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Ashland NFWCO
 Midwest Region
 mtanlogo.gif (9794 bytes) Dedicated To The Tribal Aquaculture Program December 1992 - Volume 2
 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: Walleye    Fingerling Fertilization in Earthen Ponds  FmHA Aquaculture  Loans  Zebra Mussel  Toxic Bait For Carp Control  Stress and Fish    Culture  Walleye    - A Light and Temperature Experiment  Radon Gas  WalleyeFingerling Fertilization in Earthen PondsBy: Larry J. Wawronowicz, Lac du Flambeau Indian ReservationThe techniques used to produce walleye fingerlings arevaried depending on environmental, biological, chemical and physical parameters of thepond, water supply, watershed, etc. Success or failure of a production season depends onthe ability of the pond managers to consider the above parameters when making pondmanagement decisions. The main objective of pond culture, regardless of the speciesraised, is to increase primary productivity by utilizing fertilizers. A pond manager willfertilize a pond for the same reason a farmer will fertilize a corn field, to increase thenumber of bushels of corn per acre to feed cattle. The pond manager will increase primaryproductivity by fertilization to convert the sun's energy to phytoplankton to zooplanktonto fish biomass.The types and combinations of fertilizers used can be organic and/orinorganic. Chicken manure, alfalfa meal, torulas yeast, whey, hay and pig manure areexamples of organic fertilizers. Inorganic fertilizers are represented by 18-46-0,10-10-10 and super triple phosphate. Inorganic fertilizers are available in liquid andgranular forms. Agricultural lime may also be used to buffer the soil and water to moreeffectively use the fertilizer. The type, amount, and/or combination of fertilizers useddepends on soil fertility, soil pH, water pH, soil and water buffering capacityavailability, pond manager's experience and preference, and success or failure of aproduction season.In Lac du Flambeau, agricultural lime (2,000 pounds/acre), alfalfa meal(500 pounds/acre) and torulas yeast (50 pounds/acre) are applied to the pond bottom orwater column at various times during the production season. All of the agricultural limeis applied to the pond bottom and disked into the soil before the pond is filled.Approximately 10 days before the walleye fry hatch, the ponds are filled and 250pounds/acre of alfalfa meal and 25 pounds/acre of torulas yeast are applied to the pond.The balance of the fertilizers is applied during the 30-45 day growing season. Generally,a pond is fertilized weekly with 63 pounds/acre of alfalfa meal and 6.5 pounds/acretorulas yeast.The fertilization program described will produce daphnia's and copepodswhich are preferred by young walleye. The time to apply the balance of the fertilizer willbe determined by the pond manager when the zooplankton populations are sampled (2-3times/week), oxygen concentration at first light is determined, and weather conditionsevaluated. The relative abundance, species composition, and quality of the zooplanktonmust be monitored and noted. If, for example, the number of zooplankton has decreased,there is no sign of recruitment, the pond color changes, walleye fingerlings are foragingin front of the water intake, etc., it is time to fertilize if oxygen concentration andweather conditions are desirable. The pond manager may choose not to fertilize ifthe first light oxygen concentration was below 5 mg/l and the weatherman is predicting 5consecutive cloudy days and high humidity. Under these conditions, increasing thebiological oxygen demand caused by the decomposition of additional alfalfa meal andtorulas yeast may cause an oxygen depletion.The fertilization program described will produce on the average 58,100,1.5-2.0 inch walleye fingerlings per acre annually during a 30-45 growing season. Annualproduction has ranged from 22,200 to 98,000 walleye fingerlings/acre depending on theproduction year. The Lac du Flambeau fertilization program was developed by analyzing thepond soils, trial and error, and the intuitive reasoning of the pond manager.FmHA AquacultureLoansAccording to Mike Navin, Native American Coordinator forFarmer's Home Administration (FmHA) State of Minnesota, FmHA has a program directedspecifically toward Native Americans. Mike said that under this program, loans areavailable for Native American's interested in Aquaculture farming. The loans are notavailable for tribal programs, rather individuals only. You can reach Mike at (612)290-3842.Zebra Mussel Basedon the experience ofelectric generating stations and municipal water systems in dealing with zebra mussels, itmay be just a matter of time until a fish hatchery becomes affected. Biologists believe that the interbasin transport of the zebra musselfrom the Great Lakes system into inland fresh surface waters is taking place vianatural and human influenced dispersal vectors, and that the mussels will ultimatelyinfest most areas of North America south of central Canada and north of the FloridaPanhandle. Such dispersal will likely be greatly enhanced by interlake transportof veligers (larvae) in ship ballast, and adult and juvenile mussels attached to ship andrecreational boat hulls. There is concern that the range expansion of the zebra musselwill be further facilitated by transport of veligers by commercial bait transport, inangler's bait bucket water, recreational boat engine cooling water, plus transport ofjuveniles and adults by waterfowl and by attachment to crayfish and turtles. With this inmind the time is right to develop a monitoring program at your hatchery facility. Toxic BaitStrategy Effective For Carp Control Commoncarp can pose majorproblems for fisheries managers when their feeding activity degrades valuable fish andwaterfowl habitat. Several methods are available to help reduce carp numbers: angling,electrofishing, construction of barriers, water level manipulation, baited traps, nets andalso toxicants. If you feel that toxic bait is needed you may want to look into the use ofAntimycin. Toxic baits would be especially effective if carp were congregated in smallareas. This might be best achieved by baiting a preselected area or through water levelmanipulations. For the toxic bait to be effective, the carp should be actively feedingduring the application. The question of limiting the losses from nontarget organismssuch as waterfowl and other fishes will also need to be addressed. For moreinformation regarding the use of Antimycin contact Jeff Rach at the USFWS NationalFisheries Research Center, La Crosse, Wisconsin (608-783-6451). Stress and Fish CultureBy: MTANThe following topic was selected from "Introduction To FishHealth, published by the U.S. Fish and Wildlife Service. Stressin fish may be describedas a fish's physical response to an environmental change. These physical responses caninclude blood hormone and other cellular changes as the fish try to regain internalequilibrium to an external environmental change that has displaced the internalequilibrium. There are many environmental changes associated with the intensiveculture of fish which are capable of disrupting the fish's internal balance. These changesinclude unfavorable or fluctuating water temperatures, ammonia and nitrate levels, anddissolved oxygen concentrations. In addition, management practices such as handling,crowding, transport, anesthesia, and therapeutic treatment can all disturb the delicateinternal balance of the fish. Typically, the response of the fish to most of the human activities isfright. Frightened fish move about rapidly and their oxygen demand increases considerably.If the stress continues, the fish's ability to restore its internal balance becomes lessand less. Stresses requiring an adjustment exceeding the fish's ability to accommodate areoften lethal. Sublethal responses to chronic or acute stress in fish are seen inbehavioral changes, production traits (growth, weight gain or loss, food conversion) anddisease outbreaks. These changes are the fish's way of showing that it is suffering from astress it can no longer deal with and if the stressor is not reduced, these sublethalresponses may become lethal. Because many of the stresses are related to human activity, several arecontrollable through a change in management practices. The following recommendations willassist in decreasing hatchery related stress: 1. Reduce handling of fish to a minimum.    2. Avoid temperature shock.    3. Stresses may be additive; allow recuperation between    stressful situations.    4. Avoid high loading densities.    5. Maintain optimum water quality conditions.  Comments on Good Management Management has the responsibility to raise the highest quality fish forits programs. To accomplish this task the following must be taken into consideration. 1. Avoid hatchery to hatchery transfer of fish.    2. Maintain water supply systems free of fish and other aquatic    life.    3. Provide optimal environmental conditions for the species      being raised, paying attention to maintaining optimal oxygen levels, and minimal ammonia    levels. Attempt to keep densities low.    4. Handle fish gently, and where there is a seasonality to      disease outbreaks, avoid handling fish two to three weeks prior to and during the expected    time of usual outbreaks. 5. Maintain cleanliness of rearing facilities. This includes      segregated fish handling equipment or strict practices of disinfection of nets and other      equipment between lots of fish. This also includes picking out mortalities and fish      showing distinct signs of stress, disease, or failure to survive.    6. Where appropriate, use strains of fish species which show      resistance to the specific endemic disease problems.    7. Disinfect all salmonid eggs spawned on-site or shipped to      station with a polyvinylpyrrolidone iodine compound.    8. When stress is unavoidable, allow sufficient recovery time,      based on the physiological disturbances involved, before again handling or stressing fish. The fish culturist who has frequent contact with the fish should be thefirst line of defense against a full-blown disease outbreak in a fish population. The fishfeeder sees the fish regularly and should be alert to subtle changes which may precedesignificant losses.  Observations to note are as follows: Changes in appearance or behavior from normal. We must first know how a    normal fish looks and acts. The internal examination of healthy fish is as important as an    external examination. Fish in poor health gather near the incoming water supply, do not    feed well, are sluggish, and may flash on the bottom of the holding unit.    Changes in vitality. Fish in good health quickly flee from    disturbances. Symptoms of fish in poor health are: fin erosion, loss of balance, general    sluggishness, not reacting to disturbances, swimming with the head high up in the water,    and crowding the inlet.    Changes in the feeding pattern. Fish in good health feed actively and    clean up the food within minutes. Fish in poor health may cease to feed. High water    temperatures, low oxygen, crowded holding units, parasites and bacterial infestation cause    fish to go off feed. ANY TIME FISH GO OFF FEED FIND OUT WHY !!!!    Sores, lesions, coloration or ghostly appearance. A complete    examination may be needed but the appearance of any of the above usually indicates disease    or physical problems. The following two topics were taken from the January 1992 issue of"The Progressive Fish-Culturist". Light  and Temperature Effects on Performance of Walleye and Hybrid Walleye Fingerlings RearedIntensively By: Gary Siegwarth and Robert Summerfelt Abstract. Growth, survival, and feed conversion of walleye (Stizostedionvitreum)and F1 hybrid fingerlings were comparedunder conditions of submerged and overhead lighting. We also compared these variables forthe hybrids at 20 and 25C. After 71 d, walleyes reared with submerged lighting were longerthan walleyes reared with overhead lighting. Other differences in performance betweenlight treatment groups for walleyes were not significant. The performance of the hybridswas unaffected by temperature or light regime. Hybrids were longer and heavier thanwalleyes when reared with overhead lighting, but not when reared with submerged lighting.Hybrids had better feed conversion than walleyes when reared with submerged lights, andhigher survival in both light regimes. Growth differences between walleyes and hybridsfound in the present study and in previous investigations were reduced with the use ofsubmerged tank lighting. Submerged lights also reduced agitation of the fish from shadowsof people that were caused by overhead lighting. Removalof Radon Gas Liberated by Aeration in Fish HatcheriesBy: Wesley OrrAbstract. Radon gas, a radioactive by-product of uraniumdecay, is found in groundwater in some areas of the country. Aeration of this water cancause radon gas to be released into the atmosphere. Exposure to radon gas by-products is ahealth concern because of the increased risk of lung cancer. High levels of radon gas havebeen measured in fish hatchery buildings, and in some cases, are due to the water flowingthrough the aeration columns. We developed a simple inexpensive method to reduce the radonproblem at Ennis (Montana) National Fish Hatchery. Radon levels in the hatchery buildingwere measured at 200-250 picocuries radon/L air (Pci/L). The U.S. Environmental ProtectionAgency guidelines recommend remedial action when radon levels exceed 4 Pci/L. Because airis drawn down through aeration columns, we were able to put a collector at the base of thecolumn to collect the off-gas coming out of solution. Off-gas collectors were installed on38 packed columns at a cost of US$600. Since installation of the collectors, radon gaslevels have decreased from 250 Pci/L to 25-40 Pci/L. The off-gas collector is a simpleinexpensive method to reduce the magnitude of a dangerous health problem.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 selectionpageReturn to Ashland NFWCO homepageReturn to Region 3 U.S. Fish and Wildlife Service
 
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