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Ashland NFWCO
 Midwest Region
 Dedicated
To The Tribal Aquaculture Program September
1999 - Volume 29
  **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: Fish Truck Goes to LCO Bird Netting Winter Pond Management Fish Health Hatchery Tips  Fish Truck Goes to LCOBy: MTAN Frank
    Stone (Ashland FRO) arranged for the
transfer of a surplus 1986 fish distribution truck (from the
Welaka NFH, Florida) to be reassigned to the Lac Courte Oreilles
(LCO) Indian Reservation. The truck is equipped with a 1,000
gallon fish tank plus oxygenation and water recirculating life
support systems. The LCO Tribal Fish Hatchery program paid the
travel expenses for Frank to fly to Florida and drive the vehicle
back to northern Wisconsin (1,650 miles). The Tribe will use the
vehicle to help transport hatchery fish to various stocking sites
near the Reservation. Over the past nine
years the Ashland FRO has arranged for the transfer of several
hundred thousand dollars worth of fish distribution trucks, fish
hatchery equipment, generators and vehicles to Tribal resource
programs in Region 3. By making surplus equipment transfers like
this possible, we not only prolong the intended use for the
equipment but also help free up funds by the receiving agency to
be used in other natural resource areas.  Bird NettingBy: Greg Faulkner, Fish Farming
News, January/February 1999 It looked really good. It went up easily and it
was very inexpensive, maybe 4 cents a square foot. The mesh was
small enough that even the kingfishers couldn't get through. Then
came the rain and the wind. It took about 15 minutes for 3,500
square feet of that light netting to shear itself apart. It just
fell in shreds. This fish farmer's
experience with ultralight bird netting was not a good one. The
bursting strength of the netting was adequate enough, but he
hadn't accounted for the effects of flex and wind resistance.
Hanging netting in the air is quite different from placing it in
water. Netting hung in the air is at the mercy of gravity and
wind. Burst strength, which is tested by placing an even strain
all along the meshes, has little meaning when a limb or pile of
leaves accumulates on the net and wind resistance increases by
200%-300%. The whipping action of erratic winds coming from
different angles causes the material to flex and twist. With that
combination, the netting can just break. Is this to say that the
farmer's choice of material was wrong or that the netting is
ill-suited for bird cover? Absolutely not! What he could have
done to save his cover was as simple as fastening in several
Aguy@ ropes to suppress movement and support the net. A
3/16" braided line every 12' or 15' would have kept the
netting from "whipping" itself back and forth in the
wind. Debris collection and the increased wind resistance it
produces would have been partially supported by the guys. Extruded Extruded netting comes
in numerous thicknesses. The thicker and heavier the product, the
more rigid it is and the greater the expense. These heavier sizes
are the backbone of the cage industry and can outlast most nylon
netting in the water. The flat, offsided joint that holds the
extruded meshes to one another is not a knot. It is simply a
melted joint. Burst strengths on the lightweight materials run 20
pounds or so. In the heavier densities, burst strength runs into
the 100-pound range. In the lighter, bird
netting sizes, the netting is adequate to support itself but
requires some underlying guy lines if it is going to be stretched
over a large area. One such ultra lightweight extruded net with
guy lines in place every 8' has remained undamaged for 3 years in
an outside environment. Knitted Another popular
material often seen in fruit tree protection is a loosely woven
knitted material. The samples I have worked with were all
polypropylene or polyethylene material. They were ultra light and
the material came in gigantic rolls of hundreds of feet long by
30'-40' wide. This material is very loosely woven as evidenced by
the amount of space in between the fibers. You can see daylight.
If pulled, it loses its shape quickly and can be torn with less
than 20 pounds of strain. Cost-wise, it is the most inexpensive
of all materials, perhaps 2-3 cents a square foot. Be aware that you will
have to contend with a lot of sagging in the material if you try
to span a large area without supports. It can be used to cover a
small pond or tank quite easily and is often used in applications
where netting must be rolled back frequently to access a tank. Knotless
Polyethylene An offshoot from the
commercial seine industry, this material has just found its way
into the bird predation scene. Two strands of polyethylene are
twisted and "z" locked at the joining. It can be used
as a diamond or a square-shaped netting. Square-shaped netting
has less wind resistance and produces less sag when hung up in
the air. Knotless poly (brand name K-Less) can be stretched over
a greater span than most other nettings. In some applications it
can be pulled tightly over a 65'-75' expanse with little or no
sag. Bursting strength of the lightest of the materials is well
over 70 pounds and the medium weight materials can hit 200. That
means guy lines can be placed 50'-60' or more apart. K-Less comes in
multiple sizes from 1-1/2" to 12" mesh. it can be
manufactured in diamond or square mesh form. Cost is in the 5-9
cents a square foot range. In a 1995 experiment, a
13,000-square foot pond cover was hit by 75 mph winds twice in
one year along with two ice storms. No damage was reported. Knotted Poly or
Nylon The most widely
accepted netting material has always been the knotted version. In
this knotted form, either poly or nylon can be pulled across
great expanses. Shortcomings of nylon are that it will absorb
water and sag and that it must be removed and treated with net
coating from time to time. Knotted poly is not affected by water
absorption, but ultraviolet (UV) rays can be a problem. In a
black or dark blue color, poly is able to tolerate years of UV
exposure. In lighter colors such as green or orange it can wither
very quickly. These knotted nettings
are relatively inexpensive and can be found in almost any net
shop or netting supply house. Prices are from 4-8 cents a square
foot. There are numerous mesh sizes of each and these two
nettings have probably the widest array of twine thicknesses of
any of the nettings on the market. At a cost of 8 cents, #12
2"x2" square mesh can be used to cover extremely large
open areas with just a few upright pvc poles in the center of the
net. Monofilament Used for years in the
commercial gillnet and cast net fisheries, this material is
ultralight and readily available. Its tensile strength is
adequate, although I wouldn't put too much strain on it without
supports. The stiffness of monofilament makes it ideal for sites
with lots of debris and it cleans itself rather easily. While
available in colors, monofilament is translucent and has little
UV protection. In constant sunlight it will break down. One
consideration is that it is so clear that it can be a hazard to
some birds. Mono comes in a variety of mesh sizes and depths.
Costs range from 5-7 cents a square foot. Bird Netting
Terminology Sag:The amount
of drooping a net will do when it is in place up in the air. Sag
can only be reduced by tightening the webbing or placing guy
lines. Diamond shaped material will always have greater sag than
will square shaped material. Flex: The amount
of bending a netting can take either from water action or wind.
Tensile and burst strength mean nothing here. If the material
cannot flex, it will snap off, not pull apart. Ultraviolet (UV):
This is nature's own microwave oven. Generally speaking, draw a
line east and west through Memphis, TN. Above this line UV is
weaker and below it you had better watch the nettings' colors. Catchability: If
a bird did hit your net, what would happen? Catchability refers
to how much entangling capability your net has. Will the bird
just bounce off or will it gets its feet or wings entangled. Burst strength:
This is the gauge used to test at what amount of pull a netting
will break. It is always done with even rows of meshes under a
controlled environment. It does not take into account sudden
twists or jerks caused by debris or wind. Diamond mesh:
Just as it says, a four-sided, diamond-shaped mesh. Square mesh: A
four-sided box-shaped mesh. Square mesh are generally cut from
diamond mesh in knotted and K-Less netting. Structure: The
amount of poles and supports needed to hold up a bird net. This
includes the guy lines underneath the net. Chafe resistance:
The amount of wear and tear a netting can take as it slides back
and forth along guy lines or frame work. Retractable:
Some types of nets can be made in such a style that the entire
net can be slid from one end of the pond to the other. Nesting: Some
small mesh bird netting will offer an attractive nesting area to
some birds. Periphery cover:
Some first-time net users forget that cranes and egrets often
walk into a pond. It is important to have your cover extend
around your entire pond edge as well as up in the air.Most birds
that do become entangled in your net do so by getting their feet
caught first. Too much sag in your net will get you in trouble
with trapped and dead birds.  Winter Pond Management As water temperatures fall and daylight hours
get shorter, out door activities turn from fishing to other
pursuits such as hunting and football. Many of the routine
activities associated with maintaining the pond
cease--fertilization is no longer needed, and weeds tend to die
back. A pond owner could believe management isn't important
during winter and that the pond can be forgotten until early
spring, but that's not the case. Winter pond management is less
critical to the function of the pond than summer management.
However, for activities such as harvesting and fertilization,
winter provides opportunities to make changes to the pond that
result in higher fish production. In established ponds,
fall and winter are the best times to correct structural defects.
Water level can be drawn down to allow maintenance of piers,
boathouses, and fertilizer platforms without the risk of oxygen
depletion. Also, since fish are less active and feed less in cold
weather, they can be concentrated in less water without harming
populations. With water levels down,
shallow shorelines can be deepened, reducing the amount of pond
area that is less than 2 feet in depth. Deepening the edge of a
pond can be done with tractors or other earthmoving equipment
once the exposed pond bottom is dry. Deepening reduces the chance
of too many pond plants growing in shallow water and causing
problems during summer. Drawdown can reduce
weed problems in the pond even without deepening pond edges.
Drawdown allows the pond bottom to dry and the cold weather will
freeze the plants and their roots. To be effective, the drawdown
must be maintained through the coldest period of winter. Exposing
the bottom of the pond for three consecutive winters may be
necessary to control some problem weeds. Don't use drawdown to
control needlerush, Southern watergrass, or hydrilla. These
plants can be spread throughout the pond by drawdown.  Fish HealthBy: George W.
Klontz, M.S., D.V.M., Technical Services Advisor, Nelson and
Sons, Inc., Moscow, Idaho In late winter and early spring, when water
temperatures begin to increase, these organisms frequently emerge
from their winter hibernation and cause problems for their fish
hosts. The problems are often quite serious because the defensive
mechanisms of the fish are still quite depressed because of the
low water temperatures. In addition, the nutritional status of
the fish, in many cases, is also compromised from the winter
conditions. Thus, both conditions favor the reproductive cause(s)
of the organisms. In many cases, to administer a chemical such as
formalin at this time could cause more problems than it would
cure because of the reduced capability of the fish to withstand
such an activity. When considering the
use of formalin to remove external protozoa, metazoa, or
bacteria, the following process should be followed to insure
optimum safety for the fish and optimum efficiency in removing
the offending organisms: 1. Do not feed the fish
during 24-36 hours prior to the treatment. 2. Conduct a bioassay
to determine the safe and effective concentration of chemical.
This process is usually not done because of its perceived
complexity. However, its omission from the treatment process is
probably the chief reason for the chemical-related fish kills. Examine the gills and
pectoral fins of a few (2-3) fish for external organisms. This
step may be omitted if one assumes that organisms are present
because clinical episodes have occurred in the past. Prepare at least 3
concentrations of the candidate chemical in 15-20 l of water. For
example, if formalin is to be used, prepare concentrations of
1:4,000; 1:5,000; and 1:6,000 in water from the pond to be
treated. Provide aeration using airstones and an aquarium pump. Place 2-3 clinically
healthy fish and 2-3 not-so-healthy ("screen-hangers")
fish into each container. During the ensuing 60 minutes, observe
the fish for signs of distress. At the end of 60
minutes, examine the gills and pectoral fins of the fish for
organisms. This step is often omitted, but it should not be. The resultant
concentration of chemical to administer is that which does not
compromise the well-being of the fish and does kill the resident
organisms. 3. While the bioassay
is in progress, the dimensions of the water volume and the water
inflow of the pond to be treated should be determined with as
much accuracy as possible. Obtaining the water
dimensions of most ponds is quite straightforward. In cases where
the pond has an irregular shape, time should be spent in
acquiring the proper measurements. The determination of
water inflow can, in many cases, be described as a S.W.I.G. (a
Scientifically-Wild Intuitive Guess). There are many methods to
determine pond inflow. The simplest, in my opinion is the Filling
Time Method. In this method, the water level is reduced by, for
example, 25 cm. At that point, begin recording the time required
for the water depth to increase 20 cm. Divide the volume (liters)
replaced by the time (minutes or seconds) to determine the LPM or
LPS water inflow. In most raceway
systems, the 60-minute continuous drip is the most effective and
safe method to administer the majority of water-administered
chemicals approved for treating diseases of foodfish. When
calculating the correct water volume to be treated, the volume of
water displaced by the fish should be considered. In the case of
most salmonids, 1.018 kg fish displaces 1.0 l of water. Many fish
farmers are often quite surprised to note that, in high density
conditions, perhaps 1/3 of the water volume is displaced by fish.
To treat such a condition would result in a significant increase
in chemical concentration and, perhaps, a significant unnecessary
mortality. In circulating water
systems; e.g., circular ponds or rectangular circulating ponds,
the most effective treatment method is a combination of the bath
and drip methods. The proper amount of chemical is spread in
diluted form throughout the pond. Also, a 60-minute drip system
is set to replace the chemical discharged during the 60-minute
period. In applying
water-administered chemicals to prevent and/or treat diseases in
fish, there are a few caveats to be observed. The major
consideration is the nature of the chemical. The majority of
water-administered chemicals for fish were not developed and
marketed for such use and as such the manufacturer of the
chemical assumes no liability for problems occurring in such use.
Secondly, the margin of safety; i.e., the "distance"
between killing the offending organism and negatively affecting
the fish, is often minimal. Thirdly, the efficacy and safety of
the majority of chemicals used in fish farming are affected by
the physical and chemical nature of the water. Thus, dosages
recommended in texts and magazine articles may not be suitable
for use in all water systems. Fourthly, prior to using a
water-administered chemical, all calculations should be validated
by a second person. In summary, to a large
degree, the statement is true that water-administered chemicals
have killed more fish than the organisms they were supposed to
kill. It can be a very hard but unnecessary lesson to learn.
Perhaps the foregoing presentation will prevent some future
unwanted problems and the fish farmer can spend more time indoors
in front of a warm fireplace instead of out in the cold removing
morts from the screens.  Hatchery TipsBy: Aquatic Eco-Systems,
Apopka, FL. Shipping
Live Fish The art of shipping live fish has been mastered
by the tropical fish industry who ship fish around the world.
Before the fish are packed, many factors must be considered.
Questions you need to address include: Are warm water fish being
shipped to a cold climate or vice versa? What is the duration of
the shipment before the box will be unpacked? Are the fish
aggressive and need to be isolated, or can they be packed as a
group? Do they have sharp spines which require double or triple
bagging? Eight and one-half
techniques commonly used for shipping live fish in commercial
quantities include: 1. Only ship healthy
fish that have not been fed for 2-4 days. 2. If the fish are cold
tolerant, such as trout, blue gill, striped bass, temperatures
should be lowered gradually to 60 F (the metabolic rate of the
fish will be reduced). 3. Know the quality of
the water the fish will be released into at their destination,
the quality of your water should be adjusted slowly to the same
levels (pH, alkalinity, salinity, etc.). 4. The clean water used
for shipping should be held separate from the fish before
packing. Salt is typically added to the water at a rate of 1 to 5
ppt (parts per thousand); that is 0.8 to 4 pounds of salt per 100
gallons or 3.8 to 19 grams per gallon. This reduces
osmatic stress on freshwater fish. 5. Various substances
such as zeolite, activated carbon, and ammonia locking solutions
are also used. 6. Fill shipping bags
1/3 full with the pretreated water and gently place fish into the
bags. 7. Compress the bag to
remove all air and refill with pure oxygen. The typical ratio is
1/3 water 2/3 oxygen. 8. Seal the bags with
rubber bands. 9. Place the bags in
insulated containers and add heat or cool packs to maintain
temperature. Table of
Equivalents To convert units
appearing in Column 1 (left column) into equivalent values in
Column 2 (center column), multiply by factor in Column 3. 
Example: To convert 7 feet into meters multiply 7 x .3048 = 2.13
meters.  To convert units appearing in Column 2 (center)
into equivalent values of units in Column 1 (left), divide by
factor in Column 3. Example: To convert 25 horsepower into BTU
per minute, divide 25 by 0.02356 = 1061. **From
        To**
        **To
        From**
        **Multiply By
        Divide By**BTU
        per Hour Watts
        BTU per Minute
        Centimeters
        Cubic Feet
        Feet
          Feet
        Feet of Water
        Gallons (U.S.) 
        Gallons of Water
        Horsepower
        Horsepower
        Inches
        In/Mer. (Hg)
        Inches of Water
        Liters
        Liters
        Micron
        Miles (Statute)
        Ounces (Weight)
        Pints (Liquid)
        Pounds
        Pounds
        PSI (Lbs./Sq. Inch)
        PSI (Lbs./Inch)
        Quarts
        Temp.(F-32)
        Tons (U.S.)
        Watts
        -----------------
        Horsepower
        Inches
        Gallons (U.S.)
        Meters
            Miles
              PSI (Lbs./Sq. Inch)
              Cubic Feet
              Pounds of Water
              Ft-Pounds/Min.
            Watts
              Centimeters
              PSI (Lbs./Sq. Inch)
              PSI (Lbs./Sq. Inch) 
              Cubic Centimeters
            Gallons (U.S.) 
              Inches
              Feet
              Pounds
              Quarts (Liquid)
            Grams
              Ounces
              Feet of Water
              In/Mer. (Hg) 
              Gallons (U.S.)
            Temperature (C)
              Pounds
              Horsepower
        0.2931
        0.02356
        0.3937
        7.48052
        0.3048
            0.0001894
              0.4335
              0.1337
              8.3453
              33,000
            745.7
              2.54
              0.4912
              0.03613
              1000
            0.2642
              0.00004
              5280
              0.0625
              0.5
            453.59
              16
              2.307
              2.036
              0.25
            0.5555
              2000
              0.001341
 Storage and
Care of pH Electrodes Proper handling and
storage of your pH electrodes can not only help in prolonging the
life of your electrode, but also ensure fast, accurate readings.
General guidelines include: 1. Electrodes should be
rinsed between samples with deionized or distilled water. 2. Never wipe an
electrode dry, this can cause erroneous readings due to static
charges. 3. Never store your
electrodes in water, doing so will cause a sluggish response. 4. Always keep the tip
of your pH electrode moist. Electrode storage solution is a
solution of 4m KCL. If unavailable, a pH4 buffer solution will
also work temporarily. 5. In general, pH
buffers only have a two year shelf life unopened. Once opened,
the shelf life drops to 
2-3 months, pH 10 buffer solution only as a 30 day shelf life
once opened. Float
Switches Automatic float
switches can burn out motors if they cycle too frequently. Pumps
should not be started and stopped every few minutes. The switches
will wear out prematurely and the motor can overheat. Never let
cascading water or wave action cause a float switch to bounce
because this will quickly burn out the motor. Design your sump
large enough (or your pump small enough) so that your pump does
not turn on more than once every five minutes. Water Pumps With the variety of
water pumps available today, selecting the ideal model for your
application can be tricky. The following are a few useful
definitions, helpful hints to aid you in your decision: Centrifugal Pump:
Medium to moderate pressure, flooded suction or self priming
pump. An impeller is used to "sling" water to the
outside, pumping by centrifugal force. Check Valves:
Installed on pump outlet to prevent back siphoning when off. Flooded Suction:
Water must enter pump by gravity. Foot Valve:
Installed on a pump inlet to prevent the loss of prime during
nonoperational periods. Freshwater Pumps:
Freshwater pumps can be used with salt water for brief periods
and experience only minimal corrosion. Be sure to rinse with
fresh water after use. Head: The amount
of pressure that a pump must work against during operation. Total
head equals feet of vertical lift plus friction. The amount of
head is an important value when sizing a pump correctly. One psi
equals 27 inches of water. Friction: The
loss in pressure and volume that occurs when liquids travel
through pipes, fittings and other restrictive elements of a
piping system. GPM: U.S.
gallons per minute. Pedestal Pump: A
self-supporting pump mounted above a long shaft with the motor
above water and the intake below the water level. Pressure Curves:
Motor overload can occur if pumps are operated below the lowest
pressures depicted by the curves shown in the pumps
specifications. If your application does not have sufficient head
pressure to stay within the curve you should throttle the outlet
with a valve or other restriction. Use an amp meter for guidance. Propeller Pump:
A submersible pump with a propeller which draws water through a
housing. Propeller pumps are usually high volume low head. Saltwater Compatible:
Salt water compatible pumps are rated for long-term continuous
duty with salt water. Little corrosion should occur within 1
year. Spherical Pump:
A silent pump that has only one moving part -- an induction
driven impeller. Spherical pumps have no motor shaft, seals or
bearings, making them virtually maintenance free. Trash Pump: A
centrifugal pump that can pass large objects, including sand,
gravel and mud. Often used for dewatering ponds. Vertical Pump: A
centrifugal pump mounted in a vertical direction. Vertical pumps
usually have a long shaft with the motor mounted above water.  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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