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Ashland NFWCO
 Midwest Region
 mtanlogo.gif (9794 bytes) Dedicated To TheTribal Aquaculture Program June 1994 -        Volume 8
 http://www.fws.gov/midwest/ashland/mtanhome.html **Administrative        Coordinator:**        **Frank G. Stone        (715-682-6185) Ext.12        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: Application    Process for an Environmental Protection Agency Permit To Use MS-222 Proper    Storage and Handling of Fish FeedsGreat    Lakes Fish Disease Control PolicyAn    on Site Mini Hatchery System for WalleyeCommon-Sense    Rules for Research RecordkeepingInfluence    of Stocking Densities on Walleye Fry Viability in Experimental and    Production TanksDetecting    Swim Bladder Inflation in Fingerling WalleyesHydrogen    Peroxide Controls Fungal Infections On Trout EggsProduct    Manufacturers   Application Process for an Environmental Protection AgencyPermit To Use MS-222By: Mike Donofrio, Keweenaw Bay Tribal Biologist, Keweenaw Bay IndianCommunity  Tricaine Methane Sulfonate (MS-222) isused as a fish anesthetic in hatcheries. We will use MS-222 to anesthetize our lake troutyearlings for the fin clipping and microtagging process. The Food and Drug Administrationhas approved MS-222 for use on food fishes. MS-222 is restricted to a level of 15 to 330PPM and fish must not be used, for food purposes, within 21 days following the anesthetictreatment.  However, you must obtain a permit from the Environmental ProtectionAgency (EPA) to discharge this chemical with your effluent. EPA permits are issuedthrough the regional office in Chicago, IL. We sent a letter describing the product, itsproposed use, and product label to: Claudia Johnson-Schultz, Indian Programs Coordinator,Water Division, EPA W-15J, 77 West Jackson Blvd. Chicago, IL 60604-3590. We also sent acopy of the request to Mary Ann Starus, Michigan Tribal Environmental Liaison. There isalso a Tribal Environmental Liaison for Minnesota and Wisconsin. Ms. Starus wasinstrumental in making direct contact with a telephone call to the Regional office. You shouldn't expect to receive a timely reply from EPA since they areunderstaffed. I recommend you apply for this permit a year in advance and use your TribalEnvironmental Liaison to expedite the permit process. Proper Storage and Handling of FishFeedsBy: Terrence Ott , U.S. Fish and Wildlife Service, La Crosse Fish HealthCenter, La Crosse, WI 608-781-6238  One of the main ingredients in raisingand producing healthy fish for the resource or as table fare is the quality of feeds youput into your fish. Quality fish feeds are just as important at your hatchery as thequality of water you use to raise your fish in. Without providing your fish a properly balanced diet, growth will beabnormal, food conversion will be low, and health of your fish will be at stake.Malnourished fish cannot remain healthy and grow properly to produce the next generationof fish with an improper diet. Feeding your fish on a daily basis can become and often does a routinepractice at your hatchery. Routine experiences can lead to ignoring or skipping manycommon rules in the proper storage, handling, and feeding of your fish. Proper handlingand storage procedures must be followed to protect the quality of the feed you purchasefrom the manufacturer. If proper storage conditions are not met, fish feed with their highlevels of proteins, fats, and vitamins will rapidly spoil. These high levels must bemaintained in order to meet the nutritional requirements your fish need to grow andreproduce. The formulated fish feeds you use at your hatchery are soft and fragileand care must be expended in their handling to reduce breakage of the pellets. Brokenpellets result in dust, and small particles which feed manufacturers describe as"fines" in your feeding operation. Fines that exceed 3.0 percent are notconsumed by your fish and can increase feed conversions, result in poor water quality,create suitable habitat for fish pathogens, and cause environmental gill disease. Toeliminate or keep to a minimum the fines in your feeding operation follow these four easysteps; Don't walk or stand on bags of feed.  Don't throw or drop bags of feed onto hard    surfaces.  Don't forcibly stack bags of feed.  Don't stack bags of feed over 10 high. Proper storage of fish feeds at your hatchery depends if the feed youreceive is dry, semi-moist, or moist. Dry feeds or semi-moist feeds do not requirerefrigeration. Ideal conditions for storing these types of feeds involve stacking the feedbags on wooden pellets so the bags are 3 to 4 inches off the floor. Keep the stacks in acool, dry storage area where relative humidity is below 75 percent. Humid conditions canlead to insect infestations and moldy feed. It is also important to set feed stacks apartin order to provide air circulation and rodent control. Moist pellets should be stackedsimilar and stored in a freezer at temperatures below 0EF, until you are ready to feed your fish. Then thaw only the requiredamount to feed your fish at that time. Never leave a pail of feed sitting out next to a raceway during warm days.Excessive heat can quickly turn that pail of quality feed into a costly supply offertilizer for your garden by a process called, "oxidation". Oxidation willdestroy the vitamins in the feed and turn the feed rancid. Rancid feed can be toxic toyour fish, and will produce an undesirable flavor in fish eating the feed. Off-flavor ofthe feed can also occur due to the spoilage of the proteins and fats in the feed. Rancidfeed can taste poorly to the fish, making them eat less and waste more. This can result inan accumulation of feed material on the bottom of the raceway, providing excellent habitatfor fish pathogens to hide in and multiply. Recommended maximum storage time for feeds is 90 days from the time ofmanufacturer, not from the time the feed arrives at your hatchery. Bags of feed which haveexceeded the recommended shelf life or do not have a readable manufacturing date stampedon them should not be fed, or even purchased. Also any feed that appears abnormal(excessive fines, moldy, off-colors and odors) should not be given to your fish. If these rules for the proper handling and storage of fish feeds are notmet at your hatchery, you could be jeopardizing the health of your fish and your fisheryprogram.  GreatLakes Fish Disease Control Policy Special Publication 93-1By: Great Lakes, Fishery Commission, 2100 Commonwealth Blvd. Suite 209,Ann Arbor, MI 48105, 313-741-2077 The MTAN sincerely believes thatevery Tribal hatchery should adopt an aggressive fish disease prevention and monitoringprogram. This is especially important for all salmonid fish hatchery facilities. The MTANalso encourages you to become actively involved in the Great Lakes Fish Disease ControlCommittee. If you are not aware of the goals of the Committee, the following informationmay help you to better understand the management role they have in the Great Lakes fisheryprogram.  The Great Lakes Fish Disease ControlCommittee (Committee) was established by the Great Lakes Fishery Commission (GLFC) in 1973to recommend measures to protect the health of cultured and wild-fish populations in theGreat Lakes basin. The Committee is comprised of representatives from state, provincial,and federal agencies involved with Great Lakes fishes and from private aquaculturalinterests. Decisions are made by a consensus of the membership. In 1985, the Committeedeveloped a "Model Program" for controlling fish diseases in the basin. ThisModel Program was subsequently adopted as a policy of the GLFC. Increasing national and international interest in importation of salmonidfishes for fisheries management and aquacultural purposes, and the damage caused bydisease introductions indicated that expanded guidelines were needed to protect the healthof salmonid fish stocks within the Great Lakes basin. Consequently, the Committeerecommended at first a ban on importation's of salmonid fishes from regions where diseaseswere enzootic. For example, importation's were banned from the U.S. and Canada west of theContinental Divide, areas where infectious hematopoietic necrosis virus (IHN) and theparasite Ceratomyxa shasta,neither of which are known to occur in the GreatLakes basin, are found. Fish disease control in the Great Lakes basin is the responsibility ofthose agencies that manage the fisheries resources. The Model Program as established bythe Committee, sets forth the essential requirements for the prevention and control ofserious infectious diseases, and includes a system for inspecting and classifying fishhatcheries as well as the technical procedures to be used during these evaluations. ***The Committee does not seek fish-disease control authority.*** The recommendations they propose are provided as an aid to the memberagencies in the development of legislation and regulations. The Committee seeks the adviceand counsel of these agencies in the continuing development of fish-disease controlprograms to assure that such programs are in the best interests of the fishery resourcesof the Great Lakes.  CONTROL POLICY Efficient propagation of fish may be severely affected by the occurrenceof fish diseases. Disease outbreaks have caused serious losses in fish hatcheries andpotential exists for such losses in feral Great Lakes fish populations. Disease problemshave resulted in reduced survival of stocked fish, production cost increases of 20%-30% ormore, significant losses of fish to the public, and diminished economic returns to GreatLakes communities. The policy of the Great Lakes FDCC encourages each agency to work towardthe control of fish diseases in the Great Lakes basin by: Developing legislative authority and    regulations to allow control and possible eradication of fish diseases.  Preventing the release of seriously infected    fish.  Discouraging the rearing of diseased fish.  Preventing the importation into the Great Lakes    basin of disease infected fish.  Preventing the transfer within the Great Lakes    basin of fish infected with restricted diseases.  Eradicating fish diseases, where practicable. The Great Lakes FDCC will strive to coordinate the fish disease controlprogram of the agencies. To this end, the FDCC endorses and supports the Great Lakes FishDisease Control Policy and Model Program as a guide for agency program development.  An on Site MiniHatchery System for WalleyeBy: Lee Newman, U.S. Fish and Wildlife Service, Ashland Fishery ResourcesOffice Ashland, WI 715-682-6185  The Grand Portage Natural ResourcesDepartment and the Ashland Fishery Resources Office identified a problem limiting thewalleye fishery on the Pigeon River. That problem was that walleye recruitment was veryerratic and limited, probably due to poor hatch and rearing characteristics of the river. Stocking hatchery fish from outside sources was considered but rejectedbecause of concerns about disease introductions through transported fish and because ofconcerns for damaging the genetic makeup of the native stock. Assuming that the idealsystem would be to use eggs from native Pigeon River walleye and to rear them on site, wetested whether this could be done economically. During assessment work on the spawning run in 1993, we collected andfertilized about three quarts of walleye eggs on the Pigeon River. We placed the eggs in aBig Redd in the basement of the Grand Portage Tribal Office for development. An estimatedtotal of 100,000 fry were hatched. About 20,000 of the fry were immediately stocked in thePigeon River and the remaining 80,000 were introduced into a small natural pond forrearing. The fry were allowed to feed on natural food in the pond for about 5weeks. At the end of that period the pond was allowed to empty directly into the PigeonRiver. No attempt was made to count the number of fry produced in the pond, but many 1.0to 1.4 inch fry were observed as the pond was emptied. We suspect that survival was good. Total cost for materials for this project was very low, the Big Redd wasborrowed and other materials needed cost about $50. Approximately 55 man-hours of laborwere required. Operation of the Big Redd requires only a dependable supply of well waterand 110 volt electrical power. It appears at this point that the on site, mini-hatchery, might prove tobe both an economical system for producing small numbers of walleye and, a system whichcould provide important benefits in terms of eliminating some of the problems associatedwith stocking transported fish. In 1994, Grand Portage will construct a wetlands project that willincorporate a drainable natural pond for rearing walleye and an intensive culture pond.These ponds and the mini hatchery system should produce all of the walleye needed forstocking on reservation.  Common-Sense Rulesfor Research RecordkeepingBy: Jean Lang, University-Industry Research Program, University ofWisconsin-Madison - originally printed in Touchstone, August 1990 If one thing can be guaranteedabout cool water fish culture, it's that the fish culture practices used during one seasonwill not always guarantee the same results the very next year. Despite how hard you workat it, or how consistent you try to maintain your fish culture practices, the nature ofthe business will often give you varying degrees of success. One of the best solutions tothis problem is to record everything you do during the rearing process. This would includethe quantities, frequency, duration, time of day and dates, which you conduct any fishculture practice. This "Diary" of your stations operations is especiallyimportant for newly activated fish hatcheries, or even for well established facilitieswhich have recently incorporated a new rearing system. If detailed records areconsistently maintained, the result will be a much easier time for your employees toremember all the fine details which will be needed to repeat the successes from theprevious year. If problems occurred during the rearing season, the station diary will alsoenable you to review last years activities and attempt to determine how to avoid repeatingprevious mistakes.  The MTAN thought that the following article (edited to conserve space)would help our readers to better appreciate how to best document their stations fishculture activities. Although some of the material may not be relevant to your program, itdoes help to illustrate how detailed your field notes should be. This article wasdistributed by Peggy Ross, University-Industry Research Program, 1215 WARF Bldg., 610Walnut St., University of Wisconsin-Madison, Madison WI. The MTAN would also like toexpress our thanks to Chuck McCuddy (BIA-Ashland WI) who brought this article to ourattention  Any researcher's success in obtaininga patent these days may depend as much on how carefully he or she has kept a researchnotebook as on how original and patentable the discovery is. University researchers generally do not feel the need to follow the strictnotebook-keeping practices of their industrial colleagues. They should, nevertheless, takea few common-sense steps to protect themselves and their work. These practices can notonly back up patent claims, but also insure against loss of valuable data, provide proofof fulfillment of contracts, and protect against allegations of conflict of interest orresearch fraud.  Standard Practice The basic mechanics of keeping a notebook are familiar but bear repeating: Research should be recorded in a bound    notebook.  Every page should be numbered and dated. It is    best to begin each new day's work on a new page.  Use pen, not pencil, and if possible, use the    same pen throughout the day. This helps support the case that an entry was made all at the    same time and not altered later.  If there is need to correct an old data entry,    you may return to a previous page, but the change must be easily identified as separate    from the original and must be dated.  Notebooks represent months of work. If for no    other reason, they should be locked up at the end of the day in a fireproof cabinet.  A Record of Thoughts and Data A good research notebook is a diary, not a memoir. It reports things asthey happen, not as they are recalled. It is also like a diary in that it reports what youare thinking in addition to what you are doing. This means writing out aneasy-to-read summary of your ideas, why you are planning a particular experiment, whatmaterials and processes you will use, and what you hope to find out. Too many notebooks are simply static data repositories with no hint of theevolving thoughts that are driving the research. A researcher can spend months onexperiments that have the makings of a new discovery, or that reduce a concept topractice. But if that researcher's notebook fails to indicate any awareness of thepotential, that person may have a hard time later answering challenges to the ownership ofthe ultimate discovery. If you don't state your mental constructs as you go along, thesupporting evidence may not be there. The theoretical description can be as simple as writing, "I thinkfactor X is controlling response of Y by blocking position Z on the enzyme. I will begintesting that today with the following series of experiments." A week later, an entrymight read, "Today I've had second thoughts about this theory for thesereasons," and list them. The point is to state your ideas clearly enough that someonecan pick up your notebook years later and understand what you were thinking as well asdoing on a particular date. Scientists who learn to regularly summarize their findings in words aswell as numbers generally find that their notebooks become more useful to them asreferences. An articulate notebook helps to maintain workplace continuity when a long-termproject is passed from one laboratory assistant to another, and it also makes the processof witnessing and archiving data much more efficient.  Reviewing and Archiving To verify the legitimacy of data, especially for patent purposes,notebooks should be witnessed on a regular basis by an impartial party. The idealarrangement occurs when two colleagues who understand, but do not participate in, eachother's work, can review each other's work in confidence. Together reviewers go throughtheir respective notebooks and discuss the recent work. If your reviewer finds a sectionunclear, you make an entry to that effect on the current day's page and proceed to clarifyit in writing to the reviewer's satisfaction. Then the reviewer writes that he or she hasread and discussed in confidence the work of pages X to Y on Z date, and signs off.  Electronic Notebooks Some scientists today keep their research records on computer. Theserecords may be validly archived by copying them onto disc or tape that is then held in asafe location. If electronic records are to be the only record, then it is advisable tohave a "time stamping" program that automatically dates an entry into the systemand would detect any late entries into already complete work. Whether in notebooks or oncomputer, records should be kept for as long as the researcher wants to be able to verifythe legitimacy of his or her work. If the scientist has applied for a patent, the recordsshould be kept for the 17-year life of the patent plus an additional 10 years. In summary, researchers should make their notebooks into real diaries oftheir thinking processes. This is the greatest failing of most notebooks. Many scientistsdon't realize the importance of recording their speculations and daydreams or of notingdown where they got an idea. The other major failing is that notebooks are notunderstandable to others. To determine whether your current system of note-taking is okay,try to review one of your ten-year-old notebooks. If you have trouble reading your ownmaterial, then you'd better change your approach. Finally, it is very important to have adisinterested party review and archive sequential copies of data. Influence of Stocking Densities on Walleye Fry Viabilityin Experimental and Production TanksBy: Alan Moore and Margaret A. Prange, Iowa Department of NaturalResources, Rathbun State Fish Hatchery RR 2, Moravia, Iowa 52781 and Brian T. Bristow andRobert C. Summerfelt Department of Animal EcologyIowa State University Ames, Iowa 50011  The main constraints to development ofa production scale system for intensive culture of larval walleye have been low incidenceof gas bladder inflation (GBI) and poor survival. Noninflation of the gas bladder (NGB)has been a critical factor in most attempts to rear larval walleye. Walleyes withoutinflated gas bladders are of little value to fishery managers because without an inflatedswim bladder a fish has little chance for long term survival. Noninflation of the gasbladder in walleye is considered to be due to a surface tension-oil film barrierpreventing small larva from penetrating the surface film for the initial intake ofatmospheric gas. Noninflation of the gas bladder, however, has been a problem in live feedexperiments and has been observed in pond-cultured fingerlings as well. An oil film is notthe only obstacle to successful gas bladder inflation: larval walleye need a cleansurface to inflate their gas bladders because, when air is gulped from the surface andforced into the swim bladder, feed and bacteria may also enter. Surface sprays have been shown to increase gas bladder inflation in larvalwalleye reared intensively. In 1991, at both the Rathbun Hatchery (Moravia, IA) and atIowa State University (Ames, IA), vertical (Rathbun) and horizontal (ISU) surface sprayswere used to disrupt surface films and to create turbulence on the water surface ofwalleye rearing tanks. Walleye reared in these experiments had gas bladder inflationpercentages ranging from 71.5 to 100 (mean of 89) at Rathbun, and from 18.3 to 82 (mean of45) at Iowa State. After sprays were used at Iowa State University and Rathbun Hatchery,GBI averaged 83.3% in tanks with surface spray, but only 38.8% in experiments conductedwithout surface sprays. Additional experiments were conducted at Rathbun Hatchery to determine ifintensively reared larval walleye performances in deep cylindrical tanks with a circularflow and in a cuboidal tank with an upflow pattern were different. This experimentshowed that walleye fry in the deep cylindrical tanks performed better than those incuboidal tanks in two out of three trials. Fry viability ranged from 3.8 to 60.8%.Evidently, continuous recirculation of feed by the upwelling current in the cuboidal tankshad an adverse affect on gas bladder inflation and survival. The next step in developing techniques for mass culture of larval walleyewill require determining optimal fry densities. Experimentally, larval walleye have beencultured intensively at densities ranging from 1 to 1000 fry/L. It has been suggested thatthe optimal density for the intensive culture of larval walleye is somewhere between 10and 1000 fry/L, but this range is far too broad to serve as a guideline for practicalculture. Most studies have indicated that stocking densities of less than 20 fry/L resultin higher survival. Li and Mathias (1982) stated that "increasing fish density aboveone fish per liter had a deleterious effect on survival." The decrease in survival athigher densities may be caused by successful cannibalism or by injury caused by cohortattacks. For intensive culture to be a practical alternative to pond or tandem culture,however, densities must be above 20 fry/L. Most studies published to date haveconcentrated on some variable other than stocking density, such as diet or cultureenvironment, and the observed effects of stocking density on survival have beenincidental. In 1992, the goal of the research at Rathbun State Fish Hatchery was toreplicate the excellent results of the 1991 production season, to evaluate fry stockingdensity, and to compare performance in large (679 L) cylindrical tanks, which simulate afull-scale hatchery production system, with smaller (278 L) cylindrical experimentaltanks.  Methods and Procedures:  Experimental Design Effect of stocking density on gas bladder inflation and survival ofwalleye fry was studied. Six 278-L cylindrical tanks were used in each of three trials(T-1, T-2, and T-3), between April 11 and June 15, 1992. Five different stocking densities(20, 30, 40, 50, and 60 fry/L) were evaluated with two replicates at each density. Intrials one (T-1) and three (T-3), the densities were 20, 30, and 40 fry/L, and in trialtwo (T-2) the tanks were stocked at 20, 50, and 60 fry/L. In addition, three 679-L tanksstocked at 20 fry/L were used to evaluate fry viability in production-scale tanks. Fryperformance in these large tanks was compared with that in each of the two 278-L tanksstocked at 20/L of each trial.  Fry Culture Tank Designs and Water Flow The small cylindrical tanks were the same design used in 1991 experiments.The entire inside walls of the tank, standpipe, screen, and inlet pipe were paintedblack; the tank bottom was light gray. Flow was directed at a point midway betweenthe wall of the tank and the edge of the screen, in a clockwise direction. The flow ratewas regulated by a flow meter connected to the inlet pipe by plastic tubing. In alltrials, the flow rate was set at 3.0 L/min for the first day after stocking and wasmaintained between 5.5 and 6.5 L/min thereafter. Each 278 L cylindrical tank was provided with one surface spray directedinto the tank with a 180 degree perimeter nozzle and a flow regulation valve. Spray wasdirected at an angle (80 degrees) so that it contacted the surface between the screen andthe right side of the tank in the same direction as the water flow. The large cylindrical tank rearing volume was approximately 679 liters.Flow was directed at a point midway between the wall of the tank and the edge of thescreen, in a clockwise direction. The inside wall of the tank was painted flat black, andthe bottom was light green. The screen was painted black, and the standpipe was white.Initially the flow rate was 8.0 L/min, but it was increased to as much as 11.0 L/min asthe fry grew. Each large tank was provided with two surface sprays connected to thewater source by a 1.3-cm ID PVC pipe placed over the center of the tank, approximately 20cm above the water surface. Spray was directed at an angle so that it contacted thesurface between the screen and each side of the tank in the same direction as the flow.Spray volume/sprayer was the same as with the small tanks.  Lighting All tanks were illuminated by overhead 150-watt projector flood lamps. Thelights were on from 1500 hours to 1000 hours the next day. Black plastic covered framessurrounding the small tanks to prevent exposure to light entering from nearby windows anddoors. The large tanks were not surrounded with black plastic and were exposed to lightfrom nearby windows and doors.  Water supply The water supply was from Rathbun Reservoir, and the temperature of thewater supply was that of the lake, but three heaters were placed in the head tank toincrease the initial water temperature to 12.2 C in T-1 and to 18.3 C in T-2. Heaters werenot used in the T-3 trial because the lake temperature exceeded 18.3 C. Temperaturesduring T-1, T-2, and T-3 averaged 13.3, 18.7, and 20.3 C, respectively.  Source of Fry and Stocking Densities T-1: April 11-May 2 - Upon arrival at Rathbun Hatchery, eyed eggs weretempered for one hour to reduce the temperature from 9.4 to 6.6 C before they were placedin incubation jars. Incubating eggs were warmed gradually to approximately 12.2 C. Eggsfinished hatching nine days later. At 2d post-hatch, fry were enumerated for stocking witha mechanical fry counter (model FC2, Jensorter, Inc., Bend, Oregon). Densities were 20,30, and 40 fry/L in the six small tanks (two tanks at each density), and 20 fry/L in eachof the three large tanks. T-2: May 5-May 26 - Eyed eggs were counted with a mechanical fry counter.Densities were 20, 50, and 60 fry/L in the six small tanks (two tanks at each level) and20 fry/L in each of the three large tanks. T-3: May 25-June 15 - One-day-old fry numbers were estimatedvolumetrically. The stocking densities were the same as in T-1, that is, 20, 30, and 40fry/L in the small tanks, and 20 fry/L in the large tanks.  Feeding Small tanks - Variable speed auger feeders were used to dispense the feed.Three marbles were placed in each feeder to reduce bridging of food over the auger. Allfeeders were connected to an automatic timer (Sweeney Enterprises, Inc., Boerne, Texas)which controlled duration and frequency of feedings. Fry were fed every 4 min for 16 heach day (1530-0730 hours). Duration of each feeding ranged from 3 to 14.1 seconds (s). Large tanks - Each tank had two auger feeders placed 30 cm above the wateron opposite sides of the tank. Feeding frequency was controlled with an automatic timer.Fry were fed every 5 min during T-1 and every 4 min during T-2 and T-3. Feeders were onfor 22 h/d (1000 to 0800 hours). Duration of each feeding ranged from 0.1 to 0.5 s. Proposed feeding rates (grams of food/1,000 fry) were based on trials twoand three in 1991. Feeding rates were adjusted for fish age and for the estimated numberof fry in the tank. Changes in food size and type were based on fry length. Fry were fedthe Kyowa Fry Feed (Kyowa Hakko Kogyo Co. Ltd., Japan) throughout the experiments. Tank Cleaning Three to five h/d were spent siphoning and cleaning the nine tanks. Thedaily routine for tank cleaning included siphoning waste feed and dead fry, removing andspraying the drain screens with pressurized water until clean. Dead fry removed by thesiphon were counted. A coarse sponge was used to wipe inlet pipes and all inside surfacesof tanks beginning 9 d posthatch in trial T-1 and 6 d posthatch in trials T-2 and T-3.Before the sidewalls were cleaned, the water level was decreased by 50%. When cannibalismbecame evident (11, 7, and 6 d posthatch during trials T-1, T-2, and T-3, respectively),up to 10 min/tank/d were spent siphoning out cannibals and recording their numbers. Water Quality Water samples were collected at the water source (head tank) to theculture tanks. Carbon dioxide, total hardness, and alkalinity were measured using a HachKit (Hach Company, Loveland, Colorado). A Hach DR/3000 spectrophotometer was used todetermine nitrite and total ammonia nitrogen levels and turbidity. An Orion pH meter wasused to measure pH. A dissolved gas meter (Common Sensing, Inc., Bainbridge Island,Washington) was used to measure DP, N2 mm Hg, % N2, total gas pressure (TGP) mm Hg, and % TGP. Fry Sampling and Final Count From 6 to 18 d posthatch, three to four random samples of 20 fry wereremoved from each tank and observed microscopically for presence of inflated gas bladders,food in gut, and oil globules. The percentages of fry with food in gut and with inflatedgas bladders was recorded along with oil globule diameter, gas bladder length, and frylength. Final samples of 100 fry/tank were removed at the end of each trial. Presence offood in gut, lengths of gas bladders, and lengths of fry were recorded. The surviving frywere hand counted at the end of each trial. DiscussionDensity Effects Fry survival was not significantly affected by stocking densities between20 and 40 fry/L, but survival was significantly lower at densities of 50 and 60 fry/L thanat a density of 20/L. The number of survivors (i.e. production per tank), however, wassignificantly greater in the tanks stocked at 50 and 60/L (216% greater at 60/L) than inthe tanks stocked at 20/L. Considering the comparative value of a newly hatched fry tothat of a 21 d old, feed-trained fingerling, it would be more economical to stock fry atdensities of 50 than at 20 fry/L despite the reduced percentage of survival, because theoutput of trained fingerlings is greater at the higher densities. Production Scale Tanks With the exception of the third trial, when bacterial gill diseasesubstantially reduced survival, fry viability was greater in the large than in the smalltanks. Gas bladder inflation, however, was significantly lower in the large tanks in 2 of3 comparisons. The differences in gas bladder inflation may have been due to the lowernumber of spray heads per unit surface area of tank in the large tanks; i.e. more sprayheads may be needed in the large tanks. There was one spray per 4,778 cm2 ofsurface area in the small tanks and one spray per 5,941 cm2of surface area inthe large tanks. Small tanks had 24% more spray coverage than did the large tanks. The lower incidence of cannibalism in the large tanks may be related tothe difference in the length of the feeding period. The small tanks were fed for 16hours/day, and the large tanks for 22 hours/day. The mean percentage of fry removed ascannibals was 4.9% (range 1.9 to 7.5%) in tanks fed 16 hours/day, but only 1.8% (range 0.3to 3.4%) in tanks fed 22 hours/day. Effects of Temperature The best performance of fry in the three trials was in T-2 when the meantemperature was 18.7 C. Theoptimum temperature for raising walleye from 0-22 days posthatch seems to be between 17and 18 C. Fry raised at 13.3 C (T-1) developed more slowly and weremore likely to be killed or injured during cleaning and to succumb to cannibalism. In T-3,when mean temperature was 20.3 C, fry performance was less favorable because of bacterial gilldisease. Temperature, crowding, and the general cleanliness of the inflowing water mayhave been a factor in the development of bacterial gill disease during the third week ofthis trial. In T-1, T-2, and T-3, respectively, survival and mean temperatures were 3.8%at 15.0 C, 34.2% at 15.8 C, and 68.2% at 19.2 C. In T-3, the mean temperature duringthe first nine days of culture was 18.2 C; close to the projected optimum. DetectingSwim Bladder Inflation in Fingerling WalleyesBy: Frederic T. Barrows, Greg A. Kindschi, and Ronald E. Zitzow, U.S. Fishand Wildlife Service, Fish Technology Center, 4050 Bridger Canyon Road, Bozeman, Montana59715In the March '94 issue of the MTAN, we included two articles regarding theimportance of surface water spray and swim bladder inflation to guarantee the successfulrearing of walleye fry. As a follow up, we wanted to explain how you can detect the earlysigns of swim bladder inflation problems. The following information has been edited toconserve space. **The** lack of swim bladderinflation is a major problem in the intensive culture of several species of larval fish.This phenomenon has been reported several times in intensively reared walleyes, stripedbass, white seabass and madai. Recently, however, in pond-reared walleye fingerlings,9,490 of 13,000 (73%) had uninflated swim bladders (personal observation). Although somepopulations of pond-reared walleyes had been observed to have low percentages of fish withuninflated swim bladders, such high percentages have not been previously documented. Determining swim bladder inflation status of larval walleyes (< 40 mmtotal length) can be completed easily with the aid of a dissecting microscope. Thismethod, however, is time-consuming, cumbersome, and not effective with large fish. Chapman(1988) developed a method of separating larval striped bass with inflated swim bladdersfrom those with uninflated swim bladders. An anesthetic solution was used to separate thefish by their buoyancy. Henderson-Arzapalo (1992) used Tricaine (MS-222) in a saltwatersolution to separate normal phase-I striped bass from those with uninflated gas bladders.Radiography (X-ray photography) has also been used to monitor development and to determineswim bladder inflation in salmonids and European bass. The development of methods to easily detect swim bladder inflation statusin fingerling walleyes (25-155 mm total length) would enable large groups of fingerlingsto be monitored. Our objective was to compare four methods for determining swim bladderinflation, in terms of their accuracy, cost, and effect on walleye survival. Methods The light table (glow box, model 12-20E-3, Instruments for Research andIndustry, Cheltenham, Pennsylvania), anesthesia, saltwater float, and radiographic methodswere tested for detecting swim bladder inflation in walleyes that were 80-167 mm long. Thelight table method involved the use of a box that contained two fluorescent light bulbsand had a translucent top; such a box is normally used for viewing photographic slides.Fish were anesthetized in Tricaine (100 mg/L) and them passed over the light box. The swimbladder is easily identifiable as a light tubular area between the spinal column and theviscera. In the anesthesia method, MS-222 was used to relax the fish so that aninflated swim bladder would have a buoyant effect on fish position. Preliminary trialsindicated that the concentration of the anesthetic affected the buoyancy and relaxationtime of fish with inflated swim bladders. Seven concentrations of MS 222 were tested (40,60, 80, 100, 120, 140, and 160 mg/L), and the time required for the cessation of all fishmovement, except gill movement, was recorded. Salt water was used to separate fish with inflated swim bladders fromthose with uninflated swim bladders according to buoyancy, as in the anesthesia method.However, only dead fish were used in this trial. Saltwater concentrations of 1, 2, 3, and4% by weight and plain water (no salt) were used to separate walleye fingerlings. Fishwere placed in the bucket, stirred, and allowed to settle for about 30 s. Buoyantfingerlings were removed with an aquarium net and placed in a separate bucket of freshwater. Nonbuoyant fish (those lying flat on the bottom, unable to be raised into the watercolumn with gentle stirring) were removed and then placed into another bucket containingfresh water. After the samples were separated in this manner, they were again removed fromthe water and placed on a light table so that swim bladder inflation could be verifiedvisually and the fish of the different groups could be counted. Twelve frozen samples,each known to contain a mixture of walleye fingerlings with and without inflated swimbladders, were available for the trial. Three samples were tested for each saltconcentration. Samples separated with plain water were mixed back together and separatedagain with 4% salt solution. An additional experiment was conducted to determine if freezing andthawing had an effect on the detection of inflated swim bladders. Anesthetized fish wereseparated in 2% salt solution, and nonbuoyant fish were checked for inflated swim bladdersunder a dissecting scope. The fourth method involved X-ray radiography of several walleyes lyingflat and close together on a film plate. This procedure was conducted at a localveterinary clinic. In the present trial, no efforts were made to keep the X-rayed fishalive. This method could be used for determining the percentage of swim bladder inflationin a population of fish, whereas the other three methods could be used to sort live fishwith inflated swim bladders from those with uninflated swim bladders. Different triplicate lots, each with 30 fish of mixed swim bladder status,were examined with the light table, anesthesia, and X-ray methods. All fish were thensacrificed, dissected, and visually examined for the presence of an inflated swim bladder.The accuracy of each method was evaluated by comparing the ratio of inflated to uninflatedswim bladders determined by the method being tested with the ratio determined bydissection. To evaluate the effect of the methods on survival, three lots of fish weresorted by the light table method and three lots were sorted by the anesthesia method withthe high concentration of MS-222 (160 mg/L). They were then placed in 19-L rearingcontainers for 14 d to monitor survival. Results and Discussion The anesthesia and X-ray methods were 100% accurate in detecting swimbladder inflation status of the tested walleye fingerlings, which were longer than 75 mmand weighed about 18 g each. The anesthesia method with MS-222 at a concentration of 100mg/L seems to be inexpensive and accurate, but fish condition must be closely monitored toprevent mortality during the treatment. At this MS-222 concentration, fish could beseparated after 75 s. Walleyes with inflated swim bladders were upside down or floating atthe surface, whereas those with uninflated swim bladders were lying flat on their sides onthe bottom of the container. Shallow and wide containers, which provide more water surfacearea, were more useful than deep and narrow containers. The light table method for detecting swim bladder inflation in walleyefingerlings is inexpensive, fast and did not adversely affect the fish after treatment.The accuracy, however, of the light table method was only 91.5%. In preliminary studies,the accuracy of this method was observed to be higher for fish shorter than 75 mm than forthe larger fish used in this trial. This difference is attributable to the greatertransparency of small walleyes, which allows an unobstructed view of the swim bladder.Neither the MS-222 method nor the X-ray method was tested on fish less than 75 mm long. The saltwater float method was 99.7% accurate and simple to conduct. Moretime was required to separate and remove fingerlings in the 0, 1, and 2% salt solutions,because numerous buoyant fish remained throughout the water column and at the bottom. Onlya few fish with inflated swim bladders were found among the nonbuoyant ones. Separation of fingerlings according to swim bladder status worked well in3 and 4% salt solutions. Very few buoyant fish remained in the water column or near thebottom. One fish with an uninflated swim bladder was found among buoyant fish of onesample separated in 3% salt solution. This fish may have stuck in some way to a buoyantfish. It appears that 4% salt solution may be too strong, as several fish with uninflatedswim bladders separated with buoyant fish in all three samples. Based on these results,our recommendation is that 3% salt solution be used to separate 2.5-5-cm-long walleyefingerlings with inflated swim bladders from those with uninflated swim bladders afterfish have been frozen and then thawed. There was an effect on freezing and thawing on swim bladder inflationstatus. After fish had been frozen and thawed, a higher rate of noninflation was observedthan before freezing. When expressed as a percentage of fish with uninflated swim bladdersbefore freezing, the average increase was 7.9%. However, when expressed as a percentage ofthe total sample, the increase was only 0.3%. The effect of this method of storage andevaluation was considered minor. The X-ray method is expensive but extremely accurate for testing walleyesof any size. Whether keeping fish alive for this method is practical is not known, but agood approach for this method may be to radiograph only a subsample of a population todetermine relative percentages of swim bladder inflation and noninflation. This methodalso provides, however, a permanent record for future use. Survival was not affected by evaluating the swim bladder status of fishwith either the anesthesia (160 mg MS-222/L) or light table method. No mortality occurredduring the 2 weeks after the use of these methods. We recommend either the light table method or the MS-222 method inconjunction with a 3% salt solution for routine screening of populations of walleyefingerlings. These methods are simple, inexpensive, and fairly accurate. Trainingpersonnel to perform these evaluations could consist of first using one of these methodsto sort the fish according to their swim bladder inflation status and then checking theresults by either dissection or the X-ray method. HydrogenPeroxide Controls Fungal Infections On Trout EggsBy: Leif Marking, Jeffrey Rach, and Theresa Schreier, National FisheriesResearch Center, P.O. Box 818, La Crosse, WI 54601 (608-783-6451)Malachite green,once the preferred fungicide for fishery use, is no longer permitted for treatment of fishor fish eggs for control of fungus because the Food and Drug Administration has restrictedthe use of malachite green on food fish. Formalin is an effective fungicide, but fisherymanagers are concerned about safety to the user and effluents in the environment. Otherantifungal agents, therefore, are needed to maintain healthy fish and eggs in fish culturesystems.Hydrogen peroxide is active against a wide variety of organisms-bacteria,yeasts, fungi, viruses, and spores. Federal agencies list this chemical as "GenerallyRecognized As Safe" when used as a bleaching agent in manufacturing or feedingpractices or as an antimicrobial agent in cheese production or drinking water treatment.Furthermore, hydrogen peroxide has been used as an antiseptic and a treatment for skinparasites, protozoans, and monogenetic trematodes on fish and is proposed as a treatmentfor sea lice on salmon. We designed experiments to evaluate the effectiveness of hydrogenperoxide for control of fungal infections on eggs of rainbow trout.**In Vivo Procedures**Green eggs of rainbow trout were placed in Heath incubation trays andmaintained in well water with a flow rate of 1 L/min. Groups of 500 eggs were confinedwithin 15-cm diameter acrylic rings that were fastened to the screen of each incubationtray. Eggs were inoculated with fungus (Saprolegnia parasitica)activelygrowing on hemp seeds suspended by tea balls in the upper tray of each duplicatedtreatment. Infection of eggs generally occurred within 7 days. The infection rate of about10% in each tray was obtained by exchanging infected eggs between trays. Eggs infected atthe 0 and 10% level were then exposed to hydrogen peroxide for 15, 30, or 60 min everyother day for 2 weeks. Treatments ceased when the eggs began to hatch. A positive controlgroup was inoculated with fungus but not treated with hydrogen peroxide. A negativecontrol group was neither inoculated with fungus nor treated with hydrogen peroxide.**Efficacy of Hydrogen Peroxide**Artificial infection of eggs was successful - infection rates increasedsubstantially in the positive control and the hatch rate for those eggs was only 2.1%.Hydrogen peroxide treatments of 500 ppm controlled fungal infections on eggs not infected(O% infection) at exposures of 15, 30, and 60 min; hatch rates were significantly higherthan for control groups. This treatment concentration was effective for control of fungusat the 10% infection rate only in the 60-min exposure. The 1,000-ppm treatments, however,were effective for control of fungus and increasing the hatch rate at all three exposureperiods. Both treatment concentrations controlled fungus and increased hatch rate ofuninfected eggs (O% infection) at all exposures.In reality, the 10% infection rate is perhaps a "worst case"situation in hatcheries where treatments are normally done when the fungus first appearsor is suspected. The 1,000-ppm treatment rate may be excessive, especially for the longerexposures. It is premature to recommend a general treatment rate, therefore, a suitabletreatment rate should be developed to meet the particular conditions in individualhatcheries. Hydrogen peroxide seems to be equally or more effective than formalin forcontrol of fungus on trout eggs in similar in vivo experiments.**Availability for Use in Fisheries**Hydrogen peroxide is one of the most environmentally compatible chemicalsbecause the primary decomposition products are oxygen and water. This versatile chemicalalready has widespread application and acceptance in pulp and paper, textile, wastetreatment, mining, petroleum, food and chemical processing, cosmetic, and pharmaceuticalindustries. The U.S. Food and Drug Administration recently approved a petition from theNational Fisheries Research Center-La Crosse that hydrogen peroxide be classified as a lowregulatory priority when used to control fungi on all species and life stages of fish,including eggs. This ruling means that hydrogen peroxide can be used as a fungicidewithout an investigational new animal drug permit or a new animal drug application.**Product ManufacturersOver the lastseveral months the MTAN has been accumulating additional information from productmanufacturers which sell aquaculture related supplies. The following list will hopefullyhelp you with locating different suppliers to insure your getting the best product andprice available.Little Titan: This pond aeration system    offers an efficient and cost effective way to improve water quality and to provide fish    with oxygen enriched water. The device is produced by Otterbine/Barebo, Inc., 3840 Main    Rd. East, Emmaus, PA 18049 (215-965-6018).  AquaTornado Aerator: This large pond    aeration system will mix and destratify, increase available dissolved oxygen, plus help to    control algae and ice. The device is produced by Aeromix Systems, Inc., 2611 N. Second    St., Minneapolis, MN 55411-1634 (800-879-3677).  PT4 - Hauling Oxygen Meter: Multichannel    monitor for reading oxygen, temperature and pH. Serves to constantly monitor DO in    incubators and fish transport tanks. Used at St. Croix Tribal hatchery during incubation    periods with great success. This meter is made by Point Four Systems, Inc. and sold by    Aquatic Ecosystems, Inc. 2056 Apopka Blvd., Apopka, FL 32703 (800-422-3939).  Sentry 3: This oxygen and temperature    monitor is ideal for monitoring water for fish hatcheries or recreational sport fishing.    The device is produced by Otterbine/Barebo, Inc., 3840 Main Rd. East, Emmaus, PA 18049    (215-965-6018).  Portable Dissolved Oxygen Meter:    Features include a rugged waterproof design, automatic compensation of temperature,    salinity, and partial pressure, plus an analog and digital outputs. The device is produced    by Royce Instrument Corp., 13555 Gentilly Rd., New Orleans, LA 70129 (800-347-3505).  Fishing News Books-1994 Catalog: This    reference book list several detailed descriptions of many other fisheries/aquaculture    related books and journals which are available through Fishing News Books. The list is    unique in its all-embracing coverage of the many technical and scientific aspects of fish    farming, commercial and environmental management of aquatic resources and technical and    scientific aspects of commercial fishing. An order form is also included with the catalog    so you may purchase any of the books which are listed. The 1994 catalog can be obtained by    writing to Philip Saugman, Fishing News Books, Blackwell Scientific Publications Ltd.,    Osney Mead, Oxford 0X2 0EL, UK (phone number is 0865-240201).  Fiberglass Rearing Tanks: Numerous sizes    are available for round, half round, cone, rectangular and square tanks. Custom orders for    specialized tanks are also taken. The standard features include; smooth molded gelcoated    interior, exteriors are gelcoated over a mat finish, handlaid multiple laminates of mat    and roving, flanges, drains, sumps, fittings, rounded corners and sidewall stiffening    ribs. These tanks are produced from:Hulls Unlimited East, Inc., PO Box 70,  Deltaville, VA 23043 (804-776-9711).Peterson Fiberglass Laminates, 300 Stariha Dr.,  Shell Lake, WI 54871 (715-468-2306).  Polytank, Inc., 62824 250th St.,  Litchfield, MN 55355 (612-693-8370).J & S Tanks, 935 Highway 29 N., P.O. Box 144,  Alexandria, MN 56308 (612-763-4191).Will-O'-The-Wisp's: This device presents    a totally new concept in commercially feeding your pond fish. The feeder is placed on a    post overhanging the water. A circular ultra violet light attracts the insects and are    pulled into the feeder by a high speed fan. The fan then blows the insects against a    screen at the back of the feeder, dropping them into the water to feed your fish. The    monthly electrical cost are reported to be less then $5.00. The device is distributed by    Aquatic Biologist, Inc., N5174 Summit Ct., Fond du Lac, WI 54935 (414-921-6827).  Fish Farm and River Ecosystem: High    schools and other public educational programs who want to get into aquaculture (in a small    way) may want to look into these devices. The Fish Farm is a self-contained recirculating    system (10' * 10') that provides "hands-on" fish rearing capabilities. The    rearing system comes with a galvanized steel tank, liner, air pump, molded clarifier, PVC    water lines and a rotating biological filter. The River Ecosystem is a small cross-section    of a working river, complete with banks, shallows, pools, waterfalls and rapids. This    system allows you to watch and monitor fish, frogs, lizards and plants in a    "natural" setting. The system includes a tank, pump, light, heater, filtration    cartridge and owners manual. To receive more information contact the Stoney Creek    Equipment Company, 11073 Peach Ave., Grant, MI 49327 (800-448-3873).  Nets and Seines: Nylon gill nets,    experimental gill nets, herring-pike-perch nets, hoop/fyke nets, seines, small mesh    netting, survival and bait nets, landing and dip nets, mosquito nets, rope, leaded and    float lines, nylon twine and netting needles, floats and leads, net pens, bird and animal    capture nets and hydroelectric dam tail race nets. These products are available from:InterNet Inc., 2730 Nevada Ave. North,  Minneapolis, MN 55427-9949 (800-328-8456).  H. Christiansen Co., 22 North 2nd Ave.  West, Duluth, MN 55802 (218-722-1142).  FNT Industries, Inc., 927 First St., PO Box 157,  Menominee, MI 49858 (800-338-9860).Minnow Traps: Cylinder, Cloverleaf, B,    and Box type traps are available. All the traps are made of galvanized metal or treated    wood frames, zinc coated screws, welded or woven galvanized hardware cloth and    steel/aluminum rivets. They also have PVC coated wire. Easy-slide doors and smooth edges    are part of every trap. Custom orders are also accepted. For more information contact    Jerry Radermacher, Community Services Workshop, PO Box 787, Willmar, MN 56201    (612-235-4613).  Everything Else:If you like one stop shopping for feeds,  chemicals, equipment and books, be sure to subscribe to Aurum Aquaculture, 11818 115th  Ave. N.E., Kirtland, WA 98034 (800-817-5808).  Two additional sources for a full range of  aquaculture related materials are through:  Aquaculture Supply, 33418 Old Saint Joe Rd., Dade City, FL 33525 and Eagar  Inc., P.O. Box 540476, North Salt Lake, UT 84054 (800-423-6249).  To find equipment for aeration, measuring,  monitoring, pumps, filtration, sterilization, laboratory, chemicals, feed and feeders,  nets, cages, predator control, tanks and liners, be sure to subscribe to Aquatic  Eco-Systems Inc., 2056 Apopka Blvd., Apopka, FL 32703 (800-422-3939).  To find equipment for aeration systems,  regenerative blowers, air and water pumps, air diffusers, vinyl tubing, RBC biofilters,  biofiltration media, fish feeding devices, telephone alarms, plus hauling and rearing  tanks, be sure to contact the Stoney Creek Equipment Company, 11073 Peach Ave., Grant, MI  49327 (800-448-3873).  If you need materials for water aeration  (destratification of ponds, maximizing oxygen transfer, airlift systems, packed columns,  diffusers, degassers and air curtains) or water heating/chilling systems, you may want to  contact Aquaculture Research/Environmental Associates (AREA), P.O. Box 1303, Homestead, FL  33090 (305-248-4205).  Vertical tray incubation systems with or  without isolation options, circular fish tanks, rearing troughs, egg shipping cases, fish  measuring boards and "Heath" water/egg tray replacement components. For more  information contact F.A.L/Heath, 4540 So. Adams St., P.O. Box  9037, Tacoma, WA 98409 (800-851-1510).To develop a career in aquaculture you may want  to contact the Alexandria Technical College, 1601 Jefferson St., Alexandria, MN 56308  (612-762-0221).  A new wallet size handout which describes  how to identify the Eurasian Ruffe is now available through the Ashland FRO  (715-682-6185).  Do you need transport containers for fish?  Dynoplast has developed a series of versatile food containers which can withstand rough  usage. These containers (manufactured from food approved materials) will ensure delivery  of cool and fresh products in prime condition. For more information contact Canam Trading  Corp., Elgin, IL(800-231-9721 - ask for Jim Quinn).  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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