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Ashland NFWCO
 Midwest Region
 Dedicated To The Tribal Aquaculture ProgramImage of fish jumping.
    March
        2003-Volume 43
**Administrative
        Coordinator:
        Frank G. Stone 
        (715-682-6185) Ext.
        202
        U.S. Fish and
        Wildlife Service
        Email: 
        [email protected]**
      **Edited
        By:
        Elizabeth W. Greiff 
        (715-349-2195) Ext. 141
        St. Croix Tribal Nat. Res. Depart.
        Email:**
      **[email protected]** Topics
Of Interest: AquaMats Pond
Fertilizing Procedure Used At The Lac du Flambeau Indian
Reservation Pond Fertilizing
Procedure Used At The St. Croix Indian Reservation Pond Fertilizing
Procedure Used At The Leech Lake Indian Reservation Fertilization
Procedures for Pond Culture Pond Management
Tips  AquaMatsBy:  Jamie Ennis,
Meridian Aquatic Technology, LLC, 301-937-1240 ...
  "By combining the natural habitat, food production, and biofiltration
  functions of natural seagrass beds and coral reefs, the developers of AquaMats
  are revolutionizing aquaculture by bringing these natural environmental
  conditions into the commercial rearing of fish and other aquatic animals and
  showing remarkable successes in doing so." 
 By definition, aquaculture is the
reproduction and manipulation of an aquatic environment in order that it may
sufficiently support a given species.   The idea seems simple enough; give those slippery little babies water to
swim in, food to eat and a fair ratio of girls to boys and poof youve got
aquaculture, right?  Well,
commercial production of aquatic animals either for consumption or restocking
programs is infinitely more complicated than a dictionary could ever attempt to
describe.  Mutating diseases,
carrying capacities, food conversion ratios, biosecurity, and genetic diversity
all sound like Sci-Fi titles but are very much a part of everyday operation of
todays aquaculture facilities.   And
as with most things in the 21st century, technology has been there to
answer the call when problems arise.  Ozone
for all the creepy crawlies you cant see, water quality monitors that will
page you at the bowling alley should your pH drop, not to mention 47,975 types
of equipment to make sure the dissolved oxygen is just right; all there at the
touch of a button for your convenience.  However, for all its advances, technology has yet to
eliminate the presence of disease or discover the perfect diet or for that
matter be able to keep up with half the problems our fish seem to come up with
everyday.  But maybe thats the
point.  Maybe, just maybe, a
patchwork of solutions isnt the way around these problems. Perhaps
there are lessons we can learn from nature that could be applied in a modern
aquaculture faculty to produce a more self-sustaining environment rather than
one that needs constant maintenance.Perhaps we can learn to stop banging our heads against
the wall rather than taking aspirin for the pain. Natural
Rearing Natural Rearing is a method of
looking at an animals natural habitat and attempting to reproduce that
environment as best as you can in order to make that animal happier and
ultimately healthier.Why in the
world should Joe Fishfarmer care about his fish being happy?Because a happy fish grows faster, grows bigger, has superior Food
Conversion Ratios (FCRs), is considerably less susceptible to disease and will
never know what an eroded dorsal fin feels like.Make a list of the things that fish have access to in the wild and
youll see there is a lot more on that list than clean water and pellet food. In aquaculture, the most common
application of Natural Rearing is installing structure or habitat of some sort
in the ponds and rearing tanks.Everything
from Christmas trees to military surplus is used as fish habitat and that lesson
has begun to filter down to aquaculture.It
seems when structure is installed in what would otherwise be a barren raceway or
pond, the fish congregate around the structures for food and shelter.Unfortunately, put a pile of cinderblock and two-by-fours in the middle
of your raceway and you may encounter a few logistical hurdles that need to be
overcome.From that seemingly
obvious lesson spawned an entire market of manufactured structures known as
AquaMats.By combining the
natural habitat, food production, and biofiltration functions of natural
seagrass beds and coral reefs, the developers of AquaMats are revolutionizing
aquaculture by bringing these natural environmental conditions into the
commercial rearing of fish and other aquatic animals and showing remarkable
successes in doing so. Working Within
The Food Chain The idea of using habitat in
tanks and ponds is certainly nothing new.The innovations that AquaMats have brought to aquaculture and
commercial biofiltration are their ability to reproduce and support a natural
balance in environments that are nothing like nature.At first glace, these structures dont look like much more then
shredded plastic bags floating with the current, but upon closer inspection the
genius of this technology becomes apparent.The surfaces of these structures are designed and manufactured
specifically to grow periphyton, a collection of benthic algae and bacteria,
which attaches and grows on submerged surfaces.Just like trees that filter carbon dioxide and produce oxygen, the
periphytic community metabolizes toxic by-products like ammonia, nitrites, heavy
metals and other problematic nutrients into non-toxic forms, which are then
available for the plants to use for growth. The more places you offer for
periphyton to grow, the more periphyton youll produce.  The more periphyton
you have, the more of a biofiltration capacity your system will have.This is not a new concept; every mechanical/biofilter ever produced runs
on this simple concept of surface area dictating biological uptake and
conversion.But what makes an
AquaMat unique is that the actual biofiltration is only part of the
picture.You see periphyton is also
a very valuable food resource to herbivorous and omnivorous fish as is the
zooplankton, copepods and countless other animals that are produced as a result
of this community.By introducing
surface area you close the loop on the food chain.In essence, waste from the fish becomes fertilizer for primary production
and eventually fish biomass rather than washing out of the effluent.If fact, AquaMats have proven to be such effective filtration units
that they alone are designed to provide biofiltration to zero exchange
aquaculture systems as well as remediation in the municipal and industrial
wastewater industries.The concept
is simple; by adding AquaMats you give your water and its inhabitants the
ability to reach a balance.Instead
of trying to manipulate and control all the aspects of the environment, you give
it the tools so that it establishes and maintains a balance, which is after all
what nature does.And for your
troubles, the system produces healthier fish, which ultimately leads to a
healthier bottom line. Oh Give Me A
Home So now we know that AquaMats
produce cleaner water through natural filtration, which has the benefit of also
being an excellent supplementary food source.  Still thats only half the
story.Extensive studies on natural
rearing and on AquaMats specifically continue to show the value habitat offers
to aquaculture.When structure is
provided, measurable differences in Cortisol, an indicator of stress, has been
shown. This reduction in stress has been attributed to higher survival despite
double and triple stocking densities, near elimination of Dorsal Fin Erosion,
notable resistance to various diseases such as Bacterial Kidney Disease (BKD)
and increased growth rates, which produce fish that grow faster and are
harvested larger. Another benefit to Natural
Rearing techniques is using habitat to train behavior in the animals in an
environment that is more like what they would encounter in the wild.One of the biggest problems faced by hatchery managers involved in
release programs is that fisherman often complain that the fish are too easy to
catch.  Most monitoring groups record post-release survival of hatchery raised
animals at dismal estimates.And it
makes sense doesnt it?A fish
raised without the benefit of habitat doesnt know how to hide from a predator
or forage for food or even hunt for that matter.So why would we assume that an animal, even one as driven by instinct as
a fish, could adapt to a completely new environment quickly enough to survive in
it. By
offering structure like AquaMats, survival is increased not only in the
facility but in the wild due to predator avoidance and the behavior
traits learned in the presence of habitat during rearing. By combining these aspects of
food production, biofiltration and habitat management, AquaMats are changing
the face of aquaculture for the future.But
more than the technology itself, they represent a profound understanding that is
occurring in this industry.It is
human nature to try to manipulate our environment to our benefit.But what we are slowly learning is that nature has already answered most
of the questions we seek and by incorporating the natural functions of the
environment in the things we do, it is much easier for us to achieve those
benefits.Natural Rearing is just
one more step towards a sustainable industry but moreover, it is a step closer
to understanding the world around us and the lessons it has to offer.  Selected
Case Studies University
of Miami,Rosenstiel School of Marine and Astmospheric Science The
University of Miami in cooperation with the Aquaculture Center of the Florida
Keys, a commercial fish hatchery, are currently conducting research on the use
of AquaMats in mesocosm systems for the semi-intensive husbandry of mutton
snapper (Lutjanus analis).Each
system was fitted with AquaMats to reduce levels of NH4 and act as
a natural habitat for larvae and organisms in with the mesocosm.Preliminary results indicate rates of growth and development of L. analis
is faster in outdoor mesocosms containing AquaMats than indoor intensive
systems.In fact, first year
results marked a 30% growth rate increase and the average weight of the fish
improved 25%. Bozeman
Fish Technology Research Center, US Fish and Wildlife, Bozeman, Montana The
Bozeman Fish Technology Research Center has conducted research studies
implementing AquaMatstechnology since 1997.Research has focused on the use of AquaMatsto provide natural habitat for trout
species to reduce the stress of raceway culture operations and to increase
survival of fish released into the wild. Results during 1997 included a 15%
increase in survival of trout species reared with AquaMatsin raceway trials and marked improvement in
the dorsal fin index (DFI) values, which rose from 2.9 in controls to 8.3 in
AquaMats raceways.(DFI is an
indicator of stress as measured by dorsal fin erosion.A DFI of 10 is considered ideal.)Additionally,
the average weight gain of fish in the AquaMatsraceways was 11% greater than
controls.During 1998, trials
indicated that AquaMats raceways experienced far-reduced vulnerability to
bacterial kidney disease (BKD), with BKD appearing with 80% less frequency in
raceways provided with AquaMats.
Trials were also conducted to determine the quantity of structure necessary to
optimize survival in western slope cutthroat and rainbow trout. Montana Warm
Water Fish Hatchery, Montana Department of Fish, Wildlife and Parks,
Miles City, Montana Extensive
field trials were conducted during the 1997, 1998 and the 1999 growing seasons
to optimize the use of AquaMatswith five different species of warm water game fish, including walleye,
largemouth bass, smallmouth bass, northern pike, and sturgeon. Average survivals
for walleye with use of AquaMats have increased 40% over the past three years
as compared with controls in ponds ranging from 0.5 to 3.0 acres in size. The
culture work was conducted exclusively with live feeds generated in ponds,
either with or without AquaMats.
Fertilizer use has been reduced by 70% in AquaMats ponds (compared against
controls) and fish stocking populations have been simultaneously increased by
33% over the three year period.During
its work with AquaMats,
the Miles City facility has become the largest walleye hatchery in the US,
handling 158 million eggs in 1999.
In
addition to pond trials with fish, the Miles City facility relies on AquaMatsfor Flow Control as a filter field to reduce
the sediment load of in-coming water for their 52-acre facility.AquaMatsfor Flow Control reduced the average sediment load by 62% during the first year
of operations.This reduction of
incoming sediment load had the beneficial effects of vastly reducing the acreage
devoted by the facility to settlement functions and also reduced operational
costs. North Carolina State/Smithfield Foods Inc. (commercial biofiltration
application) Effective and low-cost treatment
of farm waste is a significant and important challenge for our nation.Smithfield Foods, Inc., in cooperation with North Carlonia State and
industry partners specializing in wastewater treatment, has worked aggressively
to meet this national challenge.
Like many commercial farm operations, the Smithfield Foods
site in Duplin County has relied principally on anaerobic pits for treatment of
a combined waste stream of solid and liquid waste.  Their objective was
to receive water from an existing anaerobic pit (to include recycled liquid used
to flush barns) and treat that water in an aerobic lagoon to (1) reduce ammonia
and VOC levels of discharge water (2) reduce nitrogen loads for land application
of effluent (3) reduce concentrations of Phosphorus and other metals in effluent
and (4) reduce noxious odors.  Pond
Fertilizing Procedure Used At The Lac du Flambeau Indian
ReservationBy:  Larry Wawronowicz (Natural Resource
Director) The ponds are partially filled approximately 4 weeks before
the walleye fry are stocked. Initially, the ponds are fertilized and filled to
one third the pond volume.This
allows the water to warm up faster which speeds up the establishment of
zooplankton.Surface water from
Pokegama Lake is used to fill the ponds, which is the same water source used to
hatch walleye eggs.We are able to
observe the zooplankton in the unfiltered hatchery water.When the zooplankton is observed, the water from the lake is again pumped
to capitalize on the plankton present in the lake water.An additional one third of the volume is filled when we first see the
plankton in the hatchery water and the final one third is added when walleye
eggs start to hatch. The amount of fertilizer used largely depends on pond
fertility, weather conditions, number and size of the fish and the quality and
quantity of the zooplankton population.Generally,
we apply a total of 1,171 lb/acre of alfalfa meal and 115 lb/acre of Torula yeast.The fertilization program usually begins by applying approximately  the
total amount of fertilizer required when the pond is first filled, and
subsequent applications are weekly. Each weekly application is about 1/8 of the
total amount of fertilizer required during the production season. See the Table
below. Table: Application rate
          lb/acre of Alfalfa meal and Torulas yeast during the production
          season.1st
      2nd
      3rd
      4th
      5th
      TotalAlfalfa
        Meal
      587
      146
      146
      146
      146
      1,171Torulas
        Yeast
      59
      14
      14
      14
      14
      115Total
      646
      160
      160
      160
      160
      1,286
 For more detail see Wawronowicz, L. J., and W. G. Allen. 1996. Walleye fingerling
production techniques in drainable ponds on the Lac du Flambeau Indian
Reservation. Pages 111-113 in R. C. Summerfelt, editor. Walleye culture manual.
NCRAC Culture Series 101. North Central Regional Aquaculture Center Publications
Office, Iowa State University, Ames.  Pond
Fertilizing Procedure Used At The St. Croix Indian
ReservationBy:  Donald
Taylor, Field Supervisor, St.
Croix Reservation Here
is a brief overview of how we fertilize our natural (undrainable) walleye ponds.As a general rule, we would like to fertilize our ponds at
least two weeks before the fry are stocked, which allows for a spike in
zooplankton numbers. But, our department has a small staff and the spring is
very busy with incubation and spring walleye assessments.As a result we generally don't have time to fertilize.We may still fertilize if after fry stocking we notice that the ponds are
clear and plankton samples show low numbers. Our
natural ponds are surrounded by agriculture fields and normal run-off brings
ample amounts of nitrogen and phosphorus into the ponds.Looking back in our records, we really could not find any correlation
between harvest numbers and fertilizing.There
were times when we did not fertilize and had good harvest numbers and there were
other times when we did fertilize but harvest numbers were below average.Also, we had heavy algae blooms in years when we did not fertilize, yet
no algae blooms when we did fertilize. When
we do fertilize we use "Arco" alfalfa meal and "Diamond V"
yeast, both come in 50 lb bags.We
try to use 100-lbs/surface acre of both types.The procedure is relatively easy, in that we open the bags and spread the
fertilizer out evenly over the coverage area using a Jon boat.What we do not want is to have the fertilizer "clump" out and
then rest on the bottom of the pond.We
try to have the entire water column receive the fertilizer. Besides
fertilizing, what we really try to do is collect zooplankton and stock them into
the ponds.We go to the local wastewater treatment plants and
get permission to collect the zooplankton.On good days,
a person can collect huge amounts of all sizes of zooplankton. Collecting
them involves chest waders, a plankton dipnet, gauntlet gloves, and 5-gallon
buckets.We haul the zooplankton in
our distribution truck, but you may use the buckets with lids.We also bring a small pressure sprayer filled with a chlorine mixture to
sterilize everything down after each use. If
timed correctly, the transfer of zooplankton 
could be a savior to the walleye fry. Our
natural ponds are controlled by elements beyond our control, which fortunately
have usually worked to our benefit.In
the past we measured specific water quality parameters, but limited time,
manpower, and funding have led us to stop measuring.  Pond Fertilizing Procedure Used At The Leech
Lake Indian ReservationBy: John Ringle, Fish & Wildlife
Director, Leech Lake Reservation Introduction The Leech Lake Tribal Fish Hatchery was first
constructed in 1984 and expanded just two years later in 1986. This 25,000
square foot indoor complex contains rearing tank space in addition to an 80 jar
egg incubation battery. Due to increasing production needs, construction began
on a 10 acre drainable pond complex in 1993. This state of the art hatchery
facility has a total capacity of about 1,500 quarts of eggs and indoor rearing
space for about 400,000 whitefish fingerlings. Once the outdoor pond complex was
completed, an additional 500,000 fingerling are were able to be reared. In
addition, this program uses some of the small natural lakes on the reservation,
as well as some natural rearing ponds on the White Earth Reservation, to
cooperatively rear walleye fingerlings. Annual fish production is 8 to 10 million walleye
fry, 50,000 walleye fingerlings, 400,000 lake whitefish fingerlings, and when
the need arises, trout, bass, cisco, and panfish are also produced. In addition,
upwards of 20,000,000 white sucker eggs are collected annually. These eggs are
incubated, hatched and sold to bait growers who in turn rear and sell them as
fishing bait. All of the game fish are stocked back into lakes
and streams on the reservation for tribal subsistence harvest as well as tribal
and non-tribal recreational fishing. Whitefish support a tribal commercial
fishery and other nongame fish species are also commercially harvested by tribal
members. A commercial bait harvest industry, regulated by the Leech Lake Band of
Ojibwe also exists. Pond Fertilization protocol for a 1 acre
walleye pond: Ten days prior to stocking add 500 pounds of
    alfalfa meal
    and 50 pounds of brewers yeast.
    After initial fry stocking: This is followed by weekly applications of
    alfalfa meal (50 pounds)
    and 5 pounds of brewers yeast.  Fertilization
Procedures for Pond Culture in Ohio PondsBy: David Culver, Department of Zoology, The Ohio State University The following is an excerpt that was reprinted from the Walleye Culture Manual,
NCRAC Culture Series 101 A number of walleye and saugeye production
problems have been addressed using limnological strategies. Four of these
problems are highlighted below, along with the means for their solution. 1) Maintaining an adequate abundance of copepods
and cladocerans for fish growth and survival: We encouraged growth of small
algae (diatoms, coccoid greens, flagellates) for growth using liquid inorganic
fertilizers once per week to achieve an inorganic N:P ratio of 20:1 by weight.
The ratio began changing immediately upon fertilization, but we restored it to
20:1 once per week. We stocked fish at 4-5 d of age and filled ponds at the same
time using reservoir water. High densities (over 50/L) of zooplankton were not
necessary to provide adequate food for fry at stocking. Walleye consumption per
day per fish was very low initially and increased exponentially with time. The
zooplankton bloom grew along with the walleye's appetite, and we avoided
overgrazing by Daphnia by stocking sufficient fish to prevent overabundance of
Daphnia in week 4 or 5. 2) Avoiding high ammonia concentrations in the
ponds, especially during the clearwater phase during week 4 or 5: We measured
nutrients in ponds once a week and fertilized up to a target inorganic P
concentration and N:P ratio, rather than using one fixed fertilizer amount. 3) Avoiding low oxygen concentrations: We used no
organic fertilizers. For each unit of photosynthetically-produced biomass, one
unit of oxygen is released to the water; for each unit of heterotrophically
produced biomass, one unit of oxygen is consumed. 4) Avoiding large filamentous green and
blue-green algae: We maintained a low phosphate concentration, favoring those
algae (mostly small species) whose phosphate uptake mechanisms become saturated
at low concentrations. Addition of large amounts of fertilizer at one time,
especially when ponds are filled, favored large filamentous phosphorus storers,
so we fertilized often with small amounts of N and P. We restored the N:P ratio
in the pond to 20:1 once per week to minimize growth of nitrogen-fixing
filamentous blue-greens. Also, we found many filamentous greens and blue-greens
grew heterotrophically on the bottom of the pond, especially in those ponds to
which organic fertilizers such as alfalfa meal had been added. When ponds
cleared up, these algae were still rich with phosphorus from the sediments and
were able to photosynthesize sufficiently to produce oxygen bubbles, which
caused them to float up to surface just when we wanted to harvest fish.  After a suitable
fertilization regimen was identified, we adjusted the density of stocked fish to
obtain the optimum trade-off among zooplankton abundance, fish size, and numbers
produced. Fertilization of the ponds We use liquid nitrogen and phosphorus fertilizers
from agricultural suppliers exclusively. For nitrogen fertilization, we use
28:0:0, which is a combination of urea and ammonium nitrate. All hatcheries now
use phosphoric acid (0:54:0) as a phosphorus source. None of the agricultural
fertilizers we have purchased contained exactly the amounts of N and P expected.
Nevertheless, for planning purposes, 28:0:0 fertilizer has about 4 lb N/gal (480
g NIL) (half as urea), and phosphoric acid is about 3.3 lb P/gal (396 g PJL). A
typical 1-1.2 acre pond with no inorganic nitrogen or reactive phosphate will
receive 1.3-1.6 gal of the former and 10 fl oz of the latter. We have also used
10:34:0 liquid fertilizer (ammonium phosphate) plus 28:0:0 to obtain the desired
additions, but the calculations are simpler using phosphoric acid and 28:0:0.
Hatchery staff has reported no difficulties working with concentrated phosphoric
acid, provided care is exercised, and they appreciate the much smaller volumes
that need to be used. Measurements must be accurate. Once the N and P
concentrations of fertilizer and ponds are known, we use them and the volume of
each pond at the current water level to calculate the amounts of N and P
fertilizers to add to each pond that week. As noted above, we only use liquid inorganic
fertilizer. Not only does organic fertilizer contribute to oxygen problems but
it is also not possible to alter the relative amounts of N and P in organic
fertilizer, nor is it possible to know with certainty when or where the N and P
contained in organic fertilizer will be released into the pond. Inorganic
fertilizers are also less expensive than organic fertilizers. Liquid fertilizer is added to the tank of an
agricultural sprayer that is attached to a tractor and diluted with 50 gal of
pond water. Then the solution is sprayed over the surface of the pond as the
tractor travels along the dam. Some practice is required to time tractor speed
to spray the entire contents of the tank in one pass. Measuring out the
fertilizer went quickly using carboys with spigots for dispensing the phosphoric
acid and larger polyethylene tanks with valves for the nitrogen fertilizer. In
practice, the N and P are depleted by the next week in most ponds.  Biological monitoring The progress of the seasonal bloom of algae was
followed with weekly algal counts or more frequent measurements with a Secchi
disk. Secchi transparency can be seen to decrease and then increase as imperfect
evidence of an algal bloom that builds and declines as a result of a zooplankton
bloom that occurred in the ponds. The dynamics of the algae and zooplankton can
also be followed by their indirect effects on water chemistry. For example,
oxygen declined throughout the season as the algae declined. Lower algae
abundance resulted in lower photosynthesis, resulting in lower oxygen
concentration. The pH tends to be high when photosynthesis is high and declines
later in the season.  Analysis of N and
P in the ponds is particularly important, since hatchery managers may see an
increase in Secchi transparency, assume that additional fertilizer was required,
and then overfertilize the ponds. Fish growth is monitored weekly, and the pond
draining is influenced by whether growth exceeds 1 mm/d, apparent condition of
the fish, and whether they are >25mm. Fish are usually harvested when they
are 30-40 mm; larger fish are easier to harvest, as they are less likely to be
pressed against the screens on the kettle by the draining currents. Growth is
affected by stocking density, but it is difficult to follow this through the
season, since survival is not 100% and one cannot know with certainty when
mortality occurred. If we assume that most mortality occurs the first week after
stocking, however, we can compare growth of fish living at different densities
using their abundance at harvest. Walleye and saugeye attained larger size at
harvest densities below 32,000/acre. Above that density, however, fish size at
harvest stays constant up through at least 144,000/acre. These techniques may need to be adjusted for
other locations where lower or higher inorganic carbon content (alkalinity),
warmer or colder water temperatures, or differently shaped ponds might alter the
dynamics of the system. For example, we use lower phosphorus additions in our
deep ponds and in lakes. Still, chemical and biological monitoring of the
production season and high stocking density have successfully decreased the
variability among ponds, while increasing the number and weight of fish produced
per acre.  Pond ManagementTips Pond fertilization is one of many methods of managing your pond to
    increase production. Because the number of fish that can be produced in a
    pond greatly depends on water fertility, fertilization may improve the
    quality of fish growth, if the watershed in which your pond is located is
    poor in natural nutrients. However, while fertilization can benefit your
    pond, improper management can lead to significant problems such as excessive
    aquatic vegetation or oxygen depletion.
  Adequate oxygen can be maintained by removing excess vegetation from the
    water and by keeping pond banks fairly open, allowing wind to circulate the
    water. If heavy snow covers the ice during winter, scraping it clear can let
    sunlight penetrate and stimulate photosynthesis. If you choose to aerate
    your pond, consider a bubbler system rather than one which sprays water into
    the air. A bubbler can circulate the water efficiently, and it's much less
    energy-expensive to pump air than to pump water.
  Excessive growth of aquatic plants and algae are the most frequently
    received complaints from farm pond managers. Controls for nuisance plants
    can be physical, chemical, or biological. For physical control, shallow
    areas of the pond should be deepened by mechanical dredging and the pond
    sides should have 3:1 slopes. Watershed management that avoids leaching from
    fertilized fields, manure or sewage can help minimize algae mats and other
    problems.  Chemical weed control is a seasonal approach which, if done
    properly, can eliminate weeds and still leave the water suitable for other
    uses. Mats of algae, identified by their thick, hair-like appearance, are
    controlled best with copper sulfate. Submerged weeds can be held in check by
    a number of aquatic herbicides. Emergent plants like cattails are easily
    killed by glyphosate herbicides labeled for aquatic use. With any herbicide
    pay very strict attention to the label instructions and
    precautions.
  Fertilization may not necessarily increase the size of individual fish,
    though it can help increase the total poundage.
  Ponds with excessive water flow should not be fertilized. In ponds such as
    these, you are probably wasting time and contributing to nutrient overload,
    or enrichment, in waters downstream from your pond.
  Ponds with extensive areas less than two feet in depth should not be
    fertilized. The addition of nutrients will only worsen the problem with
    overgrowth of aquatic vegetation.
  Ponds that have acidic soils should not be fertilized before proper
    liming. Proper liming allows the phosphorus to be available to the
    phytoplankton and not become bound up on the soil.
  The total hardness of the pond and soil pH should be checked every 3 to 5
    years. If liming is required, apply at the recommended rate and that should
    improve the ability of the pond to develop adequate blooms.
  Ponds that are constantly muddy should not be fertilized. Phytoplankton
    require sunlight for growth and if the pond is constantly muddy, it is most
    likely that insufficient sunlight is penetrating the water to allow proper phytoplankton
    blooms to develop.
  A poor, infrequent fertilization program is worse than no fertilization
    program at all. Infrequent fertilization can result in fluctuations in the
    food chain and, therefore, food that is available to the fish populations.
    Infrequent fertilization can also add to aquatic weed problems.
  Once rooted aquatic vegetation begins to become established in a pond, you
    should not fertilize. The addition of inorganic nutrients at this time will
    only result in worsening the aquatic vegetation problems. **Return
to MTAN selection pageReturn to Ashland NFWCO home pageReturn to Region 3 U.S. Fish and Wildlife Service** 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.
 Last updated: 
		  November 19, 2008
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