** This can be done by placing the bag into the pond and allowing the bag watertemperature to become equal to that of the pond. Once fry are acclimated, cut open theplastic bag and gradually move it back and forth in the water until the fry are dispersed.Take care to place the fry on the leeward (up wind) side of the pond so they will not bewashed ashore. Optimal fry stocking densities are dependent upon productivity levels ofthe water, the pond configuration, soil organic content, and fertilization regimes.Conservative recommendations on stocking densities range from 20,000 to 30,000 peracre-foot (1 surface acre 1 foot deep). In extremely productive waters with experiencedmanagement, stocking rates as high as 50,000 per acre foot have been successful. Highstocking densities may lead to strong competition for available food supplies resulting inhigh numbers of small fish. Lower stocking densities may reduce competition and maximizethe size of fish produced. Production goals must be considered prior to stocking. Two to three weeks after stocking the fry, collect fish to monitor progress. Small,soft mesh seines (1/16 to inch, "ace" type) work well at this time. Measure andweigh 10 to 20 fish, and examine stomachs for prey types being consumed and evidence ofcannibalism. After 4-8 weeks of normal growing conditions, walleye fingerlings should be ready toharvest. The exact size or age at which to harvest fingerlings is often determined by foodavailability, fish condition, draining restrictions, and market demands. If the fish arein good condition, an adequate food source is present, and there is no significantcannibalism, they can be left in the pond until they are approximately 2 inches long.Once the fish reach 1 to 2 inches in length, culture conditions may begin to decline(e.g. decreased prey populations or increased cannibalism), and the fish should beharvested at this time. If conditions decline prior to fish reaching the desired size, tryfertilization or zooplankton inoculation. If that does not work, then begin harvest assoon as possible. In poor culture conditions, both walleye fitness and survival rates candecline rapidly. **HARVEST TECHNIQUES** It is crucial that harvest of fingerlings be conducted efficiently. Drainable pondswith concrete catch basins (collecting basins at drain outlets) have many advantages forharvesting fingerlings. In the catch basin, fingerlings can be dip netted out and placedinto portable tanks for transportation. If the pond is not drainable, fingerlings can becaptured in fish traps (fyke nets) or seined. Appropriate fyke net construction consistsof to  inch "ace" type mesh. Seine construction for harvesting 2-inch fishconsists of inch "ace" or "king" type mesh. When fish are 2 to 3inches long, use  inch mesh of #9 twine size. By early fall, when fish are 5 to 7 incheslong, use  inch mesh and #15 to #21 twine size. Successive attempts may be needed toassure a large percentage of the fish are harvested. None of these methods will be asefficient as pond draining. **Stress at harvest must be kept to a minimum to ensuredelivery of healthy fingerlings.** Stress may be associated with crowding, handling, and environmental extremes, e.g., lowdissolved oxygen, high ammonia levels, and high temperatures. As the fingerlings are beingharvested, the culturist must ensure that an adequate supply of well-oxygenated cleanwater is present for the fish during harvesting. Do not harvest walleye when watertemperature exceeds 75; less than 70 is better. All of the other management measures areuseless if the fish are stressed and die at harvest or later due to subsequent diseases.Do not hold walleye less than 2-inches long for more than 3 days in holding tanks orstarvation may begin. At harvest, weigh the fish and take three or four sample counts from each pond todetermine total number and size of the fish harvested. Size of fingerlings is usuallypresented as the number of fish per pound. Though determination of harvest success isoften based on percent return, fish condition and total pounds of fish produced are alsoimportant. **MARKETS** **Find a market before it is time to harvest fish. Markets are available, butthey usually must be cultured as carefully as the fish.** The culturist has the option of either selling the fingerlings or attempting to raisethem to food size. One of the best market choices is to sell fingerlings to individuals orsporting clubs for sport fish stocking purposes. Techniques and facilities to trainpond-raised walleye to formulated feeds are being investigated in current research. **WaterQuality Test Methods for Aquaculture** **By: Margaret L. Phillips, Market Manager, LaMotte Company, P.O. Box 329,Chestertown, MD 21620, 800-344-3100** A variety of test procedures and methods are available for use by the aquaculturalist.They run the gamut from colorimetric, titrimetric, electrometric (meter and probe),turbidimetric and nephelometric methods. Often, more than one of these methods can be usedto measure a single parameter. For example, dissolved oxygen may be measured by atitrimetric test or by a meter and probe. What is the best method for your operation? Herewe will review the first three methods as they are the most common in aquacultureoperations. First, let's define these methods, give examples, learn the limitations, andthen decide what method is best suited for your needs. The key issue is to decide upon theprocedure and equipment that best meets your requirements for: cost, both initial and cost per test  skill level of operator  accuracy, repeatability and portability  decision-making information obtained Remember, the information obtained from your testing will be the decision making toolto monitor your system and make any operational changes that may be required. **COLORIMETRIC METHODS** Colorimetric methods are defined as the measurement of a parameter where itsconcentration is directly proportional to color development and intensity after theaddition of a known volume of chemical reagents to a specific sample size. In some cases,like the DPD chlorine test, the reaction is almost immediate. Other tests like ammonia andnitrite may require a waiting period of 5 minutes or more before full color development isreached due to the chemistry involved. To determine the concentration, the color developed in the sample is either comparedvisually with standards supplied by the test kit manufacturer or inserted into acolorimeter or spectrophotometer to give results directly on a scale or digital readout.The results are expressed as ppm (parts per million) or mg/l (milligrams per liter). Thereare some limitations to visual comparators: There may be individual differences in one's ability to discern color intensity. Color    blindness is a problem.  Background lighting can affect reading. Most test kit manufacturers formulate color    standards using natural daylight. Night readings, incandescent, or fluorescent light may    produce errors. Even with the limitations described above, visual color comparison methods areinexpensive, generally easy to use, conveniently packaged, and are designed forsimplicity. Colorimetric analysis using a colorimeter or spectrophotometer offer someadvantages and disadvantages. Many meters are battery powered and conveniently packagedfor portability. Briefly, they operate as follows. A light beam is passed through thesample; depending upon the amount of color present, light is transmitted through thesample and detected by a photodiode; with aid of electronics, the results are displayed onthe meter, either directly in concentration or as a percentage of light transmitted. **Advantages of instrumentation are:** elimination of the need for visual interpretation  elimination of the concern for background lighting  ultimate greater accuracy **Disadvantages are:** high initial start up costs for the unit  greater degree of maintenance and care required  may be overkill for small operations Colorimetric tests offer an opportunity to provide on-the-spot test results and havethe capability to test for a variety of critical factors such as ammonia nitrogen, nitritenitrogen, copper, nitrate nitrogen and others. Weigh the advantages, disadvantages andoverall equipment lines before making a decision about what type to use. **TITRIMETRIC METHODS** With a titrametric method, a sample is taken and specific reagents are added to producea color. Depending upon the reagent system, the sample may often require pH adjustment orbuffering for the reaction to occur. The indicator reagent produces the color. A titrantor reacting reagent is added drop by drop until a color change occurs. The point at whichthe color changes is called the endpoint. Titrametric methods offer a number of titrantdispensing equipment. Drop Count where a calibrated dropper pipet or plug dispenses drops of equal size. The    number of drops added to produce the endpoint are counted and multiplied by a conversion    factor to obtain the results in ppm.  Direct Reading Titrator where a calibrated micro buret dispenses the titrant until the    endpoint is reached. Results are usually read directly off the calibrated scale in ppm    without need of conversion.  Digital Titrator where titrant from a cartridge is inserted into a microdispensing    device. The amount dispensed is read on a digital readout, usually in ppm.  Automatic/Laboratory Burets are usually larger in scale and are best suited for bench    top situations. Titration methods are generally quite inexpensive and are the preferred method for manytest factors, such as alkalinity, hardness, and dissolved oxygen. Here too, convenientpackaging and simplicity are the key to their portability. **ELECTROMETRIC METHODS** Here, an electrode is inserted into a sample, and a small current/voltage is producedand electronically amplified and read on a meter scale, analog or digital. Typical testshere are pH and dissolved oxygen, but a variety of parameters using ion specificelectrodes (ISE's) can be measured, including nitrates, ammonia, chlorine. Nearly every electrometric procedure requires meter calibration and/or samplepretreatment, such as dissolved oxygen meter calibration. The manufacturer recommends aparticular procedure for this. Generally, electrometric methods are more costly initiallyand require a greater degree of care and maintenance due to the electrode system. Today, pH and dissolved oxygen meters are available covering a wide range of prices. Asyour operation expands, you may want to consider a DO meter as they do save considerabletime over titration methods. Keep in mind the costs and care of the unit involved. **TESTING GUIDELINES** Remember, one of the most important requirements in developing a water quality testingprogram is record keeping. Develop a testing schedule.  Keep records. Historical data is extremely important if treatments are required. Note    environmental conditions, fish activity, peculiar behavior, etc. Remember, each test    result is just a snapshot of what is going on in the system at that time.  Look for trends or sudden changes in each factor, as they may be a clue to perform    further analysis. All the tests described above require a proper sample and technique for the mostaccurate results: Follow the manufacturer's directions specifically! Do not alter the test procedure to    suit your needs or take shortcuts risking skewed results. With a new procedure, walk    through the test without using the reagents as a "dry " run to familiarize    yourself with the equipment. If you have questions, call the manufacturer - don't second guess as results may beskewed. This includes safety information regarding the chemical reagents. Remember, you are    working with chemicals that may be hazardous in nature. Follow all recommendations. Store    all test kits and reagents out of the reach of children. Storage out of direct sunlight    and at room temperature is preferred unless specified.  Replace reagents on a regular schedule according to the manufacturer's recommendations.  Do not mix reagents of different manufacturers unless you are sure they are of the exact    same formulation. Briefly, we have reviewed three water test methods for use in aquaculture applications.Which one is right for you? Make a list of the test factors most critical to your operation.  What accuracy is required?  Choose the test method that best suits the operator's skill level.  Review the test method cost versus expected results.  Look to the marketplace for manufacturers and suppliers of test equipment and kits.    Review their products. **Effluents FromCoolwater Fish Ponds Commercial Fisheries NewslineVol. XV, No.1 January 1996** **Submitted to the MTAN by:  Greg Fischer - Red Cliff, and Mike Donofrio -Keweenaw Bay Tribal Hatcheries,** **Source: Wisconsin Aquaculture Update-Fall 95** Carla Rivera recently completed a research project under the joint direction of JeffMalison and John Magnuson at the University of Wisconsin-Madison. Rivera characterized thequality of effluents discharged from fertilized fingerling ponds, and assessed theecological impact of these effluents on the receiving stream. Her research was innovativein two respects. First, although pond effluents have been fairly well characterized in thewarmwater catfish ponds of the southern United States, until this study, effluents had notbeen described in coolwater fish ponds. Second, previous effluent studies had beenconducted on intensively-fed grow-out ponds, whereas Rivera's studies examined theeffluents from fingerling production ponds that had been heavily fertilized to encouragephyto- and zooplankton growth, but in which the fish were not fed a pelleted diet. The water quality of effluents coming from aquaculture ponds is, justifiably, of greatconcern to a variety of groups, including adjacent property owners and environmentalists.The research site chosen for Rivera's study was the Wisconsin Department of NaturalResources (DNR) Lake Mills Fish Hatchery in Lake Mills, WI. The study was conducted inconjunction with the DNR's annual walleye and northern pike fingerling production forsouthern district lakes. Early each spring the ponds at the hatchery are filled with waterfrom nearby Rock Lake, fertilized with hay and drained about eight weeks later to harvestthe fish. During 1994, Rivera took water samples from a total of 14 ponds during harvest;seven of these ponds had been renovated in 1992, the others were 40-50 years old. As theponds were draining, water samples were obtained at five different times to determine thenutrient levels of the discharge waters. When the samples were brought back to thelaboratory, Rivera measured several different water quality parameters includingtemperature, dissolved oxygen, nitrogen and phosphorus levels. The second part of the project was to evaluate the effects of the pond harvesteffluents on Rock Creek, a small stream that flows out of Rock Lake, through the hatchery,and eventually into the Rock River. Both the water quality and the biological communitiesof the stream were evaluated in the late spring, during the June harvest period, and againin the late summer. Three different sampling sites were chosen: upstream from thehatchery, adjacent to, and just downstream from the fish hatchery. **Riveraconcluded that the levels of most measured parameters increased significantly only in thelast 10-15 percent of the water drained from the ponds.** She suggests that a simple management strategy to reduce or even eliminate thepollution to the receiving waterway would be to direct the last 15 percent of the effluentwater to settling or sedimentation ponds. The final sludge could be used as a fertilizerfor many types of agricultural activities. The settling ponds could also be used forcropping species such as rice, which are adapted to similar environmental conditions. **Anotherinteresting finding from Rivera's work was that the effluents from fertilized fingerlingproduction ponds did not pose a serious pollution threat to the natural waters.** Very few of the pollutants measured in the stream were at higher levels than thosenormally found in undisturbed streams. In fact, she found that hatchery effluents had anet positive effect on the stream due to the increased water flow, a possible outcome notoften recognized but of great importance to the aquaculture industry. The minor impacts ofthe harvest effluents were concentrated in the area immediately next to the hatchery.However, due to the stream's capacity to regenerate at the increased flow rates, thebiotic communities downstream from the hatchery were restored to a more diverse state thanbefore. **Hatchery Tip** Thanks to the help of Bob Jackson (BIA) and the Native American Fish and WildlifeSociety, the MTAN was able to organize and schedule a coolwater fish culture course forTribal fish hatchery employees. The course was given in February and focused on spawning,pond preparation and rearing of walleye and northern pike. Another area of Tribaltechnical assistance the MTAN was able to participate in was the transfer of another fishdistribution truck to a Tribal fish hatchery program. This particular unit came from theJordan River/Pendills Creek National Fish Hatcheries. The truck and tank combination willbe transferred to the Red Cliff Band of Lake Superior Chippewa Indians and will be used toship both brook trout and walleye fingerlings. **The MTAN wanted to remind all our Tribal hatchery readers that in order for us    to know how to best serve your needs, we first need to hear from you. If you are aware of    additional training needed for your employees, or need to locate hard to find hatchery    equipment, or just want to suggest topics of interest you would like to read in a future    issue of the MTAN, please make Beth or Frank aware of your concerns.**     Product and company names mentioned in this publication are for informational          purposes only. It does not imply endorsement by the MTAN or the U.S. Government.    Return to MTAN    selection page    Return to Ashland NFWCO home    page    Return to Region 3 U.S. Fish and Wildlife Service
 
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