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Ashland NFWCO
 Midwest Region
 Dedicated To The Tribal Aquaculture Program March 1995 - Volume
          11
    **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:
    Aquaculture On Line And On Screen
      Oxygen Injection Backup System
      Maximize Your Hatchery Budget
      Intensive
      Walleye Culture
      Tank Culture Techniques
      For Walleye
      Fingerling
      Walleye Production At Garrison Dam
      BGD In Hatchery's
      Hatchery
      TipAquaculture - On Line and On Screen
    By: MTANYes it's true, the time has finally
  come to drop that pocket calculator and make way for the new "Information
  Highway". This new technology to the sky has many forms. It may just be a more
  enlightened use of the many software programs now available for aquaculture professionals,
  or a it could be a "In-Your-Office" trip to the other end of the planet. Using a
  computer modem permits many exciting opportunities for people who are interested in
  aquaculture not only to share information with other professionals, but also to learn from
  them so we can better insure that our programs have the same levels of success. The MTAN
  has been gathering information on both the various types of aquaculture software now
  available plus a skyward path you may wish to take as you travel along this new
  Information Highway.
    So buckle those seat belts, the posted speed limit is only as finite as
  your computer system's operating speed or your own imagination.
    Let us first begin with the "Internet" because
  it's the true backbone for the information superhighway. The Internet is a network of
  thousands of other networks linking millions of people worldwide through their computer
  modems. Besides being a method of exchanging electronic mail (e-mail), the Internet
  provides access to databases, computer programs, card catalogs, electronic forums
  (listservs) and much more. Electronic forums provide a way for hundreds of users to
  exchange information, discuss issues, and find solutions to common problems. An electronic
  forum is like a mailing list; every message sent to the list gets forwarded to every other
  member on that list. There are electronic forums on almost any imaginable topic.
    If you have access to the Information Highway, you can also retrieve
  information from the Aquaculture Network Information Center (AquaNIC). AquaNIC (http://ag.ansc.purdue.edu/aquanic)
  is a gateway to the world's electronic resources in aquaculture. AquaNIC is maintained at
  Purdue University in West Lafayette, Indiana and is supported by the Libraries of Purdue
  University, Purdue University Cooperative Extension Service, University of Illinois
  Cooperative Extension Service, the Illinois-Indiana Sea Grant Program, and the United
  States Dept. of Agriculture Extension Service.
    AquaNIC is a multi-branched system containing a wide variety of
  information. Most documents can either be viewed on your computer monitor, downloaded via
  modem, or a copy sent to your e-mail address. AquaNIC also contains an image directory
  that holds hundreds of pictures, short videos, and slides in a variety of common image
  formats. A long-term AquaNIC objective is on-line interactive media that can be used by
  Cooperative Extension Service or Sea Grant county staff.
    One of AquaNIC's unique features is that it is linked to other aquaculture
  databases on the Internet. These links are established for you when another aquaculture
  database is selected. AquaNIC's gateway searching capability allows users to individualize
  specific search criteria. If a user does not have direct access to the Internet, there are
  several commercial carriers that will help you to link up with AquaNIC, including America
  On-Line, DELPHI, and Prodigy, which do charge a user fee.
    If the Information Highway can go no further then the back of your
  computer, several options still exist to connect your hatchery program with the expertise
  from other professionals. Several stand alone computer programs and spreadsheet/database
  worksheets are available which provide a fantastic means of quickly organizing and
  calculating information. These programs can also be specifically tailored to meet your
  needs. Often the initial time to setup the worksheet may test your tolerance level, but
  once the format has been established and the worksheet has been tested, you will quickly
  see what time savers these programs can truly be.
    The MTAN has collected some information on a few of these stand alone
  programs and worksheets which may help your aquaculture program. If you feel these may
  have some application to your facility you should contact the originator of the
  application to obtain a copy of the program. These programs use accepted formulas for
  calculations involving cool and cold water fish culture. For those programs involving the
  application of chemicals, the user should use the program at your own risk and always
  apply the necessary precautions before application.
    Stand Alone Program
    SamCalc (V2.1)Written by Joe N. Fries, 500 E. McCarty Lane, San Marcos, TX. 78666  
  512-353-0011
    The Following Menu Items Are Included:
    Fish-hauling, Static Treatment, Flow-through,
  Length-weight, Contingency Table (2x2), Analysis of Variance, Experimental Design,
  Dissolved Oxygen Solubility, Injection Calculations.
    Fish Hatchery Mathematics (1986)Written by Darryl Bathel, French River Coldwater Hatchery, 5357 No. Shore
  Dr., Duluth, MN. 55804  218-723-4881
    The Following Menu Items Are Included:
    Weekly Feed Rate, Treatments, Raceway Capacity,
  Piper's Density and Flow Indices, Feed Order For Production Fish, Length of Salmonid
  Incubation, Daily Temp. Unit Calculator, Gas Supersaturation, Condition Factor (C),
  Distribution Tank Loading Guidelines, Descriptive Statistics.
    Aquadec (1989)Written by Chuck Adams and Rom Alderman
    University of Florida, Institute of Food and Agricultural Sciences, Bldg.
  120 Room 203, P.O. Box 110340, Grainesville, FL 32611-0340  904-392-7853.
    Aquadec is a budgeting and financial analysis software package that can
  provide information to the financial decision-making process of an aquacultural
  (commercial) business. A wide range of financial statements and other related information
  can be gathered by Aquadec for a one to five year period. Sensitivity analyses can also be
  performed on key management and market parameters.
    AquaSoftP.O. Box 853, Gresham, OR 97030
    AquaSoft has developed three aquaculture software packages for
  professionals who are their own "expert systems" and see microcomputers
  primarily as tools for increasing personal productivity.
    Aquacalc: This program allows the user to enter simple,
      language-like phrases to calculate the amount of chemical to add to produce a specific
      concentration, or convert from one unit of measure to another. The language-like interface
      provides easy access to over one hundred fifty conversion factors for over fifty commonly
      used units of measurement. Version 2.0 (PC compatible only) allows the definition and
      storage of up to twenty conversion factors and units.CARPplusl1: Computer assisted rearing projection takes another step
      forward with this newly enhanced level of CARPplus. This fish growth and feed projection
      program works for any species of fish, under any conditions, with user specified
      units that can be changed at any time. Six units of fish size make it possible that you
      may never again have to refer to a manual of fish culture to convert from length to
      weight. Three units for describing fish mortality, four units for growth, and three units
      for feed output combine to give the user tremendous versatility. Spreadsheet like input
      screens add to the ease of use.
      CARPplus: For not much more than you would spend for
      "free" public domain software you can have a copy of this second generation
      program for computer assisted rearing projection. CARPplus calculates required amounts and
      estimated costs of feed for any species of fish. CARPplus also schedules fish
      harvests, calculates feeding rates, and estimates amounts of space and water needed for
      groups of fish. Levee Mississippi Cooperative Extension Service, Mississippi State Univ.,
  Mississippi State, Miss. 39762 Levee calculates volume of earth to be moved during pond construction.
  User enters levee width, wet and dry slopes, finished elevation, survey elevations and
  length of levee segments. Output is in the format used by the Soil Conservation Service. Fishpond Construction Planning TemplatesTexas Agricultural Extension Service, Extension Computer Technology Group,
  Special Services Build. Rm 105, College Station, TX 77843
    This program lists some of the considerations in initial construction
  planning of fish ponds and allows estimation of excavation and dam volume (cubic yards)
  required for construction. Pond excavation volumes can be estimated for one pond or a
  series.
    AQUA MEDICNorth Systems, 4443 Nalani Court SE, Salem, OR 97302  503-364-3829
    AQUA MEDIC is a diagnostic program specifically designed to aid in the
  differential diagnosis of fish diseases. AQUA MEDIC allows veterinarians, fisheries
  professionals and scientists to enter a set of symptoms, physical findings, and water
  quality information. The program will then list the diseases associated with those
  attributes (in ranking order) according to the number of symptoms in common with each
  disease. Additionally the program allows the user to display a complete list of attributes
  and symptoms for any disease in the data base.
    Symptoms are entered quickly and easily by the first three letters of the
  name, by a code number, or by its classification. A listing of all of the diseases and
  attributes is included in the manual, and a new listing may be printed at any time after
  modifications or additions to the data base have been made by the user. A record form,
  including a complete listing of all attributes in the AQUA MEDIC data base, accompanies
  the program and enables users to input and analyze attributes efficiently.
    Spreadsheet/Database Worksheets
    Broodstock Egg Take CalculatorLotus 123 Worksheet
    Written by Lee Peterson, Peterson State Fish Hatchery, Rt. 1 Box 85A,
  Peterson, MN 55962  507-875-2625
    Lee has developed a very easy to use worksheet to determine the number of
  broodstock (male and female) needed to insure you will always have the correct number of
  eggs for any given year. For those fish hatcheries who need to continually adjust
  broodstock densities to maximize rearing space and to satisfy established egg production
  levels, will find this worksheet to be very useful.
    Carrying Capacity of TanksLotus 123 Worksheet
    Written by Steve Roberts, Washington Dept. of Game
    This worksheet calculates water inflow and space requirements based on
  pounds and numbers of fish. It also calculates pounds and numbers of fish based on water
  inflow and space. The formulas used in the worksheet are based on Piper's flow and density
  indexes.
    OXYGEN INJECTION BACKUP SYSTEM
    By: Gregory J. Fischer
    Hatchery Manager, Red Cliff Tribal Fish Hatchery
    The Red Cliff Tribal Fish Hatchery is
  now rearing Lake Trout and Coaster Brook Trout. This hatchery facility has been in the
  works for many years and is still not fully completed due to budget constraints. One of
  the hatchery's main goals is to establish a reliable and accessible source for Coaster
  Brook Trout eggs via a broodstock supply. To accomplish this goal the hatchery has two
  electric powered fifty horse submersible pumps capable of pumping between 500 to 1000
  gallons of water per minute.
    Last fall (1994) as the hatchery was nearing operating capability, it was
  evident that we were not going to be able to afford a backup generator in case of an
  electrical power failure. Due to the remote location of the facility and the history of
  power failure in years past, some type of backup had to be designed and installed. After
  speaking with many other hatchery professionals on our dilemma, we decided to set up an
  oxygen injection backup system.
    The oxygen injection system has many qualities Red Cliff's facility was
  looking for:
    1) It is relatively cheap and easy to install. 2) It is portable and
    easily relocated throughout the hatchery. 3) It is easy to operate at 2:00 a.m., when most
    power outages always seem to occur. 4) The system can be used to inject oxygen into tanks
    to increase productivity at a later date. 5) The system provides additional oxygen to fish
    in a standing body of water (raceway) when they need it most.
    This system also has some disadvantages:
    1) Does not remove harmful gases from the water, such as ammonia, during
    the power outage.
    2) Requires bottles of oxygen which must be bought, rented, or leased and
    refilled as necessary. 3) Only a temporary solution for a relatively short period of time
    depending on build-up of other gases in the system.
    Red Cliff ordered our oxygen system from Eagar Inc. of Utah
  (1-800-423-6249). They were extremely helpful and were able to custom design a system for
  treating a small number of tanks (<10) at a low cost of $300. This system consists of a
  flowmeter and regulator, 1 x 4 manifold with valves, aquapor diffusing hose, air hose and
  all the necessary fittings. Oxygen bottles were rented at a local supplier of welding
  materials. Installation was simple and completed in about one hour.
    In case of a power failure or pump shutdown, hatchery personnel are
  notified via an alarm system (MTAN Dec. 1994). After getting to the hatchery and assessing
  the situation, the oxygen backup system hose is lowered into the raceways and the oxygen
  is turned on. Oxygen flow is adjusted for each raceway depending on the amount of fish.
  Our tanks hold between 130 to 160 pounds of fish and the folks at Eagar felt that one
  liter per minute per raceway would be sufficient to sustain the fish. At that rate, one
  large oxygen bottle can sustain 10 tanks for approximately 10-12 hours. Of course, each
  facility is different depending on water conditions and species of fish, so it is
  advisable to contact Eager Inc. and other professionals before hooking up a system. Also,
  Red Cliff hatchery personal plan on monitoring the dissolved oxygen levels at the front
  and rear of the raceways during the use of the oxygen backup system and adjust the flow
  accordingly.
    Remember, this is only a short-term, low-cost remedy to a power outage and
  is not the solution. Red Cliff Tribal Fish Hatchery has plans to have a backup generator
  installed this summer, until then the oxygen injection backup system has given us a little
  more security and "piece of mind".
    Maximize
  Your Hatchery's Budget To Train Your Staff
    By: MTAN
    How often do you find yourself faced
  with the dilemma of having insufficient revenues to spend on your hatchery program? How
  frequently do you wish you had the opportunity to find good affordable training for your
  hard working staff? The MTAN would like to offer one option which may save your hatchery
  program training dollars that could be channeled to other areas.
    Fish hatchery supervisors from state and federal hatchery systems are
  excited about sharing information with Tribal hatchery workers. One of the ways this
  exchange is taking place is through an "On The Spot Hatchery Experience." If you
  feel that your staff would benefit from a training visit to one of these hatchery
  facilities, please give a call to the MTAN so we can help to made the arrangements.
  Depending on your specific needs, this kind of training could be one or several days in
  length and could even be spaced out over a broad cross section of the fish rearing cycle.
  The only expenses incurred to your program would be for travel, meals and lodging.
    Evaluation
  of Tank Shape and a Surface Spray for Intensive Culture of Larval Walleyes Fed Formulated
  Feed
    By: Alan Moore and Margaret PrangeIowa Dept. of Natural Resources, Rathbun State Fish Hatchery, Rural Route
2, Moravia, IowaAnd Robert Summerfelt and Richard Bushman, Dept. of Animal Ecology, Iowa
State University, Ames, Iowa
    (From
  the Progressive Fish-Culturest 56:100-110,1994)
The objectives of this study was to examine the effects of different tank
  characteristics on intensive culture of larval walleyes reared on only formulated feed.
    To improve reliability and success of
  maintenance stocking of walleyes, many natural resource agencies are giving more attention
  to large fingerlings (> 100 mm, typically 100-150 mm, total length) as an alterative to
  stocking yolk-sac larvae or small fingerlings. Currently, a tandem procedure involving
  pond culture first, then tank culture, is used to rear almost all large fingerling
  walleyes. Typically, fingerlings are reared from fry in a pond environment to total
  lengths of 35-50 mm, then harvested and transferred to tank or raceway (i.e., intensive
  culture) facilities, where they are trained to eat formulated diets and reared to total
  lengths of more than 100 mm. Because of the mortalities that occur in pond production and
  when the pond-reared fingerlings are trained to formulated feed, totally intensive culture
  is an attractive alternative. Intensive culture efforts to raise larval walleyes on
  formulated diets, however, have met with limited and inconsistent success.
    Failure of gas bladder inflation in larval walleyes is considered the key
  factor in poor survival to 20 d posthatch. Noninflation of the gas bladder usually results
  in mortality before 30 d posthatch. Fry with uninflated gas bladders swim poorly and
  expend extra energy to maintain position in the water column. These weakened fish become
  stressed easily, and mortality is high when they are moved between tanks or transported
  for short distances in bags. Fry with uninflated gas bladders probably are more vulnerable
  to predators and less capable of capturing prey after stocking. Tank design is regarded as
  important to survival and gas bladder inflation of walleye.
    Walleyes are assumed to inflate their gas bladders by gulping air at the
  air-water interface. Larval walleyes go through a stage of pushing their snouts upwards
  against the surface film, presumably to gulp air. Walleyes reared in tanks with a surface
  exit for oil and debris (at the surface film) have higher gas bladder inflation rates than
  do walleyes reared in tanks with only a subsurface outlet.
    The present study was an effort to advance the technology for intensive
  culture of larval walleyes, especially by finding ways to improve gas bladder inflation.
  Experiments were performed to compare rearing success of larval walleyes held in a
  cuboidal tanks (T-1) and of those held in a deep cylindrical tanks (T-2). These
  differently shaped tanks also differ in flow pattern. The cuboidal tanks have an upwelling
  water circulation pattern that resuspends feed to maintain a high feed particle density.
  We modified the screen of the original design to create a surface drain. The cylindrical
  tanks have a circular flow pattern. Both tank types were equipped with surface sprays as a
  means to clear the surface of oil, feed, and debris. A preliminary evaluation of the role
  of surface spray in gas bladder inflation was also undertaken (T-3).
    Results
    Comparison of Cuboidal and Cylindrical Tanks:In experiment T-1, survival and viability were significantly greater for
  walleyes reared in cuboidal tanks than for those in cylindrical tanks. The gas bladder was
  inflated in 100% of the fish in the cylindrical tanks and in 86.7% of the fish in the
  cuboidal tanks, but this difference was nonsignificant. Fish reared in cuboidal tanks were
  significantly longer than those reared in cylindrical tanks.
    The 11.4% difference in survival between cuboidal tanks and cylindrical
  tanks in experiment T-2 was not statistically significant, but gas bladder inflation (GBI)
  and viability were significantly greater for fish reared in cylindrical tanks than for
  those in cuboidal tanks. Fish reared in cylindrical tanks were significantly longer than
  those in cuboidal tanks.
    In experiment T-3, survival, GBI, and viability were significantly higher
  for walleyes reared in cylindrical tanks with surface sprays than for those in cuboidal
  tanks with surface sprays. Differences in mean length of fish between the two tank designs
  were not statistically significant.
    Comparison of performance in tanks with and
      without a surface spray:Differences in survival, viability, and mean length for fish in tanks with
  and without surface sprays could not be statistically compared because of the lack of
  replicates. However, in cylindrical tanks, survival, GBI, and viability were substantially
  greater in the two tanks with surface sprays than in the one tank without a surface spray.
  In the cuboidal tanks, survival and viability also were substantially greater in the two
  tanks with surface sprays than for the one without a surface spray, but GBI was slightly
  greater in the cuboidal tank without a surface spray.
    Discussion
    Zitzow reported higher survival and GBI rates for larval walleyes reared
  to 29-32 d posthatch in cylindrical tanks than for those in cuboidal tanks. Viability
  calculated from their data on survival and GBI was only 23.9%, whereas viability was 60.8%
  in the same tanks in experiment T-3 of the present study. In the present study, GBI and
  viability were considered the critical measures of performance, and performance was better
  in the cylindrical tanks in two of the three experiments (T-2 and T-3).
    In the present study, survival of larval walleyes to 15-25 d posthatch
  ranged from 3.8 to 68.2% over all three experiments, compared with an average of 17.5% in
  prior studies. The GBI in the present study ranged from 71.5 to 100.0% in the three
  experiments. Survival was significantly higher in the cuboidal tanks only in experiment T-
  1, when a feed bridging problem in both the cylindrical and cuboidal tanks kept feed from
  being dispensed at the desired times. The upwelling flow pattern in the cuboidal tanks,
  however, maintained higher particle densities and thus made more feed available to fish.
  Therefore, the higher survival in the cuboidal tanks in experiment T- I may be attributed
  to the greater starvation of fish in the cylindrical tanks as a result of the feeder
  problem. Survival was higher in the cylindrical tanks in experiment T-2 and significantly
  higher in these tanks in T-3.
    The results of this study represent improvements over previous efforts to
  rear larval walleyes on formulated feed. If these results can be repeated, they will
  represent a substantial advancement in the intensive culture of larval walleyes. Other
  investigators have used live food (brine shrimp nauplii or zooplankton), formulated feed,
  or combinations thereof. We think that the surface spray influenced the success of the
  present study. In the cylindrical tanks (T-3), all performance values were greater in the
  two tanks with a spray than in the one tank without a spray; however, in the cuboidal
  tanks, GBI was greater in the one tank without a spray than in the two with a spray
  (although viability and survival were higher in those tanks with a spray).TANK
  CULTURE TECHNIQUES FOR REARING WALLEYE FINGERLINGS
    By: Eric E. Moodie, Department of Biology, University of Winnipeg,
  Winnipeg, Manitoba, R3B 2E9 Canada 204-786-9435
The system is based on the idea of growing walleye from egg through to
fingerling size or larger entirely inside a hatchery.Our research group has been developing
  a commercially feasible walleye culture system for the past several years.This kind of culture offers several advantages; the fish can be reared in
  a disease-free environment, the operators rather than Mother Nature control environmental
  conditions, ideal year-round rearing temperatures can be maintained, the fish are reared
  on prepared feed throughout their lives so feed conversion problems are avoided, and the
  fish never need to be moved from a pond to a tank at any point in their lives.
    The main obstacles to successful walleye culture have been mortality
  resulting when hungry larvae cannibalize each other and problems due to poor swim bladder
  inflation. (For a report on swim bladder inflation problems in walleye see the article by
  Kindschi and Barrows in the March, 1994 issue of the MTAN Newsletter.) We have been able
  to reduce cannibalism to an acceptable level by supplying plenty of high quality feed
  (BioKyowa B400 and C700) in carefully controlled quantities. We make sure there are always
  at least 100 food particles per liter of tank water. Normal swim bladder inflation depends
  on good water quality so we reduce the level of recirculation and increase the supply of
  new water while inflation is taking place.
    We feel that good hygiene is another important factor in successful
  intensive culture. At the start of each culture cycle we disinfect the entire system with
  a 10% solution of Prepodyne. After the eggs are fully hardened they are disinfected with a
  10 minute immersion in a 1% solution of Iodine before being placed in the incubation jars.
  Our water supply is drawn from a deep well which also reduces the risk of disease
  organisms getting into the tanks.
    During the hatching period we let the larvae accumulate in a 600 L holding
  tank after they leave the incubation jars. The outlet of the holding tank is provided with
  a removable screen with a mesh size of 500u and an area of 2200 cm2. When
  hatching begins we increase water flow through the jars and the holding tank to help move
  larvae out of the jars and to flush away oils and other wastes. Larvae stay in the holding
  tank until about 1 day before the yolk is used up. We siphon out empty egg shells and dead
  larvae once or twice a day during this period. The outlet end of the tank is darkened to
  encourage the larvae to avoid that region and simplify cleaning the screen and removal of
  dead larvae and egg shells.
    Larvae are transferred from the holding tank in a small 125u mesh nylon
  net. Groups of about 1,500 larvae are caught and gently poured through a funnel into a 50
  ml graduate cylinder. We estimate larval numbers volumetrically by draining most of the
  water from the netted larvae. We determine the number of larvae occupying 2-3 ml of a 10
  ml graduate cylinder by actual counts of several samples. Appropriate quantities of larvae
  are then placed in the rearing trough which is at the same temperature as the holding
  tank. After the larvae are moved to the rearing trough the temperature in the trough is
  raised to 20 C over the next 48 hours.
    The rearing trough has a capacity of 2.6 m3. Until the larvae
  begin to feed, the rate of water flow in the trough can be low (77 L/minute [1.8
  exchanges/hour]) because the larvae are small and water quality is easy to maintain as
  long as no food is entering the system. After feeding begins, we increase the flow rate to
  123 L/minute (2.8 exchanges/hour). This produces a velocity of about 8 cm/second at the
  surface which is enough to delay the sinking of food and maintain adequate water quality.
  The trough is designed to keep the food where the larvae can make use of it. Walleye
  larvae will not take food from the bottom or from the water surface. We get around this
  problem by pumping water into the trough through a perforated pipe running along the
  bottom. The flow of water from the perforated pipe lifts sinking food so that the larvae
  can "capture" it. Water leaves the trough via screened outlets along the back of
  the trough. The screen has a mesh size of 500um which is sufficient to keep the larvae and
  most of the food inside the trough. The boxes are removable and can be opened for
  cleaning. It might seem to make sense to use a slightly larger mesh in order to allow
  uneaten food to escape, however, that would just mean having to provide more food (which
  is very expensive) to supply the density needed to keep cannibalism under control.
    Waste water from the trough flows by gravity to a particle separator which
  removes fish and food wastes which pass through the outlet screens. Water is then pumped
  to an inline heater and on to a down-flow submerged gravel biofilter. After filtration the
  water goes to an aeration tower consisting of a 2 m length of 30 cm diameter PVC pipe. The
  tower was built on-site and contains a series of internal baffles which break up the water
  as it falls down the pipe. The tower restores the oxygen content of the culture water to
  about 94% saturation or an oxygen concentration of about 8.4 mg/L at 20 C. Water from the
  tower collects in a small reservoir from which it is pumped back to the rearing trough.
  Pumping is necessary at this point in order to generate the water pressure which drives
  the water circulation in the rearing trough.
    These components together with additional tanks are also used for juvenile
  grow-out after 30 days. The rate of water flow to the rearing trough is critical to its
  successful operation; we keep it under 70 L/m. The upwelling flow which is necessary to
  prolong the suspension of food has to be managed carefully because excessive current is
  harmful to the larvae. We think surface water velocity should be under 10 cm/second. This
  velocity can be achieved by changing the angle at which water is ejected from the
  perforated inlet pipe and by adjusting a valve on the main supply line to the trough.
    Interruptions to the food supply and drops in the dissolved oxygen
  resulting from component failures can quickly kill large numbers of larvae. To limit this
  possibility, the system is backed up by alarms triggered by high temperature, low water
  levels, or a pump failure. Compressed oxygen is available if electricity or water flow can
  not be restored immediately.
    The system requires a maximum flow rate of about 7 m3/day. We
  maintain water temperature at 20C during the 30 day culture period. We keep dissolved oxygen
  concentration close to the saturation level or at least over 65% of saturation. Un-ionized
  ammonia concentrations are held below 0.1 mg/L. Total ammonia concentrations do not exceed
  0.7 mg/L. These oxygen and ammonia levels are easy to maintain at the larval and feed
  densities we use. Declining oxygen levels can be corrected by more cleaning, backwashing
  of the filter, and flushing of sludge in the trap of the particle remover.
    During the period when the swimbladder is inflating we supply new water at
  a rate of 6.3 m3/day. This high level which is equivalent to 2.5 exchanges of
  the entire system volume per day, reduces the accumulation of surface oils and films which
  inhibit swim bladder inflation. For the remainder of the larval culture period the new
  volume is reduced to 0.7 m3/day (equivalent to an exchange of the system every
  2.5 days).
    We used to begin supplying feed shortly before the larvae would accept it.
  Now we think swim bladder inflation occurs very soon after the yolk is consumed and that
  the process is completed quickly under ideal conditions. Better swim bladder inflation may
  result if feeding can be delayed until the level of inflation reaches 80%. We feed the
  larvae BioKyowa B-400 feed for the first 7 days. Larvae remain on B-400 feed longer if
  necessary to ensure all individuals are ready to shift to larger (C-700) feed. This gives
  smaller fish a chance to catch up in size to larger ones and may slow down the growth of
  larger ones, so that size variation will be reduced. The automatic feeders we use are
  custom built and capable of reliably releasing about 0.06 g of B400 food per delivery.
  Five to ten feeders per trough will ensure even food distribution. If ten feeders are
  used, each will need to deliver at about 2 minute intervals to maintain the correct food
  particle density in the water. The larvae are held under continuous illumination and fed
  day and night to reduce cannibalism resulting from food deprivation which occurs if the
  lights and feeders are shut off during the night.
    The food ration is based on supplying enough to maintain a density of at
  least 100 particles/L. We monitor food particle density regularly and adjust the output of
  the feeders as necessary to maintain the correct food density within the trough. The same
  procedure applies after the diet is changed to C700 food. It is important to note that we
  base the feeding rate not on the number of fish present, nor the density of fish, but
  rather on maintaining approximately 100 particles per liter in the water column at all
  times.
    Most of the labor involves cleaning. The system relies on supplying an
  excess of food which must eventually be siphoned from the trough at least once or twice a
  day. The exit screens also have to be removed and cleaned once or twice daily. By the time
  the fish are receiving C700 the sides and bottom of the trough need to be brushed or wiped
  to remove films which build up there (solid kitchen scrub pads are perfect for this job).
  Sludge traps in the particle remover and elsewhere in the system also need to be drained
  every 2-3 days. A major objective of our research has been to reduce the labor
  requirements which make up a large portion of aquaculture production costs. We have
  therefore tried to develop a system that is easy to operate. The system I have described
  requires 5 hours of labor per day.
    Other routine chores involve monitoring water quality, swim bladder
  inflation, feed supply and particle density, level of feeding, growth rate, general
  well-being of the larvae, and the extent of cannibalism.
    We have produced from 23,000 to 33,500 thirty day old juveniles from
  starting densities ranging from 19 to 56 larvae/L. Once the juveniles reach the age of 30
  days, their survival rates improve tremendously and their culture becomes relatively
  straightforward. We have released over 20,000 6 inch fingerlings into several lakes in
  Manitoba and have successfully held others in the hatchery for 5 years. The modular design
  of the system makes it possible to scale up production for larger numbers simply by adding
  additional troughs and associated components.
    Pond
  Production of Fingerling Walleye at Garrison Dam National Fish Hatchery
    By: John E. Call, U.S. Fish & Wildlife Service, P.O. Box 530,
  Riverdale, N.D. 58565
    The Garrison Dam National Fish Hatchery, located in central North Dakota,
  has been operated by the U.S. Fish and Wildlife Service since 1964 for the production of
  sport fishes. Up to 10 million walleye fingerlings are produced annually. Northern pike,
  saugeye, bass, paddlefish, trout, and salmon are also cultured. The hatchery is situated
  below the dam of Lake Sakakawea, which serves as its primary water source. There are sixty four 1.5 acre
  (0.61-ha) ponds. All ponds are equipped with outside kettles.
    Walleye eggs are obtained from wild stocks at Devils Lake and Lake
  Sakakawea in mid-April. The hatchery water supply at this time of year is approximately 35
  F (2 C), and must be heated by boilers to provide more suitable water temperature for egg
  incubation. Manipulating water temperatures enables us to control the egg incubation
  period length and double crop some rearing ponds, producing both northern pike and walleye
  fingerlings in the same rearing ponds. This is possible because northern pike spawn
  earlier in the year than walleye, and northern pike fingerlings require a relatively short
  rearing period. Fry survival from eggs incubated over 40 days may be reduced, but it's a
  small price to pay for enabling us to double crop ponds.
    Pond filling and egg hatching are coordinated by using a spreadsheet which
  predicts hatching dates based on cumulative temperature units. Pond filling begins
  approximately May 6, at which time the water temperature is near 50 F (10 C) and prolonged
  periods of cold weather are normally past.
    Pond fertilization is based on information gathered by trial and error
  over 30 years. For many years alfalfa hay was chopped and added to the ponds. It performed
  well as a fertilizer, but was labor intensive to handle and spoiled quickly in storage. In
  1992, after several years of testing, we switched to alfalfa meal. The small particle size
  allows rapid decomposition and it does not plug screens during pond draining.
  Additionally, because it is stored in a bin, there is no spoilage. A grain box mounted on
  a trailer is used to transport the alfalfa meal to the ponds. The meal is broadcast into
  the pond by an auger projecting out over the pond water as the truck is slowly driven
  along the dike.
    Fertilization begins immediately after pond filling using 133 lbs/acre (60
  kg/ha) of alfalfa meal per application. Ponds are fertilized once every 3 days.
  Fertilization is discontinued 7 days before the anticipated draining date. Pond
  fertilization schedules are generated by a computer program and dissolved oxygen levels
  are monitored closely. If dissolved oxygen levels fall below 5 mg/l at sunrise, when
  measured 1 ft(30 cm) above the pond bottom, fertilization ceases until oxygen levels
  recover.
    The maximum amount of organic fertilizer that can be safely used without
  oxygen depletion will be influenced by many factors, such as water temperature, natural
  soil fertility, cloud cover and the amount of phytoplankton present. No attempt is made to
  adjust fertilization based on plankton tows, pond color or other criteria. Cost of alfalfa
  meal for pond fertilization is approximately $75.00/acre ($185.00/ha).
    Walleye fry, 24 to 48 hours old, are stocked 9 days after the pond has
  started to fill with water. Fry are enumerated by water displacement (220/ml) and are
  transported to the pond in 5 gal. buckets which are equipped with a stone diffuser through
  which oxygen is bubbled during transport. Stocking rate varies from 166,000/acre
  (410,000/ha) to 200,000/acre(494,000/ha). The culture period for walleye fingerling is
  normally 29 days, but abnormal water temperatures can alter this period by as much as
  seven days.
    As the anticipated draining time approaches, fish are sampled by seining
  to determine fish size and condition. When fish reach 1.25 inches (32 mm) total length,
  the pond is drained. If successive sampling 3 days apart indicate that the fish have not
  grown, a food shortage probably exists, and the pond is drained before fish condition
  deteriorates. We believe that survival after distribution is determined as much by fish
  condition as it is by fish size.
    Average production for the last 3 years has been 136,000/acre (336,000/ha)
  of 1700/lb fingerlings. Average survival for the same period was 76%. As the pond bottom
  is exposed during the draining process, it is seeded with annual ryegrass using a
  broadcast seeder at the rate of 33 lbs/acre. This is done to increase soil organic matter
  and to help control soil erosion.
    Information gathered during the growing season is stored in a computer
  database file as it occurs. We have found this to be a convenient way to not only record
  information but to later analyze the data we collected.
    ENVIRONMENTAL GILL DISEASE
    By: Terrence Ott, La Crosse Fish Health Center, La Crosse, WI
    This is not a new disease, but a very
  common bacterial problem experienced by many culturing fish in a closed or open system.
  The disease more commonly known as Bacterial Gill Disease or simply "BGD" is
  most devastating to fry and fingerling fish.
    Environmental gill disease is a complex disease in which more than one
  type of filamentous bacterium may be involved. Diagnostic cases of environmental gill
  disease have isolated Flexibacter sp. and Flavobacteria sp. from the gills
  of infected fishes. These opportunistic soil and water born bacteria are present in most
  waters which harbor fish. The only way to eliminate these facultative bacteria from a
  water source would be by a process called ozonation. Water entering a facility would pass
  through a machine emitting ozone at levels appropriate to kill these microorganisms,
  before they made contact with the fish. A costly process and one that is not always 100
  percent effective.
    All freshwater species of fish are susceptible to environmental gill
  disease. However, various species of fishes differ in resistance to this disease. Cultured
  salmonids are especially susceptible to this disease and the disease becomes of great
  economic importance in salmonid culture.
    Environmental gill disease develops when gill irritants are present in the
  water source at concentrations high enough to damage gill epithelium (skin covering the
  gills). Gills which become irritated produce a condition called hyperplasia. This occurs
  when epithelial cells (skin cells in the gill) increase in number in response to the
  irritant. These excess cells are not lost as rapidly as they are formed, so a thickening
  of the gill membrane develops at the distal end of the gills. As the gill surface
  increases in size it obstructs flow of water between them so that hemoglobin in the blood
  cannot be oxygenated.
    Overcrowding of fishes, especially when accompanied by reduced water
  exchange, is one of the major causes of gill irritants. Another very common gill irritant
  occurs during this time of year when fry are being fed fry feeds. These fine particulate
  feeds can irritate and clog gill membranes encouraging the development of environmental
  gill disease.
    Salmonids affected with environmental gill disease are usually lethargic
  and refuse food, "ride high" in the water and orient toward the incoming water
  supply. They may also be spaced equidistantly from one another, have labored opercular
  movements, and gills will appear excessively slimy with whitened tips.
    Clinical signs, behavior, and bacterial isolation can be used to diagnose
  environmental gill disease. Measuring the water chemistry parameters to determine the
  source of gill irritant may also be helpful in the diagnosis.
    Treatment of environmental gill disease should be initiated as soon as
  possible. The longer the delay before starting a chemical treatment can result in
  extensive gill hyperplasia and high fish mortalities. The disease is best controlled by
  eliminating the cause of gill irritants in the water column and treating the fish with the
  low regulatory chemical sodium chloride containing no anti-caking agents at a 2%
  concentration. A dip or standing bath treatment for 15 to 30 minutes and repeated daily
  for 3 to 4 days should eliminate the bacteria buildup on the gills of the fish.
    Hatchery Tip
    By: MTANNow that we are approaching the
  electrical "power outage" season, you may want to consider how you would
  maneuver within your hatchery facility should the lights go dim.
    One solution that works for the MTAN is to install a rechargeable
  flashlight just inside the entry door to your hatchery. We're referring to the kind of
  flashlight that you keep plugged into a wall electrical outlet. The flashlight will
  continue to be fully charged and readily available when you need
  it. Should you choose to adopt this same safety measure for your home use, be sure to
  instruct the kids to always return the light to its recharging station (good luck
  with that one).
    
    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.
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 Last updated:
      November 19, 2008
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